Hepatocyte-specific deletion of IL1-RI attenuates liver injury by blocking IL-1 driven autoinflammation

Gut microbiota dysbiosis links chronic apical periodontitis to liver fibrosis in nonalcoholic fatty liver disease: Insights from a mouse model

AIM

In this study, we investigated the systemic implications of chronic apical periodontitis (CAP). CAP may contribute to the nonalcoholic fatty liver disease (NAFLD) progression through the gut microbiota and its metabolites, which are related to the degree of fibrosis.

METHODOLOGY

Sixteen 7-week-old male apolipoprotein E knockout (apoE-/-) mice were randomly divided into two groups: the CAP and Con groups. A CAP model was established by sealing the first- and second-maxillary molars with bacterium-containing cotton balls. Apical lesions were evaluated by micro-CT. Histological evaluations of NAFLD were performed using second harmonic generation/two-photon excitation fluorescence (SHG/TPEF) assays. Additionally, we comprehensively analyzed the gut microbiota using 16S rRNA gene sequencing and explored metabolic profiles by liquid chromatography-mass spectrometry (LC-MS). Immunofluorescence analysis was used to examine the impact of CAP on tight junction proteins and mucin expression. Transcriptome assays have elucidated gene expression alterations in liver tissues.

RESULTS

Micro-CT scans revealed an evident periapical bone loss in the CAP group, and the total collagen percentage was increased (Con, 0.0361 ± 0.00510%, CAP, 0.0589 ± 0.00731%, p < .05). 16S rRNA sequencing revealed reduced diversity and distinct taxonomic enrichment in the CAP group. Metabolomic assessments revealed that differentially enriched metabolites, including D-galactosamine, were enriched and that 16-hydroxyhexadecanoic acid and 3-methylindole were depleted in the CAP group. Immunofluorescence analyses revealed disruptions in tight junction proteins and mucin production, indicating intestinal barrier integrity disruption. Liver transcriptome analysis revealed upregulation of Lpin-1 expression in the CAP group.

CONCLUSION

This study provides comprehensive evidence of the systemic effects of CAP on liver fibrosis in NAFLD patients by elucidating alterations in the gut microbiota composition and metabolism.

A Novel Bifunctional Fusion Protein (Anti-IL-17A-sST2) Protects against Acute Liver Failure, Modulating the TLR4/MyD88 Pathway and NLRP3 Inflammasome Activation

Acute liver failure (ALF) is a serious inflammatory disorder with high mortality rates, which poses a significant threat to human health. The IL-33/ST2 signal is a crucial regulator in inflammation responses associated with lipopolysaccharide (LPS)-induced macrophages. The IL-17A signaling pathway promotes the release of chemokines and inflammatory cytokines, recruiting neutrophils and T cells under LPS stimulation, thus facilitating inflammatory responses. Here, the potential therapeutic benefits of neutralizing the IL-17A signal and modulating the IL-33/ST2 signal in ALF were investigated. A novel dual-functional fusion protein, anti-IL-17A-sST2, was constructed, which displayed high purity and biological activities. The administration of anti-IL-17A-sST2 resulted in significant anti-inflammatory benefits in ALF mice, amelioration of hepatocyte necrosis and interstitial congestion, and reduction in TNF-α and IL-6. Furthermore, anti-IL-17A-sST2 injection downregulated the expression of TLR4 and NLRP3 as well as important molecules such as MyD88, caspase-1, and IL-1β. The results suggest that anti-IL-17A-sST2 reduced the secretion of inflammatory factors, attenuated the inflammatory response, and protected hepatic function by regulating the TLR4/MyD88 pathway and inhibiting the NLRP3 inflammasome, providing a new therapeutic approach for ALF.

Hyperactivation of succinate dehydrogenase promotes pyroptosis of macrophage via ROS-induced GSDMD oligomerization in acute liver failure

Acute liver failure (ALF) is a life-threatening disease with high mortality. Given excessive inflammation is one of the major pathogenesis of ALF, candidates targeting inflammation could be beneficial in the condition. Now the effect of hyperactivated succinate dehydrogenase (SDH) on promoting inflammation in lipopolysaccharide (LPS)-treated macrophages has been studied. However, its role and mechanism in ALF is not well understood. Here intraperitoneal injection of D-galactosamine and LPS was conducted in male C57BL/6 J mice to induce the ALF model. Dimethyl malonate (DMM), which inhibited SDH activity, was injected intraperitoneally 30 min before ALF induction. Macrophage pyroptosis was induced by LPS plus adenosine triphosphate (ATP). Pyroptosis-related molecules and proteins including GSDMD oligomer were examined by ELISA and western blot techniques, respectively. ROS production was assessed by fluorescence staining. The study demonstrated SDH activity was increased in liver macrophages from ALF mice. Importantly, DMM administration inhibited ROS, IL-1β, and pyroptosis-associated proteins levels (NLRP3, cleaved caspase-1, GSDMD-N, and GSDMD oligomers) both in the ALF model and in macrophages stimulated with LPS plus ATP. In vitro, ROS promoted pyroptosis by facilitating GSDMD oligomerization. Additionally, when ROS levels were increased through the addition of H2O2 to the DMM group, the levels of GSDMD oligomers were reverted. In conclusion, SDH hyperactivation promotes macrophage pyroptosis by ROS-mediated GSDMD oligomerization, suggesting that targeting this pathway holds promise as a strategy for treating ALF and other inflammatory diseases.

Malaria blood stage infection suppresses liver stage infection via host-induced interferons but not hepcidin

Malaria-causing Plasmodium parasites first replicate as liver stages (LS), which then seed symptomatic blood stage (BS) infection. Emerging evidence suggests that these stages impact each other via perturbation of host responses, and this influences the outcome of natural infection. We sought to understand whether the parasite stage interplay would affect live-attenuated whole parasite vaccination, since the efficacy of whole parasite vaccines strongly correlates with their extend of development in the liver. We thus investigated the impact of BS infection on LS development of genetically attenuated and wildtype parasites in female rodent malaria models and observed that for both, LS infection suffered severe suppression during concurrent BS infection. Strikingly and in contrast to previously published studies, we find that the BS-induced iron-regulating hormone hepcidin is not mediating suppression of LS development. Instead, we demonstrate that BS-induced host interferons are the main mediators of LS developmental suppression. The type of interferon involved depended on the BS-causing parasite species. Our study provides important mechanistic insights into the BS-mediated suppression of LS development. This has direct implications for understanding the outcomes of live-attenuated Plasmodium parasite vaccination in malaria-endemic areas and might impact the epidemiology of natural malaria infection.

Thrombospondin 1 enhances systemic inflammation and disease severity in acute-on-chronic liver failure

BACKGROUND

The key role of thrombospondin 1 (THBS1) in the pathogenesis of acute-on-chronic liver failure (ACLF) is unclear. Here, we present a transcriptome approach to evaluate THBS1 as a potential biomarker in ACLF disease pathogenesis.

METHODS

Biobanked peripheral blood mononuclear cells (PBMCs) from 330 subjects with hepatitis B virus (HBV)-related etiologies, including HBV-ACLF, liver cirrhosis (LC), and chronic hepatitis B (CHB), and normal controls (NC) randomly selected from the Chinese Group on the Study of Severe Hepatitis B (COSSH) prospective multicenter cohort underwent transcriptome analyses (ACLF = 20; LC = 10; CHB = 10; NC = 15); the findings were externally validated in participants from COSSH cohort, an ACLF rat model and hepatocyte-specific THBS1 knockout mice.

RESULTS

THBS1 was the top significantly differentially expressed gene in the PBMC transcriptome, with the most significant upregulation in ACLF, and quantitative polymerase chain reaction (ACLF = 110; LC = 60; CHB = 60; NC = 45) was used to verify that THBS1 expression corresponded to ACLF disease severity outcome, including inflammation and hepatocellular apoptosis. THBS1 showed good predictive ability for ACLF short-term mortality, with an area under the receiver operating characteristic curve (AUROC) of 0.8438 and 0.7778 at 28 and 90 days, respectively. Enzyme-linked immunosorbent assay validation of the plasma THBS1 using an expanded COSSH cohort subjects (ACLF = 198; LC = 50; CHB = 50; NC = 50) showed significant correlation between THBS1 with ALT and γ-GT (P = 0.01), and offered a similarly good prognostication predictive ability (AUROC = 0.7445 and 0.7175) at 28 and 90 days, respectively. ACLF patients with high-risk short-term mortality were identified based on plasma THBS1 optimal cut-off value (< 28 µg/ml). External validation in ACLF rat serum and livers confirmed the functional association between THBS1, the immune response and hepatocellular apoptosis. Hepatocyte-specific THBS1 knockout improved mouse survival, significantly repressed major inflammatory cytokines, enhanced the expression of several anti-inflammatory mediators and impeded hepatocellular apoptosis.

