Vitamin D treatment modulates immune activation in cystic fibrosis.

Persistent inflammatory response in cystic fibrosis (CF) airways is believed to play a central role in the progression of lung damage. Anti-inflammatory treatment may slow lung disease progression, but adverse side effects have limited its use. Vitamin D has immunoregulatory properties. We randomized 16 CF patients to receive vitamin D2, vitamin D3 or to serve as controls, and investigated the effect of vitamin D supplementation on soluble immunological parameters, myeloid dendritic cells (mDCs) and T cell activation. Three months of vitamin D treatment were followed by two washout months. Vitamin D status at baseline was correlated negatively with haptoglobin, erythrocyte sedimentation rate and immunoglobulin A concentration. Total vitamin D dose per kg bodyweight correlated with the down-modulation of the co-stimulatory receptor CD86 on mDCs. Vitamin D treatment was associated with reduced CD279 (PD-1) expression on CD4+ and CD8+ T cells, as well as decreased frequency of CD8+ T cells co-expressing the activation markers CD38 and human leucocyte antigen D-related (HLA-DR) in a dose-dependent manner. There was a trend towards decreased mucosal-associated invariant T cells (MAIT) cell frequency in patients receiving vitamin D and free serum 25-hydroxyvitamin D (free-s25OHD) correlated positively with CD38 expression by these cells. At the end of intervention, the change in free-s25OHD was correlated negatively with the change in CD279 (PD-1) expression on MAIT cells. Collectively, these data indicate that vitamin D has robust pleiotropic immunomodulatory effects in CF. Larger studies are needed to explore the immunomodulatory treatment potential of vitamin D in CF in more detail.

Clinical impact of vitamin D treatment in cystic fibrosis: a pilot randomized, controlled trial.

BACKGROUND/OBJECTIVES: Vitamin D insufficiency in cystic fibrosis is common. Vitamin D3 is currently preferred over D2. We aimed to study the efficacy of vitamin D2 and D3 at increasing serum 25-hydroxyvitamin D (s25OHD) concentrations and their effect on respiratory health in cystic fibrosis. SUBJECTS/METHODS: Sixteen CF patients were randomized to receive vitamin D2 or D3 or to serve as controls. The starting dose of 5000 IU (<16 years old) or 7143 IU/day (⩾16 years old) was further individually adjusted. Three months of intervention were followed by two of washout (ClinicalTrials.gov NCT01321905). RESULTS: To increase s25OHD, the mean daily dose of vitamin D2 and D3 had to be increased up to 15650 and 8184 IU, respectively. The combined group of vitamin D2 and D3 treated patients decreased plasma IL-8 (P<0.05). Patients provided vitamin D3 improved FVC at the end of the trial (P<0.05). Change in s25OHD was positively correlated with changes in the adult Quality-of-Life respiratory score at the end of supplementation (P=0.006, r=0.90), and with changes in FEV1 (P=0.042, r=0.62) and FVC (P=0.036, r=0.63) at one month of washout. CONCLUSIONS: Vitamin D supplementation may contribute to reduced inflammation and improved lung function in CF.

Bacteroides are associated with GALT iNKT cell function and reduction of microbial translocation in HIV-1 infection.

Invariant natural killer T (iNKT) cells are innate-like T cells that respond to lipid antigens presented by CD1d. These immunoregulatory cells have the capacity for rapid cytokine release after antigen recognition and are essential for the activation of multiple arms of the immune response. HIV-1 infection is associated with iNKT cell depletion in the peripheral blood; however, their role in the gastrointestinal-associated lymphoid tissue (GALT) is less well studied. Our results show that iNKT cells are found at a higher frequency in GALT compared with blood, particularly in HIV-1 elite controllers. The capacity of iNKT cells to produce interleukin-4 (IL-4) and IL-10 in the GALT was associated with less immune activation and lower markers of microbial translocation, whereas regulatory T cell frequency showed positive associations with immune activation. We hypothesized that the composition of the microbiota would influence iNKT cell frequency and function. We found positive associations between the abundance of several Bacteroides species and iNKT cell frequency and their capacity to produce IL-4 in the GALT but not in the blood. Overall, our results are consistent with the hypothesis that GALT iNKT cells, influenced by certain bacterial species, may have a key role in regulating immune activation in HIV-1 infection.

MAIT cells reside in the female genital mucosa and are biased towards IL-17 and IL-22 production in response to bacterial stimulation.

The female genital tract (FGT) mucosa is a critically important site for immune defense against microbes. Mucosal-associated invariant T (MAIT) cells are an innate-like T-cell population that recognizes microbial riboflavin metabolite antigens in an MR1-dependent manner. The role of MAIT cells in the FGT mucosa is unknown. Here, we found that MAIT cells and MR1+ antigen-presenting cells were present in the upper and lower FGT, with distinct tissue localization of MAIT cells in endometrium vs. cervix. The MAIT cells from the FGT and blood displayed a distinct phenotype with expression of interleukin (IL)-18Rα, CD127, α4ß7, PD-1, as well as the transcription factors promyelocytic leukemia zinc finger (PLZF), RORγt, Helios, Eomes, and T-bet. Their expression levels of PLZF and Eomes were lower in the FGT compared with blood. When stimulated with Escherichia coli, MAIT cells from the FGT displayed a bias towards IL-17 and IL-22 expression, whereas blood MAIT cells produced primarily IFN-γ, TNF, and Granzyme B. Furthermore, both FGT- and blood-derived MAIT cells were polyfunctional and contributed to the T-cell-mediated response to E. coli. Thus, MAIT cells in the genital mucosa have a distinct IL-17/IL-22 profile and may have an important role in the immunological homeostasis and control of microbes at this site.