IL10 (-1082 G>A, rs1800896) gene polymorphisms are associated with oxidative stress in sickle cell disease patients in Uganda.

Background: Sickle cell disease (SCD) is characterised by chronic oxidative stress. However, there is limited information on how polymorphisms in cytokine genes influence oxidative stress in SCD patients. The study aimed to determine the effect of Interleukin gene (IL-10) and Tumor Necrosis Factor (TNF_αβ) polymorphisms on oxidative stress and cytokine levels in SCD patients from Mulago hospital.

Methods: A case control study with cross-sectional sample size of 163 SCD patients and 189 healthy controls was carried out. The extent of oxidative stress was quantified using Malondialdehyde (MDA) by spectrophotometry. Levels of IL-10 and TNF-α were measured using the Enzyme-Linked Immuno-Sorbent Assay (ELISA). The Amplification Refractory Mutation System polymerase chain reaction (ARMS-PCR) assay was used to genotype IL10-1082 A > G, (rs1800896), IL10-819 C > T (rs1800871) and TNF-α-308G > A (rs1800629) and TNF-β + 252 A > G (rs909253) gene polymorphisms.

Results: Samples showed significantly (P = 0.0063) higher median plasma levels of MDA in SCD patients (2.756µM) than healthy controls (2.364µM). A similar trend was observed with significantly (P < 0.0001) higher median plasma levels of IL-10 in SCD patients (20.37pg/ml) than healthy controls (7.5pg/ml). The most frequent genotype for IL-10 (-1082, rs1800896) gene polymorphism was heterozygous GA (62.6%). No significant association between IL10 (-1082G > A, rs1800896) gene polymorphisms and SCD was observed (OR = 1.08, 95% CI = 0.54-2.14, P = 0.87). Yet, IL10 homozygous GG (-1082, rs1800896) (22.12pg/ml) that was found to be significantly associated (P = 0.0234) with increased plasma levels of IL-10 as compared to heterozygous genotype (GA) (13.94pg/ml) in SCD patients. Similarly, higher levels of MDA were found to be significantly (P < 0.0001) associated with homozygous GG at IL-10 (-1082, rs1800896). The most frequent and only reported genotype for TNF-α/β gene polymorphisms were heterozygous GA, thus no associations were described.

Conclusion: In conclusion, our results suggest that the IL10 (-1082 G > A, rs1800896) gene polymorphism is associated with increased oxidative stress and IL-10 cytokine level in Ugandan SCD patients.