miR-200a attenuated oxidative stress, inflammation, and apoptosis in dextran sulfate sodium-induced colitis through activation of Nrf2.

Introduction: Oxidative stress and inflammatory responses are critical factors in ulcerative colitis disease pathogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) modulates oxidative stress and suppresses inflammatory responses, and the protective benefits of Nrf2 activation have been associated with the therapy of ulcerative colitis. MicroRNA-200a (miR-200a) could target Kelch-like ECH-associated protein 1 (Keap1) and activate the Nrf2-regulated antioxidant pathway. Nevertheless, whether miR-200a modulates the Keap1/Nrf2 pathway in dextran sulfate sodium (DSS)-induced colonic damage is unknown. Here, our research intends to examine the impact of miR-200a in the model of DSS-induced colitis. Methods: Prior to DSS intervention, we overexpressed miR-200a in mice for four weeks using an adeno-associated viral (AAV) vector to address this problem. ELISA detected the concentration of inflammation-related cytokines. The genes involved in inflammatory reactions and oxidative stress were identified using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence. Moreover, we applied siRNAs to weakened Nrf2 expression to confirm the hypothesis that miR-200a provided protection via Nrf2. Results: The present study discovered miR-200a down-regulation, excessive inflammatory activation, enterocyte apoptosis, colonic dysfunction, and Keap1/Nrf2 antioxidant pathway inactivation in mouse colitis and NCM460 cells under DSS induction. However, our data demonstrated that miR-200a overexpression represses Keap1 and activates the Nrf2 antioxidant pathway, thereby alleviating these adverse alterations in animal and cellular models. Significantly, following Nrf2 deficiency, we failed to observe the protective benefits of miR-200a against colonic damage. Discussion: Taken together, through activating the Keap1/Nrf2 signaling pathway, miR-200a protected against DSS-induced colonic damage. These studies offer an innovative therapeutic approach for ulcerative colitis.

The role of Nrf2 in the pathogenesis and treatment of ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease involving mainly the colorectal mucosa and submucosa, the incidence of which has been on the rise in recent years. Nuclear factor erythroid 2-related factor 2 (Nrf2), known for its key function as a transcription factor, is pivotal in inducing antioxidant stress and regulating inflammatory responses. Numerous investigations have demonstrated the involvement of the Nrf2 pathway in maintaining the development and normal function of the intestine, the development of UC, and UC-related intestinal fibrosis and carcinogenesis; meanwhile, therapeutic agents targeting the Nrf2 pathway have been widely investigated. This paper reviews the research progress of the Nrf2 signaling pathway in UC.

Maternal vitamin D deficiency aggravates the dysbiosis of gut microbiota by affecting intestinal barrier function and inflammation in obese male offspring mice.

OBJECTIVES: The colonization of gut microbiota during early life may play a critical role in the progression of metabolic syndrome in adulthood. Targeting gut-based genes in the barrier function, inflammation, and lipid transportation are potential therapies for obesity. Therefore, this study focused on whether maternal deficient vitamin D (VD) intake could aggravate the dysbiosis of gut microbiota by affecting the expressions of these genes in the ileum and colon of obese male offspring mice. METHODS: Four-week-old female C57 BL/6 J mice were fed normal (VD-C) or VD-deficient (VD-D) reproductive diets throughout pregnancy and lactation (n = 15/group). Weaning male pups (n = 10/group) were fed either a high-fat (HFD; VD-C-HFD, VD-D-HFD) or normal-fat diet (control) for 16 wk. All biologic samples were obtained after the mice were anesthetized by cervical dislocation. Subsequently, the compositions of the gut microbiota in cecal contents were analyzed using 16 S ribosomal RNA sequencing. Messenger RNA expression in the ileum and colon was determined using real-time reverse transcription-polymerase chain reaction. The distributions of ZO-1 and Claudin-1 were determined using immunohistochemistry testing. RESULTS: Maternal deficient VD intake significantly aggravated the dysbiosis of gut microbiota persisting into adulthood from phylum to genus levels in the cecal contents among obese male offspring mice. This aggravation led to significantly depleted Bacteroidetes and Verrucomicrobia (Akkermansia, Alliprevotella, and Bacteroides), with higher relative abundance of Firmicutes (Lactobacillus, Lachnoclostridium, Romboutsia, and Ruminiclostridium_9) and Firmicutes/Bacteroidetes. The gene expressions of proinflammatory cytokines (Ccl2, Ccl4 and interleukin-1ß) and lipid transportation molecules (Ffar3, Fabp4, and Fabp1) were higher, and the levels of intestinal barrier function (Occludin, ZO-1, and Claudin-1) were lower in the VD-D-HFD group than those in the VD-C-HFD group. Furthermore, there were significant correlations between the dysbiosis of intestinal microbials and expressions of genes related to barrier function, inflammation, and lipid transportation in the ileum and/or colon. CONCLUSIONS: Maternal VD deficiency during pregnancy and lactation could aggravate the dysbiosis of gut microbiota to affect the progression of obesity among male offspring, which might be regulated by genes associated with barrier function, inflammation, and lipid transportation. So early life appropriate VD intake could play a significant role in preventing later obesity.

