Non-selective dampening of the host immune response after hepatitis C clearance and its association with circulating chemokine and endotoxin levels

BACKGROUND & AIMS

Direct-acting antiviral (DAA) therapy has revolutionized treatment for the hepatitis C virus (HCV). While DAA therapy is common, little is known about the intrahepatic immunological changes after sustained virologic response (SVR). We aim to describe transcriptional alterations of the gut microbiome and the liver after SVR.

METHODS

Twenty-two HCV patients were evaluated before and 9 months after 12 weeks of sofosbuvir/velpatasvir treatment. All achieved SVR. A liver biopsy, portal blood (direct portal vein cannulation), peripheral blood and stool samples were obtained. RNA-seq and immunofluorescent staining were performed on liver biopsies. RNA-seq and 16S rRNA metagenomics were performed on stool.

RESULTS

Differential expression within liver transcription showed 514 downregulated genes (FDR q < .05; foldchange > 2) enriched in inflammatory pathways; of note, GO:0060337, type 1 IFN signalling (p = 8e-23) and GO:0042742, defence response to bacterium (p = 8e-3). Interestingly, microbial products increased in the portal blood and liver after SVR. Due to the increase in microbial products, the gut microbiome was investigated. There was no dysbiosis by Shannon diversity index or Bacteroides/Firmicutes ratio. There was a differential increase in genes responsible for bacterial lipopolysaccharide production after SVR.

CONCLUSIONS

The decrease in the antiviral interferon pathway expression was expected after SVR; however, there was an unanticipated decrease in the transcription of genes involved in recognition and response to bacteria, which was associated with increased levels of microbial products. Finally, the alterations in the function of the gut microbiome are a promising avenue for further investigation of the gut-liver axis, especially in the context of the significant immunological changes noted after SVR.

Babesia BdFE1 esterase is required for the anti-parasitic activity of the ACE inhibitor fosinopril

Effective and safe therapies for the treatment of diseases caused by intraerythrocytic parasites are impeded by the rapid emergence of drug resistance and the lack of novel drug targets. One such disease is human babesiosis, which is a rapidly emerging tick-borne illness caused by Babesia parasites. In this study, we identified fosinopril, a phosphonate-containing, FDA-approved angiotensin converting enzyme (ACE) inhibitor commonly used as a prodrug for hypertension and heart failure, as a potent inhibitor of Babesia duncani parasite development within human erythrocytes. Cell biological and mass spectrometry analyses revealed that the conversion of fosinopril to its active diacid molecule, fosinoprilat, is essential for its antiparasitic activity. We show that this conversion is mediated by a parasite-encoded esterase, BdFE1, which is highly conserved among apicomplexan parasites. Parasites carrying the L238H mutation in the active site of BdFE1 failed to convert the prodrug to its active moiety and became resistant to the drug. Our data set the stage for the development of this class of drugs for the therapy of vector-borne parasitic diseases.

Longitudinal multi-omics analyses of the gut-liver axis reveals metabolic dysregulation in hepatitis C infection and cirrhosis

The gut and liver are connected via the portal vein, and this relationship, which includes the gut microbiome, is described as the gut-liver axis. Hepatitis C virus (HCV) can infect the liver and cause fibrosis with chronic infection. HCV has been associated with an altered gut microbiome; however, how these changes impact metabolism across the gut-liver axis and how this varies with disease severity and time is unclear. Here we used multi-omics analysis of portal and peripheral blood, faeces and liver tissue to characterize the gut-liver axis of patients with HCV across a fibrosis severity gradient before (n = 29) and 6 months after (n = 23) sustained virologic response, that is, no detection of the virus. Fatty acids were the major metabolites perturbed across the liver, portal vein and gut microbiome in HCV, especially in patients with cirrhosis. Decreased fatty acid degradation by hepatic peroxisomes and mitochondria was coupled with increased free fatty acid (FFA) influx to the liver via the portal vein. Metatranscriptomics indicated that Anaerostipes hadrus-mediated fatty acid synthesis influences portal FFAs. Both microbial fatty acid synthesis and portal FFAs were associated with enhanced hepatic fibrosis. Bacteroides vulgatus-mediated intestinal glycan breakdown was linked to portal glycan products, which in turn correlated with enhanced portal inflammation in HCV. Paired comparison of patient samples at both timepoints showed that hepatic metabolism, especially in peroxisomes, is persistently dysregulated in cirrhosis independently of the virus. Sustained virologic response was associated with a potential beneficial role for Methanobrevibacter smithii, which correlated with liver disease severity markers. These results develop our understanding of the gut-liver axis in HCV and non-HCV liver disease aetiologies and provide a foundation for future therapies.

