Mechanisms of drug resistance in HCC.

HCC comprises ∼80% of primary liver cancer. HCC is the only major cancer for which death rates have not improved over the last 10 years. Most patients are diagnosed with advanced disease when surgical and locoregional treatments are not feasible or effective. Sorafenib, a multikinase inhibitor targeting cell growth and angiogenesis, was approved for advanced unresectable HCC in 2007. Since then, other multikinase inhibitors have been approved. Lenvatinib was found to be noninferior to sorafenib as a first-line agent. Regorafenib, cabozantinib, and ramucirumab were shown to prolong survival as second-line agents. Advances in immunotherapy for HCC have also added hope for patients, but their efficacy remains limited. A large proportion of patients with advanced HCC gain no long-term benefit from systemic therapy due to primary and acquired drug resistance, which, combined with its rising incidence, keeps HCC a highly fatal disease. This review summarizes mechanisms of primary and acquired resistance to therapy and includes methods for bypassing resistance. It addresses recent advancements in immunotherapy, provides new perspectives on the linkage between drug resistance and molecular etiology of HCC, and evaluates the role of the microbiome in drug resistance. It also discusses alterations in signaling pathways, dysregulation of apoptosis, modulations in the tumor microenvironment, involvement of cancer stem cells, changes in drug metabolism/transport, tumor hypoxia, DNA repair, and the role of microRNAs in drug resistance. Understanding the interplay among these factors will provide guidance on the development of new therapeutic strategies capable of improving patient outcomes.

Quantitative methods for optimizing patient outcomes in liver transplantation.

Liver transplantation (LT) is a lifesaving yet complex intervention with considerable challenges impacting graft and patient outcomes. Despite best practices, 5-year graft survival is only 70%. Sophisticated quantitative techniques offer potential solutions by assimilating multifaceted data into insights exceeding human cognition. Optimizing donor-recipient matching and graft allocation presents additional intricacies, involving the integration of clinical and laboratory data to select the ideal donor and recipient pair. Allocation must balance physiological variables with geographical and logistical constraints and timing. Quantitative methods can integrate these complex factors to optimize graft utilization. Such methods can also aid in personalizing treatment regimens, drawing on both pretransplant and posttransplant data, possibly using continuous immunological monitoring to enable early detection of graft injury or infected states. Advanced analytics is thus poised to transform management in LT, maximizing graft and patient survival. In this review, we describe quantitative methods applied to organ transplantation, with a focus on LT. These include quantitative methods for (1) utilizing and allocating donor organs equitably and optimally, (2) improving surgical planning through preoperative imaging, (3) monitoring graft and immune status, (4) determining immunosuppressant doses, and (5) establishing and maintaining the health of graft and patient after LT.

Loss of CEACAM1 in hepatocytes causes hepatic fibrosis.

BACKGROUND: The role of insulin resistance in hepatic fibrosis in Metabolic dysfunction-Associated SteatoHepatitis (MASH) remains unclear. Carcinoembryonic Antigen-related Cell Adhesion Molecule1 protein (CEACAM1) promotes insulin clearance to maintain insulin sensitivity and repress de novo lipogenesis, as bolstered by the development of insulin resistance and steatohepatitis in AlbuminCre + Cc1fl/fl mice with liver-specific mouse gene encoding CEACAM1 protein (Ceacam1) deletion. We herein investigated whether these mice also developed hepatic fibrosis and whether hepatic CEACAM1 is reduced in patients with MASH at different fibrosis stages. METHODS: AlbuminCre + Cc1fl/fl mice were fed a regular or a high-fat diet before their insulin metabolism and action were assessed during IPGTT, and their livers excised for histochemical, immunohistochemical and Western blot analysis. Sirius red staining was used to assess fibrosis, and media transfer was employed to examine whether mutant hepatocytes activated hepatic stellate cells (HSCs). Hepatic CEACAM1 protein levels in patients with varying disease stages were assessed by ELISA. RESULTS: Hepatocytic deletion of Ceacam1 caused hyperinsulinemia-driven insulin resistance emanating from reduced hepatic insulin clearance. AlbuminCre + Cc1fl/fl livers showed inflammation, fibrosis and hepatic injury, with more advanced bridging and chicken-wire hepatic fibrosis under high-fat conditions. Media transferred from hepatocytes isolated from mutant mice activated control HSCs, likely owing to their elevated endothelin1 content. Interestingly, hepatic CEACAM1 levels were lower in the livers of patients with MASH and declined gradually with advanced fibrosis stage. CONCLUSIONS: Hepatic CEACAM1 levels declined with progression of MASH in humans. The phenotype of AlbuminCre + Cc1fl/fl mice assigned a key role to CEACAM1 loss from hepatocytes in hepatic fibrosis independently of other liver cells.

