Background: Mechanical ventilation is a dispensable work in clinical treatment and rescue, and always caused of ventilator-induced lung injury (VILI). Dexmedetomidine is a clinical drug to prevent lung injury, but its mechanism still unclear.Methods: Thirty-six SD rats were randomly divided into three groups: self-breathing control group (Group C), high tidal volume (V T 20 mL/kg) group (Group H) and high V T + dexmedetomidine group (Group DEX). Serum, lung tissue, bronchoalveolar lavage fluid (BALF) were collected after rats were sacrificed by anesthetic drug of pentobarbital sodium. The pathological changes of lung tissue were observed by hematoxylin and eosin stain (HE staining), and the lung injury score and wet/dry (W/D) ratio were tested to assess lung injury. The total protein level in BALF and contents of the interleukin-1β (IL-1β), IL-18 in serum and BALF were detected by enzyme-linked immunosorbent assay (ELISA), the mRNA and protein expression level of NLR Family CARD Domain Containing 3 (NLRC3), NLR Family Pyrin Domain Containing 3 (NLRP3), Apoptosis associated speck-like protein containing a CARD domain (ASC) and caspase-1 were measured by qRT-PCR and Western Blotting respectively.Results: Compared with Group C, VILI mode of Group H were success established because of lung injury score and W/D value increased. when compared with Group H, which were decreased significantly in Group DEX (P<0.05), and the total protein level in BALF and the contents of IL-1β, IL-18 in serum and BALF of Group DEX were reduced markedly (P<0.05), Besides the mRNA and protein expression of NLRP3, ASC and caspase-1 in lung tissue of Group DEX were lowered dramatically (P<0.05). However, mRNA and protein expression of NLRC3 in lung tissue of Group DEX were up-regulated observably (P<0.05).Conclusions: This study demonstrates that NLRC3 is involved in the VILI of rats, and dexmedetomidine can attenuate the VILI in rats by up-regulating the expression level of NLRC3.

Urine is a promising resource for biomarker research. Therefore, the purpose of this study was to investigate potential urinary biomarkers to monitor the disease activity of ventilator-induced lung injury (VILI). In the discovery phase, a label-free data-dependent acquisition (DDA) quantitative proteomics method was used to profile the urinary proteomes of VILI rats. For further validation, the differential proteins were verified by parallel reaction monitoring (PRM)-targeted quantitative proteomics. In total, 727 high-confidence proteins were identified with at least 1 unique peptide (FDR ≤ 1%). Compared to the control group, 110 proteins (65 upregulated, 45 downregulated) were significantly changed in the VILI group (1.5-fold change, P < 0.05). The canonical pathways and protein–protein interaction analyses revealed that the differentially expressed proteins were enriched in multiple functions, including oxidative stress and inflammatory responses. Finally, thirteen proteins were identified as candidate biomarkers for VILI by PRM validation. Among these PRM-validated proteins, AMPN, MEP1B, LYSC1, DPP4 and CYC were previously reported as lung-associated disease biomarkers. SLC31, MEP1A, S15A2, NHRF1, XPP2, GGT1, HEXA, and ATPB were newly discovered in this study. Our results suggest that the urinary proteome might reflect the pathophysiological changes associated with VILI. These differential proteins are potential urinary biomarkers for the activity of VILI.