The Foxo1-YAP-Notch1 axis reprograms STING-mediated innate immunity in NASH progression.

Innate immune activation is critical for initiating hepatic inflammation during nonalcoholic steatohepatitis (NASH) progression. However, the mechanisms by which immunoregulatory molecules recognize lipogenic, fibrotic, and inflammatory signals remain unclear. Here, we show that high-fat diet (HFD)-induced oxidative stress activates Foxo1, YAP, and Notch1 signaling in hepatic macrophages. Macrophage Foxo1 deficiency (Foxo1M-KO) ameliorated hepatic inflammation, steatosis, and fibrosis, with reduced STING, TBK1, and NF-κB activation in HFD-challenged livers. However, Foxo1 and YAP double knockout (Foxo1/YAPM-DKO) or Foxo1 and Notch1 double knockout (Foxo1/Notch1M-DKO) promoted STING function and exacerbated HFD-induced liver injury. Interestingly, Foxo1M-KO strongly reduced TGF-ß1 release from palmitic acid (PA)- and oleic acid (OA)-stimulated Kupffer cells and decreased Col1α1, CCL2, and Timp1 expression but increased MMP1 expression in primary hepatic stellate cells (HSCs) after coculture with Kupffer cells. Notably, PA and OA challenge in Kupffer cells augmented LIMD1 and LATS1 colocalization and interaction, which induced YAP nuclear translocation. Foxo1M-KO activated PGC-1α and increased nuclear YAP activity, modulating mitochondrial biogenesis. Using chromatin immunoprecipitation (ChIP) coupled with massively parallel sequencing (ChIP-Seq) and in situ RNA hybridization, we found that NICD colocalizes with YAP and targets Mb21d1 (cGAS), while YAP functions as a novel coactivator of the NICD, which is crucial for reprogramming STING function in NASH progression. These findings highlight the importance of the macrophage Foxo1-YAP-Notch1 axis as a key molecular regulator that controls lipid metabolism, inflammation, and innate immunity in NASH.

Intestinal Re-Transplantation.

The history of intestinal transplantation can be traced back to the turn of the twentieth century. Although advancements have been made, the intestine still presents a greater challenge to transplantation than does that of other solid organs, experiencing higher rates of graft rejection and lower long-term survival. Increasingly, intestinal re-transplantation (re-ITx) is seen as a viable option and is now the fourth most common indication for ITx. Changes to immunosuppression protocols, technical modifications, and infectious disease monitoring have contributed to improved outcomes. The authors review the literature on re-ITx in regard to the history, management considerations, and future directions.

Cold stress-induced ferroptosis in liver sinusoidal endothelial cells determines liver transplant injury and outcomes.

Although cold preservation remains the gold standard in organ transplantation, cold stress-induced cellular injury is a significant problem in clinical orthotopic liver transplantation (OLT). Because a recent study showed that cold stress activates ferroptosis, a form of regulated cell death, we investigated whether and how ferroptosis determines OLT outcomes in mice and humans. Treatment with ferroptosis inhibitor (ferrostatin-1) during cold preservation reduced lipid peroxidation (malondialdehyde; MDA), primarily in liver sinusoidal endothelial cells (LSECs), and alleviated ischemia/reperfusion injury in mouse OLT. Similarly, ferrostatin-1 reduced cell death in cold-stressed LSEC cultures. LSECs deficient in nuclear factor erythroid 2-related factor 2 (NRF2), a critical regulator of ferroptosis, were susceptible to cold stress-induced cell death, concomitant with enhanced endoplasmic reticulum (ER) stress and expression of mitochondrial Ca2+ uptake regulator (MICU1). Indeed, supplementing MICU1 inhibitor reduced ER stress, MDA expression, and cell death in NRF2-deficient but not WT LSECs, suggesting NRF2 is a critical regulator of MICU1-mediated ferroptosis. Consistent with murine data, enhanced liver NRF2 expression reduced MDA levels, hepatocellular damage, and incidence of early allograft dysfunction in human OLT recipients. This translational study provides a clinically applicable strategy in which inhibition of ferroptosis during liver cold preservation mitigates OLT injury by protecting LSECs from peritransplant stress via an NRF2-regulatory mechanism.

SIRT1 regulates hepatocyte programmed cell death via GSDME - IL18 axis in human and mouse liver transplantation.

