Inflamma-miRs Profile in Myelodysplastic Syndrome Patients

Abstract

Etiological factors involved in myelodysplastic syndrome (MDS) include immunologic, oxidative stress and inflammatory factors, among others, and these are targets for microRNAs (miRNs). Here, we evaluated whether some miRNs may affect tumor development comparing untreated and 5-azacitidine (5-AZA) MDS-treated patients. Peripheral blood samples were collected from 20 controls and 24 MDS patients, and selected miRNs related to redox balance and inflammation (inflamma-miRs), including miR-18a, miR-21, miR-34a and miR-146a, were isolated and measured by quantitative real-time polymerase chain reaction (qRTPCR). A differential expression profile of miRNs was detected in untreated MDS patients and the 5-AZA group. Inflammation increases miRNs and, specifically, miR-18a, miR-21 and miR-34a were significantly overexpressed in untreated MDS, compared to controls. However, we did not observe any miRN profile alteration during the progression of the disease. On the other hand, 5-AZA treatment tends to restore miRN expression levels. Relating to prognostic risk factors, high-risk MDS groups (high Revised International Prognostic Scoring System (IPSS-R), high cytogenetic risk, high molecular risk (HMR) mutations) tended to be related with higher expression levels of miR-18a and miR-34a. Higher miRN expression is correlated with lower glutathione peroxidase activity, while they are related with a higher profile of pro-inflammatory cytokines (IL-2, IL-6, IL-8, TNF-α). Although our study was limited by the low number of MDS patients included, we identified miRN deregulation involved in MDS development that could regulate redox sensors and inflammatory responses. Finally, 5-AZA treatment is related with lower miRN expression levels in MDS patients.

Keywords: 5-azacitidine (5-AZA); inflammatory cytokines; microRNAs (miRNs); myelodysplastic syndrome (MDS); oxidative stress.

Figure 1

Changes in the relative expression of the miRN transcripts in MDS untreated (n = 19) and MDS 5-AZA-treated (n = 7) patients. The following miRN levels are represented: (A) miR-18a, (B) miR-21, (C) miR-34a, (D) miR-146a. Data are expressed as means ± SEM of miRNs (miR), using miR-30b as an endogenous control in plasma samples of 24 myelodysplastic syndrome (MDS) patients and controls. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001 vs. control.

Figure 2

The relative expression of the miRN transcripts in MDS untreated patients (n = 19) during the disease progression. The relative expression of (A) miR-18a, (B) miR-21, (C) miR-34a and (D) miR-146a is represented. Data are expressed as means ± SEM of miRNs (miR), using miR-30b as an endogenous control in plasma samples of 19 untreated myelodysplastic syndrome (MDS) patients according to the disease progression: Early Stage (ES) untreated MDS (n = 13) and Advanced Stage (AS) untreated MDS (n = 6). No significant differences were observed (p > 0.05).

Figure 3

The relative expression of (A,E,I) miR-18a, (B,F,J) miR-21, (C,G,K) miR-34a and (D,H,L) miR-146a, using miR-30b as an endogenous control in plasma samples of 24 patients with myelodysplastic syndrome (MDS), classified according to the following risk prognostic factors: IPSS-R score (A–D) (high risk, n = 9; low risk, n = 10), cytogenetic risk (E–H) (favorable, n = 15; unfavorable, n = 4); and molecular risk (I–L) (high risk, n = 12; low risk, n = 6). The p values were calculated by the non-parametric Mann–Whitney test. Data are presented as mean ± SEM. * p < 0.05 vs. control.

Figure 4

Correlation analysis between (A) miR-21 and CAT activity, miR-18a and TNF-α (B), and miR-146a and IL-6 (C) in MDS patients. Analysis was conducted with the Pearson’s correlation coefficient.