Inhibition of heat shock protein 90 alleviates steatosis and macrophage activation in murine alcoholic liver injury

Gkongensin A, an HSP90β inhibitor, improves hyperlipidemia, hepatic steatosis, and insulin resistance

The prevalence of obesity and its primary associated comorbidities, such as type 2 diabetes and fatty liver disease, has reached epidemic proportions, with no successful treatment available at present. Heat shock protein 90 (HSP90), a crucial chaperone, plays a key role in de novo lipogenesis (DNL) by stabilizing and maintaining sterol regulatory element binding protein (SREBP) activity. Kongensin A (KA), derived from Croton kongensis, inhibits RIP3-mediated necrosis, showing promise as an anti-necrotic and anti-inflammatory agent. It is not yet clear if KA, acting as an HSP90 inhibitor, can enhance hyperlipidemia, hepatic steatosis, and insulin resistance in obese individuals by controlling lipid metabolism. In this study, we first found that KA can potentially decrease lipid content at the cellular level. C57BL/6J mice were given a high-fat diet (HFD) and received KA and lovastatin through oral administration for 7 weeks. KA improved hyperlipidemia, fatty liver, and insulin resistance, as well as reduced body weight in diet-induced obese (DIO) mice, with no significant alteration in food intake. In vitro, KA suppressed DNL and reduced the amounts of mSREBPs. KA promoted mSREBP degradation via the FBW7-mediated ubiquitin-proteasome pathway. KA decreased the level of p-Akt Ser308, and p-GSK3β Ser9 by inhibiting the interaction between HSP90β and Akt. Overall, KA enhanced hyperlipidemia, hepatic steatosis, and insulin resistance by blocking SREBP activity, thereby impacting the FBW7-controlled ubiquitin-proteasome pathway.

HSP90a promotes the resistance to oxaliplatin in HCC through regulating IDH1-induced cell competition

Though burgeoning research manifests that cell competition, an essential selection and quality control mechanism for maintaining tissue or organ growth and homeostasis in multicellular organisms, is closely related to tumorigenesis and development, the mechanism of cell competition associated with tumor drug resistance remains elusive. In the study, we uncovered that oxaliplatin-resistant hepatocellular carcinoma (HCC) cells exhibit a pronounced competitive advantage against their sensitive counterparts, which is related to lipid takeover of resistant cells from sensitive cells. Of note, such lipid takeover is dependent on the existence of isocitrate dehydrogenase 1 (IDH1) in resistant HCC cells. Mechanistically, IDH1 activity is regulated by heat shock protein 90 alpha (HSP90α) through binding with each other, which orchestrates the expressions of lipid metabolic enzymes and lipid accumulation in resistant HCC cells. Our results suggest that HCC cell competition-driven chemoresistance can be regulated by HSP90α/IDH1-mediated lipid metabolism, which may serve as a promising target for overcoming drug resistance in HCC.

Steroid responsiveness in alcohol-associated hepatitis is linked to glucocorticoid metabolism, mitochondrial repair, and heat shock proteins

BACKGROUND

Alcohol-associated hepatitis (AH) is one of the clinical presentations of alcohol-associated liver disease. AH has poor prognosis, and corticosteroids remain the mainstay of drug therapy. However, ~40% of patients do not respond to this treatment, and the mechanisms underlying the altered response to corticosteroids are not understood. The current study aimed to identify changes in hepatic protein expression associated with responsiveness to corticosteroids and prognosis in patients with AH.

METHODS

Patients with AH were enrolled based on the National Institute on Alcohol Abuse and Alcoholism inclusion criteria for acute AH and further confirmed by a diagnostic liver biopsy. Proteomic analysis was conducted on liver samples acquired from patients with AH grouped as nonresponders (AH-NR, n = 7) and responders (AH-R, n = 14) to corticosteroids, and nonalcohol-associated liver disease controls (n = 10). The definition of responders was based on the clinical prognostic model, the Lille Score, where a score < 0.45 classified patients as AH-R and a score > 0.45 as AH-NR. Primary outcomes used to assess steroid response were Lille Score (eg, improved liver function) and survival at 24 weeks.

RESULTS

Reduced levels of the glucocorticoid receptor and its transcriptional co-activator, glucocorticoid modulatory element-binding protein 2, were observed in the hepatic proteome of AH-NR versus AH-R. The corticosteroid metabolizing enzyme, 11-beta-hydroxysteroid dehydrogenase 1, was increased in AH-NR versus AH-R along with elevated mitochondrial DNA repair enzymes, while several proteins of the heat shock pathway were reduced. Analysis of differentially expressed proteins in AH-NR who survived 24 weeks relative to AH-NR nonsurvivors revealed several protein expression changes, including increased levels of acute phase proteins, elevated coagulation factors, and reduced mast cell markers.

CONCLUSIONS

This study identified hepatic proteomic changes that may predict responsiveness to corticosteroids and mortality in patients with AH.

Decoding the roles of heat shock proteins in liver cancer

Hepatocellular carcinoma (HCC) is one of the most common gastrointestinal malignancies, characterized by insidious onset and high propensity for metastasis and recurrence. Apart from surgical resection, there are no effective curative methods for HCC in recent years, due to resistance to radiotherapy and chemotherapy. Heat shock proteins (HSP) play a crucial role in maintaining cellular homeostasis and normal organism development as molecular chaperones for intracellular proteins. Both basic research and clinical data have shown that HSPs are crucial participants in the HCC microenvironment, as well as the occurrence, development, metastasis, and resistance to radiotherapy and chemotherapy in various malignancies, particularly liver cancer. This review aims to discuss the molecular mechanisms and potential clinical value of HSPs in HCC, which may provide new insights for HSP-based therapeutic interventions for HCC.

Albumosomes formed by cytoplasmic pre-folding albumin maintain mitochondrial homeostasis and inhibit nonalcoholic fatty liver disease

Hepatic mitochondrial dysfunction contributes to the progression of nonalcoholic fatty liver disease (NAFLD). However, the factors that maintain mitochondrial homeostasis, especially in hepatocytes, are largely unknown. Hepatocytes synthesize various high-level plasma proteins, among which albumin is most abundant. In this study, we found that pre-folding albumin in the cytoplasm is completely different from folded albumin in the serum. Mechanistically, endogenous pre-folding albumin undergoes phase transition in the cytoplasm to form a shell-like spherical structure, which we call the "albumosome". Albumosomes interact with and trap pre-folding carnitine palmitoyltransferase 2 (CPT2) in the cytoplasm. Albumosomes control the excessive sorting of CPT2 to the mitochondria under high-fat-diet-induced stress conditions; in this way, albumosomes maintain mitochondrial homeostasis from exhaustion. Physiologically, albumosomes accumulate in hepatocytes during murine aging and protect the livers of aged mice from mitochondrial damage and fat deposition. Morphologically, mature albumosomes have a mean diameter of 4μm and are surrounded by heat shock protein Hsp90 and Hsp70 family proteins, forming a larger shell. The Hsp90 inhibitor 17-AAG promotes hepatic albumosomal accumulation in vitro and in vivo, through which suppressing the progression of NAFLD in mice.

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

An iron-deficient diet prevents alcohol- or diethylnitrosamine-induced acute hepatotoxicity in mice by inhibiting ferroptosis

The liver is easily injured by exogenous chemicals through reactive oxygen species (ROS), which lead to ferroptosis, a ROS-dependent programmed cell death characterized by iron accumulation and lipid peroxidation. However, whether iron restriction has a positive role in chemicals-induced liver injuries is unknown. The present study investigated the effects of an iron-deficient diet on liver injuries induced by alcohol or diethylnitrosamine (DEN). Mice were fed an iron-deficient diet for four weeks, then treated with three doses of alcohol (5 g/kg, 24 h interval, gavage) to mimic mild liver injury or five doses of DEN (50 mg/kg, 24 h interval, i. p.) to mimic severe liver failure. The results showed that mice were iron-deficient after four weeks of feeding. Interestingly, as evaluated by H&E staining of liver slices, liver/body weight ratio, serum ALT and AST, iron deficiency significantly alleviated liver injuries triggered by alcohol or DEN. The activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), and the expression of CYP2E1 were increased by iron deficiency. Mechanistically, iron deficiency prevented the decrease of glutathione peroxidase 4 (GPX4), which eliminated malondialdehyde (MDA) by utilizing glutathione (GSH). In summary, alcohol- or DEN-induced liver injuries were mitigated by the iron-deficient diet by inhibiting ferroptosis, which might be a promising measure for preventing liver injuries induced by alcohol, DEN, or other exogenous chemicals.

