Discovery and Validation of a Biomarker Model (PRESERVE) Predictive of Renal Outcomes After Liver Transplantation

Acute kidney injury in patients with cirrhosis: Acute Disease Quality Initiative (ADQI) and International Club of Ascites (ICA) joint multidisciplinary consensus meeting

Patients with cirrhosis are prone to developing acute kidney injury (AKI), a complication associated with a markedly increased in-hospital morbidity and mortality, along with a risk of progression to chronic kidney disease. Whereas patients with cirrhosis are at increased risk of developing any phenotype of AKI, hepatorenal syndrome (HRS), a specific form of AKI (HRS-AKI) in patients with advanced cirrhosis and ascites, carries an especially high mortality risk. Early recognition of HRS-AKI is crucial since administration of splanchnic vasoconstrictors may reverse the AKI and serve as a bridge to liver transplantation, the only curative option. In 2023, a joint meeting of the International Club of Ascites (ICA) and the Acute Disease Quality Initiative (ADQI) was convened to develop new diagnostic criteria for HRS-AKI, to provide graded recommendations for the work-up, management and post-discharge follow-up of patients with cirrhosis and AKI, and to highlight priorities for further research.

European Society for Organ Transplantation Consensus Statement on Biomarkers in Liver Transplantation

Currently, one-year survival following liver transplantation (LT) exceeds 90% in large international registries, and LT is considered definitive treatment for patients with end-stage liver disease and liver cancer. Recurrence of disease, including hepatocellular carcinoma (HCC), significantly hampers post-LT outcomes. An optimal approach to immunosuppression (IS), including safe weaning, may benefit patients by mitigating the effect on recurrent diseases, as well as reducing adverse events associated with over-/under-IS, including chronic kidney disease (CKD). Prediction of these outcome measures-disease recurrence, CKD, and immune status-has long been based on relatively inaccurate clinical models. To address the utility of new biomarkers in predicting these outcomes in the post-LT setting, the European Society of Organ Transplantation (ESOT) and International Liver Transplant Society (ILTS) convened a working group of experts to review literature pertaining to primary disease recurrence, development of CKD, and safe weaning of IS. Summaries of evidence were presented to the group of panelists and juries to develop guidelines, which were discussed and voted in-person at the Consensus Conference in Prague November 2022. The consensus findings and recommendations of the Liver Working Group on new biomarkers in LT, clinical applicability, and future needs are presented in this article.

Development and validation of a nomogram model for predicting chronic kidney disease after liver transplantation: a multi-center retrospective study

Chronic kidney disease (CKD) is a frequent complication after liver transplantation (LT) and associated with poor prognosis. In this study, we retrospectively analyzed 515 adult patients who underwent LT in our center. They were randomly divided into a training set (n = 360) and an internal test set (n = 155). Another 118 recipients in other centers served as external validation set. Univariate and multivariate COX regression analysis were used to determine risk factors. A nomogram model was developed to predict post-LT CKD. The incidence of post-LT CKD in our center was 16.9% (87/515) during a median follow-up time of 22.73 months. The overall survival of recipients with severe CKD (stage IV and V) were significantly lower than those with non or mild CKD (stage III) (p = 0.0015). A nomogram model was established based on recipient's age, anhepatic phase, estimated glomerular filtration rate and triglyceride levels at 30 days after LT. The calibration curves for post-LT CKD prediction in the nomogram were consistent with the actual observation in both the internal and external validation set. In conclusion, severe post-LT CKD resulted in a significantly reduced survival in liver recipient. The newly established nomogram model had good predictive ability for post-LT CKD.

Essentials of Liver Transplantation in the Setting of Acute Kidney Injury and Chronic Kidney Disease

Kidney dysfunction is common among liver transplant candidates with decompensated cirrhosis and has a major impact on pre- and post-liver transplant survival. Updated definitions of acute kidney injury and criteria for the diagnosis of hepatorenal syndrome allow for early recognition and intervention, including early initiation of vasoconstrictor therapy for hepatorenal syndrome. The rise of the metabolic syndrome and nonalcoholic fatty liver disease as a cause of cirrhosis has coincided with an increase in intrinsic chronic kidney disease recognized in transplant candidates and recipients. Ultimately, the ability to accurately assess kidney function and associated risk is essential to decision-making in the context of transplantation, including selection of candidates for simultaneous liver and kidney transplantation.

