[Kiwi fruit essence reduces radiation-induced lung injury by down-regulating TNF-α and PDGF-B in rats]

Objective To observe the role of tumor necrosis factor-α (TNF-α) and platelet-derived growth factor-B (PDGF-B) in kiwi fruit essence-mediated protection of radiation-induced lung injury (RILI) in rats. Methods 96 male healthy Sprague-Dawley rats were divided into normal control group, model group, and kiwi fruit essence treatment group(60 and 240 mg/kg) by the random number table method, with 24 animals in each group. The whole lungs underwent 6 MV X-ray irradiation (18 Gy) to induce RILI animal models in rats of the latter three groups. On the next day after irradiation, rats in the latter two groups were intragastrically administrated with 60 or 240 mg/kg kiwi fruit essence, once a day. The rats in the normal control and model groups were treated with 9 g/L sodium chloride solution. Eight rats in the latter three groups were randomly sacrificed on days 14, 28, and 56, while normal control rats were sacrificed on day 56 as the overall control. Blood samples were collected and separated. Serum concentrations of TNF-α and PDGF-B were detected using ELISA. The lung tissues were isolated for HE and Masson staining to evaluate alveolitis and pulmonary fibrosis (PF). The hydroxyproline (HYP) content in lung tissues was detected. The mRNA and protein expression of pulmonary TNF-α and PDGF-B were determined by quantitative real-time PCR and immunohistochemistry. Results Compared with the model group, treatment with 60 and 240 mg/kg kiwi fruit essence group significantly reduced alveolitis on days 14 and 28 as well as PF lesions on days 28 and 56. Compared with the normal control group, HYP content in the lung tissue of the model group increased on day 28 and day 56, while TNF-α and PDGF-B levels in the serum and lung tissues increased at each time point. Compared with the model group during the same period, 60 and 240 mg/kg kiwi fruit essence element treatment group reported the diminished levels of serum and pulmonary TNF-α on day 14 and day 28. Consistently, the lung tissue HYP content and serum and pulmonary PDGF-B levels on day 28 and day 56 were reduced. In addition, the above indicators in the 240 mg/kg kiwi fruit essence treatment group were lower than those for the 60 mg/kg kiwi fruit essence treatment group. Conclusion Kiwi fruit essence can alleviate RILI in rats, which is related to the down-regulation of TNF-α expression at the early stage and decreased PDGF-B level at the middle and late stages.