Sirtuin 1 (SIRT1) is a histone/protein deacetylase in the cellular response to inflammatory, metabolic, and oxidative stressors. We previously reported that myeloid SIRT1 regulates the inflamed liver's canonical pyroptosis cell death pathway. However, whether/how hepatocyte SIRT1 is engaged in programmed cell death in the cold-stressed liver remains uncertain. Here, we undertook translational studies in human and mouse orthotopic liver transplantation (OLT) to interrogate the significance of hepatocyte-specific SIRT1 in cold-stored donor livers and liver grafts after reperfusion. In the clinical arm of sixty human OLT patients, hepatic SIRT1 levels in cold-preserved donor livers correlated with the anti-apoptotic Bcl-2 expression. After reperfusion, improved OLT function was accompanied by hepatic SIRT1 levels negatively associated with cleaved caspase-3 expression. In the experimental arm, we compared FLOX-control with hepatocyte-specific SIRT1-KO livers after orthotopic transplantation into WT mouse recipients, parallel with primary murine hepatocyte cultures subjected to cold activation with/without knockdown of SIRT1, GSDME, and IL18Rß. Indeed, hepatocyte SIRT1 deficiency upregulated apoptosis and GSDME-mediated programmed cell death, deteriorating hepatocellular function and shortening OLT survival. Augmented GSDME processing, accompanied by increased secretion of IL18 by stressed hepatocytes, was prominent in SIRT1-deficient, cold-stored livers. Hepatocyte SIRT1 expression regulated anti-apoptotic Bcl-2/XIAP proteins, suppressed cold stress-triggered apoptosis, and mitigated GSDME licensing to release IL18. Notably, consistent with the ability of IL18 to depress hepatocyte SIRT1 and Bcl-2/XIAP in vitro, IL18 neutralization in vivo prevented hepatocellular damage and restored the anti-apoptotic phenotype in otherwise injury-prone SIRT1-deficient OLTs. In conclusion, this translational study identifies a novel hepatocyte SIRT1-IL18 molecular circuit as a therapeutic target in the mechanism underpinning hepatocyte death pathways in human and mouse liver transplantation.

Macrophage RIPK3 triggers inflammation and cell death via the XBP1-Foxo1 axis in liver ischaemia-reperfusion injury.

Background & Aims: Receptor-interacting serine/threonine-protein kinase 3 (RIPK3) is a central player in triggering necroptotic cell death. However, whether macrophage RIPK3 may regulate NOD1-dependent inflammation and calcineurin/transient receptor potential cation channel subfamily M member 7 (TRPM7)-induced hepatocyte death in oxidative stress-induced liver inflammatory injury remains elusive. Methods: A mouse model of hepatic ischaemia-reperfusion (IR) injury, the primary hepatocytes, and bone marrow-derived macrophages were used in the myeloid-specific RIPK3 knockout (RIPK3M-KO) and RIPK3-proficient (RIPK3FL/FL) mice. Results: RIPK3M-KO diminished IR stress-induced liver damage with reduced serum alanine aminotransferase/aspartate aminotransferase levels, macrophage/neutrophil infiltration, and pro-inflammatory mediators compared with the RIPK3FL/FL controls. IR stress activated RIPK3, inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α), x-box binding protein 1 (XBP1), nucleotide-binding oligomerisation domain-containing protein 1 (NOD1), NF-κB, forkhead box O1 (Foxo1), calcineurin A, and TRPM7 in ischaemic livers. Conversely, RIPK3M-KO depressed IRE1α, XBP1, NOD1, calcineurin A, and TRPM7 activation with reduced serum tumour necrosis factor α (TNF-α) levels. Moreover, Foxo1M-KO alleviated IR-induced liver injury with reduced NOD1 and TRPM7 expression. Interestingly, chromatin immunoprecipitation coupled with massively parallel sequencing revealed that macrophage Foxo1 colocalised with XBP1 and activated its target gene Zc3h15 (zinc finger CCCH domain-containing protein 15). Activating macrophage XBP1 enhanced Zc3h15, NOD1, and NF-κB activity. However, disruption of macrophage Zc3h15 inhibited NOD1 and hepatocyte calcineurin/TRPM7 activation, with reduced reactive oxygen species production and lactate dehydrogenase release after macrophage/hepatocyte coculture. Furthermore, adoptive transfer of Zc3h15-expressing macrophages in RIPK3M-KO mice augmented IR-triggered liver inflammation and cell death. Conclusions: Macrophage RIPK3 activates the IRE1α-XBP1 pathway and Foxo1 signalling in IR-stress livers. The XBP1-Foxo1 interaction is essential for modulating target gene Zc3h15 function, which is crucial for the control of NOD1 and calcineurin-mediated TRPM7 activation. XBP1 functions as a transcriptional coactivator of Foxo1 in regulating NOD1-driven liver inflammation and calcineurin/TRPM7-induced cell death. Our findings underscore a novel role of macrophage RIPK3 in stress-induced liver inflammation and cell death, implying the potential therapeutic targets in liver inflammatory diseases. Impact and implications: Macrophage RIPK3 promotes NOD1-dependent inflammation and calcineurin/TRPM7-induced cell death cascade by triggering the XBP1-Foxo1 axis and its target gene Zc3h15, which is crucial for activating NOD1 and calcineurin/TRPM7 function, implying the potential therapeutic targets in stress-induced liver inflammatory injury.

