Drug development against tuberculosis: Past, present and future

Activity of Bacteriophage D29 Loaded on Nanoliposomes against Macrophages Infected with Mycobacterium tuberculosis

The search for new antimicrobial agents is a continuous struggle, mainly because more and more cases of resistant strains are being reported. Mycobacterium tuberculosis (MTB) is the main microorganism responsible for millions of deaths worldwide. The development of new antimicrobial agents is generally aimed at finding strong interactions with one or more bacterial receptors. It has been proven that bacteriophages have the ability to adhere to specific and selective regions. However, their transport and administration must be carefully evaluated as an excess could prevent a positive response and the bacteriophages may be eliminated during their journey. With this in mind, the mycobacteriophage D29 was encapsulated in nanoliposomes, which made it possible to determine its antimicrobial activity during transport and its stability in the treatment of active and latent Mycobacterium tuberculosis. The antimicrobial activity, the cytotoxicity in macrophages and fibroblasts, as well as their infection and time-kill were evaluated. Phage nanoencapsulation showed efficient cell internalization to induce MTB clearance with values greater than 90%. Therefore, it was shown that nanotechnology is capable of assisting in the activity of degradation-sensitive compounds to achieve better therapy and evade the immune response against phages during treatment.

Antimicrobial peptides as drugs with double response against Mycobacterium tuberculosis coinfections in lung cancer

Tuberculosis and lung cancer are, in many cases, correlated diseases that can be confused because they have similar symptoms. Many meta-analyses have proven that there is a greater chance of developing lung cancer in patients who have active pulmonary tuberculosis. It is, therefore, important to monitor the patient for a long time after recovery and search for combined therapies that can treat both diseases, as well as face the great problem of drug resistance. Peptides are molecules derived from the breakdown of proteins, and the membranolytic class is already being studied. It has been proposed that these molecules destabilize cellular homeostasis, performing a dual antimicrobial and anticancer function and offering several possibilities of adaptation for adequate delivery and action. In this review, we focus on two important reason for the use of multifunctional peptides or peptides, namely the double activity and no harmful effects on humans. We review some of the main antimicrobial and anti-inflammatory bioactive peptides and highlight four that have anti-tuberculosis and anti-cancer activity, which may contribute to obtaining drugs with this dual functionality.

Identification of novel anti-tuberculosis agent: An in silico investigation

BACKGROUND

Multi-drug resistance tuberculosis is chronic and highly affected to mankind. Millions of people are affected by tuberculosis and lost their lives every year. Mycobacterium tuberculosis is resistant to the most commonly used anti-TB drugs, hence new drugs need to be developed in a short time. In this direction, many chemical compounds including benzimidazole derivatives have been identified as potent anti-tb agents.

METHOD

Various benzimidazole derivatives were subjected to in-silico computational screening to identify the potent anti-tubercular analogues. The ADME pharmacokinetics evaluation was performed to identify the drug-like molecules. Molecular docking investigation of selected compounds was performed against Mycobacterium Tuberculosis Enoyl Reductase (Inha) with PDB ID: 2B37, 1QG6, 4TZK, and 4TZK. The common pharmacophore hypothesis was generated using the molecular docking post-processing module.

RESULT

The result of ADME pharmacokinetics of some compounds is very close to the drug-like properties and can be developed as good inhibitors. Molecular docking study suggests that the proposed benzimidazole and 4H-pyran derivative have better binding affinity than standard and triclosan derivatives. Results from the pharmacophore hypothesis development study also support and suggest our prediction regarding the minimum pharmacophore features required in ligands to behave as a Mycobacterium Tuberculosis inhibitor.

CONCLUSION

Coumarin, phenylurea clubbed benzimidazole moiety and pyrano[2,3-c]pyrazole derivatives have shown greater selectivity and potency towards Mycobacterium Tuberculosis. By employing a combination of ADME, docking, and pharmacophore study calculations, novel potent hits to inhibit enoyl-acp reductase were identified with the points for consideration for designing of enoyl-acp reductase inhibitor.

Tanshinone IIA alleviates NLRP3 inflammasome-mediated pyroptosis in Mycobacterium tuberculosis-(H37Ra-) infected macrophages by inhibiting endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Tanshinone IIA (Tan), extracted from Salvia miltiorrhiza Bunge, is a perennial herbal plant widely used as a folk remedy in Asian countries. Several studies have proved that Tanshinone IIA possesses many biological activities, such as anti-inflammatory, free-radical scavenging abilities, antioxidant properties, liver protection, and anti-cancer properties.

