Up-Regulation of Mir-21 and Mir-130a and Serum Leptin Levels on Leg Ulcers Development in Sickle Cell Anemia

Abstract

Introduction: Leg ulcers (LUs) are a cutaneous complication of sickle cell anemia (SCA), whose etiology is considered multifactorial. In the search for new candidates for modulators of SCA clinical events, recent evidence suggests the significant role of mechanisms related to post-transcriptional regulation, especially microRNAs (miRNAs). Thus, the analysis of miRNAs miR-21 and miR-130a differential expression in patients with SCA becomes an interesting approach, since both act in the regulation of several biological mechanisms related to the pathophysiology of LU, especially the tissue repair process. In addition, these miRNAs have already been related to the regulation of serum leptin levels, a strong angiogenic pleiotropic hormone that acts in the healing process of skin lesions. Therefore, the aim of the study was to investigate the influence of miR-21 and miR-130a and serum leptin levels on the development of LUs in SCA patients. Methods: After analyzing medical records, 60 SCA patients were selected. Patients who presented some of the main clinical manifestations that may have etiology due to the underlying disease (for example: osteonecrosis, stroke, priapism and acute chest syndrome) were not included. Patients with a history of LU were considered cases, and those who did not develop this complication (n=20), were considered control (median age: 26 years, range: 19-61, 50% males). The control group was called "HbSS-Control" and the case group was divided into two subgroups: Active leg ulcer group, composed of 19 patients with active LU at the time of blood collection (median age: 35 years, range: 24-56, 68% males), and healed leg ulcer group, composed of 21 patients with healed LU at the time of blood collection (median age: 34 years, range: 22-52, 43% males). In addition, it was analyzed a group of 10 donors with normal hemoglobin profile (median age: 25 years, range: 20-30, 50% males), identified as "HbAA-Control". Expression levels of miRNAs extracted from peripheral blood, using mirVanaTM PARIS Kit (Invitrogen™) were evaluated by RT-qPCR technique utilizing TaqMan® probes. Serum leptin levels of the patients were evaluated employing the ELISA method (Human Leptin ELISA Kit, Millipore®). Mann-Whitney and Kruskal-Wallis tests were applied to compare continuous variables. Results: Up-regulation of both miRNAs was observed in the active leg ulcer group in contrast to the healed leg ulcer (miR-21: P<0.0001, Figure 1A, Fold change [FC]=14,2; miR-130a: P=0.0004, FC=18,8, Figure 1B) and Control-HbSS groups (miR-21: P<0.0001, FC=34,4, Figure 1A; miR-130a: P=0.0006, FC=15,3, Figure 1B) and the HbAA-Control group (miR-21: P<0.0001, FC=5,8, Figure 1C; miR-130a: P=0.0009, FC=10,9, Figure 1D). However, there was no significant difference between the healed leg ulcer, HbSS-Control and HbAA-Control groups (miR-21: P=0.1829, Figure 1E; miR-130a: P=0.3537; Figure 1F). Furthermore, the active leg ulcer group had lower serum leptin levels when compared to the healed leg ulcer and Control-HbSS groups (P=0.0058; Figure 2A). The levels of leptin in the healed leg ulcer group did not differ from the Control-HbSS group (P=0.5929; Figure 2B). Conclusion: Our results demonstrated an inverse relation between the miRNAs miR-21 and miR-130a expression with serum leptin levels, suggesting that the up-regulation of these miRNAS may be related to the chronicity and healing of LUs in individuals with SCA through decreased of serum leptin levels. Disclosures No relevant conflicts of interest to declare.