Hydrogen sulphide (H2S) inhibits human platelet activation through an inside-out integrin ƒ¿IIbƒÀ3 signaling pathway.

BERMEJO, EMILSE; SAENZ, DANIEL; ALBERTO, FABIANA; LAZZARI, MARÍA; ROSENSTEIN, RUTH

Kyoto, Japon

Congreso; XIII Congress of the International Society on Thrombosis and Haemostasis (ISTH); 2011

International Society on Thrombosis and Haemostasis (ISTH)

Hydrogen sulphide (H2S) is emerging as an important endogenous modulator which exhibits beneficial effects on the cardiovascular system, without producing toxic metabolites.Objective: To examine the effects of H2S on several human platelet parameters.Methods:Tests were performed using platelet rich plasma (PRP) or washed platelets (WP) (300 × 109 plat/l). Sodium hydrogen sulfide (NaHS) was used as H2S donor. Samples were preincubated with buffer or H2S (10 mM) at 37°C for 2 min, before adding several agonists. In resting and activated platelets, the following parameters were assessed: platelet aggregation, ATP release, expression of glycoprotein (CD41, CD61) and activation markers (CD62, CD63, PAC-1), fibrinogen binding (B-Fg) and Ca2+ influx (by flow cytometry using mean fluorescence intensities). Student’s t-test: * = P< 0.05), ** = P < 0.01, control vs. H2S.  Results:H2S significantly inhibited platelet aggregation and ATP release (P< 0.01) induced by 2.5 μM ADP, 2 μg/ml Col, 1 μM U46619, 10 mΜ TRAP and 1μM A23187 but no by 200 nM PMA or 3 mM DTT. The expression of CD62 (29±2 vs. 8±2)**,CD63 (19±1 vs. 9±2)**; PAC-1(18±4 vs. 8±3)**, B-Fg (126±12 vs. 15±5)** and CD41(178±8 vs. 110±5)*, CD61 (253±10 vs. 168±3)* induced by 20 μM ADP was inhibited in the presence of H2S, whereas CD41/61 expression in resting platelet and Ca2+ influx in WP stimulated by A23187 were unaffected. Conclusion: Resting platelet aIIbB3 was unchanged in the presence of H2S, as shown by CD41/61 levels, and aggregation induced by DTT, whereas secondary platelet aggregation induced by several agonists (except PMA), ATP release, and activation markers, were significantly inhibited by H2S. These results, together with a significant inhibition on αIIbβ3 expression and B-Fg post stimulus provoked by H2S, support the participation of an inside-out pathway in which CalDAG-GEFI/Rap 1 could be involved. Thus, H2S may constitute a novel target for antithrombotic drug development.