This study focused on the impact of the treatment with the hypomethylating agent 5-Azacitidine on the redox status and inflammation in 24 MDS patients. Clinical and genetic features of MDS patients were recorded and peripheral blood samples were used to determine the activity of the endogenous antioxidant defense system (superoxide dismutase, SOD, catalase, CAT, glutathion peroxidase, GPx, and reductase, GRd, activities), markers of oxidative damage (lipid peroxidation, LPO, and advanced oxidation protein products, AOPP). Moreover, pro-inflammatory cytokines and plasma nitrite plus nitrate levels as markers of inflammation, and CoQ10 plasma levels, were also measured. Globally, MDS patients showed less redox status in terms of a reduction in the GSSG/GSH ratio and in the LPO levels, and increased CAT activity compared with healthy subjects, with not changes in SOD, GPx and GRd activities, and AOPP levels. When analyzed the evolution from early- to advanced stages of the disease, the GPx activity, GSSG/GSH ratio, LPO and AOPP increased, with a reduction in CAT. GPx changes were related with the presence of risk factors such as high-risk IPSS-R or mutational score. Besides, there was an increase in IL-2, IL-6, IL-8 and TNF-α plasma levels, with further increase of IL-2 and IL-10 from early to advanced stage of the disease. However, we did not observe any association between inflammation and oxidative stress. Finally, 5-azacitidine treatment generates oxidative stress in MDS patients, without affecting inflammation levels, suggesting that oxidative status and inflammation are two independent processes.

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 the 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, 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 5-AZA group. MiR-18a, miR-21, miR-34a and miR-146a were significantly overexpressed in untreated MDS, compared to controls. However, we did not observe any miRNs profile alteration during the progression of the disease. On the other hand, 5-AZA treatment tends to restore miRNs expression levels. Relating to prognostic risk factors, high risk MDS groups (high 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 miRNs 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 miRNs deregulation involved in the MDS development, that could regulate redox sensors and inflammatory responses. Finally, 5-AZA treatment is related with lower miRNs expression levels in MDS patients.