Targeted Complement Inhibition Protects Vascularized Composite Allografts From Acute Graft Injury and Prolongs Graft Survival When Combined With Subtherapeutic Cyclosporine A Therapy

Transplantation. 2017 Apr;101(4):e75-e85. doi: 10.1097/TP.0000000000001625.

Abstract

Background: Recipients of vascularized composite allografts require aggressive and lifelong immunosuppression, and because the surgery is usually performed in nonlife-threatening situations, the development of strategies to minimize immunosuppression is especially pertinent for this procedure. We investigated how complement affects acute graft injury, alloimmunity, and immunosuppressive therapy.

Methods: Vascularized composite allografts were transplanted from Balb/C to C57BL/6 mice that were complement deficient (C3 or double C3a Receptor (R)/C5aR), or treated with a targeted complement inhibitor (CR2-Crry). Allografts were analyzed for acute inflammation and injury, subacute T cell response, and survival in the absence and presence of cyclosporine A (CsA) therapy.

Results: Allografts in C3-deficient or CR2-Crry-treated recipients were protected from skin and muscle ischemia-reperfusion injury (IRI). C3aR/C5aR-deficient recipients were more modestly protected. IgM and C3d colocalized within allografts from wild type and C3aR/C5aR-deficient recipients indicating IgM-mediated complement activation, and C3d deposition was almost absent in allografts from C3-deficient and CR2-Crry-treated recipients. Inflammatory cell infiltration and P-selectin expression was also significantly reduced in C3-deficient and CR2-Crry-treated recipients. Acute treatment with CR2-Crry or with 3 mg/kg per day CsA modestly, but significantly increased median allograft survival from 5.8 to 7.4 and 7.2 days, respectively. However, combined acute CR2-Crry treatment and CsA therapy increased mean graft survival to 17.2 days. Protection was associated with significantly reduced T cell infiltration of allografts and Tc1 cells in recipient spleens.

Conclusions: Complement-mediated IRI augments graft allogenicity, and appropriate complement inhibition ameliorates IRI, decreases alloimmune priming and allows more immune-sparing CsA dosing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Chemotaxis, Leukocyte / drug effects
  • Complement Activation / drug effects
  • Complement C3 / deficiency
  • Complement C3 / genetics
  • Complement Inactivating Agents / pharmacology*
  • Composite Tissue Allografts / blood supply
  • Composite Tissue Allografts / drug effects*
  • Composite Tissue Allografts / immunology
  • Composite Tissue Allografts / transplantation*
  • Cyclosporine / pharmacology*
  • Genotype
  • Graft Survival / drug effects*
  • Hindlimb / blood supply
  • Hindlimb / drug effects*
  • Hindlimb / immunology
  • Hindlimb / transplantation*
  • Immunosuppressive Agents / pharmacology*
  • Male
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Models, Animal
  • Phenotype
  • Receptor, Anaphylatoxin C5a / deficiency
  • Receptor, Anaphylatoxin C5a / genetics
  • Receptors, G-Protein-Coupled / deficiency
  • Receptors, G-Protein-Coupled / genetics
  • Recombinant Fusion Proteins / pharmacology*
  • Reperfusion Injury / etiology
  • Reperfusion Injury / immunology
  • Reperfusion Injury / metabolism
  • Reperfusion Injury / prevention & control*
  • Spleen / drug effects
  • Spleen / immunology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology
  • Time Factors
  • Vascularized Composite Allotransplantation* / adverse effects

Substances

  • C3 protein, mouse
  • C3a-derived anaphylatoxin receptor, mouse
  • CR2-Crry fusion protein, mouse
  • Complement C3
  • Complement Inactivating Agents
  • Immunosuppressive Agents
  • Receptor, Anaphylatoxin C5a
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins
  • Cyclosporine