Inhibition of cytokine secretion from adipocytes by 1,25-dihydroxyvitamin D3 via the NF-κB pathway

Adipose tissue inflammation is an important pathological process in obese people, associated with diabetes and cardiovascular disease. We hypothesized that 1,25-dihydroxyvitamin D-3 [1,25(OH)2D(3)] inhibits cytokine secretion from adipocytes via direct inhibition of transcription factor nuclear factor-kappa B (NF-kappa B). We utilized two different human models. Bone marrow-derived human mesenchymal stromal cells (hMSCs) differentiated into adipocytes, and adipocytes isolated from biopsies stimulated with lipopolysaccharide (LPS) were treated with or without 1,25(OH) 2D(3). Expression and secretion of interleukin-6 (IL-6) were measured by quantitative RT-PCR analysis and ELISA. Assessment of NF-kappa B nuclear translocation, DNA binding activity was performed by immunofluorescence (IF) and electrophoretic mobility assay (EMSA). Inhibitor kappa B (I kappa B) and its phosphorylation were detected by Western blot (WB) analysis. Simultaneous 1,25(OH) 2D(3) cotreatment significantly re-duced LPS-stimulated (10 ng/ml) IL-6 secretion dose dependently by 15% at 10(-10) M and 26% at 10(-7) M (P<0.05) in hMSCs, while preincubation with 1,25(OH) 2D(3) (10(-7) M) for 24 h reduced IL-6 secretion by 24 and 35% (P<0.001) and mRNA levels by 34 and 30% (P<0.05) in hMSCs and isolated adipocytes, respectively. 1,25(OH) 2D(3) suppressed LPS-stimulated I kappa B phosphorylation-mediated NF-kappa B translocation into the nucleus were evident from WB, IF, and EMSA. 1,25(OH) 2D(3) inhibits LPS-stimulated IL-6 secretion in two human adipocyte models via interference with NF-kappa B signaling.-Mutt, S.J., Karhu, T., Lehtonen, S., Lehenkari, P., Carlberg, C., Saarnio, J., Sebert, S., Hypponen, E., Jorvelin, M.-R., Herzig, K.-H. Inhibition of cytokine secretion from adipocytes by 1,25-dihydroxyvitamin D-3 via the NF-kappa B pathway. FASEB J. 26, 4400-4407 (2012). www.fasebj.org