American Society of Transplant Surgeons recommendations on best practices in donation after circulatory death organ procurement.

The American Society of Transplant Surgeons supports efforts to increase the number of organs that are critically needed for patients desperately awaiting transplantation. In the United States, transplantation using organs procured from donation after circulatory death (DCD) donors has continued to increase in number. Despite these increases, substantial variability in the utilization and practices of DCD transplantation still exists. To improve DCD organ utilization, it is important to create a set of best practices for DCD recovery. The following recommendations aim to provide guidance on contemporary issues surrounding DCD organ procurement in the United States. A work group was composed of members of the American Society of Transplant Surgeon Scientific Studies Committee and the Thoracic Organ Transplantation Committee. The following topics were identified by the group either as controversial or lacking standardization: prewithdrawal preparation, definition of donor warm ischemia time, DCD surgical technique, combined thoracic and abdominal procurements, and normothermic regional perfusion. The proposed recommendations were classified on the basis of the grade of available evidence and the strength of the recommendation. This information should be valuable for transplant programs as well as for organ procurement organizations and donor hospitals as they develop robust DCD donor procurement protocols.

Resolution of inflammation via RvD1/FPR2 signaling mitigates Nox2 activation and ferroptosis of macrophages in experimental abdominal aortic aneurysms.

Abdominal aortic aneurysm (AAA) formation is characterized by inflammation, leukocyte infiltration, and vascular remodeling. Resolvin D1 (RvD1) is derived from ω-3 polyunsaturated fatty acids and is involved in the resolution phase of chronic inflammatory diseases. The aim of this study was to decipher the protective role of RvD1 via formyl peptide receptor 2 (FPR2) receptor signaling in attenuating abdominal aortic aneurysms (AAA). The elastase-treatment model of AAA in C57BL/6 (WT) mice and human AAA tissue was used to confirm our hypotheses. Elastase-treated FPR2-/- mice had a significant increase in aortic diameter, proinflammatory cytokine production, immune cell infiltration (macrophages and neutrophils), elastic fiber disruption, and decrease in smooth muscle cell α-actin expression compared to elastase-treated WT mice. RvD1 treatment attenuated AAA formation, aortic inflammation, and vascular remodeling in WT mice, but not in FPR2-/- mice. Importantly, human AAA tissue demonstrated significantly decreased FPR2 mRNA expression compared to non-aneurysm human aortas. Mechanistically, RvD1/FPR2 signaling mitigated p47phox phosphorylation and prevented hallmarks of ferroptosis, such as lipid peroxidation and Nrf2 translocation, thereby attenuating HMGB1 secretion. Collectively, this study demonstrates RvD1-mediated immunomodulation of FPR2 signaling on macrophages to mitigate ferroptosis and HMGB1 release, leading to resolution of aortic inflammation and remodeling during AAA pathogenesis.

High levels of donor-derived cell-free DNA in a case of graft-versus-host-disease following liver transplantation.

The diagnosis of graft-versus-host-disease (GVHD) after solid organ transplantation is made difficult by its variable clinical presentation and lack of sensitive and specific biomarkers to evaluate the immune state of transplant recipients. Emerging noninvasive diagnostic techniques like the quantification of donor-derived cell-free DNA (dd-cfDNA) for surveillance may improve the current standard-of-care. Herein, we report the use of this methodology in a patient with GVHD and corresponding levels of dd-cfDNA without any evidence of graft injury. Correlation of dd-cfDNA levels with the clinical course and its novel application here could lead to improvements in the rapid diagnosis of GVHD and in monitoring of response to treatment.

