Acetaldehyde suppresses the display of HBV-MHC class I complexes on HBV-expressing hepatocytes

Increased liver stiffness promotes hepatitis B progression by impairing innate immunity in CCl4-induced fibrotic HBV+ transgenic mice

Background

Hepatitis B virus (HBV) infection develops as an acute or chronic liver disease, which progresses from steatosis, hepatitis, and fibrosis to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). An increased stromal stiffness accompanies fibrosis in chronic liver diseases and is considered a strong predictor for disease progression. The goal of this study was to establish the mechanisms by which enhanced liver stiffness regulates HBV infectivity in the fibrotic liver tissue.

Methods

For in vitro studies, HBV-transfected HepG2.2.15 cells were cultured on polydimethylsiloxane gels coated by polyelectrolyte multilayer films of 2 kPa (soft) or 24 kPa (stiff) rigidity mimicking the stiffness of the healthy or fibrotic liver. For in vivo studies, hepatic fibrosis was induced in C57Bl/6 parental and HBV+ transgenic (HBVTg) mice by injecting CCl4 twice a week for 6 weeks.

Results

We found higher levels of HBV markers in stiff gel-attached hepatocytes accompanied by up-regulated OPN content in cell supernatants as well as suppression of anti-viral interferon-stimulated genes (ISGs). This indicates that pre-requisite "fibrotic" stiffness increases osteopontin (OPN) content and releases and suppresses anti-viral innate immunity, causing a subsequent rise in HBV markers expression in hepatocytes. In vitro results were corroborated by data from HBVTg mice administered CCl4 (HBVTg CCl4). These mice showed higher HBV RNA, DNA, HBV core antigen (HBcAg), and HBV surface antigen (HBsAg) levels after liver fibrosis induction as judged by a rise in Col1a1, SMA, MMPs, and TIMPs mRNAs and by increased liver stiffness. Importantly, CCl4-induced the pro-fibrotic activation of liver cells, and liver stiffness was higher in HBVTg mice compared with control mice. Elevation of HBV markers and OPN levels corresponded to decreased ISG activation in HBVTg CCl4 mice vs HBVTg control mice.

Conclusion

Based on our data, we conclude that liver stiffness enhances OPN levels to limit anti-viral ISG activation in hepatocytes and promote an increase in HBV infectivity, thereby contributing to end-stage liver disease progression.

Analysis of Aldehyde Dehydrogenase 2 as a Prognostic Marker Associated with Immune Cell infiltration and Chemotherapy Efficacy in Head and Neck Squamous Cell Carcinoma

Background: Previous investigations have demonstrated the role of Aldehyde Dehydrogenase 2 (ALDH2) levels in the cancer initiation and progression, prognosis, and treatment response in kinds of malignancies. However, its significance in the head and neck squamous cell carcinoma (HNSC) by different human papillomavirus (HPV) statuses remains unclear. Methods: We conducted an in-depth analysis of ALDH2 in HNSC using various bioinformatics tools, investigating its expression, alteration, differential levels, prognostic significance, molecular interactions, immune characteristics, and conducting experimental validation through immunohistochemistry (IHC) arrays and Western blot to compare expression levels between tumor and normal tissues, analyze the associations with clinicopathological features, and investigate its responses to chemotherapies. Results: ALDH2 levels are downregulated in HNSC tissues and associated with higher American Joint Committee on Cancer (AJCC) T classification and worse overall survival in HPV-unrelated HNSC, yet not in HPV-related HNSC. ALDH2 is positively regulated by copy-number variation and negatively regulated by DNA methylation. The association of ALDH2 with prognosis may be due to its interaction with ALDH6A1, and its co-expressed genes are predictive biomarkers of HNSC. We also found high ALDH2 levels in bulk tumors are associated with increased immune surveillance cells, such as naïve B cells and M1 macrophages in HPV-unrelated HNSC. IHC and western blot showed that ALDH2 is downregulated in the oral cavity, hypopharyngeal cancers, and well-differentiated carcinoma. In vitro, low ALDH2 levels showed reduced response to 5-fluorouracil in HNSC-derived cell lines. Conclusion: Our analyses revealed the genetic and cellular targets and drug response of ALDH2 in HNSC. We also found ALDH2 is involved in regulating the immune response of the tumor microenvironment, and high levels of ALDH2 in bulk HNSC may enhance antitumor immunity, which could improve prognosis. These findings suggest that ALDH2 could be a potential biomarker in improving risk stratification and tailoring treatment strategies in HNSC patients, especially in the HPV-unrelated subgroup.

