Cytosolic phospholipase A2 is responsible for prostaglandin E2 and leukotriene B4 formation in phagocyte-like PLB-985 cells: studies of differentiated cPLA2-deficient PLB-985 cells

Abstract

Our previously established model of cytosolic phospholipase A(2) (cPLA(2))-deficient, differentiated PLB-985 cells (PLB-D cells) was used to determine the physiological role of cPLA(2) in eicosanoid production. Parent PLB-985 (PLB) cells and PLB-D cells were differentiated toward the monocyte or granulocyte lineages using 5 x 10(-)(8) M 1,25 dihydroxyvitamin D(3) or 1.25% dimethyl sulfoxide, respectively. Parent monocyte- or granulocyte-like PLB cells released prostaglandin E(2) (PGE(2)) when stimulated by ionomycin, A23187, opsonized zymosan, phorbol 12-myristate 13-acetate, or formyl-Met-Leu-Phe (fMLP), and monocyte- or granulocyte-like PLB-D cells did not release PGE(2) with any of the agonists. The kinetics of cPLA(2) translocation to nuclear fractions in monocyte-like PLB cells stimulated with fMLP or ionomycin was in correlation with the kinetics of PGE(2) production. Granulocyte-like PLB cells, but not granulocyte-like PLB-D cells, secreted leukotriene B(4) (LTB(4)) after stimulation with ionomycin or A23187. Preincubation of monocyte-like parent PLB cells with 100 ng/ml lipopolysaccharide (LPS) for 16 h enhanced stimulated PGE(2) production, which is in correlation with the increased levels of cPLA(2) detected in these cells. LPS preincubation was less potent in increasing PGE(2) and LTB(4) secretion and did not affect cPLA(2) expression in granulocyte-like PLB cells, which may be a result of their lower levels of surface LPS receptor expression. LPS had no effect on monocyte- or granulocyte-like PLB-D cells. The lack of eicosanoid formation in stimulated, differentiated cPLA(2)-deficient PLB cells indicates that cPLA(2) contributes to stimulated eicosanoid formation in monocyte- and granulocyte-like PLB cells.

Endothelial ICAM-1 Protein Induction Is Regulated by Cytosolic Phospholipase A2α via Both NF-κB and CREB Transcription Factors

“…Antisense oligonucleotides against cPLA 2 a Antisense oligonuclotides against cPLA 2 a were engineered using the computer-based approach RNADraw V1.1 (Mazura Multimedia) and used as described in our previous study (12). A combination of three oligonucleotide antisenses (TCAAAGGTCTCATTCCACA, CAAAACATTTTC-CTGATTAGG, and GCTGTCAGGGGTTGTAG) and their corresponding senses with phosphorothioate modifications on the last three bases at both 59 and 39 ends was used.…”

“…The expression of cPLA 2 a and of ICAM-1 was detected as previously described (12,17). Nonspecific reactivity was inhibited by incubation of deparaffinized tissue sections mounted on slides for 30 min in a solution of 4% normal horse serum (avidin-biotin VECTA-STAIN Kit Elite PK 6105; Vector Laboratories, Burlingame CA).…”

“…CIA was induced by intradermal injection of 100 ml emulsion containing 200 mg CII to 8-wk-old mice at the base of the tail and boosted on day 21 with CII emulsion in IFA. The severity of arthritis was assessed as described in detail in our previous study (12).…”

“…PGE 2 plays an important role in the signal transduction cascade events during induction of gene transcription (10,11). Our recent study (12) demonstrated that there is a significant elevation in cPLA 2 a expression and its metabolites in the inflamed site in two mouse models of inflammation: collagen-induced arthritis (CIA) and thioglicollateinduced peritonitis. In vivo inhibition of elevated cPLA 2 a protein expression by i.v.…”

Reduction of cPLA2α overexpression: An efficient anti‐inflammatory therapy for collagen‐induced arthritis

“…Furthermore, dual inhibitors of 5-lipoxygenase and COX were more effective than selective COX inhibitors in preventing arthritis [12]. We have previously provided evidence that cPLA 2 , in addition to its known role in participating in eicosanoid production [13], regulates the phagocyte NADPH oxidase-releasing superoxides [14][15][16]. Moreover, consistent with many other studies, we have demonstrated in vivo and in vitro that during inflammation, the level and activity of both cPLA 2 and NADPH oxidase enzymes are elevated in neutrophils and monocytes [17,18].…”