A S Apt

Central Research Institute of Epidemiology, Moskva, Moscow, Russia

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Publications (93)194.16 Total impact

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    ABSTRACT: About 90% of all cases of tuberculosis (TB) infection are comprised of latent mycobacterial persistence in the absence of clinical manifestations. In a proportion of latently infected individuals infection eventually reactivates and becomes contagious, seriously influencing epidemiological situation. Mechanisms of Mycobacterium tuberculosis transition to dormancy and TB reactivation are poorly understood, and biological markers of latency remain largely unknown. Data are accumulating that the dynamical equilibrium between the parasite and the host (expressed as a long term asymptomatic infection) and its abrogation (expressed as a reactivation disease) are genetically controlled by both parties. In this short review, the authors summarize the results of experimental studies on genetic regulation of the latent TB infection.
    Tuberculosis. 01/2014;
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    ABSTRACT: Whole transcriptome profiling is now almost routinely used in various fields of biology, including microbiology. In vivo transcriptome studies usually provide relevant information about the biological processes in the organism and thus are indispensable for the formulation of hypotheses, testing, and correcting. In this study, we describe the results of genome-wide transcriptional profiling of the major human bacterial pathogen M. tuberculosis during its persistence in lungs. Two mouse strains differing in their susceptibility to tuberculosis were used for experimental infection with M. tuberculosis. Mycobacterial transcriptomes obtained from the infected tissues of the mice at two different time points were analyzed by deep sequencing and compared. It was hypothesized that the changes in the M. tuberculosis transcriptome may attest to the activation of the metabolism of lipids and amino acids, transition to anaerobic respiration, and increased expression of the factors modulating the immune response. A total of 209 genes were determined whose expression increased with disease progression in both host strains (commonly upregulated genes, CUG). Among them, the genes related to the functional categories of lipid metabolism, cell wall, and cell processes are of great interest. It was assumed that the products of these genes are involved in M. tuberculosis adaptation to the host immune system defense, thus being potential targets for drug development.
    Acta naturae. 04/2013; 5(2):62-9.
  • Boris V Nikonenko, Alexander S Apt
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    ABSTRACT: Mice as a species are susceptible to tuberculosis infection while mouse inbred strains present wide spectrum of susceptibility/resistance to this infection. However, non-tuberculosis Mycobacterial infections usually cannot be modeled in mice of common inbred strains. Introduction of specific properties, such as gene mutations, recombinants, targeted gene knockouts significantly extended the use of mice to mimic human Mycobacterial infections, including non-tuberculosis ones. This review describes the available mouse models of tuberculosis and non-tuberculosis infections and drug therapy in these models. Mouse models of non-tuberculosis infections are significantly less developed than tuberculosis models, hampering the development of therapies.
    Tuberculosis (Edinburgh, Scotland) 03/2013; · 2.54 Impact Factor
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    ABSTRACT: The balance between activation and inhibition of local immune responses in affected tissues during prolonged chronic infections is important for host protection. There is ample evidence that regulatory, tolerogenic dendritic cells (DC) are developed and present in tissues and inhibit overwhelming inflammatory reactions. Also, it was firmly established that stromal microenvironment of many organs is able to induce development of immature regulatory DC (DCreg), an essential element of a general immune regulatory network. However, direct experimental data demonstrating inhibition of immune responses by stroma-instructed immature DCreg in infectious models are scarce, and virtually nothing is known about functioning of this axis of immunity during tuberculosis (TB) infection. In this study, we demonstrate that lung stromal cells are capable of supporting the development in culture of immature CD11b(+)CD11c(low)CD103(-) DCreg from lineage-negative (lin(-)) bone marrow precursors. DCreg developed on lung stroma isolated from mice of genetically TB-hyper-susceptible I/St and relatively resistant B6 inbred strains inhibited proliferative response of mycobacteria-specific CD4(+) T-cell lines a dose-dependent manner. Importantly, the inhibitory activity of B6 DCreg was substantially higher than that of I/St Dcreg. Moreover, when the donors of stromal cells were chronically infected with virulent mycobacteria, the capacity to instruct inhibitory DCreg was retained in B6, but further diminished in I/St stromal cells. DCreg-provided suppression was mediated by a few soluble mediators, including PGE2, NO and IL-10. The content of CD4(+)Foxp3(+) Treg cells in the mediastinal, lung-draining lymph nodes at the advanced stages of chronic infection did not change in I/St, but increased 2-fold in B6 mice, and lung pathology was much more pronounced in the former mice. Taken together, these data provide genetic evidence that the capacity to maintain populations of regulatory cells during M. tuberculosis infection is a part of the host protective strategy.