Comprehensive investigating of mismatch repair genes (MMR) polymorphisms in participants with chronic hepatitis B virus infection

Background and aim: In this study, we focused on the relationship between single nucleotide polymorphisms in MMR genes and the occurrence and development of HBV infection. Materials and methods: A total of 3,128 participants were divided into five groups: negative control group (NeC), spontaneous clearance group (SC), chronic hepatitis B group (CHB), liver cirrhosis group (LC) and hepatocellular carcinoma group (HCC), CHB, liver cirrhosis and hepatocellular carcinoma constitute HLD. We conducted three case-control studies: NeC (840 cases) vs. HLD (1792 cases), SC (486 cases) vs. HLD (1792 cases) and CHB + LC (1,371 cases) vs. HCC (421 cases). 11 polymorphic loci in MLH1, MLH3, MSH5, PMS1 and PMS2 were involved in genotyping by Sequenom MassArray. The SNPStats performed Hardy-Weinberg equilibrium test. Linkage disequilibrium patterns were visualized using Haploview4.2. The GMDR (v0.9) was conducted to generalized multifactor dimension reduction analysis. The correlation, multiplicative interaction and additive interaction analyses were calculated by Logistic Regression through SPSS21.0. Matrix and programmed excel were also involved in the calculation of additive interaction. Results: In NeC vs. HLD group, MSH5-rs1150793(G) was a risk base to HBV susceptibility (nominal p = 0.002, OR = 1.346). We found multiplicative interaction between MLH1-rs1540354 (AA + AT) and PMS1-rs1233255 (AA) (nominal p = 0.024, OR = 1.240). There was additive interaction between PMS1-rs1233255 (AA) and PMS1-rs256554(CA + CC). In SC vs. HLD group, MLH1-rs1540354 (TT) was a risk genotype (nominal p < 0.05, OR>1). Through haplotype analysis, we found the linkage disequilibrium of three loci in MLH1. The results of GMDR showed the optimal five-locus model about the spontaneous clearance of HBV. In CHB + LC vs. HCC group, PMS2-rs12112229(A) was related to the cancerization of liver. Conclusion: We found rs1150793(G), rs1540354(T) and rs12112229(A) were significantly related to HBV susceptibility, spontaneous clearance of HBV and cancerization after infection, respectively.

An ultralong-acting tenofovir ProTide nanoformulation achieves monthslong HBV suppression

Treatment of chronic hepatitis B virus (HBV) requires lifelong daily therapy. However, suboptimal adherence to the existing daily therapy has led to the need for ultralong-acting antivirals. A lipophilic and hydrophobic ProTide was made by replacing the alanyl isopropyl ester present in tenofovir alafenamide (TAF) with a docosyl phenyl alanyl ester, now referred to as M1TFV. NM1TFV and nanoformulated TAF (NTAF) nanocrystals were formulated by high-pressure homogenization. A single intramuscular injection of NM1TFV, but not NTAF, delivered at a dose of TFV equivalents (168 milligrams per kilogram) demonstrated monthslong antiviral activities in both HBV-transgenic and human hepatocyte transplanted TK-NOG mice. The suppression of HBV DNA in blood was maintained for 3 months. Laboratory experiments on HBV-transfected HepG2.2.15 cells affirmed the animal results and the critical role of docosanol in the sustained NM1TFV antiviral responses. These results provide clear "proof of concept" toward an emerging therapeutic paradigm for the treatment and prevention of HBV infection.

