IgG-complex stimulated platelets: a source of sCD40L and RANTES in initiation of inflammatory cascade.

Platelets are a crucial element in maintenance of hemostasis. Other functions attributable to platelets are now being appreciated such as their role in inflammatory reactions and vascular remodeling. Platelets have been reported to bind immunological stimuli like IgG-complexes and the understanding that platelets may participate in immunological reactions has been speculated for nearly 50years. In previous observations, we demonstrated that platelets could bind and internalize aggregated IgG-complexes without inducing platelet aggregation or granule release. To characterize this observation further, we tested the hypothesis that aggregated IgG-complexes do not activate platelets. To this end, platelets were stimulated with IgG-complexes or thrombin as a positive control and evaluated for activation by aggregation, expression of surface markers and production of cytokines. Activation with thrombin resulted in aggregation, expression of high levels of CD62P (P-selectin) expression and activation of the fibrinogen receptor, alpha(IIb)beta(3). Furthermore, stimulation with thrombin resulted in significant amounts of sCD40L (CD154) and RANTES (CCL5). However, platelets stimulated with IgG-complexes resulted in no aggregation and low levels of CD62P expression. Surprisingly, platelets stimulated with aggregated IgG-complexes released similar amounts of sCD40L and RANTES as platelets activated by thrombin. These data suggest that platelets are capable of secreting inflammatory molecules in response to IgG-complexes.

[The study of relationship between platelet function and thrombus in patients with essential thrombocythaemia].

OBJECTIVE: To observe the influence of the plasma thromboxane B2 (TXB2), 6-keto-PGF1alpha, CD62P and PAC-1 and Thrombus in patients with primary thrombocytosis (ET). To observe the effect of sodium ozagrel to prevent and treat thrombosis in patients with ET. METHODS: The subjects including 48 patients with ET. All patients were measured the plasma TXB2, 6-keto-PGF1alpha, CD62P and PAC-1 before and after treatment with or without sodium ozagrel. RESULTS: The plasma levels of CD62P, PAC-1, TXB2, 6-keto-PGF1alpha and TXA2/PGI2 in the patients with ET were significantly higher than the normal people (P < 0.01). The levels of CD62P, PAC-1, TXB2, TXB2/6-keto-PGF1alpha in patients with treatment of sodium ozagrel were higher than patients without treatment of sodium ozagrel (P < 0.01). The plasma levels of CD62P, PAC-1 and TXA2/PGI2 in patients with treatment of sodium ozagrel and that in normal people had no significant distinction (P < 0.01). All the index of conventional therapy group were higher than normal people (P < 0.01) but had no significant distinction with the patients before conventional treating. The incidence of thrombus in patients treated with sodium ozagrel was lower than patients treated without sodium ozagrel (P < 0.05). CONCLUSION: With the treatment of sodium ozagrel in patients with ET, the CD62P, PAC-1, TXB2 and TXA2/PGI2 of plasma could be decreased. And the incidence of thrombus was decreased.

Endothelial cell activation by IL-1beta in the presence of fibrinogen requires alphavbeta3.

OBJECTIVE: The purpose of this study was to investigate the receptor requirements for enhanced IL-1beta-induced secretion of nitric oxide (NO) by endothelial cells (ECs) in the presence of fibrinogen. METHODS AND RESULTS: ECs were exposed to IL-1beta with or without fibrinogen and NO was measured as nitrite. NO production by EC exposed to fibrinogen (0.3+/-0.1 micromol/L) was comparable concentration to control (0.2+/-0.1 micromol/L), but IL-1beta significantly increased NO production (0.8+/-0.1 micromol/L), and the combination of both fibrinogen and IL-1beta resulted in a further increase to 2.2+/-0.2 micromol/L (P<0.002). 7E3 or LM609, antibodies to alphavbeta3, inhibited NO production stimulated by fibrinogen-bound IL-1beta to 0.2+/-0.1 micromol/L (P<0.001) or 0.2+/-0.03 micromol/L (P<0.0001), respectively. These levels were comparable to control and significantly less than with IL-1beta (P<0.002). EC or fibroblasts exposed to both fibrinogen and IL-1beta, but not vitronectin and IL-1beta, demonstrated positive Western blotting for alphavbeta3 after immunopurification with anti- IL-1R, indicating specific association between alphavbeta3 and IL-1R. Dual immunofluorescence also revealed colocalization of alphavbeta3 and IL-1R only when the cells were exposed to both fibrinogen and IL-1beta. CONCLUSIONS: The enhanced NO production by ECs in the presence of fibrinogen-bound IL-1beta requires the coordinated effects of colocalized alphavbeta3 and IL-1R.