Whole transcriptomic analysis in rat Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a common acute and critical illness in the field of critical care medicine. An international epidemiological LUNG SAFE study showed that the incidence of ARDS among the intensive care unit (ICU) patients was about 10%. In recent years, severe acute respiratory infections, which endanger human health, have been frequently occurring, such as severe acute respiratory syndromes (SARS) in 2003, influenza A (H1N1) in 2009, and novel coronavirus pneumonia (Corona Virus Disease-19, COVID-19; the latter is still spreading around the world). Most of the critically ill patients progress to ARDS, having a fatality rate of over 40%. Although significant advancements have been made in understanding and treating the pathophysiology of ARDS in the past 20 years, the mechanism of acute lung injury in endogenous ARDS has not been fully understood yet. Furthermore, the specific biomarkers and effective therapeutic targets are also lacking. In the present study, RNA-seq technology was used to study the expression profiles of lung injury genes in the endogenous subtype of lipopolysaccharide (LPS)-induced ARDS, and the key genes and pathways were screened. This study was approved by the Medical Ethics Committee of Lianyungang Clinical College of Nanjing Medical University and all the animal experiments were performed strictly according to the requirements of animal ethics (Number: KY20200311001,Date: March 11, 2020). A total of 12 healthy clean-grade male Sprague Dawley rats were selected, which were 6-8 weeks old, weighing 230-250 grams each. Mice were divided randomly into blank control group (N group) and experimental group (LPS group) with 6 animals in each group. The endogenous ARDS lung injury rat models (LPS group) were established by instilling LPS (Sigma-Aldrich, USA; 10 mg/kg) into their airways. After 36 h, all the rats were anesthetized by the intraperitoneal injection of xylazine (Sigma-Aldrich, USA; 8 mg/kg) and ketamine (Hengrui, China; 80 mg/kg). After successful anesthetization, the rats were sacrificed by cardiac puncturing and bloodletting and the sample specimens were collected for examination. The total RNA was extracted from the lung tissues using RNA extraction kits (Thermo Ficher Scientific, USA). The purity and RNA integrity factor of the extracted RNA samples were detected using Thermo Nanodrop one ultra-micro spectrophotometer and Agilent2100 bioanalyzer (Santa Clara, CA, USA), respectively, in order to meet the requirements of subsequent sequencing quality. the paired-end sequencing mode of the Illumina HiSeq sequencing platform was used for the high-throughput sequencing of multiple samples. The purpose of this study was to provide some ideas for studying the mechanism of endogenous ARDS lung injury and exploring the therapeutic targets and specific biomarkers.