Tuberculosis eradication versus control

Comparison of the Single Cell Immune Landscape between Subjects with High Mycobacterium tuberculosis Bacillary Loads during Active Pulmonary Tuberculosis and Household Members with Latent Tuberculosis Infection

It is unclear how the immune system controls the transition from latent tuberculosis (TB) infection (LTBI) to active pulmonary infection (PTB). Here, we applied mass spectrometry cytometry time-of-flight (CyTOF) analysis of peripheral blood mononuclear cells to compare the immunological landscapes in patients with high tuberculous bacillary load PTB infections and LTBI. A total of 32 subjects (PTB [n = 12], LTBI [n = 17], healthy volunteers [n = 3]) were included. Participants with active PTBs were phlebotomized before administering antituberculosis treatment, whereas participants with LTBI progressed to PTB at the time of household screening. In the present study, CyTOF analysis identified significantly higher percentages of mucosal-associated invariant natural killer T (MAIT NKT) cells in subjects with LTBI than in those with active PTB and healthy controls. Moreover, 6 of 17 (35%) subjects with LTBI progressed to active PTB (LTBI progression) and had higher proportions of MAIT NKT cells and early NKT cells than those without progression (LTBI non-progression). Subjects with LTBI progression also showed a tendency toward low B cell levels relative to other subject groups. In conclusion, MAIT NKT cells were substantially more prevalent in subjects with LTBI, particularly those with progression to active PTB.

MA, Tovar-Rosero YY, Oñate AA, O'Ryan M. Two centuries of vaccination: historical and conceptual approach and future perspectives

Over the past two centuries, vaccines have been critical for the prevention of infectious diseases and are considered milestones in the medical and public health history. The World Health Organization estimates that vaccination currently prevents approximately 3.5-5 million deaths annually, attributed to diseases such as diphtheria, tetanus, pertussis, influenza, and measles. Vaccination has been instrumental in eradicating important pathogens, including the smallpox virus and wild poliovirus types 2 and 3. This narrative review offers a detailed journey through the history and advancements in vaccinology, tailored for healthcare workers. It traces pivotal milestones, beginning with the variolation practices in the early 17th century, the development of the first smallpox vaccine, and the continuous evolution and innovation in vaccine development up to the present day. We also briefly review immunological principles underlying vaccination, as well as the main vaccine types, with a special mention of the recently introduced mRNA vaccine technology. Additionally, we discuss the broad benefits of vaccines, including their role in reducing morbidity and mortality, and in fostering socioeconomic development in communities. Finally, we address the issue of vaccine hesitancy and discuss effective strategies to promote vaccine acceptance. Research, collaboration, and the widespread acceptance and use of vaccines are imperative for the continued success of vaccination programs in controlling and ultimately eradicating infectious diseases.

In vitro bioevaluation and docking study of dihydrosphingosine and ethambutol analogues against sensitive and multi-drug resistant Mycobacterium tuberculosis

Tuberculosis remains a major public health problem and one of the top ten causes of death worldwide. The alarming increase in multidrug-resistant and extensively resistant variants (MDR, pre-XDR, and XDR) makes the disease more difficult to treat and control. New drugs that act against MDR/XDR strains are needed for programs to contain this major epidemic. The present study aimed to evaluate new compounds related to dihydro-sphingosine and ethambutol against sensitive and pre-XDR Mycobacterium strains, as well as to characterize the pharmacological activity through in vitro and in silico approaches in mmpL3 protein. Of the 48 compounds analyzed, 11 demonstrated good to moderate activity on sensitive and MDR Mycobacterium tuberculosis (Mtb), with a Minimum Inhibitory Concentration (MIC) ranging from 1.5 to 8 μM. They presented 2 to 14 times greater potency of activity when compared to ethambutol in pre-XDR strain, and demonstrated a selectivity index varying between 2.21 and 82.17. The substance 12b when combined with rifampicin, showed a synergistic effect (FICI = 0.5) on sensitive and MDR Mtb. It has also been shown to have a concentration-dependent intracellular bactericidal effect, and a time-dependent bactericidal effect in M. smegmatis and pre-XDR M. tuberculosis. The binding mode of the compounds in its cavity was identified through molecular docking and using a predicted structural model of mmpL3. Finally, we observed by transmission electron microscopy the induction of damage to the cell wall integrity of M. tuberculosis treated with the substance 12b. With these findings, we demonstrate the potential of a 2-aminoalkanol derivative to be a prototype substance and candidate for further optimization of molecular structure and anti-tubercular activity in preclinical studies.

