Background: Snake venom phospholipases A2 (PLA2s) have hemolytic, anticoagulant, myotoxic, oedematogenic, bactericidal, and inflammatory actions. BthTX-I, a Lys49-PLA2 isolated from Bothrops jararacussu venom, is an example of Lys49-PLA2 that presents such actions. NLRP3 is a cytosolic receptor from the NLR family responsible for inflammasome activation via caspase-1 activation and IL-1β liberation. The study of NLRs that recognize tissue damage and activate the inflammasome is relevant in envenomation.
Methods: Male mice (18-20 g) received an intramuscular injection of BthTX-I or sterile saline. The serum was collected for creatine-kinase (CK), lactate dehydrogenase (LDH), and interleukin-1β (IL-1β) assays, and muscle was removed for inflammasome activation immunoblotting and qRT-PCR expression for nucleotide and oligomerization domain, leucine-rich repeat-containing protein family, pyrin-containing domain 3 receptor (NLRP3) inflammasome components.
Results: BthTX-I-induced inflammation and myonecrosis, shown by intravital microscope, and LDH and CK release, respectively. Mouse treatment with A438079, a P2X7 receptor antagonist, did not modify these effects. BthTX-I induced inflammasome activation in muscle, but P2X7R participation in this effect was not observed.
Conclusion: Together, the results showed for the first time that BthTX-I in gastrocnemius muscle induces inflammation and consequently, inflammasome activation via NLRP3 with caspase-1 activation and IL-1β liberation.
Keywords: Lys49-PLA2; inflammasome; muscle; snake venom.