| Background and Objective Ankylosing spondylitis (AS) is an autoimmune disease of chronic inflammation, which pathogenesis is complex and unkonwn. Recent studies have demonstrated that chemokines and inflammatory factors constitute a complex cytokine system, which plays a key role in the pathogenesis of AS through molecular interaction and mutual influence. CXCL16, one of multifunctional chemokines of CXC subfamily, performs an important role in the inflammation and immune response, and studies have found that CXCL16 was significantly increased in peripheral blood of AS, but the pathogenesis is unclear. In this study, we will explore the role of CXCL16/CXCR6 in the pathogenesis of AS and the functional mechanism of recombinant tumor necrosis factor receptorFc fusion protein (rhTNFR:Fc) by detecting the expression of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), CXCL16 and CXCR6 in peripheral blood, even more, the effect of CXCL16 on lymphocyte proliferation, and comparing the expression of CXCL16, CXCR6 in active AS patients with those in treated patients.Methods All of twenty-two cases of AS in active were treated with 25 mg of rhTNFR:Fc subcutaneously, twice a week, for 3 consecutive months; besides, twenty-two of healthy controls who were matched with AS patients in age and gender were collected. The level of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG) and CXCL16 in serum were respectively tested by enzyme-linked immunosorbent assay (ELISA) and the lever of CXCL16, CXCR6 mRNA in peripheral blood cells (PBMC) were respectively measured by fluorescent quantitative PCR; then the proliferation ability of lymphocytes and the level of RANKL in culture supernatant stimulated by different concentrations (40ng/ml and 80 ng/ml, respectively) of rhCXCL16 were respectively detected by CCK-8 and ELISA. Finally, statistical analysis were tested by Mest, one-way ANOVA and Spearman’S correlation analysis.Results 〢fter three months’treatment, the clinical response reached ASAS20 standard of 21 cases, accounted for 95.45%, ASAS40 of 18 cases, accounted for 81.82%, ASAS70 of 12 cases, accounted for 54.55%. Besides, clinical indicators including Erythrocyte sedimentation rate (ESR), C reactive protein (CRP), Bath AS activity index (BASDAI), Bath AS functional index (BASFI), spinal pain and nocturnal pain were significantly reduced after treatment of rhTNFR:Fc in AS (7=8.38, t=8.45,t=13.23,t=10.72,t=24.91, t=39.14, P<0.05, respectively). ②Serum RANKL level and RANKL/OPG ratio in active AS patients were significantly higher than those in healthy controls [(6.01±1.00) pmol/1 vs (3.41±0.61) pmol/1,t=10.41; (0.98±0.16) vs (0.62±0.16), t=7.45, P<0.05, respectively]. ③Serum CXCL16 level in active AS patients were all significantly higher than those in healthy controls and in treated patients [(2.28±0.15) ng/ml vs (1.83±0.11) ng/ml vs (1.82±0.12) ng/ml, /=11.37, t=11.35, P<0.05, respectively]. Coincidentally, CXCL16 and CXCR6 mRNA levels in active AS patients were all significantly higher than those in healthy controls and in treated patients [(0.058±0.030) vs (0.033±0.008) vs(0.034±0.014), t=3.74, t=337, (0.046±0.024) vs (0.020±0.007) vs (0.025±0.009),t=4.96, t=4.06, P<0.05, respectively]. ④The proliferation ability of lymphocytes stimulated by CXCL16 (40ng/m,80 ng/ml) was significantly higher than that without CXCL16 in active AS patients [(136±31)%vs (183±35)%vs (100%),t=5.52,t=11.25, P<0.05, respectively], however, the proliferation ability of lymphocytes has no statistically significance in healthy controls with or without CXCL16 (P>0.05, respectively); the culture supernatant level of RANKL that stimulated by CXCL16(40n/ml,80n/ml) was significantly higher than that without CXCL16 in active AS [(1.439±0.091) pmol/1 vs (1.850±0.111)pmol/l vs (1.097±0.088) pmol/1, t=1.49,/=25.55, P<0.05, respectively]. ⑤There were positive lineal correlation among the serum levels of CXCL16, RANKL, RANKLL/OPG ratio and the laboratory indicators, such as CRP and ESR (r=0.87, r=0.8, r=0.45, r=0.639, P<0.05, respectively), but there was no significant correlation between the serum levels of CXCL16 and OPG (r=0.075, P>0.05).Conclusion CXCL16/CXCR6 may play an important role in the pathogenesis of AS, and as one of the most effective targeted drugs, rhTNFR:Fc could suppress inflammation and bone destruction by reducing the expression of CXCL16/CXCR6. |
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