Prognostic value of protein biomarkers in liver transplantation: A systematic review

Liver transplantation is currently the preferred method for the treatment of advanced liver disease and early-stage hepatocellular carcinoma (HCC). Although advances in surgical techniques, immunosuppressive drugs and postoperative management have reduced the incidence of postoperative complications, how to effectively predict or diagnose postoperative complications earlier and reduce their incidence is still a clinical concern. We performed a comprehensive proteomics literature research to identified protein biomarkers in complications after liver transplantation. Seventeen studies met the inclusion criteria including ischemia reperfusion injury (IRI) (n = 4), acute rejection (AR) (n = 4), renal dysfunction (n = 4), HCC recurrence (n = 2), primary graft dysfunction (PGD) (n = 1), infection (n = 1), and liver fibrosis (n = 1). A total of 625 differentially expressed proteins (DEPs) have been reported between postoperative complications and controls, of which 63 have been validated by quantitative protein expression and 26 have been reported by at least two studies and showed consistently changes. The results of the bioinformation analysis show that the immune system, especially the innate immune system and cytokine signaling in immune system, is an important protein-mediated pathway that affects the prognosis of liver transplantation.

ConSIG: consistent discovery of molecular signature from OMIC data

The discovery of proper molecular signature from OMIC data is indispensable for determining biological state, physiological condition, disease etiology, and therapeutic response. However, the identified signature is reported to be highly inconsistent, and there is little overlap among the signatures identified from different biological datasets. Such inconsistency raises doubts about the reliability of reported signatures and significantly hampers its biological and clinical applications. Herein, an online tool, ConSIG, was constructed to realize consistent discovery of gene/protein signature from any uploaded transcriptomic/proteomic data. This tool is unique in a) integrating a novel strategy capable of significantly enhancing the consistency of signature discovery, b) determining the optimal signature by collective assessment, and c) confirming the biological relevance by enriching the disease/gene ontology. With the increasingly accumulated concerns about signature consistency and biological relevance, this online tool is expected to be used as an essential complement to other existing tools for OMIC-based signature discovery. ConSIG is freely accessible to all users without login requirement at https://idrblab.org/consig/.

Role of Novel Kidney Biomarkers in Patients With Cirrhosis and After Liver Transplantation

Acute kidney injury (AKI) and chronic kidney disease (CKD) are important drivers of morbidity and mortality in patients with cirrhosis before and after liver transplantation (LT). In this review, we examine the role of novel kidney biomarkers for early recognition of kidney injury. Studies are limited by lack of reference standards, heterogeneous definitions of outcomes and biomarker cutoffs, and inconsistent diagnostic performance. Overall, a change in biomarker is more relevant than an absolute cutoff. Cystatin C and urinary neutrophil gelatinase-associated lipocalin (uNGAL) are the most studied candidate biomarkers and identify AKI or progression of AKI earlier than serum creatinine (sCr). Kidney injury molecule 1 and liver-type fatty acid-binding protein (L-FABP) also show potential. NGAL and interleukin 18 may play a role in differentiating acute tubular necrosis from other forms of AKI. Combining novel biomarkers with the Model for End-Stage Liver Disease score may assist prognosis. Persistent elevations in select markers (eg, NGAL) can portend irreversible injury. Several pretransplantation markers (including sCr) predict posttransplantation kidney dysfunction. Pretransplantation assessment of clinical factors (eg, age, diabetes) and novel markers (osteopontin and tissue inhibitor of metalloproteinases 1 [TIMP-1]) may predict renal kidney recovery after LT. Intraoperative changes in biomarkers predict early post-LT AKI. Prediction of CKD remains difficult, although a combination of biomarkers (eg, beta-2 microglobulin, CD40) is promising. Novel biomarkers have yet to replace sCr in guideline-based evaluation and management of kidney dysfunction in patients with cirrhosis. We propose a theoretical framework for practical incorporation of these biomarkers that considers patient characteristics (risk for irreversible injury), markers of functional and structural change, and assessment of the AKI-CKD continuum to identify patients at the highest risk for progressive kidney disease before and after LT.

An Essential Guide for Managing Post-Liver Transplant Patients: What Primary Care Physicians Should Know

With long-term survival after liver transplantation becoming the rule, care for medical problems arising over time in liver-transplanted patients gained increasing importance. The most common causes of death occurring more than 1 year after liver transplantation are unrelated to liver diseases and facilitated by immunosuppressive treatments; examples are malignancies, renal failure, and cardiovascular, metabolic, and infectious diseases. Recipients receive life-long follow-up care at transplant centers, however, the increasing number of liver-transplanted patients is saturating the health care supply that transplant centers have to offer. Primary care physicians are increasingly exposed to liver-transplanted patients, even in the early periods after transplant, and an understanding of the most common risks and complications faced by these patients would enhance their care. This article reviews the long-term care of liver transplant recipients, emphasizing the key internal medicine-related issues that should be known by primary care physicians. A specific section is devoted to implementing strategies to involve these physicians in the long-term follow-up of liver-transplanted patients in close collaboration with transplant hepatologists.

