The repair effect and mechanism of amphiregulin on injured lung tissue in mice / 中华急诊医学杂志

Objective:To investigate the repair effect of amphiregulin (Areg) on injured lung tissue in mice with acute respiratory distress syndrome (ARDS) and its underlying mechanism.Methods:The ARDS mouse model was made by tracheal infusion of lipopolysaccharide (LPS), and bronchoalveolar lavage fluid (BALF) was extracted for 7 consecutive days. Adult male C57BL/6 mice were randomly (random number) divided into 5 groups ( n=4 per group): (1) Control group; (2) Areg group: mice were treated intraperitoneally (i.p.) with recombinant Areg; (3) LPS+PBS group; (4) LPS+Areg group; and (5) LPS+Anti-Areg group; mice were instilled with LPS, then were injected i.p. with PBS, Areg or Areg neutralization antibody (Anti-Areg) 30 min later. Lung tissue and BALF were extracted at day 1, 3, 5 and 7 after ARDS. HE staining was used to evaluate the pathological changes of lung tissues. The total protein content in BALF was detected by BCA method, and the concentrations of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β and immunoglobulin M (IgM) were determined by ELISA method. The phosphorylated levels of epidermal growth factor receptor (EGFR) and expressions of proliferating cell nuclear antigen (PCNA) and surface proteins-C (SP-C) were tested by Western blot. The immunofluorescence was used to detect the co-expression of PCNA and SP-C in lung tissues. One-way analysis of variance was used to compare the mean values of normally distributed measurement data between groups. Comparisons between groups were performed using the least significant difference t-test. Results:Compared with that at before modeling [(51.05±2.47) pg/mL], Areg concentrations were increased significantly at day 1 [(71.97±6.51) pg/mL; P<0.01] and day 3 [(147.58±7.56) pg/mL, P<0.01] in the BALF after ARDS. At day 1 after ARDS, there were significant interstitial edema, neutrophil infiltration and alveolar collapse in the LPS+PBS group and LPS+Areg group. Compared with the LPS+PBS group at day 3, 5 and 7, the pathological changes of lung tissues were notably improved in the LPS+Areg group, while were more serious in the LPS+Anti-Areg group. Compared with the control group, the LPS+PBS group had higher levels of neutrophil number, total protein, IgM, TNF-α, IL-1β, and IL-6. However, Areg treatment significantly reduced the levels of these indicators. Moreover, the expressions of PCNA (1.34±0.10), SP-C (1.48±0.10) and p-EGFR (0.92±0.032) in the LPS+Areg group were significantly up-regulated compared with those in the LPS+PBS group (0.88±0.03, 1.06±0.15, and 0.68±0.03, all P<0.01). And compared with the LPS+PBS group, PCNA and SP-C double positive cells were significantly increased in the LPS+Areg group, but decreased in the LPS+Anti-Areg group. Conclusions:Areg enhances the proliferation of alveolar typeⅡ epithelial cells by activating EGFR pathway, therefore promotes the repair of lung tissues during ARDS development.

Stimulation of Yes-associated protein activity attenuates lung injury repair induced by LPS in mice / 中国临床药理学与治疗学

AIM: To observe the effect and possible mechanism of stimulation of Yes-associated protein (YAP) activity on acute lung injury and repair induced by LPS in mice. METHODS: Ninety adult male ICR mice were divided into two groups: acute lung injury model group induced by LPS (7.5 mg/kg, i.p.) and LPS+XMU treatment (1 mg•kg-1•d-1) group. At 0 h, 24 h, 48 h and 72 h after LPS injection, the contents of TNF-α and IL-6 in bronchoalveolar lavage fluid (BALF) were detected by ELISA method. The activity of myeloperoxidase (MPO) and the content of protein in BALF were evaluated by chemical technique. The protein level of nuclear YAP, cytosol phosphorylated YAP (P-YAP), connective tissue growth factor (CTGF) and proliferating cell nuclear antigen (PCNA) in lung were analyzed by Western blot. RESULTS:The protein level of nuclear YAP at 24 h, 48 h and 72 h in lung of LPS+XMU group were up-regulated than those of LPS group by 39.2%, 148.1% and 42.9%, and the protein level of CTGF in lung were up-regulated than those of LPS group by 186.6%, 10.1% and 146.1% (P<0.05), respectively, while the protein level of cytosol P-YAP was down-regulated. The content of IL-6 and TNF-α at 24 h in BALF of LPS+XMU group were lower than those of LPS group by 28.4% and 23.7%, and the activity of MPO and the content of TNF-α at 48 h in BALF were lower by 13.5% and 39.5%, and the content of IL-6 and TNF-α at 72 h in BALF were lower by 42.8% and 16.7% (P<0.05), respectively. The protein level of PCNA at 48 h and 72 h in lung of LPS+XMU group were up-regulated than those of LPS group by 44.2% and 14.9% (P<0.05), respectively, while there was no significant difference at 24 h. The content of protein at 24 h, 48 h and 72 h in BALF of LPS+XMU group were lower than those of LPS group by 32.4%, 46.0% and 26.3% (P<0.05), respectively. The pathological changes showed a significantly attenuated tissue injury and accelerated recovery from lung injury in LPS+XMU group compared with mice injected with LPS alone at each times point. CONCLUSION: Stimulation of YAP activity attenuates lung injury and promotes lung recovery by alleviating lung inflammation and injury at injury phase, but by promoting inflammation resolution and stimulating cell proliferation at repair phase.

