Interleukin-22-mediated host glycosylation prevents Clostridioides difficile infection by modulating the metabolic activity of the gut microbiota

IL-22 promotes mucin-type O-glycosylation and MATH1+ cell-mediated amelioration of intestinal inflammation

The interleukin (IL)-22 cytokine can be protective or inflammatory in the intestine. It is unclear if IL-22 receptor (IL-22Ra1)-mediated protection involves a specific type of intestinal epithelial cell (IEC). By using a range of IEC type-specific Il22Ra1 conditional knockout mice and a dextran sulfate sodium (DSS) colitis model, we demonstrate that IL-22Ra1 signaling in MATH1+ cells (goblet and progenitor cells) is essential for maintaining the mucosal barrier and intestinal tissue regeneration. The IL-22Ra1 signaling in IECs promotes mucin core-2 O-glycan extension and induces beta-1,3-galactosyltransferase 5 (B3GALT5) expression in the colon. Adenovirus-mediated expression of B3galt5 is sufficient to rescue Il22Ra1IEC mice from DSS colitis. Additionally, we observe a reduction in the expression of B3GALT5 and the Tn antigen, which indicates defective mucin O-glycan, in the colon tissue of patients with ulcerative colitis. Lastly, IL-22Ra1 signaling in MATH1+ progenitor cells promotes organoid regeneration after DSS injury. Our findings suggest that IL-22-dependent protective responses involve O-glycan modification, proliferation, and differentiation in MATH1+ progenitor cells.

Deficiency of IL-22-binding protein enhances the ability of the gut microbiota to protect against enteric pathogens

Interleukin 22 (IL-22) promotes intestinal barrier integrity, stimulating epithelial cells to enact defense mechanisms against enteric infections, including the production of antimicrobial peptides. IL-22 binding protein (IL-22BP) is a soluble decoy encoded by the Il22ra2 gene that decreases IL-22 bioavailability, attenuating IL-22 signaling. The impact of IL-22BP on gut microbiota composition and functioning is poorly understood. We found that Il22ra2-/- mice are better protected against Clostridioides difficile and Citrobacter rodentium infections. This protection relied on IL-22-induced antimicrobial mechanisms before the infection occurred, rather than during the infection itself. Indeed, the gut microbiota of Il22ra2-/- mice mitigated infection of wild-type (WT) mice when transferred via cohousing or by cecal microbiota transplantation. Indicator species analysis of WT and Il22ra2-/- mice with and without cohousing disclosed that IL22BP deficiency yields a gut bacterial composition distinct from that of WT mice. Manipulation of dietary fiber content, measurements of intestinal short-chain fatty acids and oral treatment with acetate disclosed that resistance to C. difficile infection is related to increased production of acetate by Il22ra2-/--associated microbiota. Together, these findings suggest that IL-22BP represents a potential therapeutic target for those at risk for or with already manifest infection with this and perhaps other enteropathogens.

Clostridioides difficile infection in inflammatory bowel disease: a clinical review

INTRODUCTION

Strong clinical data demonstrate that inflammatory bowel disease (IBD) is an independent risk factor for Clostridiodes difficile infection (CDI) and suggest a globally increased prevalence and severity of C. difficile coinfection in IBD patients (CDI-IBD). In addition to elderly individuals, children are also at higher risk of CDI-IBD. Rapid diagnosis is essential since the clinical manifestations of active IBD and CDI-IBD are indistinguishable. Antibiotics have been well established in the treatment of CDI-IBD, but they do not prevent recurrence.

AREAS COVERED

Herein, the authors focus on reviewing recent research advances on the new therapies of CDI-IBD. The novel therapies include gut microbiota restoration therapies (such as prebiotics, probiotics and FMT), immunotherapy (such as vaccines and monoclonal antibodies) and diet strategies (such as groningen anti-inflammatory diet and mediterranean diet). Future extensive prospective and placebo-controlled studies are required to evaluate their efficacy and long-term safety.

EXPERT OPINION

Available studies show that the prevalence of CDI-IBD is not optimistic. Currently, potential treatment options for CDI-IBD include a number of probiotics and novel antibiotics. This review updates the knowledge on the management of CDI in IBD patients, which is timely and important for GI doctors and scientists.

N-glycoproteomic analyses of human intestinal enteroids, varying in histo-blood group geno- and phenotypes, reveal a wide repertoire of fucosylated glycoproteins

Human noroviruses, globally the main cause of viral gastroenteritis, show strain specific affinity for histo-blood group antigens (HBGA) and can successfully be propagated ex vivo in human intestinal enteroids (HIEs). HIEs established from jejunal stem cells of individuals with different ABO, Lewis and secretor geno- and phenotypes, show varying susceptibility to such infections. Using bottom-up glycoproteomic approaches we have defined and compared the N-linked glycans of glycoproteins of seven jejunal HIEs. Membrane proteins were extracted, trypsin digested, and glycopeptides enriched by hydrophilic interaction liquid chromatography and analyzed by nanoLC-MS/MS. The Byonic software was used for glycopeptide identification followed by hands-on verifications and interpretations. Glycan structures and attachment sites were identified from MS2 spectra obtained by higher-energy collision dissociation through analysis of diagnostic saccharide oxonium ions (B-ions), stepwise glycosidic fragmentation of the glycans (Y-ions), and peptide sequence ions (b- and y-ions). Altogether 694 unique glycopeptides from 93 glycoproteins were identified. The N-glycans encompassed pauci- and oligomannose, hybrid- and complex-type structures. Notably, polyfucosylated HBGA-containing glycopeptides of the four glycoproteins tetraspanin-8, carcinoembryonic antigen-related cell adhesion molecule 5, sucrose-isomaltase and aminopeptidase N were especially prominent and were characterized in detail and related to donor ABO, Lewis and secretor types of each HIE. Virtually no sialylated N-glycans were identified for these glycoproteins suggesting that terminal sialylation was infrequent compared to fucosylation and HBGA biosynthesis. This approach gives unique site-specific information on the structural complexity of N-linked glycans of glycoproteins of human HIEs and provides a platform for future studies on the role of host glycoproteins in gastrointestinal infectious diseases.

A commensal protozoan attenuates Clostridioides difficile pathogenesis in mice via arginine-ornithine metabolism and host intestinal immune response

Antibiotic-induced dysbiosis is a major risk factor for Clostridioides difficile infection (CDI), and fecal microbiota transplantation (FMT) is recommended for treating CDI. However, the underlying mechanisms remain unclear. Here, we show that Tritrichomonas musculis (T.mu), an integral member of the mouse gut commensal microbiota, reduces CDI-induced intestinal damage by inhibiting neutrophil recruitment and IL-1β secretion, while promoting Th1 cell differentiation and IFN-γ secretion, which in turn enhances goblet cell production and mucin secretion to protect the intestinal mucosa. T.mu can actively metabolize arginine, not only influencing the host's arginine-ornithine metabolic pathway, but also shaping the metabolic environment for the microbial community in the host's intestinal lumen. This leads to a relatively low ornithine state in the intestinal lumen in C. difficile-infected mice. These changes modulate C. difficile's virulence and the host intestinal immune response, and thus collectively alleviating CDI. These findings strongly suggest interactions between an intestinal commensal eukaryote, a pathogenic bacterium, and the host immune system via inter-related arginine-ornithine metabolism in the regulation of pathogenesis and provide further insights for treating CDI.

In vitro digestive properties of Dictyophora indusiata polysaccharide by steam explosion pretreatment methods

Dictyophora indusiata is medicinal and edible fungi containing various nutrients. The aim of this study was to investigate the efficient extraction and structural evolution of Dictyophora indusiata polysaccharide during the vitro digestion based on steam explosion pretreatment methods. In this study, the extraction rate of Dictyophora indusiata polysaccharide was optimized by steam explosion pretreatment methods, which was 2.46 folds that of the water extraction method. In addition, the digestion and fermentation properties of Dictyophora indusiata polysaccharide before and after steam explosion were evaluated in vitro by the changes of molecular weights, total and reducing sugars levels, surface morphology and functional groups, which showed that the structure of Dictyophora indusiata polysaccharide remained stable after salivary-gastric digestion, and partially entered the large intestine, where it could be utilized by gut microbiota. Dictyophora indusiata polysaccharide promoted the increase of beneficial bacteria Megamonas and increased the content of acetic acid, propionic acid and butyric acid, which was 2.17, 2.81, 2.43 folds that of the CON group after fermentation for 24 h, and 1.87, 2.77, 1.90 folds that of the CON group after fermentation for 48 h, respectively. This study will provide theoretical basis for the high value utilization of Dictyophora indusiata polysaccharide.

