AIM To analyze the improvement effect of TRPV1 expression levels on inflammatory reaction and vascular atherosclerosis degree in vivo in diabetic rats.

METHODS A total of 30 SD diabetic rats were randomLy divided into 2 groups: pepper ingredients group (feeding with pepper ingredients) and model group (feeding with high-sugar and high-fat feed), with 15 rats in each group. Fifteen normal SD rats served as normal group (feeding with regular feed). The indexes of serum TNF-α, IFN-γ, IL-2, IL-6 and IL-10 levels were compared between the 3 groups. The expression levels of TRPV1 at peripheral blood monocytes were measured by Western blot and were compared between the 3 groups. The degree of aortic atherosclerosis and plaque area were also compared between the 3 groups. The correlation between the various inflammatory factors levels and the TRPV1 expression levels in peripheral blood monocytes was assessed by Pearson correlation analysis. The risk degrees of the above indexes for the vascular atherogenesis in diabetic rats were analyzed by multivariate logistic regression analysis and the clinical values of the TRPV1 expression levels for the vascular atherosclerosis in diabetic rats were analyzed by the receiver operating characteristic (ROC) curve.

RESULTS Compared with those in normal group, the serum levels of TNF-α, IFN-γ, IL-2, IL-6 and IL-10 in model group were higher, and IL-10 was lower (P<0.05) and the serum levels of TNF-α, IFN-γ, IL-2, IL-6 in pepper ingredients group were lowe, and IL-10 was higher (P<0.05, P<0.01). Compared with those in normal group, the TRPV1 expression levels in peripheral blood monocytes in pepper ingredients group were higher (P<0.05), but no significant difference was observed in the TRPV1 expression levels in model group. Compared with those in normal group, the aortic atherosclerotic plaque areas in model group were higher (P<0.05) and the aortic atherosclerotic plaque areas in model group were smaller (P<0.05). The levels of inflammatory factors TNF-α, IFN-γ, IL-2, IL-6 in three groups of rats were negatively correlated with the expression level of TRPV1 in peripheral blood monocytes, while IL-10 was positively correlated with the expression level of TRPV1 in peripheral blood monocytes (all P<0.05). By the multivariate Logistic regression analysis, feeding pepper ingredients and TRPV1 expression levels were the protective factors for the vascular atherogenesis in diabetic rats (P<0.05). The cut-off point of TRPV1 expression levels (0.56) was identified by the ROC curve to predict the vascular atherogenesis in diabetic rats, with the sensitivity of 86.3% and specificity of 80.6% (AUC=0.872).

CONCLUSION The up-regulated TRPV1 expression levels of diabetic rats fed with pepper ingredients inhibit the inflammatory reaction and improve the vascular atherosclerosis.