Actinobacteria e a Homeostase Intestinal

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Accepted Manuscript
Title: Actinobacteria: a relevant minority for the maintenance
of gut homeostasis
Author: Cecilia Binda Loris Riccardo Lopetuso Gianenrico
Rizzatti Giulia Gibiino Vincenzo Cennamo Antonio
Gasbarrini
PII: S1590-8658(18)30210-X
DOI: https://doi.org/doi:10.1016/j.dld.2018.02.012
Reference: YDLD 3676
To appear in: Digestive and Liver Disease
Received date: 18-10-2017
Revised date: 26-1-2018
Accepted date: 19-2-2018
Please cite this article as: Binda C, Lopetuso LR, Rizzatti G, Gibiino
G, Cennamo V, Gasbarrini A, Actinobacteria: a relevant minority for the
maintenance of gut homeostasis, Digestive and Liver Disease (2018),
https://doi.org/10.1016/j.dld.2018.02.012
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https://doi.org/doi:10.1016/j.dld.2018.02.012
https://doi.org/10.1016/j.dld.2018.02.012
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Title page 
ACTINOBACTERIA: A RELEVANT MINORITY FOR THE MAINTENANCE OF GUT 
HOMEOSTASIS 
 
Cecilia Binda*, Loris Riccardo Lopetuso*, Gianenrico Rizzatti*, Giulia Gibiino*, Vincenzo 
Cennamo^, Antonio Gasbarrini* 
 
* Department of Internal Medicine, Gastroenterology and Hepatology, Catholic University of 
Sacred Heart of Rome, A. Gemelli Hospital - Italy. 
^ Unit of Gastroenterology and Digestive Endoscopy, AUSL Bologna Bellaria-Maggiore Hospital, 
Bologna - Italy 
 
Electronic word count: 4120 
 
Corresponding Author: 
Prof. Antonio Gasbarrini 
Department of Internal Medicine, Gastroenterology Division, 
Catholic University of Rome, Policlinico “A. Gemelli” Hospital 
Largo Gemelli, 8 
00168 Rome (ITALY) 
Phone/fax number: 0039-06-30156018 
E-mail: antonio.gasbarrini@unicatt.it 
 
 
 
 
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Abstract 
Actinobacteria are one the four major phyla of the gut microbiota and, although they represent only 
a small percentage, are pivotal in the maintenance of gut homeostasis. During the last decade many 
studies focused the attention on Actinobacteria, especially on their role both in gastrointestinal and 
systemic diseases and on their possible therapeutic use. In fact, classes of this phylum, especially 
Bifidobacteria, are widely used as probiotic demonstrating beneficial effects in many pathological 
conditions, even if larger in vivo studies are needed to confirm such encouraging results. This 
review aims to explore the current knowledge on their physiological functions and to speculate on 
their possible therapeutic role(s) in gastrointestinal and systemic diseases. 
 
Key words: gut microbiota, Actinobacteria, Bifidobacteria spp, gut homeostasis, dysbiosis, 
probiotic. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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INTRODUCTION 
The gut microbiota is composed by multiple commensal microbial species including 100 trillion 
(10^14) bacteria, quadrillion viruses, fungi, parasites, archeas and yeasts, reaching an overall 
biomass of about 1 kg and more than 3 million of genes [1- 4]. The different gastrointestinal regions 
are characterized by a different bio-compartmentalization with a distinct and stable microbial 
community. This is influenced by the acid environment, the presence of bile and pancreatic 
secretion and the high peristaltic activity in the stomach and small intestine, which do not allow a 
stable bacterial colonization, differently from the colon where bacterial colonization is favored by 
the low redox potential and the slow transit [5, 6]. The majority of microbes forming the human 
microbiota can be assigned to four major phyla: Bacteroidetes, Firmicutes, Proteobacteria and 
Actinobacteria [7, 8]. Firmicutes and Bacteroidetes represent more than 90% of the relative 
abundance of the gut microbiome and their relationship plays a pivotal role in the maintenance of 
gut homeostasis. Actinobacteria and Proteobacteria represent the remaining 10% [7, 8]. 
Mainly oropharyngeal origin aerobic gram-positive bacteria inhabit stomach, duodenum and 
jejunum, whereas coliforms and anaerobic species (such as Bacteroides, Bifidobateria, Clostridia 
and Lactobacilli) are predominant in the ileum and post ileocecal valve, respectively [9, 10]. 
Gut microbiota is involved in many useful functions, such as energy production from nutrient 
biotransformation [11, 12], regulation of lipid metabolism [13], metabolism of vitamins and 
absorption of calcium, magnesium and iron [12, 14, 15], maintenance of the intestinal barrier 
function [16, 17], the development of immune system from the first days of life [18- 23]. 
Many conditions are supposed to be related to quantitative and qualitative changes in gut 
microbiota composition and function, such as inflammatory bowel diseases, celiac disease, irritable 
bowel syndrome (IBS), obesity, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic 
steato-hepatitis (NASH), diabetes, cardiovascular disease, arthritis, psoriasis and psychiatric 
disorders. This gut microbiota impairment is known as dysbiosis [24- 30]. 
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Recently, increasing interest has focused on the phyla of Actinobacteria, especially on 
Bifidobacteria family. The purpose of this review is to explore the crucial role of Actinobacteria in 
the maintenance of gut homeostasis and the critical importance of their future therapeutic 
applications. 
 
ACTINOBACTERIA IN THE GASTROINTESTINAL TRACT 
Actinobacteria are Gram positive, multiple branching rods, non-motile, non-spore-forming and 
anaerobic bacteria [31], that include three main anaerobe families (Bifidobacteria, Propionibacteria 
and Corynebacteria) and an aerobe family (Streptomyces). The most represented in the human gut 
are Bifidobacteria. Interestingly, the complete genome sequences are available for certain 
Bifidobacterial species, like B. adolescents, B. animalis, B. breve, B. bifidum, B. long and B. 
angulatum [31]. 
Many factors can impact on the presence of Actinobacteria in the intestine. Although the relation 
between phylum diversity and delivery is still unclear, studies demonstrated a higher diversity 
within Actinobacteria phylum among children that underwent vaginal delivery [32-37]. In fact, 
phylum diversity within Actinobacteria, (i.e., Bifidobacterium) was significantly lower in infants 
delivered by caesarean section compared to vaginally delivered newborns during the first week of 
life [33 -35], at the age of 1 month [36], and three months [37]. Other studies did not confirm such 
differences or showed a lower effect on Bifidobacteria and Bacteroides colonization at the age of 6 
and 12 month [38, 39]. The lower abundance of Bifidobacteria and Bacteroides in c-section 
delivered infants may be explained with a higher mother consumption of antibiotics before, during 
and after the delivery. Indeed, postnatal use of antibiotic has been associated with decreased 
numbers of Bifidobacterium and Bacteroides and a higher relative abundance of the Clostridium 
leptum [40- 42]. Furthermore, a higher abundance of Bifidobacterium genus has been demonstrated 
in breastfed infants [43]. Interestingly, it has been demonstrated that human milk is rich in 
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substances, like human milk oligosaccharides (HMOs), that may act as probiotics and stimulate the 
growth of Lactobacillus and Bifidobacterium species [44]. 
Weaning causes a further change in microbial composition and Bifidobacteria are no longer the 
dominant group, with the adult microbiotaestablished after the second year of life [45]. During the 
adulthood, the percentage of Actinobacteria remains stable around 8% [46] and constitutes one of 
the prevalent commensal bacterial in the distal small and large intestine [47]. Intriguingly, an Italian 
study on centenarian patients showed a reduction in the total number of anaerobes compared to 
young adults, with a reduction of Bifidobacteria and Bacteroides [48]. These evidences have opened 
new horizons for the concept of “fragile” microbiota that could deeply affect the delicate health 
equilibrium in old patients. 
 
