| Objective: To explore the possible mechanism of fecal microbiota transplantation(FMT)on acute lung injury(ALI)induced by lipopolysaccharide(LPS)in rats,and to study the role of Keap1-Nrf2/ARE signaling pathway in the process of FMT on ALI induced by lipopolysaccharide in rats.Methods: Fifteen healthy male adult SD rats were selected as the research objects of this experiment.The ALI model of rats was created by intraperitoneal injection of lipopolysaccharide,and the fecal bacteria liquid was gavage as an intervention method.The 15 rats were divided into healthy control group(NS group),model experimental group(LPS group),and FMT group by random number table method,with 5 rats in each group.LPS was injected into the abdominal cavity of rats in the LPS and FMT groups at a dose of 5 mg/kg to build an ALI model.Under the same conditions,rats in the NS group were injected with an equal volumeof sterile saline.24 hours after the completion of this model,the FMT group was given self-made fecal bacteria liquid by gavage(10ml/kg,2 times/d,2d in total),and the NS group and LPS group were given gavagesterile normal saline(2ml/time,2 times/d,for 2 consecutive days).24 hours after the completion of the intervention,the blood of abdominal aorta,lung tissue and fresh feces of rats in each group were collected.Abdominal aortic blood samples were used for blood gas and oxygen analysis,mainly to detect the arterial partial pressure of oxygen [p(O)2] and the concentration of superoxide dismutase(SOD),malondialdehyde(MDA)andprotein carbonyl(PCO).Macogenomic classification and sequencing was used to analyze the intestinal flora in feces.Lung tissue was used to measure lung wet/dry weight ratio(W/D).HE staining compares the pathological changes of lung tissues in each group.Immunohistochemical staining was used to detect the expression of NF-E2 related factor 2(Nrf2)in lung tissue.Western blot was used to detect the expression of related proteins downstream of nuclear Nrf2 and Keap1-Nrf2/ARE signal transduction pathway in lung tissue.Results: Compared with the NS group,the lung W/D and HE staining lung injury pathological scores of the rats in the LPS group increased,and the P(O)2decreased.the content of SOD in serum decreased,while MDA and PCO increased[(47.13±3.27)vs(36.92±2.65)pg/ml,(5.99±0.37)vs(9.25±0.43)nmol/ml,(29.41±2.51)vs(43.88±3.65)pg/ml,P<0.05].The relative expression of NRF2 in the nucleus and HO-1 in lung tissue increased[(0.08±0.01)vs(0.17±0.03),(0.09±0.02)vs(0.24±0.08),P<0.05].After FMT,compared with the LPS group,the lung W/D and pathological scores of the FMT group decreased,and the P(O)2 increased;The content of SOD increased,while MDA and PCO decreased[(36.92±2.65)vs(57.37±3.37)pg/ml,(9.25±0.43)vs(7.76±0.45)nmol/ml,(43.88±3.65)vs(36.13±1.99)pg/ml,P<0.05];The relative expression of NRF2 in the nucleus and HO-1 in lung tissue were further increased[(0.17±0.03)vs(0.36±0.06),(0.24±0.08)vs(0.52±0.08),P<0.05].Metagenomic sequencing showed that the abundance,structure,and diversity of the intestinal flora in the LPS group were different from othergroups,and the abundance,structure,and diversity of the intestinal flora of the FMT group were similar to the NS group.Conclusion: FMT may improve rat ALI induced by LPS by regulating the intestinal flora to increase anti-oxidative stress response and reduce oxidative damage-related products through Keap1-Nrf2/ARE signal pathway. |
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