title: Tetraspanin CD37 Regulates β2 Integrin-Mediated Adhesion and Migration in Neutrophils.
abstract: Deciphering the molecular basis of leukocyte recruitment is critical to the understanding of inflammation. In this study, we investigated the contribution of the tetraspanin CD37 to this key process. CD37-deficient mice showed impaired neutrophil recruitment in a peritonitis model. Intravital microscopic analysis indicated that the absence of CD37 impaired the capacity of leukocytes to follow a CXCL1 chemotactic gradient accurately in the interstitium. Moreover, analysis of CXCL1-induced leukocyte-endothelial cell interactions in postcapillary venules revealed that CXCL1-induced neutrophil adhesion and transmigration were reduced in the absence of CD37, consistent with a reduced capacity to undergo β2 integrin-dependent adhesion. This result was supported by in vitro flow chamber experiments that demonstrated an impairment in adhesion of CD37-deficient neutrophils to the β2 integrin ligand, ICAM-1, despite the normal display of high-affinity β2 integrins. Superresolution microscopic assessment of localization of CD37 and CD18 in ICAM-1-adherent neutrophils demonstrated that these molecules do not significantly cocluster in the cell membrane, arguing against the possibility that CD37 regulates β2 integrin function via a direct molecular interaction. Moreover, CD37 ablation did not affect β2 integrin clustering. In contrast, the absence of CD37 in neutrophils impaired actin polymerization, cell spreading and polarization, dysregulated Rac-1 activation, and accelerated β2 integrin internalization. Together, these data indicate that CD37 promotes neutrophil adhesion and recruitment via the promotion of cytoskeletal function downstream of integrin-mediated adhesion.
authors.affiliation: Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria 3168, Australia;
authors.forename: Janet L
authors.initials: JL
authors.lastname: Wee
authors.affiliation: Monash Micro Imaging, Monash University, Clayton, Victoria 3800, Australia;
authors.forename: Keith E
authors.identifier: http://orcid.org/0000-0001-7261-3314
authors.initials: KE
authors.lastname: Schulze
authors.affiliation: Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia;
authors.forename: Eleanor L
authors.initials: EL
authors.lastname: Jones
authors.affiliation: Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria 3168, Australia;
authors.forename: Louisa
authors.identifier: http://orcid.org/0000-0003-1233-1168
authors.initials: L
authors.lastname: Yeung
authors.affiliation: Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria 3168, Australia;
authors.forename: Qiang
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: Burnet Institute, Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; and.
authors.forename: Candida F
authors.initials: CF
authors.lastname: Pereira
authors.affiliation: Monash Micro Imaging, Monash University, Clayton, Victoria 3800, Australia;
authors.forename: Adam
authors.initials: A
authors.lastname: Costin
authors.affiliation: Monash Micro Imaging, Monash University, Clayton, Victoria 3800, Australia;
authors.forename: Georg
authors.identifier: http://orcid.org/0000-0003-3596-2288
authors.initials: G
authors.lastname: Ramm
authors.affiliation: Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Annemiek B
authors.initials: AB
authors.lastname: van Spriel
authors.affiliation: Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria 3168, Australia;
authors.forename: Michael J
authors.identifier: http://orcid.org/0000-0003-2354-357X
authors.initials: MJ
authors.lastname: Hickey
authors.affiliation: Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; mark.wright@monash.edu.
authors.forename: Mark D
authors.identifier: http://orcid.org/0000-0002-2177-5214
authors.initials: MD
authors.lastname: Wright
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D018821:CD18 Antigens / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement / Q000235:genetics; D002478:Cells, Cultured; D054360:Chemokine CXCL1 / Q000378:metabolism; D002633:Chemotaxis / Q000235:genetics; D003599:Cytoskeleton / Q000276:immunology*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000502:physiology*; D011485:Protein Binding; D059470:Tetraspanins / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D018821:CD18 Antigens; C504565:Cd37 protein, mouse; D054360:Chemokine CXCL1; D059470:Tetraspanins; D018799:Intercellular Adhesion Molecule-1; D020830:rac1 GTP-Binding Protein