Endothelial Cells in Antibody-Mediated Rejection of Kidney Transplantation: Pathogenesis Mechanisms and Therapeutic Implications
Table 2
The proposed mechanisms of endothelial cell-mediated accommodation in ABOi transplantation.
Study
Design
Key findings
Reference
Alleviation of apoptosis and complement
Bach et al.
Hamster to rat heart xenografts
Heart xenografts could acquire accommodation by upregulation of a number of antiapoptotic and anti-inflammatory genes including A20, Bcl-2, Bcl-xl, and hemeoxygenase-1 in endothelial cells.
Immunohistochemistry of the graft biopsies demonstrated increased expression of antiapoptotic protein Bcl-xl in glomerular and peritubular capillary endothelial cells. In vitro experiments confirmed that endothelial cells with upregulated Bcl-xl were rendered resistant to complement-dependent cytotoxicity.
In vitro study of the effects of anti-HLA and anti-A/B antibody binding on complement-mediated cytotoxicity and signal transduction
Accommodation for anti-A/B antibodies relied on unregulated complement regulatory proteins CD55 and CD59 induced by suppressed ERK1/2 pathway, whereas in the background of anti-HLA antibodies activated PI3K/AKT pathway of endothelial cells led to expression of cytoprotective molecules such as hemeoxygenase-1 and ferritin H.
Time-dependent downregulation of donor’s blood-type antigen on the graft endothelium was observed, which might contribute to the long-term accommodation after ABOi kidney transplantation.