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Cellular responses to mycobacterial antigens are present in bronchoalveolar lavage fluid used in the diagnosis of sarcoidosis.

ABSTRACT: Considerable evidence supports the concept that CD4(+) T cells are important in sarcoidosis pathogenesis, but the antigens responsible for the observed Th1 immunophenotype remain elusive. The epidemiologic association with bioaerosols and the presence of granulomatous inflammation support consideration of mycobacterial antigens. To explore the role of mycobacterial antigens in sarcoidosis immunopathogenesis, we assessed the immune recognition of mycobacterial antigens, the 6-kDa early secreted antigenic protein (ESAT-6) and catalase-peroxidase (KatG), by T cells derived from bronchoalveolar lavage (BAL) fluid obtained during diagnostic bronchoscopy. We report the presence of antigen-specific recognition of ESAT-6 and KatG in T cells from BAL fluid of 32/44 sarcoidosis subjects, compared to 1/27 controls (P < 0.0001). CD4(+) T cells were primarily responsible for immune recognition (32/44 sarcoidosis subjects), although CD8(+) T-cell responses were observed (25/41 sarcoidosis subjects). Recognition was significantly absent from BAL fluid cells of patients with other lung diseases, including infectious granulomatous diseases. Blocking of Toll-like receptor 2 reduced the strength of the observed immune response. The presence of immune responses to mycobacterial antigens in cells from BAL fluid used for sarcoidosis diagnosis suggests a strong association between mycobacteria and sarcoidosis pathogenesis. Inhibition of immune recognition with monoclonal antibody against Toll-like receptor 2 suggests that induction of innate immunity by mycobacteria contributes to the polarized Th1 immune response.

SUBMITTER: Oswald-Richter KA

PROVIDER: S-EPMC2738026 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Cellular responses to mycobacterial antigens are present in bronchoalveolar lavage fluid used in the diagnosis of sarcoidosis.

Oswald-Richter Kyra A KA Culver Daniel A DA Hawkins Charlene C Hajizadeh Rana R Abraham Susamma S Shepherd Bryan E BE Jenkins Cathy A CA Judson Marc A MA Drake Wonder P WP

Infection and immunity 20090713 9

Considerable evidence supports the concept that CD4(+) T cells are important in sarcoidosis pathogenesis, but the antigens responsible for the observed Th1 immunophenotype remain elusive. The epidemiologic association with bioaerosols and the presence of granulomatous inflammation support consideration of mycobacterial antigens. To explore the role of mycobacterial antigens in sarcoidosis immunopathogenesis, we assessed the immune recognition of mycobacterial antigens, the 6-kDa early secreted a ...[more]

PMID: 19596780

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Project description:Background: Sarcoidosis and idiopathic pulmonary fibrosis (IPF) are two most frequent forms of interstitial lung diseases (ILDs). Cellular and biochemical composition of bronchoalveolar lavage fluid (BALf) was shown to reflect the proliferative and fibrotic changes in the local environment in the lung. However, the usefulness of BALf cellular profile evaluation in the diagnosis of ILDs is limited. The aim of the study was a multivariate, molecular, comparative analysis of BALf cells from IPF and sarcoidosis patients. Methods: Transcriptomic measurements were carried out using Affymetrix Human Gene 2.1 ST ArrayStrip in 21 samples: 9 IPF and 12 sarcoidosis. The mRNA expression for the most significantly differentiating genes was evaluated by real time PCR in 32 samples (11 IPF and 21 sarcoidosis). Results: The number of genes differentially expressed between IPF and sarcoidosis groups were 4832 (13359 probesets). Our cluster analysis indicated that sarcoidosis BALf cells are characterized by increased mRNA expression of genes associated with ribosome biogenesis, transcription machinery. Clusters formed by genes with changed mRNA expression in IPF samples were implicated in the processes of cell adhesion and migration, metalloproteinase expression and negative regulation of cell proliferation. PCR verification showed higher expression of ANK3 in the sarcoidosis compared to the IPF group, and higher expression of MMP7 and PPBP in patients with IPF. The GO analysis indicated that predominant biological processes associated with the differential mRNA gene expression of BALf cells were upregulation of neutrophils in IPF and lymphocytes in sarcoidosis. Conclusions: Analysis of BALf from sarcoidosis and IPF showed highly different mRNA profile of cells present in bronchoalveolar compartment and provided new data on the pathobiology of these ILDs. The changes of most important biological processes observed at the molecular level in BALf cells were associated with ribosome biogenesis and proteasome apparatus in sarcoidosis and neutrophilic dysfunction in IPF.

