Effects of Ginkgo biloba extract on cytokines in rats with TNBS-induced ulcerative colitis

Abstract

AIM: To investigate the effects of Ginkgo biloba extract (Egb) on cytokine profile produced by splenocytes, colonic mucosa and serum and to study the main mechanism of EGb in protection of TNBS-induced ulcerative colitis in rats. METHODS: A rat ulcerative colitis model was induced by 2.4.6-trinitrobenzene sulfonic acid (TNBS). All rats were divided into four groups: normal, TNBS, TNBS+NS, and TNBS+EGb. The macroscopical and histological changes of the colon were evaluated. The IL-12, IFN-γ and IL-4 produced by splenocytes, colonic mulosal and serum were analyzed with ELISA. RESULTS: In TNBS+EGb group, the macroscopical and histological scores were significantly lower than those of TNBS group (2.83 0.94 vs 5.33 1.50, P <0.01, 1.92 0.67 vs 4.33 0.98, P <0.01). In the TNBS+EGb group, a lower level of IFN-γ production in splenocytes (60 21.5 vs 125.6 14.6, P <0.01); colonic mucosa (202.8 49.6 vs 431.8 57.6, P <0.01) and serum (8.6 1.4 vs 13.5 1.7, P <0.01) was noticed as compared with TNBS group. In comparison with TNBS group, significantly increased IL-4 was noticed (splenocytes: 11.2 1.3 vs 6.05 1.5, P <0.01; colonic mucosa: 10.2 1.9 vs 6.9 1.4, P <0.01; serum: 7.9 1.8 vs 4.2 1.1, P <0.01) in TNBS+EGb group. IL-12 production by serum in TNBS+EGb group was lower than that of TNBS group (8.2 2.2 vs 25.8 4.8, P <0.01). The ratio of IL-12/IL-4 was lower in TNBS+EGb group compared with TNBS group (serum: 1.13 0.49 vs 6.4 1.8, P <0.01). The ratio of IL-12/IL-4 was lower than that in TNBS+EGb group compared with TNBS group (splenocytes:5.2 2.0 vs 21.9 4.9, P <0.01; colonic mucosa: 20.9 7.97 vs 65.9 18, P <0.01; serum: 1.1 0.3 vs 3.4 0.8, P <0.01). CONCLUSION: TNBS-induced ulceratived colitis is a Th1 type dominant (IL-12 overproduction)murine model; EGb has protective effects on ulcerative colitis of rat by suppresses of increased IL-12 and IFN-γ and maintaines the balance of helper T cell 1 with helper T cell 2.