The macrophage STING-YAP axis controls hepatic steatosis by promoting the autophagic degradation of lipid droplets.

BACKGROUND AND AIMS: The hallmark of NAFLD or hepatic steatosis is characterized by lipid droplet (LD) accumulation in hepatocytes. Autophagy may have profound effects on lipid metabolism and innate immune response. However, how innate immune activation may regulate the autophagic degradation of intracellular LDs remains elusive. APPROACH AND RESULTS: A mouse model of a high-fat diet-induced NASH was used in the myeloid-specific stimulator of interferon genes (STING) knockout or STING/yes-associated protein (YAP) double knockout mice. Liver injury, lipid accumulation, lipid droplet proteins, autophagic genes, chromatin immunoprecipitation coupled with massively parallel sequencing, and RNA-Seq were assessed in vivo and in vitro . We found that high-fat diet-induced oxidative stress activates STING and YAP pathways in hepatic macrophages. The acrophage STING deficiency (myeloid-specific STING knockout) enhances nuclear YAP activity, reduces lipid accumulation, and increases autophagy-related proteins ATG5, ATG7, and light chain 3B but diminishes LD protein perilipin 2 expression. However, disruption of STING and YAP (myeloid STING and YAP double knockout) increases serum alanine aminotransferase and triglyceride levels and reduces ß-fatty acid oxidation gene expression but augments perilipin 2 levels, exacerbating high-fat diet-induced lipid deposition. Chromatin immunoprecipitation coupled with massively parallel sequencing reveals that macrophage YAP targets transmembrane protein 205 and activates AMP-activated protein kinase α, which interacts with hepatocyte mitofusin 2 and induces protein disulfide isomerase activation. Protein disulfide isomerase activates hypoxia-inducible factor-1α signaling, increases autophagosome colocalization with LDs, and promotes the degradation of perilipin 2 by interacting with chaperone-mediated autophagy chaperone HSC70. CONCLUSIONS: The macrophage STING-YAP axis controls hepatic steatosis by reprogramming lipid metabolism in a transmembrane protein 205/mitofusin 2/protein disulfide isomerase-dependent pathway. These findings highlight the regulatory mechanism of the macrophage STING-driven YAP activity on lipid control.

Simultaneous vs Staged Cardiac Intervention in High-Acuity Liver Transplant.

This cohort study examines mortality, survival, and other outcomes among adults who underwent combined cardiac surgery and liver transplant, coronary revascularization prior to liver transplant, or isolated liver transplant.

Alternative splicing of CEACAM1 by hypoxia-inducible factor-1α enhances tolerance to hepatic ischemia in mice and humans.

