Targeting Complement Pathways During Cold Ischemia and Reperfusion Prevents Delayed Graft Function

Area of Science:

• Immunology
• Transplantation Biology
• Nephrology

Background:

• The complement system significantly contributes to ischemia-reperfusion injury (IRI) and delayed graft function (DGF) in kidney transplantation.
• Understanding the specific roles of complement activation pathways is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the impact of inhibiting the alternative pathway (AP) and terminal pathway (TP) of the complement system on IRI and DGF in a rat kidney transplantation model.
• To evaluate the efficacy of pretransplant ex vivo and posttransplant systemic administration of complement inhibitors.

Main Methods:

• Donor kidneys were treated ex vivo with TP inhibitor (anti-rat C5 mAb 18A10) or AP inhibitor (TT30) for 28 hours during cold ischemia (CI) in a syngeneic rat kidney transplantation model.
• Graft survival was monitored, and inhibitor efficacy was assessed with pretransplant and posttransplant treatment strategies.

Main Results:

• Pretransplant treatment with 18A10 (TP inhibitor) led to 100% graft survival beyond day 21, while TT30 (AP inhibitor) resulted in 67% survival, compared to 16.7% for controls (p < 0.01).
• Posttransplant systemic treatment with 18A10 significantly increased graft survival (p < 0.01), whereas TT30 showed minimal benefit.
• The alternative pathway plays a key role during CI, but blocking the TP is more effective in preventing reperfusion injury and DGF.

Conclusions:

• Both AP and TP contribute to IRI and DGF in kidney transplantation.
• Targeting the TP, particularly with posttransplant administration, is a promising strategy for preventing reperfusion injury and enhancing graft survival.
• Complement inhibitors show feasibility for preventing DGF in human kidney transplantation.