Cytotoxic and inflammatory potential of a phospholipase A from snake venom.

BACKGROUND

Snake venom phospholipases A (PLAs) have been reported to induce myotoxic, neurotoxic, hemolytic, edematogenic, cytotoxic and proinflammatory effects. This work aimed at the isolation and functional characterization of a PLA isolated from venom, named BJ-PLA-I.

METHODS AND RESULTS

For its purification, three consecutive chromatographic steps were used (Sephacryl S-200, Source 15Q and Mono Q 5/50 GL). BJ-PLA-I showed acidic characteristics, with pI~ 4.4 and molecular mass of 14.2 kDa. Sequencing resulted in 60 amino acid residues that showed high similarity to other PLAs, including 100% identity with BJ-PLA, an Asp49 PLA previously isolated from venom. Being an Asp49 PLA, BJ-PLA-I showed high catalytic activity, and also inhibitory effects on the ADP-induced platelet aggregation. Its inflammatory characterization showed that BJ-PLA-I was able to promote leukocyte migration in mice at different concentrations (5, 10 and 20 μg/mL) and also at different response periods (2, 4 and 24 h), mainly by stimulating neutrophil infiltration. Furthermore, increased levels of total proteins, IL-6, IL-1β and PGE were observed in the inflammatory exudate induced by BJ-PLA-I, while nitric oxide, TNF-α, IL-10 and LTB levels were not significantly altered. This toxin was also evaluated for its cytotoxic potential on normal (PBMC) and tumor cell lines (HL-60 and HepG2). Overall, BJ-PLA-I (2.5-160 μg/mL) promoted low cytotoxicity, with cell viabilities mostly varying between 70 and 80% and significant values obtained for HL-60 and PBMC only at the highest concentrations of the toxin evaluated.

CONCLUSIONS

BJ-PLA-I was characterized as an acidic Asp49 PLA that induces acute local inflammation and low cytotoxicity. These results should contribute to elucidate the action mechanisms of snake venom PLAs.