Human retinal pigment epithelial cells express the long pentraxin PTX3

To determine whether the long pentraxin 3 (PTX3) is expressed in human retinal pigment epithelial cells and is induced by inflammatory cytokines, interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), expression of PTX3 was investigated in the human retinal pigment epithelial cell line, ARPE-19 cells.

In ARPE-19 cells, we first analyzed PTX3 production in the presence or absence of inflammatory cytokines, IL-1β, TNF-α, and IFN-γ, dose- and time-dependently using enzyme-linked immunosorbent assay. Protein and mRNA expression of PTX3 was measured with western blotting analysis and real-time reverse transcription-polymerase chain reaction. Specific inhibitors were used to determine the signaling pathways of inflammatory cytokine-induced PTX3 expression.

In this study, production of PTX3 was induced by IL-1β and TNF-α dose- and time-dependently, but not by IFN-γ in ARPE-19 cells. Protein and mRNA expression of PTX3 was significantly upregulated in the presence of IL-1β and TNF-α. Furthermore, pretreatment with extracellular signal-regulated kinase1/2 and nuclear factor kappa-light-chain-enhancer of activated B cells specific inhibitor abolished IL-1β and TNF-α-induced PTX3 production, but the other inhibitors had no effect.

These results suggested that human retinal pigment epithelial cells may be a major source of PTX3 production in the presence of proinflammatory cytokines, IL-1β and TNF-α, and could be an important mediator for host defense and inflammatory response in the retina. The importance of the mitogen-activated protein kinase/extracellular signal-regulated kinase1/2 and nuclear factor kappa-light-chain-enhancer of activated B cells pathways for regulated PTX3 expression may be a potential target for PTX3 regulation in the retina.