Alternative role of platelets in the pathogenesis of haemolytic uraemic syndrome (HUS).

ABREY-RECALDE MJ; AMARAL MM; ALVAREZ R; ALBERTO F; MEJÍAS MP; RAMOS MV; FERNANDEZ-BRANDO RJ; EXENI R; ALCONCHER L; PALERMO MS

Mar del Plata

Congreso; LIX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica y LXII Reunión Científica Anual de la Sociedad Argentina de Inmunología,; 2014

Sociedad Argentina de Inmunología,

Typical HUS is caused by Shiga toxin (Stx)-producing Escherichia coli infections and is characterized by haemolytic anaemia, thrombocytopenia and acute renal failure.  Stx induce endothelial damage. The injured endothelium release vasoactive substances that leads to platelet activation and subsequent adhesión to form the clot.  Platelets contain CD40L stored in alpha granules.  Upon activation, CD40L is exposed at the platelet surface, and cleaved to generate a soluble product that interact with its widely expressed receptor CD40.  Thus, sCD40L induces the release of tissue factor by monocytes and proinflammatory cytokines, as IL-8 and MCP-1 by endothelial cells, leading to prothrombotic and proinflammatory state, that could contribute to HUS pathogenesis. The aim of this work was analyze the platelet activation and its inflammatory function, through the sCD40L release in a HUS context.  Cocultures of human glomerular endothelial cells (E) and platelets (P), were made.  E were culture in medium with or without Stx, 0.1ng/ml (S0.1) y 1 ng/ml (S1).  After 24 h, P were added for 1 h.  sCD40L levels in supernatants were determined by ELISA, endothelial damage by neutral red cytotoxicity assay, and P adhesion to E, by acid-phosphatase assay.  The treatments were: 1:E, 2:E+P, 3:E+S0.1, 4: E+S0.1+P, 5:E+S1, 6:E+S1+P. Results of sCD40L level are expressed in ng/ml(MEAN±SEM): 1= non-detectable (ND), 2=0.051±0,026, 3=ND, 4=0,115±0,059, 5=ND, 6=0.275±0.065. Endothelial damage, as percentage of live cells(MEAN±SEM): 1=100, 2=103±5, 3=89±6, 4=85±4, 5=70±4, 6=72±5.  P adhesion to E, as percentage of adhesion relative to treatment 2(MEAN±SEM): 2=100±5,  4=192±66, 6=346±72.  We conclude that Stx induce an endhotelial damage, that leads to platelet activation and subsequent release of sCD40L. Thus, we describe an alternative platelet role that may contribute to HUS pathogenesis, potentiating the inflammatory response.