Nasal mucosal microRNA expression in children with respiratory syncytial virus infection

Abstract

Background: Respiratory syncytial virus (RSV) infection is a common cause of pediatric hospitalization. microRNA, key regulators of the immune system, have not previously been investigated in respiratory specimens during viral infection. We investigated microRNA expression in the nasal mucosa of 42 RSV-positive infants, also comparing microRNA expression between disease severity subgroups.

Methods: Nasal mucosa cytology specimens were collected from RSV-positive infants and healthy controls. 32 microRNA were selected by microarray for qPCR verification in 19 control, 16 mild, 7 moderate and 19 severe disease samples.

Results: Compared to healthy controls, RSV-positive infants downregulated miR-34b, miR-34c, miR-125b, miR-29c, mir125a, miR-429 and miR-27b and upregulated miR-155, miR-31, miR-203a, miR-16 and let-7d. On disease subgroups analysis, miR-125a and miR-429 were downregulated in mild disease (p=0.03 and 0.02, respectively), but not in severe disease (p=0.3 and 0.3).

Conclusion: microRNA expression in nasal epithelium cytology brushings of RSV-positive infants shows a distinct profile of immune-associated miRNA. miR-125a has important functions within NF-κB signaling and macrophage function. The lack of downregulation of miR-125a and miR-429 in severe disease may help explain differences in disease manifestations on infection with RSV.

Figure 1

miRNA Microarray of nasal mucosa brushings in infants infected with Respiratory syncytial virus , compared to healthy controls. Note: Only miRNAs significant in the microarray (p < 0.05, adjusted for a false discovery rate of 5%) are shown. For each miRNA, results are calibrated to the mean of the control group for that miRNA. Number of samples: Control 13, Mild RSV disease 13; Severe RSV disease 14. miRNAs are grouped according to results of Limma analysis, as compared to the control group: Group A: Upregulation in RSV disease. Group B: Upregulation in severe disease; downregulation in mild disease. Group C: Downregulation in mild disease; not regulated in severe disease. Group D: Downregulation in RSV disease.

Figure 2

Nasal mucosal miRNA expression in infants infected with Respiratory syncytial virus, compared to healthy controls. Note: Samples from 42 children with RSV were compared to 19 control samples using qPCR for selected miRNA. Values presented are mean differences between disease and control groups with 95% confidence interval. *Multiple linear regression analysis with correction for RIN. p-values are adjusted for a false discovery rate of 5%.

Figure 3

Nasal mucosal miRNA expression according to disease severity in infants infected with Respiratory syncytial virus . Note: Relative quantities of 4 miRNAs assessed for differential expression between disease severity subgroups. Results are calibrated to the mean of the control group, indicated by the dashed line at a relative quantity 100%. Plotted lines indicate the mean with 95% confidence interval for each group. Numbers in each group: control 19; mild 16; moderate 7; severe 19. For miR-125a there is downregulation in mild and moderate disease groups, but not in the severe group. For miR-429 there is a similar pattern, with downregulation in the mild group but not the severe group. ^† One-way ANOVA, adjusted for a false discovery rate of 5%. * Dunnett’s post-hoc t-test after One-way ANOVA, in which mild, moderate and severe disease severity subgroups are compared individually to the control group, with correction for multiple testing. Up- or downregulation is therefore as compared to the control group.