AIM OF THE STUDY

The objective of the present study was to examine the anti-inflammatory effects of Tan.

MATERIALS AND METHODS

The in vitro infection model of Mycobacterium tuberculosis-infected macrophages with the H37Ra strain was established. Murine macrophage Raw 264.7 and human monocyte THP-1 were used for the experiments. Cell viability was determined by the MTT assay. Western blot and lactate dehydrogenase (LDH) activity assays were used to detect the effects of Tan on cell pyroptosis and the level of NLRP3 inflammasome activation. Western blot, Co-immunoprecipitation and Immunofluorescence assays were used to observe the effect of Tan on the expression level of TXNIP. Immunofluorescence assays were applied to explore the effect of Tan on mtROS. Western blot and agarose gel electrophoresis were adopted to observe the effect of Tan on endoplasmic reticulum stress. The siRNA technique was applied to knockdown the expression levels of PERK/peIF2α, IRE1α and ATF6, and Western blot assay was employed to explore the NLRP3 inflammasome activation and possible molecular regulation mechanism of Tan.

RESULTS

This study demonstrated that Tan decreased Mtb-induced cell pyroptosis by measuring GSDMD-N and LDH release provoked by NLRP3 inflammasome activation. Additionally, Tan inhibited endoplasmic reticulum stress (ERS), mitochondrial damage, and TXNIP protein expression, all of which acted as upstream signals of NLRP3 inflammasome activation in Mtb-infected macrophages. Significantly, NLRP3 inflammasome activation was suppressed by knocking down ERS pathway proteins, which further clarified that Tan partly targeted ERS to exert anti-inflammatory and immunoregulatory actions.

CONCLUSION

This research confirms Tan's anti-inflammatory and immunoregulatory mechanisms in Mtb-infected macrophages by downregulating NLRP3 inflammasome activation-mediated pyroptosis provoked by ERS. Tan may function as an adjuvant drug to treat TB by adjusting host immune responses.

Cytochrome c/Multi-walled Carbon Nanotubes Modified Glassy Carbon Electrode for the Detection of Streptomycin in Pharmaceutical Samples

A novel electrochemical glassy carbon electrode modified with a multi-walled carbon nanotube, cytochrome c (Cyt c) and zinc oxide nanoparticles (ZnONPs) was fabricated to increase the sensitivity of electrode for the detection of streptomycin (STN) in certain pharmaceutical samples. Cyclic voltammetry (CV) and differential pulse voltammetry techniques were used for an electrochemical characterization of the electrode. Furthermore, the electrochemical biosensor construction phases were examined by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). Under the optimal experimental conditions, the electrode offers a high selectivity and sensitivity signaling in the co-existence method of STN with the linear concentration ranging from 0.02 to 2.2 μM. The detection limits (LOD) and limit of quantification (LOQ) were found to be 0.0028 and 0.0562 μM, respectively. The fabricated sensing electrode has good stability, reproducibility and sensitivity towards STN in the pharmaceutical samples. Preliminary determinations of binding sites within the specified grid box size, which covers both Cyt c and STN, were done by molecular docking analysis. Moreover, density functional theory (DFT) computations were performed to provide insightful information into the optimized geometry of STN.

Synthetic molecules as DprE1 inhibitors: A patent review

INTRODUCTION

In recent years, the advent of multidrug-resistant tuberculosis (MDR-TB), the extensively-resistant TB (XDR-TB), and the total drug-resistant-TB (TDR-TB) have led the community to develop new antitubercular molecules. The decaprenylphosphoryl-β-D-ribose-2'-epimerase-1 (DprE1) is an established target to developed new anti-TB drugs. This enzyme is required to synthesize the cell wall of Mycobacterium tuberculosis (Mtb).

AREA COVERED

This patent review focuses on the granted patents and patent applications related to the chemical entities developed as DprE1 inhibitors for TB treatment from the publication year of the BTZ-043 compound patent application (2007) till 30 September 2020.

EXPERT OPINION

The DprE1 has many advantages in the development of new antitubercular molecules, for example, its location in the periplasm of the Mtb cell wall and its absence in the human body. This indicates that the DprE1 inhibitors are selective for Mtb, and their toxic and side effects on the human body may be negligible or small. Accordingly, the use of DprE1 inhibitors may be benefic for patients with drug-resistant bacteria that require long-term medication. Four molecules are in clinical trials, which could become the drugs of the future for TB-therapy.