ACTINOBACTERIA AND GUT BARRIER 
Gut barrier is a multi-layer system able to afford a daily exposure to pathogens and external 
environment. It can be divided into a superficial physical barrier constituted by the epithelial cells, 
the tight junctions and the mucus; and a functional barrier represented by gut-associated mucosa 
lymphoid tissue (GALT), peristalsis and antimicrobial substances, able to regulate the 
immunological response to pathogens and tolerance to commensal bacteria [16, 49]. Gut microbiota 
is pivotal in the maintenance of intestinal barrier functions, increasing tight junctions expression, 
regulating mucin biosynthesis and catabolism, providing energy for epithelial cells proliferation and 
stimulating the immune system [17, 49]. In this scenario, Actinobacteria are absolute players in 
maintaining gut barrier homeostasis. 
The production of short chain fatty acids (SCFA), such as acetate, propionate and butyrate, from 
carbohydrate fermentation is crucial for providing energy to epithelial cells turnover and for their 
potent antibacterial activity [16, 17]. In this field, Bifidobacteria have beneficial effects in the 
maintenance of gut barrier thanks to their great production of SCFA [50]. In particular, they 
produce high concentration of acetate that can protect the host from enteropathogenic infections, 
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such as entero-hemorrhagic Escherichia coli and Shigella [51]. Moreover it has been demonstrated 
that Bifidobacteria have a non-negligible production of lactate, which can be metabolized by a 
group of bacteria (“lactate utilizer”) to produce butyrate [52]. In this scenario, in vitro studies 
demonstrated that SCFA, especially butyrate, are correlated with an increased expression of the 
gene MUC2, a mucin glycoprotein that is one of the major component of the mucous layer and thus 
of intestinal barrier [53-55]. The mechanism responsible for the increased production of MUC 
induced by butyrate is not definitely established. Gaudier et al demonstrated that butyrate could 
modify MUC gene expression in goblet cells depending on the energy source available with a 
consequent higher expression of MUC2 in conditions of glucose deprivation when the consumption 
of butyrate by goblet cells is increased [54]. Authors concluded that butyrate metabolism is 
involved not only in mucin synthesis but can play a role also in gene transcription. Another in vitro 
study showed a relationship between SCFA, especially butyrate, the production of prostaglandins 
(PG) by intestinal myofibroblasts and epithelial mucin expression [53]. In fact, SCFA seemed to 
enhance the production of PGE1 in subepithelial myofibroblasts that in turn was able to stimulate 
epithelial mucin expression, probably through the epithelial differentiation induced by cell-to-cell 
contact, extracellular matrix and soluble factors such as transforming growth factor β. Other 
important elements that contribute to the viscoelastic properties of the mucous layer are the Trefoil 
factors (TFFs). These mucin-associated peptides are mainly secreted by goblet cells, are supposed 
to be involved in the mucosal maintenance and repair, and seem to reduce the recruitment of 
inflammatory cells [56, 57]. Moreover, butyrate contributes to the colonic defense barrier by 
increasing the expression of TFFs [58]. In vitro and in vivo studies and in studies showed a possible 
effects of butyrate on the expression of heat shot proteins (HSPs), which contribute to the gut 
barrier homeostasis by suppressing the production of inflammatory modulators [59, 60]. A 
mechanism for the enhancement of HSPs expression has not been already discerned. So far, only 
some hypotheses have been proposed. Indeed, SCFA are able to induce cellular acidification 
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through a non-ionic diffusion that may induce the production of stress kinases and HSPs. Moreover, 
the butyrate seems to inhibit the histone deacetylase, a crucial transcriptional regulator [59]. 
Finally, a possible role of butyrate on intestinal permeability has been assessed in different in vitro 
studies, which demonstrated a butyrate influence on tight junctions expression. Interestingly, these 
effects seem to be concentration-dependent, with a concentration up to 2 mM that can decrease the 
intestinal permeability and a concentration higher than 8 mM that, on the contrary, is able to induce 
an increased permeability [56, 61, 62]. 
 
ACTINOBACTERIA AND METABOLISM 
Human intestine does not possess many of the enzymes involved in the degradation and 
biotransformation of substances introduced with the diet. Indeed, the majority of enzymes engaged 
in energy production is provided by the commensal bacteria, especially located in the colon and 
belonging to the genus Bacteroides, Bifidobacterium, Ruminococcus and Roseburia [63]. In 
particular, the pathways involved include the fermentation of large polysaccharides, 
oligosaccarides, unabsorbed sugars and fibers, that release hydrogen, carbon dioxide and SCFAs, 
the degradation of proteins, the regulation of lipid metabolism through lipoprotein lipase (LPL), and 
the absorption and biosynthesis of vitamin K, B12, iron, calcium and magnesium [13-15, 64-67]. 
Bifidobacteria are able to produce large quantities of acetate, but do not produce propionate and 
butyrate, which are mainly produced by Bacteroides phylium and Clostridium cluster XIVa and IV 
[68, 69]. However, the acetate released by B. longum NCC2705 represents a co-substrate for 
butyrate production [70] that constitutes the main energy source for colonocytes [71]. 
Actinobacteria are also involved in the biodegradation of resistant starch [72 - 74]. Actinobacteria, 
in particular Bifidobacteria, through the glycosyl hydrolases (GHs) hydrolyze the glycosidic bond 
between two or more sugars and cooperate to the breakdown of plant-derived carbohydrate starch 
and polysaccharides, such as FOS, GOS, XOS, inulin or arabinoxilan [75 - 77]. Moreover, 
Bifidobacteria are supposed to be involved in the transformation of linoleic acid (LA) into 
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conjugated linoleic acids (CLA), a group of isomers of LA [78], that have potential health-
promoting properties like anticarcinogenesis, anti-atherosclerosis, anti-diabetes, anti obesity and 
enhancement of immune functions [79]. 
Although it has been largely demonstrated that the diet strongly influences gut microbiota 
composition, the relationship between diet and Actinobacteria is still unclear. In fact, energy 
restrictions, high fiber diet and dietary components such as fructo-oligosaccharides (FOS), galacto-
oligosaccharides (GOS), xylo-oligosaccharides (XOS) are associated to higher microbial diversity 
[80]. While some studies showed that Actinobacteria abundance is positively associated with a 
high-fat diet and negatively associated with fiber intake [81, 82], an opposite association is 
suggested by other studies in which a high concentration of Bifidobacterium spp is positively 
correlated with lean individuals, high consumption of complex carbohydrates, improvement of 
glucose homeostasis, reduction of obesity and inflammation [83 – 86]. A study comparing fecal 
samples of lean and obese women showeddifferent concentration of Bifidobacteria and Clostridium 
coccoides between the two groups. In particular, there was a negative correlation between 
Bifidobacteria and body fat percentage with an inverse correlation with insulin levels and the 
homeostasis model assessment (HOMA) index [83]. However, in this study there was no difference 
in LPS levels between lean and obese subjects and no correlation with body fat percentage, insulin 
levels or HOMA-index. Nevertheless, a study by Cani et al [85] demonstrated that mice fed with an 
high fat diet enriched with prebiotic (fermentable dietary fibre, oligofructose (OFS)) could restore 
their levels of Bifidobacteria, improve glucose tolerance, insulin secretion, and induce an increase 
of proglucagon mRNA precursor. Authors highlighted that all these changes were correlated with a 
reduction of endotoxiemia, suggesting a protective role of Bifidobacteria, while no relationship was 
evident with other bacterial group [85]. Despite the mechanism of action has not been completely 
understood, authors suggested that the product of OFS degradation, the SCFA, could ameliorate the 
gut barrier function both through a direct action on colonic cells and by modulating gut microbiota, 
especially Bifidobacteria [85]. Furthermore, the use of dextrins derived from maize starch is able to 
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stimulate the growth of Actinobacteria and Bacteroidetes in both normal-weight and obese children 
[87], with possible beneficial effect on the production of SCFA. 
A modulation on gut microbiota, and therefore on Actinobacteria phylum, has been shown with the 
diet low in fermentable oligosaccharides, disaccharides and polyols, fructo-oligosaccharides and 
galacto-oligosaccharides (FODMAPs). FODMAPs are small carbohydrate molecules that are 
slowly absorbed in the form of monosaccharides or not absorbed when disaccharides or 
polysaccharides, lasting for a prolonged period into the intestinal lumen [67]. There, FODMAPs 
exert an osmotic action collecting water into the lumen and are fermented by commensal bacteria 
releasing SCFA, dioxide, hydrogen, methane and carbon [88, 89]. A study by McIntosh et al 
compared the impact of high and low FODMAPs diet in IBS patients and demonstrated an 
increased richness of Actinobacteria with a decreased number of Bifidobacteria in the low 
FODMAPs diet group [90]. On the contrary, other studies showed that a low FODMAPs diet could 
lead to a lower abundance in both Bifidobacteria and Actinobacteria because of their FODMAPs 
need for their metabolism [91, 92]. However, not all the patients treated with low FODMAPs 
experienced an improvement of IBS symptoms [90]. This could probably due to different effects of 
diverse Bifidobacteria strains. Recent studies demonstrated that the use of Bifidobacterium infantis 
and Bifidobacterium animalis has beneficial effects on IBS symptoms [93 - 95]. However, all the 
available studies have not examined the microbiome of patients with IBS following the 
reintroduction phase, but only after the end of the strict low-FODMAP diet, which is usually only 
recommended for 2 to 6 weeks. 
 
