Keep calm: the intestinal barrier at the interface of peace and war

Nicotinamide Alleviates Synergistic Impairment of Intestinal Barrier Caused by MC-LR and NaNO2 Coexposure

Microcystin-LR (MC-LR) and nitrites from the environment and daily life can be ingested and absorbed by humans via the digestive tract. However, their combined effects on intestinal health remain unclear. Here, the combined impact of MC-LR and sodium nitrite (NaNO2) on the intestines of mice was investigated under actual human exposure conditions. After mice were exposed to MC-LR (10, 100 μg/L) and NaNO2 (30, 300 mg/L) individual and in combination for 6 months, it was found that MC-LR and NaNO2 synergistically decreased intestinal permeability and disrupted intestinal physical, chemical, immune, and microbial barriers. In the coexposure groups, the synergistic impairment to the intestinal barrier was noted with increasing concentrations of MC-LR or NaNO2, but this adverse effect was alleviated by nicotinamide supplementation. This study underscores the potential risks of simultaneous ingestion of MC-LR and nitrite on intestinal health. The protective role of nicotinamide suggests avenues for therapeutic intervention against environmental toxin-induced intestinal impairment.

Lipid signature associated with chronic colon inflammation reveals a dysregulation in colonocyte differentiation process

Inflammatory Bowel Disease (IBD) comprises a heterogeneous group of chronic inflammatory conditions of the gastrointestinal tract that include ulcerative colitis (UC) and Crohn's disease. Although the etiology is not well understood, IBD is characterized by a loss of the normal epithelium homeostasis that disrupts the intestinal barrier of these patients. Previous work by our group demonstrated that epithelial homeostasis along the colonic crypts involves a tight regulation of lipid profiles. To evaluate whether lipidomic profiles conveyed the functional alterations observed in the colonic epithelium of IBD, we performed matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) analyses of endoscopic biopsies from inflamed and non-inflamed segments obtained from UC patients. Our results indicated that lipid profiling of epithelial cells discriminated between healthy and UC patients. We also demonstrated that epithelial cells of the inflamed mucosa were characterized by a decrease in mono- and di-unsaturated fatty acid-containing phospholipids and higher levels of arachidonic acid-containing species, suggesting an alteration of the lipid gradients occurring concomitantly to the epithelial differentiation. This result was reinforced by the immunofluorescence analysis of EPHB2 and HPGD, markers of epithelial cell differentiation, sustaining that altered lipid profiles were at least partially due to a faulty differentiation process. Overall, our results showed that lipid profiling by MALDI-MSI faithfully conveys molecular and functional alterations associated with the inflamed epithelium, providing the foundation for a novel molecular characterization of UC patients.

Isatidis Folium Represses Dextran Sulfate Sodium-Induced Colitis and Suppresses the Inflammatory Response by Inhibiting Inflammasome Activation

BACKGROUND/OBJECTIVES

Isatidis Folium (IF) has been used in traditional medicine for various ailments, and recent research highlights its anti-inflammatory, antiviral, and detoxifying properties. This study investigated the anti-inflammatory effects of a hydroethanolic extract of IF (EIF) on inflammasomes and colitis.

METHODS

Dextran sulfate sodium (DSS)-induced colitis model C57BL/6 mice were treated with DSS, mesalamine, or EIF (200 mg/kg). Parameters such as daily disease activity index (DAI), spleen weight, colon length, and histopathology were evaluated. Intestinal fibrosis, mucin, and tight junction proteins were assessed using Masson's trichrome, periodic acid-Schiff, and immunohistochemistry staining. RAW264.7 and J774a.1 macrophages were treated with EIF and lipopolysaccharide, with cell viability assessed via the cell counting kit-8 assay, nitric oxide (NO) production with Griess reagent, and cytokine levels with the enzyme-linked immunosorbent assay. NF-κB inhibition was analyzed using the luciferase assay, and phytochemical analysis was performed using UPLC-MS/MS.

RESULTS

EIF mitigated weight loss, reduced DAI scores, prevented colon shortening, and attenuated mucosal damage, fibrosis, and goblet cell loss while enhancing the tight junction protein occludin. The anti-inflammatory effects of EIF in RAW264.7 cells included reduced NO production, pro-inflammatory cytokines, and NF-κB activity, along with inhibition of NLRP3 inflammasome responses in J774a.1 cells. The key constituents identified were tryptanthrin, indigo, and indirubin.

CONCLUSIONS

Animal studies demonstrated the efficacy of EIF in alleviating colitis, suggesting its potential for treating inflammatory diseases.

Natural polysaccharides as promising reno-protective agents for the treatment of various kidney injury

Renal injury, a prevalent clinical outcome with multifactorial etiology, imposes a substantial burden on society. Currently, there remains a lack of effective management and treatments. Extensive research has emphasized the diverse biological effects of natural polysaccharides, which exhibit promising potential for mitigating renal damage. This review commences with the pathogenesis of four common renal diseases and the shared mechanisms underlying renal injury. The renoprotective roles of polysaccharides in vivo and in vitro are summarized in the following five aspects: anti-oxidative stress effects, anti-apoptotic effects, anti-inflammatory effects, anti-fibrotic effects, and gut modulatory effects. Furthermore, we explore the structure-activity relationship and bioavailability of polysaccharides in relation to renal injury, as well as investigate their utility as biomaterials for alleviating renal injury. The clinical experiments of polysaccharides applied to patients with chronic kidney disease are also reviewed. Broadly, this review provides a comprehensive perspective on the research direction of natural polysaccharides in the context of renal injury, with the primary aim to serve as a reference for the clinical development of polysaccharides as pharmaceuticals and prebiotics for the treatment of kidney diseases.

Methionine-choline deficient diet deteriorates DSS-induced murine colitis through disturbance of gut microbes and infiltration of macrophages

Ulcerative colitis (UC) is associated with changed dietary habits and mainly linked with the gut microbiota dysbiosis, necroptosis of epithelial cells, and mucosal ulcerations. Liver dysfunction and abnormal level of liver metabolism indices were identified in UC patients, suggesting a close interaction between gut and liver disorders. Methionine-choline deficient diet (MCD) has been shown to induce persistent alterations of gut microbiota and metabolome during hepatitis. In this study we further explored the disease phenotypes in UC patients and investigated whether MCD functioned as a trigger for UC susceptibility. After assessing 88 serum specimens from UC patients, we found significant liver dysfunction and dyslipidemia including abnormal ALT, AST, TG, TC, LDL-c and HDL-c. Liver dysfunction and dyslipidemia were confirmed in DSS-induced colitis mice. We fed mice with MCD for 14 days to cause mild liver damage, and then treated with DSS for 7 days. We found that MCD intake significantly exacerbated the pathogenesis of mucosal inflammation in DSS-induced acute, progressive, and chronic colitis, referring to promotion of mucosal ulcers, colon shortening, diarrhea, inflammatory immune cell infiltration, cytokines release, and abnormal activation of inflammatory macrophages in colon and liver specimens. Intraperitoneal injection of clodronate liposomes to globally delete macrophages dramatically compromised the pathogenesis of MCD-triggering colitis. In addition, MCD intake markedly changed the production pattern of short-chain fatty acids (SCFAs) in murine stools, colons, and livers. We demonstrated that MCD-induced colitis pathogenesis largely depended on the gut microbes and the disease phenotypes could be transmissible through fecal microbiota transplantation (FMT). In conclusion, this study supports the concept that intake of MCD predisposes to experimental colitis and enhances its pathogenesis via modulating gut microbes and macrophages in mice.

Toxigenic Clostridium perfringens Isolated from At-Risk Paediatric Inflammatory Bowel Disease Patients

BACKGROUND AND AIMS

This study aimed to identify microbial drivers of inflammatory bowel disease [IBD], by investigating mucosal-associated bacteria and their detrimental products in IBD patients.

METHODS

We directly cultured bacterial communities from mucosal biopsies from paediatric gastrointestinal patients and examined for pathogenicity-associated traits. Upon identifying Clostridium perfringens as toxigenic bacteria present in mucosal biopsies, we isolated strains and further characterized toxicity and prevalence.

