Protective effect of vitamin D on radiation-induced lung injury: experimental evidence

ABSTRACT

Vitamin D, especially its most active metabolite 1, 25-dihydroxyvitamin D3[Vit D] is essential in regulating a wide variety of biologic processes, such as regulating mesangial cell activation. The objective of this study was to assess the histopathological changes of effectiveness of Vit D as a protective agent against radiation induced lung injury. Eighteen Wistar rats were divided into three groups control group [group 14 rats], irradiation alone group [group 27 rats] and irradiation+vit D [group 37 rats]. Rats in group 2 and 3 were exposed to 20 Gy radiations to the right lung in a Co[60] radiotherapy machine under general anesthesia. Additionally, rats in group 3 received Vit D at a single dose of 0.2 mcg injected IM 2 hours before exposure to irradiation. Rats were sacrificed and lungs were dissected fifty days after post-irradiation. Myofibroblasts and vitamin D3 receptors [VDR] in extracted lungs were stained by immunohistochemistry using alpha-smooth muscle actin [SMA] and VDR antibodies. Blinded histological evaluation was performed to assess lung injury. Lung injury was assessed by the acute lung injury score and myofibroblastic differentiation score. Acute lung injury scores and myofibroblastic differentiation scores were significantly lower in the radiation+vit D group compared to irradiation alone group [p=0.001 and p=0.001, respectively]. This study indicates that administration of vit D plays a protective role against acute lung injury through blocking myofibroblastic differentiation