Low IL-13Rα1 expression on mast cells tunes them unresponsive to IL-13.

Cytokine-mediated mast cell regulation enables precise optimization of their own proinflammatory cytokine production. During allergic inflammation, interleukin (IL)-4 regulates mast cell functions, tissue homing, and proliferation, but the direct role of closely related IL-13 for mast cell activation remains unclear. Previous work has shown that mast cells are potent IL-13 producers, but here we show that mouse mast cells do not directly respond to IL-13 by Stat6 activation, as they do not express measurable amount of IL-13 receptor α1 (IL-4Rα1) messenger RNA. Consequently, IL-4 responses are mediated via type I IL-4R (IL-4/IL4Rα/γC), and IL-4-induced Stat6 activation is abolished in γC-deficient mast cells. Type II IL-4R deficiency (IL-13Rα1 knockout) has no effect on IL-4-induced Stat6 activation. In basophils, both IL-4 and IL-13 induce Stat6 activation in wild-type and γC-deficient cells, while in type II IL-4R-deficient basophils, IL-4 signaling is impaired at low ligand concentration. Thus, mast cell and basophil sensitivity to IL-4/IL-13 is different, and in mast cells, lack of IL-13Rα1 expression likely explains their unresponsiveness to IL-13.

Effect of inactivated nature-derived microbial composition on mouse immune system.

INTRODUCTION: The hygiene hypothesis suggests that decrease in early life infections due to increased societal-level hygiene standards subjects one to allergic and autoimmune diseases. In this report, we have studied the effect of sterilized forest soil and plant-based material on mouse immune system and gut microbiome. METHODS: Inbred C57Bl/6 mice maintained in normal sterile environment were subjected to autoclaved forest soil-derived powder in their bedding for 1 h a day for 3 weeks. Immune response was measured by immune cell flow cytometry, serum cytokine enzyme-linked immunoassay (ELISA) and quantitative polymerase chain reaction (qPCR) analysis. Furthermore, the mouse gut microbiome was analyzed by sequencing. RESULTS: When compared to control mice, mice treated with soil-derived powder had decreased level of pro-inflammatory cytokines namely interleukin (IL)-17F and IL-21 in the serum. Furthermore, splenocytes from mice treated with soil-derived powder expressed less IL-1b, IL-5, IL-6, IL-13, and tumor necrosis factor (TNF) upon cell activation. Gut microbiome appeared to be stabilized by the treatment. CONCLUSIONS: These results provide insights on the effect of biodiversity on murine immune system in sterile environment. Subjecting mice to soil-based plant and microbe structures appears to elicit immune response that could be beneficial, for example, in type 2 inflammation-related diseases, that is, allergic diseases.

A PBMC-Based System to Assess Human T Cell Responses to Influenza Vaccine Candidates In Vitro.

Vaccine development is an expensive and time-consuming process that heavily relies on animal models. Yet, vaccine candidates that have previously succeeded in animal experiments often fail in clinical trials questioning the predictive value of animal models. Alternative assay systems that can add to the screening and evaluation of functional characteristics of vaccines in a human context before embarking on costly clinical trials are therefore urgently needed. In this study, we have established an in vitro system consisting of long-term cultures of unfractionated peripheral blood mononuclear cells (PBMCs) from healthy volunteers to assess (recall) T cell responses to vaccine candidates. We observed that different types of influenza vaccines (whole inactivated virus (WIV), split, and peptide vaccines) were all able to stimulate CD4 and CD8 T cell responses but to different extents in line with their reported in vivo properties. In-depth analyses of different T cell subsets revealed that the tested vaccines evoked mainly recall responses as indicated by the fact that the vast majority of the responding T cells had a memory phenotype. Furthermore, we observed vaccine-induced activation of T follicular helper cells, which are associated with the induction of humoral immune responses. Our results demonstrate the suitability of the established PBMC-based system for the in vitro evaluation of memory T cell responses to vaccines and the comparison of vaccine candidates in a human immune cell context. As such, it can help to bridge the gap between animal experiments and clinical trials and assist in the selection of promising vaccine candidates, at least for recall antigens.