GPR17 as an Innate Sensor for Bacterial Peptidoglycan: Implications for Necrotizing Fasciitis

GPR17 as a Macrophage Sensor for Gram-Positive Peptidoglycan: Implications for Invasive Bacterial Infection | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article GPR17 as a Macrophage Sensor for Gram-Positive Peptidoglycan: Implications for Invasive Bacterial Infection Jay L Rothstein This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8968070/v2 This work is licensed under a CC BY 4.0 License Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Abstract Invasive gram-positive infections, including necrotizing fasciitis, streptococcal toxic shock syndrome, and staphylococcal sepsis, disproportionately strike otherwise healthy individuals, implying a dominant role for host genetic susceptibility in innate bacterial surveillance. Here we present transcriptomic, structural pharmacophore, and molecular docking evidence supporting GPR17, a G protein-coupled receptor phylogenetically intermediate between purinergic P2Y receptors and cysteinyl leukotriene receptors, as a candidate surface-expressed pattern recognition receptor for gram-positive peptidoglycan on tissue macrophages. Reanalysis of Human Protein Atlas single-cell RNA-seq data reveals that GPR17 is expressed predominantly on tissue macrophages (31.7 nTPM) and monocytes (12 to 18 nTPM), with markedly lower expression in lymphoid lineages (< 2 nTPM). AutoDock Vina docking of 15 compounds against the AlphaFold-predicted GPR17 structure identifies UDP-muramic acid (UDP-Mur), a peptidoglycan biosynthetic intermediate, as a high-affinity ligand for the GPR17 orthosteric pocket (− 7.2 kcal/mol), within 0.2 kcal/mol of UDP-glucose and UDP-galactose (− 7.4 kcal/mol each). N-acetylated peptidoglycan intermediates (UDP-MurNAc, UDP-GlcNAc) dock poorly (− 4.3 and − 4.4 kcal/mol), suggesting a steric constraint at the C2 position of the hexose ring. Critically, UDP-glucose has never been independently confirmed as a GPR17 agonist despite multiple attempts across at least eight functional assay platforms. We propose that UDP-glucose and UDP-galactose function as endogenous neutral antagonists that occupy the GPR17 orthosteric pocket without activating downstream signaling, while UDP-Mur may be the true agonist whose C3 lactyl ether likely provides the pharmacophoric contact necessary for receptor activation. This framework may resolve the longstanding GPR17 deorphanization controversy, establish a mechanistic basis for peptidoglycan surveillance through a mammalian GPCR, and provide a molecular explanation for the clinical association between NSAID use and adverse outcomes in invasive gram-positive infections, including necrotizing fasciitis. Immunology Infectious Diseases gram-positive infection GPR17 pattern recognition receptor innate immunity UDP-muramic acid macrophage GPCR genetic susceptibility peptidoglycan indomethacin NSAID pharmacophore necrotizing fasciitis molecular docking deorphanization Full Text Additional Declarations The authors declare potential competing interests as follows: Immunometabolism Development Corp supported this work. Cite Share Download PDF Status: Posted Version 2 posted You are reading this latest preprint version Show more versions Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8968070","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":610926482,"identity":"5cd7b4a6-89d7-40db-b241-cb844f32417f","order_by":0,"name":"Jay L Rothstein","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3UlEQVRIie3PsQrCMBCA4YSDc4ntmqC+Q6TgqA8j6OLmJEIVhK6uPklwtAR0ic5CF6tP0EHQzdTNpY2bYH7IZbkPEkJ8vl9sZw9d2gGEXuzFAieSLgm3BGRJ0J0QguUgtSTIjvmt2MZx2GjuZ/dJv40E8uu5gojTOJKp0VysglHWUUP7MIyiSQWRBpGnyY5LzXqZUGAJw5YDifnAkqlQC2cCXALr0ULpeiIMgjwmWmw0i1pUHRhCzV8Cg/QyS+IwXJtu8VTzQdhY5bcq8hGw93RdL6OPb7Z9Pp/vb3oB06pB6+97mPAAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-4697-8405","institution":"Immunometabolism Development Corp.","correspondingAuthor":true,"prefix":"","firstName":"Jay","middleName":"L","lastName":"Rothstein","suffix":""}],"badges":[],"createdAt":"2026-02-25 13:03:36","currentVersionCode":2,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8968070/v2","doiUrl":"https://doi.org/10.21203/rs.3.rs-8968070/v2","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106960856,"identity":"beb6796a-a2e5-4ddb-86d2-b2a9b455d62f","added_by":"auto","created_at":"2026-04-15 09:23:25","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":764660,"visible":true,"origin":"","legend":"","description":"","filename":"GPR17RSRevision2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8968070/v2_covered_ab3bb3d4-fc99-4e03-bdfd-705f05169875.pdf"}],"financialInterests":"The authors declare potential competing interests as follows: Immunometabolism Development Corp supported this work.","formattedTitle":"GPR17 as a Macrophage Sensor for Gram-Positive Peptidoglycan: Implications for Invasive Bacterial Infection","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Immunometabolism Development Corp","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"gram-positive infection, GPR17, pattern recognition receptor, innate immunity, UDP-muramic acid, macrophage, GPCR, genetic susceptibility, peptidoglycan, indomethacin, NSAID, pharmacophore, necrotizing fasciitis, molecular docking, deorphanization","lastPublishedDoi":"10.21203/rs.3.rs-8968070/v2","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8968070/v2","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eInvasive gram-positive infections, including necrotizing fasciitis, streptococcal toxic shock syndrome, and staphylococcal sepsis, disproportionately strike otherwise healthy individuals, implying a dominant role for host genetic susceptibility in innate bacterial surveillance. Here we present transcriptomic, structural pharmacophore, and molecular docking evidence supporting GPR17, a G protein-coupled receptor phylogenetically intermediate between purinergic P2Y receptors and cysteinyl leukotriene receptors, as a candidate surface-expressed pattern recognition receptor for gram-positive peptidoglycan on tissue macrophages. Reanalysis of Human Protein Atlas single-cell RNA-seq data reveals that GPR17 is expressed predominantly on tissue macrophages (31.7 nTPM) and monocytes (12 to 18 nTPM), with markedly lower expression in lymphoid lineages (\u0026lt;\u0026thinsp;2 nTPM). AutoDock Vina docking of 15 compounds against the AlphaFold-predicted GPR17 structure identifies UDP-muramic acid (UDP-Mur), a peptidoglycan biosynthetic intermediate, as a high-affinity ligand for the GPR17 orthosteric pocket (\u0026minus;\u0026thinsp;7.2 kcal/mol), within 0.2 kcal/mol of UDP-glucose and UDP-galactose (\u0026minus;\u0026thinsp;7.4 kcal/mol each). N-acetylated peptidoglycan intermediates (UDP-MurNAc, UDP-GlcNAc) dock poorly (\u0026minus;\u0026thinsp;4.3 and \u0026minus;\u0026thinsp;4.4 kcal/mol), suggesting a steric constraint at the C2 position of the hexose ring. Critically, UDP-glucose has never been independently confirmed as a GPR17 agonist despite multiple attempts across at least eight functional assay platforms. We propose that UDP-glucose and UDP-galactose function as endogenous neutral antagonists that occupy the GPR17 orthosteric pocket without activating downstream signaling, while UDP-Mur may be the true agonist whose C3 lactyl ether likely provides the pharmacophoric contact necessary for receptor activation. 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