ABSTRACT
BACKGROUND: Vitamin D modulates inflammation in Crohn's disease (CD). Programmed death (PD)-1 receptor contributes to the maintenance of immune tolerance. Vitamin D might modulate PD-1 signalling in CD. AIM: To investigate PD-1 expression on T cell subsets in CD patients treated with vitamin D or placebo. METHODS: We included 40 CD patients who received 1200 IU vitamin D3 for 26 weeks or placebo and eight healthy controls. Peripheral blood mononuclear cells (PBMCs) and plasma were isolated at baseline and week 26. The expressions of PD-1, PD-L1, and surface activation markers were analysed by flow cytometry. Soluble PD-1 plasma levels were measured by ELISA. RESULTS: PD-1 expression upon T cell stimulation was increased in CD4+CD25+int T cells in vitamin D treated CD patients from 19% (range 10 - 39%) to 29% (11 - 79%)(p = 0.03) compared with placebo-treated patients. Vitamin D treatment, but not placebo, decreased the expression of the T cell activation marker CD69 from 42% (31 - 62%) to 33% (19 - 54%)(p = 0.01). Soluble PD-1 levels were not influenced by vitamin D treatment. CONCLUSIONS: Vitamin D treatment increases CD4+CD25+int T cells ability to up-regulate PD-1 in response to activation and reduces the CD69 expression in CD patients.
Subject(s)
Crohn Disease/genetics , Crohn Disease/metabolism , Gene Expression Regulation , Programmed Cell Death 1 Receptor/genetics , Vitamin D/metabolism , Adult , Aged , Cells, Cultured , Crohn Disease/drug therapy , Crohn Disease/immunology , Female , Gene Expression Regulation/drug effects , Humans , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/metabolism , Lymphocyte Activation/drug effects , Lymphocyte Activation/genetics , Lymphocyte Activation/immunology , Male , Middle Aged , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/metabolism , Vitamin D/pharmacology , Vitamin D/therapeutic use , Young AdultABSTRACT
BACKGROUND: Low serum vitamin D levels may provoke or aggravate Crohn's disease (CrD). Vitamin D3 is a well-known immune modulator that affects immune functions in vitro and may prevent CrD flares. Dendritic cells (DC) are key mediators of vitamin D3 effects. In this study, we describe changes in monocyte-derived DC (mo-DC) maturation marker expression and cytokine production following 26 weeks of oral vitamin D3 supplementation in CrD patients. METHODS: Ten CrD patients who had increased serum 25-hydroxy vitamin D levels after oral vitamin D3 and calcium treatment and ten seasonally matched placebo-treated patients were selected for this study. Mo-DC were generated before and after the 26 weeks and induced to mature upon lipopolysaccharide (LPS) stimulation. Maturation marker expression and cytokine production were analysed. Mo-DC function was analysed in a mixed leucocyte reaction (MLR). RESULTS: Compared with baseline values, LPS-matured mo-DC exhibited reduced expression of CD80 and reduced production of the cytokines IL-10, IL-1ß, and IL-6 following 26 weeks of oral vitamin D3 supplementation. Mo-DC performance in an allogeneic MLR was unchanged after vitamin D3 supplementation. Treatment with the placebo did not affect maturation markers, cytokine production, or the MLR. CONCLUSIONS: Vitamin D3 treatment in CrD patients led to hypo-responsive LPS-stimulated mo-DC. This finding indicates that vitamin D3 levels have an impact on the monocytic precursors of mo-DC in vivo and may explain the positive effects of vitamin D3 supplementation on CrD patients. Alternatively, CrD patients with high serum vitamin D3 levels may represent a subgroup with low disease activity.
Subject(s)
Cholecalciferol/administration & dosage , Crohn Disease/immunology , Cytokines/immunology , Dendritic Cells/drug effects , Dendritic Cells/immunology , Monocytes/drug effects , Monocytes/immunology , Administration, Oral , Adult , Calcium/administration & dosage , Cholecalciferol/immunology , Crohn Disease/blood , Dietary Supplements , Female , Humans , Lipopolysaccharides/immunology , Male , Middle Aged , T-Lymphocytes/drug effects , T-Lymphocytes/immunology , Vitamin D/analogs & derivatives , Vitamin D/blood , Young AdultABSTRACT
BACKGROUND: In Crohn's disease (CrD), vitamin D may help to balance an exaggerated immune response and thereby improve the disease course. The immunomodulating effects depend on the activation of 25-hydroxy vitamin D3 (25-D3), into 1,25-dihydroxy vitamin D3 (1,25-D3). This activation has previously been shown to take place in dendritic cells (DC) from healthy individuals. We hypothesised that DC from CrD patients are able to regulate and control inflammatory responses through 25-D3 activation. METHODS: During differentiation, monocyte-derived DC from 20 CrD patients were cultured with either 25-D3 or 1,25-D3 and matured with lipopolysaccharide (LPS). We examined DC surface marker expression, cytokine production, and the ability to induce cell proliferation in an allogeneic mixed leukocyte reaction. RESULTS: Following stimulation with LPS, DC exposed to either 25-D3 or 1,25-D3 exhibited lower expression levels of CD80, CD83, CD86, and HLA-DR and diminished TNF-α production compared with DC cultured with LPS alone. In contrast, CD14 expression and IL-6 production were higher following 25-D3 or 1,25-D3 treatment. Compared with LPS alone, both forms of vitamin D3 reduced the ability of DC to activate lymphocytes. CONCLUSIONS: Following stimulation with 25-D3, DC from CrD patients displayed a reduced response to LPS with a diminished capability to activate T cells compared with DC stimulated with LPS alone. These data indicate that intrinsic activation of 25-D3 occurs in DC from CrD patients and show that 25-D3 can modulate DC function in CrD. Our data suggest that vitamin D deficiency may contribute to the uncontrolled inflammatory process seen in CrD.