title: Rat middle cerebral artery occlusion is not a suitable model for the study of stroke-induced spontaneous infections.
abstract: BACKGROUND
  Infections related to stroke-induced immunodepression are an important complication causing a high rate of death in patients. Several experimental studies in mouse stroke models have described this process but it has never been tested in other species such as rats.
  
  
  METHODS
  Our study focused on the appearance of secondary systemic and pulmonary infections in ischemic rats, comparing with sham and naive animals. For that purpose, male Wistar rats were subjected to embolic middle cerebral artery occlusion (eMCAO) or to transient MCAO (tMCAO) inserting a nylon filament. Forty-eight hours after ischemia, blood and lung samples were evaluated.
  
  
  RESULTS
  In eMCAO set, ischemic rats showed a significant decrease in blood-peripheral lymphocytes (naive = 58.8±18.1%, ischemic = 22.9±16.4%) together with an increase in polymorphonuclears (PMNs) (naive = 29.2±14.7%, ischemic = 71.7±19.5%), while no change in monocytes was observed. The increase in PMNs counts was positively correlated with worse neurological outcome 48 hours after eMCAO (r = 0.55, p = 0.043). However, sham animals showed similar changes in peripheral leukocytes as those seen in ischemic rats (lymphocytes: 40.1±19.7%; PMNs: 51.7±19.2%). Analysis of bacteriological lung growth showed clear differences between naive (0±0 CFU/mL; log10) and both sham (3.9±2.5 CFU/mL; log10) and ischemic (4.3±2.9 CFU/mL; log10) groups. Additionally, naive animals presented non-pathological lung histology, while both sham and ischemic showed congestion, edema or hemorrhage. Concordant results were found in the second set of animals submitted to a tMCAO.
  
  
  CONCLUSIONS
  Inflammatory and infection changes in Wistar rats subjected to MCAO models may be attributed not only to the brain ischemic injury but to the surgical aggression and/or anaesthetic stress. Consequently, we suggest that stroke-induced immunodepression in ischemic experimental models should be interpreted with caution in further experimental and translational studies, at least in rat stroke models that entail cervicotomy and cranial trepanation.
authors.affiliation: Neurovascular Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Mireia
authors.initials: M
authors.lastname: Campos-Martorell
authors.affiliation: Neurovascular Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Hernández-Guillamón
authors.affiliation: Neurovascular Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Rosell
authors.affiliation: Infectious Diseases Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Gomis
authors.affiliation: Neurovascular Unit, Department of Neurology, Universitat Autònoma de Barcelona, Hospital Vall d' Hebron, Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Salat
authors.affiliation: Neurovascular Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: García-Bonilla
authors.affiliation: Neurovascular Research Laboratory, Institut de Recerca Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain; Neurovascular Unit, Department of Neurology, Universitat Autònoma de Barcelona, Hospital Vall d' Hebron, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Montaner
mesh_terms: D000818:Animals; D060085:Coinfection / Q000209:etiology* / Q000276:immunology; D004195:Disease Models, Animal; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000276:immunology; D016131:Lymphocyte Subsets; D008297:Male; D011183:Postoperative Complications / Q000276:immunology; D051381:Rats; D017208:Rats, Wistar; D012141:Respiratory Tract Infections / Q000209:etiology* / Q000276:immunology; D018805:Sepsis / Q000209:etiology* / Q000276:immunology