Monocyte and Macrophage miRNA: Potent Biomarker and Target for Host-Directed Therapy for Tuberculosis

The end TB strategy reinforces the essentiality of readily accessible biomarkers for early tuberculosis diagnosis. Exploration of microRNA (miRNA) and pathway analysis opens an avenue for the discovery of possible therapeutic targets. miRNA is a small, non-coding oligonucleotide characterized by the mechanism of gene regulation, transcription, and immunomodulation. Studies on miRNA define their importance as an immune marker for active disease progression and as an immunomodulator for innate mechanisms, such as apoptosis and autophagy. Monocyte research is highly advancing toward TB pathogenesis and biomarker efficiency because of its innate and adaptive response connectivity. The combination of monocytes/macrophages and their relative miRNA expression furnish newer insight on the unresolved mechanism for Mycobacterium survival, exploitation of host defense, latent infection, and disease resistance. This review deals with miRNA from monocytes, their relative expression in different disease stages of TB, multiple gene regulating mechanisms in shaping immunity against tuberculosis, and their functionality as biomarker and host-mediated therapeutics. Future collaborative efforts involving multidisciplinary approach in various ethnic population with multiple factors (age, gender, mycobacterial strain, disease stage, other chronic lung infections, and inflammatory disease criteria) on these short miRNAs from body fluids and cells could predict the valuable miRNA biosignature network as a potent tool for biomarkers and host-directed therapy.

Mycobacterium vicinigordonae sp. nov., a slow-growing scotochromogenic species isolated from sputum

A slow-growing, scotochromogenic mycobacterial strain (24T) was isolated from the sputum of a Chinese male human. Phylogenetic analysis using the 16S rRNA gene assigned strain 24T to the Mycobacterium gordonae complex, which includes Mycobacterium gordonae and Mycobacterium paragordonae . The phenotypic characteristics, unique mycolic acid profile and the results of phylogenetic analysis based on hsp65 and rpoB sequences strongly supported the taxonomic status of strain 24T as a representative of a species distinct from the other members of the M. gordonae complex. The genomic G+C content of strain 24T was 65.40mol%. Genomic comparisons showed that strain 24T and M. gordonae ATCC 14470T had an average nucleotide identity (ANI) value of 81.00 % and a DNA–DNA hybridization (DDH) value of 22.80 %, while the ANI and DDH values between strain 24Tand M. paragordonae 49 061T were 80.98 and 22.80 %, respectively. In terms of phylogenetic, phenotypic and chemotaxonomic features, strain 24T is distinguishable from its closest phylogenetic relatives and represents a novel species of the genus Mycobacterium , therefore the name Mycobacterium vicinigordonae sp. nov. is proposed. The type strain is 24T (=CMCC 93559T=DSM 105979T).

Experimental and computational studies of an antiplasmodial derivative of allantoin; antimycobacterial essential oil from Cordia batesii WERNHAM (Boraginaceae)

Background Chemical and pharmacological investigations were performed on the stems of Cordia batesii (Boraginaeae); chemical studies included quantum calculations applied on a newly described compound. Results A new derivative of allantoin (1) named batesiin (2) was characterized. Thirteen other known compounds involving allantoin (1) were either isolated or identified. GC–MS enabled the identification of six compounds from a fraction containing essential oil. MeOH extract and some isolated compounds were tested in vitro against Pf7G8 CQS and Pf Dd2 CQR strains of Plasmodium falciparum; extract disclosed a moderate antiplasmodial activity (IC50 = 50 μg mL−1). Meantime, the CH2Cl2 extract and essential oil fraction were tested on a resistant mycobacterial strain of Mycobacterium tuberculosis; a potent antimycobacterial activity with a MIC = 9.52 μg mL−1 was deduced from essential oil. Density functional theory (DFT) calculations were carried on batesiin (2). Calculated chemical shifts at B3LYP/6-31G(d,p) and MPW1PW91/6-31G+(d,p) showed much better correlations with the experimental data. Time dependent DFT at B3LYP/6-31G+(d,p) displayed a major absorption band 3.01 nm higher than the experimental value. Conclusion Cordia batesii can be considered as promising in search of compounds with antimalarial and antitubercular properties. DFT studies are very helpful when trying to learn more about the spectroscopic insights of a derivative of allantoin (1).

