Hepatic nNOS impaired hepatic insulin sensitivity through the activation of p38 MAPK.

Neuronal nitric oxide synthase (nNOS) interacts with its adaptor protein NOS1AP through its PZD domain in the neurons. Previously, we had reported that NOS1AP enhanced hepatic insulin sensitivity through its PZD-binding domain, which suggested that nNOS might mediate the effect of NOS1AP. This study aimed to examine the role and underlying mechanisms of nNOS in regulating hepatic insulin sensitivity. nNOS co-localized with NOS1AP in mouse liver. The overexpression of NOS1AP in mouse liver decreased the level of phosphorylated nNOS (p-nNOS (Ser1417)), the active form of nNOS. Conversely, the liver-specific deletion of NOS1AP increased the level of p-nNOS (Ser1417). The overexpression of nNOS in the liver of high-fat diet-induced obese mice exacerbated glucose intolerance, enhanced intrahepatic lipid accumulation, decreased glycogen storage, and blunted insulin-induced phosphorylation of IRbeta and Akt in the liver. Similarly, nNOS overexpression increased triglyceride production, decreased glucose utilization, and downregulated insulin-induced expression of p-IRbeta, p-Akt, and p-GSK3beta in the HepG2 cells. In contrast, treatment with Nω-propyl-L-arginine (L-NPA), a selective nNOS inhibitor, improved glucose tolerance and upregulated insulin-induced phosphorylation of IRbeta and Akt in the liver of ob/ob mice. Furthermore, overexpression of nNOS increased p38MAPK phosphorylation in the HepG2 cells. In contrast, inhibition of p38MAPK with SB203580 significantly reversed the nNOS-induced inhibition of insulin-signaling activity (all P < 0.05). This indicated that hepatic nNOS inhibited the insulin-signaling pathway through the activation of p38MAPK. These findings suggest that nNOS is involved in the development of hepatic insulin resistance and that nNOS might be a potential therapeutic target for diabetes.

Resveratrol Attenuates High Glucose-Induced Vascular Endothelial Cell Injury by Activating the E2F3 Pathway.

Type 2 diabetes mellitus (T2DM) is the most common metabolic disease. High glucose-induced macrovascular disease and microangiopathy are major complications of diabetes. E2F3, a member of the E2F transcription factor family, is closely related to cardiovascular diseases. Resveratrol, a nonflavonoid polyphenolic compound widely found in plants, has been shown to have cardiovascular protection. However, there are few studies on whether resveratrol can effectively treat diabetic angiopathy, and the specific mechanism involved needs further study. This study investigated whether E2F3 transcription factors are involved in the process of vascular endothelial injury induced by high glucose and observed its effects on the proliferation of vascular endothelial cells. Then, it analyzed whether resveratrol can inhibit high glucose-induced vascular endothelial cell injury by regulating the E2F3 pathway. We demonstrated that the expression level of the E2F3 transcription factor was significantly inhibited in high glucose state. Resveratrol inhibited high glucose-induced vascular endothelial cell injury by upregulating the E2F3 pathway. High glucose can induce vascular endothelial injury by inhibiting E2F3 gene expression, while resveratrol can inhibit high glucose-induced vascular endothelial injury by activating the E2F3 pathway.

Decreased number and impaired function of type 1 regulatory T cells in autoimmune diseases.

Type 1 regulatory T (Tr1) cell is a special type of T regulatory cells with surface molecular markers such as lymphocyte-activation gene 3 and CD49b. A key property of Tr1 cells is the capability to produce high-level interleukin 10 (IL-10) upon activation, in a FOXP3-independent manner. The immunosuppressive function of IL-10 producing Tr1 cells has been extensively studied for many years. Autoimmune diseases (AIDs) are conditions in which the immune system breaks down and starts to attack the body. AIDs include inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis (MS), type 1 diabetes mellitus, Greaves' disease, and so forth. In recent years, more and more studies have documented that the number of Tr1 cells is decreased and the function is inhibited in a variety of AIDs, among which MS is the most widely studied. The protocol for engineering Tr1 cell therapy has been established and is gradually being used in clinical practice in recent years. Tr1 cell therapy has been proven to be safe and effective, but it is mainly involved in myeloid leukemia, graft versus host disease currently. Its therapeutic role in AIDs still needs to be further explored. In this study, we will summarize the research advances of Tr1 cells in AIDs, which will provide useful information for treating AIDs through Tr1 cell therapy in the future.

Associations of TNFRSF1A Polymorphisms with Autoimmune Thyroid Diseases: A Case-Control Study.

Previous studies have shown associations of polymorphisms in the tumor necrosis factor (TNF) receptor super family member 1A (TNFRSF1A) gene with several groups of inflammatory and autoimmune related diseases, but associations of TNFRSF1A polymorphisms with autoimmune thyroid diseases (AITD), mainly including two sub-types of Hashimoto's thyroiditis (HT) and Graves' disease (GD), in the Chinese Han population is unclear. A case-control study of 1812 subjects (965 AITD patients and 847 unrelated healthy controls) was conducted to assess AITD associations with five single nucleotide polymorphisms (SNPs), including rs4149576, rs4149577, rs4149570, rs1800693, and rs767455 in the TNFRSF1A gene locus. Genotyping was performed and evaluated using the platform of ligase detection reaction. No significant difference was observed in the allele and genotype frequencies between HT or GD patients and controls in any of the five SNPs in the TNFRSF1A gene (all p values >0.05). However, a moderate association of rs4149570 with HT was found after adjusting for age and gender [odds ratio (OR)=1.40, p=0.03]. No obvious difference was found in the haplotype distribution of any of the five SNPs in the TNFRSF1A gene between the AITD patients and controls. These data suggest that these five SNPs in the TNFRSF1A gene are not associated with AITD in the Chinese Han population, but rs4149570 shows a weak association with HT after adjusting for gender and age.