title: CD300f immunoreceptor contributes to peripheral nerve regeneration by the modulation of macrophage inflammatory phenotype.
abstract: BACKGROUND
  It has recently become evident that activating/inhibitory cell surface immune receptors play a critical role in regulating immune and inflammatory processes in the central nervous system (CNS). The immunoreceptor CD300f expressed on monocytes, neutrophils, and mast cells modulates inflammation, phagocytosis, and outcome in models of autoimmune demyelination, allergy, and systemic lupus erythematosus. On the other hand, a finely regulated inflammatory response is essential to induce regeneration after injury to peripheral nerves since hematogenous macrophages, together with resident macrophages and de-differentiated Schwann cells, phagocyte distal axonal and myelin debris in a well-orchestrated inflammatory response. The possible roles and expression of CD300f and its ligands have not been reported under these conditions.
  
  
  METHODS
  By using quantitative PCR (QPCR) and CD300f-IgG2a fusion protein, we show the expression of CD300f and its ligands in the normal and crush injured sciatic nerve. The putative role of CD300f in peripheral nerve regeneration was analyzed by blocking receptor-ligand interaction with the same CD300f-IgG2a soluble receptor fusion protein in sciatic nerves of Thy1-YFP-H mice injected at the time of injury. Macrophage M1/M2 polarization phenotype was also analyzed by CD206 and iNOS expression.
  
  
  RESULTS
  We found an upregulation of CD300f mRNA and protein expression after injury. Moreover, the ligands are present in restricted membrane patches of Schwann cells, which remain stable after the lesion. The lesioned sciatic nerves of Thy1-YFP-H mice injected with a single dose of CD300f-IgG2a show long lasting effects on nerve regeneration characterized by a lower number of YFP-positive fibres growing into the tibial nerve after 10 days post lesion (dpl) and a delayed functional recovery when compared to PBS- or IgG2a-administered control groups. Animals treated with CD300f-IgG2a show at 10 dpl higher numbers of macrophages and CD206-positive cells and lower levels of iNOS expression than both control groups. At later time points (28 dpl), increased numbers of macrophages and iNOS expression occur.
  
  
  CONCLUSIONS
  Taken together, these results show that the pair CD300f ligand is implicated in Wallerian degeneration and nerve regeneration by modulating both the influx and phenotype of macrophages.
authors.affiliation: Neuroinflammation and Gene Therapy Laboratory, Institut Pasteur Montevideo, Mataojo 2020, CP 11400, Montevideo, Uruguay. Hugo.peluffo@pasteur.edu.uy.|Department of Histology and Embryology, Faculty of Medicine, UDELAR, Montevideo, Uruguay. Hugo.peluffo@pasteur.edu.uy.
authors.forename: Hugo
authors.initials: H
authors.lastname: Peluffo
authors.affiliation: Neuroinflammation and Gene Therapy Laboratory, Institut Pasteur Montevideo, Mataojo 2020, CP 11400, Montevideo, Uruguay. patricia.solari08@gmail.com.
authors.forename: Patricia
authors.initials: P
authors.lastname: Solari-Saquieres
authors.affiliation: Neuroinflammation and Gene Therapy Laboratory, Institut Pasteur Montevideo, Mataojo 2020, CP 11400, Montevideo, Uruguay. luchanegro@gmail.com.
authors.forename: Maria Luciana
authors.initials: ML
authors.lastname: Negro-Demontel
authors.affiliation: Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain. isaac.francos@uab.cat.
authors.forename: Isaac
authors.initials: I
authors.lastname: Francos-Quijorna
authors.affiliation: Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain. Xavier.Navarro@uab.es.
authors.forename: Xavier
authors.initials: X
authors.lastname: Navarro
authors.affiliation: Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain. ruben.lopez@uab.cat.
authors.forename: Ruben
authors.initials: R
authors.lastname: López-Vales
authors.affiliation: Immunobiology Group, CIBBIM-Nanomedicine Program, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autonoma de Barcelona, Barcelona, Spain. joan.sayos@vhir.org.
authors.forename: Joan
authors.initials: J
authors.lastname: Sayós
authors.affiliation: Neuroinflammation and Gene Therapy Laboratory, Institut Pasteur Montevideo, Mataojo 2020, CP 11400, Montevideo, Uruguay. nlago@pasteur.edu.uy.|Neurodegeneration Laboratory, Institut Pasteur Montevideo, Montevideo, Uruguay. nlago@pasteur.edu.uy.
authors.forename: Natalia
authors.initials: N
authors.lastname: Lago
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000235:genetics; D007249:Inflammation / Q000473:pathology*; D037181:Lectins, C-Type / Q000378:metabolism; D008024:Ligands; D008264:Macrophages / Q000473:pathology*; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D051379:Mice; D009409:Nerve Crush; D009416:Nerve Regeneration; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D010525:Peripheral Nerves / Q000473:pathology; D010587:Phagocytosis; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics*; D012583:Schwann Cells / Q000473:pathology; D020426:Sciatic Neuropathy / Q000473:pathology; D014855:Wallerian Degeneration / Q000473:pathology
chemical_list: C482560:CLM-1 protein, mouse; D007074:Immunoglobulin G; D037181:Lectins, C-Type; D008024:Ligands; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D052247:Nitric Oxide Synthase Type II