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The QTL within the H2 Complex Involved in the Control of Tuberculosis Infection in Mice Is the Classical Class II H2-Ab1 Gene.

Logunova N, Korotetskaya M, Polshakov V, Apt A - PLoS Genet. (2015)

Bottom Line: Cloning and sequencing of the H2j allelic variants of these genes demonstrated profound polymorphic variations compare to the H2b haplotype.These variations were sufficient to produce different TB-relevant phenotypes: the more susceptible B6.I-249.1.15.100 strain demonstrated shorter survival time, more rapid body weight loss, higher mycobacterial loads in the lungs and more severe lung histopathology compared to the more resistant B6.I-249.1.15.139 strain.CD4+ T cells recognized mycobacterial antigens exclusively in the context of the H2-A Class II molecule, and the level of IFN-γ-producing CD4+ T cells in the lungs was significantly higher in the resistant strain.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Immunogenetics, Central Institute for Tuberculosis, Moscow, Russia.

ABSTRACT
The level of susceptibility to tuberculosis (TB) infection depends upon allelic variations in numerous interacting genes. In our mouse model system, the whole-genome quantitative trait loci (QTLs) scan revealed three QTLs involved in TB control on chromosomes 3, 9, and in the vicinity of the H2 complex on chromosome 17. For the present study, we have established a panel of new congenic, MHC-recombinant mouse strains bearing differential small segments of chromosome 17 transferred from the TB-susceptible I/St (H2j) strain onto the genetic background of TB-resistant C57BL/6 (B6) mice (H2b). This allowed narrowing the QTL interval to 17Ch: 33, 77-34, 34 Mb, containing 36 protein-encoding genes. Cloning and sequencing of the H2j allelic variants of these genes demonstrated profound polymorphic variations compare to the H2b haplotype. In two recombinant strains, B6.I-249.1.15.100 and B6.I-249.1.15.139, recombination breakpoints occurred in different sites of the H2-Aβ 1 gene (beta-chain of the Class II heterodimer H2-A), providing polymorphic variations in the domain β1 of the Aβ-chain. These variations were sufficient to produce different TB-relevant phenotypes: the more susceptible B6.I-249.1.15.100 strain demonstrated shorter survival time, more rapid body weight loss, higher mycobacterial loads in the lungs and more severe lung histopathology compared to the more resistant B6.I-249.1.15.139 strain. CD4+ T cells recognized mycobacterial antigens exclusively in the context of the H2-A Class II molecule, and the level of IFN-γ-producing CD4+ T cells in the lungs was significantly higher in the resistant strain. Thus, we directly demonstrated for the first time that the classical H2- Ab1 Class II gene is involved in TB control. Molecular modeling of the H2-Aj product predicts that amino acid (AA) substitutions in the Aβ-chain modify the motif of the peptide-MHC binding groove. Moreover, unique AA substitutions in both α- and β-chains of the H2-Aj molecule might affect its interactions with the T-cell receptor (TCR).

