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Enterovirus D68 (EV-D68), a respiratory RNA virus in the family Picornaviridae, is implicated as a potential etiological agent for acute flaccid myelitis in preteen adolescents. The absence of a specific therapeutic intervention necessitates the development of an effective animal model for EV-D68. The AG129 mouse strain, characterized by the double knockout of IFN-α/β and IFN-γ receptors on the 129 genetic background, has been proposed as a suitable model for EV-D68. The goals of this study were to assess the effect of a nonmouse-adapted EV-D68 strain (US/MO/14-18947, NR-49129) in AG129 (IFN-α/β and IFN-γ receptors null), A129 (IFN-α/β receptor null), G129 (IFN-γ receptor null), and the 129 background strain (129S2/SvPasCrl) when infected intraperitoneally at 10 d of age. Both AG129 and A129 strains demonstrated similar clinical signs (paralysis, paresis, lethargy, dyspnea [characterized by prominent abdominal respiration], and morbidity requiring euthanasia) induced by EV-D68. While G129 and 129S2 strains also exhibited susceptibility to EV-D68, the severity of clinical signs was less than in AG129 and A129 strains, and many survived to the experimental endpoint. Histopathological and immunohistochemical data confirmed EV-D68 tropism for the skeletal muscle and spinal cord and suggest that the dyspnea observed in infected mice could be attributed, in part, to lesions in the diaphragmatic skeletal muscles. These findings contribute valuable insights into the pathogenesis of EV-D68 infection in this mouse model and provide investigators with key information on virus dose and mouse strain selection when using this mouse model to evaluate candidate EV-D68 therapeutics.

Zika virus, a mosquito-borne arbovirus, has repeatedly caused large pandemics with symptoms worsening from mild and self-limiting diseases to Guillain-Barré syndrome in adults and fetal microcephaly in newborns. In recent years, Zika virus diseases have posed a serious threat to human health. The shortage of susceptible small animal models makes it difficult to study pathogenic mechanisms and evaluate potential therapies for Zika virus infection. Therefore, we chose immunocompromised mice (AG129 mice) deficient in IFN-α/β and IFN-γ receptors, which can abolish the innate immune system that prevents Zika virus infection early. AG129 mice were infected with the Zika virus, and this mouse model exhibited replication dynamics, tissue tropism, pathological lesion and immune activation of the Zika virus. Our results suggest that the inoculum dose of Zika virus can affect the viral replication dynamics, cytokine responses and survival rate in AG129 mice. By testing the potential antiviral drug favipiravir, several critical indicators, including replication dynamics and survival rates, were identified in AG129 mice after Zika virus infection. It is suggested that the model is reliable for drug evaluation. In brief, this model provides a potential platform for studies of the infectivity, virulence, and pathogenesis of the Zika virus. Moreover, the development of an accessible mouse model of Zika virus infection will expedite the research and deployment of therapeutics and vaccines., (© 2024. The Author(s).)

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by approximately 21 genetic defects, including a mutation in Interferon-Gamma Receptor 1 (IFNGR1). IFNGR1 deficiency leads to a loss of cellular responsiveness to type II Interferon (IFN-γ), which plays a significant role in controlling intracellular bacteria. This study explored the response of IFN-β therapy in a patient with partial IFNGR1 deficiency to treat invasive mycobacterial infection. The biological therapy was used successfully as an adjuvant to anti-mycobacterial medications to treat a 17-year-old girl with partial IFNGR1 deficiency who presented with a recurrent mycobacterial infection that extended to her central nervous system, which resulted in clinical and radiological improvement. This report suggests that activation of type I IFN through Signal Transducers and Activators of Transcription1 (STAT1) could bypass the early IFN-γ signaling defects and activate IFN-γ production. For that reason, IFN-β might be used as a beneficial adjuvant therapy for managing extensive central nervous system mycobacterial infection, especially in patients with IFNGR1 deficiency., Competing Interests: Declaration of Competing Interest None declared., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

We encountered two patients with partial interferon γ receptor 1 (IFN-γR1) deficiency in whom early diagnosis enhanced disease management. Patient 1 was a 44-year-old woman with enlarged lymph nodes diagnosed in a pre-pregnancy checkup, and pathological examination revealed a Mycobacterium avium infection. Based on her history of unknown multiple osteomyelitis during early childhood, mendelian susceptibility to mycobacterial disease was suspected. Genetic analysis revealed a novel heterozygous variant in IFNGR1. Genetic counseling was administered to the patient and her husband before they had their baby. Patient 2 was a 4-month-old boy whose father was previously diagnosed with autosomal dominant IFN-γR1 deficiency owing to Bacille de Calmette et Guérin (BCG) osteomyelitis. Genetic analysis showed that he had the same INFGR1 variant. He avoided BCG vaccination and has been disease-free since then. Early diagnosis is considered to be useful for genetic counseling and essential for preventing BCG osteomyelitis., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Patients with Mendelian susceptibility to mycobacterial disease (MSMD) experience recurrent and/or persistent infectious diseases associated with poorly virulent mycobacteria. Multifocal osteomyelitis is among the representative manifestations of MSMD. The frequency of multifocal osteomyelitis is especially high in patients with MSMD etiologies that impair cellular response to IFN-γ, such as IFN-γR1, IFN-γR2, or STAT1 deficiency., Objectives: This study sought to characterize the mechanism underlying multifocal osteomyelitis in MSMD., Methods: GM colonies prepared from bone marrow mononuclear cells from patients with autosomal dominant (AD) IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 gain of function (GOF) and from healthy controls were differentiated into osteoclasts in the presence or absence of IFN-γ. The inhibitory effect of IFN-γ on osteoclastogenesis was investigated by quantitative PCR, immunoblotting, tartrate-resistant acid phosphatase staining, and pit formation assays., Results: Increased osteoclast numbers were identified by examining the histopathology of osteomyelitis in patients with AD IFN-γR1 deficiency or AD STAT1 deficiency. In the presence of receptor activator of nuclear factor kappa-B ligand and M-CSF, GM colonies from patients with AD IFN-γR1 deficiency, AD STAT1 deficiency, or STAT1 GOF differentiated into osteoclasts, similar to GM colonies from healthy volunteers. IFN-γ concentration-dependent inhibition of osteoclast formation was impaired in GM colonies from patients with AD IFN-γR1 deficiency or AD STAT1 deficiency, whereas it was enhanced in GM colonies from patients with STAT1 GOF., Conclusions: Osteoclast differentiation is increased in AD IFN-γR1 deficiency and AD STAT1 deficiency due to an impaired response to IFN-γ, leading to excessive osteoclast proliferation and, by inference, increased bone resorption in infected foci, which may underlie multifocal osteomyelitis., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

