Pathophysiological mechanisms of cell death affecting graft survival in liver transplantation

Abstract

Early allograft dysfunction (EAD) is a significant complication of liver transplantation (LT). LT remains the sole curative treatment for patients with end-stage liver disease. EAD is correlated with heightened morbidity, extended stays in intensive care units, and decreased graft survival rates. Within the clinical practice, EAD presents a substantial challenge, necessitating vigilant monitoring, heightened clinical awareness, and prompt multidisciplinary intervention to prevent progression to primary graft nonfunction and multiorgan failure. Multiple forms of programmed cell death, including necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis, autophagy, PANoptosis, and NETosis, have been implicated in graft injury. Apoptosis facilitates the regulated elimination of damaged or senescent hepatocytes via caspase-dependent pathways, whereas necroptosis and other necrotic mechanisms exacerbate caspase-independent tissue injury through membrane disruption and the release of inflammatory mediators. Pyroptosis, driven by inflammasome activation and gasdermin-mediated pore formation, further amplifies inflammatory signaling within the graft. Moreover, ferroptosis, characterized by iron-dependent lipid peroxidation, has emerged as a pivotal contributor to hepatocellular injury during hepatic ischemia–reperfusion events. Failure of hepatocellular protective mechanisms to adequately counteract energy depletion and oxidative stress during ischemia results in cell death, which subsequently activates immune and contributing to acute graft rejection.

Key Words: Liver transplantation; Early allograft dysfunction; Hepatic ischemia-reperfusion injury; Cell death; Graft injury; Hepatocellular damage pathways

Core Tip: The incidence of end-stage liver disease and its associated mortality have increased substantially in recent years, with liver transplantation remaining the sole definitive therapeutic intervention for affected patients. Hepatic ischemia-reperfusion injury is implicated strongly in early allograft dysfunction (EAD), increased postoperative complications, and unfavorable long-term prognoses. It affects nearly all grafts to varying extents, with the severity of injury being correlated with elevated morbidity, primary graft dysfunction, and potential graft loss. The prevention and immediate recognition of EAD, along with a thorough understanding of its pathophysiological processes, are crucial for optimal transplant function.

INTRODUCTION

Liver transplantation (LT) has emerged as the preferred life-saving intervention for patients with end-stage liver disease and certain malignancies. Nevertheless, graft survival continues to pose a considerable challenge because of stresses associated with the transplantation process. These stresses include cold preservation following organ procurement and during transportation, as well as warm ischemia occurring until vascular reconstitution, both of which can induce hepatocellular death[1]. Warm ischemia is common in clinical scenarios such as liver resection, hemorrhagic shock, trauma, cardiac arrest, or hepatic sinusoidal obstruction syndrome, where vascular occlusion impedes normal hepatic blood flow. In contrast, cold ischemia is specific to LT and results from the preservation of the donor liver graft in a hypothermic environment prior to reperfusion at normothermic temperatures[2]. An extended duration of cold ischemia prior to LT utilizing static cold storage preservation has been correlated with an increased incidence of ischemia-related complications. The advent of normothermic machine perfusion (NMP) has been associated with a reduction in the overall occurrence of early allograft dysfunction (EAD) and biliary complications[3]. Maintaining intraoperative hemodynamic stability is advantageous. Notably, elevated fluid balance and the administration of higher doses of vasopressors have not been linked to an increased risk of EAD within seven days or primary graft nonfunction following LT[4]. Additionally, dextran-40 exhibits rheological and antithrombotic properties that may influence the modulation of EAD[5].

Hepatic ischemia-reperfusion injury (HIRI) represents a critical complication in liver surgery and LT, as it induces oxidative stress and inflammatory responses that significantly contribute to compromised graft function and adverse clinical outcomes. A fundamental aspect of HIRI is the degradation of the endothelial glycocalyx, which leads to microcirculatory dysfunction[6-8]. When hepatocellular protective mechanisms fail to adequately counterbalance energy depletion and oxidative stress during ischemia, cell death ensues. The resulting tissue damage triggers the release of damage-associated molecular patterns (DAMPs), which recruit and activate immune cells such as neutrophils and monocytes, thereby orchestrating the initiation, progression, and resolution of sterile inflammation[9].

The application of NMP has been shown to preserve the glycocalyx, thereby mitigating the effects of HIRI on graft function and reducing postoperative complications[6]. Additionally, ischemia-free LT has been demonstrated to attenuate liver transplant-related injury[10]. Machine perfusion is transforming LT by converting preservation from a passive storage process into an active, physiologically based intervention[7,11,12]. Liver X receptor alpha (LXRα) has been identified as a key regulator of the inflammatory immune response elicited by HIRI and acute rejection. M1 macrophage polarization contributes to the pathogenesis and progression of acute rejection. Although LXR activation is known to have anti-inflammatory effects, the specific role of LXRα in acute rejection following LT remains to be fully elucidated[13].

Despite recent advancements in LT, several challenges persist, including donor-recipient matching, and organ allocation. The advent of artificial intelligence (AI), particularly large language models, has introduced novel applications within the field of LT. Current research highlights the utility of AI across diverse domains, encompassing clinical practice, research, and education. The integration of AI can increase the efficiency for healthcare professionals by reducing the time spent on nonclinical tasks and can also benefit liver transplant recipients, thereby providing accurate and accessible information[14,15].

Graft rejection, primarily driven by major histocompatibility complex mismatches, remains a significant obstacle. Although contemporary immunosuppressive therapies have substantially decreased the incidence and severity of rejection, they have not eradicated it entirely. Autophagy, an evolutionarily conserved cellular process in eukaryotes, mediates autophagocytosis and confers cytoprotection. This process is regulated by autophagy-related genes and their encoded protein families, which maintain cellular homeostasis in terms of material and energy balance. Furthermore, autophagy has been implicated in the development, maturation, differentiation, and functional responses of immune cells[16].

Despite significant advances in LT, EAD remains a major clinical challenge. Increasing evidence suggests that complex interactions among regulated cell death pathways, immune responses, endothelial impairment, and microcirculatory dysfunction contribute to graft injury and subsequent multiorgan failure; however, these mechanisms are often considered independently[17-21]. Numerous predictive models of EAD have been formulated[18]. The early allograft failure in living donor LT model accurately identifies LDLT recipients at the highest risk for EAD postoperatively as shown in Table 1[18]. Main interacting processes occurred in LT patients are showed in Figure 1.

