A pilot study of circulating <i>miR</i><i>‑</i><i>361-5p</i> and <i>miR-3125</i> in active tuberculosis patients in Babylon Province, Iraq

Tuberculosis (TB) remains a major global health challenge and is closely linked to host immune responses to Mycobacterium tuberculosis.MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of immune and inflammatory pathways and may serve as potential diagnostic biomarkers.This pilot study aimed to explore the diagnostic potential of serum miR-361-5p and miR-3125 in active pulmonary tuberculosis included 150 clinically suspected TB cases, of which 35 were laboratory-confirmed, along with 25 healthy controls. Diagnosis was performed using Acid-Fast Bacilli (AFB) smear microscopy (20.6% detection), Löwenstein–Jensen culture, and the GeneXpert MTB/RIF assay (23.3% detection). Serum levels of miR-361-5p and miR-3125 were measured by RT-qPCR and normalized using the 2^−ΔΔCt method. Both miRNAs were significant level upregulated in TB patients compared to controls. miR-361-5p levels were 6.73 ± 13.21 vs. 1.57 ± 1.7 (p = 0.0487), while miR-3125 levels were 3.48 ± 1.87 vs. 1.24 ± 0.62 (p < 0.0001). Median (IQR) values further supported these findings, particularly for miR-3125, which showed more consistent upregulation. ROC analysis demonstrated high diagnostic accuracy for miR-3125 (AUC = 0.92, sensitivity = 89%, specificity=79%), whereas miR-361-5p showed limited performance (AUC = 0.547). Additionally, miR-3125 levels were significantly higher in rifampicin-resistant patients than in sensitive cases (4.92 ± 2.1 vs. 3.12 ± 1.7; p = 0.007), where miR-361-5p showed no significant association. This pilot study shows that serum miR-361-5p and miR-3125 are elevated in active TB, with miR-3125 potentially serving as a biomarker for rifampicin resistance, indicating it could be useful as a non-invasive tool for early TB detection.