Impact of preweaning vaccination on host gene expression and antibody titers in healthy beef calves

The impact of preweaning vaccination for bovine respiratory viruses on cattle health and subsequent bovine respiratory disease morbidity has been widely studied yet questions remain regarding the impact of these vaccines on host response and gene expression. Six randomly selected calves were vaccinated twice preweaning (T1 and T3) with a modified live vaccine for respiratory pathogens and 6 randomly selected calves were left unvaccinated. Whole blood samples were taken at first vaccination (T1), seven days later (T2), at revaccination and castration (T3), and at weaning (T4), and utilized for RNA isolation and sequencing. Serum from T3 and T4 was analyzed for antibodies to BRSV, BVDV1a, and BHV1. Sequenced RNA for all 48 samples was bioinformatically processed with a HISAT2/StringTie pipeline, utilizing reference guided assembly with the ARS-UCD1.2 bovine genome. Differentially expressed genes were identified through analyzing the impact of time across all calves, influence of vaccination across treatment groups at each timepoint, and the interaction of time and vaccination. Calves, regardless of vaccine administration, demonstrated an increase in gene expression over time related to specialized proresolving mediator production, lipid metabolism, and stimulation of immunoregulatory T-cells. Vaccination was associated with gene expression related to natural killer cell activity and helper T-cell differentiation, enriching for an upregulation in Th17-related gene expression, and downregulated genes involved in complement system activity and coagulation mechanisms. Type-1 interferon production was unaffected by the influence of vaccination nor time. To our knowledge, this is the first study to evaluate mechanisms of vaccination and development in healthy calves through RNA sequencing analysis.

Systematic characterization of Puerariae Flos metabolites in vivo and assessment of its protective mechanisms against alcoholic liver injury in a rat model

Puerariae Flos, a representative homology plant of medicine and food for alcoholism, has a long history of clinical experience and remarkable curative effect in the treatment of alcoholic liver disease (ALD). However, its effective forms and hepatoprotective mechanisms remain unknown. In the present study, a strategy based on UPLC-QTOF MS combined with mass defect filtering technique was established for comprehensive mapping of the metabolic profile of PF in rat plasma, urine, bile, and feces after oral administration. Furthermore, the absorbed constituents into plasma and bile with a relatively high level were subjected to the network analysis, functional enrichment analysis, and molecular docking to clarify the potential mechanism. Finally, the therapeutic effect of PF on ALD and predicted mechanisms were further evaluated using a rat model of alcohol-induced liver injury and Western blot analysis. In total, 25 prototype components and 82 metabolites, including 93 flavonoids, 13 saponins, and one phenolic acid, were identified or tentatively characterized in vivo. In addition, glucuronidation, sulfation, methylation, hydroxylation, and reduction were observed as the major metabolic pathways of PF. The constructed compound–target–pathway network revealed that 11 absorbed constituents associated with the 16 relevant targets could be responsible for the protective activity of PF against ALD by regulating nine pathways attributable to glycolysis/gluconeogenesis, amino acid metabolism, and lipid regulation as well as inflammation and immune regulation. In addition, four active ingredients (6″-O-xylosyltectoridin, genistein-7-glucuronide-4′-sulfate, tectoridin-4′-sulfate, and 6″-O-xylosyltectoridin-4′-sulfate) as well as two target genes (MAO-A and PPAR-α) were screened and validated to play a crucial role with a good molecular docking score. The present results not only increase the understanding on the effective form and molecular mechanisms of PF-mediated protection against ALD but also promote better application of PF as a supplement food and herbal medicine for the treatment of ALD.

Progress in the treatment of drug-induced liver injury with natural products

There are numerous prescription drugs and non-prescription drugs that cause drug-induced liver injury (DILI), which is the main cause of liver disease in humans around the globe. Its mechanism becomes clearer as the disease is studied further. For an instance, when acetaminophen (APAP) is taken in excess, it produces N-acetyl-p-benzoquinone imine (NAPQI) that binds to biomacromolecules in the liver causing liver injury. Treatment of DILI with traditional Chinese medicine (TCM) has shown to be effective. For example, activation of the Nrf2 signaling pathway as well as regulation of glutathione (GSH) synthesis, coupling, and excretion are the mechanisms by which ginsenoside Rg1 (Rg1) treats APAP-induced acute liver injury. Nevertheless, reducing the toxicity of TCM in treating DILI is still a problem to be overcome at present and in the future. Accumulated evidences show that hydrogel-based nanocomposite may be an excellent carrier for TCM. Therefore, we reviewed TCM with potential anti-DILI, focusing on the signaling pathway of these drugs' anti-DILI effect, as well as the possibility and prospect of treating DILI by TCM based on hydrogel materials in the future. In conclusion, this review provides new insights to further explore TCM in the treatment of DILI.

Identifying the Mechanism of Polygoni Cuspidati Rhizoma et Radix in Treating Acute Liver Failure Based on Network Pharmacology and Molecular Docking

Materials and Methods

The potential bioactive compounds of PCRR and their targets were collected from TCMSP, TCMID, and BATMAN-TCM databases with absorption, distribution, metabolism, and excretion protocols (oral bioavailability ≥30% and drug-likeness ≥0.18). The ALF-related target genes were identified using the GeneCards and OMIM databases. A protein-protein interaction (PPI) network among these targets was constructed using the Cytoscape software to obtain the core targets. The genes associated with ALF were analyzed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to identify the signaling pathways related to the therapeutic effect of PCRR in ALF.

Results

In total, 10 bioactive compounds of PCRR and 200 targets related to them were obtained, and 2913 ALF-related target genes were identified. PPI network analysis pinpointed 15 core targets, namely, TP53, AKT1, JUN, HSP90AA1, MAPK1, RELA, TNF, ESR1, IL6, MYC, MAPK14, FOS, RB1, CDKN1A, and EGFR. GO enrichment and KEGG pathway analyses revealed that the therapeutic mechanisms of PCRR in ALF are related to cell metabolism, oxidative stress, inflammation, and hepatocyte apoptosis.

Conclusion

This is the first study to explore the therapeutic mechanisms of PCRR in ALF via network pharmacology and molecular docking. This study provides a research platform with candidate ALF-related targets of PRCC for the development of therapeutics against ALF.

HSP90 Inhibitor 17-AAG Attenuates Nucleus Pulposus Inflammation and Catabolism Induced by M1-Polarized Macrophages

Overactivated inflammation and catabolism induced by proinflammatory macrophages are involved in the pathological processes of intervertebral disc (IVD) degeneration (IVDD). Our previous study suggested the protective role of inhibiting heat shock protein 90 (HSP90) in IVDD, while the underlying mechanisms need advanced research. The current study investigated the effects of HSP90 inhibitor 17-AAG on nucleus pulposus (NP) inflammation and catabolism induced by M1-polarized macrophages. Immunohistochemical staining of degenerated human IVD samples showed massive infiltration of macrophages, especially M1 phenotype, as well as elevated levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)13. The conditioned medium (CM) of inflamed NP cells (NPCs) enhanced M1 polarization of macrophages, while the CM of M1 macrophages but not M2 macrophages promoted the expression of inflammatory factors and matrix proteases in NPCs. Additionally, we found that 17-AAG could represent anti-inflammatory and anti-catabolic effects by modulating both macrophages and NPCs. On the one hand, 17-AAG attenuated the pro-inflammatory activity of M1 macrophages via inhibiting nuclear factor-κB (NF-κB) pathway and mitogen-activated protein kinase (MAPK) pathways. On the other hand, 17-AAG dampened M1-CM-induced inflammation and catabolism in NPCs by upregulating HSP70 and suppressing the Janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) pathway. Moreover, both in vitro IVD culture models and murine disc puncture models supported that 17-AAG treatment decreased the levels of inflammatory factors and matrix proteases in IVD tissues. In conclusion, HSP90 inhibitor 17-AAG attenuates NP inflammation and catabolism induced by M1 macrophages, suggesting 17-AAG as a promising candidate for IVDD treatment.

Extracellular Hsp90α, which participates in vascular inflammation, is a novel serum predictor of atherosclerosis in type 2 diabetes

INTRODUCTION

Atherosclerosis is the main pathological change in diabetic angiopathy, and vascular inflammation plays an important role in early atherosclerosis. Extracellular heat shock protein 90 (eHsp90) is secreted into the serum and is involved in various physiological and pathophysiological processes. However, the specific mechanism of eHsp90 in early atherosclerosis remains unclear. This study explored the relationship between Hsp90 and diabetic lower extremity arterial disease and investigated the expression of eHsp90 in vascular endothelial cells under environmental stimulation and the function and mechanism of eHsp90α involved in diabetic atherosclerosis.

