Omentin

Omentin, also known as intelectin-1, is a secreted protein classified as an adipokine, meaning it is produced by adipose tissue. It exists in at least two isoforms, omentin-1 and omentin-2, with omentin-1 being the predominant circulating form in humans. The ITLN1 gene encodes omentin-1, while ITLN2 encodes omentin-2. Omentin is primarily expressed by visceral (omental) adipose tissue, though detectable levels are found in the circulation.

Omentin is thought to play a role in metabolic regulation and inflammation. In cellular models, omentin-1 enhances insulin-stimulated glucose uptake and signaling in adipocytes, suggesting a positive influence on insulin sensitivity. It is also associated with anti-inflammatory effects, including modulation of cytokine production, and may contribute to endothelial function, potentially promoting nitric oxide availability. However, the exact receptors and signaling pathways for omentin are not fully defined, and much of the mechanistic detail remains to be clarified.

Serum omentin levels are inversely related to adiposity in many studies; concentrations are typically lower in obesity and type 2 diabetes and tend to rise with weight loss or increased physical activity. Because of these associations, omentin has been investigated as a potential biomarker for metabolic health and cardiovascular risk, though findings across studies are not entirely consistent.

In summary, omentin is a visceral adipose–derived adipokine implicated in insulin sensitivity and anti-inflammatory processes, with circulating levels reflecting metabolic status and body composition. Further research is ongoing to delineate its receptors, signaling mechanisms, and clinical utility.