Project description:Chronic inflammation and localized alterations in immune cell function are suspected to contribute to the progression of endometriosis and its associated symptoms. In particular, the alarmin IL-33 is elevated in the plasma, peritoneal fluid, and endometriotic lesions from patients with endometriosis; however, the exact role of IL-33 in the pathophysiology of endometriosis is not well understood. In this study, we demonstrate, in both humans and a murine model, that IL-33 contributes to the expansion of group 2 innate lymphoid cells (ILC2s), and this IL-33-induced ILC2 expansion modulates the endometriosis lesion microenvironment. Importantly, we show that IL-33 drives hallmarks of severe endometriosis, including elevated inflammation, lesion proliferation, and fibrosis, and that this IL-33-induced aggravation is mediated by ILC2s. Finally, we demonstrate the functionality of IL-33 neutralization as a promising and potentially novel therapeutic avenue for treating the debilitating symptoms of endometriosis.
Project description:Rationale: The major cause of heart failure is myocardium death consequent to detrimental cardiac remodeling and fibrosis following myocardial infarction. The cardiac protective cytokine interleukin (IL)-33, which signals by ST2 receptor binding, is associated with group 2 innate lymphoid cell (ILC2) activation and regulates tissue homeostasis and repair following tissue injury in various tissues. However, the distribution and role of IL-33-responsive ILC2s in cardiac fibrosis remain unclear. In this study, we elucidated the roles of IL-33-responsive cardiac-resident ILC2s and IL-33-mediated immunomodulatory functions in cardiac fibrosis. Methods: We examined the distribution of cardiac ILC2s by using flow cytometry. The roles of IL-33-mediated ILC2 expansion in cardiac fibrosis was evaluated in the mouse model of catecholamine-induced cardiac fibrosis. ILC-deficient Rag2‒/‒IL2Rγc‒/‒ mice were implemented to determine the contribution of endogenous ILC in the progression of cardiac fibrosis. Histopathological assessments, speckle tracking echocardiography, and transcriptome profile analysis were performed to determine the effects of IL-33-mediated cardiac protective functions. Results: We identified the resident cardiac ILC2s, which share similar cell surface marker and transcriptional factor expression characteristics as peripheral blood and lung tissue ILC2s. IL-33 treatment induced ILC2 expansion via ST2. In vivo, ILC-deficient Rag2‒/‒IL2Rγc‒/‒ mice developed exacerbated cardiac fibrosis following catecholamine-induced stress cardiac injury. IL-33 treatment expanded cardiac ILC2s and revealed protective effects against cardiac tissue damage with reduced cardiomyocyte death, immune cell infiltration, tissue fibrosis, and improved myocardial function. Transcriptome analysis revealed that IL-33 attenuated extracellular matrix synthesis- and fibroblast activation-associated gene expressions. IL13-knockout or epidermal growth factor receptor (EGFR) inhibition abolished IL-33-mediated cardiac protective function, confirming IL-13 and EGFR signaling as crucial for IL-33-mediated cardioprotective responses. Moreover, ILC2-produced BMP-7 served as a novel anti-fibrotic factor to inhibit TGF-β1-induced cardiac fibroblast activation. Conclusion: Our findings indicate the presence of IL-33-responsive ILC2s in cardiac tissue and that IL-33-mediated ILC2 expansion affords optimal cardioprotective function via ILC2-derived factors. IL-33-mediated immunomodulation is thus a promising strategy to promote tissue repair and alleviate cardiac fibrosis following acute cardiac injury.
Project description:Clostridium difficile (C. difficile) incidence has tripled over the past 15 years and is attributed to the emergence of hypervirulent strains. While it is clear that C. difficile toxins cause damaging colonic inflammation, the immune mechanisms protecting from tissue damage require further investigation. Through a transcriptome analysis, we identify IL-33 as an immune target upregulated in response to hypervirulent C. difficile. We demonstrate that IL-33 prevents C. difficile-associated mortality and epithelial disruption independently of bacterial burden or toxin expression. IL-33 drives colonic group 2 innate lymphoid cell (ILC2) activation during infection and IL-33 activated ILC2s are sufficient to prevent disease. Furthermore, intestinal IL-33 expression is regulated by the microbiota as fecal microbiota transplantation (FMT) rescues antibiotic-associated depletion of IL-33. Lastly, dysregulated IL-33 signaling via the decoy receptor, sST2, predicts C. difficile-associated mortality in human patients. Thus, IL-33 signaling to ILC2s is an important mechanism of defense from C. difficile colitis.
