M Type 1 and 3 Group A Streptococci Stimulate Tissue Factor-Mediated Procoagulant Activity in Human Monocytes and Endothelial Cells

Abstract

Streptococcal toxic shock syndrome (StrepTSS) is an invasive infection characterized by marked coagulopathy, multiple organ failure, and rapid tissue destruction and is strongly associated with M type 1 and 3 group A streptococci (GAS). Initiation of the coagulation cascade with formation of microvascular thrombi contributes to multiple organ failure in human cases of gram-negative bacteremia; however, little is known regarding the mechanism of coagulopathy in StrepTSS. Thus, we investigated the abilities of several strains of M type 1 and 3 GAS isolated from human cases of StrepTSS to stimulate production of tissue factor (TF), the principal initiator of coagulation in vivo. Washed, killed M type 1 and 3 GAS, but not M type 6 GAS, elicited high-level TF-mediated procoagulant activity from both isolated human monocytes and cultured human umbilical vein endothelial cells. M type 1 GAS consistently elicited higher levels of TF from monocytes than did M type 3 GAS. GAS-induced TF synthesis in monocytes did not correlate with production of tumor necrosis factor alpha or interleukin-8. Conversely, M type 3 GAS were consistently more potent than M type 1 GAS in stimulating endothelial cell TF synthesis. These results demonstrate that (i) M type 1 and 3 strains of GAS are potent inducers of TF synthesis, (ii) GAS-induced TF synthesis is not simply an epiphenomenon of cytokine generation, and (iii) induction of TF in endothelial cells and monocytes may be M type specific. In total, these findings suggest that a novel interaction between GAS and host cells contributes to the observed coagulopathy in StrepTSS.

Invasion of Endothelial Cells by Tissue-invasive M3 Type Group A Streptococci Requires Src Kinase and Activation of Rac1 by a Phosphatidylinositol 3-Kinase-independent Mechanism

“…Interestingly, differences between these serotypes and their capacity to interact with endothelial cells have been observed. Bryant and co-workers (33) found that M3 GAS are able to specifically interact with endothelial cells, resulting in a tissue factor-mediated procoagulant response by these cells. Furthermore, it was shown that M3 GAS were more efficiently internalized by HUVEC compared with an M2 serotype strain (7).…”

Biology and Pathogenesis of Thrombosis and Procoagulant Activity in Invasive Infections Caused by Group A Streptococci andClostridium perfringens

“…Interestingly, GAS appeared to have an M-type-specific predilection for the TF-producing cells they stimulated. Specifically, M type 3 GAS elicited high levels of TF from endothelial cells but not monocytes, whereas with M type 1 strains, the converse was observed (21). This disparity existed although both M types elicited high levels of TNF-␣ and IL-8 from cultured monocytes (21) and enhanced leukocyte adherence molecule expression in endothelial cells (my unpublished observations).…”

“…Our recent investigations of this latter hypothesis demonstrated that killed, washed M type 1 and 3 strains of GAS isolated from patients with invasive infection stimulated the in vitro production of TF (21). Interestingly, GAS appeared to have an M-type-specific predilection for the TF-producing cells they stimulated.…”

Disease Manifestations and Pathogenic Mechanisms of Group A Streptococcus

“…Serotype-dependent activation of the extrinsic pathway of coagulation has been demonstrated in vitro, with heat-killed serotype M1 and M3, but not serotype M6, GAS strains triggering tissue factor synthesis on isolated human monocytes and cultured human umbilical vein endothelial cells, resulting in subsequent induction of procoagulant activity (373,379). Unlike the activation of the intrinsic pathway, which occurs at the cell surface, the activation of the extrinsic pathway is thought to occur via the interaction of the M protein with TLR2 following the release of M protein from the bacterial cell wall by bacterial or host-derived proteases (380)(381)(382).…”

“…Transgenic mice lacking clotting factor V, deficient for thrombin generation, or lacking fibrinogen are more susceptible to invasive disease following subcutaneous challenge with GAS (372), highlighting the protective effect of proper coagulation in GAS infection. However, vascular thrombosis can promote hypoxia-induced tissue damage in necrotizing fasciitis (373). GAS activates the clotting cascade via both the intrinsic (contact activation) and extrinsic (tissue factor) pathways.…”