title: mTOR pathway inhibition prevents neuroinflammation and neuronal death in a mouse model of cerebral palsy.
abstract: OBJECTIVE
  Mammalian target of rapamycin (mTOR) pathway signaling governs cellular responses to hypoxia and inflammation including induction of autophagy and cell survival. Cerebral palsy (CP) is a neurodevelopmental disorder linked to hypoxic and inflammatory brain injury however, a role for mTOR modulation in CP has not been investigated. We hypothesized that mTOR pathway inhibition would diminish inflammation and prevent neuronal death in a mouse model of CP.
  
  
  METHODS
  Mouse pups (P6) were subjected to hypoxia-ischemia and lipopolysaccharide-induced inflammation (HIL), a model of CP causing neuronal injury within the hippocampus, periventricular white matter, and neocortex. mTOR pathway inhibition was achieved with rapamycin (an mTOR inhibitor; 5mg/kg) or PF-4708671 (an inhibitor of the downstream p70S6kinase, S6K, 75 mg/kg) immediately following HIL, and then for 3 subsequent days. Phospho-activation of the mTOR effectors p70S6kinase and ribosomal S6 protein and expression of hypoxia inducible factor 1 (HIF-1α) were assayed. Neuronal cell death was defined with Fluoro-Jade C (FJC) and autophagy was measured using Beclin-1 and LC3II expression. Iba-1 labeled, activated microglia were quantified.
  
  
  RESULTS
  Neuronal death, enhanced HIF-1α expression, and numerous Iba-1 labeled, activated microglia were evident at 24 and 48 h following HIL. Basal mTOR signaling, as evidenced by phosphorylated-S6 and -S6K levels, was unchanged by HIL. Rapamycin or PF-4,708,671 treatment significantly reduced mTOR signaling, neuronal death, HIF-1α expression, and microglial activation, coincident with enhanced expression of Beclin-1 and LC3II, markers of autophagy induction.
  
  
  CONCLUSIONS
  mTOR pathway inhibition prevented neuronal death and diminished neuroinflammation in this model of CP. Persistent mTOR signaling following HIL suggests a failure of autophagy induction, which may contribute to neuronal death in CP. These results suggest that mTOR signaling may be a novel therapeutic target to reduce neuronal cell death in CP.
authors.affiliation: Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, United States.
authors.forename: Isha N
authors.initials: IN
authors.lastname: Srivastava
authors.affiliation: Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, United States.
authors.forename: Jona
authors.initials: J
authors.lastname: Shperdheja
authors.affiliation: Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, United States.
authors.forename: Marianna
authors.initials: M
authors.lastname: Baybis
authors.affiliation: Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, United States.
authors.forename: Tanya
authors.initials: T
authors.lastname: Ferguson
authors.affiliation: Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, United States. Electronic address: peter.crino@temple.edu.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Crino
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002547:Cerebral Palsy / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D020925:Hypoxia-Ischemia, Brain; D008070:Lipopolysaccharides; D008810:Mice, Inbred C57BL; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D000893:Anti-Inflammatory Agents; D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
keywords: Autophagy; Cell death; Cerebral palsy; Inflammation; Microglia; Rapamycin; mTOR