Glutamine attenuation of cell death and inducible nitric oxide synthase expression following inflammatory cytokine-induced injury is dependent on heat shock factor-1 expression.
BACKGROUND
Glutamine (GLN) has been shown to improve outcome after experimental and clinical models of critical illness. Enhanced expression of heat shock protein (HSP) has been hypothesized to be responsible for this protection. The heat shock response has been shown to inhibit inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) production. This study tested the hypothesis that GLN-mediated activation of the HSP pathway is responsible for improved survival and attenuation of iNOS expression after an inflammatory cytokine-induced injury.


METHODS
Heat shock factor-1 (HSF-1) wild-type and knockout mouse embryonic fibroblasts (HSF-1+/+ and HSF-1-/-) were used in all experiments. Cells were treated with 0 mmol/L or 8 mmol/L GLN and cytomix (tumor necrosis factor-alpha, lipopolysaccharide, and interferon-gamma) in a concurrent treatment model once they had reached confluence. Cell viability was assayed with MTS/PMS mixture. Apoptosis and necrosis were assayed via immunohistochemistry. iNOS and HSP-70 expression were detected via Western blotting. NO production was measured using the Griess reagent.


RESULTS
GLN treatment significantly attenuated inflammatory cytokine-induced cell death and apoptosis in HSF-1+/+ cells vs 0 mmol/L GLN treatment; however, GLN's cellular protection was lost in HSF-1-/- cells. GLN supplementation attenuated cytomix-induced iNOS expression and NO production only in HSF-1+/+ cells. Further, GLN induced HSP-70 expression only in HSF-1+/+ cells.


CONCLUSIONS
This is the first demonstration that GLN-mediated cellular protection after inflammatory cytokine injury is due to HSF-1 expression and cellular capacity to activate an HSP response.
Peng
Zhi-Yong
ZY
Department of Anesthesiology, University of Colorado Health Science Center, Denver, 80262, USA.
Hamiel
Christine R
CR
Banerjee
Anirban
A
Wischmeyer
Paul E
PE
Friese
Randall S
RS
Wischmeyer
Paul
P
D000818:Animals; D015153:Blotting, Western; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000502:physiology; D015870:Gene Expression; D005786:Gene Expression Regulation; D005973:Glutamine / Q000494:pharmacology*; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D009336:Necrosis / Q000473:pathology; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000187:drug effects* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; C490017:Hsf1 protein, mouse; D014157:Transcription Factors; D005973:Glutamine; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II