An enhanced level of VCAM in transplant preservation fluid is an independent predictor of early kidney allograft dysfunction

Abstract

Background: We aimed to evaluate whether donor-related inflammatory markers found in kidney transplant preservation fluid can associate with early development of kidney allograft dysfunction.

Methods: Our prospective study enrolled 74 consecutive donated organs who underwent kidney transplantation in our center between September 2020 and June 2021. Kidneys from 27 standard criteria donors were allocated to static cold storage and kidneys from 47 extended criteria donors to hypothermic machine perfusion. ELISA assessment of inflammatory biomarkers (IL-6, IL6-R, ICAM, VCAM, TNFα, IFN-g, CXCL1 and Fractalkine) was analyzed in view of a primary endpoint defined as the occurrence of delayed graft function or slow graft function during the first week following transplantation.

Results: Soluble VCAM levels measured in transplant conservation fluid were significantly associated with recipient serum creatinine on day 7. Multivariate stepwise logistic regression analysis identified VCAM as an independent non-invasive predictor of early graft dysfunction, both at 1 week (OR: 3.57, p = .04, 95% CI: 1.06-12.03) and 3 Months (OR: 4.039, p = .034, 95% CI: 1.11-14.73) after transplant surgery.

Conclusions: This prospective pilot study suggests that pre-transplant evaluation of VCAM levels could constitute a valuable indicator of transplant health and identify the VCAM-CD49d pathway as a target to limit donor-related vascular injury of marginal transplants.

Keywords: VCAM = vascular cell adhesion molecule; delayed graft function; extended criteria donor; kidney transplantation; machine perfusion.

Figure 1

Evolution of renal function according to the occurrence of early ECD transplant dysfunction 7 days post-transplant surgery eGFR (mL/min/1.73 m²) was analyzed in kidney transplant recipients at different time points (D: days) and notably at two months and 3 months following transplant surgery within the group of the 47 ECD donors (Extended Criteria Donors), further stratified according to the occurrence or delayed or slow graft dysfunction during the first week following transplantation (DGF/SDG group, lower line) or no early graft dysfunction at day 7 (upper dot line).

Figure 2

Quantitative analysis of soluble inflammatory biomarker levels in transplant preservation fluids. Levels of soluble iammatory markers were analyzed by ELISA in preservation fluids from SCD transplants (Standard criteria donors n = 27, all conserved in static conditions) and from ECD transplant (extended criteria donorsn n=47) further classified as a group of transplants conserved in static conditions (ECD static: n = 8) and a group of transplants conserved by machine Perfusion (ECD MP, n = 39). Different panels of soluble markers evaluated are represented : (A) Soluble IL6, (B) Soluble IL6 receptor, (C) Soluble IFN-gamma, (D) Soluble TNF-alpha, (E) Soluble CXCL1, (F) Soluble Fractalkine, (G) Soluble ICAM, (H) soluble VCAM. Significant p values (p <.05) or trends for significance were (p < .2) resulting from non- parametric Mann-Whitney test comparison of evaluated soluble biomarkers median levels are indicated.

Figure 3

Analysis of fractalkine and VCAM levels association with ECD donor-related risk factors. (A). VCAM levels were significantly correlated with the fractalkine levels evaluated in the perfusion fluid of ECD donors. (B). Comparative analysis of VCAM levels in perfusion fluid of transplant stratified according to three donor-related risk factors (donor age > 58.5 years, HTA and donor stroke) revealed that VCAM levels were significantly higher in aging ECD donors (> to the median 58 years value observed in the cohort and in conservation fluids of transplant from donors with hypertension (HTA). Significant p values (p <.05) or trends for significance were (p < .2) resulting from non-parametric Mann-Whitney test comparison of evaluated soluble biomarkers median levels are indicated. Non-significant values >.2 are not reported. (C). Comparative analysis of fractalkine levels in the perfusion fluid of transplants stratified according to three risk factors (age >58years, HTA and donor stroke) revealed enhanced levels in aging donors and a trend for enhanced fractalkine levels in preservation fluid in deceased donors with stroke.

Figure 4

VCAM levels evaluated in transplant conservation fluid associate with early graft dysfunction. (A). Receiver operating characteristic analysis of the value of VCAM levels predicting early graft dysfunction of ECD transplants at 7 days post-transplant surgery. Area under the curve (AUC) and 95% confidence intervals of prediction models are indicated. (B). Enhanced VCAM values are observed in conservation fluid of machine-perfused transplants with delayed or slow graft dysfunction by day 7. p values were considered significant at <.05.