CONCLUSIONS

THBS1 might be an ACLF disease development-related biomarker, promoting inflammatory responses and hepatocellular apoptosis, that could provide clinicians with a new molecular target for improving diagnostic and therapeutic strategies.

NF-κB in biology and targeted therapy: new insights and translational implications

NF-κB signaling has been discovered for nearly 40 years. Initially, NF-κB signaling was identified as a pivotal pathway in mediating inflammatory responses. However, with extensive and in-depth investigations, researchers have discovered that its role can be expanded to a variety of signaling mechanisms, biological processes, human diseases, and treatment options. In this review, we first scrutinize the research process of NF-κB signaling, and summarize the composition, activation, and regulatory mechanism of NF-κB signaling. We investigate the interaction of NF-κB signaling with other important pathways, including PI3K/AKT, MAPK, JAK-STAT, TGF-β, Wnt, Notch, Hedgehog, and TLR signaling. The physiological and pathological states of NF-κB signaling, as well as its intricate involvement in inflammation, immune regulation, and tumor microenvironment, are also explicated. Additionally, we illustrate how NF-κB signaling is involved in a variety of human diseases, including cancers, inflammatory and autoimmune diseases, cardiovascular diseases, metabolic diseases, neurological diseases, and COVID-19. Further, we discuss the therapeutic approaches targeting NF-κB signaling, including IKK inhibitors, monoclonal antibodies, proteasome inhibitors, nuclear translocation inhibitors, DNA binding inhibitors, TKIs, non-coding RNAs, immunotherapy, and CAR-T. Finally, we provide an outlook for research in the field of NF-κB signaling. We hope to present a stereoscopic, comprehensive NF-κB signaling that will inform future research and clinical practice.

ANGPTL3 negatively regulates IL-1β-induced NF-κB activation by inhibiting the IL1R1-associated signaling complex assembly

Interleukin-1β (IL-1β)-induced signaling is one of the most important pathways in regulating inflammation and immunity. The assembly of the receptor complex, consisting of the ligand IL-1β, the IL-1 receptor (IL-1R) type 1 (IL1R1), and the IL-1R accessory protein (IL1RAP), initiates this signaling. However, how the IL1R1-associated complex is regulated remains elusive. Angiopoietin like 3 (ANGPTL3), a key inhibitor of plasma triglyceride clearance, is mainly expressed in the liver and exists in both intracellular and extracellular secreted forms. Currently, ANGPTL3 has emerged as a highly promising drug target for hypertriglyceridemia and associated cardiovascular diseases. However, most studies have focused on the secreted form of ANGPTL3, while its intracellular role is still largely unknown. Here, we report that intracellular ANGPTL3 acts as a negative regulator of IL-1β-triggered signaling. Overexpression of ANGPTL3 inhibited IL-1β-induced NF-κB activation and the transcription of inflammatory genes in HepG2, THP1, and HEK293T cells, while knockdown or knockout of ANGPTL3 resulted in opposite effects. Mechanistically, ANGPTL3 interacted with IL1R1 and IL1RAP through its intracellular C-terminal fibrinogen-like domain and disrupted the assembly of the IL1R1-associated complex. Taken together, our study reveals a novel role for ANGPTL3 in inflammation, whereby it inhibits the physiological interaction between IL1R1 and IL1RAP to maintain immune tolerance and homeostasis in the liver.

Therapeutic modulation of the liver immune microenvironment

Inflammation is a hallmark of progressive liver diseases such as chronic viral or immune-mediated hepatitis, alcohol-associated liver disease, and NAFLD. Preclinical and clinical studies have provided robust evidence that cytokines and related cellular stress sensors in innate and adaptive immunity orchestrate hepatic disease processes. Unresolved inflammation and liver injury result in hepatic scarring, fibrosis, and cirrhosis, which may culminate in HCC. Liver diseases are accompanied by gut dysbiosis and a bloom of pathobionts, fueling hepatic inflammation. Anti-inflammatory strategies are extensively used to treat human immune-mediated conditions beyond the liver, while evidence for immunomodulatory therapies and cell therapy-based strategies in liver diseases is only emerging. The development and establishment of novel immunomodulatory therapies for chronic liver diseases has been dampened by several clinical challenges, such as invasive monitoring of therapeutic efficacy with liver biopsy in clinical trials and risk of DILI in several studies. Such aspects prevented advancements of novel medical therapies for chronic inflammatory liver diseases. New concepts modulating the liver immune environment are studied and eagerly awaited to improve the management of chronic liver diseases in the future.

Interleukin-36γ is causative for liver damage upon infection with Rift Valley fever virus in type I interferon receptor-deficient mice

Type I interferons (IFN) are pro-inflammatory cytokines which can also exert anti-inflammatory effects via the regulation of interleukin (IL)-1 family members. Several studies showed that interferon receptor (IFNAR)-deficient mice develop severe liver damage upon treatment with artificial agonists such as acetaminophen or polyinosinic:polycytidylic acid. In order to investigate if these mechanisms also play a role in an acute viral infection, experiments with the Bunyaviridae family member Rift Valley fever virus (RVFV) were performed. Upon RVFV clone (cl)13 infection, IFNAR-deficient mice develop a severe liver injury as indicated by high activity of serum alanine aminotransferase (ALT) and histological analyses. Infected IFNAR-/- mice expressed high amounts of IL-36γ within the liver, which was not observed in infected wildtype (WT) animals. In line with this, treatment of WT mice with recombinant IL-36γ induced ALT activity. Furthermore, administration of an IL-36 receptor antagonist prior to infection prevented the formation of liver injury in IFNAR-/- mice, indicating that IL-36γ is causative for the observed liver damage. Mice deficient for adaptor molecules of certain pattern recognition receptors indicated that IL-36γ induction was dependent on mitochondrial antiviral-signaling protein and the retinoic acid-inducible gene-I-like receptor. Consequently, cell type-specific IFNAR knockouts revealed that type I IFN signaling in myeloid cells is critical in order to prevent IL-36γ expression and liver injury upon viral infection. Our data demonstrate an anti-inflammatory role of type I IFN in a model for virus-induced hepatitis by preventing the expression of the novel IL-1 family member IL-36γ.

HIF-1α inhibition in macrophages preserves acute liver failure by reducing IL-1β production

The development of acute liver failure (ALF) is dependent on its local inducer. Inflammation is a high-frequency and critical factor that accelerates hepatocyte death and liver failure. In response to injury stress, the expression of the transcription factor hypoxia-inducible factor-1α (HIF-1α) in macrophages is promoted by both oxygen-dependent and oxygen-independent mechanisms, thus promoting the expression and secretion of the cytokine interleukin-1β (IL-1β). IL-1β further induces hepatocyte apoptosis or necrosis by signaling through the receptor (IL-1R) on hepatocyte. HIF-1α knockout in macrophages or IL-1R knockout in hepatocytes protects against liver failure. However, whether HIF-1α inhibition in macrophages has a protective role in ALF is unclear. In this study, we revealed that the small molecule HIF-1α inhibitor PX-478 inhibits the expression and secretion of IL-1β, but not tumor necrosis factor α (TNFα), in bone marrow-derived macrophages (BMDMs). PX-478 pretreatment alleviates liver injury in LPS/D-GalN-induced ALF mice by decreasing the hepatic inflammatory response. In addition, preventive or therapeutic administration of PX-478 combined with TNFα neutralizing antibody markedly improved LPS/D-GalN-induced ALF. Taken together, our data suggest that PX-478 administration leads to HIF-1α inhibition and decreased IL-1β secretion in macrophages, which represents a promising therapeutic strategy for inflammation-induced ALF.

A new class of potent liver injury protective compounds: Structural elucidation, total synthesis and bioactivity study

A new class of potent liver injury protective compounds, phychetins A-D (1-4) featuring an unique 6/6/5/6/5 pentacyclic framework, were isolated and structurally characterized from a Chinese medicinal plant Phyllanthus franchetianus. Compounds 2-4 are three pairs of enantiomers that were initially obtained in a racemic manner, and were further separated by chiral HPLC preparation. Compounds 1-4 were proposed to be originated biosynthetically from a coexisting lignan via an intramolecular Friedel-Crafts reaction as the key step. A bioinspired total synthesis strategy was thus designated, and allowed the effective syntheses of compounds 2-4 in high yields. Some of compounds exhibited significant anti-inflammatory activities in vitro via suppressing the production of pro-inflammatory cytokine IL-1β. Notably, compound 4, the most active enantiomeric pair in vitro, displayed prominent potent protecting activity against liver injury at a low dose of 3 mg/kg in mice, which could serve as a promising lead for the development of acute liver injury therapeutic agent.