Anti-inflammatory activity of Boletus aereus polysaccharides: Involvement of digestion and gut microbiota fermentation

Boletus aereus, an edible mushroom, has gained popularity as a medicinal and functional food. This study aimed to investigate the digestive characteristics of B. aereus polysaccharide (BAP) and its effects on gut microbiota. In vitro digestion results indicated partial degradation of BAP. Furthermore, the digested BAP displayed significantly enhanced antioxidant ability. The 16S rRNA sequencing data revealed that BAP positively influenced the abundance of Phascolarctobacterium, Prevotella, and Bifidobacterium in the gut microbiota. Additionally, BAP promoted the production of short-chain fatty acids (SCFAs). Metabolites of BAP utilized by the gut microbiota effectively reduced the concentration of TNF-α, IL-1β, and NO in an LPS-stimulated RAW 264.7 cell inflammation model. Mantel tests demonstrated a strong correlation among fermentation indicators, gut microbiome composition, SCFAs, and inflammatory cytokines. Overall, this research revealed the underlying digestive and fermentation mechanisms of BAP and provided new insights into the usage of edible mushroom polysaccharides in functional food.

Metabolic network of the gut microbiota in inflammatory bowel disease

Gut dysbiosis is closely linked to the pathogenesis of inflammatory bowel disease (IBD). Emerging studies highlight the relationship between host metabolism and the modulation of gut microbiota composition through regulating the luminal microenvironment. In IBD, various disease-associated factors contribute to the significant perturbation of host metabolism. Such disturbance catalyzes the selective proliferation of specific microbial populations, particularly pathobionts such as adherent invasive Escherichia coli and oral-derived bacteria. Pathobionts employ various strategies to adapt better to the disease-associated luminal environments. In addition to the host-microbe interaction, recent studies demonstrate that the metabolic network between commensal symbionts and pathobionts facilitates the expansion of pathobionts in the inflamed gut. Understanding the metabolic network among the host, commensal symbionts, and pathobionts provides new insights into the pathogenesis of IBD and novel avenues for treating IBD.

Essential oils improve nursery pigs' performance and appetite via modulation of intestinal health and microbiota

Optimal intestinal health and functionality are essential for animal health and performance, and simultaneously intestinal nutrient transporters and intestinal peptides are also involved in appetite and feed intake control mechanisms. Given the potential of essential oil (EO) in improving animal performance and improving feed palatability, we hypothesized that dietary supplementation of cinnamaldehyde and carvacrol could improve performance and appetite of nursery pigs by modulating intestinal health and microbiota. Cinnamaldehyde (100 mg/kg), carvacrol (100 mg/kg), and their mixtures (including 50 mg/kg cinnamaldehyde and 50 mg/kg carvacrol) were supplemented into the diets of 240 nursery pigs for 42 d, and data related to performance were measured. Thereafter, the influence of EO on intestinal health, appetite and gut microbiota and their correlations were explored. EO supplementation increased (P < 0.05) the body weight, average daily gain (ADG) and average daily feed intake (ADFI) of piglets, and reduced (P < 0.05) diarrhea rates in nursery pigs. Furthermore, EO increased (P < 0.05) the intestinal absorption area and the abundance of tight junction proteins, and decreased (P < 0.05) intestinal permeability and local inflammation. In terms of intestinal development and the mucus barrier, EO promoted intestinal development and increased (P < 0.05) the number of goblet cells. Additionally, we found that piglets in the EO-supplemented group had upregulated (P < 0.05) levels of transporters and digestive enzymes in the intestine, which were significantly associated with daily gain and feed utilization. In addition, EO supplementation somewhat improved appetite in nursery pigs, increased the diversity of the gut microbiome and the abundance of beneficial bacteria, and there was a correlation between altered bacterial structure and appetite-related hormones. These findings indicate that EO is effective in promoting growth performance and nutrient absorption as well as in regulating appetite by improving intestinal health and bacterial structure.

A non-human primate model for human norovirus infection

Norovirus infection can cause gastrointestinal disease in humans. Development of therapies and vaccines against norovirus have been limited by the lack of a suitable and reliable animal model. Here we established rhesus macaques as an animal model for human norovirus infection. We show that rhesus macaques are susceptible to oral infection with human noroviruses from two different genogroups. Variation in duration of virus shedding (days to weeks) between animals, evolution of the virus over the time of infection, induction of virus-specific adaptive immune responses, susceptibility to reinfection and preferential replication of norovirus in the jejunum of rhesus macaques was similar to infection reported in humans. We found minor pathological signs and changes in epithelial cell surface glycosylation patterns in the small intestine during infection. Detection of viral protein and RNA in intestinal biopsies confirmed the presence of the virus in chromogranin A-expressing epithelial cells, as it does in humans. Thus, rhesus macaques are a promising non-human primate model to evaluate vaccines and therapeutics against norovirus disease.

Exploring the causal relationship between gut microbiota and multiple myeloma risk based on Mendelian randomization and biological annotation

Introduction

The microbial genome-wide association studies (mbGWAS) have highlighted significant host-microbiome interactions based on microbiome heritability. However, establishing causal relationships between particular microbiota and multiple myeloma (MM) remains challenging due to limited sample sizes.

Methods

Gut microbiota data from a GWAS with 18,340 participants and MM summary statistics from 456,348 individuals. The inverse variance-weighted (IVW) method was used as the main bidirectional Mendelian randomization (MR) analysis. To assess the robustness of our results, we further performed supplementary analyses, including MR pleiotropy residual sum and outlier (MR-PRESSO) test, MR-Egger, Weighted median, Simple mode, and Weighted mode. Moreover, a backward MR analysis was conducted to investigate the potential for reverse causation. Finally, gene and gene-set-based analyses were then conducted to explore the common biological factors connecting gut microbiota and MM.

Results

We discovered that 10 gut microbial taxa were causally related to MM risk. Among them, family Acidaminococcaceae, Bacteroidales family S24-7, family Porphyromonadaceae, genus Eubacterium ruminantium group, genus Parabacteroides, and genus Turicibacter were positively correlated with MM. Conversely, class Verrucomicrobia, family Verrucomicrobiaceae, genus Akkermansia, and order Verrucomicrobiales were negatively correlated with MM. The heterogeneity test revealed no Heterogeneity. MR-Egger and MR-PRESSO tests showed no significant horizontal pleiotropy. Importantly, leave-one-out analysis confirmed the robustness of MR results. In the backward MR analysis, no statistically significant associations were discovered between MM and 10 gut microbiota taxa. Lastly, we identified novel host-microbiome shared genes (AUTS2, CDK2, ERBB3, IKZF4, PMEL, SUOX, and RAB5B) that are associated with immunoregulation and prognosis in MM through biological annotation.

Discussion

Overall, this study provides evidence supporting a potential causal relationship between gut microbiota and MM risk, while also revealing novel host-microbiome shared genes relevant to MM immunoregulation and clinical prognosis.

Shengjiang Xiexin decoction mitigates murine Clostridium difficile infection through modulation of the gut microbiota and bile acid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

The overuse of antibiotics has resulted in Clostridium difficile infection (CDI) as a significant global public health concern. Studies have shown that imbalances in gut microbiota and metabolism play a vital role in the onset of CDI. Shengjiang Xiexin decoction (SJT), a traditional Chinese medicinal formula widely employed in the treatment of gastrointestinal ailments, demonstrates effectiveness in addressing murine CDI. However, the precise mechanistic role of SJT in CDI treatment remains uncertain, particularly regarding its impact on gut microbiota and intestinal metabolism. Thus, further investigation is imperative to shed light on these mechanisms.

AIM OF THE STUDY

This study aims to thoroughly investigate the therapeutic potential of SJT in the treatment of CDI, while also examining its impact on the intricate interplay between gut microbiota and bile acid metabolism. By employing a mouse model, we aspire to uncover novel insights that could pave the way for the development of more effective strategies in combating CDI.

MATERIALS AND METHODS

We developed a mouse model for CDI and assessed SJT's potential as a therapeutic agent through pharmacological analyses. Our study employed high-throughput sequencing of 16S rRNA to identify changes in gut microbiota composition and untargeted metabolomics analysis to evaluate SJT's intervention on intestinal metabolism. We also conducted targeted analysis of bile acid metabolism to examine the specific effects of SJT. Finally, the growth-inhibitory effect of SJT on C. difficile was confirmed through ex vivo cultivation of the pathogen using cecal contents, supporting its potential role in treating CDI by modulating gut microbiota and bile acid metabolism.

RESULTS

In pharmacological studies, SJT was found to effectively reduce the levels of A&B toxins and alleviate colonic inflammation in CDI mice. Mechanistically, SJT demonstrated a mild increase in the abundance and diversity of the gut microbiota. However, its most significant impact was observed in the substantial improvement of the structural composition of the gut microbiota. Specifically, SJT decreased the abundance of gut Polymorphs and Firmicutes while restoring the proportions of family Trichophyton and Bacteroides_S24-7 spp (P < 0.001). Moreover, SJT not only decreased the levels of primary bile acids but also elevated the levels of secondary bile acids. Notably, it enhanced the conversion of taurocholic acid (TCA) to deoxycholic acid (DCA), leading to a balanced bile acid metabolism. Finally, cecal contents of SJT-treated mice showed a significant reduction in the growth of C. difficile, underscoring the therapeutic potential of SJT via modulation of gut microbiota and bile acid metabolism.

