Background: Platelets play a fundamental role in myocardial infarction and the pathogenesis of ischemia/reoxygenation (I/R) injuries. They contain matrix metalloproteinases (MMPs) that are involved in arterial thrombosis. The MMP inhibitor doxycycline has been shown to exert protective effects in I/R injuries involving various organs and mechanisms.
Objectives: To explore the influence of doxycycline on platelet activation and MMP-2 activity during I/R.
Material and methods: Platelets isolated from the blood of healthy human volunteers were subjected to chemical I/R conditions. The study included aerobic controls (AERO), I/R platelets and I/R platelets pretreated with doxycycline (I/R+D). The concentration of doxycycline used was standardized to 10 μM. The analysis of platelet activation markers and platelet microvesicles (PMVs) was performed using flow cytometry. Adenosine diphosphate (ADP)-induced and collagen-induced aggregation, as well as MMP-2 activity and its concentration in platelets were evaluated.
Results: Doxycycline decreased the expression of activated glycoprotein IIb/IIIa on platelets (p = 0.043). Additionally, an increased expression of CD63 was observed in buffers containing PMVs after doxycycline administration (p = 0.043). The ADP-dependent aggregation of I/R platelets was significantly lower in comparison to AERO (p = 0.022). Furthermore, there was a stronger tendency of enhanced ADP-dependent aggregation in I/R platelets pretreated with doxycycline compared to platelets that underwent I/R without doxycycline. Higher MMP-2 activity was observed in I/R+D platelets compared to I/R platelets (p < 0.01).
Conclusions: The inhibition of platelet MMP-2 by doxycycline attenuated platelet activation and protected platelets by preserving their aggregation ability.
Keywords: doxycycline; ischemia; metalloproteinases; platelets; reperfusion.