Disulfide High-Mobility Group Box 1 Drives Ischemia-Reperfusion Injury in Human Liver Transplantation.

BACKGROUND AND AIMS: Sterile inflammation is a major clinical concern during ischemia-reperfusion injury (IRI) triggered by traumatic events, including stroke, myocardial infarction, and solid organ transplantation. Despite high-mobility group box 1 (HMGB1) clearly being involved in sterile inflammation, its role is controversial because of a paucity of patient-focused research. APPROACH AND RESULTS: Here, we examined the role of HMGB1 oxidation states in human IRI following liver transplantation. Portal blood immediately following allograft reperfusion (liver flush; LF) had increased total HMGB1, but only LF from patients with histopathological IRI had increased disulfide-HMGB1 and induced Toll-like receptor 4-dependent tumor necrosis factor alpha production by macrophages. Disulfide HMGB1 levels increased concomitantly with IRI severity. IRI+ prereperfusion biopsies contained macrophages with hyperacetylated, lysosomal disulfide-HMGB1 that increased postreperfusion at sites of injury, paralleling increased histone acetyltransferase general transcription factor IIIC subunit 4 and decreased histone deacetylase 5 expression. Purified disulfide-HMGB1 or IRI+ blood stimulated further production of disulfide-HMGB1 and increased proinflammatory molecule and cytokine expression in macrophages through a positive feedback loop. CONCLUSIONS: These data identify disulfide-HMGB1 as a mechanistic biomarker of, and therapeutic target for, minimizing sterile inflammation during human liver IRI.

Machine perfusion organ preservation: Highlights from the American Transplant Congress 2021.

The American Transplant Congress 2021 was a virtual meeting and occurred between June 4 and June 9 through an online platform. We highlighted abstracts discussing machine perfusion preservation, a hot topic that may become the gold standard of organ preservation in the future. A total of 33 abstracts on organ machine preservation (3 for heart, 4 for lungs, 18 for liver, and 8 for kidneys) were presented at the meeting. We selected 23 abstracts that showed advances including new approaches to organ preservation, promising treatments and biomarkers, cellular therapy, and novel research areas. Here, we summarize the new developments concerning machine perfusion in both experimental and clinical studies.

Progress and challenges in diagnosis and treatment of rejection following liver transplantation.

PURPOSE OF REVIEW: Liver biopsy remains the most widely utilized method for diagnosis of allograft rejection following liver transplantation. However, associated risks and limitations present an opportunity for emerging noninvasive diagnostic techniques to improve upon the current standard of care. This review evaluates progress toward development of new noninvasive methods for the monitoring and diagnosing of allograft rejection. RECENT FINDINGS: Recent studies investigate the potential of a variety of analytes. Quantification of dd-cfDNA and of DSA show potential to indicate status of allograft rejection and aid in immunosuppression modulation. Moreover, mRNA microarray profiling of differentially expressed genes, as well as characterization of cytokine responses and immunophenotypic shifts following liver transplantation, may predict and recognize rejection events. SUMMARY: Noninvasive methods are not yet ready to replace liver biopsy as the standard of care for diagnosis of allograft rejection, though several assays and biomarkers have shown promising preliminary results. As noninvasive techniques become validated in clinical settings, their integration with current diagnostic methods is likely to foster increased sensitivity, specificity, and reliability of diagnosis.

What Can We Learn About Drug Safety and Other Effects in the Era of Electronic Health Records and Big Data That We Would Not Be Able to Learn From Classic Epidemiology?