Figure 1 Sequence of interacting processes occurring in liver transplantation patients. LT: Liver transplantation; AI: Artificial intelligence; NMP: Normothermic macnine perfusion; HIRI: Hepatic ischemia reperfusion injury; SIRS: Systemic inflammatory response syndrome; MODS: Multiple organ dysfunction syndrome; ATP: Adenosine triphosphate; NO: Nitric oxide; ROS: Reactive oxygen species; KC: Kupffer cells; EAD: Early allograft dysfunction; MHC: Major histocompatibility complex.

Table 1 Early allograft failure after living donor liver transplantation model.

n	Factor
1	MELD score ≥ 27
2	Donor BMI > 30 kg/m2
3	Portal vein thrombosis
4	Hepaticojejunostomy
5	Peak alanine transferase > 468 U/L
6	Peak INR > 1.9
7	Bilirubin > 3.5 mg/dL at 7th postoperative week
8	INR > 1.3 at 7th postoperative week

Early allograft failure in living donor liver transplantation model at the highest risk for EAD: Sensitivity 75.0%, specificity 73.7%. MELD: Model for end-stage liver disease; BMI: Body mass index; INR: International normalized ratio.

EAD, characterized by hepatic insufficiency occurring within one week following orthotopic LT (OLT), affects up to 25% of transplant recipients and is linked to increased morbidity and mortality. Heme oxygenase-1 (HO-1), a cytoprotective enzyme, has been proposed as a potential novel biomarker for the detection of EAD[17].

EAD, following LT, is characterized by a combination of clinical and laboratory criteria. Notably, elevated and progressively increasing serum total bile acid levels within the first postoperative week have been correlated with the occurrence of EAD[22].

A novel classification system for EAD severity, comprising three distinct stages, has been proposed: (1) Stage I EAD is characterized solely by alanine aminotransferase (ALT) or aspartate aminotransferase levels equal to or exceeding 2000 U/L within the first postoperative week; (2) Stage II EAD is defined as either a bilirubin concentration ranging from 10 to 30 mg/dL or an international normalized ratio (INR) of 1.6 or higher on postoperative day 7; and (3) Stage III EAD is indicated by bilirubin levels of 30 mg/dL or greater or the concurrent presence of bilirubin levels equal to or exceeding 10 mg/dL alongside an INR of 1.6 or higher at the first postoperative week[23].

The prompt recognition of liver transplant recipients who are at increased risk of graft failure is essential to facilitate timely retransplantation. Lactate concentrations have been suggested as potential indicators of graft dysfunction[24].

Risk factors associated with failure to rescue transplant recipients include sarcopenia, EAD, and socioeconomic disparities, all of which may contribute to adverse outcomes[25]. The clinical status of the recipient, the age of the donor, and the intraoperative conditions must be meticulously evaluated to reduce the risk of EAD[26,27]. Challenging transplantations are common and associated with less favorable outcomes. Recipients who are older, obese, have elevated model for end-stage liver disease (MELD) scores, and have portal vein thrombosis are at an increased risk of complex surgical procedures. The MELD score for predicting 3-month mortality indicates the need for transplantation. Its calculation, interpretation, and clinical relevance are presented in Table 2. Additionally, a MELD score ≥ 27 predicts EAD. Early identification of these high-risk patients, modification of their risk factors, and optimization of donor–recipient matching protocols may improve future transplantation outcomes[28].

Table 2 Model for end-stage liver disease score and need for transplantation.

Variables	Calculation score equation	Score clinical relevance
TBIL	MELD: (3.78 × TBIL) + (11.2 × INR) + (9.57 × Cr) + 6.43	15 → transplanta-tion
INR	MELD-Na: MELD + 1.32 × (137-Na)-[0.033 × MELD × (137-Na)]	15-24 → interme-diate priority
Cr (mg/dL)		≥ 25 → high priority
Na		≥ 30 → high risk patient

MELD: Model for end-stage liver disease; TBIL: Total bilirubin; INR: International normalized ratio; Cr: Creatinine; Na: Sodium.

Bile, which is directly secreted by hepatocytes and cholangiocytes, is an organ-specific biofluid with significant diagnostic potential for evaluating graft viability and detecting early complications. Consequently, bile holds the potential to transform graft monitoring practices and enable personalized immunological surveillance[29].

Metagenomic next-generation sequencing represents a highly effective approach for the detection of bacteroids in bile. These findings may indicate the translocation of the intestinal microbiota into the biliary tract and could function as a potential early biomarker for assessing the compromised quality of donor livers[19].

The tissue inhibitor of metalloproteinase-2 has been identified as a predictive marker for EAD following LT[30]. Elastography-based assessment of liver stiffness has the potential to serve as an early predictor of EAD and graft failure following transplantation[31].

LT represents the primary therapeutic intervention for patients with hepatocellular carcinoma; however, postoperative complications, including EAD, maybe due to immunosuppression, acute rejection, and biliary complications, may adversely affect patient prognosis[32].

Various modalities of programmed cell death, including necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis, autophagy, PANoptosis, and NETosis, are associated with graft injury[1] (Figure 2).

Figure 2 Cell death mechanisms involved in hepatic ischemia reperfusion injury and liver graft injury. HIRI: Hepatic ischemia reperfusion injury; TNF-R1: TNF-α-receptor; DAMPs: Damage-associated molecular patterns; PRRs: Pattern recognition receptors; TLRs: Toll-like receptors; ROS: Reactive oxygen species; NF-κB: Nuclear factor Κβ; ATG: Autophagy-related proteins; NLRP3: NLR family pyrin domain containing 3; MAPK: Mitogen-activated protein kinase; GPX4: Glutathione peroxidase 4; TRPM2: Transient receptor potential melastatin 2; STAT1/STAT3: Signal transducer and activator of transcription; GSDMD: Gasdermin D; cGAS–STING: Cyclic GMP–AMP synthase; RIPK3: Receptor-interacting protein kinase 3; MLKL: Mixed lineage kinase domain-like protein; TNFRSF: Tumor necrosis factor receptor superfamily; ZBP1: Z-DNA-binding protein 1; NE: Neutrophilic elastase; MPO: Myeloperoxidase; PAD4: Peptidyl-arginine deaminase 4.

Overall, the abovementioned steps and concepts are interconnected and focus on the early diagnosis, prevention, treatment, or even slowing of EAD progression. EAD plays a significant role, as it leads to graft cell death and subsequent rejection. The sequential interaction of these processes occurs in the following order: LT → HIRI → EAD → graft cell necrosis → graft rejection. This sequence is illustrated in Figure 1, which also briefly highlights the factors contributing to EAD development alongside corresponding preventive measures.

