Neutrophil extracellular traps contribute to liver damage and increase defective low-density neutrophils in alcohol-associated hepatitis

BACKGROUND & AIMS

In alcohol-associated hepatitis (AH), inflammation and neutrophil counts correlate with poor clinical outcomes. Here, we investigated how neutrophils contribute to liver damage in AH.

METHODS

We isolated blood neutrophils from individuals with AH to examine neutrophil extracellular traps (NETs) and performed RNA sequencing to explore their unique characteristics.

RESULTS

We observed a significant increase in NET production in AH. We also observed a unique low-density neutrophil (LDN) population in individuals with AH and alcohol-fed mice that was not present in healthy controls. Transcriptome analysis of peripheral LDNs and high-density neutrophils (HDNs) from individuals with AH revealed that LDNs exhibit a functionally exhausted phenotype, while HDNs are activated. Indeed, AH HDNs exhibited increased resting reactive oxygen species (ROS) production and produced more ROS upon lipopolysaccharide stimulation than control HDNs, whereas AH LDNs failed to respond to lipopolysaccharide. We show that LDNs are generated from HDNs after alcohol-induced NET release in vitro, and this LDN subset has decreased functionality, including reduced phagocytic capacity. Moreover, LDNs showed reduced homing capacity and clearance by macrophage efferocytosis; therefore, dysfunctional neutrophils could remain in the circulation and liver. Depletion of both HDNs and LDNs in vivo prevented alcohol-induced NET production and liver damage in mice. Granulocyte-colony stimulating factor treatment also ameliorated alcohol-induced liver injury in mice.

CONCLUSION

Neutrophils contribute to liver damage through increased NET formation which increases defective LDNs in AH. Alcohol induces phenotypic changes in neutrophils; HDNs are activated whereas LDNs are defective. Our findings provide mechanistic insights that could guide the development of therapeutic interventions for AH.

IMPACT AND IMPLICATIONS

In this study we discovered heterogeneity of neutrophils in alcohol-associated hepatitis, including high-density and low-density neutrophils that show hyper-activated or exhausted transcriptomic profiles, respectively. We found that alcohol induces neutrophil extracellular trap (NET) formation, which contributes to liver damage. NET release by high-density neutrophils resulted in low-density neutrophils that reside in the liver and escape clean-up by macrophages. Our findings help to understand the opposing neutrophil phenotypes observed in individuals with alcohol-associated hepatitis and provide mechanistic insights that could guide therapeutic strategies targeting neutrophils.

Relationship Between Recreational Cannabis Use and Helicobacter pylori Infection

Background: Cannabis plant extracts suppress gastric acid secretion and inflammation, and promote gastroduodenal ulcer healing, all of which are triggered by Helicobacter Pylori infection (HPI). Here, we evaluate the association between cannabis use and HPI among a representative community sample. Materials and Methods: We identified respondents who completed cannabis use questions and were tested for HPI (H. pylori IgG antibody seropositivity) from the National Health and Nutrition Examination Survey III dataset (n=4556). Cannabis usage was categorized as ever-use (ever, never), cumulative lifetime use (>10-times, 1-10-times, never), or recent use (>31-days-ago, within-31-days, never). We calculated the crude and adjusted risk (prevalence rate ratio, cPRR and aPRR) of having HPI with cannabis use using generalized Poisson models (SAS 9.4). The models were adjusted for demographics and risk factors for HPI. Results: The prevalence of HPI was lower among ever versus never cannabis users (18.6% vs. 33%, p<0.0001). Cannabis use was associated with a decreased risk of HPI (cPRR: 0.56 confidence interval [95% CI: 0.47-0.67]; p<0.0001), which persisted after adjusting for demographics (aPRR: 0.75 [95% CI: 0.63-0.90]; p=0.0016) and comorbidities (aPRR: 0.79 [95% CI: 0.66-0.95]; p=0.0145). Further, individuals with >10-times lifetime cannabis use had a decreased risk of HPI compared with those with 1-10-times lifetime use (aPRR: 0.70 [95% CI: 0.55-0.89]; p=0.0011) and never-users (aPRR: 0.65 [95% CI: 0.50-0.84]; p=0.0002). Conclusion: Recreational cannabis use is associated with diminished risk of HPI. These observations suggest the need for additional research assessing the effects of medical cannabis formulations on HPI.

