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

Abstract

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.

Cytokines and radiation-induced pulmonary injuries

“… Wang et al [ 134 ] IL-4, IL-5 C57Bl/6 TBI 137 Cs/0.3 and 1 Gy continuously for 24 d 26 d ELISA BALF Continuous exposure to low-dose-rate radiation significantly reduced these cytokines. Kim et al [ 135 ] IL-1β, TNF-α, TGF-β1 C57Bl/6 TBI 137 Cs/6 × 0.25 Gy per 2 w 2 w ELISA, RT-PCR BAFL Significant induction of mRNA TGF-ß1 in mice exposed to hypoxia and/or radiation. Levels of active TGF-ß1 were significantly elevated in all cohorts in the BALF of mice.…”

Organ-Specific Effects of Low Dose Radiation Exposure: A Comprehensive Review

“…Although many studies opposed it through showing LDR (0.1 and 0.2 Gy) reportedly promoted cell death, inflammation, ROS generation (lipid oxidation), and DNA damage (5-hydroxymethylcytosine); and activated damage responses (p53, p38, p21, ERK1/2, NF-κB, TGF-β, etc.) in the lung, these studies unanimously agreed that certain irradiation conditions resulted in less severe changes in lung than that in the liver and the spleen ( Sypin et al, 2003 ; Avti et al, 2005 ; Lee et al, 2006 ; Kim et al, 2007 , 2015 ; Hong et al, 2014 ; Jangiam et al, 2018 ). Moreover, the protective roles of LDR in the lung have been demonstrated in various stress models.…”

“…Moreover, the protective roles of LDR in the lung have been demonstrated in various stress models. In these studies, LDR up to 0.5 Gy suppressed ROS generation, attenuated inflammatory responses (IL-1β, IL-5, IL-6, and TNF-α), delayed senescence, and reduced adverse effects induced by HDR ( Kim et al, 2007 , 2015 ; Hong et al, 2014 ; Liang et al, 2016 ; Velegzhaninov et al, 2018 ; Park et al, 2019 ; Son et al, 2019 ). Given these results, the lung may be more resistant to LDR exposure than other organs and seems to have a high threshold for LDR-induced lung specific biological marker alteration.…”

Hormetic Response to Low-Dose Radiation: Focus on the Immune System and Its Clinical Implications

“…For instance, it has been observed that repeated LDR significantly inhibited osteoclastic activity and subsequent bone resorption in patients with rheumatoid arthritis [ 66 , 67 , 68 ]. In mice with autoimmune encephalomyelitis or asthma, LDR treatment improved symptoms and suppressed disease development [ 13 , 69 ]. While the cancer risk posed by LDR remains controversial, progress in understanding LDR benefits to immune regulation may help establish it as an alternative treatment for autoimmune diseases.…”