title: Integrin Cross-Talk Regulates the Human Neutrophil Response to Fungal β-Glucan in the Context of the Extracellular Matrix: A Prominent Role for VLA3 in the Antifungal Response.
abstract: Candida albicans infection produces elongated hyphae resistant to phagocytic clearance compelling alternative neutrophil effector mechanisms to destroy these physically large microbial structures. Additionally, all tissue-based neutrophilic responses to fungal infections necessitate contact with the extracellular matrix (ECM). Neutrophils undergo a rapid, ECM-dependent mechanism of homotypic aggregation and NETosis in response to C. albicans mediated by the β2integrin, complement receptor 3 (CR3, CD11b/CD18, αMβ2). Neither homotypic aggregation nor NETosis occurs when human neutrophils are exposed either to immobilized fungal β-glucan or to C. albicans hyphae without ECM. The current study provides a mechanistic basis to explain how matrix controls the antifungal effector functions of neutrophils under conditions that preclude phagocytosis. We show that CR3 ligation initiates a complex mechanism of integrin cross-talk resulting in differential regulation of the β1integrins VLA3 (α3β1) and VLA5 (α5β1). These β1integrins control distinct antifungal effector functions in response to either fungal β-glucan or C. albicans hyphae and fibronectin, with VLA3 inducing homotypic aggregation and VLA5 regulating NETosis. These integrin-dependent effector functions are controlled temporally whereby VLA5 and CR3 induce rapid, focal NETosis early after binding fibronectin and β-glucan. Within minutes, CR3 undergoes inside-out auto-activation that drives the downregulation of VLA5 and the upregulation of VLA3 to support neutrophil swarming and aggregation. Forcing VLA5 to remain in the activated state permits NETosis but prevents homotypic aggregation. Therefore, CR3 serves as a master regulator during the antifungal neutrophil response, controlling the affinity states of two different β1integrins, which in turn elicit distinct effector functions.
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.|Graduate Program in Pathobiology, Brown University, Providence, RI 02912.
authors.forename: Courtney M
authors.initials: CM
authors.lastname: Johnson
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.
authors.forename: Xian M
authors.initials: XM
authors.lastname: O'Brien
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.|Graduate Program in Pathobiology, Brown University, Providence, RI 02912.
authors.forename: Angel S
authors.initials: AS
authors.lastname: Byrd
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Graduate Program in Pathobiology, Brown University, Providence, RI 02912.
authors.forename: Valentina E
authors.initials: VE
authors.lastname: Parisi
authors.affiliation: Department of Physics, Brown University, Providence, RI 02912.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Loosely
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.|Graduate Program in Pathobiology, Brown University, Providence, RI 02912.
authors.forename: Hadley
authors.initials: H
authors.lastname: Witt
authors.affiliation: Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612.
authors.forename: Mohd H
authors.initials: MH
authors.lastname: Faridi
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.
authors.forename: Craig T
authors.initials: CT
authors.lastname: LeFort
authors.affiliation: Department of Internal Medicine, Rush University Medical Center, Chicago, IL 60612.
authors.forename: Vineet
authors.initials: V
authors.lastname: Gupta
authors.affiliation: David H. Smith Center for Vaccine Biology and Immunology, Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642.
authors.forename: Minsoo
authors.initials: M
authors.lastname: Kim
authors.affiliation: Division of Surgical Research, Department of Surgery, Rhode Island Hospital, Providence, RI 02903.|Warren Alpert Medical School, Brown University, Providence, RI 02912.|Graduate Program in Pathobiology, Brown University, Providence, RI 02912.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Reichner
mesh_terms: D002176:Candida albicans / Q000276:immunology; D002469:Cell Separation; D005109:Extracellular Matrix / Q000276:immunology*; D065206:Extracellular Traps / Q000276:immunology*; D031541:Fluorescence Resonance Energy Transfer; D005656:Fungal Proteins / Q000276:immunology; D006801:Humans; D039201:Integrin alpha3beta1 / Q000276:immunology*; D016177:Macrophage-1 Antigen / Q000276:immunology; D008855:Microscopy, Electron, Scanning; D009504:Neutrophils / Q000276:immunology*; D020239:Receptor Cross-Talk / Q000276:immunology; D047071:beta-Glucans / Q000276:immunology*
chemical_list: D005656:Fungal Proteins; D039201:Integrin alpha3beta1; D016177:Macrophage-1 Antigen; D047071:beta-Glucans