Tubercle and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease最新文献

The expression of transforming growth factor (TGF-β1), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and interleukin-4 (IL-4) were assessed in lung tissues from patients with tuberculosis. Vimentin, a constitutively expressed cellular protein, was present in 12 of 19 tissue sections indicating adequate preservation of tissue proteins in these cases. Immunohistochemical studies for cytokines were done in the vimentin positive sections only. TGF-β1 was localized to mononuclear phagocytes of tuberculous lung lesions in 4 of 12 tuberculosis patients. TNF-α, IFN-γ, and IL-4 were absent in sections from all tuberculosis patients. The failure to detect the latter cytokines may indicate that these molecules may not be expressed at the site of disease, or are not a feature of the late stages of tuberculous granulomas. TGFβ -1, although not universally expressed, may be involved in the development and/or consequences of tuberculous granuloma formation. These data substantiate further the role of TGF-β1 in the immunopathology of tuberculosis.

Objective: During the follow-up of a group of patients with active tuberculosis, the predictive potential of several antibody-based assays was evaluated in monitoring treatment efficacy.

Design: Eleven patients with bacteriologically documented pulmonary tuberculosis and two patients with tuberculosis pleurisy were studied over a period of 6 months, from the day before treatment to its completion. The kinetics of the humoral response to Mycobacterium tuberculosis was determined by the number of specific circulating antibody secreting cells (ASC) (ELISPOT assay), as well as the titres of specific circulating antibody and specific antibody present in circulating immune complexes (quantitative ELISA).

Results: Follow-up ELISPOT assays, performed after initiation of tuberculosis therapy showed a rapid increase of ASC, during the first week, followed by rapid 3–10 fold decline of ASC in 12 of 13 patients tested. This decline occurred more rapidly than the mycobacterial culture conversion. In contrast, follow-up of ELISA assays did not give relevant information in assessing the outcome of treatment.

Conclusion: In comparison with direct detection of tubercle bacilli in sputum samples, the rapid clearance of specific circulating ASC occuring early on after the onset of therapy could suggest a potential usefulness of ELISPOT in monitoring therapeutic response.

Nucleotide sequences of domain V and domain II regions of the 23S rRNA gene were determined in both in vitro-made mutants and clinical isolates of Mycobacterium avium and M. intracellulare conferring clarithromycin-resistance. All laboratory-made mutants showed high level resistance to clarithromycin (⪢150 μg ml⁻¹) and mutation at position 2058 (cognate with Escherichia coli base) in domain V region. In the clinical isolates, while the susceptible ones had no mutation in domain V, the resistant strains showed mutation at 2058 or 2059. Six isolates with low level of resistance exhibited no mutation in domain V. All strains tested had no mutation in domain II region. These results suggested that most of the resistance arose from the mutation in domain V of the 23S rRNA gene, but other unknown mechanisms evidently exist in mycobacteria.

Objective: To determine whether synthetic peptides containing an amino terminal formyl-methionine residue and corresponding to the sequence of several proteins produced by Mycobacterium tuberculosis, would elicit an immune response in mice.

Design: Peptides corresponding to the amino termini of 8 M. tuberculosis proteins and initiating with formyl methionine residues were synthesized. The ability of these peptides to bind to the mouse non-classical MHC class I molecule H-2M3^awas determined by flow microfluorimetry. These peptides were used to pulse dendritic cells that were then injected into normal mice. These mice were subsequently challenged with aerosolized M. tuberculosis and, 30 days later, the number of viable bacteria in the lungs was determined.

Results: Four of the 8 synthetic peptides bound to H-2M3^aand stabilized its expression on the cell surface. Injection of mice with dendritic cells pulsed with H-2M3^abinding peptides elicited non-MHC restricted cytotoxic T lymphocytes that killed peptide pulsed target cells and macrophages infected with M. tuberculosis. Immunization of mice with syngeneic dendritic cells pulsed in vitro with 2 of these peptides led to retardation of the growth of M. tuberculosis following aerosol challenge.

Conclusion: Peptides that bind to non-polymorphic class I molecules can elicit immune reactivity directed towards M. tuberculosis.

Setting: The availability and appropriate use of animal models is of significant importance for a better and more detailed understanding of the genetic, immunological and pathological mechanisms underlying the development of mycobacterial disease in humans.

Objective: To define a mouse model for tuberculosis severity that can be easily adapted to genetic and immunological analysis of host repsonse to Mycobacterium tuberculosis infection.

Design: We describe here two inbred strains of mice, I/St and A/Sn (both Nramp1'), that differ vastly in commonly used parameters of susceptibility to infection with virulent and attenuated strains of M. tuberculosis.

