Autocrine IL-10 promotes human B-cell differentiation into IgM- or IgG-secreting plasmablasts.

B-cell-derived interleukin-10 (IL-10) is known to act in a paracrine fashion to suppress inflammation. Here, we show that IL-10 also acts in an autocrine manner to regulate the differentiation of activated human B cells. We report that IL-10 expression is not restricted to a dedicated B-cell subset, but is induced transiently in peripheral human naïve, memory, and CD5(+) B cells alike upon activation. Global transcriptome comparison of activated human B cells, secreting IL-10 or not, identified 138 differentially regulated genes, most of which were associated with differentiation into antibody-secreting cells and reflecting autocrine IL-10 signaling. We monitored the differentiation of IL-10-secreting B cells and determined the effect of IL-10-blocking antibodies against its autocrine and paracrine signaling. IL-10 signaling promoted the differentiation of activated IL-10-secreting B cells into IgM- or IgG-secreting cells, but was dispensable for IgA secretion. Our data imply that B-cell-derived IL-10 not only suppresses immune reactions via paracrine mechanisms, but can also contribute to the differentiation of IL-10-secreting B cells into IgM- and IgG-secreting plasmablasts through both autocrine and paracrine signaling.

Oral vitamin D increases the frequencies of CD38+ human B cells and ameliorates IL-17-producing T cells.

Vitamin D deficiency (serum 25-hydroxyvitamin D < 50 nm) has been associated with the onset of immunological diseases including atopic dermatitis (AD), cutaneous or systemic lupus erythematosus and allergic asthma. In this study, we assessed whether oral vitamin D (cholecalciferol) supplementation leads to a systemic modulation of the phenotype of circulating lymphocyte populations and whether a defined serum 25-hydroxyvitamin D (25(OH)D) concentration can be related to the effects on lymphocytes. Cholecalciferol was administered in a dose-escalation setting to vitamin D-deficient individuals from 2000 up to 8000 IU daily for 12 weeks. Individuals without cholecalciferol intake served as controls. Peripheral B cells and T cells were examined by multicolour flow cytometric analysis. The mean serum 25(OH)D concentrations increased upon cholecalciferol intake up to 159 ± 28.7 nm, and remained low in the control group 30.0 ± 12.5 nm. Following cholecalciferol intake, the frequencies of circulating CD38 expressing B cells were significantly increased and IFN-γ+ , and/or IL-17+ CD4+ T helper cells were decreased. These data were identified to correlate with the serum 25(OH)D levels by applying two different analysis approaches (ROC and a nonlinear regression analysis). Our data indicate that increasing 25(OH)D serum concentrations are associated with an increased expression of CD38 on B cells and a decreased T-cell-dependent proinflammatory cytokine production. The therapeutical role of our findings in systemic immunological diseases should be explored in the future by further controlled clinical studies.

Immunomodulation in patients with chronic hand eczema treated with oral alitretinoin.

BACKGROUND: Oral alitretinoin (9-cis-retinoic acid; 9-cis-RA) has shown clinical efficacy in patients with chronic hand eczema (CHE). Herein, we investigated the impact of oral 9-cis-RA on the local and systemic immune response in patients with CHE. METHODS: Twenty patients with CHE were treated with oral alitretinoin (10 or 30 mg/day) for at least 24 weeks. Blood samples were taken for flow cytometry, and serum samples were assessed by ELISA to determine immunoglobulin (Ig) levels. Skin biopsies from lesional skin were evaluated immunohistochemically. RESULTS: Upon 9-cis-RA treatment, improvement of the CHE was observed in all patients. A significant decrease in plasmablasts in the peripheral blood and a significant reduction of serum IgE levels were determined. Furthermore, we detected a significant reduction of CD4+ cells and regulatory T cells in the peripheral blood upon treatment. By contrast, these cell subsets were significantly increased in the affected skin. Cytokine analysis of activated CD154-positive T cells showed a reduction of interleukin (IL)-17 but not of IL-4 or IFN-γ production. CONCLUSIONS: Overall, our data indicate a disease-modifying effect of 9-cis-RA, including a systemic decrease in IL-17-positive cells, but decreased serum IgE and CD23 expression. The increased frequency of FoxP3-positive cells in the skin upon treatment may suggest a mechanism by which hand eczema is therapeutically targeted by 9-cis-RA, but this will need to be proven in the future studies.

Pharmacokinetic Evaluation of a Single Intramuscular High Dose versus an Oral Long-Term Supplementation of Cholecalciferol.