This narrative review highlights EAD, its prevention, prompt detection and the underlying pathophysiological mechanisms of cell death that affect graft survival following OLT. The literature was identified through searches of the PubMed and Scopus databases using combinations of keywords, including “liver transplantation”, “hepatic ischemia–reperfusion injury”, “programmed cell death”, “apoptosis”, “necrosis”, “autophagy”, “ferroptosis”, “pyroptosis”, “necroptosis”, “NETosis”, “PANoptosis”, and “early allograft dysfunction”. Particular emphasis was placed on English-language experimental and clinical studies as well as systematic reviews. Priority was given to recent publications to ensure a current understanding of the mechanisms underlying LT.

APOPTOSIS

Apoptosis is a form of cell death characterized by cell shrinkage, membrane blebbing, chromatin condensation, nuclear fragmentation, and DNA fragmentation[33,34]. A hallmark feature of apoptosis is the formation of apoptotic bodies, a process mediated by the activation of caspases, which are a family of cysteine-dependent aspartate-specific proteases[33]. Hepatocyte apoptosis is an energy-requiring process that contributes to the pathogenesis of both acute and chronic liver diseases, including viral hepatitis, alcoholic and nonalcoholic liver disease, cholestatic disorders and HIRI during liver surgery and LT[35].

The mechanism of apoptotic cell death is regulated through intrinsic and extrinsic pathways. The extrinsic pathway is a death receptor-mediated mechanism initiated by ligand binding to Fas, TNF-α1, DR4 and DR5 receptors, leading to the formation of a death-inducing signaling complex and the recruitment of caspase-8 and caspase-10[36]. The intrinsic pathway is regulated by mitochondria and involves the release of various intracellular proteins, such as cytochrome c, apoptosis-inducing factor, second mitochondrial activator of caspases, endonuclease G, and high-temperature requirement protein A2 (Omi/HtrA2), into the cytosol. The release of mitochondrial proteins promotes the formation of apoptosome complexes, leading to the activation of the caspase-9 pathway, which further activates the effector caspase-3. The intrinsic pathway is regulated by the Bcl-2 family, which includes proapoptotic proteins such as Bid, Bax, Bak and Bcl-2 homology-3 and antiapoptotic proteins such as Bcl-2 and Bcl-xL[35,37,38].

HIRI is a major challenge in liver surgery and LT and significantly contributes to posttransplant complications, including primary graft nonfunction, EAD, graft rejection, and bile duct injury[9]. Experimental activation of the peroxisome proliferator-activated receptor alpha/peroxisome proliferator-activated receptor gamma coactivator 1-alpha pathway suppresses Bax and upregulates Bcl-2, leading to inhibition of apoptosis through reduced mitochondrial membrane permeability, cytochrome c release and caspase-3 activation, providing a new potential target for liver graft protection[39]. Furthermore, the activation of Kupffer cells (KCs) during HIRI may lead to the polarization of KCs into proinflammatory M1 or anti-inflammatory M2 phenotypes. The regulation of KC apoptosis and the modulation of its polarization appear to attenuate HIRI during LT; however, future research is needed[40].

During LT, apoptosis typically occurs in hepatocytes and other liver cells exposed to hypoxia and oxidative stress during ischemia. Specifically, the intrinsic pathway predominates during ischemia and early reperfusion because of ATP depletion, oxidative stress and mitochondrial dysfunction, whereas the extrinsic mechanism is activated mainly during the reperfusion phase when immune cell infiltration occurs. Unlike other cell death pathways, apoptosis does not trigger the release of inflammatory intracellular metabolites. However, the extensive apoptosis rate may still compromise liver graft function, leading to EAD[1,41].

NECROSIS

Necrosis is an uncontrolled form of cell death triggered by trauma, ischemia-reperfusion or infection and is characterized by cellular breakdown and the release of intracellular contents into the extracellular space. In contrast to apoptosis, necrosis is strongly associated with the induction of inflammatory responses and tissue damage due to activation of the immune cascade[42]. Necrosis promotes the release of DAMPs, such as high mobility group box 1 (HMGB1), interleukin (IL) 1-α, ATP, mitochondrial components and DNA fragments. The opening of the mitochondrial permeability transition pore results in the loss of mitochondrial membrane potential, ATP depletion, mitochondrial swelling, membrane rupture and the release of DAMPs. These molecules activate pattern recognition receptors (PRRs), including toll-like receptors (TLRs) and NOD-like receptors (NLRs), triggering inflammatory pathways such as nuclear factor κΒ (NF-κB) signaling, while the entire process is associated with the generation of ROS, the induction of oxidative stress, calcium overload, and the activation of nonapoptotic proteases such as calpains and nuclear DNA fragmentation. Interactions among calcium balance dysregulation, ROS-induced injury, and energy depletion amplify cellular injury and promote extensive cell death[43,44].

Necrosis involves both accidental and regulated pathways of cell death. Accidental necrosis results from chemical or metabolic insults that disrupt cellular homeostasis and membrane integrity, whereas regulated necrosis refers to genetically controlled lytic cell death programs mediated by specific signaling pathways. In contrast, secondary necrosis occurs when apoptotic cells are not promptly cleared by phagocytes and subsequently lose their membrane integrity; this leads to the release of intracellular contents and DAMPs, thereby promoting an inflammatory response[43,45].

The predominant mechanism of hepatocyte death following HIRI remains controversial. Early studies revealed necrosis as a prevalent form of cell death, whereas later investigations highlighted the role of apoptosis[46]. An experimental study based on established biomarkers of necrosis (ALT), full-length keratin-18, miR-122, HMGB1 and apoptosis (caspase activity and caspase-cleaved cytokeratin-18) provided strong evidence that necrosis was the predominant form of cell death, whereas apoptosis remained consistently minimal, further supporting necrosis as the primary mechanism of hepatocellular injury after HIRI[47]. In particular, during the reperfusion phase, necrosis appears to be responsible for more than 90% of the total cell death in liver grafts. However, following HIRI, the release of proinflammatory cytokines and DAMPs leads to a sterile inflammatory response in the transplanted liver and activates the innate immune cascade, which contributes to EAD and graft rejection[48,49]. Necrosis is particularly pronounced in vulnerable grafts, such as steatotic or donation after circulatory death (DCD) grafts, which exhibit impaired mitochondrial function, enhanced lipid peroxidation and reduced antioxidant defense, resulting in increased susceptibility to HIRI[1,50-52].

AUTOPHAGY

Autophagy is a stress-related cellular process responsible for the degradation and recycling of proteins and damaged organelles to maintain intracellular homeostasis. Although autophagy generally exerts a cytoprotective effect, disruption of autophagic regulatory mechanisms and excessive autophagic activity may contribute to cell death and organ damage[53,54]. Autophagy is regulated by autophagy-related proteins and includes several significant steps: Induction, initiation, nucleation, elongation, maturation, autophagosome biogenesis, fusion with lysosomes, degradation and recycling[55,56].

