*2.4. MicroRNAs Are Significantly Correlated with Each Other in Th17 and Treg Cells in RA and OA Patients*

Next, we investigated the correlation between examined miRNAs expression in Th17 and Treg cells isolated from RA and control groups: OA patients as well as from healthy subjects. We observed significant, positive correlations between miR-31 and miR-24 (r = 0.73, p = 0.011), between miR-31 and miR-155 (r = 0.76, p = 0.006) in Treg from RA, as well as between miR-126 and miR-26 (r = 0.79, p = 0.003) and between miR-24 and miR-31 (r = 0.62, p = 0.0026) in Th17 cells from RA patients (Figure 9).

**Figure 9.** Correlation between microRNAs in Th17 and Treg cells in RA patients. (**A**) correlation between miR-31 and miR-24; (**B**) correlation between miR-31 and miR-155; (**C**) correlation between miR-126 and miR-26; (**D**) correlation between miR-24 and miR-31.

Figure S1 presents correlations between miRNAs in Treg cells from OA patients. We noticed a significant, positive correlations between miR-155 and miR-24 (r = 0.81, p = 0.001), between miR-155 and miR-26 (r = 0.75, p = 0.004), and between miR-26 and miR-24 (r = 0.62, p = 0.02).

Whereas in OA Th17 cells (Table S2), the highest correlation has been observed between expression of miR-24 and miR-146a (r = 0.70, p = 0.0006), expression of miR-26 and miR-146a (r = 0.83, p < 0.0001), expression of miR-26 and miR-155 (r = 0.89, p < 0.0001); and also between expression of miR-31 and

miR-155 (r = 0.70, p = 0.007), and expression of miR-146a and miR-155 (r = 0.73, p = 0.004). In healthy controls, we have not noticed correlations between examined microRNAs in Th17 and Treg cells.