A pivotal role of type I interferons in systemic lupus erythematosus (SLE) is widely accepted. Type III interferons (IFN-λ) however, the most recently discovered cytokines grouped within the interferon family, have not been extensively studied in lupus disease models yet. Growing evidence suggests a role for IFN-λ in regulating both innate and adaptive immune responses, and increased serum concentrations have been described in multiple autoimmune diseases including SLE. Using the pristane-induced lupus model, we found that mice with defective IFN-λ receptors ( Ifnlr1 -/- ) showed increased survival rates, decreased lipogranuloma formation and reduced anti-dsDNA autoantibody titers in the early phase of autoimmunity development compared to pristane-treated wild-type mice. Moreover, Ifnlr1 -/- mice treated with pristane had reduced numbers of inflammatory mononuclear phagocytes and cNK cells in their kidneys, resembling untreated control mice. Systemically, circulating B cells and monocytes (CD115 + Ly6C + ) were reduced in pristane-treated Ifnlr1 -/- mice. The present study supports a significant role for type III interferons in the pathogenesis of pristane-induced murine autoimmunity as well as in systemic and renal inflammation. Although the absence of type III interferon receptors does not completely prevent the development of autoantibodies, type III interferon signaling accelerates the development of autoimmunity and promotes a pro-inflammatory environment in autoimmune-prone hosts.

Mastitis is an inflammation of the mammary gland in the breast and is typically due to bacterial infection. In malaria-endemic areas, mastitis with accompanying fever can be challenging to differentiate from malaria. At the same time, it is unclear whether malaria infection is directly involved in the development of mastitis. In the present study, whether mastitis develops during infection with malaria parasites was investigated using a rodent malaria model with Plasmodium berghei (P. berghei; Pb) ANKA. The course of parasitemia in postpartum mice infected with Pb ANKA was similar to the course in infected virgin mice. However, infected postpartum mice died earlier than did infected virgin mice. In addition, the weight of pups from mice infected with Pb ANKA was significantly reduced compared with pups from uninfected mice. The macroscopic and histological analyses showed apparent changes, such as destruction of the alveolus wall and extensive presence of leukocytes, in mammary gland tissue in mice infected during the postpartum period. The findings suggest that women during the postpartum period are more vulnerable to complications when infected with malaria parasites, particularly women who do not acquire protective immunity against malaria parasites. Based on the proteomic analysis, IFN-γ signaling pathway-related proteins in mammary gland tissue of the infected postpartum mice were increased. Our results indicate that inflammation induced by IFN-γ, a proinflammatory cytokine, may contribute to negative histological changes in mammary gland tissue of postpartum mice infected with Pb ANKA. In IFN-γ receptor 1-deficient (IFNGR1-KO) mice, the histological changes in mammary gland tissue of the infected postpartum wild-type mice were improved to almost normal mammary gland structure. Furthermore, weight loss in pups delivered by infected IFNGR1-KO postpartum mice was not observed. Taken together, these findings indicate that inflammation induced by IFN-γ is associated with development of mastitis in postpartum mice infected with Pb ANKA. The present study results may increase our understanding of how disease aggravation occurs during postpartum malaria., Competing Interests: The authors have declared that no competing interests exist.

Arthropod-borne rickettsial pathogens cause mild and severe human disease worldwide. The tick-borne pathogen Rickettsia parkeri elicits skin lesions (eschars) and disseminated disease in humans; however, inbred mice are generally resistant to infection. We report that intradermal infection of mice lacking both interferon receptors ( Ifnar1 -/- ;Ifngr1 -/- ) with as few as 10 R . parkeri elicits eschar formation and disseminated, lethal disease. Similar to human infection, eschars exhibited necrosis and inflammation, with bacteria primarily found in leukocytes. Using this model, we find that the actin-based motility factor Sca2 is required for dissemination from the skin to internal organs, and the outer membrane protein OmpB contributes to eschar formation. Immunizing Ifnar1 -/- ;Ifngr1 -/- mice with sca2 and ompB mutant R. parkeri protects against rechallenge, revealing live-attenuated vaccine candidates. Thus, Ifnar1 -/- ;Ifngr1 -/- mice are a tractable model to investigate rickettsiosis, virulence factors, and immunity. Our results further suggest that discrepancies between mouse and human susceptibility may be due to differences in interferon signaling., Competing Interests: TB, CT, IL, DG, DE, EH, MW None, PE none, (© 2021, Burke et al.)

Lambda interferons mediate antiviral immunity by inducing interferon-stimulated genes (ISGs) in epithelial tissues. A common variant rs368234815TT/∆G creating functional gene from an IFNL4 pseudogene is associated with the expression of major ISGs in the liver but impaired clearance of hepatitis C. To explain this, we compared Halo-tagged and non-tagged IFNL3 and IFNL4 signaling in liver-derived cell lines. Transfection with non-tagged IFNL3, non-tagged IFNL4 and Halo-tagged IFNL4 led to a similar degree of JAK-STAT activation and ISG induction; however, the response to transfection with Halo-tagged IFNL3 was lower and delayed. Transfection with non-tagged IFNL3 or IFNL4 induced no transcriptome change in the cells lacking either IL10R2 or IFNLR1 receptor subunits. Cytosolic overexpression of signal peptide-lacking IFNL3 or IFNL4 in wild type cells did not interfere with JAK-STAT signaling triggered by interferons in the medium. Finally, expression profile changes induced by transfection with non-tagged IFNL3 and IFNL4 were highly similar. These data do not support the hypothesis about IFNL4-specific non-canonical signaling and point out that functional studies conducted with tagged interferons should be interpreted with caution.

Viruses have devised highly effective approaches that modulate the host immune response, blocking immune responses that are designed to eradicate viral infections. Over millions of years of evolution, virus-derived immune-modulating proteins have become extraordinarily potent, in some cases working at picomolar concentrations when expressed into surrounding tissues and effectively blocking host defenses against viral invasion and replication. The marked efficiency of these immune-modulating proteins is postulated to be due to viral engineering of host immune modulators as well as design and development of new strategies (i.e., some derived from host proteins and some entirely unique). Two key characteristics of viral immune modulators confer both adaptive advantages and desirable functions for therapeutic translation. First, many virus-derived immune modulators have evolved structures that are not readily recognized or regulated by mammalian immune pathways, ensuring little to no neutralizing antibody responses or proteasome-mediated degradation. Second, these immune modulators tend to target early steps in central immune responses, producing a powerful downstream inhibitory "domino effect" which may alter cell activation and gene expression.We have proposed that peptide metabolites of these immune-modulating proteins can enhance and extend protein function. Active immunomodulating peptides have been derived from both mammalian and viral proteins. We previously demonstrated that peptides derived from computationally predicted cleavage sites in the reactive center loop (RCL) of a viral serine proteinase inhibitor (serpin ) from myxoma virus, Serp-1 , can modify immune response activation. We have also demonstrated modulation of host gut microbiota produced by Serp-1 and RCL-derived peptide , S7, in a vascular inflammation model. Of interest, generation of derived peptides that maintain therapeutic function from a serpin can act by a different mechanism. Whereas Serp-1 has canonical serpin-like function to inhibit serine proteases, S7 instead targets mammalian serpins. Here we describe the derivation of active Serp- RCL peptides and their testing in inflammatory vasculitis models.

