Metabolic Changes of Mycobacterium tuberculosis during the Anti-Tuberculosis Therapy

Mycobacterium tuberculosis and Pulmonary Rehabilitation: From Novel Pharmacotherapeutic Approaches to Management of Post-Tuberculosis Sequelae

Tuberculosis (TB) is still a worldwide public health burden, as more than 1.3 million deaths are expected to be reported in 2021. Even though almost 20 million patients have completed specific anti-TB treatment and survived in 2020, little information is known regarding their pulmonary sequelae, quality of life, and their need to follow rehabilitation services as researchers shifted towards proper diagnosis and treatment rather than analyzing post-disease development. Understanding the underlying immunologic and pathogenic mechanisms during mycobacterial infection, which have been incompletely elucidated until now, and the development of novel anti-TB agents could lead to the proper application of rehabilitation care, as TB sequelae result from interaction between the host and Mycobacterium tuberculosis. This review addresses the importance of host immune responses in TB and novel potential anti-TB drugs’ mechanisms, as well as the assessment of risk factors for post-TB disease and usefulness of guidance and optimization of pulmonary rehabilitation. The use of rehabilitation programs for patients who successfully completed anti-tuberculotic treatment represents a potent multifaceted measure in preventing the increase of mortality rates, as researchers conclude that a patient with a TB diagnosis, even when properly completing pharmacotherapy, is threatened by a potential life loss of 4 years, in comparison to healthy individuals. Dissemination of pulmonary rehabilitation services and constant actualization of protocols could strengthen management of post-TB disease among under-resourced individuals.

Transcriptomic Profile of Mycobacterium smegmatis in Response to an Imidazo[1,2-b][1,2,4,5]tetrazine Reveals Its Possible Impact on Iron Metabolism

Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex bacteria, is one of the most pressing health problems. The development of new drugs and new therapeutic regimens effective against the pathogen is one of the greatest challenges in the way of tuberculosis control. Imidazo[1,2-b][1,2,4,5]tetrazines have shown promising activity against M. tuberculosis and M. smegmatis strains. Mutations in MSMEG_1380 lead to mmpS5–mmpL5 operon overexpression, which provides M. smegmatis with efflux-mediated resistance to imidazo[1,2-b][1,2,4,5]tetrazines, but the exact mechanism of action of these compounds remains unknown. To assess the mode of action of imidazo[1,2-b][1,2,4,5]tetrazines, we analyzed the transcriptomic response of M. smegmatis to three different concentrations of 3a compound: 1/8×, 1/4×, and 1/2× MIC. Six groups of genes responsible for siderophore synthesis and transport were upregulated in a dose-dependent manner, while virtual docking revealed proteins involved in siderophore synthesis as possible targets for 3a. Thus, we suggest that imidazo[1,2-b][1,2,4,5]tetrazines may affect mycobacterial iron metabolism.

Development of a microfluidic biosensor for the diagnostics and typing of <i>Mycobacterium Tuberculosis</i>

Background. Despite on the general trend towards decreasing the incidence of newly diagnosed active forms of tuberculosis, the situation with spreading of this disease in Russian Federation remains extremely tense. At the same time, the diagnosis is carried out according to the standard scheme, which takes about a month; another month takes test formulation for drug sensitivity. Thus, the development of new methods for diagnostics and typing of mycobacteria, as well as practice implementation of these developments is an urgent direction. Modern developments in the field of microfluidic technologies open up great opportunities in this direction. Aim. Development of a method for identification and typing of Mycobacterium tuberculosis using a label-free biosensor on surface waves in a one-dimensional photonic crystal (PC SM biosensor). Methods. Oligonucleotide probes were selected and synthesized as DNA targets for M. tuberculosis typing. The photonic crystal surface was modified with aqueous solutions of (3-aminopropyl)triethoxysilane, Leuconostoc mesenteroides dextrans and bovine serum albumin. Experiments were carried out using a PC SM biosensor. Results. Sequences of detecting oligonucleotide probes were selected for spoligotyping of M. tuberculosis on the PC SM biosensor. Modification of their 3'-ends was carried out in order to create extended single-stranded regions that are not subject to the formation of secondary structures and facilitate hybridization with a single-stranded DNA target. Several series of experimental modifications of the PC surface were carried out by using L. mesenteroides dextrans with different functional groups (including detection of the modification results real time) with simultaneous registration of the increment layer size and volume refractive index of the mixture, which excludes the use of a reference cell. Other experiments were carried out to detect the specific binding of biotinylated oligonucleotide probes to the modified PC surface. Conclusions. A technique for the design of probes was developed and a model system of oligonucleotides for the detection of single-stranded DNA using a PC biosensor was proposed. The developed technique of modification of the PC surface with dextrans from L. mesenteroides, which allows to increase the sensitivity of detection of oligonucleotides using the PC SM biosensor. This approach will further expand the panel of diagnostic probes, including identification of resistance markers.