Pathogenesis of Alcohol-Associated Liver Disease

Excessive alcohol consumption is a global healthcare problem with enormous social, economic, and clinical consequences. While chronic, heavy alcohol consumption causes structural damage and/or disrupts normal organ function in virtually every tissue of the body, the liver sustains the greatest damage. This is primarily because the liver is the first to see alcohol absorbed from the gastrointestinal tract via the portal circulation and second, because the liver is the principal site of ethanol metabolism. Alcohol-induced damage remains one of the most prevalent disorders of the liver and a leading cause of death or transplantation from liver disease. Despite extensive research on the pathophysiology of this disease, there are still no targeted therapies available. Given the multifactorial mechanisms for alcohol-associated liver disease pathogenesis, it is conceivable that a multitherapeutic regimen is needed to treat different stages in the spectrum of this disease.

Hepatitis B viral infection and role of alcohol

End-stage liver disease is frequently caused by hepatitis B virus (HBV) and alcohol consumption. Notably, the mechanism by which alcohol affects the course of HBV-associated liver disease is unknown, and additional research is needed in this area. A reduced immunological response, oxidative stress, endoplasmic reticulum stress, Golgi apparatus stress, and enhanced HBV replication are a few potential causes.

Mitochondrial Aldehyde Dehydrogenase 2 Represents a Potential Biomarker of Biochemical Recurrence in Prostate Cancer Patients

BACKGROUND

We aimed to explore the role of mitochondrial aldehyde dehydrogenase 2 (ALDH2) in prostate cancer (PCa) patients and provide insights into the tumor immune microenvironment (TME) for those patients undergoing radical radiotherapy.

METHODS

We performed all analyses using R version 3.6.3 and its suitable packages. Cytoscape 3.8.2 was used to establish network of competing endogenous RNAs (ceRNAs).

RESULTS

Downregulation of ADLH2 was significantly associated with higher risk of BCR-free survival (HR: 0.40, 95%CI: 0.24-0.68, p = 0.001) and metastasis-free survival (HR: 0.21, 95%CI: 0.09-0.49, p = 0.002). Additionally, ALDH2 repression contributed to significantly shorter BCR-free survival in the TCGA database (HR: 0.55, 95%CI: 0.33-0.93, p = 0.027). For immune checkpoints, patients that expressed a higher level of CD96 had a higher risk of BCR than their counterparts (HR: 1.79, 95%CI: 1.06-3.03, p = 0.032), as well as NRP1 (HR: 2.18, 95%CI: 1.29-3.69, p = 0.005). In terms of the TME parameters, the spearman analysis showed that ALDH was positively associated with B cells (r: 0.13), CD8+ T cells (r: 0.19), neutrophils (r: 0.13), and macrophages (r: 0.17). Patients with higher score of neutrophils (HR: 1.75, 95%CI: 1.03-2.95, p = 0.038), immune score (HR: 1.92, 95%CI: 1.14-3.25, p = 0.017), stromal score (HR: 2.52, 95%CI: 1.49-4.26, p = 0.001), and estimate score (HR: 1.81, 95%CI: 1.07-3.06, p = 0.028) had higher risk of BCR than their counterparts. Our ceRNA network found that PART1 might regulate the expression of ALDH via has-miR-578 and has-miR-6833-3p. Besides, PHA-793887, PI-103, and piperlongumine had better correlations with ALDH2.

CONCLUSIONS

We found that ALDH2 might serve as a potential biomarker predicting biochemical recurrence for PCa patients.

