miRNA profile and disease severity in patients with sickle cell anemia.

Identification of biomarkers associated with severity in sickle cell anemia is desirable. Circulating serum microRNAs (miRNA) are targets studied as diagnostic or prognostic markers, but few studies have been conducted in sickle cell anemia. The purpose of this study is to identify specific signatures of miRNAs in plasma samples from sickle cell anemia patients according to severity indexes. Screening of the miRNAs expression was performed in 8 patients, classified by tricuspid regurgitation velocity (TRV) measure: 4 with TRV ≥ 2.5 m/s and 4 with TRV < 2.5 m/s. The samples were analyzed by real-time PCR using Megaplex RT Human Pool A and Pool B comprising 667 distinct miRNAs. Seventeen miRNAs were differentially expressed between the two groups (p < 0.05). Five differentially expressed miRNAs (miR15b, miR502, miR510, miR544, miR629) were selected for validation in a cohort of 52 patient samples, 26 with TRV ≥ 2.5 m/s. Another two severity scores were also used: organ injury score (OIS) and Bayesian score (BS). Univariate binary logistic regressions were performed to analyze the data. Five out of 17 differentially expressed miRNAs were selected for validation in 52 patient samples: miR15b, miR502, miR510, miR544, and miR629. Two miRNAs (miR510 and miR629) were significantly decreased in cases of greater severity. Whereas miR510 expression discriminated the patients according to TRV and OIS, miR629 expression did it according to BS. This is the first study investigating plasma miRNAs as possible biomarkers for SCA severity. Our data suggest that low levels of miR510 and miR629 expression are associated with greater SCA disease severity. Further studies are still necessary to elucidate mechanism of these miRNAs and their related proteins.