TGF-beta1 transgenic mouse model of thoracic irradiation: Modulation of MMP-2 and MMP-9 in the lung tissue

Abstract

To investigate the effects of TGF-β1 on the gelatinases (MMP-2 and MMP-9), and their roles in lung remodeling after irradiation-induced lung injury. Expressions of TGF-β1 were measured with western blot, and expressions of MMP-2 and MMP-9 were analyzed with zymography in a TGF-β1 transgenic mouse model after thoracic irradiation with 12 Gy. We found expressions of TGF-β1 in the lung from the transgenic mice were three folds as compared to those from control mice. With densitometrical analysis, we found a significant decrease in MMP-9 activity in lung homogenates from the transgenic mice as compared with those from non-transgenic control mice 8 weeks after sham-irradiation (relative MMP-9 activity: C: 1.000±0.1091; TG: 0.4772±0.470 (n=8,P<0.05). But MMP-2 was constitutively expressed in the lung homogenates from the transgenic mice as compared to those from control mice 8 weeks after sham-irradiation (relative MMP-2 activity 8 weeks after sham-irradiation: C: 1.000±0.1556, TG: 1.0075±0.1472). Eight weeks after thoracic irradiation with 12 Gy, we observed a significant increase of MMP-2 and MMP-9 activity in lung homogenates from both transgenic and normal mice. In TGF-β1 transgenic mice relative MMP-9 activity was increased to 1.5321±0.2217 folds 8 weeks after thoracic irradiation with 12 Gy as compared to those after sham-irradiation (1.000±0.2153), and relative MMP-2 activity was increased to 1.7142±0.4231 folds. Our results show that TGF-β1 itself down-regulates activity of MMP-9, thereby decreases ECM degradation in lungs of TGF-β1 transgenic mice. Also we find that ionizing irradiation upregulates both MMP-2 and MMP-9 activity. Over-expressions of MMP-9 and MMP-2 after lung irradiation are involved in the inflammatory response associated with radiation-induced lung injury, and maybe further in radiation-induced lung fibrosis.

Keywords

TGF-β1 transgenic mouse / metalloproteinases (MMPs) / tissue inhibitors of metalloproteinase (TIMPs)

References

[1] RuebeC E, UtheD, SchmidK W, et al.. Dose-dependent induction of transforming growth factorβin the lung tissue of fibrosis-prone mice after thoracic irradiation. Int J Radiation Oncology Biol Phys, 2000, 47: 1033-1042

[2] SandersonN, FactorV, NagyP, et al.. Hepatic expression of mature transforming growth factor beta 1 in transgenic mice results in multiple tissue lesions. Proc Natl Acad Sci USA, 1995, 92: 572-576

[3] SmithP K, KrohnR I, HermansonG T, et al.. Measurement of protein using bicinchoninic acid. Anal Biochem, 1985, 150: 76-85

[4] SeelandU, HaeuselerC, HinrichsR, et al.. Myocardial fibrosis in transforming growth factor β1 (TGF-β1) transgenic mice is associated with inhibition of interstitial collagenase. European J of Clinical Investigation, 2002, 32: 295-303

[5] FaehligM, PerlewitzA, DollerA, et al.. Regulation of collagen prolyl 4-hydroxylase and matrix metalloproteinases in fibrosarcoma cells by hypoxia. Comp Biochem Physiol C: Toxicol Pharmacol, 2004, 139: 119-126

[6] TanakaH, HojoK, YoshidaH, et al.. Molecular cloning and expression of the mouse 105-kDa gelatinase cDNA. Biochem Biophys Res Commun, 1993, 190: 732-740

[7] VadayG G, SchorH, RahatM A, et al.. Transforming growth factor-beta suppress tumor necrosis factor alpha-induced matrix metalloproteinase-9 expression in monocytes. J Leukoc Biol, 2001, 69: 613-621

[8] ZechelJ, GohilH, LustW D, et al.. Alterations in matrix metalloproteinase-9 levels and tissue inhibitor of matrix metalloproteinases-1 expression in a transforming growth factor-β transgenic model of hydrocephalus. J Neurosci Res, 2002, 69: 662-668

[9] CorbelM, LanchouJ, GermainN, et al.. Modulation of airway remodeling-associated mediators by antifibrotic compound, pirfenidone, and the matrix metalloproteinase inhibitor, batimastat, during acute lung injury in mice. Eur J Pharmacol, 2001, 426: 113-121

[10] HayashiT, Stetler-StevensonW G, FlemingM V, et al.. WD Immunoshistochemical study of metalloproteinases and their tissue inhibitors in the lungs of patients with diffuse alveolar damage and idiopathic pulmonary fibrosis. Am J Pathol, 1996, 149: 1241-1256

[11] DelclauxC, d’OrthoM P, DelacourtC, et al.. Gelatinases in epithelial lining fluid of patients with adult respiratory distress syndr ome. Am J Physiol Lung Cell Mol Physiol, 1997, 272: L442-L451