CONCLUSION

SJT demonstrates remarkable efficacy in treating CDI in mice by not only effectively combating the infection but also restoring the intricate balance of gut microbiota and bile acid metabolism. Furthermore, promising indications suggest that SJT may have the potential to prevent CDI recurrence. These findings underscore the comprehensive therapeutic value of SJT in managing CDI. Moving forward, we plan to transition from the laboratory to clinical settings to conduct further studies, validating our conclusions on SJT's efficacy.

Digestive characteristics of extracellular polysaccharide from Lactiplantibacillus plantarum T1 and its regulation of intestinal microbiota

This study assessed the potential prebiotic characteristics of the previously reported Lactiplantibacillus plantarum extracellular polysaccharide (EPS-T1) with immunological activity. EPS-T1 was a novel heteropolysaccharide composed of glucose and galactose (1.00:1.21), with a molecular weight of 1.41 × 106 Da. The monosaccharide composition, molecular weight, fourier transform infrared, and 1H NMR analysis showed that EPS-T1 was well tolerated in the simulated oral cavity, gastric fluid, and small intestinal fluid environments, and was not easily degraded. Meanwhile, EPS-T1 could effectively be used as a carbon source to promote the growth of beneficial Lactobacillus species (Lactobacillus delbrueckii ssp. Bulgaricus, Streptococcus thermophilus, Lacticaseibacillus rhamnose GG, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei and Lactobacillus reuteri). After 24 h of fecal fermentation, EPS-T1(5 mg/mL) effectively reduced the relative abundance of harmful bacteria such as the Escherichia-Shigella, Citrobacter, Fusobacterium, Parasutterella, and Lachnoclostridium. While, the level content of beneficial flora (Bacteroides, Blautia, Phascolarctobacterium, Bifidobacterium, Parabacteroides, and Subdoligranulum) were significantly increased. In addition, EPS-T1 was able to significantly promote the enrichment of short-chain fatty acids such as acetic acid, propionic acid and butyric acid. These results provide some basis for the functional application of EPS-T1 as a potential prebiotic.

Reviewing the Clostridioides difficile Mouse Model: Insights into Infection Mechanisms

Clostridioides difficile is an anaerobic, spore-forming bacterium associated with intestinal infection, manifesting a broad spectrum of gastrointestinal symptoms, ranging from mild diarrhea to severe colitis. A primary risk factor for the development of C. difficile infection (CDI) is antibiotic exposure. Elderly and immunocompromised individuals are particularly vulnerable to CDI. A pivotal aspect for comprehending the complexities of this infection relies on the utilization of experimental models that mimic human CDI transmission, pathogenesis, and progression. These models offer invaluable insights into host-pathogen interactions and disease dynamics, and serve as essential tools for testing potential therapeutic approaches. In this review, we examine the animal model for CDI and delineate the stages of infection, with a specific focus on mice. Our objective is to offer an updated description of experimental models employed in the study of CDI, emphasizing both their strengths and limitations.

Ruminococcus torques is a keystone degrader of intestinal mucin glycoprotein, releasing oligosaccharides used by Bacteroides thetaiotaomicron

Symbiotic interactions between humans and our communities of resident gut microbes (microbiota) play many roles in health and disease. Some gut bacteria utilize mucus as a nutrient source and can under certain conditions damage the protective barrier it forms, increasing disease susceptibility. We investigated how Ruminococcus torques- a known mucin-degrader that remains poorly studied despite its implication in inflammatory bowel diseases (IBDs)- degrades mucin glycoproteins or their component O -linked glycans to understand its effects on the availability of mucin-derived nutrients for other bacteria. We found that R. torques utilizes both mucin glycoproteins and released oligosaccharides from gastric and colonic mucins, degrading these substrates with a panoply of mostly constitutively expressed, secreted enzymes. Investigation of mucin oligosaccharide degradation by R. torques revealed strong fucosidase, sialidase and β1,4-galactosidase activities. There was a lack of detectable sulfatase and weak β1,3-galactosidase degradation, resulting in accumulation of glycans containing these structures on mucin polypeptides. While the Gram-negative symbiont, Bacteroides thetaiotaomicron grows poorly on mucin glycoproteins, we demonstrate a clear ability of R. torques to liberate products from mucins, making them accessible to B. thetaiotaomicron . This work underscores the diversity of mucin-degrading mechanisms in different bacterial species and the probability that some species are contingent on others for the ability to more fully access mucin-derived nutrients. The ability of R. torques to directly degrade a variety of mucin and mucin glycan structures and unlock released glycans for other species suggests that it is a keystone mucin degrader, which may contribute to its association with IBD.

Importance

An important facet of maintaining healthy symbiosis between host and intestinal microbes is the mucus layer, the first defense protecting the epithelium from lumenal bacteria. Some gut bacteria degrade different components of intestinal mucins, but detailed mechanisms used by different species are still emerging. It is imperative to understand these mechanisms as they likely dictate interspecies interactions and may illuminate particular species associated with bacterial mucus destruction and subsequent disease susceptibility. Ruminococcus torques is positively associated with IBD in multiple studies. We identified mucin glycan-degrading enzymes in R. torques and found that it shares mucin degradation products with another gut bacterium implicated in IBD, Bacteroides thetaiotaomicron . Our findings underscore the importance of understanding the mucin degradation mechanisms of different gut bacteria and their consequences on interspecies interactions, which may identify keystone bacteria that disproportionately contribute to defects in mucus protection and could therefore be targets to prevent or treat IBD.

Huanglian Jiedu Wan intervened with "Shi-Re Shanghuo" syndrome through regulating immune balance mediated by biomarker succinate

With increasing stress in daily life and work, subhealth conditions induced by "Shi-Re Shanghuo" syndrome was gradually universal. "Huanglian Jiedu Wan" (HLJDW) was the first new syndrome Chinese medicine approved for the treatment of "Shi-Re Shanghuo" with promising clinical efficacy. Preliminary small-sample clinical studies have identified some notable biomarkers (succinate, 4-hydroxynonenal, etc.). However, the correlation and underlying mechanism between these biomarkers of HLJDW intervention on "Shi-Re Shanghuo" syndrome remained ambiguous. Therefore, this study was designed as a randomized, double-blind, multicenter, placebo-controlled Phase II clinical trial, employing integrated analysis techniques such as non-targeted and targeted metabolomics, salivary microbiota, proteomics, parallel peaction monitoring, molecular docking and surface plasmon resonance (SPR). The results of the correlation analysis indicated that HLJDW could mediate the balance between inflammation and immunity through succinate produced via host and microbial source to intervene "Shi-Re Shanghuo" syndrome. Further through the HIF1α/MMP9 pathway, succinate regulated downstream arachidonic acid metabolism, particularly the lipid peroxidation product 4-hydroxynonenal. Finally, an animal model of recurrent oral ulcers induced by "Shi-Re Shang Huo" was established and HLJDW was used for intervention, key essential indicators (succinate, glutamine, 4-hydroxynonenal, arachidonic acid metabolism) essential in the potential pathway HIF1α/MMP9 discovered in clinical practice were validated. The results were found to be consistent with our clinical findings. Taken together, succinate was observed as an important signal that triggered immune responses, which might serve as a key regulatory metabolic switch or marker of "Shi-Re Shanghuo" syndrome treated with HLJDW.

Hyperbaric oxygen augments susceptibility to C. difficile infection by impairing gut microbiota ability to stimulate the HIF-1α-IL-22 axis in ILC3

Hyperbaric oxygen (HBO) therapy is a well-established method for improving tissue oxygenation and is typically used for the treatment of various inflammatory conditions, including infectious diseases. However, its effect on the intestinal mucosa, a microenvironment known to be physiologically hypoxic, remains unclear. Here, we demonstrated that daily treatment with hyperbaric oxygen affects gut microbiome composition, worsening antibiotic-induced dysbiosis. Accordingly, HBO-treated mice were more susceptible to Clostridioides difficile infection (CDI), an enteric pathogen highly associated with antibiotic-induced colitis. These observations were closely linked with a decline in the level of microbiota-derived short-chain fatty acids (SCFAs). Butyrate, a SCFA produced primarily by anaerobic microbial species, mitigated HBO-induced susceptibility to CDI and increased epithelial barrier integrity by improving group 3 innate lymphoid cell (ILC3) responses. Mice displaying tissue-specific deletion of HIF-1 in RORγt-positive cells exhibited no protective effect of butyrate during CDI. In contrast, the reinforcement of HIF-1 signaling in RORγt-positive cells through the conditional deletion of VHL mitigated disease outcome, even after HBO therapy. Taken together, we conclude that HBO induces intestinal dysbiosis and impairs the production of SCFAs affecting the HIF-1α-IL-22 axis in ILC3 and worsening the response of mice to subsequent C. difficile infection.

