Anti-inflammatory effect of erythropoietin pretreatment on cardiomyocytes with hypoxia/reoxygenation injury and the possible mechanism

OBJECTIVE: To investigate the anti-inflammatory effect of erythropoietin (EPO) pretreatment on cardiomyocytes exposed to hypoxia/reoxygenation injury (H/R) and explore the possible mechanism. METHODS: The cultured neonatal rats?ventricular cardiomyocytes were divided randomly into 4 groups, control group (C group), EPO pretreatment group (E group), EPO and pyrrolidine dithiocarbamate (PDTC) pretreatment group (EP group) and PDTC pretreatment group (P group). After 24 hours?pretreatment, the cardiomyocytes were exposed to H/R. After pretreatment and H/R, the expression of tumor necrosis factor-alpha(TNF-alpha) gene in all the groups was detected by RT-PCR and Western blot. The nuclear factor-kappa B (NF-kappa B) activity was detected by electrophoretic mobility shift assay (EMSA) and the inhibitor-kappa B alpha (I-kappa B alpha) protein level was detected by Western blot. RESULTS: The decrement of I-kappa B alpha protein and the increasing NF-kappa B activity were found in cardiomyocytes pretreated with EPO before H/R compared to other groups (t equal to 3.321, 4.183, P less than 0.01). However, after H/R, NF-kappa B activity and expression of TNF-alphagene were significantly reduced, I-kappa B alpha protein expression was increased in cardiomyocytes of E group compared to other groups (t=3.425, 3.687, 3.454, P less than 0.01). All theses changes caused by EPO pretreatment were eliminated by the intervention of PDTC (an antagonist to NF-kappa B) during pretreatment. CONCLUSIONS: EPO pretreatment can inhibit the activation of NF-kappa B and upregulation of TNF-alpha gene in cardiomyocytes exposed to H/R through a negative feedback of NF-kappa B signaling pathway, and thus produces the anti-inflammatory effect. This might be one of the ways EPO produces the anti-inflammatory effect.