As more and more health systems have converted to the use of electronic health records, the amount of searchable and analyzable data is exploding. This includes not just provider or laboratory created data but also data collected by instruments, personal devices, and patients themselves, among others. This has led to more attention being paid to the analysis of these data to answer previously unaddressed questions. This is especially important given the number of therapies previously found to be beneficial in clinical trials that are currently being re-scrutinized. Because there are orders of magnitude more information contained in these data sets, a fundamentally different approach needs to be taken to their processing and analysis and the generation of knowledge. Health care and medicine are drivers of this phenomenon and will ultimately be the main beneficiaries. Concurrently, many different types of questions can now be asked using these data sets. Research groups have become increasingly active in mining large data sets, including nationwide health care databases, to learn about associations of medication use and various unrelated diseases such as cancer. Given the recent increase in research activity in this area, its promise to radically change clinical research, and the relative lack of widespread knowledge about its potential and advances, we surveyed the available literature to understand the strengths and limitations of these new tools. We also outline new databases and techniques that are available to researchers worldwide, with special focus on work pertaining to the broad and rapid monitoring of drug safety and secondary effects.

Recent advances in precision medicine for individualized immunosuppression.

PURPOSE OF REVIEW: The current tools to proactively guide and individualize immunosuppression in solid organ transplantation are limited. Despite continued improvements in posttransplant outcomes, the adverse effects of over-immunosuppression or under-immunosuppression are common. The present review is intended to highlight recent advances in individualized immunosuppression. RECENT FINDINGS: There has been a great focus on genomic information to predict drug dose requirements, specifically on single nucleotide polymorphisms of CYP3A5 and ABCB1. Furthermore, biomarker studies have developed ways to better predict clinical outcomes, such as graft rejection. SUMMARY: The integration of advanced computing tools, such as artificial neural networks and machine learning, with genome sequencing has led to intriguing findings on individual or group-specific dosing requirements. Rapid computing allows for processing of data and discovering otherwise undetected clinical patterns. Genetic polymorphisms of CYP3A5 and ABCB1 have yielded results to suggest varying dose requirements correlated with race and sex. Newly proposed biomarkers offer precise and noninvasive ways to monitor patient's status. Cell-free DNA quantitation is increasingly explored as an indicator of allograft injury and rejection, which can help avoid unneeded biopsies and more frequently monitor graft function.

Recombinant relaxin protects liver transplants from ischemia damage by hepatocyte glucocorticoid receptor: From bench-to-bedside.

Hepatic ischemia-reperfusion injury (IRI) represents a major risk factor of early graft dysfunction and acute/chronic rejection as well as a key obstacle to expanding the donor pool in orthotopic liver transplantation (OLT). Although glucocorticoid receptor (GR) signaling may enhance cytoprotective programs, clinical use of glucocorticoid is limited because of adverse effects, whereas clinical relevance of GR-facilitated cytoprotection in OLT remains unknown. We aimed to evaluate the significance of hepatic GR in clinical OLT and verify the impact of recombinant human relaxin (rhRLX), which may function as a GR agonist in a tissue/disease-specific manner. Fifty-one OLT patients were recruited under an institutional research board (IRB) protocol. Liver biopsies were collected after cold storage (presurgery) and 2 hours postreperfusion (before abdominal closure), followed by western blotting-assisted hepatic analyses. Forty-three percent of OLTs failed to increase GR perioperatively under surgical stress. Post-/pre-GR ratios at postoperative day 1 correlated negatively with serum aspartate aminotransferase (AST)/cleaved caspase-3 and positively with B-cell lymphoma-extra large (Bcl-xL)/B-cell lymphoma 2 (Bcl-2) levels. In a murine OLT model with extended (18-hour) cold storage, treatment with rhRLX ameliorated ischemia-reperfusion (IR) damage and improved survival while up-regulating hepatocyte GR and Bcl-xL/Bcl-2 expression in OLT. rhRLX-induced GR suppressed hepatocyte high-mobility group box 1 (HMGB1) translocation/release, accompanied by decreased Toll-like receptor 4 (TLR4)/receptor for advanced glycation end products (RAGE), suppressed interleukin 1 beta (IL1ß), chemokine (C-C motif) ligand 2 (CCL2), C-X-C motif chemokine (CXCL)10, tumor necrosis factor alpha (TNFα), CXCL1, and CXCL2 levels, and attenuated neutrophil/macrophage accumulation in OLT. Inhibition of GR in hepatocyte culture and in OLT diminished rhRLX-mediated cytoprotection. CONCLUSION: This translational study underscores the role of rhRLX-GR signaling as a regulator of hepatocellular protection against IR stress in OLT. In the context of a recent phase III clinical trial demonstrating positive outcomes of rhRLX in patients with acute heart failure, studies on rhRLX for the management of IRI in OLT recipients are warranted. (Hepatology 2018;68:258-273).

