Differential transendothelial transport of adiponectin complexes

Area of Science:

• Endocrinology
• Molecular Biology
• Physiology

Background:

• Adiponectin is an insulin-sensitizing and anti-inflammatory adipokine with known systemic effects.
• The transport mechanisms of adiponectin to its target cells are not well understood.
• Adiponectin exists in various oligomeric forms with high molecular weights, posing transport challenges.

Purpose of the Study:

• To investigate the mechanisms of adiponectin transport across endothelial barriers.
• To determine how adiponectin oligomer size and endothelial permeability influence its tissue distribution.
• To explore the impact of interventions like exercise and pharmacological treatments on adiponectin transport and efficacy.

Main Methods:

• Recombinant murine adiponectin was produced and fractionated into oligomers.
• Dynamic light scattering was used to measure adiponectin complex sizes (Stokes radii).
• Transendothelial transport of adiponectin oligomers was assessed in vitro using endothelial cells and in vivo in mouse models.

Main Results:

• Adiponectin oligomers have large transport radii, limiting their passage across endothelial barriers.
• Lower molecular weight adiponectin fractions were preferentially transported across endothelial monolayers.
• In vivo studies showed differential distribution of adiponectin oligomers in various organs (heart, liver, tail vein).
• Pharmacological interventions (e.g., PPARγ agonists) and exercise differentially affected adiponectin clearance and tissue uptake.
• Exercise increased adiponectin uptake in oxidative skeletal muscles, leading to reduced ceramide levels.
• Endothelial barriers were found to control adiponectin transport in a cell- and tissue-specific manner.

Conclusions:

• Endothelial transport significantly mediates adiponectin oligomer efficacy in different tissues.
• Targeting endothelial dysfunction through exercise and pharmaceuticals can enhance adiponectin's beneficial metabolic effects.
• Understanding adiponectin transport is crucial for developing strategies to manage metabolic syndrome.