Project description:IL-33 is an alarmin required for resistance to the parasite Toxoplasma gondii, but its role in innate resistance to this organism is unclear. Infection with T. gondii promotes increased stromal cell expression of IL-33, and levels of parasite replication correlate with release of IL-33 in affected tissues. In response to infection, a subset of innate lymphoid cells (ILC) emerges composed of IL-33R+ NK cells and ILC1s. In Rag1-/-mice, where NK cells and ILC1 production of IFN-γ mediate innate resistance to T. gondii, the loss of the IL-33R resulted in reduced ILC responses and increased parasite replication. Furthermore, administration of IL-33 to Rag1-/- mice resulted in a marked decrease in parasite burden, increased production of IFN-γ, and the recruitment and expansion of inflammatory monocytes associated with parasite control. These protective effects of exogenous IL-33 were dependent on endogenous IL-12p40 and the ability of IL-33 to enhance ILC production of IFN-γ. These results highlight that IL-33 synergizes with IL-12 to promote ILC-mediated resistance to T. gondii.
Project description:Group 2 innate lymphoid cells (ILC2s) are effector cells within the mucosa and key participants in type 2 immune responses in the context of allergic inflammation and infection. ILC2s develop in the bone marrow from common lymphoid progenitor cells, but little is known about how ILC2s egress from the bone marrow for hematogenous trafficking. In this study, we identified a critical role for IL-33, a hallmark peripheral ILC2-activating cytokine, in promoting the egress of ILC2 lineage cells from the bone marrow. Mice lacking IL-33 signaling had normal development of ILC2s but retained significantly more ILC2 progenitors in the bone marrow via augmented expression of CXCR4. Intravenous injection of IL-33 or pulmonary fungal allergen challenge mobilized ILC2 progenitors to exit the bone marrow. Finally, IL-33 enhanced ILC2 trafficking to the lungs in a parabiosis mouse model of tissue disruption and repopulation. Collectively, these data demonstrate that IL-33 plays a critical role in promoting ILC2 egress from the bone marrow.
Project description:Asthma is a complex disease that is promoted by dysregulated immunity and the presence of many cytokine and lipid mediators. Despite this, there is a paucity of data demonstrating the combined effects of multiple mediators in asthma pathogenesis. Group 2 innate lymphoid cells (ILC2s) have recently been shown to play important roles in the initiation of allergic inflammation; however, it is unclear whether lipid mediators, such as cysteinyl leukotrienes (CysLTs), which are present in asthma, could further amplify the effects of IL-33 on ILC2 activation and lung inflammation. In this article, we show that airway challenges with the parent CysLT, leukotriene C4 (LTC4), given in combination with low-dose IL-33 to naive wild-type mice, led to synergistic increases in airway Th2 cytokines, eosinophilia, and peribronchial inflammation compared with IL-33 alone. Further, the numbers of proliferating and cytokine-producing lung ILC2s were increased after challenge with both LTC4 and IL-33. Levels of CysLT1R, CysLT2R, and candidate leukotriene E4 receptor P2Y12 mRNAs were increased in ILC2s. The synergistic effect of LTC4 with IL-33 was completely dependent upon CysLT1R, because CysLT1R-/- mice, but not CysLT2R-/- mice, had abrogated responses. Further, CysLTs directly potentiated IL-5 and IL-13 production from purified ILC2s stimulated with IL-33 and resulted in NFAT1 nuclear translocation. Finally, CysLT1R-/- mice had reduced lung eosinophils and ILC2 responses after exposure to the fungal allergen Alternaria alternata Thus, CysLT1R promotes LTC4- and Alternaria-induced ILC2 activation and lung inflammation. These findings suggest that multiple pathways likely exist in asthma to activate ILC2s and propagate inflammatory responses.
Project description:Group 2 innate lymphoid cells (ILC2s) in mouse lungs are activated by the epithelium-derived alarmin IL-33. Activated ILC2s proliferate and produce IL-5 and IL-13 that drive allergic responses. In neonatal lungs, the occurrence of spontaneous activation of lung ILC2s is dependent on endogenous IL-33. Here, we report that neonatal lung ILC2 activation by endogenous IL-33 has significant effects on ILC2 functions in adulthood. Most neonatal lung ILC2s incorporated 5-bromo-2'-deoxyuridine (BrdU) and persisted into adulthood. BrdU+ ILC2s in adult lungs responded more intensely to IL-33 treatment compared with BrdU- ILC2s. In IL-33-deficient (KO) mice, lung ILC2s develop normally, but they are not activated in the neonatal period. Lung ILC2s in KO mice responded less intensely to IL-33 in adulthood compared with WT ILC2s. While there was no difference in the number of lung ILC2s, there were fewer IL-13+ ILC2s in KO mice compared with those in WT mice. The impaired responsiveness of ILC2s in KO mice was reversed by i.n. administrations of IL-33 in the neonatal period. These results suggest that activation of lung ILC2s by endogenous IL-33 in the neonatal period may "train" ILC2s seeding the lung after birth to become long-lasting resident cells that respond more efficiently to challenges later in life.