RESEARCH DESIGN AND METHODS

One hundred and three selected patients were divided into three groups: the diabetes mellitus group (n=27), the diabetic lower extremity arterial disease group (n=46), and the diabetic critical limb ischemia group (n=30). The relationships among serum Hsp90, oxidative stress indexes, and patient outcomes and the correlations among the indexes were analyzed. H&E staining and immunohistochemistry were used to observe the vasculature of amputated feet from patients with diabetic foot. An oxidative stress endothelial injury model was established under high glucose in vitro to explore the role of eHsp90 release in atherosclerosis progression.

RESULTS

The level of serum Hsp90 was upregulated with aggravation of diabetic vascular disease. Hsp90α was correlated with malondialdehyde to some extent and was an independent risk factor in the progression of diabetic vascular disease, with predictive ability. The expression area of Hsp90α was consistent with the area of inflammatory infiltration in the vessel lumen. Vascular endothelial cells were found to increase eHsp90α secretion under stress. Then inhibition of eHsp90α can reduce the degree of cellular inflammation and damage. Endothelial cell-conditioned medium and recombinant human Hsp90α increased monocyte migration via the low-denisity lipoprotein receptor-related protein 1 (LRP1) receptor to promote disease progression.

CONCLUSIONS

eHsp90α plays a critical role in the early inflammatory injury stage of atherosclerosis.

TRIAL REGISTRATION NUMBER

NCT04787770.

HSP90 as a regulator of extracellular matrix dynamics

The extracellular matrix (ECM) is a dynamic and organised extracellular network assembled from proteins and carbohydrates exported from the cell. The ECM is critical for multicellular life, providing spatial and temporal cellular cues to maintain tissue homeostasis. Consequently, ECM production must be carefully balanced with turnover to ensure homeostasis; ECM dysfunction culminates in disease. Hsp90 is a molecular chaperone central to protein homeostasis, including in the ECM. Intracellular and extracellular Hsp90 isoforms collaborate to regulate the levels and status of proteins in the ECM via multiple mechanisms. In so doing, Hsp90 regulates ECM dynamics, and changes in Hsp90 levels or activity support the development of ECM-related diseases, like cancer and fibrosis. Consequently, Hsp90 levels may have prognostic value, while inhibition of Hsp90 may have therapeutic potential in conditions characterised by ECM dysfunction.

Alcohol-induced Hsp90 acetylation is a novel driver of liver sinusoidal endothelial dysfunction and alcohol-related liver disease

BACKGROUND & AIMS

Liver sinusoidal endothelial cell (LSEC) dysfunction has been reported in alcohol-related liver disease, yet it is not known whether LSECs metabolize alcohol. Thus, we investigated this, as well as the mechanisms of alcohol-induced LSEC dysfunction and a potential therapeutic approach for alcohol-induced liver injury.

METHODS

Primary human, rat and mouse LSECs were used. Histone deacetylase 6 (HDAC6) was overexpressed specifically in liver ECs via adeno-associated virus (AAV)-mediated gene delivery to decrease heat shock protein 90 (Hsp90) acetylation in ethanol-fed mice.

RESULTS

LSECs expressed CYP2E1 and alcohol dehydrogenase 1 (ADH1) and metabolized alcohol. Ethanol induced CYP2E1 in LSECs, but not ADH1. Alcohol metabolism by CYP2E1 increased Hsp90 acetylation and decreased its interaction with endothelial nitric oxide synthase (eNOS) leading to a decrease in nitric oxide (NO) production. A non-acetylation mutant of Hsp90 increased its interaction with eNOS and NO production, whereas a hyperacetylation mutant decreased NO production. These results indicate that Hsp90 acetylation is responsible for decreases in its interaction with eNOS and eNOS-derived NO production. AAV8-driven HDAC6 overexpression specifically in liver ECs deacetylated Hsp90, restored Hsp90's interaction with eNOS and ameliorated alcohol-induced liver injury in mice.

CONCLUSION

Restoring LSEC function is important for ameliorating alcohol-induced liver injury. To this end, blocking acetylation of Hsp90 specifically in LSECs via AAV-mediated gene delivery has the potential to be a new therapeutic strategy.

LAY SUMMARY

Alcohol metabolism in liver sinusoidal endothelial cells (LSECs) and the mechanism of alcohol-induced LSEC dysfunction are largely unknown. Herein, we demonstrate that LSECs can metabolize alcohol. We also uncover a mechanism by which alcohol induces LSEC dysfunction and liver injury, and we identify a potential therapeutic strategy to prevent this.

Myeloid Endoplasmic Reticulum Resident Chaperone GP96 Facilitates Inflammation and Steatosis in Alcohol-Associated Liver Disease

Cellular stress-mediated chaperones are linked to liver macrophage activation and inflammation in alcohol-associated liver disease (ALD). In this study, we investigate the role of endoplasmic reticulum (ER) resident stress chaperone GP96/HSP90B1/GRP94, paralog of the HSP90 family, in ALD pathogenesis. We hypothesize that ER resident chaperone, heat shock protein GP96, plays a crucial role in alcohol-associated liver inflammation and contributes to liver injury. We show high expression of GP96/HSP90B1 and GRP78/HSPA5 in human alcohol-associated hepatitis livers as well as in mouse ALD livers with induction of GP96 prominent in alcohol-exposed macrophages. Myeloid-specific GP96 deficient (M-GP96KO) mice failed to induce alcohol-associated liver injury. Alcohol-fed M-GP96KO mice exhibit significant reduction in steatosis, serum endotoxin, and pro-inflammatory cytokines compared with wild-type mice. Anti-inflammatory cytokines interleukin-10 and transforming growth factor β, as well as activating transcription factor 3 and triggering receptor expressed on myeloid cells 2, markers of restorative macrophages, were higher in alcohol-fed M-GP96KO livers. M-GP96KO mice exhibit protection in a model of endotoxin-mediated liver injury in vivo, which is in agreement with reduced inflammatory responses during ex vivo lipopolysaccharide/endotoxin- stimulated bone marrow-derived macrophages from M-GP96KO mice. Furthermore, we show that liver macrophages from alcohol-fed M-GP96KO mice show compensatory induction of GRP78 messenger RNA, likely due to increased splicing of X-box binding protein-1. Finally, we show that inhibition of GP96 using a specific pharmacological agent, PU-WS13 or small interfering RNA, alleviates inflammatory responses in primary macrophages. Conclusion: Myeloid ER resident GP96 promotes alcohol-induced liver damage through activation of liver macrophage inflammatory responses, alteration in lipid homeostasis, and ER stress. These findings highlight a critical role for liver macrophage ER resident chaperone GP96/HSP90B1 in ALD, and its targeted inhibition represents a promising therapeutic approach in ALD.

Hepatic DNAJB9 Drives Anabolic Biasing to Reduce Steatosis and Obesity

Nutrients stimulate the anabolic synthesis of proteins and lipids, but selective insulin resistance in obesity biases the anabolic program toward lipogenesis. Here, we report the identification of a DNAJB9-driven program that favors protein synthesis and energy production over lipid accumulation. We show there are two pools of DNAJB9 cochaperone. DNAJB9 in the ER lumen promotes the degradation of the lipogenic transcription factor SREBP1c through ERAD, whereas its counterpart on the ER membrane promotes the assembly of mTORC2 in the cytosol and stimulates the synthesis of proteins and ATP. The expression of Dnajb9 is induced by nutrients and downregulated in the obese mouse liver. Restoration of hepatic DNAJB9 expression effectively improves insulin sensitivity, restores protein synthesis, and suppresses food intake, accompanied by reduced hepatic steatosis and adiposity in multiple mouse models of obesity. Therefore, targeting the anabolic balance may provide a unique opportunity to tackle obesity and diabetes.