Cognitive impairment, acute or long-term, is a common complication in patients with severe bacterial infection. However, the underlying mechanisms are not fully verified and effective medicine is not available in clinics. Interferon gamma (IFNγ) is a pivotal cytokine against infection and is believed to be a tune in homeostasis of cognitive function. Here, we collected blood and cerebrospinal fluid (CF) from human subjects and mice, and found that plasma and CF levels of IFNγ were significantly increased in septic patients and endotoxin-challenged mice when compared with healthy controls. IFNγ signaling was boosted in the hippocampus of mice after a challenge of lipopolysaccharide (LPS), which was accompanied with cognitive impairment and decline of neurogenesis. Deficiency of IFNγ or its receptor (IFNγR) dramatically attenuated microglia-induced A1 astrocytes and consequently restored neurogenesis and cognitive function in endotoxemia mice model. Using primary microglia, astrocytes and neurons, we found that IFNγ remarkably increased LPS-mediated release of TNFα and IL-1α in microglia and consequently induced the transformation of astrocyte to A1 subtype, which ultimately resulted in neuron damage. Thus, IFNγ promotes cognitive impairment in endotoxemia by enhancing microglia-induced A1 astrocytes. Targeting IFNγ would be a novel strategy for preventing or treating cognitive dysfunction in patients with Gram-negative infection., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Summary : We characterized Mycobacterium bovis BCG isolates found in lung and brain samples from a previously vaccinated patient with IFNγR1 deficiency. The isolates collected displayed distinct genomic and phenotypic features consistent with host adaptation and associated changes in antibiotic susceptibility and virulence traits. Background : We report a case of a patient with partial recessive IFNγR1 deficiency who developed disseminated BCG infection after neonatal vaccination (BCG-vaccine). Distinct M. bovis BCG-vaccine derived clinical strains were recovered from the patient's lungs and brain. Methods : BCG strains were phenotypically (growth, antibiotic susceptibility, lipid) and genetically (whole genome sequencing) characterized. Mycobacteria cell infection models were used to assess apoptosis, necrosis, cytokine release, autophagy, and JAK-STAT signaling. Results : Clinical isolates BCG-brain and BCG-lung showed distinct Rv0667 rpoB mutations conferring high- and low-level rifampin resistance; the latter displayed clofazimine resistance through Rv0678 gene (MarR-like transcriptional regulator) mutations. BCG-brain and BCG-lung showed mutations in fadA2, fadE5, and mymA operon genes, respectively. Lipid profiles revealed reduced levels of PDIM in BCG-brain and BCG-lung and increased TAGs and Mycolic acid components in BCG-lung, compared to parent BCG-vaccine. In vitro infected cells showed that the BCG-lung induced a higher cytokine release, necrosis, and cell-associated bacterial load effect when compared to BCG-brain; conversely, both strains inhibited apoptosis and altered JAK-STAT signaling. Conclusions : During a chronic-disseminated BCG infection, BCG strains can evolve independently at different sites likely due to particular microenvironment features leading to differential antibiotic resistance, virulence traits resulting in dissimilar responses in different host tissues.

It is controversially discussed whether immune-deficient mice experience severity in the absence of infection. Because a comprehensive analysis of the well-being of immune-deficient mice under specific pathogen free conditions is missing, we used a multi-parametric test analyzing, corticosterone, weight, nest building and facial expression over a period of 9 month to determine the well-being of two immune-deficient mouse lines (recombination activating gene 2- and interferon gamma receptor-deficient mice). We do not find evidence for severity when comparing immune-deficient mice to their heterozygous immune-competent littermates. Our data challenge the assumption that immune-deficiency per se regardless of housing conditions causes severity. Based on our study we propose to use objective non-invasive parameters determined by laboratory animal science for decisions concerning severity of immune-deficient mice., Competing Interests: The authors declare that they do not have any competing interests.

Natural killer (NK) cells are important components of the innate immune defense against infections and cancers. Signal transducer and activator of transcription 1 (STAT1) is a transcription factor that is essential for NK cell maturation and NK cell-dependent tumor surveillance. Two alternatively spliced isoforms of STAT1 exist: a full-length STAT1α and a C-terminally truncated STAT1β isoform. Aberrant splicing is frequently observed in cancer cells and several anti-cancer drugs interfere with the cellular splicing machinery. To investigate whether NK cell-mediated tumor surveillance is affected by a switch in STAT1 splicing, we made use of knock-in mice expressing either only the STAT1α ( Stat1 α/α ) or the STAT1β ( Stat1 β / β ) isoform. NK cells from Stat1 α/α mice matured normally and controlled transplanted tumor cells as efficiently as NK cells from wild-type mice. In contrast, NK cells from Stat1 β/β mice showed impaired maturation and effector functions, albeit less severe than NK cells from mice that completely lack STAT1 ( Stat1 -/- ). Mechanistically, we show that NK cell maturation requires the presence of STAT1α in the niche rather than in NK cells themselves and that NK cell maturation depends on IFNγ signaling under homeostatic conditions. The impaired NK cell maturation in Stat1 β/β mice was paralleled by decreased IL-15 receptor alpha (IL-15Rα) surface levels on dendritic cells, macrophages and monocytes. Treatment of Stat1 β/β mice with exogenous IL-15/IL-15Rα complexes rescued NK cell maturation but not their effector functions. Collectively, our findings provide evidence that STAT1 isoforms are not functionally redundant in regulating NK cell activity and that the absence of STAT1α severely impairs, but does not abolish, NK cell-dependent tumor surveillance., (Copyright © 2020 Meissl, Simonović, Amenitsch, Witalisz-Siepracka, Klein, Lassnig, Puga, Vogl, Poelzl, Bosmann, Dohnal, Sexl, Müller and Strobl.)

