ALPHA-TOXIN FROM CLOSTRIDIUM-PERFRINGENS INDUCES PROINFLAMMATORY CHANGES IN ENDOTHELIAL-CELLS

Alpha toxin from Clostridium perfringens type A, a phospholipase C, ha s been implicated in many of the localized and systemic features of ga s gangrene. We demonstrated that human endothelial cells synthesize tw o vasoactive lipids, platelet-activating factor (PAF) and prostacyclin , in response to alpha toxin treatment, The stimulated synthesis of PA F required the enzymatic activity of the toxin and subsequent protein kinase C activation. Alpha toxin-treated endothelial cells accumulated the products of the phospholipase C reaction, diacylglycerol and cera mide, and exhibited a decrease in the enzymatic precursors phosphatidy lcholine and sphingomyelin. Furthermore, the temporal accumulation of PAF depended on the concentration of the toxin in the overlying medium and was blocked in the presence of a neutralizing antibody. The cultu red endothelial cells also exhibited enhanced neutrophil adhesion in r esponse to alpha toxin which was mediated through the PAF receptor and P-selectin. P-selectin expression by endothelial cells and extravascu lar neutrophil accumulation were also observed in tissue sections from alpha toxin-injected Sprague-Dawley rats. These endothelial cell-medi ated processes are important in maintaining vascular homeostasis and, when activated in a dysregulated manner by C. perfringens alpha toxin, may contribute to localized and systemic manifestations of gas gangre ne including enhanced vascular permeability, localized neutrophil accu mulation, and myocardial dysfunction.