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Biology subjects

Vogel, P.

Publications and source records attributed to Vogel, P..

15 recordsLinked to original sources

Inhibition of the EBF1-ITGB8 Axis in Bone Marrow Niche Ameliorates Hallmarks of Myelofibrosis

Fibrotic remodeling of the bone marrow (BM) niche is a characteristic feature of myelofibrosis (MF) that contributes to disease progression. In MF, mesenchymal stromal cells (MSCs) produce excessive amounts of inflammatory cytokines and extracellular matrix, leading to BM fibrosis, impaired blood production, extramedullary hematopoiesis, and progressive BM failure. While the genetic events that initiate MF in hematopoietic cells are well defined, our understanding of the mechanisms responsible for BM fibrosis remains incomplete. Here, we show that transcription factor EBF1 is a key regulator of the fibrotic gene program in mouse and human MSCs. EBF1 is upregulated in pre-fibrotic MSCs, while mice with MSC-specific deletion of Ebf1 exhibit reduced BM fibrosis, decreased expansion of myeloid cells and splenomegaly when transplanted with hematopoietic progenitors harboring the MF driver mutation MPLW515L. Moreover, we identify ITGB8 as an EBF1-regulated gene with therapeutic potential. MF mice treated with ITGB8-neutralizing antibodies or with MSC-specific Itgb8 deletion show reduced disease burden, as indicated by decreased marrow fibrosis, significantly reduced frequencies of MPL mutant cells, and reduced inflammation in the BM. Our data indicate that targeting the EBF1-ITGB8 axis in the MF MSCs may have therapeutic benefits.

cell biology↗

Mitochondrial Integrated Stress Response Activation Creates a Therapeutic Vulnerability to MCL-1 Inhibition in Acute Myeloid Leukemia

MCL-1 (myeloid cell leukemia-1) promotes survival and confers therapeutic resistance in acute myeloid leukemia (AML), particularly in high-risk subtypes harboring KMT2A rearrangements (KMT2A-r). Clinical trials of patients with hematological malignancies treated with MCL-1 inhibitor monotherapy have revealed dose-limiting toxicity and poor response rates. Therefore, we sought to identify combinatorial treatment approaches to enhance the efficacy of MCL-1 inhibitors with the goal of improving response rates and limiting toxicities. Here, we report the inhibition of electron transport chain (ETC) complex I (CI) function as a synthetic lethal partner for MCL-1 inhibition. Co-targeting CI and MCL-1 synergistically reduces the viability in AML cell lines and patient-derived xenograft (PDX) samples in vitro, while significantly prolonging survival in mice bearing PDX AML, indicating the preclinical potential for combinatorial therapy. These findings provide a mechanistic rationale and preclinical evidence for dual inhibition of MCL-1 and CI as a therapeutic strategy, offering a potential path to overcome resistance to single-agent MCL-1 inhibitors and improve outcomes for patients with high-risk AML. Mechanistically, we reveal that CI inhibition induces the activation of the integrated stress response (ISR), resulting in ATF4 activation downstream of the eIF2 kinase, HRI. The activation of HRI by CI inhibition is dependent on the mitochondrial stress messenger, DELE1. Together, these results indicate that co-inhibition of MCL-1 and ETC CI function has the potential for improving responses in patients with KMT2A-r AML.

cancer biology↗

The critical role of the ZBP1-NINJ1 axis and IRF1/IRF9 in ethanol-induced cell death, PANoptosis, and alcohol-associated liver disease

