Hydrogen sulphide (H2S) inhibits human platelet activation through an inside-out integrin aIIbb3 signaling pathway

BERMEJO E; SAENZ DA; ALBERTO MF; LAZZARI MA; ROSENSTEIN RE

Kyoto

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 modulator which exhibits beneficial effects on the cardiovascular system.Objective: Examine the effects of H2S on several human platelet parameters.Methods: Tests were performed using platelet rich plasma or washed platelets (WP; 300 x109 plat/L). Sodium hydrogen sulfide (NaHS) was used as H2S donor. Samples were preincubated with buffer or H2S (10 mM) at 37 ºC for 2 min, before adding agonists. The following parameters were assessed: platelet aggregation, ATP release, expression of glycoprotein (CD41, CD61) and activation markers (CD62, CD63, PAC1), fibrinogen binding (B-Fg) and Ca+2influx (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 lM ADP, 2 lg/mL Col, 1 lM U46619, 10 mM TRAP and 1 lM 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)**; PAC1 (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 lM ADP was inhibited in the presence of H2S, whereas CD41/61 expression in resting platelet and Ca+2influx 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 significantinhibition on aIIbb3 expression and B-Fg post stimulus provoked by H2S, support the participation of an inside-out pathway in which CalDAG-GEFI/Rap1 could be involved. Thus, H2S may constitute a novel target for antithrombotic drug development.