ACTINOBACTERIA AND IMMUNOLOGICAL FUNCTION 
The gut microbiota plays a pivotal role in the development of immune system and Bifidobacteria, 
are also critical in this field. The stimulation of intraepithelial lymphocytes, the production of 
mucosal immunoglobulins and the promotion of a tolerogenic immune response are the main 
functions exerted by commensal bacteria [19, 20,22, 23, 96]. 
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A decreased number of Bifidobacteria is associated to an enhancement of gut permeability [97] that 
leads to the translocation of LPS into the serum. This triggers the immune system activation and 
sustains chronic inflammatory conditions, such as insulin resistance, diabetes and liver diseases 
[98]. The administration of Bifidobacterium pseudocatenulatum CECT 7765 along with high fat 
diet in mice is able to down-regulate the inflammation by reducing the production of inflammatory 
cytokines and chemokines, especially IL-6 and MCP-1, which are usually increased in obesity and 
metabolic disorders [99]. The reduction of these inflammatory markers is concomitant with the 
improvement of glucose tolerance and with the increasing of IL-4 and IL-13. These cytokines are 
able to stimulate the M2 phenotypic differentiation of macrophages, a subtype of adipose tissue 
macrophages that secretes the anti-inflammatory cytokine IL-10, and to promote the control of 
inflammation and normal insulin sensitivity [100]. However, the same study showed that after the 
administration of B. pseudocatenulatum CECT 7765 there were increased level of IL-10 only in 
standard diet fed mice and not in high fat diet-fed mice, indicating that probably parallel regulatory 
mechanisms are involved. Furthermore, B. pseudocatenulatum CECT 7765 can boost an 
appropriate inflammatory response to a bacterial stimulus (LPS) that is usually impaired in high fat 
diet fed mice. In fact, the administration of this probiotic in these mice stimulates the production of 
TNF-α by LPS-stimulated macrophages, boosts the oxidative burst and therefore the phagocytosis 
function in peritoneal macrophages. Finally, it increases the ability of DCs to present antigens and 
prime a T-lymphocyte proliferative response [99]. In this direction, the reduced phagocytic capacity 
and oxidative burst of macrophages and the impaired function of DCs are possible reasons for the 
increased susceptibility to infections in obese subjects [101, 102]. 
Moreover, Actinobacteria, and mainly Bifidobacteria species, can modulate immune-inflammatory 
and autoimmune response by inducing regulatory T-cells [103, 104]. 
Grounding on the evidence that Bifidobacterium longum subspecies infantis (B.infantis) induces 
regulatory T cells activity in animal models [103, 105 - 108] and increases the relative proportion of 
the same cells in peripheral blood of healthy humans [109], Groeger et al studied the effect of 
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B.infantis inflammatory mediator production in inflammatory disorders in patients with ulcerative 
colitis (UC), psoriasis and chronic fatigue syndrome (CFS) [110]. They found that 6-8 weeks of 
treatment with B.infantis significantly reduced plasma C-reactive protein (CRP) levels in all three 
group of patients, whereas a statistically significant attenuation of TNF-α was observed for psoriasis 
and CFS. In the UC group they observed a trend of reduction in TNF-α levels that however did not 
reach the statistical significance, probably because of the shorter treatment period (6 weeks of 
treatment vs 8 weeks of treatment of the other two groups). Instead, plasma levels of IL-6 were only 
marginally decreased after treatment reinforcing the hypothesis of a specific influence on immune 
response for each gut microbiota component [110]. The use of Bifidobacterium species has also 
been studied in respiratory pathology, alone or in combination with prebiotic or other probiotics like 
Lactobacilllus. In this field, Bifidobacteria seem to be effective to prevent asthma-like symptoms in 
infant with atopic dermatitis and to treat the symptoms of allergic rhinitis [111 – 115]. This is 
probably due to an immunomodulatory effect of Bifidobacteria on Th balance, regulating Th-2 
immunoresponse that is usually skewed in atopic patients and is responsible of higher levels of 
eosinophils and IgE production [113]. 
 
ACTINOBACTERIA AND GUT-BRAIN AXIS 
Recently, the interest on the impact of gut microflora on gut-brain axis is increasing. This could 
involve neuroendocrine, immunological and direct neural mechanisms [116 - 118]. Dysbiosis and 
the consequent increased intestinal permeability are associated to an up-regulation of systemic 
inflammation thatmay also involve the central nervous system [119]. Both the gut microbiota 
production of neurochemicals (i.e., serotonin, SCFA, dopamine and γ-aminobutyric acid) [116, 120] 
and neurotoxic metabolites (i.e., ammonia) [119] by strengthens the possibility of an implication of 
the gut-brain axis in depression, anxiety, IBS, IBD, and neurodevelopmental disorders such as 
autism [116, 121 - 124]. A direct neural communication between the gut and the brain through the 
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stimulation of the enteric nervous system and consequently the vagus nerve has also been supposed 
[125, 126]. 
Standing on previous studies that showed a reduction of Bifidobacteria and lactobacilli following a 
stressful experience and emotional stress both in animals and humans [127 - 131], Desbonnet et al 
conducted a study to assess the potential antidepressant properties of probiotic Bifidobacteria 
infantis in rats [132]. They demonstrated that a two-week treatment with the probiotic 
Bifidobacteria infantis determines an attenuation of pro-inflammatory immune response and an 
elevation of tryptophan, a precursor of serotonine that represents a target of antidepressant 
treatments. Authors concluded that these results might support the beneficial effect of this probiotic 
in the treatment of depression, especially when associated to gastrointestinal disorders. Two years 
later, these findings were supported by the evidence that the chronic treatment with Bifidobacteria 
infantis was able to attenuate depression in the rats exposed to maternal separation stress in early 
life [133]. 
On the other side, a recent study by Lyte at al [134] showed that mice fed with resistant starch (RS) 
had increased levels of Bifidobacteria, according also to a previous study by Tachon et al [135]. 
RS-fed mice evidenced a significant increase in anxiety-like behavior that the authors considered to 
be induced by the same diet with a concomitant abundance of Bifidobacterium [134]. 
Furthermore, a role of Actinobacteria, mainly Bifidobacteria, in the deterioration of cognitive 
function has been supposed. In fact, preliminary data on the use of the probiotic VSL#3, a mixture 
of 8 different strains of bacteria including three Bifidobacteria species, showed an improvement in 
the age-related decrease of long-term potentiation (LTP) in rats [136]. One of the mechanisms 
supposed to be involved in the regulation of LTP is the anti-inflammatory effect of VSL#3 on the 
modulation of the hippocampal molecules expression, such as CD 68 and CD 11b. These are 
markers of microglial activation, and therefore of inflammation. Moreover the authors reported that 
VSL#3 is able to influence the expression of several genes in the cortex. In particular, it is able to 
attenuate the age-related changes in three genes, PLA2G3, Nid2 and Alox15, which are associated 
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to inflammation. Changes of genes expression in the brain may be linked to the variation of several 
molecules induced by VSL#3. In fact, this study showed that this probiotic regulates specific 
mediators involved in synaptic plasticity in the hippocampus of aged rats, especially brain-derived 
neurotrophic factor (BDNF), synapsin and syntaxin. The authors suggested that the synaptotrophic 
effect of VSL#3 is mainly due to the BDNF, whose expression was increased in those rats treated 
with the probiotic. The increase of BDNF levels was associated to higher level of synapsin. Of note, 
previous studies recognized its fundamental role in sustaining LTP through the induction of 
neurogenesis and synaptogenesis [136]. 
Lastly, the existence and the importance of gut-brain axis have also been suggested in alcohol 
dependence. Some alcohol dependent subjects develop a high intestinal permeability that is 
associated with significantly lower levels of Bifidobacteria [137]. These subjects are characterized 
by higher levels of depression, anxiety and craving and have a consistent higher risk of persistence 
of psychological symptoms after detoxification when compared to alcohol dependent subject with a 
lower intestinal permeability, that on the contrary recover completely after the abstinence period. 
 
