Tuberculosis--advances in development of new drugs, treatment regimens, host-directed therapies, and biomarkers

Discovery of novel pyrimidinetrione derivatives as DprE1 inhibitors with potent antimycobacterial activities

Tuberculosis (TB) is one of the ten major factors threatening human life and health. At present, many factors limit the application of existing anti-tuberculosis drugs, such as a small range of available drug options, poor treatment compliance, and severe toxic and side effects. It is extremely urgent to develop novel anti-tuberculosis drugs. DprE1 is a potential anti-mycobacterial cell wall target, and some DprE1 inhibitors have entered the clinical research stage. Our research group found DprE1 inhibitor G50 with similar activity as isoniazid through virtual screening in the early stage. To obtain better DprE1 inhibitors, 45 new compounds were designed and synthesized based on the structure of G50. Among them, 12 selected DprE1 enzyme inhibitors could significantly inhibit the growth of Mycobacterium tuberculosis (M.tb) H37Ra and H37Rv growth in vitro. The MIC50 value of compound 42 against M.tb H37Ra is 1.071 ± 0.041 μM, with the selective index (SI) value of 186.74 (the SI value of linezolid is 119.9). Compared to G50, compound 42 exhibits a 5-fold increase in DprE1 enzyme inhibitory activity. In addition, the binding affinity of compound 42 is equivalent to that of G50. This study further enriches the examples of developing DprE1 inhibitors based on the backbone of pyrimidinetrione and also provides potential anti-tuberculosis lead compounds.

Sesamol hinders the proliferation of intracellular bacteria by promoting fatty acid metabolism and decreasing excessive inflammation

The extraintestinal pathogenic Escherichia coli (ExPEC) is a significant zoonotic bacterial pathogen that can cause severe infections and potentially cross-transmit between different hosts. The treatment of clinical bacterial infections is challenging because of the increasingly severe problem of drug resistance. The development of new strategies for managing bacterial infections is essential. Host-acting antibacterial compound (HAC)-based host-directed therapy (HDT) has emerged as a promising approach to combat bacterial infections by targeting host-pathogen interactions and bacterial intracellular survival strategies. In this study, we conducted a cell-based screening to identify compounds that can inhibit the survival and proliferation of ExPEC within host cells. Our screening revealed that sesamol effectively inhibited ExPEC proliferation but had no effect on the natural growth of bacteria. Analysis of the transcriptome data revealed that sesamol has the ability to increase the metabolism of host fatty acids while also suppressing excessive inflammation. Mechanistic studies have shown that sesamol-induced PPAR-β activation is crucial for increased fatty acid metabolism and clearance of intracellular bacteria. Furthermore, sesamol treatment demonstrated protective effects against ExPEC infection in both Galleria mellonella and mouse models, suggesting its potential use for treating diseases caused by intracellular bacterial pathogens and as a lead compound for further development of anti-infection drugs on the basis of the HDT strategy.

Cryo-EM structure of the Mycobacterium smegmatis MmpL5-AcpM complex

Mycobacterium tuberculosis, the causative agent of the airborne infection tuberculosis (TB), contains 13 mycobacterial membrane protein large (MmpL) transporters that can be divided into two distinct subclasses. These MmpL proteins play important functional roles within the mycobacterium and subsequently are considered attractive drug targets to combat TB infection. Previously, we reported both X-ray and cryo-electron microscopy (cryo-EM) structures of the MmpL3 transporter, providing high-resolution structural information for this subclass of the MmpL proteins. Thus far, there is no structural information available for the other subclass, which includes MmpL5, an inner membrane transporter that plays a critical role in iron hemostasis. Here, we report the first cryo-EM structure of the Mycobacterium smegmatis MmpL5 transporter bound with the meromycolate extension acyl carrier protein M (AcpM) to a resolution of 2.81 Å. Our structural data reveals that MmpL5 and AcpM interact in the cytoplasm to form a complex, and this allows us to propose that MmpL5 may also associate with the mycobactin L (MbtL) protein in a similar fashion to form a heterocomplex important for iron acquisition, which enables the survival and replication of the mycobacterium.

