The impact of immunosuppression on endothelial function.

Area of Science:

• Transplant immunology
• Vascular biology
• Pharmacology

Background:

• Endothelial dysfunction is an early indicator of transplant atherosclerosis.
• Mechanisms include alloimmunity, ischemia/reperfusion, metabolic changes, infections, and drug toxicity.
• No studies have directly compared immunosuppressants' effects on endothelial function under varying oxygen conditions.

Purpose of the Study:

• To compare the effects of different immunosuppressive drugs on human microvascular endothelial cells (HMEC-1) in vitro.
• To assess drug-induced oxidative stress, apoptosis, metabolic activity, proliferation, endothelin-1 (ET-1) release, and nitric oxide (NO) production.
• To investigate the influence of normoxic and hypoxic conditions on these cellular responses.

Main Methods:

• HMEC-1 cells were stimulated with therapeutic concentrations of methylprednisolone (MP), mycophenolic acid (MMF), cyclosporine A (CS), rapamycin (Rapa), and tacrolimus (Tac).
• Assays measured oxidative stress, apoptosis, metabolic activity, proliferation, ET-1, and NO production.
• Experiments were conducted under both normoxic and hypoxic conditions.

Main Results:

• CS, MMF, and Rapa induced greater oxidative stress than MP and Tac, correlating with metabolic activity and apoptosis.
• MMF inhibited proliferation under hypoxia; low-dose CS and MP increased proliferation.
• ET-1 release increased with Rapa, Tac, and MP; NO production increased with all drugs except Tac.
• MP and MMF caused fewer endothelial changes compared to CS, Rapa, and Tac.

Conclusions:

• Immunosuppression quality and quantity significantly modify endothelial function.
• Drug effects on endothelial cells are dose-dependent and influenced by oxygenation status.
• CS, Rapa, and Tac demonstrate a greater potential for endothelial dysfunction compared to MP and MMF.