Cell-to-Cell Communications in Alcohol-Associated Liver Disease

This review covers some important new aspects of the alcohol-induced communications between liver parenchymal and non-parenchymal cells leading to liver injury development. The information exchange between various cell types may promote end-stage liver disease progression and involves multiple mechanisms, such as direct cell-to-cell interactions, extracellular vesicles (EVs) or chemokines, cytokines, and growth factors contained in extracellular fluids/cell culture supernatants. Here, we highlighted the role of EVs derived from alcohol-exposed hepatocytes (HCs) in activation of non-parenchymal cells, liver macrophages (LM), and hepatic stellate cells (HSC). The review also concentrates on EV-mediated crosstalk between liver parenchymal and non-parenchymal cells in the settings of HIV- and alcohol co-exposure. In addition, we overviewed the literature on the crosstalk between cell death pathways and inflammasome activation in alcohol-activated HCs and macrophages. Furthermore, we covered highly clinically relevant studies on the role of non-inflammatory factors, sinusoidal pressure (SP), and hepatic arterialization in alcohol-induced hepatic fibrogenesis. We strongly believe that the review will disclose major mechanisms of cell-to-cell communications pertained to alcohol-induced liver injury progression and will identify therapeutically important targets, which can be used for alcohol-associated liver disease (ALD) prevention.

Ethanol attenuates presentation of cytotoxic T-lymphocyte epitopes on hepatocytes of HBV-infected humanized mice

BACKGROUND AND AIMS

Approximately 3.5% of the global population is chronically infected with Hepatitis B Virus (HBV), which puts them at high risk of end-stage liver disease, with the risk of persistent infection potentiated by alcohol consumption. However, the mechanisms underlying the effects of alcohol on HBV persistence remain unclear. Here, we aimed to establish in vivo/ex vivo evidence that alcohol suppresses HBV peptides-major histocompatibility complex (MHC) class I antigen display on primary human hepatocytes (PHH), which diminishes the recognition and clearance of HBV-infected hepatocytes by cytotoxic T-lymphocytes (CTLs).

METHODS

We used fumarylacetoacetate hydrolase (Fah)-/-, Rag2-/-, common cytokine receptor gamma chain knock-out (FRG-KO) humanized mice transplanted with human leukocyte antigen-A2 (HLA-A2)-positive hepatocytes. The mice were HBV-infected and fed control and alcohol diets. Isolated hepatocytes were exposed ex vivo to HBV 18-27-HLA-A2-restricted CTLs to quantify cytotoxicity. For mechanistic studies, we measured proteasome activities, unfolded protein response (UPR), and endoplasmic reticulum (ER) stress in hepatocytes from HBV-infected humanized mouse livers.

RESULTS AND CONCLUSIONS

We found that alcohol feeding attenuated HBV core 18-27-HLA-A2 complex presentation on infected hepatocytes due to the suppression of proteasome function and ER stress induction, which diminished both the processing of HBV peptides and trafficking of HBV-MHC class I complexes to the hepatocyte surface. This alcohol-mediated decrease in MHC class I-restricted antigen presentation of the CTL epitope on target hepatocytes reduced the CTL-specific elimination of infected cells, potentially leading to HBV-infection persistence, which promotes end-stage liver disease outcomes.

Effects of alcohol consumption on viral hepatitis B and C

The liver is the main target organ for hepatitis viruses and the vital organ for alcohol metabolism. These two factors of viral hepatitis and alcohol abuse in combination can exert dual harmful actions, leading to enhanced damage to the liver. Epidemiological studies have revealed a higher prevalence of hepatitis C virus (HCV) infection among alcoholics than the general population. The interaction of alcohol with viral hepatitis [e.g., hepatitis B virus (HBV), HCV] and the underlying mechanisms are not fully understood. The effects of alcohol on viral hepatitis include promoted viral replication, weakened immune response, and increased oxidative stress. Clinically, alcohol abuse is correlated with an increased risk of developing end-stage liver cirrhosis and hepatocellular carcinoma in patients with chronic hepatitis B and C, suggesting that the combination of alcohol and HBV/HCV lead to more severe liver damage. The influence of mild to moderate alcohol drinking on the HBV-induced liver fibrosis, cirrhosis, and hepatocellular carcinoma among patients infected with HBV remains unclear. Unlike HBV infected patients, no safe level of alcohol intake has been established for patients with HCV. Even light to moderate alcohol use can exert a synergistic effect with viral hepatitis, leading to the rapid progression of liver disease. Furthermore, interferon-based therapy is less effective in alcohol drinkers than in control patients, even after abstinence from alcohol for a period of time. Therefore, abstaining from alcohol is highly recommended to protect the liver, especially in individuals with HBV/HCV infection, to improve the clinical efficacy of antiviral treatment and prevent the rapid progression of chronic viral hepatitis.