IMPORTANCE

The emergence and spread of multidrug-resistant tuberculosis (TB) present enormous challenges to the global public health. The causative agent, Mycobacterium tuberculosis, has now infected more than one-third of the world's population. Here, we report the first structure of the mycobacterial membrane protein large 5 (MmpL5), an essential transporter for iron acquisition, bound with the meromycolate extension acyl carrier protein M (AcpM), indicating a plausible pathway for mycobactin translocation. Our studies will ultimately inform an era in structure-guided drug design to combat TB infection.

Nanoparticles target M2 macrophages to silence kallikrein-related peptidase 12 for the treatment of tuberculosis and drug-resistant tuberculosis

Matrix metalloproteinases (MMPs) are involved in the breakdown of lung extracellular matrix and the consequent release of Mycobacterium tuberculosis into the airways. Recent studies indicate that kallikrein-related peptidase 12 (KLK12) regulate MMP-1 and MMP-9, suggesting that targeting the KLK12 gene could be a promising tuberculosis (TB) treatment. To maximise therapeutic potential, this strategy of silencing KLK12 needs to be delivered to the pathogenic cell population while preserving the immunoprotective and tissue homeostatic functions of other lung macrophages. Our research found that KLK12 is highly expressed in M2 macrophages, leading us to design mannose-based bovine serum albumin nanoparticles (MBNPs) for delivering siRNA to silence KLK12 in these cells. The results of in vitro experiments showed that MBNPs could accurately enter M2 macrophages and sustainably release KLK12-siRNA with the help of mannose and mannose receptor targeting. The results of the in vivo experiments showed that MBNPs could reach the lungs within 1 h after intraperitoneal injection and peaked at 6 h. MBNPs increased collagen fibre content in the lungs by decreasing the levels of KLK12/MMPs thereby limiting the progression of TB. Importantly, MBNPs provided greater alleviation of pulmonary TB symptoms and reduced bacterial load in both TB and drug-resistant TB models. These findings provide an alternative and effective option for the treatment of TB, especially when drug resistance occurs. STATEMENT OF SIGNIFICANCE: RNA interference using small interfering RNA (siRNA) can target various genes and has potential for treating diseases such as tuberculosis (TB). However, siRNAs are unstable in the blood and within cells. This study presents bovine serum albumin nanoparticles encapsulating KLK12-siRNA (BNPs) synthesized via desolvation. A mannose layer was added (MBNPs) to target mannose receptors on M2 macrophages, facilitating endocytosis. The low pH-responsive MBNPs enhance lysosomal escape for siRNA delivery, downregulating the KLK12 pathway. Tests confirmed that MBNPs effectively inhibited Mycobacterium bovis proliferation, reduced granulomas, and decreased inflammation in a mouse model. This research aims to reduce antibiotic use, shorten treatment duration, and provide a novel TB treatment option.

Structures of the mycobacterial MmpL4 and MmpL5 transporters provide insights into their role in siderophore export and iron acquisition

The Mycobacterium tuberculosis (Mtb) pathogen, the causative agent of the airborne infection tuberculosis (TB), harbors a number of mycobacterial membrane protein large (MmpL) transporters. These membrane proteins can be separated into 2 distinct subclasses, where they perform important functional roles, and thus, are considered potential drug targets to combat TB. Previously, we reported both X-ray and cryo-EM structures of the MmpL3 transporter, providing high-resolution structural information for this subclass of the MmpL proteins. Currently, there is no structural information available for the subclass associated with MmpL4 and MmpL5, transporters that play a critical role in iron homeostasis of the bacterium. Here, we report cryo-EM structures of the M. smegmatis MmpL4 and MmpL5 transporters to resolutions of 2.95 Å and 3.00 Å, respectively. These structures allow us to propose a plausible pathway for siderophore translocation via these 2 transporters, an essential step for iron acquisition that enables the survival and replication of the mycobacterium.

