Modulation of the IL-33/IL-13 Axis in Obesity by IL-13R α2 Jennifer Duffen, Melvin Zhang, Katherine Masek-Hammerman, Angela Nunez, Agnes Brennan, Jessica This information is current as E. C. Jones, Jeffrey Morin, Karl Nocka and Marion Kasaian of September 29, 2021. J Immunol published online 5 January 2018 http://www.jimmunol.org/content/early/2018/01/05/jimmun ol.1701256 Downloaded from Supplementary http://www.jimmunol.org/content/suppl/2018/01/05/jimmunol.170125 Material 6.DCSupplemental http://www.jimmunol.org/ Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision • No Triage! 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Published January 5, 2018, doi:10.4049/jimmunol.1701256 The Journal of Immunology Modulation of the IL-33/IL-13 Axis in Obesity by IL-13Ra2 Jennifer Duffen,* Melvin Zhang,* Katherine Masek-Hammerman,† Angela Nunez,‡ Agnes Brennan,* Jessica E. C. Jones,x Jeffrey Morin,‡ Karl Nocka,* and Marion Kasaian* In obesity, IL-13 overcomes insulin resistance by promoting anti-inflammatory macrophage differentiation in adipose tissue. En- dogenous IL-13 levels can be modulated by the IL-13 decoy receptor, IL-13Ra2, which inactivates and depletes the cytokine. In this study, we show that IL-13Ra2 is markedly elevated in adipose tissues of obese mice. Mice deficient in IL-13Ra2 had high expression of IL-13 response markers in adipose tissue, consistent with increased IL-13 activity at baseline. Moreover, exposure to the type 2 cytokine-inducing alarmin, IL-33, enhanced serum and tissue IL-13 concentrations and elevated tissue eosinophils, macrophages, and type 2 innate lymphoid cells. IL-33 also reduced body weight, fat mass, and fasting blood glucose levels. Strikingly, however, the IL-33–induced protection was greater in IL-13Ra2–deficient mice compared with wild-type littermates, Downloaded from and these changes were largely attenuated in mice lacking IL-13. Although IL-33 administration improved the metabolic profile in the context of a high fat diet, it also resulted in diarrhea and perianal irritation, which was enhanced in the IL-13Ra2–deficient mice. Weight loss in this group was associated with reduced food intake, which was likely related to the gastrointestinal effects. These findings outline both potentially advantageous and deleterious effects of a type 2–skewed immune response under conditions of metabolic stress, and identify IL-13Ra2 as a critical checkpoint in adipose tissues that limits the protective effects of the IL-33/ IL-13 axis in obesity. The Journal of Immunology, 2018, 200: 000–000. http://www.jimmunol.org/ besity is a growing epidemic, with high body mass index Whereas IL-13Ra1 can mediate cellular responses to both IL-4 (BMI) contributing to disease burden worldwide (1). and IL-13, an additional receptor form, IL-13Ra2, interacts with O Emerging evidence suggests that obesity is supported IL-13 but not IL-4. It is thought to act primarily as a decoy, and maintained by immune activation in metabolic tissues. The binding IL-13 with higher affinity than IL-13Ra1, and seques- lean state is characterized by a protective anti-inflammatory mi- tering IL-13 from the signaling receptor, thereby reducing Stat6- lieu in adipose tissue, consisting of eosinophils, type 2 innate mediated signaling activity (9). IL-13Ra2 also mediates efficient lymphoid cells (ILC2), T regulatory cells (Treg), and anti- internalization and depletion of extracellular IL-13 (10). Although inflammatory macrophages. In contrast, obesity is associated IL-13Ra2 lacks any known cytoplasmic signaling motif, its ability by guest on September 29, 2021 with a shift toward reduced eosinophilic inflammation, with ele- to mediate cellular activation responses is debated (11). In addi- vated proinflammatory macrophages and CD8+ T cells (2, 3). In tion to the membrane-bound receptor, mice but not humans have a mouse models of obesity, the Th2 cytokines IL-4 (4), IL-13 (5), soluble form of IL-13Ra2 (sIL-13Ra2) that is abundant in the and IL-5 (6) can promote glucose tolerance and insulin sensitivity. circulation (12, 13). In contrast to the IL-13Ra1/IL-4Ra signaling IL-4 and IL-13 polarize macrophages to an anti-inflammatory receptor, which is widely expressed, tissue expression of phenotype through the IL-13Ra1/IL-4R receptor (2), whereas IL-13Ra2 is normally very low, and is induced under conditions IL-5 signaling drives the development and recruitment of eosin- of high IL-13 release (14). In the absence of IL-13Ra2, circulating ophils (7). The association of type 2 cytokines with metabolic levels of IL-13 are reduced, suggesting that the soluble form acts regulation suggests that glycemic control may be achieved as a carrier of IL-13 