RESULTS

Mucosal biopsy microbial composition differed from corresponding stool samples. C. perfringens was present in eight of nine patients' mucosal biopsies, correlating with haemolytic activity, but was not present in all corresponding stool samples. Large IBD datasets showed higher C. perfringens prevalence in stool samples of IBD adults [18.7-27.1%] versus healthy controls [5.1%]. In vitro, C. perfringens supernatants were toxic to cell types beneath the intestinal epithelial barrier, including endothelial cells, neuroblasts, and neutrophils, while the impact on epithelial cells was less pronounced, suggesting C. perfringens may be particularly damaging when barrier integrity is compromised. Further characterization using purified toxins and genetic insertion mutants confirmed perfringolysin O [PFO] toxin was sufficient for toxicity. Toxin RNA signatures were found in the original patient biopsies by PCR, suggesting intestinal production. C. perfringens supernatants also induced activation of neuroblast and dorsal root ganglion neurons in vitro, suggesting C. perfringens in inflamed mucosal tissue may directly contribute to abdominal pain, a frequent IBD symptom.

CONCLUSIONS

Gastrointestinal carriage of certain toxigenic C. perfringens may have an important pathogenic impact on IBD patients. These findings support routine monitoring of C. perfringens and PFO toxins and potential treatment in patients.

Gut microbiota composition links to variation in functional domains across psychiatric disorders

OBJECTIVE

Changes in microbial composition are observed in various psychiatric disorders, but their specificity to certain symptoms or processes remains unclear. This study explores the associations between the gut microbiota composition and the Research Domain Criteria (RDoC) domains of functioning, representing symptom domains, specifically focusing on stress-related and neurodevelopmental disorders in patients with and without psychiatric comorbidity.

METHODS

The gut microbiota was analyzed in 369 participants, comprising 272 individuals diagnosed with a mood disorder, anxiety disorder, attention deficit/hyperactivity disorder, autism spectrum disorder, and/or substance use disorder, as well as 97 psychiatrically unaffected individuals. The RDoC domains were estimated using principal component analysis (PCA) with oblique rotation on a range of psychiatric, psychological, and personality measures. Associations between the gut microbiota and the functional domains were assessed using multiple linear regression and permanova, adjusted for age, sex, diet, smoking, medication use and comorbidity status.

RESULTS

Four functional domains, aligning with RDoC's negative valence, social processes, cognitive systems, and arousal/regulatory systems domains, were identified. Significant associations were found between these domains and eight microbial genera, including associations of negative valence with the abundance of the genera Sellimonas, CHKCI001, Clostridium sensu stricto 1, Oscillibacter, and Flavonifractor; social processes with Sellimonas; cognitive systems with Sporobacter and Hungatella; and arousal/regulatory systems with Ruminococcus torques (all pFDR < 0.05).

CONCLUSION

Our findings demonstrate associations between the gut microbiota and the domains of functioning across patients and unaffected individuals, potentially mediated by immune-related processes. These results open avenues for microbiota-focused personalized interventions, considering psychiatric comorbidity. However, further research is warranted to establish causality and elucidate mechanistic pathways.

Formyl peptide receptor 1 mitigates colon inflammation and maintains mucosal homeostasis through the inhibition of CREB-C/EBPβ-S100a8 signaling

Excessive inflammatory responses are the main characteristic of ulcerative colitis (UC). Activation of formyl peptide receptor 1 (FPR1) has been found to promote the proliferation and migration of epithelial cells, but its role and therapeutic potential in UC remain unclear. This study observed an increased expression of FPR1 in a mouse model of colitis. Interestingly, FPR1 deficiency exacerbated UC and increased the secretion of the proinflammatory mediator from immune cells (e.g. macrophages), S100a8, a member of the damage-associated molecular patterns. Notably, the administration of the FPR agonist Cmpd43 ameliorated colon injury in a preclinical mice model of UC, likely via inhibiting phosphorylation of cyclic adenosine monophosphate-response element-binding protein and expression of CCAAT/enhancer-binding protein β, which in turn suppressed the secretion of S100a8. In conclusion, these findings discovered a novel role of FPR1 in the development of colitis and will facilitate the development of FPR1-based pharmacotherapy to treat UC.

Expression of genes related to ileal barrier function in heritage and modern broiler chickens

1. An experiment was conducted to determine differences in the expression of genes encoding intestinal barrier proteins between fast, medium and slow-growing chickens. Chicken breeds Athens Canadian Random Bred (ACRB), Longenecker's Heritage (LHR), RedBro, Hubbard H1 (HH1), Cobb500 and Ross708 were raised from hatch for 35 d.2. Ileal samples were collected at embryonic day E19 (-2 days post-hatch), hatch and d 7, 14, 21, 28 and 35 post-hatch to assess the expression of genes encoding tight junction proteins (claudins, CLDN; occludin, OCLN; zonula occludens, ZO; and junctional adhesion molecules, JAM), mucin (Muc2), immunoglobulin A (IgA), polymeric immunoglobulin receptor (pIgR) and fatty acid binding protein (FABP2).3. Expression of CLDN-1 was increased (p < 0.0001) in LHR compared to Cobb500 while CLDN-5 was increased (p < 0.0001) in ACRB, HH1, RedBro and Ross708 compared to LHR as well as in ACRB compared to Cob500. Occludin was upregulated (p = 0.01) in ACRB and LHR compared to Ross708 at d 14 post-hatch. Expression of ZO-1 was upregulated (p = 0.001) in LHR compared to Ross708, HH1 and Cobb500. Tight junction genes, except CLDN-4, JAM-2 and JAM-3 were downregulated (p < 0.0001) at hatch and d 7 post-hatch. Expression of Muc2 was increased (p < 0.0001) in LHR compared to RedBro and from -2 d to d 7 post-hatch.4. Immunoglobulin A was increased (p = 0.001) in LHR compared to Ross708 and HH1 at -2 d post-hatch and in LHR compared to ACRB, Cobb500 and Ross708 at hatch. In addition, IgA expression was increased in all breeds at d 14 post-hatch while pIgR was upregulated (p = 0.02) in Cobb500 and Ross708 compared to ACRB, HH1, LHR and RedBro at hatch.5. The gene expression patterns suggest that selection for growth may have not induced changes in junctional complexes and immune defence genes. However, the results confirmed that the expression of these genes is age dependent.

Bile acid metabolism modulates intestinal immunity involved in ulcerative colitis progression

The bile acids (BA) in the intestine promote inflammation by interacting with immune cells, playing a crucial role in the progression of UC, but the specific mechanism between the two remains elusive. This study aims to explore the relationship between BAMand UC inflammation and determine its potential mechanisms.Firstly, we employed a hybrid approach using Lasso regression and support vector machine (SVM) feature selection in bioinformatics to identify genes linked to UC and BAM. The relationship between these genes and immune infiltration was explored, along with their correlation with immune factors in the Tumor-Immune System Interaction Database (TISIDB) database. Gene Set Enrichment Analysis (GSEA) pathway enrichment analysis was then used to predict signaling pathways associated with key genes in UC. Single-cell data from the GSE13464 dataset was also analyzed. Finally, Five differentially expressed genes (DEGs) related to BAM (APOA1, AMACR, PEX19, CH25H, and AQP9) were significantly upregulated/downregulated in UC immune cells. The expression of important genes in UC tissue was confirmed in the experimental validation section and AQP9, which showed significant differential expression, was chosen for further validation. The results showed that the AQP9 gene may regulate the IFN - γ/JAK signaling axis, thereby promoting CD8+T cell activation. This research has greatly advanced our comprehension of the pathogenesis and underlying mechanism of BAM in immune cells linked to UC.

Geranylgeranylacetone mitigates sepsis-associated intestinal injury through CHIP-dependent anti-inflammation and anti-oxidative effect

Geranylgeranylacetone (GGA), an isoprenoid compound widely utilized as an antiulcer agent in Asia, confers protection against ischemia, anoxia, and oxidative stress by rapidly enhancing the expression of HSP70. Nevertheless, the impact of GGA on sepsis-associated intestinal injury remains unexplored. Thus, this study is crafted to elucidate the protective efficacy and underlying mechanisms of GGA against septic intestinal damage. Our findings revealed that GGA significantly extended the survival duration of septic mice, and mitigated lipopolysaccharide (LPS)-induced alterations in intestinal permeability and tissue damage. Furthermore, GGA effectively suppressed LPS-induced cytokine release, attenuated levels of reactive oxygen species (ROS) and malondialdehyde, and bolstered antioxidant-related parameters within the intestinal tissue of LPS-stimulated mice. Mechanistically, GGA significantly increased HSP70 expression and promoted E3 ubiquitin ligase CHIP to play the role in ubiquitination and degradation of karyopherin-α2 (KPNA2), resulting in inhibition of nuclear translocation of NF-κB and reduced NOX1, NOX2 and NOX4 expression. The inhibitory action of GGA on cytokine release and ROS generation was abolished by CHIP knockdown in IEC-6 cells treated with LPS. Simultaneously, the downregulation of CHIP reversed the suppressive role of GGA in the LPS-induced NF-κB activation and the expression of NOX1, NOX2 and NOX4 in IEC-6 cells. The effects of GGA on mitigating intestinal damage, inflammation and oxidative stress caused by LPS were eliminated in CHIP knockout mice. Our results demonstrate that the protective effect of GGA against LPS-caused intestinal injury of mice is dependent on CHIP activation, which promotes KPNA2 degradation and restrains translocation of NF-κB into nucleus, leading to suppressing LPS-induced inflammatory response and oxidative stress.

