Explorer A role for lipoxin A as an anti-inflammatory mediator in the human endometrium

Lipoxin A4 is a lipid mediator that elicits anti-inflammatory and pro-resolution actions via its receptor, formyl peptide receptor 2 (FPR2/ALX). In this study, we aimed to investigate the expression and potential role of lipoxin A4 and FPR2/ALX in the regulation of inflammation associated with cyclical remodeling of the human endometrium across the menstrual cycle and during early pregnancy. Using quantitative RT-PCR analysis, we found that FPR2/ALX expression is upregulated during the menstrual phase of the cycle and in decidua tissue from the first trimester of pregnancy. We localized the site of expression of FPR2/ALX in menstrual phase endometrium and first-trimester decidua tissue to glandular epithelial cells and cells within the stromal compartment, including cells lining the blood vessels and immune cells. Measurement of serum lipoxin A4 by ELISA revealed no difference in its levels across the menstrual cycle but an elevation in early pregnancy (P!0.001). We found that lipoxin A4 was regulated by human chorionic gonadotrophin (hCG) during early pregnancy, because treatment of human decidua tissue with hCG increased lipoxin A4 release (P!0.01). Finally, we have shown that lipoxin A4 can suppress phorbol myristate acetate-induced expression of the inflammatory cytokines interleukin 6 and 8 in human endometrium and decidua tissue. These results demonstrate for the first time that lipoxin A4 and its receptor FPR2/ALX can regulate inflammatory events in the human endometrium and decidua of early pregnancy. Reproduction (2011) 142 345–352