1,25(OH)2D3 deficiency-induced gut microbial dysbiosis degrades the colonic mucus barrier in Cyp27b1 knockout mouse model

Protective effect of low-dose lactulose in dextran sulfate sodium induced ulcerative colitis model of rats

Although low-dose lactulose has shown a good theoretical foundation for the treatment of ulcerative colitis (UC) in previous studies, the exact effects and mechanism remain unclear. The rats were randomly distributed into 5 groups, i.e., normal drinking water was provided for an initial 14 days in blank control group, 4% dextran sulfate sodium was used for modeling in the remaining 4 groups. During the 15-24th day, rats in the blank control group were administered with 0.9% saline (0.5 ml/d) by gavage. In the rest 4 groups, rats were administered 0.9% saline (0.5 ml/d, UC model), mesalazine (400 mg/kg/d), lactulose (1000 mg/kg/d), and lactulose + mesalazine (two-drug combination) by gavage. In addition to symptoms and pathological changes, serum IL-6, TNF-α, and High-sensitivity C-reactive protein(Hs-CRP) by ELISA analysis, mRNA and protein expression levels of TLR-2, TLR-4, Nuclear factor-κB(NF-κB), IL-6, and TNF-α in colon tissues by RT-qPCR and WB analyses respectively. Meanwhile, short-chain fatty acid(SCFAs) and intestinal flora were analyzed. Low-dose lactulose improved symptoms (diarrhea, blood in stool, weight loss) and pathological inflammation. In addition to serum IL-6, TNF-α, and Hs-CRP, the mRNA and protein expression levels of TLR-2, TLR-4, NF-κB, IL-6 and TNF-α in the colon were down-regulated with the intervention of lactulose.Meanwhile, lactulose decreased the ileocecal PH, increased SCFAs and altered the intestinal flora. Low-dose lactulose may be beneficial to UC by regulating TLRs/NF-κB pathway, reducing ileocecal PH, increasing SCFAs, regulating intestinal flora and improving the intestinal mucosal barrier. Meanwhile, low-dose lactulose and mesalazine may have additive effects upon combination.

Vitamin D and Bone Metabolism in Celiac Disease. The Possibilities of Dietary Correction

The review describes the state of the vitamin D system and bone metabolism in celiac disease, the mechanisms of the influence of vitamin D on the state of the intestinal mucosa, and risk factors that contribute to pathological changes in bones in celiac disease. Studies are presented that evaluate bone mineral density, bone metabolism, and vitamin D status in patients with celiac disease. The results of a discussion on the effect of calcium and vitamin D supplements on the course of celiac disease and the condition of bone tissue in this disease are presented.

Overweight and vitamin D deficiency are common in patients with irritable bowel syndrome - a cross-sectional study

BACKGROUND

Irritable bowel syndrome (IBS) is a common disease with unknown etiology. Poor dietary intake with nutritional deficiency and overweight have been described to increase the risk of IBS. The aim of the present study was to compare weight and circulating levels of micronutrients in IBS compared with healthy controls.

DESIGN

Cross-sectional study.

METHODS

Patients diagnosed with IBS and healthy volunteers were recruited. Participants had to complete a dietary diary book and the questionnaires Rome IV, IBS-severity scoring system (IBS-SSS), and visual analog scale for IBS (VAS-IBS). Weight and height were measured, and blood samples were drawn. C-reactive protein (CRP), cobalamin, folate, iron, total iron-binding capacity (TIBC), and 25-hydroxy (25-OH) vitamin D were analyzed. Differences were calculated between groups and generalized linear model for regressions was adjusted for false discovery rate (FDR).

RESULTS

IBS patients (n = 260) were elder than controls (n = 50) (44.00 (33.25-56.00) vs. 37.85 (30.18-45.48) years; p = 0.012). After adjustment for age, both weight (β: 5.880; 95% CI: 1.433-10.327; p = 0.010, FDR = 0.020) and body mass index (BMI) (β: 2.02; 95% CI: 0.68-3.36; p = 0.003, FDR = 0.012) were higher in patients. Among IBS participants, 48.1% were overweight/obese compared with 26.0% in controls (p = 0.007). Diarrhea-predominated IBS had highest weight (p < 0.001) and BMI (p = 0.077). CRP and cobalamin were higher in patients than controls (p = 0.010 vs. p = 0.007), whereas folate was highest in controls (p = 0.001). IBS patients had lower intake of vegetables (p = 0.026), dairy products (p = 0.004), and cereals (p = 0.010) compared with controls. Despite 21.5% of IBS patients were taking vitamin D supplements, 23.65% of them had vitamin D levels below 50 nmol/L, compared with 26.0% observed in the control group (p = 0.720). Vitamin D levels were lower in overweight than in normal weight IBS patients (60 (48-73) nmol/L vs. 65 (53-78) nmol/L, p = 0.022). Vitamin D correlated with cobalamin and folate but correlated inversely with TIBC and BMI. IBS patients had a high degree of gastrointestinal and extraintestinal symptoms, which were inversely associated with iron levels. Extraintestinal symptoms were associated with increased BMI.

CONCLUSION

IBS patients were often overweight or obese, with low vitamin D levels. High burden of extraintestinal symptoms were associated with overweight and lower iron levels.

REGISTRATION

ClinicalTrials.gov, NCT05192603 (Date of registration 11/29/2021) and NCT03306381 (Date of registration 09/18/2017), respectively.

Regulation of Bacteroides acidifaciens by the aryl hydrocarbon receptor in IL-22-producing immune cells has sex-dependent consequential impact on colitis

Introduction

Colitis is an inflammatory bowel disease (IBD) characterized by immune cell dysregulation and alterations in the gut microbiome. In our previous report, we showed a natural product in cruciferous vegetables and ligand of the aryl hydrocarbon receptor (AhR), indole-3-carbinol (I3C), was able to reduce colitis-induced disease severity and microbial dysbiosis in an interleukin-22 (IL-22) dependent manner.

Methods

In the current study, we performed single-cell RNA sequencing (scRNAseq) from colonocytes during colitis induction and supplementation with I3C and show how this treatment alters expression of genes involved in IL-22 signaling. To further define the role of IL-22 signaling in I3C-mediated protection during colitis and disease-associated microbial dysbiosis, we generated mice with AhR deficiency in RAR-related orphan receptor c (Rorc)-expressing cells (AhR ΔRorc ) which depletes this receptor in immune cells involved in production of IL-22. Colitis was induced in wildtype (WT), AhR ΔRorc , and littermate (LM) mice with or without I3C treatment.

Results

Results showed AhR ΔRorc mice lost the efficacy effects of I3C treatment which correlated with a loss of ability to increase IL-22 by innate lymphoid type 3 (ILC3s), not T helper 22 (Th22) cells. 16S rRNA microbiome profiling studies showed AhR ΔRorc mice were unable to regulate disease-associated increases in Bacteroides, which differed between males and females. Lastly, inoculation with a specific disease-associated Bacteroides species, Bacteroides acidifaciens (B. acidifaciens), was shown to exacerbate colitis in females, but not males.

Discussion

Collectively, this report highlights the cell and sex-specific role of AhR in regulating microbes that can impact colitis disease.