Heat shock protein 90 inhibitors suppress pyroptosis in THP-1 cells

Pyroptosis is a recently discovered inflammatory form of programmed cell death which is mostly triggered by infection with intracellular pathogens and critically contributes to inflammation. Mitigating pyroptosis may be a potential therapeutic target in inflammatory diseases. However, small chemicals to reduce pyroptosis is still elusive. In the present study, we screened 155 chemicals from a microbial natural product library and found Geldanamycin, an HSP90 inhibitor, profoundly rescued THP-1 cells from pyroptosis induced by LPS plus Nigericin treatment. Consistently, other HSP90 inhibitors, including Radicicol, 17-DMAG and 17-AAG, all ameliorated pyroptosis in THP-1 cells by suppressing the inflammasome/Caspase-1/GSDMD signal pathway in pyroptosis. HSP90 inhibition compromised the protein stability of NLRP3, a critical component of the inflammasome. Moreover, up-regulated HSP70 may also contribute to this effect. HSP90 inhibition may thus be a potential therapeutic strategy in the treatment of inflammatory diseases in which pyroptosis plays a role.

Hydrogen gas alleviates acute alcohol-induced liver injury by inhibiting JNK activation

Binge alcohol drinking is fast becoming a global health concern, with the liver among the first organ involved and the one afflicted with the greatest degree of injury. Oxidative stress, alterations in hepatic metabolism, immunity and inflammation have all been reported to contribute to the development of alcoholic liver disease (ALD). Hydrogen gas (H₂) serves a key role in the modulation of hepatic redox, immune and inflammatory homeostasis. However, the effects of treatment using intraperitoneal injection of H₂ on ALD remain unexplored. Therefore, the aim of the present study was to investigate the effects and underlying mechanism of intraperitoneal injection of H₂ on acute alcohol-induced liver injury in a mouse model. H₂ was administered by daily intraperitoneal injections (1.0 ml/100 g) for 4 days. On day 4, the mice received H₂ after fasting for 5.5 h. After 30 min, the mice were administered with 33% (v/v) ethanol at a cumulative dose of 4.5 g/kg body weight by four equally divided gavages at 20-min intervals. Blood and liver tissues were collected at 16 h after the first ethanol gavage. Subsequently, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride and total cholesterol (TC) levels were analyzed using an Automatic Clinical Analyzer. Hepatic JNK activity and GAPDH levels were examined by western blotting. It was observed that acute ethanol gavage induced liver injury, as indicated by significantly increased serum ALT and AST levels, which were effectively decreased by H₂ at 16 h after the first ethanol gavage. In addition, H₂ treatment reduced serum TC levels in the Alcohol+H₂ group when compared with those in Alcohol group. Mechanistically, H₂ attenuated hepatic JNK phosphorylation induced by acute ethanol gavage. Therefore, the results of the present study demonstrated that treatment with exogenous H₂ by intraperitoneal injection may alleviate acute alcohol-induced liver injury by inhibiting hepatic JNK activation, which may represent a novel therapeutic strategy for ALD.

Inhibition of heat shock protein 90 alleviates cholestatic liver injury by decreasing IL-1β and IL-18 expression

Severe cholestatic liver injury diseases, such as obstructive jaundice and the subsequent acute obstructive cholangitis, are induced by biliary tract occlusion. Heat shock protein 90 (HSP90) inhibitors have been demonstrated to be protective for various organs. The potential of HSP90 inhibitors in the treatment of cholestatic liver injury, however, remains unclear. In the present study, rat models of bile duct ligation (BDL) were established, the HSP90 inhibitor 17-dimethylamino-ethylamino-17-demethoxygeldanamycin (17-DMAG) was administered, and its ability to ameliorate the cholestasis-induced liver injuries was evaluated. In the BDL rat models and clinical samples, increased HSP90 expression was observed to be associated with cholestatic liver injury. Furthermore, 17-DMAG alleviated cholestasis-induced liver injury in the rat models, as revealed by the assessment of pathological changes and liver function. In addition, 17-DMAG protected hepatocytes against cholestatic injury in vitro. Further assays indicated that 17-DMAG administration prevented cholestasis-induced liver injury in the rats by decreasing the expression of interleukin (IL)-1β and IL-18. Moreover, 17-DMAG also decreased the cholestasis-induced upregulation of IL-1β and IL-18 in liver sinusoidal endothelial cells in vitro. In conclusion, the HSP90 inhibitor 17-DMAG is able to prevent liver injury in rats with biliary obstruction, and this phenomenon is associated with the reduction of IL-1β and IL-18 expression.

Insights into the Role of Granulocyte Colony-Stimulating Factor in Severe Alcoholic Hepatitis

Alcohol use disorder is the predominant cause of chronic liver disease globally. The standard of care for the treatment of alcoholic hepatitis, corticosteroids, has been shown to provide a therapeutic response in ∼60% of carefully selected patients with a short-term survival benefit. The patients who do not respond to steroids, or are ineligible due to infections or very severe disease, have little options other than liver transplantation. There is, thus, a large unmet need for new therapeutic strategies for this large and sick group of patients. Granulocyte colony stimulating factor (G-CSF) has been shown to favorably modulate the intrahepatic immune milieu and stimulate the regenerative potential of the liver. Initial studies have shown encouraging results with G-CSF in patients with severe alcoholic hepatitis. It has also been found to help steroid nonresponsive patients. There is, however, a need for careful selection of patients, regular dose monitoring and close observation for adverse events of G-CSF. In this review, we analyze the basis of the potential benefits, clinical studies, cautions and challenges in the use of G-CSF in alcoholic hepatitis.

Danger signals in liver injury and restoration of homeostasis

Damage-associated molecular patterns are signalling molecules involved in inflammatory responses and restoration of homeostasis. Chronic release of these molecules can also promote inflammation in the context of liver disease. Herein, we provide a comprehensive summary of the role of damage-associated molecular patterns as danger signals in liver injury. We consider the role of reactive oxygen species and reactive nitrogen species as inducers of damage-associated molecular patterns, as well as how specific damage-associated molecular patterns participate in the pathogenesis of chronic liver diseases such as alcohol-related liver disease, non-alcoholic steatohepatitis, liver fibrosis and liver cancer. In addition, we discuss the role of damage-associated molecular patterns in ischaemia reperfusion injury and liver transplantation and highlight current studies in which blockade of specific damage-associated molecular patterns has proven beneficial in humans and mice.

Inhibition of HSP90 and Activation of HSF1 Diminish Macrophage NLRP3 Inflammasome Activity in Alcohol-Associated Liver Injury

BACKGROUND

Activation of NLRP3 in liver macrophages contributes to alcohol-associated liver disease (ALD). Molecular chaperone heat shock protein (HSP) 90 facilitates NLRP3 inflammasome activity during infections and inflammatory diseases. We previously reported that HSP90 is induced in ALD and regulates proinflammatory cytokines, tumor necrosis factor alpha, and IL-6. Whether HSP90 affects IL-1β and IL-18 regulated by NLRP3 inflammasome in ALD is unknown. Here, we hypothesize that HSP90 modulated NLRP3 inflammasome activity and affects IL-1β and IL-18 secretion in ALD.

METHODS

The expression of HSP90AA1 and NLRP3 inflammasome genes was evaluated in human alcoholic livers and in mouse model of ALD. The importance of HSP90 on NLRP3 inflammasome activation in ALD was evaluated by administering HSP90 inhibitor, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) to mice subjected to ALD, and in vitro to bone marrow-derived macrophages (BMDM) stimulated with LPS and ATP. The effect of activation of HSF1/HSPA1A axis during HSP90 inhibition or direct activation during heat shock of BMDMs on NLRP3 activity and secretion of downstream cytokines was evaluated.

RESULTS

We found positive correlation between induction of HSP90 and NLRP3 inflammasome genes in human alcoholic cirrhotic livers. Administration of 17-DMAG in mouse model of ALD significantly down-regulated NLRP3 inflammasome-mediated caspase-1 (CASP-1) activity and cytokine secretion, with reduction in ALD. 17-DMAG-mediated decrease in NLRP3 was restricted to liver macrophages. Using BMDMs, we show that inhibition of HSP90 prevented CASP-1 activity, and Gasdermin D (GSDMD) cleavage, important in release of active IL-1β and IL-18. Interestingly, activation of the heat shock factor 1 (HSF1)/HSPA1A axis, either during HSP90 inhibition or by heat shock, decreased NLRP3 inflammasome activity and reduced secretion of cytokines.

CONCLUSION

Our studies indicate that inhibition of HSP90 and activation of HSF1/HSPA1A reduce IL-1β and IL-18 via decrease in NLRP3/CASP-1 and GSDMD activity in ALD.