Reticulon-3 modulates the incorporation of replication competent hepatitis C virus molecules for release inside infectious exosomes

Background

Cell released microvesicles specifically, exosomes, play an important role in mediating immunologic escape, treatment resistance, and disease persistence of Hepatitis C virus (HCV) infection. Reports on the molecular compositions of exosomes released by cells under diverse conditions, especially during viral infections, suggest that their cargo contents are not randomly loaded. However, the precise molecular mechanisms directing the selective cargo sorting and loading inside infectious viral exosomes remains elusive.

Aim

To decipher the role of Reticulon 3 (RTN3) in the selective molecular cargo sorting and loading inside infectious viral exosomes during HCV infection.

Methods

We used Huh7 cells–JFH1 HCV infection and HCV Full-Length (FL) replicon systems. Additionally, we analyzed human liver and serum exosome samples from healthy and treatment naïve HCV infected individuals. Our experiments made use of molecular biology and immunology techniques.

Results

HCV infection (JFH1-Huh7 or HCV-FL replicon cells) was associated with increased RTN3L&S isoforms expression in cells and cell released exosomes. Accordingly, increased expression of RTN3L&S was observed in liver and serum exosome samples of HCV infected individuals compared to healthy controls. RNA-ChIP analysis revealed that RTN3L&S interacted with dsHCV RNA. Lentiviral CRISPR/Cas9 mediated knockdown (KD) of RTN3 and plasmid overexpression (OE) of wild type, C- and N-terminal deletion mutants of RTN3L&S in HCV- infected Huh7 cells differentially impacted the cellular release of infectious viral exosomes. RTN3L&S KD significantly decreased, while RTN3S OE significantly increased the number of Huh7 cell-released infectious exosomes. The C-terminal domain of RTN3 interacted with and modulated the loading of dsHCV RNA inside infectious exosomes. Antiviral treatment of HCV infected Huh7 cells reduced virus-induced RTN3L&S expression and attenuated the release of infectious exosomes.

Conclusion

RTN3 constitutes a novel regulator and a potential therapeutic target that mediates the specific loading of infectious viral exosomes.

Reduced Prevalence of Alcoholic Gastritis in Hospitalized Individuals Who Consume Cannabis

BACKGROUND

Alcoholic gastritis, a superficial erosive disease of the stomach, is a common manifestation of risky alcohol use. In contrast, cannabis which is frequently co-used with alcohol suppresses gastric acidity and might counteract the deleterious effect of alcohol on the gastric mucosa. However, no clinical study has examined the impact of cannabis use on the development of alcoholic gastritis among risky alcohol users.

METHODS

We analyzed hospital discharge records of adults (age ≥ 18 years), from 2014 of the Nationwide Inpatient Sample, with a diagnosis of risky alcohol use (n = 316,916). We used a propensity-based matching algorithm to match cannabis users to nonusers on 1:1 ratio (30,713: 30,713). We then measured the adjusted relative risk (aRR) for having alcoholic gastritis using conditional Poisson regression models with generalized estimating equations.

RESULTS

Our study revealed that among risky alcohol users, cannabis co-users have a lower prevalence of alcoholic gastritis compared to noncannabis users (1,289 [1,169 to 1,421] vs. 1,723 [1,583 to 1,875] per 100,000 hospitalizations for risky alcohol use), resulting in a 25% decreased probability of alcoholic gastritis (aRR: 0.75 [0.66 to 0.85]; p-value <0.0001). Furthermore, dependent cannabis usage resulted in a lower prevalence of alcoholic gastritis when compared to both nondependent cannabis users (0.72 [0.52 to 0.99]) and to noncannabis users (0.56 [0.41 to 0.76]).

CONCLUSIONS

We reveal that risky alcohol drinking combined with cannabis use is associated with reduced prevalence of alcohol-associated gastritis in patients. Given increased cannabis legislation globally, understanding whether and how the specific ingredients in cannabis plant extract can be used in the treatment of alcoholic gastritis is paramount. In this regard, further molecular mechanistic studies are needed to delineate the mechanisms of our novel findings not only for alcoholic gastritis but also for gastritis from other causes.