Interferon-γ receptor 1 (IFNγR1) deficiency is one of the inborn errors of IFN-γ immunity underlying Mendelian Susceptibility to Mycobacterial Disease (MSMD). This molecular circuit plays a crucial role in regulating the interaction between dendritic cells (DCs) and T lymphocytes, thus affecting DCs activation, maturation, and priming of T cells involved in the immune response against intracellular pathogens. We studied a girl who developed at the age of 2.5 years a Mycobacterium avium infection characterized by disseminated necrotizing granulomatous lymphadenitis, and we compared her findings with other patients with the same genetic condition. The patient carried a heterozygous 818del4 mutation in the IFNGR1 gene responsible of autosomal dominant (AD) partial IFNγR1 deficiency. During the acute infection blood cells immunophenotyping showed a marked reduction in DCs counts, including both myeloid (mDCs) and plasmacytoid (pDCs) subsets, that reversed after successful prolonged antimicrobial therapy. Histology of her abdomen lymph node revealed a profound depletion of tissue pDCs, as compared to other age-matched granulomatous lymphadenitis of mycobacterial origin. Circulating DCs depletion was also observed in another patient with AD partial IFNγR1 deficiency during mycobacterial infection. To conclude, AD partial IFNγR1 deficiency can be associated with a transient decrease in both circulating and tissular DCs during acute mycobacterial infection, suggesting that DCs counts monitoring might constitute a useful marker of treatment response., (Copyright © 2020 Dotta, Vairo, Giacomelli, Moratto, Tamassia, Vermi, Lonardi, Casanova, Bustamante, Giliani and Badolato.)

Type I and III IFNs play diverse roles in bacterial infections, being protective for some but deleterious for others. Using RNA-sequencing transcriptomics we investigated lung gene expression responses to Bordetella pertussis infection in adult mice, revealing that type I and III IFN pathways may play an important role in promoting inflammatory responses. In B. pertussis- infected mice, lung type I/III IFN responses correlated with increased proinflammatory cytokine expression and with lung inflammatory pathology. In mutant mice with increased type I IFN receptor (IFNAR) signaling, B. pertussis infection exacerbated lung inflammatory pathology, whereas knockout mice with defects in type I IFN signaling had lower levels of lung inflammation than wild-type mice. Curiously, B. pertussis -infected IFNAR1 knockout mice had wild-type levels of lung inflammatory pathology. However, in response to infection these mice had increased levels of type III IFN expression, neutralization of which reduced lung inflammation. In support of this finding, B. pertussis -infected mice with a knockout mutation in the type III IFN receptor (IFNLR1) and double IFNAR1/IFNLR1 knockout mutant mice had reduced lung inflammatory pathology compared with that in wild-type mice, indicating that type III IFN exacerbates lung inflammation. In marked contrast, infant mice did not upregulate type I or III IFNs in response to B. pertussis infection and were protected from lethal infection by increased type I IFN signaling. These results indicate age-dependent effects of type I/III IFN signaling during B. pertussis infection and suggest that these pathways represent targets for therapeutic intervention in pertussis., (Copyright © 2020 by The American Association of Immunologists, Inc.)

During the 2013-2016 Ebola virus (EBOV) epidemic, a significant number of patients admitted to Ebola treatment units were co-infected with Plasmodium falciparum, a predominant agent of malaria. However, there is no consensus on how malaria impacts EBOV infection. The effect of acute Plasmodium infection on EBOV challenge was investigated using mouse-adapted EBOV and a biosafety level 2 (BSL-2) model virus. We demonstrate that acute Plasmodium infection protects from lethal viral challenge, dependent upon interferon gamma (IFN-γ) elicited as a result of parasite infection. Plasmodium-infected mice lacking the IFN-γ receptor are not protected. Ex vivo incubation of naive human or mouse macrophages with sera from acutely parasitemic rodents or macaques programs a proinflammatory phenotype dependent on IFN-γ and renders cells resistant to EBOV infection. We conclude that acute Plasmodium infection can safeguard against EBOV by the production of protective IFN-γ. These findings have implications for anti-malaria therapies administered during episodic EBOV outbreaks in Africa., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Interferon γ (IFN-γ) was shown to be a macrophage activating factor already in 1984. Consistently, inborn errors of IFN-γ immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD). MSMD is characterized by genetic predisposition to disease caused by weakly virulent mycobacterial species. Paradoxically, macrophages from patients with MSMD were little tested. Here, we report a disease modeling platform for studying IFN-γ related pathologies using macrophages derived from patient specific induced pluripotent stem cells (iPSCs). We used iPSCs from patients with autosomal recessive complete- and partial IFN-γR2 deficiency, partial IFN-γR1 deficiency and complete STAT1 deficiency. Macrophages from all patient iPSCs showed normal morphology and IFN-γ-independent functionality like phagocytic uptake of bioparticles and internalization of cytokines. For the IFN-γ-dependent functionalities, we observed that the deficiencies played out at various stages of the IFN-γ pathway, with the complete IFN-γR2 and complete STAT1 deficient cells showing the most severe phenotypes, in terms of upregulation of surface markers and induction of downstream targets. Although iPSC-derived macrophages with partial IFN-γR1 and IFN-γR2 deficiency still showed residual induction of downstream targets, they did not reduce the mycobacterial growth when challenged with Bacillus Calmette-Guérin. Taken together, we report a disease modeling platform to study the role of macrophages in patients with inborn errors of IFN-γ immunity.

Blau syndrome (BS) is an auto-inflammatory granulomatous disease that possibly involves abnormal response to interferon gamma (IFNγ) due to exaggerated nucleotide-binding oligomerization domain containing 2 (NOD2) activity. Mendelian susceptibility to mycobacterial diseases (MSMD) is an infectious granulomatous disease that is caused by impaired production of or response to IFNγ. We report a mother and daughter who are both heterozygous for NOD2 c.2264C˃T variant and dominant-negative IFNGR1 818del4 mutation. The 17-year-old patient displayed an altered form of BS and milder form of MSMD, whereas the 44-year-old mother was completely asymptomatic. This experiment of nature supports the notion that IFNγ is an important driver of at least some BS manifestations and that elucidation of its involvement in the disease immunopathogenesis may identify novel therapeutic targets.

