Disparate Effects of Metformin on Mycobacterium tuberculosis Infection in Diabetic and Nondiabetic Mice.
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ABSTRACT:
SUBMITTER: Sathkumara HD
PROVIDER: S-EPMC7927854 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Diabetes mellitus is associated with increased tuberculosis risk and severity. We previously reported that tuberculosis susceptibility in diabetic mice results from a delay in innate immune response to inhaled Mycobacterium tuberculosis, leading to delayed adaptive immune priming and, consequently, a higher plateau lung bacterial burden and greater immune pathology.?We tested the capacity of alveolar macrophages from diabetic mice to phagocytose M. tuberculosis ex vivo and promote T-cell activation in vivo.?Alveolar macrophages from diabetic mice had reduced expression of CD14 and macrophage receptor with collagenous structure (MARCO), which recognize the bacterial cell wall component trehalose 6,6'-dimycolate (TDM). Diabetic alveolar macrophages exhibited reduced phagocytosis of M. tuberculosis or TDM-coated latex beads. This alveolar macrophage phenotype was absent in peritoneal and bone marrow-derived macrophages. Transfer of infected alveolar macrophages from diabetic mice into nondiabetic recipients confirmed an intrinsic alveolar macrophage defect that hindered T-cell priming. The diabetic alveolar macrophage phenotype depended in part on expression of the receptor for advanced glycation end products.?Reduced MARCO and CD14 expression contributes to defective sentinel function of alveolar macrophages, promoting tuberculosis susceptibility in diabetic hosts at a critical early step in the immune response to aerosol infection.
| S-EPMC5144731 | biostudies-literature
Project description:Diabetes mellitus (DM) is a major risk factor for tuberculosis (TB) but the defect in protective immunity responsible for this has not been defined. We previously reported that streptozotocin-induced DM impaired TB defense in mice, resulting in higher pulmonary bacterial burden, more extensive inflammation, and higher expression of several proinflammatory cytokines known to play a protective role in TB. In the current study, we tested the hypothesis that DM leads to delayed priming of adaptive immunity in the lung-draining lymph nodes (LNs) following low dose aerosol challenge with virulent Mycobacterium tuberculosis. We show that M. tuberculosis-specific IFN-gamma-producing T cells arise later in the LNs of diabetic mice than controls, with a proportionate delay in recruitment of these cells to the lung and stimulation of IFN-gamma-dependent responses. Dissemination of M. tuberculosis from lung to LNs was also delayed in diabetic mice, although they showed no defect in dendritic cell trafficking from lung to LNs after LPS stimulation. Lung leukocyte aggregates at the initial sites of M. tuberculosis infection developed later in diabetic than in nondiabetic mice, possibly related to reduced levels of leukocyte chemoattractant factors including CCL2 and CCL5 at early time points postinfection. We conclude that TB increased susceptibility in DM results from a delayed innate immune response to the presence of M. tuberculosis-infected alveolar macrophages. This in turn causes late delivery of Ag-bearing APC to the lung draining LNs and delayed priming of the adaptive immune response that is necessary to restrict M. tuberculosis replication.
| S-EPMC2874741 | biostudies-literature
Project description:Tuberculosis (TB) has emerged as the most prominent bacterial disease found in human immunodeficiency virus (HIV)-positive individuals worldwide. Due to high prevalence of asymptomatic Mycobacterium tuberculosis (Mtb) infections, the future HIV vaccine in areas highly endemic for TB will often be administrated to individuals with an ongoing Mtb infection. The impact of concurrent Mtb infection on the immunogenicity of a HIV vaccine candidate, MultiHIV DNA/protein, was investigated in mice. We found that, depending on the vaccination route, mice infected with Mtb before the administration of the HIV vaccine showed impairment in both the magnitude and the quality of antibody and T cell responses to the vaccine components p24Gag and gp160Env. Mice infected with Mtb prior to intranasal HIV vaccination exhibited reduced p24Gag-specific serum IgG and IgA, and suppressed gp160Env-specific serum IgG as compared to respective titers in uninfected HIV-vaccinated controls. Importantly, in Mtb-infected mice that were HIV-vaccinated by the intramuscular route the virus neutralizing activity in serum was significantly decreased, relative to uninfected counterparts. In addition mice concurrently infected with Mtb had fewer p24Gag-specific IFN-?-expressing T cells and multifunctional T cells in their spleens. These results suggest that Mtb infection might interfere with the outcome of prospective HIV vaccination in humans.
