Cutting Edge: Coordinate Regulation of IFN Regulatory Factor-1 and the Polymeric Ig Receptor by Proinflammatory Cytokines

Abstract

The polymeric IgR (pIgR) mediates transcytosis of IgA across epithelial barriers of mucous membranes and exocrine glands. Synthesis of pIgR is up-regulated by the proinflammatory cytokines TNF-α, IFN-γ, and IL-1 in HT-29 human colon carcinoma cells. We previously reported that IFN-γ and TNF-α induce production of the transcription factor IFN regulatory factor-1 (IRF-1) in HT-29 cells and that IRF-1 binds to an element in exon 1 of the PIGR gene. We now report that levels of IRF-1 and pIgR mRNA are coordinately regulated in HT-29 cells by TNF-α, IFN-γ, and IL-1β. Furthermore, we demonstrate that in vivo expression of pIgR mRNA is greatly depressed in the intestine and liver of IRF-1-deficient mice. Our findings indicate a major role for the IRF-1 transcription factor in regulation of the PIGR gene and suggest a model for regulation of important genes in the mucosal immune system by proinflammatory cytokines.