Delayed graft function after kidney transplantation: the clinical perspective

Exploring associations between anthropometric indices and graft function in patients receiving renal transplant

BACKGROUND

The aim of the present study was to identify indicators of malnutrition, as obtained by anthropometric measurements, that might be potential predictors of transplant outcomes.

METHODS

One hundred and three patients receiving a graft from a living or a deceased donor were included in this prospective study. Body mass index (BMI) based on pretransplant dry body weight, triceps skinfold, mid-arm muscle circumference and corrected mid-arm muscle area were measured. Post-transplant data on delayed graft function (DGF) and glomerular filtration rate (GFR) at discharge were collected until patient discharge.

RESULTS

Delayed graft function developed in 36.9% of the patients. BMI was the only anthropometric variable associated with a higher likelihood of DGF (odds ratio = 1.25, 95% confidence interval = 1.07-1.47) after adjusting for age, gender, donor group, donor age and years of dialysis before transplantation. Obesity was associated with a higher frequency of DGF (83.3% versus 31.1%, P = 0.001) compared to normal weight. GFR at discharge was negatively associated with BMI [β = -0.014 (0.005), P = 0.004], being overweight [β = -0.151 (0.041), P < 0.001] and obesity [β = -0.188 (0.053), P = 0.001], after adjusting for age, gender, donor group, donor age and years of dialysis, but was not associated with indices of muscle reserves.

CONCLUSIONS

The likelihood of DGF was higher among obese patients, whereas GFR at discharge was negatively associated with being overweight and obesity.

Molecular pathogenesis of post-transplant acute kidney injury: assessment of whole-genome mRNA and miRNA profiles

Acute kidney injury (AKI) affects roughly 25% of all recipients of deceased donor organs. The prevention of post-transplant AKI is still an unmet clinical need. We prospectively collected zero-hour, indication as well as protocol kidney biopsies from 166 allografts between 2011 and 2013. In this cohort eight cases with AKI and ten matched allografts without pathology serving as control group were identified with a follow-up biopsy within the first twelve days after engraftment. For this set the zero-hour and follow-up biopsies were subjected to genome wide microRNA and mRNA profiling and analysis, followed by validation in independent expression profiles of 42 AKI and 21 protocol biopsies for strictly controlling the false discovery rate. Follow-up biopsies of AKI allografts compared to time-matched protocol biopsies, further baseline adjustment for zero-hour biopsy expression level and validation in independent datasets, revealed a molecular AKI signature holding 20 mRNAs and two miRNAs (miR-182-5p and miR-21-3p). Next to several established biomarkers such as lipocalin-2 also novel candidates of interest were identified in the signature. In further experimental evaluation the elevated transcript expression level of the secretory leukocyte peptidase inhibitor (SLPI) in AKI allografts was confirmed in plasma and urine on the protein level (p<0.001 and p = 0.003, respectively). miR-182-5p was identified as a molecular regulator of post-transplant AKI, strongly correlated with global gene expression changes during AKI. In summary, we identified an AKI-specific molecular signature providing the ground for novel biomarkers and target candidates such as SLPI and miR-182-5p in addressing AKI.

Preoperative fasting protects against renal ischemia-reperfusion injury in aged and overweight mice

Ischemia-reperfusion injury (IRI) is inevitable during kidney transplantation leading to oxidative stress and inflammation. We previously reported that preoperative fasting in young-lean male mice protects against IRI. Since patients are generally of older age with morbidities possibly leading to a different response to fasting, we investigated the effects of preoperative fasting on renal IRI in aged-overweight male and female mice. Male and female F1-FVB/C57BL6-hybrid mice, average age 73 weeks weighing 47.2 grams, were randomized to preoperative ad libitum feeding or 3 days fasting, followed by renal IRI. Body weight, kidney function and survival of the animals were monitored until day 28 postoperatively. Kidney histopathology was scored for all animals and gene expression profiles after fasting were analyzed in kidneys of young and aged male mice. Preoperative fasting significantly improved survival after renal IRI in both sexes compared with normal fed mice. Fasted groups had a better kidney function shown by lower serum urea levels after renal IRI. Histopathology showed less acute tubular necrosis and more regeneration in kidneys from fasted mice. A mRNA analysis indicated the involvement of metabolic processes including fatty acid oxidation and retinol metabolism, and the NRF2-mediated stress response. Similar to young-lean, healthy male mice, preoperative fasting protects against renal IRI in aged-overweight mice of both genders. These findings suggest a general protective response of fasting against renal IRI regardless of age, gender, body weight and genetic background. Therefore, fasting could be a non-invasive intervention inducing increased oxidative stress resistance in older and overweight patients as well.

