Microbiota-activated PPAR-γ signaling inhibits dysbiotic Enterobacteriaceae expansion

Aspergillus cristatus attenuates DSS-induced intestinal barrier damage through reducing the oxidative stress, regulating short-chain fatty acid and inhibiting MAPK signaling pathways

BACKGROUND

Probiotics are regarded as a promising strategy for relieving colitis caused by dextran sulfate sodium (DSS). One of the dominant probiotic fungi in Fuzhuan brick tea is identified as Aspergillus cristatus, but whether it can effectively improve colitis remains poorly understood. Here, the improving effect of A. cristatus on colitis was investigated.

RESULTS

Our results showed that A. cristatus intervention prominently alleviated gut damage as evidenced by the inhibition of shortened colon length, goblet cell depletion, and histological injury. Mechanistically, after administration with low concentrations of A. cristatus H-1 and A. cristatus S-6, the expression of interleukin-6, tumor necrosis factor-α, interleukin-1β, nitric oxide, and malondialdehyde were significantly downregulated, and the content of glutathione, catalase, interleukin-10, immunoglobulin G, claudin-1, occludin, and zonula occludens-1 were effectively upregulated. More importantly, live A. cristatus supplementation lightened DSS-induced gut barrier damage by suppressing activation of the mitogen-activated protein kinase (MAPK) signaling pathway, increasing the synthesis of short-chain fatty acids (SCFAs) and stimulating the increase in peroxisome proliferator-activated receptor γ expression.

CONCLUSION

Together, A. cristatus can attenuate DSS-induced intestinal barrier damage through reducing the oxidative stress, regulating SCFA and inhibiting MAPK signaling pathways (P38/JNK/ERK). Our findings indicate that A. cristatus replenishment has potential as a new probiotic fungi to reduce DSS-induced colitis. © 2022 Society of Chemical Industry.

Cannabinoids modulate the microbiota-gut-brain axis in HIV/SIV infection by reducing neuroinflammation and dysbiosis while concurrently elevating endocannabinoid and indole-3-propionate levels

BACKGROUND

Although the advent of combination anti-retroviral therapy (cART) has transformed HIV into a manageable chronic disease, an estimated 30-50% of people living with HIV (PLWH) exhibit cognitive and motor deficits collectively known as HIV-associated neurocognitive disorders (HAND). A key driver of HAND neuropathology is chronic neuroinflammation, where proinflammatory mediators produced by activated microglia and macrophages are thought to inflict neuronal injury and loss. Moreover, the dysregulation of the microbiota-gut-brain axis (MGBA) in PLWH, consequent to gastrointestinal dysfunction and dysbiosis, can lead to neuroinflammation and persistent cognitive impairment, which underscores the need for new interventions.

METHODS

We performed RNA-seq and microRNA profiling in basal ganglia (BG), metabolomics (plasma) and shotgun metagenomic sequencing (colon contents) in uninfected and SIV-infected rhesus macaques (RMs) administered vehicle (VEH/SIV) or delta-9-tetrahydrocannabinol (THC) (THC/SIV).

RESULTS

Long-term, low-dose THC reduced neuroinflammation and dysbiosis and significantly increased plasma endocannabinoid, endocannabinoid-like, glycerophospholipid and indole-3-propionate levels in chronically SIV-infected RMs. Chronic THC potently blocked the upregulation of genes associated with type-I interferon responses (NLRC5, CCL2, CXCL10, IRF1, IRF7, STAT2, BST2), excitotoxicity (SLC7A11), and enhanced protein expression of WFS1 (endoplasmic reticulum stress) and CRYM (oxidative stress) in BG. Additionally, THC successfully countered miR-142-3p-mediated suppression of WFS1 protein expression via a cannabinoid receptor-1-mediated mechanism in HCN2 neuronal cells. Most importantly, THC significantly increased the relative abundance of Firmicutes and Clostridia including indole-3-propionate (C. botulinum, C. paraputrificum, and C. cadaveris) and butyrate (C. butyricum, Faecalibacterium prausnitzii and Butyricicoccus pullicaecorum) producers in colonic contents.

CONCLUSION

This study demonstrates the potential of long-term, low-dose THC to positively modulate the MGBA by reducing neuroinflammation, enhancing endocannabinoid levels and promoting the growth of gut bacterial species that produce neuroprotective metabolites, like indole-3-propionate. The findings from this study may benefit not only PLWH on cART, but also those with no access to cART and more importantly, those who fail to suppress the virus under cART.

A major mechanism for immunomodulation: Dietary fibres and acid metabolites

Diet and the gut microbiota have a profound influence on physiology and health, however, mechanisms are still emerging. Here we outline several pathways that gut microbiota products, particularly short-chain fatty acids (SCFAs), use to maintain gut and immune homeostasis. Dietary fibre is fermented by the gut microbiota in the colon, and large quantities of SCFAs such as acetate, propionate, and butyrate are produced. Dietary fibre and SCFAs enhance epithelial integrity and thereby limit systemic endotoxemia. Moreover, SCFAs inhibit histone deacetylases (HDAC), and thereby affect gene transcription. SCFAs also bind to 'metabolite-sensing' G-protein coupled receptors (GPCRs) such as GPR43, which promotes immune homeostasis. The enormous amounts of SCFAs produced in the colon are sufficient to lower pH, which affects the function of proton sensors such as GPR65 expressed on the gut epithelium and immune cells. GPR65 is an anti-inflammatory Gα_s-coupled receptor, which leads to the inhibition of inflammatory cytokines. The importance of GPR65 in inflammatory diseases is underscored by genetics associated with the missense variant I231L (rs3742704), which is associated with human inflammatory bowel disease, atopic dermatitis, and asthma. There is enormous scope to manipulate these pathways using specialized diets that release very high amounts of specific SCFAs in the gut, and we believe that therapies that rely on chemically modified foods is a promising approach. Such an approach includes high SCFA-producing diets, which we have shown to decrease numerous inflammatory western diseases in mouse models. These diets operate at many levels - increased gut integrity, changes to the gut microbiome, and promotion of immune homeostasis, which represents a new and highly promising way to prevent or treat human disease.

Wogonin regulates colonocyte metabolism via PPARγ to inhibit Enterobacteriaceae against dextran sulfate sodium-induced colitis in mice

To investigate the potential effects and mechanism of wogonin on dextran sulfate sodium (DSS)-induced colitis, 70 male mice were administered wogonin (12.5, 25, 50 mg·kg^-1 ·d^-1 , i.g.) for 10 days, meanwhile, in order to induce colitis, the mice were free to drink 3% DSS for 6 days. We found that wogonin could obviously ameliorate DSS-induced colitis, including preventing colon shortening and inhibiting pathological damage. In addition, wogonin could increase the expression of PPARγ, which not only restores intestinal epithelial hypoxia but also inhibits iNOS protein to reduce intestinal nitrite levels. All these effects facilitated a reduction in the abundance of Enterobacteriaceae in DSS-induced colitis mice. Therefore, compared with the DSS group, the number of Enterobacteriaceae in the intestinal flora was significantly reduced after administration of wogonin or rosiglitazone by 16s rDNA technology. We also verified that wogonin could promote the expression of PPARγ mRNA and protein in Caco-2 cells, and this effect disappeared when PPARγ signal was inhibited. In conclusion, our study suggested that wogonin can activate the PPARγ signal of the Intestinal epithelium to ameliorate the Intestinal inflammation caused by Enterobacteriaceae bacteria expansion.

The gut microbiome: a core regulator of metabolism

The human body is inhabited by numerous bacteria, fungi, and viruses, and each part has a unique microbial community structure. The gastrointestinal tract harbors approximately 100 trillion strains comprising more than 1000 bacterial species that maintain symbiotic relationships with the host. The gut microbiota consists mainly of the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Of these, Firmicutes and Bacteroidetes constitute 70-90% of the total abundance. Gut microbiota utilize nutrients ingested by the host, interact with other bacterial species, and help maintain healthy homeostasis in the host. In recent years, it has become increasingly clear that a breakdown of the microbial structure and its functions, known as dysbiosis, is associated with the development of allergies, autoimmune diseases, cancers, and arteriosclerosis, among others. Metabolic diseases, such as obesity and diabetes, also have a causal relationship with dysbiosis. The present review provides a brief overview of the general roles of the gut microbiota and their relationship with metabolic disorders.

