Type I interferons and endoplasmic reticulum stress in health and disease

Type I interferons (IFNs) comprise of pro-inflammatory cytokines created, as well as sensed, by all nucleated cells with the main objective of blocking pathogens-driven infections. Owing to this broad range of influence, type I IFNs also exhibit critical functions in many sterile inflammatory diseases and immunopathologies, especially those associated with endoplasmic reticulum (ER) stress-driven signaling pathways. Indeed, over the years accumulating evidence has indicated that the presence of ER stress can influence the production, or sensing of, type I IFNs induced by perturbations like pattern recognition receptor (PRR) agonists, infections (bacterial, viral or parasitic) or autoimmunity. In this article we discuss the link between type I IFNs and ER stress in various diseased contexts. We describe how ER stress regulates type I IFNs production or sensing, or how type I IFNs may induce ER stress, in various circumstances like microbial infections, autoimmunity, diabetes, cancer and other ER stress-related contexts.

The beginning of the end: what is the future of interferon therapy for chronic hepatitis C?

Interferon has been the backbone of therapy for hepatitis C virus (HCV) infection for over 20years. Initial response rates were poor, however they have slowly but steadily improved, such that with the addition of the nucleotide analogue ribavirin and the pegylation of interferon, over 50% of infected individuals could be cured with a course of therapy. However, interferon therapy is not ideal, requiring up to a year of weekly injections and associated with numerous systemic side effects. Advances in understanding of the HCV lifecycle have led to the development of numerous highly effective, well-tolerated oral direct acting antivirals (DAAs). Although the first DAAs were combined with peginterferon and ribavirin, with the rapid progress in the field, it is likely that interferon-free therapy will be available for most patients in the relatively near future. In the short term, peginterferon will be required with either the protease inhibitor simeprevir, or the nucleotide analogue polymerase inhibitor, sofosbuvir, for the treatment of genotype 1 infection. Peginterferon also appears to be a useful adjunct to sofosbuvir and ribavirin for patients with genotype 3 infection, particularly those with cirrhosis. In the future, once combination DAA therapies are available, peginterferon will serve a smaller and smaller role. Peginterferon may be useful as part of QUAD therapy with 2 DAAs and ribavirin in prior null responders or in patients who fail DAA regimens with multi-drug resistant HCV. Peginterferon may also have a role in resource-limited regions to reduce the number and/or duration of DAAs required. Ultimately, although peginterferon will remain a salvage therapy, its days as a mainstay of therapy are definitely numbered.

GILT restricts the cellular entry mediated by the envelope glycoproteins of SARS-CoV, Ebola virus and Lassa fever virus

Interferons (IFNs) control viral infections by inducing expression of IFN-stimulated genes (ISGs) that restrict distinct steps of viral replication. We report herein that gamma-interferon-inducible lysosomal thiol reductase (GILT), a lysosome-associated ISG, restricts the infectious entry of selected enveloped RNA viruses. Specifically, we demonstrated that GILT was constitutively expressed in lung epithelial cells and fibroblasts and its expression could be further induced by type II interferon. While overexpression of GILT inhibited the entry mediated by envelope glycoproteins of SARS coronavirus (SARS-CoV), Ebola virus (EBOV) and Lassa fever virus (LASV), depletion of GILT enhanced the entry mediated by these viral envelope glycoproteins. Furthermore, mutations that impaired the thiol reductase activity or disrupted the N-linked glycosylation, a posttranslational modification essential for its lysosomal localization, largely compromised GILT restriction of viral entry. We also found that the induction of GILT expression reduced the level and activity of cathepsin L, which is required for the entry of these RNA viruses in lysosomes. Our data indicate that GILT is a novel antiviral ISG that specifically inhibits the entry of selected enveloped RNA viruses in lysosomes via disruption of cathepsin L metabolism and function and may play a role in immune control and pathogenesis of these viruses.

