The pathological alterations induced by
neuwiedase, a 22 kDa class P-I
metalloproteinase from the
venom of the South American pit viper Bothrops neuwiedi, were studied in mice.
Neuwiedase was devoid of hemorrhagic activity when tested in the skin up to a dose of 200 microgram, and also after
intramuscular injection in the gastrocnemius. However, it induced
bleeding when applied onto the mouse cremaster muscle in intravital microscopy experiments, and caused pulmonary
hemorrhage when injected intravenously at doses higher than 5 microgram/g. Median lethal dose (LD(50)) by the intravenous route was 5 microgram/g, whereas LD(50) of crude
venom was 0.47 microgram/g. After
intramuscular injection,
neuwiedase induced a mild myotoxic effect, evidenced histologically and by the increment in plasma
creatine kinase activity, but it was devoid of hemorrhagic and thrombotic effects. In contrast, crude B. neuwiedi
venom induced prominent
hemorrhage and myonecrosis in gastrocnemius muscle. Both
venom and
neuwiedase induced an inflammatory reaction in muscle tissue characterized by abundant polymorphonuclear leukocytes. Moreover, a conspicuous
edema developed in the foot pad after
subcutaneous injection of
neuwiedase. Anti-
neuwiedase antibodies produced in rabbits were effective in the neutralization of hemorrhagic activity of crude
venom, evidencing immunological cross-reactivity between
neuwiedase and other hemorrhagic
metalloproteinases present in the
venom, and suggesting that
metalloproteinases devoid of, or having low, hemorrhagic activity could be good immunogens to generate
antibodies effective against high molecular mass metalloproteinasas having potent hemorrhagic activity. It is concluded that
neuwiedase, despite its lack of hemorrhagic effect when injected in the gastrocnemius muscle, contributes to local tissue damage by inducing
edema, inflammatory infiltrate and mild
myotoxicity, and by degrading extracellular matrix components. In addition, large doses of
neuwiedase may contribute to pulmonary
bleeding