Human C-reactive protein exacerbates metabolic disorders in association with adipose tissue remodelling

Aims C-reactive protein (CRP) expression is increased with metabolic alterations. We sought to clarify the effect of CRP on the development of obesity-induced metabolic disorders using human CRP-overexpressing transgenic mice (CRPTG). Methods and results CRPTG and their non-transgenic littermates (CON) were fed a standard diet (STD) or a high-fat diet (HFD) from 6 weeks of age. Oral glucose tolerance and intraperitoneal insulin tolerance tests 12 weeks after starting the diets showed deterioration of glucose tolerance and insulin sensitivity in HFD/CRPTG compared with HFD/CON. Hepatocellular ballooning, oil droplets, and peri-sinusoidal fibrosis were more prominent in HFD/CRPTG than in HFD/CON. In HFD/CRPTG, hepatic triglyceride content was higher and serum adiponectin levels lower than in HFD/CON. Epididymal adipose tissue mRNA expression of mucin-like, hormone receptor-like 1, monocyte chemotactic protein-1, and tumour necrosis factor-α in HFD/CRPTG was up-regulated compared with that in HFD/CON. Immunohistochemical staining of epididymal adipose tissue showed that the number of Mac-3 macrophages was higher in HFD/CRPTG than in HFD/CON. Conclusion Human CRP overexpression facilitated the development of insulin resistance and hepatosteatosis with HFD in association with adiponectin down-regulation and enhancement of macrophage infiltration and expression of pro-inflammatory cytokines in epididymal adipose tissue, suggesting its pathogenic role in the development of obesity-induced metabolic disorders.