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Possession of the H2-Ab1j-like alleles results in a more severe TB infectious course.A–Representative tuberculous lung lesions at day 35 post-infection. Hematoxylin and eosin staining, magnification x100. Arrows show granulomatous structures. B–TNF-α and IL-6 production in infected lungs at day 60 post-challenge. Whole-lung homogenates from individual mice (3 per group) were assessed in the ELISA format. The results are expressed as mean ± SD from two independent experiments (total N = 6), P < 0.05 for B6.I-100 and B6.I-139, ANOVA. C–The number of lung IFN-γ-producing CD4+ T cells was assessed by intracellular staining for IFN-γ at 35 days post-challenge. After culturing with mycobacterial sonicate, the lung cell population gated for CD3 expression was analyzed as displayed. Results of one of two similar experiments (total N = 6) are shown, with statistics for 3 individual mice per group provided in quadrants. In controls (cells from normal mice with mycobacterial sonicate, or cells from infected mice without antigen in culture) the per cent of IFN-γ-producing lung CD4+ T cells never exceed 0.1. P < 0.05 for B6.I-100 and B6.I-139, ANOVA.
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pgen.1005672.g005: Possession of the H2-Ab1j-like alleles results in a more severe TB infectious course.A–Representative tuberculous lung lesions at day 35 post-infection. Hematoxylin and eosin staining, magnification x100. Arrows show granulomatous structures. B–TNF-α and IL-6 production in infected lungs at day 60 post-challenge. Whole-lung homogenates from individual mice (3 per group) were assessed in the ELISA format. The results are expressed as mean ± SD from two independent experiments (total N = 6), P < 0.05 for B6.I-100 and B6.I-139, ANOVA. C–The number of lung IFN-γ-producing CD4+ T cells was assessed by intracellular staining for IFN-γ at 35 days post-challenge. After culturing with mycobacterial sonicate, the lung cell population gated for CD3 expression was analyzed as displayed. Results of one of two similar experiments (total N = 6) are shown, with statistics for 3 individual mice per group provided in quadrants. In controls (cells from normal mice with mycobacterial sonicate, or cells from infected mice without antigen in culture) the per cent of IFN-γ-producing lung CD4+ T cells never exceed 0.1. P < 0.05 for B6.I-100 and B6.I-139, ANOVA.

Mentions: We performed fine genetic mapping using the most integrative TB characteristics–survival curves, mycobacterial multiplication in the lungs, and body weight loss. Differences in the regulation of lung tissue inflammation after infection in B6 and I/St mice are of critical importance for TB pathogenesis [46, 47]. To characterize the influence of the H2-Ab1 polymorphism on TB-induced inflammation, we compared lung pathology 35 days post-infection in mice of both parental and new recombinant strains. As shown in Fig 5A, in B6 and B6.I-139 mice, lung pathology was represented by granulomatous areas well-delimited from the breathing tissue, whereas I/St and B6.I-100 mice developed diffuse TB pneumonia that was more severe in I/St mice.


The QTL within the H2 Complex Involved in the Control of Tuberculosis Infection in Mice Is the Classical Class II H2-Ab1 Gene.

Logunova N, Korotetskaya M, Polshakov V, Apt A - PLoS Genet. (2015)

Possession of the H2-Ab1j-like alleles results in a more severe TB infectious course.A–Representative tuberculous lung lesions at day 35 post-infection. Hematoxylin and eosin staining, magnification x100. Arrows show granulomatous structures. B–TNF-α and IL-6 production in infected lungs at day 60 post-challenge. Whole-lung homogenates from individual mice (3 per group) were assessed in the ELISA format. The results are expressed as mean ± SD from two independent experiments (total N = 6), P < 0.05 for B6.I-100 and B6.I-139, ANOVA. C–The number of lung IFN-γ-producing CD4+ T cells was assessed by intracellular staining for IFN-γ at 35 days post-challenge. After culturing with mycobacterial sonicate, the lung cell population gated for CD3 expression was analyzed as displayed. Results of one of two similar experiments (total N = 6) are shown, with statistics for 3 individual mice per group provided in quadrants. In controls (cells from normal mice with mycobacterial sonicate, or cells from infected mice without antigen in culture) the per cent of IFN-γ-producing lung CD4+ T cells never exceed 0.1. P < 0.05 for B6.I-100 and B6.I-139, ANOVA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664271&req=5

