RIPK3 promoter hypermethylation in hepatocytes protects from bile acid-induced inflammation and necroptosis

KLX ameliorates liver cancer progression by mediating ZBP1 transcription and ubiquitination and increasing ZBP1-induced PANoptosis

Liver cancer is a highly aggressive malignancy with poor survival rates. Current treatments, including liver transplantation, immunotherapy, and gene therapy, are often limited by late-stage diagnosis and significant side effects, highlighting the urgent need for novel therapeutic agents. In this study, we evaluated the therapeutic potential of Kanglexin (KLX), a novel anthraquinone derivative, in the treatment of liver cancer. In vitro, KLX inhibited the proliferation and migration of HepG2 and Hep3B cells in a dose-dependent manner. Mechanistically, KLX upregulated Z-DNA binding protein 1 (ZBP1) expression, inducing PANoptosis by directly binding to ZBP1, altering its conformation, and reducing its affinity for the E3 ubiquitin ligase ring finger protein 180 (RNF180). This interaction decreased ZBP1 ubiquitination, thereby increasing its stability. Additionally, KLX upregulated the expression of the transcription factor homeobox D10 (HOXD10), which further increased ZBP1 expression. Elevated ZBP1 levels significantly suppressed liver cancer cell proliferation and migration, whereas the inhibitory effects of KLX were reversed upon ZBP1 knockdown. In a xenograft model, KLX significantly inhibited tumor growth with a lower toxicity than oxaliplatin (OXA). In conclusion, KLX promoted PANoptosis in liver cancer cells by upregulating ZBP1 and preventing its degradation, thereby inhibiting liver cancer progression and migration. These findings suggest that KLX is a promising therapeutic agent for liver cancer.

Targeting protein kinase C-α prolongs survival and restores liver function in sepsis: Evidence from preclinical models

Sepsis is a life-threatening organ failure resulting from a poorly regulated infection response. Organ dysfunction includes hepatic involvement, weakening the immune system due to excretory liver failure, and metabolic dysfunction, increasing the death risk. Although experimental studies correlated excretory liver functionality with immune performance and survival rates in sepsis, the proteins and pathways involved remain unclear. This study identified protein kinase C-α (PKCα) as a novel target for managing excretory liver function during sepsis. Using a preclinical murine sepsis model, we found that both PKCα knockout and the use of a PKCα-inhibitor midostaurin successfully restored liver function without hindering the host's response or ability to clear the pathogen, highlighting PKCα's vital role in excretory liver failure. In septic animals, both approaches significantly boosted survival rates. Midostaurin is the clinically approved active pharmaceutical ingredient in Rydapt, approved for the adjuvant treatment of FTL3-mutated AML. Here, it reduced plasma bile acids and related inflammation in those patients, opening a translational avenue for therapeutics in sepsis. Conclusively, our research underscores the significance of PKCα in controlling excretory liver function during inflammation. This suggests that targeting this protein could restore liver function without compromising the immune system, thereby decreasing sepsis mortality and supporting the recent paradigm that the liver is a hub for the host response to infection that might, in the future, result in novel host-directed therapies supporting the current state-of-the-art intensive care medicine in patients with sepsis-associated liver failure.

Divergent roles of RIPK3 and MLKL in high-fat diet-induced obesity and MAFLD in mice

Cell death frequently occurs in the pathogenesis of obesity and metabolic dysfunction-associated fatty liver disease (MAFLD). However, the exact contribution of core cell death machinery to disease manifestations remains ill-defined. Here, we show via the direct comparison of mice genetically deficient in the essential necroptotic regulators, receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL), as well as mice lacking apoptotic caspase-8 in myeloid cells combined with RIPK3 loss, that RIPK3/caspase-8 signaling regulates macrophage inflammatory responses and drives adipose tissue inflammation and MAFLD upon high-fat diet feeding. In contrast, MLKL, divergent to RIPK3, contributes to both obesity and MAFLD in a manner largely independent of inflammation. We also uncover that MLKL regulates the expression of molecules involved in lipid uptake, transport, and metabolism, and congruent with this, we discover a shift in the hepatic lipidome upon MLKL deletion. Collectively, these findings highlight MLKL as an attractive therapeutic target to combat the growing obesity pandemic and metabolic disease.

Intricate interplay between cell metabolism and necroptosis regulation in metabolic dysfunction-associated steatotic liver disease: A narrative review

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), encompasses a progressive spectrum of liver conditions, ranging from steatosis to metabolic dysfunction-associated steatohepatitis, characterised by hepatocellular death and inflammation, potentially progressing to cirrhosis and/or liver cancer. In both experimental and human MASLD, necroptosis-a regulated immunogenic necrotic cell death pathway-is triggered, yet its exact role in disease pathogenesis remains unclear. Noteworthy, necroptosis-related signalling pathways are emerging as key players in metabolic reprogramming, including lipid and mitochondrial metabolism. Additionally, metabolic dysregulation is a well-established contributor to MASLD development and progression. This review explores the intricate interplay between cell metabolism and necroptosis regulation and its impact on MASLD pathogenesis. Understanding these cellular events may offer new insights into the complexity of MASLD pathophysiology, potentially uncovering therapeutic opportunities and unforeseen metabolic consequences of targeting necroptosis.