New treatment approaches for Clostridioides difficile infections: alternatives to antibiotics and fecal microbiota transplantation

Clostridioides difficile causes a range of debilitating intestinal symptoms that may be fatal. It is particularly problematic as a hospital-acquired infection, causing significant costs to the health care system. Antibiotics, such as vancomycin and fidaxomicin, are still the drugs of choice for C. difficile infections, but their effectiveness is limited, and microbial interventions are emerging as a new treatment option. This paper focuses on alternative treatment approaches, which are currently in various stages of development and can be divided into four therapeutic strategies. Direct killing of C. difficile (i) includes beside established antibiotics, less studied bacteriophages, and their derivatives, such as endolysins and tailocins. Restoration of microbiota composition and function (ii) is achieved with fecal microbiota transplantation, which has recently been approved, with standardized defined microbial mixtures, and with probiotics, which have been administered with moderate success. Prevention of deleterious effects of antibiotics on microbiota is achieved with agents for the neutralization of antibiotics that act in the gut and are nearing regulatory approval. Neutralization of C. difficile toxins (iii) which are crucial virulence factors is achieved with antibodies/antibody fragments or alternative binding proteins. Of these, the monoclonal antibody bezlotoxumab is already in clinical use. Immunomodulation (iv) can help eliminate or prevent C. difficile infection by interfering with cytokine signaling. Small-molecule agents without bacteriolytic activity are usually selected by drug repurposing and can act via a variety of mechanisms. The multiple treatment options described in this article provide optimism for the future treatment of C. difficile infection.

Transplant of microbiota from Crohn's disease patients to germ-free mice results in colitis

Although the role of the intestinal microbiota in the pathogenesis of inflammatory bowel disease (IBD) is beyond debate, attempts to verify the causative role of IBD-associated dysbiosis have been limited to reports of promoting the disease in genetically susceptible mice or in chemically induced colitis. We aimed to further test the host response to fecal microbiome transplantation (FMT) from Crohn's disease patients on mucosal homeostasis in ex-germ-free (xGF) mice. We characterized and transferred fecal microbiota from healthy patients and patients with defined Crohn's ileocolitis (CD_L3) to germ-free mice and analyzed the resulting microbial and mucosal homeostasis by 16S profiling, shotgun metagenomics, histology, immunofluorescence (IF) and RNAseq analysis. We observed a markedly reduced engraftment of CD_L3 microbiome compared to healthy control microbiota. FMT from CD_L3 patients did not lead to ileitis but resulted in colitis with features consistent with CD: a discontinued pattern of colitis, more proximal colonic localization, enlarged isolated lymphoid follicles and/or tertiary lymphoid organ neogenesis, and a transcriptomic pattern consistent with epithelial reprograming and promotion of the Paneth cell-like signature in the proximal colon and immune dysregulation characteristic of CD. The observed inflammatory response was associated with persistently increased abundance of Ruminococcus gnavus, Erysipelatoclostridium ramosum, Faecalimonas umbilicate, Blautia hominis, Clostridium butyricum, and C. paraputrificum and unexpected growth of toxigenic C. difficile, which was below the detection level in the community used for inoculation. Our study provides the first evidence that the transfer of a dysbiotic community from CD patients can lead to spontaneous inflammatory changes in the colon of xGF mice and identifies a signature microbial community capable of promoting colonization of pathogenic and conditionally pathogenic bacteria.

Clinical Efficacy and Gut Microbiota Regulating-Related Effect of Si-Jun-Zi Decoction in Postoperative Non-Small Cell Lung Cancer Patients: A Prospective Observational Study

BACKGROUND

Postoperative non-small cell lung cancer (NSCLC) patients frequently encounter a deteriorated quality of life (QOL), disturbed immune response, and disordered homeostasis. Si-Jun-Zi Decoction (SJZD), a well-known traditional Chinese herbal formula, is frequently employed in clinical application for many years. Exploration is underway to investigate the potential therapeutic effect of SJZD for treating postoperative NSCLC.

OBJECTIVE

To assess the efficacy of SJZD on QOLs, hematological parameters, and regulations of gut microbiota in postoperative NSCLC patients.

METHODS

A prospective observational cohort study was conducted, enrolling 65 postoperative NSCLC patients between May 10, 2020 and March 15, 2021 in Yueyang Hospital, with 33 patients in SJZD group and 32 patients in control (CON) group. The SJZD group comprised of patients who received standard treatments and the SJZD decoction, while the CON group consisted of those only underwent standard treatments. The treatment period was 4 weeks. The primary outcome was QOL. The secondary outcomes involved serum immune cell and inflammation factor levels, safety, and alterations in gut microbiota.

RESULTS

SJZD group showed significant enhancements in cognitive functioning (P = .048) at week 1 and physical functioning (P = .019) at week 4. Lung cancer-specific symptoms included dyspnea (P = .001), coughing (P = .008), hemoptysis (P = .034), peripheral neuropathy (P = .019), and pain (arm or shoulder, P = .020, other parts, P = .019) eased significantly in the fourth week. Anemia indicators such as red blood cell count (P = .003 at week 1, P = .029 at week 4) and hemoglobin (P = .016 at week 1, P = .048 at week 4) were significantly elevated by SJZD. SJZD upregulated blood cell cluster differentiation (CD)3+ (P = .001 at week 1, P < .001 at week 4), CD3+CD4+ (P = .012 at week 1), CD3+CD8+ (P = .027 at week 1), CD19+ (P = .003 at week 4), increased anti-inflammatory interleukin (IL)-10 (P = .004 at week 1, P = .003 at week 4), and decreased pro-inflammatory IL-8 (P = .004 at week 1, p = .005 at week 4). Analysis of gut microbiota indicated that SJZD had a significant impact on increasing microbial abundance and diversity, enriching probiotic microbes, and regulating microbial biological functions.

CONCLUSIONS

SJZD appears to be an effective and safe treatment for postoperative NSCLC patients. As a preliminary observational study, this study provides a foundation for further research.

In vitro faecal fermentation of Tritordeum breads and its effect on the human gut health

Spontaneous fermentation of Tritordeum flour enhances the nutritional potential of this hybrid cereal. However, the effect of consumption of Tritordeum sourdough bread (SDB) on gut health remains to be elucidated. This study investigated the effect of in vitro digestion and faecal fermentation of SDB compared to that of traditional baker's yeast (BYB) Tritordeum bread. After 24-h anaerobic faecal fermentation, both SDB and BYB (1% w/v) induced an increase in the relative abundances of Bifidobacterium, Megasphaera, Mitsuokella, and Phascolarctobacterium genera compared to baseline, while concentrations of acetate and butyrate were significantly higher at 24 h for SDB compared to those for BYB. Integrity of intestinal epithelium, as assessed through in vitro trans-epithelial electrical resistance (TEER) assay, was slightly increased after incubation with SDB fermentation supernatants, but not after incubation with BYB fermentation supernatants. The SDB stimulated in vitro mucosal immune response by inducing early secretion of inflammatory cytokines, IL-6 and TNF-α, followed by downregulation of the inflammatory trigger through induction of anti-inflammatory IL-10 expression. Overall, our findings suggest that Tritordeum sourdough can modulate gut microbiota fermentation activity and positively impact the gut health.

The role of faecal microbiota transplantation in chronic noncommunicable disorders

The gut microbiome plays a key role in influencing several pathways and functions involved in human health, including metabolism, protection against infection, and immune regulation. Perturbation of the gut microbiome is recognised as a pathogenic factor in several gastrointestinal and extraintestinal disorders, and is increasingly considered as a therapeutic target in these conditions. Faecal microbiota transplantation (FMT) is the transfer of the microbiota from healthy screened stool donors into the gut of affected patients, and is a well-established and highly effective treatment for recurrent Clostridioides difficile infection. Despite the mechanisms of efficacy of FMT not being fully understood, it has been investigated in several chronic noncommunicable disorders, with variable results. This review aims to give an overview of mechanisms of efficacy of FMT in chronic noncommunicable disorders, and to paint the current landscape of its investigation in these medical conditions, including inflammatory bowel disease (IBD), chronic liver disorders, and also extraintestinal autoimmune conditions.

Polyamines and hypusination are important for Clostridioides difficile toxin B (TcdB)-mediated activation of group 3 innate lymphocytes (ILC3s)

Clostridioides difficile is the most common cause of nosocomial gastrointestinal tract bacterial infections. We lack fully effective reliable treatments for this pathogen, and there is a critical need to better understand how C. difficile interacts with our immune system. Group 3 innate lymphocytes (ILC3s) are rare immune cells localized within mucosal tissues that protect against bacterial infections. Upon activation, ILC3s secrete high levels of the cytokine interleukin-22 (IL-22), which is a critical regulator of tissue responses during infection. C. difficile toxin B (TcdB), the major virulence factor, directly activates ILC3s, resulting in high IL-22 levels. We previously reported that polyamines are important in the activation of ILC3s by the innate cytokine interleukin-23 (IL-23) but did not identify a specific mechanism. In this study, we examine how a pathogen impacts a metabolic pathway important for immune cell function and hypothesized that polyamines are important in TcdB-mediated ILC3 activation. We show that TcdB upregulates the polyamine biosynthesis pathway, and the inhibition of the pathway decreases TcdB-mediated ILC3 activation. Two polyamines, putrescine and spermidine, are involved. Spermidine is the key polyamine in the hypusination of eukaryotic initiation factor 5A (eIF5A), and the inhibition of eIF5A reduced ILC3 activation. Thus, there is potential to leverage polyamines in ILC3s to promote activation of ILC3s during C. difficile infection and other bacterial infections where ILC3s serve a protective role.

