Non-classical circulating monocytes in severe obesity and obesity with uncontrolled diabetes: A comparison with tuberculosis and healthy individuals

Abstract

Severe obesity and diabetes lead to a significant decrease in quality of life. Although controversial, population-wide studies have implicated obesity in the development of tuberculosis (TB). Non-classical monocytes have been described in obesity and TB, whereas in diabetes they have been associated with poorer clinical outcomes. The present study focuses on the functional significance of several monocyte populations of obese, obesity-related diabetic (OBDM), non-obese/diabetic tuberculosis and non-obese healthy control patients. Monocytes were evaluated by measuring expression of CD86, CD206, TLR-2 and TLR-4 as well as production of IL-6, IL-12, and by using a mycobacterial growth inhibition assay for both Mycobacterium tuberculosis and M. abscessus subsp. massiliense. Non-classical monocytes from OBDM and non-obese TB patients exhibited similar activation profiles (CD86/CD206/TLR-2 and TLR-4 expressions). Only monocytes from TB patients had a higher positivity for IL-12 and IL-6, whereas adiponectin serum levels increased similarly between TB and OBDM patients. Monocytes from active TB patients and OBDM were more permissive to Mtb growth than obese individuals, but this susceptibility was not observed for M. abscessus subsp. massiliense. From these findings, we conclude that diabetes and tuberculosis had similarities in the population of circulating non-classical monocytes, improving our understanding of the association of these diseases.