Sugar-sweetened beverages exacerbate high-fat diet-induced inflammatory bowel disease by altering the gut microbiome

High-fat diets (HFDs) and frequent consumption of sugar-sweetened beverages (SSBs) are potential contributors to increasing inflammatory bowel disease (IBD) incidences. While HFDs have been implicated in mild intestinal inflammation, the role of sucrose in SSBs remains unclear. Therefore, we studied the role of SSBs in IBD pathogenesis in a mouse model and humans. C57BL6/J mice were given ad libitum access to a sucrose solution or plain water for 10 weeks, with or without an HFD. Interestingly, sucrose solution consumption alone did not induce gut inflammation in mice; however, when combined with an HFD, it dramatically increased the inflammation score, submucosal edema, and CD45⁺ cell infiltration. 16S ribosomal RNA gene-sequencing revealed that sucrose solution and HFD co-consumption significantly increased the relative abundance of IBD-related pathogenic bacteria when compared with HFD consumption. RNA sequencing and flow cytometry showed that co-consumption promoted pro-inflammatory cytokine and chemokine synthesis, dendritic-cell expansion, and IFN-γ⁺TNF-α⁺CD4⁺ and CD8⁺ T-cell activation. Fecal microbiota transplantation from HFD- and sucrose water-fed mice into gut-sterilized mice increased the susceptibility to dextran sulfate sodium-induced colitis in the recipient mice. Consistent herewith, high consumption of SSBs and animal fat-rich diets markedly increased systemic inflammation-associated IBD marker expression in humans. In conclusion, SSBs exacerbate HFD-induced colitis by triggering a shift of the gut microbiome into a pathobiome. Our findings provide new insights for the development of strategies aimed at preventing IBD.

Carotenoids and Their Health Benefits as Derived via Their Interactions with Gut Microbiota

Carotenoids have been related to a number of health benefits. Their dietary intake and circulating levels have been associated with a reduced incidence of obesity, diabetes, certain types of cancer, and even lower total mortality. Their potential interaction with the gut microbiota (GM) has been generally overlooked but may be of relevance, as carotenoids largely bypass absorption in the small intestine and are passed on to the colon, where they appear to be in part degraded into unknown metabolites. These may include apo-carotenoids that may have biological effects because of higher aqueous solubility and higher electrophilicity that could better target transcription factors, i.e., NF-κB, PPARγ, and RAR/RXRs. If absorbed in the colon, they could have both local and systemic effects. Certain microbes that may be supplemented were also reported to produce carotenoids in the colon. Although some bactericidal aspects of carotenoids have been shown in vitro, a few studies have also demonstrated a prebiotic-like effect, resulting in bacterial shifts with health-associated properties. Also, stimulation of IgA could play a role in this respect. Carotenoids may further contribute to mucosal and gut barrier health, such as stabilizing tight junctions. This review highlights potential gut-related health-beneficial effects of carotenoids and emphasizes the current research gaps regarding carotenoid-GM interactions.

Gut Enterobacteriaceae and uraemic toxins - Perpetrators for ageing

Ageing is a complex process that is associated with changes in the composition and functions of gut microbiota. Reduction of gut commensals is the hallmarks of ageing, which favours the expansion of pathogens even in healthy centenarians. Interestingly, gut Enterobacteriaceae have been found to be increased with age and also consistently observed in the patients with metabolic diseases. Thus, they are associated with all-cause mortality, regardless of genetic origin, lifestyle, and fatality rate. Moreover, Enterobacteriaceae are also implicated in accelerating the ageing process through telomere attrition, cellular senescence, inflammasome activation and impairing the functions of mitochondria. However, acceleration of ageing is likely to be determined by intrinsic interactions between Enterobacteriaceae and other associated gut bacteria. Several studies suggested that Enterobacteriaceae possess genes for the synthesis of uraemic toxins. In addition to intestine, Enterobacteriaceae and their toxic metabolites have also been found in other organs, such as adipose tissue and liver and that are implicated in multiorgan dysfunction and age-related diseases. Therefore, targeting Enterobacteriaceae is a nuance approach for reducing inflammaging and enhancing the longevity of older people. This review is intended to highlight the current knowledge of Enterobacteriaceae-mediated acceleration of ageing process.

Efficiency of Chinese medicine Bushen Huatan formula for treatment of polycystic ovary syndrome in mice via regulating gut microbiota and PPARγ pathway

OBJECTIVES

To explore the effect and mechanism of Chinese medicine Bushen Huatan formula in treatment of polycystic ovary syndrome (PCOS).

METHODS

Twenty-four SPF female C57BL/6J mice were randomly divided into 3 groups with 8 animals in each group. Control group was given drinking water ad libitum; PCOS was induced by giving letrozole gavage and high-fat diet in model group and treatment group; treatment group received Bushen Huatan formula suspension for 35 d. The sex hormone levels of mice were detected by enzyme-linked immunosorbent assay. Ovary morphology was observed under light microscope after hematoxylin and eosin staining. The feces in the colon of mice were collected, and the gut microbiota was detected by 16S rRNA sequencing. The short chain fatty acids were detected by gas chromatography-mas spectrometry. The expression of peroxisome proliferator activated receptor (PPARγ) was detected by immunohistochemistry. The mRNA expression of mucin-2, occludin-1, tight junction protein zonula occludens 1 (ZO-1) and PPARγ in intestinal epithelium were detected by realtime RT-PCR. The expression of inducible nitric oxide synthase (iNOS) and PPARγ was detected by Western blotting.

RESULTS

Compared with the control group, the body weight, serum levels of follicle stimulating hormone, luteinizing hormone and testosterone in the model group were increased, and serum levels of estradiol were decreased (all P<0.01); the ovarian structure under light microscope was consistent with the characteristics of PCOS. Compared with the model group, the serum levels of sex hormone and ovarian structure in treatment group were improved. The overall structure of gut microbiota in PCOS model mice changed. Compared with control group, there were significantly reduced abundance of Firmicutes, and increased abundance of Verrucomicrobia, Proteobacteria and Actinobacteria inthe model group at phylum level (all P<0.05); there were significantly reduced abundance of Lactobacillus, and increased abundance of Akkermansia, Lachnoclostridium, Lactococcus and Eubacterium_coprostanoligenes at genus level (all P<0.05). The disordered condition of gut microbiota was significantly improved in treatment group. Compared with control group, the contents of acetic acid, propionic acid and butyric acid in feces of model group were significantly decreased (all P<0.05); while the contents of propionic acid and butyric acid in treatment group were significantly increased compared with model control group (both P<0.05). Compared with control group, the mRNA expression of ZO-1 and protein expression of iNOS in model group were significantly increased, and the protein expression of PPARγ and the mRNA expressions of mucin-2 and occludin-1 were significantly decreased (all P<0.05). Compared with model group, the mRNA expression of ZO-1 and protein expression of iNOS in treatment group were decreased, and the protein expression of PPARγ and the mRNA expressions of mucin-2 and occludin-1 were increased.

CONCLUSIONS

PCOS induced by letrozole high-fat diet induces microflora imbalance in mice. Chinese medicine Bushen Huatan formula may increase the level of short chain fatty acid by regulating gut microbiota, thereby activating the intestinal PPARγ pathway and improving intestinal barrier function to act as a cure for PCOS.