Innate immunity provides the critical first line of defense against infection and sterile triggers. Cell death is a key component of the innate immune response to clear pathogens, but excessive or aberrant cell death can induce inflammation, cytokine storm, and pathology, making it a central molecular mechanism in inflammatory diseases. Alcohol-associated liver disease (ALD) is one such inflammatory disease, but the specific innate immune mechanisms driving pathology in this context remain unclear. Here, by leveraging RNAseq and tissue expression in clinical samples, we identified increased expression of the innate immune sensor Z-DNA binding protein (ZBP1) in patients with ALD. We discovered that ZBP1 expression correlated with ALD progression in patients, and that ethanol induced ZBP1-dependent lytic cell death, PANoptosis, in immune (macrophages, monocytes, Kupffer cells) and non-immune cells (hepatocytes). Mechanistically, the interferon regulatory factors (IRFs) IRF9 and IRF1 upregulated ZBP1 expression, allowing ZBP1 to sense Z-NAs through its Z2 domain and drive PANoptosis signaling, cell membrane rupture through NINJ1, and DAMP release. Furthermore, the expressions of ZBP1 and NINJ1 were upregulated in both liver and serum samples from patients with ALD. In mouse models of chronic and acute ALD, ZBP1-deficient mice were significantly protected from disease pathology and liver damage. Overall, our findings establish the critical role of the ZBP1-NINJ1 axis regulated by IRFs in driving inflammatory cell death, PANoptosis, in liver cells, suggesting that targeting these molecules will have therapeutic potential in ALD and other inflammatory conditions.

immunology↗

Somatic mtDNA Mutation Burden Shapes Metabolic Plasticity in Leukemogenesis

The role of somatic mitochondrial DNA (mtDNA) mutations in leukemogenesis remains poorly characterized. To determine the impact of somatic mtDNA mutations on the process, we assessed the leukemogenic potential of hematopoietic progenitor cells (HPCs) from mtDNA mutator mice (Polg D257A) with or without NMyc overexpression. We observed a higher incidence of spontaneous leukemogenesis in recipients transplanted with heterozygous Polg HPCs and a lower incidence of NMyc-driven leukemia in those with homozygous Polg HPCs compared to controls. Although mtDNA mutations in heterozygous and homozygous HPCs caused similar baseline impairments in mitochondrial function, only heterozygous HPCs responded to and supported altered metabolic demands associated with NMyc overexpression. Homozygous HPCs showed altered glucose utilization with pyruvate dehydrogenase inhibition due to increased phosphorylation, exacerbated by NMyc overexpression. The impaired growth of NMyc-expressing homozygous HPCs was partially rescued by inhibiting pyruvate dehydrogenase kinase, highlighting a relationship between mtDNA mutation burden and metabolic plasticity in leukemogenesis. TEASERSomatic mtDNA mutations as drivers of metabolic change in the development of leukemia.

cancer biology↗

Ixodes ricinus bites promote allergic skin inflammation and intestinal tuft and mast cell expansion in mice.

BackgroundTick bites often promote local allergic reactions in the skin and predispose to red meat allergy. The mechanisms involved in these processes are not fully understood. Here we investigated the local changes to the skin and intestine induced by tick bites. MethodsC3H/HEN or Balb/c mice were subjected to either tick bites by Ixodes ricinus (I. ricinus) or mechanical skin injury. Skin or intestine was analyzed a different time point by transcriptomic and histological techniques. ResultsOur results indicate that I. ricinus bites promote epidermal hyperplasia, spongiosis and an accumulation of eosinophils and mast cells in the bitten skin. In addition, I. ricinus bites promote the expression of genes and activate pathways also induced by mechanical skin injury elicited by tape stripping. Remarkably, similar to tape stripping, I. ricinus bites promote an increase in total serum IgE, and intestinal tuft cell and mast cell expansion. ConclusionI. ricinus bites in mice promote cutaneous inflammation that resembles allergic skin inflammation, as well as intestinal changes that could play a role in the predisposition to red meat allergy.

immunology↗

Inducible genetic ablation of Immt induces a lethal disruption of the MICOS complex

The mitochondrial contact site and cristae organizing system (MICOS) is important for cristae junctions (CJ) formation and for maintaining inner mitochondrial membrane (IMM) architecture. As the largest member, MIC60 is the primary scaffold protein for this complex. While MIC60 has been well studied in yeast and cell culture models, its function in mammals is poorly understood. To address this, we developed a mouse model conditionally deleting Immt (which encodes MIC60) and found that global Immt deletion disrupted the MICOS complex and resulted in lethality within 9 days of tamoxifen treatment. Pathologically, these mice display intestinal defects consistent with paralytic ileus, resulting in dehydration. We also identified bone marrow hypocellularity in tamoxifen-treated mice. However, bone marrow transplants from ImmtWT mice failed to rescue survival. Altogether, this novel mouse model demonstrates the importance of MIC60 in vivo, in both hematopoietic and non-hematopoietic tissues, and provides a valuable resource for future mechanistic investigations into the MICOS complex. Such investigations could include an in vivo structure-function analysis of MIC60 functional domains, with characterizations that are relevant to human diseases.

