Complement Properdin Regulates the Metabolo-Inflammatory Response to a High Fat Diet

Area of Science:

• Immunology
• Metabolic disease
• Renal pathology

Background:

• Overnutrition triggers complement activation, with properdin amplifying this response.
• Properdin deficiency exacerbates obesity in mice on high-fat diets.
• Understanding properdin's role is crucial for metabolic disease research.

Purpose of the Study:

• To investigate how properdin influences the obese phenotype.
• To elucidate the mechanisms by which properdin impacts metabolic and inflammatory responses in obesity.

Main Methods:

• Comparison of wild-type (WT) and properdin-deficient (KO) mice fed a high-fat diet (HFD) for 12 weeks.
• Analysis of liver triglyceride content, steatosis, steatohepatitis, and AKT signaling.
• Assessment of C5L2 and CD36 expression in adipose tissue, plasma, and microparticles.
• Evaluation of renal ultrastructural changes.

Main Results:

• Properdin deficiency led to increased liver triglycerides and steatohepatitis compared to WT mice.
• Insulin sensitivity was reduced in KO mice in the liver and kidney.
• Decreased C5L2 and increased CD36 expression were observed in KO mice, particularly on microparticles and in adipose tissue.
• Both genotypes showed obesity-associated glomerulopathy, but KO mice exhibited greater tubular strain.

Conclusions:

• Complement properdin significantly limits the severity of obesity-associated liver and kidney conditions.
• C5L2 and CD36 act as downstream mediators of properdin's protective effects.
• Properdin plays a critical role in modulating the inflammatory and metabolic consequences of obesity.