Interacting mechanisms in the pathogenesis of cardiac allograft vasculopathy

Cardiac allograft vasculopathy is the major cause of late graft loss in heart transplant recipients. Histological studies of characteristic end-stage lesions reveal arterial changes consisting of a diffuse, confluent, and concentric intimal expansion containing graft-derived cells expressing smooth muscle markers, extracellular matrix, penetrating microvessels, and a host mononuclear cell infiltrate concentrated subjacent to an intact graft-derived luminal endothelial cell lining with little evidence of acute injury. This intimal expansion combined with inadequate compensatory outward remodeling produces severe generalized stenosis extending throughout the epicardial and intramyocardial arterial tree that causes ischemic graft failure. Cardiac allograft vasculopathy lesions affect ≥50% of transplant recipients and are both progressive and refractory to treatment, resulting in ≈5% graft loss per year through the first 10 years after transplant. Lesions typically stop at the suture line, implicating alloimmunity as the primary driver, but pathogenesis may be multifactorial. Here, we will discuss 6 potential contributors to lesion formation (1) conventional risk factors of atherosclerosis; (2) pre- or peritransplant injuries; (3) infection; (4) innate immunity; (5) T-cell-mediated immunity; and (6) B-cell-mediated immunity through production of donor-specific antibody. Finally, we will consider how these various mechanisms may interact with each other.

Delayed graft function in pediatric deceased donor kidney transplantation: donor-related risk factors and impact on two-yr graft function and survival: a single-center analysis

There is mounting evidence that the quality of organs from cadaver donors may be influenced by events occurring around the time of brain death. Aim of this present study was to analyze the correlation of DGF with brain-dead donor variables in a single-center pediatric population and to evaluate DGF influence on patients- and grafts outcome. End-points of the study were DGF prevalence, DGF donor-related risk factors, graft function, patient- and graft survival rate, respectively, at six, 12, and 24 months FU. The univariate analysis showed that donor age above 15 yr and vascular cause of donor brain death represented risk factors for DGF. The multivariate analysis confirmed as independent risk factors for DGF donor age >15 yr. At six months FU, DGF showed a negative impact on graft function. In conclusion, among all considered brain-dead donor resuscitation parameters, just non-traumatic cause of death turned out to be of impact for DGF. Donor age >15 yr represented the only independent risk factor for prolonged DGF in our series of children. At two-yr FU, DGF showed a transient negative impact on six-month graft function.

Interaction between systemic inflammation and renal tubular epithelial cells

Systemic inflammation is known to target tubular epithelial cells (TECs), leading to acute kidney injury. Tubular cells have been implicated in the response to inflammatory mediators in ischaemic and septic renal damage. Moreover, loss of tubular cells by apoptosis or epithelial-to-mesenchymal transition may ingenerate conditions that lead to progression towards chronic kidney disease. On the other hand, TECs may actively contribute to the production of inflammatory mediators that may propagate the injury locally or in distant organs. In the present review, we discuss the tubular cell response and its contribution to systemic inflammation.

Postoperative care/critical care of the transplant patient

Critical care of the general surgical patient requires synthesis of the patient's physiology, intraoperative events, and preexisting comorbidities. Evaluating an abdominal solid-organ transplant recipient after surgery adds a new dimension to clinical decisions because the transplanted allograft has undergone its own physiologic challenges and now must adapt to a new environment. This donor-recipient interaction forms the foundation for assessment of early allograft function (EAF). The intensivist must accurately assess and support EAF within the context of the recipient's current physiology and preexisting comorbidities. Optimizing EAF is essential because allograft failure is a significant predictor of recipient morbidity and mortality.