An in vitro model to consider the effect of 2 mM glutamine and KNK437 on endotoxin-stimulated release of heat shock protein 70 and inflammatory mediators

What is known:
• Glutamine supplementation promotes heat shock protein 70 (HSP70) release in in vitro experimental models of sepsis.
• During times of infection, HSP70 signals via cell surface ligands TLR2/4 to activate the inflammatory pathway of NF-κB, promoting the release of inflammatory mediators.
• In an in vitro experimental model of sepsis, the HSP70 inhibitor KNK437 effectively blocks HSP70 release, diminishing the release of inflammatory mediators.What this study adds:
• The addition of 2 mM of glutamine to a whole blood endotoxin model promotes the release of HSP70.
• The effect of 2 mM glutamine on HSP70 release is lost after the addition of the HSP70 inhibitor KNK437 to an in vitro model of sepsis.

ObjectiveGlutamine has been shown to promote the release of heat shock protein 70 (HSP70) both within experimental in vitro models of sepsis and in adults with septic shock. This study aimed to investigate the effects of 2 mM glutamine and an inhibitor of HSP70 (KNK437) on the release of HSP70 and inflammatory mediators in healthy adult volunteers.MethodsAn in vitro whole blood endotoxin stimulation assay was used.ResultsThe addition of 2 mM glutamine significantly increased HSP70 levels over time (P < 0.05). HSP70 release had a positive correlation at 4 h with IL-1 β (r = 0.51, P = 0.03) and an inverse correlation with TNF-α (r = −0.56, P = 0.02) and IL-8 levels (r = −0.52, P = 0.03), and there were no significant correlations between HSP70 and IL6 or IL-10 or glutamine. Glutamine supplementation significantly (P < 0.05) attenuated the release of IL-10 at 4 h and IL-8 at 24 h, compared with conditions without glutamine. In endotoxin-stimulated blood there were no significant differences in the release of IL-6, TNF-α, and IL-1 β with glutamine supplementation at 4 and 24 h. However, glutamine supplementation (2 mM) appeared to attenuate the release of inflammatory mediators (IL-1 β, IL-6, TNF-α), although this effect was not statistically significant. The addition of KNK437, a HSP70 inhibitor, significantly diminished HSP70 release, which resulted in lower levels of inflammatory mediators (P < 0.05).ConclusionGlutamine supplementation promotes HSP70 release in an experimental model of sepsis. After the addition of KNK437, the effects of glutamine on HSP70 and inflammatory mediator release appear to be lost, suggesting that HSP70 in part orchestrates the inflammatory mediator response to sepsis. The clinical implications require further investigation.