Biology subjects

Yount, J. S.

Publications and source records attributed to Yount, J. S..

At least 19 recordsLinked to original sources

bioRxiv2026

TFAM Dependent Mitochondrial Fitness Limits CD8⁺ T Cell Immunopathology and Sustains Protective Immunity during Viral Pneumonia

During respiratory virus infection, CD8 T cells kill infected cells and establish antigen-specific memory, but mechanisms regulating these functions remain incompletely understood. Here, we identify mitochondrial transcription factor A (TFAM)-dependent mitochondrial fitness as a regulator of CD8 T cell function during influenza infection. Human CD8 T cells exhibited an age-associated decline in TFAM expression and mitochondrial function. To model this physiologically relevant decline and determine its consequences for antiviral immunity, we generated CD8 T cell-specific TFAM-haploinsufficient mice. TFAM insufficiency disrupted mitochondrial integrity and bioenergetics and increased mitochondrial DNA and oxidative stress. During influenza infection, TFAM-insufficient CD8 T cells exhibited increased cytotoxic and inflammatory activity associated with lung immunopathology without improved viral control. This early phenotype was followed by loss of effector function, diminished antigen-specific responses, reduced protection following adoptive transfer, and impaired heterosubtypic recall immunity. Thus, TFAM-dependent mitochondrial fitness is a cell-intrinsic regulator that limits immunopathology while sustaining recall immunity.

immunology↗

bioRxiv2025

Cardioprotective effects of AMPK activation in H1N1 influenza virus infection

Cardiac complications are among the most common and severe extrapulmonary manifestations of influenza virus infection, yet they are rarely recapitulated in mouse models without immunodeficiency. We found that influenza virus A/California/04/2009 (H1N1) carrying a mouse-adaptive amino acid substitution in the PB2 protein (E158A) disseminates to the heart in WT C57BL/6 mice, where it induces inflammation, electrical dysfunction, and fibrotic remodeling. Influenza virus-infected heart tissue was significantly altered in mitochondrial metabolism, extracellular matrix, circadian rhythm, and immunity pathways. Particularly striking was activation of gene expression downstream of the mitochondrial biogenesis-promoting AMPK/PGC-1 axis, which occurred late in infection but failed to reverse the repression of mitochondria-associated genes, suggesting an insufficient or delayed compensatory response. Accordingly, we administered AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) early in infection and observed restoration of mitochondria-associated gene levels, amelioration of cardiac electrical dysfunction and fibrosis, and improvement in survival without overt effects on lung function. Overall, the advent of an immunocompetent model for severe influenza-associated cardiac dysfunction revealed activation of AMPK signaling as a host-targeted metabolic intervention for mitigating virus-induced heart pathologies

microbiology↗

bioRxiv2025

Accelerated Adaptation of SARS-CoV-2 Variants in Mice Lacking IFITM3 Preserves Distinct Tropism and Pathogenesis

Here we investigated whether interferon induced transmembrane protein 3 (IFITM3), a key antiviral protein deficient in certain human populations, affects interspecies adaptation of SARS-CoV-2. We found that SARS-CoV-2 Beta and Omicron variants passaged through IFITM3-deficient versus wild type mice exhibit enhanced replication and pathogenesis in this new host species. Enhancements associated with amino acid substitutions in the viral genome, suggesting that IFITM3 limits accumulation of adaptive mutations. Mouse-adapted viruses enabled comparative studies of variants in mice. Beta caused lung dysfunction and altered cilia-associated gene programs, consistent with broad viral antigen distribution in lungs. Omicron, which shows low pathogenicity and upper respiratory tract preference in humans, replicated to high nasal titers while showing restrained spatial distribution in lungs and diminished lung inflammatory responses compared to Beta. Our findings demonstrate that IFITM3 deficiency accelerates coronavirus adaptation and reveal that intrinsic SARS-CoV-2 variant traits shape tropism, immunity, and pathogenesis across hosts. HIGHLIGHTSO_LIIFITM3 is a critical barrier to SARS-CoV-2 adaptation in new host species C_LIO_LIMouse-adapted SARS-CoV-2 strains enable comparative pathology C_LIO_LIOmicron favors nose and large airways, leading to mild lung pathology C_LIO_LIBeta exhibits broad lung replication, driving severe inflammation and dysfunction C_LI

