Chokshi Rikki, Bennett Orville, Zhelay Tetyana, Kozak J Ashot
Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine, College of Science and Mathematics, Wright State University, Dayton, OH, United States.
Front Physiol. 2021 Oct 18;12:727549. doi: 10.3389/fphys.2021.727549. eCollection 2021.
Non-steroidal anti-inflammatory drugs (NSAIDs) are used for relieving pain and inflammation accompanying numerous disease states. The primary therapeutic mechanism of these widely used drugs is the inhibition of cyclooxygenase 1 and 2 (COX1, 2) enzymes that catalyze the conversion of arachidonic acid into prostaglandins. At higher doses, NSAIDs are used for prevention of certain types of cancer and as experimental treatments for Alzheimer's disease. In the immune system, various NSAIDs have been reported to influence neutrophil function and lymphocyte proliferation, and affect ion channels and cellular calcium homeostasis. Transient receptor potential melastatin 7 (TRPM7) cation channels are highly expressed in T lymphocytes and are inhibited by Mg, acidic pH, and polyamines. Here, we report a novel effect of naproxen, ibuprofen, salicylate, and acetylsalicylate on TRPM7. At concentrations of 3-30mM, they reversibly inhibited TRPM7 channel currents. By measuring intracellular pH with the ratiometric indicator BCECF, we found that at 300μM to 30mM, these NSAIDs reversibly acidified the cytoplasm in a concentration-dependent manner, and propose that TRPM7 channel inhibition is a consequence of cytosolic acidification, rather than direct. NSAID inhibition of TRPM7 channels was slow, voltage-independent, and displayed use-dependence, increasing in potency upon repeated drug applications. The extent of channel inhibition by salicylate strongly depended on cellular PI(4,5)P levels, as revealed when this phospholipid was depleted with voltage-sensitive lipid phosphatase (VSP). Salicylate inhibited heterologously expressed wildtype TRPM7 channels but not the S1107R variant, which is insensitive to cytosolic pH, Mg, and PI(4,5)P depletion. NSAID-induced acidification was also observed in Schneider 2 cells from , an organism that lacks orthologous COX genes, suggesting that this effect is unrelated to COX enzyme activity. A 24-h exposure to 300μM-10mM naproxen resulted in a concentration-dependent reduction in cell viability. In addition to TRPM7, the described NSAID effect would be expected to apply to other ion channels and transporters sensitive to intracellular pH.
非甾体抗炎药（NSAIDs）用于缓解伴随多种疾病状态的疼痛和炎症。这些广泛使用的药物的主要治疗机制是抑制环氧化酶1和2（COX1、2），这两种酶催化花生四烯酸转化为前列腺素。在较高剂量下，NSAIDs用于预防某些类型的癌症，并作为阿尔茨海默病的实验性治疗药物。在免疫系统中，已有报道称各种NSAIDs会影响中性粒细胞功能和淋巴细胞增殖，并影响离子通道和细胞钙稳态。瞬时受体电位褪黑素7（TRPM7）阳离子通道在T淋巴细胞中高度表达，并受到镁、酸性pH值和多胺的抑制。在此，我们报告了萘普生、布洛芬、水杨酸盐和乙酰水杨酸盐对TRPM7的一种新作用。在3-30mM的浓度下，它们可逆地抑制TRPM7通道电流。通过用比率指示剂BCECF测量细胞内pH值，我们发现，在300μM至30mM时，这些NSAIDs以浓度依赖的方式可逆地酸化细胞质，并提出TRPM7通道抑制是细胞质酸化的结果，而非直接作用。NSAIDs对TRPM7通道的抑制作用缓慢、不依赖电压，并表现出使用依赖性，在重复用药时效力增加。水杨酸盐对通道的抑制程度强烈依赖于细胞内磷脂酰肌醇-4,5-二磷酸（PI(4,5)P）水平，当用电压敏感脂质磷酸酶（VSP）耗尽这种磷脂时就可揭示这一点。水杨酸盐抑制异源表达的野生型TRPM7通道，但不抑制S1107R变体，该变体对细胞质pH值、镁和PI(4,5)P耗尽不敏感。在缺乏直系同源COX基因的果蝇的Schneider 2细胞中也观察到了NSAIDs诱导的酸化，这表明这种作用与COX酶活性无关。暴露于300μM-10mM萘普生24小时会导致细胞活力呈浓度依赖性降低。除了TRPM7外，上述NSAIDs的作用预计也适用于其他对细胞内pH值敏感的离子通道和转运蛋白。
