Supplementary Material for: Hypertension in living kidney donors has no effect on complement activation and fibrosis

Background: In the past, elevated blood pressure was considered an exclusion criterion for living kidney donation because of concerns about premature kidney failure. Hypertension leads to complement deposits and renal fibrosis in the kidney. Therefore, the aim of this study was to investigate whether increased complement deposits and fibrosis can be observed in grafts of hypertensive compared to normotensive living donors. Methods: Zero-time renal biopsies from 238 living donors (52 hypertensive) and the corresponding one-year protocol biopsies were examined for complement deposits of C1q, C3c, and MASP-2. Findings were compared to kidney biopsies from patients with hypertensive nephropathy. Further, renal fibrosis was visualized by Sirius Red staining, scored semiquantitatively and compared to biopsies from deceased donors and kidneys with hypertensive nephropathy. Additionally, zero-time biopsies from hypertensive (n = 6) and normotensive (n = 5) living donors were analyzed for expression of fibrosis-associated genes by multiplex mRNA analysis and compared to zero-time biopsies (n = 6) from deceased donors. Results: In all zero-time biopsies from living donors, complement deposits were minimal for C1q, C3c, and MASP-2 compared to samples with hypertensive nephropathy, regardless of whether the donor was hypertensive or normotensive. In one-year protocol biopsies, complement deposits were unchanged, while renal fibrosis was slightly but not significantly increased in hypertensive compared to normotensive living donors. Gene expression data showed that the 11 zero-time biopsies from hypertensive and normotensive living donors clustered together, and were clearly separated from the deceased donor biopsies. Conclusion: The use of kidneys from hypertensive living donors appears to have no or little effect on renal complement deposits and fibrosis one year after transplantation.