Biphasic Hormetic-like Effect of Lebecetin, a C-type Lectin of Snake Venom, on Formalin-induced Inflammation in Mice.

Background: Integrins, important extracellular matrix (ECM) receptor proteins, are affected by inflammation and can participate in the maintenance of many painful conditions. Although they are ubiquitous and changeable across all cell types, the roles of these cell adhesion molecules in pathological pain have not been fully explored.

Objective: We evaluated the effects of the subcutaneous injection of lebecetin, a C-type lectin isolated from snake venom, previously reported to inhibit α5β1 and αv integrin activity, on different components of inflammation induced by the formalin administration in the hind paw of mice.

Methods: The formalin-induced nocifensive behavior, edema, and histopathological changes in the hind paw associated with cytokine, iNOS, and COX2 expression, nociceptive-specific neuron activity, and microglial activation analysis in the spinal cord were evaluated in mice receiving vehicle or lebecetin pretreatment.

Results: Lebecetin inhibited the nocifensive responses in the formalin test, related edema, and cell infiltration in the injected paw in a biphasic, hormetic-like, and dose-dependent way. According to that hormetic trend, a reduction in pro-inflammatory cytokines IL-6, IL-8, and TNF-alpha and upregulation of the anti-inflammatory cytokine IL-10 in the spinal cord were found with the lowest doses of lebecetin. Moreover, COX2 and iNOS expression in serum and spinal cord followed the same biphasic pattern of cytokines. Finally, nociceptive neurons sensitization and activated microglia were normalized in the dorsal horn of the spinal cord by lebecetin.

Conclusion: These findings implicate specific roles of integrins in inflammation and tonic pain, as well as in the related central nervous system sequelae.