Project description:Group 2 innate lymphoid cells (ILC2s) reside in multiple organs in the body, where they play roles in immunity, tissue homeostasis, and metabolic regulation. However, little is known about the regulatory mechanisms of ILC2s in different organs. Here, we identified ILC2s in the mouse uterus and found that they express cell surface molecules, including the IL-33 receptor, ST2, that are roughly comparable to those expressed by lung ILC2s. Both in vivo and in vitro treatment with IL-33 induced type 2 cytokine production in uterine ILC2s, suggesting that they respond to IL-33 in a manner similar to ILC2s in other organs. Importantly, uterine ILC2s were nearly absent in ovariectomized mice and were increased in wild-type mice by estrogen administration, whereas lung ILC2s were unaffected by both ovariectomy and estrogen administration. Likewise, a marked reduction in uterine ILC2s was observed in mice deficient in estrogen receptor ? or estrogen receptor ?. Furthermore, uterine ILC2s highly expressed estrogen receptor ?, and in vitro culture of isolated uterine ILC2s with 17?-estradiol modified expression of a number of genes. Finally, an increased prevalence in neonatal mortality was observed in litters from dams lacking the IL-33 receptor, ST2. Taken together, our findings indicate that unlike lung IL2Cs, uterine ILC2s are regulated by female sex hormones, which may specialize them for specific physiological functions.
Project description:Although a number of studies have recently explored the contribution of the adaptive immunity in IL-33-mediated antitumor effects, innate immune involvement has been poorly characterized. Utilizing Rag1-/- mice (lacking T and B lymphocytes), we show in this study that either systemic administration of recombinant IL-33 or ectopic expression of IL-33 in melanoma cells is sufficient to inhibit tumor growth independent of adaptive antitumor immunity. We have demonstrated that IL-33-mediated antitumor effects depend on expansion and activation of NK cells. Interestingly, IL-33 also promoted the expansion of active type 2 innate lymphoid cells (ILC2s) via its receptor, ST2, which in turn inhibited NK activation and cytotoxicity. This IL-33-induced ILC2 activity coincided with greater expression of the immunosuppressive ectoenzyme CD73. Removal of CD73 from ILC2s in culture with NK cells resulted in markedly increased activation levels in NK cells, offering a potential mechanism by which ILC2s might suppress NK cell-mediated tumor killing. Thus, our data reveal an important contribution of IL-33-induced ILC2 to tumor growth by weakening NK cell activation and tumor killing, regardless of adaptive immunity.
Project description:Innate lymphoid cells (ILCs) are enriched at barrier surfaces, including the gastrointestinal tract. While most studies have focused on the balance between pathogenic group 1 ILCs (ILC1s) and protective ILC3s in maintaining gut homeostasis and during chronic intestinal inflammation, such as Crohn's disease (CD), less is known regarding ILC2s. Using an established murine model of CD-like ileitis, i.e., the SAMP1/YitFc (SAMP) mouse strain, we showed that ILC2s, compared with ILC1s and ILC3s, were increased within draining mesenteric lymph nodes and ilea of SAMP versus AKR (parental control) mice early, during the onset of disease. Gut-derived ILC2s from CD patients versus healthy controls were also increased and expanded, similarly to ILC1s, in greater proportion compared with ILC3s. Importantly, we report that the intracellular bacteria-sensing protein, nucleotide-binding oligomerization domaining-containing protein 2, encoded by Nod2, the first and strongest susceptibility gene identified for CD, promoted ILC2 expansion, which was dramatically reduced in SAMP mice lacking NOD2 and in SAMP mice raised under germ-free conditions. Furthermore, these effects occurred through a mechanism involving the IL-33/ST2 ligand-receptor pair. Collectively, our results indicate a functional link between NOD2 and ILC2s, regulated by the IL-33/ST2 axis, that mechanistically may contribute to early events leading to CD pathogenesis.