Alcohol-Induced Lysosomal Damage and Suppression of Lysosome Biogenesis Contribute to Hepatotoxicity in HIV-Exposed Liver Cells

Although the causes of hepatotoxicity among alcohol-abusing HIV patients are multifactorial, alcohol remains the least explored "second hit" for HIV-related hepatotoxicity. Here, we investigated whether metabolically derived acetaldehyde impairs lysosomes to enhance HIV-induced hepatotoxicity. We exposed Cytochrome P450 2E1 (CYP2E1)-expressing Huh 7.5 (also known as RLW) cells to an acetaldehyde-generating system (AGS) for 24 h. We then infected (or not) the cells with HIV-1_ADA then exposed them again to AGS for another 48 h. Lysosome damage was assessed by galectin 3/LAMP1 co-localization and cathepsin leakage. Expression of lysosome biogenesis-transcription factor, TFEB, was measured by its protein levels and by in situ immunofluorescence. Exposure of cells to both AGS + HIV caused the greatest amount of lysosome leakage and its impaired lysosomal biogenesis, leading to intrinsic apoptosis. Furthermore, the movement of TFEB from cytosol to the nucleus via microtubules was impaired by AGS exposure. The latter impairment appeared to occur by acetylation of α-tubulin. Moreover, ZKSCAN3, a repressor of lysosome gene activation by TFEB, was amplified by AGS. Both these changes contributed to AGS-elicited disruption of lysosome biogenesis. Our findings indicate that metabolically generated acetaldehyde damages lysosomes and likely prevents their repair and restoration, thereby exacerbating HIV-induced hepatotoxicity.

The role of ALDH2 in tumorigenesis and tumor progression: Targeting ALDH2 as a potential cancer treatment

A major mitochondrial enzyme for protecting cells from acetaldehyde toxicity is aldehyde dehydrogenase 2 (ALDH2). The correlation between ALDH2 dysfunction and tumorigenesis/growth/metastasis has been widely reported. Either low or high ALDH2 expression contributes to tumor progression and varies among different tumor types. Furthermore, the ALDH2∗2 polymorphism (rs671) is the most common single nucleotide polymorphism (SNP) in Asia. Epidemiological studies associate ALDH2∗2 with tumorigenesis and progression. This study summarizes the essential functions and potential ALDH2 mechanisms in the occurrence, progression, and treatment of tumors in various types of cancer. Our study indicates that ALDH2 is a potential therapeutic target for cancer therapy.

ALDH2 polymorphism rs671 is a predictor of PD-1/PD-L1 inhibitor efficacy against thoracic malignancies

Background

Aldehyde dehydrogenase 2 (ALDH2) plays an important role in the endogenous aldehyde detoxification of various types of cells. ALDH2*2, a variant allele of the ALDH2 polymorphism rs671, leads to decreased enzymatic activity. ALDH2*2 may enhance tumor antigen presentation due to aldehyde-induced DNA damage while suppressing peripheral blood T cell counts and T cell activation.

Methods

On the basis of our hypothesis that rs671 affects the sensitivity of immune checkpoint inhibitors (ICIs), we evaluated the effects of rs671 on patients with thoracic malignancies who started ICI therapy in 2016–2019. The cohort consisted of 105 cases, including 64 cases with adenocarcinoma and 30 cases with squamous cell carcinoma, 49 of whom were ALDH2*2 carriers. The first ICI was PD-1/PD-L1 inhibitor (Nivolumab, Pembrolizumab, or Atezolizumab) in all cases.