in murine blood (15). Mice lacking IL-13Ra2 through cytokine manipulation (8). have elevated tissue IL-13, consistent with impaired cytokine clearance, and have enhanced IL-13 bioactivity due to impaired cytokine neutralization (15), leading to exacerbated fibrotic re- sponses (16, 17), increased smooth muscle contractility and epi- *Inflammation and Immunology Research Unit, Pfizer, Inc., Cambridge, MA 02139; thelial resistance (18), and aggravated atopic responses (19, 20) †Drug Safety Research and Development, Pfizer, Inc., Cambridge, MA 02139; driven by IL-13. Although the role of IL-13 in metabolic ho- ‡Comparative Medicine, Pfizer, Inc., Andover, MA 01810; and xInternal Medicine Research Unit, Pfizer, Inc., Cambridge, MA 02139 meostasis is becoming appreciated (21–23), the contribution of IL-13Ra2 to regulation of this response has not been explored. ORCID: 0000-0002-1656-296X (J.M.). The alarmin IL-33 is stored in epithelial cells, endothelial cells, Received for publication August 31, 2017. Accepted for publication December 11, 2017. and fibroblasts, and is released upon tissue damage to mediate local Address correspondence and reprint requests to Dr. Marion Kasaian, Pfizer Research, immune activation (24). A key effector mechanism is the IL-33– 1 Portland Street, Cambridge, MA 02139. E-mail address: marion.kasaian@pfizer. induced release of cytokines, principally IL-5 and IL-13, from com ILC2, Th2, mast cells, basophils, and other cell types expressing The online version of this article contains supplemental material. the cell surface IL-33 receptor, ST2 (24). Administration of IL-33 Abbreviations used in this article: BMI, body mass index; EMH, extramedullary to mice triggers a range of IL-13–dependent responses (25–28), hematopoiesis; eWAT, epididymal white adipose tissue; GI, gastrointestinal; HDL, but may also induce production of IL-4 and IL-5 (25, 28–31), high-density lipoprotein; HFD, high fat diet; ILC2, type 2 innate lymphoid cell; scWAT, s.c. WAT; sIL-13Ra2, soluble form of IL-13Ra2; Treg, T regulatory cell; either of which could modulate inflammation in adipose tissue VAT, visceral adipose tissue; wt, wild type. (4, 6, 32). IL-33 has been shown to protect mice from the meta- bolic consequences of obesity (29), but the extent to which this is Copyright Ó 2018 by The American Association of Immunologists, Inc. 0022-1767/18/$35.00 www.jimmunol.org/cgi/doi/10.4049/jimmunol.1701256 2 MODULATION OF THE IL-33/IL-13 AXIS IN OBESITY BY IL-13Ra2 dependent on induction of IL-13, as opposed to other cytokines, CD3e2CD52CD192CD42NK1.12CD11c2CD11b2F4/802FcεRla2. Eo- + + + has not been evaluated. sinophils were gated as CD45 CD11b SiglecF . In this study, we manipulated tissue IL-13 levels by blocking Analysis of circulating lipids depletion through IL-13Ra2, both in untreated mice and in mice driven to express high levels of endogenous IL-13 by adminis- Blood was collected by cardiac puncture and immediately following eu- thanasia by carbon dioxide. For serum measurements, blood was allowed to tration of IL-33. We examined effects on glucose homeostasis clot at room temperature for 2 h before centrifugation to separate the serum under conditions of a normal chow diet and high fat diet (HFD), for further analysis. Total cholesterol and high-density lipoprotein (HDL) and explored the IL-13 dependence of these responses. Our find- fraction were quantified in serum using the Siemens Advia 1800 Chemistry ings support that IL-33 regulation of metabolic homeostasis is Analyzer (Malvern, PA). Whole blood in EDTA was rocked at room temperature to mix thoroughly, then total cell differential was determined largely IL-13 dependent, and that extreme type 2 skewing fol- using the Siemens Advia 2120 hematology system. lowing IL-33 administration in the presence of IL-13Ra2 defi- ciency ameliorates the metabolic consequences of HFD. Although Protein quantification these observations suggest that manipulation of tissue IL-13 re- Flash-frozen adipose and liver tissue were weighed then homogenized in sponses could be beneficial in restoring glycemic control on HFD, Tissue Protein Extraction Reagent (Thermo Fisher Scientific, Waltham, these effects were accompanied by increased risk of gastrointes- MA) + protease inhibitors (Cell Signaling Technology, Danvers, MA) using tinal (GI) toxicity. the TissueLyser II (Qiagen, Germantown, MD). The samples were then centrifuged at 4˚C and the resulting supernatant used in subsequent assays. Mouse IL-13Ra2, leptin (R&D Systems), and insulin (Crystal Chem, Materials and Methods Downers Grove, IL) measurements were performed on serum and/or tissue homogenate samples by ELISA according to the manufacturer’s protocol.