Alternative therapies against Mycobacterium abscessus infections

BACKGROUND

Mycobacterium abscessus (Mab) is considered as the most pathogenic rapid-growing mycobacteria in humans, causing pulmonary and extra-pulmonary diseases, especially in patients with cystic fibrosis. Mab shows intrinsic and acquired resistance to many drugs, leaving limited treatment options that lead to a generally poor prognosis. The standard therapeutic regimen last for more than 6 months and consists of a drug cocktail that ideally includes a macrolide and amikacin. Yet, toxicity and efficacy are suboptimal due also to the high toxicity. There is a need to introduce innovative and out-of-the-box approaches to improve treatments.

OBJECTIVES

In this narrative review, we summarize the recent research on the alternative strategies proposed and discuss the importance of using appropriate experimental assays to assess their activity.

SOURCES

Included articles were identified by searching PubMed and MEDLINE until June 2023. The search terms were 'Mycobacterium abscessus', 'antimicrobial', and 'alternative therapies'. Additional relevant references were obtained from articles retrieved from the primary search.

CONTENT

Therapies against Mab including host directed therapies, repurposed drugs, phage therapy, anti-virulence strategies, essential oils, and inhalation therapies.

IMPLICATIONS

Alternative treatments may represent a valid tool to cope the burden of antimicrobial resistance in Mab-caused diseases.

Understanding the Spectrum and Management of Post-Tuberculosis Lung Disease: A Comprehensive Review

Post-tuberculosis lung disease (PTLD) poses a significant clinical challenge in regions with a high burden of tuberculosis (TB). This review provides a comprehensive overview of PTLD, encompassing its pathogenesis, clinical manifestations, diagnostic modalities, management strategies, long-term outcomes, and public health implications. PTLD arises from residual lung damage following TB treatment and is characterized by a spectrum of pathological changes, including fibrosis, bronchiectasis, and cavitation. Clinical presentation varies widely, from chronic cough and hemoptysis to recurrent respiratory infections, which are oftentimes a diagnostic dilemma. Radiological imaging, pulmonary function tests, and careful consideration of patient history play pivotal roles in diagnosis. Management strategies involve pharmacological interventions to alleviate symptoms and prevent disease progression, which are influenced by the extent of lung damage, comorbidities, and access to healthcare. Rehabilitation programs and surgical options are available for select cases. Prognosis is influenced by the extent of lung damage, comorbidities, and access to healthcare. Prevention efforts through a TB control program and early detection are crucial in reducing the burden of PTLD. This review stresses the importance of understanding and addressing PTLD to mitigate its impact on individuals and public health systems worldwide.

Incidence, Outcomes, and Risk Factors for Isoniazid-Resistant Tuberculosis from 2012 to 2022 in Eastern China

BACKGROUND

Isoniazid-resistant, rifampicin-susceptible tuberculosis (Hr-TB) is the most frequent drug-resistant tuberculosis (DR-TB) in the world, and unfavorable outcomes of Hr-TB are more common compared to drug-susceptible TB. Considering there is no optimal regimen accepted worldwide, we undertook a retrospective cohort study in eastern China to estimate incidence trends and risk factors associated with unfavorable outcomes of Hr-TB.

METHODS

Between January 2012 and December 2022, all Hr-TB patients' information was extracted from the Tuberculosis Information Management System (TIMS), which is a national electronic information platform, to record TB patients' clinical information in this study. The incidence of Hr-TB was determined by the mid-year population according to census data published by the government. We categorized treatment regimens depending on fluoroquinolone (FQ) use, and potential risk factors were analyzed using multivariable logistic regression.

RESULTS

A total of 3116 Hr-TB patients fulfilled the inclusion criteria and were enrolled in this study. The average annual rate of Hr-TB in the 11 years under investigation was 0.34 per 100,000 and increased to 0.53 per 100,000 until 2019. In total, six different treatment regimens were utilized in the study sites, and less than 1% of regimens adopted FQ. There was no difference in the unfavorable outcomes between the FQ-included and FQ-excluded groups (p = 0.22). The average treatment duration was 7.06 months, and the longest treatment was 26 months. Approximately 20% (637/3116) of Hr-TB patients had unfavorable outcomes, and 60.13% (383/637) of them proceeded to multidrug-resistant tuberculosis (MDR-TB). Treatment duration and a positive smear at the end of the 5th month were significantly associated with unfavorable outcomes (p < 0.001).

