Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Bariatric surgery and subsequent weight loss lead to a reversal of peripheral blood monocytosis in obesity.

Abstract

OBJECTIVE: To examine changes in monocyte subpopulations and surface markers in people with obesity before and after bariatric surgery, and their relation to weight loss, inflammation markers, and comorbidities. METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from patients with obesity designated for bariatric surgery at three different time points: before surgery (=baseline), six months and twelve months after the intervention. PBMCs were analyzed using flow cytometry to distinguish the different monocytic subpopulations. At each visit, anthropometric measures and routine laboratory parameters (e.g., C-reactive protein) have been determined. RESULTS: 111 individuals with obesity (59.5% female, mean age 45.2+-11.3 years) with a median body mass index (BMI) of 48.4 kg/m2 were included into this study. Median weight loss was 44.5 kg. The absolute monocyte count decreased significantly after surgery within twelve months (p = 0.0035). Classical monocytes, non-classical monocytes, intermediate monocytes, and monocytic myeloid-derived suppressor cells (M-MDSC) decreased significantly after the surgical intervention within six to twelve months. CD14bright/CD56+ monocytes did not change significantly during twelve months of observation. Surface expression of CD14 increased in both classical and intermediate monocytes (p = 0.0272 and 0.0087, respectively) within 6 months whereas CD16 declined across all monocyte subpopulations at every time point. The total monocyte counts as well as numbers of non-classical monocytes were significantly higher in patients with obesity and type 2 diabetes mellitus. COVID-19 containment measures resulted in a longitudinal reduction in the number of patient evaluations. CONCLUSIONS: Following bariatric surgery and the resulting weight loss, the obesity-associated perturbation of the monocyte compartment was largely reversed. Normalization of both the total monocyte pool and of monocyte subpopulations, particularly those with pro-inflammatory properties such as intermediate monocytes, could contribute to a risk reduction of known co-morbidities of obesity such as chronic inflammation, impaired glucose regulation, and an increased risk of cancer.