title: CD4+ T cell-mediated neuroprotection is independent of T cell-derived BDNF in a mouse facial nerve axotomy model.
abstract: BACKGROUND
  The production of neurotrophic factors, such as BDNF, has generally been considered an important mechanism of immune-mediated neuroprotection. However, the ability of T cells to produce BDNF remains controversial.
  
  
  METHODS
  In the present study, we examined mRNA and protein of BDNF using RT-PCR and western blot, respectively, in purified and reactivated CD4(+) T cells. In addition, to determine the role of BDNF derived from CD4(+) T cells, the BDNF gene was specifically deleted in T cells using the Cre-lox mouse model system.
  
  
  RESULTS
  Our results indicate that while both mRNA expression and protein secretion of BDNF in reactivated T cells were detected at 24 h, only protein could be detected at 72 h after reactivation. The results suggest a transient up-regulation of BDNF mRNA in reactivated T cells. Furthermore, in contrast to our hypothesis that the BDNF expression is necessary for CD4(+) T cells to mediate neuroprotection, mice with CD4(+) T cells lacking BDNF expression demonstrated a similar level of facial motoneuron survival compared to their littermates that expressed BDNF, and both levels were comparable to wild-type. The results suggest that the deletion of BDNF did not impair CD4(+) T cell-mediated neuroprotection.
  
  
  CONCLUSIONS
  Collectively, while CD4(+) T cells are a potential source of BDNF after nerve injury, production of BDNF is not necessary for CD4(+) T cells to mediate their neuroprotective effects.
authors.affiliation: Neuroscience Institute, Loyola University Medical Center, IL 60153, USA. jxin@lumc.edu
authors.forename: Junping
authors.initials: J
authors.lastname: Xin
authors.forename: Nichole A
authors.initials: NA
authors.lastname: Mesnard
authors.forename: Taylor
authors.initials: T
authors.lastname: Beahrs
authors.forename: Derek A
authors.initials: DA
authors.lastname: Wainwright
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Serpe
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Alexander
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Sanders
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Jones
mesh_terms: D000818:Animals; D019771:Axotomy; D015153:Blotting, Western; D019208:Brain-Derived Neurotrophic Factor / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002452:Cell Count; D002470:Cell Survival / Q000502:physiology; D020220:Facial Nerve Injuries / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D051379:Mice; D018345:Mice, Knockout; D009046:Motor Neurons / Q000502:physiology; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012313:RNA