Prediction of chronic kidney disease after orthotopic liver transplantation: development and validation of a nomogram model

Background

We aimed to develop and validate a nomogram model for predicting CKD after orthotopic liver transplantation (OLT).

Methods

The retrospective data of 399 patients who underwent transplantation and were followed in our centre were collected. They were randomly assigned to the training set (n = 293) and validation set (n = 106). Multivariable Cox regression analysis was performed in the training set to identify predictors of CKD. According to the Cox regression analysis results, a nomogram model was developed and validated. The renal function of recipients was monitored, and the long-term survival prognosis was assessed.

Results

The incidence of CKD at 5 years after OLT was 25.6%. Cox regression analysis identified several predictors of post-OLT CKD, including recipient age at surgery (HR 1.036, 95% CI 1.006-1.068; p = 0.018), female sex (HR 2.867, 95% CI 1.709-4.810; p < 0.001), preoperative hypertension (HR 1.670, 95% CI 0.962-2.898; p = 0.068), preoperative eGFR (HR 0.996, 95% CI 0.991-1.001; p = 0.143), uric acid at 3 months (HR 1.002, 95% CI 1.001-1.004; p = 0.028), haemoglobin at 3 months (HR 0.970, 95% CI 0.956-0.983; p < 0.001), and average concentration of cyclosporine A at 3 months (HR 1.002, 95% CI 1.001-1.003; p < 0.001). According to these parameters, a nomogram model for predicting CKD after OLT was constructed and validated. The C-indices were 0.75 and 0.80 in the training and validation sets. The calibration curve of the nomogram showed that the CKD probabilities predicted by the nomogram agreed with the observed probabilities at 1, 3, and 5 years after OLT (p > 0.05). Renal function declined slowly year by year, and there were significant differences between patients divided by these predictors. Kaplan-Meier survival analysis showed that the survival prognosis of recipients decreased significantly with the progression of renal function.

Conclusions

With excellent predictive abilities, the nomogram may be a simple and reliable tool to identify patients at high risk for CKD and poor long-term prognosis after OLT.

Kidney Disease After Nonkidney Solid Organ Transplant

Nonkidney solid organ transplants (NKSOTs) are increasing in the United States with improving long-term allograft and patient survival. CKD is prevalent in patients with NKSOT and is associated with increased morbidity and mortality especially in those who progress to end-stage kidney disease. Calcineurin inhibitor nephrotoxicity is a main contributor to CKD after NKSOT, but other factors in the pretransplant, peritransplant, and post-transplant period can predispose to progressive kidney dysfunction. The management of CKD after NKSOT generally follows society guidelines for native kidney disease. Kidney-protective and calcineurin inhibitor-sparing immunosuppression has been explored in this population and warrants a discussion with transplant teams. Kidney transplantation in NKSOT recipients remains the kidney replacement therapy of choice for suitable candidates, as it provides a survival benefit over remaining on dialysis.

Discovery and validation of a novel blood-based molecular biomarker of rejection following liver transplantation

Noninvasive biomarker profiles of acute rejection (AR) could affect the management of liver transplant (LT) recipients. Peripheral blood was collected following LT for discovery (Northwestern University [NU]) and validation (National Institute of Allergy and Infectious Diseases Clinical Trials in Organ Transplantation [CTOT]-14 study). Blood gene profiling was paired with biopsies showing AR or ADNR (acute dysfunction no rejection) as well as stable graft function samples (Transplant eXcellent-TX). CTOT-14 subjects had serial collections prior to AR, ADNR, TX, and after AR treatment. NU cohort gene expression (46 AR, 45 TX) was analyzed using random forest models to generate a classifier training set (36 gene probe) distinguishing AR vs TX (area under the curve 0.92). The algorithm and threshold were locked and tested on the CTOT-14 validation cohort (14 AR, 50 TX), yielding an accuracy of 0.77, sensitivity 0.57, specificity 0.82, positive predictive value (PPV) 0.47, and negative predictive value (NPV) 0.87 for AR vs TX. The probability score line slopes were positive preceding AR, and negative preceding TX and non-AR (TX + ADNR) (P ≤ .001) and following AR treatment. In conclusion, we have developed a blood biomarker diagnostic for AR that can be detected prior to AR-associated graft injury as well a normal graft function (non-AR). Further studies are needed to evaluate its utility in precision-guided immunosuppression optimization following LT.