physiology↗

PARP1 Inhibition Halts EBV+ Lymphoma Progression by Disrupting the EBNA2/MYC Axis

PARP1 has been shown to regulate EBV latency. However, the therapeutic effect of PARP1 inhibitors on EBV+ lymphomagenesis has not yet been explored. Here, we show that PARPi BMN-673 has a potent anti-tumor effect on EBV-driven LCL in a mouse xenograft model. We found that PARP1 inhibition induces a dramatic transcriptional reprogramming of LCLs driven largely by the reduction of the MYC oncogene expression and dysregulation of MYC targets, both in vivo and in vitro. PARP1 inhibition also reduced the expression of viral oncoprotein EBNA2, which we previously demonstrated depends on PARP1 for activation of MYC. Further, we show that PARP1 inhibition blocks the chromatin association of MYC, EBNA2, and tumor suppressor p53. Overall, our study strengthens the central role of PARP1 in EBV malignant transformation and identifies the EBNA2/MYC pathway as a target of PARP1 inhibitors and its utility for the treatment of EBNA2-driven EBV-associated cancers. Significance StatementA promising approach to treating EBV-driven malignancies involves targeting cancer and EBV biology. However, investigating host factors that co-regulate EBV latent gene expression, such as PARP1, has been incomplete. Our study demonstrates that the PARP1 inhibitor BMN-673 effectively reduces EBV-driven tumors and metastasis in an LCL xenograft model. Additionally, we have identified potential dysregulated mechanisms associated with PARP1 inhibition. These findings strengthen the role of PARP1 in EBV+ lymphomas and establish a link between PARP1 and the EBNA2/MYC axis. This has important implications for developing therapeutic approaches to various EBV-associated malignancies.

cancer biology↗

Time-Dependent Increase in Susceptibility and Severity of Secondary Bacterial Infection during SARS-CoV-2 Infection

Secondary bacterial infections can exacerbate SARS-CoV-2 infection, but their prevalence and impact remain poorly understood. Here, we established that a mild to moderate SARS-CoV-2 infection increased the risk of pneumococcal coinfection in a time-dependent, but sexindependent, manner in the transgenic K18-hACE mouse model of COVID-19. Bacterial coinfection was not established at 3 d post-virus, but increased lethality was observed when the bacteria was initiated at 5 or 7 d post-virus infection (pvi). Bacterial outgrowth was accompanied by neutrophilia in the groups coinfected at 7 d pvi and reductions in B cells, T cells, IL-6, IL-15, IL-18, and LIF were present in groups coinfected at 5 d pvi. However, viral burden, lung pathology, cytokines, chemokines, and immune cell activation were largely unchanged after bacterial coinfection. Examining surviving animals more than a week after infection resolution suggested that immune cell activation remained high and was exacerbated in the lungs of coinfected animals compared with SARS-CoV-2 infection alone. These data suggest that SARS-CoV-2 increases susceptibility and pathogenicity to bacterial coinfection, and further studies are needed to understand and combat disease associated with bacterial pneumonia in COVID-19 patients.

microbiology↗

COVID-19 cytokines and the hyperactive immune response: Synergism of TNF-α and IFN-γ in triggering inflammation, tissue damage, and death