immunology↗

bioRxiv2024

ERK5 Signaling is Required for Type III IFN-mediated Mucosal Antiviral Responses

Type III interferons (IFN{lambda}) are innate immune cytokines that limit viral replication and coordinate tissue repair through the induction of interferon stimulated genes (ISGs). This response must be tightly regulated to avoid excessive responses that result in the disruption of tissue barrier integrity or inefficient responses that allow for pathogen escape. Here we examine the contribution of Mitogen Activated Protein Kinase (MAPK) signaling on IFN{lambda}-mediated antiviral activity. We find that extracellular-signal-regulated kinase 5 (ERK5), a poorly characterized member of the conventional MAPK family, potentiates the antiviral efficacy of IFN{lambda}. Chemical inhibition and genetic targeting of ERK5 during IFN{lambda} treatment of cells results in a decrease in ISG induction and impaired control of viral infections. This decrease in IFN{lambda} antiviral efficacy in the absence of ERK5 kinase activity corresponded to lowered STAT1 phosphorylation, revealing a noncanonical role for ERK5 in STAT1 activation downstream of IFN{lambda}. In contrast, type I IFN antiviral signaling is largely resistant to ERK5 modulation. Altogether, we identify ERK5 as a potentiator of STAT1 activation, ISG expression, and antiviral activity following type III IFN stimulation. SIGNIFICANCERegulation of type III interferons (IFN{lambda}) at mucosal barriers in response infection to mitigate viral replication and support barrier integrity. The specific mechanistic requirements for MAPK signaling to sustain IFN{lambda}-mediated gene expression have remained elusive. Amongt the least characterized members of the MAPK family, the role of ERK5 in regulating host inflammatory responses has been hampered by off-target effects of kinase inhibitors. Here, we combine pharmacological and genetic approaches to specifically demonstrate that ERK5 promotes antiviral immunity in epithelial cells. Mechanistically, ERK5 enhances the activation of STAT1 in response to IFN stimulation to augment the transcription of IFN-stimulated genes. Our work demonstrates that therapeutic modulation of MAPK and IFN signaling pathway co-integration could distinguish between the protective and deleterious outcomes of IFN expression. One-sentence summaryERK5 potentiates IFN lambda responses.

immunology↗

bioRxiv2023

Innate immune control of influenza virus interspecies adaptation

Influenza virus pandemics are caused by viruses from animal reservoirs that adapt to efficiently infect and replicate in human hosts. Here, we investigated whether Interferon-Induced Transmembrane Protein 3 (IFITM3), a host antiviral factor with known human deficiencies, plays a role in interspecies virus infection and adaptation. We found that IFITM3-deficient mice and human cells could be infected with low doses of avian influenza viruses that failed to infect WT counterparts, identifying a new role for IFITM3 in controlling the minimum infectious viral dose threshold. Remarkably, influenza viruses passaged through Ifitm3-/- mice exhibited enhanced host adaptation, a result that was distinct from passaging in mice deficient for interferon signaling, which caused virus attenuation. Our data demonstrate that IFITM3 deficiency uniquely facilitates zoonotic influenza virus infections and subsequent adaptation, implicating IFITM3 deficiencies in the human population as a vulnerability for emergence of new pandemic viruses.

microbiology↗

bioRxiv2023

A role for Toll-like receptor 3 in lung vascular remodeling associated with SARS-CoV-2 infection