The road ahead for health and lifespan interventions

Aging is a modifiable risk factor for most chronic diseases and an inevitable process in humans. The development of pharmacological interventions aimed at delaying or preventing the onset of chronic conditions and other age-related diseases has been at the forefront of the aging field. Preclinical findings have demonstrated that species, sex and strain confer significant heterogeneity on reaching the desired health- and lifespan-promoting pharmacological responses in model organisms. Translating the safety and efficacy of these interventions to humans and the lack of reliable biomarkers that serve as predictors of health outcomes remain a challenge. Here, we will survey current pharmacological interventions that promote lifespan extension and/or increased healthspan in animals and humans, and review the various anti-aging interventions selected for inclusion in the NIA's Interventions Testing Program as well as the ClinicalTrials.gov database that target aging or age-related diseases in humans.

Chronic alcohol-induced liver injury correlates with memory deficits: Role for neuroinflammation

Alcohol use disorder (AUD) affects over 15 million adults over age 18 in the United States, with estimated costs of 220 billion dollars annually - mainly due to poor quality of life and lost productivity, which in turn is intricately linked to cognitive dysfunction. AUD-induced neuroinflammation in the brain, notably the hippocampus, is likely to contribute to cognitive impairments. The neuroinflammatory mechanisms mediating the impact of chronic alcohol on the central nervous system, specifically cognition, require further study. We hypothesized that chronic alcohol consumption impairs memory and increases the inflammatory cytokines TNFα, IL6, MCP1, and IL1β in the hippocampus and prefrontal cortex regions in the brain. Using the chronic-binge Gao-NIAAA alcohol mouse model of liver disease, representative of the drinking pattern common to human alcoholics, we investigated behavioral and neuroinflammatory parameters. Our data show that chronic alcohol intake elevated peripheral and brain alcohol levels, induced serum alanine aminotransferase (ALT, a marker of liver injury), impaired memory and sensorimotor coordination, and increased inflammatory gene expression in the hippocampus and prefrontal cortex. Interestingly, serum ALT and hippocampal IL6 correlated with memory impairment, suggesting an intrinsic relationship between neuroinflammation, cognitive decline, and liver disease. Overall, our results point to a likely liver-brain functional partnership and suggest that future strategies to alleviate hepatic and/or neuroinflammatory impacts of chronic AUD may result in improved cognitive outcomes.

Inhibition of HSP90β Improves Lipid Disorders by Promoting Mature SREBPs Degradation via the Ubiquitin-proteasome System

Rationale: Heat shock protein 9 (HSP90) are a family of the most highly expressed cellular proteins and attractive drug targets against cancer, neurodegeneration diseases, etc. HSP90 proteins have also been suggested to be linked to lipid metabolism. However, the specific function of HSP90 paralogs, as well as the underlying molecular cascades remains largely unknown. This study aims to unravel the paralog-specific role of HSP90 in lipid metabolism and try to discover paralog-specific HSP90 inhibitors.

Methods: In non-alcohol fatty liver disease (NAFLD) patients, as well as in diet induced obese (DIO) mice, expression of HSP90 paralogs were analyzed by immunohistochemistry and western blot. In hepatocytes and in DIO mice, HSP90 proteins were knockdown by siRNAs/shRNAs, metabolic parameters, as well as downstream signaling were then investigated. By virtue screening, corylin was found to bind specifically to HSP90β. Using photo-affinity labeling and mass spectrum, corylin binding proteins were identified. After oral administration of corylin, its lipid lowering effects in different metabolic disease mice models were evaluated.

Results: We showed that hepatic HSP90β, rather than HSP90α, was overexpressed in NAFLD patients and obese mice. Hepatic HSP90β was also clinical relevant to serum lipid level. Depletion of HSP90β promoted mature sterol regulatory element-binding proteins (mSREBPs) degradation through Akt-GSK3β-FBW7 pathway, thereby dramatically decreased the content of neutral lipids and cholesterol. We discovered an HSP90β-selective inhibitor (corylin) that only bound to its middle domain. We found that corylin treatment partially suppressed Akt activity only at Thr308 site and specifically promoted mSREBPs ubiquitination and proteasomal degradation. Corylin treatment significantly reduced lipid content in both liver cell lines and human primary hepatocytes. In animal studies, we showed that corylin ameliorated obesity-induced fatty liver disease, type 2 diabetes and atherosclerosis.

Principle conclusions: HSP90β plays a parolog-specific role in regulating lipid homeostasis. Compound that selectively inhibits HSP90β could be useful in the clinic for the treatment for metabolic diseases.

Recent Insights Into the Role of Immune Cells in Alcoholic Liver Disease

Accumulating clinical and experimental evidences have demonstrated that both innate and adaptive immunity are involved in the pathogenesis of alcoholic liver disease (ALD), in which the role of immunity is to fuel the inflammation and to drive the progression of ALD. Various immune cells are implicated in the pathogenesis of ALD. The activation of innate immune cells induced by alcohol and adaptive immune response triggered by oxidative modification of hepatic constituents facilitate the persistent hepatic inflammation. Meanwhile, the suppressed antigen-presenting capability of various innate immune cells and impaired function of T cells may consequently lead to an increased risk of infection in the patients with advanced ALD. In this review, we summarized the significant recent findings of immune cells participating in ALD. The pathways and molecules involved in the regulation of specific immune cells, and novel mediators protecting the liver from alcoholic injury via affecting these cells are particularly highlighted. This review aims to update the knowledge about immunity in the pathogenesis of ALD, which may facilitate to enhancement of currently available interventions for ALD treatment.

The influence of high-fat, high-sugar diet and bariatric surgery on HSP70 and HSP90 plasma and liver concentrations in diet-induced obese rats

Metabolic surgery ameliorates insulin resistance and is associated with long-term, effective weight loss, but the mechanisms involved remain unknown. Here, the duodenal-jejunal omega switch (DJOS) surgery in combination with high-fat, high-carbohydrate diet was performed on diet obese rats and joint effects of bariatric surgery and different dietary patterns on heat shock protein 70 (HSP70) and HSP90 plasma and liver concentrations were measured. We found that plasma and liver levels of HSP70 were lower after DJOS surgery in comparison to the control in the groups of animals kept on control diet (CD) and high-fat, high-sugar diet (HFS) but the postoperative change of the diet led to the increase in HSP70 in plasma and liver concentration in DJOS-operated animals. A high-calorie meal, rich in carbohydrates and fats, significantly increased circulating levels of HSP90, reducing the normalising effect of DJOS. The HFS diet applied during all stages of the experiment led to the higher levels of liver HSP90 concentration. The combination of CD and DJOS surgery was the most efficient in the lowering of the HSP90 liver concentration. The normalisation of circulating levels and liver concentrations of HSP70 and HSP90 may be achieved in a combination of DJOS procedure with a proper dietary plan.

Inflammatory pathways in alcoholic steatohepatitis

Inflammatory processes are primary contributors to the development and progression of alcoholic steatohepatitis (ASH), with severe alcoholic hepatitis characterised by non-resolving inflammation. Inflammation in the progression of ASH is a complex response to microbial dysbiosis, loss of barrier integrity in the intestine, hepatocellular stress and death, as well as inter-organ crosstalk. Herein, we review the roles of multiple cell types that are involved in inflammation in ASH, including resident macrophages and infiltrating monocytes, as well as other cell types in the innate and adaptive immune system. In response to chronic, heavy alcohol exposure, hepatocytes themselves also contribute to the inflammatory process; hepatocytes express a large number of chemokines and inflammatory mediators and can also release damage-associated molecular patterns during injury and death. These cellular responses are mediated and accompanied by changes in the expression of pro- and anti-inflammatory cytokines and chemokines, as well as by signals which orchestrate the recruitment of immune cells and activation of the inflammatory process. Additional mechanisms for cell-cell and inter-organ communication in ASH are also reviewed, including the roles of extracellular vesicles and microRNAs, as well as inter-organ crosstalk. We highlight the concept that inflammation also plays an important role in promoting liver repair and controlling bacterial infection. Understanding the complex regulatory processes that are disrupted during the progression of ASH will likely lead to better targeted strategies for therapeutic interventions.

Effect of ethanol on lipid metabolism

Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.