Contemporary Perspectives on the Role of Vitamin D in Enhancing Gut Health and Its Implications for Preventing and Managing Intestinal Diseases

Vitamin D, a crucial fat-soluble vitamin, is primarily synthesized in the skin upon exposure to ultraviolet radiation and is widely recognized as a bone-associated hormone. However, recent scientific advancements have unveiled its intricate association with gut health. The intestinal barrier serves as a vital component, safeguarding the intestinal milieu and maintaining overall homeostasis. Deficiencies in vitamin D have been implicated in altering the gut microbiome composition, compromising the integrity of the intestinal mucosal barrier, and predisposing individuals to various intestinal pathologies. Vitamin D exerts its regulatory function by binding to vitamin D receptors (VDR) present in immune cells, thereby modulating the production of pro-inflammatory cytokines and influencing the intestinal barrier function. Notably, numerous studies have reported lower serum vitamin D levels among patients suffering from intestinal diseases, including inflammatory bowel disease, irritable bowel syndrome, and celiac disease, highlighting the growing significance of vitamin D in gut health maintenance. This comprehensive review delves into the latest advancements in understanding the mechanistic role of vitamin D in modulating the gut microbiome and intestinal barrier function, emphasizing its pivotal role in immune regulation. Furthermore, we consolidate and present relevant findings pertaining to the therapeutic potential of vitamin D in the management of intestinal diseases.

Supplementation of Vitamin D3 and Fructooligosaccharides Downregulates Intestinal Defensins and Reduces the Species Abundance of Romboutsia ilealis in C57BL/6J Mice

The activation of the vitamin D receptor (VDR) in the ileum has been shown to regulate Paneth cell-specific defensins, a large family of antimicrobial peptides; hence, this may serve as a potential mechanism to maintain intestinal homeostasis. Previously, we have demonstrated that a combination of vitamin D3 (VD) and fructooligosaccharides (FOSs) upregulates colonic Vdr in mice. Here, we aim to examine the effect of VD, alone or in combination with FOSs, on intestinal barrier integrity and the secretion of antimicrobial peptides, as well as the gut microbial community. Male and female C57BL/6J mice at 6 weeks old were randomized into three groups to receive the following dietary regimens (n = 10/sex/group) for 8 weeks: (1) standard AIN-93G control diet (CTR), (2) CTR + 5000 IU vitamin D3 (VD), and (3) VD + 5% fructooligosaccharides (VF). VD and VF differentially regulated the mRNA expressions of tight junction proteins in the colon and ileum. VF suppressed the upregulation of colonic ZO-1 and occludin, which was induced by VD supplementation alone. In the ileum, occludin but not ZO-1 was upregulated 20-fold in the VF-treated mice. While VD did not alter the mRNA expressions of Vdr and defensins in the ileum, these targets were downregulated by VF. Microbial analysis further reveals a shift of microbial beta diversity and a reduction in Romboutsia ilealis, a pathobiont, in VF-treated mice. Though the implications of these phenotypical and microbial changes remain to be determined, the administration of FOSs in the presence of VD may serve as an effective dietary intervention for maintaining intestinal homeostasis.

Strain specific differences in vitamin D3 response: impact on gut homeostasis

Vitamin D3 regulates a variety of biological processes irrespective of its well-known importance for calcium metabolism. Epidemiological and animal studies indicate a role in immune regulation, intestinal barrier function and microbiome diversity. Here, we analyzed the impact of different vitamin D3- containing diets on C57BL/6 and BALB/c mice, with a particular focus on gut homeostasis and also investigated effects on immune cells in vitro. Weak regulatory effects were detected on murine T cells. By trend, the active vitamin D3 metabolite 1,25-dihydroxyvitamin D3 suppressed IFN, GM-CSF and IL-10 cytokine secretion in T cells of C57BL/6 but not BALB/c mice, respectively. Using different vitamin D3-fortified diets, we found a tissue-specific enrichment of mainly CD11b+ myeloid cells but not T cells in both mouse strains e.g. in spleen and Peyer's Patches. Mucin Reg3γ and Batf expression, as well as important proteins for gut homeostasis, were significantly suppressed in the small intestine of C57BL76 but not BALB/c mice fed with a high-vitamin D3 containing diet. Differences between both mouse stains were not completely explained by differences in vitamin D3 receptor expression which was strongly expressed in epithelial cells of both strains. Finally, we analyzed gut microbiome and again an impact of vitamin D3 was detected in C57BL76 but not BALB/c. Our data suggest strain-specific differences in vitamin D3 responsiveness under steady state conditions which may have important implications when choosing a murine disease model to study vitamin D3 effects.

Gut microbiota-palmitoleic acid-interleukin-5 axis orchestrates benzene-induced hematopoietic toxicity

Due to the annual increase in its production and consumption in occupational environments, the adverse blood outcomes caused by benzene are of concern. However, the mechanism of benzene-induced hematopoietic damage remains elusive. Here, we report that benzene exposure causes hematopoietic damage in a dose-dependent manner and is associated with disturbances in gut microbiota-long chain fatty acids (LCFAs)-inflammation axis. C57BL/6J mice exposed to benzene for 45 days were found to have a significant reduction in whole blood cells and the suppression of hematopoiesis, an increase in Bacteroides acidifaciens and a decrease in Lactobacillus murinus. Recipient mice transplanted with fecal microbiota from benzene-exposed mice showed potential for hematopoietic disruption, LCFAs, and interleukin-5 (IL-5) elevation. Abnormally elevated plasma LCFAs, especially palmitoleic acid (POA) exacerbated benzene-induced immune-inflammation and hematopoietic damage via carnitine palmitoyltransferase 2 (CPT2)-mediated disorder of fatty acid oxidation. Notably, oral administration of probiotics protects the mice against benzene-induced hematopoietic toxicity. In summary, our data reveal that the gut microbiota-POA-IL-5 axis is engaged in benzene-induced hematopoietic damage. Probiotics might be a promising candidate to prevent hematopoietic abnormalities from benzene exposure.

Linking serum vitamin D levels with gut microbiota after 1-year lifestyle intervention with Mediterranean diet in patients with obesity and metabolic syndrome: a nested cross-sectional and prospective study

Vitamin D, microbiota, and the Mediterranean diet (MedDiet) have been the focus of recent research due to their potential role in maintaining overall health. We hypothesize that MedDiet may alter the gut microbiota profile through changes in vitamin D levels. We aimed to investigate changes in gut microbiota and serum vitamin D levels after a MedDiet within a lifestyle intervention. The study included 91 patients with obesity and metabolic syndrome, who were categorized based on their serum vitamin D levels as having either optimal or low 25-hydroxyvitamin D [25(OH)D levels]. The profile of the gut microbiota was analyzed by the 16S rRNA sequencing, inferring its functionality through PICRUsT. Participants underwent a hypocaloric MedDiet and change in their lifestyle for 1 year, and the profile and functionality of their gut microbiota were evaluated by analyzing inter-individual differences in time. At baseline, gut microbiota profiles qualitatively differed between participants with Optimal or Low 25(OH)D levels [Unweighted (p = 0.016)]. Moreover, participants with Optimal 25(OH)D levels showed a higher gut microbiota diversity than those with Low 25(OH)D levels (p < 0.05). The differential analysis of abundance between the Low and Optimal 25(OH)D groups revealed differences in the levels of Bacteroides, Prevotella, and two Clostridiales features. After 1-year dietary intervention, both groups increased their 25(OH)D levels. Furthermore, both groups did not show significant differences in gut microbiota diversity, although the Low 25(OH)D group showed greater improvement in gut microbiota diversity by comparing at baseline and after dietary intervention (p < 0.05). Changes in specific bacterial taxa were observed within each group but did not differ significantly between the groups. Metabolic pathway analysis indicated differences in microbial functions between the groups (p < 0.05). These findings suggest that 25(OH)D status is associated with gut microbiota composition, diversity, and functionality, and lifestyle intervention can modulate both gut microbiota and 25(OH)D levels, potentially influencing metabolic pathways.

