Platelets facilitate primary progressive tuberculosis by restricting the oxidative burst in phagocytes
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ABSTRACT: Tuberculosis (TB) remains the leading cause of death by a single infectious agent worldwide. Despite decades of active research, host factors which underly susceptibility to Mycobacterium tuberculosis (Mtb), the etiologic agent of TB, are still ill defined. We investigated the role of platelets (PLTs) during primary TB in mice as these cells were recently assigned multiple immunological functions. PLTs were present at the site of infection, formed aggregates with different myeloid subsets during experimental TB and such aggregates were detected also in TB patients. PLTs were detrimental during the early phase of infection and this effect was uncoupled from their canonical activation. PLTs left lung cell dynamics and patterns of anti-mycobacterial T-cell responses unchanged. PLTs hampered cell autonomous defense by restricting production of reactive oxygen species (ROS) in lung residing myeloid cells. Thus, PLTs orchestrate immunity in TB by modulating innate immune responsiveness during primary lung infection and may be amenable to new interventions for this deadly disease.
Project description:The molecular mechanisms that control innate cell recruitment during chronic infection and inflammation, such as tuberculosis (TB), are incompletely understood. During TB, myeloid cells infiltrate the lung and sustain local inflammation. We identified microRNA (miR)-223 as one of the most abundant noncoding RNAs in lung parenchyma of TB patients and susceptible mice. MiR-223 controlled lung recruitment of myeloid cells, and consequently, neutrophil-driven lethal inflammation, by directly targeting the chemoattractants CXCL2, CCL3 and IL-6. Our study reveals an essential role for a single miR in TB. Moreover, we identify new targets for and assign novel biological functions to miR-223. By regulating leukocyte chemotaxis via chemoattractants, miR223 is critical for control of TB and probably other nonresolving inflammatory diseases. MicroRNAs expression analysis in whole blood from 8 TB and 8 TST+ subjects. The samples were collected at Makerere University in Kampala, Uganda. Gene expression analysis of whole blood and lung tissue of C57/BL6 and miR-223-/- mouse strains (8-12 weeks of age) after Mtb aerosol infection. Samples were collected at 7, 14 and 21 days post infection.
Project description:The molecular mechanisms that control innate cell recruitment during chronic infection and inflammation, such as tuberculosis (TB), are incompletely understood. During TB, myeloid cells infiltrate the lung and sustain local inflammation. We identified microRNA (miR)-223 as one of the most abundant noncoding RNAs in lung parenchyma of TB patients and susceptible mice. MiR-223 controlled lung recruitment of myeloid cells, and consequently, neutrophil-driven lethal inflammation, by directly targeting the chemoattractants CXCL2, CCL3 and IL-6. Our study reveals an essential role for a single miR in TB. Moreover, we identify new targets for and assign novel biological functions to miR-223. By regulating leukocyte chemotaxis via chemoattractants, miR223 is critical for control of TB and probably other nonresolving inflammatory diseases.
Project description:Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), latently infects one quarter of the world’s population. The rise of multidrug resistant (MDR) Mtb infections worldwide presents a significant obstacle to curb TB globally. While human studies report dysregulated immune responses in MDR TB patients, there is a lack of clear understanding of the host-pathogen interactions following MDR Mtb infection. We recently showed that Mtb carrying a rifampicin drug resistance (RDR)-conferring single nucleotide polymorphism in the RNA polymerase-B gene (Mtb rpoB-H445Y) can modulate host macrophage metabolic reprogramming by production of Type I IFNs. Here, using a mouse model, we have characterized the host immune response in vivo following RDR Mtb infection. We show that despite establishment of Mtb infection in the lung and dissemination to the peripheral organs, lung myeloid and lymphoid immune responses to RDR Mtb is suppressed through a Type I IFN-dependent mechanism. These results coincide with a muted responses in the bone marrow hematopoietic stem and progenitor cells (HSPCs) and progenitors following RDR Mtb infection. These results suggest that host directed therapeutics and vaccines for drug resistant TB may need to be target specific host immune pathways for protection.
Project description:Bacille Calmette Guerin (BCG) is the only licensed vaccine against Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease. However, BCG has limited efficacy, necessitating the development of better vaccines. Non-tuberculous mycobacteria (NTM), a distinct lineage from Mtb, are opportunistic pathogens present in the environment. TB endemic countries experience higher exposure to NTM, but previous studies have not elucidated the relationship between NTM exposure and BCG efficacy. Therefore, we developed a mouse model (BCG+NTM) that mimics human BCG vaccination at an early stage and continuous NTM exposure via the oral route, including during TB infection. Our results show that BCG+NTM mice had improved protection against pulmonary TB correlating with increased pulmonary influx of B-cells, higher titers of anti-Mtb IgA and IgG antibodies in serum and airways, compared to mice vaccinated with BCG alone. Notably, the lungs of BCG+NTM mice developed B-cell aggregates expressing markers of germinal center formation as determined by spatial transcriptomics. We conclude a direct correlation between NTM exposure and protection from TB, with B-cells playing a crucial role.