Organic Iodine Improves the Growth Performance and Gut Health of Fujian Yellow Rabbits

Organic iodine is a new trace element additive that is highly efficient in regulating cell growth, function, and metabolism. This study demonstrated that organic iodine improves the growth performance and gut health of Fujian yellow rabbits. A total of 160 healthy rabbits of similar weight were randomly divided into four groups, which were treated with organic iodine (0, 0.5, 1.0, and 1.5 mg/kg) for 60 days. Our results indicated that organic iodine improved the growth performance, including significantly increased BW, ADG, and ADFI, and decreased F/G notably. Organic iodine improved the content of T3, T4, IgM, IgA, and IgM in serum, and intestinal mucosal immunity (IL-1α, IL-2, and sIgA). Organic iodine supplementation ameliorated gut morphometry and morphology, such as higher villus height and lower crypt depth. Organic iodine increased the amount of goblet cells significantly. The 0.5 mg/kg organic iodine most increased the activities of amylase, cellulase, and trypsin in caecum. Organic iodine induced more active caecum fermentation, higher NH3-N, acetic acid, propionic acid, and butyric acid, while lowering PH. In conclusion, organic iodine improved the growth performance and gut morphometry and morphology, and increased caecum enzyme activities, active caecum fermentation, and intestinal immunity of Fujian yellow rabbits.

Paeoniflorin ameliorates chronic colitis via the DR3 signaling pathway in group 3 innate lymphoid cells

Inhibiting the death receptor 3 (DR3) signaling pathway in group 3 innate lymphoid cells (ILC3s) presents a promising approach for promoting mucosal repair in individuals with ulcerative colitis (UC). Paeoniflorin, a prominent component of Paeonia lactiflora Pall., has demonstrated the ability to restore barrier function in UC mice, but the precise mechanism remains unclear. In this study, we aimed to delve into whether paeoniflorin may promote intestinal mucosal repair in chronic colitis by inhibiting DR3 signaling in ILC3s. C57BL/6 mice were subjected to random allocation into 7 distinct groups, namely the control group, the 2 % dextran sodium sulfate (DSS) group, the paeoniflorin groups (25, 50, and 100 mg/kg), the anti-tumor necrosis factor-like ligand 1A (anti-TL1A) antibody group, and the IgG group. We detected the expression of DR3 signaling pathway proteins and the proportion of ILC3s in the mouse colon using Western blot and flow cytometry, respectively. Meanwhile, DR3-overexpressing MNK-3 cells and 2 % DSS-induced Rag1-/- mice were used for verification. The results showed that paeoniflorin alleviated DSS-induced chronic colitis and repaired the intestinal mucosal barrier. Simultaneously, paeoniflorin inhibited the DR3 signaling pathway in ILC3s and regulated the content of cytokines (Interleukin-17A, Granulocyte-macrophage colony stimulating factor, and Interleukin-22). Alternatively, paeoniflorin directly inhibited the DR3 signaling pathway in ILC3s to repair mucosal damage independently of the adaptive immune system. We additionally confirmed that paeoniflorin-conditioned medium (CM) restored the expression of tight junctions in Caco-2 cells via coculture. In conclusion, paeoniflorin ameliorates chronic colitis by enhancing the intestinal barrier in an ILC3-dependent manner, and its mechanism is associated with the inhibition of the DR3 signaling pathway.

Neuropeptide substance P attenuates colitis by suppressing inflammation and ferroptosis via the cGAS-STING signaling pathway

Neuropeptide substance P (SP) belongs to a family of bioactive peptides and regulates many human diseases. This study aims to investigate the role and underlying mechanisms of SP in colitis. Here, activated SP-positive neurons and increased SP expression were observed in dextran sodium sulfate (DSS)-induced colitis lesions in mice. Administration of exogenous SP efficiently ameliorated the clinical symptoms, impaired intestinal barrier function, and inflammatory response. Mechanistically, SP protected mitochondria from damage caused by DSS or TNF-α exposure, preventing mitochondrial DNA (mtDNA) leakage into the cytoplasm, thereby inhibiting the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. SP can also directly prevent STING phosphorylation through the neurokinin-1 receptor (NK1R), thereby inhibiting the activation of the TBK1-IRF3 signaling pathway. Further studies revealed that SP alleviated the DSS or TNF-α-induced ferroptosis process, which was associated with repressing the cGAS-STING signaling pathway. Notably, we identified that the NK1R inhibition reversed the effects of SP on inflammation and ferroptosis via the cGAS-STING pathway. Collectively, we unveil that SP attenuates inflammation and ferroptosis via suppressing the mtDNA-cGAS-STING or directly acting on the STING pathway, contributing to improving colitis in an NK1R-dependent manner. These findings provide a novel mechanism of SP regulating ulcerative colitis (UC) disease.

Human in vitro blood barrier models: architectures and applications

Blood barriers serve as key points of transport for essential molecules as well as lines of defense to protect against toxins. In vitro modeling of these barriers is common practice in the study of their physiology and related diseases. This review describes a common method of using an adaptable, low cost, semipermeable, suspended membrane to experimentally model three blood barriers in the human body: the blood-brain barrier (BBB), the gut-blood barrier (GBB), and the air-blood barrier (ABB). The GBB and ABB both protect from the outside environment, while the BBB protects the central nervous system from potential neurotoxic agents in the blood. These barriers share several commonalities, including the formation of tight junctions, polarized cellular monolayers, and circulatory system contact. Cell architectures used to mimic barrier anatomy as well as applications to study function, dysfunction, and response provide an overview of the versatility enabled by these cultural systems.

The interaction of inflammasomes and gut microbiota: novel therapeutic insights

Inflammasomes are complex platforms for the cleavage and release of inactivated IL-1β and IL-18 cytokines that trigger inflammatory responses against damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). Gut microbiota plays a pivotal role in maintaining gut homeostasis. Inflammasome activation needs to be tightly regulated to limit aberrant activation and bystander damage to the host cells. Several types of inflammasomes, including Node-like receptor protein family (e.g., NLRP1, NLRP3, NLRP6, NLRP12, NLRC4), PYHIN family, and pyrin inflammasomes, interact with gut microbiota to maintain gut homeostasis. This review discusses the current understanding of how inflammasomes and microbiota interact, and how this interaction impacts human health. Additionally, we introduce novel biologics and antagonists, such as inhibitors of IL-1β and inflammasomes, as therapeutic strategies for treating gastrointestinal disorders when inflammasomes are dysregulated or the composition of gut microbiota changes.

Crosstalk between hypoxia-inducible factor-1α and short-chain fatty acids in inflammatory bowel disease: key clues toward unraveling the mystery

The human intestinal tract constitutes a complex ecosystem, made up of countless gut microbiota, metabolites, and immune cells, with hypoxia being a fundamental environmental characteristic of this ecology. Under normal physiological conditions, a delicate balance exists among these complex "residents", with disruptions potentially leading to inflammatory bowel disease (IBD). The core pathology of IBD features a disrupted intestinal epithelial barrier, alongside evident immune and microecological disturbances. Central to these interconnected networks is hypoxia-inducible factor-1α (HIF-1α), which is a key regulator in gut cells for adapting to hypoxic conditions and maintaining gut homeostasis. Short-chain fatty acids (SCFAs), as pivotal gut metabolites, serve as vital mediators between the host and microbiota, and significantly influence intestinal ecosystem. Recent years have seen a surge in research on the roles and therapeutic potential of HIF-1α and SCFAs in IBD independently, yet reviews on HIF-1α-mediated SCFAs regulation of IBD under hypoxic conditions are scarce. This article summarizes evidence of the interplay and regulatory relationship between SCFAs and HIF-1α in IBD, pivotal for elucidating the disease's pathogenesis and offering promising therapeutic strategies.

How dietary advanced glycation end products could facilitate the occurrence of food allergy

BACKGROUND

Food allergy (FA) is one of the most common chronic conditions in children with an increasing prevalence facilitated by the exposure to environmental factors in predisposed individuals. It has been hypothesized that the increased consumption of ultra-processed foods, containing high levels of dietary advanced glycation end products (AGEs), could facilitate the occurrence of FA.

