Flagellin Modulates the Function of Invariant NKT Cells From Patients With Asthma via Dendritic Cells

PURPOSE: Invariant natural killer T (iNKT) cells play a critical role in the pathogenesis of asthma. We previously reported the association between circulating Th2-like iNKT cells and lung function in asthma patients and the suppressive effect of Toll-like receptor 5 ligand flagellin B (FlaB) on asthmatic in a mouse model. Thus, we investigated whether FlaB modulates the function of circulating iNKT cells in asthmatic patients. METHODS: Peripheral blood mononuclear cells (PBMCs) were treated with FlaB, and the secreted and intracellular cytokines of iNKT cells were evaluated by using ELISA and flow cytometry, respectively, following stimulation with alpha-galactosylceramide. Foxp3+ iNKT cells were also measured. To determine the effect of FlaB-treated dendritic cells (DCs) on iNKT cells, we co-cultured CD14+ monocyte-derived DCs and T cells from patients with house dust mite-sensitive asthma and analyzed intracellular cytokines in iNKT cells. RESULTS: A reduction of IL-4 and IL-17 production by iNKT cells in PBMCs after FlaB treatment was alleviated following blocking of IL-10 signaling. A decrease in the frequencies of IL-4+ and IL-17+ iNKT cells by FlaB-treated DCs was reversed after blocking of IL-10 signaling. Simultaneously, an increase in Foxp3+ iNKT cells induced by FlaB treatment disappeared after blocking of IL-10. CONCLUSIONS: FlaB may inhibit Th2- and Th17-like iNKT cells and induce Foxp3+ iNKT cells by DCs via an IL-10-dependent mechanism in asthmatic patients. In patients with a specific asthma phenotype associated with iNKT cells, FlaB may be an effective immunomodulator for iNKT cell-targeted immunotherapy.

Raw shiitake-induced systemic allergic contact dermatitis

It has been reported that ingestion of raw or undercooked shiitake mushrooms is associated with various adverse food reactions. A 58-year-old man presented with pruritic and maculopapular rashes on the trunk and extremities starting 1 day after ingestion of partially uncooked shiitake mushrooms. A probable diagnosis of systemic allergic contact dermatitis was made. Raw and cooked shiitake mushroom-derived allergen extracts were prepared, and patch and intradermal tests with delayed readings were performed. The case showed positive intradermal test results with delayed readings to the raw, but not cooked, extracts. The case suggests that ingestion of uncooked shiitake mushrooms may induce systemic allergic contact dermatitis through type IV hypersensitivity reaction.

Increased Th2-like Invariant Natural Killer T cells in Peripheral Blood From Patients With Asthma

PURPOSE: Invariant natural killer T (iNKT) cells might play an important role in asthma pathogenesis in humans. Our previous study found no difference in the number of blood iNKT cells between asthma patients and controls. However, few studies have examined the function of blood iNKT cells in human asthma. METHODS: Twenty asthma patients and eight controls were included in this study. Blood iNKT cells were identified using double staining with anti-Valpha24 and anti-Vbeta11 monoclonal antibodies (mAbs) or with 6B11 and anti-Vbeta11 mAbs. Intracellular IL-4, IL-10, and IFN-gamma cytokines were stained in blood iNKT cells using their respective mAbs and isotypes. In addition, their relationships with clinical parameters were analyzed. RESULTS: The number of Valpha24+Vbeta11+ iNKT cells or 6B11+Vbeta11+ iNKT cells did not differ between asthma patients and controls. However, among Valpha24+Vbeta11+iNKT cells, the proportion of IL-4+iNKT cells was increased in asthma patients compared to controls (7.0+/-3.0% vs 0.5+/-0.4%, P<0.05). There were no differences in the proportions of IL-10+or IFN-gamma+iNKT cells between the groups. The proportion of IL-4+ cells among 6B11+Vbeta11+iNKT cells inversely correlated with FEV1, expressed as a percentage predicted value in asthma patients (Rs=-0.64, P<0.05, n=19). CONCLUSIONS: Blood iNKT cells are thought to be Th2-like, and IL-4-producing iNKT cells may be associated with lung function in human asthma.

TLR4, 5, and 9 Agonists Inhibit Murine Airway Invariant Natural Killer T Cells in an IL-12-Dependent Manner

PURPOSE: Invariant natural killer T (iNKT) cells may play an important role in the pathogenesis of asthma in mice and humans. Thus, an agent that modulates the function of iNKT cells may have therapeutic potential to control asthma. We hypothesized that lipopolysaccharide (LPS)-, flagellin-, or CpG-induced changes in the cytokine milieu may modify and even inhibit the function of airway iNKT cells in asthma. METHODS: Because increased alpha-galactosylceramide (GalCer)-induced airway hyperreactivity (AHR) reflects the presence of airway iNKT cells, alpha-GalCer-induced AHR, as well as inflammatory cells and cytokines in bronchoalveolar lavage (BAL) fluid, were determined 24 hours after in vivo treatment with LPS, flagellin, or CpG in naive BALB/c mice. Intracellular IL-4 and IFN-gamma were measured in spleen iNKT cells after in vitro treatment with LPS, flagellin, or CpG. A role for IL-12 following the treatments was determined. RESULTS: Intranasal administration of LPS, flagellin, or CpG reduced development of alpha-GalCer-induced AHR, eosinophilic airway inflammation, and Th1 and Th2 cytokine responses in BAL fluid, while producing IL-12 in BAL fluid. Intraperitoneal administration of IL-12 mAb blocked the suppressive effect of LPS, flagellin, or CpG. In vitro treatment with LPS, flagellin, or CpG reduced production of IL-4 and IFN-gamma from alpha-GalCer-stimulated spleen iNKT cells; these effects were ameliorated by addition of anti-IL-12 mAb. CONCLUSIONS: TLR4, 5, and 9 agonists may suppress the function of airway and spleen iNKT cells via IL-12-dependent mechanisms. Anergy of iNKT cells by IL-12 might play a role in suppression by these TLR agonists.