CONCLUSION

The unfavorable treatment outcomes of Hr-TB are still high in eastern China, and the efficacy of FQ-containing regimens needs to be validated for Hr-TB treatment.

Activities of Daily Living, Hypoxemia, and Lymphocytes Score for Predicting Mortality Risk in Patients With Pulmonary TB

BACKGROUND

A clinically applicable mortality risk prediction system for pulmonary TB may improve treatment outcomes, but no easy-to-calculate and accurate score has yet been reported. The aim of this study was to construct a simple and objective disease severity score for patients with pulmonary TB.

RESEARCH QUESTION

Does a clinical score consisting of simple objective factors predict the mortality risk of patients with pulmonary TB?

STUDY DESIGN AND METHODS

The data set from our previous prospective study that recruited patients newly diagnosed with pulmonary TB was used for the development cohort. Patients for the validation cohort were prospectively recruited between March 2021 and September 2022. The primary end point was all-cause in-hospital mortality. Using Cox proportional hazards regression, a mortality risk prediction model was optimized in the development cohort. The disease severity score was developed by assigning integral points to each variate.

RESULTS

The data from 252 patients in the development cohort and 165 patients in the validation cohort were analyzed, of whom 39 (15.5%) and 17 (10.3%), respectively, died in the hospital. The disease severity score (named the AHL score) included three clinical parameters: activities of daily living (semi-dependent, 1 point; totally dependent, 2 points); hypoxemia (1 point), and lymphocytes (< 720/μL, 1 point). This score showed good discrimination with a C statistic of 0.902 in the development cohort and 0.842 in the validation cohort. We stratified the score into three groups (scores of 0, 1-2, and 3-4), which clearly corresponded to low (0% and 1.3%), intermediate (13.5% and 8.9%), and high (55.8% and 39.3%) mortality risk in the development and validation cohorts.

INTERPRETATION

The easy-to-calculate AHL disease severity score for patients with pulmonary TB was able to categorize patients into three mortality risk groups with great accuracy.

CLINICAL TRIAL REGISTRATION

University Hospital Medical Information Network Center; No. UMIN000012727 and No. UMIN000043849; URL: www.umin.ac.jp.

Natural products in anti-tuberculosis host-directed therapy

Given that the disease progression of tuberculosis (TB) is primarily related to the host's immune status, it has been gradually realized that chemotherapy that targets the bacteria may never, on its own, wholly eradicate Mycobacterium tuberculosis, the causative agent of TB. The concept of host-directed therapy (HDT) with immune adjuvants has emerged. HDT could potentially interfere with infection and colonization by the pathogens, enhance the protective immune responses of hosts, suppress the overwhelming inflammatory responses, and help to attain a state of homeostasis that favors treatment efficacy. However, the HDT drugs currently being assessed in combination with anti-TB chemotherapy still face the dilemmas arising from side effects and high costs. Natural products are well suited to compensate for these shortcomings by having gentle modulatory effects on the host immune responses with less immunopathological damage at a lower cost. In this review, we first summarize the profiles of anti-TB immunology and the characteristics of HDT. Then, we focus on the rationale and challenges of developing and implementing natural products-based HDT. A succinct report of the medications currently being evaluated in clinical trials and preclinical studies is provided. This review aims to promote target-based screening and accelerate novel TB drug discovery.

Inflammatory immune profiles associated with disease severity in pulmonary tuberculosis patients with moderate to severe clinical TB or anemia

Background

Immune control of Mycobacterium tuberculosis (Mtb) infection is largely influenced by the extensive disease heterogeneity that is typical for tuberculosis (TB). In this study, the peripheral inflammatory immune profile of different sub-groups of pulmonary TB patients was explored based on clinical disease severity, anemia of chronic disease, or the radiological extent of lung disease.