Cardiovascular sequelae of severe acute respiratory syndrome (SARS) coronavirus-2 (CoV-2) disease 2019 (COVID-19) contribute to the complications of the disease. One potential complication is lung vascular remodeling, but the exact cause is still unknown. We hypothesized that endothelial TLR3 insufficiency contributes to lung vascular remodeling induced by SARS-CoV-2. In the lungs of COVID-19 patients and SARS-CoV-2 infected Syrian hamsters, we discovered thickening of the pulmonary artery media and microvascular rarefaction, which were associated with decreased TLR3 expression in lung tissue and pulmonary artery endothelial cells (ECs). In vitro, SARS-CoV-2 infection reduced endothelial TLR3 expression. Following infection with mouse-adapted (MA) SARS-CoV-2, TLR3 knockout mice displayed heightened pulmonary artery remodeling and endothelial apoptosis. Treatment with the TLR3 agonist polyinosinic:polycytidylic acid reduced lung tissue damage, lung vascular remodeling, and endothelial apoptosis associated with MA SARS-CoV-2 infection. In conclusion, repression of endothelial TLR3 is a potential mechanism of SARS-CoV-2 infection associated lung vascular remodeling and enhancing TLR3 signaling is a potential strategy for treatment.

molecular biology↗

bioRxiv2022

Aiolos modulates the TFH and CD4-CTL differentiation programs via reciprocal regulation of the Zfp831/TCF-1/Bcl-6 axis and CD25

Effective immunity to influenza virus and other respiratory viruses requires the generation of CD4+ T cell subsets that coordinate multiple aspects of the immune response. These subsets include T follicular helper (TFH) and T helper 1 (TH1) cells, which promote humoral and cell-mediated responses, respectively. A third population, CD4+ cytotoxic T lymphocytes (CD4-CTLs) facilitates clearance of infection via mechanisms normally associated with CD8+ T cells. Here, we identify the transcription factor Aiolos as a regulator of TFH and CD4-CTL responses. We demonstrate that Aiolos deficiency compromises TFH differentiation and antibody production during influenza virus infection. Conversely, we find that CD4+ T cells acquire a cytotoxic-like program in the absence of Aiolos, including increased expression of the CTL-associated transcription factors Eomes and Blimp-1. We further show that while Aiolos positively regulates the TFH transcriptional regulators Zfp831, TCF-1 and Bcl-6, it also directly represses expression of IL-2R and IL-2/STAT5-driven expression of the cytotoxic gene program. Thus, our findings identify Aiolos as a pivotal regulator of TFH and CD4-CTL differentiation and highlight its potential as a target for manipulating CD4+ T cell humoral and cytotoxic responses.

immunology↗

bioRxiv2022

Prime-pull immunization of mice with a BcfA-adjuvanted vaccine elicits mucosal immunity and prevents SARS CoV-2 infection and pathology

Vaccines against SARS-CoV-2 that induce mucosal immunity capable of preventing infection and disease remain urgently needed. We show that intramuscular priming of mice with an alum and BcfA-adjuvanted Spike subunit vaccine, followed by a BcfA-adjuvanted mucosal booster, generated Th17 polarized tissue resident CD4+ T cells, and mucosal and serum antibodies. The serum antibodies efficiently neutralized SARS-CoV-2 and its Delta variant, suggesting cross-protection against a recent variant of concern (VOC). Immunization with this heterologous vaccine prevented weight loss following challenge with mouse-adapted SARS-CoV-2 and reduced viral replication in the nose and lungs. Histopathology showed a strong leukocyte and polymorphonuclear (PMN) cell infiltrate without epithelial damage in mice immunized with BcfA-containing vaccines. In contrast, viral load was not reduced in the upper respiratory tract of IL-17 knockout mice immunized with the same formulation, suggesting that the Th17 polarized T cell responses are critical for protection. We show that vaccines adjuvanted with alum and BcfA, delivered through a heterologous prime-pull regimen, protect against SARS-CoV-2 infection without causing enhanced respiratory disease. SIGNIFICANCEThere remains a need for SARS CoV-2 booster vaccines that generate mucosal immunity and prevent transmission. We show that systemic priming followed by a mucosal booster with a BcfA-adjuvanted subunit vaccine generates neutralizing antibodies and Th17 polarized systemic and tissue-resident immune responses that provide sterilizing immunity against wildtype SARS CoV-2, and a variant of concern. Importantly, in contrast to alum alone, the addition of BcfA prevents respiratory pathology. These results suggest that a BcfA-adjuvanted mucosal booster may elicit mucosal immunity in individuals previously immunized systemically with approved vaccines. This foundational study in mice sets the stage for testing our vaccine regimen in larger animal models as a booster vaccine.

