ABSTRACT
To investigate the effect of overexpression of microRNA-21-5p (miR-21-5p) on early apoptosis of type Ⅱalveolar epithelial cells (AECⅡ) in rats with hyperoxic acute lung injury (HALI). Methods The Sprague-Dawley (SD) rats were randomly divided into four groups: control group (CON group), hyperoxia group (H group), overexpression group (OE group) and empty vector group (EV group), with 20 rats in each group. HALI animal model was made by inhaling high concentration oxygen (oxygen concentration ≥90%); CON group was arranged to inhale room air. The miR-21-5p adeno-associated virus-6 (AAV-6) overexpression vectors or empty vectors were dripped into the lungs of OE group and EV group through tracheal tube, respectively. The hyperoxia model was prepared after 3 weeks of feeding. At 0, 24, 48 and 60 hours after making model, 5 rats were selected to detect lung injury parameters:oxygenation index (OI), respiratory index (RI), wet/dry ratio (W/D), pathological injury score of lung tissue; real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of miR-21-5p in AECⅡ, and flow cytometry was used to detect the early apoptotic rate of AECⅡ. Results ① The lung injury parameters: in H group, the OI gradually decreased with time, but the RI, lung W/D ratio and pathological score increased gradually with time, the difference between CON group was statistically significant at 24 hours [OI (mmHg, 1 mmHg = 0.133 kPa):336.04±5.79 vs. 400.22±19.70, RI: 0.20±0.02 vs. 0.10±0.06, lung W/D ratio: 5.04±0.09 vs. 4.85±0.09, lung tissue pathological score: 0.13±0.01 vs. 0.07±0.01, all P < 0.05]. It indicated that HALI model could be successfully established by inhaling high concentration oxygen continuously. ② The expression of miR-21-5p: the miR-21-5p was gradually increased in H, OE and EV groups, and the expression of miR-21-5p was significantly higher than that in CON group at 24, 48 and 60 hours. Compared with H group, the expression of miR-21-5p was significantly increased further in OE group at 0, 24, 48 and 60 hours (2-ΔΔCt: 3.75±0.11 vs. 0.98±0.14, 3.98±0.12 vs. 1.18±0.13, 4.28±0.18 vs. 1.49±0.06, 4.66±0.12 vs. 1.80±0.12, all P < 0.05). ③ The early apoptosis of AECⅡ: the early apoptosis rate gradually increased with time in H, OE and EV groups, and the early apoptosis of AECⅡ was significantly higher than that in CON group at 24, 48 and 60 hours. Compared with H group, the early apoptosis rate was significantly decreased in OE group at 24, 48 and 60 hours [(1.22±0.63)% vs. (2.84±0.59)%, (5.76±0.18)% vs. (13.10±2.01)%, (29.48±0.48)% vs. (49.04±1.36)%, all P < 0.05]. ④ There was no significant difference in the expression of miR-21-5p and the early apoptosis of AECⅡ cells between EV group and H group at each time point. Conclusion Overexpression of miR-21-5p could inhibit the early apoptosis of AECⅡ in rats with HALI.
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Objective To explore the effects of Hippo pathway on differentiation, proliferation, and migration of bone marrow mesenchymal stem cells (BMSCs) in vitro. Methods BMSCs of C57BL/6 mice were identified using fluorescence-activated cellsorting analysis and the capabilities of osteogenic, chondrogenic and adipogenic differentiation were evaluated. The differentiation of BMSCs to typeⅡalveolar epithelial cells (AECⅡ) was induced by indirect co-culture with mouse lung epithelial cells (MLE-12) and small airway epithelial cell growth medium (SAGM). The Hippo pathway was regulated by 2-deoxy-D-glucose (2-DG) and 9E1, the effects of 2-DG and 9E1 on the expression of BMSCs surface proteins (SPB, SPC and SPD) mRNA and pro-SPC protein were detected by real time quantitative polymerase chain reaction (qRT-PCR) and Western Blot. The effect of Hippo pathway on differentiation of BMSCs to AECⅡ cells was evaluated. The effect of Hippo pathway on the proliferation of BMSCs was evaluated by methyl thiazolyl tetrazolium (MTT) assay (intervention of 0.1, 0.5, 1.0, 5.0 mmol/L 2-DG). The scratch test and Transwell chamber test were used to analyze the effect of Hippo pathway on migration ability of BMSCs to conditioned medium of acute respiratory distress syndrome (ARDS) lung tissue. Results 2-DG could activate Hippo pathway in a dose-dependent manner and promote the differentiation to AECⅡ and proliferation of BMSCs, the maximum effects were observed after 5 mmol/L of 2-DG treatment [SPB mRNA (2-ΔΔCT): 2.42±0.28 vs. 1.89±0.11, SPC mRNA (2-ΔΔCT): 8.06±0.68 vs. 6.59±0.79, SPD mRNA (2-ΔΔCT): 6.45±0.37 vs. 5.27±0.28, pro-SPC/β-actin: 5.80±1.86 vs. 4.93±1.18, proliferation rate:(145.46±18.18)% vs. (98.91±4.36)%, all P < 0.05], but 9E1 could reverse those effects through inhibition of Hippo pathway [SPB mRNA (2-ΔΔCT): 1.32±0.17 vs. 1.89±0.11, SPC mRNA (2-ΔΔCT): 3.91±0.34 vs. 6.59±0.79, SPD mRNA (2-ΔΔCT): 3.38±0.25 vs. 5.27±0.28, pro-SPC/β-actin: 2.48±0.17 vs. 4.93±1.18, proliferation rate: (80.00±7.27)% vs. (98.91±4.36)%, all P < 0.05]. The ability of horizontal migration [wound healing: (27.17±3.53)% vs. (52.45±6.52)%, P < 0.05] and homing BMSCs to conditioned medium of ARDS lung tissue [cell count (fold, relative to control): 2.77±0.21 vs. 1.90±0.19, P < 0.05] were increased after activation of Hippo pathway by 2-DG treatment, but those effects were reversed after inhibition of Hippo pathway by 9E1 treatment [wound healing: (79.89±8.42)% vs. (52.45±6.52)%, cell count (fold, relative to control): 1.69±0.13 vs. 1.90±0.19, both P < 0.05]. Conclusion Activation of Hippo pathway could enhance differentiation of BMSCs to AECⅡ, promote proliferation and ability of horizontal migration and homing BMSCs to conditioned medium of ARDS lung tissue in vitro.