Autophagy plays important roles in energy balance, oxidative stress and the inflammatory response during HIRI via complex regulatory networks. The AMPK/mTOR pathway constitutes the most important mechanism in autophagy. During early ischemia, reduced mTOR activity induces autophagy, which exerts protective effects by limiting innate immune activation and apoptosis. However, excessive or prolonged autophagy may exacerbate hepatocellular injury[57]. The PINK1/Parkin pathway initiates the selective subtype of autophagy called mitophagy. As HIRI develops, damaged mitochondria release excessive amounts of mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA), which activate the NLRP3 inflammasome and promote the production of proinflammatory cytokines, thereby exacerbating the inflammatory response. Conversely, mtROS and mtDNA also stimulate the PINK1/Parkin pathway, inducing mitophagy that removes dysfunctional mitochondria, suppresses NLRP3 activation, and attenuates sterile immune activation[58]. Although protective, overactive mitophagy may result in uncontrolled elimination of mitochondria and other cellular components, leading to cell death. The MAPK pathway is another signaling cascade that transduces extracellular signals to regulate cellular processes, including apoptosis and autophagy. The MAPK pathway is divided into different pathways because of its four subgroups: ERK/MAPK, JNK/MAPK, p38/MAPK and ERK5/MAPK[56,59]. During HIRI, ERK activation promotes autophagy regulation and is generally associated with hepatoprotection, whereas JNK and p38 are often linked to inflammatory damage and cell death. Furthermore, the activation of the ERK/MAPK pathway promotes the dissociation of Bcl-2 from Beclin-1 in the reperfused hepatocytes, thereby inhibiting apoptosis and promoting autophagy[56]. Sirtuin 1 (SIRT)/FoxO3α signaling may also exert protective effects through the mediation of autophagy in ischemic hepatocytes[60]. The PI3K/AKT pathway is a major regulator of cellular metabolism, apoptosis and autophagy. Upon activation, PI3K generates PIP3, which activates AKT and downstream signaling pathways, including mTOR. In HIRI, the PI3K/AKT/mTOR axis has been shown to moderate autophagy, although its precise role remains controversial[61].

Although autophagy serves as an adaptive and generally hepatoprotective response during the early stages of ischemia, its overactivation may paradoxically exacerbate cellular damage during reperfusion. Excessive autophagy, particularly in steatotic or aged liver grafts, may promote autophagic cell death through the depletion of essential cellular components, thereby leading to graft rejection or EAD after LT. Overall, the effects of autophagy in LT and liver graft survival are highly context dependent, with moderate activation being protective and excessive activation potentially harmful. Moreover, autophagy interacts closely with other regulated cell death pathways, including apoptosis, necroptosis and ferroptosis, underscoring its contribution to HIRI. Further research is needed to define the critical threshold at which protective autophagy shifts to autophagic cell death, significantly challenging for improving liver graft survival[2,16,56].

NONAPOPTOTIC INFLAMMATORY FORMS OF CELL DEATH

In contrast to the immunologically silent nature of apoptosis, nonapoptotic inflammatory forms of cell death involves the activation of lytic pathways that trigger an excessive inflammatory response. The major forms of nonapoptotic inflammatory cell death include ferroptosis, pyroptosis, necroptosis, PANoptosis and NETosis. These pathways promote the release of DAMPs and cytokines into the extracellular space, which amplify immune-mediated injury and indicate damage to surrounding cells[62,63].

Ferroptosis

Ferroptosis is a recently recognized form of programmed cell death characterized by iron-dependent lipid peroxidation, depletion of glutathione, and inactivation of glutathione peroxidase 4 (GPX4)[64]. Ferroptosis-inducing agents can be classified into four major categories according to their molecular targets and mechanisms of action. The first category includes erastin, which inhibits the cystine/glutamate antiporter. The second category directly inhibits GPX4 through the activation of RSL3 and ML162 compounds, which prevents the detoxification of lipid hydroperoxides and leads to their accumulation. The third category induces FIN56, which promotes GPX4 degradation and depletes CoQ10, while the fourth category involves FINO2[65,66].

Recent evidence suggests the extensive role of ferroptosis in the pathophysiology of HIRI. Moreover, liver grafts from older donors and steatotic grafts increase the ferroptosis rate during HIRI, predisposing liver transplant patients to EAD and rejection[67,68]. Key mediators include transient receptor potential melastatin 2-dependent calcium influx, macrophage-derived indoleamine 2,3-dioxygenase 1 activation, and signal transducer and activator of transcription STAT1/STAT3 signaling pathway, which promote ferroptosis through the upregulation of iron metabolism, oxidative stress, and proinflammatory cytokine production[69-71]. Moreover, increasing evidence indicated that the STAT3-HO-1/COX-2 pathway contributes to iron-induced ferroptosis during HIRI through the dysregulation of the balance in the expression of proferroptotic (Hmox1, Tfrc, and Slc11a2) and antiferroptotic (Slc40a1 and Gpx4) genes[72,73]. Ferroptotic hepatocytes release DAMPs in the surrounding tissue, triggering neutrophil and macrophage infiltration and activation and stimulating the production of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6. Liver sinusoidal endothelial cells (LSECs) and hepatocytes appear to be particularly susceptible to ferroptosis, which contributes to severe hepatocellular injury during organ preservation and in the early postoperative period, making this pathway a key mechanistic driver of EAD following LT[74-76].

Pyroptosis

Pyroptosis is a lytic, inflammatory form of programmed cell death triggered by pathogen or danger-associated signaling pathways, resulting in cell edema, membrane rupture and the release of DAMPs, ultimately promoting the inflammatory response[77]. Pyroptosis is mediated through two major mechanisms: Canonical and noncanonical inflammasome pathways. Canonical pyroptosis is mediated by NLRP3 inflammasome-dependent activation of caspase-1 following recognition of pathogen-associated molecular patterns (PAMPs) or DAMPs. The activation of caspase-1 results in the cleavage of pro-IL-1β and pro-IL-18 into their active forms and the processing of the pyroptotic substrate gasdermin D (GSDMD) into N- and C-terminal fragments. The resulting GSDMD N-terminal fragments form membrane pores, leading to cell swelling and lysis and facilitating the release of IL-1β, IL-18, and other intracellular contents[78,79]. In contrast, noncanonical pyroptosis in humans is triggered by direct activation of caspase-4/5 by intracellular lipopolysaccharide. This pathway directly cleaves GSDMD and activates pannexin-1, a transmembrane channel protein. The results include the formation of large, nonselective pores in the cell membrane, uncontrolled potassium efflux, NLRP3 inflammasome activation, and subsequent caspase-1–dependent cytokine release[78,80]. In addition to GSDMD, other gasdermin family members also contribute to pyroptosis. GSDMB enhances noncanonical pyroptosis by mediating caspase-4 pathway activation, whereas GSDME can convert caspase-3–mediated apoptosis to pyroptosis, highlighting the extensive crosstalk between programmed cell death pathways[81,82].

