Too much of a good thing: Detrimental effects of interferon

Synthesis and evaluation of alkoxy-substituted enamides against influenza A virus in vitro and in vivo

Alkoxy-substituted enamides are often used as synthetic intermediates due to their special reactivity. To the best our knowledge, the biological activity of alkoxy-substituted amines has never been reported so far. We have synthesized a series of alkoxy-substituted enamides to study their anti-influenza A virus activity in vitro and in vivo. Among these compounds, compound E-2o had the best antiviral activity (EC50 = 2.76 ± 0.67 μM) and low cytotoxicity (CC50 = 662.87 ± 24.85 μM). The mechanism of action of this compound was preliminarily explored by us. It alleviated the cytopathic effects and cell death caused by different subtypes of influenza A virus. Different drug delivery methods and timed dosing experiments had shown that E-2o had the best therapeutic effect and mainly played a role in the early stages of virus replication. The expansion of influenza viruses in cells was inhibited by reducing ROS accumulation, cell apoptosis, and autophagy. Alkoxy-substituted enamide E-2o reduced the production of interferon and other pro-inflammatory factors in the RIG-Ⅰ pathway and its downstream NF-κB was induced by influenza A virus in vitro and in vivo. It avoided damage in the mice which was caused by excessive inflammatory factors. In addition, the weight loss and lung lesion damage in mice caused by influenza virus were improved by compound E-2o. Therefore, Alkoxy-substituted enamide E-2o could inhibit the replication of influenza viruses in vivo and in vitro, and has the potential to be developed into a drug for treating influenza.

Epigenetics behind tumor immunology: a mini review

Immunogenic- and immune-therapies have become hot spots in the treatment of cancer. Although promising, these strategies are frequently associated with innate or acquired resistance, calling for combined targeting of immune inhibitory signals. Epigenetic therapy is attracting considerable attention as a combination partner for immune-based therapies due to its role in molding the state and fate of cancer and immune cells in the tumor microenvironment. Here, we describe epigenetic dysregulations in cancer, with a particular focus on those related to innate immune signaling and Type I interferons, and emphasize opportunities and current efforts to translate this knowledge into treatment regimens with improved clinical benefit.

Upregulation of IFN-stimulated genes persists beyond the transitory broad immunologic changes of acute HIV-1 infection

Chronic immune activation during HIV-1 infection contributes to morbidity and mortality in people living with HIV. To elucidate the underlying biological pathways, we evaluated whole blood gene expression trajectories from before, through acute, and into chronic HIV-1 infection. Interferon-stimulated genes, including MX1, IFI27 and ISG15, were upregulated during acute infection, remained elevated into chronic infection, and were strongly correlated with plasma HIV-1 RNA as well as TNF-α and CXCL10 cytokine levels. In contrast, genes involved in cellular immune responses, such as CD8A, were upregulated during acute infection before reaching a peak and returning to near pre-infection levels in chronic infection. Our results indicate that chronic immune activation during HIV-1 infection is characterized by persistent elevation of a narrow set of interferon-stimulated genes and innate cytokines. These findings raise the prospect of devising a targeted intervention to restore healthy immune homeostasis in people living with HIV-1.

IRF3 inhibits nuclear translocation of NF-κB to prevent viral inflammation

Interferon (IFN) regulatory factor 3 (IRF3) is a transcription factor activated by phosphorylation in the cytoplasm of a virus-infected cell; by translocating to the nucleus, it induces transcription of IFN-β and other antiviral genes. We have previously reported IRF3 can also be activated, as a proapoptotic factor, by its linear polyubiquitination mediated by the RIG-I pathway. Both transcriptional and apoptotic functions of IRF3 contribute to its antiviral effect. Here, we report a nontranscriptional function of IRF3, namely, the repression of IRF3-mediated NF-κB activity (RIKA), which attenuated viral activation of NF-κB and the resultant inflammatory gene induction. In Irf3^-/- mice, consequently, Sendai virus infection caused enhanced inflammation in the lungs. Mechanistically, RIKA was mediated by the direct binding of IRF3 to the p65 subunit of NF-κB in the cytoplasm, which prevented its nuclear import. A mutant IRF3 defective in both the transcriptional and the apoptotic activities was active in RIKA and inhibited virus replication. Our results demonstrated IRF3 deployed a three-pronged attack on virus replication and the accompanying inflammation.

