Effect Of Human Amniotic Mesenchymal Stem Cells Transplantation On The Expression Of Aquaporin 1 In Lung Tissue Of Rats With Lipopolysaccharide-induced Acute Lung Injury

Objective:To observe the effect of the transplantation of human amniotic mesenchymal stem cells(h AMSCs)on the expressions of Aquaporin 1(AQP1)and phosphorylated p38mitogen activated protein kinase(p-p38 MAPK)in lung tissue of rats with lipopolysaccharide(LPS)-induced acute lung injury(ALI),and to further identify whether h AMSCs can reduce lung injury and its possible mechanism,so as to provide new insights for the treatment of ALI.Methods:A total of 84 male Sprague-Dawley(SD)rats were randomly divided into four groups:normal saline control group(NS group),LPS-induced ALI model group(LPS group),h AMSCs control group(NH group)and h AMSCs intervention group(LH group).Rats in the LPS group and LH group were injected with LPS(4mg/kg)through a sublingual vein to construct the experimental model.Rats in the NS group and NH group were injected with 250μL normal saline through a sublingual vein.Rats in the NH group and LH group were injected with 250μL DAPI labeled h AMSCs(2.5×10~6cells)through the caudal vein 2h later.While rats in the NS group and LPS group were injected with250μL normal saline through a caudal vein.Seven rats in each group were randomly killed at 6h,12h and 72h for sampling.The colonization of h AMSCs in the lung tissue of rats in the NH group and LH group was observed by fluorescence microscope;and the pathological morphology of lung tissue in each group was observed under a optical microscope.The lung wet/dry weight(W/D)ratio in each group was measured as an index of alveolar fluid clearance.Furthermore,the levels of tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in bronchoalveolar lavage fluid(BALF)of rats in each group were detected by enzyme linked immunosorbent assay(ELISA).Immunohistochemistry(IHC)was used to detect the expressions of AQP1,p38 MAPK and p-p38 MAPK in the lung tissue of each group.Moreover,the protein expressions of AQP1,p38 MAPK and p-p38MAPK in lung tissue of each group were tested by western blot(WB).Results:1.Under the fluorescence microscope,it could be observed that there were blue fluorescent labeled h AMSCs around the alveoli of rats in NH and LH groups.Among them,the distribution of h AMSCs was more in the LH group and less in the NH group,indicating the possibility of colonization of h AMSCs in the injured lung tissue.2.There was no significant difference in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,AQP1 and p-p38 MAPK protein expressions between NS group and NH group at each time point(P>0.05).3.Compared with the NS group and NH group at each time point,the LPS group and LH group showed an increase in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,and p-p38 MAPK protein expression,and decrease in AQP1 expression at corresponding time points(P<0.05).4.Intra-group comparison of the LPS group revealed that there was no significant difference in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,AQP1 and p-p38 MAPK protein expressions at the time points of 6h and 12h(P>0.05).Compared with LPS 6h group and the LPS 12h group,LPS 72h group exhibited a decrease in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,and p-p38MAPK protein expression,and increase in AQP1 expression(P<0.05).Furthermore,there was no significant difference in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,and p-p38 MAPK protein expression,and decrease in AQP1 expression between LH 6h group and LH 12h group(P>0.05).While in relative to LH 6h group and LH 12h group,LH 72h group revealed a decrease in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,and p-p38 MAPK protein expression,and increase in AQP1 expression(P<0.05).In addition,compared with the LPS group at each time point,LH showed a decrease in lung histopathological score,W/D ratio,TNF-αand IL-1βlevels in BALF,and p-p38 MAPK protein expression,and increase in AQP1 expression at corresponding time points(P<0.05).5.There was no significant difference in the expression of p38 MAPK in lung tissue at each time point among the NS group,NH group,LPS group and LH group(P>0.05).Conclusion:h AMSCs can inhibit the activation of p38 MAPK,decrease the release of inflammatory factors TNF-αand IL-1β,and reduce pulmonary inflammatory response;moreover,intravenous transplantation of h AMSCs can upregulate the expression of AQP1in lung tissue to enhance alveolar fluid clearance,so as to alleviate lung injury.