Splicing Factor SRSF1 Promotes Pancreatitis and KRASG12D-Mediated Pancreatic Cancer

Inflammation is strongly associated with pancreatic ductal adenocarcinoma (PDAC), a highly lethal malignancy. Dysregulated RNA splicing factors have been widely reported in tumorigenesis, but their involvement in pancreatitis and PDAC is not well understood. Here, we report that the splicing factor SRSF1 is highly expressed in pancreatitis, PDAC precursor lesions, and tumors. Increased SRSF1 is sufficient to induce pancreatitis and accelerate KRASG12D-mediated PDAC. Mechanistically, SRSF1 activates MAPK signaling-partly by upregulating interleukin 1 receptor type 1 (IL1R1) through alternative-splicing-regulated mRNA stability. Additionally, SRSF1 protein is destabilized through a negative feedback mechanism in phenotypically normal epithelial cells expressing KRASG12D in mouse pancreas and in pancreas organoids acutely expressing KRASG12D, buffering MAPK signaling and maintaining pancreas cell homeostasis. This negative feedback regulation of SRSF1 is overcome by hyperactive MYC, facilitating PDAC tumorigenesis. Our findings implicate SRSF1 in the etiology of pancreatitis and PDAC, and point to SRSF1-misregulated alternative splicing as a potential therapeutic target.

SIGNIFICANCE

We describe the regulation of splicing factor SRSF1 expression in the context of pancreas cell identity, plasticity, and inflammation. SRSF1 protein downregulation is involved in a negative feedback cellular response to KRASG12D expression, contributing to pancreas cell homeostasis. Conversely, upregulated SRSF1 promotes pancreatitis and accelerates KRASG12D-mediated tumorigenesis through enhanced IL1 and MAPK signaling. This article is highlighted in the In This Issue feature, p. 1501.

Transcriptomics integrated with metabolomics unravels the interweaving of inflammatory response and 1-stearoyl-2-arachidonoyl-sn-glycerol metabolic disorder in chronic cadmium exposure-induced hepatotoxicity

Chronic Cd exposure induces an inflammatory response that contributes to liver damage. In the present study, C57BL/6J mice (8 weeks) were administered CdCl₂ (0.6mg/L) orally for 6 months, and the underlying mechanism of chronic Cd-induced hepatotoxicity was explored through the application of transcriptomics and metabolomics. Chronic Cd exposure induced focal necrosis and inflammatory cell infiltration in the livers of mice. Importantly, hepatic IL-1β, IL-6, IL-9, IL-10, IL-17 and GM-CSF levels were significantly increased following chronic Cd exposure. Ingenuity Pathway Analysis of the transcriptomics profiles combined with RTqPCR was used to identify and optimize a crucial inflammatory response network in chronic Cd hepatotoxicity. Furthermore, an integrative analysis combining inflammatory response genes with differential metabolites revealed that 1-stearoyl-2-arachidonoyl-sn-glycerol and 4-hydroxybutanoic acid lactone levels were significantly correlated with all inflammatory response genes. Overall, our findings in this study help decipher the underlying mechanisms and key molecular events of chronic Cd hepatotoxicity.

The Pharmacological Efficacy of Baicalin in Inflammatory Diseases

Baicalin is one of the most abundant flavonoids found in the dried roots of Scutellaria baicalensis Georgi (SBG) belonging to the genus Scutellaria. While baicalin is demonstrated to have anti-inflammatory, antiviral, antitumor, antibacterial, anticonvulsant, antioxidant, hepatoprotective, and neuroprotective effects, its low hydrophilicity and lipophilicity limit the bioavailability and pharmacological functions. Therefore, an in-depth study of baicalin's bioavailability and pharmacokinetics contributes to laying the theoretical foundation for applied research in disease treatment. In this view, the physicochemical properties and anti-inflammatory activity of baicalin are summarized in terms of bioavailability, drug interaction, and inflammatory conditions.

Fluorofenidone protects against acute liver failure in mice by regulating MKK4/JNK pathway

AIMS

Acute liver failure (ALF) is a life-threatening disease characterized by abrupt and extensive hepatic necrosis and apoptosis, resulting in high mortality. The approved drug, N-acetylcysteine (NAC), is only effective for acetaminophen (APAP)-associated ALF at the early stage. Thus, we investigate whether fluorofenidone (AKF-PD), a novel antifibrosis pyridone agent, protects against ALF in mice and explore its underlying mechanisms.

METHODS

ALF mouse models were established using APAP or lipopolysaccharide/D-galactosamine (LPS/D-Gal). Anisomycin and SP600125 were used as JNK activator and inhibitor, respectively, and NAC served as a positive control. Mouse hepatic cell line AML12 and primary mouse hepatocytes were used for in vitro studies.

RESULTS

AKF-PD pretreatment alleviated APAP-induced ALF with decreased necrosis, apoptosis, reactive oxygen species (ROS) markers, and mitochondrial permeability transition in liver. Additionally, AKF-PD alleviated mitochondrial ROS stimulated by APAP in AML12 cells. RNA-sequencing in the liver and subsequent gene set enrichment analysis showed that AKF-PD significantly impacted MAPK and IL-17 pathway. In vitro and in vivo studies demonstrated that AKF-PD inhibited APAP-induced phosphorylation of MKK4/JNK, while SP600125 only inhibited JNK phosphorylation. The protective effect of AKF-PD was abolished by anisomycin. Similarly, AKF-PD pretreatment abolished hepatotoxicity caused by LPS/D-Gal, decreased ROS levels, and diminished inflammation. Furthermore, unlike NAC, AKF-PD, inhibited the phosphorylation of MKK4 and JNK upon pretreatment, and improved survival in cases of LPS/D-Gal-induced mortality with delayed dosing.

CONCLUSIONS

In summary, AKF-PD can protect against ALF caused by APAP or LPS/D-Gal, in part, via regulating MKK4/JNK pathway. AKF-PD might be a novel candidate drug for ALF.

The effects of pentoxifylline and caffeic acid phenethyl ester on TNF-α and lung histopathology in D-galactosamine-induced pulmonary injury in rats

In this study, we aimed to investigate the effects of pentoxifylline [PTX] and caffeic acid phenethyl ester [CAPE] in D-galactosamine [D-GAL]-induced pulmonary injury in rats. The rats were randomly divided into six groups: control, D-GAL, D-GAL+PTX, D-GAL+CAPE, PTX and CAPE. Each group included eight animals. Lung sections from the control, PTX and CAPE groups had a normal histological appearance. The D-GAL group showed histopathological changes in lung tissue, including haemorrhage, oedema, inter-alveolar septal thickening and widespread infiltration of inflammatory lymphocytes and macrophages. Administration of PTX and CAPE significantly reduced histopathological damage scores in the D-GAL+PTX and D-GAL+CAPE groups compared with the D-GAL group. PTX and CAPE treatment also significantly decreased malondialdehyde levels, increased levels of reduced GSH and increased catalase and superoxide dismutase activity in lung tissue samples. These results indicate that the destructive effects of D-GAL-induced inflammation in the rat lung are significantly reduced following administration of PTX and CAPE.

Cumulus Cells Accelerate Postovulatory Oocyte Aging through IL1-IL1R1 Interaction in Mice

The oocytes of female mammals will undergo aging after ovulation, also known as postovulatory oocyte aging (POA). Until now, the mechanisms of POA have not been fully understood. Although studies have shown that cumulus cells accelerate POA over time, the exact relationship between the two is still unclear. In the study, by employing the methods of mouse cumulus cells and oocytes transcriptome sequencing and experimental verification, we revealed the unique characteristics of cumulus cells and oocytes through ligand-receptor interactions. The results indicate that cumulus cells activated NF-κB signaling in oocytes through the IL1-IL1R1 interaction. Furthermore, it promoted mitochondrial dysfunction, excessive ROS accumulation, and increased early apoptosis, ultimately leading to a decline in the oocyte quality and the appearance of POA. Our results indicate that cumulus cells have a role in accelerating POA, and this result lays a foundation for an in-depth understanding of the molecular mechanism of POA. Moreover, it provides clues for exploring the relationship between cumulus cells and oocytes.

The Role of the NLRP3 Inflammasome and Programmed Cell Death in Acute Liver Injury

Acute liver injury (ALI) is a globally important public health issue that, when severe, rapidly progresses to acute liver failure, seriously compromising the life safety of patients. The pathogenesis of ALI is defined by massive cell death in the liver, which triggers a cascade of immune responses. Studies have shown that the aberrant activation of the nod-like receptor protein 3 (NLRP3) inflammasome plays an important role in various types of ALI and that the activation of the NLRP3 inflammasome causes various types of programmed cell death (PCD), and these cell death effectors can in turn regulate NLRP3 inflammasome activation. This indicates that NLRP3 inflammasome activation is inextricably linked to PCD. In this review, we summarize the role of NLRP3 inflammasome activation and PCD in various types of ALI (APAP, liver ischemia reperfusion, CCl₄, alcohol, Con A, and LPS/D-GalN induced ALI) and analyze the underlying mechanisms to provide references for future relevant studies.

