1,720,973 research outputs found
PE_PGRS3: a new player inMycobacterium tuberculosispathogenesis
Full text linkTheM. tuberculosis(Mtb) genome contains around 60 pe_pgrs genes, whose role and function remain elusive. In this study, two PE_PGRS proteins with high sequence homology were selected and investigated (PE_PGRS3 and PE_PGRS4), with PE_PGRS3 characterized by the presence of a C-terminal domain rich in arginine. Interestingly, full-length PE_PGRS3 protein is expressed by Mtb strains but not by other MTBC subspecies causing disease in animals. A gene reporter system was developed to investigate inM. smegmatis(Msm) the expression pattern of these genes. Fluorescence microscopy, FACS and transcriptional analysis indicated that the two genes are differentially regulated, with pe_pgrs3 but not pe_pgrs4 being expressed only when mycobacteria are cultivated in low inorganic phosphate (iPhos). Expression of pe_pgrs3 in low iPhos correlated with the upregulation of relA in Msm recombinant strains and Mtb, suggesting that pe_pgrs3 is involved in the stringent response. Overexpression of the PE_PGRS3, and of its functional deletion mutant (PE_PGRS3ΔCt), in Msm were obtained by expressing these genes under control of hbhA promoter. Interestingly, Msm strains overexpressing PE_PGRS3 showed enhanced ability to entry in macrophages and epithelial cells compared to Msm expressing PE_PGRS3ΔCt or Msm parental strain. No differences in the ability of these strains to survive intracellularly were measured. These results provide new insights on the role of PE_PGRS3 in TB pathogenesis
Serum CK18 as a Predictive Factor of Response to Chemotherapy in Locally Advanced and Metastatic Breast Cancer
No full textLack of Response to HBHA in HIV-Infected Patients with Latent Tuberculosis Infection
No full textHeparin-binding haemagglutinin (HBHA) has been proposed as an immunological biomarker for discriminating active tuberculosis (TB) from latent TB infection (LTBI) and to identify those at higher risk of progressing to active disease. Few data are available in immune-compromised patients, which are those with increased risk of TB reactivation. The aim of this stusy was to evaluate the immune response to HBHA in HIV-infected subjects with LTBI (HIV-LTBI) or active TB (HIV-TB) in comparison with the immune response to additional Mycobacterium tuberculosis (Mtb) or HIV and CMV antigens. The responses are evaluated in relation to TB status and in the LTBI subjects with the progression to active TB within 2 years. Forty-one HIV-infected antiretroviral-naïve subjects were prospectively enrolled: 18 were HIV-TB and 23 HIV-LTBI. Whole blood was in vitro stimulated overnight with several antigens and mitogen. Interferon-γ response in the harvested plasma was evaluated by ELISA. Despite that CD4 cell count was significantly different between HIV-LTBI and HIV-TB, no differences were observed in response to Mtb- or HIV-specific antigens. Differently, low responses to HBHA were observed in both HIV-LTBI and HIV-TB subjects. Importantly, none of the six HIV-LTBI responding to HBHA developed TB, while two of 17 non-HBHA responders developed active disease. HIV-TB-coinfected subjects, regardless of their TB status, showed low responses to HBHA despite maintaining detectable responses to other antigens; moreover, among the HIV-LTBI, the lack of HBHA responses indicated an increased risk to develop active TB. These results, although preliminary, suggest that a positive response to HBHA in HIV-LTBI correlates with Mtb containment
PE_PGRS3: a new player in <i>Mycobacterium tuberculosis</i> pathogenesis
Full text linkThe M. tuberculosis (Mtb) genome contains around 60 pe_pgrs genes, whose role and function remain elusive. In this study, two PE_PGRS proteins with high sequence homology were selected and investigated (PE_PGRS3 and PE_PGRS4), with PE_PGRS3 characterized by the presence of a C-terminal domain rich in arginine. Interestingly, full-length PE_PGRS3 protein is expressed by Mtb strains but not by other MTBC subspecies causing disease in animals. A gene reporter system was developed to investigate in M. smegmatis (Msm) the expression pattern of these genes. Fluorescence microscopy, FACS and transcriptional analysis indicated that the two genes are differentially regulated, with pe_pgrs3 but not pe_pgrs4 being expressed only when mycobacteria are cultivated in low inorganic phosphate (iPhos). Expression of pe_pgrs3 in low iPhos correlated with the upregulation of relA in Msm recombinant strains and Mtb, suggesting that pe_pgrs3 is involved in the stringent response. Overexpression of the PE_PGRS3, and of its functional deletion mutant (PE_PGRS3ΔCt), in Msm were obtained by expressing these genes under control of hbhA promoter. Interestingly, Msm strains overexpressing PE_PGRS3 showed enhanced ability to entry in macrophages and epithelial cells compared to Msm expressing PE_PGRS3ΔCt or Msm parental strain. No differences in the ability of these strains to survive intracellularly were measured. These results provide new insights on the role of PE_PGRS3 in TB pathogenesis
