It is generally thought that Mycobacterium tuberculosis (Mtb)-specific CD4+ Th1 cells producing IFN-γ are essential for protection against tuberculosis (TB). In some studies, protection has recently been associated with polyfunctional subpopulation of Mtb-specific Th1 cells, i.e., with cells able to simultaneously secrete several type 1 cytokines. However, the role for Mtb-specific Th1 cells and their polyfunctional subpopulations during established TB disease is not fully defined. Pulmonary TB is characterized by a great variability of disease manifestations. To address the role for Mtb-specific Th1 responses during TB, we investigated how Th1 and other immune cells correlated with particular TB manifestations, such as the degree of pulmonary destruction, TB extent, the level of bacteria excretion, clinical disease severity, clinical TB forms, and “Timika X-ray score,” an integrative parameter of pulmonary TB pathology. In comparison with healthy Mtb-exposed controls, TB patients (TBP) did not exhibit deficiency in Mtb-specific cytokine-producing CD4+ cells circulating in the blood and differed by a polyfunctional profile of these cells, which was biased toward the accumulation of bifunctional TNF-α+IFN-γ+IL-2− lymphocytes. Importantly, however, severity of different TB manifestations was not associated with Mtb-specific cytokine-producing cells or their polyfunctional profile. In contrast, several TB manifestations were strongly correlated with leukocyte numbers, the percent or the absolute number of lymphocytes, segmented or band neutrophils. In multiple alternative statistical analyses, band neutrophils appeared as the strongest positive correlate of pulmonary destruction, bacteria excretion, and “Timika X-ray score.” In contrast, clinical TB severity was primarily and inversely correlated with the number of lymphocytes in the blood. The results suggest that: (i) different TB manifestations may be driven by distinct mechanisms; (ii) quantitative parameters and polyfunctional profile of circulating Mtb-specific CD4+ cells play a minor role in determining TB severity; and (iii) general shifts in production/removal of granulocytic and lymphocytic lineages represent an important factor of TB pathogenesis. Mechanisms leading to these shifts and their specific role during TB are yet to be determined but are likely to involve changes in human hematopoietic system.

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.

Создание новых противотуберкулезных вакцин и разработка методов патогенетической хозяин-ориентированной терапии туберкулеза требуют понимания механизмов, ответственных за протективный противотуберкулезный иммунитет. На протяжении долгого времени основным коррелятом протекции считались антиген-специфичные лимфоциты Th1. Однако со временем накопились сведения, не согласующиеся с этой концепцией. В статье обсуждаются спорные вопросы, касающиеся роли лимфоцитов Th1 в противотуберкулезном иммунитете, и возможности их использования в качестве коррелятов протекции при проведении доклинических и клинических исследований эффективности разрабатываемых вакцинных препаратов. Development of new tuberculosis (TB) vaccines and host-oriented therapy requires understanding mechanisms mediating protective antituberculous immunity. Antigen-specific Th1 lymphocytes have long been considered as the main correlate of TB protection. However, recent data do not confirm this concept. This article discusses debatable issues concerning the role for Th1 lymphocytes in antituberculous immunity, as well as their use as correlates of protection in preclinical and clinical studies assessing the effectiveness of new candidate TB vaccines.