A High Dose of Dietary Berberine Improves Gut Wall Morphology, Despite an Expansion of Enterobacteriaceae and a Reduction in Beneficial Microbiota in Broiler Chickens

Phytogenic products are embraced as alternatives to antimicrobials, and some are known to mitigate intestinal inflammation and ensure optimal gut health and performance in broiler chickens. Dietary inclusion of berberine, a benzylisoquinoline alkaloid found in plants, is believed to exert gut health-promoting effects through modulation of the gut microbiota; however, there are only a few studies investigating its effects in chickens. The aim of this study was to investigate the interplay between dietary supplementation of a high concentration of berberine, the gastrointestinal microbiota, and histomorphological parameters in the gut. Berberine was shown to increase villus length and decrease crypt depth and CD3⁺ T-lymphocyte infiltration in the gut tissue of chickens at different ages. Berberine affected the diversity of the gut microbiota from the jejunum to the colon, both at a compositional and functional level, with larger effects observed in the large intestine. A high concentration of berberine enriched members of the Enterobacteriaceae family and depleted members of the Ruminococcaceae, Lachnospiraceae, and Peptostreptococcaceae families, as well as tended to reduce butyrate production in the cecum. In vivo results were confirmed by in vitro growth experiments, where increasing concentrations of berberine inhibited the growth of several butyrate-producing strains while not affecting that of Enterobacteriaceae strains. Positive correlations were found between berberine levels in plasma and villus length or villus-to-crypt ratio in the jejunum. Our study showed that berberine supplementation at a high concentration improves chicken gut morphology toward decreased inflammation, which is likely not mediated by the induced gut microbiota shifts. IMPORTANCE Dietary additives are widely used to reduce intestinal inflammation and enteritis, a growing problem in the broiler industry. Berberine, with anti-inflammatory, antioxidant, and antimicrobial activity, would be an interesting feed additive in this regard. This study investigates for the first time the impact of berberine supplementation on the chicken gastrointestinal microbiota, as a potential mechanism to improve gut health, together with histological effects in the small intestine. This study identified a dose-effect of berberine on the gut microbiota, indicating the importance of finding an optimal dose to be used as a dietary additive.

Peroxisome proliferator-activated receptors-alpha and gamma synergism modulate the gut-adipose tissue axis and mitigate obesity

AIM

To evaluate the effects of single PPARα or PPARγ activation, and their synergism (combined PPARα/γ activation) upon the gut-adipose tissue axis, focusing on the endotoxemia and upstream interscapular brown adipose tissue (iBAT) function in high-saturated fat-fed mice.

METHODS

Male C57BL/6 mice received a control diet (C, 10% lipids) or a high-fat diet (HF, 50% lipids) for 12 weeks. Then, the HF group was divided to receive the treatments for four weeks: HFγ (pioglitazone, 10 mg/kg), HFα (WY-14643, 3.5 mg/kg), and HFα/γ (tesaglitazar, 4 mg/kg).

RESULTS

The HF group exhibited overweight, oral glucose intolerance, gut dysbiosis, altered gut permeability, and endotoxemia, culminating in iBAT whitening. The downregulation of LPS-Tlr4 signaling underpinned reduced inflammation and improved lipid metabolism in iBAT in the HFα/γ group, the unique to show normalized body mass and increased energy expenditure.

CONCLUSION

PPARα/γ synergism treated obesity by ameliorating the gut-adipose tissue axis, where restored gut microbiota and permeability controlled endotoxemia and rescued iBAT whitening through favored thermogenesis.

Gut Microbiota and Coronary Artery Disease: Current Therapeutic Perspectives

The human gut microbiota is the community of microorganisms living in the human gut. This microbial ecosystem contains bacteria beneficial to their host and plays important roles in human physiology, participating in energy harvest from indigestible fiber, vitamin synthesis, and regulation of the immune system, among others. Accumulating evidence suggests a possible link between compositional and metabolic aberrations of the gut microbiota and coronary artery disease in humans. Manipulating the gut microbiota through targeted interventions is an emerging field of science, aiming at reducing the risk of disease. Among the interventions with the most promising results are probiotics, prebiotics, synbiotics, and trimethylamine N-oxide (TMAO) inhibitors. Contemporary studies of probiotics have shown an improvement of inflammation and endothelial cell function, paired with attenuated extracellular matrix remodeling and TMAO production. Lactobacilli, Bifidobacteria, and Bacteroides are some of the most well studied probiotics in experimental and clinical settings. Prebiotics may also decrease inflammation and lead to reductions in blood pressure, body weight, and hyperlipidemia. Synbiotics have been associated with an improvement in glucose homeostasis and lipid abnormalities. On the contrary, no evidence yet exists on the possible benefits of postbiotic use, while the use of antibiotics is not warranted, due to potentially deleterious effects. TMAO inhibitors such as 3,3-dimethyl-1-butanol, iodomethylcholine, and fluoromethylcholine, despite still being investigated experimentally, appear to possess anti-inflammatory, antioxidant, and anti-fibrotic properties. Finally, fecal transplantation carries conflicting evidence, mandating the need for further research. In the present review we summarize the links between the gut microbiota and coronary artery disease and elaborate on the varied therapeutic measures that are being explored in this context.

Over supplementation with vitamin B12 alters microbe-host interactions in the gut leading to accelerated Citrobacter rodentium colonization and pathogenesis in mice

BACKGROUND

Vitamin B12 supplements typically contain doses that far exceed the recommended daily amount, and high exposures are generally considered safe. Competitive and syntrophic interactions for B12 exist between microbes in the gut. Yet, to what extent excessive levels contribute to the activities of the gut microbiota remains unclear. The objective of this study was to evaluate the effect of B12 on microbial ecology using a B12 supplemented mouse model with Citrobacter rodentium, a mouse-specific pathogen. Mice were fed a standard chow diet and received either water or water supplemented with B12 (cyanocobalamin: ~120 μg/day), which equates to approximately 25 mg in humans. Infection severity was determined by body weight, pathogen load, and histopathologic scoring. Host biomarkers of inflammation were assessed in the colon before and after the pathogen challenge.

RESULTS

Cyanocobalamin supplementation enhanced pathogen colonization at day 1 (P < 0.05) and day 3 (P < 0.01) postinfection. The impact of B12 on gut microbial communities, although minor, was distinct and attributed to the changes in the Lachnospiraceae populations and reduced alpha diversity. Cyanocobalamin treatment disrupted the activity of the low-abundance community members of the gut microbiota. It enhanced the amount of interleukin-12 p40 subunit protein (IL12/23p40; P < 0.001) and interleukin-17a (IL-17A; P < 0.05) in the colon of naïve mice. This immune phenotype was microbe dependent, and the response varied based on the baseline microbiota. The cecal metatranscriptome revealed that excessive cyanocobalamin decreased the expression of glucose utilizing genes by C. rodentium, a metabolic attribute previously associated with pathogen virulence.

CONCLUSIONS

Oral vitamin B12 supplementation promoted C. rodentium colonization in mice by altering the activities of the Lachnospiraceae populations in the gut. A lower abundance of select Lachnospiraceae species correlated to higher p40 subunit levels, while the detection of Parasutterella exacerbated inflammatory markers in the colon of naïve mice. The B12-induced change in gut ecology enhanced the ability of C. rodentium colonization by impacting key microbe-host interactions that help with pathogen exclusion. This research provides insight into how B12 impacts the gut microbiota and highlights potential consequences of disrupting microbial B12 competition/sharing through over-supplementation. Video Abstract.

Clostridioides difficile infection: traversing host-pathogen interactions in the gut

C. difficile is the primary cause for nosocomial infective diarrhoea. For a successful infection, C. difficile must navigate between resident gut bacteria and the harsh host environment. The perturbation of the intestinal microbiota by broad-spectrum antibiotics alters the composition and the geography of the gut microbiota, deterring colonization resistance, and enabling C. difficile to colonize. This review will discuss how C. difficile interacts with and exploits the microbiota and the host epithelium to infect and persist. We provide an overview of C. difficile virulence factors and their interactions with the gut to aid adhesion, cause epithelial damage and mediate persistence. Finally, we document the host responses to C. difficile, describing the immune cells and host pathways that are associated and triggered during C. difficile infection.