OBJECTIVE

We sought to provide preclinical and clinical evidence on the potential role of AGEs in facilitating the occurrence of FA.

METHODS

Human enterocytes, human small intestine organ culture, and PBMCs from children at risk for allergy were used to investigate the direct effect of AGEs on gut barrier, inflammation, TH2 cytokine response, and mitochondrial function. Intake of the 3 most common glycation products in Western diet foods, Nε-(carboxymethyl) lysine, Nε-(1-carboxyethyl) lysin, and Nδ-(5-hydro-5- methyl-4-imidazolone-2-yl)-ornithine (MG-H1), and the accumulation of AGEs in the skin were comparatively investigated in children with FA and in age-matched healthy controls.

RESULTS

Human enterocytes exposed to AGEs showed alteration in gut barrier, AGE receptor expression, reactive oxygen species production, and autophagy, with increased transepithelial passage of food antigens. Small intestine organ cultures exposed to AGEs showed an increase of CD25+ cells and proliferating crypt enterocytes. PBMCs exposed to AGEs showed alteration in proliferation rate, AGE receptor activation, release of inflammatory and TH2 cytokines, and mitochondrial metabolism. Significant higher dietary AGE intake and skin accumulation were observed children with FA (n = 42) compared with age-matched healthy controls (n = 66).

CONCLUSIONS

These data, supporting a potential role for dietary AGEs in facilitating the occurrence of FA, suggest the importance of limiting exposure to AGEs children as a potential preventive strategy against this common condition.

Age-, sex- and proximal-distal-resolved multi-omics identifies regulators of intestinal aging in non-human primates

The incidence of intestinal diseases increases with age, yet the mechanisms governing gut aging and its link to diseases, such as colorectal cancer (CRC), remain elusive. In this study, while considering age, sex and proximal-distal variations, we used a multi-omics approach in non-human primates (Macaca fascicularis) to shed light on the heterogeneity of intestinal aging and identify potential regulators of gut aging. We explored the roles of several regulators, including those from tryptophan metabolism, in intestinal function and lifespan in Caenorhabditis elegans. Suggesting conservation of region specificity, tryptophan metabolism via the kynurenine and serotonin (5-HT) pathways varied between the proximal and distal colon, and, using a mouse colitis model, we observed that distal colitis was more sensitive to 5-HT treatment. Additionally, using proteomics analysis of human CRC samples, we identified links between gut aging and CRC, with high HPX levels predicting poor prognosis in older patients with CRC. Together, this work provides potential targets for preventing gut aging and associated diseases.

Adenosine in Intestinal Epithelial Barrier Function

At the intestinal front, several lines of defense are in place to resist infection and injury, the mucus layer, gut microbiome and strong epithelial junctions, to name a few. Their collaboration creates a resilient barrier. In intestinal disorders, such as inflammatory bowel disease (IBD), barrier function is compromised, which results in rampant inflammation and tissue injury. In response to the destruction, the intestinal epithelium releases adenosine, a small but powerful nucleoside that functions as an alarm signal. Amidst the chaos of inflammation, adenosine aims to restore order. Within the scope of its effects is the ability to regulate intestinal epithelial barrier integrity. This review aims to define the contributions of adenosine to mucus production, microbiome-dependent barrier protection, tight junction dynamics, chloride secretion and acid-base balance to reinforce its importance in the intestinal epithelial barrier.

Intestinal microbiota regulates the gut-thyroid axis: the new dawn of improving Hashimoto thyroiditis

Intestinal microbiota plays an indispensable role in the host's innate immune system, which may be related to the occurrence of many autoimmune diseases. Hashimoto thyroiditis (HT) is one of the most common autoimmune diseases, and there is plenty of evidence indicating that HT may be related to genetics and environmental triggers, but the specific mechanism has not been proven clearly. Significantly, the composition and abundance of intestinal microbiota in patients with HT have an obvious difference. This phenomenon led us to think about whether intestinal microbiota can affect the progress of HT through some mechanisms. By summarizing the potential mechanism of intestinal microflora in regulating Hashimoto thyroiditis, this article explores the possibility of improving HT by regulating intestinal microbiota and summarizes relevant biomarkers as therapeutic targets, which provide new ideas for the clinical diagnosis and treatment of Hashimoto thyroiditis.

Mechanisms and functions of intestinal vascular specialization

The intestinal vasculature has been studied for the last 100 years, and its essential role in absorbing and distributing ingested nutrients is well known. Recently, fascinating new insights into the organization, molecular mechanisms, and functions of intestinal vessels have emerged. These include maintenance of intestinal epithelial cell function, coping with microbiota-induced inflammatory pressure, recruiting gut-specific immune cells, and crosstalk with other organs. Intestinal function is also regulated at the systemic and cellular levels, such that the postprandial hyperemic response can direct up to 30% of systemic blood to gut vessels, while micron-sized endothelial cell fenestrations are necessary for nutrient uptake. In this review, we will highlight past discoveries made about intestinal vasculature in the context of new findings of molecular mechanisms underpinning gut function. Such comprehensive understanding of the system will pave the way to breakthroughs in nutrient uptake optimization, drug delivery efficiency, and treatment of human diseases.

Secretory-IgA binding to intestinal microbiota attenuates inflammatory reactions as the intestinal barrier of preterm infants matures

Previous work has shown that Secretory-IgA (SIgA) binding to the intestinal microbiota is variable and may regulate host inflammatory bowel responses. Nevertheless, the impact of the SIgA functional binding to the microbiota remains largely unknown in preterm infants whose immature epithelial barriers make them particularly susceptible to inflammation. Here, we investigated SIgA binding to intestinal microbiota isolated from stools of preterm infants <33 weeks gestation with various levels of intestinal permeability. We found that SIgA binding to intestinal microbiota attenuates inflammatory reactions in preterm infants. We also observed a significant correlation between SIgA affinity to the microbiota and the infant's intestinal barrier maturation. Still, SIgA affinity was not associated with developing host defenses, such as the production of mucus and inflammatory calprotectin protein, but it depended on the microbiota shifts as the intestinal barrier matures. In conclusion, we reported an association between the SIgA functional binding to the microbiota and the maturity of the preterm infant's intestinal barrier, indicating that the pattern of SIgA coating is altered as the intestinal barrier matures.

Potential Benefits of Egg White Proteins and Their Derived Peptides in the Regulation of the Intestinal Barrier and Gut Microbiota: A Comprehensive Review

Impaired intestinal barrier function can impede the digestion and absorption of nutrients and cause a range of metabolic disorders, which are the main causes of intestinal disease. Evidence suggests that proper dietary protein intake can prevent and alleviate intestinal diseases. Egg white protein (EWP) has received considerable attention, because of its high protein digestibility and rich amino acid composition. Furthermore, bioactive peptides may have an increased repair effect due to their high degradation efficiency in the gut. In this study, we aimed to review the effects of EWP and its bioactive peptides on intestinal structural repair. The potential modulation mechanisms by which EWP and their peptides regulate the gut microbiota and intestinal barrier can be summarized as follows: (1) restoring the structure of the intestinal barrier to its intact form, (2) enhancing the intestinal immune system and alleviating the inflammatory response and oxidative damage, and (3) increasing the relative abundance of beneficial bacteria and metabolites. Further in-depth analysis of the coregulation of multiple signaling pathways by EWP is required, and the combined effects of these multiple mechanisms requires further evaluation in experimental models. Human trials can be considered to understand new directions for development.

Application of Intestinal Barrier Molecules in the Diagnosis of Acute Cellular Rejection After Intestinal Transplantation

Diagnosing acute rejection after intestinal transplantation currently heavily relies on histopathological analysis of graft biopsies. However, the invasive risks associated with ileoscopic examination and the inaccessibility for biopsy after ileostomy closure hinder real-time detection of rejection responses. Molecules comprising the intestinal barrier have been identified as physiological and molecular biomarkers for various bowel conditions and systemic diseases. To investigate the potential of barrier function-related molecules in diagnosing rejection after intestinal transplantation, plasma samples were collected longitudinally from transplant recipients. The samples were categorized into "indeterminate for rejection (IND)" and "acute rejection (AR)" groups based on clinical diagnoses at each time point. The longitudinal association between plasma levels of these barrier function-related molecules and acute rejection was analyzed using the generalized estimating equations (GEE) method. Logistic GEE models revealed that plasma levels of claudin-3, occludin, sIgA, and zonulin were independent variables correlated with the clinical diagnosis of acute rejection. The subsequent prediction model demonstrated moderate ability in discriminating between IND and AR samples, with a sensitivity of 76.0%, specificity of 89.2%, and accuracy of 84.6%. In conclusion, monitoring plasma levels of claudin-3, occludin, sIgA, and zonulin shows great potential in aiding the diagnosis of acute rejection after intestinal transplantation.

