A combination of podophyllotoxin and rutin alleviates radiation-induced pneumonitis and fibrosis through modulation of lung inflammation in mice

Abstract

Pneumonitis and pulmonary fibrosis are predominant consequences of radiation exposure, whether planned or accidental. The present study, demonstrates radioprotective potential of a formulation, prepared by combining podophyllotoxin and rutin (G-003M), in mice exposed to 11 Gy thoracic gamma radiation (TGR). Treated mice were observed for survival and other symptomatic features. Formation of reactive oxygen species (ROS)/nitric oxide (NO) was measured in bronchoalveolar lavage cells. DNA damage and cell death were assessed in alveolar cells by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. Total protein (TP), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) were measured in bronchoalveolar lavage fluid (BALF)/serum of mice to assess lung vascular permeability. Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), cluster of differentiation 45, inducible nitric oxide synthase (iNOS), and nitrotyrosine were also estimated in lungs/BALF of differentially treated mice. Our observations revealed 100% survival in G-003M-pretreated mice against 66.50% in 11 Gy TGR exposed. Other symptoms like reduction in graying of hair, weight loss, and breathing rate were also observed in pretreated groups. Significant decline in ROS/NO and cell death in formulation pretreated mice were also observed. Decreased level of TP, LDH, and ALP in BALF/serum samples revealed G-003M-induced inhibition in lung permeability. Level of IL-6, TNF-α, and TGF-β1 in the lungs of these mice was found corresponding to control group at 8 weeks posttreatment. On the contrary, these cytokines raised significantly in 11 Gy TGR-exposed mice. Lung pneumonitis and fibrosis were found significantly countered in these mice. The observations revealed that G-003M could regulate immune system by curtailing radiation-induced oxidative and inflammatory stress, which has helped in minimizing radiation-inflicted pneumonitis and fibrosis.