BIFIDOBACTERIA AS PROBIOTIC 
Bifidobacteria, together with Lactobacilli, represents the cornerstone of probiotic therapeutic 
approach, but only few Bifidobacteria strains have been studied alone. Thus, in the latter cases the 
beneficial effects cannot be exclusively related to this probiotic family. 
For example, the probiotic formulation VSL#3, a mixture of lyophilized four Lactobacilli (L. casei, 
L. plantarium, L acidophilus, L. bulgaricus), three Bifidobacteria strains (B. longuum, B. breve, B. 
infantis) and Streptococcus salivaris subspecies termophilus demonstrated to be effective in several 
conditions. Its efficacy has been mainly assessed in the prevention of pouchitis relapse in patients 
with UC [138, 139], with promising results in maintaining remission and treating mild-to-moderate 
UC both in adult and children [140 - 143], in metabolic disorders, in non-alcoholic steato-hepatitis 
(NASH) [144, 145] and in the prevention of antibiotic-associated diarrhea [146]. An amelioration of 
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the pro-inflammatory status in patients affected by UC has been demonstrated with the use of 
Bifidobacterium infantis alone [110], as mentioned above, and Bifidobacterium breve in association 
with GOS [147]. The use of Bifidobacteria, alone or in association with other probiotics is also 
effective in the alleviation of symptoms in patients with IBS [93 - 95, 148 - 150], constipation [151, 
152] and in the reduction of antibiotic-associated diarrhea in infants [153]. Moreover, a recent study 
showed that a supplementation of B.breve in association with breast feeding is able to reduce the 
incidence of necrotizing enterocolitis (NEC) in preterm neonates born between 28 and 34 weeks of 
gestation. However, further studies are needed for neonates < 28 weeks where the reduction of NEC 
didn’t reach a statistical significance [154]. 
Furthermore, in vitro and murine models studies highlighted how Bifidobacteria, especially B. 
longum and B. lactis strains, seem to be active against rotavirus infection [155] and could protect 
against colorectal cancer (CRC) [156, 157]. Grounding on a previous study where the use of a 
combination of RS and B. lactis had significantly increased the acute apoptotic response to a 
genotoxic carcinogen (AARGC) in rat colon [158], Le Leu et al confirmed his protective action 
against CRC in rats model, supporting the importance of this synbiotic in cancer prevention. The 
mechanism(s) of actions that sustain(s) apoptosis with this symbiotic remain(s) unclear, but authors 
supposed the presence of immunomodulating properties derived by the interaction between B.lactis 
and RS resulting in butyrate production [156]. A recent randomized, double-blind, placebo-
controlled study on humans affected by colorectal polyps (no CRC) or CRC [157] highlighted how 
the dietary symbiotic, B. lactis, L. Rhamnosus and oligofructose-enriched inulin, was able to reduce 
colon cell proliferation and cell DNA-damage. However, the two groups responded differently to 
the synbiotic, maybe because of an increased resistance to qualitative and quantitative changes of 
cancer patients intestinal microflora [157]. 
In addition, the effects of Bifidobacteria are not limited to the gastrointestinal tract. In fact, a 
possible therapeutic role of such probiotic has also been supposed in the treatment of respiratory 
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pathologies [112-115], psoriasis, chronic fatigue syndrome [110], depression [132, 133] and in the 
deterioration of cognitive functions [136]. 
 
CONCLUSIONS 
This review shows how Actinobacteriaphylum, despite it represents a minority group of 
commensal bacteria, plays a pivotal role in the development and maintenance of gut homeostasis 
(Figure 1). Its involvement has been supposed in the modulation of gut permeability, immune 
system, metabolism and gut-brain axis. An unbalanced abundance has been evidenced in several 
pathological conditions. For this reason, the interest in the use of Actinobacteria, especially of 
Bifidobacteria family, as probiotic is constantly increasing. This group may represent a significant 
part of the next-generation of probiotics with a potential efficacy both in gut diseases and extra-
intestinal disorders (Table 1). 
However, further studies are needed to deeply understand the interaction between Actinobacteria 
and the host and consequently their therapeutic implications in the prevention and treatment of 
several systemic disorders with the end goal of promoting gut health. 
 
 
 
 
 
 
 
 
 
 
 
