AIM:To study the immunological protective effect of H pylori vaccine with chitosan as an adjuvant and its mechanism.

The pathogenic mechanism of insulin resistance and associated diseases such as metabolic syndrome and diabetes remains unclear. Since inflammatory cytokines secreted by T cells play an important role in immune system homeostasis, we evaluated the role of interleukin-6 (IL-6) and the Th17/Treg balance in insulin sensitivity and the underlying mechanism in a rat model. After establishing an insulin-resistant rat model, the rats were injected with anti-mouse IL-6R receptor antibody (MR16-1) to block IL-6. Adipose tissue and blood samples were obtained for the analysis of cytokines, Th17 and Treg markers, and insulin sensitivity blood parameters, for comparisons with those of the normal control group, IL-6-blocked control group, and insulin resistance control group. In the insulin resistance control group, the expression levels of IL-6, RORγt, and IL-17 increased, whereas those of IL-10, FoxP3, and CD4+CD25+Treg decreased. Insulin sensitivity decreased, whereas glucose, total serum cholesterol, triglycerides, and free fatty acid levels significantly increased. However, the completely opposite effects for all parameters were detected in the insulin resistance IL-6-blocked group. Insulin resistance can cause inflammation and an imbalance in Th17 cells/Treg cells. IL-6 can restore this imbalance and play an important role in the development and progression of insulin resistance.

The aim of the present study was to delineate the therapeutic effect of a Helicobacter pylori vaccine with chitosan as an adjuvant, as well as to identify the potential mechanism against H. pylori infection when compared with an H. pylori vaccine, with cholera toxin (CT) as an adjuvant. Mice were first infected with H. pylori and, following the establishment of an effective infection model, were vaccinated using an H. pylori protein vaccine with chitosan as an adjuvant. Levels of H. pylori colonization, H. pylori-specific antibodies and cytokines were determined by enzyme-linked immunosorbent assay. The TLR4 and Foxp3 mRNA and protein levels were determined by reverse transcription polymerase chain reaction and immunohistochemistry, respectively. It was identified that the H. pylori elimination rate of the therapeutic vaccine with chitosan as an adjuvant (58.33%) was greater than the therapeutic vaccine with CT as an adjuvant (45.45%). The therapeutic H. pylori vaccine with chitosan as an adjuvant induced significantly greater antibody and cytokine levels when compared with the control groups. Notably, the IL-10 and IL-4 levels in the groups with chitosan as an adjuvant to the H. pylori vaccine were significantly greater than those in the groups with CT as an adjuvant. The mRNA expression levels of TLR4 and Foxp3 were significantly elevated in the mice that were vaccinated with chitosan as an adjuvant to the H. pylori vaccine, particularly in mice where the H. pylori infection had been eradicated. The H. pylori vaccine with chitosan as an adjuvant effectively increased the H. pylori elimination rate, the humoral immune response and the Th1/Th2 cell immune reaction; in addition, the therapeutic H. pylori vaccine regulated the Th1 and Th2 response. The significantly increased TLR4 expression and decreased CD4+CD25+Foxp3+Treg cell number contributed to the immune clearance of the H. pylori infection. Thus, the present findings demonstrate that in mice the H. pylori vaccine with chitosan as an adjuvant exerts an equivalent immunotherapeutic effect on H. pylori infection when compared with the H. pylori vaccine with CT as an adjuvant.

The host immune response plays an important role in the pathogenesis of Helicobacter pylori infection. The aim of this study was to clarify the immune pathogenic mechanism of Helicobacter pylori infection via TLR signaling and gastric mucosal Treg cells in mice. To discover the underlying mechanism, we selectively blocked the TLR signaling pathway and subpopulations of regulatory T cells in the gastric mucosa of mice, and examined the consequences on H. pylori infection and inflammatory response as measured by MyD88, NF-κB p65, and Foxp3 protein expression levels and the levels of Th1, Th17 and Th2 cytokines in the gastric mucosa. We determined that blocking TLR4 signaling in H. pylori infected mice decreased the numbers of Th1 and Th17 Treg cells compared to controls (P < 0.001–0.05), depressed the immune response as measured by inflammatory grade (P < 0.05), and enhanced H. pylori colonization (P < 0.05). In contrast, blocking CD25 had the opposite effects, wherein the Th1 and Th17 cell numbers were increased (P < 0.001–0.05), immune response was enhanced (P < 0.05), and H. pylori colonization was inhibited (P < 0.05) compared to the non-blocked group. In both blocked groups, the Th2 cytokine IL-4 remained unchanged, although IL-10 in the CD25 blocked group was significantly decreased (P < 0.05). Furthermore, MyD88, NF-κB p65, and Foxp3 in the non-blocked group were significantly lower than those in the TLR4 blocked group (P < 0.05), but significantly higher than those of the CD25 blocked group (P < 0.05). Together, these results suggest that there might be an interaction between TLR signaling and Treg cells that is important for limiting H. pylori colonization and suppressing the inflammatory response of infected mice.

H. pylori could inhibit the differentiation of T lymphocytes toward Th2 cells, promote the Th1 cell differentiation, and induce Th1-biased immune response. The expression of Tim-1 and Tim-3 could reflect Th2 and Th1 immune response, respectively, which provide evidence for the prevention and treatment of H. pylori infection and correlation diseases through regulation of Tim-1 and Tim-3.