    PLoS ONE 01/2013; 8(8):e72773. · 3.73 Impact Factor
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    ABSTRACT: Deep sequencing was implemented to study the transcriptional landscape of Mycobacterium avium. High-resolution transcriptome analysis identified the transcription start points for 652 genes. One third of these genes represented leaderless transcripts, whereas the rest of the transcripts had 5' UTRs with the mean length of 83 nt. In addition, the 5' UTRs of 6 genes contained SAM-IV and Ykok types of riboswitches. 87 antisense RNAs and 10 intergenic small RNAs were mapped. 6 intergenic small RNAs, including 4.5S RNA and rnpB, were transcribed at extremely high levels. Although several intergenic sRNAs are conserved in M. avium and M. tuberculosis, both of these species have unique intergenic sRNAs. Moreover, we demonstrated that even conserved small RNAs are regulated differently in these species. Different sets of intergenic sRNAs may underlie differences in physiology between conditionally pathogenic M. avium and highly specialized pathogen M. tuberculosis.
    PLoS ONE 01/2013; 8(9):e74209. · 3.73 Impact Factor
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    ABSTRACT: Using whole genome microarrays, we compared changes in gene expression patterns in the lungs of TB-resistant A/Sn and TB-susceptible I/St mice at day 14 following infection with Mycobacterium tuberculosis H37Rv. Analyses of differentially expressed genes for representation of gene ontology terms and activation of regulatory pathways revealed interstrain differences in antigen presentation, NK, T and B cell activation pathways. In general, resistant A/Sn mice exhibited a more complex pattern and stronger activation of host defense pathways compared to the TB-susceptible I/St mouse strain. In addition, in I/St mice elevated activation of genes involved in neutrophil response was observed and confirmed by quantitative RT-PCR and histopathology. Furthermore, a specific post infection upregulation of cysteine protease inhibitors was found in susceptible I/St mice.
    Tuberculosis (Edinburgh, Scotland) 12/2012; · 2.54 Impact Factor
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    ABSTRACT: The species Mycobacterium avium includes several subspecies representing highly specialized avian and mammalian pathogens, non-obligatory pathogens of immune compromised humans and saprophitic organisms. Recently obtained information concerning the diversity of M. avium genomic structures not only clarified phylogenic relationships within this species, but began to shed light on the question of how such closely related microorganisms adapt to the occupation of distinct ecological niches. In this review we discuss specific features of M. avium genetic composition, as well as genetic and molecular aspects of M. avium hominissuis (MAH)-triggered disease pathogenesis, including virulence, penetration, immune response manipulation and host genetic control.
    Cellular Microbiology 02/2012; 14(6):808-18. · 4.81 Impact Factor
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    ABSTRACT: Protein genes Ag85A, Esat-6, and Cfp10 of Mycobacterium tuberculosis were sequenced using the database GenBank to implement selection and synthesis of primer pairs of given genes. PCR was used to obtain target amplicons of the genes. Chromosome DNA of M. tuberculosis H37Rv was used as the DNA amplification matrix. The PCR products were obtained using the plasmid pQE6, cloned, and amplified in the Escherichia coli M15 strain. Chimere products containing mycobacterial genes and cellulose binding protein domain (CBD), were obtained using the plasmid treated with restriction endonucleases. CBD fragment obtained using similar treatment of the ptt10 plasmid. The plasmids containing merged sequences of mycobacterial genes-antigenes and CBD were selected. The 3 mycobacterial genes were expressed in the E. coli M15 cells resulting in biosynthesis of corresponding recombinant proteins of expected molecular weight. Concentration of CBD, Cfp10-CBD, Ag85A-CBD, and ESAT6-CBD was 20%, 15%, and 15% total protein, respectively. The resulting chimere proteins provide high affinity for cellulose and high stability. Immobilization of CBD-containing recombinant proteins proceeds as one-stage process providing target protein purification and adsorption on cellulose. The vaccines produced using this technology are inexpensive because of low cost of cellulose sorbents as well as simultaneous use of cellulose for purification and immobilization of protein. Many cellulose preparations are not toxic, biocompatible, and widely used in medicine.
    Molekuliarnaia genetika, mikrobiologiia i virusologiia 01/2012;
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    Alexander S Apt
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    ABSTRACT: Relevance and accuracy of experimental mouse models of tuberculosis (TB) are the subject of constant debate. This article briefly reviews genetic aspects of this problem and provides a few examples of mycobacterial diseases with similar or identical genetic control in mice and humans. The two species display more similarities than differences regarding both genetics of susceptibility/severity of mycobacterial diseases and the networks of protective and pathological immune reactions. In the opinion of the author, refined mouse models of mycobacterial diseases are extremely useful for modelling the corresponding human conditions, if genetic diversity is taken into account.