Cross-regulation of antibody responses against the SARS-CoV-2 Spike protein and commensal microbiota via molecular mimicry

The commensal microflora provides a repertoire of antigens that illicit mucosal antibodies. In some cases, these antibodies can cross-react with host proteins, inducing autoimmunity, or with other microbial antigens. We demonstrate that the oral microbiota can induce salivary anti-SARS-CoV-2 Spike IgG antibodies via molecular mimicry. Anti-Spike IgG antibodies in the saliva correlated with enhanced abundance of Streptococcus salivarius 1 month after anti-SARS-CoV-2 vaccination. Several human commensal bacteria, including S. salivarius, were recognized by SARS-CoV-2-neutralizing monoclonal antibodies and induced cross-reactive anti-Spike antibodies in mice, facilitating SARS-CoV-2 clearance. A specific S. salivarius protein, RSSL-01370, contains regions with homology to the Spike receptor-binding domain, and immunization of mice with RSSL-01370 elicited anti-Spike IgG antibodies in the serum. Additionally, oral S. salivarius supplementation enhanced salivary anti-Spike antibodies in vaccinated individuals. Altogether, these data show that distinct species of the human microbiota can express molecular mimics of SARS-CoV-2 Spike protein, potentially enhancing protective immunity.

Microbiota-gut-brain axis drives overeating disorders

Overeating disorders (ODs), usually stemming from dieting history and stress, remain a pervasive issue in contemporary society, with the pathological mechanisms largely unresolved. Here, we show that alterations in intestinal microbiota are responsible for the excessive intake of palatable foods in OD mice and patients with bulimia nervosa (BN). Stress combined with a history of dieting causes significant changes in the microbiota and the intestinal metabolism, which disinhibit the vagus nerve terminals in the gut and thereby lead to a subsequent hyperactivation of the gut-brain axis passing through the vagus, the solitary tract nucleus, and the paraventricular nucleus of the thalamus. The transplantation of a probiotic Faecalibacterium prausnitzii or dietary supplement of key metabolites restores the activity of the gut-to-brain pathway and thereby alleviates the OD symptoms. Thus, our study delineates how the microbiota-gut-brain axis mediates energy balance, unveils the underlying pathogenesis of the OD, and provides potential therapeutic strategies.

The Effects of Dietary Silybin Supplementation on the Growth Performance and Regulation of Intestinal Oxidative Injury and Microflora Dysbiosis in Weaned Piglets

Oxidative stress is the major incentive for intestinal dysfunction in weaned piglets, which usually leads to growth retardation or even death. Silybin has caught extensive attention due to its antioxidant properties. Herein, we investigated the effect of dietary silybin supplementation on growth performance and determined its protective effect on paraquat (PQ)-induced intestinal oxidative damage and microflora dysbiosis in weaned piglets. In trial 1, a total of one hundred twenty healthy weaned piglets were randomly assigned into five treatments with six replicate pens per treatment and four piglets per pen, where they were fed basal diets supplemented with silybin at 0, 50, 100, 200, or 400 mg/kg for 42 days. In trial 2, a total of 24 piglets were randomly allocated to two dietary treatments with 12 replicates per treatment and 1 piglet per pen: a basal diet or adding 400 mg/kg silybin to a basal diet. One-half piglets in each treatment were given an intraperitoneal injection of paraquat (4 mg/kg of body weight) or sterile saline on day 18. All piglets were euthanized on day 21 for sample collection. The results showed that dietary supplementation with 400 mg/kg silybin resulted in a lower feed conversion ratio, diarrhea incidence, and greater antioxidant capacity in weaned piglets. Dietary silybin enhanced intestinal antioxidant capacity and mitochondrial function in oxidative stress piglets induced by PQ. Silybin inhibited mitochondria-associated endogenous apoptotic procedures and then improved the intestinal barrier function and morphology of PQ-challenged piglets. Moreover, silybin improved intestinal microbiota dysbiosis induced by the PQ challenge by enriching short-chain fatty-acid-producing bacteria, which augmented the production of acetate and propionate. Collectively, these findings indicated that dietary silybin supplementation linearly decreased feed conversion ratio and reduced diarrhea incidence in normal conditions, and effectively alleviated oxidative stress-induced mitochondrial dysfunction, intestinal damage, and microflora dysbiosis in weaned piglets.

Fecal microbiota transplantation promotes reduction of antimicrobial resistance by strain replacement

Multidrug-resistant organism (MDRO) colonization is a fundamental challenge in antimicrobial resistance. Limited studies have shown that fecal microbiota transplantation (FMT) can reduce MDRO colonization, but its mechanisms are poorly understood. We conducted a randomized, controlled trial of FMT for MDRO decolonization in renal transplant recipients called PREMIX (NCT02922816). Eleven participants were enrolled and randomized 1:1 to FMT or an observation period followed by delayed FMT if stool cultures were MDRO positive at day 36. Participants who were MDRO positive after one FMT were treated with a second FMT. At last visit, eight of nine patients who completed all treatments were MDRO culture negative. FMT-treated participants had longer time to recurrent MDRO infection versus PREMIX-eligible controls who were not treated with FMT. Key taxa (Akkermansia muciniphila, Alistipes putredinis, Phocaeicola dorei, Phascolarctobacterium faecium, Alistipes species, Mesosutterella massiliensis, Barnesiella intestinihominis, and Faecalibacterium prausnitzii) from the single feces donor used in the study that engrafted in recipients and metabolites such as short-chain fatty acids and bile acids in FMT-responding participants uncovered leads for rational microbiome therapeutic and diagnostic development. Metagenomic analyses revealed a previously unobserved mechanism of MDRO eradication by conspecific strain competition in an FMT-treated subset. Susceptible Enterobacterales strains that replaced baseline extended-spectrum β-lactamase-producing strains were not detectable in donor microbiota manufactured as FMT doses but in one case were detectable in the recipient before FMT. These data suggest that FMT may provide a path to exploit strain competition to reduce MDRO colonization.

Itaconate inhibits SYK through alkylation and suppresses inflammation against hvKP induced intestinal dysbiosis

Hypervirulent Klebsiella pneumoniae (hvKP) is a highly lethal opportunistic pathogen that elicits more severe inflammatory responses compared to classical Klebsiella pneumoniae (cKP). In this study, we investigated the interaction between hvKP infection and the anti-inflammatory immune response gene 1 (IRG1)-itaconate axis. Firstly, we demonstrated the activation of the IRG1-itaconate axis induced by hvKP, with a dependency on SYK signaling rather than STING. Importantly, we discovered that exogenous supplementation of itaconate effectively inhibited excessive inflammation by directly inhibiting SYK kinase at the 593 site through alkylation. Furthermore, our study revealed that itaconate effectively suppressed the classical activation phenotype (M1 phenotype) and macrophage cell death induced by hvKP. In vivo experiments demonstrated that itaconate administration mitigated hvKP-induced disturbances in intestinal immunopathology and homeostasis, including the restoration of intestinal barrier integrity and alleviation of dysbiosis in the gut microbiota, ultimately preventing fatal injury. Overall, our study expands the current understanding of the IRG1-itaconate axis in hvKP infection, providing a promising foundation for the development of innovative therapeutic strategies utilizing itaconate for the treatment of hvKP infections.

Promoting intestinal antimicrobial defense and microbiome symbiosis contributes to IL-22-mediated protection against alcoholic hepatitis in mice

Background

The hepatoprotective effect of interleukin 22 (IL-22) has been reported in several models of liver injuries, including alcohol-associated liver disease (ALD). However, the intestinal role of IL-22 in alcoholic hepatitis remains to be elucidated.

Methods

Intestinal IL-22 levels were measured in mice fed with alcohol for 8 weeks. IL-22 was then administered to alcohol-fed mice to test its protective effects on alleviating alcoholic hepatitis, focusing on intestinal protection. Acute IL-22 treatment was conducted in mice to further explore the link between IL-22 and the induction of antimicrobial peptide (AMP). Intestinal epithelial cell-specific knockout of signal transducer and activator of transcription 3 (STAT3) mice were generated and used for organoid study to explore its role in IL-22-mediated AMP expression and gut barrier integrity.

