Lonomia obliqua venom activity upon extracellular matrix

Abstract

Lonomia obliqua is a medically important caterpillar endemic in South Brazil. Contact with theis caterpillar’s bristles causes an envenomation syndrome characterized by ecchymosis and hemorrhage. The Lonomia obliqua bristle extract (LOBE) is mainly composed by highly active proteases known to interfere with the hemostatic system of the victims. Although the effects of the venom enzymes upon blood coagulation and platelet aggregation is well characterized, it is possible that LOBE might also affect the environment surrounding small blood vessels, favoring hemorrhage and impairing wound healing. In this work we evaluated the proteolytic activity of LOBE upon extracellular matrix (ECM) components. Degradation of extracellular matrix proteins was performed by in vitro digestion of purified proteins (collagen, laminin, fibronectin), and matrigel and fragments were analyzed by SDS-PAGE. Additionally, in vivo ECM organization of envenomed rat skin was investigated by immunohistochemistry and hystochemistry. Fibroblast cell migration and wound healing was evaluated by the cell scratch assay. LOBE was able to degrade all tested ECM substrates in a time-dependent way. It was also observed impairment on fibroblast migratory behavior. Analysis of envenomed skin showed an increase on inflammatory cells in the connective tissue surrounding the local of LOBE injection, which was accompanied by changes on collagen organization and degradation of laminin on blood vessel basement membrane. In conclusion, Lonomia obliqua bristle extract has a proteolytic activity on extracellular matrix proteins, which might play a role on local and systemic hemorrhage and the appearance of ecchymosis.