Targeting Notch1-YAP Circuit Reprograms Macrophage Polarization and Alleviates Acute Liver Injury in Mice

BACKGROUND & AIMS

Hepatic immune system disorder plays a critical role in the pathogenesis of acute liver injury. The intrinsic signaling mechanisms responsible for dampening excessive activation of liver macrophages are not completely understood. The Notch and Hippo-YAP signaling pathways have been implicated in immune homeostasis. In this study, we investigated the interactive cell signaling networks of Notch1/YAP pathway during acute liver injury.

METHODS

Myeloid-specific Notch1 knockout (Notch1^M-KO) mice and the floxed Notch1 (Notch1^FL/FL) mice were subjected to lipopolysaccharide/D-galactosamine toxicity. Some mice were injected via the tail vein with bone marrow-derived macrophages transfected with lentivirus-expressing YAP. Some mice were injected with YAP siRNA using an in vivo mannose-mediated delivery system.

RESULTS

We found that the activated Notch1 and YAP signaling in liver macrophages were closely related to lipopolysaccharide/D-galactosamine-induced acute liver injury. Macrophage/neutrophil infiltration, proinflammatory mediators, and hepatocellular apoptosis were markedly ameliorated in Notch1^M-KO mice. Importantly, myeloid Notch1 deficiency depressed YAP signaling and facilitated M2 macrophage polarization in the injured liver. Furthermore, YAP overexpression in Notch1^M-KO livers exacerbated liver damage and shifted macrophage polarization toward the M1 phenotype. Mechanistically, macrophage Notch1 signaling could transcriptionally activate YAP gene expression. Reciprocally, YAP transcriptionally upregulated the Notch ligand Jagged1 gene expression and was essential for Notch1-mediated macrophage polarization. Finally, dual inhibition of Notch1 and YAP in macrophages further promoted M2 polarization and alleviated liver damage.

CONCLUSIONS

Our findings underscore a novel molecular insight into the Notch1-YAP circuit for controlling macrophage polarization in acute liver injury, raising the possibility of targeting macrophage Notch1-YAP circuit as an effective strategy for liver inflammation-related diseases.

Identification of a Chromosome 1 Substitution Line B6-Chr1BLD as a Novel Hyperlipidemia Model via Phenotyping Screening

Hyperlipidemia is a chronic disease that seriously affects human health. Due to the fact that traditional animal models cannot fully mimic hyperlipidemia in humans, new animal models are urgently needed for basic drug research on hyperlipidemia. Previous studies have demonstrated that the genomic diversity of the wild mice chromosome 1 substitution lines was significantly different from that of laboratory mice, suggesting that it might be accompanied by phenotypic diversity. We first screened the blood lipid-related phenotype of chromosome 1 substitution lines. We found that the male HFD-fed B6-Chr1BLD mice showed more severe hyperlipidemia-related phenotypes in body weight, lipid metabolism and liver lesions. By RNA sequencing and whole-genome sequencing results of B6-Chr1BLD, we found that several differentially expressed single nucleotide polymorphism enriched genes were associated with lipid metabolism-related pathways. Lipid metabolism-related genes, mainly including Aida, Soat1, Scly and Ildr2, might play an initial and upstream role in the abnormal metabolic phenotype of male B6-Chr1BLD mice. Taken together, male B6-Chr1BLD mice could serve as a novel, polygenic interaction-based hyperlipidemia model. This study could provide a novel animal model for accurate clinical diagnosis and precise medicine of hyperlipidemia.

Human liver tissue transcriptomics revealed immunometabolic disturbances and related biomarkers in hepatitis B virus-related acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a major cause of liver-related death worldwide, but its key pathological features remain incompletely defined. This study aimed to reveal the molecular basis of hepatitis B virus-related ACLF (HBV-ACLF) by transcriptome sequencing of human liver tissue. A total of 18 human liver tissues from patients with different stages of HBV-related disease were collected for RNA sequencing, and liver tissues from patients and mouse models with ACLF were used for subsequent validation. Specifically, 6,853 differentially expressed genes (DEGs) and 5,038 differentially expressed transcripts were identified in patients with ACLF compared to patients with chronic hepatitis B (CHB) and normal controls (NCs). Investigation of functional by KEGG pathway enrichment analysis revealed prominent immune and metabolic dysregulation at the ACLF stage. We found that the key genes FGF19, ADCY8 and KRT17, which are related to immunometabolic disturbances, were significantly upregulated in the progression of ACLF. The three key genes were validated in human and mouse samples, indicating their prognostic and therapeutic potential in ACLF. In summary, our work reveals that immunometabolic disorder is involved in HBV-ACLF pathogenesis and indicates that FGF19, ADCY8 and KRT17 may be sensitive biomarkers for HBV-related ACLF.

Hepatic HRC induces hepatocyte pyroptosis and HSCs activation via NLRP3/caspase-1 pathway

The histidine-rich calcium-binding protein (HRC) is a regulator of Ca2 + homeostasis and it plays a significant role in liver fibrosis. Pyroptosis, a specific inflammatory cell death, can lead to hepatic stellate cells (HSCs) activation and liver fibrosis. However, the role of HRC in pyroptosis has not been explored. In this study, we demonstrated that HRC, mainly located in the hepatocyte, was over expressed in fibrotic liver tissues. We further found that enforced expression of HRC in hepatocytes induced pyroptosis and HMGB1 release, and subsequently led to HSCs activation by NLRP3/caspase-1 pathway. In addition, the proliferation and migration of HSCs were also enhanced by HRC overexpression in hepatocytes. Furthermore, NLRP3 inhibitor MCC950 and caspase-1 inhibitor VX-765 alleviated hepatic HRC-mediated hepatocytes pyroptosis and HSCs activation. This study demonstrated that hepatic HRC promoted HSCs activation by inducing hepatocyte pyroptosis, which suggests that HRC may be a promising therapeutic target to prevent liver fibrosis.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Hypoxia inducible factor 1α promotes interleukin-1 receptor antagonist expression during hepatic ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion injury (IRI) is a major risk associated with liver surgery and transplantation, and its pathological mechanism is complex. Interleukin-1 receptor antagonist (IL-1ra) can protect the liver from IRI. However, the regulatory mechanism of IL-1ra expression is still unclear.

AIM

To identify the mechanism that could protect the liver in the early stage of IRI.

METHODS

To screen the key genes in hepatic IRI, we performed RNA sequencing and gene enrichment analysis on liver tissue from mice with hepatic IRI. Subsequently, we verified the expression and effect of IL-1ra in hepatic IRI. We also used promoter mutagenesis and chromatin immunoprecipitation assay to search for the transcriptional regulatory sites of hypoxia-inducible factor (HIF)-1α. Finally, to explore the protective mechanism of ischemic preconditioning (IP), we examined the expression of HIF-1α and IL-1ra after IP.

RESULTS

We identified IL-1ra as a key regulator in hepatic IRI. The expression of IL-1ra was significantly upregulated after hepatic IRI both in vivo and in vitro. Furthermore, we found that HIF-1α regulated Il-1ra transcription in response to hypoxia. Increased HIF-1α accumulation promoted IL-1ra expression, whereas inhibition of HIF-1α exhibited the opposite effect. We also confirmed a predominant role for hypoxia response element in the regulation of Il1ra transcription by HIF-1α activation. Of note, we demonstrated that IP protects against hepatic IRI by inducing IL-1ra expression, which is mediated through HIF-1α.

CONCLUSION

We demonstrated that ischemia or hypoxia leads to increased expression of IL-1ra through HIF-1α. Importantly, IP protects the liver from IRI via the HIF-1α–IL-1ra pathway.

The important role of NLRP6 inflammasome in Pasteurella multocida infection

Pasteurella multocida (P. multocida) can cause severe respiratory disease in cattle, resulting in high mortality and morbidity. Inflammasomes are multiprotein complexes in the cytoplasm that recognize pathogens and play an important role in the host defense against microbial infection. In this study, the mechanism of P. multocida-induced NLRP6 inflammasome activation was investigated in vitro and in vivo. Firstly, P. multocida induced severe inflammation with a large number of inflammatory cells infiltrating the lungs of WT and Nlrp6^−/− mice. Nlrp6^−/− mice were more susceptible to P. multocida infection and they had more bacterial burden in the lungs. Then, the recruitment of macrophages and neutrophils in the lungs was investigated and the results show that the number of immune cells was significantly decreased in Nlrp6^−/− mice. Subsequently, NLRP6 was shown to regulate P. multocida-induced inflammatory cytokine secretion including IL-1β and IL-6 both in vivo and in vitro while TNF-α secretion was not altered. Moreover, NLRP6 was found to mediate caspase-1 activation and ASC oligomerization, resulting in IL-1β secretion. Furthermore, NLRP6 inflammasome mediated the gene expression of chemokines including CXCL1, CXCL2 and CXCR2 which drive the activation of NLRP3 inflammasomes. Finally, NLRP3 protein expression was detected to be abrogated in P. multocida-infected Nlrp6^−/− macrophages, indicating the synergic effect of NLRP6 and NLRP3. Our study demonstrates that NLRP6 inflammasome plays an important role in the host against P. multocida infection and contributes to the development of immune therapeutics against P. multocida.

