Putative role of protein kinase C in neurotoxic inflammation mediated by extracellular heat shock protein 70 after ischemia-reperfusion

Galina Dvoriantchikova, Andrea Rachelle C Santos, Ali M. Saeed, Xenia Dvoriantchikova, Dmitry V Ivanov

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Background: Sterile inflammation occurs in the absence of live pathogens and is an unavoidable consequence of ischemia-reperfusion (IR) injury in the central nervous system (CNS). It is known that toll-like receptor 4 (Tlr4) contributes to damage and sterile inflammation in the CNS mediated by IR. However, the mechanism of Tlr4 activation under sterile conditions in ischemic tissue is poorly understood. We performed this study to clarify the mechanism. To this end, we focused on the extracellular heat shock protein 70 (Hsp70), the prototypic Tlr4 ligand.Methods: Tlr4-, Myd88- and Trif-knockout animals, as well as C57BL/6 mice, were used for the wild type control. For the in vivo study, we used a mouse model of retinal IR injury. To test the role of protein kinase C (PKC) in IR injury, IR retinas were treated with the PKC inhibitors (polymyxin B and Gö6976) and retinal damage was evaluated by directly counting neurons in the ganglion cell layer of flat-mounted retinas seven days after IR. Primary retinal neurons (retinal ganglion cells) and glial cells were used for in vitro experiments. Quantitative RT-PCR, ELISA and western blot analysis were used to study the production of pro-inflammatory factors in IR retinas and in primary cell cultures.Results: We found significant accumulation of extracellular Hsp70 in a model of retinal IR injury. We noted that PKC was involved in Tlr4 signaling, and found that PKC inhibitors promoted neuroprotection by reducing pro-inflammatory activity in ischemic tissue. To put all of the pieces in the signaling cascade together, we performed an in vitro study. We found that PKC was critical to mediate the Hsp70-dependent pro-inflammatory response. At the same time, the contamination of Hsp70 preparations with low-dose endotoxin was not critical to mediate the production of pro-inflammatory factors. We found that extracellular Hsp70 can promote neuronal death at least, by mediating production of cytotoxic levels of tumor necrosis factor alpha, predominantly due to the Tlr4/Myd88 signaling cascade.Conclusions: Our findings suggest that PKC acts as a switch to amplify the pro-inflammatory activity of Hsp70/Tlr4 signaling, which is sufficient to mediate neuronal death.

Original languageEnglish
Article number81
JournalJournal of Neuroinflammation
Volume11
DOIs
StatePublished - Apr 23 2014

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Toll-Like Receptor 4
HSP70 Heat-Shock Proteins
Protein Kinase C
Reperfusion
Ischemia
Inflammation
Reperfusion Injury
Retina
Protein C Inhibitor
Protein Kinase Inhibitors
Central Nervous System
Retinal Neurons
Polymyxin B
Primary Cell Culture
Retinal Ganglion Cells
Inbred C57BL Mouse
Endotoxins
Neuroglia
Ganglia
Tumor Necrosis Factor-alpha

Keywords

  • Damage-associated molecular patterns (DAMPs)
  • Endotoxins
  • Extracellular heat shock protein 70 (Hsp70)
  • Ischemia-reperfusion (IR) injury
  • Neuronal death
  • Polymyxin B
  • Protein kinase C (PKC)
  • Sterile inflammation
  • Toll-like receptor 4 (Tlr4)

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Neurology
  • Immunology
  • Neuroscience(all)
  • Medicine(all)

Cite this

Putative role of protein kinase C in neurotoxic inflammation mediated by extracellular heat shock protein 70 after ischemia-reperfusion. / Dvoriantchikova, Galina; Santos, Andrea Rachelle C; Saeed, Ali M.; Dvoriantchikova, Xenia; Ivanov, Dmitry V.

In: Journal of Neuroinflammation, Vol. 11, 81, 23.04.2014.

Research output: Contribution to journalArticle

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AU - Ivanov, Dmitry V

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KW - Polymyxin B

KW - Protein kinase C (PKC)

KW - Sterile inflammation

KW - Toll-like receptor 4 (Tlr4)

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