title: Attenuation of acute stroke injury in rat brain by minocycline promotes blood-brain barrier remodeling and alternative microglia/macrophage activation during recovery.
abstract: BACKGROUND
  Minocycline reduces reperfusion injury by inhibiting matrix metalloproteinases (MMPs) and microglia activity after cerebral ischemia. Prior studies of minocycline investigated short-term neuroprotective effects during subacute stage of stroke; however, the late effects of minocycline against early reperfusion injury on neurovascular remodeling are less well studied. We have shown that spontaneous angiogenesis vessels in ischemic brain regions have high blood-brain barrier (BBB) permeability due to lack of major tight junction proteins (TJPs) in endothelial cells at three weeks. In the present study, we longitudinally investigated neurological outcome, neurovascular remodeling and microglia/macrophage alternative activation after spontaneous and minocycline-induced stroke recovery.
  
  
  METHODS
  Adult spontaneously hypertensive rats had a 90 minute transient middle cerebral artery occlusion. At the onset of reperfusion they received a single dose of minocycline (3 mg/kg intravenously) or a vehicle. They were studied at multiple time points up to four weeks with magnetic resonance imaging (MRI), immunohistochemistry and biochemistry.
  
  
  RESULTS
  Minocycline significantly reduced the infarct size and prevented tissue loss in the ischemic hemispheres compared to vehicle-treated rats from two to four weeks as measured with MRI. Cerebral blood flow measured with arterial spin labeling (ASL) showed that minocycline improved perfusion. Dynamic contrast-enhanced MRI indicated that minocycline reduced BBB permeability accompanied with higher levels of TJPs measured with Western blot. Increased MMP-2 and -3 were detected at four weeks. Active microglia/macrophage, surrounding and within the peri-infarct areas, expressed YM1, a marker of M2 microglia/macrophage activation, at four weeks. These microglia/macrophage expressed both pro-inflammatory factors tumor necrosis factors-α (TNF-α) and interleukin-1β (IL-1β) and anti-inflammatory factors transforming growth factor-β (TGF-β) and interleukin-10 (IL-10). Treatment with minocycline significantly reduced levels of TNF-α and IL-1β, and increased levels of TGF-β, IL-10 and YM1.
  
  
  CONCLUSIONS
  Early minocycline treatment against reperfusion injury significantly promotes neurovascular remodeling during stroke recovery by reducing brain tissue loss, enhancing TJP expression in ischemic brains and facilitating neuroprotective phenotype alternative activation of microglia/macrophages.
authors.affiliation: College of Pharmacy, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. yiyang@salud.unm.edu.
authors.forename: Yirong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. victors@salud.unm.edu.
authors.forename: Victor M
authors.initials: VM
authors.lastname: Salayandia
authors.affiliation: Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. jefthompson@salud.unm.edu.
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Thompson
authors.affiliation: Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. lisayyang@salud.unm.edu.
authors.forename: Lisa Y
authors.initials: LY
authors.lastname: Yang
authors.affiliation: Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. eesttrada@salud.unm.edu.
authors.forename: Eduardo Y
authors.initials: EY
authors.lastname: Estrada
authors.affiliation: Department of Neurology, University of New Mexico Health Sciences Center, 1 University of New Mexico, Albuquerque, NM, 87131, USA. yyang@salud.unm.edu.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy* / Q000473:pathology*; D008264:Macrophages / Q000187:drug effects*; D008279:Magnetic Resonance Imaging; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D017628:Microglia / Q000187:drug effects*; D008911:Minocycline / Q000627:therapeutic use*; D051381:Rats; D011918:Rats, Inbred SHR; D011938:Rec A Recombinases / Q000378:metabolism; D020127:Recovery of Function / Q000187:drug effects*; D015424:Reperfusion; D013997:Time Factors
chemical_list: D016207:Cytokines; D011938:Rec A Recombinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008911:Minocycline