New opportunities are needed to increase immune checkpoint blockade (ICB) benefit. Whereas the interferon (IFN)γ pathway harbors both ICB resistance factors and therapeutic opportunities, this has not been systematically investigated for IFNγ-independent signaling routes. A genome-wide CRISPR/Cas9 screen to sensitize IFNγ receptor-deficient tumor cells to CD8 T cell elimination uncovered several hits mapping to the tumor necrosis factor (TNF) pathway. Clinically, we show that TNF antitumor activity is only limited in tumors at baseline and in ICB non-responders, correlating with its low abundance. Taking advantage of the genetic screen, we demonstrate that ablation of the top hit, TRAF2, lowers the TNF cytotoxicity threshold in tumors by redirecting TNF signaling to favor RIPK1-dependent apoptosis. TRAF2 loss greatly enhanced the therapeutic potential of pharmacologic inhibition of its interaction partner cIAP, another screen hit, thereby cooperating with ICB. Our results suggest that selective reduction of the TNF cytotoxicity threshold increases the susceptibility of tumors to immunotherapy., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Inflammatory activation of CD8 + T cells can, when left unchecked, drive severe immunopathology. Hyperstimulation of CD8 + T cells through a broad set of triggering signals can precipitate hemophagocytic lymphohistiocytosis (HLH), a life-threatening systemic inflammatory disorder., Objective: The mechanism linking CD8 + T-cell hyperactivation to pathology is controversial, with excessive production of IFN-γ and, more recently, excessive consumption of IL-2, which are proposed as competing hypotheses. We formally tested the proximal mechanistic events of each pathway in a mouse model of HLH., Methods: In addition to reporting a complete autosomal recessive IFN-γ receptor 1-deficient patient with multiple aspects of HLH pathology, we used the mouse model of perforin (Prf1) KO mice infected with lymphocytic choriomeningitis virus to genetically eliminate either IFN-γ production or CD25 expression and assess the immunologic, hematologic, and physiologic disease measurement., Results: We found a striking dichotomy between the mechanistic basis of the hematologic and inflammatory components of CD8 + T cell-mediated pathology. The hematologic features of HLH were completely dependent on IFN-γ production, with complete correction after loss of IFN-γ production without any role for CD8 + T cell-mediated IL-2 consumption. By contrast, the mechanistic contribution of the immunologic features was reversed, with no role for IFN-γ production but substantial correction after reduction of IL-2 consumption by hyperactivated CD8 + T cells. These results were complemented by the characterization of an IFN-γ receptor 1-deficient patients with HLH-like disease, in whom multiple aspects of HLH pathology were observed in the absence of IFN-γ signaling., Conclusion: These results synthesize the competing mechanistic models of HLH pathology into a dichotomous pathogenesis driven through discrete pathways. A holistic model provides a new paradigm for understanding HLH and, more broadly, the consequences of CD8 + T-cell hyperactivation, thereby paving the way for clinical intervention based on the features of HLH in individual patients., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Converging evidence supports the involvement of pro-inflammatory pathways and the gut microbiome in major depressive disorder (MDD). Pre-clinical and clinical studies suggest that decreasing pro-inflammatory signaling may provide clinical benefit in MDD. In this study, we used the chronic unpredictable stress (CUS) paradigm to assess whether mice lacking the pro-inflammatory caspase 1, interferon gamma-receptor, and nitric oxide synthase (Casp1, Ifngr, Nos2) -/- present altered depressive- and anxiety-like behaviour at baseline and in response to CUS. In comparison to wild-type (wt) mice, (Casp1, Ifngr, Nos2) -/- mice displayed decreased depressive- and anxiety-like behaviour, and increased hedonic-like behaviour and locomotor activity at baseline, and resistance to developing anhedonic-like behaviour and a heightened emotional state following stress. Plasma levels of ACTH and CORT did not differ between the triple knockout and wt mice following stress. The faecal microbiome of (Casp1, Ifngr, Nos2) -/- mice differed from that of wt mice at baseline and displayed reduced changes in response to chronic stress. Our results demonstrate that simultaneous deficit in multiple pro-inflammatory pathways has antidepressant-like effects at baseline, and confers resilience to stress-induced anhedonic-like behaviour. Moreover, accompanying changes in the gut microbiome composition suggest that CASP1, IFNGR and NOS2 play a role in maintaining microbiome homeostasis.

Interferon-γ (IFN-γ) plays an important role in innate and adaptive immunity against intracellular infections and is used clinically for the prevention and control of infections in chronic granulomatous disease (CGD) and inborn defects in the IFN-γ/interleukin (IL)-12 axis. Using transcriptome profiling (RNA-seq), we sought to identify differentially expressed genes, transcripts and exons in Epstein-Barr virus-transformed B lymphocytes (B-EBV) cells from CGD patients, IFN-γ receptor deficiency patients, and normal controls, treated in vitro with IFN-γ for 48 hours. Our results show that IFN-γ increased the expression of a diverse array of genes related to different cellular programs. In cells from normal controls and CGD patients, IFN-γ-induced expression of genes relevant to oxidative killing, nitric oxide synthase pathway, proteasome-mediated degradation, antigen presentation, chemoattraction, and cell adhesion. IFN-γ also upregulated genes involved in diverse stages of messenger RNA (mRNA) processing including pre-mRNA splicing, as well as others implicated in the folding, transport, and assembly of proteins. In particular, differential exon expression of WARS (encoding tryptophanyl-transfer RNA synthetase, which has an essential function in protein synthesis) induced by IFN-γ in normal and CGD cells suggests that this gene may have an important contribution to the benefits of IFN-γ treatment for CGD. Upregulation of mRNA and protein processing related genes in CGD and IFNRD cells could mediate some of the effects of IFN-γ treatment. These data support the concept that IFN-γ treatment may contribute to increased immune responses against pathogens through regulation of genes important for mRNA and protein processing., (© 2018 Wiley Periodicals, Inc.)

