Circulating human microRNAs are not linked to JC polyomavirus serology or urinary viral load in healthy subjects

Abstract

Background: JC polyomavirus (JCPyV) is a widespread human polyomavirus that usually resides latently in its host. It can be reactivated under immunomodulating conditions and cause Progressive Multifocal Leukoencephalopathy (PML). Circulating microRNAs (miRNAs) are emerging as promising biomarkers for several pathologies. In this study, we have investigated whether circulating miRNAs exist that are differentially expressed between JCPyV seropositive and JCPyV seronegative on the one hand or between JCPyV shedders and JCPyV non-shedders on the other hand.

Methods: Human miRNA expression profiling was performed in a small set of plasma samples obtained from seronegative subjects, seropositive shedders and seropositive non-shedders. A set of 10 miRNAs was selected for further analysis in a larger group of samples.

Results: Based on the plasma profiling experiment of 30 samples, 6 miRNAs were selected that were possibly differentially expressed between seropositive and seronegative subjects and 4 miRNAs were selected that were possibly differentially expressed between shedders and non-shedders. Subsequently, expression of these 10 selected miRNAs was assessed in an independent set of 100 plasma samples. Results indicated that none of them were differentially expressed.

Conclusion: This study could not identify circulating human miRNAs that were differentially expressed between plasma from JCPyV seropositive and JCPyV seronegative subjects or between JCPyV shedders and JCPyV non-shedders.

Figure 1

Comparison of all miRNAs assessed by RT-qPCR analysis of RNA isolated from plasma of JCPyV seronegative subjects (Ab⁻, n = 10) or JCPyV seropositive subjects (Ab⁺, n = 20). A. Volcano plot of pairwise comparisons. The volcano plot displays the relationship between fold-change and significance between the two groups, using a scatter plot view. The y-axis is the negative log10 of P values (a higher value indicates greater significance) and the x-axis is the difference in expression between two experimental groups as measured in log2 space. MiRNAs that were selected for further analysis are indicated in red on the plot. B. Mann-Whitney p-values, adjusted p-values and fold changes (fc) of JCPyV seronegative subjects (Ab⁻) vs. JCPyV seropositive subjects (Ab⁺) for miRNAs with p-value < 0.05. C. Relative expression levels of selected circulating miRNAs in subjects from each group. Data is presented relative to the mean of the entire population in log10 scale (n = 30).

Figure 2

Comparison of all miRNAs assessed by RT-qPCR analysis of RNA isolated from plasma of subjects with negative urine JCPyV Viral Load (VL⁻, n = 10) or subjects with positive urine JCPyV Viral Load (VL⁺, n = 10). A. Volcano plot of pairwise comparisons. The volcano plot displays the relationship between fold-change and significance between the two groups, using a scatter plot view. The y-axis is the negative log10 of P values (a higher value indicates greater significance) and the x-axis is the difference in expression between two experimental groups as measured in log2 space. MiRNAs that were selected for further analysis are indicated in red on the plot. B. Mann-Whitney p-values, adjusted p-values and fold changes (fc) of subjects with positive urine JCPyV Viral Load (VL⁺) vs. subjects with negative urine JCPyV Viral Load (VL⁻) for miRNAs with p-value < 0.05. C. Relative expression levels of selected circulating miRNAs in subjects from each group. Data is presented relative to the mean of the entire population in log10 scale (n = 30).

Figure 3

Relative expression levels of selected circulating miRNAs in subjects from each group in the validation study (Ab⁻, Ab⁺, VL⁻, VL⁺). Data is presented relative to the mean of the entire population in log10 scale (n = 100). * p-value < 0.05.