Butyrate's role in human health and the current progress towards its clinical application to treat gastrointestinal disease

Butyrate is a key energy source for colonocytes and is produced by the gut microbiota through fermentation of dietary fiber. Butyrate is a histone deacetylase inhibitor and also signals through three G-protein coupled receptors. It is clear that butyrate has an important role in gastrointestinal health and that butyrate levels can impact both host and microbial functions that are intimately coupled with each other. Maintaining optimal butyrate levels improves gastrointestinal health in animal models by supporting colonocyte function, decreasing inflammation, maintaining the gut barrier, and promoting a healthy microbiome. Butyrate has also shown protective actions in the context of intestinal diseases such as inflammatory bowel disease, graft-versus-host disease of the gastrointestinal tract, and colon cancer, whereas lower levels of butyrate and/or the microbes which are responsible for producing this metabolite are associated with disease and poorer health outcomes. However, clinical efforts to increase butyrate levels in humans and reverse these negative outcomes have generated mixed results. This article discusses our current understanding of the molecular mechanisms of butyrate action with a focus on the gastrointestinal system, the links between host and microbial factors, and the efforts that are currently underway to apply the knowledge gained from the bench to bedside.

Beyond allergic progression: From molecules to microbes as barrier modulators in the gut-lung axis functionality

The "epithelial barrier hypothesis" states that a barrier dysfunction can result in allergy development due to tolerance breakdown. This barrier alteration may come from the direct contact of epithelial and immune cells with the allergens, and indirectly, through deleterious effects caused by environmental changes triggered by industrialization, pollution, and changes in the lifestyle. Apart from their protective role, epithelial cells can respond to external factors secreting IL-25 IL-33, and TSLP, provoking the activation of ILC2 cells and a Th2-biased response. Several environmental agents that influence epithelial barrier function, such as allergenic proteases, food additives or certain xenobiotics are reviewed in this paper. In addition, dietary factors that influence the allergenic response in a positive or negative way will be also described here. Finally, we discuss how the gut microbiota, its composition, and microbe-derived metabolites, such as short-chain fatty acids, alter not only the gut but also the integrity of distant epithelial barriers, focusing this review on the gut-lung axis.

The Crosstalk between Microbiome and Mitochondrial Homeostasis in Neurodegeneration

Mitochondria are highly dynamic organelles that serve as the primary cellular energy-generating system. Apart from ATP production, they are essential for many biological processes, including calcium homeostasis, lipid biogenesis, ROS regulation and programmed cell death, which collectively render them invaluable for neuronal integrity and function. Emerging evidence indicates that mitochondrial dysfunction and altered mitochondrial dynamics are crucial hallmarks of a wide variety of neurodevelopmental and neurodegenerative conditions. At the same time, the gut microbiome has been implicated in the pathogenesis of several neurodegenerative disorders due to the bidirectional communication between the gut and the central nervous system, known as the gut-brain axis. Here we summarize new insights into the complex interplay between mitochondria, gut microbiota and neurodegeneration, and we refer to animal models that could elucidate the underlying mechanisms, as well as novel interventions to tackle age-related neurodegenerative conditions, based on this intricate network.

Gas-Mediated Intestinal Microbiome Regulation Prompts the Methanol Extract of Schizonepetae Spica to Relieve Colitis

Intestinal dysbiosis plays an important role in the pathogenesis of colitis (UC). Schizonepetae Herba can achieve anti-inflammatory effects as a medicine and food homologous vegetable. Luteolin, eriodictyol, fisetin, and kaempferol are the main anti-inflammatory active compounds obtained through mass spectrometry from the methanol extract of Schizonepetae Spica (JJSM). JJSM intervention resulted in attenuated weight loss, high disease-activity-index score, colon length shortening and colonic pathological damage in DSS-induced colitis mice. Interestingly, hydrogen sulfide (H₂S) was inhibited remarkably, which is helpful to elucidate the relationship between active substance and intestinal flora. Furthermore, JJSM administration improved intestinal flora with down-regulating the abundance of harmful bacteria such as Clostridiales and Desulfovibrio and up-regulating the abundance of beneficial bacteria such as Muribaculaceae and Ligolactobacillus and enhanced the production of SCFAs. It is worth noticing that Desulfovibrio is related to the production of intestinal gas H₂S. The elevated levels of Desulfovibrio and H₂S will hasten the onset of colitis, which is a crucial risk factor for colitis. The results displayed that JJSM could considerably ameliorate colitis by rebuilding H₂S-related intestinal flora, which provides a new therapeutic strategy for Schizonepetae Spica to be utilized as a functional food and considered as an emerging candidate for intestinal inflammation.

Immunological consequences of microbiome-based therapeutics

The complex network of microscopic organisms living on and within humans, collectively referred to as the microbiome, produce wide array of biologically active molecules that shape our health. Disruption of the microbiome is associated with susceptibility to a range of diseases such as cancer, diabetes, allergy, obesity, and infection. A new series of next-generation microbiome-based therapies are being developed to treat these diseases by transplanting bacteria or bacterial-derived byproducts into a diseased individual to reset the recipient's microbiome and restore health. Microbiome transplantation therapy is still in its early stages of being a routine treatment option and, with a few notable exceptions, has had limited success in clinical trials. In this review, we highlight the successes and challenges of implementing these therapies to treat disease with a focus on interactions between the immune system and microbiome-based therapeutics. The immune activation status of the microbiome transplant recipient prior to transplantation has an important role in supporting bacterial engraftment. Following engraftment, microbiome transplant derived signals can modulate immune function to ameliorate disease. As novel microbiome-based therapeutics are developed, consideration of how the transplants will interact with the immune system will be a key factor in determining whether the microbiome-based transplant elicits its intended therapeutic effect.

Neglected gut microbiome: interactions of the non-bacterial gut microbiota with enteric pathogens

A diverse array of commensal microorganisms inhabits the human intestinal tract. The most abundant and most studied members of this microbial community are undoubtedly bacteria. Their important role in gut physiology, defense against pathogens, and immune system education has been well documented over the last decades. However, the gut microbiome is not restricted to bacteria. It encompasses the entire breadth of microbial life: viruses, archaea, fungi, protists, and parasitic worms can also be found in the gut. While less studied than bacteria, their divergent but important roles during health and disease have become increasingly more appreciated. This review focuses on these understudied members of the gut microbiome. We will detail the composition and development of these microbial communities and will specifically highlight their functional interactions with enteric pathogens, such as species of the family Enterobacteriaceae. The interactions can be direct through physical interactions, or indirect through secreted metabolites or modulation of the immune response. We will present general concepts and specific examples of how non-bacterial gut communities modulate bacterial pathogenesis and present an outlook for future gut microbiome research that includes these communities.

Treatment of peanut allergy and colitis in mice via the intestinal release of butyrate from polymeric micelles

The microbiome modulates host immunity and aids the maintenance of tolerance in the gut, where microbial and food-derived antigens are abundant. Yet modern dietary factors and the excessive use of antibiotics have contributed to the rising incidence of food allergies, inflammatory bowel disease and other non-communicable chronic diseases associated with the depletion of beneficial taxa, including butyrate-producing Clostridia. Here we show that intragastrically delivered neutral and negatively charged polymeric micelles releasing butyrate in different regions of the intestinal tract restore barrier-protective responses in mouse models of colitis and of peanut allergy. Treatment with the butyrate-releasing micelles increased the abundance of butyrate-producing taxa in Clostridium cluster XIVa, protected mice from an anaphylactic reaction to a peanut challenge and reduced disease severity in a T-cell-transfer model of colitis. By restoring microbial and mucosal homoeostasis, butyrate-releasing micelles may function as an antigen-agnostic approach for the treatment of allergic and inflammatory diseases.

