Gαi2 Signaling Regulates Inflammasome Priming and Cytokine Production by Biasing Macrophage Phenotype Determination
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Gαi2 Signaling Regulates Inflammasome Priming and Cytokine Production by Biasing Macrophage Phenotype Determination This information is current as Ali Vural, Neel R. Nabar, Il-Young Hwang, Silke Sohn, of September 26, 2021. Chung Park, Mikael C. I. Karlsson, Joe B. Blumer and John H. Kehrl J Immunol published online 25 January 2019 http://www.jimmunol.org/content/early/2019/01/24/jimmun ol.1801145 Downloaded from Why The JI? Submit online. http://www.jimmunol.org/ • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on September 26, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2019 by The American Association of Immunologists, Inc. All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. Published January 25, 2019, doi:10.4049/jimmunol.1801145 The Journal of Immunology Gai2 Signaling Regulates Inflammasome Priming and Cytokine Production by Biasing Macrophage Phenotype Determination Ali Vural,*,1,2 Neel R. Nabar,*,†,1 Il-Young Hwang,* Silke Sohn,† Chung Park,* Mikael C. I. Karlsson,† Joe B. Blumer,‡ and John H. Kehrl* Macrophages exist as innate immune subsets that exhibit phenotypic heterogeneity and functional plasticity. Their phenotypes are dictated by inputs from the tissue microenvironment. G-protein–coupled receptors are essential in transducing signals from the microenvironment, and heterotrimeric Ga signaling links these receptors to downstream effectors. Several Gai-coupled G-protein–coupled receptors have been implicated in macrophage polarization. In this study, we use genetically modified mice to investigate the role of Gai2 on inflammasome activity and macrophage polarization. We report that Gai2 in murine bone marrow– Downloaded from derived macrophages (BMDMs) regulates IL-1b release after activation of the NLRP3, AIM2, and NLRC4 inflammasomes. We 2/2 G184S/G184S show this regulation stems from the biased polarity of Gai2 deficient (Gnai2 ) and RGS-insensitive Gai2 (Gnai2 ) G184S/G184S BMDMs. We determined that although Gnai2 BMDMs (excess Gai2 signaling) have a tendency toward classically 2/2 activated proinflammatory (M1) phenotype, Gnai2 BMDMs (Gai2 deficient) are biased toward alternatively activated anti- inflammatory (M2) phenotype. Finally, we find that Gai2-deficient macrophages have increased Akt activation and IFN-b pro- duction but defects in ERK1/2 and STAT3 activation after LPS stimulation. Gai2-deficient macrophages also exhibit increased http://www.jimmunol.org/ STAT6 activation after IL-4 stimulation. In summary, our data indicates that excess Gai2 signaling promotes an M1 macrophage phenotype, whereas Gai2 signaling deficiency promotes an M2 phenotype. Understanding Gai2-mediated effects on macrophage polarization may bring to light insights regarding disease pathogenesis and the reprogramming of macrophages for the devel- opment of novel therapeutics. The Journal of Immunology, 2019, 202: 000–000. acrophages are critical mediators of innate immunity macrophages have heterogeneous and flexible phenotypes that are and participate in both the initial propagation of the dictated by signaling inputs from their microenvironment. Mac- M inflammatory response and later in the suppression of rophages are broadly classified as proinflammatory M1 macro- by guest on September 26, 2021 inflammation promoting a return to homeostasis (1). To do so, phages implicated in initiating and sustaining inflammation or anti-inflammatory M2 macrophages that produce high levels of *B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National IL-10 and promote tissue repair (2). Although progress has been Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, made, the signaling networks responsible for macrophage polari- † MD 20892; Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, zation remain unclear. 