Identification of potent Antigen 85C inhibitors of Mycobacterium tuberculosis via in-house lichen library and binding free energy studies Part-II

Tuberculosis remains the cause of mortality throughout the world. Currently, the available anti-tubercular drugs are not effective because of the existence of Multi-Drug resistant tuberculosis (MDR-TB) and Extensively-Drug resistant tuberculosis (XDR-TB). It has, therefore, become necessary to develop novel drugs that inhibit the activity of drug-resistant Mycobacterium tuberculosis. Due to the existence of MDR and XDR-TB, Mtb Ag85C has risen out as a propitious molecular drug target as it has importance in the synthesis of main components of the Mtb cell envelope which are essential for the virulence and survival of Mtb. In a previous paper, we studied a potential drug target by virtual high throughput screening of compounds and in continuation of the study on Mtb Ag85C, we further studied the role of lichen compounds in the inhibition of Ag85C. In the current research work, virtual screening of a lichen compounds library was performed against Ag85C. Further, ADMET analysis was employed to filter out the screened lichen compounds. Bioactivity score and toxicity prediction finalized four lichen compounds i.e. Portentol, Aspicilin, Parietinic acid and Polyporic acid as potential inhibitors of Ag85C. The stability and dynamic behavior of four compounds were analyzed by using Molecular dynamics simulation which indicated that they may be potential inhibitors of Ag85C. Therefore, based on the above results, Portentol, Aspicilin, Parietinic acid and Polyporic acid may be potential drug candidates against Mtb. We suggest that the use of these compounds can minimize the treatment time-period and the various side effects associated with the currently available anti-tubercular drugs.

Identification of robust genes in transcriptional regulatory network of Mycobacterium tuberculosis

About 30% of the world population is infected with Mycobacterium tuberculosis (MTB). It is well known that the gene expression in MTB is highly variable, thus screening of traditional single-gene in MTB has been incapable to meet the desires of clinical diagnosis. In this report, the authors systemically analysed the transcription regulatory network (TRN) in MTB H37Rv. The complex interplay of these gene interactions has been revealed using exhaustive topological and global analysis of TRN using parameters including indegree, outdegree, degree, directed and undirected average path length (APL), and randomly performed. Results from indegree analysis reveal a set of important genes, including papA5 and Rv0177 which are associated with high indegree values. Gene ontology analysis suggested their importance in the virulence of MTB. In addition, APL and analysis of highly significant genes further identified some critical genes with different APL values. Among the list of genes identified, the csoR gene has the shortest directed APL score and high outdegree value, thus suggesting their importance in maintaining network topology. This study provides a comprehensive analysis of TRN and offers a good basis of understanding for developing experimental study in search of new therapeutic targets against MTB H37Rv pathogen.

Identification of Mycobacterium tuberculosis CtpF as a target for designing new antituberculous compounds

The emergence of tuberculosis (TB) produced by multi-drug resistance (MDR) and extensively-drug resistance (XDR) Mycobacterium tuberculosis (Mtb), encourages the development of new antituberculous compounds, as well as the identification of novel drug targets. In this regard, plasma membrane P-type ATPases are interesting targets because they play a crucial role in ion homeostasis and mycobacterial survival. We focused on Mtb CtpF, a calcium P-type ATPase that responds to a broad number of intraphagosomal conditions, as a novel target. In this study, we evaluated the capacity of cyclopiazonic acid (CPA), a well-known inhibitor of the sarco-endoplasmic reticulum Ca²⁺-ATPase (SERCA), to inhibit the ATPase activity of CtpF and the Mtb growth demonstrating that CtpF is a druggable target. A homology modeling of CtpF was generated for molecular docking studies of CtpF with CPA and key pharmacophoric features were identified, which were used to perform a pharmacophore-based virtual screening of the ZINC database, and to identify CtpF inhibitor candidates. Molecular docking-based virtual screening and MM-BGSA calculations of candidates allowed identifying six compounds with the best binding energies. The compounds displayed in vitro minimum inhibitory concentrations (MIC) ranging from 50 to 100 μg/mL, growth inhibitions from 29.5 to 64.0% on Mtb, and inhibitions of Ca²⁺-dependent ATPase activity in Mtb membrane vesicles (IC₅₀) ranging from 4.1 to 35.8 μM. The compound ZINC63908257 was the best candidate by displaying a MIC of 50 μg/mL and a Ca²⁺ P-type ATPase inhibition of 45% with IC₅₀ = 4.4 μM. Overall, the results indicate that CtpF is a druggable target for designing new antituberculous compounds.

