ABSTRACT
Objective:To explore the feasibility of U6 and Cel-miR-39 as reference genes for quantitative detection of microRNA (miRNA) in cerebrospinal fluid (CSF) of tuberculous meningitis (TBM), and validate the difference of miRNAs between tuberculous and viral meningitis (VM).Methods:The remaining CSF specimens after routine examination were collected in Beijing Chest Hospital of Capital Medical University. A total of 36 TBM and 34 VM patients were enrolled based on the information in the medical records. Total RNA were extracted from the CSF samples, and Taqman based real-time quantitative PCR (RT-CR) analysis were performed to determine the concentration of the miRNAs in CSF. GeNorm, NormFinder and Bestkeeper software were used for stability analysis of the two reference genes. 2 -ΔCt method was used to determine the relative gene expression. Accordance of repeated tests was analyzed by Pearson correlation test. Continuous variables were compared by the t-test. Results:Among the 70 samples, the average cycle threshold (Ct) value of U6 was 30.40±3.30, while the average Ct value of Cel-miR-39 was 21.49±0.70. The expression level of Cel-miR-39 was higher than that of U6. Correlation analysis showed good accordance of the repeated tests among the reference genes and target genes analysis in the randomly selected 10 samples ( r>0.931, P<0.001). Based on the analyses results of the three software, including GeNorm, NormFinder and Bestkeeper, Cel-miR-39 presented better stability in RT-PCR analysis and was more suitable as a reference gene for miRNA quantitative determination in CSF sample of TBM patients. The relative expression levels of the three target miRNAs were calculated using Cel-miR-39 as the reference gene, and miR-126-3p (1.13±0.41 vs 3.34±0.82, t=2.452, P=0.016), miR-130a-3p (0.56±0.10 vs 2.59±0.70, t=2.960, P=0.004) and miR-151a-3p (0.64±0.25 vs 2.11±0.33, t=3.536, P<0.001) were showed significant lower expression levels in CSF in TBM group than that in VM group. Conclusions:Cel-miR-39 can be used as a reference gene for quantitative detection of miRNAs in CSF of TBM patients. Significant differences were detected in expression level of miR-126-3p, miR-130a-3p and miR-151a-3p between TBM and VM group.