Switch of Steady-State to an Accelerated Granulopoiesis in Response to Androctonus australis hector Venom.

Although several studies have shown that scorpion venoms cause a systemic inflammatory response syndrome, little is known about the contribution of the hematopoietic organs. The aim of this study was to investigate the effect of Androctonus australis hector venom on the bone marrow and on local inflammatory mediators, in concordance with the systemic inflammatory reaction elicited in mice. The consequences of a direct interaction of venom with murine bone marrow cells were also assessed by in vitro study. Obtained results showed that the early systemic neutrophilia correlated with a rapid granulocyte mobilization. This response was followed by an accelerated granulopoiesis that was supported by TNF-α and IL-6 signals. In vitro data revealed that the venom exerted a proliferative effect on murine hematopoietic cells and stimulated their differentiation towards granulocyte lineage mainly through cytokine secretion. In conclusion, this study indicated that the bone marrow rapidly exerts its activity in response to the experimental envenomation via the granulopoiesis process and inflammatory mediators in concert with the development of a systemic response. The ability of venom to directly switch steady-state granulopoiesis to an accelerated state in vitro could aggravate the disturbance caused by the venom. Better understanding of the mechanisms involved may lead to the emergence of new targets to avoid cell spreading and accumulation by acting on the very early stage of the systemic inflammatory response.