Angiotensin II Type 1 Receptor Expression in Renal Transplant Biopsies and Anti-AT1R Antibodies in Serum Indicates the Risk of Transplant Loss

Abstract

The manifestation of anti-angiotensin II type 1 receptor (AT1R) antibodies is considered a risk factor for transplant injury; however, the occurrence of angiotensin II type 1 (AT1)-Receptor expression in renal transplant biopsy may help to predict transplant loss.The aim of our study was to evaluate the expression of AT1-Receptors together with their antibodies and assess the risk of transplant loss in patients who had a renal transplant indication biopsy. MethodsAT1-Receptor immunoreactivity was analyzed in renal transplant biopsies. Additionally, we analyzed the presence of anti-AT1R antibodies in these patients using the enzyme-linked immunosorbent assay (ELISA) method. A result ≥ 10 was assessed as positive.An immunohistochemical evaluation of AT1-Receptor expression was performed on 4 μm-thick paraffin sections mounted on salinized slides. ResultsWe checked 156 samples of biopsies for the immunoreactivity of the AT1-Receptor. Additionally, we analyzed the presence of anti-AT1R antibodies in these patients using the ELISA method.A group of 67 patients had positive AT1-Receptor expression, and 16 patients had positive anti-AT1R antibodies (R+Ab+) results. A group of 89 patients had no expression of AT1-Receptor, among which 51 had also no anti-AT1R (R-Ab-). One-year postbiopsy graft loss in the R+Ab+ patients was 37% (6/16) compared to 10% (7/69) in the R-Ab- patients (P = .006).Two-year and 3-year graft loss was 43% versus 17% and 50% versus 21%, respectively. ConclusionsThe presence of anti-AT1R antibodies in serum together with the expression of AT1-Receptor in transplant biopsies was associated with a significantly higher graft loss. The relevance of AT1-Receptor expression analyzed together with anti-AT1R antibodies should be considered for better transplant immunologic risk assessment.