Methods

Plasma samples were obtained from n=107 patients with active pulmonary TB at the time of diagnosis and after start of standard chemotherapy. A composite clinical TB symptoms score, blood hemoglobin status and chest X-ray imaging were used to sub-group TB patients into 1.) mild and moderate-severe clinical TB, 2.) anemic and non-anemic TB, or 3.) limited and extensive lung involvement. Plasma levels of biomarkers associated with inflammation pathways were assessed using a Bio-Plex Magpix 37-multiplex assay. In parallel, Th1/Th2 cytokines were quantified with a 27-multiplex in matched plasma and cell culture supernatants from whole blood stimulated with M. tuberculosis-antigens using the QuantiFERON-TB Gold assay.

Results

Clinical TB disease severity correlated with low blood hemoglobin levels and anemia but not with radiological findings in this study cohort. Multiplex protein analyses revealed that distinct clusters of inflammation markers and cytokines separated the different TB disease sub-groups with variable efficacy. Several top-ranked markers overlapped, while other markers were unique with regards to their importance to differentiate the TB disease severity groups. A distinct immune response profile defined by elevated levels of BAFF, LIGHT, sTNF-R1 and 2, IP-10, osteopontin, chitinase-3-like protein 1, and IFNα2 and IL-8, were most effective in separating TB patients with different clinical disease severity and were also promising candidates for treatment monitoring. TB patients with mild disease displayed immune polarization towards mixed Th1/Th2 responses, while pro-inflammatory and B cell stimulating cytokines as well as immunomodulatory mediators predominated in moderate-severe TB disease and anemia of TB.

Conclusions

Our data demonstrated that clinical disease severity in TB is associated with anemia and distinct inflammatory immune profiles. These results contribute to the understanding of immunopathology in pulmonary TB and define top-ranked inflammatory mediators as biomarkers of disease severity and treatment prognosis.

Mechanisms of lung damage in tuberculosis: implications for chronic obstructive pulmonary disease

Pulmonary tuberculosis is increasingly recognized as a risk factor for COPD. Severe lung function impairment has been reported in post-TB patients. Despite increasing evidence to support the association between TB and COPD, only a few studies describe the immunological basis of COPD among TB patients following successful treatment completion. In this review, we draw on well-elaborated Mycobacterium tuberculosis-induced immune mechanisms in the lungs to highlight shared mechanisms for COPD pathogenesis in the setting of tuberculosis disease. We further examine how such mechanisms could be exploited to guide COPD therapeutics.

Cisatracurium besylate rescues Mycobacterium Tuberculosis-infected macrophages from necroptosis and enhances the bactericidal effect of isoniazid

OBJECTIVE

Tuberculosis is the leading killer among the chronic single-source infectious diseases. Mycobacterium tuberculosis can induce necrotic-dominant multiple modes of cell death in macrophages, which accelerates bacterium dissemination and expands tissue injury in host lungs. Mining drugs to counteract Mycobacterium tuberculosis-induced cell death would be beneficial to tuberculosis patients.

METHODS

In this study, the protective drug was screened out from the FDA-approved drug library in Mycobacterium tuberculosis-infected macrophages with CCK-8 assay. The death mode regulated by the drug was identified using transcriptomic sequencing, cytomorphological observation, and in the experimental mouse Mycobacterium tuberculosis-infection model. The functional mechanism was explored using western blot, co-immunoprecipitation, and DARTS assay. The intracellular bacterial survival was detected using colony forming unit assays.

RESULTS

Cisatracurium besylate was identified to be highly protective for the viability of macrophages during Mycobacterium tuberculosis infection via inhibiting necroptosis. Cisatracurium besylate prevented RIPK3 to be associated with the executive molecule MLKL for forming the necroptotic complex, resulting in the inhibition of MLKL phosphorylation and pore formation on cell membrane. However, Cisatracurium besylate did not interfere with the association between RIPK3 with its upstream kinase RIPK1 or ZBP1 but regulated RIPK3 autophosphorylation. Moreover, Cisatracurium besylate significantly inhibited the expansion of intracellular Mycobacterium tuberculosis both in vitro and in vivo, which also displayed a strong auxiliary bacteriostatic effect to support the therapeutic efficacy of isoniazid and rifampicin, the first-line anti-tubercular drugs.