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REFERENCES 
 
1. Mondot S, de Wouters T, Doré J, Lepage P. The human gut microbiome and its dysfunctions. 
Dig Dis 2013; 31(3-4):278-85 
2. Leser TD, Molbach L: Better living through microbial action: the benefits of the mammalian 
gastrointestinal microbiota on the host. Envirol Microbiol 2009; 11:2194-2206 
3. Neish AS. Microbes in gastrointestinal health and disease. Gastroenterology 2009; 136: 65-80. 
4. Lopetuso LR, Ianiro G, Scaldaferri F, Cammarota G, Gasbarrini A. Gut Virome and 
Inflammatory Bowel Disease. Inflamm Bowel Dis 2016;22:1708-12 
5. Donaldson GP, Lee SM, Mazmanian SK. Gut biogeography of the bacterial microbiota. Nat Rev 
Microbiol 2016; 14(1):20-32 
6. Guarner F, Malagelada JR. Gut flora in health and disease. Lancet 2003; 361:512-9 
7. Arumugam M, Raes J, Pelletier E, Le Paslier D, Yamada T, Mende DR et al. Enterotypes of the 
human gut microbiome. Nature 2011; 473: 174-180. 
8. Segata N, Haake SK, Mannon P, Lemon KP, Waldron L, Gevers D et al. Composition of the 
adult digestive tract bacterial microbiome based on seven mouth surfaces, tonsils, throat and 
stool samples. Genome Biol 2012; 13:R42. 
9. D'Aversa F, Tortora A, Ianiro G, Ponziani FR, Annicchiarico BE, Gasbarrini A.Gut microbiota 
and metabolic syndrome. Intern Emerg Med 2013; 8 Suppl1:S11-5 
10. Gallo A, Passaro G, Gasbarrini A, Landolfi R, Montalto M. Modulation of microbiota as 
treatment for intestinal inflammatory disorders: An uptodate. World J Gastroenterol 2016; 
22:7186-202 
11. Round JL, O'Connell RM, Mazmanian SK. Coordination of tolerogenic immuneresponses by 
the commensal microbiota. J Autoimmun 2010; 34:J220-5 
12. Sekirov I, Russel SL, Antunes LC, Finlay BB. Gut microbiota in health and disease. Physiol 
Rev 2010;90:859-904. 
Page 17 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
13. Backhed G, Crawford PA. Coordinated regulation of the metabolome and lipidome at the host-
microbial interface. Biochem Biophys Acta 2010; 1801:240-245 
14. Conly JM, Stein K, Worobetz L, Rutledge-Harding S. The contribution of vitaminK2 
(menaquinones) produced by the intestinal microflora to human nutritional requirements for 
vitamin K. Am J Gastroenterol 1994; 89:915-23 
15. Younes H, Coudray C, Bellanger J, Demigné C, Rayssiguier Y, Rémésy C. Effects of two 
fermentable carbohydrates (inulin and resistant starch) and their combination on calcium and 
magnesium balance in rats. Br J Nutr 2001; 86:479-85 
16. Scaldaferri F, Pizzoferrato M, Gerardi V, Lopetuso L, Gasbarrini A. The gut barrier: new 
acquisition and therapeutic approaches. J Clin Gastroenterol 2012; 46(Suppl):S12-S17. 
17. Purchiaroni F, Tortora A, Gabrielli M, Bertucci F, Gigante G, Ianiro G, OjettiV, Scarpellini E, 
Gasbarrini A. The role of intestinal microbiota and the immune system. Eur Rev Med 
Pharmacol Sci 2013; 17:323-33 
18. Allen CA, Torres AG. Host-microbe communication within the GI tract. Adv Expt Med Biol 
2008;635:93-101. 
19. Maynard CL, Elson CO, Hatton RD, Weaver CT. Reciprocal interactions of theintestinal 
microbiota and immune system. Nature 2012; 489:231-41 
20. Atarashi K, Tanoue T, Oshima K, Suda W, Nagano Y, Nishikawa H et al. Treg induction bya 
rationally selected mixture of Clostridia strains from the human microbiota.Nature 2013; 
500:232-6 
21. Galdean CM, Perdigon G. The probiotic bacterium Lactobacillus casei induces activation of the 
gut mucosal immune system through innate immunity. Colin Vaccine Immunol 2006;13:219-
226. 
22. Sun M, He C, Cong Y, Liu Z. Regulatory immune cells in regulation of intestinal inflammatory 
response to microbiota. Mucosal Immunol 2015; 8:969-78 
Page 18 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
23. McCarville JL, Caminero A, Verdu EF. Novel perspectives on therapeutic modulation of the gut 
microbiota. Therap Adv Gastroenterol 2016; 9:580-93 
24. Sartor RB. Microbial influences in inflammatory bowel disease. Gastroenterology 2008; 
134:577-594. 
25. De Palma G, Blennerhassett P, Lu J, Deng Y, Park AJ, Green W, et al. Microbiota and host 
determinants of behavioural phenotype in maternally separated mice. Nat Commun 2015; 
6:7735 
26. Hill DA, Artis D. Intestinal bacteria and the regulation of immune cell homeostasis. Annu Rev 
Immunol 2010; 28:623-667. 
27. Cox A, West N and Cripps A. Obesity, inflammation, and the gut microbiota. Lancet Diabetes 
Endocrinol 2015; 3:207-215 
28. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, et al. Intestinal 
microbiotametabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 
2013; 19:576-85 
29. Sun J, Furio L, Mecheri R, van der Does AM, Lundeberg E, Saveanu L, et al. Pancreatic β-Cells 
Limit Autoimmune Diabetes via an Immunoregulatory Antimicrobial Peptide Expressed under 
the Influence ofthe Gut Microbiota. Immunity 2015; 43:304-17 
30. Scher JU, Ubeda C, Artacho A, Attur M, Isaac S, Reddy SM, et al. Decreasedbacterial diversity 
characterizes the altered gut microbiota in patients withpsoriatic arthritis, resembling dysbiosis 
in inflammatory bowel disease. Arthritis Rheumatol 2015; 67:128-39. 
31. Belizario JE, Napolitano M. Human microbes and their roles in dysbiosis, common disease, and 
novel therapeutic approaches. Front Microbiol 2015; 6: 1050. 
32. Adlerberth I, Carlsson B, de Man P, Jalil F, Khan SR, Larsson P, Mellander L, Svanborg C, 
Wold AE, Hanson LA. Intestinal colonization with Enterobacteriaceae in Pakistani and Swedish 
hospital-delivered infants. Acta Paediatr Scand. 1991;80(6–7):602–10. 
Page 19 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
33. Hesla HM, Stenius F, Jaderlund L, Nelson R, Engstrand L, Alm J, Dicksved J. Impact of 
lifestyle on the gut microbiota of healthy infants and their mothers - the ALADDIN birth cohort. 
FEMS Microbiol Ecol. 2014;90(3):791–801. 
34. Mitsou EK, Kirtzalidou E, Oikonomou I, Liosis G, Kyriacou A. Fecal microflora of Greek 
healthy neonates. Anaerobe. 2008;14(2):94–101. 
35. Dogra S, Sakwinska O, Soh SE, Ngom-Bru C, Bruck WM, Berger B, Brussow H, Lee YS, Yap 
F, Chong YS et al.: Dynamics of infant gut microbiota are influenced by delivery mode and 
gestational duration and are associated with subsequent adiposity. MBio 2015, 6(1).doi: 
10.1128/mBio.02419-14. 
36. Huurre A, Kalliomaki M, Rautava S, Rinne M, Salminen S, Isolauri E. Mode of delivery - 
Effects on gut microbiota and humoral immunity. Neonatology 2008;93(4):236–40. 
37. Kabeerdoss J, Ferdous S, Balamurugan R, Mechenro J, Vidya R, Santhanam S, Jana AK, 
Ramakrishna BS. Development of the gut microbiota in southern Indian infants from birth to 6 
months: a molecular analysis. J Nutr Sci 2013;2:e18. 
38. Gronlund MM, Lehtonen OP, Eerola E, Kero P. Fecal microflora in healthy 
infants born by different methods of delivery: permanent changes in intestinal flora after 
cesarean delivery. J Pediatr Gastroenterol Nutr. 1999; 28(1):19–25. 
39. Bezirtzoglou E. The intestinal microfloraduring the first weeks of life. Anaerobe. 1997;3(2–
3):173–7. 
40. Yap GC, Chee KK, Hong PY, Lay C, Satria CD, Sumadiono AA, Soenarto Y, Haksari EL, Aw 
M, Shek LPC, et al. Evaluation of stool microbiota signatures in two cohorts of Asian 
(Singapore and Indonesia) newborns at risk of atopy. Bmc Microbiol. 2011;11:193. 
41. Dethlefsen L, Huse S, Sogin ML, Relman DA. The pervasive effects of an antibiotic on the 
human gut microbiota, as revealed by deep 16S rRNA sequencing. PLoS Biol. 2008;6(11):e280. 
Page 20 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
42. Penders J, Thijs C, Vink C, Stelma FF, Snijders B, Kummeling I, van den Brandt PA, 
Stobberingh EE. Factors influencing the composition of the intestinal microbiota in early 
infancy. Pediatrics. 2006;118(2):511–21. 
43. Bezirtzoglou E, Tsiotsias A, Welling GW. Microbiota profile in feces of breast- and formula-fed 
newborns by using fluorescence in situ hybridization (FISH). Anaerobe. 2011;17(6):478–82. 
44. Underwood MA, German JB, Lebrilla CB, Mills DA. Bifidobacterium longum subspecies 
infantis: champion colonizer of the infant gut. Pediatr Res. 2015; 77(1–2):229–35. 
45. Ley RE, Peterson DA, Gordon JI. Ecological and evolutionary forces shaping microbial 
diversity in the human intestine. Cell 2006; 124:837-848. 
46. D’Argenio V, Salvatore F. The role of the gut microbiome in the healthy adult status. Clin Chim 
Acta 2015; 451(PtA):97-102. 
47. Eckburg PB, Bik EM, Bernstein CN, Purdom E, Dethlefsen L, Sargent M, Gill SR, Nelson KE, 
Relman DA. Diversity of the human intestinal microbial flora. Science. 2005; 308:1635-16388. 
48. Drago L, Toscano M, Rodighiero V, De Vecchi E, Mogna G. Cultivable and pyrosequenced 
fecal microflora in centenarians and young subjects. J Clin Gastroenterol 2012;46(suppl):S81-
84. 
49. Ashida H, Ogawa M, Kim M, Mimuro H, Sasakawa C. Bacterial and host interactions in the gut 
epithelial barrier. Nature 2012; 489:231-241. 
50. Hardy H, Harris J, Lyon E, Beal J, Foey AD. Probiotics, prebiotics and immunomodulation of 
gut mucosal defences: homeostasis and immunopathology.Nutrients 2013; 5:1869-912. 
51. Fukuda S, Toh H, Taylor TD, Ohno H, Hattori M. Acetate-producing bifidobacteria protect the 
host from enteropathogenic infection via carbohydrate transporters. Gut Microbes. 2012; 3:449-
54. 
52. Scott KP, Martin JC, Duncan SH, Flint HJ. Prebiotic stimulation of human colonic butyrate-
producing bacteria and bifidobacteria, in vitro. FEMS Microbial Ecol 2014;87:30-40 
Page 21 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
53. Willemsem LE, Koetsier MA, van Deventer SJ et al. Short chain fatty acids stimulate epithelial 
mucin 2 expression through differential effects on prostaglandin E(1) and E(2) production by 
intestinal myofibroblasts. Gut 2003;52:1442-47 
54. Gaudier E, Jarry A, Blottiere HM et al. Butyrate specifically modulates MUC gene expression in 
intestinal epithelial goblet cells deprived of glucose. Am J Physiol Gastrointest Liver Physiol 
2004;287:G1168-74 
55. Gendler SJ,Spicer AP. Epithelial mucin genes. Annu Rev Physiol 1995; 57:607-34 
56. Hamer HM, Jonkers D, Venema K, Vanhoutviny S, Troost FJ.Review article: the role of 
butyrate on colonic function. Aliment Pharmacy There 2008; 27:104-119. 
57. Barrett KE. A new twist on trefoils. Focus on "TFF3 modulates NF-{kappa}B and a novel 
regulatory molecule of NF-{kappa}B in intestinal epithelial cells via a mechanism distinct from 
TNF-{alpha}". Am J Physiol Cell Physiol 2005; 289:C1069-71 
58. Song M, Xia B, Li J. Effects of topical treatment of sodium butyrate and 5-aminosalicylic acid 
on expression of trefoil factor 3, interleukin 1beta, and nuclear factor kappaB in trinitrobenzene 
sulphonic acid induced colitis in rats. Postgrad Med J 2006; 82:130-5 
59. Arvans DL, Vavricka SR, Ren H, et al. Luminal bacterial flora determines physiological 
expression of intestinal epithelial cytoprotective heat shock proteins 25 and 72. Am J Physiol 
Gastrointest Liver Physiol 2005; 288: G696–704 
60. Ren H, Musch MW, Kojima K, et al. Short-chain fatty acids induce intestinal epithelial heat 
shock protein 25 expression in rats and IEC 18 cells. Gastroenterology 2001; 121: 631–9 
61. Peng L, He Z, Chen W, et al. Effects of butyrate on intestinal barrier function in a caco-2 cell 
monolayer model of intestinal barrier. Pediatr Res 2007; 61: 37–41 
62. Mariadason JM, Kilias D, Catto-Smith A, et al. Effect of butyrate on paracellular permeability 
in rat distal colonic mucosa ex vivo. J Gastroenterol Hepa- tol 1999; 14: 873–9 
Page 22 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
63. Davila AM, Blachier F, Gotteland M, Andriamihaja M, Benetti PH, Sanz Y, Tomé D. Intestinal 
luminal nitrogen metabolism: Role of the gut microbiota and consequences for the host. 
Pharmacol Res 2012; 68:95-107. 
64. Bernalier-Donadille A. Fermentative metabolism by the human gut microbiota. Gastroenterol 
Clin Biol 2010; 34 Suppl 1:S16-22 
65. CummingsJand MacfarlaneG. The control and consequences of bacterial fermentation in the 
human colon. J. Appl Microbiol 1991; 70:443–459 
66. Hamer HM, De Preter V, Windey Kand Verbeke K. Functional analysis of colonic bacterial 
metabolism: relevant to health? Am J Physiol Gastrointest Liver Physiol 2012; 302, G1–9. 
67. Ponziani FR, Binda C, Gasbarrini A. How to modulate gut microbiota:diet, pre-probiotic or 
antibiotics? Minerva Gastroenterol Dietol 2017; 8:1026-1025. 
68. Bindels LB, Delzenne NM, Cani PD, Walter J. Towards a more comprehensive concept for 
prebiotics. Nat Rev Gastroenterol Hepatol 2015; 12:303-310. 
69. O’Callaghan A, van Sinderen D. Bifidobacteria and their role as members of the human gut 
microbiota. Front Microbiol 2016; 7:925. 
70. Rivière A, Gagnon M, Weckx S, Roy D, De Vuyst L. Mutual cross-feeding interactions between 
Bifidobacterium longum NCC2705 and eubacterium rectale ATCC336656 explain the 
bifidogenic and butyrogenic effects of arabinoxylan-oligosaccharides. Appl Environ Microbiol 
2015; 80:204-217. 
71. Clausen MR, Mortensen PB: Kinetic studies on colonocyte metabolism of short chain fatty acids 
and glucose in ulcerative colitis. Gut 1995; 37:684-689. 
72. Macfarlane GT, Englyst HN. Starch utilization by the human large intestinal microflora. J Appl 
Bacteriol 1986;60:195–201. 
73. Ryan SM, Fitzgerald GF, van Sinderen D. Screening for and identification of starch-, 
amylopectin-, and pullulan-degrading activities in bifidobacterial strains. Appl Environ 
Microbiol. 2006;72(8):5289–96. 
Page 23 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
74. Salyers AA, West SE, Vercellotti JR, Wilkins TD. Fermentation of mucins and plant 
polysaccharides by anaerobic bacteria from the human colon. Appl Environ Microbiol. 
1977;34(5):529–33. 
75. Pokusaeva K, Fitzgerald GF and Van Sinderen D. Carbohydrate metabolism in Bifidobacteria. 
Genes Nutr 2011; 6:285-306. 
76. El Kaoutari A, Armougom F, Gordon JI, Raoult D, Henrissat B. The abundance and variety of 
carbohydrate-active enzymes in the human gut microbiota. Nat Rev Microbol 2013; 11:497-504. 
77. Milani C, Lugli AG, Duranti S, Turroni F, Mancabelli L, Ferrario C et al. Bifidobacteria exhibit 
social behaviour through carbohydrate resource sharing in the gut. Sci Rep 2015; 5:15782. 
78. Raimondi S, Amaretti A, Leonardi L, Quartieri A, Gozzoli C, Rossi M. Conjugated linoileic 
acid production by Bifidobacteria: screening, kinetic, and composition. Biomed Res Int 2016; 
2016:8654317. 
79. Kim JH, Kim Y, Kim YJ, Park Y. Conjugated linoleic acids: potential health benefits as a 
functional food ingredient. Annu Rev Food and Sci Techol 2016; 7:221-244. 
80. Cotillard A, Kennedy SP, Kong LC, Prifti E, Pons N, Le Chatelier E et al. Dietary intervention 
impact on gut microbial gene richness. Nature 2013; 500:585-8 
81. TurnbaughPJ, BäckhedF, FultonLand Gordon JI. Diet-induced obesity is linked to marked but 
reversible alterations in the mouse distalgut microbiome. Cell Host Microbe 2008; 3:213–223 
82. Wu GD, Chen J, Hoffmann C, Bittinger K, Chen YY, Keilbaugh SA, Bewtra M, Knights D, 
Walters WA, Knight R, et al. Linking long-term dietary patterns with gutmicrobial enterotypes. 
Science 2011; 334:105–108. 
83. Teixeira TFS, Grze_skowiak ŁM, Salminen S, Laitinen K, Bressan J, Gouveia Peluzio Mdo C. 
Faecal levels of Bifidobacterium and Clostridium coccoides but not plasma lipopolysaccharide 
are inversely related to insulin andHOMA index in women. Clin Nutr 2013; 32:1017–1022. 