Mechanism of hydroxysafflor yellow A on acute liver injury based on transcriptomics

Objective: To investigate how Hydroxysafflor yellow A (HSYA) effects acute liver injury (ALI) and what transcriptional regulatory mechanisms it may employ.

Methods: Rats were randomly divided into five groups (n = 10): Control, Model, HSYA-L, HSYA-M, and HSYA-H. In the control and model groups, rats were intraperitoneally injected with equivalent normal saline, while in the HSYA groups, they were also injected with different amounts of HSYA (10, 20, and 40 mg/kg/day) once daily for eight consecutive days. One hour following the last injection, the control group was injected into the abdominal cavity with 0.1 ml/100 g of peanut oil, and the other four groups got the same amount of a peanut oil solution containing 50% CCl4. Liver indexes were detected in rats after dissection, and hematoxylin and eosin (HE) dyeing was utilized to determine HSYA’s impact on the liver of model rats. In addition, with RNA-Sequencing (RNA-Seq) technology and quantitative real-time PCR (qRT-PCR), differentially expressed genes (DEGs) were discovered and validated. Furthermore, we detected the contents of anti-superoxide anion (anti-O2−) and hydrogen peroxide (H2O2), and verified three inflammatory genes (Icam1, Bcl2a1, and Ptgs2) in the NF-kB pathway by qRT-PCR.

Results: Relative to the control and HSYA groups, in the model group, we found 1111 DEGs that were up-/down-regulated, six of these genes were verified by qRT-PCR, including Tymp, Fabp7, Serpina3c, Gpnmb, Il1r1, and Creld2, indicated that these genes were obviously involved in the regulation of HSYA in ALI model. Membrane rafts, membrane microdomains, inflammatory response, regulation of cytokine production, monooxygenase activity, and iron ion binding were significantly enriched in GO analysis. KEGG analysis revealed that DEGs were primarily enriched for PPAR, retinol metabolism, NF-kB signaling pathways, etc. Last but not least, compared with the control group, the anti-O2− content was substantially decreased, the H2O2 content and inflammatory genes (Icam1, Bcl2a1, and Ptgs2) levels were considerably elevated in the model group. Compared with the model group, the anti-O2− content was substantially increased, the H2O2 content and inflammatory genes (Icam1, Bcl2a1, and Ptgs2) levels were substantially decreased in the HSYA group (p &lt; 0.05).

Conclusion: HSYA could improve liver function, inhibit oxidative stress and inflammation, and improve the degree of liver tissue damage. The RNA-Seq results further verified that HSYA has the typical characteristics of numerous targets and multiple pathway. Protecting the liver from damage by regulating the expression of Tymp, Fabp7, Serpina3c, Gpnmb, Il1r1, Creld2, and the PPAR, retinol metabolism, NF-kappa B signaling pathways.

Hepatic interleukin-1 receptor type 1 signalling regulates insulin sensitivity in the early phases of nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with hepatic as well as systemic insulin resistance even in the absence of type 2 diabetes. The extent and pathways through which hepatic inflammation modulates insulin sensitivity in NAFLD are only partially understood. We explored the contribution of hepatic interleukin (IL)-1 signalling in a novel conditional knockout mouse model and expand the knowledge on this signalling pathway with regard to its liver-specific functions.

METHODS

A high-fat, high-carbohydrate diet (HFD) over 12 weeks was used in male hepatocyte-specific IL-1 receptor type 1 (IL-1R1) knockout mice (Il1r1Hep-/- ) and wild-type (WT) littermates.

RESULTS

Both genotypes developed an obese phenotype and accompanying macrovesicular hepatic steatosis. In contrast to WT mice, microvesicular steatosis and ballooning injury was less pronounced in HFD-fed Il1r1Hep-/- mice, and alanine aminotransferase remained in the normal range. This was paralleled by the suppression of injurious and proinflammatory hepatic c-Jun N-terminal kinases and extracellular signal-regulated kinases signalling, stable peroxisome proliferator activated receptor gamma coactivator-1alpha and farnesoid X receptor-alpha expression and preservation of mitochondrial function. Strikingly, despite HFD-feeding Il1r1Hep-/- mice remained highly insulin sensitive as indicated by lower insulin levels, homeostatic model assessment for insulin resistance, higher glucose tolerance, more stable hepatic insulin signalling cascade, and less adipose tissue inflammation compared to the WT.

CONCLUSIONS

The current data highlights that hepatocyte IL-1R1 contributes to hepatic and extrahepatic insulin resistance. Future liver-directed therapies in NAFLD could have effects on insulin sensitivity when improving hepatic inflammation and IL-1R1 signalling.

Inhibition of IL1R1 or CASP4 attenuates spinal cord injury through ameliorating NLRP3 inflammasome-induced pyroptosis

Spinal cord injury (SCI) is a devastating trauma characterized by serious neuroinflammation and permanent neurological dysfunction. However, the molecular mechanism of SCI remains unclear, and few effective medical therapies are available at present. In this study, multiple bioinformatics methods were used to screen out novel targets for SCI, and the mechanism of these candidates during the progression of neuroinflammation as well as the therapeutic effects were both verified in a rat model of traumatic SCI. As a result, CASP4, IGSF6 and IL1R1 were identified as the potential diagnostic and therapeutic targets for SCI by computational analysis, which were enriched in NF-κB and IL6-JAK-STATA3 signaling pathways. In the injured spinal cord, these three signatures were up-regulated and closely correlated with NLRP3 inflammasome formation and gasdermin D (GSDMD) -induced pyroptosis. Intrathecal injection of inhibitors of IL1R1 or CASP4 improved the functional recovery of SCI rats and decreased the expression of these targets and inflammasome component proteins, such as NLRP3 and GSDMD. This treatment also inhibited the pp65 activation into the nucleus and apoptosis progression. In conclusion, our findings of the three targets shed new light on the pathogenesis of SCI, and the use of immunosuppressive agents targeting these proteins exerted anti-inflammatory effects against spinal cord inflammation by inhibiting NF-kB and NLRP3 inflammasome activation, thus blocking GSDMD -induced pyroptosis and immune activation.

Sapidolide A alleviates acetaminophen-induced acute liver injury by inhibiting NLRP3 inflammasome activation in macrophages

Macrophages play a critical role in the pathogenesis of acetaminophen (APAP)-induced liver injury (AILI), a major cause of acute liver failure or even death. Sapidolide A (SA) is a sesquiterpene lactone extracted from Baccaurea ramiflora Lour., a folk medicine used in China to treat inflammatory diseases. In this study, we investigated whether SA exerted protective effects on macrophages, thus alleviated the secondary hepatocyte damage in an AILI. We showed that SA (5-20 μM) suppressed the phosphorylated activation of NF-κB in a dose-dependent manner, thereby inhibiting the expression and activation of the NOD-like receptor protein 3 (NLRP3) inflammasome and pyroptosis in LPS/ATP-treated mouse bone marrow-derived primary macrophages (BMDMs). In human hepatic cell line L02 co-cultured with BMDMs, SA (10 μM) protected macrophages from the pyroptosis induced by APAP-damaged L02 cells. Moreover, SA treatment reduced the secondary liver cell damage aggravated by the conditioned medium (CM) taken from LPS/ATP-treated macrophages. The in vivo assessments conducted on mice pretreated with SA (25, 50 mg/kg, ip) then with a single dose of APAP (400 mg/kg, ip) showed that SA significantly alleviated inflammatory responses of AILI by inhibiting the expression and activation of the NLRP3 inflammasome. In general, the results reported herein revealed that SA exerts anti-inflammatory effects by regulating NLRP3 inflammasome activation in macrophages, which suggests that SA has great a potential for use in the treatment of AILI patients.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

Immune suppressive function of IL-1α release in the tumor microenvironment regulated by calpain 1

Interleukin-1α (IL-1α) plays an important role in inflammation and hematopoiesis. Many tumors have increased IL-1α expression. However, the immune regulatory role of secreted IL-1α in tumor development and whether it can be targeted for cancer therapy are still unclear. Here, we found that tumoral-secreted IL-1α significantly promoted hepatocellular carcinoma (HCC) development in vivo. Tumoral-released IL-1α were found to inhibit T and NK cell activation, and the killing capacity of CD8⁺ T cells. Moreover, MDSCs were dramatically increased by tumoral-released IL-1α in both spleens and tumors. Indeed, higher tumoral IL-1α expression is associated with increased tumoral infiltration of MDSCs in HCC patients. Further studies showed that tumoral-released IL-1α promoted MDSC recruitment to the tumor microenvironment through a CXCR2-dependent mechanism. Depletion of MDSCs could diminish the tumor-promoting effect of tumoral-released IL-1α. On the contrary, systemic administration of recombinant IL-1α protein significantly inhibited tumor development by activating T cells. In fact, IL-1α protein could promote T cell activation and enhance the cytotoxicity of CD8⁺ T cells in vitro. Thus, our study demonstrated that tumoral-released IL-1α promoted tumor development through recruiting MDSCs to inhibit T cell activation, while systemic IL-1α directly promoted anti-tumor T cell responses. We further identified calpain 1 as the major intracellular protease mediating tumoral IL-1α secretion. Calpain 1 KO tumors had diminished IL-1α release and reduced tumor development. Thus, our findings provide new insights into the functions of secreted IL-1α in tumor immunity and its implications for immunotherapy.

