Hsf1 Involved In G-csf-induced Cardiac Protection Against Ischemic Reperfusion Injury

Revascularization is the most effective therapy in ischemic heart disease, inducing cardiac ischemia reperfusion injury which causes oxidative stress and inflammation, undermining the benefits of revascularization. It is one of the highlights in the cardiovascular research that protecting the heart from ischemia reperfusion injury during revascularization.Ischemic conditioning is the modern strategy to triger the innate cardiac protection, including preconditioning and postconditioning. Howerver, the characteristics of these two methods preclude this approach from clinical application. As the mechanisms underlying are elucidated, more and more oppotunities for pharmacological intervention are revealed, in which G-CSF is one of the pop. The inconsistency among the clinical trials about G-CSF raises a posibility that complex clinical background may account, calling for the further research on G-CSF.Heat shock factor 1 (HSF1) and heat shock response is of great importance against miscellaneous stress. HSF1 is required in production of many heat shock proteins (HSP), which act as molecular chaperones assisting protein folding and transporting during growth, differentiation and other pathophysiological processes.It was reported that HSF1 plays a critical role in anti-apoptosis, anti-inflammation and improving cardiac function during ischemia reperfusion injury. But the expression and activation of HSF1 alter in different diseases. However, it remains unknown whether HSF1 participates in the cardiac protection of G-CSF, making for the further understanding. Rational-Granulocyte colony-stimulating factor (G-CSF) has been reported to protect cardiomyocytes (CM) from ischemic injury by activating reperfusion injury salvage kinases. Heat shock transcription factor 1 (HSF1), a definite protective factor in the heart, may involve in the protection of G-CSF.Objective-The present study was to investigate whether HSF1 is involved in G-CSF-induced cardiac protection after ischemia/reperfusion.Methods-In the present study, HSF1 knockout (KO) and their littermate wild type mice (WT) were administered with G-CSF (100μg/kg/day) or vehicle (saline) subcutaneously. Three days later, the mice were subjected to ischemia for 30 min and then reperfusion for 24 hr by temporary left anterior descending artery ligation. Estimate the cardiac function and infarction area by echocardiography, haemodynamics and sections. (2) After transfected with HSF1 siRNA, cardiomycytes treated with or without G-CSF were subjected to H2O2 for 24hr. Then staining with Annexin V to determine the apoptosis.Results - Comparing with vehicle treatment, G-CSF not only had a beneficial effect on cardiac functions characterized by a higher EF%, a lower LVEDP and a larger dP/dt value but also decreased infarction area in WT group. In HSF1 KO mice, however, these protective effects on cardiac dysfunction and infarction by G-CSF were declined. G-CSF could prevent the apoptosis of cardiomyocytes subjected to H2O2, which effect was eliminated when transfected with HSF1 siRNA.Conclusion-HSF1 is involved in G-CSF-induced cardiac protection after ischemia/reperfusion. Rational-Granulocyte colony-stimulating factor (G-CSF) has been reported to protect cardiomyocytes (CM) from ischemic injury through Jak2/STAT3 pathway. Heat shock transcription factor 1 (HSF1), a definite protective factor in the heart, may interact with STAT family under stress conditions.Objective-The present study was to investigate whether a cross talk between HSF1 and STAT3 is involved in G-CSF-induced cardiac protection after ischemia/reperfusion.Methods-(1) To examine the expression and activity of HSF1 after administration of G-CSF in Langendorff model and cultured cardiomyocytes. (2) To observe the phosphorylation of STAT3 in G-CSF treated cardiomyocytes. (3) To test whether states of HSF1 alter when STAT3 was inhibited. (4) To determine how STAT3 changed when HSF1 was downregulated. (5) To reveal the interaction between HSF1 and STAT3 with co-immunoprecipitation.Results-(1) Neither ischemia reperfusion injury nor G-CSF altered the HSF1 transcription level in Langendorff models. G-CSF upregulated the phosphorylation of HSF1 at Ser230 and the productions of heat shock proteins (HSP) without shifting in the level of HSF1 mRNA. (2) G-CSF could activate STAT3 in a time-dependent manner. (3) Activation of HSF1 was undermined after treated with S3I-201, a STAT3 inhibitor. (4) STAT3 was less phosphorylated when transfected with HSF1 siRNA or treated with KNK437, a HSF1 inhibitor. (5) HSF1 and STAT3 may interact with each other, which was enhanced by G-CSF and inhibited by S3I-201 or KNK437.Conclusions-G-CSF can induce an interaction between HSF1 and STAT3 to enhance the intrinsic protection, which increases the transcriptional activities of HSF1 and therefore protects the heart against ischemia/reperfusion injury.