Exogenous antibiotic resistance gene contributes to intestinal inflammation by modulating the gut microbiome and inflammatory cytokine responses in mouse

Dysregulation of the gut microbiota by environmental factors is associated with a variety of autoimmune and immune-mediated diseases. In addition, naturally-occurring extracellular antibiotic resistance genes (eARGs) might directly enter the gut via the food chain. However, following gut microbiota exposure to eARGs, the ecological processes shaping the microbiota community assembly, as well as the interplay between the microbiota composition, metabolic function, and the immune responses, are not well understood. Increasing focus on the One Health approach has led to an urgent need to investigate the direct health damage caused by eARGs. Herein, we reveal the significant influence of eARGs on microbiota communities, strongly driven by stochastic processes. How eARGs-stimulate variations in the composition and metabolomic function of the gut microbiota led to cytokine responses in mice of different age and sex were investigated. The results revealed that cytokines were significantly associated with immunomodulatory microbes, metabolites, and ARGs biomarkers. Cytokine production was associated with specific metabolic pathways (arachidonic acid and tryptophan metabolic pathways), as confirmed by ex vivo cytokine responses and recovery experiments in vivo. Furthermore, the gut microbial profile could be applied to accurately predict the degree of intestinal inflammation ascribed to the eARGs (area under the curve = 0.9616). The present study provided a comprehensive understanding of the influence of an eARGs on immune responses and intestinal barrier damage, shedding light on the interplay between eARGs, microbial, metabolites, and the gut antibiotic resistome in modulating the human immune system.

ALZHEIMER'S DISEASE AND ITS RELATIONSHIP WITH THE MICROBIOTA-GUT-BRAIN AXIS

BACKGROUND

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disease, characterized by the accumulation of amyloid plaques and neurofibrillary tangles in the brain. Several pathways enable bidirectional communication between the central nervous system (CNS), the intestine and its microbiota, constituting the microbiota-gut-brain axis.

OBJECTIVE

Review the pathophysiology of AD, relate it to the microbiota-gut-brain axis and discuss the possibility of using probiotics in the treatment and/or prevention of this disease.

METHODS

Search of articles from the PubMed database published in the last 5 years (2017 to 2022) structure the narrative review.

RESULTS

The composition of the gut microbiota influences the CNS, resulting in changes in host behavior and may be related to the development of neurodegenerative diseases. Some metabolites produced by the intestinal microbiota, such as trimethylamine N-oxide (TMAO), may be involved in the pathogenesis of AD, while other compounds produced by the microbiota during the fermentation of food in the intestine, such as D-glutamate and fatty acids short chain, are beneficial in cognitive function. The consumption of live microorganisms beneficial to health, known as probiotics, has been tested in laboratory animals and humans to evaluate the effect on AD.

CONCLUSION

Although there are few clinical trials evaluating the effect of probiotic consumption in humans with AD, the results to date indicate a beneficial contribution of the use of probiotics in this disease.

Effects of antimicrobials on the gastrointestinal microbiota of dogs and cats

Among several environmental factors, exposure to antimicrobials has been in the spotlight as a cause of profound and long-term disturbance of the intestinal microbiota. Antimicrobial-induced dysbiosis is a general term and includes decreases in microbial richness and diversity, loss of beneficial bacterial groups, blooms of intestinal pathogens and alterations in the metabolic functions and end-products of the microbiota. Mounting evidence from human and experimental animal studies suggest an association between antimicrobial-induced dysbiosis and susceptibility to gastrointestinal, metabolic, endocrine, immune and neuropsychiatric diseases. These associations are commonly stronger after early life exposure to antimicrobials, a period during which maturation of the microbiota and immune system take place in parallel. In addition, these associations commonly become stronger as the number of antimicrobial courses increases. The repeatability of these findings among different studies as well as the presence of a dose-dependent relationship between antimicrobial exposure and disease development collectively require careful consideration of the need for antimicrobial use. There are limited studies are available in dogs and cats regarding the long-term effects of antimicrobials on the microbiota and subsequent susceptibility to diseases. This review discusses the effects of antimicrobials on the gastrointestinal microbiota and the most important associations between antimicrobial-induced dysbiosis and diseases in humans, dogs, and cats.

Microbiome in Anxiety and Other Psychiatric Disorders

Initial studies suggested that the fluctuations in the quantity, variety, and composition of the gut microbiota can significantly affect disease processes. This change in the gut microbiota causing negative health benefits was coined dysbiosis. Initial research focused on gastrointestinal illnesses. However, the gut microbiome was found to affect more than just gastrointestinal diseases. Numerous studies have proven that the gut microbiome can influence neuropsychiatric diseases such as Parkinson's disease, Alzheimer's disease, and multiple sclerosis.

Gut microbiota modulation in patients with non-alcoholic fatty liver disease: Effects of current treatments and future strategies

Non-alcoholic fatty liver disease (NAFLD) is frequently associated with metabolic disorders, being highly prevalent in obese and diabetic patients. Many concomitant factors that promote systemic and liver inflammation are involved in NAFLD pathogenesis, with a growing body of evidence highlighting the key role of the gut microbiota. Indeed, the gut-liver axis has a strong impact in the promotion of NAFLD and in the progression of the wide spectrum of its manifestations, claiming efforts to find effective strategies for gut microbiota modulation. Diet is among the most powerful tools; Western diet negatively affects intestinal permeability and the gut microbiota composition and function, selecting pathobionts, whereas Mediterranean diet fosters health-promoting bacteria, with a favorable impact on lipid and glucose metabolism and liver inflammation. Antibiotics and probiotics have been used to improve NAFLD features, with mixed results. More interestingly, medications used to treat NAFLD-associated comorbidities may also modulate the gut microbiota. Drugs for the treatment of type 2 diabetes mellitus (T2DM), such as metformin, glucagon-like peptide-1 (GLP-1) agonists, and sodium-glucose cotransporter (SGLT) inhibitors, are not only effective in the regulation of glucose homeostasis, but also in the reduction of liver fat content and inflammation, and they are associated with a shift in the gut microbiota composition towards a healthy phenotype. Even bariatric surgery significantly changes the gut microbiota, mostly due to the modification of the gastrointestinal anatomy, with a parallel improvement in histological features of NAFLD. Other options with promising effects in reprogramming the gut-liver axis, such as fecal microbial transplantation (FMT) and next-generation probiotics deserve further investigation for future inclusion in the therapeutic armamentarium of NAFLD.

NAD Supplement Alleviates Intestinal Barrier Injury Induced by Ethanol Via Protecting Epithelial Mitochondrial Function

BACKGROUND

The epithelial tight junction is an important intestinal barrier whose disruption can lead to the release of harmful intestinal substances into the circulation and cause damage to systemic injury. The maintenance of intestinal epithelial tight junctions is closely related to energy homeostasis and mitochondrial function. Nicotinamide riboside (NR) is a NAD booster that can enhance mitochondrial biogenesis in liver. However, whether NR can prevent ethanol-induced intestinal barrier dysfunction and the underlying mechanisms remain unclear.

METHODS

We applied the mouse NIAAA model (chronic plus binge ethanol feeding) and Caco-2 cells to explore the effects of NR on ethanol-induced intestinal barrier dysfunction and the underlying mechanisms. NAD homeostasis and mitochondrial function were measured. In addition, knockdown of SirT1 in Caco-2 cells was further applied to explore the role of SirT1 in the protection of NR.

RESULTS

We found that ethanol increased intestinal permeability, increased the release of LPS into the circulation and destroyed the intestinal epithelial barrier structure in mice. NR supplementation attenuated intestinal barrier injury. Both in vivo and in vitro experiments showed that NR attenuated ethanol-induced decreased intestinal tight junction protein expressions and maintained NAD homeostasis. In addition, NR supplementation activated SirT1 activity and increased deacetylation of PGC-1α, and reversed ethanol-induced mitochondrial dysfunction and mitochondrial biogenesis. These effects were diminished with the knockdown of SirT1 in Caco-2 cells.

CONCLUSION

Boosting NAD by NR alleviates ethanol-induced intestinal epithelial barrier damage via protecting mitochondrial function in a SirT1-dependent manner.

