Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease. TGF-b1/Smad3 signalling plays a major pathological role in DN; however, the contribution of Smad4 has not been examined. Smad4 depletion in the kidney using anti-Smad4 locked nucleic acid halted progressive podocyte damage and glomerulosclerosis in mouse type 2 DN, suggesting a pathogenic role of Smad4 in podocytes. Smad4 is upregulated in human and mouse podocytes during DN. Conditional Smad4 deletion in podocytes protects mice from type 2 DN, independent of obesity. Mechanistically, hyperglycaemia induces Smad4 localization to mitochondria in podocytes, resulting in reduced glycolysis and oxidative phosphorylation and increased production of reactive oxygen species. This operates, in part, via direct binding of Smad4 to the glycolytic enzyme PKM2 and reducing the active tetrameric form of PKM2. In addition, Smad4 interacts with ATPIF1, causing a reduction in ATPIF1 degradation. In conclusion, we have discovered a mitochondrial mechanism by which Smad4 causes diabetic podocyte injury.

The IBS-D and UC groups showed similar clinical symptom scores, visceral sensitivity, and levels of serotonin signaling pathway indicators in the plasma and colonic mucosa. However, the pain threshold and 5-HT7R expression in the colonic mucosa were significantly different between these groups. The results reveal that (1) IBS-D and UC are related to visceral sensitivity pathogenesis and the clinical manifestations of these conditions and (2) the observed differences in visceral hypersensitivity are possibly due to differences in levels of the 5-HT7 receptor, a component of the 5-HT signaling pathway.

Huangqin-tang (HQT) is a traditional Chinese medicine (TCM) formula widely used for the treatment of inflammatory bowel disease in China. However, the molecular mechanisms by which HQT protects the colon are unclear. We studied the protective effects of HQT and the underlying mechanisms in an experimental mouse model and in vitro. In vivo, dextran sodium sulphate (DSS)-induced acute and chronic colitis were significantly ameliorated by HQT as gauged by phenotypic, histopathologic and inflammatory manifestations of the disease. Mechanistically, DSS-induced nuclear factor-κB (NF-κB) signalling was inhibited by HQT. Moreover, HQT-treated mice demonstrated significant changes in cell apoptosis, expression of apoptosis-associated genes such as caspase-3, bax, bcl-2, and intestinal permeability. HQT also increased occluding and zonula occludens-1 (ZO-1), inhibited cell proliferation (Ki67), and increased regulatory T cells numbers, protein expression of Foxp3 and IL-10 in the colonic tissue. In vitro, HQT down-regulated production of pro-inflammatory cytokines and supressed the NF-κB signalling pathway in lipopolysaccharides-induced RAW 264.7 macrophages. Our study suggests that HQT plays a critical role in regulating intestinal epithelial cell homeostasis, inflammation and immune response in colitis and offers novel therapeutic options in the management of inflammatory bowel disease.

The results indicate that baicalin regulates immune balance and relieves the ulcerative colitis-induced inflammation reaction by promoting proliferation of CD4(+)CD29(+) cells and modulating immunosuppressive pathways.

Baicalin, a flavonoid, has a wide range of pharmacological properties, including immunomodulation. The objective of this study was to investigate the effect of baicalin on the balance of T helper 17 (Th17) and regulatory T (Treg) cells in a colitis model. The rat colitis model was induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). Baicalin (10 ml/kg, each) or mesalazine (positive control) was then administered orally for 7 days. Inflammatory and immunological responses were evaluated by pathology, enzyme-linked immunosorbent assay, real-time polymerase chain reaction, western blot analysis, and flow cytometry. Our study showed that baicalin not only significantly attenuated TNBS-induced colitis by reducing the disease activity index as well as macroscopic and microscopic scores, but it also improved the weight loss and shortening of the colon. Baicalin treatment also induced a significant decrease in the levels of inflammatory mediators, including the myeloperoxidase activity, the levels of tumor necrosis factor α, IL-1β, and Th1-related cytokines IL-12 and IFN-γ. Furthermore, the beneficial effects of baicalin seem to be associated with regulation of the Th17 and Treg paradigm. We found that administration of baicalin significantly downregulated the number of Th17 cells and the levels of Th17-related cytokines (IL-17 and IL-6) and retinoic acid receptor-related orphan receptor γt. In contrast, there was an increase in Treg cells numbers, Treg-related cytokines transforming growth factor-β and IL-10, and forkhead box P3. Our results suggest that the anti-inflammatory effect of baicalin may be linked to modulation of the balance between Th17 and Treg cells in TNBS-induced ulcerative colitis.