Explore the vast range of titles available.

The interaction between host and external environment mainly occurs in the gastrointestinal tract, where the mucosal barrier has a critical role in many physiologic functions ranging from digestion, absorption, and metabolism. This barrier allows the passage and absorption of nutrients, but at the same time, it must regulate the contact between luminal antigens and the immune system, confining undesirable products to the lumen. Diet is an important regulator of the mucosal barrier, and the cross-talk among dietary factors, the immune system, and microbiota is crucial for the modulation of intestinal permeability and for the maintenance of gastrointestinal tract (GI) homeostasis. In the present review, we will discuss the role of a number of dietary nutrients that have been proposed as regulators of inflammation and epithelial barrier function. We will also consider the metabolic function of the microbiota, which is capable of elaborating the diverse nutrients and synthesizing products of great interest. Better knowledge of the influence of dietary nutrients on inflammation and barrier function can be important for the future development of new therapeutic approaches for patients with mucosal barrier dysfunction, a critical factor in the pathogenesis of many GI and non-GI diseases.

Current asthma therapies reduce inflammation and symptoms but there are concerns regarding adverse effects and the long-term treatment burden. The anti-asthmatic potential of Dictamnine (Dic) has not been investigated. The therapeutic effect of Dic on airway inflammation and remodeling was investigated by targeting the tumor growth factor (TGF)-β/Smad2/3 pathway. A murine model of ovalbumin (OVA)-induced asthma was used to evaluate the effects of orally-administered Dic on airway hyperresponsiveness, inflammatory cytokines in bronchoalveolar lavage fluid (BALF), OVA-specific IgE in the serum, and histopathological changes. The expression of TGF-β/Smad2/3 and epithelial markers was assessed. Human bronchial epithelial cells were used in vitro to examine the effects of Dic on TGF-β-induced Smad2/3 phosphorylation. Network pharmacology was conducted to predict Dic-associated targets and pathways. Dic substantially reduced the levels of Th2 cytokines, mucin 5AC in BALF, and OVA-specific IgE in the serum. Histology indicated reduced inflammatory cell infiltration, bronchial wall thickening, and peribronchial fibrosis in Dic-treated mice. Dic downregulated TGF-β and p-Smad2/3 expression and upregulated ZO-1 expression in the lung tissue. Dic downregulated TGF-β-induced Smad2/3 phosphorylation in bronchial epithelial cells. Network pharmacology indicated enrichment of Dic-related genes in the TGF-β pathway. Dic exhibited anti-asthmatic effects and is a potential therapeutic candidate.

Biophysical cues from the cell microenvironment are detected by mechanosensitive components at the cell surface. Such machineries convert physical information into biochemical signaling cascades within cells, subsequently leading to various cellular responses in a stimulus-dependent manner. At the surface of extracellular environment and cell cytoplasm exist several ion channel families that are activated by mechanical signals to direct intracellular events. One of such channel is formed by transient receptor potential cation channel subfamily V member, TRPV4 that is known to act as a mechanosensor in wide variaty of tissues and control ion-influx in a spatio-temporal way. Here we report that TRPV4 is prominently expressed in the stem/progenitor cell populations of the mammary epithelium and seems important for the lineage-specific differentiation, consequently affecting mechanical features of the mature mammary epithelium. This was evident by the lack of several markers for mature myoepithelial and luminal epithelial cells in TRPV4-depleted cell lines. Interestingly, TRPV4 expression is controlled in a tension-dependent manner and it also impacts differentation process dependently on the stiffness of the microenvironment. Furthermore, such cells in a 3D compartment were disabled to maintain normal mammosphere structures and displayed abnormal lumen formation, size of the structures and disrupted cellular junctions. Mechanosensitive TRPV4 channel therefore act as critical player in the homeostasis of normal mammary epithelium through sensing the physical environment and guiding accordingly differentiation and structural organization of the bilayered mammary epithelium.

