Interleukin-33 (IL-33), a newly described member of the IL-1 family, is expressed by many cell types following pro-inflammatory stimulation and is thought to be released on cell lysis. The IL-33 ...receptor, consisting of ST2 and IL-1 receptor accessory protein, is also widely expressed, particularly by T helper 2 (T(H)2) cells and mast cells. IL-33 is host-protective against helminth infection and reduces atherosclerosis by promoting T(H)2-type immune responses. However, IL-33 can also promote the pathogenesis of asthma by expanding T(H)2 cells and mediate joint inflammation, atopic dermatitis and anaphylaxis by mast cell activation. Thus IL-33 could be a new target for therapeutic intervention across a range of diseases.
Alzheimer’s disease (AD) is a devastating condition with no known effective treatment. AD is characterized by memory loss as well as impaired locomotor ability, reasoning, and judgment. Emerging ...evidence suggests that the innate immune response plays a major role in the pathogenesis of AD. In AD, the accumulation of β-amyloid (Aβ) in the brain perturbs physiological functions of the brain, including synaptic and neuronal dysfunction, microglial activation, and neuronal loss. Serum levels of soluble ST2 (sST2), a decoy receptor for interleukin (IL)-33, increase in patients with mild cognitive impairment, suggesting that impaired IL-33/ST2 signaling may contribute to the pathogenesis of AD. Therefore, we investigated the potential therapeutic role of IL-33 in AD, using transgenic mouse models. Here we report that IL-33 administration reverses synaptic plasticity impairment and memory deficits in APP/PS1 mice. IL-33 administration reduces soluble Aβ levels and amyloid plaque deposition by promoting the recruitment and Aβ phagocytic activity of microglia; this is mediated by ST2/p38 signaling activation. Furthermore, IL-33 injection modulates the innate immune response by polarizing microglia/macrophages toward an antiinflammatory phenotype and reducing the expression of proinflammatory genes, including IL-1β, IL-6, and NLRP3, in the cortices of APP/PS1 mice. Collectively, our results demonstrate a potential therapeutic role for IL-33 in AD.
IL-33 has emerged as an important mediator in the immunopathogenesis of allergy and asthma. However, the role of IL-33 in eosinophil-mediated inflammation has not been fully explored. In this ...article, we report that IL-33 directly stimulates eosinophil differentiation from CD117(+) progenitors in an IL-5-dependent manner. Although resting eosinophils expressed moderate levels of the IL-33R alpha-chain (ST2L), eosinophils that accumulated in the airways of mice with OVA-induced asthma expressed increased amounts of ST2L. In vitro, IL-33 and GM-CSF are potent inducers of ST2L expression on eosinophils, and IL-33 induced the production of IL-13, CCL17, and TGF-beta by eosinophils. In adoptive-transfer experiments, IL-33 exacerbated eosinophil-mediated airway inflammation by increasing the levels of eosinophils, macrophages, lymphocytes, IL-13, TGF-beta, CCL3, CCL17, and CCL24 in the lungs. IL-33 also enhanced the eosinophil-mediated differentiation of airway macrophages toward the alternatively activated macrophage phenotype in an IL-13-dependent manner. Taken together, this study demonstrates that the IL-33/ST2 signaling pathway activates airway eosinophils that exacerbate airway inflammation in an autocrine and paracrine manner.
CD4(+) T cells have long been grouped into distinct helper subsets on the basis of their cytokine-secretion profile. In recent years, several subsets of innate lymphoid cell have been described as ...key producers of these same Th-associated cytokines. However, the functional relationship between Th cells and innate lymphoid cells (ILCs) remains unclear. We show in this study that lineage-negative ST2(+)ICOS(+)CD45(+) type 2 ILCs and CD4(+) T cells can potently stimulate each other's function via distinct mechanisms. CD4(+) T cell provision of IL-2 stimulates type 2 cytokine production by type 2 ILCs. By contrast, type 2 ILCs modulate naive T cell activation in a cell contact-dependent manner, favoring Th2 while suppressing Th1 differentiation. Furthermore, a proportion of type 2 ILCs express MHC class II and can present peptide Ag in vitro. Importantly, cotransfer experiments show that type 2 ILCs also can boost CD4(+) T cell responses to Ag in vivo.
Numerous pro-inflammatory cytokines have been implicated in the pathogenesis of several cardiovascular diseases. Interleukin (IL)-33 is a new member of the IL-1 family of cytokines that promotes Th2 ...type immune responses by signaling through the ST2L and IL-1RAcP dimeric receptor complex. Furthermore, the biological effects of IL-33 are limited by a soluble decoy form of ST2 (sST2). Recent studies indicate a protective role for IL-33 and ST2L in atherosclerosis, obesity and cardiac remodeling. The present review summarizes currently available data showing the role for IL-33 and its receptor ST2L within cardiovascular disease, and the potential use of sST2 as a predictive cardiovascular biomarker.