pgen.1005672.g005: Possession of the H2-Ab1j-like alleles results in a more severe TB infectious course.A–Representative tuberculous lung lesions at day 35 post-infection. Hematoxylin and eosin staining, magnification x100. Arrows show granulomatous structures. B–TNF-α and IL-6 production in infected lungs at day 60 post-challenge. Whole-lung homogenates from individual mice (3 per group) were assessed in the ELISA format. The results are expressed as mean ± SD from two independent experiments (total N = 6), P < 0.05 for B6.I-100 and B6.I-139, ANOVA. C–The number of lung IFN-γ-producing CD4+ T cells was assessed by intracellular staining for IFN-γ at 35 days post-challenge. After culturing with mycobacterial sonicate, the lung cell population gated for CD3 expression was analyzed as displayed. Results of one of two similar experiments (total N = 6) are shown, with statistics for 3 individual mice per group provided in quadrants. In controls (cells from normal mice with mycobacterial sonicate, or cells from infected mice without antigen in culture) the per cent of IFN-γ-producing lung CD4+ T cells never exceed 0.1. P < 0.05 for B6.I-100 and B6.I-139, ANOVA.
Mentions: We performed fine genetic mapping using the most integrative TB characteristics–survival curves, mycobacterial multiplication in the lungs, and body weight loss. Differences in the regulation of lung tissue inflammation after infection in B6 and I/St mice are of critical importance for TB pathogenesis [46, 47]. To characterize the influence of the H2-Ab1 polymorphism on TB-induced inflammation, we compared lung pathology 35 days post-infection in mice of both parental and new recombinant strains. As shown in Fig 5A, in B6 and B6.I-139 mice, lung pathology was represented by granulomatous areas well-delimited from the breathing tissue, whereas I/St and B6.I-100 mice developed diffuse TB pneumonia that was more severe in I/St mice.

Bottom Line: Cloning and sequencing of the H2j allelic variants of these genes demonstrated profound polymorphic variations compare to the H2b haplotype.These variations were sufficient to produce different TB-relevant phenotypes: the more susceptible B6.I-249.1.15.100 strain demonstrated shorter survival time, more rapid body weight loss, higher mycobacterial loads in the lungs and more severe lung histopathology compared to the more resistant B6.I-249.1.15.139 strain.CD4+ T cells recognized mycobacterial antigens exclusively in the context of the H2-A Class II molecule, and the level of IFN-γ-producing CD4+ T cells in the lungs was significantly higher in the resistant strain.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Immunogenetics, Central Institute for Tuberculosis, Moscow, Russia.

ABSTRACT
The level of susceptibility to tuberculosis (TB) infection depends upon allelic variations in numerous interacting genes. In our mouse model system, the whole-genome quantitative trait loci (QTLs) scan revealed three QTLs involved in TB control on chromosomes 3, 9, and in the vicinity of the H2 complex on chromosome 17. For the present study, we have established a panel of new congenic, MHC-recombinant mouse strains bearing differential small segments of chromosome 17 transferred from the TB-susceptible I/St (H2j) strain onto the genetic background of TB-resistant C57BL/6 (B6) mice (H2b). This allowed narrowing the QTL interval to 17Ch: 33, 77-34, 34 Mb, containing 36 protein-encoding genes. Cloning and sequencing of the H2j allelic variants of these genes demonstrated profound polymorphic variations compare to the H2b haplotype. In two recombinant strains, B6.I-249.1.15.100 and B6.I-249.1.15.139, recombination breakpoints occurred in different sites of the H2-Aβ 1 gene (beta-chain of the Class II heterodimer H2-A), providing polymorphic variations in the domain β1 of the Aβ-chain. These variations were sufficient to produce different TB-relevant phenotypes: the more susceptible B6.I-249.1.15.100 strain demonstrated shorter survival time, more rapid body weight loss, higher mycobacterial loads in the lungs and more severe lung histopathology compared to the more resistant B6.I-249.1.15.139 strain. CD4+ T cells recognized mycobacterial antigens exclusively in the context of the H2-A Class II molecule, and the level of IFN-γ-producing CD4+ T cells in the lungs was significantly higher in the resistant strain. Thus, we directly demonstrated for the first time that the classical H2- Ab1 Class II gene is involved in TB control. Molecular modeling of the H2-Aj product predicts that amino acid (AA) substitutions in the Aβ-chain modify the motif of the peptide-MHC binding groove. Moreover, unique AA substitutions in both α- and β-chains of the H2-Aj molecule might affect its interactions with the T-cell receptor (TCR).

Show MeSH
Related in: MedlinePlus