Although alternative splicing (AS) drives transcriptional responses and cellular adaptation to environmental stresses, its contributions in organ transplantation have not been appreciated. We have shown that carcinoembryonic antigen-related cell adhesion molecule (Ceacam1; CD66a), a transmembrane biliary glycoprotein expressed in epithelial, endothelial, and immune cells, determines donor liver transplant quality. Here, we studied how AS of Ceacam1 affects ischemia-reperfusion injury (IRI) in mouse and human livers. We found that the short cytoplasmic isoform Ceacam1-S increased during early acute and late resolution phases of warm IRI injury in mice. Transfection of Ceacam1-deficient mouse hepatocytes with adenoviral Ceacam1-S mitigated hypoxia-induced loss of cellular adhesion by repressing the Ask1/p-p38 cell death pathway. Nucleic acid-blocking morpholinos, designed to selectively induce Ceacam1-S, protected hepatocyte cultures against temperature-induced stress in vitro. Luciferase and chromatin immunoprecipitation assays identified direct binding of hypoxia-inducible factor-1α (Hif-1α) to the mouse polypyrimidine tract binding protein 1 (Ptbp1) promoter region. Dimethyloxalylglycine protected mouse livers from warm IR stress and hepatocellular damage by inhibiting prolyl hydroxylase domain-containing protein 1 and promoting AS of Ceacam1-S. Last, analysis of 46 human donor liver grafts revealed that CEACAM1-S positively correlated with pretransplant HIF1A expression. This also correlated with better transplant outcomes, including reduced TIMP1, total bilirubin, proinflammatory MCP1, CXCL10 cytokines, immune activation markers IL17A, and incidence of delayed complications from biliary anastomosis. This translational study identified mouse Hif-1α-controlled AS of Ceacam1, through transcriptional regulation of Ptbp1 promoter region, as a functional underpinning of hepatoprotection against IR stress and tissue damage in liver transplantation.

SIRT1 Regulates Hepatocyte Programmed Cell Death via GSDME - IL18 Axis in Human and Mouse Liver Transplantation.

Sirtuin 1 (SIRT1) is a histone/protein deacetylase involved in cellular senescence, inflammation, and stress resistance. We previously reported that myeloid SIRT1 signaling regulates the inflamed liver's canonical pyroptosis cell death pathway. However, whether/how hepatocyte SIRT1 is engaged in programmed cell death in the cold-stressed liver remains uncertain. Here, we undertook translational studies in human and mouse orthotopic liver transplantation (OLT) to interrogate the significance of hepatocyte-specific SIRT1 signaling in cold-stored donor livers and liver grafts after reperfusion. In the clinical arm of sixty human OLT patients, hepatic SIRT1 levels in cold-preserved donor livers correlated with anti-apoptotic Bcl-2 expression. After reperfusion, improved OLT function was accompanied by hepatic SIRT1 levels negatively associated with cleaved caspase-3 expression. In the experimental arm, we compared FLOX-control with hepatocyte-specific SIRT1-KO livers after orthotopic transplantation into WT mouse recipients, parallel with primary murine hepatocyte cultures subjected to cold activation with/without knockdown of SIRT1, GSDME, and IL18Rß signaling. Hepatocyte SIRT1 deficiency upregulated apoptosis and GSDME-mediated programmed cell death, which in turn deteriorated the hepatocellular function and shortened OLT survival. Augmented GSDME processing, accompanied by increased secretion of IL18 by stressed hepatocytes, was prominent in SIRT1-deficient, cold-stored livers. Hepatocyte SIRT1 signaling regulated anti-apoptotic Bcl-2/XIAP proteins, suppressed cold stress-triggered apoptosis, and mitigated GSDME licensing to release IL18. Notably, while crosslinking IL18R depressed SIRT1 and Bcl-2/XIAP signaling in vitro, IL18 neutralization in vivo prevented hepatocellular damage and restored the anti-apoptotic phenotype in otherwise injury-prone SIRT1-deficient OLTs. In conclusion, this translational study identifies a novel hepatocyte SIRT1-IL18 signaling circuit as a therapeutic target in the mechanism underpinning hepatocyte death in human and mouse liver transplantation.

T Cell CEACAM1-TIM-3 Crosstalk Alleviates Liver Transplant Injury in Mice and Humans.

