Induction of mast cell accumulation, histamine release and skin edema by N49 phospholipase A2.
BACKGROUND
It has been recognized that phospholipase A2 (PLA2) is a crucial component of snake venom, which contributes greatly to snake venom induced inflammation in man. However, the mechanisms through which N49 PLA2 provoke inflammation remain unclear. Recently, a N49 PLA2, TM-N49 from Protobothrops mucrosquamatus crude venom was characterized in our laboratory. Since the purification procedure developed is able to supply us with relatively large quantity of highly purified TM-N49, we investigated the ability of TM-N49 in induction of inflammation.


RESULTS
The results showed that TM-N49 provoked a dose dependent increase in microvascular leakage in the skin of rats. The potency of TM-N49 in induction of skin edema appeared similar potency of bradykinin and histamine. Pretreatment of rats with compound 48/80 diminished TM-N49 induced skin reaction and reduced mast cell numbers in rats. Ginkgolide B and cyproheptadine, but not terfenadine and quinacrine, inhibited TM-N49 elicited microvascular leakage when they were co-injected with the stimulus to rat skin. Moreover, TM-N49 was found to induce histamine release from human colon, lung and tonsil mast cells, and both metabolic inhibitors and pertussis toxin were capable of inhibiting TM-N49 elicited histamine release. TM-N49 induced mast cell accumulation in the peritoneum of mice, which was inhibited by co-injection of ginkgolide B, cyproheptadine and terfenadine. Intravenous injection of monoclonal antibodies against CD18, ICAM-1 and CD11a also blocked TM-N49 induced mast cell accumulation.


CONCLUSIONS
TM-N49 is a potent stimulus for skin edema, mast cell activation and accumulation.
Wei
Ji-Fu
JF
Clinical Experiment Center, the First Affiliated Hospital of Nanjing Medical University, Nanjing, PR China. weijifu@hotmail.com
Wei
Xiao-Long
XL
Mo
Ya-Zhen
YZ
He
Shao-Heng
SH
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D019138:Antibodies, Blocking / Q000008:administration & dosage; D040881:CD11a Antigen / Q000276:immunology; D018821:CD18 Antigens / Q000276:immunology; D002199:Capillary Permeability / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects; D003106:Colon / Q000473:pathology; D004487:Edema / Q000097:blood / Q000139:chemically induced / Q000473:pathology*; D046934:Ginkgolides / Q000008:administration & dosage; D054501:Group II Phospholipases A2 / Q000302:isolation & purification / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology; D007783:Lactones / Q000008:administration & dosage; D008168:Lung / Q000473:pathology; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D010537:Peritoneum / Q000187:drug effects / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D030162:Reptilian Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D012867:Skin / Q000187:drug effects / Q000473:pathology*; D012910:Snake Venoms / Q000737:chemistry; D012911:Snakes
D000893:Anti-Inflammatory Agents; D019138:Antibodies, Blocking; D040881:CD11a Antigen; D018821:CD18 Antigens; D046934:Ginkgolides; D007783:Lactones; D030162:Reptilian Proteins; D012910:Snake Venoms; D018799:Intercellular Adhesion Molecule-1; C045856:ginkgolide B; D054501:Group II Phospholipases A2; C510097:TM-N49 protein, Protobothrops mucrosquamatus