A new effector of lipid metabolism: complement factor properdin.

Area of Science:

• Immunology
• Metabolic Research
• Adipose Tissue Biology

Background:

• The complement system, crucial for innate immunity, is increasingly recognized for its roles in adipose tissue.
• Properdin, a complement activator, stabilizes C3 convertase and is found on adipocyte membranes.

Purpose of the Study:

• To investigate the role of properdin in energy metabolism.
• To utilize properdin-deficient (PKO) mice and cell-based assays for this evaluation.

Main Methods:

• Comparison of PKO mice with wild-type (WT) littermates on high-fat diets.
• Assessment of weight gain, body fat mass, energy expenditure, and postprandial lipid clearance.
• In vitro studies using 3T3-L1 adipocytes and L6 rat skeletal muscle cells to examine properdin's effects on glucose and lipid metabolism.

Main Results:

• PKO mice exhibited diet-dependent weight gain and increased fat mass on a high-fat diet.
• Decreased energy expenditure and altered lipid clearance were observed in PKO mice.
• Properdin inhibited insulin-mediated fatty acid uptake in adipocytes but did not affect glucose transport.

Conclusions:

• Properdin influences lipid metabolism and energy storage in adipose tissue.
• This finding supports a dual role for complement proteins in regulating adipose tissue function and potentially insulin resistance.