Transcriptional Landscape of Staphylococcus aureus Kayvirus Bacteriophage vB_SauM-515A1

The Twort-like myoviruses (Kayvirus genus) of S. aureus are promising agents for bacteriophage therapy due to a broad host range and high killing activity against clinical isolates. This work improves the current understanding of the phage infection physiology by transcriptome analysis. The expression profiles of a typical member of the Kayvirus genus (vB_SauM-515A1) were obtained at three time-points post-infection using RNA sequencing. A total of 35 transcription units comprising 238 ORFs were established. The sequences for 58 early and 12 late promoters were identified in the phage genome. The early promoters represent the strong sigma-70 promoters consensus sequence and control the host-dependent expression of 26 transcription units (81% of genes). The late promoters exclusively controlled the expression of four transcription units, while the transcription of the other five units was directed by both types of promoters. The characteristic features of late promoters were long -10 box of TGTTATATTA consensus sequence and the absence of -35 boxes. The data obtained are also of general interest, demonstrating a strategy of the phage genome expression with a broad overlap of the early and late transcription phases without any middle transcription, which is unusual for the large phage genomes (>100 kbp).

Gene Networks Underlying the Resistance of Bifidobacterium longum to Inflammatory Factors

As permanent residents of the normal gut microbiota, bifidobacteria have evolved to adapt to the host’s immune response whose priority is to eliminate pathogenic agents. The mechanisms that ensure the survival of commensals during inflammation and maintain the stability of the core component of the normal gut microbiota in such conditions remain poorly understood. We propose a new in vitro approach to study the mechanisms of resistance to immune response factors based on high-throughput sequencing followed by transcriptome analysis. This approach allowed us to detect differentially expressed genes associated with inflammation. In this study, we demonstrated that the presence of the pro-inflammatory cytokines IL-6 and TNFα to the growth medium of the B. longum subsp. longum GT15 strain changes the latter’s growth rate insignificantly while affecting the expression of certain genes. We identified these genes and performed a COG and a KEGG pathway enrichment analysis. Using phylogenetic profiling we predicted the operons of genes whose expression was triggered by the cytokines TNFα and IL-6 in vitro. By mapping the transcription start points, we experimentally validated the predicted operons. Thus, in this study, we predicted the genes involved in a putative signaling pathway underlying the mechanisms of resistance to inflammatory factors in bifidobacteria. Since bifidobacteria are a major component of the human intestinal microbiota exhibiting pronounced anti-inflammatory properties, this study is of great practical and scientific relevance.

Aureolic Acid Group of Agents as Potential Antituberculosis Drugs

Mycobacterium tuberculosis is one of the most dangerous pathogens. Bacterial resistance to antituberculosis drugs grows each year, but searching for new drugs is a long process. Testing for available drugs to find active against mycobacteria may be a good alternative. In this work, antibiotics of the aureolic acid group were tested on a model organism Mycobacterium smegmatis. We presumed that antibiotics of this group may be potential G4 ligands. However, this was not confirmed in our analyses. We determined the antimicrobial activity of these drugs and revealed morphological changes in the cell structure upon treatment. Transcriptomic analysis documented increased expression of MSMEG_3743/soj and MSMEG_4228/ftsW, involved in cell division. Therefore, drugs may affect cell division, possibly disrupting the function of the Z-ring and the formation of a septum. Additionally, a decrease in the transcription level of several indispensable genes, such as nitrate reductase subunits (MSMEG_5137/narI and MSMEG_5139/narX) and MSMEG_3205/hisD was shown. We concluded that the mechanism of action of aureolic acid and its related compounds may be similar to that bedaquiline and disturb the NAD+/NADH balance in the cell. All of this allowed us to conclude that aureolic acid derivatives can be considered as potential antituberculosis drugs.

Transcriptomic dataset of Mycolicibacterium smegmatis exposed to an imidazo[1,2-b][1,2,4,5]tetrazine

Deciphering the mechanism of action of novel anti-tuberculosis compounds is a key step in the drug development process. We have previously described a number of imidazo[1,2-b][1,2,4,5]tetrazines with a promising activity on Mycobacterium tuberculosis[1]. These compounds had predicted activity as serine‑threonine protein kinase inhibitors, however spontaneous drug resistant Mycolicibacterium smegmatis mc ² 155 (formerly Mycobacterium smegmatis) revealed only the mycobacterial mechanism of resistance to imidazo[1,2-b][1,2,4,5]tetrazines: mutations in MSMEG_1380 gene lead to overexpression of the mmpS5-mmpL5 operon in M. smegmatis, thus providing resistance to imidazo[1,2-b][1,2,4,5]tetrazines via enhanced efflux [2]. Here we report the RNA sequencing data of M. smegmatis mc ²  155 culture treated with one of the imidazo[1,2-b][1,2,4,5]tetrazines for 1.5 h and the untreated culture as a control. The mapped reads showed that a total of 1386 genes are differentially expressed in this experiment. A further analysis of these data can shed light of the mechanism of action of imidazo[1,2-b][1,2,4,5]tetrazines. The data generated by RNA-seq (raw reads) have been deposited to NCBI sequence read archive (SRA) and have been assigned a BioProject accession number PRJNA615922.

Mycobacterium tuberculosis Pathogenesis, Infection Prevention and Treatment

Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis (MTB) and it represents a persistent public health threat for a number of complex biological and sociological reasons. According to the most recent Global Tuberculosis Report (2019) edited by the World Health Organization (WHO), TB is considered the ninth cause of death worldwide and the leading cause of mortality by a single infectious agent, with the highest rate of infections and death toll rate mostly concentrated in developing and low-income countries. We present here the editorial section to the Special Issue entitled “Mycobacterium tuberculosis Pathogenesis, Infection Prevention and Treatment” that includes 7 research articles and a review. The scientific contributions included in the Special Issue mainly focus on the characterization of MTB strains emerging in TB endemic countries as well as on multiple mechanisms adopted by the bacteria to resist and to adapt to antitubercular therapies.