The COVID-19 pandemic has caused significant morbidity and mortality. Currently, there is a critical shortage of proven treatment options and an urgent need to understand the pathogenesis of multi-organ failure and lung damage. Cytokine storm is associated with severe inflammation and organ damage during COVID-19. However, a detailed molecular pathway defining this cytokine storm is lacking, and gaining mechanistic understanding of how SARS-CoV-2 elicits a hyperactive inflammatory response is critical to develop effective therapeutics. Of the multiple inflammatory cytokines produced by innate immune cells during SARS-CoV-2 infection, we found that the combined production of TNF- and IFN-{gamma} specifically induced inflammatory cell death, PANoptosis, characterized by gasdermin-mediated pyroptosis, caspase-8-mediated apoptosis, and MLKL-mediated necroptosis. Deletion of pyroptosis, apoptosis, or necroptosis mediators individually was not sufficient to protect against cell death. However, cells deficient in both RIPK3 and caspase-8 or RIPK3 and FADD were resistant to this cell death. Mechanistically, the JAK/STAT1/IRF1 axis activated by TNF- and IFN-{gamma} co-treatment induced iNOS for the production of nitric oxide. Pharmacological and genetic deletion of this pathway inhibited pyroptosis, apoptosis, and necroptosis in macrophages. Moreover, inhibition of PANoptosis protected mice from TNF- and IFN-{gamma}-induced lethal cytokine shock that mirrors the pathological symptoms of COVID-19. In vivo neutralization of both TNF- and IFN-{gamma} in multiple disease models associated with cytokine storm showed that this treatment provided substantial protection against not only SARS-CoV-2 infection, but also sepsis, hemophagocytic lymphohistiocytosis, and cytokine shock models, demonstrating the broad physiological relevance of this mechanism. Collectively, our findings suggest that blocking the cytokine-mediated inflammatory cell death signaling pathway identified here may benefit patients with COVID-19 or other cytokine storm-driven syndromes by limiting inflammation and tissue damage. The findings also provide a molecular and mechanistic description for the term cytokine storm. Additionally, these results open new avenues for the treatment of other infectious and autoinflammatory diseases and cancers where TNF- and IFN-{gamma} synergism play key pathological roles.

immunology↗

Requirement for Anti-Apoptotic MCL-1 during Early Erythropoiesis

Mature erythrocytes are under tight homeostatic control with the need for constant replacement from progenitors to replace damaged or obsolete red blood cells (RBCs). This process is regulated largely by erythropoietin (Epo) which promotes the survival of erythroid progenitors and facilitates their differentiation and proliferation. Ablation of Bcl2l1 (which encodes BCL-xL) results in embryonic lethality with a lack of mature erythrocytes but does not perturb erythroid progenitors. Similarly, conditional Bcl2l1-deletion results in severe anemia with the death of late erythroid progenitors and induction of extramedullary erythropoiesis. While BCL-xL is critical to the survival of mature erythrocytes, it is still unclear whether other anti-apoptotic molecules mediate survival during earlier stages of erythropoiesis. Here, we demonstrate that erythroid-specific Mcl1-deletion results in embryonic lethality due to severe anemia caused by a lack of mature RBCs. Mcl1-deleted embryos exhibit stunted growth, ischemic necrosis, and decreased RBCs in the blood. Furthermore, we demonstrate that the dependence on MCL-1 is only during early erythropoiesis, whereas during later stages the cells become MCL-1-independent and upregulate the expression of BCL-xL. Functionally, MCL-1 relies upon its ability to prevent apoptosis to promote erythroid development since co-deletion of the pro-apoptotic effectors Bax and Bak can overcome the requirement for MCL-1 expression. Furthermore, ectopic expression of human BCL2 in erythroid progenitors can compensate for Mcl1 deletion, indicating redundancy between these two anti-apoptotic family members. These data clearly demonstrate a requirement for MCL-1 in promoting survival of early erythroid progenitors.

developmental biology↗

Za2 domain of ZBP1 is a molecular switch regulating Influenza-induced PANoptosis and perinatal lethality during development

