Circulating AST, H-FABP, and NGAL are Early and Accurate Biomarkers of Graft Injury and Dysfunction in a Preclinical Model of Kidney Transplantation

Abstract

Objective: To investigate circulating biomarkers of initial graft injury in a porcine kidney autotransplant model. Background: Injury endured by kidney grafts early posttransplant determines their outcome. However, creatinine (clearance) is a poor surrogate of tissue injury and urinary biomarkers are limited by graft anuria or persistent native kidney diuresis. No validated circulating biomarkers quantifying initial graft injury exist. Methods: Minimally injured porcine kidney grafts (n = 6) were cold stored (18 hours) and autotransplanted. Moderately (n = 6) and severely injured grafts (n = 7) were exposed to 30 or 60 minutes warm ischemia before storage and autotransplantation. Four biomarkers [aspartate transaminase (AST), hearttype fatty acid-binding protein (H-FABP), neutrophil gelatinase-associated lipocalin (NGAL), and N-acetyl-β-glucosaminidase (NAG)] were measured posttransplant and compared with creatinine (clearance) and histology. Results: Diuresis was delayed in moderately [2.5 days (2-3)] and severely [4 days (4-5)] versus minimally injured grafts (P < 0.001). Creatinine peaked later than AST, H-FABP, and NGAL [4 days (3-5) vs 3 hours (3-6), 6 hours (6-24), 2 days (1-3), respectively] and only differentiated minimally from severely injured grafts. Peak AST and H-FABP distinguished all injury grades. Neutrophil gelatinase-associated lipocalin discriminated initial graft injury 2 days posttransplant. Peak AST, H-FABP, and NGAL correlated with peak creatinine [Pearson coefficients: 0.70 (P = 0.001), 0.85 (P < 0.0001), 0.80 (P < 0.0001)]. N-acetyl-β-glucosaminidase was not different. Decreased clearance accounted for a small percentage of H-FABP and NGAL increase. Histology was not different among transplanted groups. Conclusion: Plasma AST, H-FABP, and NGAL reflect the severity of initial kidney graft injury and predict graft dysfunction earlier and more accurately than creatinine (clearance) and histology. They represent promising tools to improve patient care after kidney transplantation. (Ann Surg 2011;254:784-792) E ach step of the kidney transplant process contributes to parenchymal graft injury, culminating early after revascularization because of ischemia-reperfusion injury.

Renal auto-transplantation promotes cortical microvascular network remodeling in a preclinical porcine model

“…A sample size of five pigs per group was calculated based on a 2-sided α of 0.05, a power (1-β error probability) of 0.80, and an effect size of 2.1, based on our main criterion which was a decrease in the number of vessels with a diameter < 30 μm (G*Power software 3.1) [22]. Statistical analysis was performed using NCSS 2007 for Windows (Hintze, J.…”

Fast Detection of Renal Ischemia in Transplanted Kidneys With Delayed Graft Function—An Experimental Study

“…However, NGAL has only been described in few porcine studies (15Y17). They demonstrated increasing NGAL perfusate levels in machine-perfused kidneys (15) and increased plasma NGAL of reperfused injured kidney grafts (16). In our experimental model, delayed graft function was also associated with a substantial and significant increase in plasma NGAL levels throughout the study.…”

Alterações no perfil metabólico em resposta a isquemia/reperfusão renal em modelo suíno de lesão renal aguda

“…Estudos da NGAL em modelo suíno de isquemia detectaram aumento nas concentrações urinárias de animais isquêmicos (Silberstein et al 2013) - (Hunter et al 2012). Avaliações séricas de NGAL mostraram aumento desta em 48h pós transplante (Jochmans et al 2011) e após 8 horas de I/R bilateral de 120 minutos de isquemia com grande lesão (Matějková et al 2013). …”

“…Talvez, a análise sanguínea possa apresentar biomarcadores tão sensíveis e específicos quanto os da urina sem a interferência nutricional e de metabolização como acontece na urina. Os suínos têm sido utilizados amplamente em modelos pré-clínicos para doenças cardiovascular (Ho et al 2009), intestinal (Korth U et al 2003) e transplante renal (Jochmans et al 2011). …”

“…Baseado nesses valores, apenas dois animais seriam classificados com LRA em nosso hilar e o grupo controle (Silberstein et al 2013), podendo ser uma resposta a lesão cirúrgica. Outros estudos mostraram aumento após 48h de transplante renal (Jochmans et al 2011) e após 8 horas de reperfusão da I/R renal bilateral de 120 minutos (Matějková et al 2013 No padrão de proteínas excretadas que apresentamos neste estudo, encontramos proteínas com alto peso molecular presentes na urina durante a isquemia e no início da reperfusão, similar ao descrito em indivíduos transplantados (Artz et al 2014) (Stefanidis et al 1996). Desde o início da isquemia, os podócitos são submetidos ao achatamento e espalhamento (Racusen et al 1984) associado à perda de heparan sulfato da membrana basal glomerular, levando a redução da seletividade por carga e tamanho, e assim, aumentando os poros glomerulares e excretando proteínas de maior peso melocular.…”