Human guanylate binding proteins: nanomachines orchestrating host defense

Disease-causing microorganisms not only breach anatomical barriers and invade tissues but also frequently enter host cells, nutrient-enriched environments amenable to support parasitic microbial growth. Protection from many infectious diseases is therefore reliant on the ability of individual host cells to combat intracellular infections through the execution of cell-autonomous defense programs. Central players in human cell-autonomous immunity are members of the family of dynamin-related guanylate binding proteins (GBPs). The importance of these interferon-inducible GTPases in host defense to viral, bacterial, and protozoan pathogens has been established for some time; only recently, cell biological and biochemical studies that largely focused on the prenylated paralogs GBP1, GBP2, and GBP5 have provided us with robust molecular frameworks for GBP-mediated immunity. Specifically, the recent characterization of GBP1 as a bona fide pattern recognition receptor for bacterial lipopolysaccharide (LPS) disrupting the integrity of bacterial outer membranes through LPS aggregation, the discovery of a link between hydrolysis-induced GMP production by GBP1 and inflammasome activation, and the classification of GBP2 and GBP5 as inhibitors of viral envelope glycoprotein processing via suppression of the host endoprotease furin have paved the way for a vastly improved conceptual understanding of the molecular mechanisms by which GBP nanomachines execute cell-autonomous immunity. The herein discussed models incorporate our current knowledge of the antimicrobial, proinflammatory, and biochemical properties of human GBPs and thereby provide testable hypotheses that will guide future studies into the intricacies of GBP-controlled host defense and their role in human disease.

STAT1 gain-of-function heterozygous cell models reveal diverse interferon-signature gene transcriptional responses

Signal transducer and activator of transcription 1 (STAT1) gain-of-function (GOF) is an autosomal dominant immune disorder marked by wide infectious predisposition, autoimmunity, vascular disease, and malignancy. Its molecular hallmark, elevated phospho-STAT1 (pSTAT1) following interferon (IFN) stimulation, is seen consistently in all patients and may not fully account for the broad phenotypic spectrum associated with this disorder. While over 100 mutations have been implicated in STAT1 GOF, genotype-phenotype correlation remains limited, and current overexpression models may be of limited use in gene expression studies. We generated heterozygous mutants in diploid HAP1 cells using CRISPR/Cas9 base-editing, targeting the endogenous STAT1 gene. Our models recapitulated the molecular phenotype of elevated pSTAT1, and were used to characterize the expression of five IFN-stimulated genes under a number of conditions. At baseline, transcriptional polarization was evident among mutants compared with wild type, and this was maintained following prolonged serum starvation. This suggests a possible role for unphosphorylated STAT1 in the pathogenesis of STAT1 GOF. Following stimulation with IFNα or IFNγ, differential patterns of gene expression emerged among mutants, including both gain and loss of transcriptional function. This work highlights the importance of modeling heterozygous conditions, and in particular transcription factor-related disorders, in a manner which accurately reflects patient genotype and molecular signature. Furthermore, we propose a complex and multifactorial transcriptional profile associated with various STAT1 mutations, adding to global efforts in establishing STAT1 GOF genotype-phenotype correlation and enhancing our understanding of disease pathogenesis.

Crosstalk between Interleukin-1β and Type I Interferons Signaling in Autoinflammatory Diseases

Interleukin-1β (IL-1β) and type I interferons (IFNs) are major cytokines involved in autoinflammatory/autoimmune diseases. Separately, the overproduction of each of these cytokines is well described and constitutes the hallmark of inflammasomopathies and interferonopathies, respectively. While their interaction and the crosstalk between their downstream signaling pathways has been mostly investigated in the frame of infectious diseases, little information on their interconnection is still available in the context of autoinflammation promoted by sterile triggers. In this review, we will examine the respective roles of IL-1β and type I IFNs in autoinflammatory/rheumatic diseases and analyze their potential connections in the pathophysiology of some of these diseases, which could reveal novel therapeutic opportunities.