Results

After alcohol feeding for 8 weeks, the intestinal levels of IL-22 were significantly reduced in mice. IL-22 treatment to alcohol-fed mice mitigated liver injury as indicated by normalized serum transaminase levels, improved liver histology, reduced lipid accumulation, and attenuated inflammation. In the intestine, alcohol-reduced Reg3γ and α-defensins levels were reversed by IL-22 treatment. IL-22 also improved gut barrier integrity and decreased endotoxemia in alcohol-fed mice. While alcohol feeding significantly reduced Akkermansia, IL-22 administration dramatically expanded this commensal bacterium in mice. Regardless of alcohol, acute IL-22 treatment induced a fast and robust induction of intestinal AMPs and STAT3 activation. By using in vitro cultured intestinal organoids isolated from WT mice and mice deficient in intestinal epithelial-STAT3, we further demonstrated that STAT3 is required for IL-22-mediated AMP expression. In addition, IL-22 also regulates intestinal epithelium differentiation as indicated by direct regulation of sodium-hydrogen exchanger 3 via STAT3.

Conclusion

Our study suggests that IL-22 not only targets the liver but also benefits the intestine in many aspects. The intestinal effects of IL-22 include regulating AMP expression, microbiota, and gut barrier function that is pivotal in ameliorating alcohol induced translocation of gut-derived bacterial pathogens and liver inflammation.

Dysbiosis of intestinal homeostasis contribute to Whitmania pigra edema disease

Whitmania pigra is widely used in traditional Chinese medicine. However, W. pigra is being threatened by an edema disease with unknown causes (WPE). In this study, a comprehensive exploration of virome, microbiome, and metabolome aberrations in the intestine of W. pigra was performed to address the aetiology of WPE. Virome analysis indicated that eukaryotic viruses did not contribute to WPE, whereas an expansion of Caudovirales was observed in WPE. Compared to the control, the microbial richness and diversity in diseased W. pigra decreased remarkably. Nine genera, including Aeromonas, Anaerotruncus, Vibrio, Proteocatella, Acinetobacter, and Brachyspira were overrepresented in WPE, whereas eleven genera, including Bifidobacterium, Phascolarctobacterium, Lactobacillus, Bacillus and AF12, were enriched in healthy individuals. Furthermore, certain metabolites, especially amino acids, short-chain fatty acids, and bile acids, were found to be linked to intestinal microbiota alterations in WPE. An integration of the microbiome and metabolome in WPE found that dysbiosis of the gut microbiota or metabolites caused WPE. Notably, W. pigra accepted intestinal microbiota transplantation from WPE donors developed WPE clinical signs eventually, and the dysbiotic intestinal microbiota can be recharacterized in this recipient W. pigra. Strikingly, pathological features of metanephridium and uraemic toxin enrichment in the gut indicated a putative interconnection between the gut and metanephridium in WPE, which represents the prototype of the gut-kidney axis in mammals. These finding exemplify the conservation of "microecological Koch's postulates" from annelids to insects and other vertebrates, which provides a direction of prevention and treatment for WPE and opens a new insight into the pathogenesis of aquatic animal diseases from an ecological perspective.

Identification of Novel Glycans in the Mucus Layer of Shark and Skate Skin

The mucus layer covering the skin of fish has several roles, including protection against pathogens and mechanical damage. While the mucus layers of various bony fish species have been investigated, the composition and glycan profiles of shark skin mucus remain relatively unexplored. In this pilot study, we aimed to explore the structure and composition of shark skin mucus through histological analysis and glycan profiling. Histological examination of skin samples from Atlantic spiny dogfish (Squalus acanthias) sharks and chain catsharks (Scyliorhinus retifer) revealed distinct mucin-producing cells and a mucus layer, indicating the presence of a functional mucus layer similar to bony fish mucus albeit thinner. Glycan profiling using liquid chromatography-electrospray ionization tandem mass spectrometry unveiled a diverse repertoire of mostly O-glycans in the mucus of the two sharks as well as little skate (Leucoraja erinacea). Elasmobranch glycans differ significantly from bony fish, especially in being more sulfated, and some bear resemblance to human glycans, such as gastric mucin O-glycans and H blood group-type glycans. This study contributes to the concept of shark skin having unique properties and provides a foundation for further research into the functional roles and potential biomedical implications of shark skin mucus glycans.

Vaccination and Microbiota Manipulation Approaches for Colon Cancer Prevention in Rodent Models

Colorectal cancer represents the third most common cancer type worldwide and is a leading cause of cancer-related mortality in the United States and Western countries. Rodent models have been invaluable to study the etiology of colorectal cancer and to test novel chemoprevention avenues. In the past, the laboratory mouse has become one of the best preclinical models for these studies due to the availability of genetic information for commonly used mouse strains with well-established and precise gene targeting and transgenic techniques. Well-established chemical mutagenesis technologies are also being used to develop mouse and rat models of colorectal cancer for prevention and treatment studies. In addition, xenotransplantation of cancer cell lines and patient-derived xenografts has been useful for preclinical prevention studies and drug development. This review focuses on the recent use of rodent models to evaluate the utility of novel strategies in the prevention of colon cancers including immune prevention approaches and the manipulation of the intestinal microbiota.

Genetic support of the causal association between gut microbiome and COVID-19: a bidirectional Mendelian randomization study

Background

The association between gut microbiome and coronavirus disease 2019 (COVID-19) has attracted much attention, but its causality remains unclear and requires more direct evidence.

Methods

In this study, we conducted the bidirectional Mendelian randomization (MR) analysis to assess the causal association between gut microbiome and COVID-19 based on the summary statistics data of genome-wide association studies (GWASs). Over 1.8 million individuals with three COVID-19 phenotypes (severity, hospitalization and infection) were included. And 196 bacterial taxa from phylum to genus were analyzed. The inverse-variance weighted (IVW) analysis was chosen as the primary method. Besides, false discovery rate (FDR) correction of p-value was used. To test the robustness of the causal relationships with p-FDR < 0.05, sensitivity analyses including the secondary MR analyses, horizontal pleiotropy test, outliers test, and "leave-one-out" analysis were conducted.

Results

In the forward MR, we found that 3, 8, and 10 bacterial taxa had suggestive effects on COVID-19 severity, hospitalization and infection, respectively. The genus Alloprevotella [odds ratio (OR) = 1.67; 95% confidence interval (95% CI), 1.32-2.11; p = 1.69×10^-5, p-FDR = 2.01×10^-3] was causally associated with a higher COVID-19 severity risk. In the reverse MR, COVID-19 severity, hospitalization and infection had suggestive effects on the abundance of 4, 8 and 10 bacterial taxa, respectively. COVID-19 hospitalization causally increased the abundance of the phylum Bacteroidetes (OR = 1.13; 95% CI, 1.04-1.22; p = 3.02×10^-3; p-FDR = 2.72×10^-2). However, secondary MR analyses indicated that the result of COVID-19 hospitalization on the phylum Bacteroidetes required careful consideration.

Conclusion

Our study revealed the causal association between gut microbiome and COVID-19 and highlighted the role of "gut-lung axis" in the progression of COVID-19.

Host Immunity and Immunization Strategies for Clostridioides difficile Infection

Clostridioides difficile infection (CDI) represents a significant challenge to public health. C. difficile-associated mortality and morbidity have led the U.S. CDC to designate it as an urgent threat. Moreover, recurrence or relapses can occur in up to a third of CDI patients, due in part to antibiotics being the primary treatment for CDI and the major cause of the disease. In this review, we summarize the current knowledge of innate immune responses, adaptive immune responses, and the link between innate and adaptive immune responses of the host against CDI. The other major determinants of CDI, such as C. difficile toxins, the host microbiota, and related treatments, are also described. Finally, we discuss the known therapeutic approaches and the current status of immunization strategies for CDI, which might help to bridge the knowledge gap in the generation of therapy against CDI.

Microbiota-mediated colonization resistance: mechanisms and regulation

A dense and diverse microbial community inhabits the gut and many epithelial surfaces. Referred to as the microbiota, it co-evolved with the host and is beneficial for many host physiological processes. A major function of these symbiotic microorganisms is protection against pathogen colonization and overgrowth of indigenous pathobionts. Dysbiosis of the normal microbial community increases the risk of pathogen infection and overgrowth of harmful pathobionts. The protective mechanisms conferred by the microbiota are complex and include competitive microbial-microbial interactions and induction of host immune responses. Pathogens, in turn, have evolved multiple strategies to subvert colonization resistance conferred by the microbiota. Understanding the mechanisms by which microbial symbionts limit pathogen colonization should guide the development of new therapeutic approaches to prevent or treat disease.

Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

Dietary Berberine and Ellagic Acid Supplementation Improve Growth Performance and Intestinal Damage by Regulating the Structural Function of Gut Microbiota and SCFAs in Weaned Piglets

Early weaning is an effective method for improving the utilization rate of sows in intensive pig farms. However, weaning stress induces diarrhea and intestinal damage in piglets. Berberine (BBR) is known for its anti-diarrhea properties and ellagic acid (EA) is known for its antioxidant properties, however, whether their combination improves diarrhea and intestinal damage in piglets has not been studied, and the mechanism remains unclear. To explore the combined effects in this experiment, a total of 63 weaned piglets (Landrace × Yorkshire) were divided into three groups at 21 days. Piglets in the Ctrl group were treated with a basal diet and 2 mL saline orally, while those in the BE group were treated with a basal diet supplemented with 10 mg/kg (BW) BBR, 10 mg/kg (BW) EA, and 2 mL saline orally. Piglets in the FBE group were treated with a basal diet and 2 mL fecal microbiota suspension from the BE group orally, respectively, for 14 days. Compared with the Ctrl group, dietary supplementation with BE improved growth performance by increasing the average daily gain and average daily food intake and reducing the fecal score in weaned piglets. Dietary supplementation with BE also improved intestinal morphology and cell apoptosis by increasing the ratio of villus height to crypt depth and decreasing the average optical density of apoptotic cells; meanwhile, improvements also involved attenuating oxidative stress and intestinal barrier dysfunction by increasing the total antioxidant capacity, glutathione, and catalase, and upregulating the mRNA expressions of Occludin, Claudin-1, and ZO-1. Interestingly, the oral administration of a fecal microbiota suspension to piglets fed BE had similar effects to those of the BE group. According to 16S rDNA sequencing analysis, dietary supplementation with BE altered the composition of the microbiota, including firmicutes, bacteroidetes, lactobacillus, phascolarctobacterium, and parabacteroides, and increased the metabolites of propionate and butyrate. In addition, Spearman analysis revealed that improvements in growth performance and intestinal damage were significantly correlated with differential bacteria and short-chain fatty acids (SCFAs). In brief, dietary supplementation with BE improved the growth performance and intestinal damage by altering the gut microbiota composition and SCFAs in weaned piglets.

multiMiAT: an optimal microbiome-based association test for multicategory phenotypes

Microbes can affect the metabolism and immunity of human body incessantly, and the dysbiosis of human microbiome drives not only the occurrence but also the progression of disease (i.e. multiple statuses of disease). Recently, microbiome-based association tests have been widely developed to detect the association between the microbiome and host phenotype. However, the existing methods have not achieved satisfactory performance in testing the association between the microbiome and ordinal/nominal multicategory phenotypes (e.g. disease severity and tumor subtype). In this paper, we propose an optimal microbiome-based association test for multicategory phenotypes, namely, multiMiAT. Specifically, under the multinomial logit model framework, we first introduce a microbiome regression-based kernel association test for multicategory phenotypes (multiMiRKAT). As a data-driven optimal test, multiMiAT then integrates multiMiRKAT, score test and MiRKAT-MC to maintain excellent performance in diverse association patterns. Massive simulation experiments prove the success of our method. Furthermore, multiMiAT is also applied to real microbiome data experiments to detect the association between the gut microbiome and clinical statuses of colorectal cancer as well as for diverse statuses of Clostridium difficile infections.

IL-22 alters gut microbiota composition and function to increase aryl hydrocarbon receptor activity in mice and humans

BACKGROUND

IL-22 is induced by aryl hydrocarbon receptor (AhR) signaling and plays a critical role in gastrointestinal barrier function through effects on antimicrobial protein production, mucus secretion, and epithelial cell differentiation and proliferation, giving it the potential to modulate the microbiome through these direct and indirect effects. Furthermore, the microbiome can in turn influence IL-22 production through the synthesis of L-tryptophan (L-Trp)-derived AhR ligands, creating the prospect of a host-microbiome feedback loop. We evaluated the impact IL-22 may have on the gut microbiome and its ability to activate host AhR signaling by observing changes in gut microbiome composition, function, and AhR ligand production following exogenous IL-22 treatment in both mice and humans.

RESULTS

Microbiome alterations were observed across the gastrointestinal tract of IL-22-treated mice, accompanied by an increased microbial functional capacity for L-Trp metabolism. Bacterially derived indole derivatives were increased in stool from IL-22-treated mice and correlated with increased fecal AhR activity. In humans, reduced fecal concentrations of indole derivatives in ulcerative colitis (UC) patients compared to healthy volunteers were accompanied by a trend towards reduced fecal AhR activity. Following exogenous IL-22 treatment in UC patients, both fecal AhR activity and concentrations of indole derivatives increased over time compared to placebo-treated UC patients.

CONCLUSIONS

Overall, our findings indicate IL-22 shapes gut microbiome composition and function, which leads to increased AhR signaling and suggests exogenous IL-22 modulation of the microbiome may have functional significance in a disease setting. Video Abstract.

Fermented mixed feed regulates intestinal microbial community and metabolism and alters pork flavor and umami

This study aimed to determine the effects of fermented mixed feed (FMF) supplementation (0%, 5% and 10%) on the intestinal microbial community and metabolism, and the compositions of volatile flavor compounds and inosine monophosphate (IMP) contents in the longissimus thoracis. In this study, 144 finishing pigs (Duroc × Berkshire × Jiaxing Black) were randomly allocated to 3 groups with 4 replicate pens per group and 12 pigs per pen. The experiment lasted 38 days after 4 days of acclimation. The 16S rRNA gene sequences and an untargeted metabolomics analysis showed FMF altered the profiles of microbes and metabolites in the colon. Heracles flash GC e-nose analysis showed that 10% FMF (treatment 3) had a greater influence on the compositions of volatile flavor compounds than 5% FMF (treatment 2). Compared to 0% FMF (treatment 1), the contents of total aldehydes, (E,E)-2,4-nonadienal, dodecanal, nonanal and 2-decenal were significantly increased by treatment 3, and treatment 3 increased IMP concentrations and gene expressions related to its synthesis. Correlations analysis showed significantly different microbes and metabolites had strong correlations with the contents of IMP and volatile flavor compounds. In conclusion, treatment 3 regulated intestinal microbial community and metabolism, that in turn altered the compositions of volatile compounds, which contributed to improving pork flavor and umami.

Gut microbiota-derived nicotinamide mononucleotide alleviates acute pancreatitis by activating pancreatic SIRT3 signalling

BACKGROUND AND PURPOSE

Gut microbiota dysbiosis induced by acute pancreatitis (AP) exacerbates pancreatic injury and systemic inflammatory responses. The alleviation of gut microbiota dysbiosis through faecal microbiota transplantation (FMT) is considered a potential strategy to reduce tissue damage and inflammation in many clinical disorders. Here, we aim to investigate the effect of gut microbiota and microbiota-derived metabolites on AP and further clarify the mechanisms associated with pancreatic damage and inflammation.

EXPERIMENTAL APPROACH

AP rat and mouse models were established by administration of caerulein or sodium taurocholate in vivo. Pancreatic acinar cells were exposed to caerulein and lipopolysaccharide in vitro to simulate AP.

KEY RESULTS

Normobiotic FMT alleviated AP-induced gut microbiota dysbiosis and ameliorated the severity of AP, including mitochondrial dysfunction, oxidative damage and inflammation. Normobiotic FMT induced higher levels of NAD⁺ (nicotinamide adenine dinucleotide)-associated metabolites, particularly nicotinamide mononucleotide (NMN). NMN administration mitigated AP-mediated mitochondrial dysfunction, oxidative damage and inflammation by increasing pancreatic NAD⁺ levels. Similarly, overexpression of the NAD⁺ -dependent mitochondrial deacetylase sirtuin 3 (SIRT3) alleviated the severity of AP. Furthermore, SIRT3 deacetylated peroxiredoxin 5 (PRDX5) and enhanced PRDX5 protein expression, thereby promoting its antioxidant and anti-inflammatory activities in AP. Importantly, normobiotic FMT-mediated NMN metabolism induced SIRT3-PRDX5 pathway activation during AP.

CONCLUSION AND IMPLICATIONS

Gut microbiota-derived NMN alleviates the severity of AP by activating the SIRT3-PRDX5 pathway. Normobiotic FMT could be served as a potential strategy for AP treatment.

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.

Experimental bacterial dysbiosis with consequent immune alterations increase intrarectal SIV acquisition susceptibility

Variations in the composition of the intestinal bacterial microbiome correlate with acquisition of some sexually transmitted pathogens. To experimentally assess the contribution of intestinal dysbiosis to rectal lentiviral acquisition, we induce dysbiosis in rhesus macaques (RMs) with the antibiotic vancomycin prior to repeated low-dose intrarectal challenge with simian immunodeficiency virus (SIV) SIVmac239X. Vancomycin administration reduces T helper 17 (TH17) and TH22 frequencies, increases expression of host bacterial sensors and antibacterial peptides, and increases numbers of transmitted-founder (T/F) variants detected upon SIV acquisition. We observe that SIV acquisition does not correlate with measures of dysbiosis but rather associates with perturbations in the host antimicrobial program. These findings establish a functional association between the intestinal microbiome and susceptibility to lentiviral acquisition across the rectal epithelial barrier.

