Whole blood platelet aggregation and coagulation factors in patients with systemic sclerosis

Abstract

It is unclear whether the changes in platelet function which are observed in systemic sclerosis are a primary characteristic of this disease or whether they occur secondary to vascular changes. Whole blood platelet aggregation was studied in 26 patients with systemic sclerosis, normal subjects matched for age, sex and secondary characteristics, 19 patients with Raynaud's disease and 19 patients with systemic lupus erythematosus. Plasma levels of fibrinogen, von Willebrand factor antigen and factor VIII:C were also measured. Systemic sclerosis was associated with a significant (P > 0.001) enhancement of the sensitivity of platelets to collagen. In contrast, significant enhancement of the response to either ADP or adrenaline was not observed. Enhanced sensitivity to collagen was not associated with the presence of either Raynaud's disease or systemic lupus erythematosus. Systemic sclerosis was associated with significantly raised levels of von Willebrand factor antigen and fibrinogen. On an individual patient basis, von Willebrand factor antigen was related to the severity of the disease whereas platelet sensitivity to collagen was not. In conclusion, this study suggests that the enhanced sensitivity to collagen which occurs in systemic sclerosis is due to a primary change in the platelet and that this change can combine with elevated levels of adhesive proteins.

Skin ulcers in systemic sclerosis: Determinants of presence and predictive factors of healing

“…This discrepancy may be due to the different samples used for VEGF detection: in serum, VEGF levels are several-fold higher than in matched plasma samples, owing to VEGF release from activated platelets in SSc patients during blood clotting. 36,37 Higher VEGF plasma levels in SSc patients, mainly in those with larger ulcers, may be explained by a different genetic setting involving the VEGF gene. A recent study of the EULAR Scleroderma and Research (EUSTAR) group demonstrated that there is no association between SSc and some functional VEGF polymorphisms even though, in healthy subjects, selected single-nucleotide polymorphisms in the VEGF gene have been found to be associated with differences in VEGF protein production.…”

Ativação plaquetária na esclerose sistêmica e alternativas metodológicas para sua avaliação

“…Vale ressaltar que a ativação plaquetária na esclerose sistê-mica pode contribuir para a ocorrência de doença arterial oclusiva pela liberação de fatores de crescimento; pode contribuir também para a fibrose tecidual uma vez que produtos plaquetários estimulam a síntese de glicosaminoglicanos, particularmente pelos fibroblastos (46,47) . Os fibroblastos dos pacientes com esclerose sistêmica apresentam anormalidades na membrana plasmática e ligam-se ao colágeno via GPIa/IIa, eletroforeticamente e imunologicamente idêntica à integrina α2/β1, que também regula a ligação do colágeno e laminina com as células endoteliais, queratinócitos e células epiteliais.…”

“…Os fibroblastos dos pacientes com esclerose sistêmica apresentam anormalidades na membrana plasmática e ligam-se ao colágeno via GPIa/IIa, eletroforeticamente e imunologicamente idêntica à integrina α2/β1, que também regula a ligação do colágeno e laminina com as células endoteliais, queratinócitos e células epiteliais. Portanto, aumento na resposta plaquetária ao colágeno na esclerose sistêmica pode refletir uma alteração generalizada na membrana celular, mas se faz necessário uma melhor investigação da expressão da integrina nas membranas celulares, em particular, naquelas observadas na esclerose sistêmica (46,47) .…”

Blood Platelets and Systemic Sclerosis

“…Reduced sensitivity to PGI2 [160] Increased platelet sensitivity to collageninduced aggregation [138]; [157] Increased expression of collagen type 1 receptor [153] Hyperaggregability not found [161] …”

“…Hyperaggregability Spontaneous (in whole blood) In response to agonists [126]; [131]; [154][155][156][157][158] Enhanced adhesion to collagen [159];…”