| S-EPMC3406616 | biostudies-literature
Project description:Objective – Previous studies showed that genetic deletion or pharmacological blockade of the Receptor for Advanced Glycation Endproducts (RAGE) prevents the early structural changes in the glomerulus associated with diabetic nephropathy (DN). To overcome limitations of mouse models that lack the progressive glomerulosclerosis observed in humans, we studied the contribution of RAGE to DN in the OVE26 type 1 mouse, a model of progressive glomerulosclerosis and decline of renal function. Research Design and Methods – We bred OVE26 mice with homozygous RAGE knock out (RKO) mice and examined structural changes associated with DN and used inulin clearance studies and albumin:creatinine measurements to assess renal function. Affymetrix Mouse 430.2 microarrays were used to measure the differential expression of OVE26vsFVB(WT) mice. Transcriptional changes in the TGF-β1 and Plasminogen activator inhibitor 1 gene products were measured by pcr to investigate mechanisms underlying accumulation of mesangial matrix in OVE26 mice. Results - Deletion of RAGE in OVE26 mice reduced nephromegaly, mesangial sclerosis, cast formation, glomerular basement membrane thickening, podocyte effacement, and albuminuria. The significant 29% reduction in glomerular filtration rate observed in OVE26 mice was completely prevented by deletion of RAGE. Increased transcription of the genes for Plasminogen activator inhibitor 1, TGF-β1, TGF-β induced, α1- (IV) collagen observed in OVE26 renal cortex significantly reduced in OVE26 RKO kidney cortex. ROCK1 activity was significantly lower in OVE26 RKO compared to OVE26 kidney cortex. Conclusions - These data provide compelling evidence for critical roles for RAGE in the pathogenesis of DN and suggest that strategies targeting RAGE in long-term diabetes may prevent loss of renal function.
2011-02-22 | GSE20844 | GEO
Project description:Objective – Previous studies showed that genetic deletion or pharmacological blockade of the Receptor for Advanced Glycation Endproducts (RAGE) prevents the early structural changes in the glomerulus associated with diabetic nephropathy (DN). To overcome limitations of mouse models that lack the progressive glomerulosclerosis observed in humans, we studied the contribution of RAGE to DN in the OVE26 type 1 mouse, a model of progressive glomerulosclerosis and decline of renal function. Research Design and Methods – We bred OVE26 mice with homozygous RAGE knock out (RKO) mice and examined structural changes associated with DN and used inulin clearance studies and albumin:creatinine measurements to assess renal function. Affymetrix Mouse 430.2 microarrays were used to measure the differential expression of OVE26vsFVB(WT) mice. Transcriptional changes in the TGF-?1 and Plasminogen activator inhibitor 1 gene products were measured by pcr to investigate mechanisms underlying accumulation of mesangial matrix in OVE26 mice. Results - Deletion of RAGE in OVE26 mice reduced nephromegaly, mesangial sclerosis, cast formation, glomerular basement membrane thickening, podocyte effacement, and albuminuria. The significant 29% reduction in glomerular filtration rate observed in OVE26 mice was completely prevented by deletion of RAGE. Increased transcription of the genes for Plasminogen activator inhibitor 1, TGF-?1, TGF-? induced, ?1- (IV) collagen observed in OVE26 renal cortex significantly reduced in OVE26 RKO kidney cortex. ROCK1 activity was significantly lower in OVE26 RKO compared to OVE26 kidney cortex. Conclusions - These data provide compelling evidence for critical roles for RAGE in the pathogenesis of DN and suggest that strategies targeting RAGE in long-term diabetes may prevent loss of renal function. The differential gene expression of OVE26 (diabetics) vs FVB (nodiabetic WT) mice was measured using Affymetrix Mouse 430.2 arrays.