BACKGROUND & AIMS: Carcinoembryonic antigen-related cell adhesion molecule 1 (CC1) acts through homophilic and heterophilic interactions with T cell immunoglobulin domain and mucin domain-containing protein 3 (TIM-3), which regulates innate immune activation in orthotopic liver transplantation (OLT). We investigated whether cluster of differentiation (CD) 4+ T cell-dependent CC1-TIM-3 crosstalk may affect OLT outcomes in mice and humans. METHODS: Wild-type (WT) and CC1-deficient (CC1 knock-out [KO]) mouse livers were transplanted into WT, CC1KO, or T-cell TIM-3 transgenic (TIM-3Tg)/CC1KO double-mutant recipients. CD4+ T cells were adoptively transferred into T/B cell-deficient recombination activating gene 2 protein (Rag2) KO recipients, followed by OLT. The perioperative liver-associated CC1 increase was analyzed in 50 OLT patients. RESULTS: OLT injury in WT livers deteriorated in CC1KO compared with CC1-proficient (WT) recipients. The frequency of TIM-3+CD4+ T cells was higher in WT than CC1KO hosts. Reconstitution of Rag2KO mice with CC1KO-T cells increased nuclear factor (NF)-κB phosphorylation and OLT damage compared with recipients repopulated with WT T cells. T-cell TIM-3 enhancement in CC1KO recipients (WT â†’ TIM3Tg/CC1KO) suppressed NF-κB phosphorylation in Kupffer cells and mitigated OLT injury. However, TIM-3-mediated protection was lost by pharmacologic TIM-3 blockade or an absence of CC1 in the donor liver (CC1KO â†’ TIM-3Tg/CC1KO). The perioperative CC1 increase in human OLT reduced hepatocellular injury, early allograft dysfunction, and the cumulative rejection rate. CONCLUSIONS: This translational study identifies T cell-specific CC1 signaling as a therapeutic means to alleviate OLT injury by promoting T cell-intrinsic TIM-3, which in turn interacts with liver-associated CC1 to suppress NF-κB in Kupffer cells. By suppressing peritransplant liver damage, promoting T-cell homeostasis, and improving OLT outcomes, recipient CC1 signaling serves as a novel cytoprotective sentinel.

The Evolution of Redo Liver Transplantation Over 35 Years: Analysis of 654 Consecutive Adult Liver Retransplants at a Single Center.

OBJECTIVE: To examine liver retransplantation (ReLT) over 35 years at a single center. BACKGROUND: Despite the durability of liver transplantation (LT), graft failure affects up to 40% of LT recipients. METHODS: All adult ReLTs from 1984 to 2021 were analyzed. Comparisons were made between ReLTs in the pre versus post-model for end-stage liver disease (MELD) eras and between ReLTs and primary-LTs in the modern era. Multivariate analysis was used for prognostic modeling. RESULTS: Six hundred fifty-four ReLTs were performed in 590 recipients. There were 372 pre-MELD ReLTs and 282 post-MELD ReLTs. Of the ReLT recipients, 89% had one previous LT, whereas 11% had ≥2. Primary nonfunction was the most common indication in the pre-MELD era (33%) versus recurrent disease (24%) in the post-MELD era. Post-MELD ReLT recipients were older (53 vs 48, P = 0.001), had higher MELD scores (35 vs 31, P = 0.01), and had more comorbidities. However, post-MELD ReLT patients had superior 1, 5, and 10-year survival compared with pre-MELD ReLT (75%, 60%, and 43% vs 53%, 43%, and 35%, respectively, P < 0.001) and lower in-hospital mortality and rejection rates. Notably, in the post-MELD era, the MELD score did not affect survival. We identified the following risk factors for early mortality (≤12 months after ReLT): coronary artery disease, obesity, ventilatory support, older recipient age, and longer pre-ReLT hospital stay. CONCLUSIONS: This represents the largest single-center ReLT report to date. Despite the increased acuity and complexity of ReLT patients, post-MELD era outcomes have improved. With careful patient selection, these results support the efficacy and survival benefit of ReLT in an acuity-based allocation environment.

Implications of Pleural Fluid Composition in Persistent Pleural Effusion following Orthotopic Liver Transplant.

