resistin

Resistin is a secreted protein that functions as an adipokine involved in metabolic and inflammatory processes. In rodents, resistin is produced mainly by adipocytes and linked to insulin resistance and obesity. In humans, resistin is expressed predominantly by inflammatory cells such as macrophages, and its connection to insulin resistance is less clear. The name resistin derives from its originally proposed role in opposing insulin action, but the exact physiological relevance across species remains a topic of study.

Genetics and expression: In humans, the RETN gene encodes resistin. Expression patterns differ from those in mice, with adipose-tissue production being relatively low in humans and immune cells contributing more significantly to circulating resistin levels. Resistin-like molecules (RETNLB and related family members) exist, but their relationships to classical resistin biology are distinct.

Biological role: Resistin is associated with regulation of glucose metabolism and inflammatory responses. Experimental models show that resistin can impair insulin signaling and promote hepatic glucose production, while also stimulating the production of inflammatory mediators such as interleukin-6 and tumor necrosis factor-alpha. The precise receptors and signaling pathways mediating resistin’s actions are not fully defined, though inflammatory signaling cascades such as NF-κB are frequently observed in resistin-related studies. The overall contribution of resistin to insulin resistance and metabolic dysfunction in humans remains an area of active investigation.

Clinical relevance: Elevated resistin levels have been reported in obesity and inflammatory conditions, but associations with insulin resistance and type 2 diabetes are variable across studies. As such, resistin is considered a potential biomarker and research target rather than a proven therapeutic factor. Ongoing work aims to clarify species differences, mechanisms of action, and its utility in metabolic disease risk assessment.