Abstract
Background: T helper 17 cells (Th17)/ regulatory T cells (Treg), as subtypes of CD4+T cells, played an important role in the inflammatory response of acute respiratory distress syndrome (ARDS). However, there is still a lack of effective methods to regulate the differentiation balance of Th17/Treg. It was proved that mesenchymal stem cells (MSCs) could regulate the differentiation of CD4+T cells, but the mechanism was still unclear. TGFβ1, as one of the paracrine cytokines of MSCs, could also regulate the differentiation of Th17/Treg but possess low expression in MSCs. Therefore, mouse MSCs (mMSCs)overexpressing TGFβ1 was constructed by lentivirus transfection and intratracheally transplanted into LPS-induced ARDS mice in our study. And the aim of which was to evaluate the therapeutic effects of mMSCs overexpressing TGFβ1 on inflammation and immunoregulationvia impacting Th17/Treg balance inLPS-induced ARDS mice. Methods: mMSCs with TGFβ1 overexpression were constructed using lentiviral vectors. Then mBM-MSCs and mBM-MSC-TGFβ1 (mMSCs overexpressing TGFβ1) were transplanted intratracheally into the ARDS mice induced by lipopolysaccharide. At 3d and 7d after transplantation, mice were sacrificed and the histopathology of lungs was assessed by hematoxylins and eosin staining and lung injury scoring. Homing of the mMSCs were assayed by ex vivooptical imaging. The relative number of Th17 and Treg in the lungs and spleens in mice were detected by FCM. IL-17A and IL-10 in the lungs of mice were analyzed by western blot. Permeability was evaluated by analysing the protein concentration of BALF using ELISA. Alveolar Lung fibrosis was assessed by Masson’s trichrome staining and Ashcroft scoring. The mortality of ARDS mice was followed until 7 days after transplantation. Results: The transduction efficiencies mediated by the lentiviral vectors were 82.3-88.6%. Overexpressing TGF-β1 inhibited the proliferation of mMSCs during day 5-7 (p<0.05), but made no effects on their differentiation or migration (p>0.05). Compared to the LPS+mBM-MSC-NC group, mMSCs overexpressing TGFβ1 engraftment led to improved histopathology of lung tissue in ARDS mice (p<0.05), much more differentiation of mMSCs into Th17 or Treg (p<0.05) and improved permeability of injured lungs (p<0.05). Moreover, IL-17A was also decreased while IL-10 increased in the LPS+mBM-MSC-TGFβ1 group than in the LPS+mBM-MSC-NC group respectively (p<0.05).Finally, mMSCs overexpressing TGFβ1 did not aggravate the fibrosis of lungs in ARDS mice (p>0.05). Conclusion: MSCs overexpressing TGFβ1 could regulate lung inflammation and attenuated lung injuries via modulating the imbalance of Th17/Treg in the lungs of ARDS mice.
Phagocytosis of Apoptotic Cells Modulates Mesenchymal Stem Cells Osteogenic Differentiation to Enhance IL-17 and RANKL Expression on CD4+ T cells
