Pilot study of microRNA expression in bronchoalveolar lavage and urine in burn patients with inhalation injury

Inhalation injury (INHI) in burn patients is currently diagnosed using invasive and subjective procedures. Identifying molecular biomarkers such as microRNAs (miRNAs) may help improve diagnostic accuracy and standardization. This pilot prospective study investigated the miRNA expression profiles in bronchoalveolar lavage (BAL) and urine samples from burn patients with high-grade (HG) and low-grade (LG) INHI. Samples were collected at two time points during hospitalization: Day 1 (immediately post-injury) and Day 14 (after acute effects had subsided). Whole miRNome sequencing was performed using next-generation sequencing. Thirty-four miRNAs in BAL and ten in urine showed differential expression between time points. Twelve miRNAs in BAL and eight in urine were overexpressed on Day 1. Eight BAL miRNAs were associated with INHI severity; notably, miR-34c-3p and miR-12136 were linked to HG INHI on Day 1, but this association was no longer evident by Day 14. No miRNAs in urine were associated with INHI severity. These results suggest that specific BAL miRNAs, particularly miR-34c-3p, may serve as potential biomarkers for early diagnosis of severe inhalation injury in burn patients.