Thaunat, Olivier

Background. Chronic kidney disease (CKD) is a common complication of nonrenal transplantation, influencing recipients’ morbidity and mortality. The incidence of CKD varies depending on the transplanted organ. Recipients of vascularized composite allotransplantation (VCA) need lifelong immunosuppression similar to that of solid organ transplantation. This study investigated renal function in VCA recipients. Methods. We studied 70 recipients from 17 centers (median follow-up: 8 y): 59 upper extremity, 10 face, and 1 penis transplant. Pretransplant and posttransplant clinical data and sera were collected to calculate the estimated glomerular filtration rate (eGFR) using the CKD Epidemiology collaboration 2021 formula. Results. Pretransplantation, the median eGFR was 105.36 mL/min (range, 71.39–155.39 mL/min). By 3 mo posttransplant, the eGFR had significantly decreased to 78.42 mL/min (range, 32.49–130.74 mL/min; P = 0.001) before stabilizing. Despite higher tacrolimus levels at 3 mo, no correlation with eGFR was found. During follow-up, 17.1% of patients experienced a ≥50% eGFR decline, 10.9% progressed to CKD, and 4.7% developed end-stage kidney disease. Some risk factors were identified, but their responsibility could not be established with certainty because of the low number of severe renal outcomes. Conclusions. Renal function declines in the majority of VCA recipients, but the function loss is lower compared with nonrenal solid organ transplantation recipients. Although no statistically significant correlation could be established between tacrolimus exposure and renal function decline, strategies aiming at minimizing calcineurin inhibitor exposure and avoiding other nephrotoxic causes are recommended to preserve long-term kidney function.

Abstract Renal transplant is the treatment of choice for patients with terminal end-stage renal disease. We have previously identified low levels of catalytic IgG as a potential prognosis marker for chronic allograft rejection. The origin and physiopathological relevance of catalytic Abs is not well understood, owing to the fact that catalytic Abs have been studied in relatively small cohorts of patients with rare diseases and/or without systematic follow-up. In the current study, we have followed the evolution of the levels of catalytic IgG in a large cohort of renal transplant patients over a 2-y period. Our results demonstrate that, prior to transplant, patients with renal failure present with heterogeneous levels of IgG hydrolyzing the generic proline-phenylalanine-arginine-methylcoumarinamide (PFR-MCA) substrate. PFR-MCA hydrolysis was greater for patients’ IgG than for a therapeutic preparation of pooled IgG from healthy donors. Renal transplant was marked by a drastic decrease in levels of catalytic IgG over 3 mo followed by a steady increase during the next 21 mo. Patients who displayed high levels of catalytic IgG pretransplant recovered high levels of catalytic Abs 2 y posttransplant. Interestingly, IgG-mediated hydrolysis of a model protein substrate, procoagulant factor VIII, did not correlate with that of PFR-MCA prior transplantation, whereas it did 12 mo posttransplant. Taken together, our results suggest that the level of circulating catalytic IgG under pathological conditions is an intrinsic property of each individual’s immune system and that recovery of pretransplant levels of catalytic IgG is accompanied by changes in the repertoire of target Ags.