RESUMEN
OBJECTIVE: To study the expression and significance of Th17 cells and related cytokines in the peripheral blood, skin and lung in a murine model of systemic sclerosis (SSc). METHODS: Twenty female BALB/c mice were randomly divided into 2 groups, including a control group and a bleomycin(BLM) -injected-4-week group (SSc group). Pathological changes of the skin and lung were detected. The proportion of CD4(+)IL-17(+)Th17 cells in the peripheral blood, skin and lung of the mice was determined by flow cytometry. The mRNA expressions of RORγt, IL-17A, and IL-6 of the skin and lung were evaluated by real-time PCR. Enzyme linked immunosorbent assay was used to measure the levels of IL-17 and IL-6 in the serum. RESULTS: Dermal inflammation and the score of PF were significantly increased in the SSc group as compared with the control group (2.60±0.84 vs. 0.40±0.52, 2.80± 1.81 vs.0.60±0.70). Hydroxyproline(HYP) contents of the skin and lung were obviously increased in the SSc group than in the control group [(3.17±1.74) mg/g vs. (1.45±0.40) mg/g,(0.53±0.14) mg/g vs. (0.38±0.16) mg/g], all P<0.05. The percentage of Th17 cells in the peripheral blood, skin and lung of the SSc group were significantly increased as compared with the control group [(2.07±0.89)% vs. (1.02±0.32)%,(5.80±2.02)% vs. (1.64±0.58)%,(5.24±2.43)% vs. (1.92±0.98)%,P <0.01]. Compared with the control group, the mRNA levels of IL-17A, RORγt, IL-6 in the skin and lung of the SSc group were higher. The levels of IL-17, IL-6 of the SSc group in the serum were significantly increased, all P<0.05. The frequency of Th17 cells, and the levels of IL-17 and IL-6 in the blood had a positive correlation with dermal and pulmonary inflammation, fibrosis and HYP contents of the skin and lung, The frequency of Th17, IL-17 and IL-6 in the skin and lung had, respectively, a positive correlation with dermal and pulmonary inflammation, HYP contents of the skin and lung, all P<0.01. CONCLUSION: Th17 cells were significantly increased in the peripheral blood, skin and lung of a murine model of SSc, and had an intimate relationship with inflammation and fibrosis of the skin and lung, and involved the pathogenesis of SSc through producing IL-17, IL-6.