Page 24 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
84. Zimmer J, Lange B, Frick JS, Sauer H, Zimmermann K, Schwiertz A, Rusch K, et al. A vegan 
or vegetarian diet substantially alters the human colonic faecal microbiota. Eur J Clin Nutr 2012; 
66:53–60. 
85. Cani PD, Neyrinck AM, Fava F, Knauf C, Burcelin RG, Tuohy KM, Gibson GR, Delzenne NM. 
Selective increases of bifidobacteria in gut microflora improve high-fat-diet-induced diabetes in 
mice through a mechanism associated with endotoxaemia. Diabetologia 2007; 50:2374–2383. 
86. Geurts L, Neyrinck AM, Delzenne NM, Knauf C, Cani PD. Gut microbiota controls adipose 
tissue expansion, gut barrier and glucose metabolism: novel insights into molecular targets and 
interventions using prebiotics. Benef Microbes 2014; 5:3–17. 
87. Barczynska R, Kapusniak J, Litwin M, Slizewska K, Szalecky M. Dextrins from maize starch as 
substances activating the growth of Bacteroidetes and Actinobacteria simultaneosly inhibiting 
the growth of Firmicutes, responsible for the occurrence of obesity. Plant Foods Hum Nutr 
2016; 71:190-196. 
88. Barrett JS, Gearry RB, Muir JG, Irving PM, Rose R, Rosella O, et al. Dietary poorly absorbed, 
short-chain carbohydrates increase delivery of water and fermentable substrates to the proximal 
colon. Aliment Pharmacol Ther. 2010;31:874-82 
89. De Giorgio R, Volta U, Gibson PR. Sensitivity to wheat, gluten and FODMAPs in IBS: facts or 
fiction? Gut. 2016;65:169-78 
90. McIntosh K, Reed DE, Schneider T, Dang F, Keshteli AH, De Palma G, Madsen K, Bercik P, 
Vanner S. FODMAPs alter symptoms and the metabolome of patients with IBS: a randomised 
controlled trial. Gut. 2017 Jul;66(7):1241-1251. 
91. Staudacher HM, Lomer MC, Anderson JL, et al. Fermentable carbohydrate restriction reduces 
luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. 
J Nutr 2012;142:1510–18. 
Page 25 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
92. Bennet SMP, Böhn L, Störsrud S, Liljebo T, Collin L, Lindfors P, Törnblom H, Öhman L, 
Simrén M. Multivariate modelling of faecal bacterial profiles of patients with IBS predicts 
responsiveness to a diet low in FODMAPs. Gut 2017. [Epub ahead of print] 
93. O’Mahony L, McCarthy J, Kelly P, et al. Lactobacillus and Bifidobacterium in irritable bowel 
syndrome: Symptom responses and relationship to cytokine profiles. Gastroenterology 
2005;128:541–51. 
94. Whorwell PJ, Altringer L, Morel J, et al. Efficacy of an encapsulated probiotic Bifidobacterium 
infantis 35624 in women with irritable bowel syndrome. Am J Gastroenterol 2006;101:1581–90. 
95. Guyonnet D, Chassany O, Ducrotte P, et al. Effect of a fermented milk containing 
Bifidobacterium animalis DN-173 010 on the health-related quality of life and symptoms in 
irritable bowel syndrome in adults in primary care: a multicentre, randomized, double-blind, 
controlled trial. Aliment Pharmacol Ther 2007;26:475–86. 
96. Sivan A, Corrales L, Hubert N, Williams JB, Aquino-Michaels K, Earley ZM, et al. Commensal 
Bifidobacterium promotes antitumor immunity and facilitates anti-PD-L1 efficacy. Science. 
2015;350:1084-9. 
97. Duca FA, Sakar Y, Covasa M. The modulatory role of high fat feeding on gastrointestinal 
signals in obesity. J Nutr Biochem 2013; 24:1663-77. 
98. Scarpellini E, Tack J. Obesity and metabolic syndrome: an inflammatory condition. Dig Dis 
2012; 30:148-153. 
99. Gauffin Cano P, Santacruz A, Trejo MF, Sanz Y. Bifidobacterium CECT 7765 improves 
metabolic and immunological alterations associated with obesity in high-fat diet-fed mice. 
Obesity 2013; 21:2310-21. 
100. Cani PD, Possemiers S, Van de Wiele T et al. Changes in gut microbiota control 
inflammation in obese mice through a mechanism involving GLP-2 driven improvement of gut 
permeability. Gut 2009; 58:1091-1103. 
Page 26 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
101. Zhou Q, Leeman SE, Amar S. Signaling mechanism involved in altered function of 
macrophages from diet-induced obese mice affect immune responces. Proc Natl Acad Sci USA 
2009; 106:10740-10745. 
102. Macia L, Declare M, Abboud G et al. Impairment of dendritic cell functionally and steady-
state number in obese mice. J Immunol 2006; 177: 5997-6006. 
103. O’Mahony C, Scully P, O’Mahony D, Murphy S, O’Brien F, Lyons A et al. Commensal-
induced regulatory T cells mediate protection against pathogen-stimulated NF-kappaB 
activation. PLoS Pathog 2008; 4:e1000112. 
104. Lyons A, O’Mahony D, O’Brien F, MacSharry J, Sheil B, Ceddia M et al. Bacterial strain-
specific induction of Foxp3+ T regulatory cells is protective in murine allergy models. Clin Exp 
Allergy 2010; 40:811-19. 
105. O'Mahony L, Feeney M, O'Halloran S, Murphy L, Kiely B, Fitzgibbon J, Lee G, O'Sullivan 
G, Shanahan F, Collins JK. Probiotic impact on microbial flora, inflammation and tumour 
development in IL-10 knockout mice. Aliment Pharmacol Ther 2001; 15:1219-25. 
106. Konieczna P, Akdis CA, Quigley EM, Shanahan F, O'Mahony L. Portrait of an 
immunoregulatory Bifidobacterium. Gut Microbes 2012; 3:261-6. 
107. McCarthy J, O'Mahony L, O'Callaghan L, Sheil B, Vaughan EE, Fitzsimons N, Fitzgibbon 
J, O'Sullivan GC, Kiely B, Collins JK, Shanahan F. Double blind, placebo controlled trial of two 
probiotic strains in interleukin 10 knockout mice and mechanistic link with cytokine balance. 
Gut 2003; 52:975-80. 
108. McKernan DP, Fitzgerald P, Dinan TG, Cryan JF. The probiotic Bifidobacterium infantis 
35624 displays visceral antinociceptive effects in the rat. Neurogastroenterol Motil 2010; 
22:1029-35, e268. 
109. Konieczna P, Groeger D, Ziegler M, Frei R, Ferstl R, Shanahan F, Quigley EM, Kiely B, 
Akdis CA, O'Mahony L. Bifidobacterium infantis 35624 administration induces Foxp3 T 
Page 27 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
regulatory cells in human peripheral blood: potential role for myeloid and plasmacytoid 
dendritic cells. Gut 2012; 61:354-66. 
110. Groeger D, O'Mahony L, Murphy EF, Bourke JF, Dinan TG, Kiely B, Shanahan F, Quigley 
EM. Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut. 
Gut Microbes 2013; 4:325-39. 
111. Tojo R, Suárez A, Clemente MG, de los Reyes-Gavilán CG, Margolles A, Gueimonde M, 
Ruas-Madiedo P. Intestinal microbiota in health and disease: role of bifidobacteria in gut 
homeostasis. World J Gastroenterol 2014; 20:15163-76. 
112. van der Aa LB, van Aalderen WM, Heymans HS, Henk Sillevis Smitt J, Nauta AJ, Knippels 
LM, Ben Amor K, Sprikkelman AB; Synbad Study Group. Synbiotics prevent asthma-like 
symptoms in infants with atopic dermatitis. Allergy 2011;66:170-7. 
113. Xiao JZ, Kondo S, Yanagisawa N, Takahashi N, Odamaki T, Iwabuchi N, Miyaji K, 
Iwatsuki K, Togashi H, Enomoto K, Enomoto T. Probiotics in the treatment of Japanese cedar 
pollinosis: a double-blind placebo-controlled trial. Clin Exp Allergy 2006 Nov;36(11):1425-35. 
114. Singh A, Hacini-Rachinel F, Gosoniu ML, Bourdeau T, Holvoet S, Doucet-Ladeveze R, 
Beaumont M, Mercenier A, Nutten S. Immune-modulatory effect of probiotic Bifidobacterium 
lactis NCC2818 in individuals suffering from seasonal allergic rhinitis to grass pollen: an 
exploratory, randomized, placebo-controlled clinical trial. Eur J Clin Nutr 2013; 67:161-7. 
115. Odamaki T, Xiao JZ, Iwabuchi N, Sakamoto M, Takahashi N, Kondo S, Miyaji K, Iwatsuki 
K, Togashi H, Enomoto T, Benno Y.Influence of Bifidobacterium longum BB536 intake on 
faecal microbiota in individuals with Japanese cedar pollinosis during the pollen season. J Med 
Microbiol 2007; 56:1301-8. 
116. Mayer EA, Tillisch K, Gupta A. Gut/brain axis and the microbiota. J Clin Invest 2015; 125: 
926-938. 
117. Grenham S, Clarke G, Cryan JF, Dinan TG. Brain-gut-microbe communication in health 
and disease. Front Physiol 2011; 2: 94. 
Page 28 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
118. Rhee SH, Pothoulakis C, Mayer EA. Principles and clinical implications of the brain-gut-
enteric microbiota axis. Nat Rev Gastroenterol Hepatol 2009; 6: 306-314. 
119. Galland L. The gut microbiome and the brain. J Med Food 2014; 17: 1261-1272. 
120. Lyte M. Microbial endocrinology: Host-microbiota neuroendocrine interactions influencing 
brain and behavior. Gut Microbes 2014; 5: 381-389. 
121. Borre YE, O’Keeffe GW, Clarke G, Stanton C, Dinan TG, Cryan JF. Microbiota and 
neurodevelopmental windows: implications for brain disorders. Trends Mol Med 2014; 20: 509-
518. 
122. Dinan TG, Cryan JF. Melancholic microbes: a link between gut microbiota and depression? 
Neurogastroenterol Motil 2013; 25: 713-719. 
123. Bonaz BL, Bernstein CN. Brain-gut interactions in inflammatory bowel disease. 
Gastroenterology 2013; 144: 36-49. 
124. Hsiao EY, McBride SW, Hsien S, Sharon G, Hyde ER, McCue T, Codelli JA, Chow J, 
Reisman SE, Petrosino JF, Patterson PH, Mazmanian SK. Microbiota modulate behavioral and 
physiological abnormalities associated with neurodevelopmental disorders.Cell 2013; 155: 
1451-1463. 
125. Forsythe P, Bienenstock J, Kunze WA. Vagal pathways for microbiome-brain-gut axis 
communication. Adv Exp Med Biol 2014; 817: 115-133. 
126. Mulak A, Bonaz Bruno. Brain-gut-microbiota axis in Parkinson’s disease. World J 
Gastroenterol 2015; 21:10609-10620. 
127. Bailey MT, Coe CL. Maternal separation disrupts the integrity of the intestinal microflora in 
infant rhesus monkeys. Dev Psychobiol 1999;35:146-55. 
128. Bailey MT, Lubach GR, Coe CL. Prenatal stress alters bacterial colonization of the gut in 
infant monkeys. J Pediatr Gastroenterol Nutr 2004; 38:414–421. 
129. Tannock GW, Savage DC. Influences of dietary and environmental stress on microbial 
populations in the murine gastrointestinal tract. Infect Immun 1974; 9:591-8. 
Page 29 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
130. Suzuki K, Harasawa R, Yoshitake Y, Mitsuoka T. Effects of crowding and heat stress on 
intestinal flora, body weight gain, and feed efficiency of growing rats and chicks. Nippon 
Juigaku Zasshi 1983; 45:331–338. 
131. Goncharova GI, Liz’ko NN, Liannaia AM, Shilov VM, Spitsa TI. Bifidobacterium flora 
status of cosmonauts before and after com- pleting space flights. Kosm Biol Aviakosm Med 
1981; 15:14–18. 
132. Desbonnet L, Garrett L, Clarke G, Bienenstock J, Dinan TG. The probiotic Bifidobacteria 
infantis: an assessment of potential antidepressant properties in the rat. J Psych Res 2009; 
43:164-174. 
133. Desbonnet L, Garrett L, Clarke G, Kiely B, Cryan JF, Dinan TG. Effects of the probiotic 
bifidobacterium infantis in the maternal separation model of depression. Neuroscience 2010; 
170:1179-1188. 
134. Lyte M, Chapel A, Lyte JM, Ai Y, Proctor A, Jane JL, Phillips GJ. Resistant starch alters 
the microbiota-gut-brain axis: implications for dietary modulation of behavior. PloS ONE 2016; 
11:e0146406. 
135. Tachon S, Zhou J, Keenan M, Martin R, Marco ML. The intestinal microbiota in aged mice 
is modulated by dietary resistant starch and correlated with improvements in host responses. 
FEMS Microbiol Ecol. 2013; 83:299–309. 
136. Distrutti E, O’Reilly J-A, McDonald C, Cipriani S, Renga B, et al. Modulation of Intestinal 
Microbiota by the Probiotic VSL#3 Resets Brain Gene Expression and Ameliorates the Age-
Related Deficit in LTP. PLoS ONE 2014; 9: e106503. 
137. Leclercq S, Matamoros S, Cani PD, Neyrinck AM, Jamar F, Stärkel P, Windey K,Tremaroli 
V, Bäckhed F, Verbeke K, de Timary P, Delzenne NM. Intestinalpermeability, gut-bacterial 
dysbiosis, and behavioral markers of alcohol-dependence severity. Proc Natl Acad Sci U S A 
2014;111:e4485-93. 
Page 30 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
138. Gionchetti P, Rizzello F, Helwig U, Venturi A, Lammers KM, Brigidi P, et al. Prophylaxis 
of pouchitis onset withprobiotic therapy: a double-blind, placebo-controlled trial. 
Gastroenterology 2003; 124:1202-9. 
139. Mimura T, Rizzello F, Helwig U, Poggioli G, Schreiber S, Talbot IC, et al. Once daily high 
dose probiotic therapy(VSL#3) for maintaining remission in recurrent or refractory pouchitis. 
Gut 2004; 53:108-14. 
140. Sood A, Midha V, Makharia GK, Ahuja V, Singal D, Goswami P, Tandon RK. The 
probiotic preparation, VSL#3 induces remission in patients with mild-to-moderately active 
ulcerative colitis. Clin Gastroenterol Hepatol 2009; 7:1202-9. 
141. Mardini HE, Grigorian AY. Probiotic mix VSL#3 is effective adjunctive therapy for mild to 
moderately active ulcerative colitis: a meta-analysis. Inflamm Bowel Dis 2014; 20:1562-7. 
142. Tursi A, Brandimarte G, Papa A, Giglio A, Elisei W, Giorgetti GM, Forti G, Morini S, 
Hassan C, Pistoia MA, Modeo ME, Rodino' S, D'Amico T, Sebkova L, Sacca’ N, Di Giulio E, 
Luzza F, Imeneo M, Larussa T, Di Rosa S, Annese V, Danese S, Gasbarrini A. Treatment of 
relapsing mild-to-moderate ulcerative colitis with the probiotic VSL#3 as adjunctive to a 
standard pharmaceutical treatment: a double-blind, randomized, placebo-controlled study. Am J 
Gastroenterol 2010; 105:2218-27. 
143. Miele E, Pascarella F, Giannetti E, Quaglietta L, Baldassano RN, Staiano A. Effect of a 
probiotic preparation (VSL#3) on induction and maintenance of remission in children with 
ulcerative colitis. Am J Gastroenterol 2009;104: 437-43. 
144. Abu-Shanab A, Quigley EM. The role of the gut microbiota in nonalcoholic fatty liver 
disease. Nat Rev Gastroenterol Hepatol 2010; 7:691-701. 
145. Machado MV, Cortez-Pinto H. Gut microbiota and nonalcoholic fatty liverdisease. Ann 
Hepatol 2012; 11:440-9. 
Page 31 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
146. Selinger CP, Bell A, Cairns A, Lockett M, Sebastian S, Haslam N. Probiotic VSL#3 
prevents antibiotic-associated diarrhoea in a double-blind, randomized, placebo-controlled 
clinical trial. J Hosp Infect 2013; 84:159-65. 
147. Ishikawa H, Matsumoto S, Ohashi Y, Imaoka A, Setoyama H, Umesaki Y, Tanaka R, Otani 
T. Beneficial effects of probiotic bifidobacterium and galacto-oligosaccharide in patients with 
ulcerative colitis: a randomized controlled study. Digestion. 2011;84:128-33. 
148. Kajander K, Hatakka K, Poussa T, Färkkilä M, Korpela R. A probiotic mixture alleviates 
symptoms in irritable bowel syndrome patients: a controlled 6-month intervention. Aliment 
Pharmacol Ther 2005; 22:387-94. 
149. Kajander K, Myllyluoma E, Rajilić-Stojanović M, Kyrönpalo S, Rasmussen M, Järvenpää 
S, Zoetendal EG, de Vos WM, Vapaatalo H, Korpela R. Clinical trial: multispecies probiotic 
supplementation alleviates the symptoms of irritable bowel syndrome and stabilizes intestinal 
microbiota. Aliment Pharmacol Ther 2008; 27:48-57. 
150. Guandalini S, Magazzù G, Chiaro A, La Balestra V, Di Nardo G, Gopalan S, Sibal A, 
Romano C, Canani RB, Lionetti P, Setty M. VSL#3 improves symptoms in children with 
irritable bowel syndrome: a multicenter, randomized, placebo-controlled, double-blind, 
crossover study. J Pediatr Gastroenterol Nutr 2010; 51:24-30. 
151. Kleessen B, Sykura B, Zunft HJ, Blaut M. Effects of inulin and lactose on fecal microflora, 
microbial activity, and bowel habit in elderly constipated persons. Am J Clin Nutr 1997; 
65:1397-402. 
152. Leahy SC, Higgins DG, Fitzgerald GF, van Sinderen D. Getting better with bifidobacteria. J 
Appl Microbiol 2005; 98:1303-15. 
153. Corrêa NB, Péret Filho LA, Penna FJ, Lima FM, Nicoli JR. A randomized formula 
controlledtrial of Bifidobacterium lactis and Streptococcus thermophilus for prevention of 
antibiotic-associated diarrhea in infants. J Clin Gastroenterol 2005; 39:385-9. 
Page 32 of 36
Ac
ce
pt
ed
 M
an
us
cr
ip
t
 
