Stephanie Knippenberg

Effects of vitamin D on the peripheral adaptive immune system: A review

Epidemiological studies have shown that a poor vitamin D status is associated with an increased risk of several diseases, including autoimmune diseases. The immune regulatory function of vitamin D is thought to have an important role in these associations. Cells of the adaptive immune system have shown to be direct targets of the vitamin D metabolites. Besides being direct targets, cells of the adaptive immune system express the enzymes involved in the metabolism of vitamin D, enabling them to locally convert 25(OH)D into its active metabolite 1,25(OH)2D. In this review, the effects of vitamin D on cells of the adaptive immune system are described. Experimental data in vitro show that vitamin D skews cells of the adaptive immune system toward a more tolerogenic status which might be exploited in the treatment of autoimmune diseases. However, it should be noticed that in vivo effects may differ from in vitro effects due to the cross-talk between different vitamin D sensitive cells, but data support the view that vitamin D is positively involved in maintaining or restoring immune homeostasis. Upcoming vitamin D supplementation trials will further elucidate the in vivo effects of vitamin D on the immune system and its potency to serve as an immune regulating agent in autoimmune diseases.

Reduction in IL-10 producing B cells (Breg) in multiple sclerosis is accompanied by a reduced naïve/memory Breg ratio during a relapse but not in remission

In this study, we assessed B cell subsets, including Bregs, during stable and active disease in relapsing remitting multiple sclerosis (RRMS) patients and related B cell subsets to vitamin D status. We report that RRMS patients have a decreased percentage of both memory B cells and Bregs compared to healthy controls. During a relapse, the reduction in Bregs involved in particular naïve Bregs. We found no correlation between vitamin D status and B cell subsets. An effect of vitamin D on Bregs cannot be ruled out, since it might be the function that is interfered with instead of relative numbers.

Regulatory B cells in ANCA-associated vasculitis

Objectives B cells have immunoregulatory function acting as antigen-presenting cells. A separate subset of interleukin (IL)-10 producing B cells (Breg) regulating T cell mediated immunity has been identified. In the present study, we investigated the role of Breg in antineutrophil cytoplasmic antibodies-associated vasculitis (AAV). Methods 17 healthy controls (HCs) and 41 patients with AAV were enrolled. 30 patients with AAV were in remission. Furthermore, 11 patients with AAV with active disease were studied. Breg were defined as IL-10+CD19+ B cells upon culture with cytosine-phosphate-guanosine oligodeoxynucleotide (CpG ODN) 2006. Next to Breg, CD4+CD127lowCD25hiCD39neg/CD39+ regulatory T-cells (Treg), interferon (IFN)γ+, IL-4+ and Il-17A+T helper cell subsets were determined via flow cytometry. Results Patients with active or quiescent disease showed a diminished fraction of Breg as compared with HCs. The frequency of IFNγ+ T helper cells was negatively associated with Breg in untreated AAV in remission but not in active vasculitis or in HCs. Interestingly, the total Treg population and the CD39+ Treg subpopulation correlated positively with Breg in inactive patients with AAV. Conclusions IL-10 producing B cells are diminished in AAV. Furthermore, Breg might regulate Th1 cells and are associated with Treg in quiescent AAV. Suppression of Th1 cells by Breg may be insufficient in active AAV.

Effect of vitamin D3 supplementation on peripheral B cell differentiation and isotype switching in patients with multiple sclerosis

Background: Vitamin D has been proposed as a promoter of immune homeostasis in multiple sclerosis (MS). During the past decade, the focus of the effects of vitamin D has been on dendritic cells and on T cells. Since there is an increasing interest in the role of B cells in the pathophysiology of MS, we studied the role of vitamin D on B cells in vivo in patients with MS. Objective: We explored the effects of 12 weeks high-dose vitamin D3 supplementation on peripheral B cell differentiation, immunoglobulin production and levels of B cell activating factor (BAFF) in 15 patients with MS. Methods: Circulating B cell subsets were characterized by flow cytometry. Plasma immunoglobulin levels were assessed by nephelometry. Plasma BAFF levels were assessed by enzyme-linked immunosorbent assay (ELISA). Results: Although a significant increase serum 25-hydroxyvitamin D was induced, we found no significant shift in B cell differentiation, isotype switching, or plasma BAFF levels. Conclusion: In patients with MS, supplementation of high doses vitamin D3 does not have substantial effects on phenotypic markers of B cell differentiation in circulating B cells. Future studies may unravel more subtle changes in the B cell compartment, either in the circulation or in the central nervous system.

Th17 expansion in MS patients is counterbalanced by an expanded CD39(+) regulatory T cell population during remission but not during relapse

In this study, percentages of CD39(+) Treg and Th17 cells were compared between relapsing-remitting MS patients and controls and were related to the vitamin D status. The Th17 cell population was expanded in about 40% of the MS patients. In MS patients in remission, but not during relapse, a positive association was found between Th17 cell and CD39(+) Treg percentages (r=0.468, p=0.007). Since CD39(+) Tregs have been shown to have Th17 suppressive capacities, we propose that a dysregulated Th17/CD39(+) Treg balance might contribute to disease exacerbation. A clear role for vitamin D in this regulation could not be established.

