The in vitro effect of antirheumatic drugs on platelet function

Several antirheumatic drugs lower the cardiovascular risk among rheumatoid arthritis patients. It is, however, unknown whether inhibition of platelet function contributes to this risk reduction. Only few studies have investigated the potential role of platelets as a target of antirheumatic drugs. In this study, platelet function was tested in vitro in samples from 24 healthy individuals spiked with antirheumatic drugs in clinically relevant concentrations or vehicle. Platelet aggregation was tested with 96-well light transmission aggregometry (LTA), and when an effect ≥20% compared to vehicle was observed, flow cytometric platelet aggregation and activation were evaluated and closure time was measured by Platelet Function Analyzer (PFA-200). When evaluated by LTA, teriflunomide (the active metabolite of leflunomide), tocilizumab, and prednisolone reduced ADP- and collagen-induced platelet aggregation ≥20%, while adalimumab increased TRAP-induced platelet aggregation ≥20%. Using flow cytometry, agonist-induced platelet aggregation with teriflunomide or vehicle was mean ± standard deviation (SD); 30.7% ± 5.8 vs. 41.7% ± 6.5, p = 0.02 using ADP, and 34.7% ± 13.9 vs. 55.8% ± 3.9, p = 0.01 using collagen. Results indicate that teriflunomide, prednisolone, and tocilizumab inhibit, and adalimumab increases platelet aggregation. The study suggests that the majority of antirheumatic drugs mainly reduced cardiovascular risk through indirect effects (e.g., reducing inflammation).多款抗风湿药物可降低类风湿关节炎患者的心血管风险。然而目前尚不清楚，血小板功能抑制是否参与了这一风险降低过程。目前仅有少数研究探讨了血小板作为抗风湿药物作用靶点的潜在价值。本研究纳入24名健康志愿者的血液样本，在体外向样本中加入临床相关浓度的抗风湿药物或溶媒对照，对血小板功能进行检测。本研究采用96孔透光率聚集法（LTA）检测血小板聚集情况；当检测到与溶媒对照组相比差异≥20%的效应时，进一步通过流式细胞术评估血小板聚集与活化状态，并借助血小板功能分析仪（PFA-200）检测闭合时间。经LTA检测发现，特立氟胺（teriflunomide，来氟米特的活性代谢产物）、托珠单抗（tocilizumab）与泼尼松龙（prednisolone）可使二磷酸腺苷（ADP）及胶原诱导的血小板聚集率降低≥20%；而阿达木单抗（adalimumab）则可使凝血酶受体激活肽（TRAP）诱导的血小板聚集率升高≥20%。采用流式细胞术检测激动剂诱导的血小板聚集情况：以ADP为激动剂时，特立氟胺组与溶媒对照组的血小板聚集率分别为30.7%±5.8与41.7%±6.5（p=0.02）；以胶原为激动剂时，两组的该指标分别为34.7%±13.9与55.8%±3.9（p=0.01）。研究结果表明，特立氟胺、泼尼松龙与托珠单抗可抑制血小板聚集，而阿达木单抗则会促进血小板聚集。本研究提示，多数抗风湿药物主要通过间接途径（如减轻炎症反应）降低类风湿关节炎患者的心血管风险。