Transcriptome Analyses Implicate Endogenous Retroviruses Involved in the Host Antiviral Immune System through the Interferon Pathway

Human endogenous retroviruses (HERVs) are the remains of ancient retroviruses that invaded our ancestors' germline cell and were integrated into the genome. The expression of HERVs has always been a cause for concern because of its association with various cancers and diseases. However, few previous studies have focused on specific activation of HERVs by viral infections. Our previous study has shown that dengue virus type 2 (DENV-2) infection induces the transcription of a large number of abnormal HERVs loci; therefore, the purpose of this study was to explore the relationship between exogenous viral infection and HERV activation further. In this study, we retrieved and reanalyzed published data on 21 transcriptomes of human cells infected with various viruses. We found that infection with different viruses could induce transcriptional activation of HERV loci. Through the comparative analysis of all viral datasets, we identified 43 key HERV loci that were up-regulated by DENV-2, influenza A virus, influenza B virus, Zika virus, measles virus, and West Nile virus infections. Furthermore, the neighboring genes of these HERVs were simultaneously up-regulated, and almost all such neighboring genes were interferon-stimulated genes (ISGs), which are enriched in the host's antiviral immune response pathways. Our data supported the hypothesis that activation of HERVs, probably via an interferon-mediated mechanism, plays an important role in innate immunity against viral infections.

ISG20 inhibits bluetongue virus replication

ISG20 is an interferon-inducible exonuclease that inhibits virus replication. Although ISG20 is thought to degrade viral RNA, the antiviral mechanism and specificity of ISG20 remain unclear. In this study, the antiviral role of ovine ISG20 (oISG20) in bluetongue virus ​(BTV) infection was investigated. It was found that BTV infection up-regulated the transcription of ovine ISG20 (oISG20) in a time- and BTV multiplicity of infection (MOI)-dependent manner. Overexpression of oISG20 suppressed the production of BTV genome, proteins, and virus titer, whereas the knockdown of oISG20 increased viral replication. oISG20 was found to co-localize with BTV proteins VP4, VP5, VP6, and NS2, but only directly interacted with VP4. Exonuclease defective oISG20 significantly decreased the inhibitory effect on BTV replication. In addition, the interaction of mutant oISG20 and VP4 was weakened, suggesting that binding to VP4 was associated with the inhibition of BTV replication. The present data characterized the anti-BTV effect of oISG20, and provides a novel clue for further exploring the inhibition mechanism of double-stranded RNA virus by ISG20.

Impact of the SARS-CoV-2 nucleocapsid 203K/204R mutations on the inflammatory immune response in COVID-19 severity

BACKGROUND

The excessive inflammatory responses provoked by SARS-CoV-2 infection are critical factors affecting the severity and mortality of COVID-19. Previous work found that two adjacent co-occurring mutations R203K and G204R (KR) on the nucleocapsid (N) protein correlate with increased disease severity in COVID-19 patients. However, links with the host immune response remain unclear.

METHODS

Here, we grouped nasopharyngeal swab samples of COVID-19 patients into two cohorts based on the presence and absence of SARS-CoV-2 nucleocapsid KR mutations. We performed nasopharyngeal transcriptome analysis of age, gender, and ethnicity-matched COVID-19 patients infected with either SARS-CoV-2 with KR mutations in the N protein (KR patients n = 39) or with the wild-type N protein (RG patients n = 39) and compared to healthy controls (n = 34). The impact of KR mutation on immune response was further characterized experimentally by transcriptomic and proteomic profiling of virus-like-particle (VLP) incubated cells.

RESULTS

We observed markedly elevated expression of proinflammatory cytokines, chemokines, and interferon-stimulated (ISGs) genes in the KR patients compared to RG patients. Using nasopharyngeal transcriptome data, we found significantly higher levels of neutrophils and neutrophil-to-lymphocyte (NLR) ratio in KR patients than in the RG patients. Furthermore, transcriptomic and proteomic profiling of VLP incubated cells confirmed a similar hyper-inflammatory response mediated by the KR variant.

CONCLUSIONS

Our data demonstrate an unforeseen connection between nucleocapsid KR mutations and augmented inflammatory immune response in severe COVID-19 patients. These findings provide insights into how mutations in SARS-CoV-2 modulate host immune output and pathogenesis and may contribute to more efficient therapeutics and vaccine development.

Early Changes in Interferon Gene Expression and Antibody Responses Following Influenza Vaccination in Pregnant Women

BACKGROUND

Influenza immunization during pregnancy provides protection to the mother and the infant. Studies in adults and children with inactivated influenza vaccine have identified changes in immune gene expression that were correlated with antibody responses. The current study was performed to define baseline blood transcriptional profiles and changes induced by inactivated influenza vaccine in pregnant women and to identify correlates with antibody responses.