Ethanol and unsaturated dietary fat induce unique patterns of hepatic ω-6 and ω-3 PUFA oxylipins in a mouse model of alcoholic liver disease

Alcoholic liver disease (ALD), a significant health problem, progresses through the course of several pathologies including steatosis, steatohepatitis, fibrosis, and cirrhosis. There are no effective FDA-approved medications to prevent or treat any stages of ALD, and the mechanisms involved in ALD pathogenesis are not well understood. Bioactive lipid metabolites play a crucial role in numerous pathological conditions, as well as in the induction and resolution of inflammation. Herein, a hepatic lipidomic analysis was performed on a mouse model of ALD with the objective of identifying novel metabolic pathways and lipid mediators associated with alcoholic steatohepatitis, which might be potential novel biomarkers and therapeutic targets for the disease. We found that ethanol and dietary unsaturated, but not saturated, fat caused elevated plasma ALT levels, hepatic steatosis and inflammation. These pathologies were associated with increased levels of bioactive lipid metabolites generally involved in pro-inflammatory responses, including 13-hydroxy-octadecadienoic acid, 9,10- and 12,13-dihydroxy-octadecenoic acids, 5-, 8-, 9-, 11-, 15-hydroxy-eicosatetraenoic acids, and 8,9- and 11,12-dihydroxy-eicosatrienoic acids, in parallel with an increase in pro-resolving mediators, such as lipoxin A4, 18-hydroxy-eicosapentaenoic acid, and 10S,17S-dihydroxy-docosahexaenoic acid. Elucidation of alterations in these lipid metabolites may shed new light into the molecular mechanisms underlying ALD development/progression, and be potential novel therapeutic targets.

Schisantherin A alleviated alcohol-induced liver injury by the regulation of alcohol metabolism and NF-kB pathway

Schisantherin A (SinA), one of the most abundant active ingredients of Schisandra chinensis, was reported to protect and benefit the liver, however, its effect on alcohol-induced liver injury (ALI) was still not clear. In the present study, an ALI mice model was induced by feeding mice an alcohol-containing liquid diet for four weeks. Then, 100 mg/kg or 200 mg/kg SinA was administered to mice every day by gavage for the last two weeks. Histopathological analysis showed that alcohol-induced liver lipid vacuoles were reduced by SinA. The activities of aspartate aminotransferase (AST, 61.90 ± 14.65 vs. 93.65 ± 20.50, 50.46 ± 13.21 vs. 93.65 ± 20.50) and alanine transaminase (ALT, 41.29 ± 9.20 vs. 64.04 ± 18.13, 36.52 ± 7.71 vs. 64.04 ± 18.13) in the serum of ALI mice were significantly reduced by 100 mg/kg or 200 mg/kg SinA when compared with control mice. Alcohol-induced oxidative stress and the inflammatory response in the liver were suppressed by SinA in a dose-dependent manner. Meanwhile, treatment with SinA decreased alcohol dehydrogenase (ADH) activity and increased acetaldehyde dehydrogenase (ALDH) activity in ALI mice. Alcohol-induced upregulation of CYP2E1 and CYP1A2 in the liver was inhibited by SinA. Further, SinA suppressed activation of the NF-kB pathway in ALI mice. In conclusion, our findings demonstrate that SinA is able to protect against ALI, and this may be, at least in part, caused by regulation of alcohol metabolism and the NF-kB pathway. Our data suggest a therapeutic potential of SinA in the treatment of ALI.

A High-Throughput Assay for Collagen Secretion Suggests an Unanticipated Role for Hsp90 in Collagen Production

Collagen overproduction is a feature of fibrosis and cancer, while insufficient deposition of functional collagen molecules and/or the secretion of malformed collagen is common in genetic disorders like osteogenesis imperfecta. Collagen secretion is an appealing therapeutic target in these and other diseases, as secretion directly connects intracellular biosynthesis to collagen deposition and biological function in the extracellular matrix. However, small molecule and biological methods to tune collagen secretion are severely lacking. Their discovery could prove useful not only in the treatment of disease, but also in providing tools for better elucidating mechanisms of collagen biosynthesis. We developed a cell-based, high-throughput luminescent assay of collagen type I secretion and used it to screen for small molecules that selectively enhance or inhibit that process. Among several validated hits, the Hsp90 inhibitor 17-allylaminogeldanamycin (17-AAG) robustly decreases the secretion of collagen-I by our model cell line and by human primary cells. In these systems, 17-AAG and other pan-isoform Hsp90 inhibitors reduce collagen-I secretion post-translationally and are not global inhibitors of protein secretion. Surprisingly, the consequences of Hsp90 inhibitors cannot be attributed to inhibition of the endoplasmic reticulum's Hsp90 isoform, Grp94. Instead, collagen-I secretion likely depends on the activity of cytosolic Hsp90 chaperones, even though such chaperones cannot directly engage nascent collagen molecules. Our results highlight the value of a cell-based high-throughput screen for selective modulators of collagen secretion and suggest an unanticipated role for cytosolic Hsp90 in collagen secretion.

Extracellular vesicles from mice with alcoholic liver disease carry a distinct protein cargo and induce macrophage activation through heat shock protein 90

A salient feature of alcoholic liver disease (ALD) is Kupffer cell (KC) activation and recruitment of inflammatory monocytes and macrophages (MØs). These key cellular events of ALD pathogenesis may be mediated by extracellular vesicles (EVs). EVs transfer biomaterials, including proteins and microRNAs, and have recently emerged as important effectors of intercellular communication. We hypothesized that circulating EVs from mice with ALD have a protein cargo characteristic of the disease and mediate biological effects by activating immune cells. The total number of circulating EVs was increased in mice with ALD compared to pair-fed controls. Mass spectrometric analysis of circulating EVs revealed a distinct signature for proteins involved in inflammatory responses, cellular development, and cellular movement between ALD EVs and control EVs. We also identified uniquely important proteins in ALD EVs that were not present in control EVs. When ALD EVs were injected intravenously into alcohol-naive mice, we found evidence of uptake of ALD EVs in recipient livers in hepatocytes and MØs. Hepatocytes isolated from mice after transfer of ALD EVs, but not control EVs, showed increased monocyte chemoattractant protein 1 mRNA and protein expression, suggesting a biological effect of ALD EVs. Compared to control EV recipient mice, ALD EV recipient mice had increased numbers of F4/80^hi cluster of differentiation 11b (CD11b)^lo KCs and increased percentages of tumor necrosis factor alpha-positive/interleukin 12/23-positive (inflammatory/M1) KCs and infiltrating monocytes (F4/80^int CD11b^hi ), while the percentage of CD206⁺ CD163⁺ (anti-inflammatory/M2) KCs was decreased. In vitro, ALD EVs increased tumor necrosis factor alpha and interleukin-1β production in MØs and reduced CD163 and CD206 expression. We identified heat shock protein 90 in ALD EVs as the mediator of ALD-EV-induced MØ activation.

CONCLUSION

Our study indicates a specific protein signature of ALD EVs and demonstrates a functional role of circulating EVs containing heat shock protein 90 in mediating KC/MØ activation in the liver. (Hepatology 2018;67:1986-2000).

Alcoholic Hepatitis: Lost in Translation

Alcoholic hepatitis is the most severe and acute form of alcoholic liver disease. The mortality rate associated with alcoholic hepatitis is high, largely due to the lack of suitable pharmacological interventions. While there has been substantial research in the area, generating pharmacological interventions has been plagued by the lack of a robust mouse model both for testing and for understanding the underlying pathology. A number of major notable advances have been made in this area recently, with the goal of generating a mouse model of alcoholic hepatitis. The purpose of this article is to review recent advances in modeling alcoholic liver disease both in vitro and in vivo in the mouse, and place them in the context of the greater spectrum of alcoholic liver disease, with a focus on how we can translate current advances into a high-fidelity model of alcoholic hepatitis. In addition, we will review the basic mechanisms of alcoholic hepatitis as it is currently understood, focusing on recent advancements in diagnosis, prognosis and current pathophysiology, especially as it relates to the profound immune dysfunction present during alcoholic hepatitis.

