The Mechanism Of Estrogen-mediated Attenuation Of ALI By Sepsis Base On Mitochondrial Biogenesis

Aim: Acute lung injury(ALI)and its serious form acute respiratory distress syndrome(ARDS)is a common and lethality syndrome,and its mortality was up to 24%-60%.Sepsis is a common reason of acute lung injury,the apoptosis of alveolar epithelial cells induced by mitochondrial injury is an important mechanism in the pathogenesis of sepsis associated with acute lung injury.Studies had shown that increased mitochondrial biogenesis can attenuate acute lung injury,while there were other researches indicate that estrogen can increase mitochondrial biogenesis via PGC1/NRF/TFAM signaling pathway.As a result,this study intend to investigate the mechanism of estrogenmediated attenuation of ALI.Method: 1,First of all,we adopted female SD rat ovariectomy(OVX)model,then we measured the uterine weight/final weight in 2 weeks after operation.2,Then,we used acute lung injury model induced by LPS as well as estrogen(E2)treatment at the same time.The experiment was divided into 6 groups: sham operation(SHAM),OVX,SHAM+LPS,OVX+LPS,SHAM+LPS+E2.After 6 hours of stimulation,we tested the following indicators: lung HE staining,MPO immunohistochemical,TUNEL staining,lung dry/wet ratio,lung ATP,mitochondrial DNA(mt DNA)level,PGC1/NRF/TFAM m RNA and protein level.3,We cultured human A549 cells in vitro,the cells were divided into 3 groups: CON,LPS,LPS+E2.After 24 hours of stimulation,we detected following outcomes: apoptosis,ATP,mt DNA level,PGC1/NRF/TFAM m RNA and protein level.Results:1,After 2 weeks of ovariectomy,OVX group significantly reduce uterine weight/final weight ration compared to non-OVX.These results indicate that after ovariectomy,estrogen levels were significantly decreased in rats.2,HE staining showed that LPS could cause obviously pathological damage and the injury of OVX group was more serious than that of its control group,estrogen treatment can significantly ameliorate the lung damage caused by LPS.;MPO Immunohistochemistry show that LPS could significantly increase the expression of MPO,and the expression of MPO in OVX+LPS group was higher than SHAM+LPS group,while estrogen treatment could significantly reduce the expression of MPO.;TUNEL staining showed that LPS significantly increased the proportion of apoptosis,in which the proportion of apoptotic cells in OVX+LPS group was higher than SHAM+LPS group,estrogen treatment significantly reduced the proportion of apoptotic cells induced by LPS.;The lung Wet/Dry ratio showed that LPS significantly increased the Wet/Dry ratio,while estrogen treatment could decrease Wet/Dry ratio.These results indicate that estrogen play a critical role in the rats with acute lung injury,a lower level of estrogen result in aggravating lung injury,while estrogen treatment could significantly alleviate lung injury caused by LPS.3,Detection of mt DNA and ATP showed that LPS could significantly decrease the expression of mt DNA and ATP content,and estrogen treatment could restore such change.The results of flow cytometry showed that the apoptosis of LPS group was significantly increased compared with the control group,while estrogen could significantly reduce the apoptosis induced by LPS.These results suggest that sepsisrelated lung injury can significantly increase the number of lung mitochondrial and ATP content.Estrogen treatment can increase the number of lung mitochondrial and ATP content,and inhibit the apoptosis of lung cells.4,Animal and cell experiments showed that estrogen can increase the expression of PGC1? /NRF2/TFAM m RNA and protein level.These results indicate that estrogen can up-regulate PGC1? /NRF2/TFAM signaling pathway.Conclusion Estrogen may enhance mitochondrial biogenesis through up-regulation of PGC1? /NRF2/TFAM signaling pathway,increasing the number of mitochondria in lung tissue of rats,increasing ATP content,reducing cell apoptosis in lung tissues of rats so as to reducing acute lung injury.