Project description:Mycobacterium marinum infection in zebrafish (Danio rerio) has been widely used to study human tuberculosis because the bacteria causing these two diseases are close relatives. We studied the zebrafish immune response to M. marinum infection through a whole-genome level transcriptome analysis. In addition, we carried out a medium-scale forward genetic screen to identify genes underlying defense mechanisms against M. marinum infection in zebrafish. Our aim was to gain more information about the genetic mechanisms important in the immune defense against human tuberculosis. In this screen, we identified a mutant zebrafish line with impaired resistance to a low-dose M. marinum infection. In this line, the transcriptome analysis at 14 days post infection revealed decreased expression of a gene homologous to human UNC119 which has been shown to have a role in T cell activation.
Project description:Identification of genetic polymorphisms associated with inter-individual variation in immune response to Mycobacterium tuberculosis infection.
Project description:Investigation of whole genome gene expression level changes in Mycobacterium tuberculosis treated with the DHFR inhibitor WR99210, compared to untreated cells. The antimycobacterial properties of WR99210 are further described in Gerum, A., Ulmer, J., Jacobus, D., Jensen, N., Sherman, D., and C. Sibley. 2002. Novel Saccharomyces cerevisiae screen identifies WR99210 analogues that inhibit Mycobacterium tuberculosis dihydrofolate reductase. Antimicrob Agents Chemother 46(11):3362-3369 [PMID:12384337]
Project description:The innate immune system provides the first response to pathogen infection and orchestrates the activation of the adaptive immune system. Though a large component of the innate immune response is common to all infections, pathogen-specific innate immune responses have been documented as well. The innate immune response is thought to be especially critical for fighting infection with Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB). While TB can be a deadly disease, only 5-10% of individuals infected with MTB develop active disease, and this inter-individual variation is, at least partly, heritable. Studies of inter-individual variation in the innate immune response to MTB infection may therefore shed light on the genetic basis for variation in susceptibility to TB. Yet, to date, we still do not know which properties of the innate immune response are specific to MTB infection and which represent a general response to pathogen infection. To begin addressing this gap, we infected macrophages with eight different bacterial pathogens, including different MTB strains and related mycobacteria, and studied the transcriptional response to infection. We found that although the gene expression changes were largely consistent across the bacterial infection treatments, we were able to identify a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. Genetic variants that are associated with regulatory differences in these genes should be considered candidate loci for explaining inter-individual susceptibility TB. RNA-seq of monocyte-derived macrophages isolated from 6 healthy European males at 4, 18, and 48 hours post-infection with the following 8 bacteria: Mycobacterium tuberculosis (MTB) H37Rv, Mycobacterium tuberculosis GC1237, MTB GC1237, bacillus Calmette-Guérin (BCG), Mycobacterium smegmatis, Yersinia pseudotuberculosis, Salmonella typhimurium, and Staphylococcus epidermidis. table-s1.txt is a tab-delimited text file that contains the batch-corrected log2 counts per million for each of the 156 samples, as well as the Ensembl gene ID and gene name. BCG = bacillus Calmette-Guérin GC = Mycobacterium tuberculosis GC1237 Rv = Mycobacterium tuberculosis (MTB) H37Rv Rv+ = heat-inactivated MTB H37Rv Salm = Salmonella typhimurium Smeg = Mycobacterium smegmatis Staph = Staphylococcus epidermidis Yers = Yersinia pseudotuberculosis
Project description:A zebrafish forward genetic screen for determinants of susceptibility to Mycobacterium marinum identified a hypersusceptible mutant deficient in the lysosomal hydrolase Cathepsin L that manifests the hallmarks of human lysosomal storage diseases. In uninfected mutants, macrophages progressively accumulate undigested material in their lysosomes, leading to impaired migration and the accumulation of unengulfed cell debris. During mycobacterial infection, these vacuolated macrophages cannot migrate to phagocytose infected macrophages undergoing apoptosis in the tuberculous granuloma. Consequently, unengulfed apoptotic macrophages undergo secondary necrosis causing granuloma breakdown and increased mycobacterial growth. Macrophage lysosomal accumulations similarly impair migration to newly infecting mycobacteria. We find that important aspects of this phenotype are recapitulated in human smokers, who are at increased risk for tuberculosis. A majority of alveolar macrophages from smokers exhibit lysosomal accumulations and do not migrate to Mycobacterium tuberculosis. This incapacitation of highly microbicidal first-responding macrophages may contribute to smokers' susceptibility to tuberculosis.
Project description:Identification of genetic polymorphisms associated with inter-individual variation in immune response to Mycobacterium tuberculosis infection.
