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

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. (C) 2013 Elsevier B.V. All rights reserved.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A2001950 to J.D.J) and (2010-0022379 T-H.K)