Ring1a protects against colitis through regulating mucosal immune system and colonic microbial ecology

Inflammatory bowel disease (IBD) represents a prominent chronic immune-mediated inflammatory disorder, yet its etiology remains poorly comprehended, encompassing intricate interactions between genetics, immunity, and the gut microbiome. This study uncovers a novel colitis-associated risk gene, namely Ring1a, which regulates the mucosal immune response and intestinal microbiota. Ring1a deficiency exacerbates colitis by impairing the immune system. Concomitantly, Ring1a deficiency led to a Prevotella genus-dominated pathogenic microenvironment, which can be horizontally transmitted to co-housed wild type (WT) mice, consequently intensifying dextran sodium sulfate (DSS)-induced colitis. Furthermore, we identified a potential mechanism linking the altered microbiota in Ring1aKO mice to decreased levels of IgA, and we demonstrated that metronidazole administration could ameliorate colitis progression in Ring1aKO mice, likely by reducing the abundance of the Prevotella genus. We also elucidated the immune landscape of DSS colitis and revealed the disruption of intestinal immune homeostasis associated with Ring1a deficiency. Collectively, these findings highlight Ring1a as a prospective candidate risk gene for colitis and suggest metronidazole as a potential therapeutic option for clinically managing Prevotella genus-dominated colitis.

The Gut and Skin Microbiome in Alopecia: Associations and Interventions

Objective

This review examines the current literature on the gut-skin connection in alopecia and summarizes interventions that impact hair growth by modulation of the gut or skin microbiome.

Methods

PubMed searches were done to assess studies of the gut and skin microbiome and forms of alopecia including, alopecia areata (AA), androgenic alopecia (AGA), alopecia universalis (AU), central centrifugal cicatricial alopecia (CCCA) and lichen planopilaris (LPP). Filters were applied for human and animal studies. Articles not translated to English and studies assessing supplemental therapies on alopecia were excluded.

Results

There is evidence that scalp, hair follicle, and gut microbiome alterations are associated with various types of alopecia. There is potential in the use of interventions targeting microbiome dysbiosis, including fecal transplants and probiotics.

Limitations

This field of study still requires more high-quality research and studies with larger participant populations.

Conclusion

Dysbiosis on the scalp, within the hair follicle and the gut seem to have a role in the pathophysiology of various forms of alopecia. There is evidence that interventions targeting dysbiosis may have potential in the treatment and management of hair loss. Further studies are needed to establish a direct connection and to clarify specific effects of these interventions.

Developmental vitamin D-deficiency produces autism-relevant behaviours and gut-health associated alterations in a rat model

Developmental vitamin D (DVD)-deficiency is an epidemiologically established risk factor for autism. Emerging studies also highlight the involvement of gut microbiome/gut physiology in autism. The current study aims to examine the effect of DVD-deficiency on a broad range of autism-relevant behavioural phenotypes and gut health. Vitamin D deficient rat dams exhibited altered maternal care, DVD-deficient pups showed increased ultrasonic vocalizations and as adolescents, social behaviour impairments and increased repetitive self-grooming behaviour. There were significant impacts of DVD-deficiency on gut health demonstrated by alterations to the microbiome, decreased villi length and increased ileal propionate levels. Overall, our animal model of this epidemiologically validated risk exposure for autism shows an expanded range of autism-related behavioural phenotypes and now alterations in gut microbiome that correlate with social behavioural deficits raising the possibility that DVD-deficiency induced ASD-like behaviours are due to alterations in gut health.

Role of Akkermansia in Human Diseases: From Causation to Therapeutic Properties

The gut microbiota plays a critical role in the modulation of host metabolism and immune response, and its impairment has been implicated in many gastrointestinal and extraintestinal diseases. Current evidence shows the well-documented role of A. muciniphila in maintaining the integrity of the intestinal barrier, modulating the host immune response, and improving several metabolic pathways, making it a key element in the pathogenesis of several human diseases. In this scenario, A. muciniphila is the most promising next-generation probiotic and one of the first microbial species suitable for specific clinical use when compared with traditional probiotics. Further studies are needed to provide more accurate insight into its mechanisms of action and to better elucidate its properties in several major areas, paving the way for a more integrated and personalized therapeutic approach that finally makes the most of our knowledge of the gut microbiota.

Modulation of allergic contact dermatitis via gut microbiota modified by diet, vitamins, probiotics, prebiotics, and antibiotics

Allergic contact dermatitis is one of the most common recorded occupational diseases. There are many different substances that the skin comes into contact with on a daily basis and that can cause ACD, e.g., preservatives, surfactants, and antimicrobial agents. The development of a mouse model of ACD has provided insight into the immune mechanisms involved. Drugs used in the treatment of skin diseases have many side effects. Therefore, alternative methods of suppressing the immune response to reduce the symptoms of skin diseases are being sought. In recent years, high hopes have been placed on dietary modulation and supplementation to affect the intestinal microbial composition and promote anti-inflammatory responses. In addition, other studies have shown the crucial role of intestinal microbiota in many immune-mediated diseases. Recognition and characterization of pro- and anti-inflammatory nutrients and supplements may be crucial to support the treatment of diseases such as atopic dermatitis, acne vulgaris, psoriasis, and allergic contact dermatitis.

Immunomodulatory Properties of Vitamin D in the Intestinal and Respiratory Systems

Vitamin D plays a crucial role in modulating the innate immune response by interacting with its intracellular receptor, VDR. In this review, we address vitamin D/VDR signaling and how it contributes to the regulation of intestinal and respiratory microbiota. We additionally review some components of the innate immune system, such as the barrier function of the pulmonary and intestinal epithelial membranes and secretion of mucus, with their respective modulation by vitamin D. We also explore the mechanisms by which this vitamin D/VDR signaling mounts an antimicrobial response through the transduction of microbial signals and the production of antimicrobial peptides that constitute one of the body’s first lines of defense against pathogens. Additionally, we highlight the role of vitamin D in clinical diseases, namely inflammatory bowel disease and acute respiratory distress syndrome, where excessive inflammatory responses and dysbiosis are hallmarks. Increasing evidence suggests that vitamin D supplementation may have potentially beneficial effects on those diseases.

Vitamin D and Microbiome: Molecular Interaction in Inflammatory Bowel Disease Pathogenesis

Studies of systemic autoimmune diseases point to characteristic microbial patterns in various diseases, including inflammatory bowel disease (IBD). Autoimmune diseases, and IBD in particular, show a predisposition to vitamin D deficiency, leading to alterations in the microbiome and disruption of intestinal epithelial barrier integrity. In this review, we examine the role of the gut microbiome in IBD and discuss how vitamin D-vitamin D receptor (VDR)-associated molecular signaling pathways contribute to the development and progression of IBD through their effects on gut barrier function, the microbial community, and immune system function. The present data demonstrate that vitamin D promotes the proper function of the innate immune system by acting as an immunomodulator, exerting anti-inflammatory effects, and critically contributing to the maintenance of gut barrier integrity and modulation of the gut microbiota, mechanisms that may influence the IBD development and progression. VDR regulates the biological effects of vitamin D and is related to environmental, genetic, immunologic, and microbial aspects of IBD. Vitamin D influences the distribution of the fecal microbiota, with high vitamin D levels associated with increased levels of beneficial bacterial species and lower levels of pathogenic bacteria. Understanding the cellular functions of vitamin D-VDR signaling in intestinal epithelial cells may pave the way for the development of new treatment strategies for the therapeutic armamentarium of IBD in the near future.