Melatonin Alleviates Intestinal Barrier Damaging Effects Induced by Polyethylene Microplastics in Albino Rats

There have been concerns about the potential health risks posed by microplastics (MP). The detection of MP in a variety of food products revealed that humans are ingesting MP. Nevertheless, there is a paucity of data about their impacts, as well as their uptake, on intestinal barrier integrity. This study examined the toxic effects of oral administration of two doses of polyethylene microplastics (PE-MP) (3.75 or 15 mg/kg/day for 5 weeks; mean particle size: 4.0-6.0 µm) on the intestinal barrier integrity in rats. Moreover, the effect of melatonin treatment with MP exposure was also assessed. The PE-MP particle uptake, histopathological changes, Alcian blue staining, Muc2 mRNA, proinflammatory cytokines (IL-1β and TNF-α), and cleaved caspase-3, as well as tight junction proteins (claudin-1, myosin light-chain kinase (MLCK), occludin, and zonula occludens-1 (ZO-1)) were assessed. Oral administration of PE-MP resulted in apparent jejunal histopathological alterations; significantly decreased mucin secretion, occludin, ZO-1, and claudin-1 expression; and significantly upregulated MLCK mRNA, IL-1β concentration, and cleaved caspase-3 expression. Melatonin reversed these altered parameters and improved the PE-MP-induced histopathological and ultrastructure changes. This study highlighted the PE-MP's toxic effect on intestinal barrier integrity and revealed the protective effect of melatonin.

Gut Protective Effect from Newly Isolated Bacteria as Probiotics against Dextran Sulfate Sodium and Carrageenan-Induced Ulcerative Colitis

Gut microbiome dysbiosis might be linked to certain diseases such as inflammatory bowel diseases (IBDs), which are categorized by vigorous inflammation of the gastrointestinal tract. Several studies have shown the favorable anti-inflammatory effect of certain probiotics in IBD therapy. In the present investigation, the possible gut protective effects of commensal bacteria were examined in an IBD model mouse that was cost-effectively induced with low molecular weight dextran sulfate sodium (DSS) and kappa carrageenan. Our conclusions show that certain probiotic supplementation could result in the attenuation of the disease condition in the IBD mouse, suggesting a favorable therapeutic capability for considerably improving symptoms of gut inflammation with an impact on the IBD therapy. However, the molecular mechanisms require further investigation.

Polysaccharides from Passion Fruit Peels: From an Agroindustrial By-Product to a Viable Option for 5-FU-Induced Intestinal Damage

Gastrointestinal mucositis is a serious and dose-limiting toxic side effect of oncologic treatment. Interruption of cancer treatment due to gastrointestinal mucositis leads to a significant decrease in cure rates and consequently to the deterioration of a patient's quality of life. Natural polysaccharides show a variety of beneficial effects, including a gastroprotective effect. Treatment with soluble dietary fiber (SDF) from yellow passion fruit (Passiflora edulis) biomass residues protected the gastric and intestinal mucosa in models of gastrointestinal injury. In this study, we investigated the protective therapeutic effect of SDF on 5-FU-induced mucositis in male and female mice. Oral treatment of the animals with SDF did not prevent weight loss but reduced the disease activity index and preserved normal intestinal function by alleviating diarrhea and altered gastrointestinal transit. SDF preserved the length of the colon and histological damage caused by 5-FU. SDF significantly restored the oxidative stress and inflammation in the intestine and the enlargement and swelling of the spleen induced by 5-FU. In conclusion, SDF may be a promising adjuvant strategy for the prevention and treatment of intestinal mucositis induced by 5-FU.

Gut Protective Effect from D-Methionine or Butyric Acid against DSS and Carrageenan-Induced Ulcerative Colitis

Microbiome dysbiosis resulting in altered metabolite profiles may be associated with certain diseases, including inflammatory bowel diseases (IBD), which are characterized by active intestinal inflammation. Several studies have indicated the beneficial anti-inflammatory effect of metabolites from gut microbiota, such as short-chain fatty acids (SCFAs) and/or D-amino acids in IBD therapy, through orally administered dietary supplements. In the present study, the potential gut protective effects of d-methionine (D-Met) and/or butyric acid (BA) have been investigated in an IBD mouse model. We have also built an IBD mouse model, which was cost-effectively induced with low molecular weight DSS and kappa-carrageenan. Our findings revealed that D-Met and/or BA supplementation resulted in the attenuation of the disease condition as well as the suppression of several inflammation-related gene expressions in the IBD mouse model. The data shown here may suggest a promising therapeutic potential for improving symptoms of gut inflammation with an impact on IBD therapy. However, molecular metabolisms need to be further explored.

Modified Gegen Qinlian decoction ameliorated ulcerative colitis by attenuating inflammation and oxidative stress and enhancing intestinal barrier function in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Gegen Qinlian decoction (MGQD), which was first documented in Treatise on Febrile Disease, is recognized as a classic prescription to treat ulcerative colitis (UC). However, its protective mechanism against UC remains to be fully elucidated.

AIM OF THE STUDY

To explore the impact and the potential molecular mechanism of MGQD on dextran sodium sulfate (DSS)-induced UC mice and tumor necrosis factor alpha (TNF-α)-induced Caco-2 cell monolayer model of intestinal barrier.

MATERIALS AND METHODS

The chemical components of MGQD and MGQD drug containing serum (MGQD-DS) were characterized by LC-MS/MS. The therapeutic effect of MGQD on DSS-induced UC was evaluated based on body weight, disease activity index (DAI), colon length, colonic histopathological injury, inflammatory cytokines, oxidative stress response and intestinal barrier function. Cell Counting Kit (CCK)-8 assay was applied to detect the effect of MGQD-DS on the viability of Caco-2 cells. Additionally, TNF-α-induced Caco-2 cell monolayer model of intestinal barrier was established in vitro. The Caco-2 cell monolayers were administered blank serum or MGQD-DS to observe the effects of MGQD-DS on transepithelial electrical resistance (TEER), permeability of fluorescein isothiocyanate (FITC)-dextran, inflammatory cytokines, oxidative stress indicators and intestinal epithelial barrier (IEB).

RESULTS

MGQD significantly improved symptoms and pathological damage in UC mice by downregulating the expression of interleukin (IL)-1β and malondialdehyde (MDA), attenuating the loss of goblet cells and the destruction of intestinal epithelial ultrastructure, and upregulating the expression of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), zonula occludens-1 (ZO-1), Occludin, Claudin-1 and E-cadherin. In vitro, MGQD-DS significantly reduced the flux of FITC-dextran, increased the TEER, inhibited the expression of IL-21, IL-17A and MDA, and promoted the expression of IL-4, IL-10, transforming growth factor-β (TGF-β), SOD, CAT, GSH, Occludin and E-cadherin in TNF-α-induced Caco-2 cell monolayer model of intestinal barrier.

CONCLUSION

MGQD can ameliorate DSS-induced UC mice and TNF-α-induced Caco-2 cell monolayer model of intestinal barrier, and the protective effect is related to its inhibition of inflammation, alleviation of oxidative stress, and repair of intestinal barrier damage.

Contribution of Blood Vessel Activation, Remodeling and Barrier Function to Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) consist of a group of chronic inflammatory disorders with a complex etiology, which represent a clinical challenge due to their often therapy-refractory nature. In IBD, inflammation of the intestinal mucosa is characterized by strong and sustained leukocyte infiltration, resulting in the loss of epithelial barrier function and subsequent tissue destruction. This is accompanied by the activation and the massive remodeling of mucosal micro-vessels. The role of the gut vasculature in the induction and perpetuation of mucosal inflammation is receiving increasing recognition. While the vascular barrier is considered to offer protection against bacterial translocation and sepsis after the breakdown of the epithelial barrier, endothelium activation and angiogenesis are thought to promote inflammation. The present review examines the respective pathological contributions of the different phenotypical changes observed in the microvascular endothelium during IBD, and provides an overview of potential vessel-specific targeted therapy options for the treatment of IBD.