Persistent pleural effusions (PPEf) represent a known complication of orthotopic liver transplant (OLT). However, their clinical relevance is not well described. We evaluated the clinical, biochemical, and cellular characteristics of post-OLT PPEf and assessed their relationship with longitudinal outcomes. We performed a retrospective cohort study of OLT recipients between 2006 and 2015. Included patients had post-OLT PPEf, defined by effusion persisting >30 days after OLT and available pleural fluid analysis. PPEf were classified as transudates or exudates (ExudLight) by Light's criteria. Exudates were subclassified as those with elevated lactate dehydrogenase (ExudLDH) or elevated protein (ExudProt). Cellular composition was classified as neutrophil- or lymphocyte-predominant. Of 1602 OLT patients, 124 (7.7%) had PPEf, of which 90.2% were ExudLight. Compared to all OLT recipients, PPEf patients had lower two-year survival (HR 1.63; p = 0.002). Among PPEf patients, one-year mortality was associated with pleural fluid RBC count (p = 0.03). While ExudLight and ExudProt showed no association with outcomes, ExudLDH were associated with increased ventilator dependence (p = 0.03) and postoperative length of stay (p = 0.03). Neutrophil-predominant effusions were associated with increased postoperative ventilator dependence (p = 0.03), vasopressor dependence (p = 0.02), and surgical pleural intervention (p = 0.02). In summary, post-OLT PPEf were associated with increased mortality. Ninety percent of these effusions were exudates by Light's criteria. Defining exudates using LDH only and incorporating cellular analysis, including neutrophils and RBCs, was useful in predicting morbidity.

Neutrophil CEACAM1 determines susceptibility to NETosis by regulating the S1PR2/S1PR3 axis in liver transplantation.

Neutrophils, the largest innate immune cell population in humans, are the primary proinflammatory sentinel in the ischemia-reperfusion injury (IRI) mechanism in orthotopic liver transplantation (OLT). Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CC1, or CD66a) is essential in neutrophil activation and serves as a checkpoint regulator of innate immune-driven IRI cascade in OLT. Although CC1 alternative splicing generates two functionally distinct short and long cytoplasmic isoforms, their role in neutrophil activation remains unknown. Here, we undertook molecular and functional studies to interrogate the significance of neutrophil CC1 signaling in mouse and human OLT recipients. In the experimental arm, we employed a mouse OLT model to document that ablation of recipient-derived neutrophil CC1-long (CC1-L) isotype aggravated hepatic IRI by promoting neutrophil extracellular traps (NETs). Notably, by regulating the S1P-S1PR2/S1PR3 axis, neutrophil CC1-L determined susceptibility to NET formation via autophagy signaling. In the clinical arm, liver grafts from 55 transplant patients selectively enriched for neutrophil CC1-L showed relative resistance to ischemia-reperfusion (IR) stress/tissue damage, improved hepatocellular function, and clinical outcomes. In conclusion, despite neutrophils being considered a principal villain in peritransplant tissue injury, their CC1-L isoform may serve as a regulator of IR stress resistance/NETosis in human and mouse OLT recipients.

Recipient TIM4 signaling regulates ischemia reperfusion-induced ER stress and metabolic responses in liver transplantation: from mouse-to-human.

T-cell immunoglobulin and mucin (Tim)4 is expressed on APCs, including macrophages, as one of the main amplifiers in the mechanism of liver ischemia-reperfusion injury (IRI) following orthotopic liver transplantation (OLT). Though donor Tim4 selectively expressed on Kupffer cells serves as a checkpoint regulator of innate immune-driven IRI cascades, its role on cells outside the OLT remains unclear. To dissect the role of donor vs. recipient-specific Tim4 signaling in IR-induced stress and hepatocellular function, we employed a murine OLT model utilizing Tim4-knockout (KO) mice as either donor or recipient (WT → WT, WT → Tim4-KO, Tim4-KO → WT). In the experimental arm, disruption of donor Tim4 attenuated IRI-OLT damage, while recipient Tim4-null mutation aggravated hepatic IRI concomitant with disturbed lipid metabolism, enhanced endoplasmic reticulum stress, and activated pro-apoptotic signaling in the grafts. In the in vitro study, murine hepatocytes co-cultured with Tim4-null adipose tissue showed enhanced C/EBP homologous protein (CHOP) expression pattern and susceptibility to hepatocellular death accompanied by activated caspase cascade in response to TNF-α stimulation. In the clinical arm, liver grafts from forty-one transplant patients with enhanced TIM4 expression showed higher body mass index, augmented hepatic endoplasmic reticulum stress, enhanced pro-apoptotic markers, upregulated innate/adaptive immune responses, exacerbated hepatocellular damage, and inferior graft survival. In conclusion, although TIM4 is considered a principal villain in peri-transplant early tissue injury, recipient TIM4 signaling may serve as a savior of IR-triggered metabolic stress in mouse and human OLT recipients.