The interaction between obesity and visceral hypersensitivity

Obesity has been a worldwide problem associated with numerous chronic diseases such as cardiovascular disease, type 2 diabetes, and metabolic disorders. It may also play a role in visceral hypersensitivity, contributing to irritable bowel syndrome. (i) Adipose tissue secretes various inflammatory mediators, causing intestinal hyperpermeability and nerve endings activation. (ii) Obesity and gastrointestinal microbiota could affect each other, and microbial metabolites can increase sensitivity of the colon. (iii) Vitamin D deficiency contributes to both fat accumulation and disruption of the intestinal mucosal barrier. (iv) Brain-gut axis may be another bridge from obesity to visceral hypersensitivity.

Vitamin D3 alleviates inflammation in ulcerative colitis by activating the VDR-NLRP6 signaling pathway

Inflammation is a key factor in the development of ulcerative colitis (UC). 1,25-dihydroxyvitamin D3 (1,25(OH)2D3, VD3), as the major active ingredient of vitamin D and an anti-inflammatory activator, is closely related to the initiation and development of UC, but its regulatory mechanism remains unclear. In this study, we carried out histological and physiological analyses in UC patients and UC mice. RNA sequencing (RNA-seq), assays for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), chromatin immunoprecipitation (ChIP) assays and protein and mRNA expression were performed to analyze and identify the potential molecular mechanism in UC mice and lipopolysaccharide (LPS)-induced mouse intestinal epithelial cells (MIECs). Moreover, we established nucleotide-binding oligomerization domain (NOD)-like receptor protein nlrp6 -/- mice and siRNA-NLRP6 MIECs to further characterize the role of NLRP6 in anti-inflammation of VD3. Our study revealed that VD3 abolished NOD-like receptor protein 6 (NLRP6) inflammasome activation, suppressing NLRP6, apoptosis-associated speck-like protein (ASC) and Caspase-1 levels via the vitamin D receptor (VDR). ChIP and ATAC-seq showed that VDR transcriptionally repressed NLRP6 by binding to vitamin D response elements (VDREs) in the promoter of NLRP6, impairing UC development. Importantly, VD3 had both preventive and therapeutic effects on the UC mouse model via inhibition of NLRP6 inflammasome activation. Our results demonstrated that VD3 substantially represses inflammation and the development of UC in vivo. These findings reveal a new mechanism by which VD3 affects inflammation in UC by regulating the expression of NLRP6 and show the potential clinical use of VD3 in autoimmune syndromes or other NLRP6 inflammasome-driven inflammatory diseases.

The role of Akkermansia muciniphila in inflammatory bowel disease: Current knowledge and perspectives

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, is a chronic relapsing gastrointestinal inflammatory disease mediated by dysregulated immune responses to resident intestinal microbiota. Current conventional approaches including aminosalicylates, corticosteroids, immunosuppressive agents, and biological therapies are focused on reducing intestinal inflammation besides inducing and maintaining disease remission, and managing complications. However, these therapies are not curative and are associated with various limitations, such as drug resistance, low responsiveness and adverse events. Recent accumulated evidence has revealed the involvement of mucin-degrading bacterium Akkermansia muciniphila (A. muciniphila) in the regulation of host barrier function and immune response, and how reduced intestinal colonisation of probiotic A. muciniphila can contribute to the process and development of inflammatory bowel diseases, suggesting that it may be a potential target and promising strategy for the therapy of inflammatory bowel disease. In this review, we summarise the current knowledge of the role of A. muciniphila in IBD, especially focusing on the related mechanisms, as well as the strategies based on supplementation with A. muciniphila, probiotics and prebiotics, natural diets, drugs, and herbs to promote its colonisation in the gut, and holds promise for A. muciniphila-targeted and -based therapies in the treatment of inflammatory bowel disease.

Role of Vitamin D in Celiac Disease and Inflammatory Bowel Diseases

Vitamin D (VD) is a pro-hormone that has long been known as a key regulator of calcium homeostasis and bone health in both children and adults. In recent years, studies have shown that VD may exert many extra-skeletal functions, mainly through a relevant modulation of the innate and adaptive immune system. This has suggested that VD could play a fundamental role in conditioning development, clinical course, and treatment of several autoimmune disorders, including celiac disease (CD) and inflammatory bowel diseases (IBDs). The main aim of this review is to evaluate the relationships between VD, CD, and IBDs. Literature analysis showed a potential impact of VD on CD and IBDs can be reasonably assumed based on the well-documented in vitro and in vivo VD activities on the gastrointestinal tract and the immune system. The evidence that VD can preserve intestinal mucosa from chemical and immunological damage and that VD modulation of the immune system functions can contrast the mechanisms that lead to the intestinal modifications characteristic of gastrointestinal autoimmune diseases has suggested that VD could play a role in controlling both the development and the course of CD and IBDs. Administration of VD in already diagnosed CD and IBD cases has not always significantly modified disease course. However, despite these relevant problems, most of the experts recommend monitoring of VD levels in patients with CD and IBDs and administration of supplements in patients with hypovitaminosis.

Changes in Metabolic Parameters in Patients with Diabetic Kidney Disease Depending on the Status of D3

BACKGROUND

Type 2 diabetes is a metabolic disease characterized by hyperglycemia as a result of insulin resistance and decreased insulin secretion. A relatively large number of patients with this type of diabetes have abdominal obesity, which also affects insulin resistance development. Chronic hyperglycemia can lead to damage and dysfunction of various organs, and a striking example is diabetic nephropathy. Diabetic nephropathy is a specific kind of kidney damage that occurs due to complications of diabetes and is accompanied by the formation of diffuse or nodular glomerulosclerosis, which can lead to terminal renal failure and requires immediate substitution through renal therapy or renal transplantation. Diabetic nephropathy is diagnosed with albuminuria and a decrease in the rate of glomerular filtration.

METHODS

This review was based on a literature search for the most important evidence of vitamin D as a possible method of prevention for obesity, type 2 diabetes, and diabetic nephropathy. Collected published articles were summarized according to their overall themes.

RESULTS

In this review, we considered vitamin D as a possible method of treatment for type 2 diabetes, as well as its complications, including diabetic nephropathy.

CONCLUSION

Studies show that vitamin D inhibits the renin-angiotensin-aldosterone system, resulting in improved renal function in diabetic nephropathy. Vitamin D also has antiinflammatory, antiproliferative, and anti-metastatic effects, which improve endothelial function.

Heterophil/Lymphocyte Ratio Level Modulates Salmonella Resistance, Cecal Microbiota Composition and Functional Capacity in Infected Chicken

The gastrointestinal microbiota plays a vital role in ensuring the maintenance of host health through interactions with the immune system. The Heterophil/Lymphocyte (H/L) ratio reflects poultry’s robustness and immune system status. Chickens with low H/L ratio are superior to the chickens with high H/L ratio in survival, immune response, and resistance to Salmonella infection, but the underlying mechanisms remain unclear. This study aimed to identify microorganisms associated with resistance to Salmonella Enteritidis infection in chickens based on the H/L ratio. The 16S rRNA and metagenomic analysis were conducted to examine microbiome and functional capacity between the 2 groups, and Short Chain Fatty Acids (SCFAs) and histopathology were conducted to explore the potential difference between susceptible and resistant groups at 7 and 21 days post-infection (dpi). The microbiome exploration revealed that low H/L ratio chickens, compared to high H/L ratio chickens, displayed a significantly higher abundance of Proteobacteria (Escherichia coli) and Bacteroidetes (Bacteroides plebeius) at 7 and 21 dpi, respectively. Anaerostipes (r = 0.63) and Lachnoclostridium (r = 0.63) were identified as bacterial genus significantly correlated with H/L (P < 0.001). Interestingly, Bacteroides was significantly and positively correlated with bodyweight post-infection (r = 0.72), propionate (r = 0.78) and valerate (r = 0.82) contents, while Salmonella was significantly and negatively correlated with bodyweight post-infection (r = − 0.67), propionate (r = − 0.61) and valerate (r = − 0.65) contents (P < 0.001). Furthermore, the comparative analysis of the functional capacity of cecal microbiota of the chickens with high and low H/L ratio revealed that the chickens with low H/L ratio possess more enriched immune pathways, lower antibiotic resistance genes and virulence factors compared to the chickens with high H/L ratio. These results suggest that the chickens with low H/L ratio are more resistant to Salmonella Enteritidis, and it is possible that the commensal Proteobacteria and Bacteroidetes are involved in this resistance against Salmonella infection. These findings provide valuable resources for selecting and breeding disease-resistant chickens.

