Modulation of Hippo signaling pathway facilitates mesenchymal stem cells to repair lung injury in murine lipopolysaccharide induced acute respiratory distress syndrome

Abstract

Objectives To determine the effect of Hippo signaling pathway on lung injury repair of bone-marrow derived mesenchymal stem cells (mMSCs) in murine lipopolysaccharide (LPS) induced acute respiratory distress syndrome (ARDS). Methods C57BL/6 mouse bone marrow-derived MSC (mMSCs) cell lines with low expression of large tumor suppressor 1 (LATS1) were constructed by lentiviral vector transfection. ARDS was modeled by intratracheally injection of 2 mg/mL lipopolysaccharide (LPS) 50 μL. C57BL/6 mice were randomly(random number) divided into four groups (n=36): normal control group, ARDS group, ARDS mice transplanted with mMSCs transfected with blank lentivirus vector (MSC-shcontrol group) or sh-LATS1 lentivirus vector (MSC-shLATS1 group). Mice were sacrificed at 3, 7, and 14 d after modeling, and lung tissue and bronchoalveolar lavage fluid (BALF) were collected. Near-infrared fluorescence imaging, immunofluorescence staining and Western blot were used to evaluate retention and differentiation of mMSCs in lung tissue. Lung tissue wet weight/body weight ratio (LWW/BW) and total protein (TP) and albumin (ALB) in BALF were determined to reflect pulmonary edema. The expression of Occludin protein in lung epithelium was tested by Western blot. The levels of interleukins (IL-1β, IL-6, and IL-10) in BALF were assessed by enzyme-linked immunosorbent assay (ELISA). Lung injury score and pulmonary fibrosis score in lung tissue were assessed. Results The retention of mMSCs at 3, 7 and 14 d in the MSC-shLATS1 group were significantly higher than those in the MSC-shcontrol group [(26.25±4.58) vs (12.13±3.75) cells/HP, (20.49±3.86) vs (9.97±2.76) cells/HP, and (13.77±3.55) vs (6.89±2.10) cells/HP, all P<0.05], so was the differentiation of mMSCs into typeⅡ alveolar epithelial cells at 14 d [(64.12±15.29)% vs (19.64±3.71)%, P<0.05]. LWW/BW and TP and ALB in BALF at 3 and 14 d in the MSC-shLATS1 group [(9.85±1.51), (6.11±0.83) (mg/g) and (5.12±0.87), (3.05±0.87) (mg/mL) and (0.44±0.18), (0.33±0.04) (mg/mL)] were higher than those in the MSC-shcontrol group [(14.88±1.74), (8.04±1.70)(mg/g) and (8.08±1.72), (5.94±1.20) (mg/mL) and (0.71±0.21), (1.07±0.29) (mg/mL)] (all P<0.05), so was the relative expression of Occludin protein[(0.79±0.11) vs (0.49±0.19), (P<0.05)]. The levels of IL-1β and IL-6(pg/mL) in BALF in the MSC-shLATS1 group [(60.11±8.58), (101.74±11.55)] was lower than those in the MSC-shcontrol group [(99.26±14.32), (145.54±13.29) ] (all P<0.05), but the levels of IL-10 in BALF in the MSC-shLATS1 group (316.65±37.88)pg/mL was higher than those in the MSC-shcontrol group (190.83±22.61)pg/mL (P<0.05). Lung injury scores at 3 and 14 d in the MSC-shLATS1 group [(7.18±1.12), (3.33±0.49)] was lower than those in the MSC-shcontrol group [(9.72±1.45), (5.11±0.86)] (all P<0.05), so was pulmonary fibrosis score at 14 d [(0.68±0.12) vs (1.47±0.18), P<0.05]. Conclusion Inhibition of Hippo signaling pathway through underexpression of LATS1 could improve the therapeutic effects of mMSCs in murine LPS-induced ARDS. Key words: Hippo signaling; Mesenchymal stem cells; Alveolar type Ⅱ epithelial cells; Acute respiratory distress syndrome; Lung injury repair