 
154. Patole SK, Rao SC, Keil AD, Nathan EA, Doherty DA, Simmer KN. Benefits of 
Bifidobacterium breve M-16V Supplementation in Preterm Neonates - A Retrospective Cohort 
Study. PLoS One. 2016;11:e0150775. 
155. Chenoll E, Rivero M, Codoñer FM, Martinez-Blanch JF, Ramón D, Genovés S, Moreno 
Muñoz JA. Complete Genome Sequence of Bifidobacterium longum subsp. infantis Strain 
CECT 7210, a Probiotic Strain Active against Rotavirus Infections. Genome Announc 2015 
;3(2). pii: e00105-15. 
156. Le Leu RK, Hu Y, Brown IL, Woodman RJ, Young GP. Synbiotic intervention of 
Bifidobacterium lactis and resistant starch protects against colorectal cancer development in 
rats. Carcinogenesis. 2010; 31:246-51. 
157. Rafter J, Bennett M, Caderni G, Clune Y, Hughes R, Karlsson PC, Klinder A, O'Riordan M, 
O'Sullivan GC, Pool-Zobel B, Rechkemmer G, Roller M, Rowland I, Salvadori M, Thijs H, Van 
Loo J, Watzl B, Collins JK. Dietary synbiotics reduce cancer risk factors in polypectomized and 
colon cancer patients. Am J Clin Nutr 2007;85:488-96. 
158. Le Leu,R.K. et al. (2005) A synbiotic combination of resistant starch and Bifidobacterium 
lactis facilitates apoptotic deletion of carcinogen-damaged cells in rat colon. J. Nutr., 135, 996–
1001 
 