Novel role of macrophage TXNIP-mediated CYLD-NRF2-OASL1 axis in stress-induced liver inflammation and cell death.

Background & Aims: The stimulator of interferon genes (STING)/TANK-binding kinase 1 (TBK1) pathway is vital in mediating innate immune and inflammatory responses during oxidative/endoplasmic reticulum (ER) stress. However, it remains unknown whether macrophage thioredoxin-interacting protein (TXNIP) may regulate TBK1 function and cell death pathways during oxidative/ER stress. Methods: A mouse model of hepatic ischaemia/reperfusion injury (IRI), the primary hepatocytes, and bone marrow-derived macrophages were used in the myeloid-specific TXNIP knockout (TXNIPM-KO) and TXNIP-proficient (TXNIPFL/FL) mice. Results: The TXNIPM-KO mice were resistant to ischaemia/reperfusion (IR) stress-induced liver damage with reduced serum alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels, macrophage/neutrophil infiltration, and pro-inflammatory mediators compared with the TXNIPFL/FL controls. IR stress increased TXNIP, p-STING, and p-TBK1 expression in ischaemic livers. However, TXNIPM-KO inhibited STING, TBK1, interferon regulatory factor 3 (IRF3), and NF-κB activation with interferon-ß (IFN-ß) expression. Interestingly, TXNIPM-KO augmented nuclear factor (erythroid-derived 2)-like 2 (NRF2) activity, increased antioxidant gene expression, and reduced macrophage reactive oxygen species (ROS) production and hepatic apoptosis/necroptosis in IR-stressed livers. Mechanistically, macrophage TXNIP deficiency promoted cylindromatosis (CYLD), which colocalised and interacted with NADPH oxidase 4 (NOX4) to enhance NRF2 activity by deubiquitinating NOX4. Disruption of macrophage NRF2 or its target gene 2',5' oligoadenylate synthetase-like 1 (OASL1) enhanced Ras GTPase-activating protein-binding protein 1 (G3BP1) and TBK1-mediated inflammatory response. Notably, macrophage OASL1 deficiency induced hepatocyte apoptotic peptidase activating factor 1 (APAF1), cytochrome c, and caspase-9 activation, leading to increased caspase-3-initiated apoptosis and receptor-interacting serine/threonine-protein kinase 3 (RIPK3)-mediated necroptosis. Conclusions: Macrophage TXNIP deficiency enhances CYLD activity and activates the NRF2-OASL1 signalling, controlling IR stress-induced liver injury. The target gene OASL1 regulated by NRF2 is crucial for modulating STING-mediated TBK1 activation and Apaf1/cytochrome c/caspase-9-triggered apoptotic/necroptotic cell death pathway. Our findings underscore a novel role of macrophage TXNIP-mediated CYLD-NRF2-OASL1 axis in stress-induced liver inflammation and cell death, implying the potential therapeutic targets in liver inflammatory diseases. Lay summary: Liver inflammation and injury induced by ischaemia and reperfusion (the absence of blood flow to the liver tissue followed by the resupply of blood) is a significant cause of hepatic dysfunction and failure following liver transplantation, resection, and haemorrhagic shock. Herein, we uncover an underlying mechanism that contributes to liver inflammation and cell death in this setting and could be a therapeutic target in stress-induced liver inflammatory injury.

Use of a self-expanding transcatheter valve for a degenerated INTUITY valve.

Valve-in-valve transcatheter aortic valve replacement for degenerated surgical bioprosthesis is becoming a more common therapeutic option. Rapid-deployment valves are novel, have distinct structural differences from standard surgical valves, and are increasingly used in minimal-access surgery. We report the case of a 61-year-old man who developed severe stenosis of an Edwards INTUITY Elite rapid-deployment valve and who subsequently underwent successful valve-in-valve placement of a self-expanding transcatheter valve. To our knowledge, this is the first description of the technical aspects of and considerations for using the self-expanding transcatheter platform in the Edwards INTUITY Elite valve.

Postoperative Trapped Lung After Orthotopic Liver Transplantation is a Predictor of Increased Mortality.