Project description:BackgroundSarcoidosis is a multisystem immuno-inflammatory disorder of unknown etiology that most commonly involves the lungs. We hypothesized that an unbiased approach to identify pathways activated in bronchoalveolar lavage (BAL) cells can shed light on the pathogenesis of this complex disease.MethodsWe recruited 15 patients with various stages of sarcoidosis and 12 healthy controls. All subjects underwent bronchoscopy with lavage. For each subject, total RNA was extracted from BAL cells and hybridized to an Affymetrix U133A microarray. Rigorous statistical methods were applied to identify differential gene expression between subjects with sarcoidosis vs.ControlsTo better elucidate pathways differentially activated between these groups, we integrated network and gene set enrichment analyses of BAL cell transcriptional profiles.ResultsSarcoidosis patients were either non-smokers or former smokers, all had lung involvement and only two were on systemic prednisone. Healthy controls were all non-smokers. Comparison of BAL cell gene expression between sarcoidosis and healthy subjects revealed over 1500 differentially expressed genes. Several previously described immune mediators, such as interferon gamma, were upregulated in the sarcoidosis subjects. Using an integrative computational approach we constructed a modular network of over 80 gene sets that were highly enriched in patients with sarcoidosis. Many of these pathways mapped to inflammatory and immune-related processes including adaptive immunity, T-cell signaling, graft vs. host disease, interleukin 12, 23 and 17 signaling. Additionally, we uncovered a close association between the proteasome machinery and adaptive immunity, highlighting a potentially important and targetable relationship in the pathobiology of sarcoidosis.ConclusionsBAL cells in sarcoidosis are characterized by enrichment of distinct transcriptional programs involved in immunity and proteasomal processes. Our findings add to the growing evidence implicating alveolar resident immune effector cells in the pathogenesis of sarcoidosis and identify specific pathways whose activation may modulate disease progression.

Project description:BackgroundIt is now possible to comprehensively characterize the microbiota of the lungs using culture-independent, sequencing-based assays. Several sample types have been used to investigate the lung microbiota, each presenting specific challenges for preparation and analysis of microbial communities. Bronchoalveolar lavage fluid (BALF) enables the identification of microbiota specific to the lower lung but commonly has low bacterial density, increasing the risk of false-positive signal from contaminating DNA. The objectives of this study were to investigate the extent of contamination across a range of sample densities representative of BALF and identify features of contaminants that facilitate their removal from sequence data and aid in the interpretation of BALF sample 16S sequencing data.ResultsUsing three mock communities across a range of densities ranging from 8E+?02 to 8E+?09 16S copies/ml, we assessed taxonomic accuracy and precision by 16S rRNA gene sequencing and the proportion of reads arising from contaminants. Sequencing accuracy, precision, and the relative abundance of mock community members decreased with sample input density, with a significant drop-off below 8E+?05 16S copies/ml. Contaminant OTUs were commonly inversely correlated with sample input density or not reproduced between technical replicates. Removal of taxa with these features or physical concentration of samples prior to sequencing improved both sequencing accuracy and precision for samples between 8E+?04 and 8E+?06 16S copies/ml. For the lowest densities, below 8E+?03 16S copies/ml BALF, accuracy and precision could not be significantly improved using these approaches. Using clinical BALF samples across a large density range, we observed that OTUs with features of contaminants identified in mock communities were also evident in low-density BALF samples.ConclusionRelative abundance data and community composition generated by 16S sequencing of BALF samples across the range of density commonly observed in this sample type should be interpreted in the context of input sample density and may be improved by simple pre- and post-sequencing steps for densities above 8E+?04 16S copies/ml.

Dataset Information

Cellular responses to mycobacterial antigens are present in bronchoalveolar lavage fluid used in the diagnosis of sarcoidosis.

Publications

Cellular responses to mycobacterial antigens are present in bronchoalveolar lavage fluid used in the diagnosis of sarcoidosis.

Similar Datasets

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