Interleukin-10 promoter polymorphisms and haplotypes in patients with Guillain-Barré syndrome

Interleukin-10 (IL-10) is a multifunctional cytokine that exerts both pro- and anti-inflammatory effects on the immune system as well as in the pathogenesis of Guillain-Barré syndrome (GBS). We investigated whether the three common polymorphisms -1082 G/A(rs1800896), -819 C/T(rs1800871), and -592 C/A(rs1800872) in the promoter region of IL-10 have any influence on the susceptibility, severity, and clinical outcome of GBS.

IL-10 promoter polymorphisms were investigated in 152 patients with GBS and 152 healthy controls from Bangladesh using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP), and allele-specific oligonucleotide-PCR (ASO-PCR). Haplotype patterns and frequencies were analyzed using Heatmaply R-package, chi-square, and Fisher's exact test. The serum level of IL-10 was measured through enzyme-linked immunosorbent assays. p-values < 0.05 were considered statistically significant.

IL-10 promoter polymorphisms -1082 G/A, -819 C/T, and -592 C/A were not associated with GBS susceptibility. The homozygous -819 TT genotype showed a tendency with susceptibility (p = 0.029; pc = 0.08) and was prevalent in axonal variants of GBS compared to demyelinating subtypes and controls (p = 0.042, OR = 8.67, 95% CI = 1.03-72.97; pc = 0.123 and p = 0.005, OR = 4.2, 95% CI = 1.55-11.40; pc = 0.015, respectively). Haplotype analysis revealed 19 patterns of genotypes and high IL-10 expression haplotype combinations (GCC/GTA, GCC/ATA, and GCC/GCA) may have influence on disease severity (p = 0.026; pc = 0.078). Serum expression of IL-10 was elevated in GBS patients ([GBS, 12.16 ± 45.71] vs. [HC, 0.65 ± 5.17] pg/mL; p = 0.0027) and varied with disease severity ([severe-GBS, 15.25 ± 51.72] vs. [mild-GBS, 3.59 ± 19.79] pg/mL, p = 0.046).

The -819 TT genotypes influence axonal GBS, and high frequency of IL-10 expression haplotype combination with elevated serum IL-10 may play an important role in disease severity.