Background The initiation and regulation of pulmonary fibrosis are not well understood. IL-33, an important cytokine for respiratory diseases, is overexpressed in the lungs of patients with ...idiopathic pulmonary fibrosis. Objectives We aimed to determine the effects and mechanism of IL-33 on the development and severity of pulmonary fibrosis in murine bleomycin-induced fibrosis. Methods Lung fibrosis was induced by bleomycin in wild-type or Il33r ( St2 ) −/− C57BL/6 mice treated with the recombinant mature form of IL-33 or anti–IL-33 antibody or transferred with type 2 innate lymphoid cells (ILC2s). The development and severity of fibrosis was evaluated based on lung histology, collagen levels, and lavage cytology. Cytokine and chemokine levels were quantified by using quantitative PCR, ELISA, and cytometry. Results IL-33 is constitutively expressed in lung epithelial cells but is induced in macrophages by bleomycin. Bleomycin enhanced the production of the mature but reduced full-length form of IL-33 in lung tissue. ST2 deficiency, anti–IL-33 antibody treatment, or alveolar macrophage depletion attenuated and exogenous IL-33 or adoptive transfer of ILC2s enhanced bleomycin-induced lung inflammation and fibrosis. These pathologic changes were accompanied, respectively, by reduced or increased IL-33, IL-13, TGF-β1, and inflammatory chemokine production in the lung. Furthermore, IL-33 polarized M2 macrophages to produce IL-13 and TGF-β1 and induced the expansion of ILC2s to produce IL-13 in vitro and in vivo. Conclusions IL-33 is a novel profibrogenic cytokine that signals through ST2 to promote the initiation and progression of pulmonary fibrosis by recruiting and directing inflammatory cell function and enhancing profibrogenic cytokine production in an ST2- and macrophage-dependent manner.
Cerebral malaria (CM) is a complex parasitic disease caused by Plasmodium sp. Failure to establish an appropriate balance between pro- and anti-inflammatory immune responses is believed to contribute ...to the development of cerebral pathology. Using the blood-stage PbA (Plasmodium berghei ANKA) model of infection, we show here that administration of the pro-Th2 cytokine, IL-33, prevents the development of experimental cerebral malaria (ECM) in C57BL/6 mice and reduces the production of inflammatory mediators IFN-γ, IL-12 and TNF-α. IL-33 drives the expansion of type-2 innate lymphoid cells (ILC2) that produce Type-2 cytokines (IL-4, IL-5 and IL-13), leading to the polarization of the anti-inflammatory M2 macrophages, which in turn expand Foxp3 regulatory T cells (Tregs). PbA-infected mice adoptively transferred with ILC2 have elevated frequency of M2 and Tregs and are protected from ECM. Importantly, IL-33-treated mice deleted of Tregs (DEREG mice) are no longer able to resist ECM. Our data therefore provide evidence that IL-33 can prevent the development of ECM by orchestrating a protective immune response via ILC2, M2 macrophages and Tregs.
Interleukin (IL)-33 is a member of the IL-1 cytokine family that has been shown to play an important role in the induction and effector phases of type 2 immune responses. Both innate and adaptive ...immunity are regulated by IL-33, and many studies have shown disease-associated functions for this cytokine. Recently, IL-33 has been implicated in the function of novel innate lymphocyte populations that regulate both protective responses in parasitic infections and allergic airway inflammation. Here, we discuss recent data highlighting the dual roles of IL-33 in protective and deleterious immune responses.
IL‐33 is a novel cytokine of the IL‐1 family and mediates its biological effect via the receptor ST2, which is selectively expressed on Th2 cells but not Th1 cells. IL‐33 drives production of ...Th2‐associated cytokines including IL‐5 and IL‐13 and thereby promotes defense and pathology in mucosal organs. Cell locomotion is crucial to the induction of an effective immune response. We report here the chemoattraction of Th2 cells by IL‐33. Recombinant IL‐33 increased the proportion of human Th2 cells, but not Th1 cells, in polarized morphology in vitro and stimulated their subsequent invasion into collagen gels in an IL‐33 concentration‐dependent manner. Injection of recombinant IL‐33 into the footpad of ST2–/– mice which had been adoptively transferred with polarized Th2 cells, led to local accumulation of the transferred Th2 cells. These data therefore demonstrate that IL‐33 is a selective Th2 chemoattractant associated with the pro‐inflammatory property of this novel cytokine.
MicroRNA (miRNA) species (miR) regulate mRNA translation and are implicated as mediators of disease pathology via coordinated regulation of molecular effector pathways. Unraveling miR disease-related ...activities will facilitate future therapeutic interventions. miR-155 recently has been identified with critical immune regulatory functions. Although detected in articular tissues, the functional role of miR-155 in inflammatory arthritis has not been defined. We report here that miR-155 is up-regulated in synovial membrane and synovial fluid (SF) macrophages from patients with rheumatoid arthritis (RA). The increased expression of miR-155 in SF CD14⺠cells was associated with lower expression of the miR-155 target, Src homology 2-containing inositol phosphatase-1 (SHIP-1), an inhibitor of inflammation. Similarly, SHIP-1 expression was decreased in CD68⺠cells in the synovial lining layer in RA patients as compared with osteoarthritis patients. Overexpression of miR-155 in PB CD14⺠cells led to down-regulation of SHIP-1 and an increase in the production of proinflammatory cytokines. Conversely, inhibition of miR-155 in RA synovial CD14⺠cells reduced TNF-α production. Finally, miR-155-deficient mice are resistant to collagen-induced arthritis, with profound suppression of antigen-specific Th17 cell and autoantibody responses and markedly reduced articular inflammation. Our data therefore identify a role of miR-155 in clinical and experimental arthritis and suggest that miR-155 may be an intriguing therapeutic target.
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