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 ex-posed to hypoxia/reoxygenation injury (H/R) and explore the possible mechanism. Methods: The cultured neonatal rats' ventricular cardiomyocytes were divided randomly into 4 groups, con-trol 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- α (TNF- α ) gene in all the groups was detected by RT-PCR and Western blot. The nuclear factor- KB (NF- kB) activity was detected by electrophoretic mobility shift assay (EMSA) and the inhibitor-kBα (I- kBα)protein level was detected by Western blot. Results: The decrement of I- K B α protein and the in-creasing NF- kB activity were found in cardiomyocytes pre-treated with EPO before H/R compared to other groups (t=-3.321,4.183, P<0.01). However, after H/R, NF- kB activity and ex-pression of TNF- α gene were significantly reduced, I- k B α protein expression was increased in cardiomyocytes of E group compared to other groups (t=-3.425, 3.687, 3.454, P<0.01). All theses changes caused by EPO pretreatment were eliminated by the intervention of PDTC (an antagonist to NF- kB) dur-ing pretreatment. Conclusions: EPO pretreatment can inhibit the activa-tion of NF- kB and upregulation of TNF- α gene in cardiomyocytes exposed to H/R through a negative feed-back of NF- k B signaling pathway, and thus produces the anti-inflammatory effect. This might be one of the ways EPO produces the anti-inflammatory effect.