The human gut microbiome is a stratified and resilient ecosystem co-inhabited by a diverse and dynamic pool of microorganisms. Microbial selection, establishment, and colonization are modulated through a complex molecular network of host-microbial interactions. These molecular bioprocesses ensure the taxonomic composition of the mature human gut microbiome. The human gut microbiome plays a vital role in host health; otherwise, any microbial dysbiosis could predispose to the onset of physiological and metabolic disorder/s. Focussed research are being carried out to identify key molecular agents defining gut homeostasis. These molecules hold the potential to develop effective therapeutic solutions for microbial dysbiosis-associated human disorders. Of these, Hypoxia-inducible factor-1α (HIF-1α) is a central player in host-microbial crosstalk to maintain gut homeostasis. Human gut microbial metabolites regulate its cellular stability, which in turn regulates various cellular processes required for the stable gut microbiome. In the present review, an effort has been made to summarize the key role of HIF-1α to maintain gut homeostasis.Highlights- Explain the molecular process of host microbial molecular interactions.- Establish the explicit role of HIF-1α in intestinal epithelial integrity and gut health.- Regulation of HIF-1α by human gut commensals and vice a versa.- Regulation of the host immune response for survival and colonization of human gut commensal.

(1) Exposure of intestinal epithelial cells to heat and hypoxia causes a (heat) stress response, resulting in the breakdown of epithelial integrity. There are indications that several categories of nutritional components have beneficial effects on maintaining the intestinal epithelial integrity under stress conditions. This study evaluated the effect of nine nutritional components, including non-digestible oligosaccharides (galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), chitosan oligosaccharides (COS)), antioxidants (α-lipoic acid (ALA), resveratrol (RES)), amino acids (l-glutamine (Glu), l-arginine (Arg)) and polyunsaturated fatty acids (PUFAs) (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)), on heat/hypoxia-induced epithelial injury. (2) Two human colonic cell lines, Caco-2 and HT-29, were co-cultured and pre-treated with the nutritional components for 48 h. After pre-treatment, the cells were exposed to heat/hypoxia (42 °C, 5% O2) for 2 h. Epithelial integrity was evaluated by measuring trans-epithelial electrical resistance (TEER), paracellular Lucifer Yellow (LY) permeability, and tight junction (TJ) protein expression. Heat stress and oxidative stress levels were evaluated by determining heat-shock protein-70 (HSP-70) expression and the concentration of the lipid peroxidation product malondialdehyde (MDA). (3) GOS, FOS, COS, ALA, RES, Arg, and EPA presented protective effects on epithelial damage in heat/hypoxia-exposed Caco-2/HT-29 cells by preventing the decrease in TEER, the increase in LY permeability, and/or decrease in TJ proteins zonula occludens-1 (ZO-1) and claudin-3 expression. COS, RES, and EPA demonstrated anti-oxidative stress effects by suppressing the heat/hypoxia-induced MDA production, while Arg further elevated the heat/hypoxia-induced increase in HSP-70 expression. (4) This study indicates that various nutritional components have the potential to counteract heat/hypoxia-induced intestinal injury and might be interesting candidates for future in vivo studies and clinical trials in gastrointestinal disorders related to heat stress and hypoxia.

Oral lichen planus (OLP) is a chronic immune-mediated inflammatory disorder of the oral mucosa associated with oxidative stress, epithelial degeneration, and persistent T-cell-driven inflammation. Despite numerous therapeutic approaches, disease control and mucosal healing remain challenging. This review aims to summarize current evidence on the biological functions of vitamin C (VitC) relevant to OLP pathogenesis and to evaluate its potential as an adjunctive therapeutic agent. A comprehensive literature review was performed to identify studies exploring the molecular mechanisms of VitC in oxidative stress modulation, epithelial integrity, and immune regulation, as well as clinical and experimental data assessing its therapeutic outcomes in OLP. VitC has various effects relevant to OLP, including scavenging of reactive oxygen species, stabilization of epithelial structures, regulation of apoptosis, and modulation of cytokine expression. Preliminary studies indicate beneficial effects on oxidative balance, inflammation, and tissue repair; however, the evidence is still limited and varies among different study designs and formulations. VitC represents a biologically plausible and safe adjunct in OLP management, acting at multiple pathobiological levels. Further well-designed clinical trials are needed to establish optimal dosing, delivery strategies, and long-term outcomes.