Preventing Bacterial Translocation in Patients with Leaky Gut Syndrome: Nutrition and Pharmacological Treatment Options

Leaky gut syndrome is a medical condition characterized by intestinal hyperpermeability. Since the intestinal barrier is one of the essential components maintaining homeostasis along the gastrointestinal tract, loss of its integrity due to changes in bacterial composition, decreased expression levels of tight junction proteins, and increased concentration of pro-inflammatory cytokines may lead to intestinal hyperpermeability followed by the development of gastrointestinal and non-gastrointestinal diseases. Translocation of microorganisms and their toxic metabolites beyond the gastrointestinal tract is one of the fallouts of the leaky gut syndrome. The presence of intestinal bacteria in sterile tissues and distant organs may cause damage due to chronic inflammation and progression of disorders, including inflammatory bowel diseases, liver cirrhosis, and acute pancreatitis. Currently, there are no medical guidelines for the treatment or prevention of bacterial translocation in patients with the leaky gut syndrome; however, several studies suggest that dietary intervention can improve barrier function and restrict bacteria invasion. This review contains current literature data concerning the influence of diet, dietary supplements, probiotics, and drugs on intestinal permeability and bacterial translocation.

Role of vitamin D in ulcerative colitis: an update on basic research and therapeutic applications

INTRODUCTION

Vitamin D deficiency is common in patients with ulcerative colitis (UC). Moreover, vitamin D supplementation seems to contribute to disease relief. Nevertheless, the exact etiological link between vitamin D deficiency and UC is far from clear, and an agreement has not been reached on the frequency and dosage of vitamin D supplementation required.

AREAS COVERED

This review will outline the possible role of vitamin D in the pathogenesis of UC and summarize the current state of clinical research on vitamin D. Literature was searched on PUBMED, with 'Vitamin D,' 'Ulcerative colitis,' 'Vitamin D receptor,' and 'disease activity' as MeSH Terms. Relevant information is presented in figures or tables.

EXPERT OPINION

The etiological relationship between vitamin D and the onset of UC is still being researched. More high-quality double-blind randomized clinical studies are needed to determine the efficacy of vitamin D supplementation in the treatment of UC, whether as the main treatment or as an adjuvant treatment. Importantly, determining the dosage and frequency of vitamin D supplementation should be the main research direction in the future, and regional factors should also be fully considered in this respect.

A β-N-acetylhexosaminidase Amuc_2109 from Akkermansia muciniphila protects against dextran sulfate sodium-induced colitis in mice by enhancing intestinal barrier and modulating gut microbiota

Inflammatory bowel disease (IBD) is associated with the microbial composition of the gut and its metabolites. Akkermansia muciniphila is a probiotic that exerts a significant alleviative or therapeutic effect on host enteritis. This study was designed to determine the protective effect and potential mechanism underlying the secretion of β-acetylaminohexosidase (Amuc_2109) by A. muciniphila against dextran sulfate sodium (DSS)-induced colitis in mice. C57BL/6 mice were gavaged with Amuc_2109 for 21 days, and during the last seven days of treatment, they drank DSS dissolved in their drinking water to induce colitis. Our results showed that supplementation with Amuc_2109 improved DSS-induced colitis as evidenced by lowered disease activity index (DAI) scores, reduced weight loss, increased colon length, and inhibited oxidative stress. In addition, Amuc_2109 inhibited the overexpression of inflammatory cytokines (TNF-α, IL-1β, IL-6) and the NLR family pyrin domain containing 3 (NLRP3) inflammasome in DSS-induced colitis. Furthermore, supplementation with Amuc_2109 also restored the mRNA expression of tight junction proteins (ZO-1, occludin, claudin-1). Further analysis of fecal microbial 16S rRNA sequences showed that Amuc_2109 reshaped the intestinal microbiota. While the anti-inflammatory effects of Amuc_2109 were only manifested with the wild-type protein, the anti-inflammatory effects were completely lost after the mutation of its key catalytic amino acids rendered Amuc_2109 inactive. In summary, these findings demonstrate the potential of Amuc_2109, as a therapeutic agent for ulcerative colitis. We posit that it will provide additional assistance in the prevention and treatment of mucus layer-related diseases such as ulcerative colitis.

Gegen Qinlian Decoction Alleviates Experimental Colitis and Concurrent Lung Inflammation by Inhibiting the Recruitment of Inflammatory Myeloid Cells and Restoring Microbial Balance

Objective

Ulcerative colitis (UC) as one of the intractable diseases in gastroenterology seriously threatens human health. Respiratory pathology is a representative extraintestinal manifestation of UC affecting the quality of life of patients. Gegen Qinlian Decoction (GQD) is a classical traditional Chinese medicine prescription for UC or acute lung injury. This study was aimed to reveal the therapeutic effect of GQD on UC and its pulmonary complications and uncover its molecular mechanism mediated by myeloid cells and microbiota.

Methods

Mice with DSS-induced colitis were orally administrated with GQD. Overall vital signs were assessed by body weight loss and disease activity index (DAI). Pulmonary general signs were evaluated by pulmonary pathology and lung function. The mechanism of GQD relieving UC was characterized by detecting myeloid cells (neutrophils, macrophages, inflammatory monocytes, and resident monocytes) in colonic and lung tissues, related inflammatory cytokines, as well as the microbiota in bronchoalveolar lavage fluid (BALF) and feces.

Results

GQD significantly reduced weight loss, DAI scores, and lung injury but improved the lung function of colitis mice. The DSS-induced colonic and concurrent pulmonary inflammation were also alleviated by GQD, as indicated by the down-regulated expressions of inflammatory cytokines (TNF-α, IL-1β, IL-6, CCR2, and CCL2) and the suppressed recruitment of neutrophils and inflammatory monocytes. Meanwhile, GQD greatly improved intestinal microbiota imbalance by enriching Ruminococcaceae UCG-013 while decreasing Parabacteroides, [Eubacterium]_fissicatena_group, and Akkermansia in the feces of colitis mice. Expectantly, GQD also restored lung microbiota imbalance by clearing excessive Coprococcus 2 and Ochrobactrum in the BALF of colitis mice. Finally, significant correlations appeared between GQD-mediated specific bacteria and inflammatory cytokines or immune cells.

Conclusion

GQD could alleviate UC by decreasing excessive inflammatory myeloid cells and cytokines, and reshaping the microbiota between the colon and lung, which contributes to clarifying the mechanism by which GQD ameliorates colitis-associated pulmonary inflammation.

