The Role Of Epithelial To Mesenchymal Transition In The Remodeling Of Lung Injury Induced By Acute Graft-Versus-Host Disease

Abstract

BackgroundNoninfectious lung injury caused by graft-versus-graft disease (GVHD) is a life-threatening complication after allogeneic hematopoietic stem cell transplant (allo-HSCT). Epithelial injury is a central event in the pathogenesis of noninfectious lung injury. Recent studies have shown that alveolar epithelial cells are able to self-renew and reestablish a functional alveolar epithelium. In the inflammatory and fibrotic lung diseases, differentiated epithelia also can acquire a myofibroblast phenotype in the process termed epithelial to mesenchymal transition (EMT), which contributes to aberrant healing and fibrosis. Many factors such as inflammatory cytokine TGF-β have been suggested to induce EMT. However, the role of EMT in the remodeling of acute GVHD (aGVHD) induced lung injury is unclear. MethodsBALB/c mice were lethally irradiated and transplanted T cell-deleted (TCD) bone marrow plus whole spleen cells from C57BL/6 mice as aGVHD group, and only transplanted TCD bone marrow cells as control group. Alveolar epithelial cells were isolated from mice of two groups and Ep-CAM expression was measured by flow cytometry. The mRNA expression of cytokines including IFN-γ, TNF-α and TGF-β was detected by RT-PCR. The mRNA and protein expressions of specific markers, including E-cadherin, vimentin, Snail and surfactant proteins (SP)-C in lung tissue, were detected by RT-PCR and western blot. ResultsAll mice in the aGVHD group showed diffuse periluminal infiltrates and parenchymal pneumonitis by histopathology, while the mice in the control group did not show any lung injury evidence. IFN-γ, TNF-α, TGF-β mRNA expressions were markedly up-regulated in the lung injury group as compared to the control group (P=0.045, P=0.032, P=0.025). Alveolar epithelial cells of injured lung expressed higher Ep-CAM (P=0.017) and lower SP-C (P=0.023). RT-PCR and western blot analyses revealed a significant decrease in epithelial marker E-cadherin (P=0.029) and increase in mesenchymal marker vimentin (P=0.026) in the GVHD damaged lung. Snail, a key EMT related transcription factor, was significantly elevated at mRNA and protein level in comparison to control group (P=0.015). ConclusionEMT is involving in the remodeling of lung injury induced by aGVHD. TGF-β is demonstrated to induce EMT. Whether up-regulation of IFN-γ and TNF-α contributes to EMT is deserved to be further explored. Disclosures:Wu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Liu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Zhao:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Wu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Zhang:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Fan:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Fan:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Yin:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Zheng:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Yi:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Liu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding.