The association between galactosylation of immunoglobulin G and body mass index

Obesity is becoming a fast-growing health problem worldwide. Glycosylation of proteins and their variations significantly affect protein structure and function, thus altering numerous physiological and pathophysiological cellular processes. Since plasma glycans were significantly associated with body mass index (BMI) in both Croatian and Chinese populations, the study evaluated the association between immunoglobulin G (IgG) glycome, which is closer to biological function, and BMI. The study included individuals from two Croatian Adriatic islands, Vis and Korčula, and individuals from Northern Scottish Orkney Islands. A hydrophilic interaction chromatography on Waters BEH Glycan chromatography column was used to analyze N-glycans attached to IgG in plasma samples from a total of 3515 individuals. A small but significant positive correlation between BMI and the level of neutral glycans without galactoses was detected. After taking into account the influence of age and gender, correlation coefficients indicated that BMI was responsible for up to 2.0% of variation in the level of neutral glycans without galactoses. Furthermore, after adjusting the effects of age and gender, the level of neutral glycans with two terminal galactoses was negatively associated with BMI in analyzed sample groups, suggesting that BMI could be responsible for up to 3.2% of variation in this glycan feature. Our study is the first large-scale study to indicate the association of BMI and changes in IgG galactosylation. The observed loss of galactose which is associated with increased BMI might be related to chronic inflammation that accompanies the development of obesity