SB 203347, an inhibitor of 14 kDa phospholipase A2, alters human neutrophil arachidonic acid release and metabolism and prolongs survival in murine endotoxin shock.

Abstract

Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 fatty acyl group [predominantly arachidonic acid (AA)] of membrane phospholipids, the products of which are further metabolized, forming a variety of eicosanoids and/or platelet-activating factor. PLA2 activity is significantly enhanced during inflammation and therefore offers an intriguing target in designing anti-inflammatory drugs. SB 203347 (2-[2-[3,5-bis (trifluoromethyl) sulfonamido]-4- trifluoromethylphenoxy] benzoic acid) potently inhibits rh type II 14 kDa PLA2 (IC50 = 0.5 microM) but exhibits a 40-fold weaker inhibition of 85 kDa PLA2 (IC50 = 20 microM) using [3H]-AA E. coli as substrate. A specific interaction with rh type II 14 kDa PLA2 was confirmed both by observing the pH dependence of its IC50 and by demonstrating linear inhibition in a "scooting" kinetic model using radiolabeled phospholipid reporter substrate in a 1,2-dimyristoyl phosphatidylmethanol vesicle. Before evaluating the effect of SB 203347 on AA metabolism in intact human neutrophil, we showed that it fully inhibits PLA2 activity in acid extracted-intact human neutrophil homogenate (IC50 = 4.7 microM). SB 203347 inhibited A23187-induced intact human neutrophil AA mass release in a concentration-dependent manner (IC50 = 1 microM), which coincided with reductions in the biosynthesis of platelet-activating factor (IC50 = 1.5 microM) and leukotriene B4 (IC50 = 2.3 microM). Finally, SB 203347 prolonged survival in a mouse model of endotoxin shock delivered i.p. Taken together, the data support a role of cellular 14 kDa PLA2 in the formation of AA-derived proinflammatory lipid mediator.(ABSTRACT TRUNCATED AT 250 WORDS)

• Authors: L A Marshall, R H Hall, J D Winkler, A Badger, B Bolognese, A Roshak, P L Flamberg, C M Sung, M Chabot-Fletcher, J L Adams
• Journal: The Journal of pharmacology and experimental therapeutics (J Pharmacol Exp Ther) Vol. 274 Issue 3 Pg. 1254-62 (Sep 1995) ISSN: 0022-3565 [Print] United States
• PMID: 7562496 (Publication Type: Journal Article)

Chemical References

• Enzyme Inhibitors
• Lipopolysaccharides
• Platelet Activating Factor
• SB 203347
• Sulfonamides
• Leukotriene B4
• Arachidonic Acid
• Phospholipases A
• Phospholipases A2
• 1-Alkyl-2-acetylglycerophosphocholine Esterase

Topics

• 1-Alkyl-2-acetylglycerophosphocholine Esterase
• Animals
• Arachidonic Acid (metabolism)
• Cell-Free System
• Disease Models, Animal
• Enzyme Inhibitors (pharmacology)
• Humans
• Leukotriene B4 (metabolism)
• Lipopolysaccharides (toxicity)
• Male
• Mice
• Mice, Inbred C57BL
• Neutrophils (drug effects, enzymology, metabolism)
• Phospholipases A (antagonists & inhibitors)
• Phospholipases A2
• Platelet Activating Factor (biosynthesis)
• Shock, Septic (chemically induced, metabolism, mortality)
• Sulfonamides (pharmacology)
• Survivors