In the context of LT, pyroptosis has been increasingly implicated in the inflammatory processes that occur during HIRI. At the onset of reperfusion, excessive amounts of DAMPs are released from injured hepatocytes, and oxidative stress activates NLRP3 in KCs and infiltrating macrophages, triggering caspase-1 activation, GSDMD cleavage and pyroptotic cell death[83]. Warm ischemia, particularly in DCD, is associated with greater inflammasome activation and inflammatory injury, where elevated expression of NLRP3, IL-1β, IL-18 and caspase-1 has been reported in DCD models[84]. Furthermore, experimental evidence has indicated that caspase-1 is a driver of hepatocellular injury in steatotic livers from patients with HIRI[85]. Similarly, a reduction in hepatocyte SIRT1 levels upregulated apoptosis and GSDME-mediated programmed cell death, leading to the deterioration of liver graft function and shortening survival[86].

Pharmacological inhibition of caspase-1 or NLRP3 reduces the inflammatory response and improves graft outcomes in experimental transplantation models[87]. mtDNA, a potent endogenous alarmins released during liver injury, is associated with EAD. Cytosolic mtDNA activates the cyclic GMP-AMP synthase (cGAS)–STING pathway, a key mediator of the innate immune response that promotes inflammatory signaling. Increasing evidence indicates that cGAS–STING signaling can increase NLRP3 inflammasome activation through a potassium efflux-dependent mechanism, thereby facilitating caspase-1 activation, IL-1β/IL-18 expression, and pyroptosis under specific inflammatory conditions. Thus, the interaction between cGAS–STING and NLRP3 signaling appears to amplify the sterile inflammatory response and contribute to posttransplant graft damage and rejection, rather than representing a direct pyroptotic pathway[83,88].

Necroptosis

Necroptosis is a regulated form of cell death that combines features of both apoptosis and necrosis and is mediated primarily by receptor-interacting protein kinase 3 (RIPK3) and its downstream effector, mixed lineage kinase domain-like protein (MLKL). Necroptosis can be triggered by several upstream signaling pathways, including those involving the tumor necrosis factor receptor superfamily (TNFRSF), TLR3/TLR4 and interferon receptors. In terms of the initiating stimuli, necroptosis can be broadly categorized into extrinsic necroptosis based on TNFα signaling, intrinsic necroptosis induced by ROS, and ischemia-associated intrinsic necroptosis[89]. The upregulation of TNFRSF subsequently activates RIPK3 and promotes the formation of the necrosome complex. Within the necrosome, RIPK3 phosphorylates and oligomerizes MLKL, which leads to the formation of lytic membrane pores and cell death via necroptosis. The local release of DAMPs and proinflammatory mediators further exacerbates the inflammatory response[90].

Recent evidence revealed that necroptosis is a major contributor to HIRI, particularly in vulnerable settings such as those involving steatosis and aging graft donation[46,91]. Furthermore, in experimental models, HIRI severity was associated with increased expression of RIPK3 and MLKL, suggesting that activation of the necroptotic pathway is a notable driver of liver injury[92]. Following HIRI, necroptotic cells release DAMPs that promote the inflammatory response and aggravate liver injury. These signals activate TLRs, leading to innate immune cell recruitment to the graft and contributing to EAD and allograft rejection[48]. Experimental and clinical studies have demonstrated increased expression of phosphorylated MLKL (pMLKL) in grafts subjected to HIRI. Elevated pMLKL levels following reperfusion were correlated with higher serum aminotransferase and lactate dehydrogenase concentrations and were strongly associated with the subsequent development of EAD[93].

PANoptosis

Described in 2019, PANoptosis is a form of programmed cell death that combines the characteristics of pyroptosis, apoptosis and necroptosis; however, it cannot be explained by any of these pathways alone. The key mechanism of PANoptosis involves the formation of multiprotein complexes, termed PANoptosomes, which are assembled by innate immune receptors, adaptors and catalytic effectors, such as ZBP1, NLRP3, RIPK1, RIPK3, caspase-6, caspase-8, caspase-1, absent in melanoma 2 (AIM2), apoptosis-associated speck-like protein containing a CARD (ASC) and fas-associated death domain[94,95]. To date, four distinct PANoptosome complexes have been identified-the ZBP1-, AIM2-, NLRP12- and RIPK1-PANoptosomes-each of which is defined by its initiating sensor and unique molecular composition[96]. Main mechanisms of PANoptosis are shown in Figure 3.

Figure 3 Mechanisms of PANoptosis. ZBP1: Z-DNA-binding protein 1; AIM2: Absent in melanoma; NLRP12: NLR family pyrin domain containing 12; NLRP3: NLR family pyrin domain containing 3; RIPK1: Receptor-interacting protein kinase 1; ASC: Apoptosis-associated speck-like protein containing a CARD; FADD: Fas-associated death domain; Casp: Caspase; GSDMD: Gasdermin D; MLKL: Mixed lineage kinase domain-like protein; HIRI: Hepatic ischemia-reperfusion injury; EAD: Early allograft dysfunction; LT: Liver transplantation.

Growing evidence suggests that PANoptosis plays a critical role in inflammatory conditions. In the context of liver disease, compared with distinct programmed cell death mechanisms, PANoptosis initiates more potent inflammatory and cytotoxic responses by simultaneously inducing pyroptotic cytokine release, necroptotic membrane disruption, and apoptotic structural fragmentation[97]. Tulahong et al[98] performed a gene set enrichment analysis that revealed eight differentially expressed PANoptosis-related genes with potential diagnostic value in HIRI. These genes are involved in key inflammatory responses and cell survival pathways. Notably, IL-1α and IL-1β serve as major mediators of inflammatory cascade, whereas NLRP12-driven inflammasome activation promotes IL-1β activation and PAMP- and DAMP-associated signaling. Other genes, including IER3, CDKN1A (p21), c-JUN, EMP1 and BTG family members, regulate stress responses, oxidative injury, cell cycle progression and tissue repair. Another bioinformatic analysis identified six PANoptosis-associated genes (CEBPB, HSPA1A, HSPA1B, IRF1, SERPINE1 and TNFAIP3) as HIRI-related biomarkers that are regulated by NF-κB and miRNA-155[99]. In steatotic liver grafts, ROS-induced ZBP1 aggregation promotes RIPK1-dependent apoptosis and inflammatory amplification independent of Z-nucleic acid recognition, thereby exacerbating HIRI. Although this mechanism has primarily been linked to RIPK1-mediated cell death, ZBP1 is a recognized PANoptosis regulator, suggesting that it may function as a trigger of PANoptotic signaling in vulnerable steatotic grafts. Furthermore, caspase-8 plays an important regulatory role in the coordination of apoptotic signaling, the modulation of RIPK3/MLKL-dependent necroptosis and the enhancement of pyroptotic mechanisms through gasdermin cleavage, thereby linking multiple cell death pathways during HIRI[100,101]. Collectively, these data indicate that PANoptosis is a potential driver of liver graft injury and suggest that coordinated activation of apoptotic, pyroptotic, and necroptotic pathways may be detectable in clinical settings, suggesting that PANoptosis is a potential tool for risk stratification of EAD.