Z-DNA-binding protein 1 (ZBP1) is an innate nucleic acid sensor which regulates host defense responses and development. ZBP1 activation triggers inflammation and pyroptosis, necroptosis, and apoptosis (PANoptosis) by activating RIPK3, caspase-8, and the NLRP3 inflammasome. ZBP1 is unique among innate sensors because of its N-terminal Z1 and Z2 domains, which bind to nucleic acids in the Z-conformation. However, the specific role of these Z domains in orchestrating ZBP1 activation and subsequent inflammation and cell death is not clear. Here we have generated Zbp1{Delta}Z2/{Delta}Z2 mice that lack the Z2 domain of ZBP1 and demonstrate that this domain is critical for influenza A virus (IAV)-induced PANoptosis and perinatal lethality in RIPK1-RHIM mutated (Ripk1RHIM/RHIM) mice. Deletion of the Z2 domain in ZBP1 abolished IAV-induced PANoptosis and NLRP3 inflammasome activation. Furthermore, deletion of the Z2 domain of ZBP1 was sufficient to rescue Ripk1RHIM/RHIM mice from the perinatal lethality which is caused by ZBP1-driven cell death and inflammation. Our findings identify the essential role of the Z2 domain of ZBP1 in physiological functions and establish a link between sensing of Z-RNAs via the Z2 domain and the promotion of influenza-induced PANoptosis and perinatal lethality.

immunology↗

HA stability regulates H1N1 influenza virus replication and pathogenicity in mice by modulating type I interferon responses in dendritic cells

Hemagglutinin (HA) stability, or the pH at which the HA is activated to cause membrane fusion, has been associated with the replicative fitness, pathogenicity, transmissibility, and interspecies adaptation of influenza A viruses. Here, we investigated several mechanisms by which a destabilizing HA mutation, Y17H (activation pH 6.0), may attenuate virus replication and pathogenicity in DBA/2 mice, compared to wild-type (WT; activation pH 5.5). Extracellular lung pH was measured to be near neutral (pH 6.9-7.5). WT and Y17H viruses had similar environmental stability at pH 7.0; thus, extracellular inactivation was unlikely to attenuate Y17H virus. The Y17H virus had accelerated single-step replication kinetics in MDCK, A549, and Raw264.7 cells. The destabilizing mutation also increased early infectivity and type I interferon (IFN) responses in mouse bone marrow-derived dendritic cells (DCs). In contrast, the HA-Y17H mutation reduced multistep replication in murine airway mNEC and mTEC cultures and attenuated virus replication, virus spread, severity of infection, and cellular infiltration in the lungs of mice. Normalizing virus infection and weight loss in mice by inoculating them with Y17H virus at a dose 500-fold higher than that of WT virus revealed that the destabilized mutant virus triggered the upregulation of more host genes and increased type I IFN responses and cytokine expression in DBA/2 mouse lungs. Overall, HA destabilization decreased virulence in mice by boosting early infection in DCs, resulting in greater activation of antiviral responses, including type I IFN. These studies reveal HA stability may regulate pathogenicity by modulating IFN responses.\n\nImportanceDiverse influenza A viruses circulate in wild aquatic birds, occasionally infecting farm animals. Rarely, an avian- or swine-origin influenza virus adapts to humans and starts a pandemic. Seasonal and many universal influenza vaccines target the HA surface protein, which is a key component of pandemic influenza. Understanding HA properties needed for replication and pathogenicity in mammals may guide response efforts to control influenza. Some antiviral drugs and broadly reactive influenza vaccines that target the HA protein have suffered resistance due to destabilizing HA mutations that do not compromise replicative fitness in cell culture. Here, we show that despite not compromising fitness in standard cell cultures, a destabilizing H1N1 HA stalk mutation greatly diminishes viral replication and pathogenicity in vivo by modulating type I IFN responses. This encourages targeting the HA stalk with antiviral drugs and vaccines as well as reevaluating previous candidates that were susceptible to destabilizing resistance mutations.

microbiology↗

Dynamic pneumococcal genetic adaptations support bacterial growth and inflammation during coinfection with influenza

