Lung Inflammation Signature in Post-COVID-19 TB Patients.

Tuberculosis (TB) remains a leading cause of infectious disease mortality worldwide, despite the COVID-19 pandemic. The mechanisms by which SARS-CoV-2 affects tuberculosis progression have not yet been established. Here, we compared the level of inflammation in the wall of the tuberculoma and in the parenchymal lung tissue of 30 patients diagnosed with tuberculoma without a history of COVID-19 and 30 patients diagnosed with tuberculoma 3 months after COVID-19. We also characterized TB activity in these patients using a panel of TB-associated miRNAs. Histopathological changes were examined in the resection material, and the expression level of cytokine/chemokine genes was determined by qRT-PCR. In patients with a history of COVID-19, the histological data obtained suggested activation of tuberculosis. In the same group of patients, as opposed to those without a history of COVID-19, equally high levels of pro-inflammatory cytokines/chemokines were expressed both in the tuberculoma wall and in the periphery of the resected specimen. A full set of miRNAs (miR-191, miR-193a, miR-222, miR-223, miR-155, miR-26a, and miR-150) were downregulated in the sera of patients with TB and active COVID-19 co-infection compared to controls. Our observations indicate signs of tuberculosis activation resulting from COVID-19 infection.

MicroRNAs as Biomarkers of Active Pulmonary TB Course.

The spread of drug-resistant forms of TB dictates the need for surgical treatment in the complex of anti-tuberculosis measures in Russia. Most often, surgical intervention is performed in the case of pulmonary tuberculoma or fibrotic cavitary tuberculosis (FCT). This study is devoted to the search for biomarkers that characterize the course of disease in surgical TB patients. It is assumed that such biomarkers will help the surgeon decide on the timing of the planned operation. A number of serum microRNAs, potential regulators of inflammation and fibrosis in TB, selected on the basis of PCR-Array analysis, were considered as biomarkers. Quantitative real time polymerase chain reaction and receiver operating curves (ROC) were used to verify Array data and to estimate the ability of microRNAs (miRNAs) to discriminate between healthy controls, tuberculoma patients, and FCT patients. The study showed that miR-155, miR-191 and miR-223 were differentially expressed in serum of tuberculoma with "decay" and tuberculoma without "decay" patients. Another combination (miR-26a, miR-191, miR-222 and miR-320) forms a set to differentiate between tuberculoma with "decay" and FCT. Patients with tuberculoma without "decay" diagnosis differ from those with FCT in serum expression of miR-26a, miR-155, miR-191, miR-222 and miR-223. Further investigations are required to evaluate these sets on a larger population so as to set cut-off values that could be applied in laboratory diagnosis.

Partial redundancy of the pattern recognition receptors, scavenger receptors, and C-type lectins for the long-term control of Mycobacterium tuberculosis infection.

Mycobacterium tuberculosis is recognized by multiple pattern recognition receptors involved in innate immune defense, but their direct role in tuberculosis pathogenesis remains unknown. Beyond TLRs, scavenger receptors (SRs) and C-type lectins may play a crucial role in the sensing and signaling of pathogen motifs, as well as contribute to M. tuberculosis immune evasion. In this study, we addressed the relative role and potential redundancy of these receptors in the host response and resistance to M. tuberculosis infection using mice deficient for representative SR, C-type lectin receptor, or seven transmembrane receptor families. We show that a single deficiency in the class A SR, macrophage receptor with collagenous structure, CD36, mannose receptor, specific ICAM-3 grabbing nonintegrin-related, or F4/80 did not impair the host resistance to acute or chronic M. tuberculosis infection in terms of survival, control of bacterial clearance, lung inflammation, granuloma formation, and cytokine and chemokine expression. Double deficiency for the SRs class A SR types I and II plus CD36 or for the C-type lectins mannose receptor plus specific ICAM-3 grabbing nonintegrin-related had a limited effect on macrophage uptake of mycobacteria and TNF response and on the long-term control of M. tuberculosis infection. By contrast, mice deficient in the TNF, IL-1, or IFN-gamma pathway were unable to control acute M. tuberculosis infection. In conclusion, we document a functional redundancy in the pattern recognition receptors, which might cooperate in a coordinated response to sustain the full immune control of M. tuberculosis infection, in sharp contrast with the nonredundant, essential role of the TNF, IL-1, or IFN-gamma pathway for host resistance to M. tuberculosis.

Comparative analysis of different vaccine constructs expressing defined antigens from Mycobacterium tuberculosis.

BACKGROUND: Studies of different vaccine constructs have demonstrated variable efficacy against Mycobacterium tuberculosis in animal models. Despite the fact that these vaccines have used one or another of a very small number of immunodominant antigens, a direct comparison of the relative efficacy of the antigens and delivery systems has been difficult, because the studies have used different parameters for assessment. METHODS: We compared the efficacies of the most commonly used vaccine constructs--adjuvanted protein, plasmid DNA, and live bacterial vectors--bearing the immunodominant secreted antigens early secreted antigen target-6 and antigen 85B, either alone or as a fusion protein. Mice were vaccinated with these constructs, and the effects of different delivery systems on protective efficacy (as assessed by survival studies and by monitoring bacterial load) and antigen-specific responses (including the contribution of CD4 and CD8 T cells to these responses) were assayed by various methods. RESULTS: The relative efficacy of different vaccines is dependent on the delivery system, the antigen, and the animal model. Likewise, the relative immunodominance of individual antigens in the fusion molecule is altered by the choice of delivery system. CONCLUSION: These results clearly demonstrate the importance of assessing vaccine function by use of multiple parameters and indicate which parameters are most reliable for assessing vaccine efficacy.

Proteins of the Rpf family: immune cell reactivity and vaccination efficacy against tuberculosis in mice.

It was shown recently that Mycobacterium tuberculosis expresses five proteins that are homologous to Rpf (resuscitation promoting factor), which is secreted by growing cells of Micrococcus luteus. Rpf is required to resuscitate the growth of dormant Micrococcus luteus organisms, and its homologues may be involved in mycobacterial reactivation. Mycobacterial Rpf-like products are secreted proteins, which makes them candidates for recognition by the host immune system and anti-Rpf immune responses potentially protective against reactivated tuberculosis. Here we report that the Rpf protein itself and four out of five of its mycobacterial homologues, which were administered as subunit vaccines to C57BL/6 mice, are highly immunogenic. Rpf-like proteins elicit immunoglobulin G1 (IgG1) and IgG2a responses and T-cell proliferation and stimulate production of gamma interferon, interleukin-10 (IL-10), and IL-12 but not IL-4 or IL-5. Both humoral and T-cell responses against these antigens show a high degree of cross-reactivity. Vaccination of mice with Rpf-like proteins results in a significant level of protection against a subsequent high-dose challenge with virulent M. tuberculosis H37Rv, both in terms of survival times and mycobacterial multiplication in lungs and spleens.