    Immunology 10/2011; 134(2):109-15. · 3.71 Impact Factor
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    ABSTRACT: In this study, we investigated the residual virulence of mutants of Mycobacterium tuberculosis that are defective in 4 of the 5 rpf-like genes, their capacity to persist in the murine host and the utility present in these mutants to serve as novel vaccine candidates. Our data indicate that the two quadruple rpf deletion mutants, ΔACBD and ΔACDE, both display significant attenuation in the mouse lungs after aerosol infection, with no observable increase in bacillary loads upon aminoguanidine-induced immune suppression. However, after subcutaneous injection these strains were able to persist at the low level, similar to that of BCG, in the mouse lungs and lymphoid organs. Furthermore, both rpf quadruple mutants were able to enhance the numbers of IFN-γ-producing T-cells in spleens to a level comparable to that of BCG, and conferred protection upon subsequent challenge with virulent M. tuberculosis in terms of mycobacterial multiplication in organs and survival time. The reduction in organ bacillary loads after vaccination with ΔACDE was comparable to that of BCG, while ΔACBD displayed a small but statistically significant enhancement in protection compared to BCG. Collectively, these data suggest that rpf deletion mutants show potential for further development as novel vaccine candidates for tuberculosis.
    Tuberculosis (Edinburgh, Scotland) 03/2011; 91(3):219-23. · 2.54 Impact Factor
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    ABSTRACT: One of genetic loci involved in tuberculosis (TB) infection control in mice is located within the segment of Chr. 17 occupied by the H2 complex, the mouse MHC. As far as this region includes approximately 40 Mb and contains hundreds of genes affecting immune responses and host-parasite interactions, narrowing the interval by genetic recombination is pre-requisite for identification of particular gene(s). We have developed a panel of recombinant congenic strains bearing different parts of the H2 complex from TB-susceptible I/St mice on the genetic background of TB-resistant C57BL/6 mice. By superposing the phenotype "severe vs. mild infectious course" against the chart of alleles inherited by these new strains from the two parental strains, we have mapped a locus involved in TB control within the segment 33.305-34.479 Mb (-1.1 Mb) of the Chr. 17. Such a location indicates that allelic variants of the prominent pro-inflammatory factor TNF do not affect TB course in our experimental system. This result was confirmed by the assessment of the TNF level in the lung tissue of infected mice of different strains. The QTL (quantitative trait locus) mapped in our study influences several important parameters of TB infection: multiplication of mycobacteria in the lungs, severity of lung pathology and regulation of the early inflammatory response.
    Molekuliarnaia biologiia 01/2011; 45(1):68-76.
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    ABSTRACT: IL-11 is multifunctional cytokine whose physiological role in the lungs during pulmonary tuberculosis (TB) is poorly understood. Here, using in vivo administration of specific antibodies against IL-11, we demonstrate for the first time that blocking IL-11 diminishes histopathology and neutrophilic infiltration of the lung tissue in TB-infected genetically susceptible mice. Antibody treatment decreased the pulmonary levels of IL-11 and other key inflammatory cytokines not belonging to the Th1 axis, and down-regulated IL-11 mRNA expression. This suggests the existence of a positive feedback loop at the transcriptional level, which is further supported by up-regulation of IL-11 mRNA expression in the presence of rIL-11 in in vitro cultures of lung cells. These findings imply a pathogenic role for IL-11 during the early phase of Mycobacterium tuberculosis-triggered disease in a genetically susceptible host.
    PLoS ONE 01/2011; 6(7):e21878. · 3.73 Impact Factor
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    ABSTRACT: We performed a comparative analysis ofMycobacterium aviumtranscriptomes (strain 724R) in infected mice of two different strains- resistant and susceptible to infection. Sets of mycobacterial genes transcribed in lung tissue were defined, and differentially transcribed genes were revealed. Our results indicate thatM. aviumgenes coding for enzymes of the Krebs cycle, oxidative phosphorylation, NO reduction, fatty acid biosynthesis, replication, translation, and genome modification are expressed at high levels in the lungs of genetically susceptible mice. The expression of genes responsible for cell wall properties, anaerobic nitrate respiration, fatty acid degradation, synthesis of polycyclic fatty acid derivatives, and biosynthesis of mycobactin and other polyketides is increased in the resistant mice. In the resistant host environment,Mycobacterium aviumapparently transitions to a latent state caused by the deficiency in divalent cations and characterised by anaerobic respiration, degradation of fatty acids, and modification of cell wall properties.