Effects of Hippo signaling pathway on lung injury repair by mesenchymal stem cells in acute respiratory distress syndrome / 中华危重病急救医学

Objective To investigate the effects of Hippo signaling pathway on lung injury repair of mesenchymal stem cells (MSC) in acute respiratory distress syndrome (ARDS) and its mechanism. Methods Mouse bone marrow-derived MSC (mMSCs) cell lines with low expression of large tumor suppressor 2 (LATS2) were constructed by lentiviral vector transfection. Male C57BL/6 mice aging 6-8 weeks old were divided into four groups according to random number table (n = 36). The ARDS animal model (ARDS group) was reproduced by intratracheally injection of 2 g/L lipopolysaccharide (LPS) 50 μL, the normal saline (NS) control group was injected with an equal volume of NS. After 4 hours of model reproduction, 5×104 mMSCs transfected with blank lentivirus vector (MSC-shcontrol group) or shLATS2 lentivirus vector (MSC-shLATS2 group) were transplanted intratracheally, while NS control group and ARDS group were injected with equal volume of phosphate buffered saline (PBS). Mice were sacrificed at 3, 7, and 14 days after modeling, and lung tissue and bronchoalveolar lavage fluid (BALF) were harvested. Near-infrared fluorescence imaging, immunofluorescence staining and Western Blot were used to track mMSCs in lung tissue. Retension and proportion of mMSC differentiation into type Ⅱ alveolar epithelial cells (AECⅡ) were evaluated. 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 to reflect permeability of epithelium. The levels of interleukins (IL-1β, IL-6, IL-10) in BALF were assessed by enzyme-linked immunosorbent assay (ELISA) to reflect lung inflammation. Hematoxylin-eosin (HE) staining and modified Masson staining were carried out, and the scores were assessed to reflect lung injury and evaluate pulmonary fibrosis. Results The signal intensity of isolated lung fluorescence images at 3 days in the MSC-shLATS2 group was significantly higher than that in the MSC-shcontrol group (fluorescence intensity: 0.039±0.005 vs. 0.017±0.002, P < 0.05), the number of green fluorescent protein (GFP)-positive cells in lung tissue was also significantly higher than that in the MSC-shcontrol group (cells/HP:29.65±6.98 vs. 17.50±4.58, P < 0.05), but they all decreased with time; and the proportion of mMSCs differentiated into AECⅡ was significantly increased [(64.12±15.29)% vs. (19.64±3.71)%, P < 0.05]. Compared with the NS control group, the levels of surface active protein C (SPC) and Occludin protein in the ARDS group were significantly decreased, LWW/BW ratio and TP, ALB and inflammatory factors levels in BALF were significantly increased; extensive alveolar and interstitial edema, hemorrhage and diffuse inflammatory cell infiltration were found in lung tissue, and the lung injury score was significantly increased; collagen fibers were deposited in alveolar septum and alveolar cavity, and pulmonary fibrosis score was also increased significantly. Compared with the ARDS group, the expression levels of SPC and Occludin at 14 days in the MSC-shcontrol group and the MSC-shLATS2 group were significantly increased (SPC/β-actin: 0.51±0.12, 0.68±0.10 vs. 0.27±0.08, Occludin/β-actin: 0.49±0.19, 0.79±0.11 vs. 0.25±0.08, all P < 0.05), TP, ALB, IL-1β, IL-6 levels in BALF at 3 days were significantly decreased [TP (g/L): 8.08±1.72, 5.12±0.87 vs. 12.55±2.09; ALB (g/L): 0.71±0.21, 0.44±0.18 vs. 1.18±0.29, IL-1β(ng/L): 99.26±14.32, 60.11±8.58 vs. 161.86±25.17, IL-6 (ng/L): 145.54±13.29, 101.74±11.55 vs. 258.79±27.88, all P < 0.05], and IL-10 was significantly increased (ng/L: 190.83±22.61, 316.65±37.88, both P < 0.05). Furthermore, all the above parameters in the MSC-shLATS2 group were significantly improved as compared with those in the MSC-shcontrol group (all P < 0.05). LWW/BW ratio in the MSC-shLATS2 group was significantly lower than that in the ARDS group and the MSC-shcontrol group (mg/g: 9.85±1.51 vs. 16.78±1.92, 14.88±1.74, both P < 0.05). Conclusion Inhibiting Hippo signaling pathway by low expression of LATS2 could promote the retention of mMSCs in lung tissue and differentiation into AECⅡcells of ARDS mice, improve pulmonary edema and alveolar epithelial permeability, regulate pulmonary inflammatory response, and alleviate pathological damage and fibrosis of lung tissue.

Modulation of Hippo signaling pathway facilitates mesenchymal stem cells to repair lung injury in murine lipopolysaccharide induced acute respiratory distress syndrome / 中华急诊医学杂志

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 (LATS 1) 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-LATS 1 lentivirus vector (MSC-shLATS 1 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 ofmMSCs 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 type Ⅱ 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±l.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-shLATS 1 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.