TAT-Hsp70 induces neuroprotection against stroke via anti-inflammatory actions providing appropriate cellular microenvironment for transplantation of neural precursor cells

J Cereb Blood Flow Metab. 2013 Nov;33(11):1778-88. doi: 10.1038/jcbfm.2013.126. Epub 2013 Jul 24.

Abstract

Heat-shock protein 70 (Hsp70) protects against cerebral ischemia, which is attributed to its chaperone activity. However, recent reports also describe pro-inflammatory actions of Hsp70 via activation of Toll-like receptors (TLR). Using membrane-permeable transactivator of transcription (TAT)-Hsp70, we analyzed TAT-Hsp70-induced neuroprotection and its underlying mechanism after cerebral ischemia in mice. Infusion of TAT-Hsp70 reduced infarct volume and enhanced blood-brain barrier integrity on day 3 poststroke, when given no later than 12 hours. The latter was associated with reduction of microglial activation, although upregulation of pro-inflammatory TLR-2/4 was observed both in verum and in control animals. Nevertheless, protein abundance and nuclear translocation of downstream nuclear factor kappa B (NF-κB) as well as proteasomal degradation of the NF-κB regulator Ikappa B alpha (IκB-α) were significantly reduced by TAT-Hsp70. TAT-Hsp70-induced neuroprotection and functional recovery were restricted to 4 weeks only. However, TAT-Hsp70 provided an appropriate extracellular milieu for delayed intravenous transplantation of adult neural precursor cells (NPCs). Thus, NPCs that were grafted 28 days poststroke induced long-term neuroprotection for at least 3 months, which was not due to integration of grafted cells but rather due to paracrine effects of transplanted NPCs. Conclusively, TAT-Hsp70 ameliorates postischemic inflammation via proteasome inhibition, thus providing an appropriate extracellular milieu for delayed NPC transplantation and culminating in long-term neuroprotection.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / administration & dosage
  • Anti-Inflammatory Agents / pharmacology
  • Anti-Inflammatory Agents / therapeutic use*
  • HSP70 Heat-Shock Proteins / administration & dosage
  • HSP70 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / pharmacology
  • HSP70 Heat-Shock Proteins / therapeutic use*
  • Ischemic Attack, Transient / drug therapy
  • Ischemic Attack, Transient / immunology
  • Ischemic Attack, Transient / pathology
  • Ischemic Attack, Transient / therapy
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microglia / drug effects
  • Microglia / immunology
  • Microglia / pathology
  • Neural Stem Cells / transplantation*
  • Neuroprotective Agents / administration & dosage
  • Neuroprotective Agents / pharmacology
  • Neuroprotective Agents / therapeutic use*
  • Recombinant Fusion Proteins / administration & dosage
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / pharmacology
  • Recombinant Fusion Proteins / therapeutic use
  • Stem Cell Transplantation
  • Stroke / drug therapy*
  • Stroke / immunology
  • Stroke / pathology
  • Stroke / therapy
  • tat Gene Products, Human Immunodeficiency Virus / genetics*

Substances

  • Anti-Inflammatory Agents
  • HSP70 Heat-Shock Proteins
  • Neuroprotective Agents
  • Recombinant Fusion Proteins
  • tat Gene Products, Human Immunodeficiency Virus