My research is focused on understanding how diet-induced obesity activate adipose tissue macrophage (ATMs) leading to inflammation and metabolic disease. To study the mechanisms underlying this phenomenon, I investigate the role of the enzyme Cholesterol 25-Hydroxylase (CH25H) and its produced oxysterol, 25-Hydroxysterol, in ATMs with obesity and diabetes. To study how this oxysterol deregulation is linked to ATMs activation and inflammation, I utilize Ch25h knockout mice and wild-type controls fed a normal and a high-fat diet and characterize their metabolic and inflammatory responses in adipose tissue and on macrophage biology. Given that inflammatory ATMs of obese diabetic subjects overexpresses CH25H, I also explore how immune cell function is modulated in metabolic disease using human AT biopsies from obese subjects with and without diabetes.