A Therapeutic Role for the F1FO-ATP Synthase

Recently, the F₁F_O-ATP synthase, due to its dual role of life enzyme as main adenosine triphosphate (ATP) maker and of death enzyme, as ATP dissipator and putative structural component of the mitochondrial permeability transition pore (mPTP), which triggers cell death, has been increasingly considered as a drug target. Accordingly, the enzyme offers new strategies to counteract the increased antibiotic resistance. The challenge is to find or synthesize compounds able to discriminate between prokaryotic and mitochondrial F₁F_O-ATP synthase, exploiting subtle structural differences to kill pathogens without affecting the host. From this perspective, the eukaryotic enzyme could also be made refractory to macrolide antibiotics by chemically produced posttranslational modifications. Moreover, because the mitochondrial F₁F_O-ATPase activity stimulated by Ca²⁺ instead of by the natural modulator Mg²⁺ is most likely involved in mPTP formation, effectors preferentially targeting the Ca²⁺-activated enzyme may modulate the mPTP. If the enzyme involvement in the mPTP is confirmed, Ca²⁺-ATPase inhibitors may counteract conditions featured by an increased mPTP activity, such as neurodegenerative and cardiovascular diseases and physiological aging. Conversely, mPTP opening could be pharmacologically stimulated to selectively kill unwanted cells. On the basis of recent literature and promising lab findings, the action mechanism of F₁ and F_O inhibitors is considered. These molecules may act as enzyme modifiers and constitute new drugs to kill pathogens, improve compromised enzyme functions, and limit the deathly enzyme role in pathologies. The enzyme offers a wide spectrum of therapeutic strategies to fight at the molecular level diseases whose treatment is still insufficient or merely symptomatic.

Home-based Anti-Tuberculosis Treatment Adverse Reactions (HATTAR) study: a protocol for a prospective observational study

INTRODUCTION

Tuberculosis (TB) continues to be an important public health problem throughout much of the world. Drug treatment is the only effective treatment method, but adverse drug events (ADEs) and adverse drug reactions (ADRs) can affect medication adherence. As the number of drug-resistant TB patients and the number of anti-TB drugs have increased, it is necessary to explore the risk factors for ADEs/ADRs to reduce their occurrence. This study aims to build a home-based anti-TB treatment cohort and to recognise the incidences, prognosis and risk factors of anti-TB drug-induced ADEs/ADRs in real-world experiences.

METHODS AND ANALYSIS

This study is a multicentre, prospective observational cohort study. The study population will consist of 3200 newly diagnosed TB patients between January 2019 and December 2020. After initiating the anti-TB treatment, all patients will be followed up until finishing treatment unless they withdraw, and we will record personal drug use and signs and/or symptoms of discomfort. Patients will receive scheduled laboratory tests in designated hospitals every 2 weeks during the first 2 months, and the residual blood sample after conducting the laboratory tests will be preserved. The ADEs/ADRs will be placed into eight categories: liver dysfunction, gastrointestinal reactions, drug allergy, arthralgia or muscle pain, nervous system disorders, haematological system disorders, renal impairment and others.

ETHICS AND DISSEMINATION

This study protocol has been approved by the ethics committees of Nanjing Medical University. All patients will give written informed consent before enrollment. The findings of the study will be published in peer-reviewed journals and will be presented at national and international conferences.

Drug-susceptible tuberculosis treatment success and associated factors in Ethiopia from 2005 to 2017: a systematic review and meta-analysis

OBJECTIVES

The main aim of this study was to assess the overall tuberculosis (TB) treatment success in Ethiopia and to identify potential factors for poor TB treatment outcome.

DESIGN

A systematic review and meta-analysis of published literature was conducted. Original studies were identified through a computerised systematic search using PubMed, Google Scholar and Science Direct databases. Heterogeneity across studies was assessed using Cochran's Q test and I² statistic. Pooled estimates of treatment success were computed using the random-effects model with 95% CI using Stata V.14 software.