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Objective To investigate the effect of heme oxygenase-1 (HO-1) on the apoptosis of type Ⅱalveolar epithelial cells (AEC-Ⅱ) in rats with hyperoxia-induced acute lung injury (HALI). Methods Twenty-four healthy male Sprague-Dawley (SD) rats were randomly divided into 4 groups (n = 6): control group, HALI group, HO-1 group, and HO-1 inhibition group. The control group was fed in the room air; the HALI group was fed in the hyperoxia box (the oxygen concentration was more than 90%, the temperature was kept at 25-27 ℃, the humidity was maintained at 50%-70%, and the CO2concentration was less than 0.5%); the HO-1 group was fed in the hyperoxia box after HO-1 (0.2 μmol/L) treatment; and the HO-1 inhibition group was fed in the hyperoxia box after treatment with zinc protoporphyrin Ⅸ (20 μmol/L). After 48 hours of hyperoxia treatment, rats were sacrificed, left upper lung tissue was stained with hematoxylin-eosin (HE) and the pathological changes of lung tissue were observed under light microscope. The ratio of wet/dry weight (W/D) was measured in the lower left lung. AECⅡ was extracted from the right lung tissue, the apoptosis rate was detected by flow cytometry, and the expressions of apoptosis-related proteins Bcl-2 and caspase-3 were detected by Western Blot. Results ①It was shown by light microscopy that the lung tissue structure of the control group was clear. In HALI group and HO-1 inhibitor group, the lung tissue structure was disordered, alveolar wall was broken and fused into pulmonary alveoli, alveolar septum was obviously swollen and widened, a large number of inflammatory cells infiltrated, and edema fluid and inflammatory cells appeared in alveolar cavity. The pathological changes of lung tissue in HO-1 group were significantly less than those in HALI group. ② Compared with the control group, the lung W/D ratio, the apoptosis rate of AECⅡand the expression of Bcl-2 protein in the HALI group and the HO-1 inhibitor group were significantly increased, and the expression of caspase-3 was significantly decreased [lung W/D ratio: 4.61±0.41 vs. 3.68±0.45, apoptosis rate of AECⅡ: (42.44±0.93) % vs. (24.74±0.64) %, Bcl-2 (integral absorbance): 0.72±0.18 vs. 0.41±0.12, caspase-3 (integral absorbance): 1.32±0.32 vs. 1.81±0.69, all P < 0.05]. Compared with the HALI group, the lung W/D ratio, the apoptosis rate of AECⅡ, the expression of Bcl-2 protein in HO-1 group were significantly decreased, and the expression of caspase-3 was significantly increased [lung W/D ratio: 3.82±0.28 vs. 4.61±0.41, apoptosis rate of AECⅡ: (26.67±1.58) % vs. (42.44±0.93) %, Bcl-2 (integral absorbance): 0.39±0.08 vs. 0.72±0.18, caspase-3 (integral absorbance): 1.78±0.46 vs. 1.32±0.32, all P < 0.05]. There was no significant difference between HO-1 inhibitor group and HALI group. Conclusions HO-1 can reduce the apoptosis rate of AECⅡin rats with HALI, which may be related to the expressions of apoptosis related proteins Bcl-2 and caspase-3.
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Objective:Todevelop the isolation and purification technology for typeⅡalveolar epithelial cells(AECⅡ)of fetal rat,in order to provide experimental means for the study of lung development or neonatal lung disease.Methods:Lung tissues of 19-day fetal rats were digested with trypsin and collagenase,then purified for AECⅡwith different centrifugal force and repeated attachment.Cell viability was evaluated by typran inclusion dying before plated into six-well flask.Growth status and shape of attached cells were observed with inverted phase contrast microscope.AECⅡwere identified by electron microscopy and its percentage was assessed by modified Papanicolaou dying and immunofluorescence,the latter aiming to detect expression of surfactant protein C(SPC)in AECⅡ.Results:The total amount of cells we harvested from 3 to5 fetal rat was(36?5)?106 with a viability of 98%?2%.Cells were like polygonal and connected like island under microscope.AECⅡwas ascertained by lamellar bodies found in cytoplasma under electron microscope and its percentage was 96%?3%identified by modified Papanicolaou dying,the same as the result by immunofluorescence for SPC.Conclusion:Highly Purified and viable AECⅡcould be achieved by our methods and the cell model could be used in further study.