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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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Genotypes and TB phenotypes of new recombinant mouse strains B6.I-100 and B6.I-139.A–The genome chart for B6.I-100 and B6.I-139 recombinant strains. Chromosome segments transferred from I/St onto B6 genetic background are shown in grey. B–survival curves of B6.I-100, B6.I-139 and parental strains mice after aerosol challenge with ~500 CFU of M. tuberculosis. MST ± SEM (days): B6 = 249 ± 10; I/St = 63 ± 11; B6.I-100 = 152 ± 13; B6.I-139 = 233 ± 14; B6.I-249.1.15.46 = 153 ± 11. Recombinant strains were tested in 3–5 independent experiments (total N = 20–40 males). Summary of 3 experiments is displayed (Kaplan-Meier survival analysis). C–CFU counts in infected lungs at days 28 and 70 post-challenge (4 mice per group, **P < 0.05, ANOVA). The representative results of one out of 2 independent experiments are present. D–genes and their positions in the D17Mit21 – H2-Ea interval according to Ensembl. Red borders–location of the candidate gene.
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pgen.1005672.g003: Genotypes and TB phenotypes of new recombinant mouse strains B6.I-100 and B6.I-139.A–The genome chart for B6.I-100 and B6.I-139 recombinant strains. Chromosome segments transferred from I/St onto B6 genetic background are shown in grey. B–survival curves of B6.I-100, B6.I-139 and parental strains mice after aerosol challenge with ~500 CFU of M. tuberculosis. MST ± SEM (days): B6 = 249 ± 10; I/St = 63 ± 11; B6.I-100 = 152 ± 13; B6.I-139 = 233 ± 14; B6.I-249.1.15.46 = 153 ± 11. Recombinant strains were tested in 3–5 independent experiments (total N = 20–40 males). Summary of 3 experiments is displayed (Kaplan-Meier survival analysis). C–CFU counts in infected lungs at days 28 and 70 post-challenge (4 mice per group, **P < 0.05, ANOVA). The representative results of one out of 2 independent experiments are present. D–genes and their positions in the D17Mit21 – H2-Ea interval according to Ensembl. Red borders–location of the candidate gene.

Mentions: To search for new recombination events inside the region 33, 77–34, 34 Mb, we performed several crosses between novel recombinant and B6 mice. In particular, the F2 progeny of (B6.I-249.1.15 x B6) F1 mice was used to develop a new set of congenic strains. In two new recombinant strains, B6.I-249.1.15.100 (hereafter–B6.I-100) and B6.I-249.1.15.139 (hereafter–B6.I-139), standard genotyping identified the point of recombination between markers D17Mit21 and D17Mit22 (Fig 3A). Surprisingly, these strains demonstrated sharply contrasting TB phenotypes (Fig 3B). After aerosol challenge, B6.I-139 mice did not differ by survival time from parental B6 mice (mean survival time (MST) = 238.9 ± 13.41 and 249 ± 10.21 days, respectively, P > 0.5). B6.I-100 mice did not differ from the B6.I -249.1.15.46 strain (MST 152 ± 13.3 and 153 ± 10.97 days, respectively, P > 0.5), but did differ significantly from the B6.I-139 strain (P < 0.001). Phenotypic differences were confirmed by evaluation of cachexia dynamics (S2 Fig), and by assessment of mycobacterial loads in the lungs at weeks 4 and 10 post-challenge (Fig 3C). Annotation in the http://www.ensembl.org database provides the length of 98, 588bp for the genomic region between D17Mit21 and D17Mit22, which contains only 5 protein-coding genes, 2 lincRNA genes and no genes for micro-RNAs (Fig 3D).


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)

Genotypes and TB phenotypes of new recombinant mouse strains B6.I-100 and B6.I-139.A–The genome chart for B6.I-100 and B6.I-139 recombinant strains. Chromosome segments transferred from I/St onto B6 genetic background are shown in grey. B–survival curves of B6.I-100, B6.I-139 and parental strains mice after aerosol challenge with ~500 CFU of M. tuberculosis. MST ± SEM (days): B6 = 249 ± 10; I/St = 63 ± 11; B6.I-100 = 152 ± 13; B6.I-139 = 233 ± 14; B6.I-249.1.15.46 = 153 ± 11. Recombinant strains were tested in 3–5 independent experiments (total N = 20–40 males). Summary of 3 experiments is displayed (Kaplan-Meier survival analysis). C–CFU counts in infected lungs at days 28 and 70 post-challenge (4 mice per group, **P < 0.05, ANOVA). The representative results of one out of 2 independent experiments are present. D–genes and their positions in the D17Mit21 – H2-Ea interval according to Ensembl. Red borders–location of the candidate gene.
© Copyright Policy
Related In: Results  -  Collection

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

pgen.1005672.g003: Genotypes and TB phenotypes of new recombinant mouse strains B6.I-100 and B6.I-139.A–The genome chart for B6.I-100 and B6.I-139 recombinant strains. Chromosome segments transferred from I/St onto B6 genetic background are shown in grey. B–survival curves of B6.I-100, B6.I-139 and parental strains mice after aerosol challenge with ~500 CFU of M. tuberculosis. MST ± SEM (days): B6 = 249 ± 10; I/St = 63 ± 11; B6.I-100 = 152 ± 13; B6.I-139 = 233 ± 14; B6.I-249.1.15.46 = 153 ± 11. Recombinant strains were tested in 3–5 independent experiments (total N = 20–40 males). Summary of 3 experiments is displayed (Kaplan-Meier survival analysis). C–CFU counts in infected lungs at days 28 and 70 post-challenge (4 mice per group, **P < 0.05, ANOVA). The representative results of one out of 2 independent experiments are present. D–genes and their positions in the D17Mit21 – H2-Ea interval according to Ensembl. Red borders–location of the candidate gene.
Mentions: To search for new recombination events inside the region 33, 77–34, 34 Mb, we performed several crosses between novel recombinant and B6 mice. In particular, the F2 progeny of (B6.I-249.1.15 x B6) F1 mice was used to develop a new set of congenic strains. In two new recombinant strains, B6.I-249.1.15.100 (hereafter–B6.I-100) and B6.I-249.1.15.139 (hereafter–B6.I-139), standard genotyping identified the point of recombination between markers D17Mit21 and D17Mit22 (Fig 3A). Surprisingly, these strains demonstrated sharply contrasting TB phenotypes (Fig 3B). After aerosol challenge, B6.I-139 mice did not differ by survival time from parental B6 mice (mean survival time (MST) = 238.9 ± 13.41 and 249 ± 10.21 days, respectively, P > 0.5). B6.I-100 mice did not differ from the B6.I -249.1.15.46 strain (MST 152 ± 13.3 and 153 ± 10.97 days, respectively, P > 0.5), but did differ significantly from the B6.I-139 strain (P < 0.001). Phenotypic differences were confirmed by evaluation of cachexia dynamics (S2 Fig), and by assessment of mycobacterial loads in the lungs at weeks 4 and 10 post-challenge (Fig 3C). Annotation in the http://www.ensembl.org database provides the length of 98, 588bp for the genomic region between D17Mit21 and D17Mit22, which contains only 5 protein-coding genes, 2 lincRNA genes and no genes for micro-RNAs (Fig 3D).

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