MicroRNA expression profiles in bronchoalveolar lavage and urine samples from burn patients with inhalation injury: a pilot prospective study

Diagnosis of inhalation injury (INHI) is invasive and subjective. Molecular biomarkers, such as microRNAs (miRNAs) in bronchoalveolar lavage (BAL; invasive) or urine (non-invasive) samples, may help standardize the diagnosis. This study aimed to compare miRNA expression profiles in these two matrices from burn patients with INHI at two time points of hospitalization and relate them to INHI severity. In this pilot prospective study, BAL and urine samples from burn patients with high-grade (HG) and low-grade (LG) INHI were collected on Days 1 (immediately after injury) and 14 (after the acute effects had subsided) of hospitalization. The whole miRNome was investigated by next-generation sequencing. Expression of 34 miRNAs in BAL samples and 10 in urine differed between the two time points. Twelve BAL and eight urine miRNAs were overexpressed on Day 1 compared to Day 14. Eight miRNAs in BAL were linked with INHI severity: in particular, miR-34c-3p and miR-12136 were associated with HG INHI on Day 1, but differences disappeared by Day 14. No miRNAs in urine were associated with INHI severity. The association of miR-34c-3p with HG INHI in BAL confirms findings from an animal model, supporting its potential as a biomarker for HG INHI. • Investigation of miRNAs as possible biomarkers of inhalation injury (INHI) • Some miRNAs in bronchoalveolar lavage were higher in the acute than late stage • miR-34c-3p may serve as biomarker of INHI severity at the early stage of INHI