As a critical step during innate response, the cytoplasmic β subunit (IFN-γR2) of interferon-γ receptor (IFN-γR) is induced and translocates to plasma membrane to join α subunit to form functional IFN-γR to mediate IFN-γ signaling. However, the mechanism driving membrane translocation and its significance remain largely unknown. We found, unexpectedly, that mice deficient in E-selectin, an endothelial cell-specific adhesion molecule, displayed impaired innate activation of macrophages upon Listeria monocytogenes infection yet had increased circulating IFN-γ. Inflammatory macrophages from E-selectin-deficient mice had less surface IFN-γR2 and impaired IFN-γ signaling. BTK elicited by extrinsic E-selectin engagement phosphorylates cytoplasmic IFN-γR2, facilitating EFhd2 binding and promoting IFN-γR2 trafficking from Golgi to cell membrane. Our findings demonstrate that membrane translocation of cytoplasmic IFN-γR2 is required to activate macrophage innate response against intracellular bacterial infection, identifying the assembly of functional cytokine receptors on cell membrane as an important layer in innate activation and cytokine signaling., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background & Aims: Despite inducing an inflammatory response, Helicobacter pylori can persist in the gastric mucosa for decades. H pylori expression of cholesterol-α-glucosyltransferase (encoded by cgt) is required for gastric colonization and T-cell activation. We investigated how cgt affects gastric epithelial cells and the host immune response., Methods: MKN45 gastric epithelial cells, AGS cells, and human primary gastric epithelial cells (obtained from patients undergoing gastrectomy or sleeve resection or gastric antral organoids) were incubated with interferon gamma (IFNG) or interferon beta (IFNB) and exposed to H pylori, including cagPAI and cgt mutant strains. Some cells were incubated with methyl-β-cyclodextrin (to deplete cholesterol from membranes) or myriocin and zaragozic acid to prevent biosynthesis of sphingolipids and cholesterol and analyzed by immunoblot, immunofluorescence, and reverse transcription quantitative polymerase chain reaction analyses. We compared gene expression patterns among primary human gastric cells, uninfected or infected with H pylori P12 wt or P12Δcgt, using microarray analysis. Mice with disruption of the IFNG receptor 1 (Ifngr1-/- mice) and C57BL6 (control) mice were infected with PMSS1 (wild-type) or PMSS1Δcgt H pylori; gastric tissues were collected and analyzed by reverse transcription quantitative polymerase chain reaction or confocal microscopy., Results: In primary gastric cells and cell lines, infection with H pylori, but not cgt mutants, blocked IFNG-induced signaling via JAK and STAT. Cells infected with H pylori were depleted of cholesterol, which reduced IFNG signaling by disrupting lipid rafts, leading to reduced phosphorylation (activation) of JAK and STAT1. H pylori infection of cells also blocked signaling by IFNB, interleukin 6 (IL6), and IL22 and reduced activation of genes regulated by these signaling pathways, including cytokines that regulate T-cell function (MIG and IP10) and anti-microbial peptides such as human β-defensin 3 (hBD3). We found that this mechanism allows H pylori to persist in proximity to infected cells while inducing inflammation only in the neighboring, non-infected epithelium. Stomach tissues from mice infected with PMSS1 had increased levels of IFNG, but did not express higher levels of interferon-response genes. Expression of the IFNG-response gene IRF1 was substantially higher in PMSS1Δcgt-infected mice than PMSS1-infected mice. Ifngr1-/- mice were colonized by PMSS1 to a greater extent than control mice., Conclusions: H pylori expression of cgt reduces cholesterol levels in infected gastric epithelial cells and thereby blocks IFNG signaling, allowing the bacteria to escape the host inflammatory response. These findings provide insight into the mechanisms by which H pylori might promote gastric carcinogenesis (persisting despite constant inflammation) and ineffectiveness of T-cell-based vaccines against H pylori., (Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The mosquito-borne disease dengue is caused by four serologically- and genetically-related viruses, termed DENV-1 to DENV-4. Historical setbacks due to lack of human-like mouse models of dengue were partially remedied with characterization of lethal DENV-2 infection in immunocompromised AG129 mice (deficient in IFN-α/β/γ receptors). Recently, our group established lethal AG129 mouse infection models of DENV-1, DENV-3, and DENV-4 using human isolates. Here we compare a non-lethal, disseminated model of DENV-3 infection using strain D83-144 to that of the lethal outcome following infection by strain C0360/94. Both strains belong to DENV-3 genotype II and differ by only 13 amino acids. Intraperitoneal inoculation of AG129 mice with strain D83-144 led to clinical signs of dengue infection, such as cytokine induction, thrombocytopenia, and systemic infection. However, C0360/94 infection led to features of severe human dengue, including coagulopathy and lethal outcome, whereas D83-144 infection does not. This study is the first to investigate a low passage, non-mouse lethal strain in AG129 mice and demonstrates that D83-144 infection induces milder features of human dengue than those induced by lethal C0360/94 infection. The results suggest that the AG129 mouse model has applications to investigate factors associated with mild or severe disease.

Few animal models of Zika virus (ZIKV) infection have incorporated arthropod-borne transmission. Here, we establish an Aedes aegypti mosquito model of ZIKV infection of mice, and demonstrate altered vector competency among three strains, (Orlando, ORL, Ho Chi Minh, HCM, and Patilas, PAT). All strains acquired ZIKV in their midguts after a blood meal from infected mice, but ZIKV transmission only occurred in mice fed upon by HCM, and to a lesser extent PAT, but not ORL, mosquitoes. This defect in transmission from ORL or PAT mosquitoes was overcome by intrathoracic injection of ZIKV into mosquito. Genetic analysis revealed significant diversity among these strains, suggesting a genetic basis for differences in ability for mosquito strains to transmit ZIKV. The intrathoracic injection mosquito-mouse transmission model is critical to understanding the influence of mosquitoes on ZIKV transmission, infectivity and pathogenesis in the vertebrate host, and represents a natural transmission route for testing vaccines and therapeutics.

Enterovirus D68 (EV-D68) caused a large outbreak in the summer and fall of 2014 in the United States. It causes serious respiratory disease, but causation of associated paralysis is controversial, because the virus is not routinely identified in cerebrospinal fluid. To establish clinical correlates with human disease, we evaluated EV-D68 infection in non-lethal paralysis mouse models. Ten-day-old mice lacking interferon responses were injected intraperitoneally with the virus. Paralysis developed in hindlimbs. After six weeks of paralysis, the motor neurons were depleted due to viral infection. Hindlimb muscles were also infected and degenerating. Even at the earliest stage of paralysis, muscles were still infected and were degenerating, in addition to presence of virus in the spinal cord. To model natural respiratory infection, five-day-old mice were infected intranasally with EV-D68. Two of the four infected mice developed forelimb paralysis. The affected limbs had muscle disease, but no spinal cord infection was detected. The unique contributions of this study are that EV-D68 causes paralysis in mice, and that causation by muscle disease, with or without spinal cord disease, may help to resolve the controversy that the virus can cause paralysis, even if it cannot be identified in cerebrospinal fluid., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of interferon gamma (IFNγ) immunity and is characterized by severe infections by weakly virulent mycobacteria. Although IFNγ is the macrophage-activating factor, macrophages from these patients have never been studied. We demonstrate the generation of heterozygous and compound heterozygous (iMSMD-cohet) induced pluripotent stem cells (iPSCs) from a single chimeric patient, who suffered from complete autosomal recessive IFNγR1 deficiency and received bone-marrow transplantation. Loss of IFNγR1 expression had no influence on the macrophage differentiation potential of patient-specific iPSCs. In contrast, lack of IFNγR1 in iMSMD-cohet macrophages abolished IFNγ-dependent phosphorylation of STAT1 and induction of IFNγ-downstream targets such as IRF-1, SOCS-3, and IDO. As a consequence, iMSMD-cohet macrophages show impaired upregulation of HLA-DR and reduced intracellular killing of Bacillus Calmette-Guérin. We provide a disease-modeling platform that might be suited to investigate novel treatment options for MSMD and to gain insights into IFNγ signaling in macrophages., (Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.)