    Acta naturae. 07/2010; 2(3):78-83.
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    ABSTRACT: We propose a novel experimental approach based on coincidence cloning for analyzing sequences of bacterial intracellular pathogens specifically transcribed in affected tissues. Co-denaturation and co-renaturation of excess bacterial genomic DNA with the cDNA prepared on total RNA of the infected tissue allows one to select the bacterial fraction of the cDNA sample. We used this technique for preparing and characterizing the Mycobacterium tuberculosis cDNA pool, representing the transcriptome of infected mouse lungs in the chronic phase of infection. A cDNA pool enriched in fragments of mycobacterial cDNA was analyzed by the high-throughput 454 sequencing procedure. We demonstrated that its composition corresponded to what can be expected in the chronic phase of infection and, after the adaptation of M. tuberculosis to the host immune system, was characterized by an active lipid metabolism and switched from aerobic to anaerobic respiration. The technique is universal and requires no prior knowledge of the pathogen genome sequence. Pools of transcribed sequences obtained by this technique retain the main characteristics of the genome-wide gene transcription pattern within infected tissue, and can be used for in vivo analysis of gene expression of a wide spectrum of infection agents, such as viruses, bacteria, and protista.
    BioTechniques 02/2010; 48(2):139-44. · 2.40 Impact Factor
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    ABSTRACT: Mice of I/St strain develop severe lung inflammation and die shortly following infection with virulent mycobacteria. The susceptibility does not depend on the Nramp1 gene, as I/St mice carry its resistant allele, but is controlled by little interacting QTL mapped to chromosomes 3, 9, 17. To find out whether the tuberculosis-susceptible I/St mice are susceptible to other intracellular bacteria taxonomically distant pathogen of Chlamydia pneumoniae was studied. Comparison of I/St and TB-resistant A/Sn mice (both Nramp1r) demonstrated that the former were more susceptible to chlamydia, displaying a significantly shortened survival time following challenge (I/St, 9.2 +/- 1.2 days; A/Sn, 22.0 +/- 0 days (p < 0.001)). To estimate the degree of chlamydial multiplication in the lungs, we suggested a quantitative real-time polymerase chain reaction (PCR)-based method which allows enumeration of the parasite's genome equivalents in infected tissue from 1 to 16 days after challenge. The interstrain difference of chlamydia burden in lungs was observed only after 24 hours after infection. Multiplication of chlamydia in the lungs was controlled efficiently after day 4 of infection. The numbers of genome equivalents dropped slightly by day 8 both in I/St and A/Sn mice. Lung pathology develops more rapidly in I/St compared to A/Sn mice following infection with chlamydia despite their similar ability to control bacterial multiplication. Lung tissue of susceptible I/St mice was markedly infiltrated with macrophages (p < 0.01), which differed significantly from the lungs of resistant A/Sn mice. In agreement with higher macrophage content in the lungs, significantly more macrophage-derived proinflammatory cytokines TNF-? and IL-6 were detected in lung tissue homogenates obtained from I/St mice (p < 0.05). Because the prominent difference in survival time did not correlate with permanent difference in bacterial multiplication, we suggested that both infections trigger fatal pathological processes whose dynamics depends strongly upon the host genetics.
    Molekuliarnaia genetika, mikrobiologiia i virusologiia 01/2010;
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    ABSTRACT: Development of lung granulomata is a hallmark of infections caused by virulent mycobacteria, reflecting both protective host response that restricts infection spreading and inflammatory pathology. The role of host genetics in granuloma formation is not well defined. Earlier we have shown that mice of the I/St strain are extremely susceptible to Mycobacterium tuberculosis but resistant to M. avium infection, whereas B6 mice show a reversed pattern of susceptibility. Here, by directly comparing: (i) characteristics of susceptibility to two infections in vivo; (ii) architecture of lung granulomata assessed by immune staining; and (iii) expression of genes encoding regulatory factors of neutrophil influx in the lung tissue, we demonstrate that genetic susceptibility of the host largely determines the pattern of lung pathology. Necrotizing granuloma surrounded by hypoxic zones, as well as a massive neutrophil influx, develop in the lungs of M. avium-infected B6 mice and in the lungs of M. tuberculosis-infected I/St mice, but not in the lungs of corresponding genetically resistant counterparts. The mirror-type lung tissue responses to two virulent mycobacteria indicate that the level of genetic susceptibility of the host to a given mycobacterial species largely determines characteristics of pathology, and directly demonstrate the importance of host genetics in pathogenesis.