Vitamin D in Inflammatory Bowel Diseases. Mechanisms of Action and Therapeutic Implications

(1) Background: Vitamin D is an immunoregulatory factor influencing intestinal homeostasis. Recent evidence supports a central role of this micronutrient in the course of Inflammatory Bowel Diseases (IBD). This narrative review aims to provide a general overview of the possible biological mechanisms of action of vitamin D and its therapeutic implications in IBD. (2) Methods: A systematic electronic search of the English literature up to October 2021 was performed using Medline and the Cochrane Library. Only papers written in English that analyzed the role of vitamin D in IBD were included. (3) Results: In vitro and animal studies reported that vitamin D signaling improves epithelial barrier integrity regulating the expression of several junctional proteins, defensins, and mucins, modulates the inflammatory response, and affects gut microbiome composition. Recent studies also suggest that vitamin D deficiency is highly prevalent among IBD patients and that low serum levels correlate with disease activity and, less clearly, with disease course. (4) Conclusions: An increasing body of evidence suggests some role of vitamin D in the pathophysiology of IBD, nonetheless the underlying mechanisms have been so far only partially elucidated. A strong correlation with disease activity has been reported but its implication in the treatment is still undefined. Thus, studies focused on this issue, the definition of vitamin D levels responsible for clinical effects, and the potential role of vitamin D as a therapeutic agent are strongly encouraged.

Structural and Functional Alterations of Gut Microbiota in Males With Hyperuricemia and High Levels of Liver Enzymes

Objective: To investigate the correlation between the structure and function alterations of gut microbiota and biochemical indicators in males with hyperuricemia (HUA) and high levels of liver enzymes, in order to provide new evidences and therapeutic targets for the clinical diagnosis and treatment of HUA. Methods: A total of 69 patients with HUA (HUA group) and 118 healthy controls were enrolled in this study. Their age, height, waist circumference, weight, and pressure were measured. The clinical parameters such as fasting plasma glucose (FBG), aspartate aminotransferase (AST), alanine aminotransferase (ALT), serum uric acid (SUA), serum creatinine (Scr), total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), white blood cell (WBC), platelet (PLT), and absolute value of neutrophils (NEUT) were examined. We used whole-genome shotgun sequencing technology and HUMAnN2 MetaCyc pathway database to detect the composition and pathways of the gut microbiota. The main statistical methods were student's t test, chi-square tests, and Wilcoxon rank sum test. The correlations among bacterial diversity, microbial pathways, and biochemical indicators were evaluated by the R function "cor.test" with spearman method. Results: The gut bacterial diversity in HUA group reduced significantly and the community of the microbiota was of significant difference between the two groups. The pathways that can produce 5-aminoimidazole ribonucleotide (PWY-6122, PWY-6277, and PWY-6121), aromatic amino acids, and chorismate (COMPLETE-ARO-PWY, ARO-PWY, and PWY-6163) were enriched in the HUA group; while the pathways that can produce short-chain fatty acids (SCFAs, such as CENTFERM-PWY and PWY-6590) and the gut microbiotas that can produce SCFAs (Roseburia hominis, Odoribacter splanchnicus, Ruminococcus callidus, Lachnospiraceae bacterium 3_1_46FAA, Bacteroides uniformis, Butyricimonas synergistica) and equol (Adlercreutzia equolifaciens) were enriched in healthy controls. Conclusion: The structure and function of the gut microbiota in males with HUA and high levels of liver enzymes have altered apparently. In-depth study of related mechanisms may provide new ideas for the treatment of HUA.

Microplastic: A potential threat to human and animal health by interfering with the intestinal barrier function and changing the intestinal microenvironment

Plastics are widely used in many fields due to their stable physical and chemical properties, and their global production and usage increase significantly every year, which leads to the accumulation of microplastics in the entire ecosystem. Numerous studies have shown that microplastics (MPs) have harmful effects on living organisms. This review aims to provide a comprehensive conclusion of the current knowledge of the impacts of MPs on the stability of the gut microenvironment, especially on the gut barrier. Studies showed that exposure to MPs could cause oxidative damage and inflammation in the gut, as well as the destruction of the gut epithelium, reduction of the mucus layer, microbial disorders, and immune cell toxicity. Although there are few reports directly related to humans, we hoped that this review could bring together more and more evidence that exposure to MPs results in disturbances of the intestinal microenvironment. Therefore, it is necessary to investigate their threats to human health further.

Lactococcus lactis Delivery of Surface Layer Protein A Protects Mice from Colitis by Re-Setting Host Immune Repertoire

Inflammatory bowel disease (IBD) is characterized by gastrointestinal inflammation comprised of Crohn's disease and ulcerative colitis. Centers for Disease Control and Prevention report that 1.3% of the population of the United States (approximately 3 million people) were affected by the disease in 2015, and the number keeps increasing over time. IBD has a multifactorial etiology, from genetic to environmental factors. Most of the IBD treatments revolve around disease management, by reducing the inflammatory signals. We previously identified the surface layer protein A (SlpA) of Lactobacillus acidophilus that possesses anti-inflammatory properties to mitigate murine colitis. Herein, we expressed SlpA in a clinically relevant, food-grade Lactococcus lactis to further investigate and characterize the protective mechanisms of the actions of SlpA. Oral administration of SlpA-expressing L. lactis (R110) mitigated the symptoms of murine colitis. Oral delivery of R110 resulted in a higher expression of IL-27 by myeloid cells, with a synchronous increase in IL-10 and cMAF in T cells. Consistent with murine studies, human dendritic cells exposed to R110 showed exquisite differential gene regulation, including IL-27 transcription, suggesting a shared mechanism between the two species, hence positioning R110 as potentially effective at treating colitis in humans.

The potential of Akkermansia muciniphila in inflammatory bowel disease

Akkermansia muciniphila is a next-generation probiotic with significant application prospects. The role of A. muciniphila in metabolic diseases and tumor immunotherapy has been widely recognized. Recent clinical trials further confirmed its safety and therapeutic value in human metabolic diseases. A. muciniphila also shows potential in the treatment of intestinal inflammatory diseases, especially for inflammatory bowel disease (IBD). The improvement in the efficacy of washed microbiota transplantation (WMT) in treating IBD is closely related to the increase in the abundance of A. muciniphila in patients' gut. However, there is still controversy regarding the pro-inflammatory or anti-inflammatory effect of A. muciniphila on IBD. Currently, several studies targeting the correlation between A. muciniphila and IBD have demonstrated opposite conclusions. Similarly, the interventional studies exploring causality between them also come to conflicting results. This article therefore aims to review the relationship between A. muciniphila and IBD, the effect of intervention of A. muciniphila on IBD, and the possible reasons for the contradictory role of A. muciniphila in the treatment of IBD. KEY POINTS: The effect of A. muciniphila on inflammatory bowel disease is controversy. A. muciniphila shows anti-inflammatory potential in IBD. The colitogenicity of A. muciniphila is context dependent.

Impact of diet and the bacterial microbiome on the mucous barrier and immune disorders

The prevalence of chronic immune and metabolic disorders is increasing rapidly. In particular, inflammatory bowel diseases, obesity, diabetes, asthma and chronic obstructive pulmonary disease have become major healthcare and economic burdens worldwide. Recent advances in microbiome research have led to significant discoveries of associative links between alterations in the microbiome and health, as well as these chronic supposedly noncommunicable, immune/metabolic disorders. Importantly, the interplay between diet, microbiome and the mucous barrier in these diseases has gained significant attention. Diet modulates the mucous barrier via alterations in gut microbiota, resulting in either disease onset/exacerbation due to a "poor" diet or protection against disease with a "healthy" diet. In addition, many mucosa-associated disorders possess a specific gut microbiome fingerprint associated with the composition of the mucous barrier, which is further influenced by host-microbiome and inter-microbial interactions, dietary choices, microbe immigration and antimicrobials. Our review focuses on the interactions of diet (macronutrients and micronutrients), gut microbiota and mucous barriers (gastrointestinal and respiratory tract) and their importance in the onset and/or progression of major immune/metabolic disorders. We also highlight the key mechanisms that could be targeted therapeutically to prevent and/or treat these disorders.