Intestinal epithelial barrier integrity investigated by label-free techniques in ulcerative colitis patients

The intestinal epithelial barrier, among other compartments such as the mucosal immune system, contributes to the maintenance of intestinal homeostasis. Therefore, any disturbance within the epithelial layer could lead to intestinal permeability and promote mucosal inflammation. Considering that disintegration of the intestinal epithelial barrier is a key element in the etiology of ulcerative colitis, further assessment of barrier integrity could contribute to a better understanding of the role of epithelial barrier defects in ulcerative colitis (UC), one major form of chronic inflammatory bowel disease. Herein, we employ fast, non-destructive, and label-free non-linear methods, namely coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG), two-photon excited fluorescence (TPEF), and two-photon fluorescence lifetime imaging (2P-FLIM), to assess the morpho-chemical contributions leading to the dysfunction of the epithelial barrier. For the first time, the formation of epithelial barrier gaps was directly visualized, without sophisticated data analysis procedures, by the 3D analysis of the colonic mucosa from severely inflamed UC patients. The results were compared with histopathological and immunofluorescence images and validated using transmission electron microscopy (TEM) to indicate structural alterations of the apical junction complex as the underlying cause for the formation of the epithelial barrier gaps. Our findings suggest the potential advantage of non-linear multimodal imaging is to give precise, detailed, and direct visualization of the epithelial barrier in the gastrointestinal tract, which can be combined with a fiber probe for future endomicroscopy measurements during real-time in vivo imaging.

Association of GILZ with MUC2, TLR2, and TLR4 in Inflammatory Bowel Disease

Ulcerative colitis (UC) and Crohn's Disease (CD) are chronic relapsing inflammatory diseases that are caused by genetic, environmental, and immune factors. Treatment strategies are currently based on symptomatic control by immunosuppression. The glucocorticoid-induced leucine zipper (GILZ), a mediator of several effects of glucocorticoids, was recently found to be secreted by goblet cells and play a role in inflammatory bowel disease (IBD). This study investigates which genes GILZ is associated with in its role in intestinal barrier functions. We examined datasets from the Gene Expression Omnibus (GEO) and ArrayExpress profiles of the gut of healthy subjects (HSs), as well as UC and CD patients. The human colonic epithelial HT29 cell line was used for in vitro validation experiments. GILZ was significantly correlated with MUC2, TLR2, and TLR4. In particular, an inverse correlation was found between the GILZ and MUC2 in HS and patients with IBD, mostly in those with an active disease. Further, direct pairwise correlations for GILZ/TLR2 and GILZ/TLR4 were found in HSs and UC patients, but not in CD patients. Overall, our results reveal the crosstalk at the transcription level between the GILZ, MUC2, and TLRs in the mucosal barrier through common pathways, and they open up new perspectives in terms of mucosal healing in IBD patients.

Orally administered MOTS-c analogue ameliorates dextran sulfate sodium-induced colitis by inhibiting inflammation and apoptosis

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory disorder of the gastrointestinal tract (GI). Currently, the treatment options for IBD are limited. It has been reported that a novel bioactive mitochondrial-derived peptide (MOTS-c) encoded in the mitochondrial 12S rRNA, suppresses inflammatory response by enhancing the phagocytosis of macrophages. The aim of this study was to investigate the protective effects of MOTS-c against dextran sulfate sodium (DSS)-induced colitis. The results showed that intraperitoneal (i.p.) administration of MOTS-c significantly ameliorated the symptoms of DSS-induced experimental colitis, such as body weight loss, colon length shortening, diarrhea, and histological damage. MOTS-c down-regulated the expression of pro-inflammatory cytokines, decreased the plasma levels of myeloperoxidase, and inhibited the activation of macrophages and recruitment of neutrophils. Moreover, treatment with MOTS-c exhibited anti-apoptotic effects and significantly suppressed the phosphorylation of AMPKα1/2, ERK, and JNK. Notably, oral administration of MOTS-c did not result in any significant improvements. Screening of cell penetrating peptides was performed, (PRR)5 was linked to the C-terminus of MOTS-c through a linker to synthesize a new molecule (termed MP) with better penetration into the colon epithelium. In vitro experiments revealed the longer half-life of MP than MOTS-c, and in vivo experiments showed that oral administration of MP significantly ameliorated DSS-induced colitis. CONCLUSION: The present results demonstrate a protective role of MOTS-c in experimental IBD.

Gut microbiome in type 1 diabetes: the immunological perspective

INTRODUCTION

Type 1 diabetes (T1D) is a prevalent, and yet uncurable, autoimmune disease targeting insulin-producing pancreatic β-cells. Despite a known genetic component in T1D onset, genetics alone cannot explain the alarming worldwide rise in T1D incidence, which is attributed to a growing impact of environmental factors, including perturbations of the gut microbiome.

AREAS COVERED

Intestinal commensal bacteria plays a crucial role in host physiology in health and disease by regulating endocrine and immune functions. An aberrant gut microbiome structure and metabolic function have been documented prior and during T1D onset. In this review, we summarize and discuss the current studies depicting the taxonomic profile and role of the gut microbial communities in murine models of T1D, diabetic patients and human interventional trials.

EXPERT OPINION

Compelling evidence have shown that the intestinal microbiota is instrumental in driving differentiation and functions of immune cells. Therefore, any alterations in the intestinal microbiome composition or microbial metabolite production, particularly early in life, may impact disease susceptibility and amplify inflammatory responses and hence accelerate the course of T1D pathogenesis.

IL-1β blockade prevents cell death and mucosal damage of the small intestine in a model of sterile inflammation

The intestinal mucosa is covered by a layer of epithelial cells that is constantly challenged by commensal, opportunistic, and pathogenic microorganisms, their components, and harmful compounds. Any inflammatory response to these materials must be tightly controlled to limit tissue damage and restore the integrity of the mucosal barrier. We have shown previously that production of IL-1β via activation of the inflammasome can lead to mucosal damage in the small intestinal pathology that occurs after intragastric administration of a gluten derived peptide, p31-43. Here we show that specific inhibition of caspase-1 or NLRP3 abolishes the damage induced by p31-43, and that antibody-mediated blocking of IL-1β inhibits the both the histological changes and the induction of apoptosis and caspase-3 activation driven by p31-43. Understanding the role of IL-1β in sterile inflammation may help to understand chronic inflammatory pathological processes, and design new intervention strategies.

Understanding and harnessing triple-negative breast cancer-related microbiota in oncology

Bacterial inhabitants of the body have the potential to play a role in various stages of cancer initiation, progression, and treatment. These bacteria may be distal to the primary tumour, such as gut microbiota, or local to the tissue, before or after tumour growth. Breast cancer is well studied in this context. Amongst breast cancer types, Triple Negative Breast Cancer (TNBC) is more aggressive, has fewer treatment options than receptor-positive breast cancers, has an overall worse prognosis and higher rates of reoccurrence. Thus, an in-depth understanding of the bacterial influence on TNBC progression and treatment is of high value. In this regard, the Gut Microbiota (GM) can be involved in various stages of tumour progression. It may suppress or promote carcinogenesis through the release of carcinogenic metabolites, sustenance of proinflammatory environments and/or the promotion of epigenetic changes in our genome. It can also mediate metastasis and reoccurrence through interactions with the immune system and has been recently shown to influence chemo-, radio-, and immune-therapies. Furthermore, bacteria have also been found to reside in normal and malignant breast tissue. Several studies have now described the breast and breast tumour microbiome, with the tumour microbiota of TNBC having the least taxonomic diversity among all breast cancer types. Here, specific conditions of the tumour microenvironment (TME) - low O2, leaky vasculature and immune suppression - are supportive of tumour selective bacterial growth. This innate bacterial ability could enable their use as delivery agents for various therapeutics or as diagnostics. This review aims to examine the current knowledge on bacterial relevance to TNBC and potential uses while examining some of the remaining unanswered questions regarding mechanisms underpinning observed effects.