Combined use of Quantiferon and HBHA-based IGRA supports tuberculosis diagnosis and therapy management in children
No full textObjectives: Interferon-γ release assays (IGRA) are designed for diagnosis of tuberculosis (TB) infection, and do not discriminate latent TB infection (LTBI) from active TB. Heparin-binding hemagglutinin antigen (HBHA) emerged as a promising antigen for TB diagnosis when used in IGRA format. Aim of this study was to prospectively evaluate the performance of an HBHA-based IGRA to support TB diagnosis and TB therapy monitoring in children with TB infection or active TB disease. Methods: Following clinical, microbiological and radiological assessment, children (0–14 years old) were tested by the QuantiFERON TB-Gold In tube (QFT) assay and an aliquot of whole-blood was stimulated with HBHA and IFNγ evaluated only in QFT-positive subjects. Results: Among the 550 children tested, 486 (88.4%) scored negative and 64 (11.6%) positive. None of the QFT-negative had active TB. Among the QFT-positive, 45 were with LTBI and 19 active TB. HBHA-IGRA scored positive in 41/45 children (91.1%) with LTBI and in 6/19 active TB children (31.6%) at diagnosis (p = 0.001); remarkably, 5 of these 6 children with active TB scoring HBHA-positive were asymptomatic. Moreover, following TB-specific therapy, most of the non-HBHA-responding children, gained an HBHA-positive response. Conclusions: HBHA-based IGRA is a useful support in TB diagnosis and TB-therapy monitoring in children
Lack of Response to HBHA in HIV-Infected Patients with Latent Tuberculosis Infection
No full textHeparin-binding haemagglutinin (HBHA) has been proposed as an immunological biomarker for discriminating active tuberculosis (TB) from latent TB infection (LTBI) and to identify those at higher risk of progressing to active disease. Few data are available in immune-compromised patients, which are those with increased risk of TB reactivation. The aim of this stusy was to evaluate the immune response to HBHA in HIV-infected subjects with LTBI (HIV-LTBI) or active TB (HIV-TB) in comparison with the immune response to additional Mycobacterium tuberculosis (Mtb) or HIV and CMV antigens. The responses are evaluated in relation to TB status and in the LTBI subjects with the progression to active TB within 2 years. Forty-one HIV-infected antiretroviral-naïve subjects were prospectively enrolled: 18 were HIV-TB and 23 HIV-LTBI. Whole blood was in vitro stimulated overnight with several antigens and mitogen. Interferon-γ response in the harvested plasma was evaluated by ELISA. Despite that CD4 cell count was significantly different between HIV-LTBI and HIV-TB, no differences were observed in response to Mtb- or HIV-specific antigens. Differently, low responses to HBHA were observed in both HIV-LTBI and HIV-TB subjects. Importantly, none of the six HIV-LTBI responding to HBHA developed TB, while two of 17 non-HBHA responders developed active disease. HIV-TB-coinfected subjects, regardless of their TB status, showed low responses to HBHA despite maintaining detectable responses to other antigens; moreover, among the HIV-LTBI, the lack of HBHA responses indicated an increased risk to develop active TB. These results, although preliminary, suggest that a positive response to HBHA in HIV-LTBI correlates with Mtb containment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evaluation of PE_PGRS33 as a potential surface target for humoral responses against Mycobacterium tuberculosis
No full textMycobacterium tuberculosis (Mtb) PE_PGRS33 is a surface-exposed protein that was shown to interact with Toll-like receptor 2 on host macrophages to induce inflammatory signals and promote entry in macrophages. In this study, we investigated PE_PGRS33 as a potential target of a humoral response aimed at hampering key processes in tuberculosis pathogenesis. PE_PGRS33 protein was successfully expressed and purified under native condition in Escherichia coli. The purified protein retained its native functional and biological properties, showing the ability to elicit proinflammatory signals in murine and human macrophages. Interestingly, a polyclonal antiserum raised against native PE_PGRS33 showed no cross-reactions with other mycobacterial proteins. The anti-PE_PGRS33 serum was also able to inhibit Mtb entry into macrophages, but it did not reduce entry of the MtbΔpe_pgrs33 strain. Addition of native recombinant PE_PGRS33 to the MtbΔpe_pgrs33 strain during infection restored the Mtb wild-type entry phenotype in macrophage. Moreover, the anti-PE_PGRS33 serum was able to neutralize the proinflammatory activity of PE_PGRS33 in vitro. Furthermore, mice immunized with native recombinant PE_PGRS33, but not with a DNA vaccine expressing PE_PGRS33, were able to restrict M. smegmatis in vivo. These results highlight the potential use of PE_PGRS33 as a target of a neutralizing humoral response against tuberculosis
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