Complicated/severe cases of placental pathology due to Plasmodium falciparum and P. vivax, especially adverse pregnancy outcomes during P. vivax infection, have been increasing in recent years. However, the pathogenesis of placental pathology during severe malaria is poorly understood, while responses against IFN-γ are thought to be associated with adverse pregnancy outcomes. In the present study, we explored the role of IFN-γ receptor 1 (IFNGR1) signaling in placental pathology during severe malaria using luciferase-expressing rodent malaria parasites, P. berghei NK65 (PbNK65L). We detected luciferase activities in the lung, spleen, adipose tissue, and placenta in pregnant mice, suggesting that infected erythrocytes could accumulate in various organs during infection. Importantly, we found that fetal mortality in IFNGR1-deficient mice infected with PbNK65L parasites was much less than in infected wild type (WT) mice. Placental pathology was also improved in IFNGR1-deficient mice. In contrast, bioluminescence imaging showed that parasite accumulation in the placentas of IFNGR1-deficient pregnant mice was comparable to that in WT mice infected with PbNK65L. These findings suggest that IFNGR1 signaling plays a pivotal role in placental pathology and subsequent adverse pregnancy outcomes during severe malaria. Our findings may increase our understanding of how disease aggravation occurs during malaria during pregnancy.

Infectious pathogens contribute to the development of autoimmune disorders, but the mechanisms connecting these processes are incompletely understood. Here we show that Plasmodium DNA induces autoreactive responses against erythrocytes by activating a population of B cells expressing CD11c and the transcription factor T-bet, which become major producers of autoantibodies that promote malarial anaemia. Additionally, we identify parasite DNA-sensing through Toll-like receptor 9 (TLR9) along with inflammatory cytokine receptor IFN-γ receptor (IFN-γR) as essential signals that synergize to promote the development and appearance of these autoreactive T-bet + B cells. The lack of any of these signals ameliorates malarial anaemia during infection in a mouse model. We also identify both expansion of T-bet + B cells and production of anti-erythrocyte antibodies in ex vivo cultures of naive human peripheral blood mononuclear cells (PBMC) exposed to P. falciprum infected erythrocyte lysates. We propose that synergistic TLR9/IFN-γR activation of T-bet + B cells is a mechanism underlying infection-induced autoimmune-like responses.

Experimental cerebral malaria (ECM) is a gamma interferon (IFN-γ)-dependent syndrome. However, whether IFN-γ promotes ECM through direct and synergistic targeting of multiple cell populations or by acting primarily on a specific responsive cell type is currently unknown. Here, using a panel of cell- and compartment-specific IFN-γ receptor 2 (IFN-γR2)-deficient mice, we show that IFN-γ causes ECM by signaling within both the hematopoietic and nonhematopoietic compartments. Mechanistically, hematopoietic and nonhematopoietic compartment-specific IFN-γR signaling exerts additive effects in orchestrating intracerebral inflammation, leading to the development of ECM. Surprisingly, mice with specific deletion of IFN-γR2 expression on myeloid cells, T cells, or neurons were completely susceptible to terminal ECM. Utilizing a reductionist in vitro system, we show that synergistic IFN-γ and tumor necrosis factor (TNF) stimulation promotes strong activation of brain blood vessel endothelial cells. Combined, our data show that within the hematopoietic compartment, IFN-γ causes ECM by acting redundantly or by targeting non-T cell or non-myeloid cell populations. Within the nonhematopoietic compartment, brain endothelial cells, but not neurons, may be the major target of IFN-γ leading to ECM development. Collectively, our data provide information on how IFN-γ mediates the development of cerebral pathology during malaria infection., (Copyright © 2017 Villegas-Mendez et al.)

The spleen is known as an important filter for blood-borne pathogens that are trapped by specialized macrophages in the marginal zone (MZ): the CD209 + MZ macrophages (MZMs) and the CD169 + marginal metallophilic macrophages (MMMs). Acute systemic infection strongly impacts MZ populations and the location of T and B lymphocytes. This phenomenon has been linked to reduced chemokine secretion by stromal cells. Brucella spp. are the causative agent of brucellosis, a widespread zoonotic disease. Here, we used Brucella melitensis infection as a model to investigate the impact of chronic stealth infection on splenic MZ macrophage populations. During the late phase of Brucella infection, we observed a loss of both MZMs and MMMs, with a durable disappearance of MZMs, leading to a reduction of the ability of the spleen to take up soluble antigens, beads, and unrelated bacteria. This effect appears to be selective as every other lymphoid and myeloid population analyzed increased during infection, which was also observed following Brucella abortus and Brucella suis infection. Comparison of wild-type and deficient mice suggested that MZ macrophage population loss is dependent on interferon gamma (IFN-γ) receptor but independent of T cells or tumor necrosis factor alpha receptor 1 (TNF-αR1) signaling pathways and is not correlated to an alteration of CCL19, CCL21, and CXCL13 chemokine mRNA expression. Our results suggest that MZ macrophage populations are particularly sensitive to persistent low-level IFN-γ-mediated inflammation and that Brucella infection could reduce the ability of the spleen to perform certain MZM- and MMM-dependent tasks, such as antigen delivery to lymphocytes and control of systemic infection., (Copyright © 2017 American Society for Microbiology.)

Type III interferons (IFN-λs) are the most recently found members of the IFN cytokine family and engage IFNLR1 and IL10R2 receptor subunits to activate innate responses against viruses. We have identified IFN-λs as critical instructors of antifungal neutrophil responses. Using Aspergillus fumigatus ( Af ) as a model to study antifungal immune responses, we found that depletion of CCR2 + monocytes compromised the ability of neutrophils to control invasive fungal growth. Using an unbiased approach, we identified type I and III IFNs as critical regulators of the interplay between monocytes and neutrophils responding to Af We found that CCR2 + monocytes are an important early source of type I IFNs that prime optimal expression of IFN-λ. Type III IFNs act directly on neutrophils to activate their antifungal response, and mice with neutrophil-specific deletion of IFNLR1 succumb to invasive aspergillosis. Dysfunctional neutrophil responses in CCR2-depleted mice were rescued by adoptive transfer of pulmonary CCR2 + monocytes or by exogenous administration of IFN-α and IFN-λ. Thus, CCR2 + monocytes promote optimal activation of antifungal neutrophils by initiating a coordinated IFN response. We have identified type III IFNs as critical regulators of neutrophil activation and type I IFNs as early stimulators of IFN-λ expression., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: Several mutations have been described leading to impaired immunity in the IL-12/IFN-γ axis and, they confer susceptibility to mycobacterial infections. One of the more serious clinical phenotypes is secondary to mutations at IFN-γ receptor 1 gene, characterized by an early onset and more severe disease., Clinical Report: We present a 3-month-old female patient with systemic M. tuberculosis complex who has a homozygous mutation, it affects the splicing site at IFNGR1 c.201-1G> T. At time of this report, she is with antimycobacterial treatment in the protocol of pluripotent hematopoietic cell transplantation (TCHP)., Conclusion: It has been reported that antiphimic treatment should be maintained until the immune system is restored by the TCHP. If patients receive THCP before the age of 1 year old, they have a better prognosis. Diminish the levels of IFN-γ in plasma before the procedure is associated to better results.