Streptococcus pneumoniae (pneumococcus) is one of the primary bacterial pathogens that complicates influenza virus infections. These bacterial coinfections increase influenza-associated morbidity and mortality through a number of immunological and viral-mediated mechanisms, but the specific bacterial genes that contribute to post-influenza pathogenicity are not known. Here, we used genome-wide transposon mutagenesis (Tn-Seq) to reveal bacterial genes that confer improved fitness in influenza-infected hosts. The majority of the 32 identified genes are involved in bacterial metabolism, including nucleotide biosynthesis, amino acid biosynthesis, protein translation, and membrane transport. We generated single-gene deletion (SGD) mutants of five identified genes: SPD1414, SPD2047 (cbiO1), SPD0058 (purD), SPD1098, and SPD0822 (proB), to investigate their effect on in vivo fitness, disease severity, and host immune responses. Growth of SGD mutants was slightly attenuated in vitro and in vivo, but each still grew to high titers in the lungs of mock- and influenza-infected hosts. Despite high bacterial loads, mortality was significantly reduced or delayed with all SGD mutants. Time-dependent reductions in pulmonary neutrophils, inflammatory macrophages, and select proinflammatory cytokines and chemokines were also observed. Immunohistochemical staining further revealed that neutrophil phenotype and distribution was altered in the lungs of influenza-SGD coinfected animals. These studies demonstrate a critical role for specific bacterial genes and for bacterial metabolism in driving virulence and modulating immune function during influenza-associated bacterial pneumonia.

microbiology↗

The Nonlinear Relations that Predict Influenza Viral Dynamics, CD8+ T cell-Mediated Clearance, Lung Pathology, and Disease Severity

Influenza viruses cause a significant amount of morbidity and mortality. Understanding host immune control efficacy and how different factors influence lung injury and disease severity are critical. Here, we established dynamical connections between viral loads, infected cells, CD8+ T cell-mediated clearance, lung injury, inflammation, and disease severity using an integrative model-experiment exchange. The model was validated through CD8 depletion and whole lung histomorphometry, which showed that the infected area matched the model-predicted infected cell dynamics and that the resolved area paralleled the relative CD8 dynamics. Inflammation could further be predicted by the infected cell dynamics, and additional analyses revealed nonlinear relations between lung injury, inflammation, and disease severity. These links between important pathogen kinetics and host pathology enhance our ability to forecast disease progression, potential complications, and therapeutic efficacy.

microbiology↗

Allergic inflammation hinders synergistic viral-bacterial co-infection in C57BL/6 mice

Asthma is a chronic airways disease that can be exacerbated during respiratory infections. Our previous findings that the inflammatory state of allergic airways at the time of influenza A virus (IAV) infection in combination with epidemiologic findings that asthmatics were less likely to suffer from severe influenza during the 2009 pandemic suggest that additional complications of influenza, such as increased susceptibility to bacterial superinfection, may be mitigated in the allergic host. To test this hypothesis, we developed a murine model of triple-disease in which mice were first rendered allergic to Aspergillus fumigatus and co-infected with IAV and Streptococcus pneumoniae seven days apart. Significant alterations to known synergistic effects of co-infection were noted in the allergic mice including reduced morbidity and mortality, bacterial burden, maintenance of alveolar macrophages, and reduced lung inflammation and damage. The lung microbiome of allergic mice differed from that of non-allergic mice during co-infection. To investigate the impact of the microbiome on the pathogenesis of lung disease, we induced a perturbation with a short course of fluoroquinolone antibiotic that is often prescribed for lung infections. A significant change in the microbiome was complemented with alterations to the inflammatory profile and a drastic increase in pro-inflammatory cytokines in allergic mice which were now susceptible to severe disease from IAV and S. pneumoniae co-infection. Our data suggest that responses to co-infection in allergic hosts likely depends on the immune and microbiome states and that antibiotics should be used with caution in individuals with underlying chronic lung disease. Author Summary Asthma is a condition of the lungs that affects millions worldwide. Traditionally, respiratory infections are considered to have a negative impact on asthmatics. However, epidemiological data surrounding the 2009 influenza pandemic suggest that asthmatics may be better equipped to counter severe influenza including bacterial pneumonia. Herein, we introduce a novel mouse model system designed to recapitulate an influenza virus and Streptococcal co-infection in a host with fungal asthma. We found that underlying allergic asthma protects against severe disease induced by co-infection. Mice with underlying allergic inflammation had reduced damage to the lungs and did not show signs of respiratory distress. Among the differences noted in the allergic mice that were protected from viral and bacterial co-infection, was the lung microbiome. Allergic mice lost their protection from co-infection after we perturbed their lung microbiome with antibiotics suggesting that the lung microbiome plays a role in host immunity against invading pathogens.

pathology↗