Effect and mechanism of amphiregulin on acute respiratory distress syndrome in mice / 中华危重病急救医学

OBJECTIVE@#To explore the protective effect of amphiregulin (Areg) on acute respiratory distress syndrome (ARDS) in mice and its underlying mechanism.@*METHODS@#(1) Male C57BL/6 mice aged 6-8 weeks were selected for animal experiments and divided into 3 groups (n = 10) according to the random number table method, which includes sham-operated group (Sham group), ARDS model group [ARDS model in mice was established by intratracheal instillation of lipopolysaccharide (LPS) 3 mg/kg] and ARDS+Areg intervention group [recombinant mice Areg (rmAreg) 5 μg was injected intraperitoneally 1 hour after LPS modeling]. The mice were sacrificed at 24 h after LPS injection lung histopathological changes were observed under hematoxylin-eosin (HE) staining and scored for lung injury; oxygenation index and wet/dry ratio of lung tissue were measured; the content of protein in bronchoalveolar lavage fluid (BALF) was detected by bicinchoninic acid (BCA) method, the level of inflammatory factors interleukins (IL-1β, IL-6) and tumor necrosis factor-α (TNF-α) in BALF were measured by enzyme-linked immunosorbent assay (ELISA). (2) Mice alveolar epithelial cell line MLE12 cells were obtained and cultured for experiment in vitro. Blank control group (Control group), LPS group (LPS 1 mg/L) and LPS+Areg group (rmAreg 50 μg/L was added 1 hour after LPS stimulation) were set. The cells and culture fluid were collected at 24 hours after LPS stimulation, and the apoptosis level of MLE12 cells was detected by flow cytometry; the activation level of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and the expressions of apoptosis-related proteins Bcl-2 and Bax in MLE12 cells were detected by Western blotting.@*RESULTS@#(1) Animal experiments: compared with the Sham group, the lung tissue structure of ARDS model group was destroyed, the lung injury score was significantly increased, the oxygenation index was significantly decreased, the wet/dry weight ratio of lung was significantly increased, and the levels of protein and inflammatory factors in BALF were significantly increased. Compared with ARDS model group, lung tissue structure damage was reduced, pulmonary interstitial congestion, edema and inflammatory cell infiltration were significantly reduced, and lung injury score was significantly decreased (scores: 0.467±0.031 vs. 0.690±0.034) in ARDS+Areg intervention group. In addition, oxygenation index in ARDS+Areg intervention group was significantly increased [mmHg (1 mmHg ≈ 0.133 kPa): 380.00±22.36 vs. 154.00±20.74]. Lung wet/dry weight ratio (5.40±0.26 vs. 6.63±0.25), protein and inflammatory factors levels in BALF [protein (g/L): 0.42±0.04 vs. 0.86±0.05, IL-1β (ng/L): 30.00±2.00 vs. 40.00±3.65, IL-6 (ng/L): 190.00±20.30 vs. 581.30±45.76, TNF-α (ng/L): 30.00±3.65 vs. 77.00±4.16], and the differences were statistically significant (all P < 0.01). (2) Cell experiments: compared with the Control group, the number of apoptotic MLE12 cells was significantly increased in the LPS group, and the levels of PI3K phosphorylation, anti-apoptotic gene Bcl-2 level and pro-apoptotic gene Bax level were increased in MLE12 cells. Compared with the LPS group, the number of apoptosis in MLE12 cells was significantly reduced in the LPS+Areg group after administration of rmAreg treatment [(17.51±2.12)% vs. (36.35±2.84)%], and the levels of PI3K/AKT phosphorylation and Bcl-2 expression in MLE12 cells were significantly increased (p-PI3K/PI3K: 2.400±0.200 vs. 0.550±0.066, p-AKT/AKT: 1.647±0.103 vs. 0.573±0.101, Bcl-2/GAPDH: 0.773±0.061 vs. 0.343±0.071), and Bax expression was significantly suppressed (Bax/GAPDH: 0.810±0.095 vs. 2.400±0.200). The differences were statistically significant (all P < 0.01).@*CONCLUSIONS@#Areg could alleviate ARDS in mice by inhibiting the apoptosis of alveolar epithelial cells through activating PI3K/AKT pathway.

Establishment of pancreatic acinar cell line AR42J with stable knockdown of Beclin1 / 中华胰腺病杂志

Objective To silence the beclin1 gene expression by using RNA interference technology in AR42J rat pancreatic acinar cells,and build a stable AR42J line silencing beclin1.Methods Three kinds of shRNA targeting rat beclin1 mRNA and negative control shRNA were designed and synthesized,and were inserted into the plasmids GV112,respectively.The recombinant plasmids were named as p-sh-Beclin1-1,psh-Beclin1-2,p-sh-Beclin1-3 and p-shRNA-NC.Lipo3000 was used to transfect the recombinant plasmid into AR42J cells,the expression of beclin1 mRNA were detected by RT-PCR to screen for the most efficient silencing plasmid,and then it was packaged into lentiviral (LV).AR42J cells were infected with LV and screened by puromycin.Beclin1 mRNA and protein expression was determined by RT-PCR and Western blot.Results The recombinant plasmid was confirmed by agarose gel electrophoresis and sequencing showed that shRNA sequences were in line with expectations.The beclin1 mRNA inhibition rates of AR42J cells after p-sh-Beclin1-1,p-sh-Beclin1-2,p-sh-Beclin1-3 and p-shRNA-NC transfection were (17.8 ± 4.0) ％,(30.6 ± 2.8) ％,(45.8 ± 7.7) ％,(7.0 ± 11.8) ％,respectively.The inhibition rates of three p-sh-Beclin1 transfection cells were significantly higher than that in non-transfection cells,and the difference was statistically significant (P ＜ 0.05).While the inhibition rate of p-shRNA-NC transfection cells was not significantly different from that of non-transfection cells,p-sh-Beclin 1-3 with highest rate of inhibition was packaged by LV,and infected AR42J cells,then puromycin was applied to screen,inhibition rate of beclin mRNA expression in LV infection cells was (86.1 ± 1.2) ％,and the protein expression inhibition rate was (87.9 ± 2.8) ％,and the difference between infection and non-infection groups was statistically significant (P ＜ 0.05).Conclusions The stable AR42J line silencing beclin1 is successfully established,which can provide a new cell model for future research of the role of beclin1 in the pathogenesis of acute pancreatitis.

Establishment of a stable AR42J cell line expressing EGFP LC3 / 中华胰腺病杂志

Objective To establish a stable AR42J cell line expressing EGFP LC3.Methods The EGFP LC3 overexpressed Lentivirus was constructed and transfected into pancreatic acinar cells (AR42J) of rats.The rats with Lentiviral EGFP transfection were treated as negative control.The transfection efficiency was detected by inverted fluorescence microscope and flow cytometry.The EGFP LC3 protein expression in the stable cell lines were analyzed by Western blot.The cells were treated with thapsigargin to establish endoplasmic reticulum stress model,and the LC3,PERK protein expressions were detected by Western blot.Results The transfection efficiency of Lentiviral EGFP LC3 of AR42J cell was ＞ 85％,which could achieve stable passage.The expression of LC3 mRNA of AR42J cells transfected with Lentiviral EGFP LC3 was 9.14 ±0.32 folds higher than that of negative control,which had no expression of LC3 protein,only EGFP expression.However,compared with non-transfection group,the LC3 mRNA expression in EGFP group was not significantly different.Conclusions A pancreatic acinar cell line (AR42J) of rat stably expressing EGFP LC3 protein is successfully constructed.And it may provide a new model for further research of the relationship between acute pancreatitis and autophagy.