Clusterin is closely associated with adipose tissue insulin resistance

Aims: Clusterin (encoded by CLU) is a novel adipokine. Serum clusterin levels were elevated in populations with obesity and diabetes. Adipose tissue insulin resistance (Adipo-IR) is proposed as an early metabolic defect that precedes systemic insulin resistance. Herein, we aimed to investigate the relationship between serum clusterin levels and Adipo-IR. CLU expression in human abdominal adipose tissues and clusterin secretion in human adipocytes was also explored. Materials and Methods: A total of 201 participants (aged 18-62 years, 139 of whom were obese) were recruited. Enzyme-linked immunosorbent assay was used to measure serum clusterin levels. Adipo-IR was calculated from the product of fasting free fatty acids and fasting insulin levels. Transcriptome sequencing of abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) was performed. Human adipocytes were used to detect the secretion of clusterin. Results: Serum clusterin levels were independently associated with Adipo-IR after adjusting for several confounding factors (standardised ss = 0.165, p = 0.021). CLU expression in VAT and SAT was associated with obesity-related metabolic risk factors. Higher CLU expression in VAT was accompanied by an increase in collagen accumulation. Clusterin secretion in differentiated human adipocytes was stimulated by insulin and inhibited by rosiglitazone. Conclusions: Clusterin is strongly associated with Adipo-IR. Serum clusterin may function as an effective indicator of adipose tissue insulin resistance.