Neutrophil Extracellular Traps Mediate Acute Liver Failure in Regulation of miR-223/Neutrophil Elastase Signaling in Mice

BACKGROUND & AIMS

Marked enhancement of neutrophil infiltration in the liver is a hallmark of acute liver failure (ALF), a severe life-threatening disease with varying etiologies. However, the mechanisms and pathophysiological role corresponding to hepatic neutrophil infiltration during ALF development remain poorly characterized.

METHODS

Experimental ALF was induced in 10-week-old male microRNA-223 (miR-223) knockout (KO) mice, neutrophil elastase (NE) KO mice, and wild-type controls by intraperitoneal injection of galactosamine hydrochloride and lipopolysaccharide. Age-matched mice were injected with phosphate-buffered saline and served as vehicle controls.

RESULTS

Mouse liver with ALF showed evident formation of neutrophil extracellular traps (NETs), which were enhanced markedly in miR-223 KO mice. The blockade of NETs by pharmacologic inhibitor GSK484 significantly attenuated neutrophil infiltration and massive necrosis in mouse liver with ALF. ALF-related hepatocellular damage and mortality in miR-223 KO mice were aggravated significantly and accompanied by potentiated neutrophil infiltration in the liver when compared with wild-type controls. Transcriptomic analyses showed that miR-223 deficiency in bone marrow predominantly caused the enrichment of pathways involved in neutrophil degranulation. Likewise, ALF-induced hepatic NE enrichment was potentiated in miR-223 KO mice. Genetic ablation of NE blunted the formation of NETs in parallel with significant attenuation of ALF in mice. Pharmaceutically, pretreatment with the NE inhibitor sivelestat protected mice against ALF.

CONCLUSIONS

The present study showed the miR-223/NE axis as a key modulator of NETs, thereby exacerbating oxidative stress and neutrophilic inflammation to potentiate hepatocellular damage and liver necrosis in ALF development, and offering potential targets against ALF.

Hepatocyte Bcl-3 protects from death-receptor mediated apoptosis and subsequent acute liver failure

Acute liver failure (ALF) is a rare entity but exhibits a high mortality. The mechanisms underlying ALF are not completely understood. The present study explored the role of the hepatic B cell leukemia-3 (Bcl-3), a transcriptional regulator of nuclear factor-kappa B (NF-κB), in two independent models of ALF. We employed a recently developed transgenic mouse model in a C57BL6/J background comparing wild-type (WT) and transgenic littermates with hepatocyte-specific overexpression of Bcl-3 (Bcl-3Hep) in the ALF model of d-galactosamine (d-GalN) and lipopolysaccharide (LPS). Additionally, the apoptosis-inducing CD95 (FAS/APO-1)-ligand was explored. Bcl-3Hep mice exhibited a significant protection from ALF with decreased serum transaminases, decreased activation of the apoptotic caspases 8, 9, and 3, lower rates of oxidative stress, B-cell lymphoma 2 like 1 (BCL2L1/BCL-XL) degradation and accompanying mitochondrial cytochrome c release, and ultimately a decreased mortality rate from d-GalN/LPS compared to WT mice. d-GalN/LPS treatment resulted in a marked inflammatory cytokine release and stimulated the activation of signal transducer and activator of transcription (STAT) 3, c-Jun N-terminal kinases (JNK) and extracellular signal-regulated kinase (ERK) signaling comparably in the hepatic compartment of Bcl-3Hep and WT mice. However, in contrast to the WT, Bcl-3Hep mice showed a diminished rate of IkappaB kinase-beta (IKK-β) degradation, persistent receptor interacting protein kinase (RIPK) 1 function and thus prolonged cytoprotective nuclear factor-kappa B (NF-κB) p65 signaling through increased p65 stability and enhanced transcription. Likewise, Bcl-3 overexpression in hepatocytes protected from ALF with massive hepatocyte apoptosis induced by the anti-FAS antibody Jo2. The protection was also linked to IKK-β stabilization. Overall, our study showed that Bcl-3 rendered hepatocytes more resistant to hepatotoxicity induced by d-GalN/LPS and FAS-ligand. Therefore, Bcl-3 appears to be a critical regulator of the dynamics in ALF through IKK-β.

Crosstalk of hepatocyte nuclear factor 4a and glucocorticoid receptor in the regulation of lipid metabolism in mice fed a high-fat-high-sugar diet

Background

Hepatocyte nuclear factor 4α (HNF4α) and glucocorticoid receptor (GR), master regulators of liver metabolism, are down-regulated in fatty liver diseases. The present study aimed to elucidate the role of down-regulation of HNF4α and GR in fatty liver and hyperlipidemia.

Methods

Adult mice with liver-specific heterozygote (HET) and knockout (KO) of HNF4α or GR were fed a high-fat-high-sugar diet (HFHS) for 15 days. Alterations in hepatic and circulating lipids were determined with analytical kits, and changes in hepatic mRNA and protein expression in these mice were quantified by real-time PCR and Western blotting. Serum and hepatic levels of bile acids were quantified by LC-MS/MS. The roles of HNF4α and GR in regulating hepatic gene expression were determined using luciferase reporter assays.

Results

Compared to HFHS-fed wildtype mice, HNF4α HET mice had down-regulation of lipid catabolic genes, induction of lipogenic genes, and increased hepatic and blood levels of lipids, whereas HNF4α KO mice had fatty liver but mild hypolipidemia, down-regulation of lipid-efflux genes, and induction of genes for uptake, synthesis, and storage of lipids. Serum levels of chenodeoxycholic acid and deoxycholic acid tended to be decreased in the HNF4α HET mice but dramatically increased in the HNF4α KO mice, which was associated with marked down-regulation of cytochrome P450 7a1, the rate-limiting enzyme for bile acid synthesis. Hepatic mRNA and protein expression of sterol-regulatory-element-binding protein-1 (SREBP-1), a master lipogenic regulator, was induced in HFHS-fed HNF4α HET mice. In reporter assays, HNF4α cooperated with the corepressor small heterodimer partner to potently inhibit the transactivation of mouse and human SREBP-1C promoter by liver X receptor. Hepatic nuclear GR proteins tended to be decreased in the HNF4α KO mice. HFHS-fed mice with liver-specific KO of GR had increased hepatic lipids and induction of SREBP-1C and PPARγ, which was associated with a marked decrease in hepatic levels of HNF4α proteins in these mice. In reporter assays, GR and HNF4α synergistically/additively induced lipid catabolic genes.

Conclusions

induction of lipid catabolic genes and suppression of lipogenic genes by HNF4α and GR may mediate the early resistance to HFHS-induced fatty liver and hyperlipidemia.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01654-6.

Selective bromodomain and extra-terminal bromodomain inhibitor inactivates macrophages and hepatic stellate cells to inhibit liver inflammation and fibrosis

Liver fibrosis occurs following inflammation triggered by the integrated actions of activated liver-resident macrophages (Kupffer cells) and hepatic stellate cells (HSCs), and the multiplicity of these mechanisms complicates drug therapy. Here, we demonstrate that the selective bromodomain and extra-terminal (BET) bromodomain inhibitor compound38 can block both the Janus kinase-signal transducer and activator of transcription and mitogen-activated protein kinase signaling pathways in macrophages, which decreased their secretion of proinflammatory cytokines in a dose-dependent manner. The inactivation of macrophages attenuated lipopolysaccharide-induced injurious inflammation concurrent with a reduction in F4/80+ cells, proinflammatory cytokine levels, and neutrophil infiltration. Moreover, compound 38 inhibited the Wnt/β-catenin and transforming growth factor-beta/SMAD signaling pathways to abolish the activation of HSCs. In vivo, compound 38 significantly decreased the collagen deposition and fibrotic area of a CCl₄-induced liver fibrosis model, and restored the deficiency of activated HSCs and the upregulation of liver inflammation. These results highlight the potential role of compound 38 in treating liver fibrosis considering its simultaneous inhibitory effects on liver inflammation and related fibrosis.

Standard-Volume Plasma Exchange Improves Outcomes in Patients With Acute Liver Failure: A Randomized Controlled Trial

BACKGROUND

High volume plasma-exchange (HVPE) improves survival in patients with acute liver failure (ALF), but apprehension regarding volume overload and worsening of cerebral edema remain.