Ghrelin Alleviates Experimental Ulcerative Colitis in Old Mice and Modulates Colonocyte Metabolism via PPARγ Pathway

There is a growing prevalence of inflammatory bowel disease (IBD), a chronic inflammatory condition of the gastrointestinal tract, among the aging population. Ghrelin is a gut hormone that, in addition to controlling feeding and energy metabolism, has been shown to exert anti-inflammatory effects; however, the effect of ghrelin in protecting against colitis in old mice has not been assessed. Here, we subjected old female C57BL/6J mice to dextran sulfate sodium (DSS) in drinking water for six days, then switched back to normal drinking water, administered acyl-ghrelin or vehicle control from day 3 to 13, and monitored disease activities throughout the disease course. Our results showed that treatment of old mice with acyl-ghrelin attenuated DSS-induced colitis. Compared to the DSS group, ghrelin treatment decreased levels of the inflammation marker S100A9 in the colons collected on day 14 but not on day 8, suggesting that the anti-inflammatory effect was more prominent in the recovery phase. Ghrelin treatment also significantly reduced F4/80 and interleukin-17A on day 14. Moreover, acyl-ghrelin increased mitochondrial respiration and activated transcriptional activity of the peroxisome proliferator-activated receptor gamma (PPARγ) in Caco-2 cells. Together, our data show that ghrelin alleviated DSS-induced colitis, suggesting that ghrelin may promote tissue repair in part through regulating epithelial metabolism via PPARγ mediated signaling.

High-Density Lipoprotein Cholesterol as a Potential Medium between Depletion of Lachnospiraceae Genera and Hypertension under a High-Calorie Diet

Gut microbial dysbiosis has been associated with hypertension. An extremely high incidence of essential hypertension was found in the Han and the Yugur people who resided in Sunan County in China's nomadic steppes, with little population movement. To investigate gut microbial contributions to this high incidence of hypertension, we recruited a total of 1, 242 Yugur and Han people, who had resided in Sunan County for more than 15 years and accounted for 3% of the local population. The epidemiological survey of 1,089 individuals indicated their nearly 1.8-times-higher prevalence of hypertension (38.2 to 43.3%) than the average in China (23.2%), under a special high-calorie diet based on wheat, cattle, mutton, and animal offal. Investigations of the fecal microbiota of another cohort of 153 individuals revealed that certain Lachnospiraceae genera were positively correlated with high-density lipoprotein cholesterol (HDL-C) but negatively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP). HDL-C was negatively correlated with SBP and DBP. We further observed that the serum butyrate content was lower in both Han and Yugur people with hypertension than in those without hypertension. This study gives novel insight into the role of gut microbial dysbiosis in hypertension modulation under a high-calorie diet, where the notable depletion of Lachnospiraceae genera might lead to less production of butyrate, contributing to the lower level of HDL-C and elevating blood pressure in hypertension. IMPORTANCE Dietary nutrients can be converted by the gut microbiota into metabolites such as short-chain fatty acids, which may serve as disease-preventing agents in hypertension. Due to the limited population mobility and unique high-calorie dietary habits, the cohort of this study can serve as a representative cohort for elucidating the associations between the gut microbiota and hypertension under a high-calorie diet. Moreover, low levels of HDL-C have previously been associated with an increased risk of various cardiovascular diseases (CVDs). Our findings provide new insight showing that low levels of HDL-C may be a potential medium between the depletion of Lachnospiraceae genera and hypertension under a high-calorie diet, which might also be a potential candidate for other CVDs.

Effect of Mannan-rich fraction supplementation on commercial broiler intestinum tenue and cecum microbiota

BACKGROUND

The broiler gastrointestinal microbiome is a potent flock performance modulator yet may also serve as a reservoir for pathogen entry into the food chain. The goal of this project was to characterise the effect of mannan rich fraction (MRF) supplementation on microbiome diversity and composition of the intestinum tenue and cecum of commercial broilers. This study also aimed to address some of the intrinsic biases that exist in microbiome studies which arise due to the extensive disparity in 16S rRNA gene copy numbers between bacterial species and due to large intersample variation.

RESULTS

We observed a divergent yet rich microbiome structure between different anatomical sites and observed the explicit effect MRF supplementation had on community structure, diversity, and pathogen modulation. Birds supplemented with MRF displayed significantly higher species richness in the cecum and significantly different bacterial community composition in each gastrointestinal (GI) tract section. Supplemented birds had lower levels of the zoonotic pathogens Escherichia coli and Clostridioides difficile across all three intestinum tenue sites highlighting the potential of MRF supplementation in maintaining food chain integrity. Higher levels of probiotic genera (eg. Lactobacillus and Blautia) were also noted in the MRF supplemented birds. Following MRF supplementation, the cecum displayed higher relative abundances of both short chain fatty acid (SFCA) synthesising bacteria and SCFA concentrations.

CONCLUSIONS

Mannan rich fraction addition has been observed to reduce the bioburden of pathogens in broilers and to promote greater intestinal tract microbial biodiversity. This study is the first, to our knowledge, to investigate the effect of mannan-rich fraction supplementation on the microbiome associated with different GI tract anatomical geographies. In addition to this novelty, this study also exploited machine learning and biostatistical techniques to correct the intrinsic biases associated with microbiome community studies to enable a more robust understanding of community structure.

Repurposing a Drug Targeting Inflammatory Bowel Disease for Lowering Hypertension

Background The gut and gut microbiota, which were previously neglected in blood pressure regulation, are becoming increasingly recognized as factors contributing to hypertension. Diseases affecting the gut such as inflammatory bowel disease (IBD) present with aberrant energy metabolism of colonic epithelium and gut dysbiosis, both of which are also mechanisms contributing to hypertension. We reasoned that current measures to remedy deficits in colonic energy metabolism and dysbiosis in IBD could also ameliorate hypertension. Among them, 5-aminosalicylic acid (5-ASA; mesalamine) is a PPARγ (peroxisome proliferator-activated receptor gamma) agonist. It attenuates IBD by a dual mechanism of selectively enhancing colonic epithelial cell energy metabolism and ameliorating gut dysbiosis. Methods and Results A total of 2 groups of 11- to 12-week-old male, hypertensive, Dahl salt-sensitive (S) rats were gavaged with (n=10) or without (n=10) 5-aminosalicylic acid (150 mg/kg) for 4 weeks. Rats receiving 5-aminosalicylic acid treatment had a lower mean blood pressure than controls (145±3 mm Hg versus 153±4 mm Hg; P<0.0001). This reduction in blood pressure was accompanied by increased activity of PPARγ, increased expression of energy metabolism-related genes, and lowering of the Firmicutes/Bacteroidetes ratio in the colon, the reduction of which is a marker for the correction of gut dysbiosis. Furthermore, these data were consistent with the American Gut Project wherein the Firmicutes/Bacteroidetes ratio of non-IBD (n=611) patients was significantly lower than patients with IBD (n=631). Conclusions 5-Aminosalicylic acid could be repurposed for hypertension by specifically enhancing the gut energy metabolism and correction of microbiota dysbiosis.

Integrated multi-omics analyses reveal effects of empagliflozin on intestinal homeostasis in high-fat-diet mice

Obesity has become a global epidemic, associated with several chronic complications. The intestinal microbiome is a critical regulator of metabolic homeostasis and obesity. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, has putative anti-obesity effects. In this study, we used multi-omics analysis to determine whether empagliflozin regulates metabolism in an obese host through the intestinal microbiota. Compared with obese mice, the empagliflozin-treated mice had a higher species diversity of gut microbiota, characterized by a reduction in the Firmicutes/Bacteroides ratio. Metabolomic analysis unambiguously identified 1,065 small molecules with empagliflozin affecting metabolites mainly enriched in amino acid metabolism, such as tryptophan metabolism. RNA sequencing results showed that immunoglobulin A and peroxisome proliferator-activated receptor signaling pathways in the intestinal immune network were activated after empagliflozin treatment. This integrative analysis highlighted that empagliflozin maintains intestinal homeostasis by modulating gut microbiota diversity and tryptophan metabolism. This will inform the development of therapies for obesity based on host-microbe interactions.

