Effect of the cysteine prodrug L-2-oxothiazolidine-4-carboxylic acid on in vivo platelet activation, oxidative stress, and procoagulant responses induced by waterpipe smoke exposure in mice

Introduction: Exposure to waterpipe smoke (WPS) in humans and experimental animals has been reported to cause oxidative stress and thrombotic complications. L-2-Oxothiazolidine-4-carboxylic acid (OTC) is a cysteine prodrug that maintains glutathione (GSH) in tissues. Nevertheless, the possible mitigating effects of OTC on platelet aggregation induced by WPS inhalation, and its underlying mechanisms of action remain unexplored. This is the goal of the present work in BALB/c mice. Methods: Animals were exposed to either WPS or air (control) by inhalation daily for 30 min for 1 month. OTC was given 1 h before each exposure session by gavage at a dose of 80 mg/kg. Results: WPS inhalation increased various markers of platelet aggregation, coagulation, fibrinolysis and endothelial integrity (platelet factor 4, tissue factor, fibrinogen, thrombin-antithrombin complexes, plasminogen activator inhibitor, P-selectin, E-selectin, intercellular adhesion molecule 1 and vascular cell adhesion molecule 1). It also shortened the prothrombin time and partial thromboplastin time and augmented the plasma concentrations of C-reactive protein and triglycerides. All these effects were attenuated by OTC treatment. Likewise, OTC administration significantly mitigated platelet aggregation in vivo. Platelets isolated from mice exposed to WPS showed high levels of markers of oxidative and nitrosative stress, calcium, annexin V and calpain. The latter effects were significantly alleviated by OTC treatment. Discussion: Our data show that OTC administration significantly mitigated WPS-induced in vivo endothelial injury and thrombotic events, as well as platelet oxidative stress and apoptosis. This finding provides evidence on the mechanisms of toxicity of WPS on platelet physiology, and the alleviative action of OTC.