METHODS

In an open-label randomized controlled trial, 40 consecutive patients of ALF were randomized 1:1 to either standard medical treatment (SMT) or SMT with standard-volume plasma-exchange (SVPE). SVPE was performed using centrifugal apheresis [target volume of 1.5 to 2.0 plasma volumes per session] until desired response was achieved. Cerebral edema was assessed by brain imaging. Results were analyzed in an intention-to-treat analysis. Primary outcome was 21-day transplant-free survival. The levels of cytokines, damage-associated molecular patterns (DAMPs) and endotoxins were analyzed at baseline and day 5.

RESULTS

ALF patients [aged 31.5 ± 12.2 years, 60% male, 78% viral, 83% hyperacute, 70% with SIRS were included. At day 5, SVPE [mean sessions 2.15 ± 1.42, median plasma volume replaced 5.049 L] compared to SMT alone, resulted in higher lactate clearance (p = .02), amelioration of SIRS (84% vs. 26%; P = .02), reduction in ammonia levels [(221.5 ± 96.9) vs.(439 ± 385.6) μg/dl, P = .02) and SOFA scores [9.9(±3.3) vs. 14.6(±4.8); P = .001]. There were no treatment related deaths. SVPE was associated with a higher 21-day transplant free-survival [75% vs. 45%; P = .04, HR 0.30, 95%CI 0.01-0.88]. A significant decrease in levels of pro-inflammatory cytokines and an increase in anti-inflammatory cytokines along with a decrease in endotoxin and DAMPs was seen with SVPE.

CONCLUSION

In ALF patients with cerebral edema, SVPE is safe and effective and improves survival possibly by a reduction in cytokine storm and ammonia.

CLINICALTRIAL

gov (identifier: NCT02718079).

Nonredundancy of IL-1α and IL-1β is defined by distinct regulation of tissues orchestrating resistance versus tolerance to infection

Interleukin-1α (IL-1α) and IL-1β are inflammatory cytokines with important roles in health and disease. They trigger the same receptor and elicit comparable cellular responses but, for poorly understood reasons, are not redundant in vivo. Here, we decoupled IL-1α and IL-1β functions that drive protective responses against invasive infection with group A Streptococcus. IL-1β was essential for pathogen clearance, hence resistance to infection, by inducing granulocyte colony-stimulating factor at the infection site and establishing emergency granulopoiesis. In contrast, IL-1α governed reprogramming of liver metabolic pathways associated with tolerance to infection. The IL-1α-dominated hepatic regulation corresponded to high IL-1α levels in the liver during infection. Conversely, IL-1β was critical for the regulation of the spleen transcriptome, which correlated with ample IL-1β expression in this tissue. The results identify distinct and organ-specific roles of IL-1α versus IL-1β and implicate spatial restriction of their expression and bioavailability during infection as the underlying mechanism.

Milk Fat Globule Membrane Alleviates Short Bowel Syndrome-Associated Liver Injury in Rats Through Inhibiting Autophagy and NLRP3 Inflammasome Activation

Background

The milk fat globule membrane (MFGM), a tri-layer membrane structure surrounding the milk fat globule, has been shown to have immune-modulating properties. This study aimed to investigate the effects of MFGM supplementation in a rat model of short bowel syndrome (SBS) associated liver disease and its possible mechanisms.

Materials and Methods

Twenty one male Sprague-Dawley rats were randomly divided into three groups: Sham, SBS (underwent massive small bowel resection), and SBS+MFGM (SBS rats supplemented with 1.5 g/kg/d MFGM). Liver pathology, myeloperoxidase (MPO) staining, serum levels of aspartate aminotransferase (AST)/alanine aminotransferase (ALT), endotoxin concentration, protein expression of autophagy and nucleotide binding oligomerization domain, leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) pathway in the liver tissue were measured.

Results

Both SBS and SBS + MFGM groups had higher serum levels of ALT and liver endotoxin levels than the Sham group (P < 0.05), with no difference detected between each other. Compared with the SBS group, the SBS+MFGM group showed lower liver pathology scores of steatosis and inflammation, less MPO positive cells and reduced expressions of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), Caspase-1, interleukin (IL)-1β(P < 0.05) in the liver. Additionally, the expression of Beclin-1 and microtubule-associated protein1 light chain 3(LC3) B, the fluorescence intensity of NLRP3 and LC3B in the SBS + MFGM group were lower than the SBS group (P < 0.05). The LC3B expression was positively correlated with the NLRP3 level.

Conclusion

Enteral supplementation of MFGM help to alleviate liver injury in SBS rats, which might be related to inhibition of aberrant activation of autophagy and NLRP3 inflammasome pathways.

The dynamics of cell death patterns and regeneration during acute liver injury in mice

Acute liver injury is a serious clinical syndrome with multiple causes and unclear pathological process. Here, CCl₄‐ and D‐galactosamine/lipopolysaccharide (D‐gal/LPS)‐induced acute liver injury was established to explore the cell death patterns and determine whether or not liver regeneration occurred. In CCl₄‐induced hepatic injury, three phases, including the early, progressive, and recovery phase, were considered based on alterations of serum transaminases and liver morphology. Moreover, in this model, cytokines exhibited double‐peak fluctuations; apoptosis and pyroptosis persisted throughout all phases; autophagy occurred in the early and the progressive phases; and sufficient and timely hepatocyte regeneration was observed only during the recovery phase. All of these phenomena contribute to mild liver injury and subsequent regeneration. Strikingly, only the early and progressive phases were observed in the D‐gal/LPS model. Slight pyroptosis occurred in the early phase but diminished in the progressive phase, while apoptosis, reduced autophagy, and slight but subsequently diminished regeneration occurred only during the progressive phase, accompanied by a strong cytokine storm, resulting in severe liver injury with high mortality. Taken together, our work reveals variable modes and dynamics of cell death and regeneration, which lead to different consequences for mild and severe acute liver injury, providing a helpful reference for clinical therapy and prognosis.

Adipose-Derived Mesenchymal Stromal/Stem Cell Line Prevents Hepatic Ischemia/Reperfusion Injury in Rats by Inhibiting Inflammasome Activation

Mesenchymal stromal/stem cells (MSCs) have shown potential in the treatment of degenerative diseases, including ischemia/reperfusion injury (IRI), which occurs during organ transplantation and represents the main cause of post-transplant graft dysfunction. However, MSCs have heterogeneous characteristics, and studies of MSCs therapy have shown a variety of outcomes. To establish a new effective MSCs therapy, we developed an adipose-derived mesenchymal stromal/stem cell line (ASCL) and compared its therapeutic effects on primary adipose-derived MSCs (ASCs) using a hepatocyte co-culture model of hypoxia/reoxygenation in vitro and a rat model of hepatic IRI in vivo. The results showed that both ASCL and ASCs protect against hypoxia by improving hepatocyte viability, inhibiting reactive oxygen species release, and upregulating transforming growth factor-β in vitro. In vivo, ASCL or ASCs were infused into the spleen 24 h before the induction of rat hepatic IRI. The results showed that ASCL significantly improved the survival outcomes compared with the control (normal saline infusion) with the significantly decreased serum levels of liver enzymes and less damage to liver tissues compared with ASCs. Both ASCL and ASCs suppressed NOD-like receptor family pyrin domain-containing 3 inflammasome activation and subsequently reduced the release of activated IL-1β and IL-18, which is considered an important mechanism underlying ASCL and ASCs infusion in hepatic IRI. In addition, ASCL can promote the release of interleukin-1 receptor antagonist, which was previously reported as a key factor in hampering the inflammatory cascade during hepatic IRI. Our results suggest ASCL as a new candidate for hepatic IRI treatment due to its relatively homogeneous characteristics.

Mechanistic insights into the peroxisome proliferator-activated receptor alpha as a transcriptional suppressor

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent hepatic disorders that 20-30% of the world population suffers from. The feature of NAFLD is excess lipid accumulation in the liver, exacerbating multiple metabolic syndromes such as hyperlipidemia, hypercholesterolemia, hypertension, and type 2 diabetes. Approximately 20-30% of NAFLD cases progress to more severe chronic hepatitis, known as non-alcoholic steatohepatitis (NASH), showing deterioration of hepatic functions and liver fibrosis followed by cirrhosis and cancer. Previous studies uncovered that several metabolic regulators had roles in disease progression as key factors. Peroxisome proliferator-activated receptor alpha (PPARα) has been identified as one of the main players in hepatic lipid homeostasis. PPARα is abundantly expressed in hepatocytes, and is a ligand-dependent nuclear receptor belonging to the NR1C nuclear receptor subfamily, orchestrating lipid/glucose metabolism, inflammation, cell proliferation, and carcinogenesis. PPARα agonists are expected to be novel prescription drugs for NASH treatment, and some of them (e.g., Lanifibranor) are currently under clinical trials. These potential novel drugs are developed based on the knowledge of PPARα-activating target genes related to NAFLD and NASH. Intriguingly, PPARα is known to suppress the expression of subsets of target genes under agonist treatment; however, the mechanisms of PPARα-mediated gene suppression and functions of these genes are not well understood. In this review, we summarize and discuss the mechanisms of target gene repression by PPARα and the roles of repressed target genes on hepatic lipid metabolism, fibrosis and carcinogenesis related to NALFD and NASH, and provide future perspectives for PPARα pharmaceutical potentials.