immunology↗

bioRxiv2021

Interferon-induced transmembrane protein 3 (IFITM3) limits lethality of SARS-CoV-2 in mice

Interferon-induced transmembrane protein 3 (IFITM3) is a host antiviral protein that alters cell membranes to block fusion of viruses. Published reports have identified conflicting pro- and antiviral effects of IFITM3 on SARS-CoV-2 in cultured cells, and its impact on viral pathogenesis in vivo remains unclear. Here, we show that IFITM3 knockout (KO) mice infected with mouse-adapted SARS-CoV-2 experienced extreme weight loss and lethality, while wild type (WT) mice lost minimal weight and recovered. KO mice had higher lung viral titers and increases in lung inflammatory cytokine levels, CD45-positive immune cell infiltration, and histopathology, compared to WT mice. Mechanistically, we observed disseminated viral antigen staining throughout the lung tissue and pulmonary vasculature in KO mice, while staining was observed in confined regions in WT lungs. Global transcriptomic analysis of infected lungs identified upregulation of gene signatures associated with interferons, inflammation, and angiogenesis in KO versus WT animals, highlighting changes in lung gene expression programs that precede severe lung pathology and fatality. Corroborating the protective effect of IFITM3 in vivo, K18-hACE2/IFITM3 KO mice infected with non-adapted SARS-CoV-2 showed enhanced, rapid weight loss and early death compared to control mice. Increased heart infection was observed in both mouse models in the absence of IFITM3, indicating that IFITM3 constrains extrapulmonary dissemination of SARS-CoV-2. Our results establish IFITM3 KO mice as a new animal model for studying severe SARS-CoV-2 infection of the lung and cardiovascular system, and overall demonstrate that IFITM3 is protective in SARS-CoV-2 infections of mice.

immunology↗

bioRxiv2021

Influenza virus replication in cardiomyocytes drives heart dysfunction and fibrosis

Cardiac dysfunction is a common extrapulmonary complication of severe influenza virus infection. Prevailing models propose that influenza-associated heart dysfunction is indirectly triggered by cytokine mediated cardiotoxicity downstream of the inflamed lung, rather than by direct infection of cardiac tissue. To test the etiology of cardiac dysfunction resulting from influenza virus infection, we generated a novel recombinant H1N1 influenza A virus that was attenuated in cardiomyocytes by incorporation of target sequences for miRNAs expressed specifically in that cell type (miR133b and miR206). Compared with control virus, mice infected with the miR-targeted virus had significantly reduced heart viral titers, confirming cardiac attenuation of viral replication. The miR-targeted virus, however, was fully replicative and inflammatory in lungs when compared to control virus, and induced similar systemic weight loss. The miR-targeted virus induced considerably lower levels of cardiac arrhythmia, fibrosis, and inflammation, compared with control virus, in mice lacking interferon induced transmembrane protein 3 (IFITM3), which serve as the only available model for severe influenza-associated cardiac pathology. We conclude that robust replication of virus in the heart is required for pathology even when lung inflammation is severe. Indeed, we show that human stem cell-derived cardiomyocytes are susceptible to influenza virus infection. This work establishes a fundamental new paradigm in which influenza virus damages the heart through direct infection of cardiomyocytes.

immunology↗

bioRxiv2021

Overexpression of the SETD2 WW domain inhibits the phosphor-IWS1/SETD2 interaction and the oncogenic AKT/IWS1 RNA splicing program.

The authors have withdrawn their manuscript. While attempting to reproduce the data on the alternative splicing of exon 2 of U2AF2, they observed that the proposed splicing mechanism could not give rise to a functional U2AF2 protein. In addition, they observed evidence of manipulation in the electropherogram of the splicing junction between exons 1 and 3 and in the primary data on which this electropherogram was based, which were deposited in Mendeley by the first author. These observations raise questions on the integrity of the reported results. In light of this information, the authors have no confidence in the key findings of the paper, and therefore, do not wish it to be cited. If you have any questions, please contact the corresponding author.

