Innate immunity, hemostasis and matrix remodeling: PTX3 as a link.

Innate immunity is evolutionarily connected with hemostasis. PTX3 is an essential fluid-phase pattern recognition molecule of the innate immune system that acts as a functional ancestor of antibodies. PTX3 by interacting with defense collagens and fibrinogens amplifies effector functions of the innate immune system. At wound sites, PTX3 regulates the injury-induced thrombotic response and promotes wound healing by favoring timely fibrinolysis. Therefore, PTX3 interacts with ancestral domains conserved in innate immunity, hemostasis and extracellular matrix and exerts functions related to both antimicrobial resistance and tissue repair. These findings strengthen the connection between innate immune system and hemostasis, and suggest that recognition of microbes and extracellular matrix are evolutionarily conserved and integrated functions of the innate immune system.