Human umbilical cord mesenchymal stem cells ameliorate acute liver failure by inhibiting apoptosis, inflammation and pyroptosis

Background

Human umbilical cord mesenchymal stem cells (UC-MSCs) are multipotent progenitor cells representing an attractive therapeutic tool for tissue damage and inflammation owing to their unique immunomodulatory properties. This study was designed to determine the protective effects and underlying mechanisms of UC-MSCs on acute liver failure (ALF).

Methods

ALF was induced in mice by intraperitoneal injection of D-galactosamine (D-GalN) and lipopolysaccharide (LPS). Mice were intravenously injected with 1×10⁶ UC-MSCs one hour before or six hours after D-GalN/LPS injection. Liver function was valued by serum biochemical parameters and hematoxylin-eosin staining. Inflammatory cytokine and chemokine levels were measured by real-time PCR, and inflammatory cells infiltration was observed by immunofluorescence staining. Hepatocyte apoptosis and pyroptosis related proteins were detected by western blot. Murine macrophage Raw264.7 in the presentation of LPS was treated with the UC-MSCs condition medium (UC-MSCs-CM), and then the levels of inflammatory cytokines and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in Raw264.7 were measured.

Results

UC-MSCs significantly reduced the mortality, decreased serum alanine aminotransferase and aspartate aminotransferase levels, and improved the pathological damage. Moreover, UC-MSCs inhibited inflammatory cytokine and chemokine levels, especially TNF-α, interleukins-6 (IL-6), IL-1β, monocyte chemoattractant protein (MCP-1), CC-chemokines ligand 2 (CCL2), C-X-C motif ligand 2 (CXCL2), and reduced macrophage, neutrophil and T lymphocyte infiltration into the liver tissue. UC-MSCs also attenuated hepatocyte apoptosis, as evidenced by decreased TUNEL positive cells, increased Bcl-xl/Bax protein ratio and downregulated cleaved caspase 3 levels. NLRP3 inflammasome activation, IL-1β maturation and cleaved caspase1 were suppressed by UC-MSC administration. Furthermore, the UC-MSCs-CM reduced the levels of inflammatory cytokines and the activation of NLRP3 inflammasome in Raw264.7.

Conclusions

Our results demonstrated that UC-MSCs exerted therapeutic effects on ALF by inhibiting apoptosis, inflammation, and pyroptosis.

lncRNA CASC7 regulates pathological progression of ox-LDL-stimulated atherosclerotic cell models via sponging miR-21 and regulating PI3K/Akt and TLR4/NF-κB signaling pathways

Atherosclerosis (AS) is a frequently occurring cause of cardiovascular disease and involves a complicated pathophysiological process. Studies suggest that long non-coding RNAs (lncRNAs) are involved in AS genesis and progression, but mechanisms underlying these connections are unclear. Therefore, this work focused on exploring the role of lncRNA CASC7 in AS. In this study, RNA-seq sequencing results identified 1040 lncRNAs differentially expressed between AS patients and healthy controls. Of these lncRNAs, 458 were up-regulated and 582 were downregulated. CASC7 was found to be down-regulated in serum samples from AS patients and in HUVEC and VSMC exposed to ox-LDL. Overexpression of CASC7 inhibited proliferation and enhanced apoptosis of VSMC, and it markedly reduced IL-1β, IL-6 and TNF-α levels in HUVEC. Increased expression of a CASC7 target, miR-21, abolished the effects of CASC7 on HUVEC and VSMC. Notably, miR-21 targets PI3K in VSMC and TLR4 in HUVEC. The inhibitory effect of CASC7 was decreased by stimulation of PI3K, suggesting that the CASC7/miR-21 axis functions through PI3K/Akt signaling in VSMC. Similarly, the inhibitory effect of CASC7 on the inflammatory response in HUVEC was abolished through activating the TLR4/NF-κB signaling pathway. CASC7 inhibited proliferation and enhanced the apoptosis of VSMC through modulating the miR-21/PI3K-AKT axis, and upregulating CASC7 suppressed the inflammatory response of HUVEC by sponging miR-21 to inhibit the TLR4/NF-κB signal pathway.

Convallatoxin inhibits IL-1β production by suppressing zinc finger protein 91-mediated pro-IL-1β ubiquitination and caspase-8 inflammasome activity

BACKGROUND AND PURPOSE

ZFP91 positively regulates IL-1β production in macrophages and may be a potential therapeutic target to treat inflammatory-related diseases. Therefore, we investigated whether this process is modulated by convallatoxin, which is a cardiac glycoside isolated from the traditional Chinese medicinal plant Adonis amurensis Regel et Radde.

EXPERIMENTAL APPROACH

In vitro, the underlying mechanisms by which convallatoxin inhibits ZFP91-regulated IL-1β expression were investigated using molecular docking, western blotting, RT-PCR, ELISA, immunofluorescence, and immunoprecipitation assays. In vivo, liver injury was induced by an intraperitoneal injection of D-GalN and LPS, colitis was induced by oral administration of DSS in drinking water, and peritonitis was induced by an intraperitoneal injection of alum.

KEY RESULTS

We confirmed that convallatoxin inhibited the release of IL-1β by downregulating ZFP91. Importantly, we found that convallatoxin significantly reduced K63-linked polyubiquitination of pro-IL-1β regulated by ZFP91 and decreased the efficacy of pro-IL-1β cleavage. Moreover, convallatoxin suppressed ZFP91-mediated activation of the non-canonical caspase-8 inflammasome and MAPK signaling pathways in macrophages. Furthermore, we showed that ZFP91 promoted the assembly of the caspase-8 inflammasome complex, whereas convallatoxin treatment reversed this result. In vivo studies further demonstrated that convallatoxin ameliorated D-GalN/LPS-induced liver injury, DSS-induced colitis, and alum-induced peritonitis by downregulating ZFP91.

CONCLUSION AND IMPLICATIONS

We report for the first time that convallatoxin-mediated inhibition of ZFP91 is an important regulatory event that prevents inappropriate inflammatory responses to maintain of immune homeostasis. This mechanism provides new perspectives for the development of convallatoxin as a novel anti-inflammatory drug targeting ZFP91.

Plasma Exchange in Acute and Acute on Chronic Liver Failure

Liver failure in the context of acute (ALF) and acute on chronic liver failure (ACLF) is associated with high mortality in the absence of a liver transplant. For decades, therapeutic plasma exchange (TPE) is performed for the management of immune-mediated diseases. TPE has emerged as an attractive extracorporeal blood purification technique in patients with ALF and ACLF. The basic premise of using TPE is to remove the toxic substances which would allow recovery of native liver functions by facilitating liver regeneration. In recent years, encouraging data have emerged, suggesting the benefits of TPE in patients with liver failure. TPE has emerged as an attractive liver support device for the failing liver until liver transplantation or clinical recovery. The data in patients with ALF suggest routine use of high-volume TPE, while the data for such a strategy are less robust for patients with ACLF.

A narrative review of liver regeneration-from models to molecular basis

Objective

To elucidate the characteristics of different liver regeneration animal models, understand the activation signals and mechanisms related to liver regeneration, and obtain a more comprehensive conception of the entire liver regeneration process.

Background

Liver regeneration is one of the most enigmatic and fascinating phenomena of the human organism. Despite suffering significant injuries, the liver still can continue to perform its complex functions through the regeneration system. Although advanced topics on liver regeneration have been proposed; unfortunately, complete regeneration of the liver has not been achieved until now. Therefore, increasing understanding of the liver regenerative process can help improve our treatment of liver failure. It will provide a new sight for the treatment of patients with liver injury in the clinic.

Methods

Literatures on liver regeneration animal models and involved basic research on molecular mechanisms were retrieved to analyze the characteristics of different models and those related to molecular basis.

Conclusions

The process of liver regeneration is complex and intricate, consisting of various and interactive pathways. There is sufficient evidence to demonstrate that liver regeneration is similar between humans and rodents. At the same time, many of the same cytokines, growth factors, and signaling pathways are relevant. There are many gaps in our current knowledge. Understanding of this knowledge will provide more supportive clinical treatment strategies, including small-scale liver transplantation and high-quality regenerative process after surgical resection, and offer possible targets to treat the dysregulation of regeneration that occurs in chronic hepatic diseases and tumors. Current research work, such as the use of animal models as in vivo vectors for high-quality human hepatocytes, represents a unique and significant cutting edge in the field of liver regeneration.