Evaluating the effect of diallyl sulfide on regulation of inflammatory mRNA expression in 3T3L1 adipocytes and RAW 264.7 macrophages during ethanol treatment

Diallyl sulfide (DAS) has been studied extensively for its alleged role as an anticancer and protective agent. Alcohol influences and effects on human health have been extensively studied. However, investigations toward developing and testing therapeutic agents that can reduce the tissue injury caused by ethanol are scarce. In this backdrop, this study was designed to explore the potential effect of DAS in reducing alcohol induced damage of 3T3L1 adipocytes and RAW 264.7 macrophages. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was performed to determine the DAS effect on cell viability. Reactive oxygen species (ROS) production was assessed by flow cytometer. Expression of inflammatory genes was studied by the qRT-PCR method. Our study results showed that DAS at concentrations less than 200 μM was not toxic to the cells and the viability of ethanol-exposed 3T3L1 adipocyte cells was found to be significantly increased when ethanol-exposed cells were treated with DAS. Further, treatment of ethanol-exposed 3T3L1 cells with 100 μM DAS for 24 h was found to reduce ethanol induced ROS production, expression of pro-inflammatory cytokines, and enhance anti-inflammatory cytokine production in the cells. Also, 100 μM DAS was found to increase the expression of M2 phenotype-specific genes in ethanol-exposed RAW 264.7 macrophage cells. Further, 100 μM DAS also improved the levels of lipid accumulation in 3T3L1 adipocytes that was down-regulated by ethanol exposure. Taken together, our study results imply that DAS may be effective in reducing ethanol induced injury of cells thereby suggesting its potential to be used in drug formulations.

Dietary Linoleic Acid and Its Oxidized Metabolites Exacerbate Liver Injury Caused by Ethanol via Induction of Hepatic Proinflammatory Response in Mice

Alcoholic liver disease is a major human health problem leading to significant morbidity and mortality in the United States and worldwide. Dietary fat plays an important role in alcoholic liver disease pathogenesis. Herein, we tested the hypothesis that a combination of ethanol and a diet rich in linoleic acid (LA) leads to the increased production of oxidized LA metabolites (OXLAMs), specifically 9- and 13-hydroxyoctadecadienoic acids (HODEs), which contribute to a hepatic proinflammatory response exacerbating liver injury. Mice were fed unsaturated (with a high LA content) or saturated fat diets (USF and SF, respectively) with or without ethanol for 10 days, followed by a single binge of ethanol. Compared to SF+ethanol, mice fed USF+ethanol had elevated plasma alanine transaminase levels, enhanced hepatic steatosis, oxidative stress, and inflammation. Plasma and liver levels of 9- and 13-HODEs were increased in response to USF+ethanol feeding. We demonstrated that primarily 9-HODE, but not 13-HODE, induced the expression of several proinflammatory cytokines in vitro in RAW264.7 macrophages. Finally, deficiency of arachidonate 15-lipoxygenase, a major enzyme involved in LA oxidation and OXLAM production, attenuated liver injury and inflammation caused by USF+ethanol feeding but had no effect on hepatic steatosis. This study demonstrates that OXLAM-mediated induction of a proinflammatory response in macrophages is one of the potential mechanisms underlying the progression from alcohol-induced steatosis to alcoholic steatohepatitis.

Animal Models of Alcoholic Liver Disease: Pathogenesis and Clinical Relevance

Alcoholic liver disease (ALD), a leading cause of chronic liver injury worldwide, comprises a range of disorders including simple steatosis, steatohepatitis, cirrhosis, and hepatocellular carcinoma. Over the last five decades, many animal models for the study of ALD pathogenesis have been developed. Recently, a chronic-plus-binge ethanol feeding model was reported. This model induces significant steatosis, hepatic neutrophil infiltration, and liver injury. A clinically relevant model of high-fat diet feeding plus binge ethanol was also developed, which highlights the risk of excessive binge drinking in obese/overweight individuals. All of these models recapitulate some features of the different stages of ALD and have been widely used by many investigators to study the pathogenesis of ALD and to test for therapeutic drugs/components. However, these models are somewhat variable, depending on mouse genetic background, ethanol dose, and animal facility environment. This review focuses on these models and discusses these variations and some methods to improve the feeding protocol. The pathogenesis, clinical relevance, and translational studies of these models are also discussed.

Glycyrrhetinic acid prevents acetaminophen-induced acute liver injury via the inhibition of CYP2E1 expression and HMGB1-TLR4 signal activation in mice

Acetaminophen (APAP) is a widely used antipyretic and analgesic drug, which is safe and effective at the therapeutic dose. Unfortunately, excessive dosage of APAP could cause severe liver injury due to lack of effective therapy. Successful therapeutic strategies are urgently requested in clinic. Glycyrrhetinic acid (GA), derived from a traditional medicine licorice, has been shown to exert anti-inflammatory and antioxidant actions. In this study, the effect and the underlying mechanism of GA on APAP-induced hepatotoxicity were explored. Our results showed that pretreatment with GA significantly reduced serum ALT and AST activities, alleviated hepatic pathological damages with hepatocellular apoptosis, down-regulated expression of CYP2E1 mRNA and protein, increased GSH levels, and reduced reactive oxygen species (ROS) productions in the liver of APAP-exposed mice. Furthermore, GA obviously inhibited APAP-induced HMGB1-TLR4 signal activation, as evaluated by reduced hepatic HMGB1 release, p-IRAK1, p-MAPK and p-IκB expression as well as the productions of TNF-α and IL-1β. In addition, GA attenuated hepatic neutrophils recruitment and macrophages infiltration caused by APAP. These findings reflected that GA could alleviate APAP-induced hepatotoxicity, the possible mechanism is associated with down-regulation of CYP2E1 expression and deactivation of HMGB1-TLR4 signal pathway.

A Biomedical Investigation of the Hepatoprotective Effect of Radix salviae miltiorrhizae and Network Pharmacology-Based Prediction of the Active Compounds and Molecular Targets

Radix salviae miltiorrhizae (Danshen in Chinese), a classic traditional Chinese medicine (TCM) herb, has been used for centuries to treat liver diseases. In this study, the preventive and curative potential of Danshen aqueous extract on acute/chronic alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) was studied. The in vivo results indicated that Danshen could alleviate hepatic inflammation, fatty degeneration, and haptic fibrogenesis in ALD and NAFLD models. In the aspect of mechanism of action, the significant reduction in MDA levels in both ALD and NAFLD models implies the decreased levels of oxidative stress by Danshen. However, Danshen treatment could not activate the internal enzymatic antioxidant system in ALD and NAFLD models. To further explore the hepatoprotective mechanism of Danshen, an in silico-based network pharmacology approach was employed in the present study. The pharmacological network analysis result revealed that six potential active ingredients such as tanshinone iia, salvianolic acid b, and Danshensu may contribute to the hepatoprotective effects of Danshen on ALD and NAFLD. The action mechanism may relate with regulating the intracellular molecular targets such as PPARα, CYP1A2, and MMP2 for regulation of lipid metabolism, antioxidant and anti-fibrogenesis by these potential active ingredients. Our studies suggest that the combination of network pharmacology strategy with in vivo experimental study may provide a forceful tool for exploring the mechanism of action of traditional Chinese medicine (TCM) herb and developing novel bioactive ingredients.

Heat Shock Protein 90 Modulates Lipid Homeostasis by Regulating the Stability and Function of Sterol Regulatory Element-binding Protein (SREBP) and SREBP Cleavage-activating Protein

Sterol regulatory element-binding proteins (SREBPs) are the key transcription factors that modulate lipid biosynthesis. SREBPs are synthesized as endoplasmic reticulum-bound precursors that require proteolytic activation in the Golgi apparatus. The stability and maturation of precursor SREBPs depend on their binding to SREBP cleavage-activating protein (SCAP), which escorts the SCAP-SREBP complex to the Golgi apparatus. In this study, we identified heat shock protein (HSP) 90 as a novel SREBP regulator that binds to and stabilizes SCAP-SREBP. In HepG2 cells, HSP90 inhibition led to proteasome-dependent degradation of SCAP-SREBP, which resulted in the down-regulation of SREBP target genes and the reduction in intracellular triglyceride and cholesterol levels. We also demonstrated in vivo that HSP90 inhibition decreased SCAP-SREBP protein, down-regulated SREBP target genes, and reduced lipids levels in mouse livers. We propose that HSP90 plays an indispensable role in SREBP regulation by stabilizing the SCAP-SREBP complex, facilitating the activation of SREBP to maintain lipids homeostasis.