Gancao decoction attenuates hepatic necroptosis via activating caspase 8 in cholestatic liver injury

ETHNOPHARMACOLOGICAL RELEVANCE

Gancao Decoction (GCD) is widely used to treat cholestatic liver injury. However, it is unclear whether is related to prevent hepatocellular necroptosis.

AIM OF THE STUDY

The purpose of this study is to clarify the therapeutic effects of GCD against hepatocellular necroptosis induced by cholestasis and its active components.

MATERIALS AND METHODS

We induced cholestasis model in wild type mice by ligating the bile ducts or in Nlrp3-/- mice by intragastrical administering Alpha-naphthylisothiocyanate (ANIT). Serum biochemical indices, liver pathological changes and hepatic bile acids (BAs) were measured to evaluate GCD's hepatoprotective effects. Necroptosis was assessed by expression of hallmarkers in mice liver. Moreover, the potential anti-necroptotic effect of components from GCD were investigated and confirmed in ANIT-induced cholestasis mice and in primary hepatocytes from WT mouse stimulated with Tumor Necrosis Factor alpha (TNF-α) and cycloheximide (CHX).

RESULTS

GCD dose-dependently alleviated hepatic necrosis, reduced serum aminotranferase activity in both BDL and ANIT-induced cholestasis models. More importantly, the expression of hallmarkers of necroptosis, including MLKL, RIPK1 and RIPK3 phosphorylation (p- MLKL, p-RIPK1, p-RIPK3) were reduced upon GCD treatment. Glycyrrhetinic acid (GA), the main bioactive metabolite of GCD, effectively protected against ANIT-induced cholestasis, with decreased expression of p-MLKL, p-RIPK1 and p-RIPK3. Meanwhile, the expression of Fas-associated death domain protein (FADD), long isoform of cellular FLICE-like inhibitory protein (cFLIPL) and cleaved caspase 8 were upregulated upon GA treatment. Moreover, GA significantly increased the expression of active caspase 8, and reduced that of p-MLKL in TNF-α/CHX induced hepatocytes necroptosis.

CONCLUSIONS

GCD substantially inhibits necroptosis in cholestatic liver injury. GA is the main bioactive component responsible for the anti-necroptotic effects, which correlates with upregulation of c-FLIPL and active caspase 8.

Mediators of necroptosis: from cell death to metabolic regulation

Necroptosis, a programmed cell death mechanism distinct from apoptosis, has garnered attention for its role in various pathological conditions. While initially recognized for its involvement in cell death, recent research has revealed that key necroptotic mediators, including receptor-interacting protein kinases (RIPKs) and mixed lineage kinase domain-like protein (MLKL), possess additional functions that go beyond inducing cell demise. These functions encompass influencing critical aspects of metabolic regulation, such as energy metabolism, glucose homeostasis, and lipid metabolism. Dysregulated necroptosis has been implicated in metabolic diseases, including obesity, diabetes, metabolic dysfunction-associated steatotic liver disease (MASLD) and alcohol-associated liver disease (ALD), contributing to chronic inflammation and tissue damage. This review provides insight into the multifaceted role of necroptosis, encompassing both cell death and these extra-necroptotic functions, in the context of metabolic diseases. Understanding this intricate interplay is crucial for developing targeted therapeutic strategies in diseases that currently lack effective treatments.

New therapeutic concepts against ischemia-reperfusion injury in organ transplantation

INTRODUCTION

Ischemia-reperfusion injury (IRI) involves a positive amplification feedback loop that stimulates innate immune-driven tissue damage associated with organ procurement from deceased donors and during transplantation surgery. As our appreciation of its basic immune mechanisms has improved in recent years, translating putative biomarkers into therapeutic interventions in clinical transplantation remains challenging.

AREAS COVERED

This review presents advances in translational/clinical studies targeting immune responses to reactive oxygen species in IRI-stressed solid organ transplants, especially livers. Here we focus on novel concepts to rejuvenate suboptimal donor organs and improve transplant function using pharmacologic and machine perfusion (MP) strategies. Cellular damage induced by cold ischemia/warm reperfusion and the latest mechanistic insights into the microenvironment's role that leads to reperfusion-induced sterile inflammation is critically discussed.

EXPERT OPINION

Efforts to improve clinical outcomes and increase the donor organ pool will depend on improving donor management and our better appreciation of the complex mechanisms encompassing organ IRI that govern the innate-adaptive immune interface triggered in the peritransplant period and subsequent allo-Ag challenge. Computational techniques and deep machine learning incorporating the vast cellular and molecular mechanisms will predict which peri-transplant signals and immune interactions are essential for improving access to the long-term function of life-saving transplants.