Neutrophil gelatinase-associated lipocalin as a potential novel biomarker for ventilator-associated lung injury

Neutrophil gelatinase‑associated lipocalin (NGAL) is a 25‑kDa protein of the lipocalin superfamily and its presence was initially observed in activated neutrophils. It has previously been demonstrated that the expression of NGAL is markedly increased in stimulated epithelia, and is important in the innate immunological response to various pathophysiological conditions, including infection, cancer, inflammation and kidney injury. The present study constructed a ventilator‑associated lung injury model in mice. NGAL mRNA and protein expression levels in lung tissue were detected using reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. In addition, NGAL protein levels in bronchoalveolar lavage fluid and serum were measured via western blotting. The results of the present study suggested that NGAL expression increased under all mechanical ventilation treatments. The increase was most prominent in the high peak inflation pressure and high‑volume mechanical ventilation groups, where there was the greatest extent of lung injury. In addition, NGAL expression increased in a time‑dependent manner under high‑volume mechanical ventilation, consistent with the degree of lung injury. These findings suggested that NGAL may serve as a potential novel biomarker in ventilator‑associated lung injury.