It is therefore likely that IL-4R-α expression on airway epithelium might represent an important feedback mechanism through which IL-4 and IL-13-secreting immune cells enhance

Th2-cell immunity in ongoing immune responses. Interleukin 1α and IL-1β are among the first described members of the prototypical IL-1 cytokine family that also includes IL-18, IL-33 (IL-1F11), and many others. IL-1β is synthesized as a proform that requires cleavage via the inflammasome-caspase-1 axis to be secreted as a biologically active cytokine. There is renewed interest in the role of IL-1 and related cytokine family members in promoting asthmatic airway inflammation, due to new evidence in HDM-driven models of asthma, as well as to genetic polymorphism studies in human cells [45]. Indeed, initially it was thought that IL-1 played only a minor role https://www.selleckchem.com/products/ink128.html in asthma, as symptoms in the classical OVA-alum model of asthma were not reduced in IL-1R-deficient mice. [46, 47]. Using radiation-induced bone marrow chimeric mice and exploiting the natural route of pulmonary exposure to HDM allergen, we have recently found that IL-1R triggering on radioresistant PCI-32765 ic50 lung epithelial cells promotes the innate immune response to natural allergen [41]. Autocrine release of IL-1-α by HDM-exposed bronchial

epithelial cells leads to TSLP, GM-CSF, and IL-33 production by epithelial cells, and IL-1α is required for the development of Th2 immunity to HDM in vivo (Fig. 2) [41]. It is still unclear whether the inflammasome-caspase1-IL-1α axis is involved in asthma development as one group failed to see an effect of Nlrp3 deficiency on asthma development in their mouse model whereas other groups found a role when allergens were introduced via the skin or alum was used as an adjuvant [43, 48, 49]. Interleukin-33 has been shown to act upstream of the type-2 effector cytokine cascade, by stimulation of various innate and adaptive immune cells, and by inducing the apoptosis

of lung epithelial cells. Allergic asthma patients express Etoposide supplier higher levels of IL-33, as determined by mucosal biopsies, as compared with those of healthy subjects, and genetic association studies have identified SNPs in the lL-33 and IL-33R (T1/ST2) locus associated with asthma [50, 51]. In mice, neutralization of IL-33 blocks development of lung Th2 immunity to a number of allergens, such as HDM and peanuts, as well as to lung-dwelling parasites such as hookworms [41, 52, 53]. Numerous cells of the innate immune system, such as DCs, macrophages, basophils, mast cells, and eosinophils express T1/ST2 (the receptor for IL-33) and stimulation of these cells by IL-33 leads to prolonged survival and/or activation, often leading to increased Th2 immunity in mouse models of allergy and asthma [50, 52, 54-57]. Little is known, however, about the mechanism of IL-33 release from epithelial cells, endothelial cells, fibroblasts, and immune cells [58].