The Mechanism of lncRNA NEAT1 in Alleviating Acute Respiratory Distress Syndrome Through miR-27b Regulated Nrf2 Pathway

The acute respiratory distress syndrome, formerly known as the acute lung injury (ARDS/ALI), is a critical illness with high mortality due to the lack of effective treatment. The pathogenesis of ARDS/ALI has not been fully elucidated. Nuclear factor E2-related factor 2 (Nrf2) plays a key role in regulating lung inflammation and oxidative stress which are closely related to lung injury in ARDS/ALI, but its regulatory mechanism remains unclear. The investigator's provious study shown that microRNA-27b (miR-27b) downregulated Nrf2 to aggravate lung inflammation and histological injury. Furthermore, in lipopolysaccharide (LPS)-induced cell (J774A.1) inflammation model, miR-27b was upregulated while the long non-coding RNA (lncRNA) NEAT1 was downregulated, the putative binding sites of lncRNA NEAT1 and miR-27b were successfully predicted by bioinformatics approach. Thus, the investigators propose that NEAT1 plays as a competing endogenous RNA (ceRNA) to adsorb miR-27b and liberate Nrf2, therefore, to attenuate lung inflammation and related lung injury in ARDS/ALI. This project aims to explore the role of the lncRNA NEAT1/ mir-27b /Nrf2 signal axis in the development and treatment of ARDS/ALI in patients, as well as in LPS-induced ALI animal and cell models by using bioinformatics, molecular biology, histomorphology and clinical phenotype approaches, and to clarify the new mechanism in ARDS/ALI development and to provide new therapeutic targets.

Collect blood and BALF from 400 ARDS patients at different time (at check-in, 24, 48 and 72 h after check-in the hospital) and 25 gender and age matching healthy controls. Use RT-PCR to detect the expression of lncRNA NEAT1、miR-27b and Nrf2 in blood and BALF of ARDS patients and health controls. The expressions of inflammatory and oxidative stress associated factors (NLRP3、NF-κB-P65、 p-P65、IκB、p-IκB、HO-1、NQO1、caspase-1、IL-1β、IL-6、IL-18、TNF-α) will be detected by western blot、ELISA and RT-PCR. Moreover, flow cytometry will be adopted to measure the numbers and kinds of cells in BALF. Then, analyze the differences of the expressions of lncRNA NEAT1、miR-27b and Nrf2 in the groups. To explore the correlation of expressions of lncRNA NEAT1、miR-27b and Nrf2 with inflammation and oxidative stress in the groups. Finally, to declare the relative of lncRNA NEAT1、miR-27b and Nrf2 with the time of mechanical ventilation, severity and mortality in 28 days of ARDS patients.

Eligibility Criteria:
Inclusion Criteria:

We included patients with acute respiratory distress according to 2012 ARDS Berlin new definition (Acute Respiratory Distress Syndrome: The Berlin Definition. JAMA, 2012, 307(23):2526).

* Acute or progressive dyspnea within 1 week with identify cause;
* Chest radiograph/chest CT showed double lung infiltration, which could not be fully explained by pleural effusion, atelectasis, or nodules;
* Respiratory failure cannot be fully explained by heart failure and fluid overload;
* Hypoxemia, partial pressure of oxygen in arterial blood (PaO2)/oxygen fraction in air (FIO2) \<150 mm Hg under PEEP ≥5 cm H2O, (mild ARDS: 200mmHg\<PaO2/FiO2≤300mmHg, moderate ARDS: 100mmHg\<PaO2/FiO2≤200mmHg, severe ARDS: PaO2/FiO2≤100mmHg);
* 18\~70 years old;
* Agree to participate in the trial, and sign the informed consent.

Exclusion Criteria:

* Age less than 18 years old;
* Time of hospital stay \<24 h;
* Pregnancy;
* Using V-V ECOM;
* Cardiac index \<1.5L·ml.min-1.m-2;
* Pulmonary resection;
* Pulmonary embolism ;
* Refused to participate in the study.