The intestinal mucosa contributes to frontline gut defenses by forming a barrier (physical and biochemical) and preventing the entry of pathogenic microbes. One innate role of the human colonic epithelium is to secrete cathelicidin, a peptide with broad antimicrobial and immunomodulatory functions. In this study, the effect of cathelicidin in the maintenance of epithelial integrity, Toll-like receptor recognition, bacterial invasion and initiation of inflammatory response against Salmonella typhimurium is investigated in cultured human colonic epithelium. We found exogenous human cathelicidin restores the epithelial integrity in S. typhimurium-infected colonic epithelial (T84) cells by mostly post-translational effects associated with reorganization of zonula occludens (ZO)-1 tight junction proteins. Endogenous cathelicidin prevents S. typhimurium internalization as shown in colonic epithelial cells genetically deficient in the only human cathelicidin, LL-37 (shLL-37). Moreover, supplementation of shLL-37 cells with synthetic LL-37 reduces the grade of S. typhimurium internalization in a dose-dependent manner. Mechanistically, shLL-37 cells have lower gene expression of TLR4 and pro-inflammatory cytokine IL-1β in response to S. typhimurium. Thus, human cathelicidin aids in the early colonic epithelial defenses against enteric S. typhimurium by preventing bacterial invasion and maintaining epithelial barrier integrity, likely to occur due to the production of sensing TLR4 and pro-inflammatory cytokines.

Due to the fact that chronic inflammation as well as tumorigenesis in the gut is crucially impacted by the fate of intestinal epithelial cells, our article provides a comprehensive overview of the composition, function, regulation and homeostasis of the gut epithelium. In particular, we focus on those aspects which were found to be altered in the context of inflammatory bowel diseases or colorectal cancer and also discuss potential molecular targets for a disease-specific therapeutic intervention.

Inflammatory bowel disease (IBD) is a complex disease that is characterized by tight junction loss and dysregulation of immune homeostasis. The repair of intestinal integrity and immune function in IBD remains a clinical challenge. Sphingosine-1-phosphate (S1P) has been reported to alleviate radiation-induced salivary gland damage by maintaining epithelial integrity. However, its potential to restore function during IBD has not yet been investigated. Dextran sulfate sodium (DSS) was added to the drinking water of C57BL/6 mice for 5 days to induce colitis. Subsequently, S1P and vehicle were injected intravenously on days 1, 3, and 5. Body weight, the disease activity index (DAI), and the histological activity index (HAI) were recorded. The level of apoptosis and expression of tight junction proteins among the groups were compared. We explored the underlying mechanisms of S1P using RNA sequencing. S1P alleviated DSS-induced colitis by suppressing inflammatory cell infiltration, reducing ulcers, and maintaining intestinal epithelial junction integrity by increasing E-cadherin and occludin expression. S1P decreased apoptosis, suppressed M1 macrophage polarization and promoted M2 macrophage polarizaion. RNA sequencing revealed upregulation of the phosphatidylinositol 3-kinase/protein kinase B (PI3K-Akt) and chemokine signaling pathways in the DSS group compared with those in the S1P group. S1P alleviated colitis by maintaing the intestinal epithelial integrity, promoting the polarization of M2 macrophage, suppressing chemokines, and regulating PI3K/Akt signaling pathway.

Increased cell shedding with gap formation and local barrier dysfunction can be identified endomicroscopically in the terminal ileum of patients with inflammatory bowel disease. We aim to evaluate whether these changes are also present in the duodenum of patients with inflammatory bowel disease.MethodsFifteen patients with Crohn's disease (CD), 10 patients with ulcerative colitis (UC), and 10 controls underwent fluorescein-aided confocal laser endomicroscopy (CLE). CLE was performed on macroscopically normal antral and duodenal (D1, D2, D3, D4) mucosa. Representative CLE images were prospectively analyzed. Images were scored for the number of epithelial gaps, cell shedding, and the degree of fluorescein leakage into the intestinal lumen.ResultsBoth CD and UC patients had significantly more epithelial gaps, epithelial cell shedding, and leakage of fluorescein into the duodenal lumen than controls. The degree of cell shedding and epithelial gap formation was similar in CD and UC patients. In all cases, macroscopic endoscopic appearances of the duodenum were normal, and conventional histological analysis showed a mild nonspecific duodenitis in 7 of 15 patients with CD. Patients with UC had a histologically normal duodenum. Gap formation, cell shedding, and fluorescein leakage was similar in CD with active compared with inactive disease, except for D2 shedding.ConclusionsCLE can detect epithelial damage and barrier loss in the duodenum of CD and UC patients that is not apparent on conventional endoscopy or histology.