Project description:Mycobacterium tuberculosis thrives within macrophages by residing in phagosomes and preventing them from maturing and fusing with lysosomes. A parallel transcriptional survey of intracellular mycobacteria and their host macrophages revealed signatures of heavy metal poisoning. In particular, mycobacterial genes encoding heavy metal efflux P-type ATPases CtpC, CtpG, and CtpV, and host cell metallothioneins and zinc exporter ZnT1, were induced during infection. Consistent with this pattern of gene modulation, we observed a burst of free zinc inside macrophages, and intraphagosomal zinc accumulation within a few hours postinfection. Zinc exposure led to rapid CtpC induction, and ctpC deficiency caused zinc retention within the mycobacterial cytoplasm, leading to impaired intracellular growth of the bacilli. Thus, the use of P(1)-type ATPases represents a M. tuberculosis strategy to neutralize the toxic effects of zinc in macrophages. We propose that heavy metal toxicity and its counteraction might represent yet another chapter in the host-microbe arms race. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-122]
Project description:PARN deficiency is linked to the inherited disease Dyskeratosis Congenita and Familial Pulmonary Fibrosis. The aim of this experiment is to identify miRNAs that are regulated by PARN in human cells, deficiency of which could explain the disease phenotype in patients.
Project description:Immunometabolism is a rapidly growing field, which has led to greater understanding of innate immune cell functions. Macrophages are at the core of this research: polarized subsets of in vitro-derived cells reportedly utilize select metabolic pathways to maintain their phenotype. However, relevance of these in vitro studies to the in vivo setting is not known, and metabolic requirements are likely dependent on unique physiological and cellular metabolic environments. Here we define the metabolic requirements of peritoneal tissue-resident macrophages, the accessibility of these metabolites to cells in the peritoneum, and we dissect the role of this unique environment in maintaining a crucial macrophage function. We find that the peritoneal cavity is enriched in amino acids, most notably glutamate. Peritoneal tissue-resident macrophages have an extraordinarily large mitochondrial capacity compared with other phagocytes; this is primarily fueled by glutaminolysis, which is additionally required to maintain an extensive respiratory burst. Glutaminolysis fuels the electron transport chain, which is enhanced during tissue-resident macrophage respiratory burst via a switch to dependence of mitochondrial complex-II. This is not dependent on the level of NADPH, but requires p47 maintained NADPH-oxidase activity. Therefore, we propose that tissue-resident macrophages exploit their unique metabolic niche by implementing their glutamine-fueled mitochondrial-rich phenotype to sustain respiratory burst to assault pathogens, showing that cell-specific metabolic underpinning is important for function. Importantly, we also find that glutamine is required for the respiratory burst in human monocytes, which highlights that metabolites are not species-specific and can be the link between cellular mechanism in mouse and man.
Project description:Mycobacteria-induced apoptosis of macrophages plays an important role in modulation of the host immune response involving TNF-alpha as major cytokine. The underlying mechanisms are still ill-defined. Here, we show for the first time that methylglyoxal (MG) and AGEs levels were elevated during mycobacterial infection of macrophages and that their increased levels mediated mycobacteria-induced apoptotic and immune response of macrophages. Moreover, we show that high levels of AGEs were formed at the sites of pulmonary tuberculosis. This observation represents the first evidence of the potential involvement of AGEs in tuberculosis and in infectious diseases in general. Global gene expression profiling of MG-treated macrophages reveals diversified potential roles of MG in cellular processes, including apoptosis, immune response, and growth regulation. The results of this study provide new insights into intervention strategies to develop therapeutic tools against infectious diseases in which MG and AGE production plays critical roles. Keywords: time course, replicates, immune response, apoptosis
Project description:Missense mutations in the PLCg2 gene can cause autoinflammation, antibody deficiency and immune dysregulation (APLAID). Clinical and laboratory features include recurrent blistering skin lesions, pulmonary manifestations, inflammatory eye – and bowel diseases accompanied by reduced class-switching memory B cell counts and recurrent infections. Disease onset occurs typically during childhood with varying degrees of severity. To date there is no known cure of APLAID. The potential mechanism by which autoinflammation is promoted in APLAID remains elusive. However, neutrophils and macrophages are the main drivers of autoinflammation. In order to dissect the pathogenicity of disease we analyse the transcriptome of neutrophils and macrophages extracted from newly established APLAID mutant mice.
Project description:Mycobacteria-induced apoptosis of macrophages plays an important role in modulation of the host immune response involving TNF-alpha as major cytokine. The underlying mechanisms are still ill-defined. Here, we show for the first time that methylglyoxal (MG) and AGEs levels were elevated during mycobacterial infection of macrophages and that their increased levels mediated mycobacteria-induced apoptotic and immune response of macrophages. Moreover, we show that high levels of AGEs were formed at the sites of pulmonary tuberculosis. This observation represents the first evidence of the potential involvement of AGEs in tuberculosis and in infectious diseases in general. Global gene expression profiling of MG-treated macrophages reveals diversified potential roles of MG in cellular processes, including apoptosis, immune response, and growth regulation. The results of this study provide new insights into intervention strategies to develop therapeutic tools against infectious diseases in which MG and AGE production plays critical roles. Experiment Overall Design: MH-S cells (ATCC Number: CRL-2019), an alveolar macrophage cell line, was treated with 0.8 mM MG. At different time points after treatment (30 min, 4 h, and 8 h) the cells were harvested for total RNA preparation. As negative control the cells without treatment were included. RNA preparation was performed using Trizol method. Totally three independent experiments were performed, so that each time point consists of biological triplicates.
Project description:We report a pleiotropic disease due to loss-of-function mutations in RHBDF2, the gene encoding iRHOM2, in 2 kindreds with recurrent infections in different organs. One patient had recurrent pneumonia but no colon involvement, another had recurrent infectious hemorrhagic colitis but no lung involvement, and the other two experienced recurrent respiratory infections. Loss of iRHOM2, a rhomboid superfamily member that regulates the ADAM17 metalloproteinase, caused defective ADAM17-dependent cleavage and release of cytokines, including TNF and amphiregulin. To understand the diverse clinical phenotypes, we challenged Rhbdf2-/- mice with Pseudomonas aeruginosa by nasal gavage and observed more severe pneumonia whereas infection with Citrobacter rodentium caused worse inflammatory colitis than wild-type mice. The fecal microbiota in the colitis patient had characteristic oral species that can predispose to colitis. Thus, a new human immunodeficiency arising from iRHOM2 deficiency causes divergent disease phenotypes that can involve the local microbial environment.
Project description:We report a pleiotropic disease due to loss-of-function mutations in RHBDF2, the gene encoding iRHOM2, in 2 kindreds with recurrent infections in different organs. One patient had recurrent pneumonia but no colon involvement, another had recurrent infectious hemorrhagic colitis but no lung involvement, and the other two experienced recurrent respiratory infections. Loss of iRHOM2, a rhomboid superfamily member that regulates the ADAM17 metalloproteinase, caused defective ADAM17-dependent cleavage and release of cytokines, including TNF and amphiregulin. To understand the diverse clinical phenotypes, we challenged Rhbdf2-/- mice with Pseudomonas aeruginosa by nasal gavage and observed more severe pneumonia whereas infection with Citrobacter rodentium caused worse inflammatory colitis than wild-type mice. The fecal microbiota in the colitis patient had characteristic oral species that can predispose to colitis. Thus, a new human immunodeficiency arising from iRHOM2 deficiency causes divergent disease phenotypes that can involve the local microbial environment.