Biology subjects

Kobzik, L.

Publications and source records attributed to Kobzik, L..

9 recordsLinked to original sources

bioRxiv2025

Elimination of senescent cells with senolytic host-directed therapy reduces tuberculosis progression in mice

By eliciting lung necrosis, which enhances aerosol transmission, Mycobacterium tuberculosis (Mtb) sustains its long-term survival as a human pathogen. In studying the human-like necrotic granuloma lesions characteristic of Mtb-infected B6.Sst1S mice, we found that lung myeloid cells display elevated senescence markers: cell cycle arrest proteins p21 and p16, the DNA damage marker {gamma}H2A.X, senescence-associated {beta}-galactosidase activity, and senescence-associated secretory phenotype (SASP). These markers were also elevated in Mtb-infected aged wild type (WT) mice but not in young WT mice. Global transcriptomics data revealed upregulation of pro-survival (PI3K, MAPK) and anti-apoptotic pathways in Mtb-infected B6.Sst1S macrophages. As senescent cells are terminally growth-arrested yet metabolically active cells that release tissue-damaging, immunosuppressive SASP, we treated Mtb-infected mice with a cocktail of three senolytic drugs (dasatinib, quercetin, and fisetin) designed to kill senescent cells. Senolytic drug treatment prolonged survival and reduced Mtb lung counts in B6.Sst1S and aged WT mice to a greater degree than young WT mice and concomitantly reduced lung senescence markers. These findings indicate that (1) Mtb infection may induce lung myeloid cells to enter a senescent state and that these cells may promote disease progression, and (2) senolytic drugs merit consideration for human clinical trials against tuberculosis (TB). Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/645957v2_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@1ce7eeeorg.highwire.dtl.DTLVardef@1ef55d4org.highwire.dtl.DTLVardef@1ebef03org.highwire.dtl.DTLVardef@98b61f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIMtb lung infection results in recruitment of both restrictive and permissive myeloid cells to the nascent granuloma. C_LIO_LIMtb infection induces certain permissive myeloid cells to enter a senescent state, characterized by cell cycle arrest and they promote local immunosuppression. C_LIO_LITreatment with a Senolytic drug cocktail, which kills senescent cells, augments host resistance against Mtb proliferation, lethality and immunopathology. C_LI

microbiology↗

bioRxiv2025

Protocol for Developing a Mouse Model of Post Primary Pulmonary Tuberculosis after Hematogenous Spread in Native Lungs and Lung Implants

This protocol describes a mouse model of post-primary pulmonary tuberculosis (PTB) that develops after hematogenous spread from the primary lesion in native lungs and subcutaneous lung implants. It demonstrates that virulent Mycobacterium tuberculosis (Mtb) disseminates to lymphoid tissue in many organs, but selectively damages the lungs. This approach demonstrates a particular vulnerability of the lung tissue to virulent Mtb independent of the route of infection and provides a robust platform for examining lung-specific mechanisms driving TB pathology. HighlightsO_LIMouse model for studying mechanisms driving post-primary pulmonary TB progression in immune hosts C_LIO_LIModels a hematogenous spread of virulent Mycobacterium tuberculosis to the lungs from a primary site of infection C_LIO_LIAllows for the investigation of lung-specific mechanisms of TB susceptibility using lung tissue implants. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=184 SRC="FIGDIR/small/640830v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@1ce5384org.highwire.dtl.DTLVardef@cd3b88org.highwire.dtl.DTLVardef@1ff7ce7org.highwire.dtl.DTLVardef@614598_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Myc Dysregulation in Activated Macrophages Initiates Iron-Mediated Lipid Peroxidation that Fuels Type I Interferon and Compromises TB Resistance

A quarter of human population is infected with Mycobacterium tuberculosis, but less than 10% of those infected develop pulmonary TB. We developed a genetically defined sst1-susceptible mouse model that uniquely reproduces a defining feature of human TB: the development of necrotic lung granulomas and determined that the sst1-susceptible phenotype was driven by the aberrant macrophage activation. This study demonstrates that the aberrant response of the sst1-susceptible macrophages to prolonged stimulation with TNF is primarily driven by conflicting Myc and antioxidant response pathways leading to a coordinated failure 1) to properly sequester intracellular iron and 2) to activate ferroptosis inhibitor enzymes. Consequently, iron-mediated lipid peroxidation fueled Ifn{beta} superinduction and sustained the Type I Interferon (IFN-I) pathway hyperactivity that locked the sst1-susceptible macrophages in a state of unresolving stress and compromised their resistance to Mtb. The accumulation of the aberrantly activated, stressed, macrophages within granuloma microenvironment led to the local failure of anti-tuberculosis immunity and tissue necrosis. The upregulation of Myc pathway in peripheral blood cells of human TB patients was significantly associated with poor outcomes of TB treatment. Thus, Myc dysregulation in activated macrophages results in an aberrant macrophage activation and represents a novel target for host-directed TB therapies.

immunology↗

bioRxiv2023

Aberrant macrophage activation and failed regeneration of pulmonary epithelium promote tuberculosis progression uniquely in lung tissue

