Polymorphism of the IL6 Gene Associated with Plasma IL6 and Physical Activity Levels

Monday, July 11, 2011

Leah FitzGerald, PhD, FNP
School of Nursing, UCLA, Los Angeles, CA

Learning Objective 1: The learner will understand the possible role of exercise-induced reduction in the pro inflammatory burden in healthy males

Learning Objective 2: The learner will describe how IL6 values can be influenced by allelic and genotypic frequencies and physical activity.

Purpose:

The aim of this study was to compare allelic and genotypic frequencies of the Interleukin-6 (IL6) -174 G>C and -572 G>C polymorphism and baseline plasma IL6 values between endurance athletes and healthy controls.  We hypothesized that IL6 would be influenced by allelic and genotypic frequencies and physical activity. IL6 plays a role in metabolism regulation during exercise and in mediating inflammation. Alternatively, enhanced plasma levels of IL6 represent a strong risk marker in chronic disorders. Genetic polymorphisms in IL6 gene promoter -174/-572 positions affect IL6 expression, human exercise performance, and health-related phenotype.    

Methods: Cross-sectional assessment on 61 serious endurance athletes and 90 healthy controls (aged 18 – 65 years old), included anthropometric measurements, DNA isolation and IL6 measurement.

Results: Allele distribution was in Hardy-Weinberg’s equilibrium. There were significant overall group differences in IL6 levels (p <0.01) and athletes with -572 G>C allele had significantly lower logIL6 values (p=0.0) compared to controls.  Linear regression with logIL6 as the dependent variable and age, BMI, gender, and SNP’s -174 and -572 as covariates and group as a fixed factor supports  age, (p = 0.04) BMI (p = 0.02), SNP -572 (p = 0.02), group (p < 0.01),  (-)572*gr interaction (p= 0.03) significant in predicting logIL6.

Conclusion:

Higher levels of physical activity are associated with reduced levels of peripheral inflammatory mediators compared with a sedentary lifestyle.  Our findings suggest that the -572C allele may effect baseline plasma IL6 levels in athlete as well as age, BMI and activity level, suggesting there may be a genetically determined difference in the degree of the IL6 response to exercise stimuli between individuals.  An exercise-induced reduction in the proinflammatory burden may explain a part of the relation among regular physical activity and prevention in chronic disorders associated with systemic low-level inflammation.