Docosahexaenoic acid reverses cyclosporin A-induced changes in membrane structure and function

Area of Science:

• Biochemistry
• Pharmacology
• Toxicology

Background:

• Cyclosporin A (CsA) toxicity can be reduced by fish oil, but the underlying mechanism is not fully understood.
• Docosahexaenoic acid (DHA), a key omega-3 fatty acid in fish oil, is investigated for its role in modulating CsA toxicity.
• CsA's toxic effects are hypothesized to stem from membrane perturbation.

Purpose of the Study:

• To elucidate the mechanism by which non-oxidized docosahexaenoic acid (DHA) mitigates cyclosporin A (CsA) toxicity.
• To investigate the impact of DHA oxidation on its protective effects against CsA-induced membrane and organ damage.
• To assess the influence of CsA and DHA on endothelial macromolecular permeability and membrane bilayer function.

Main Methods:

• In vivo studies using mice treated with CsA and fish oil to evaluate organ toxicity and DHA incorporation.
• In vitro membrane studies using dipalmitoylphosphatidylcholine (DPPC) bilayers to assess permeability changes with CsA and DHA.
• Spectroscopic analysis using DPH fluorescence anisotropy to evaluate membrane fluidity alterations.
• Endothelial cell permeability assays measuring albumin passage.

Main Results:

• Mice receiving CsA and fish oil exhibited increased liver and kidney toxicity, alongside evidence of DHA oxidation.
• Non-oxidized DHA counteracted CsA-induced increases in DPPC membrane permeability and endothelial permeability to albumin.
• Oxidized DHA lost its protective effect, with CsA and oxidized DHA combinations showing similar toxicity to CsA alone.
• DHA alone decreased membrane fluidity, while CsA increased it; their combination resembled DHA's effect alone.

Conclusions:

• Non-oxidized docosahexaenoic acid (DHA) effectively reverses the membrane-perturbing and permeability-increasing effects of cyclosporin A (CsA).
• This reversal of membrane effects by non-oxidized DHA likely explains the observed reduction in CsA toxicity when administered with fish oil.
• Oxidation of DHA negates its protective role, highlighting the importance of DHA's structural integrity in mitigating CsA's adverse effects.