Expression of phospholipases A2 and C in human corneal epithelial cells

To achieve a better understanding of the involvement of phospholipases in the inflammation and wound-healing processes in human corneal epithelial cells (HCECs), expression of phospholipase A2s (PLA2s) and phospholipase Cs (PLCs) was examined in the human corneal epithelium.

Specific primers were designed for RT-PCR amplification of the known secreted (s)PLA2, cytosolic (c)PLA2, and PLC mRNAs. Corresponding PCR products were cloned and the DNA sequenced. Immunofluorescence of flatmounted corneal sections and Western blot analyses were used to detect the PLA2s and PLCs expressed by HCECs.

The mRNAs for the following phospholipases were detected by RT-PCR in the HCECs: sPLA2GIII, -GX, and -GXIIA; cPLA2alpha and -gamma; PLCbeta1, -beta2, -beta3, -beta4, -gamma1, -gamma2, -delta1, -delta3, -delta4, and -epsilon. Immunofluorescence analyses conducted on corneal epithelium cryosections and Western blot on freshly isolated HCECs demonstrated the presence of sPLA2GIII, -GX, and -GXIIA; cPLA2alpha and -gamma; and PLCbeta2, -beta3, -gamma1, -gamma2, and -delta3.

Many phospholipase isoforms are expressed by HCECs and may play a major role in signal transduction (PLCs) as well as in the release of precursors of potent mediators of inflammation, such as leukotrienes and prostaglandins (PLA2s). Moreover, the sPLA2s expressed by the corneal epithelium could be involved in the normal antibacterial activity in the tears and in wound healing.