Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma

Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation.

尽管辐射安全剂量已被明确界定，但公众对低剂量辐射有害效应的担忧仍持续存在。尤为值得关注的是，迄今为止鲜有研究探讨低剂量辐射与疾病发生发展之间的关联。哮喘作为一种常见的慢性气道炎症性疾病，已被认定为重大公共卫生问题。本研究以小鼠模型为载体，评估了低剂量率慢性辐照对变应性哮喘的影响：实验小鼠经卵清蛋白（ovalbumin, OVA）致敏并实施气道激发后，于初次致敏后接受为期24天的持续低剂量率辐照，辐照剂量率分别为0.554 mGy/h与1.818 mGy/h。本研究同时探讨了慢性辐照对促炎细胞因子及基质金属蛋白酶-9（matrix metalloproteinase-9, MMP-9）活性的影响。结果显示，低剂量率慢性辐照可显著降低气道炎症细胞数量、乙酰甲胆碱反应性（PenH值）以及OVA特异性免疫球蛋白E、白细胞介素（interleukin, IL)-4与IL-5的水平。此外，OVA激发诱导的气道炎症与肺组织黏液分泌均得到缓解，且OVA激发所上调的MMP-9表达与活性亦被显著抑制。上述结果表明，低剂量率慢性辐照可抑制OVA激发诱导的变应性哮喘，且不会对哮喘的发生发展产生任何不良影响。本研究结果可为辐射安全应用提供毒理学指导，并有助于缓解公众对低剂量辐射暴露的普遍焦虑。