Pulmonary tuberculosis (PTB) represents 85% of the disease burden caused by Mycobacterium tuberculosis (Mtb) and promotes aerosol transmission infecting about a quarter of people globally. Most Mtb infections are effectively limited within primary granulomatous lesions. Containment failures lead to hematogenous spread and the formation of post-primary destructive PTB lesions. Factors that favor Mtb survival and replication in the lungs after hematogenous spread despite systemic immunity represent appealing targets for host-directed TB therapies, but are currently unknown. We developed a novel mouse model that mimics progression of chronic post-primary PTB in humans: wherein PTB lesions form after hematogenous spread from a remote primary lesion in immunocompetent but TB-susceptible B6.Sst1S mice. The B6.Sst1S mice developed PTB lesions featuring granulomatous pneumonia, bronchogenic expansion and broncho-occlusion closely resembling post-primary PTB in humans. Using spatial transcriptomic and fluorescent multiplexed immunochemistry, we demonstrated the expansion of myeloid cell populations with the appearance of alternatively activated macrophages, dissolution of initial lymphoid follicles, and accumulation of de-differentiated lung epithelial cells in the advanced PTB lesions. To determine whether lung parenchymal cells or lung oxygenation were necessary for the pulmonary TB progression, we implanted lung and spleen fragments subcutaneously to serve as potential targets for hematogenous spread. The lung (but not spleen) implants displayed characteristic organized granulomas with necrosis and Mtb replication demonstrating that deleterious interactions of aberrantly activated macrophages with the inflammation-injured lung resident cells, and possibly hypoxia, not oxygenation, are critical determinants of PTB progression in immunocompetent hosts. Necrotic TB lesions also developed in subcutaneous implants of human lung tissue in mice with human immune system after respiratory infection. These animal models may serve to further dissect the lung-specific mechanisms of host susceptibility to virulent Mtb and for testing therapeutic interventions targeting these mechanisms.

immunology↗

bioRxiv2020

Maladaptive oxidative stress cascade drives type I interferon hyperactivity in TNF activated macrophages promoting necrosis in murine tuberculosis granulomas

Tuberculosis remains a critical infectious disease world-wide. The development of novel therapeutic strategies requires greater understanding of host factors that contribute to disease susceptibility. A major unknown in TB pathogenesis is the mechanism of necrosis in TB granulomas that leads to the massive lung tissue damage and cavity formation necessary for the pathogen transmission. In humans, TB progression has been linked to hyperactivity of type I IFN (IFN-I) pathway, the primary cause of which remains elusive. We studied the mechanistic drivers of pulmonary TB progression using a unique model B6J.C3-Sst1C3HeB/Fej Krmn mice that develop human-like necrotic TB granulomas and IFN-I hyperactivity. We established that IFN{beta} super-induction occurred in the susceptible macrophages in response to continuous TNF stimulation in the context of a dysregulated antioxidant defense. We observed that unresolving oxidative stress amplified the induction of IFN{beta} through JNK activation and induced the Integrated Stress Response via PKR activation as a compensatory pathway. Subsequently, PKR amplifies IFN{beta} upregulation, forming a positive feedback loop, maintaining the hyperinflammatory state in susceptible macrophages and leading to mitochondrial dysfunction. Thus, within the inflammatory milieu, a cell-intrinsic mechanism of chronic regulatory dysfunction and unresolved stress gradually weakens the macrophage and ultimately promotes the necrotization of TB granulomas. The aberrant macrophage response to TNF can be prevented by an iron chelator and inhibitor of lipid peroxidation, ferrostatin-1. Moreover, ferrostatin treatment increased macrophage survival and boosted bacterial control in the TNF-stimulated macrophages infected with virulent Mtb. These findings identify targets for host-directed therapeutics to interrupt necrotization in TB granulomas.

immunology↗

bioRxiv2020

Age-dependent regulation of SARS-CoV-2 cell entry genes and cell death programs correlates with COVID-19 disease severity

Angiotensin-converting enzyme 2 (ACE2) maintains cardiovascular and renal homeostasis but also serves as the entry receptor for the novel severe acute respiratory syndrome coronavirus (SARS-CoV-2), the causal agent of novel coronavirus disease 2019 (COVID-19)1. COVID-19 disease severity, while highly variable, is typically lower in pediatric patients than adults (particularly the elderly), but increased rates of hospitalizations requiring intensive care are observed in infants than in older children. The reasons for these differences are unknown. To detect potential age-based correlates of disease severity, we measured ACE2 protein expression at the single cell level in human lung tissue specimens from over 100 donors from [~]4 months to 75 years of age. We found that expression of ACE2 in distal lung epithelial cells generally increases with advancing age but exhibits extreme intra- and inter-individual heterogeneity. Notably, we also detected ACE2 expression on neonatal airway epithelial cells and within the lung parenchyma. Similar patterns were found at the transcript level: ACE2 mRNA is expressed in the lung and trachea shortly after birth, downregulated during childhood, and again expressed at high levels in late adulthood in alveolar epithelial cells. Furthermore, we find that apoptosis, which is a natural host defense system against viral infection, is also dynamically regulated during lung maturation, resulting in periods of heightened apoptotic priming and dependence on pro-survival BCL-2 family proteins including MCL-1. Infection of human lung cells with SARS-CoV-2 triggers an unfolded protein stress response and upregulation of the endogenous MCL-1 inhibitor Noxa; in juveniles, MCL-1 inhibition is sufficient to trigger apoptosis in lung epithelial cells - this may limit virion production and inflammatory signaling. Overall, we identify strong and distinct correlates of COVID-19 disease severity across lifespan and advance our understanding of the regulation of ACE2 and cell death programs in the mammalian lung. Furthermore, our work provides the framework for potential translation of apoptosis modulating drugs as novel treatments for COVID-19.

