title: Protective Effects of Myrtol Standardized Against Radiation-Induced Lung Injury.
abstract: OBJECTIVE
  As a major complication after thoracic radiotherapy, radiation-induced lung injury (RILI) has great impact on long term quality of life and could result in fatal respiratory insufficiency The present study was aimed to evaluate the effects of Myrtol standardized on RILI, and to investigate the underlying mechanism.
  
  
  METHODS
  A mouse model of radiation-induced lung injury was generated by using thoracic irradiation with a single dose of 16Gy. Mice were orally administrated with Myrtol (25 mg/kg/day) for 4 weeks after irradiation, while prednisone (5 mg/kg/day) was used as a positive control. After then, the body weight and lung coefficient were calculated. The severity of fibrosis was evaluated by observing pulmonary sections after radiation and collagen content in lung tissues was calculated following the hydroxyproline (HYP) assay. Pathological changes were observed in all the groups by using HE staining and Masson staining. The serum levels of TGF-β1, TNF-α, IL-1β, IL-6, and PGE2 were also measured with an ELISA assay. Western blot assay was used to measure the impact of Myrtol on AKT and its downstream signaling pathway, including MMP-2 and MMP-9. The levels of Vimentin and α-SMA were evaluated with an immunofluorescence assay.
  
  
  RESULTS
  Treatment with Myrtol standardized, but not prednisone, reduced lung coefficient and collagen deposition in lung tissues, while attenuated histological damages induced by irradiation. Myrtol standardized also reduced the production of MDA, while increased the level of SOD. It was also observed that Myrtol standardized inhibited TGF-β1 and a series of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, PGE2. While in prednisone group, even though the early pneumonitis was ameliorated, the collagen disposition remained unchanged in latter times. Immunofluorescence analysis also revealed elevation of vimentin and α-SMA in the alveoli after a single dose of 16Gy.
  
  
  CONCLUSIONS
  The present results suggest Myrtol standardized as an effective agent for attenuating the lung injury induced by irradiation.
authors: Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai, China.
authors: De-yun
authors: DY
authors: Zhao
authors: Hong-jin
authors: HJ
authors: Qu
authors: Jia-ming
authors: JM
authors: Guo
authors: Hai-nan
authors: HN
authors: Zhao
authors: Yan-yong
authors: YY
authors: Yang
authors: Pei
authors: P
authors: Zhang
authors: Kun
authors: K
authors: Cao
authors: Xiao
authors: X
authors: Lei
authors: Jian-guo
authors: JG
authors: Cui
authors: Cong
authors: C
authors: Liu
authors: Jian-ming
authors: JM
authors: Cai
authors: Fu
authors: F
authors: Gao
authors: Bai-long
authors: BL
authors: Li
mesh_terms: D000818:Animals; D003094:Collagen / Q000032:analysis; D016207:Cytokines / Q000032:analysis; D004338:Drug Combinations; D005260:Female; D008168:Lung / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects*; D055370:Lung Injury / Q000188:drug therapy* / Q000473:pathology; D008810:Mice, Inbred C57BL; D039821:Monoterpenes / Q000008:administration & dosage / Q000627:therapeutic use*; D011658:Pulmonary Fibrosis / Q000188:drug therapy* / Q000473:pathology; D011833:Radiation Injuries, Experimental / Q000188:drug therapy* / Q000473:pathology; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D013482:Superoxide Dismutase / Q000032:analysis
chemical_list: D016207:Cytokines; D004338:Drug Combinations; D039821:Monoterpenes; D011837:Radiation-Protective Agents; C055632:myrtol; D003094:Collagen; D013482:Superoxide Dismutase