Cp40-mediated complement C3 inhibition dampens inflammasome activation and inflammatory mediators storm induced by Bitis arietans venom.

The complement system plays a crucial role in various pathophysiological conditions, including snake envenomation. In this study, we investigated the effects of Bitis arietans venom on the complement system using an ex vivo human whole blood model. Our findings demonstrate that B. arietans venom was able to activate the complement system, leading to a significant increase in the production of anaphylatoxins (C3a/C3a-desArg, C5a/C5a-desArg) and the soluble Terminal Complement Complex (sTCC). Inhibition of the C3 component by Cp40, a C3-C3b inhibitor, resulted in the reduction of C3a/C3a-desArg, C5a/C5a-desArg, and sTCC levels to baseline in venom-stimulated samples. Furthermore, treatment with Cp40 promoted a substantial decrease in the production of pro-inflammatory mediators, such as Prostaglandin E₂ (PGE₂), IL-8/CXCL8, MCP-1/CCL2, and MIG/CXCL9. To further elucidate the molecular mechanisms, we utilized the THP-1 cell line differentiated into M0 macrophages. Incubation of these macrophages with human plasma, from the human whole blood treated with B. arietans venom, resulted in the expression of the NLRP3 inflammasome and the production of IL-8 and IL-1β. Importantly, Cp40 was able to diminish the production of these cytokines, as well as the levels of ASC and caspase-1 proteins. In conclusion, our results indicate that the inhibition of the complement by Cp40 at C3/C3b level can modulate the inflammatory response and inflammasome activation induced by B. arietans venom. These findings suggest that complement inhibition may be a promising therapeutic approach for managing the inflammatory complications associated with this snake envenomation.