2011-02-22 | E-GEOD-20844 | biostudies-arrayexpress
Project description:Infection with Mycobacterium tuberculosis causes the illness tuberculosis with an annual mortality of approximately 2 million. Understanding the nature of the host-pathogen interactions at different stages of tuberculosis is central to new strategies for developing chemotherapies and vaccines. Toward this end, we adapted microarray technology to analyze the change in gene expression profiles of M. tuberculosis during infection in mice. This protocol provides the transcription profile of genes expressed during the course of early tuberculosis in immune-competent (BALB/c) and severe combined immune-deficient (SCID) hosts in comparison with growth in medium. The microarray analysis revealed clusters of genes that changed their transcription levels exclusively in the lungs of BALB/c, SCID mice, or medium over time. We identified a set of genes (n = 67) activated only in BALB/c and not in SCID mice at 21 days after infection, a key point in the progression of tuberculosis. A subset of the lung-activated genes was previously identified as induced during mycobacterial survival in a macrophage cell line. Another group of in vivo-expressed genes may also define a previously unreported genomic island. In addition, our analysis suggests the similarity between mycobacterial transcriptional machinery during growth in SCID and in broth, which questions the validity of using the SCID model for assessing mycobacterial virulence. The in vivo expression-profiling technology presented should be applicable to any microbial model of infection.
| S-EPMC384793 | biostudies-literature
Project description:Approximately 2 billion people are infected with Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), and an estimated 1.5 million individuals die annually from TB. Presently, Mycobacterium bovis BCG remains the only licensed TB vaccine; however, previous studies suggest its protective efficacy wanes over time and fails in preventing pulmonary TB. Therefore, a safe and effective vaccine is urgently required to replace BCG or boost BCG immunizations. Our previous studies revealed that mycobacterial proteins are released via exosomes from macrophages infected with M. tuberculosis or pulsed with M. tuberculosis culture filtrate proteins (CFP). In the present study, exosomes purified from macrophages treated with M. tuberculosis CFP were found to induce antigen-specific IFN-? and IL-2-expressing CD4(+) and CD8(+) T cells. In exosome-vaccinated mice, there was a similar TH1 immune response but a more limited TH2 response compared to BCG-vaccinated mice. Using a low-dose M. tuberculosis mouse aerosol infection model, exosomes from CFP-treated macrophages were found to both prime a protective immune response as well as boost prior BCG immunization. The protection was equal to or superior to BCG. In conclusion, our findings suggest that exosomes might serve as a novel cell-free vaccine against an M. tuberculosis infection.
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Project description:Tuberculosis (TB) is a heterogeneous disease manifesting in a subset of individuals infected with aerosolized Mycobacterium tuberculosis (Mtb). Unlike human TB, murine infection results in uniformly high lung bacterial burdens and poorly organized granulomas. To develop a TB model that more closely resembles human disease, we infected mice with an ultra-low dose (ULD) of between 1-3 founding bacteria, reflecting a physiologic inoculum. ULD-infected mice exhibited highly heterogeneous bacterial burdens, well-circumscribed granulomas that shared features with human granulomas, and prolonged Mtb containment with unilateral pulmonary infection in some mice. We identified blood RNA signatures in mice infected with an ULD or a conventional Mtb dose (50-100 CFU) that correlated with lung bacterial burdens and predicted Mtb infection outcomes across species, including risk of progression to active TB in humans. Overall, these findings highlight the potential of the murine TB model and show that ULD infection recapitulates key features of human TB.
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Project description:Specific spatial organization of granulomas within the lungs is crucial for protective anti-tuberculosis (TB) immune responses. However, only large animal models such as macaques are thought to reproduce the morphological hallmarks of human TB granulomas. In this study, we show that infection of mice with clinical "hypervirulent" Mycobacterium tuberculosis (Mtb) HN878 induces human-like granulomas composed of bacilli-loaded macrophages surrounded by lymphocytes and organized localization of germinal centers and B-cell follicles. Infection with laboratory-adapted Mtb H37Rv resulted in granulomas that are characterized by unorganized clusters of macrophages scattered between lymphocytes. An in-depth exploration of the functions of B cells within these follicles suggested diverse roles and the activation of signaling pathways associated with antigen presentation and immune cell recruitment. These findings support the use of clinical Mtb HN878 strain for infection in mice as an appropriate model to study immune parameters associated with human TB granulomas.
| S-EPMC7184917 | biostudies-literature