Microbe-Mucus Interface in the Pathogenesis of Colorectal Cancer

Overlying gastrointestinal epithelial cells is the transparent mucus layer that separates the lumen from the host. The dynamic mucus layer serves to lubricate the mucosal surface, to protect underlying epithelial cells, and as a transport medium between luminal contents and epithelial cells. Furthermore, it provides a habitat for commensal bacteria and signals to the underlying immune system. Mucins are highly glycosylated proteins, and their glycocode is tissue-specific and closely linked to the resident microbiota. Aberrant mucin expression and glycosylation are linked to chronic inflammation and gastrointestinal cancers, including colorectal cancer (CRC). Aberrant mucus production compromises the mucus layer and allows bacteria to come into close contact with the intestinal epithelium, potentially triggering unfavorable host responses and the subsequent development of tumors. Here, we review our current understanding of the interaction between the intestinal microbiota and mucus in healthy and CRC subjects. Deep knowledge of the intricate mechanisms of microbe-mucus interactions may contribute to the development of novel treatment strategies for CRC, in which a dysfunctional mucus layer is observed.

Probing the Scope and Mechanisms of Calcitriol Actions Using Genetically Modified Mouse Models

Genetically modified mice have provided novel insights into the mechanisms of activation and inactivation of vitamin D, and in the process have provided phenocopies of acquired human disease such as rickets and osteomalacia and inherited diseases such as pseudovitamin D deficiency rickets, hereditary vitamin D resistant rickets, and idiopathic infantile hypercalcemia. Both global and tissue-specific deletion studies leading to decreases of the active form of vitamin D, calcitriol [1,25(OH)2D], and/or of the vitamin D receptor (VDR), have demonstrated the primary role of calcitriol and VDR in bone, cartilage and tooth development and in the regulation of mineral metabolism and of parathyroid hormone (PTH) and FGF23, which modulate calcium and phosphate fluxes. They have also, however, extended the spectrum of actions of calcitriol and the VDR to include, among others: modulation, jointly and independently, of skin metabolism; joint regulation of adipose tissue metabolism; cardiovascular function; and immune function. Genetic studies in older mice have also shed light on the molecular mechanisms underlying the important role of the calcitriol/VDR pathway in diseases of aging such as osteoporosis and cancer. In the course of these studies in diverse tissues, important upstream and downstream, often tissue-selective, pathways have been illuminated, and intracrine, as well as endocrine actions have been described. Human studies to date have focused on acquired or genetic deficiencies of the prohormone vitamin D or the (generally inactive) precursor metabolite 25-hyrodxyvitamin D, but have yet to probe the pleiotropic aspects of deficiency of the active form of vitamin D, calcitriol, in human disease. © 2020 American Society for Bone and Mineral Research © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bile Acid Signaling in Inflammatory Bowel Diseases

Bile acids are a group of chemically different steroids generated at the host/microbial interface. Indeed, while primary bile acids are the end-product of cholesterol breakdown in the host liver, secondary bile acids are the products of microbial metabolism. Primary and secondary bile acids along with their oxo derivatives have been identified as signaling molecules acting on a family of cell membrane and nuclear receptors collectively known as "bile acid-activated receptors." Members of this group of receptors are highly expressed throughout the gastrointestinal tract and mediate the bilateral communications of the intestinal microbiota with the host immune system. The expression and function of bile acid-activated receptors FXR, GPBAR1, PXR, VDR, and RORγt are highly dependent on the structure of the intestinal microbiota and negatively regulated by intestinal inflammation. Studies from gene ablated mice have demonstrated that FXR and GPBAR1 are essential to maintain a tolerogenic phenotype in the intestine, and their ablation promotes the polarization of intestinal T cells and macrophages toward a pro-inflammatory phenotype. RORγt inhibition by oxo-bile acids is essential to constrain Th17 polarization of intestinal lymphocytes. Gene-wide association studies and functional characterizations suggest a potential role for impaired bile acid signaling in development inflammatory bowel diseases (IBD). In this review, we will focus on how bile acids and their receptors mediate communications of intestinal microbiota with the intestinal immune system, describing dynamic changes of bile acid metabolism in IBD and the potential therapeutic application of targeting bile acid signaling in these disorders.

Difference in Vitamin D Levels Between Children with Clostridioides difficile Enteritis and Those with Other Acute Infectious Enteritis

PURPOSE

A steady increase in Clostridioides difficile enteritis (CDE) has been reported recently. CDE is associated with intestinal dysbiosis, and vitamin D receptors are known to play an important role in this microbial imbalance as immunological regulators. We investigated the difference in vitamin D levels between children with CDE and those with other acute infectious enteritis.

METHODS

This retrospective study was conducted on children below 18 years of age who visited the Gil hospital, underwent investigation to assess vitamin D levels, and had confirmed gastrointestinal infection between January 2015 and December 2018. Patients were divided into two groups: the "CDE group" (n=18) and the "other infectious enteritis group" (n=88); their clinical characteristics, other laboratory results, and vitamin D levels were analyzed.

RESULTS

There was no difference in gender, age, and seasonal distributions between the CDE and other infectious enteritis groups. Other laboratory results were not significantly different between two groups, excluding serum albumin level (4.52±0.45 g/dL vs. 4.31±0.28 g/dL, p=0.011). The mean 25-hydroxy vitamin D level in the CDE group was higher than that in the control group (18.75±8.11 ng/mL vs. 14.50±6.79 ng/mL, p=0.021).

CONCLUSION

Vitamin D levels in the CDE group were lower than normal but higher than the other infectious enteritis group. These results suggested that CDE has a different mechanism or susceptibility associated with vitamin D in children, and even marginal changes in vitamin D levels can act as a risk factor for infection.

Vitamin D Modulates Intestinal Microbiota in Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract (GIT), including Crohn's disease (CD) and ulcerative colitis (UC), which differ in the location and lesion extensions. Both diseases are associated with microbiota dysbiosis, with a reduced population of butyrate-producing species, abnormal inflammatory response, and micronutrient deficiency (e.g., vitamin D hypovitaminosis). Vitamin D (VitD) is involved in immune cell differentiation, gut microbiota modulation, gene transcription, and barrier integrity. Vitamin D receptor (VDR) regulates the biological actions of the active VitD (1α,25-dihydroxyvitamin D3), and is involved in the genetic, environmental, immune, and microbial aspects of IBD. VitD deficiency is correlated with disease activity and its administration targeting a concentration of 30 ng/mL may have the potential to reduce disease activity. Moreover, VDR regulates functions of T cells and Paneth cells and modulates release of antimicrobial peptides in gut microbiota-host interactions. Meanwhile, beneficial microbial metabolites, e.g., butyrate, upregulate the VDR signaling. In this review, we summarize the clinical progress and mechanism studies on VitD/VDR related to gut microbiota modulation in IBD. We also discuss epigenetics in IBD and the probiotic regulation of VDR. Furthermore, we discuss the existing challenges and future directions. There is a lack of well-designed clinical trials exploring the appropriate dose and the influence of gender, age, ethnicity, genetics, microbiome, and metabolic disorders in IBD subtypes. To move forward, we need well-designed therapeutic studies to examine whether enhanced vitamin D will restore functions of VDR and microbiome in inhibiting chronic inflammation.