Genetics of Pediatric Immune-Mediated Diseases and Human Immunity

Primary immunodeficiency diseases (PIDs) are a rapidly growing, heterogeneous group of genetically determined diseases characterized by defects in the immune system. While individually rare, collectively PIDs affect between 1/1,000 and 1/5,000 people worldwide. The clinical manifestations of PIDs vary from susceptibility to infections to autoimmunity and bone marrow failure. Our understanding of the human immune response has advanced by investigation and discovery of genetic mechanisms of PIDs. Studying patients with isolated genetic variants in proteins that participate in complex signaling pathways has led to an enhanced understanding of host response to infection, and mechanisms of autoimmunity and autoinflammation. Identifying genetic mechanisms of PIDs not only furthers immunological knowledge but also benefits patients by dictating targeted therapies or hematopoietic stem cell transplantation. Here, we highlight several of these areas in the field of primary immunodeficiency, with a focus on the most recent advances.

Innate Immune Responses to Acute Viral Infection During Pregnancy

Immunological adaptations in pregnancy allow maternal tolerance of the semi-allogeneic fetus but also increase maternal susceptibility to infection. At implantation, the endometrial stroma, glands, arteries and immune cells undergo anatomical and functional transformation to create the decidua, the specialized secretory endometrium of pregnancy. The maternal decidua and the invading fetal trophoblast constitute a dynamic junction that facilitates a complex immunological dialogue between the two. The decidual and peripheral immune systems together assume a pivotal role in regulating the critical balance between tolerance and defense against infection. Throughout pregnancy, this equilibrium is repeatedly subjected to microbial challenge. Acute viral infection in pregnancy is associated with a wide spectrum of adverse consequences for both mother and fetus. Vertical transmission from mother to fetus can cause developmental anomalies, growth restriction, preterm birth and stillbirth, while the mother is predisposed to heightened morbidity and maternal death. A rapid, effective response to invasive pathogens is therefore essential in order to avoid overwhelming maternal infection and consequent fetal compromise. This sentinel response is mediated by the innate immune system: a heritable, highly evolutionarily conserved system comprising physical barriers, antimicrobial peptides (AMP) and a variety of immune cells—principally neutrophils, macrophages, dendritic cells, and natural killer cells—which express pattern-receptors that detect invariant molecular signatures unique to pathogenic micro-organisms. Recognition of these signatures during acute infection triggers signaling cascades that enhance antimicrobial properties such as phagocytosis, secretion of pro-inflammatory cytokines and activation of the complement system. As well as coordinating the initial immune response, macrophages and dendritic cells present microbial antigens to lymphocytes, initiating and influencing the development of specific, long-lasting adaptive immunity. Despite extensive progress in unraveling the immunological adaptations of pregnancy, pregnant women remain particularly susceptible to certain acute viral infections and continue to experience mortality rates equivalent to those observed in pandemics several decades ago. Here, we focus specifically on the pregnancy-induced vulnerabilities in innate immunity that contribute to the disproportionately high maternal mortality observed in the following acute viral infections: Lassa fever, Ebola virus disease (EVD), dengue fever, hepatitis E, influenza, and novel coronavirus infections.

Treatment with Commonly Used Antiretroviral Drugs Induces a Type I/III Interferon Signature in the Gut in the Absence of HIV Infection

Tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) are used for HIV treatment and prevention. Previously, we found that topical rectal tenofovir gel caused immunological changes in the mucosa. Here, we assess the effect of oral TDF/FTC in three HIV pre-exposure prophylaxis trials, two with gastrointestinal and one with cervicovaginal biopsies. TDF/FTC induces type I/III interferon-related (IFN I/III) genes in the gastrointestinal tract, but not blood, with strong correlations between the two independent rectal biopsy groups (Spearman r = 0.91) and between the rectum and duodenum (r = 0.81). Gene set testing also indicates stimulation of the type I/III pathways in the ectocervix and of cellular proliferation in the duodenum. mRNA sequencing, digital droplet PCR, proteomics, and immunofluorescence confirm IFN I/III pathway stimulation in the gastrointestinal tract. Thus, oral TDF/FTC stimulates an IFN I/III signature throughout the gut, which could increase antiviral efficacy but also cause chronic immune activation in HIV prevention and treatment settings.