cell biology↗

bioRxiv2019

Channeling macrophage polarization by using a selective translation inhibitor

Macrophages contribute to host immunity and tissue homeostasis via alternative activation programs. M1-like macrophages control intracellular bacterial pathogens and tumor progression. In contrast, M2-like macrophages shape reparative microenvironments that can be conducive for pathogen survival or tumor growth. An imbalance of these macrophages phenotypes may perpetuate sites of chronic unresolved inflammation, such as infectious granulomas and solid tumors. We have found that plant-derived and synthetic rocaglates sensitize macrophages to low concentrations of the M1-inducing cytokine IFN-gamma and inhibit their responsiveness to IL-4, a prototypical activator of the M2-like phenotype. Treatement of primary macrophages with rocaglates increased their resilience to oxidative stress, stimulated autophagy and killing of intracellular mycobacteria. Thus, rocaglates represent a novel class of immunomodulators that can direct macrophage polarization towards the M1-like phenotype in complex microenvironments associated with hypofunction of type 1 and/or hyperactivation of type 2 immunity, e.g. chronic bacterial infections, allergies and, possibly, certain tumors.

immunology↗

bioRxiv2018

The integrated stress response mediates type I interferon driven necrosis in Mycobacterium tuberculosis granulomas

Necrosis in the tuberculous granuloma is a hallmark of tuberculosis that enables pathogen survival and transmission. Susceptibility to tuberculosis and several other intracellular bacteria is controlled by a mouse genetic locus, sst1, and mice carrying the sst1-suscepible (sst1S) genotype develop necrotic inflammatory lung lesions, similar to human TB granulomas. Our previous work established that increased disease severity in sst1S mice reflects dysfunctional macrophage effector or tolerance mechanisms, but the molecular mechanisms have remained unclear. Here we demonstrate that sst1S macrophages develop aberrant, biphasic responses to TNF characterized by super-induction of stress and type I interferon pathways after prolonged TNF stimulation with this late-stage response being initiated by oxidative stress and Myc activation and driven via a JNK - IFN{beta} - PKR circuit. This circuit leads to induction of the integrated stress response (ISR) mediated by eIF2 phosphorylation and the subsequent hyper-induction of ATF3 and ISR-target genes Chac1, Trib3, Ddit4. The administration of ISRIB, a small molecule inhibitor of the ISR, blocked the development of necrosis in lung granulomas of M. tuberculosis-infected sst1S mice and concomitantly reduced the bacterial burden revealing that induction of the ISR and the locked-in state of escalating stress driven by type I IFN pathway in sst1S macrophages plays a causal role in the development of necrosis. Our data support a generalizable paradigm in intracellular pathogen-host interactions wherein host susceptibility emerges within inflammatory tissue due to imbalanced macrophage responses to growth, differentiation, activation and stress stimuli. Successful pathogens such as M. tuberculosis may exploit this aberrant response in susceptible hosts to induce necrotic lesions that favor long-term pathogen survival and transmission. Interruption of the aberrant stress response with inhibitors such as ISRIB may offer novel therapeutic strategies.

immunology↗

bioRxiv2017

Macrophage resilience and control of intracellular bacteria requires sst1-dependent integration of c-Myc, stress response and type I IFN pathways

Host susceptibility to tuberculosis and several other intracellular bacteria is controlled by a mouse genetic locus, sst1. Necrotic inflammatory lesions, similar to human TB granulomas, are a hallmark of the sst1 susceptible phenotype. Our previous work established that increased disease severity in sst1 susceptible mice reflects dysfunctional macrophage effector or tolerance mechanisms, but the molecular mechanisms have been unclear.\n\nWe demonstrate that sst1-deficient macrophages develop aberrant, biphasic responses to TNF, characterized by super-induction of stress and type I interferon pathways after prolonged TNF stimulation. This late stage response was initiated by oxidative stress and Myc. It was driven via a JNK - IFN{beta} - PKR feed-forward circuit locking the susceptible macrophages in a state of escalating stress. Consequently, prolonged TNF stimulation of the susceptible macrophages reduced their resilience to subsequent infection with intracellular bacteria.\n\nThe data support a generalizable paradigm in host - pathogen interactions, where susceptibility emerges gradually within inflammatory tissue due to imbalanced macrophage responses to growth, differentiation, activation and stress stimuli prior to encountering pathogens. This explains how successful pathogens may locally bypass mechanisms of resistance in otherwise immunocompetent hosts and suggests novel therapeutic strategies.

immunology↗