RESUMO
Early diagnosis of leprosy is challenging, particularly its inflammatory reactions, the major cause of irreversible neuropathy in leprosy. Current diagnostics cannot identify which patients are at risk of developing reactions. This study assessed blood RNA expression levels as potential biomarkers for leprosy. Prospective cohorts of newly diagnosed leprosy patients, including reactions, and healthy controls were recruited in Bangladesh, Brazil, Ethiopia and Nepal. RNA expression in 1,090 whole blood samples was determined for 103 target genes for innate and adaptive immune profiling by dual color Reverse-Transcription Multiplex Ligation-dependent Probe Amplification (dcRT-MLPA) followed by cluster analysis. We identified transcriptomic biomarkers associated with leprosy disease, different leprosy phenotypes as well as high exposure to Mycobacterium leprae which respectively allow improved diagnosis and classification of leprosy patients and detection of infection. Importantly, a transcriptomic signature of risk for reversal reactions consisting of five genes (CCL2, CD8A, IL2, IL15 and MARCO) was identified based on cross-sectional comparison of RNA expression. In addition, intra-individual longitudinal analyses of leprosy patients before, during and after treatment of reversal reactions, indicated that several IFN-induced genes increased significantly at onset of reaction whereas IL15 decreased. This multi-site study, situated in four leprosy endemic areas, demonstrates the potential of host transcriptomic biomarkers as correlates of risk for leprosy. Importantly, a prospective five-gene signature for reversal reactions could predict reversal reactions at least 2 weeks before onset. Thus, transcriptomic biomarkers provide promise for early detection of these acute inflammatory episodes and thereby help prevent permanent neuropathy and disability in leprosy patients.
Assuntos
Hanseníase/genética , Transcriptoma , Adolescente , Adulto , Bangladesh/epidemiologia , Biomarcadores/sangue , Brasil/epidemiologia , Etiópia/epidemiologia , Feminino , Humanos , Hanseníase/sangue , Hanseníase/epidemiologia , Masculino , Mycobacterium leprae/isolamento & purificação , Nepal/epidemiologia , Países Baixos/epidemiologia , Prognóstico , Estudos Prospectivos , Adulto JovemRESUMO
Leprosy presents as a clinical and immunological spectrum of disease. With the use of gene expression profiling, we observed that a distinction in gene expression correlates with and accurately classifies the clinical form of the disease. Genes belonging to the leukocyte immunoglobulin-like receptor (LIR) family were significantly up-regulated in lesions of lepromatous patients suffering from the disseminated form of the infection. In functional studies, LIR-7 suppressed innate host defense mechanisms by shifting monocyte production from interleukin-12 toward interleukin-10 and by blocking antimicrobial activity triggered by Toll-like receptors. Gene expression profiles may be useful in defining clinical forms of disease and providing insights into the regulation of immune responses to pathogens.
Assuntos
Humanos , Análise por Conglomerados , Citocinas/genética , Citocinas/metabolismo , Contagem de Colônia Microbiana , Glicoproteínas de Membrana/imunologia , Hanseníase Tuberculoide/classificação , Hanseníase Tuberculoide/fisiopatologia , Hanseníase Tuberculoide/genética , Hanseníase Tuberculoide/imunologia , Hanseníase Virchowiana/classificação , Hanseníase Virchowiana/fisiopatologia , Hanseníase Virchowiana/genética , Hanseníase Virchowiana/imunologia , Imunidade Celular , Imunidade Inata , Macrófagos Alveolares/microbiologia , Mycobacterium tuberculosis/crescimento & desenvolvimento , Mycobacterium tuberculosis/imunologia , Perfilação da Expressão Gênica , Reação em Cadeia da Polimerase , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo , Receptores de Superfície Celular/imunologia , Regulação da Expressão Gênica , Algoritmos , Análise de Componente Principal , Análise de Sequência com Séries de Oligonucleotídeos , Genes de Imunoglobulinas , Regulação para CimaRESUMO
Nerve damage is a clinical hallmark of leprosy and a major source of patient morbidity. We investigated the possibility that human Schwann cells are susceptible to cell death through the activation of Toll-like receptor 2 (TLR2), a pattern recognition receptor of the innate immune system. TLR2 was detected on the surface of human Schwann cell line ST88-14 and on cultured primary human Schwann cells. Activation of the human Schwann cell line and primary human Schwann cell cultures with a TLR2 agonist, a synthetic lipopeptide comprising the N-terminal portion of the putative Mycobacterium leprae 19-kDa lipoprotein, triggered an increase in the number of apoptotic cells. The lipopeptide-induced apoptosis of Schwann cells could be blocked by an anti-TLR2 monoclonal antibody. Schwann cells in skin lesions from leprosy patients were found to express TLR2. It was possible to identify in the lesions Schwann cells that had undergone apoptosis in vivo. The ability of M. leprae ligands to induce the apoptosis of Schwann cells through TLR2 provides a mechanism by which activation of the innate immune response contributes to nerve injury in leprosy.
Assuntos
Humanos , Apoptose , Células Cultivadas , Células de Schwann/patologia , Dano ao DNA , Glicoproteínas de Membrana/análise , Glicoproteínas de Membrana/fisiologia , Hanseníase/imunologia , Hanseníase/patologia , Imunidade Inata , Lipoproteínas/fisiologia , Receptores de Superfície Celular/análise , Receptores de Superfície Celular/fisiologiaRESUMO
The expression and activation of Toll-like receptors (TLRs) was investigated in leprosy, a spectral disease in which clinical manifestations correlate with the type of immune response mounted toward Mycobacterium leprae. TLR2-TLR1 heterodimers mediated cell activation by killed M. leprae, indicating the presence of triacylated lipoproteins. A genome-wide scan of M. leprae detected 31 putative lipoproteins. Synthetic lipopeptides representing the 19-kD and 33-kD lipoproteins activated both monocytes and dendritic cells. Activation was enhanced by type-1 cytokines and inhibited by type-2 cytokines. In addition, interferon (IFN)-gamma and granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced TLR1 expression in monocytes and dendritic cells, respectively, whereas IL-4 downregulated TLR2 expression. TLR2 and TLR1 were more strongly expressed in lesions from the localized tuberculoid form (T-lep) as compared with the disseminated lepromatous form (L-lep) of the disease. These data provide evidence that regulated expression and activation of TLRs at the site of disease contribute to the host defense against microbial pathogens.