Inhibition of IRAK 1/4 alleviates colitis by inhibiting TLR4/ NF-κB pathway and protecting the intestinal barrier.

Interleukin-1 receptor-associated kinase 1/4 (IRAK1/4) is the main kinase of the Toll-like receptor (TLR)-mediated pathway, considered a new target for treating inflammatory diseases. Studies showed a significant correlation between TLRs and inflammatory responses in ulcerative colitis (UC). Therefore, in this study, after inducing experimental colitis in mice with 3% dextran sulfate sodium (DSS), different concentrations of IRAK1/4 inhibitors were administered intraperitoneally. Then, the disease activity index was assessed, including the degree of pathological damage, by HE staining. Subsequently, while western blotting detected the TLR4/NF-κB pathway and intestinal barrier protein expression (Zonula-1, Occludin, Claudin-1, JAM-A), real-time polymerase chain reaction (RT-PCR) detected the mRNA expression levels of IRAK1/4 and mucin1/2. Furthermore, the expression levels of Zonula-1 and occludin were detected by immunofluorescence, including the plasma FITC-dextran 4000 concentration, to evaluate intestinal barrier permeability. However, ELISA measured the expression of inflammatory factors to reflect intestinal inflammation in mice. Investigations showed that the IRAK 1/4 inhibitor significantly reduced clinical symptoms and pathological DSS-induced colitis damage in mice and then inhibited the cytoplasmic and nuclear translocation of NF-κB p65, including the phosphorylation of IκBα and reduction in downstream inflammatory factor production. Therefore, we established that the IRAK1/4 inhibitor effectively improves colitis induced by DSS, partly by inhibiting the TLR4/NF-κB pathway, reducing inflammation, and maintaining the integrity of the colonic barrier.

Maternal vitamin D deficiency increases the risk of obesity in male offspring mice by affecting the immune response.

OBJECTIVES: Recently, many epidemiologic and animal studies have indicated that obesity has its origin in early stages of life, including the inappropriate balance of some nutrients. So the objectives of this study were to determine the risk of obesity in male offspring mice as a consequence of maternal vitamin D (VD) deficiency mediating the disordered immune response. METHODS: C57BL/6J female mice 4 wk old were fed VD-deficient or normal reproductive diets during pregnancy and lactation. Their male offspring were given control and high-fat diets for 16 wk after weaning and then weighed and euthanized. The serum was collected for biochemical analyses. Epididymal (eWAT) and inguinal white adipose tissue (iWAT) were excised for histologic examination, immunohistochemistry, gene expression of inflammatory factors, and determination by flow cytometry of the proportions of immune cells. RESULTS: Insufficient maternal VD intake exacerbated the development of obesity in male offspring mice that were both obese and non-obese, as evidenced by larger adipose cells and abnormal glucose and lipid metabolisms. Also, the expressions of proinflammatory cytokines were increased and that of anti-inflammatory cytokines was decreased in eWAT and/or iWAT in the maternal VD-deficient group, accompanied by higher levels of tumor necrosis factor-α and/or interferon-γ and lower levels of interleukin-4 and interleukin-10. Insufficient maternal VD intake was also observed to induce a shift in the profiles of immune cells in the eWAT and/or iWAT of male offspring that were both obese and non-obese, resulting in increased percentages of M1 macrophages, adipose tissue dendritic cells, and CD4+ and CD8+ T cells but a significant decrease in the percentages of M2 macrophages. All these changes in the immune cell profile were more obvious in the eWAT than those in the iWAT. CONCLUSIONS: Maternal VD deficiency might promote the development of obesity in male offspring mice partly by modulating the immune cell populations and causing a polarization in the adipose depots.