NETosis

NETosis is a form of programmed neutrophil cell death characterized by the release of nuclear DNA and antimicrobial proteins into the extracellular space, creating structures known as neutrophil extracellular traps (NETs). These web-like formations function to capture and eliminate invading pathogens while contributing to innate immune defense[102,103]. NETosis is characterized by a series of events that involve mainly ROS-triggered activation of neutrophil elastase, myeloperoxidase (MPO) and peptidyl-arginine deaminase 4 (PAD4), leading to chromatin decondensation and nuclear membrane disruption. Subsequently, GSDMD-mediated pore formation allows the release of chromatin–protein complexes such as NETs, with MLKL and inflammasome signaling potentially contributing to this process[102,104]. NET formation can occur through two distinct mechanisms. In suicidal (lytic) NETosis, neutrophils undergo a regulated cell death program characterized by nuclear and plasma membrane rupture alongside the extracellular release of DNA–protein complexes. In contrast, vital (nonlytic) NET release enables neutrophils to expel nuclear or mitochondrial DNA while maintaining plasma membrane integrity and preserving essential cellular functions, including migration and phagocytosis[102].

Although NETosis contributes to host defense, excessive NET formation can aggravate tissue injury and impair graft outcomes. The liver is particularly susceptible to NET accumulation during HIRI because of the unique architecture of the hepatic sinusoids, which promotes neutrophil activation and NET release. Specifically, a sterile inflammatory environment created in postischemic hepatic tissue, in combination with endothelial dysfunction and the release of DAMPs, strongly favors NET formation. Activated LSECs further increase neutrophil recruitment through proinflammatory mediators such as IL-33, whereas HMGB1, extracellular DNA, ATP and cytokines promote NETosis via innate immune signaling pathways[105,106]. The resulting NETs enhance immunothrombosis by facilitating platelet aggregation and microthrombus formation within the liver and distant organs, thereby promoting the inflammatory response and tissue damage[106,107]. Clinical studies have demonstrated a positive correlation between NET levels and rejection severity, suggesting that NETs amplify graft injury through a positive feedback loop. Furthermore, delayed neutrophil apoptosis prolongs NET formation, contributing to sustained tissue damage and a chronic inflammatory response, resulting in an increased incidence of complications, such as acute rejection, EAD, arterial thrombosis and hepatocellular carcinoma recurrence, during the posttransplant period[108,109].

INTERACTIONS AMONG REGULATED CELL DEATH PATHWAYS DURING LT

LT involves complex cellular and molecular mechanisms in which programmed cell death pathways function not as isolated events, but rather as interconnected processes that evolve throughout the different phases of graft injury. During cold and warm ischemia, ATP depletion, metabolic acidosis, mitochondrial dysfunction, iron accumulation, and ROS production primarily promote apoptosis, necrosis, and ferroptosis, particularly in hepatocytes and LSECs. Hepatocytes are particularly susceptible to necrosis and ferroptosis during warm ischemia, driven by calcium overload and ROS overproduction, whereas cold ischemia causes these cells to undergo enhanced inflammatory cell death upon reperfusion[1]. Recent studies suggest that hepatocytes may undergo pyroptosis via the SIRT1-dependent activation of GSDME during cold graft storage and reperfusion[86]. In contrast, LSECs are highly vulnerable to cold ischemia, which promotes ferroptosis and impaired autophagy; additionally, their high sensitivity to ROS during warm ischemia may lead to early apoptosis, which contributes to endothelial dysfunction after reperfusion[1,110]. KCs and bone marrow-derived macrophages predominantly undergo pyroptosis and necroptosis following NLRP3 signaling and inflammatory activation. Meanwhile, cholangiocytes are susceptible to apoptosis and late necrosis during both cold and warm ischemia, predisposing them to posttransplant biliary complications[1,111]. Finally, NET release and neutrophil cell death via NETosis are increasingly recognized as major mediators of HIRI[112]. The main cell-specific cell death characteristics are summarized in Table 3.

Table 3 Cell type–specific regulated cell death pathways in liver transplantation.

Cell type	Dominant cell death pathway	Key mediators	Clinical implications
Hepatocytes	Apoptosis, necrosis, ferroptosis, autophagy, necroptosis, PANoptosis, pyroptosis	Caspase -3, caspase-8, caspase-9, Bcl-2 family, GPX4, ACSL4, Slc7A11, RIPK1/RIPK3/MLKL, ZBP1, NF-κB, ROS, DAMPs, NLRP3, GSDMD	Hepatocellular injury, elevated transaminases, graft dysfunction, EAD
LSEcs	Ferroptosis, apoptosis, autophagy	GPX4, HO-1, caspase-3, ROS	Endothelial dysfunction, impaired microcirculation, HIRI, EAD
KCs	Apoptosis, pyroptosis, necroptosis, PANoptosis	NLRP3, ASC, caspase-1, GSDMD, RIPK3, MLKL, cytokines, ROS	Cytokine storm, inflammatory response, HIRI
Cholangiocytes	Apoptosis, necrosis	Caspases, oxidative stress mediators	Biliary complications
Infiltrated macrophages	Pyroptosis, necroptosis, ferroptosis	NLRP3, caspase-1, cytokines, ROS	Innate inflammatory activation, HIRI
Neutrophils	NETosis	ROS, NE, MPO, PAD4, GSDMD, DAMPs	HIRI, microthrombus formation, acute rejection, EAD, inflammatory response

LSECs: Liver sinusoidal endothelial cells; KCs: Kupffer cells; GPX4: Glutathione peroxidase 4; ACSL4: Acyl-CoA synthetase long-chain family member 4; RIPK: Receptor-interacting protein kinase; MLKL: Mixed lineage kinase domain-like protein; ZBP1: Z-DNA-binding protein 1; NF-κB: Nuclear factor κB; ROS: Reactive oxygen species; DAMPs: Damage-associated molecular patterns; NLRP3: NLR family pyrin domain containing 3; GSDMD: Gasdermin D; HO-1: Heme oxygenase-1; ASC: Apoptosis-associated speck-like protein containing a CARD; NE: Neutrophilic elastase; MPO: Myeloperoxidase; PAD4: Peptidyl-arginine deaminase 4; EAD: Early allograft dysfunction; HIRI: Hepatic ischemia-reperfusion injury.