METHODS

Pregnant women were immunized with inactivated influenza vaccine during the 2013-2014 and 2014-2015 seasons. Blood samples were collected on day 0 (before vaccination) and on days 1 and 7 after vaccination for transcriptional profile analyses, and on days 0 and 30, along with delivery and cord blood samples, to measure antibody titers.

RESULTS

Transcriptional analysis demonstrated overexpression of interferon-stimulated genes (ISGs) on day 1 and of plasma cell genes on day 7. Prevaccination ISG expression and ISGs overexpressed on day 1 were significantly correlated with increased H3N2, B Yamagata, and B Victoria antibody titers. Plasma cell gene expression on day 7 was correlated with increased B Yamagata and B Victoria antibody titers. Compared with women who were vaccinated during the previous influenza season, those who were not showed more frequent significant correlations between ISGs and antibody titers.

CONCLUSIONS

Influenza vaccination in pregnant women resulted in enhanced expression of ISGs and plasma cell genes correlated with antibody responses. Brief summary: This study identified gene expression profiles of interferon-stimulated genes and plasma cells before vaccination and early after vaccination that were correlated with antibody responses in pregnant women vaccinated for influenza.

Expressions of interferon-stimulated genes in peripheral blood mononuclear cells from patients with secondary syphilis

BACKGROUND

Syphilis is a sexually transmitted disease that threatens human health worldwide. However, the immune regulation cascade caused by treponemia pallidum (TP) infection remains still largely unclear.

METHODS

To investigate the expression of ISGs in secondary syphilis (SS), we recruited 64 patients with SS and equal number of healthy participants to obtain their peripheral blood mononuclear cells (PBMCs). qRT-PCR was performed to estimate the expression of interferon-stimulated genes (ISGs) including CXCL10, OAS3, OAS1, MX1, IFIT3, IFIT2, IFI6 and AIM2. Receiver-operating characteristic (ROC) analysis was adapted to diagnostic value of these genes to distinguish healthy controls and patients with SS.

RESULTS

ISGs including CXCL10, OAS3, OAS1, MX1, IFIT3, IFIT2, IFI6 and AIM2 were all upregulated in PBMCs of patients with SS. Area under the ROC curve (AUC) of the 8 ISGs were all more than 0.5. IFIT3 exhibited the highest diagnostic value, followed by AIM2, IFIT2 and CXCL10, according to the Yoden Index.

CONCLUSION

ISGs including CXCL10, OAS3, OAS1, MX1, IFIT3, IFIT2, IFI6 and AIM2 were upregulated in patients with SS and they have diagnostic value for syphilis.

Robust antiviral innate immune response and miRNA regulatory network were identified in ZIKV-infected cells: implications in the pathogenesis of ZIKV infection

Zika virus (ZIKV) infection has emerged as a significant public health concern due to its association with fetal microcephaly and Guillain-Barre syndrome (GBS). Unfortunately, its detailed pathogenesis remains unclear. To better understand how ZIKV evades host antiviral immunity, we analyzed the microarray dataset (GSE98889) of ZIKV-infected primary human brain microvascular endothelial cells (hBMECs) retrieved from the gene expression omnibus (GEO). 160, 1423, 969, 829, and 600 differentially expressed genes (DEGs) were identified at 12, 24, 48, 72, and 216 hours post-ZIKV infection in hBMECs, respectively. Subsequently, 31 common DEGs across all time-points were selected for further analysis. Gene ontology (GO) functional analysis showed these 31 DEGs were mainly involved in the host antiviral innate immune responses. Protein-protein interaction (PPI) network analysis identified 10 hub genes (MX1, OAS1, OAS2, IFI44, IFI44L, IFIT1, IFIT2, IFIT3, IFIH1, and XAF1), which were all interferon-stimulated genes (ISGs) and upregulated. qRT-PCR was used to validate the expression patterns of these 10 hub genes in different ZIKV-infected cell lines. Finally, miRNA-mRNA regulatory network analysis revealed that hsa-miR-129-2-3p, hsa-miR-138-5p, hsa-miR-21-3p, hsa-miR-27a-5p, hsa-miR-449a, and hsa-miR449b-5p were key miRNAs regulating these hub genes. Our study showed that ZIKV infection activated the host innate immune response to restrict ZIKV infection. The common pathways, hub genes, and their regulatory miRNA network offer new insights into virus-host interactions, enhancing our understanding of ZIKV pathogenesis.