Results

The best response to anti-PD-1/PD-L1 therapy (partial response/stable disease/progressive disease) was 36%/50%/14% in the rs671(−) cases; however, the response was relatively poor in the rs671(+) cases (27%/29%/45%, respectively) (p = 0.002). The hazard ratio (95% confidence interval) of disease progression within the observation period of 6 months for the rs671(+) cases was estimated to be 5.0 (2.5–10) after the adjustment for covariates, including sex, Brinkman index, treatment line, tumor tissue programmed death-ligand 1 positivity rate, tumor tissue EGFR mutation. This association was also maintained in a stratified analysis, suggesting that ALDH2*2 is an independent negative predictive factor for the short-term prognosis of anti-PD-1/PD-L1 therapy. Thus, the progression-free survival (PFS) ratio of the rs671(+) cases decreased rapidly after ICI initiation but was eventually higher than that of the rs671(−) cases (restricted mean survival time in 12 months from 2 to 3 years afterward was 1.3 times that of the rs671(−) cases). Moreover, the highest PFS ratio after 2 years among sub-groups was found in the first-line treatment sub-group of rs671(+) group (40%).

Conclusions

Our study suggests that rs671 may be an accurate and cost-effective predictor of PD-1/PD-L1 inhibitor treatment, in which optimal case selection is an important issue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08329-y.

Alcohol Consumption in Rheumatoid Arthritis: A Path through the Immune System

Benefits and harms of different components of human diet have been known for hundreds of years. Alcohol is one the highest consumed, abused, and addictive substances worldwide. Consequences of alcohol abuse are increased risks for diseases of the cardiovascular system, liver, and nervous system, as well as reduced immune system function. Paradoxically, alcohol has also been a consistent protective factor against the development of autoimmune diseases such as type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis (RA). Here, we focused on summarizing current findings on the effects of alcohol, as well as of its metabolites, acetaldehyde and acetate, on the immune system and RA. Heavy or moderate alcohol consumption can affect intestinal barrier integrity, as well as the microbiome, possibly contributing to RA. Additionally, systemic increase in acetate negatively affects humoral immune response, diminishing TFH cell as well as professional antigen-presenting cell (APC) function. Hence, alcohol consumption has profound effects on the efficacy of vaccinations, but also elicits protection against autoimmune diseases. The mechanism of alcohol's negative effects on the immune system is multivariate. Future studies addressing alcohol and its metabolite acetate's effect on individual components of the immune system remains crucial for our understanding and development of novel therapeutic pathways.

Second hits exacerbate alcohol-related organ damage: an update

Chronic and excessive alcohol abuse cause direct and indirect detrimental effects on a wide range of body organs and systems and accounts for ~4% of deaths worldwide. Many factors influence the harmful effects of alcohol. This concise review presents newer insights into the role of select second hits in influencing the progression of alcohol-induced organ damage by synergistically acting to generate a more dramatic downstream biological defect. This review specifically addresses on how a lifestyle factor of high fat intake exacerbates alcoholic liver injury and its progression. This review also provides the mechanistic insights into how increasing matrix stiffness during liver injury promotes alcohol-induced fibrogenesis. It also discusses how hepatotropic viral (HCV, HBV) infections as well as HIV (which is traditionally not known to be hepatotropic), are potentiated by alcohol exposure to promote hepatotoxicity and fibrosis progression. Finally, this review highlights the impact of reactive aldehydes generated during alcohol and cigarette smoke coexposure impair innate antimicrobial defense and increased susceptibility to infections. This review was inspired by the symposium held at the 17th Congress of the European Society for Biomedical research on Alcoholism in Lille, France entitled 'Second hits in alcohol-related organ damage'.

Obeticholic acid attenuates human immunodeficiency virus/alcohol metabolism-induced pro-fibrotic activation in liver cells

BACKGROUND

The morbidity and mortality of human immunodeficiency virus (HIV)-infection is often associated with liver disease, which progresses slowly into severe liver dysfunction. There are multiple insults which exacerbate HIV-related liver injury, including HIV-associated dysregulation of lipid metabolism and fat turnover, co-infections with hepatotropic viruses and alcohol abuse. As we reported before, exposure of hepatocytes to HIV and alcohol metabolites causes high oxidative stress, impairs proteasomal and lysosomal functions leading to accumulation of HIV in these cells, which end-ups with apoptotic cell death and finally promotes development of liver fibrosis.

