Autoinducer N-(3-oxododecanoyl)-L-homoserine lactone induces calcium and reactive oxygen species-mediated mitochondrial damage and apoptosis in blood platelets

Acylated homoserine lactones (AHL) such as N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C₁₂ HSL) and N-butyryl-L-homoserine lactone (C₄ HSL) are the most common autoinducer molecules in Pseudomonas aeruginosa. These AHL molecules not only regulate the expression of virulence factors but also have been shown to interfere with the host cell and modulate its functions. Recently, we reported that 3-oxo-C₁₂ HSL but not C₄ HSL causes cytosolic Ca²⁺ rise and ROS production in platelets. In this study, we examined the potential of AHLs to induce apoptosis in the human blood platelet. Our result showed that 3-oxo-C₁₂ HSL but not C₄ HSL causes phosphatidylserine (PS) exposure, mitochondrial dysfunction (mitochondrial transmembrane potential loss, and mitochondrial permeability transition pore (mPTP) formation). Besides, 3-oxo-C₁₂ HSL also inhibited thrombin-induced platelet aggregation and clot retraction. The pretreatment of an intracellular calcium chelator BAPTA-AM or ROS inhibitor (DPI) significantly attenuated the 3-oxo-C₁₂ HSL induced apoptotic characters such as PS exposure and mitochondrial dysfunctions. These data, including our previous findings, confirmed that 3-oxo-C₁₂ HSL induced intracellular Ca²⁺ mediated ROS production results in the activation and subsequent induction of apoptotic features in platelets. Our results demonstrated that the 3-oxo-C₁₂ HSL modulates the functions of platelets that may cause severe thrombotic complications in P. aeruginosa infected individuals.