Metabolic factors affecting hepatocellular carcinoma in steatohepatitis.

BACKGROUND & AIMS: With the rising prevalence of alcoholism, obesity and metabolic syndrome, steatohepatitis will become the leading cause of end-stage liver disease and hepatocellular carcinoma in the United States by 2025. Patients with non-alcoholic steatohepatitis and alcoholic liver disease have similar clinical and histopathological presentations, whether these similarities persist in non-alcoholic steatohepatitis and alcoholic liver disease patients with hepatocellular carcinoma remains unknown. METHODS: A retrospective analysis of the clinical features of adult patients from a large transplant center who underwent liver transplantation for steatohepatitis due to non-alcoholic steatohepatitis and alcoholic causes (alcoholic liver disease) between 1/1/02 and 1/1/12 was performed. Clinical features, explant histopathology, and clinical outcomes were compared. RESULTS: Hepatocellular carcinoma was present in 80 of 317 patients, who underwent liver transplantation for steatohepatitis with equivalent distribution in non-alcoholic steatohepatitis and alcoholic liver disease patients (24% vs 26%; P = 0.8). On multivariate analysis, significant predictors of hepatocellular carcinoma included age, ethnicity (Hispanic), and diabetes, but not BMI, hypertension or smoking. A lower risk of hepatocellular carcinoma was associated with a clinical history of hyperlipidemia. Clinical parameters were similar between patients with alcoholic liver disease - hepatocellular carcinoma and non-alcoholic steatohepatitis-hepatocellular carcinoma, except sex and presence of metabolic syndrome. non-alcoholic steatohepatitis-hepatocellular carcinoma livers retained histopathological features of non-alcoholic steatohepatitis such as ballooning and Mallory bodies, while alcoholic liver disease-hepatocellular carcinoma livers did not. There were no significant differences in hepatocellular carcinoma recurrence rates or post-transplant overall survival. CONCLUSIONS: We report the largest single-center study evaluating clinical, histopathological and outcome measures of patients undergoing liver transplantation for steatohepatitis. Older patients, diabetics, and Hispanics may warrant more frequent cancer screening due to increased risk of hepatocellular carcinoma.

Quantitative Measure of Intestinal Permeability Using Blue Food Coloring.

BACKGROUND: Loss of intestinal barrier integrity plays a fundamental role in the pathogenesis of various gastrointestinal diseases and is implicated in the onset of sepsis and multiple organ failure. An array of methods to assess different aspects of intestinal barrier function suffers from lack of sensitivity, prolonged periods of specimen collection, or high expense. We have developed a technique to measure the concentration of the food dye FD&C Blue #1 from blood and sought to assess its utility in measuring intestinal barrier function in humans. MATERIALS AND METHODS: Four healthy volunteers and 10 critically ill subjects in the intensive care unit were recruited in accordance with an institutional review board approved protocol. Subjects were given 0.5 mg/kg Blue #1 enterally as an aqueous solution of diluted food coloring. Five blood specimens were drawn per subject: 0 h (before dose), 1, 2, 4, and 8 h. After plasma isolation, organic extracts were analyzed by high-performance liquid chromatography/mass spectrometry detecting the presence of unmodified dye. RESULTS: We found no baseline detectable absorption in healthy volunteers. After including the subjects in the intensive care unit, we compared dye absorption in the six subjects who met criteria for septic shock with the eight who did not. Septic patients demonstrated significantly greater absorption of Blue #1 after 2 h. CONCLUSIONS: We have developed a novel, easy-to-use method to measure intestinal barrier integrity using a food grade dye detectable by mass spectrometry analysis of patient blood following oral administration.

Factors predicting kidney delayed graft function among recipients of simultaneous liver-kidney transplantation: A single-center experience.