During innate immune activation, immunogenic lytic forms of regulated cell death, including pyroptosis, necroptosis, ferroptosis, PANoptosis, and NETosis, predominate. These pathways promote the release of DAMPs and proinflammatory cytokines, leading to the activation of PRRs, macrophages, and neutrophils, thereby amplifying sterile immune-mediated tissue injury. In contrast, apoptosis is largely immunologically silent, whereas necrosis also contributes to innate immune activation through the passive DAMP signaling cascade and TLR2/NF-κB activation following severe cellular injury[1,113]. Furthermore, the interactions among these cell death pathways during HIRI induce endothelial dysfunction and microcirculatory injury, thereby increasing the risk of postreperfusion syndrome, EAD, acute rejection, and liver failure.

Collectively, these findings highlight the cell type–specific vulnerabilities to distinct regulated cell death pathways during the different stages of the LT process. This provides a rationale for developing targeted therapeutic strategies tailored to the specific procedural phase and graft characteristics.

FUTURE DIRECTIONS

Despite the excellent long-term outcomes of LT in the management of end-stage liver disease, EAD remains a significant clinical challenge, which mainly reflects impaired graft function in the absence of vascular complications, rejection, or infection and may result in recovery because of the regenerative capacity of the liver. EAD occurs in approximately 15%-30% of grafts from donation after brain death donors and in up to 68% of grafts from DCD donors. EAD is associated with increased postoperative complications, progressive loss of graft function and mortality[114].

Cell death mechanisms are fundamental determinants of liver transplant outcomes and contribute to HIRI, graft dysfunction and long-term graft survival. Many risk factors for EAD remain nonmodifiable; therefore, future research should focus on reducing HIRI through optimized graft preservation, machine perfusion technologies and targeted pharmacological interventions (Figure 4). Clinical and preclinical studies have consistently demonstrated that hepatocyte death contributes to the initiation and progression of EAD. The elucidation of interactions among different pathways, including apoptosis, necrosis, autophagy, ferroptosis, pyroptosis, necroptosis, NETosis, and PANoptosis, is very important, as these pathways may act synergistically to amplify graft injury[115]. The main characteristics of the cell death pathways affecting liver graft function and survival after LT are summarized in Table 4. The application of transcriptomic, proteomic and metabolomic studies may be instrumental in defining cell–specific death signatures and identifying key molecular steps that coordinate these processes to investigate the main biological mechanisms underlying liver graft quality[116]. Factors contributing to HIRI and graft outcome during LT are shown in Figure 4. The rapid development of AI technologies and bioinformatics may further influence the field of LT by offering new tools for research on cell death mechanisms, along with clinical decision-making and training frameworks[15,117,118].

Figure 4 Factors contributing to hepatic ischemia reperfusion injury and graft outcome during liver transplantation. HIRI: Hepatic ischemia reperfusion injury; DCD: Donation after circulatory death; MELD: Model for end-stage liver disease; LSECs: Liver sinusoidal endothelial cells; EAD: Early allograft dysfunction.

Table 4 Major characteristics of cell death pathways affecting liver graft function in liver transplantation.

Cell death pathway	Molecular mediators	Pathophysiological mechanisms	Main features	Clinical consequences
Apoptosis	TNF-R1, DR4 and DR5 receptors, Caspase-8, Caspase-10, Cytochrome c, AIF, Caspase-9, Caspase-3, Bcl-2 family	DISC formation, ATP depletion, oxidative stress, mitochondrial dysfunction, immune cell infiltration	Cell shrinkage, membrane bulging, nuclear fragmentation, DNA reorganization, formation of membrane-bound apoptotic bodies	Hepatocyte loss, HIRI, liver graft dysfunction, EAD
Necrosis	DAMPs, PRRs, TLRs, NLRs, NF-κB activation, ROS	Inflammatory response, loss of mitochondrial membrane potential, ATP depletion, mitochondrial swelling, membrane rupture, oxidative stress, calcium overload	Cellular breakdown, MPTP opening, DAMPs release	HIRI, sterile inflammatory response, EAD, graft rejection
Autophagy	ATG, AMPK/mTOR, PINK1/Parkin, ROS, NLRP3 inflammasome, MAPK	Inflammatory response, energy balance, oxidative stress	Damaged organelles and proteins degradation and recycling, mitophagy	Hepatocellular injury mainly in steatotic or aged liver grafts, graft rejection, EAD
Ferroptosis	Erastin, GPX4, TRPM2, IDO-1, STAT1/STAT3, DAMPs, ROS	TRPM2-dependent calcium influx, IDO-1 activation, overregulation of iron metabolism, oxidative stress, cytokine production, DAMPs release	Iron-dependent lipid peroxidation, GSH depletion, GPX4 inactivation	HIRI, graft rejection, EAD, LSECs and hepatocellular injury
Pyroptosis	Caspase-1, NLRP3, GSDMD, Caspase 4/5, ROS, cGAS-STING, cytokines	DAMPs and PAMPs release, inflammatory response, oxidative stress	Cell edema, membrane rupture, calcium overload	HIRI, DCD and steatotic graft injury, EAD
Necroptosis	RIPK3, DAMPs, MLKL, TNFRSF, TLR3/TLR4, interferon receptors, ROS, cytokines	Oxidative stress, inflammatory response, necrosome formation	Membrane rupture, DAMPs release	HIRI, hepatocellular injury, EAD and graft rejection
PANoptosis	PANoptosome, ZBP1, NLRP3, RIPK1, RIPK3, caspase-6, caspase-8, caspase-1, AIM2, ASC, FADD, cytokines, ROS	Severe inflammatory response, oxidative stress	Combined activation of pyroptosis, apoptosis and necroptosis	HIRI, steatotic graft injury
NETosis	ROS, NE, MPO, PAD4, GSDMD, DAMPs	Neutrophil activation, sterile inflammatory response, DAMPs release, platelets aggregation	Nuclear membrane disruption and DNA release, NETs formation	Graft injury, HIRI, microthrombus formation, acute rejection, EAD, arterial thrombosis, hepatocellular carcinoma reccurrence