Sexual Dimorphism in Alcohol Induced Adipose Inflammation Relates to Liver Injury

Alcoholic liver disease occurs due to chronic, heavy drinking and is driven both by metabolic alterations and immune cell activation. Women are at a higher risk than men for developing alcohol induced liver injury and this dimorphism is reflected in animal models of alcoholic liver disease. The importance of adipose tissue in alcoholic liver disease is emerging. Chronic alcohol consumption causes adipose tissue inflammation, which can influence liver injury. Sex differences in body fat composition are well known. However, it is still unclear if alcohol-induced adipose tissue inflammation occurs in a sex-dependent manner. Here we have employed the clinically relevant NIAAA model of chronic-binge alcohol consumption to investigate this sexual dimorphism. We report that female mice have greater liver injury than male mice despite lower alcohol consumption. Chronic-binge alcohol induces adipose tissue inflammation in vivo in female mice, which is illustrated by increased expression of TNFα, IL-6, and CCL2, compared to only IL-6 induction in male adipose tissue. Further, macrophage activation markers such as CD68 as well as the pro-inflammatory activation markers CD11b and CD11c were higher in female adipose tissue. Interestingly, alcohol induced expression of TLR2, 3, 4, and 9 in female but not male adipose tissue, without affecting the TLR adaptor, MyD88. Higher trends of serum endotoxin in female mice may likely contribute to adipose tissue inflammation. In vitro chronic alcohol-mediated sensitization of macrophages to endotoxin is independent of sex. In summary, we demonstrate for the first time that there is a sexual dimorphism in alcohol-induced adipose tissue inflammation and female mice exhibit a higher degree of inflammation than male mice.

Alcoholic hepatitis: Translational approaches to develop targeted therapies

Alcoholic liver disease is a leading cause of liver-related mortality worldwide. In contrast to recent advances in therapeutic strategies for patients with viral hepatitis, there is a significant lack of novel therapeutic options for patients with alcoholic liver disease. In particular, there is an urgent need to focus our efforts on effective therapeutic interventions for alcoholic hepatitis (AH), the most severe form of alcoholic liver disease. AH is characterized by an abrupt development of jaundice and complications related to liver insufficiency and portal hypertension in patients with heavy alcohol intake. The mortality of patients with AH is very high (20%-50% at 3 months). Available therapies are not effective in many patients, and targeted approaches are imminently needed. The development of such therapies requires translational studies in human samples and suitable animal models that reproduce the clinical and histological features of AH. In recent years, new animal models that simulate some of the features of human AH have been developed, and translational studies using human samples have identified potential pathogenic factors and histological parameters that predict survival.

CONCLUSION

This review summarizes the unmet needs for translational studies on the pathogenesis of AH, preclinical translational tools, and emerging drug targets to benefit the AH patient. (Hepatology 2016;64:1343-1355).

Hepatocellular carcinoma is accelerated by NASH involving M2 macrophage polarization mediated by hif-1induced IL-10

Obesity-related inflammation promotes cancer development. Tissue resident macrophages affect tumor progression and the tumor micro-environment favors polarization into alternatively activated macrophages (M2) that facilitate tumor invasiveness. Here, we dissected the role of western diet-induced NASH in inducing macrophage polarization in a carcinogen initiated model of hepatocellular carcinoma (HCC). Adult C57BL/6 male mice received diethyl nitrosamine (DEN) followed by 24 weeks of high fat-high cholesterol-high sugar diet (HF-HC-HSD). We assessed liver MRI and histology, serum ALT, AFP, liver triglycerides, and cytokines. Macrophage polarization was determined by IL-12/TNFα (M1) and CD163/CD206 (M2) expression using flow cytometry. Role of hif-1α-induced IL-10 was dissected in hepatocyte specific hif-1αKO and hif-1αdPA (over-expression) mice. The western diet-induced features of NASH and accelerated HCC development after carcinogen exposure. Liver fibrosis and serum AFP were significantly increased in DEN + HF-HC-HSD mice compared to controls. Western diet resulted in macrophage (F4/80⁺CD11b⁺) infiltration to liver and DEN + HF-HC-HSD mice showed preferential increase in M2 macrophages. Isolated hepatocytes from western diet fed mice showed significant upregulation of the hypoxia-inducible transcription factor, hif-1α, and livers from hif-1α over-expressing mice had increased proportion of M2 macrophages. Primary hepatocytes from wild-type mice treated with DEN and palmitic acid in vitro showed activation of hif-1α and induction of IL-10, a M2 polarizing cytokine. IL-10 neutralization in hepatocyte-derived culture supernatant prevented M2 macrophage polarization and silencing hif-1α in macrophages blocked their M2 polarization. Therefore, our data demonstrate that NASH accelerates HCC progression via upregulation of hif-1α mediated IL-10 polarizing M2 macrophages.

Adult mouse model of early hepatocellular carcinoma promoted by alcoholic liver disease

AIM

To establish a mouse model of alcohol-driven hepatocellular carcinoma (HCC) that develops in livers with alcoholic liver disease (ALD).

METHODS

Adult C57BL/6 male mice received multiple doses of chemical carcinogen diethyl nitrosamine (DEN) followed by 7 wk of 4% Lieber-DeCarli diet. Serum alanine aminotransferase (ALT), alpha fetoprotein (AFP) and liver Cyp2e1 were assessed. Expression of F4/80, CD68 for macrophages and Ly6G, MPO, E-selectin for neutrophils was measured. Macrophage polarization was determined by IL-1β/iNOS (M1) and Arg-1/IL-10/CD163/CD206 (M2) expression. Liver steatosis and fibrosis were measured by oil-red-O and Sirius red staining respectively. HCC development was monitored by magnetic resonance imaging, confirmed by histology. Cellular proliferation was assessed by proliferating cell nuclear antigen (PCNA).

RESULTS

Alcohol-DEN mice showed higher ALTs than pair fed-DEN mice throughout the alcohol feeding without weight gain. Alcohol feeding resulted in increased ALT, liver steatosis and inflammation compared to pair-fed controls. Alcohol-DEN mice had reduced steatosis and increased fibrosis indicating advanced liver disease. Molecular characterization showed highest levels of both neutrophil and macrophage markers in alcohol-DEN livers. Importantly, M2 macrophages were predominantly higher in alcohol-DEN livers. Magnetic resonance imaging revealed increased numbers of intrahepatic cysts and liver histology confirmed the presence of early HCC in alcohol-DEN mice compared to all other groups. This correlated with increased serum alpha-fetoprotein, a marker of HCC, in alcohol-DEN mice. PCNA immunostaining revealed significantly increased hepatocyte proliferation in livers from alcohol-DEN compared to pair fed-DEN or alcohol-fed mice.

CONCLUSION

We describe a new 12-wk HCC model in adult mice that develops in livers with alcoholic hepatitis and defines ALD as co-factor in HCC.

Anti-Hsp90 therapy in autoimmune and inflammatory diseases: a review of preclinical studies

Heat shock protein 90 (Hsp90), a 90-kDa molecular chaperone, is responsible for biological activities of key signaling molecules (clients) such as protein kinases, ubiquitin ligases, steroid receptors, cell cycle regulators, and transcription factors regulating various cellular processes, including growth, survival, differentiation, and apoptosis. Because Hsp90 is also involved in stabilization of oncogenic 'client' proteins, its specific chaperone activity blockers are currently being tested as anticancer agents in advanced clinical trials. Recent in vitro and in vivo studies have shown that Hsp90 is also involved in activation of innate and adaptive cells of the immune system. For these reasons, pharmacological inhibition of Hsp90 has been evaluated in murine models of autoimmune and inflammatory diseases. This mini-review summarizes current knowledge of the effects of Hsp90 inhibitors on autoimmune and inflammatory diseases' features and is based solely on preclinical studies.

Development-dependent regulation of molecular chaperones after hypoxia-ischemia

Cellular stress response after hypoxia-Ischemia (HI) may be substantially different between immature and mature brains. To study this phenomenon, postnatal day 7 (P7) and P26 rats were subjected to HI followed by different periods of recovery. Nuclear accumulation of heat-shock transcription factor-1 (HSF1) and expression of molecular chaperone proteins and mRNAs were analyzed by in situ hybridization, Western blotting and confocal microscopy. Nuclear accumulation of HSF1 protein and induction of hsp70 mRNA occurred dramatically in P26 neurons, but minimally in P7 neurons and moderately in microglial cells after HI. Consistently, the level of HSF1 was significantly higher in P26 brain samples, compared with that in P7 brain. Translation of hsp70 mRNA into proteins in P26 mature neurons was seen at 4h and peaked at 24h, when some neurons had already died after HI. Induction of ER glucose-regulated protein-78 (grp78) and mitochondrial hsp60 mRNAs and proteins was moderate and occurred also only in P26 mature brain after HI. These results suggest that the cellular stress response after HI is development-dependent, being pronounced in mature but virtually negligible in neonatal neurons. Therefore, the effectiveness of therapeutic strategies targeting the stress pathway against HI may be significantly different between immature and mature brains. The delayed induction of molecular chaperones in mature brain may be somewhat late for protecting HI neurons from acute HI injury.