Raising the Alarm: Environmental Factors in the Onset and Maintenance of Chronic (Low-Grade) Inflammation in the Gastrointestinal Tract

Chronic inflammatory disease of the gastrointestinal (GI) tract is defined by several pathophysiological characteristics, such as dysbiosis of the microbiota, epithelial barrier hyperpermeability, systemic dissemination of endotoxins and chronic inflammation. In addition to well-reported environmental factors in non-communicable disease, such as smoking, diet, and exercise, humans are frequently exposed to myriads more environmental factors, from pesticides to food additives. Such factors are ubiquitous across both our diet and indoor/outdoor environments. A major route of human exposure to these factors is ingestion, which frequently occurs due to their intentional addition (intentional food additives) and/or unintentional contamination (unintentional food contaminants) of food products-often linked to environmental pollution. Understanding how this persistent, diverse exposure impacts GI health is of paramount importance, as deterioration of the GI barrier is proposed to be the first step towards systemic inflammation and chronic disease. Therefore, we aim to evaluate the impact of ingestion of environmental factors on inflammatory processes in the GI tract. In this review, we highlight human exposure to intentional food additives (e.g. emulsifiers, bulking agents) and unintentional food contaminants (e.g. persistent organic pollutants, pesticides, microplastics), then present evidence for their association with chronic disease, modification of the GI microbiota, increased permeability of the GI barrier, systemic dissemination of endotoxins, local (and distal) pro-inflammatory signalling, and induction of oxidative stress and/or endoplasmic reticulum stress. We also propose a link to NLRP3-inflammasome activation. These findings highlight the contribution of common environmental factors towards deterioration of GI health and the induction of pathophysiology associated with onset and maintenance of chronic inflammation in the GI tract.

Common bacterial metabolite indole directly activates nociceptive neuron through transient receptor potential ankyrin 1 channel

ABSTRACT

Nociceptors are known to directly recognize bacterial cell wall components or secreted toxins, thereby leading to pain induced by bacterial infection. However, direct activation of nociceptors by bacterial metabolites remains unclear although bacteria produce numerous metabolites related to health and disease. In this study, we investigated whether and how a common bacterial metabolite, indole, which is produced by normal microflora of the gastrointestinal tract and oral cavity, can directly activate nociceptive sensory neurons. We found that indole elicits calcium response and evokes inward currents in subsets of dorsal root ganglia (DRG) neurons. Intraplantar (i.pl.) injection of indole produced nocifensive behaviors in adult mice, which were enhanced in complete Freund's adjuvant-induced chronic inflammatory condition. Indole increased calcitonin gene-related peptide release in DRG neurons, and i.pl. injection of indole increased hind paw thickness, suggesting its role in generation of neurogenic inflammation. These in vitro and in vivo indole-induced responses were pharmacologically blocked by transient receptor potential ankyrin 1 (TRPA1) antagonist, HC-030031, and significantly abolished in TRPA1 knockout (KO) mice, indicating that indole targets TRPA1 for its action in DRG neurons. Nocifensive licking behavior induced by the injection of live Escherichia coli was significantly decreased in tryptophanase mutant (TnaA KO) E. coli- injected mice that lack indole production, further supporting the idea that bacteria-derived indole can induce pain during infection. Identifying the mechanism of action of indole through TRPA1 provides insights into bacteria-neuron interactions and the role of bacterial metabolites in pain signaling, especially in inflammation-accompanied bacterial infection.

Enhanced oxidative phosphorylation of IgG plasma cells can contribute to hypoxia in the mucosa of active ulcerative colitis

Mucosal hypoxia is detected in the mucosa of ulcerative colitis (UC), however the mechanism and the cause of hypoxia is not fully understood, while a dense infiltration of plasma cells is observed in the inflamed mucosa of UC. When differentiating from a B cell to a plasma cell, the energy metabolism dramatically shifts from glycolysis to oxidative phosphorylation, which results in a large amount of oxygen consumption of the plasma cell. We hypothesized that the plasma cell infiltration into the inflamed mucosa contributes to the mucosal hypoxia in UC in part. We examined the association between mucosal hypoxia and plasma cell infiltration in UC. More IgG plasma cells (but not IgA plasma cells) were distributed, and the nuclear and cell sizes were enlarged in hypoxic mucosa compared to normoxic mucosa in UC. Oxidative phosphorylation signature genes of these IgG plasma cells were markedly upregulated compared to those of other lymphoid cells infiltrating the lamina propria of inflamed mucosa of UC. Enlarged IgG plasma cells, which increase in number in the inflamed mucosa of UC, can be related to the hypoxic state of the inflamed mucosa of UC.

Cigarette Smoke Extract Disturbs Mitochondria-Regulated Airway Epithelial Cell Responses to Pneumococci

Mitochondrial functionality is crucial for the execution of physiologic functions of metabolically active cells in the respiratory tract including airway epithelial cells (AECs). Cigarette smoke is known to impair mitochondrial function in AECs. However, the potential contribution of mitochondrial dysfunction in AECs to airway infection and airway epithelial barrier dysfunction is unknown. In this study, we used an in vitro model based on AECs exposed to cigarette smoke extract (CSE) followed by an infection with Streptococcus pneumoniae (Sp). The levels of oxidative stress as an indicator of mitochondrial stress were quantified upon CSE and Sp treatment. In addition, expression of proteins associated with mitophagy, mitochondrial content, and biogenesis as well as mitochondrial fission and fusion was quantified. Transcriptional AEC profiling was performed to identify the potential changes in innate immune pathways and correlate them with indices of mitochondrial function. We observed that CSE exposure substantially altered mitochondrial function in AECs by suppressing mitochondrial complex protein levels, reducing mitochondrial membrane potential and increasing mitochondrial stress and mitophagy. Moreover, CSE-induced mitochondrial dysfunction correlated with reduced enrichment of genes involved in apical junctions and innate immune responses to Sp, particularly type I interferon responses. Together, our results demonstrated that CSE-induced mitochondrial dysfunction may contribute to impaired innate immune responses to Sp.

Food as Treatment of Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), namely, Crohn's disease (CD) and ulcerative colitis (UC), are lifelong and incurable chronic inflammatory diseases affecting 6.8 million people worldwide. By 2030, the prevalence of IBD is estimated to reach 1% of the population in Western countries, and thus there is an urgent need to develop effective therapies to reduce the burden of this disease. Microbiome dysbiosis is at the heart of the IBD pathophysiology, and current research and development efforts for IBD treatments have been focused on gut microbiome regulation. Diet can shape the intestinal microbiome. Diet is also preferred over medication, is safe, and has been proven to be an effective strategy for the management of IBD. Therefore, although often overlooked, dietary interventions targeting the microbiome represent ideal treatments for IBD. Here, I summarize the latest research on diet as a treatment for IBD from infancy to adulthood, compile evidence of the mechanisms of action behind diet as treatment, and, lastly, provide insights into future research focusing on culturally tailored diets for ethnic minority groups with increased incidence of IBD yet underrepresented in nutrition research.

Morais L. Convergent pathways of the gut microbiota-brain axis and neurodegenerative disorders

Recent research has been uncovering the role of the gut microbiota for brain health and disease. These studies highlight the role of gut microbiota on regulating brain function and behavior through immune, metabolic, and neuronal pathways. In this review we provide an overview of the gut microbiota axis pathways to lay the groundwork for upcoming sessions on the links between the gut microbiota and neurogenerative disorders. We also discuss how the gut microbiota may act as an intermediate factor between the host and the environment to mediate disease onset and neuropathology. Based on the current literature, we further examine the potential for different microbiota-based therapeutic strategies to prevent, to modify, or to halt the progress of neurodegeneration.

Effects of gut microbiota-derived extracellular vesicles on obesity and diabetes and their potential modulation through diet

Obesity and diabetes incidence rates are increasing dramatically, reaching pandemic proportions. Therefore, there is an urgent need to unravel the mechanisms underlying their pathophysiology. Of particular interest is the close interconnection between gut microbiota dysbiosis and obesity and diabetes progression. Hence, microbiota manipulation through diet has been postulated as a promising therapeutic target. In this regard, secretion of gut microbiota-derived extracellular vesicles is gaining special attention, standing out as key factors that could mediate gut microbiota-host communication. Extracellular vesicles (EVs) derived from gut microbiota and probiotic bacteria allow to encapsulate a wide range of bioactive molecules (such as/or including proteins and nucleic acids) that could travel short and long distances to modulate important biological functions with the overall impact on the host health. EV-derived from specific bacteria induce differential physiological responses. For example, a high-fat diet-induced increase of the proteobacterium Pseudomonas panacis-derived EV is closely associated with the progression of metabolic dysfunction in mice. In contrast, Akkermansia muciniphila EV are linked with the alleviation of high-fat diet-induced obesity and diabetes in mice. Here, we review the newest pieces of evidence concerning the potential role of gut microbiota and probiotic-derived EV on obesity and diabetes onset, progression, and management, through the modulation of inflammation, metabolism, and gut permeability. In addition, we discuss the role of certain dietary patterns on gut microbiota-derived EV profile and the clinical implication that dietary habits could have on metabolic diseases progression through the shaping of gut microbiota-derived EV.