BACKGROUND AND OBJECTIVES: Vitamin D deficiency is frequent during the winter and occurs throughout the year in the elderly or patients suffering from autoimmune diseases. The objective of this study was to evaluate the pharmacokinetic properties of oral supplementation versus a single intramuscular injection of cholecalciferol in healthy individuals. RESEARCH DESIGN AND METHODS: Up to 8,000 I.U. oral cholecalciferol was administered daily for 84 days in a 4 week dose-escalation setting to vitamin D deficient individuals. In another cohort, a single intramuscular injection of 100,000 I.U. cholecalciferol was given. In both cohorts, individuals without vitamin D intake served as the comparison group. 25-hydroxyvitamin D (25(OH)D) concentrations were measured in all individuals at defined time points throughout the studies. RESULTS: The mean 25(OH)D serum concentration increased significantly after oral cholecalciferol intake compared to the control group (day 28: 83.4 nmol/l and 42.5 nmol/l; day 56: 127.4 nmol/l and 37.3 nmol/l; day 84: 159.7 nmol/l and 30.0 nmol/l). In individuals receiving 100,000 I.U. cholecalciferol intramuscular, the mean 25(OH)D serum concentration peaked after 4 weeks measuring 70.9 nmol/l compared to 32.7 nmol/l in the placebo group (p = 0.002). The increase of 25(OH)D serum concentrations after 28 days was comparable between both routes of administration (p = 0.264). CONCLUSIONS: Oral and intramuscular cholecalciferol supplementation effectively increased serum 25(OH)D concentrations.

A nematode immunomodulator suppresses grass pollen-specific allergic responses by controlling excessive Th2 inflammation.

Helminth parasites modulate the immune system by complex mechanisms to ensure persistence in the host. Released immunomodulatory parasite components lead to a beneficial environment for the parasite by targeting different host cells and in parallel to a modulation of unrelated inflammatory responses in the host, such as allergy. The aim of this study was to investigate the effect of the potent helminth immunomodulator, filarial cystatin, in a murine model of airway inflammation and hyperreactivity induced by a clinically relevant aeroallergen (timothy grass (Phleum pratense) pollen) and on the function of peripheral blood mononuclear cells (PBMCs) from timothy grass pollen allergic patients. BALB/c mice were systemically sensitised with a recombinant major allergen of timothy grass pollen (rPhl p 5b) and then challenged with timothy grass pollen extract (GPE) via the airways. Filarial cystatin was applied i.p. during the sensitisation phase. Airway hyperresponsiveness to methacholine challenges, inflammation of airways, inflammatory cell recruitment, cytokine production and lung histopathology were investigated. In a translational approach, PBMCs from allergic subjects and healthy controls were treated in vitro with cystatin prior to stimulation with GPE. Administration of filarial cystatin suppressed rPhl p 5b-induced allergen-specific Th2-responses and airway inflammation, inhibited local recruitment of eosinophils, reduced levels of allergen-specific IgE and down-regulated IL-5 and IL-13 in the bronchoalveolar lavage (BAL). Ex vivo restimulation with cystatin of spleen cells from cystatin-treated mice induced the production of IL-10, while cystatin inhibited allergen-specific IL-5 and IL-13 levels. Human PBMCs from timothy grass pollen allergic patients displayed a shift towards a Th1 response after treatment with cystatin. These results show that filarial cystatin ameliorates allergic inflammation and disease in a clinically relevant model of allergy. This data indicate that filarial cystatin has a modulatory effect on grass pollen-specific responses warranting further investigation of potential preventive and therapeutic options in the treatment of allergies.

Interleukin-17A promotes IgE production in human B cells.

Recently the Th1/Th2 concept has been revised and Th17 cells have been implicated in allergy. Despite clear correlative evidence, the cellular and molecular basis for the connection between increased IL-17A and IgE in allergy has not been elucidated. Here we show using flow cytometry that allergic patients have higher numbers of IL-17A+ cells compared to nonallergic donors. The selective removal of IL-17A+ cells from peripheral blood mononuclear cells of allergic donors after an IL-17A secretion assay reduces IgE levels, whereas re-addition of recombinant IL-17A restores it, as measured by ELISA, showing their important functional implication for IgE production. In addition, IL-17A directly promotes the differentiation of IgE-secreting cells and IgE production upon anti-CD40/IL-4 costimulation, as shown by enzyme-linked immunospot technique and ELISA. IL-17A triggers rapid degradation of IκBα and subsequent translocation of NF-κB into the B-cell nucleus, followed by transcription of epsilon germ-line, activation-induced cytidine deaminase, and IFN regulatory factor 4, as analyzed by flow cytometry, western blot, and quantitative real-time RT-PCR, respectively. Our study shows that IL-17A+ cells promote IgE production and that IL-17A exerts its pro-allergic effect directly at the level of B cells. Therefore, IL-17A might be a target for the treatment of IgE-dependent diseases, including atopic dermatitis.