Yellow fever virus (YFV) is an arthropod-borne flavivirus, infecting ~200,000 people worldwide annually and causing about 30,000 deaths. The live attenuated vaccine strain, YFV-17D, has significantly contributed in controlling the global burden of yellow fever worldwide. However, the viral and host contributions to YFV-17D attenuation remain elusive. Type I interferon (IFN-α/β) signaling and type II interferon (IFN-γ) signaling have been shown to be mutually supportive in controlling YFV-17D infection despite distinct mechanisms of action in viral infection. However, it remains unclear how type III IFN (IFN-λ) integrates into this antiviral system. Here, we report that while wild-type (WT) and IFN-λ receptor knockout (λR -/- ) mice were largely resistant to YFV-17D, deficiency in type I IFN signaling resulted in robust infection. Although IFN-α/β receptor knockout (α/βR -/- ) mice survived the infection, mice with combined deficiencies in both type I signaling and type III IFN signaling were hypersusceptible to YFV-17D and succumbed to the infection. Mortality was associated with viral neuroinvasion and increased permeability of the blood-brain barrier (BBB). α/βR -/- λR -/- mice also exhibited distinct changes in the frequencies of multiple immune cell lineages, impaired T-cell activation, and severe perturbation of the proinflammatory cytokine balance. Taken together, our data highlight that type III IFN has critical immunomodulatory and neuroprotective functions that prevent viral neuroinvasion during active YFV-17D replication. Type III IFN thus likely represents a safeguard mechanism crucial for controlling YFV-17D infection and contributing to shaping vaccine immunogenicity. IMPORTANCE YFV-17D is a live attenuated flavivirus vaccine strain recognized as one of the most effective vaccines ever developed. However, the host and viral determinants governing YFV-17D attenuation and its potent immunogenicity are still unknown. Here, we analyzed the role of type III interferon (IFN)-mediated signaling, a host immune defense mechanism, in controlling YFV-17D infection and attenuation in different mouse models. We uncovered a critical role of type III IFN-mediated signaling in preserving the integrity of the blood-brain barrier and preventing viral brain invasion. Type III IFN also played a major role in regulating the induction of a potent but balanced immune response that prevented viral evasion of the host immune system. An improved understanding of the complex mechanisms regulating YFV-17D attenuation will provide insights into the key virus-host interactions that regulate host immune responses and infection outcomes as well as open novel avenues for the development of innovative vaccine strategies., (Copyright © 2017 Douam et al.)

Angiostasis mediated by interferon (IFN)-γ is a key mechanism of anti-tumour immunity; however, the effect of IFN-γ on host vascular endothelial growth factor A (VEGFA)-expressing cells during tumour progression is still elusive. Here, we developed transgenic mice with IFN-γ receptor (IFNγR) expression under control of the Vegfa promoter (V-γR). In these mice, the IFN-γ responsiveness of VEGFA-expressing cells led to dramatic growth suppression of transplanted lung carcinoma cells. Surprisingly, increased mortality and tumour metastasis were observed in the tumour-bearing V-γR mice, in comparison with the control wild-type and IFNγR-deficient mice. Further study showed that perivascular cells were VEGFA-expressing cells and potential IFN-γ targets. In vivo, tumour vascular perfusion and pericyte association with blood vessels were massively disrupted in V-γR mice. In vitro, IFN-γ inhibited transforming growth factor-β signalling by upregulating SMAD7, and therefore downregulated N-cadherin expression in pericytes. Importantly, IFN-γ neutralization in vivo with a monoclonal antibody reduced tumour metastasis. Together, the results suggest that IFNγR-mediated dissociation of perivascular cells from blood vessels contributes to the acceleration of tumour metastasis. Thus, the inhibition of tumour growth via IFN-γ-induced angiostasis might also accelerate tumour metastasis. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd., (Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Zika virus (ZIKV), a positive-sense RNA flavivirus, has attracted considerable attention recently for its potential to cause serious neurological problems, including microcephaly, cortical thinning, and blindness during early development. Recent findings suggest that ZIKV infection of the brain can occur not only during very early stages of development, but also in later fetal/early neonatal stages of maturation. Surprisingly, after peripheral inoculation of immunocompetent mice on the day of birth, the first cells targeted throughout the brain were isolated astrocytes. At later stages, more neurons showed ZIKV immunoreactivity, in part potentially due to ZIKV release from infected astrocytes. In all developing mice studied, we detected infection of retinal neurons; in many mice, this was also associated with infection of the lateral geniculate, suprachiasmatic nuclei, and superior colliculus, suggesting a commonality for the virus to infect cells of the visual system. Interestingly, in mature mice lacking a Type 1 interferon response (IFNR -/- ), after inoculation of the eye, the initial majority of infected cells in the visual system were glial cells along the optic tract. ZIKV microinjection into the somatosensory cortex on one side of the normal mouse brain resulted in mirror infection restricted to the contralateral somatosensory cortex without any infection of midline brain regions, indicating the virus can move by axonal transport to synaptically coupled brain loci. These data support the view that ZIKV shows considerable complexity in targeting the CNS and may target different cells at different stages of brain development. SIGNIFICANCE STATEMENT Zika virus (ZIKV) can cause substantial damage to the developing human brain. Here we examine a developmental mouse model of ZIKV infection in the newborn mouse in which the brain is developmentally similar to a second-trimester human fetus. After peripheral inoculation, the virus entered the CNS in all mice tested and initially targeted astrocytes throughout the brain. Infections of the retina were detected in all mice, and infection of CNS visual system nuclei in the brain was common. We find that ZIKV can be transported axonally, thereby enhancing virus spread within the brain. These data suggest that ZIKV infects multiple cell types within the brain and that astrocyte infection may play a more important role in initial infection than previously appreciated., (Copyright © 2017 the authors 0270-6474/17/372161-15$15.00/0.)

Type I interferons (IFNs, including IFN-αβ) contribute to the pathogenesis of Mycobacterium tuberculosis strains that induce high IFN-αβ levels. In the current study we examined the role of IFN-αβ during infection with a Mycobacterium africanum strain that induces low IFN-β levels. We infected wild-type and IFN-αβ receptor knockout mice with M. africanum and monitored bacterial growth, lung disease, and survival over 292 days. We found reduced lung bacterial burdens and less severe histopathological findings in the absence of IFN-αβ signaling. We conclude that IFN-αβ is pathogenic during chronic M. africanum infection and that the pathogenic effects may be mediated through poorer control of bacterial growth., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)