CyTOF analysis for differential immune cellular profiling between latent tuberculosis infection and active tuberculosis

Limited data exist about the comparative immune cell population profile determined by cytometry by time-of-flight (CyTOF) analysis between active tuberculosis (TB) and latent TB infection (LTBI). In this study, we performed CyTOF analysis using peripheral blood mononuclear cells (PBMCs) to compare the differential immune cellular profile between active TB and LTBI. A total of 51 subjects (active TB [n = 34] and LTBI [n = 17]) were included. CyTOF analysis of 16 subjects (active TB [n = 8] and LTBI [n = 8]) identified a significantly higher Th17-like cell population in active TB than in LTBI. This finding was validated in the remaining 35 subjects (active TB [n = 26] and LTBI [n = 9]) using flow cytometry analysis, which consistently reveals a higher percentage of Th17 cell population in active TB (p = 0.032). The Th1/Th17 ratio represented good ability to discriminate between active TB and LTBI (AUC = 0.812). Among patients with active TB, the Th17 cell percentage was found to be lower in more advanced forms of the disease. Additionally, Th17 cell percentage positively correlated with the levels of IL-6 and neutrophil-lymphocyte ratio, respectively. In conclusion, CyTOF analysis of PBMCs showed a significantly higher percentage of Th17 cells in active TB although fairly similar immune cell populations between active TB and LTBI were observed.

Intracellular Accumulation of Novel and Clinically Used TB Drugs Potentiates Intracellular Synergy

The therapeutic repertoire for tuberculosis (TB) remains limited despite the existence of many TB drugs that are highly active in in vitro models and possess clinical utility. Underlying the lack of efficacy in vivo is the inability of TB drugs to penetrate microenvironments inhabited by the causative agent, Mycobacterium tuberculosis, including host alveolar macrophages. Here, we determined the ability of the phenoxazine PhX1 previously shown to be active against M. tuberculosis in vitro to differentially penetrate murine compartments, including plasma, epithelial lining fluid, and isolated epithelial lining fluid cells. We also investigated the extent of permeation into uninfected and M. tuberculosis-infected human macrophage-like Tamm-Horsfall protein 1 (THP-1) cells directly and by comparing to results obtained in vitro in synergy assays. Our data indicate that PhX1 (4,750 ± 127.2 ng/ml) penetrates more effectively into THP-1 cells than do the clinically used anti-TB agents, rifampin (3,050 ± 62.9 ng/ml), moxifloxacin (3,374 ± 48.7 ng/ml), bedaquiline (4,410 ± 190.9 ng/ml), and linezolid (770 ± 14.1 ng/ml). Compound efficacy in infected cells correlated with intracellular accumulation, reinforcing the perceived importance of intracellular penetration as a key drug property. Moreover, we detected synergies deriving from redox-stimulatory combinations of PhX1 or clofazimine with the novel prenylated amino-artemisinin WHN296. Finally, we used compound synergies to elucidate the relationship between compound intracellular accumulation and efficacy, with PhX1/WHN296 synergy levels shown to predict drug efficacy. Collectively, our data support the utility of the applied assays in identifying in vitro active compounds with the potential for clinical development. IMPORTANCE This study addresses the development of novel therapeutic compounds for the eventual treatment of drug-resistant tuberculosis. Tuberculosis continues to progress, with cases of Mycobacterium tuberculosis (M. tuberculosis) resistance to first-line medications increasing. We assess new combinations of drugs with both oxidant and redox properties coupled with a third partner drug, with the focus here being on the potentiation of M. tuberculosis-active combinations of compounds in the intracellular macrophage environment. Thus, we determined the ability of the phenoxazine PhX1, previously shown to be active against M. tuberculosis in vitro, to differentially penetrate murine compartments, including plasma, epithelial lining fluid, and isolated epithelial lining fluid cells. In addition, the extent of permeation into human macrophage-like THP-1 cells and H37Rv-infected THP-1 cells was measured via mass spectrometry and compared to in vitro two-dimensional synergy and subsequent intracellular efficacy. Collectively, our data indicate that development of new drugs will be facilitated using the methods described herein.

Khat Chewing and Clinical Conditions Determine the Epidemiology of Primary Drug Resistance Tuberculosis in Amhara Region of Ethiopia: A Multicenter Study

BACKGROUND

Rifampicin and/or multidrug-resistant tuberculosis (RR/MDR-TB) remains an uncontrolled public health emergency that has been synergized by the recently increased person-to-person transmission in the community as primary RR/MDR-TB, which is defined as RR/MDR-TB in new TB patients with no prior exposure to anti-TB treatment for more than one month. This study aimed to measure the prevalence and associated factors of primary drug-resistance among drug-resistant tuberculosis patients, as evidenced by the Amhara region treatment initiating centers.

