Aspectos da lesão tecidual local e da regeneração induzidas pela BnSP-7, uma miotoxina isolada da peçonha da serpente Bothrops pauloensis: um estudo da liberação de citocinas pró-inflamatórias e da expressão de metaloproteases de matriz (MMP-9 e MMP-2)

Abstract

Envenomations caused by Bothrops snake venoms are characterized by prominent local tissue damage due to myonecrosis, hemorrhage and edema. The acute muscle damage observed in the envenoming can be due the action of different toxins present in the venom, between them, the myotoxic phospholipases A2 (PLA2) show an important role. In the present study, the progression of local tissue damage and inflammation induced by BnSP-7, a myotoxin isolated from Bothrops pauloensis snake venom was evaluated. We further investigated the MMPs expression (MMP-2 and MMP-9) during process of degeneration and regeneration of the gastrocnemius skeletal muscle. Local tissue damages were characterized by edema, necrosis and inflammation evaluated until 24 h after inoculation of BnSP-7. The regeneration of myofibers, analyzed by light microscopy, was observed from 72 hours to 2 weeks after inoculation of toxin. The expression of MMP-9 occurred at the same times intervals of regenerating muscle, suggesting that this MMP is involved with the regeneration process. MMP-2 was expressed at all times tested. The IL-8, IL-6, IL-1 β and TNF-α cytokines levels were analyzed on mice gastrocnemius muscle and MPAC (murine peritoneal adherent cells) after BnSP-7, BnSP-7 modified with BPB and Bothrops pauloensis crude venom inoculation. The cytokines released in higher levels by mice gastrocnemius muscle and MPAC were IL-1β and IL-8, respectively. The release of TNF-α wasn t significative in both models. The results showed also that the modification of BnSP-7 with BPB decreased the release of IL-8, IL-6 and IL-1 β when compared to native BnSP-7. We have demonstrated that BnSP-7 induces an increase in edema, release of CK, cytokines (IL-6, IL-8, IL-1-1β) and expression of MMP-9. This way, this myotoxin can be acting as pro-inflammatory incentives, inducing cytokine production and liberation from the inflammatory and satellite cells, that present important role in inflammatory process and, consequently, in the evolution of local tissue damage and regeneration.