Gut Microbiota Interact With the Brain Through Systemic Chronic Inflammation: Implications on Neuroinflammation, Neurodegeneration, and Aging

It has been noticed in recent years that the unfavorable effects of the gut microbiota could exhaust host vigor and life, yet knowledge and theory are just beginning to be established. Increasing documentation suggests that the microbiota-gut-brain axis not only impacts brain cognition and psychiatric symptoms but also precipitates neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). How the blood-brain barrier (BBB), a machinery protecting the central nervous system (CNS) from the systemic circulation, allows the risky factors derived from the gut to be translocated into the brain seems paradoxical. For the unique anatomical, histological, and immunological properties underpinning its permeable dynamics, the BBB has been regarded as a biomarker associated with neural pathogenesis. The BBB permeability of mice and rats caused by GM dysbiosis raises the question of how the GM and its metabolites change BBB permeability and causes the brain pathophysiology of neuroinflammation and neurodegeneration (NF&ND) and brain aging, a pivotal multidisciplinary field tightly associated with immune and chronic systemic inflammation. If not all, gut microbiota-induced systemic chronic inflammation (GM-SCI) mainly refers to excessive gut inflammation caused by gut mucosal immunity dysregulation, which is often influenced by dietary components and age, is produced at the interface of the intestinal barrier (IB) or exacerbated after IB disruption, initiates various common chronic diseases along its dispersal routes, and eventually impairs BBB integrity to cause NF&ND and brain aging. To illustrate the immune roles of the BBB in pathophysiology affected by inflammatory or "leaky" IB resulting from GM and their metabolites, we reviewed the selected publications, including the role of the BBB as the immune barrier, systemic chronic inflammation and inflammation influences on BBB permeability, NF&ND, and brain aging. To add depth to the bridging role of systemic chronic inflammation, a plausible mechanism indispensable for BBB corruption was highlighted; namely, BBB maintenance cues are affected by inflammatory cytokines, which may help to understand how GM and its metabolites play a major role in NF&ND and aging.

Lactobacillus casei Strain Shirota Ameliorates Dextran Sulfate Sodium-Induced Colitis in Mice by Increasing Taurine-Conjugated Bile Acids and Inhibiting NF-κB Signaling via Stabilization of IκBα

Inflammatory bowel disease (IBD) is a chronic progressive intestinal inflammatory disease, characterized by an altered gut microbiota composition and accompanying alterations in circulatory bile acids. Increasing evidence supports the beneficial effect of probiotics intake on health. Introduction of probiotics to the intestines can modulate gut microbiota composition and in turn regulate the host immune system and modify the inflammatory response. Probiotics can also improve intestinal barrier function and exhibit a positive impact on host physiological and pathological conditions via gut microbiota-derived metabolites. Previous studies have demonstrated that Lactobacillus casei strain Shirota (LcS) treatment could inhibit clinical manifestation of colitis in dextran sulfate sodium (DSS)-induced mice, however, the underlying mechanisms remain unknown. In this study, we employed the DSS-induced acute colitis mouse model to investigate the anti-inflammatory effects of LcS and related mechanisms. Administration of LcS ameliorated the severity of DSS-induced colitis and enhanced intestinal integrity via induction of mucin-2 and occludin expression in colons. Fecal microbiota analysis showed that LcS increased the relative abundance of beneficial bacterial species in colitic mice, whereas the relative abundance of pathobionts was reduced. Additionally, LcS treatment modulated circulating bile acid profiles in colitic mice. In mice treated with LcS, we identified increased levels of primary taurine-conjugated bile acids, including taurocholic acid (TCA) and taurochenodeoxycholic acid (TCDCA). LcS treatment also increased the levels of secondary taurine-conjugated bile acids, including taurodeoxycholic acid (TDCA) and tauroursodeoxycholic acid (TUDCA). Moreover, LcS treatment exhibited a suppressive effect on the hydroxylated primary bile acids α-muricholic acid (α-MCA) and β-muricholic acid (β-MCA). We further demonstrated that LcS treatment suppressed the expression of pro-inflammatory mediators interferon-gamma (IFN-γ) and nitric oxide (NO), and increased the expression of the anti-inflammatory mediator interleukin-10 (IL-10) in colon tissues, potentially as a result of altered bile acid profiles. Mechanistically, we showed that LcS treatment suppressed the activation of nuclear factor-kappa B (NF-κB) signaling via stabilization of inhibitor of NF-κB alpha (IκBα). Altogether, we have demonstrated the therapeutic effects of LcS in DSS-induced colitis, providing new insights into its effect on bile acid metabolism and the related anti-inflammatory mechanisms. Our findings provide support for the application of LcS in the treatment of IBD.

Surgical Management of Small Bowel Crohn's Disease

Crohn's disease in the small bowel could present itself as an inflammatory stricture, a fibrotic stricture as penetrating disease or a combination of both. It is pertinent to differentiate the disease process as well as its extent to effectively manage the disease. Currently, a combination of medical and surgical therapies forms part of the treatment plan while the debate of which therapy is better continues. In managing the strictures, identification of the disease process through imaging plays a pivotal role as inflammatory strictures respond to anti-tumor necrosis factor (TNF) and biological agents, while fibrotic strictures require endoscopic or surgical intervention. Recent evidence suggests a larger role for surgical excision, particularly in ileocolic disease, while achieving a balance between disease clearance and bowel preservation. Several adaptations to the surgical technique, such as wide mesenteric excision, side to side or Kono-S anastomosis, and long-term metronidazole therapy, are being undertaken even though their absolute benefit is yet to be determined. Penetrating disease requires a broader multidisciplinary approach with a particular focus on nutrition, skincare, and intestinal failure management. The current guidance directs toward early surgical intervention for penetrating disease when feasible. Accurate preoperative imaging, medical management of active diseases, and surgical decision-making based on experience and evidence play a key role in success.

Alternaria alternata Mycotoxins Activate the Aryl Hydrocarbon Receptor and Nrf2-ARE Pathway to Alter the Structure and Immune Response of Colon Epithelial Cells

After ingestion of food commodities, the gastrointestinal tract (GIT) poses the first barrier against xenobiotics and pathogens. Therefore, it is regularly confronted with external stressors potentially affecting the inflammatory response and the epithelial barrier. Alternaria mycotoxins such as alternariol (AOH) and altertoxin II (ATX-II) are frequently occurring food and feed contaminants that are described for their immunomodulatory capacities. Hence, this study aimed at exploring the effect of AOH and ATX-II as single compounds or binary mixtures on the immune response and epithelial homeostasis in noncancerous colon epithelial cells HCEC-1CT. Both toxins suppressed mRNA levels of proinflammatory mediators interleukin-8 (IL-8), tumor necrosis factor α (TNF-α), and secretion of IL-8, as well as mRNA levels of the matrix metallopeptidase 2 (MMP-2). Binary combinations of AOH and ATX-II reduced the response of the single toxins. Additionally, AOH and ATX-II modified immunolocalization of transmembrane proteins such as integrin β1, zona occludens 1 (ZO-1), claudin 4 (Cldn 4), and occludin (Ocln), which support colonic tissue homeostasis and intestinal barrier function. Moreover, the cellular distribution of ZO-1 was affected by ATX-II. Mechanistically, these effects could be traced back to the involvement of several transcription factors. AOH activated the nuclear translocation of the aryl hydrocarbon receptor (AhR) and the nuclear factor erythroid 2-related factor 2 (Nrf2), governing cell metabolic competence and structural integrity. This was accompanied by altered distribution of the NF-κB p65 protein, an important regulator of inflammatory response. ATX-II also induced AhR and Nrf2 translocation, albeit failing to substantiate the effect of AOH on the colonic epithelium. Hence, both toxins coherently repress the intestinal immune response on the cytokine transcriptional and protein levels. Furthermore, both mycotoxins affected the colonic epithelial integrity by altering the cell architecture.

Role of omega-3 polyunsaturated fatty acids, citrus pectin, and milk-derived exosomes on intestinal barrier integrity and immunity in animals

The gastrointestinal tract of livestock and poultry is prone to challenge by feedborne antigens, pathogens, and other stress factors in the farm environment. Excessive physiological inflammation and oxidative stress that arises firstly disrupts the intestinal epithelial barrier followed by other components of the gastrointestinal tract. In the present review, the interrelationship between intestinal barrier inflammation and oxidative stress that contributes to the pathogenesis of inflammatory bowel disease was described. Further, the role of naturally existing immunomodulatory nutrients such as the omega-3 polyunsaturated fatty acids, citrus pectin, and milk-derived exosomes in preventing intestinal barrier inflammation was discussed. Based on the existing evidence, the possible molecular mechanism of these bioactive nutrients in the intestinal barrier was outlined for application in animal diets.