Biology subjects

Lata, S.

Publications and source records attributed to Lata, S..

5 recordsLinked to original sources

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

3D Multiplexed Immunohistochemistry Using Opal-TSA Amplification for Enhanced Imaging of Pulmonary TB Lesions

Mycobacterium tuberculosis hijacks the host immune system and persists for several years before the onset of active disease. Spatial characterization of epithelial compartments, immune cell populations and bacteria simultaneously within tissue specimens provide significant information about host pathogen interactions. Here, we present a protocol to detect multiple protein markers using Opal-TSA conjugated fluorescent dyes in free floating 10% neutral buffered formalin fixed thick tissue sections (50-100 m), with minimal additional tissue processing not requiring specialized equipment. Use of thick sections provides more information as compared to classic thin microtomy sections (3-10 m), including the capacity for Z stacking and three-dimensional image rendering. Importantly, reduced tissue processing of samples with this method preserves endogenous fluorescent reporter signal. Use of Opal-TSA conjugated fluorescent dyes enhances the sensitivity of low expressing proteins and supports the use of primary antibodies raised in the same species. Before you beginThis protocol describes the specific use of Mtb infected mouse lungs, but is applicable to any tissue type and species of origin. Institutional permissionsObtain institutional permission to perform animal studies and collect tissues under an approved Institutional Animal Care and Use Committee (IACUC) or Institutional Review Board protocol. Our protocol was approved by Boston Universitys Institutional Animal Care and Use Committee (IACUC protocol number PROTO201800218). MiceB6J.C3-Sst1C3HeB/Fej Krmn and B6. Sst1S, ifnb-YFP mice were developed in our laboratory (available from MMRRC stock # 043908-UNC). HighlightsO_LICompatible with Opal-TSA conjugated fluorescent dyes resulting in enhanced signal sensitivity with low background noise C_LIO_LIReduced tissue processing preserves endogenous fluorescent reporter signals C_LIO_LICompatible with primary antibodies raised in the same species C_LIO_LIDoesnt require specialized automated instruments C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/619885v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@3e3439org.highwire.dtl.DTLVardef@1d6ba85org.highwire.dtl.DTLVardef@6f9595org.highwire.dtl.DTLVardef@1c573ae_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

Combining in-line chromatography coupled SAXS and AIpredicted structures to dissect the mechanism of ParB1parS1 partition assembly formation

Coupling of solution SAXS and AI-predicted structures can be a powerful strategy for delineating subtle conformational changes and self-association in protein switches. ParB, which is a condensate-forming DNA clamp that aids in bacterial chromosomal origin segregation, undergoes CTP-induced conformational switching to enable DNA sliding. The nature of parS DNA-induced conformational change in full-length ParB, and the structural features that govern self-association of ParB for partition assembly condensate formation, remains sparsely understood. We combined chromatography-coupled SAXS, rigid domains obtained from Alphafold model of ParB1 from Vibrio cholerae, and synthetic SAXS data describing known domain interfaces, to build integrative models of conformational states of full-length ParB1. These integrative models revealed how parS1 DNA loading primed ParB1 for clamping and sliding. The CTPase domains in ParB1 were moved nearer upon DNA loading to facilitate clamping, and a lumen lined with a weak DNA binding site was formed below parS1 binding site for capturing the sliding DNA. Furthermore, we showed that an N-terminal segment of ParB1 undergoes concentration-dependent oligomerization. An intrinsically disordered linker joining this oligomerization-prone N-terminal segment and the C-terminal domain curbs self-association of full-length ParB1, which is likely relevant for ParB1-mediated higher order partition assembly formation. To summarize, SAXS and Alphafold were effectively combined to provide unique insights into context-specific domain rearrangements and self-association in ParB1 for the mechanistic understanding of partition assembly formation.

biophysics↗

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↗