Antibacterial and Antitubercular Activity of Novel Benzothiazole- Aryl Amine Derivatives Tethered through Acetamide Functionality

A novel series of substituted benzothiazole-N-phenyl acetamides were synthesized through a feasible scheme and characterized by IR, 1H NMR and mass spectral methods. All the synthesized compounds were screened for antibacterial activity against two, Gram-positive strains: Staphylococcus aureus, Bacillus subtilis; four, Gram-negative strains: Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and Klebsiella pneumonia; and antitubercular activity against mycobacterial strain: Mycobacterium tuberculosis. Among the 15 compounds (6a-o) tested, three compounds 6e, 6l and 6m have demonstrated high potency with MIC values ranges from 6.25-12.5 μg/mL against both Gram-positive and Gram-negative strains. Compounds 6e and 6l displayed remarkable antitubercular activity with MIC value of 25 μg/mL.

Mycobacterium tuberculosis clinical isolates of the Beijing and East-African Indian lineage induce fundamentally different host responses in mice compared to H37Rv

Substantial differences exist in virulence among Mycobacterium tuberculosis strains in preclinical TB models. In this study we show how virulence affects host responses in mice during the first four weeks of infection with a mycobacterial strain belonging to the Beijing, East-African-Indian or Euro-American lineage. BALB/c mice were infected with clinical isolates of the Beijing-1585 strain or the East-African Indian (EAI)-1627 strain and host responses were compared to mice infected with the non-clinical H37Rv strain of the Euro-American lineage. We found that H37Rv induced a ‘classical’ T-cell influx with high IFN-γ levels, while Beijing-1585 and EAI-1627 induced an influx of B-cells into the lungs together with elevated pulmonary IL-4 protein levels. Myeloid cells in the lungs appeared functionally impaired upon infection with Beijing-1585 and EAI-1627 with reduced iNOS and IL-12 expression levels compared to H37Rv infection. This impairment might be related to significantly reduced expression in the bone marrow of IFN-γ, TNF-α and IFN-β in mice infected with Beijing-1585 and EAI-1627, which could be detected from the third day post infection onwards. Our findings suggest that increased virulence of two clinical isolates compared to H37Rv is associated with a fundamentally different systemic immune response, which already can be detected early during infection.

Exploiting the mycobacterial cell wall to design improved vaccines against tuberculosis

The only vaccine available against tuberculosis (TB), the Bacille Calmette-Guerin (BCG), does not provide effective protection against the most common forms of adult TB and in recent years efforts have been made to develop a new and improved vaccine. Among the strategies implemented, the generation of a new live attenuated mycobacterial strain is seen as one of the most promising and feasible, for scientific, ethical and practical reasons. The new understanding of the biology of the tubercle bacilli and of host-pathogen interaction processes, coupled with the possibility to engineer BCG or M. tuberculosis, opened new avenues to design “intelligent” vaccines, capable of eliciting the immune response associated with protection while avoiding the induction of the host immune response associated with immunopathology. The complex and highly immunogenic mycobacterial cell wall can shape the general and antigen specific immune response elicited following immunization, and the possibility to exploit this knowledge may lead to the development of new vaccines that could help conquer this ancient human disease.

Mycobacterium tuberculosis co-existence with humans: making an imprint on the macrophage P2X7 receptor gene?

The development of tuberculosis (TB) infection in humans depends on the mycobacterial strain and the human host, and is multigenically controlled in both. ATP ligation of P2X7 receptors expressed on human macrophages infected with mycobacteria induces cell death and subsequent loss of intracellular bacterial viability. This study analysed the allelic distribution of two single-nucleotide polymorphisms (SNPs) in the P2RX7 gene in the Slavic population of the St Petersburg area of Russia. Analysis of the −762 C/T P2RX7 promoter SNP revealed no significant association between pulmonary TB patients and control subjects (3×2 χ 2=3.2, 1 d.f., P=0.2). The −762C allele was highly and almost equally represented in both groups in this study (68.2 % in patients and 69.3 % in controls). This result differs strikingly from a Gambian study where this allele was found in only 7 and 12 % of pulmonary TB patients and controls, respectively [Li, C. M., Campbell, S. J., Kumararatne, D. S., Bellamy, R., Ruwende, C., McAdam, K. P. W. J., Hill, A. V. S. & Lammas, D. A. (2002). J Infect Dis 186, 1458–1462]. In contrast, the frequency of the C allele at position 1513 in exon 13, resulting in a loss of P2X7 function, was significantly higher among pulmonary TB patients in this study (P=0.02). Thus, analysis of the P2X7 receptor gene in the Russian Slavic population showed that the 1513C allele, acting dominantly, is a possible risk factor for clinical TB, whereas the −762 P2RX7 polymorphism did not appear to be associated with human susceptibility to TB.