Results: Following infection with a high dose of virulent H37Rv. M. tuberculosis and compared to their resistant A/Sn counterparts, I/St mice displayed more than a 2–fold shorter mean survival time and a more rapid onset and progression of severe body weight loss (cachexia). Moreover, I/St mice supported 20-100-fold higher multiplication of M. tuberculosis following challenge with H37Rv over a large range of infectious inocula.

The high susceptibility of I/St mice was also reflected by more severe lung histopathology as evidenced by larger and more numerous lung granuloma and macrophage dominated cellular infiltrates. Finally, we determined that I/St are also unable to control infection with attenuated H37Ra M. tuberculosis and two strains of M. bovis (BCG and Ravenel) indicating hyper-susceptibility of the I/St mouse strain to mycobacterial infections.

Conclusions: The results of our experiments suggest that comparative analysis of resistant A/Sn and susceptible I/St mice provides an ideal way to study host dependent aspects of tuberculosis susceptibility under the controlled conditions provided by an animal model.

We are interested in identifying a suitable model for investigating mycobacteria interactions with alveolar macrophages. MH-S, a murine alveolar macrophage cell line, is a possible candidate.

Objective: To compare the receptor mediated interactions of mycobacteria with primary murine macrophages and MH-S.

Design: The association of MH-S monolayers with Mycobacterium tuberculosis (MTB) and other defined particles was compared to that of resident Day 1 peritoneal macrophage (PM) and Day 4 alveolar macrophage (AM) monolayers.

Results: In the absence of serum, the association of MTB with MH-S was comparable to that of AM, with approximately 35% of each macrophage type binding at least one bacterium. In contrast, almost 80% of PM bound at least one bacterium. MTB binding was enhanced for all macrophage types by a heat-labile component of normal mouse serum. Antibodies recognising CR3 inhibited the serum-mediated enhanced binding of MTB by MH-S. Binding of latex, immunoglobulin coated or complement coated SRBC by MH-S, AM and PM was comparable. Binding of zymosan by MH-S was greatly inferior to AM and PM.

Conclusion: The receptor expression and particle binding properties of MH-S are similar to AM in many, but not all, ways. MH-S, therefore, has the potential to be used as a model for investigating MTB-macrophage interactions.

Genotypic analysis of isoniazid (INH) resistance in 79 isolates of M. tuberculosis (MTB) was undertaken by PCR-single strand conformation polymorphism (SSCP), Msp1 restriction enzyme analysis and sequence analysis of specific regions of three genes (part of the coding sequence of katG, and promoter regions of the inhA operon andahpC ) in order to determine the particular allelic variants within these genes. The epidemiologic relatedness was determined using IS6110 and polymorphic G-C region (PGRS (MTB484(1)) based restriction fragment length polymorphism (RFLP). Mutations in katG, inhA locus and ahpC were identified in 77/79, 19/79 and 10/79 isolates respectively. The ability of PCR–SSCP to detect mutations associated with INH resistance in katG, inhA andahpC genes was 100% (CI 91.2–99.7%), 98.7% (CI 74.0–99.9%), and 100% (CI 69.2–100%) respectively. Specificity was 100%. All isolates with mutations in the 209bp fragment of the MTBkatG gene containing the Ser315Thr codon were positive by PCR-RFLP using Msp1 enzyme restriction analysis. Sixteen of 19 isolates with alterations on the 3′ end of the ribosome binding site upstream of mabA in inhA locus simultaneously harbored Ser315Thr mutations in KatG. In 9/10 isolates, mutations in the ahpC promoter region were located in the 105bp oxyR-ahpC intergenic region. None of 17 INH drug susceptible isolates harbored mutations in any of the three genetic regions, although the katG1 allele (Arg 463 Leu) was present in one isolate. Characterization by IS6110/PGRS(MTB484(1))RFLP analysis revealed that a number of drug resistant clones are widespread in the community. We conclude that the frequency of the Ser315Thr katG mutation in the local strain population makes the PCR-RFLP MTBkatG assay a reliable, rapid and useful method for detecting INH resistance.

In order to determine the current situation and to evaluate the human to human transmission ofMycobacterium tuberculosis in Northern France, the genetic polymorphism of strains was studied by using IS 6110 fingerprint. One hundred and fifty-eight cases of bacteriologically confirmed tuberculosis were analyzed. One hundred and twenty-six patients (82%) were infected with genetically different isolates and 28 isolates (18%) were grouped into 14 clusters. No risk factors for recent Mycobacterium tuberculosis infections such as age, HIV status, immigrants, living in big cities were identified. This study shows that there was no major epidemic situation of tuberculosis in Northern France in 1995. Tuberculosis was characterized by a low proportion of HIV positive patients and a high proportion of elderly patients.