Abstract
Obesity leads to an altered adipocytokine production negatively effecting the function of natural killer cells (NK cells), which are important effector cells of the innate immune system. NK cells provide a defence against tumour cells or virus infected cells and have different activating and inhibitory surface receptors to distinguish between normal and transformed cells. One group of the inhibitory receptors are the sialic acid-binding immunoglobulin-like lectins (Siglecs). The aim of this study was to compare the expression of Siglecs-7, -9 and -10 on NK cells from normal weight and obese subjects. Therefore peripheral blood mononuclear cells (PBMC) were isolated from 10 normal weight (BMI < 25 kg/m2) and 11 obese (BMI > 30 kg/m2) blood donors and analysed by flow cytometry. Moreover, the amount of sialic acid on NK cell was determined using a fluorescent labelled lectin that binds terminal sialic acids. Percentages of immune cells were not altered between normal weight and obese individuals. CD56bright NK cells from obese subjects had a reduced expression of Siglec-7 while the expression of Siglec-9 was not altered. The reduction of Siglec-7 expression on CD56bright NK cells might be a marker for their dysfunction. Moreover, Siglecs-7, -9 and -10 are not expressed on the NK cell lines NK-92 and NKL. When comparing the two NK cell subpopulations CD56bright and CD56dim, CD56bright NK cells had a higher amount of sialic acids on their surface compared to CD56dim NK cells regardless of body weight.
Highlights
Obesity is one of the major health problems in high- and middle-income countries and has become a global epidemic during the last decades
The study population was composed of 21 subjects, which were divided into a normal weight group (BMI 18 kg/m2– 25 kg/m2) and an obese group (BMI > 30 kg/m2)
It has been shown previously that the NK cell function and phenotype are altered in obesity
Summary
Obesity is one of the major health problems in high- and middle-income countries and has become a global epidemic during the last decades. Obesity increases the risk of cardiovascular diseases and type II diabetes. It is a major risk factor for several types of cancer, including liver, kidney or colon cancer [2]. Increased body weight is associated with a higher risk of postoperative wound infections [3] and a higher risk of infections in general [4]. All this indicates that obesity negatively acts on the immune system
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