title: Complement system activation contributes to the ependymal damage induced by microbial neuraminidase.
abstract: In the rat brain, a single intracerebroventricular injection of neuraminidase from Clostridium perfringens induces ependymal detachment and death. This injury occurs before the infiltration of inflammatory blood cells; some reports implicate the complement system as a cause of these injuries. Here, we set out to test the role of complement.
  
  
  
  The assembly of the complement membrane attack complex on the ependymal epithelium of rats injected with neuraminidase was analyzed by immunohistochemistry. Complement activation, triggered by neuraminidase, and the participation of different activation pathways were analyzed by Western blot. In vitro studies used primary cultures of ependymal cells and explants of the septal ventricular wall. In these models, ependymal cells were exposed to neuraminidase in the presence or absence of complement, and their viability was assessed by observing beating of cilia or by trypan blue staining. The role of complement in ependymal damage induced by neuraminidase was analyzed in vivo in two rat models of complement blockade: systemic inhibition of C5 by using a function blocking antibody and testing in C6-deficient rats.
  
  
  
  The complement membrane attack complex immunolocalized on the ependymal surface in rats injected intracerebroventricularly with neuraminidase. C3 activation fragments were found in serum and cerebrospinal fluid of rats treated with neuraminidase, suggesting that neuraminidase itself activates complement. In ventricular wall explants and isolated ependymal cells, treatment with neuraminidase alone induced ependymal cell death; however, the addition of complement caused increased cell death and disorganization of the ependymal epithelium. In rats treated with anti-C5 and in C6-deficient rats, intracerebroventricular injection of neuraminidase provoked reduced ependymal alterations compared to non-treated or control rats. Immunohistochemistry confirmed the absence of membrane attack complex on the ependymal surfaces of neuraminidase-exposed rats treated with anti-C5 or deficient in C6.
  
  
  
  These results demonstrate that the complement system contributes to ependymal damage and death caused by neuraminidase. However, neuraminidase alone can induce moderate ependymal damage without the aid of complement.
authors.affiliation: Departamento de Biología Celular, Genética y Fisiología, IBIMA, Facultad de Ciencias, Universidad de Málaga, Málaga, 29071, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Granados-Durán
authors.affiliation: Departamento de Biología Celular, Genética y Fisiología, IBIMA, Facultad de Ciencias, Universidad de Málaga, Málaga, 29071, Spain.
authors.forename: María Dolores
authors.initials: MD
authors.lastname: López-Ávalos
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Hughes
authors.affiliation: Alexion Pharmaceuticals Inc., 352 Knotter Drive, Cheshire, CT, 06410, USA.
authors.forename: Krista
authors.initials: K
authors.lastname: Johnson
authors.affiliation: Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: B Paul
authors.initials: BP
authors.lastname: Morgan
authors.affiliation: Alexion Pharmaceuticals Inc., 352 Knotter Drive, Cheshire, CT, 06410, USA.
authors.forename: Paul P
authors.initials: PP
authors.lastname: Tamburini
authors.affiliation: Departamento de Biología Celular, Genética y Fisiología, IBIMA, Facultad de Ciencias, Universidad de Málaga, Málaga, 29071, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Fernández-Llebrez
authors.affiliation: Departamento de Biología Celular, Genética y Fisiología, IBIMA, Facultad de Ciencias, Universidad de Málaga, Málaga, 29071, Spain. grondona@uma.es.
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Grondona
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002478:Cells, Cultured; D058565:Cerebral Ventriculitis / Q000139:chemically induced* / Q000473:pathology*; D003176:Complement C3 / Q000378:metabolism; D003182:Complement C5 / Q000276:immunology / Q000378:metabolism; D003183:Complement C6 / Q000187:drug effects / Q000235:genetics; D015938:Complement Membrane Attack Complex / Q000378:metabolism*; D004195:Disease Models, Animal; D004805:Ependyma / Q000166:cytology / Q000293:injuries* / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D007276:Injections, Intraventricular; D037102:Lectins / Q000378:metabolism; D008297:Male; D009439:Neuraminidase / Q000633:toxicity*; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014746:Vimentin / Q000378:metabolism
chemical_list: D000906:Antibodies; D003176:Complement C3; D003182:Complement C5; D003183:Complement C6; D015938:Complement Membrane Attack Complex; D037102:Lectins; D014746:Vimentin; D009439:Neuraminidase
keywords: Anti-C5; Brain ventricles; C6-deficient rats; Complement system; Ependymal cells; Inflammation; Neuraminidase