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.


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.


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.