Effects And Mechanism Of Fecal Transplantation On Acute Lung Injury Induced By Lipopolysaccharide In Rats

Abstract:Objective:By fecal bacteria transplantation（FMT）deal with lipopolysaccharide（LPS）in rats induced by acute lung injury（ALI）,research in lung tissue of intracellular phosphatidyl inositol kinase（PI3K）/protein kinase（AKT）/-nuclear factor（NF）kappa B predominate signal path expression regulation of fecal bacteria transplanted intervention and its possible mechanism of ALI,offers a new method for early treatment of ALI and possible experimental basis.Methods:Using the random number table method,will be15 healthy adult male SD rats were divided into control group,model group and intervention group,each group 5,model group and intervention group respectively intraperitoneal injection of LPS duplicate the ALI rats model,completed building after 24 h,intervention group give daily waste（10 ml/kg）to fill the stomach 2 times,the control group and model group at the same time gives the amount of normal saline lavage,intervention in the last 2 days,24 h after the last time in FMT,extraction of three groups of rats arterial blood line detection,arterial blood gas analysis and then put to death in the rat,Enzyme linked immunosorbent（ELISA）to detect serum,bronchoalveolar lavage fluid（BALF）of intercellular adhesion molecule-1（ICAM-1）content,remove the left lung to detect lung wet/dry weight ratio,right lung line HE staining and lung tissue pathology score,immunohistochemical detection of alveolar epithelial cells of the NF-kappa B nuclear expression and ICAM-1 expression levels,Western imprinting method to detect PI3K/AKT signaling pathway related protein expression.The fecal samples of rats were collected and DNA was extracted.The PCR products of the V3 and V4 regions of the 16S ribosomal RNA gene（16SrDNA）were high-throughput sequenced,and the bioinformatics analysis of the microbial community based on the operational classification unit（OTU）was performed.Results:Compared with the control group,the ratio of wet to dry lung weight（W/D）in model group was increased（3.40±0.91 vs1.74±0.73,P<0.05）,lung histopathological score increased（score:10.32±0.23vs 1.87±0.54,P<0.05）,the partial pressure of arterial blood oxygen（PaO₂）decreased significantly[（79.20±5.89）mmHg vs（95.20±2.77）mmHg,1mmHg=0.133kpa,P<0.05];The results of intestinal microflora sequencing revealed that the control group contained 1213 OTU,the model group contained 1303 OTU,the intervention group contained 1207 OTU,the Shared OTU was 593,and the percentage of Shared OTU was 67.5%.The diversity index of model group was significantly higher than that of the control group,while the firmicutes（at the phylum level）and lactobacillus（at the genus level）of model group were significantly lower than that of the control group,and the intestinal flora structure was relatively unstable;The relative expression of ICAM-1 in serum and BALF of model group and its membrane were significantly higher than that of control group[（8.64±0.87）vs（7.40±0.32）ng/L,（0.941±0.035）vs（0.739±0.079）ng/L,（0.250±0.010）vs（0.076±0.010）]（all P<0.05）.The relative expression levels of NF-κB p-P65,p-PI3K and p-AKT（p for phosphorylation）in model group were significantly higher than those in control group（4.89±0.27vs 3.28±0.13,0.265±0.030 vs 0.036±0.013 and 0.444±0.040 vs 0.109±0.016）（all P<0.05）.The above injury effect was reduced after FMT.Lung W/D（2.11±0.81）and lung histological score（5.28±0.94）in intervention group were significantly lower than those in model group,and PaO₂[（88.00±3.53）mmHg]in intervention group were significantly higher than those in model group.The results of intestinal flora sequencing revealed that the diversity index of intervention group was significantly lower than that of model group,and the lactobacillus genus of intervention group was significantly higher than that of model group.ICAM-1 for（7.44±0.46）ng/L in blood serum,for（0.834±0.040）ng/L in BALF and the relative expression of alveolar epithelial cell membrane for（0.173±0.030）,the NF-κB p-P65 in relative expression quantity of protein in alveolar epithelial cells（2.99±0.28）,p-PI3K and p-AKT protein relative expression was downgraded to（0.090±0.013,0.206±0.018）,the detection index in intervention group were significantly lower than that of model group,the differences were statistically significant（all P<0.05）.Conclusion:the 5 mg/kg LPS 1 intraperitoneal injection can be copied in the rat model of ALI and ALI of rat intestinal flora imbalance,FMT can correct the imbalance of intestinal flora structure of transplantation,recovery of intestinal flora of rats after ALI inflammation of the lung tissue was improved,its regulation and control mechanism may be related to the inhibition of PI3K/AKT/NF-κB signaling pathway activation,reduce inflammation factors such as ICAM-1 expression.