Inhibition of PAF synthesis by stimulated human polymorphonuclear leucocytes with cloricromene, an inhibitor of phospholipase A₂ activation

Abstract

1 A phospholipase A2 (PLA2) represents the key enzyme in the remodelling pathway of plateletactivating factor (PAF) synthesis in human polymorphonuclear (PMN) leucocytes. 2 PLA2 activation is also the rate-limiting step for the release of the arachidonic acid utilized for the synthesis of leukotrienes in stimulated leucocytes; however, it is unknown whether the PLA2s involved in the two biosynthetic pathways are identical. 3 Cloricromene (8-monochloro-3-f-diethylaminoethyl-4-methyl-7-ethoxy-carbonylmethoxy coumarin) is an antithrombotic coumarin derivative which inhibits platelet and leucocyte function and suppresses arachidonic acid liberation by interfering with PLA2 activation. 4 The aim of the present study was to assess whether chloricromene inhibits PAF synthesis by stimulated human polymorphonuclear leucocytes (PMNs).

A protective effect of the synthetic coumarine derivative Cloricromene against DNB-colitis in the rat

“…This compound has been shown to inhibit platelet function in vitro and in vivo (Prosdocimi et al, 1985(Prosdocimi et al, , 1986 and to cause vasodilation in vivo (Aporti et al, 1978). In platelets and neutrophils it reduces arachidonic acid release from membrane phospholipids by interfering with phopholipase A2 activation resulting in an inhibition of platelet-activating-factor synthesis (Ribaldi et al, 1996). Cloricromene reduces neutrophil accumulation and adherence in experimental models of myocardial infarction (Groban et al, 1998) exhibiting an anti-ischaemic effect beyond its anti-platelet activity (Lidbury et al, 1993) and protects rats against endotoxin shock by reducing TNF-a synthesis (Squadrito et al, 1992).…”

PAF in Pulmonary Surfactant Contributes to Neutrophilic Oxidative Stress-Induced Acute Lung Injury of Rats Given LPS Intratracheally

“…Platelet-activating factor (PAF)는 phospholipase A2 (PLA2)의 작용에 의해 생성된 lysophosphatidylcholine이 lysoPAF-acetyltransferase의 작용에 의하여 remodelling의 과 정을 거쳐 생성되는 염증성 분자의 일종이다 [21]. 내독소에 의 해 유도되는 급성호흡곤란증후군(acute respiratory distress syndrome, ARDS)을 포함하는 급성 폐손상(acute lung injury, ALI)에서 PAF는 호중구의 침윤, 산소기의 생성 및 PLA2의 활성화에 중요한 역할을 한다 [16].…”

PAF levels in saliva are regulated by inflammatory cells

“…Each saliva sample was divided into 2 aliquots, 1 of which was immediately centrifuged at 12,000 g for 10min in an Eppendorf microcentrifuge, in order to remove cells and microparticulate material. The non-centrifuged saliva aliquot and the clear supernatant of the centrifuged aliquot (1 ml) were extracted by adding 13.5ml of chloroform/ methanol/ water (1 : 1 : 0.7 v/v) and samples were then processed as described previously ( 14,16).…”

“…The recovered PAF was then resuspended in 1 ml of assay buffer containing sodium azide 0. I%, Tween 0.05%, Na citrate 50 mM; the samples were centrifuged at 12,OOOg for 10 min to remove any debris and then assayed by radioimmunoassay (RIA) (NEN-Du Pont, Boston MA, USA), as described (14,16,17). The cross-reactivity of the antibody used with lyso-PAF, the product of PAFdegradation by acetylhydrolase, was lower than 0.003%, thus excluding any interference from PAF degradation products in the assay (17).…”