 
 
 
 
 
 
 
 
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FIGURE LEGEND 
Figure 1 
Actinobacteria phylum groups four main families: Bifidobacteria, Propionibacteria, Corynebacteria, 
Stremptomyces. Actinobacteria exert crucial physiological functions in the gut. FOS: fructo-
oligosaccharides, GOS: galacto-oligosaccharides, XOS: xylo-oligosaccharides, BDNF: brain-
derived neurotrophic factor. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 1 
Potential modulatory and therapeutic role of Actinobacteria in intestinal and extra-intestinal 
diseases. 
RCU/ UC: ulcerative colitis, IBS: irritable bowel syndrome, NEC: necrotizing entero-colitis, 
NASH: non-alcoholic steato-hepatitis. 
 
 
 
 
 
 
 
 
 
 
 
 
 
INTESTINAL DISEASES EXTRA-INTESTINAL DISEASES 
UC: prevention of pouchitis relapse, 
maintenance of remission and 
treatment of mild-to-moderate UC 
NASH 
IBS RESPIRATORY PATHOLOGIES 
CONSTIPATION PSORIASIS 
ANTIBIOTIC-ASSOCIATED 
DIARHEA 
CHRONIC FATIGUE SYNDROME 
NEC DEPRESSION 
COLORECTAL CANCER COGNITIVE DETERIORATION 
 
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CONFLICT OF INTEREST 
Authors declare no conflict of interest. 
 
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Immunological function: 
-maintenance of gut permeability 
-down-regulation of inflammation by 
production of IL-4 and IL-13 
-induction of regulatory T-cells 
-regulation of Th-2 immunoresponse 
Gut Barrier: 
-production of acetate 
-production of lactate that is used by 
“lactate-utilizer” for the production of 
butyrate 
-maintenance of gut permeability 
Gut-Brain Axis: 
-potential anti-depressant effects with the 
elevation of tryptophan levels 
-regulation of mediators involved in 
synaptic plasticity like BDNF, synapsin, 
syntaxin 
-modulation of hippocampal molecules such 
as CD68 and CD11b 
PHYSIOLOGICAL FUNCTIONS 
Actinobacteria 
Bifidobacteria Propionibacteria 
Corynebacteria Streptomyces 
Metabolism: 
-production of acetate 
-biodegradation of resistant starch with 
production of FOS, GOS, XOS, inulin, 
arabinoxilan 
-formation of conjugated linoleic acids 
Figure 1