TNF-R1: TNF-α-receptor; DISC: Death-inducing signaling complex; AIF: Apoptosis-inducing factor; DAMPs: Damage-associated molecular patterns; MPTP: Mitochondrial permeability transition pore; PRRs: Pattern recognition receptors; TLRs: Toll-like receptors; NLRs: NOD-like receptors; NF-κB: Nuclear factor κΒ; ROS: Reactive oxygen species; ATG: Autophagy-related proteins; MAPK: Mitogen-activated protein kinase; GSH: Glutathione; GPX4: Glutathione peroxidase 4; TRPM2: Transient receptor potential melastatin 2; IDO-1: Macrophage-derived indoleamine 2,3-dioxygenase 1; STAT1/STAT3: Signal transducer and activator of transcription; GSDMD: Gasdermin D; DCD: Donation after circulatory death; cGAS-STING: Cyclic GMP-AMP synthase; PAMPs: Pathogen-associated molecular patterns; RIPK3: Receptor-interacting protein kinase 3; MLKL: Mixed lineage kinase domain-like protein; TNFRSF: Tumor necrosis factor receptor superfamily; ZBP1: Z-DNA-binding protein 1; AIM2: Absent in melanoma 2; ASC: Apoptosis-associated speck-like protein containing a CARD; FADD: Fas-associated death domain; NETs: Neutrophil extracellular traps; NE: Neutrophilic elastase; MPO: Myeloperoxidase; PAD4: Peptidyl-arginine deaminase 4; EAD: Early allograft dysfunction; HIRI: Hepatic ischemia-reperfusion injury; LSECs: Liver sinusoidal endothelial cells.

From a translational perspective, the development of reliable biomarkers capable of detecting early activation of regulated cell death pathways in liver grafts may improve risk stratification and enable timely therapeutic intervention to prevent EAD. Particular attention should be given to validating pathway-specific mediators, such as HMGB1, micro-RNAs, DNA fragments, NET components, and NLRP3[118].

The detection of pathway-specific biomarkers may improve the early diagnosis, prognostic stratification, and monitoring of graft function following LT. Ferroptosis is characterized by alterations in GPX4, ACSL4, and lipid peroxidation products such as 4-hydroxynonenal and malondialdehyde[1,67,119]. Pyroptosis is associated with the activation of the NLRP3 inflammasome, caspase-1, and GSDMD, alongside the increased release of the proinflammatory cytokines IL-1β and IL-18. Necroptosis can be characterized by the elevated expression of p-RIPK3 and p-MLKL, whereas NETosis is characterized by increased circulating levels of CitH3, MPO-DNA complexes, and cell-free DNA fragments. Integrating these pathway-specific biomarkers with new technologies, such as transcriptomics and AI-based predictive models, may facilitate the comprehensive characterization of graft injury, improve the early prediction of EAD, and enable the development of personalized therapeutic approaches for LT[1,120].

The identification of novel therapeutic agents remains an urgent priority in LT to prevent graft injury and dysfunction. Future strategies may involve the simultaneous modulation of multiple cell death and inflammatory pathways rather than the inhibition of a single mechanism. Targeting shared upstream regulators, such as ROS, DAMP signaling, inflammasome activation, cytokines and NF-κB, may support broader protection against graft injury and improve long-term transplant outcomes. Specifically, during organ preservation and machine perfusion, ferroptosis inhibitors, iron chelators, and antioxidants may protect hepatocytes and LSECs by reducing lipid peroxidation and oxidative stress. Likewise, the pharmacological inhibition of the NLRP3 inflammasome, caspase-1, or GSDMD may attenuate pyroptosis and sterile inflammatory signaling during reperfusion, whereas the blockade of the RIPK1/RIPK3/MLKL signaling axis offers a strategy for suppressing necroptosis[1,121,122]. Therapies targeting NETosis, such as PAD4 inhibitors, antioxidants, and DNase I administration, may reduce immunothrombosis and microvascular dysfunction, whereas interventions directed against DAMP signaling could further downregulate the inflammatory cascade[1]. Importantly, machine perfusion technologies and organ preservation techniques provide a unique platform for the targeted delivery and evaluation of these therapies before implantation, enabling graft preconditioning and potentially improving posttransplant outcomes.

Large-scale clinical studies and randomized controlled trials are necessary to translate these experimental findings into effective therapeutic approaches for liver transplant patients.

This narrative review has several limitations inherent to its design. Given that the literature was not selected through a systematic methodology, selection bias cannot be excluded. Moreover, the evidence is derived from heterogeneous experimental and clinical studies. Additionally, several regulated cell death pathways are incompletely characterized in the context of LT and remain under investigation. Consequently, some mechanistic and therapeutic conclusions should be interpreted with caution and require further clinical validation.

CONCLUSION

Despite this progress, HIRI remains a critical determinant affecting the incidence of EAD following OLT. EAD is associated with increased postoperative morbidity and mortality, adverse long-term outcomes, and ultimately graft failure. HIRI affects nearly all transplanted grafts to varying degrees, with clinical outcomes contingent upon the extent of graft injury. Effective management of EAD necessitates prevention, early detection, and a multidisciplinary, individualized therapeutic approach. A comprehensive understanding of the pathophysiological mechanisms underlying EAD and hepatocyte necrosis is essential for optimizing graft function posttransplantation. Accumulating evidence indicates that graft injury is not driven by a single form of cell death but rather by a dynamic network of interconnected processes involving metabolic stress, mitochondrial dysfunction, oxidative injury, regulated cell death mechanisms, sterile immune activation, endothelial dysfunction, and microcirculatory failure. The cellular death pathways influencing liver graft viability include apoptosis, necrosis, autophagy, and nonapoptotic inflammatory forms of cell death, such as ferroptosis, pyroptosis, necroptosis, PANoptosis, and NETosis. Persistent crosstalk among these pathways establishes self-amplifying inflammatory cascades that aggravate hepatocellular and sinusoidal endothelial injury, ultimately compromising graft function. A more comprehensive understanding of the cell-specific interactions among these pathways offers new opportunities for clinical translation. The integration of pathway-specific biomarkers with multi-omics and AI technologies may improve graft viability assessment, facilitate early prediction of EAD and enable precision risk stratification. Future therapeutic approaches will likely require multimodal and stage-specific interventions that simultaneously target interconnected pathways rather than individual mechanisms. Recent progress in organ preservation methodologies, in addition to targeted pharmacological strategies aimed at specific cellular death mechanisms, offers significant potential for reducing graft injury and improving graft survival outcomes.