Influence of Vitamin D Status and IL-10 Gene Promoter Polymorphism (rs1800871) on Plasma IL-10 Levels in Apparently Healthy Individuals from Southern India: A Cross-sectional Study

Introduction: Interleukin-10 (IL-10) is a major anti-inflammatory cytokine, which plays an important role in regulating inflammatory responses of the immune system. Changes in IL-10 level and its function can cause an imbalance in immune response, which can be associated with various disease conditions.

Aim: To study the influence of vitamin D status and IL-10 gene promoter polymorphism (rs1800871) on circulating IL-10 cytokine levels in apparently healthy South Indian population.

Materials and Methods: A cross-sectional study was conducted at the Department of Clinical Pharmacology, JIPMER, Puducherry, India from January 2016 to December 2017. Apparently healthy South Indian volunteers (N=101) of either sex, age more than 18 years, were recruited for the study, after obtaining written informed consent. Serum 25-hydroxy vitamin D and plasma IL-10 levels were measured by using Chemiluminescence and Enzyme Linked Immunosorbent Assay (ELISA), respectively. IL-10 rs1800871 genotyping was performed by Real Time-polymerase Chain Reaction (RT-PCR). Values were expressed as median, Inter-quartile Range (IQR) and proportions were described as number with percentage.

Results: The median serum vitamin D and plasma IL-10 levels observed among the study population were 18.21 ng/mL IQR, 11.3-23.08 ng/mL) and 9.04pg/mL (IQR, 7.75, 11.34 pg/mL) respectively. The genotype and allele frequencies of rs1800871 were consistent with that of the African, South Asian population of 1000 genome project. Plasma IL-10 levels were not significantly different across genotypes (p-value=0.091), even though the median level among homozygous mutant (TT) volunteers was observed to be less (8.35 pg/mL vs 9.69 pg/mL, 9.83 pg/mL). The correlation between vitamin D and IL-10 levels was observed to be insignificant (p-value=0.143).

Conclusion: The present study has reported the rs1800871 genotype frequency, circulating serum vitamin D levels and plasma IL-10 levels in the apparently healthy South Indian population. IL-10 cytokine levels were not significant across the different genotype and vitamin D status groups. No significant correlation was observed between the IL-10 and vitamin D levels among the sample studied.