N-glycosylated intestinal protein BCF-1 shapes microbial colonization by binding bacteria via its fimbrial protein

Microbial colonization plays an instrumental role in the health of the host. However, the host factors that facilitate the establishment of the microbial colonization remain unclear. Here, we establish a screening method to identify host factors regulating E. coli colonization in C. elegans. We find that a BCF-1 possessing N-glycosylation promotes E. coli colonization by directly binding to E. coli via its fimbrial protein, YdeR. BCF-1 is activated by the bacteria and interacts with an oligosaccharyl transferase, OSTB-1, which is critical for regulating E. coli colonization. We also show that the N-glycosylation of BCF-1 is critical for E. coli colonization. In addition, we find that the microbiota composition is shaped by BCF-1. In summary, this study shows a "scaffold model" for bacterial colonization between a host glycoprotein and E. coli, and it also introduces a powerful research approach to identify individual host factors involved in modulating bacterial colonization.

Current Knowledge of Th22 Cell and IL-22 Functions in Infectious Diseases

T helper 22 (Th22) cells, a newly defined CD4+ T-cell lineage, are characterized by their distinct cytokine profile, which primarily consists of IL-13, IL-22 and TNF-α. Th22 cells express a wide spectrum of chemokine receptors, such as CCR4, CCR6 and CCR10. The main effector molecule secreted by Th22 cells is IL-22, a member of the IL-10 family, which acts by binding to IL-22R and triggering a complex downstream signaling system. Th22 cells and IL-22 have been found to play variable roles in human immunity. In preventing the progression of infections such as HIV and influenza, Th22/IL-22 exhibited protective anti-inflammatory characteristics, and their deleterious proinflammatory activities have been demonstrated to exacerbate other illnesses, including hepatitis B and Helicobacter pylori infection. Herein, we review the current understanding of Th22 cells, including their definition, differentiation and mechanisms, and the effect of Th22/IL-22 on human infectious diseases. According to studies on Th22 cells, Th22/IL-22 may be a promising therapeutic target and an effective treatment strategy for various infections.

Oral and fecal microbiota in patients with diarrheal irritable bowel syndrome

Background

This study aimed at investigating the characteristics and correlation between oral (tongue coating) and fecal microbiota in patients with diarrheal irritable bowel syndrome (IBS-D).

Methods

Fifty-two IBS-D patients were chosen, with ten healthy volunteers serving as the normal control group. Tongue coating samples and fecal samples of subjects were sequenced for the 16S rRNA gene (V4-V5). Bioinformatics analysis was done on the test data to investigate oral and fecal microbiota composition characteristics in IBS-D patients.

Results

The microbial richness of tongue coating in IBS-D group was lower than that in the normal control group (P < 0.05). The beta diversity of tongue coating microbiota and fecal microbiota was significantly different in the IBS-D group compared to the normal control group (P < 0.05). Pseudomonadales (Pseudomonadaceae and Pseudomonas), Moraxellaceae, Parvimonas, Peptostreptococcus, and Alloprevotella were considerably high in number the tongue coating samples of the IBS-D group in comparison to the normal control group. Similarly, the fecal samples from the IBS-D group were significantly enriched in Alphaproteobacteria, Pseudomonadales (Pseudomonadaceae and Pseudomonas), Acidaminococcaceae, Phascolarctobacterium, Alloprevotella, and Escherichia compared to the normal control group.

Conclusions

The oral and fecal microbiotas of IBS-D patients differ from those of the control group; hence studying IBS-D from the perspective of the oral-gut microbiome axis is an interesting research avenue.

Mouse models for bacterial enteropathogen infections: insights into the role of colonization resistance

Globally, enteropathogenic bacteria are a major cause of morbidity and mortality.1-3 Campylobacter, Salmonella, Shiga-toxin-producing Escherichia coli, and Listeria are among the top five most commonly reported zoonotic pathogens in the European Union.4 However, not all individuals naturally exposed to enteropathogens go on to develop disease. This protection is attributable to colonization resistance (CR) conferred by the gut microbiota, as well as an array of physical, chemical, and immunological barriers that limit infection. Despite their importance for human health, a detailed understanding of gastrointestinal barriers to infection is lacking, and further research is required to investigate the mechanisms that underpin inter-individual differences in resistance to gastrointestinal infection. Here, we discuss the current mouse models available to study infections by non-typhoidal Salmonella strains, Citrobacter rodentium (as a model for enteropathogenic and enterohemorrhagic E. coli), Listeria monocytogenes, and Campylobacter jejuni. Clostridioides difficile is included as another important cause of enteric disease in which resistance is dependent upon CR. We outline which parameters of human infection are recapitulated in these mouse models, including the impact of CR, disease pathology, disease progression, and mucosal immune response. This will showcase common virulence strategies, highlight mechanistic differences, and help researchers from microbiology, infectiology, microbiome research, and mucosal immunology to select the optimal mouse model.

Impact of Visceral Obesity on Structural and Functional Alterations of Gut Microbiota in Polycystic Ovary Syndrome (PCOS): A Pilot Study Using Metagenomic Analysis

OBJECTIVE

We aimed to identify structural and functional alterations of gut microbiota associated with visceral obesity in adult women with polycystic ovary syndrome (PCOS).

METHODS

Twenty-seven adults with PCOS underwent stool and fasting blood collection, oral glucose tolerance testing, and visceral fat area (VFA) measurement via dual-bioimpedance technique. Metagenomic analysis was used to analyze gut microbiota.

RESULTS

PCOS patients were divided into three groups: visceral obesity group (PCOS-VO, n=9, age 28.33±5.68 years, BMI 37.06±4.27 kg/m², VFA 128.67±22.45 cm²), non-visceral obesity group (PCOS-NVO, n=10, age 25.40±4.53, BMI 30.74±3.95, VFA 52.00±24.04), normal BMI group (PCOS-NB, n=8, age 27.88±2.53, BMI 21.56±2.20, VFA 27.00±21.18), with no statistical difference in age (P>0.05) and significantly statistical differences in BMI and VFA (P<0.05). The groups showed a significant difference in microbial β-diversity between PCOS-VO and PCOS-NVO (P=0.002) and no difference between PCOS-NVO and PCOS-NB (P=0.177). Bacteroidetes was the phylum with the highest relative abundance among all patients, followed by Firmicutes. Those with visceral obesity had a higher abundance of Prevotella, Megamonas, and Dialister genera, positively correlated with metabolic markers (r>0.4, P<0.05), and lower abundance of Phascolarctobacterium and Neisseria genera, negatively correlated with metabolic markers (r<-0.4, P<0.05). Functional annotation analysis showed significant differences in relative abundance of ribosome pathway, fatty acid biosynthesis pathway, and sphingolipid signaling pathway between groups, affecting lipid homeostasis and visceral fat accumulation.

CONCLUSION

Alteration in β-diversity of gut microbiota exists in PCOS with visceral obesity versus those without visceral obesity and relates to functional differences in ribosomes, fatty acid biosynthesis, and sphingolipid signaling pathways.

Succinate metabolism and its regulation of host-microbe interactions

Succinate is a circulating metabolite, and the relationship between abnormal changes in the physiological concentration of succinate and inflammatory diseases caused by the overreaction of certain immune cells has become a research focus. Recent investigations have shown that succinate produced by the gut microbiota has the potential to regulate host homeostasis and treat diseases such as inflammation. Gut microbes are important for maintaining intestinal homeostasis. Microbial metabolites serve as nutrients in energy metabolism, and act as signal molecules that stimulate host cell and organ function and affect the structural balance between symbiotic gut microorganisms. This review focuses on succinate as a metabolite of both host cells and gut microbes and its involvement in regulating the gut - immune tissue axis by activating intestinal mucosal cells, including macrophages, dendritic cells, and intestinal epithelial cells. We also examined its role as the mediator of microbiota - host crosstalk and its potential function in regulating intestinal microbiota homeostasis. This review explores feasible ways to moderate succinate levels and provides new insights into succinate as a potential target for microbial therapeutics for humans.

A microbiome abundant environment remodels the intestinal microbiota and improves resistance to obesity induced by chlorpyrifos in mice

There is a growing consensus that the appropriate microbiome abundant environment actuates microbiota changes to influence human health. Whether living environment reacts on the threat of contaminants and the underlying mechanism remain largely unknown. Therefore, we constructed microbiome abundant environment models, focusing on their regulatory effects on the obesity induced by the exogenous chemical chlorpyrifos (CPF) and the related mechanisms. The results uncovered that the constructed farm and woodland microbiome abundant environment could protect mice against CPF-induced obesity effectively. The microbiome abundant environment regulated CPF-induced microbiota imbalance, characterized by an increase in Lactobacillus abundance. These altered microbiotas modified the intestinal immune system by increasing the expression of Foxp3 and IL-10, and mitigated intestinal barrier injury by upregulating the expression of IL-22 and intestinal tight junction proteins. Fecal microbiota transplantation could receive similar phenotypes on alleviating CPF-induced obesity development. Our results demonstrate that the microbiome abundant environment attenuates exogenous chemical-induced health risks by remodeling the intestinal microbiota, improving the intestinal ecosystem, and preventing intestinal epithelial leakage.