Plasticity of the adult human small intestinal stoma microbiota

The human distal small intestine (ileum) has a distinct microbiota, but human studies investigating its composition and function have been limited by the inaccessibility of the ileum without purging and/or deep intubation. We investigated inherent instability, temporal dynamics, and the contribution of fed and fasted states using stoma samples from cured colorectal cancer patients as a non-invasive access route to the otherwise inaccessible small and large intestines. Sequential sampling of the ileum before and after stoma formation indicated that ileostoma microbiotas represented that of the intact small intestine. Ileal and colonic stoma microbiotas were confirmed as distinct, and two types of instability in ileal host-microbial relationships were observed: inter-digestive purging followed by the rapid postprandial blooming of bacterial biomass and sub-strain appearance and disappearance within individual taxa after feeding. In contrast to the relative stability of colonic microbiota, the human small intestinal microbiota biomass and its sub-strain composition can be highly dynamic.

Stable isotope tracing in vivo reveals a metabolic bridge linking the microbiota to host histone acetylation

The gut microbiota influences acetylation on host histones by fermenting dietary fiber into butyrate. Although butyrate could promote histone acetylation by inhibiting histone deacetylases, it may also undergo oxidation to acetyl-coenzyme A (CoA), a necessary cofactor for histone acetyltransferases. Here, we find that epithelial cells from germ-free mice harbor a loss of histone H4 acetylation across the genome except at promoter regions. Using stable isotope tracing in vivo with 13C-labeled fiber, we demonstrate that the microbiota supplies carbon for histone acetylation. Subsequent metabolomic profiling revealed hundreds of labeled molecules and supported a microbial contribution to host fatty acid metabolism, which declined in response to colitis and correlated with reduced expression of genes involved in fatty acid oxidation. These results illuminate the flow of carbon from the diet to the host via the microbiota, disruptions to which may affect energy homeostasis in the distal gut and contribute to the development of colitis.

Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation

Celiac disease (CD) is a complex multi-organ disease with a high prevalence of extra-intestinal involvement, including neurological and psychiatric manifestations, such as cerebellar ataxia, peripheral neuropathy, epilepsy, headache, cognitive impairment, and depression. However, the mechanisms behind the neurological involvement in CD remain controversial. Recent evidence shows these can be related to gluten-mediated pathogenesis, including antibody cross-reaction, deposition of immune-complex, direct neurotoxicity, and in severe cases, vitamins or nutrients deficiency. Here, we have summarized new evidence related to gut microbiota and the so-called "gut-liver-brain axis" involved in CD-related neurological manifestations. Additionally, there has yet to be an agreement on whether serological or neurophysiological findings can effectively early diagnose and properly monitor CD-associated neurological involvement; notably, most of them can revert to normal with a rigorous gluten-free diet. Moving from a molecular level to a symptom-based approach, clinical, serological, and neurophysiology data might help to disentangle the many-faceted interactions between the gut and brain in CD. Eventually, the identification of multimodal biomarkers might help diagnose, monitor, and improve the quality of life of patients with "neuroCD".

Fecal Microbiota Transplantation and Other Gut Microbiota Manipulation Strategies

The gut microbiota is composed of bacteria, archaea, phages, and protozoa. It is now well known that their mutual interactions and metabolism influence host organism pathophysiology. Over the years, there has been growing interest in the composition of the gut microbiota and intervention strategies in order to modulate it. Characterizing the gut microbial populations represents the first step to clarifying the impact on the health/illness equilibrium, and then developing potential tools suited for each clinical disorder. In this review, we discuss the current gut microbiota manipulation strategies available and their clinical applications in personalized medicine. Among them, FMT represents the most widely explored therapeutic tools as recent guidelines and standardization protocols, not only for intestinal disorders. On the other hand, the use of prebiotics and probiotics has evidence of encouraging findings on their safety, patient compliance, and inter-individual effectiveness. In recent years, avant-garde approaches have emerged, including engineered bacterial strains, phage therapy, and genome editing (CRISPR-Cas9), which require further investigation through clinical trials.

Colonocyte-derived lactate promotes E. coli fitness in the context of inflammation-associated gut microbiota dysbiosis

BACKGROUND

Intestinal inflammation disrupts the microbiota composition leading to an expansion of Enterobacteriaceae family members (dysbiosis). Associated with this shift in microbiota composition is a profound change in the metabolic landscape of the intestine. It is unclear how changes in metabolite availability during gut inflammation impact microbial and host physiology.

RESULTS

We investigated microbial and host lactate metabolism in murine models of infectious and non-infectious colitis. During inflammation-associated dysbiosis, lactate levels in the gut lumen increased. The disease-associated spike in lactate availability was significantly reduced in mice lacking the lactate dehydrogenase A subunit in intestinal epithelial cells. Commensal E. coli and pathogenic Salmonella, representative Enterobacteriaceae family members, utilized lactate via the respiratory L-lactate dehydrogenase LldD to increase fitness. Furthermore, mice lacking the lactate dehydrogenase A subunit in intestinal epithelial cells exhibited lower levels of inflammation in a model of non-infectious colitis.

CONCLUSIONS

The release of lactate by intestinal epithelial cells during gut inflammation impacts the metabolism of gut-associated microbial communities. These findings suggest that during intestinal inflammation and dysbiosis, changes in metabolite availability can perpetuate colitis-associated disturbances of microbiota composition. Video Abstract.

MlrA, a MerR family regulator in Vibrio cholerae, senses the anaerobic signal in the small intestine of the host to promote bacterial intestinal colonization

Vibrio cholerae (V. cholerae), one of the most important bacterial pathogens in history, is a gram-negative motile bacterium that causes fatal pandemic disease in humans via oral ingestion of contaminated water or food. This process involves the coordinated actions of numerous regulatory factors. The MerR family regulators, which are widespread in prokaryotes, have been reported to be associated with pathogenicity. However, the role of the MerR family regulators in V. cholerae virulence remains unknown. Our study systematically investigated the influence of MerR family regulators on intestinal colonization of V. cholerae within the host. Among the five MerR family regulators, MlrA was found to significantly promote the colonization capacity of V. cholerae in infant mice. Furthermore, we revealed that MlrA increases bacterial intestinal colonization by directly enhancing the expression of tcpA, which encodes one of the most important virulence factors in V. cholerae, by binding to its promoter region. In addition, we revealed that during infection, mlrA is activated by anaerobic signals in the small intestine of the host through Fnr. In summary, our findings reveal a MlrA-mediated virulence regulation pathway that enables V. cholerae to sense environmental signals at the infection site to precisely activate virulence gene expression, thus providing useful insights into the pathogenic mechanisms of V. cholerae.

Investigating dysbiosis and microbial treatment strategies in inflammatory bowel disease based on two modified Koch's postulates

Inflammatory bowel disease (IBD) is a chronic non-specific inflammatory disease that occurs in the intestinal tract. It is mainly divided into two subtypes, i.e., the Crohn's disease (CD) and ulcerative colitis (UC). At present, its pathogenesis has not been fully elucidated, but it has been generally believed that the environment, immune disorders, genetic susceptibility, and intestinal microbes are the main factors for the disease pathogenesis. With the development of the sequencing technology, microbial factors have received more and more attention. The gut microbiota is in a state of precise balance with the host, in which the host immune system is tolerant to immunogenic antigens produced by gut commensal microbes. In IBD patients, changes in the balance between pathogenic microorganisms and commensal microbes lead to changes in the composition and diversity of gut microbes, and the balance between microorganisms and the host would be disrupted. This new state is defined as dysbiosis. It has been confirmed, in both clinical and experimental settings, that dysbiosis plays an important role in the occurrence and development of IBD, but the causal relationship between dysbiosis and inflammation has not been elucidated. On the other hand, as a classic research method for pathogen identification, the Koch's postulates sets the standard for verifying the role of pathogens in disease. With the further acknowledgment of the disease pathogenesis, it is realized that the traditional Koch's postulates is not applicable to the etiology research (determination) of infectious diseases. Thus, many researchers have carried out more comprehensive and complex elaboration of Koch's postulates to help people better understand and explain disease pathogenesis through the improved Koch's postulates. Therefore, focusing on the new perspective of the improved Koch's postulates is of great significance for deeply understanding the relationship between dysbiosis and IBD. This article has reviewed the studies on dysbiosis in IBD, the use of microbial agents in the treatment of IBD, and their relationship to the modified Koch's postulates.

