Photobiomodulation of local alterations induced by BthTX-I, a phospholipase A2 myotoxin from Bothrops jararacussu snake venom: In vivo and in vitro evaluation

Clinical effects of combined red and infrared wavelengths in the treatment of local injuries caused by Bothrops leucurus snake venom

AIM

to evaluate the effects of visible and invisible wavelengths, individually and combined, on local edematogenic activity, serum and muscle enzymes, and clinical response in mice inoculated with B. leucurus snake venom.

METHODS

112 male mice were inoculated with diluted B. leucurus snake venom in the right gastrocnemius muscle, the same volume of saline solution was applied in the contralateral muscle. The animals were divided into four groups, one control and three treated with: 1) red laser (λ = 660 nm), 2) infrared laser (λ = 808 nm) and 3) red laser (λ = 660 nm) + infrared (λ = 808 nm). Each group was subdivided into four subgroups, according to the duration of treatment application (applications every 24 h over evaluation times of up to 144 h). A diode laser was used (0.1 W, CW, 1J/point, DE: 10 J/cm²).

RESULTS

the treatments prevented the loss of the proprioception reflex, accelerated the reestablishment of the damaged area, and reduced claudication, local hemorrhage, and edematogenic activity caused by bothropic venom. Both wavelengths reduced serum concentrations of creatine kinase (CK) and aspartate aminotransferase (AST) and increased muscle concentration of CK. The combined wavelengths caused a significant reduction in serum enzyme concentrations and a better clinical response when compared to the isolated treatments.

CONCLUSION

Laser photobiomodulation proved to be effective in the treatment of the disorders evaluated and the interaction between red and infrared wavelengths potentiated the therapy effects.

Lys49 myotoxins, secreted phospholipase A2-like proteins of viperid venoms: A comprehensive review

Muscle necrosis is a potential clinical complication of snakebite envenomings, which in severe cases can lead to functional or physical sequelae such as disability or amputation. Snake venom proteins with the ability to directly damage skeletal muscle fibers are collectively referred to as myotoxins, and include three main types: cytolysins of the "three-finger toxin" protein family expressed in many elapid venoms, the so-called "small" myotoxins found in a number of rattlesnake venoms, and the widespread secreted phospholipase A₂ (sPLA₂) molecules. Among the latter, protein variants that conserve the sPLA₂ structure, but lack such enzymatic activity, have been increasingly found in the venoms of many viperid species. Intriguingly, these sPLA₂-like proteins are able to induce muscle necrosis by a mechanism independent of phospholipid hydrolysis. They are commonly referred to as "Lys49 myotoxins" since they most often present, among other substitutions, the replacement of the otherwise invariant residue Asp49 of sPLA₂s by Lys. This work comprehensively reviews the historical developments and current knowledge towards deciphering the mechanism of action of Lys49 sPLA₂-like myotoxins, and points out main gaps to be filled for a better understanding of these multifaceted snake venom proteins, to hopefully lead to improved treatments for snakebites.

Dynamics of action of a Lys-49 and an Asp-49 PLA2s on inflammasome NLRP3 activation in murine macrophages

Phospholipases A₂ (PLA₂s) are proteins found in snake venoms with hemolytic, anticoagulant, myotoxic, edematogenic, bactericidal and inflammatory actions. In Bothrops jararacussu snake venom were isolated a Lys49-PLA₂ (BthTX-I) and an Asp49-PLA₂ (BthTX-II) with myotoxic and inflammatory actions. Both PLA₂s can activate the NLRP3 inflammasome, an intracytoplasmic platform that recognizes molecules released when tissue is damaged liberating IL-1β that contributes to the inflammatory response observed in envenoming. The dynamic of action of BthTX-I and BthTX-II in both thioglycollate (TG)-elicited macrophages and C2C12 myoblasts and the involvement of EP1 and EP2 receptors, and PGE₂ in NLRP3 inflammasome activation were evaluated. Both toxins induced PGE₂ liberation and inflammasome components (NLRP3, Caspase-1, ASC, IL-1β, and IL18), IL-6, P2X7, COX-1, COX-2, EP2 and EP4 gene expression in TG-elicited macrophages but not in C2C12 myoblasts. EP2 (PF04418948) and EP4 (GW627368X) inhibitors abolished this effect. Both PLA₂s also induced NLRP3 inflammasome protein expression that was abolished with the inhibitors used. Immunofluorescence and IL-1β assays confirmed the NLRP3 activation in TG-elicited macrophages with the participation of both EP2 and EP4 receptors confirming their involvement in this effect. All in all, BthTX-I and BthTX-II activate macrophages and induce the NLRP3 inflammasome complex activation with the participation of the PGE₂ via COX pathway and EP2 and EP4, both PGE₂ receptors, contributing to the local inflammatory effects observed in envenoming.

Photobiomodulation reduces cell death and cytokine production in C2C12 cells exposed to Bothrops venoms

Snakebites caused by the genus Bothrops are often associated with severe and complex local manifestations such as edema, pain, hemorrhage, and myonecrosis. Conventional treatment minimizes the systemic effects of venom; however, their local action is not neutralized. The purpose of this study was to evaluate the effect of photobiomodulation (PBM) on C2C12 muscle cells exposed to B. jararaca, B. jararacussu, and B. moojeni venoms on events involved in cell death and the release of inflammatory mediators. Cells were exposed to venoms and immediately irradiated with low-level laser (LLL) application in continuous wave at the wavelength of 660 nm, energy density of 4.4 J/cm², power of 10 mW, area of 0.045 cm², and time of 20 s. Cell integrity was analyzed by phase contrast microscope and cell death was performed by flow cytometry. In addition, interleukin IL1-β, IL-6, and IL-10 levels were measured in the supernatant. Our results showed that the application of PBM increases cell viability and decreases cell death by apoptosis and necrosis. Moreover, the release of pro-inflammatory interleukins was also reduced. The data reported here indicate that PBM resulted in cytoprotection on myoblast C2C12 cells after venom exposure. This protection involves the modulation of cell death mechanism and decreased pro-inflammatory cytokine release.