Franny Jongbloed

146 CHAPTER 6 ABSTRACT Morbid obesity adversely affects health and is associated with subclinical systemic inflammation and features of accelerated aging, including the T-cell immune system. The presence of metabolic syndrome (MetS) may potentiate these phenomena. Bariatric surgery might delay or reverse accelerated aging in morbidly obese patients. To examine the effects of bariatric surgery on accelerated immune aging, we measured telomere length and phenotypic characteristics of circulating T-cells in morbidly obese patients before and after bariatric surgery. Ten healthy controls (HC) and 108 morbidly obese patients scheduled for bariatric surgery were included: 41 without MetS and 67 with MetS. Relative telomere length (RTL) and differentiation status were measured in circulating CD4 + and CD8 + T-cells via flowcytometry. T-cell characteristics were compared for age, MetS, cytomegalovirus (CMV)-serostatus and gender prior to, and at three, six and 12 months after bariatric surgery. Data were compared with those of age-matched HC. Thymic output, represented by numbers of CD31-expressing naive T-cells, was significantly higher in patients ≤50 years of age without MetS. MetS, CMV-seropositivity, older age and male gender significantly enhanced T-cell differentiation. Patients with MetS had significant lower CD4 + RTL than patients without MetS and HC, which was most pronounced in patients ≤50 years of age and CMV-seropositive. Within the first year after bariatric surgery, telomere attrition was increased in CD4 + T-cells. Interestingly, T-cells were less differentiated following bariatric surgery, which was most pronounced in the MetS group. Especially in morbidly obese patients ≤50 years of age, MetS significantly decreased the RTL of CD4 + and enhanced T-cell differentiation. This was only partially reversed following bariatric surgery. These data suggest that obese patients with MetS are at risk for accelerated aging of the T-cell immune system and might benefit from bariatric surgery at an earlier stage. Cytomegalovirus (