Increased expression of triggering receptor expressed on myeloid cells-1 in the population with obesity and insulin resistance.

Abstract

Triggering receptor expressed on myeloid cells (TREM)-1 has recently been recognized as one of the potent amplifiers of acute and chronic inflammation. However, the exact role of TREM-1 in regard to insulin insensitivity is unknown. mRNA transcripts and protein expression of TREM-1, TREM-2, and TREM-1/TREM-2 ratio were examined in the tissue biopsies (liver, omentum, and subcutaneous fat) and blood samples (neutrophils and monocytes) of subjects with obesity and diabetes (SO⁺ D⁺ ; n = 15), subjects with obesity but not diabetes (SO⁺ D^- ; n = 7), and subjects without obesity (BMI < 30) and diabetes (SO^- D^- ; n = 5). The immunofluorescence and RT-PCR revealed significant increase in TREM-1, decrease in TREM-2, and increase in the TREM1/TREM2 ratio in SO⁺ D⁺ group compared with other groups. Overall, increased liver TREM-1 expression and soluble-TREM-1 were found in SO⁺ D⁺ group compared with SO⁺ D^- group (100% vs. 57.14%, r = 0.582; P = 0.023). TREM-1 was significantly increased in all subjects with obesity and those with HOMA-IR index of >2. TREM-1 was found to be significantly higher in tissues biopsies and blood of subjects with obesity. Greater expression and activity of TREM-1 suggest a possible role in the underlying pathophysiology of obesity and associated comorbidities.