Protective Effects Of DNMT Inhibitor On LPS Induced Acute Respiratory Distress Syndrome And Its Mechanisms

Objective:This study examined the effects of DAC and Aza on inflammatory and oxidative injuries,as well as on glycocalyx and MAPK signaling pathways,in a LPS-stimulated ARDS mouse model.Methods:Thirty-two C57BL/6 mice were randomly allocated into control,LPS,LPS+DAC,and LPS+Aza groups.DAC(1 mg/kg)or Aza(1 mg/kg)were intraperitoneally injected to mice.After 1 h,the model group,DAC pretreatment,and Aza pretreamentmice were intraperitoneally injected with LPS(20 mg/kg)to generate ARDS.The control group received equal volume of normal saline(NS)instead of LPS in the same manner.At 6 h after LPS administrated,the mice were euthanized and plasma was harvested from the collected orbital venous plexus and the lungs were excised by blunt dissection.TNF-?,IL-1?,MPO,MDA,HS,and HA were evaluated with the corresponding ELISA kits in accordance with the manufacturer's instructions.Hematoxylin and eosin staining and lung Wet/Dry weight ratio were performed according to to assess lung injury and pulmonary edema.Pulmonary endothelial glycocalyx was performed by electron microscopy.Bisulfite sequencing PCR and real time-PCR showed that DAC reversed the RASSF1A promoter hypermethylation and furthermore elevated the expression of RASSF1 A.Results:DAC and Aza significantly inhibited the production of TNF-? and IL-1?and prevented LPS-induced elevation of MPO and MDA levels in serum.The W/D ratio of lung and HE staining revealed that DAC and Aza pretreatment improved lung tissue injury.DAC and Aza reduced the level of glycocalyx degradation products(e.g.,HS and HA)and protected glycocalyx integrity.W-B technology demonstrated that DAC and Aza both suppressed the MAPK signaling pathways by sealing the phosphorylation of JNK,ERK and P38 in lung tissues in LPS-induced ARDS.Bisulfite sequencing PCR and real time-PCR showed that DAC reversed the RASSF1A promoter hypermethylation and furthermore elevated the expression of RASSF1A.Conclusion:DNMT inhibitor could alleviate LPS-induced ARDS damage through anti-inflammation,antioxidative,protecting the endothelial glycocalyx and inhibiting MAPK pathway activation.