Center for Thrombosis Research, Florida Hospital, Orlando, FL 32804, USA.
Platelets. 2010;21(7):571-4. doi: 10.3109/09537104.2010.512403.
The multifunctional cytokine, TWEAK (TNF-like weak inducer of apoptosis), is a member of the TNFα superfamily. TWEAK is found in a broad range of cell types and has been linked to cell growth and survival, angiogenesis and other inflammatory processes. These functions and their importance in inflammatory diseases have made TWEAK an attractive pharmaceutical target, particularly for immunotherapy with monoclonal antibodies (mAbs). Immunotherapy targeting another TNFα family member, CD154, was associated with thrombosis in clinical trials. Subsequent studies identified platelets, which contain CD154, as a possible contributing factor to thrombosis in these trials. Since clinical trials with anti-TWEAK mAbs have already begun, we considered it important to determine whether platelets contain TWEAK. Using a variety of immunologic methods we found that, upon activation, human platelets expose TWEAK antigen and release it in soluble form (sTWEAK). By flow cytometry we determined that human platelets activated by TRAP (Thrombin Receptor Agonist Peptide) and other agonists expose TWEAK antigen (22% median positivity) and release TWEAK positive microparticles. The presence of TWEAK on platelets was confirmed by confocal microscopy. By ELISA, we found that sTWEAK is released by activated platelets. Finally, western blot analysis revealed TWEAK protein (34 kDa) in washed platelet lysates. The finding that human platelets contain TWEAK raises important questions about its possible functions in normal physiology, as well as in inflammatory diseases and their treatment.
多功能细胞因子 TWEAK（TNF 样凋亡弱诱导剂）是 TNFα 超家族的一员。TWEAK 存在于广泛的细胞类型中，与细胞生长和存活、血管生成和其他炎症过程有关。这些功能及其在炎症性疾病中的重要性使 TWEAK 成为有吸引力的药物靶点，特别是用于免疫治疗的单克隆抗体 (mAb)。针对另一种 TNFα 家族成员 CD154 的免疫疗法与临床试验中的血栓形成有关。随后的研究确定含有 CD154 的血小板是这些试验中血栓形成的一个可能的促成因素。由于针对抗 TWEAK mAb 的临床试验已经开始，我们认为确定血小板是否含有 TWEAK 非常重要。使用各种免疫方法，我们发现，在激活后，人血小板暴露 TWEAK 抗原并以可溶性形式释放它（sTWEAK）。通过流式细胞术，我们确定被 TRAP（血栓素受体激动肽）和其他激动剂激活的人血小板暴露 TWEAK 抗原（中位数阳性率为 22%）并释放 TWEAK 阳性微粒。血小板上存在 TWEAK 通过共聚焦显微镜得到证实。通过 ELISA，我们发现激活的血小板释放 sTWEAK。最后，Western blot 分析显示在洗涤血小板裂解物中存在 TWEAK 蛋白（34 kDa）。发现人血小板含有 TWEAK 提出了关于其在正常生理以及炎症性疾病及其治疗中的可能功能的重要问题。
