Regulation of TREM-1 expression by 1,25-dihydroxyvitamin D-3 in human monocytes/macrophages

Abstract

Triggering receptor expressed on myeloid cells-1 (TREM-1) is a recently identified cell surface receptor that is expressed mainly on monocytes and neutrophils, and acts as an amplifier of immune responses. In this study, 1,25(OH)(2)D-3 strongly upregulated the expression of TEEM-1 in human monocytes and macrophages. 1,25(OH)(2)D-3 stimulated TREM-1 mRNA expression by augmenting transcription, and not by inhibiting mRNA degradation. The upregulated expression of TREM-1 by 1,25(OH)(2)D-3 was dependent on the NF-kappa B signaling pathway and required new protein synthesis in differentiated U937 macrophages. Our results show that 1,25(OH)(2)D-3 can affect the innate and inflammatory responses by upregulating TEEM-1 expression, and suggest that 1,25(OH)(2)D-3 may function as an enhancer of the innate immune response by upregulating TREM-1 expression, in addition to inducing the antimicrobial peptide cathelicidin.