BACKGROUND: Kidney delayed graft function (kDGF) remains a challenging problem following simultaneous liver and kidney transplantation (SLKT) with a reported incidence up to 40%. Given the scarcity of renal allografts, it is crucial to minimize the development of kDGF among SLKT recipients to improve patient and graft outcomes. We sought to assess the role of preoperative recipient and donor/graft factors on developing kDGF among recipients of SLKT. METHODS: A retrospective review of 194 patients who received SLKT in the period from January 2004 to March 2017 in a single center was performed to assess the effect of preoperative factors on the development of kDGF. RESULTS: Kidney delayed graft function was observed in 95 patients (49%). Multivariate analysis revealed that donor history of hypertension, cold static preservation of kidney grafts [versus using hypothermic pulsatile machine perfusion (HPMP)], donor final creatinine, physiologic MELD, and duration of delay of kidney transplantation after liver transplantation were significant independent predictors for kDGF. kDGF is associated with worse graft function and patient and graft survival. CONCLUSIONS: Kidney delayed graft function has detrimental effects on graft function and graft survival. Understanding the risks and combining careful perioperative patient management, proper recipient selection and donor matching, and graft preservation using HPMP would decrease kDGF among SLKT recipients.

Heme oxygenase-1 regulates sirtuin-1-autophagy pathway in liver transplantation: From mouse to human.

Liver ischemia-reperfusion injury (IRI) represents a major risk factor of early graft dysfunction and a key obstacle to expanding the donor pool in orthotopic liver transplantation (OLT). Although graft autophagy is essential for resistance against hepatic IRI, its significance in clinical OLT remains unknown. Despite recent data identifying heme oxygenase-1 (HO-1) as a putative autophagy inducer, its role in OLT and interactions with sirtuin-1 (SIRT1), a key autophagy regulator, have not been studied. We aimed to examine HO-1-mediated autophagy induction in human OLT and in a murine OLT model with extended (20 hours) cold storage, as well as to analyze the requirement for SIRT1 in autophagy regulation by HO-1. Fifty-one hepatic biopsy specimens from OLT patients were collected under an institutional review board protocol 2 hours after portal reperfusion, followed by Western blot analyses. High HO-1 levels correlated with well-preserved hepatocellular function and enhanced SIRT1/LC3B expression. In mice, HO-1 overexpression by genetically modified HO-1 macrophage therapy was accompanied by decreased OLT damage and increased SIRT1/LC3B expression, whereas adjunctive inhibition of SIRT1 signaling diminished HO-1-mediated hepatoprotection and autophagy induction. Our translational study confirms the clinical relevance of HO-1 cytoprotection and identifies SIRT1-mediated autophagy pathway as a new essential regulator of HO-1 function in IR-stressed OLT.

Hepatocyte transplantation: past efforts, current technology, and future expansion of therapeutic potential.

Hepatic cell transplantation (HCT) continues to garner interest as an alternative to orthotopic liver transplantation and the attendant donor shortage. When compared with solid organ transplantation, advantages of cell transplantation include the potential to treat more patients with a considerably less invasive procedure, the ability to utilize organs otherwise unsuitable for transplant, and leaving the native organ in situ with the potential for regeneration. While studies date back to the early 1960s, advancement of clinical application has been slow due in part to limitations of suitable tissue supplies and reproducible robust techniques. Compared with orthotopic liver transplantation, there are fewer absolute contraindications for donor selection. And, current techniques used to harvest, isolate, store, and even transfuse cells vary little between institutions. Significant variation is seen due to a lack of consensus with maintenance therapy. Although the ideal recipient has not been clearly identified, the most significant results have been demonstrated with correction of congenital metabolic liver disorders, with a few trials examining its utility in cirrhotics and more recently acute liver failure. The most exciting new topic of discussion examines techniques to improve engraftment, with many such as ischemic preconditioning and nonselective partial embolization (microbead therapy), while not yet used in HCT study, showing promise in solid organ research. Advancements in HCT, although slow in progress, have great potential in the ability to alleviate the burden faced in solid organ transplantation and possibly become a long-term viable option, beyond that of a bridge or salvage therapy.

Macrophage heme oxygenase-1-SIRT1-p53 axis regulates sterile inflammation in liver ischemia-reperfusion injury.

