This study aimed to evaluate the effect of HU therapy on the expression of inflammatory cytokines, in addition to molecularly characterizing the promoter regions of the cytokines IL-1β, IL-6, IL-10, IL-18 and TNF-α in patients with sickle cell anemia (SCA).

In the study were included SCA patients in use and without HU treatment during outpatient care performed periodically at HEMOAM and a healthy control group of blood donors. All participants underwent venipuncture to collect 5mL of peripheral blood in a tube containing EDTA anticoagulant. The cytokines of both groups were measured using the Luminex KIT (The Bioplex-Pro Human Cytokine 27-Plex Kit from Bio-Rad); DNA extraction by the QIAamp DNA Mini Kit (Qiagen); Genetic sequencing was performed using the SANGER method by Applied Biosystems™3500 Automatic Sequencer. Statistical analyses were performed using the SPSS vs21 and Prism vs9 programs, with p-values < 0.05 considered significant.

A total of 214 SCA patients and 240 healthy controls (AA) participated in the study. Females were predominant in patients (62.15%), while males were predominant in controls (74.17%). Brown race was predominant in both SS (69.16%) and AA (72.5%) groups. The mean age of patients was 16.23 ± 8.51 years, while the mean age of donors was 32.2 ± 13. Plasma concentrations of all cytokines were significantly higher in patients than in controls (p < 0.001). The most frequent SNPs found in both cases and controls were IL-1β c.-31 C>T; IL-1β c.-511 T>C; IL-6 c.-174 G>C; IL-6 c.-572 G>C; IL-8 c.-251 A>T; IL-10 c.-592 C>A; IL-10 c.-819 C>T; IL-18 c.-137 C>G; IL-18 c.-607 C>A; TNF-a c.-308 G>A. The SNP IL-1β c.-31C was significantly more prevalent in SCA patients (p = 0.030 - OR: 1.96 - CI: 1.10-3.48), while IL-8 c.-251AA (p = 0.020 - OR: 0.45 - CI: 0.23-0.89) and IL-18C c.-607CC (p = 0.034 - OR: 0.52 - CI: 0.28-.95) were significantly more prevalent in healthy donors. A significant association between HU treatment was found only of c.-251AA - IL-8 genotype (p = 0.004 - OR: 0.22 - CI: 0.07-0.66), being more prevalent in those without HU use, presenting itself as a protective factor.

Our results showed that females were more prevalent in patients with AF, corroborating regional studies and studies from other Brazilian states. As expected, males were more prevalent among blood donors, corroborating several national studies. The higher plasma concentrations of all cytokines in patients is clearly due to the constant inflammatory state that these patients have.

Although all SNPs found in our study have been demonstrated in other studies carried out with SCA patients, we were able to demonstrate for the first time the genotype (IL-8 (c.-251AA) as a possible important modulator for the prevalence of complications in SCA patients. We understand that molecular analyses of inflammatory genes may be a strategy for better understanding the heterogeneity found in patients with and their use of Hydroxyurea.