1690-P: Adipose Tissue Dectin-1 Upregulation in Hyperglycemic Obesity Involves TNF-α/NF-kB Mediated Signaling Free

Dectin-1 is a pathogen recognition receptor as well as an innate immune response modulator; its function in metabolic disorders is yet unclear. Previously, we identified dectin-1 as a biomarker of metabolic inflammation in obesity. In this study, we sought to identify potential signaling pathways that could modify the expression of the dectin-1 gene and assess the expression of dectin-1 in the adipose tissue (AT) of obese patients based on their diabetic status. The study cohort included 95 obese individuals split into two groups: prediabetics with moderate glycemia (Hb1Ac 6.5%, n = 49) and diabetics with hyperglycemia (Hb1Ac 6.5%, n = 46). Dectin-1 expression was assessed using immunohistochemistry. Gene expression and inflammatory markers were determined via qRT-PCR. We found a significant positive correlation between dectin-1 expression and HbA1C levels in AT isolated from obese individuals with HbA1C levels of 6.5% or higher. Dectin-1 gene expression was significantly correlated with several inflammatory markers; however, glycemic-dependent associations were also observed. Dectin-1 and TNF-α were found to be significantly correlated in AT from individuals with Hb1Ac 6.5%, indicating a possible mechanism of gene regulation between these two factors. As a result, we investigated the observed dectin-1/TNF-α crosstalk using in vitro cell culture and animal studies. Unlike wild-type animals, mice lacking TNF-α exhibited reduced levels of dectin-1 gene and protein expression in their AT, which were restored by injecting exogenous TNF-α. ChIP studies showed that TNF-α induced dectin-1 gene transcription by mediating NF-kB binding to newly identified regulatory elements located in the dectin-1 proximal regulatory region. The interplay between dectin-1 and TNF-α signaling pathways is intriguing and has the potential to be a therapeutic target in obesity and diabetes. Furthermore, dectin-1 could be a potential marker for the onset of hyperglycemia and diabetes.