cancer biology↗

bioRxiv2021

SARS-CoV-2 inactivation by human defensin HNP1 and retrocyclin RC-101

Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 is an enveloped virus responsible for the COVID-19 respiratory disease pandemic. While induction of adaptive antiviral immunity via vaccination holds promise for combatting the pandemic, the emergence of new potentially more transmissible and vaccine-resistant variants of SARS-CoV-2 is an ever-present threat. Thus, it remains essential to better understand innate immune mechanisms that are active against the virus. One component of the innate immune system with broad anti-pathogen, including antiviral, activity is a group of cationic immune peptides termed defensins. The defensins ability to neutralize enveloped and non-enveloped viruses and to inactivate numerous bacterial toxins correlate with their ability to promote the unfolding of thermodynamically pliable proteins. Accordingly, we found that human neutrophil a-defensin HNP1 and retrocyclin RC-101 destabilize SARS-CoV-2 Spike protein and interfere with Spike-mediated membrane fusion and SARS-CoV-2 infection in cell culture. We show that HNP1 binds to Spike with submicromolar affinity. Although binding of HNP1 to serum albumin is more than 20-fold weaker, serum reduces the anti-SARS-CoV-2 activity of HNP1. At high concentrations of HNP1, its ability to inactivate the virus was preserved even in the presence of serum. These results suggest that specific a- and 8-defensins may be valuable tools in developing SARS-CoV-2 infection prevention strategies.

immunology↗

bioRxiv2021

SARS-CoV-2 Nsp14 activates NF-κB signaling and induces IL-8 upregulation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to NF-{kappa}B activation and induction of pro-inflammatory cytokines, though the underlying mechanism for this activation is not fully understood. Our results reveal that the SARS-CoV-2 Nsp14 protein contributes to the viral activation of NF-{kappa}B signaling. Nsp14 caused the nuclear translocation of NF-{kappa}B p65. Nsp14 induced the upregulation of IL-6 and IL-8, which also occurred in SARS-CoV-2 infected cells. IL-8 upregulation was further confirmed in lung tissue samples from COVID-19 patients. A previous proteomic screen identified the putative interaction of Nsp14 with host Inosine-5-monophosphate dehydrogenase 2 (IMPDH2) protein, which is known to regulate NF-{kappa}B signaling. We confirmed the Nsp14-IMPDH2 protein interaction and found that IMPDH2 knockdown or chemical inhibition using ribavirin (RIB) and mycophenolic acid (MPA) abolishes Nsp14-mediated NF-{kappa}B activation and cytokine induction. Furthermore, IMDPH2 inhibitors (RIB, MPA) efficiently blocked SARS-CoV-2 infection, indicating that IMDPH2, and possibly NF-{kappa}B signaling, is beneficial to viral replication. Overall, our results identify a novel role of SARS-CoV-2 Nsp14 in causing the activation of NF-{kappa}B.

microbiology↗

bioRxiv2021

A bioorthogonal chemical reporter for fatty acid synthase-dependent protein acylation

Cells acquire fatty acids from dietary sources or via de novo palmitate production by fatty acid synthase (FASN). Although most cells express FASN at low levels, it is upregulated in cancers and during replication of many viruses. The precise role of FASN in disease pathogenesis is poorly understood, and whether de novo fatty acid synthesis contributes to host or viral protein acylation has been traditionally difficult to study. We describe a cell permeable, click-chemistry compatible alkynyl-acetate analog (Alk-4) that functions as a reporter of FASN-dependent protein acylation. In a FASN-dependent manner, Alk-4 selectively labeled the cellular protein interferon-induced transmembrane protein 3 (IFITM3) at its palmitoylation sites, and the HIV-1 matrix protein at its myristoylation site. Alk-4 metabolic labeling also enabled biotin-based purification and identification of more than 200 FASN-dependent acylated cellular proteins. Thus, Alk-4 is a useful bioorthogonal tool to selectively probe FASN-mediated protein acylation in normal and diseased states.

microbiology↗

bioRxiv2021

Moderately pathogenic maternal influenza A virus infection disrupts placental integrity but spares the fetal brain