Project description:Tuberculosis (TB) remains the world’s top infectious killer. Understanding how immune mediators determine the outcome of Mycobacterium tuberculosis infection could facilitate the design of better therapies against this devastating disease. GM-CSF mediates protective immunity against TB but the underlying mechanisms remain elusive. To determine the molecular mechanisms underlying the protective role of GM-CSF during M. tuberculosis infection we performed RNA-sequencing analyses of whole blood and lung samples obtained from C57Bl/6 mice infected with HN878 and treated with anti-GM-CSF monoclonal antibody or isotype control. Uninfected mice were also treated and used as uninfected controls. Three weeks post-infection, whole blood and lungs were harvested from each individual mouse and processed for RNA-sequencing. Transcriptomic analyses revealed that during M. tuberculosis infection GM-CSF regulates the expression of genes associated with neutrophil recruitment and activation and type I IFN-inducible genes, which have been previously associated with TB pathogenesis. Further mechanistical studies showed that disease exacerbation driven by GM-CSF blockade during M. tuberculosis infection was type I IFN and neutrophil-dependent and that over-activation of neutrophils by type I IFN induced NET formation at the site of infection. NETs were also found in necrotic lung lesions from patients with pulmonary TB and type I IFN-driven NET formation correlated with increased disease susceptibility in different mouse models of TB. Our findings reveal an important immune network that may play a central role in determining TB outcome.
Project description:Tuberculosis (TB) remains the world’s top infectious killer. Understanding how immune mediators determine the outcome of Mycobacterium tuberculosis infection could facilitate the design of better therapies against this devastating disease. GM-CSF mediates protective immunity against TB but the underlying mechanisms remain elusive. To determine the molecular mechanisms underlying the protective role of GM-CSF during M. tuberculosis infection we performed RNA-sequencing analyses of whole blood and lung samples obtained from C57Bl/6 mice infected with HN878 and treated with anti-GM-CSF monoclonal antibody or isotype control. Uninfected mice were also treated and used as uninfected controls. Three weeks post-infection, whole blood and lungs were harvested from each individual mouse and processed for RNA-sequencing. Transcriptomic analyses revealed that during M. tuberculosis infection GM-CSF regulates the expression of genes associated with neutrophil recruitment and activation and type I IFN-inducible genes, which have been previously associated with TB pathogenesis. Further mechanistical studies showed that disease exacerbation driven by GM-CSF blockade during M. tuberculosis infection was type I IFN and neutrophil-dependent and that over-activation of neutrophils by type I IFN induced NET formation at the site of infection. NETs were also found in necrotic lung lesions from patients with pulmonary TB and type I IFN-driven NET formation correlated with increased disease susceptibility in different mouse models of TB. Our findings reveal an important immune network that may play a central role in determining TB outcome.
Project description:Tuberculosis (TB) is a contagious disease that is a primary cause of mortality and illness in around a quater of the world' population particular in low income nations. The disease most commonly affects lung, but pathogens can also be found in other parts of the body. Mycobacterium tuberculosis (Mtb) is the etiologic agent of TB and its ability to penetrate immune cells and develop a niche by beating the host's defense mechanism is crucial to its pathogenic sucess. Mtb has a diverse lipid and protein spectrum. Understanding the host-pathogen-interplay in active TB will have a substantial impact in understanding molecular mechanisms of Mtb infection and guide the development of vaccination, diagnostics and therapy response monitoring.
Project description:Pyrazinamide (PZA) is one of the first line antibiotics used for the treatment of tuberculosis (TB). we have used human monocyte and a mouse model of pulmonary TB to investigate whether treatment with PZA, in addition to its known anti-mycobacterial properties, modulate the host immune response during Mycobacterium tuberculosis (Mtb) infection. Mice were infected with Mtb and treatment with PZA was started at 28 days post-infection. At 42 days and 63 days post-infection, group of animals were euthanized and lung tissue was collected to isolate total RNA and used in microarray experiments. Mtb-infected, untreated animals served as controls.
Project description:Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is an exquisitely adapted human pathogen capable of surviving for decades in the lungs of immune competent individuals in absence of disease. The World Health Organization estimates that 2 billion people have latent TB infection (LTBI), defined by positive immunologic response to Mtb antigens with no clinical signs of disease. A better understanding of host and pathogen determinants of LTBI and subsequent reactivation would benefit TB control efforts. Animal models of LTBI have been hampered mainly by an inability to achieve complete bacillary clearance. We have characterized a rabbit model of LTBI in which, similar to most humans, complete clearance of pulmonary Mtb infection and pathology occurs spontaneously. The evidence that Mtb-CDC1551-infected rabbits achieve LTBI, rather than sterilization, is based on the ability of the bacilli to be reactivated following immune suppression. The microarray experiments involves comparison of: 1) Changes in rabbit gene expression between Mtb-CDC1551 infected and uninfected animals at 2,4,8 and 12 weeks post infection. New Zealand White rabbits were infected with Mtb CDC1551 at 3.5log10 (on day 0). Lung tissue from Mtb-infected rabbits were isolated from uninfected (control) and at 2, 4, 8 and 16 weeks post infection and used for total RNA extraction. Total rabbit lung RNA was used for microarray analysis to determine infection induced changes in host gene expression.
Project description:We report the phenotype of human lung ILC2 and ILC3 populations from individuals with tuberculosis (TB) and non-TB cancer controls. We find that ILC2s demonstrate moderate transcriptional differences in TB infection, whereas ILC3s demonstrate large differences.