title: Feline eosinophilic dermatoses: a retrospective immunohistochemical and ultrastructural study of extracellular matrix remodelling.
abstract: BACKGROUND
  Feline eosinophilic dermatoses (FEDs) are common diseases of cats with an unknown pathogenesis. They are histologically characterized by an eosinophilic infiltration and often by the presence of flame figures (FFs) and/or areas of loss of tissue architecture, here termed necrotic foci (NF). It has been postulated that an alteration in the degradation of the extracellular matrix could be responsible for these histological features. Matrix metalloproteinases (MMPs) are a group of proteases that are fundamental in extracellular matrix remodelling.
  
  
  OBJECTIVE
  The aim of the study was to investigate retrospectively the expression of a subgroup of MMPs, in particular MMP-2 and MMP-9 gelatinases, in FEDs. The expression of one of their inhibitors, TIMP-2, was also investigated in order to establish the role of these molecules in the pathogenesis of FEDs. The ultrastructural characteristics of extracellular matrix in FFs and NF were subsequently assessed.
  
  
  METHODS
  Fifty-one formalin-fixed, paraffin-embedded specimens from cutaneous and mucosal biopsies diagnosed as FEDs were investigated immunohistochemically. Two selected samples were processed for electron microscopy.
  
  
  RESULTS
  This study revealed an increased expression of MMP-2 in NF and a decreased expression of this gelatinase in FFs. An imbalance between MMP-2 and TIMP-2 was evident using immunohistochemistry. No significative results were observed for MMP-9 expression. Electron microscopy confirmed the lack of normal collagen fibres in NF, whereas in FFs only occasional, amorphous material was observed among normal collagen fibres.
  
  
  CONCLUSIONS
  Our study suggests that an imbalance in the expression of matrix metalloproteinases could be responsible for different morphological findings in FEDs. Further studies are needed to assess the role of matrix metalloproteinases in the pathogenesis of FEDs.
authors.affiliation: Department of Veterinary Medicine, University of Perugia, 06126, Perugia, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Porcellato
authors.forename: Andrea
authors.initials: A
authors.lastname: Giontella
authors.forename: Luca
authors.initials: L
authors.lastname: Mechelli
authors.forename: Emilia
authors.initials: E
authors.lastname: Del Rossi
authors.forename: Chiara
authors.initials: C
authors.lastname: Brachelente
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000201:enzymology / Q000276:immunology / Q000473:pathology*; D002415:Cats; D003872:Dermatitis / Q000201:enzymology / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D004802:Eosinophilia / Q000201:enzymology / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D005109:Extracellular Matrix / Q000473:pathology / Q000648:ultrastructure*; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology; D007150:Immunohistochemistry / Q000662:veterinary*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D012189:Retrospective Studies; D012867:Skin / Q000648:ultrastructure*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism
chemical_list: D019716:Tissue Inhibitor of Metalloproteinase-2; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9