Role of stress granule activation in cardiomyocyte function in sepsis

Abstract

Sepsis is a life‐threatening organ dysfunction caused by a dysregulated host response to infection. It is the leading cause of mortality in Intensive Care Unit (ICU). Sepsis‐induced myocardial dysfunction (SIMD) is a major complication of the sepsis that contributes to high mortality of patients with sepsis. Stress granule (SG) is a cytoplasmic membraneless platform that is formed in response to cellular stresses. The role of SG in SIMD is unknown. The aim of present study is to understand whether activation of SG in cardiomyocytes (CM) plays a role in CM function in sepsis.MethodsCMs were treated with lipopolysaccharide (LPS). CM SG activation (eIF2α phosphorylation) and TNFα production were assessed with Western blot and ELISA, respectively. CM function was evaluated with intracellular cAMP. ISRIB or over‐expression of G3BP1 was employed interfering SG.ResultsChallenging CMs with LPS results in eIF2α phosphorylation, an increase in TNFα production, and a decrease in intracellular cAMP in response to dobutamine. Pharmacologically (ISRIB) or genetically inhibition (G3BP1 knock down) of SG leads to an exaggerated increase in TNFα expression. Further, SG inhibition results in enhanced decrease in CM function (decreased intracellular cAMP) in CM with LPS. Over‐expression of G3BP1 in CMs prevents LPS‐induced CM TNFα production and improves CM contractility.ConclusionOur results indicate that the cardiomyocyte stress granule activation plays a protective role of myocardial function in sepsis.