AIM

To study whether obeticholic acid (OCA) prevents HIV/ethanol metabolism-induced hepatotoxicity and subsequent activation of hepatic stellate cells (HSC) by HIV⁺ apoptotic hepatocyte engulfment.

METHODS

Huh7.5-CYP (RLW) cells were exposed to HIV and acetaldehyde-generating system (AGS) in the presence or absence of OCA. In the cells, we measured the expression of HIV-related markers: HIVgagRNA-by real-time polymerase chain reaction (PCR), p24- by western blot, HIV DNA-by semi-nested PCR, integrated HIV DNA-by ddPCR. Lysosomal and proteasomal activities were measured using fluorometrically-labeled substrates. For hepatocyte apoptosis, cleaved caspase 3 and cleaved PARP were visualized by western blot and cytokeratin 18- by M30 ELISA-in supernatants. Apoptotic bodies were generated from untreated and HIV-treated RLW cells exposed to UV light. Pro-fibrotic activation of HSC was characterized by Col1A1 and transforming growth factor-β mRNAs, while inflammasome activation- by NLRP3, caspase 1, interleukin (IL)-6, IL-1β mRNA levels.

RESULTS

In RLW cells, OCA treatment attenuated HIV-AGS-induced accumulation of HIVgagRNA, HIV DNA and p24. OCA suppressed reactive oxygen species production and restored chymotrypsin-like proteasome activity as well as cathepsin B lysosome activity. OCA also decreased HIV-AGS-triggered apoptosis in RLW cells. Exposure of HIV-containing apoptotic hepatocytes to HSC prevented activation of inflammasome and induced pro-fibrotic activation in these cells.

CONCLUSION

We conclude that by suppressing oxidative stress and restoring proteasomal and lysosomal functions impaired by HIV and ethanol metabolism, OCA decreases accumulation of HIV in hepatocytes, leading to down-regulation of apoptosis in these cells. In addition, OCA reverses pro-fibrotic and inflammasome-related activation of HSC triggered by engulfment of HIV-containing apoptotic hepatocytes, potentially contributing to suppression of liver fibrosis development.

Acetaldehyde suppresses HBV-MHC class I complex presentation on hepatocytes via induction of ER stress and Golgi fragmentation

Alcohol consumption worsens hepatitis B virus (HBV) infection pathogenesis. We have recently reported that acetaldehyde suppressed HBV peptide-major histocompatibility complex I (MHC class I) complex display on hepatocytes, limiting recognition and subsequent removal of the infected hepatocytes by HBV-specific cytotoxic T lymphocytes (CTLs). This suppression was attributed to impaired processing of antigenic peptides by the proteasome. However, in addition to proteasome dysfunction, alcohol may induce endoplasmic reticulum (ER) stress and Golgi fragmentation in HBV-infected liver cells to reduce uploading of viral peptides to MHC class I and/or trafficking of this complex to the hepatocyte surface. Hence, the aim of this study was to elucidate whether alcohol-induced ER stress and Golgi fragmentation affect HBV peptide-MHC class I complex presentation on HBV+ hepatocytes. Here, we demonstrate that, while both acetaldehyde and HBV independently cause ER stress and Golgi fragmentation, the combined exposure provided an additive effect. Thus we observed an activation of the inositol-requiring enzyme 1α-X-box binding protein 1 and activation transcription factor (ATF)6α, but not the phospho PKR-like ER kinase-phospho eukaryotic initiation factor 2α-ATF4-C/EBP homologous protein arms of ER stress in HBV-transfected cells treated with acetaldehyde-generating system (AGS). In addition, Golgi proteins trans-Golgi network 46, GM130, and Giantin revealed punctate distribution, indicating Golgi fragmentation upon AGS exposure. Furthermore, the effects of acetaldehyde were reproduced by treatment with ER stress inducers, thapsigargin and tunicamycin, which also decreased the display of this complex and MHC class I turnover in HepG2.2.15 cells and HBV-infected primary human hepatocytes. Taken together, alcohol-induced ER stress and Golgi fragmentation contribute to the suppression of HBV peptide-MHC class I complex presentation on HBV+ hepatocytes, which may diminish their recognition by CTLs and promote persistence of HBV infection in hepatocytes.NEW & NOTEWORTHY Our current findings show that acetaldehyde accelerates endoplasmic reticulum (ER) stress by activating the unfolded protein response arms inositol-requiring enzyme 1α-X-box binding protein 1 and activation transcription factor (ATF)6α but not phospho PKR-like ER kinase-p eukaryotic initiation factor 2α-ATF4-C/EBP homologous protein in hepatitis B virus (HBV)-transfected HepG2.2.15 cells. It also potentiates Golgi fragmentation, as evident by punctate distribution of Golgi proteins, GM130, trans-Golgi network 46, and Giantin. While concomitantly increasing HBV DNA and HBV surface antigen titers, acetaldehyde-induced ER stress suppresses the presentation of HBV peptide-major histocompatibility complex I complexes on hepatocyte surfaces, thereby promoting the persistence of HBV infection in the liver.