Tip of the iceberg: A comprehensive review of liver disease in Inborn errors of immunity

Inborn errors of immunity (IEIs) consist of numerous rare, inherited defects of the immune system that affect about 500,000 people in the United States. As advancements in diagnosis through genetic testing and treatment with targeted immunotherapy and bone marrow transplant emerge, increasing numbers of patients survive into adulthood posing fresh clinical challenges. A large spectrum of hepatobiliary diseases now present in those with immunodeficiency diseases, leading to morbidity and mortality in this population. Awareness of these hepatobiliary diseases has lagged the improved management of the underlying disorders, leading to missed opportunities to improve clinical outcomes. This review article provides a detailed description of specific liver diseases occurring in various inborn errors of immunity. A generalized approach to diagnosis and management of hepatic complications is provided, and collaboration with hepatologists, immunologists, and pathologists is emphasized as a requirement for optimizing management and outcomes.

Microbial Translocation in the Context of Hepatitis B Infection and Hepatitis D Infection

BACKGROUND

Increased microbial translocation (MT) into the systemic circulation is associated with liver disease progression. Microbial translocation has yet to be completely defined in chronic hepatitis B virus (HBV) and chronic hepatitis delta virus (HDV).

METHODS

Our aim was to characterize MT and associated immune response in chronic HBV and HDV at various stages of disease. Serum from 53 HBV, 43 HDV, and 36 healthy control (HC) subjects was obtained. Subjects were categorized by aspartate aminotransferase-to-platelet ratio index into mild (<0.5), moderate, and severe (>1.0) disease. Cytokines, microbial products, and microbial deoxyribonucleic acid (DNA) levels were assessed in a single treatment-naive time point for each patient. Next-generation sequencing identified bacterial species present within patient sera.

RESULTS

The HBV and HDV subjects display higher serum concentrations of Gram-negative (G-) bacterial lipopolysaccharide and fungal beta-glucan compared with HC (all P < .01). Gram-positive (G+) bacterial peptidoglycan is higher in HBV compared to HDV and HC (both P < .0001). Within both disease cohorts, peptidoglycan correlates with interleukin (IL)-1b, IL-8, IL-12p70, and IL-13 (all Spearman's rho >0.45; P < .05). Next-generation sequencing from 7 subjects with detectable serum bacterial DNA revealed changes in abundance of bacterial taxa and a higher proportion of Gram-positive genera in severe disease. Greater G+/G- taxa ratio is associated with higher cytokine levels and disease markers.

CONCLUSIONS

The HBV and HDV patients display increased translocation of bacterial and fungal products into serum. An increased proportion of Gram-positive genera is associated with disease progression. Correlations of peptidoglycan with antimicrobial cytokines suggest that particular microbial classes may contribute to systemic inflammation and possibly disease progression.

BmGPAC, an Antigen Capture Assay for Detection of Active Babesia microti Infection

Human babesiosis is an emerging zoonotic infectious disease caused by intraerythrocytic protozoan parasites of the genus Babesia Most cases of human babesiosis are caused by Babesia microti and often manifest in individuals over the age of 50 years or in patients with a compromised immune system. Patients who develop symptomatic B. microti infections usually experience months of asymptomatic infection after the acute infection has resolved. About one-fifth of B. microti-infected adults never develop symptoms. These asymptomatically infected individuals sometimes donate blood and thus can transmit B. microti through blood transfusion. Current assays for detection of active B. microti infections can be used to screen donor blood prior to transfusion, but they rely primarily on microscopy or PCR methods, which have sensitivity and technical limitations. Here we report the development of an antigen capture enzyme-linked immunosorbent assay (BmGPAC) based on a major secreted immunodominant antigen of B. microti (BmGPI12/BmSA1), and we provide evidence that this assay is superior for detection of active B. microti infections, compared to available microscopy methods and serological assays. The assay has been evaluated using supernatants of B. microti-infected erythrocytes cultured in vitro, sera from B. microti-infected laboratory mice, and sera from wild mice and human patients. Our data suggest that the BmGPAC assay is a reliable assay for detection of active B. microti infections and is superior to real-time PCR and antibody assays for diagnosis of acute B. microti infections, screening of the blood supply, and epidemiological surveys of humans and animal reservoir hosts.