Metabolic and functional interplay between gut microbiota and fat-soluble vitamins

Gut microbiota is a complex ecosystem seen as an extension of human genome. It represents a major metabolic interface of interaction with food components and xenobiotics in the gastrointestinal (GI) environment. In this context, the advent of modern bacterial genome sequencing technology has enabled the identification of dietary nutrients as key determinants of gut microbial ecosystem able to modulate the host-microbiome symbiotic relationship and its effects on human health. This article provides a literature review on functional and molecular interactions between a specific group of lipids and essential nutrients, e.g., fat-soluble vitamins (FSVs), and the gut microbiota. A two-way relationship appears to emerge from the available literature with important effects on human metabolism, nutrition, GI physiology and immune function. First, FSV directly or indirectly modify the microbial composition involving for example immune system-mediated and/or metabolic mechanisms of bacterial growth or inhibition. Second, the gut microbiota influences at different levels the synthesis, metabolism and transport of FSV including their bioactive metabolites that are either introduced with the diet or released in the gut via entero-hepatic circulation. A better understanding of these interactions, and of their impact on intestinal and metabolic homeostasis, will be pivotal to design new and more efficient strategies of disease prevention and therapy, and personalized nutrition.

Vitamin D and intestinal homeostasis: Barrier, microbiota, and immune modulation

Vitamin D plays a pivotal role in intestinal homeostasis. Vitamin D can impact the function of virtually every cell in the gut by binding to its intracellular receptor (VDR) and subsequently transcribing relevant genes. In the lumen, the mucus layer and the underlying epithelium serve to keep resident microbiota at bay. Vitamin D ensures an appropriate level of antimicrobial peptides in the mucus and maintains epithelial integrity by reinforcing intercellular junctions. Should bacteria penetrate the epithelial layer and enter the interstitium, immune sentinel cells (e.g. macrophages, dendritic cells, and innate lymphoid cells) elicit inflammation and trigger the adaptive immune response by activating Th1/Th17 cells. Vitamin D/VDR signaling in these cells ensures clearance of the bacteria. Subsequently, vitamin D also quiets the adaptive immune system by suppressing the Th1/Th17 cells and favoring Treg cells. The importance of vitamin D/VDR signaling in intestinal homeostasis is evidenced by the development of a chronic inflammatory state (e.g. IBD) when this signaling system is disrupted.

Vitamin D and Its Potential Interplay With Pain Signaling Pathways

About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.

Vitamin D, gut microbiota, and radiation-related resistance: a love-hate triangle

Radiation resistance is a serious issue in radiotherapy. Increasing evidence indicates that the human gut microbiome plays a role in the development of radiation resistance. Vitamin D is an important supplement for cancer patients treated with radiotherapy. Against this background, this paper reviewed research regarding the associations among vitamin D, microbiota dysbiosis, and radiation resistance. A hypothesis is developed to describe the relationships among vitamin D, the gut microbiota, and radiotherapy outcomes. Radiotherapy changes the composition of the gut microbiota, which in turn influence the serum level of vitamin D, and its distribution and metabolism in the body. Alteration of vitamin D level influences the patient response to radiotherapy, where the underlying mechanisms may be associated with the intestinal microenvironment, immune molecules in the intestines, gut microbiome metabolites, and signaling pathways associated with vitamin D receptors. Our understanding of the contribution of vitamin D and the gut microbiota to radiotherapy outcomes has been increasing gradually. A better understanding of the relationships among vitamin D, the gut microbiota, and radiotherapy outcomes will shed more light on radiation resistance, and also promote the development of new strategies for overcoming it, thus addressing an important challenge associated with the currently available radiotherapy modalities for cancer patients.

Undigested Food and Gut Microbiota May Cooperate in the Pathogenesis of Neuroinflammatory Diseases: A Matter of Barriers and a Proposal on the Origin of Organ Specificity

As food is an active subject and may have anti-inflammatory or pro-inflammatory effects, dietary habits may modulate the low-grade neuroinflammation associated with chronic neurodegenerative diseases. Food is living matter different from us, but made of our own nature. Therefore, it is at the same time foreign to us (non-self), if not yet digested, and like us (self), after its complete digestion. To avoid the efflux of undigested food from the lumen, the intestinal barrier must remain intact. What and how much we eat shape the composition of gut microbiota. Gut dysbiosis, as a consequence of Western diets, leads to intestinal inflammation and a leaky intestinal barrier. The efflux of undigested food, microbes, endotoxins, as well as immune-competent cells and molecules, causes chronic systemic inflammation. Opening of the blood-brain barrier may trigger microglia and astrocytes and set up neuroinflammation. We suggest that what determines the organ specificity of the autoimmune-inflammatory process may depend on food antigens resembling proteins of the organ being attacked. This applies to the brain and neuroinflammatory diseases, as to other organs and other diseases, including cancer. Understanding the cooperation between microbiota and undigested food in inflammatory diseases may clarify organ specificity, allow the setting up of adequate experimental models of disease and develop targeted dietary interventions.

Hair regrowth following fecal microbiota transplantation in an elderly patient with alopecia areata: A case report and review of the literature

BACKGROUND

Alopecia areata is a hair loss disease associated with genetics, autoimmunity, and other factors. There is an intriguing link between alopecia areata and gut dysbiosis. Fecal microbiota transplantation (FMT) has been recommended to treat Clostridium difficile (previously known as Clostridioides difficile) infection, and has also shown potentials in the treatment of inflammatory bowel disease, irritable bowel syndrome, and non-alcohol fatty liver disease.

CASE SUMMARY

An 86-year-old man, with a history of sigmoid colon carcinoma, suffered from recurrent abdominal pain and distension, and diarrhea for six months, with inappetence. At admission, he was also diagnosed with depression. Upon physical examination, the patient presented with a 1.5 cm × 2.0 cm alopecia areata on his right occiput. Due to the negative results of laboratory testing, capsule endoscopy, and colonoscopy, the patient was diagnosed with noninfectious diarrhea, depressive disorder, and patchy alopecia areata. Considering that noninfectious diarrhea in the elderly patient was mainly caused by gut dysbiosis, he was given six rounds of FMT. His diarrhea improved remarkably one month after FMT, with improved appetite and disappearance of abdominal pain, distension, and depressive symptoms. Surprisingly, he reported new hair growth on the affected region of his scalp, with some of his white hair gradually turning to black, without taking any other therapies for alopecia areata before and after FMT.

CONCLUSION

FMT might act as a potential therapy for patients who suffer from alopecia areata. Large and well-designed studies are required to confirm the role of FMT in alopecia areata.

Purified fraction of polysaccharides from Fuzhuan brick tea modulates the composition and metabolism of gut microbiota in anaerobic fermentation in vitro

One purified fraction from crude Fuzhuan brick tea polysaccharides (FBTPS), FBTPS-3, was obtained through column chromatography of DEAE Sepharose Fast Flow. The chemical properties and probiotic effects of FBTPS-3 were evaluated by fermentation in vitro. Moreover, the effects of FBTPS-3 on the function and metabolic pathway of gut microbiota were investigated by metagenomic sequencing. The results showed that FBTPS-3 was an heteropolysaccharide with molecular weight of 741 kDa, which was mainly composed of Man, Rha, GalA, Gal and Ara in molar ratio of 8.7:15.5:42.2:19.7:13.9. The contents of carbohydrates and uronic acid in FBTPS-3 were 44.78 ± 2.85% and 40.4 ± 2.11%, respectively. After fermentation, the molecular weight of FBTPS-3 and content of carbohydrates were significantly decreased, indicating that FBTPS-3 could be utilized by gut microbiota. Furthermore, the relative abundances of Bacteroides, Megasphaera and Prevotella were significantly increased by FBTPS-3. FBTPS-3 also significantly promoted the production of acetic, propionic and n-butyric acids. Based on the metagenomic sequencing, it was found that FBTPS-3 significantly enriched the metabolic pathway of starch and sucrose. All the results suggest that FBTPS-3 is expected to be developed as functional ingredients or foods to improve the host health through regulating the gut microbiota and physiological metabolic functions.