Role of non-Genetic Risk Factors in Exacerbating Alcohol-related organ damage

This review provides a summary of the symposium titled "Role of Non-Genetic Risk Factors in Exacerbating Alcohol-Related Organ Damage", which was held at the 42nd Annual Meeting of the Research Society on Alcoholism. The goals of the symposium were to provide newer insights into the role of non-genetic factors, including specific external factors, notably infectious agents or lifestyle factors, that synergistically act to exacerbate alcohol pathogenicity to generate more dramatic downstream biological defects. This summary of the symposium will benefit junior/senior basic scientists and clinicians currently investigating/treating alcohol-induced organ pathology, as well as undergraduate, graduate, and post-graduate students and fellows.

Role of alcohol in pathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) and alcohol abuse often contribute to the development of end-stage liver disease. Alcohol abuse not only causes rapid progression of liver disease in HBV infected patients but also allows HBV to persist chronically. Importantly, the mechanism by which alcohol promotes the progression of HBV-associated liver disease are not completely understood. Potential mechanisms include a suppressed immune response, oxidative stress, endoplasmic reticulum and Golgi apparatus stresses, and increased HBV replication. Certainly, more research is necessary to gain a better understanding of these mechanisms such that treatment(s) to prevent rapid liver disease progression in alcohol-abusing HBV patients could be developed. In this review, we discuss the aforementioned factors for the higher risk of liver diseases in alcohol-induced HBV pathogenies and suggest the areas for future studies in this field.

Alcohol Metabolism Potentiates HIV-Induced Hepatotoxicity: Contribution to End-Stage Liver Disease

In an era of improved survival due to modern antiretroviral therapy, liver disease has become a major cause of morbidity and mortality, resulting in death in 15-17% of human immunodeficiency virus (HIV)-infected patients. Alcohol enhances HIV-mediated liver damage and promotes the progression to advanced fibrosis and cirrhosis. However, the mechanisms behind these events are uncertain. Here, we hypothesize that ethanol metabolism potentiates accumulation of HIV in hepatocytes, causing oxidative stress and intensive apoptotic cell death. Engulfment of HIV-containing apoptotic hepatocytes by non-parenchymal cells (NPCs) triggers their activation and liver injury progression. This study was performed on primary human hepatocytes and Huh7.5-CYP cells infected with HIV-1ADA, and major findings were confirmed by pilot data obtained on ethanol-fed HIV-injected chimeric mice with humanized livers. We demonstrated that ethanol exposure potentiates HIV accumulation in hepatocytes by suppressing HIV degradation by lysosomes and proteasomes. This leads to increased oxidative stress and hepatocyte apoptosis. Exposure of HIV-infected apoptotic hepatocytes to NPCs activates the inflammasome in macrophages and pro-fibrotic genes in hepatic stellate cells. We conclude that while HIV and ethanol metabolism-triggered apoptosis clears up HIV-infected hepatocytes, continued generation of HIV-expressing apoptotic bodies may be detrimental for progression of liver inflammation and fibrosis due to constant activation of NPCs.