171 77 Stockholm, Sweden; and ‡Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425 G-protein–coupled receptors (GPCRs) play a central role in reg- 1A.V. and N.R.N. contributed equally to this work. ulating macrophage function, as lipid-based inflammatory mediators, 2Current address: Department of Pharmacology, Wayne State University School of vasoactive amines, complement fragments, and other inflammatory/ Medicine, Detroit, MI. anti-inflammatory stimuli activate signaling by GPCRs linked to ORCIDs: 0000-0002-1269-6338 (A.V.); 0000-0002-9704-3570 (N.R.N.); 0000-0002- heterotrimeric G-proteins (3). Typically, GPCR activation leads 7051-0933 (S.S.); 0000-0002-7819-5333 (C.P.); 0000-0002-0020-3815 (J.B.B.); to GTP nucleotide exchange on Ga, causing its dissociation from 0000-0002-6526-159X (J.H.K.). the Gbg heterodimer; this allows both GTP-bound Ga and Gbg Received for publication August 17, 2018. Accepted for publication December 19, heterodimers to activate their corresponding downstream effec- 2018. tor molecules. Signaling is terminated by the inherent GTPase This work was supported by the intramural program of the National Institutes of Allergy and Infectious Diseases. N.R.N. is supported in part by the Thomas Jefferson activity of Ga subunits, which hydrolyze GTP to GDP and cause University M.D., Ph.D. training program. the reassociation of GDP-bound Ga and Gbg. This cycle highlights A.V., N.R.N., and S.S. did the experimental work; A.V., N.R.N., M.C.I.K, and J.H.K. the importance of heterotrimeric G-proteins in cell signaling net- designed and analyzed the experiments; I.-Y.H., C.P., and J.B.B. provided knockout works, as they transduce environmental stimuli from cell surface mouse strains. A.V., N.R.N., and J.H.K. wrote and edited the manuscript. receptors to generate a coordinated biological response (4). Address correspondence and reprint requests to Dr. Neel R. Nabar and Dr. John H. Kehrl, B Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Insti- Apart from the classical GPCR/G-protein signaling paradigm, tute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Drive, there exist several regulatory proteins that modulate G-protein Room 11A01, Bethesda, MD 20892. E-mail addresses: [email protected] (N.R.N.) and signaling. The regulators of G-protein signaling (RGS) family [email protected] (J.H.K.) consists of more than 30 members and is defined by the presence of Abbreviations used in this article: AGS, activator of G-protein signaling; Arg1, Arginase 1; BMDM, bone marrow–derived macrophage; ChemR23, chemerin receptor 23; FPR2, an RGS domain (5, 6). RGS proteins act as GTPase accelerating formyl peptide receptor 2; GPCR, G-protein–coupled receptor; iNOS, inducible proteins (GAPs) for specific Ga subunits. They enhance the in- NO synthase; KI, knock-in; KO, knockout; PTX, pertussis toxin; RGS, regulator of trinsic GTPase activity of Ga by stabilizing the GTPase transition G-protein signaling; WT, wild-type. state, accelerating the intrinsic Ga GTPase activity by as much as Copyright Ó 2019 by The American Association of Immunologists, Inc. 0022-1767/19/$37.50 100-fold (6, 7). In this way, RGS proteins limit the duration of www.jimmunol.org/cgi/doi/10.4049/jimmunol.1801145 2 A CRITICAL ROLE FOR Gai2 IN MACROPHAGE POLARIZATION GPCR-mediated G-protein signaling, and G-proteins genetically previously described (32–35). All strains were backcrossed a minimum of modified to be RGS-insensitive proteins show higher basal levels of 12 times to C57BL/6J and experiments were performed using 6- to 14-wk- signaling (6). Conversely, the activators of G-protein signaling old mice with littermate controls. (AGS) family broadly functions as receptor independent activators Cell isolation and culture of G-proteins (8, 9). They do so by serving as alternative binding Bone marrow–derived macrophages (BMDMs) were prepared as previ- partners to influence subunit interactions independent of nucleotide ously described (36). Gai2-deficient macrophages were derived from exchange. Group II AGS proteins, including AGS3 and AGS4, are Gnai22/2 or Gnai2fl/flvav1-cre mice; no differences were observed be- of interest because of their high expression levels in macrophages tween strains. In certain experiments, pertussis toxin (PTX) (Sigma- (10). They exert their effects on heterotrimeric G-proteins through Aldrich) was added either on day 0 (50 ng/ml for days 0–2; 100 ng/ml their G-protein regulatory (GPR) motif, which allows them to bind for days 3–7) or on day 7 (200 ng/ml) overnight. Macrophages were M1 polarized using 1 mg/ml LPS from Escherichia coli (Enzo Life Sciences) to GDP-bound Ga, thereby regulating Gbg signaling (8). for4handpolarizedtowardM2bytreatmentwith20ng/mlmouse Several studies have shown that GPCRs can drive both M1 and M2 rIL-4 (R&D Systems) for 48 h. CD4+CD252 splenic Th cells were macrophage polarization (11). Specifically, formyl peptide receptor isolated by negative depletion using biotinylated Abs to B220