RESULTS

A total of 230 articles were identified in the systematic search. Of these 34 observational studies were eligible for systematic review and meta-analysis. It was found that 117 750 patients reported treatment outcomes. Treatment outcomes were assessed by World Health Organization (WHO) standard definitions of TB treatment outcome. The overall pooled TB treatment success rate in Ethiopia was 86% (with 95% CI 83%_88%). TB treatment success rate for each region showed that, Addis Ababa (93%), Oromia (84%), Amhara (86%), Southern Nations (83%), Tigray (85%) and Afar (86%). Mainly old age, HIV co-infection, retreatment cases and rural residence were the most frequently identified factors associated with poor TB treatment outcome.

CONCLUSION

The result of this study revealed that the overall TB treatment success rate in Ethiopia was below the threshold suggested by WHO (90%). There was also a discrepancy in TB treatment success rate among different regions of Ethiopia. In addition to these, HIV co-infection, older age, retreatment cases and rural residence were associated with poor treatment outcome. In order to further improve the treatment success rate, it is strategic to give special consideration for regions which had low TB treatment success and patients with TB with HIV co-infection, older age, rural residence and retreatment cases.

Discovery of novel anti-tuberculosis agents with pyrrolo[1,2-a]quinoxaline-based scaffold

A series of small molecules with novel pyrrolo[1,2-a]quinoxaline-based scaffold was designed via molecular hybridization of privileged agents active against Mycobacterium tuberculosis. Twenty-three compounds were synthesized and investigated for their antitubercular activities in vitro where ten compounds showed appreciable activities and moderate cytotoxicity. Compound 12g with MIC values of 5 μg/ml as a representative may possess better oral bioavailability and indicated high permeability by the parallel artificial membrane permeation assay of the blood-brain barrier (PAMPA-BBB). Further, the determination of enzyme inhibition and molecular docking study indicated that InhA may be the biological target of the active compounds. The results suggest the pyrrolo[1,2-a]quinoxaline hybrids as potential antitubercular leads for the development of new antitubercular agents.

Data Mining Mycobacterium tuberculosis Pathogenic Gene Transcription Factors and Their Regulatory Network Nodes

Tuberculosis (TB) is one of the deadliest infectious diseases worldwide. In Mycobacterium tuberculosis, changes in gene expression are highly variable and involve many genes, so traditional single-gene screening of M. tuberculosis targets has been unable to meet the needs of clinical diagnosis. In this study, using the National Center for Biotechnology Information (NCBI) GEO Datasets, whole blood gene expression profile data were obtained in patients with active pulmonary tuberculosis. Linear model-experience Bayesian statistics using the Limma package in R combined with t-tests were applied for nonspecific filtration of the expression profile data, and the differentially expressed human genes were determined. Using DAVID and KEGG, the functional analysis of differentially expressed genes (GO analysis) and the analysis of signaling pathways were performed. Based on the differentially expressed gene, the transcriptional regulatory element databases (TRED) were integrated to construct the M. tuberculosis pathogenic gene regulatory network, and the correlation of the network genes with disease was analyzed with the DAVID online annotation tool. It was predicted that IL-6, JUN, and TP53, along with transcription factors SRC, TNF, and MAPK14, could regulate the immune response, with their function being extracellular region activity and protein binding during infection with M. tuberculosis.

Identification and development of benzoxazole derivatives as novel bacterial glutamate racemase inhibitors

In the present study, we attempted to develop novel class of Mycobacterium tuberculosis (Mtb) inhibitors by exploring the pharmaceutically underexploited enzyme targets which are majorly involved in cell wall biosynthesis of mycobacteria. For this purpose glutamate racemase was selected which racemizes d-glutamate from l-glutamate, a key step in peptidoglycan synthesis. Furthermore, enzyme is neither expressed nor its product, d-glutamate is produced in mammals, and hence inhibiting this enzyme will have no vulnerable effect in host organism. A library of our in-house compounds were screened against glutamate racemase using a biophysical technique; thermal shift assay and further by enzyme inhibition assay to identify Lead 1 molecule. Lead 1 optimization and expansion resulted in twenty four compounds. Among the synthesized compounds twelve compounds shown good enzyme inhibition than Lead 1 (IC₅₀ 20.07 ± 0.29 μM). Among all the compounds; compound 22 (IC₅₀ 1.1 ± 0.52 μM) showed potent non-competitive mode of inhibition in enzyme assay. Further showed good susceptibility (in replicating bacteria) of MIC 8.72 μM and bactericidal time dependant kill on dormant culture. It also exhibited significant activity in Mtb nutrient starvation model (2.5) and Mtb biofilm model (2.4) and in vivo M. marinum infected Zebra fish model studies (3.6) reduction at logarithmic scale.