Abstract
Background and Objectives
. Malaria infection, caused by
Plasmodium falciparum
, is the most lethal and frequently culminates in severe clinical complications. Interleukin-22 (IL-22) has been implicated in several diseases including malaria. The objective of this study was to investigate the role of IL-22 gene polymorphisms in
P
.
falciparum
infection.
Material and Methods
. Ten single-nucleotide polymorphisms (SNPs), rs976748, rs1179246, rs2046068, rs1182844, rs2227508, rs2227513, rs2227478, rs2227481, rs2227491, and rs2227483, of
IL-22
gene were genotyped through PCR-based assays of 250
P
.
falciparum
-infected patients and 200 healthy controls. In addition, a luciferase reporter assay was done to assess the role of the rs2227513 SNP in
IL
-
22
gene promoter activity.
Results
. We found that the rs2227481 TT genotype (odds ratio 0.254, confidence interval = 0.097-0.663,
P
=
0.002
) and the T allele is associated with protection against
P
.
falciparum
malaria as well as the rs2227483 AT genotype (odds ratio 0.375, confidence interval = 0.187-0.754,
P
=
0.004
). The haplotype A-T-T of rs1179246, rs1182844, and rs976748 was statistically more frequent in the control group (frequency 41%,
P
=
0.034
) as well as the haplotype A-G of rs2046068 and rs2227491 (frequency 49.4%,
P
=
0.041
). The variant rs2227513 G allele had a statistically higher activity (
P
<
0.0001
) with the luciferase reporter assay.
Conclusion
. The study suggests that IL-22 polymorphisms in rs2227481 and rs2227483 could contribute to protection against
P
.
falciparum
malaria. Also, the G allele of rs2227513, located in the promoter region of
IL
-
22
gene, could be essential for higher expression levels of IL-22 cytokine.