METHODS

An institutional-based multicenter cross-sectional study was conducted from September 2010 to December 2017, among 580 RR/MDR-TB patients on the second-line anti-TB drug in the Amhara regional state. Data were collected from patient charts and registration books using a standardized data abstraction sheet. The data were entered using Epi-data 4.2.0.0 and transferred to Stata 14 software for further data management and analysis. A bivariable and multivariable binary logistic model was run subsequently, and finally, a p-value of less than 0.05 with a 95% confidence interval (CI) was used to declare the significance of the explanatory variable.

RESULTS

The magnitude of primary drug resistance among drug-resistant tuberculosis patients was 15.69% (95% CI: 12.94, 18.89). Alcohol drinking (adjusted odds ratio [AOR] = 0.31, 95% CI: 0.12-0.82), khat chewing (AOR = 4.43; 95% CI: 1.67-11.76), ambulatory and bedridden functional status (AOR = 0.43; 95% CI: 0.24-0.76) and (AOR = 0.41; 95% CI: 0.19-0.91), respectively, positive sputum smear result (AOR = 0.48; 95% CI: 0.26-0.90), and HIV coinfection (AOR= 2.31; 95% CI: 1.31-4.06) remained statistically significant associated factors of primary RR/MDR-TB.

CONCLUSION

Primary drug resistance is a public health problem in the study setting. Different behavioral and clinical conditions were significant factors of primary drug-resistant development. Mitigation strategies targeted on the patient's clinical condition, substance-related behaviors, and universal DST coverage might be very important for early detection and treatment of RR/MDR-TB to prevent community-level transmission.

Calcitriol Suppresses HIF-1 and HIF-2 Transcriptional Activity by Reducing HIF-1/2α Protein Levels via a VDR-Independent Mechanism

Hypoxia-inducible transcription factors 1 and 2 (HIFs) are major mediators of cancer development and progression and validated targets for cancer therapy. Although calcitriol, the biologically active metabolite of vitamin D, was attributed with anticancer properties, there is little information on the effect of calcitriol on HIFs and the mechanism underling this activity. Here, we demonstrate the negative effect of calcitriol on HIF-1/2α protein levels and HIF-1/2 transcriptional activity and elucidate the molecular mechanism of calcitriol action. We also reveal that the suppression of vitamin D receptor (VDR) expression by siRNA does not abrogate the negative regulation of HIF-1α and HIF-2α protein levels and HIF-1/2 transcriptional activity by calcitriol, thus testifying that the mechanism of these actions is VDR independent. At the same time, calcitriol significantly reduces the phosphorylation of Akt protein kinase and its downstream targets and suppresses HIF-1/2α protein synthesis by inhibiting HIF1A and EPAS1 (Endothelial PAS domain-containing protein 1) mRNA translation, without affecting their mRNA levels. On the basis of the acquired data, it can be proposed that calcitriol reduces HIF-1α and HIF-2α protein levels and inhibits HIF-1 and HIF-2 transcriptional activity by a VDR-independent, nongenomic mechanism that involves inhibition of PI3K/Akt signaling pathway and suppression of HIF1A and EPAS1 mRNA translation.

3D QSAR-based design and liquid phase combinatorial synthesis of 1,2-disubstituted benzimidazole-5-carboxylic acid and 3-substituted-5H-benzimidazo[1,2-d][1,4]benzodiazepin-6(7H)-one derivatives as anti-mycobacterial agents

Tuberculosis (TB) is one of the world's deadliest infectious diseases, caused by Mycobacterium tuberculosis (Mtb). In the present study, a 3D QSAR study was performed for the design of novel substituted benzimidazole derivatives as anti-mycobacterial agents. The anti-tubercular activity of the designed compounds was predicted using the generated 3D QSAR models. The designed compounds which showed better activity were synthesized as 1,2-disubstituted benzimidazole-5-carboxylic acid derivatives (series 1) and 3-substituted-5H-benzimidazo[1,2-d][1,4]benzodiazepin-6(7H)-one derivatives (series 2) using the liquid phase combinatorial approach using a soluble polymer assisted support (PEG5000). The compounds were characterized by ¹H-NMR, ¹³C-NMR, FTIR and mass spectrometry. HPLC analysis was carried out to evaluate the purity of the compounds. We observed that the synthesised compounds inhibited the growth of intracellular M. tuberculosis H₃₇Rv in a bactericidal manner. The most active compound 16 displayed an MIC value of 0.0975 μM against the Mtb H₃₇Rv strain in liquid cultures. The lead compound was also able to inhibit the growth of intracellular mycobacteria in THP-1 macrophages.