Maternal infection during pregnancy is a known risk factor for offspring mental health disorders. Animal models of maternal immune activation (MIA) have implicated specific cellular and molecular etiologies of psychiatric illness, but most rely on pathogen mimetics. Here, we developed a mouse model of live H3N2 influenza A virus (IAV) infection during pregnancy that induces a robust inflammatory response but is sublethal to both dams and offspring. We observed lung inflammatory cytokine production and severely diminished weight gain in IAV-infected dams. This was accompanied by immune cell infiltration in the placenta and partial breakdown of placental integrity. However, indications of IL-17A signaling and fetal neuroinflammation, which are hallmarks of mimetic-induced MIA, were not detected. Our results suggest that mild or moderately pathogenic IAV infection during pregnancy does not inflame the developing fetal brain, and highlight the importance of live pathogen infection models for the study of MIA. HighlightsO_LIA mouse model of influenza A virus (IAV) infection during pregnancy was established C_LIO_LIModerate IAV infection induced lung inflammation and blunted weight gain in dams C_LIO_LIMaternal IAV infection caused mild pathology in the placenta without pup loss C_LIO_LIModerate gestational IAV infection did not induce fetal brain inflammation C_LIO_LIAn IAV infection severity threshold may exist for inducing fetal neuroinflammation C_LI

immunology↗

bioRxiv2020

IWS1 phosphorylation by AKT kinase controls the nucleocytoplasmic export of type I IFNs and the sensitivity of lung adenocarcinoma cells to oncolytic viral infection, through U2AF2 RNA splicing.

cancer biology↗

bioRxiv2020

Opposing activities of IFITM proteins in SARS-CoV-2 infection

Interferon-induced transmembrane proteins (IFITMs) restrict infections by many viruses, but a subset of IFITMs enhance infections by specific coronaviruses through currently unknown mechanisms. Here we show that SARS-CoV-2 Spike-pseudotyped virus and genuine SARS-CoV-2 infections are generally restricted by expression of human IFITM1, IFITM2, and IFITM3, using both gain- and loss-of-function approaches. Mechanistically, restriction of SARS-CoV-2 occurred independently of IFITM3 S-palmitoylation sites, indicating a restrictive capacity that is distinct from reported inhibition of other viruses. In contrast, the IFITM3 amphipathic helix and its amphipathic properties were required for virus restriction. Mutation of residues within the human IFITM3 endocytosis-promoting Yxx{Phi} motif converted human IFITM3 into an enhancer of SARS-CoV-2 infection, and cell-to-cell fusion assays confirmed the ability of endocytic mutants to enhance Spike-mediated fusion with the plasma membrane. Overexpression of TMPRSS2, which reportedly increases plasma membrane fusion versus endosome fusion of SARS-CoV-2, attenuated IFITM3 restriction and converted amphipathic helix mutants into strong enhancers of infection. In sum, these data uncover new pro- and anti-viral mechanisms of IFITM3, with clear distinctions drawn between enhancement of viral infection at the plasma membrane and amphipathicity-based mechanisms used for endosomal virus restriction. Indeed, the net effect of IFITM3 on SARS-CoV-2 infections may be a result of these opposing activities, suggesting that shifts in the balance of these activities could be coopted by viruses to escape this important first line innate defense mechanism.

immunology↗

bioRxiv2019

IFITMs Inhibit Cell Fusion Mediated by Trophoblast Syncytins

Type I interferon (IFN) induced by virus infections during pregnancy causes placental damage, though the mechanisms and identities of IFN-stimulated genes that are involved remain under investigation. The IFN-induced transmembrane proteins (IFITMs) inhibit virus infections by preventing virus membrane fusion with cells and by inhibiting fusion of infected cells (syncytialization). Fusion of placental trophoblasts via expression of endogenous retroviral fusogens known as Syncytins forms the syncytiotrophoblast, a multinucleated cell structure essential for fetal development. We found that IFN blocks fusion of BeWo human placental trophoblasts. Stably-expressed IFITMs 1, 2, and 3 also blocked fusion of these trophoblasts, while making them more resistant to virus infections. Conversely, stable knockdown of IFITMs in BeWo trophoblasts increased their spontaneous fusion and allowed fusion in the presence of IFN, while also making the cells more susceptible to virus infection. Overall, our data demonstrate that IFITMs are anti-viral and anti-fusogenic in trophoblasts.

immunology↗