    PLoS ONE 01/2010; 5(5):e10515. · 3.73 Impact Factor
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    ABSTRACT: Mutations in the btk gene encoding Bruton's tyrosine kinase cause X-linked immune deficiency, with impaired B lymphocyte function as the major phenotype. Earlier, we demonstrated that CBA/N-xid mice, unlike the wild-type CBA mice, were not protected by bacillus Calmette-Guérin (BCG) vaccination against tuberculosis infection. Because IFN-gamma-producing T cells and activated macrophages are key elements of antituberculosis protection, it remained unclear how the mutation predominantly affecting B cell functions interferes with responses along the T cell-macrophage axis. In this study, we show that B cell deficiency leads to an abnormally rapid neutrophil migration toward the site of external stimulus. Using adoptive cell transfers and B cell genetic knockout, we demonstrate a previously unappreciated capacity of B cells to downregulate neutrophil motility. In our system, an advanced capture of BCG by neutrophils instead of macrophages leads to a significant decrease in numbers of IFN-gamma-producing T cells and impairs BCG performance in X-linked immune-deficient mice. The defect is readily compensated for by the in vivo neutrophil depletion.
    The Journal of Immunology 12/2009; 184(3):1227-34. · 5.52 Impact Factor
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    Alexander Apt, Igor Kramnik
    Tuberculosis (Edinburgh, Scotland) 05/2009; 89(3):195-8. · 2.54 Impact Factor
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    ABSTRACT: Tuberculosis is a chronic infectious disease that predominantly affects the lungs. The hallmark of tuberculosis infection is the formation of granulomas in the vicinity of infectious foci. Tuberculous granulomas are highly organized bodies with a complex cell composition and well-orchestrated biochemical pathways. Granuloma development plays a dual role. The process restricts the infection dissemination and forms a battlefield for protective immunity but simultaneously may compromise the lung function, threatening host health. The susceptibility to the infection per se, the degree of lung failure, and disease severity are under genetic control. Tuberculosis genetics is complex and poorly understood, but current knowledge indicates that intracellular infections are controlled by a network of biochemical reactions, many of which were not suspected to be involved until recently.
    Molecular Biology 09/2008; 42(5):784-793. · 0.64 Impact Factor
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    ABSTRACT: We previously demonstrated that mice of the I/St strain are extremely susceptible to Mycobacterium tuberculosis, as well as to the taxonomically distant intracellular bacteria Chlamydia pneumoniae and Salmonella enterica. To broaden our knowledge about the control of susceptibility to intracellular pathogens, we studied the infection caused by Mycobacterium avium virulent strain 724 in a panel of inbred mouse strains and found that I/St mice are resistant to M. avium. By comparing I/St mice with B6 mice, we demonstrated that (i) B6 mice are much more susceptible to infection caused by M. avium in terms of bacterial multiplication in the lung tissue and severity of lung pathology; (ii) in B6 mice but not in I/St mice infection leads to prolonged leukocyte infiltration of the lung tissue, development of necrotic lung granulomata, and lethality; and (iii) the unfavorable infectious course in B6 mice is accompanied by elevated production of gamma interferon, tumor necrosis factor alpha, and especially interleukin-12 in the lungs. Importantly, M. avium-resistant I/St mice carry a functional r allele of the Slc11a1 (formerly Nramp1) gene, while B6 mice have the Slc11a1(s) genotype. Segregation genetic analysis of (I/St x B6) F2 hybrids demonstrated that susceptibility or resistance to infection caused by M. avium largely depended upon the Slc11a1 genotype and that other genetic traits had a relatively weak influence. This close-to-monogenic pattern differs sharply from the host control of many other intracellular bacterial infections, for which the involvement of numerous quantitative trait loci has been ubiquitously observed.
    Infection and Immunity 11/2007; 75(10):4762-8. · 4.07 Impact Factor

Publication Stats

1k Citations
194.16 Total Impact Points

Institutions

  • 2013
    • Central Research Institute of Epidemiology
      Moskva, Moscow, Russia
  • 2012
    • Pacific Institute of Bioorganic Chemistry
      Wladiwostok, Primorskiy, Russia
  • 1997–2011
    • Russian Academy of Medical Sciences
      Moskva, Moscow, Russia
    • Imperial College London
      Londinium, England, United Kingdom
  • 2006
    • Research Institute of Epidemiology and Microbiology n.a. N. F. Gamalei, Russian Academy of Medical Sciences
      Moskva, Moscow, Russia
  • 2005
    • University of Wales
      Cardiff, Wales, United Kingdom