22-oxacalcitriol protects myocardial ischemia-reperfusion injury by suppressing NF-κB/TNF-α pathway

The aim of this study was to explore whether 22-oxacalcitriol could protect inflammatory response induced by ischemia-reperfusion injury (IRI) in rats, and to investigate its underlying mechanism.

24 male Sprague Dawley rats were randomly assigned into the sham group, the IRI group and the 22-oxacalcitriol group, with 8 rats in each group. Serum and heart samples of each rat were collected 10 days after the animal procedure. The serum levels of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in each rat were detected by relative commercial kits. Pathological lesions in rat myocardium were observed by hematoxylin and eosin (HE) staining. Cardiomyocyte apoptosis in rat heart was accessed by TUNEL staining. Meanwhile, the serum levels of tumor necrosis factor-α (TNF-α), interleukin 1 beta (IL-1β), interleukin-6 (IL-6), and KC-GRO were detected by Real Time-quantitative Polymerase Chain Reaction (RT-qPCR). Also, the protein expression levels of NF-κB, TNF-α, VCAM-1, ICAM-1, and MCP-1 in rat myocardium were detected by Western blot and immunohistochemistry.

The serum levels of CK-MB and LDH in rats of the IRI group were significantly higher than those of the sham group. 22-oxacalcitriol treatment remarkably decreased the serum levels of CK-MB and LDH when compared with the IRI group. However, cardiomyocyte apoptosis of the 22-oxacalcitriol group was markedly less than the IRI group. The activities of SOD, GSH, CAT and T-AOC in the cardiac homogenate of the 22-oxacalcitriol group were significantly elevated than those of the IRI group. Meanwhile, malondialdehyde (MDA) and reactive oxygen species (ROS) levels were remarkably decreased by 22-oxacalcitriol treatment. Furthermore, the serum levels of TNF-α, IL-1β, IL-6 and KC-GRO were significantly downregulated in the 22-oxacalcitriol group. Western blot results showed that the protein expression levels of NF-κB, TNF-α, VCAM-1, ICAM-1 and MCP-1 in the 22-oxacalcitriol group were significantly lower than those of the IRI group.

22-oxacalcitriol inhibits the inflammatory response in the myocardium by suppressing NF-kB/TNF-α pathway, thereby protecting myocardial ischemia-reperfusion injury in rats.