Host circadian behaviors exert only weak selective pressure on the gut microbiome under stable conditions but are critical for recovery from antibiotic treatment

The circadian rhythms of hosts dictate an approximately 24 h transformation in the environment experienced by their gut microbiome. The consequences of this cyclic environment on the intestinal microbiota are barely understood and are likely to have medical ramifications. Can daily rhythmicity in the gut act as a selective pressure that shapes the microbial community? Moreover, given that several bacterial species have been reported to exhibit circadian rhythms themselves, we test here whether a rhythmic environment is a selective pressure that favors clock-harboring bacteria that can anticipate and prepare for consistent daily changes in the environment. We observed that the daily rhythmicity of the mouse gut environment is a stabilizing influence that facilitates microbiotal recovery from antibiotic perturbation. The composition of the microbiome recovers to pretreatment conditions when exposed to consistent daily rhythmicity, whereas in hosts whose feeding and activity patterns are temporally disrupted, microbiotal recovery is incomplete and allows potentially unhealthy opportunists to exploit the temporal disarray. Unexpectedly, we found that in the absence of antibiotic perturbation, the gut microbiome is stable to rhythmic versus disrupted feeding and activity patterns. Comparison of our results with those of other studies reveals an intriguing correlation that a stable microbiome may be resilient to one perturbation alone (e.g., disruption of the daily timing of host behavior and feeding), but not to multiple perturbations in combination. However, after a perturbation of the stable microbiome, a regular daily pattern of host behavior/feeding appears to be essential for the microbiome to recover to the original steady state. Given the inconsistency of daily rhythms in modern human life (e.g., shiftwork, social jet-lag, irregular eating habits), these results emphasize the importance of consistent daily rhythmicity to optimal health not only directly to the host, but also indirectly by preserving the host's microbiome in the face of perturbations.

The Importance of Nutritional Aspects in the Assessment of Inflammation and Intestinal Barrier in Patients with Inflammatory Bowel Disease

Intestinal inflammation in inflammatory bowel disease (IBD) is closely linked to nutrition. This study aimed to evaluate associations between nutritional, inflammatory, and intestinal barrier parameters in patients with IBD. We assessed nutritional status, fecal short-chain fatty acid profile, serum cytokine levels, and mRNA expression of enzymes and tight junction proteins in intestinal biopsies obtained from 35 patients, including 11 patients with inactive IBD, 18 patients with active IBD, and six controls. Patients with active IBD were characterized by hypoalbuminemia, fluctuations in body weight, and restriction of fiber-containing foods. In addition, they had significantly reduced levels of isovaleric acid and tended to have lower levels of butyric, acetic, and propionic acids. Patients with active IBD had higher mRNA expression of peroxisome proliferator-activated receptor γ and inducible nitric oxide synthase, and lower mRNA expression of claudin-2 and zonula occludens-1, compared with patients with inactive IBD. Moreover, patients with a body mass index (BMI) of ≥25 kg/m2 had higher median tumor necrosis factor-α levels that those with a lower BMI. We comprehensively evaluated inflammatory parameters in relation to IBD activity and nutritional status. The discrepancies between proinflammatory and anti-inflammatory parameters depending on IBD activity may be related to nutritional factors, including diet and abnormal body weight.

Jatrorrhizine alleviates ulcerative colitis via regulating gut microbiota and NOS2 expression

Background

The natural protoberberine jatrorrhizine (JA) is reported to have several medicinal properties and a significant effect on the gut microbiota of mice. The regulation of gut microbiota is generally known to play an important role in the intestinal mucosal immune response to ulcerative colitis (UC). However, whether JA can be used in the treatment of UC is still unclear. Our study aimed to investigate the underlying therapeutic effects and mechanisms of JA in treating colitis.

Results

Compared with the DSS-induced colitis model group, the JA + DSS treated group had more significant improvements in weight loss, disease activity index score, colon length shortening, and pathological inflammation. 16s rRNA sequencing analysis showed that JA treatment protected colitis mice against DSS-induced disturbance of gut microbiota. At the phylum level, reductions in Deferribacteres and Proteobacteria were observed in the JA-treated group; At the genus level, the JA-treated group showed an increased relative abundance of Akkermansia and decreased abundance of Escherichia-Shigella, Desulfovibrio, Mucispirillum, etc. Network pharmacology was then used to screen out five drug-disease target genes (NOS2, ESR1, CALM1, CALM2, CALM3). Transcriptomics analysis further validated that the NOS2 expression was significantly reduced in colon tissue of JA-administered mice compared with DSS control mice. Additionally, analysis of correlation suggested that NOS2 expression was negatively correlated with the relative abundance of AKKermansia and positively correlated with Desulfovibrio, Rikenella.

Conclusion

JA alleviates ulcerative colitis via regulating gut microbiota and NOS2 expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-022-00514-z.

RETRACTED: Improvement of extraction from Hericium erinaceus on the gut-brain axis in AD-like mice

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the lead author, Dr. Diling Chen. Dr. Chen alerted the Editor-in-Chief that data previously published in Aging (Albany NY). 2020 Jan 6; 12:260-287 https://doi.org/10.18632/aging.102614 were accidently reused in the above-referenced Brain Research article. Dr. Chen is a co-author on both articles. The reused content pertains to the fecal transplantation data of the model group, represented by Figure 2 in the Aging article and Figure 5 in the Brain Research article. Dr. Chen did not carefully check the data published by the team before the final submission, resulting in repeated use. The lead author states further that it was an honest mistake, and the team had no intention to plagiarize previously published material. All authors were notified and all are in agreement with the retraction. The authors apologize to the scientific community for any inconvenience or challenges resulting from the publication and retraction of this article.

Sodium butyrate ameliorates thiram-induced tibial dyschondroplasia and gut microbial dysbiosis in broiler chickens

Thiram is a dithiocarbamate pesticide widely used in agriculture as a fungicide for storing grains to prevent fungal diseases. However, its residues have threatened the safety of human beings and the stability of the ecosystem by causing different disease conditions, e.g., tibial dyschondroplasia (TD), which results in a substantial economic loss for the poultry industry. So, the research on TD has a great concern for the industry and the overall GDP of a country. In current study, we investigated whether different concentrations (300, 500, and 700 mg/kg) of sodium butyrate alleviated TD induced under acute thiram exposure by regulating osteogenic gene expression, promoting chondrocyte differentiation, and altering the gut microbial community. According to the findings, sodium butyrate restored clinical symptoms in broilers, improved growth performance, bone density, angiogenesis, and chondrocyte morphology and arrangement. It could activate the signal transduction of the Wnt/β-catenin pathway, regulate the expression of GSK-3β and β-catenin, and further promote the production of osteogenic transcription factors Runx2 and OPN for restoration of lameness. In addition, the 16S rRNA sequencing revealed a significantly different community composition among the groups. The TD group increased the abundance of the harmful bacteria Proteobacteria, Subdoligranulum, and Erysipelatoclostridium. The sodium butyrate enriched many beneficial bacteria, such as Bacteroidetes, Verrucomicrobia, Faecalibacterium, Barnesiella, Rikenella, and Butyricicoccus, etc., especially at the concentration of 500 mg/kg. The mentioned concentration significantly limited the intestinal disorders under thiram exposure, and restored bone metabolism.