Pleural effusions are a common complication of orthotopic liver transplantation (OLT), and chronic post-OLT pleural effusions have been associated with worse outcomes. Furthermore, "trapped lung" (TL), defined as a restrictive fibrous visceral pleural peel preventing lung re-expansion, may have prognostic significance. We performed a retrospective analysis of adult OLT recipients over a 9-year period at UCLA Medical Center. Post-OLT patients with persistent pleural effusions, defined by the presence of pleural fluid requiring drainage one to 12 months after OLT, were included for analysis. Outcomes for patients with and without TL were compared using univariate and multivariate analysis. Of the 1722 patients who underwent OLT, 117 (7%) patients met our criteria for persistent postoperative pleural effusion, and the incidence of TL was 21.4% (25/117). Compared to patients without TL, those with TL required more surgical pleural procedures (OR 59.8, 95%CI 19.7-181.4, p < 0.001), spent more days in the hospital (IRR 1.56, 95%CI 1.09-2.23, p = 0.015), and had a higher risk of mortality (HR 2.47, 95%CI 1.59-3.82, p < 0.001) following transplant. In sum, we found that post-OLT TL was associated with higher morbidity, mortality, and healthcare utilization. Future prospective investigation is warranted to further clarify the risk factors for developing postoperative pleural effusions and TL.

Operational tolerance is not always permanent: A 10-year prospective study in pediatric liver transplantation recipients.

Immunosuppression withdrawal can be safely performed in select liver transplantation recipients, but the long-term outcomes and sustainability of tolerance have not been well studied. We completed a 10-year prospective, observational study of 18 pediatric liver transplantation recipients with operational tolerance to (1) assess the sustainability of tolerance over time, (2) compare the clinical characteristics of patients who maintained versus lost tolerance, (3) characterize liver histopathology findings in surveillance liver biopsies; and (4) describe immunologic markers in patients with tolerance. Comparator patients from two clinical phenotype groups termed "stable" and "nontolerant" patients were used as controls. Of the 18 patients with operational tolerance, the majority of patients were males (n = 14, 78%) who were transplanted for cholestatic liver disease (n = 12, 67%). Median age at transplantation was 1.9 (range, 0.6-8) years. Median time after transplantation that immunosuppression had been discontinued was 13.1 (range, 2.9-22.1) years. As many as 11 (61%) maintained tolerance for a median of 10.4 (range, 1.9-22.1) years, whereas 7 (39%) lost tolerance after a median of 3.2 (range, 1.5-18.6) years. Populations of T regulatory cells (%CD4+ CD25hi CD127lo ) were significantly higher in patients with tolerance (p = 0.02). Our results emphasize that spontaneous operational tolerance is a dynamic and nonpermanent state. It is therefore essential for patients who are clinically stable off immunosuppression to undergo regular follow-up and laboratory monitoring, as well as surveillance biopsies to rule out subclinical rejection.

Barriers for Liver Transplant in Patients with Alcohol-Related Hepatitis.

BACKGROUND: Liver transplantation (LT) for alcohol-related liver disease has historically been reserved for patients who have been six months abstinent. Given the increasing incidence of alcohol-related hepatitis (AH) and dismal survival in patients who fail medical therapy, transplant centers are extending their acceptance criteria for patients with less than 6 months of sobriety. We sought to determine the barriers for listing. METHODS: We conducted a retrospective chart review of all inpatient LT referrals for a diagnosis of AH between September 2019 and December 2020. LT evaluations were performed by a multidisciplinary team. Descriptive statistics were reported using mean and standard deviation (SD) or percentage where appropriate. RESULTS: During our study period, 82 patients were evaluated for LT. Of these 82 patients, 62 were declined for liver transplantation. The mean (SD) age of the 62-patient cohort was 44 years (10.7), and most patients were men. The mean (SD) number of reasons for denial was 2 (0.97). Four patients had medical contraindications for transplant. Twenty-seven (44%) and 35 (56%) patients lacked insight and were at risk of alcohol relapse, respectively. Forty-three (69%) and fourteen (22.5%) patients had insufficient social support and an inability to maintain a therapeutic relationship with the transplant team, respectively. CONCLUSION: Patients are more likely denied for psychosocial factors than medical comorbidities. The majority were due to lack of insight, insufficient social support, and inability to maintain a therapeutic relationship with the transplant team. Resources should be allocated to address these issues.