Increased Gene Expression of Novel Cytosolic and Secretory Phospholipase A 2 Types in Human Airway Epithelial Cells Induced by Tumor Necrosis Factor- α and IFN- γ

Abstract

Phospholipase A₂ (PLA₂) is a growing family of enzymes that may play a major role in inflammation. We investigated the effect of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) on the gene expression of 19 different PLA₂ types (IB, IIA, IID, IIE, IIF, III, IVA, IVB, IVC, V, VIA, VIB, VIIA, VIIB, VIIIA, VIIIB, X, XII, and XIII) in human bronchoepithelial (BEAS-2B) and nasal epithelial (RPMI 2650) cells. The cells were stimulated with TNF-α or IFN-γ for different lengths of time (1, 4, 18, and 48 h), and the mRNA levels of the different PLA₂ types were determined by reverse transcriptase-PCR (RT-PCR) and normalized to those of the housekeeping gene, GAPDH. In both cell lines, TNF-α increased the expression of PLA₂ IVA and IVC, and IFN-γ increased the expression of PLA₂ IIA and IID. No influence on the gene expression of PLA₂-activating protein (PLAP) was noted on cytokine stimulation. These findings indicate that TNF-α and IFN-γ induce gene expression of two novel cytosolic and secretory PLA₂ types(IVC and IID, respectively) in human airway epithelial cells. The possibility that these PLA₂ types are involved in cytokine-mediated inflammation in the respiratory tract is inferred.