BACKGROUND & AIMS: Hepatic ischemia-reperfusion injury (IRI), characterized by exogenous antigen-independent local inflammation and hepatocellular death, represents a risk factor for acute and chronic rejection in liver transplantation. We aimed to investigate the molecular communication involved in the mechanism of liver IRI. METHODS: We analyzed human liver transplants, primary murine macrophage cell cultures and IR-stressed livers in myeloid-specific heme oxygenase-1 (HO-1) gene mutant mice, for anti-inflammatory and cytoprotective functions of macrophage-specific HO-1/SIRT1 (sirtuin 1)/p53 (tumor suppressor protein) signaling. RESULTS: Decreased HO-1 expression in human post-reperfusion liver transplant biopsies correlated with a deterioration in hepatocellular function (serum ALT; p<0.05) and inferior patient survival (p<0.05). In the low HO-1 liver transplant biopsy group, SIRT1/Arf (alternative reading frame)/p53/MDM2 (murine double minute 2) expression levels decreased (p<0.05) while cleaved caspase 3 and frequency of TUNEL+cells simultaneously increased (p<0.05). Immunofluorescence showed macrophages were the principal source of HO-1 in human and mouse IR-stressed livers. In vitro macrophage cultures revealed that HO-1 induction positively regulated SIRT1 signaling, whereas SIRT1-induced Arf inhibited ubiquitinating activity of MDM2 against p53, which in turn attenuated macrophage activation. In a murine model of hepatic warm IRI, myeloid-specific HO-1 deletion lacked SIRT1/p53, exacerbated liver inflammation and IR-hepatocellular death, whereas adjunctive SIRT1 activation restored p53 signaling and rescued livers from IR-damage. CONCLUSION: This bench-to-bedside study identifies a new class of macrophages activated via the HO-1-SIRT1-p53 signaling axis in the mechanism of hepatic sterile inflammation. This mechanism could be a target for novel therapeutic strategies in liver transplant recipients. LAY SUMMARY: Post-transplant low macrophage HO-1 expression in human liver transplants correlates with reduced hepatocellular function and survival. HO-1 regulates macrophage activation via the SIRT1-p53 signaling network and regulates hepatocellular death in liver ischemia-reperfusion injury. Thus targeting this pathway in liver transplant recipients could be of therapeutic benefit.

Avoiding Futility in Simultaneous Liver-kidney Transplantation: Analysis of 331 Consecutive Patients Listed for Dual Organ Replacement.

OBJECTIVE: We sought to evaluate outcomes and predictors of renal allograft futility (RAF-patient death or need for renal replacement therapy at 3 months) after simultaneous liver-kidney transplantation (SLKT). BACKGROUND: Model for End-Stage Liver Disease (MELD) prioritization of liver recipients with renal dysfunction has significantly increased utilization of SLKT. Data on renal outcomes after SLKT in the highest MELD recipients are scarce, as are accurate predictors of recovery of native kidney function. Without well-established listing guidelines, SLKT potentially wastes renal allografts in both high-acuity liver recipients at risk for early mortality and recipients who may regain native kidney function. METHODS: A retrospective single-center multivariate regression analysis was performed for adult patients undergoing SLKT (January 2004 to August 2014) to identify predictors of RAF. RESULTS: Of 331 patients dual-listed for SLKT, 171 (52%) expired awaiting transplant, 145 (44%) underwent SLKT, and 15 (5%) underwent liver transplantation alone. After SLKT, 39% experienced delayed graft function and 20.7% had RAF. Compared with patients without RAF, RAF recipients had greater MELD scores, length of hospitalization, intraoperative base deficit, incidence of female donors, kidney and liver donor risk indices, kidney cold ischemia, and inferior overall survival. Multivariate predictors of RAF included pretransplant dialysis duration, kidney cold ischemia, kidney donor risk index, and recipient hyperlipidemia. CONCLUSIONS: With 20% short-term loss of transplanted kidneys after SLKT, our data strongly suggest that renal transplantation should be deferred in liver recipients at high risk for RAF. Consideration for a kidney allocation variance to allow for delayed renal transplantation after liver transplantation may prevent loss of scarce renal allografts.