Vitamin D status in patients with MS is negatively correlated with depression, but not with fatigue.

Knippenberg S, Bol Y, Damoiseaux J, Hupperts R, Smolders J. Vitamin D status in patients with MS is negatively correlated with depression, but not with fatigue.
Acta Neurol Scand: 2011: 124: 171–175.
© 2010 John Wiley & Sons A/S.

Vitamin D-related gene expression profiles in immune cells of patients with relapsing remitting multiple sclerosis.

An impaired vitamin D (vit-D) processing by immune cells of relapsing remitting multiple sclerosis (RRMS) patients may increase their vulnerability for a poor vit-D status. We assessed with qPCR the expression of vit-D related genes in PBMC and CD4+ T-cells. Gene expression profiles of vit-D receptor (VDR), CYP27B1 and CYP24A1 did not differ between RRMS patients and healthy controls. Interestingly, more VDR expression in PBMC correlated with less circulating IFN-γ+ CD4+ T-cells. Our results suggest that vit-D processing by immune cells is not impaired in RRMS, and is potentially relevant for the composition of the peripheral CD4+ T-cell compartment.

Fraction of IL-10 + and IL-17 + CD8 T cells is increased in MS patients in remission and during a relapse, but is not influenced by immune modulators

In the present study, circulating proportions of CD8(+) T (Tc) cell subsets, including IL-17 (Tc17) and IL-10 (Tc10) producing cells, were assessed in relapsing-remitting MS (RRMS) patients and a possible effect of beta interferon (IFN-β), glatiramer acetate (GA), and vitamin D (VitD) on these cell subsets was investigated. We show that both Tc17 and Tc10 cell fractions are elevated in the circulation of RRMS patients in remission compared to healthy subjects and that these Tc subsets remain unaffected by current immune modulating regimens.

Location of myocardium at risk in patients with first-time ST-elevation infarction: comparison among single photon emission computed tomography, magnetic resonance imaging, and electrocardiography

BACKGROUND The amount of myocardium at risk (MaR) during acute coronary occlusion and the duration of occlusion are important determinants of final infarct size. The main goal of early reperfusion therapy is to salvage ischemic myocardium, thereby preserving left ventricular function. The aims of the present study were to test the feasibility of developing polar plot representations of MaR, for perfusion single photon emission computed tomography (SPECT), regional wall thickening by magnetic resonance imaging (MRI), and distribution of ST-segment changes. A second aim was to test the hypothesis that these different modalities display similar localization of the MaR in patients with reperfused first-time myocardial infarction. METHODS Eleven patients with first-time myocardial infarction with ST-elevation received (99m)Tc tetrofosmin before primary percutaneous coronary intervention, SPECT imaging within 3 hours, and cardiac MRI of the left ventricle within 24 hours. The results for SPECT, MRI, and electrocardiogram (ECG) were developed into polar plots, and two expert observers designated the culprit coronary artery as assessed by angiography. RESULTS The perfusion SPECT, MRI wall thickening, and ST changes are presented in side-by-side polar plots. In total, the culprit artery, based on the location of the MaR, was correctly designated in 91%, 82%, and 91% of cases by SPECT, MRI, and ECG, respectively. CONCLUSIONS Polar representation for localization of the MaR by SPECT perfusion, MRI wall thickening, and ECG ST-segment deviation is feasible. All 3 modalities have the potential to be used for indirect visual designation of the culprit artery in patients with first-time acute coronary occlusion.

GM-CSF production by CD4+ T cells in MS patients: Regulation by regulatory T cells and vitamin D

BACKGROUND/OBJECTIVE Data from animal models of MS suggest that GM-CSF(+)CD4(+)T cells are pathogenic cells. Therefore, GM-CSF production by CD4(+)T cells of MS patients and their susceptibility to regulatory mechanisms were investigated. METHODS Intracellular flowcytometry was performed to determine the GM-CSF(+)CD4(+)T cell fraction in PBMC and CSF of MS patients and controls. The effect of regulatory T cells (Tregs) on GM-CSF production by CD4(+)T cells was studied in MS patients using a proliferation-suppression assay. Finally, GM-CSF(+)CD4(+)T cell fraction and GM-CSF protein levels in supernatant were assessed in anti-CD3-stimulated CD4(+)T cell cultures derived from healthy controls and MS patients, in the presence or absence of the active vitamin D metabolite calcitriol. RESULTS The GM-CSF(+)CD4(+)T cell fraction in the peripheral blood did not differ between controls and MS patients. This T cell population could also be detected in the CSF of both subjects with MS as well as subjects with another diagnosis. In the CSF, it comprised a significant fraction of the T cell population. Upon in vitro stimulation of PBMC with anti-CD3 antibody, no differences were observed in GM-CSF(+)CD4(+)T cell frequencies. GM-CSF secretion was susceptible to regulation by Treg and vitamin D. Suppression of GM-CSF secretion by vitamin D was reduced in MS patients. CONCLUSIONS Our study showed no elevation in GM-CSF(+)CD4(+)T cell fractions in MS patients compared to controls. Furthermore, GM-CSF secretion was prone to regulation by Treg and vitamin D, the latter being less effective in MS patients.