Immunological characteristics of Mycobacterium tuberculosis subunit vaccines immunized through different routes

Tuberculosis is chronic infectious disease caused by Mycobacterium tuberculosis (M.tb) that is prevalent worldwide. Several specific antigens, such as Antigen 85B (Ag85B) and 6 kDa early secretory antigenic target (ESAT-6) protein of M.tb, are listed as some of the candidate subunit vaccines against M.tb. ESAT-6, as a virulent factor and differential gene in M.tb, shows insufficient immunogenicity in animal model. In order to investigate the ways to improve the immunogenicity of ESAT-6, we immunized ESAT-6 by subcutaneous and intramuscular routes with different adjuvants. We found that ESAT-6 immunized alone did not induce significant humoral immunity in both immunization routes. However, subcutaneous immunization of ESAT-6 plus incomplete Freund's adjuvant can induce a significant humoral immune response, enhanced proliferation and elevated secretion of IFN-γ from splenocytes. Intramuscular immunization of ESAT-6 plus adjuvant aluminum salt or poly(I:C) did not enhance humoral and cellular immune responses. Therefore, it is concluded that immunization of ESAT-6 subcutaneously plus incomplete Freund's adjuvant induces stronger humoral and cellular immune responses, which can be considered of ESAT-6 as a subunit vaccine in further research against tuberculosis.

Identification of small molecular inhibitors for efflux protein Rv2688c of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is the pathogen, which causes tuberculosis. The development of multidrug-resistant and extensively drug-resistant strains in Mtb is due to an efflux mechanism of antibiotics in the bacteria. The efflux pump proteins in the bacteria are implicated in the active efflux of antibiotics. The efflux pump protein, "fluoroquinolones export ATP-binding protein Rv2688c" (FEAB), is considered as a potential therapeutic target to prevent tuberculosis. In the present work, in silico protocols are applied to identify inhibitors for the FEAB protein to arrest the efflux mechanism. Comparative modeling techniques are used to build the protein structure. The generated structure consists of 9 helices, 13 beta strands, and 3 β sheets. The active site is predicted using active site prediction server tools. The virtual screening protocols are carried out to generate small ligand inhibitor structures. The identified ligand molecules show selective binding with Ser97, Glu99, Lys149, Asp171, Glu172, and Ser175 amino acid residues of the protein. The ligand molecules are subjected to in silico prediction of pharmaco kinetic properties, and the predicted IC₅₀ (HERG) of all the molecules are less than -5.0, which is indicative of the identified ligand molecules is being potentially good FEAB inhibitors.

GI-19007, a Novel Saccharomyces cerevisiae-Based Therapeutic Vaccine against Tuberculosis

As yet, very few vaccine candidates with activity in animals against Mycobacterium tuberculosis infection have been tested as therapeutic postexposure vaccines. We recently described two pools of mycobacterial proteins with this activity, and here we describe further studies in which four of these proteins (Rv1738, Rv2032, Rv3130, and Rv3841) were generated as a fusion polypeptide and then delivered in a novel yeast-based platform (Tarmogen) which itself has immunostimulatory properties, including activation of Toll-like receptors. This platform can deliver antigens into both the class I and class II antigen presentation pathways and stimulate strong Th1 and Th17 responses. In mice this fusion vaccine, designated GI-19007, was immunogenic and elicited strong gamma interferon (IFN-γ) and interleukin-17 (IL-17) responses; despite this, they displayed minimal prophylactic activity in mice that were subsequently infected with a virulent clinical strain. In contrast, in a therapeutic model in the guinea pig, GI-19007 significantly reduced the lung bacterial load and reduced lung pathology, particularly in terms of secondary lesion development, while significantly improving survival in one-third of these animals. In further studies in which guinea pigs were vaccinated with BCG before challenge, therapeutic vaccination with GI-19007 initially improved survival versus that of animals given BCG alone, although this protective effect was gradually lost at around 400 days after challenge. Given its apparent ability to substantially limit bacterial dissemination within and from the lungs, GI-19007 potentially can be used to limit lung damage as well as facilitating chemotherapeutic regimens in infected individuals.