Abnormal neutrophil traps and impaired efferocytosis contribute to liver injury and sepsis severity after binge alcohol use

BACKGROUND & AIMS

Neutrophil extracellular traps (NETs) are an important strategy utilized by neutrophils to immobilize and kill invading microorganisms. Herein, we studied NET formation and the process of neutrophil cell death (NETosis), as well as the clearance of NETs by macrophages (MΦ) (efferocytosis) in acute sepsis following binge drinking.

METHODS

Healthy volunteers consumed 2 ml of vodka/kg body weight, before blood endotoxin and 16 s rDNA were measured. Peripheral neutrophils were isolated and exposed to alcohol followed by phorbol 12-myristate 13-acetate (PMA) stimulation. Mice were treated with three alcohol binges and intraperitoneal lipopolysaccharide (LPS) to assess the dynamics of NET formation and efferocytosis. In vivo, anti-Ly6G antibody (IA8) was used for neutrophil depletion.

RESULTS

Inducers of NETs (endotoxin and bacterial DNA) significantly increased in the circulation after binge alcohol drinking in humans. Ex vivo, alcohol alone increased NET formation, but upon PMA stimulation alcohol attenuated NET formation. Binge alcohol in mice resulted in a biphasic response to LPS. Initially, binge alcohol reduced LPS-induced NET formation and resulted in a diffuse distribution of neutrophils in the liver compared to alcohol-naïve mice. Moreover, indicators of NET formation including citrullinated histone H3, neutrophil elastase, and neutrophil myeloperoxidase were decreased at an early time point after LPS challenge in mice receiving binge alcohol, suggesting decreased NET formation. However, in the efferocytosis phase (15 h after LPS) citrullinated histone-H3 was increased in the liver in alcohol binge mice, suggesting decreased clearance of NETs. In vitro alcohol treatment reduced efferocytosis and phagocytosis of NETotic neutrophils and promoted expression of CD206 on MΦ. Finally, depletion of neutrophils prior to binge alcohol ameliorated LPS-induced systemic inflammation and liver injury in mice.

CONCLUSIONS

Dysfunctional NETosis and efferocytosis following binge drinking exacerbate liver injury associated with sepsis.

LAY SUMMARY

Disease severity in alcoholic liver disease (ALD) is associated with a significant presence of neutrophils (a type of immune cell) in the liver. It remains unknown how alcohol affects the capacity of neutrophils to control infection, a major hallmark of ALD. We found that binge alcohol drinking impaired important strategies used by neutrophils to contain and resolve infection, resulting in increased liver injury during ALD.

Cannabis use is associated with reduced prevalence of non-alcoholic fatty liver disease: A cross-sectional study

Cannabis use is associated with reduced prevalence of obesity and diabetes mellitus (DM) in humans and mouse disease models. Obesity and DM are a well-established independent risk factor for non-alcoholic fatty liver disease (NAFLD), the most prevalent liver disease globally. The effects of cannabis use on NAFLD prevalence in humans remains ill-defined. Our objective is to determine the relationship between cannabis use and the prevalence of NAFLD in humans. We conducted a population-based case-control study of 5,950,391 patients using the 2014 Healthcare Cost and Utilization Project (HCUP), Nationwide Inpatient Survey (NIS) discharge records of patients 18 years and older. After identifying patients with NAFLD (1% of all patients), we next identified three exposure groups: non-cannabis users (98.04%), non-dependent cannabis users (1.74%), and dependent cannabis users (0.22%). We adjusted for potential demographics and patient related confounders and used multivariate logistic regression (SAS 9.4) to determine the odds of developing NAFLD with respects to cannabis use. Our findings revealed that cannabis users (dependent and non-dependent) showed significantly lower NAFLD prevalence compared to non-users (AOR: 0.82[0.76-0.88]; p<0.0001). The prevalence of NAFLD was 15% lower in non-dependent users (AOR: 0.85[0.79-0.92]; p<0.0001) and 52% lower in dependent users (AOR: 0.49[0.36-0.65]; p<0.0001). Among cannabis users, dependent patients had 43% significantly lower prevalence of NAFLD compared to non-dependent patients (AOR: 0.57[0.42-0.77]; p<0.0001). Our observations suggest that cannabis use is associated with lower prevalence of NAFLD in patients. These novel findings suggest additional molecular mechanistic studies to explore the potential role of cannabis use in NAFLD development.