CONCLUSION

Cisatracurium besylate performs anti-Mycobacterium tuberculosis and anti-necroptotic roles, which potentiates its application to be an adjuvant drug for antituberculosis therapy to assist the battle against drug-resistant tuberculosis.

Synthesis, biological evaluation and molecular docking study of some new 4-aminosalicylic acid derivatives as anti-inflammatory and antimycobacterial agents

In this study, new derivatives of the antitubercular and anti-inflammatory drug, 4-aminosaliclic acids (4-ASA) were synthesized, characterized, and evaluated for these activities. In vivo and in viro evaluation of anti-inflammatory activity revealed that compounds 10, 19 and 20 are the most active with potent cyclooxygenase-2 (COX-2) and 5-lipooxgenase (5-LOX) inhibition and without causing gasric lesions. The minimum inhibitory concentrations (MIC) of the newly synthesized compound were, also, measured against Mycobacterium tuberculosis H37RV. Among the tested compounds 17, 19 and 20 exhibited significant activities against the growth of M. tuberculosis. 20 is the most potent with (MIC 1.04 µM) 2.5 folds more potent than the parent drug 4-ASA. 20 displayed low cytotoxicity against normal cell providing a high therapeutic index. Important structure features were analyzed by docking and structure-activity relationship analysis to give better insights into the structural determinants for predicting the anti-inflammatory and anti-TB activities. Our results indicated that compounds 19 and 20 are potential lead compounds for the discovery of dual anti-inflammatory and anti-TB drug candidates.

Surveillance of Daughter Micronodule Formation Is a Key Factor for Vaccine Evaluation Using Experimental Infection Models of Tuberculosis in Macaques

Tuberculosis (TB) is still a major worldwide health problem and models using non-human primates (NHP) provide the most relevant approach for vaccine testing. In this study, we analysed CT images collected from cynomolgus and rhesus macaques following exposure to ultra-low dose Mycobacterium tuberculosis (Mtb) aerosols, and monitored them for 16 weeks to evaluate the impact of prior intradermal or inhaled BCG vaccination on the progression of lung disease. All lesions found (2553) were classified according to their size and we subclassified small micronodules (<4.4 mm) as 'isolated', or as 'daughter', when they were in contact with consolidation (described as lesions ≥ 4.5 mm). Our data link the higher capacity to contain Mtb infection in cynomolgus with the reduced incidence of daughter micronodules, thus avoiding the development of consolidated lesions and their consequent enlargement and evolution to cavitation. In the case of rhesus, intradermal vaccination has a higher capacity to reduce the formation of daughter micronodules. This study supports the 'Bubble Model' defined with the C3HBe/FeJ mice and proposes a new method to evaluate outcomes in experimental models of TB in NHP based on CT images, which would fit a future machine learning approach to evaluate new vaccines.

Optimized LC-MS/MS quantification of tuberculosis drug candidate macozinone (PBTZ169), its dearomatized Meisenheimer Complex and other metabolites, in human plasma and urine

Tuberculosis, and especially multidrug-resistant tuberculosis (MDR-TB), is a major global health threat which emphasizes the need to develop new agents to improve and shorten treatment of this difficult-to-manage infectious disease. Among the new agents, macozinone (PBTZ169) is one of the most promising candidates, showing extraordinary potency in vitro and in murine models against drug-susceptible and drug-resistant Mycobacterium tuberculosis. A previous analytical method using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed by our group to support phase I clinical trials of PBTZ169. These plasma sample analyses revealed the presence of several additional metabolites among which the most prominent was H₂PBTZ, a reduced species obtained by dearomatization of macozinone, one of the first examples of Meisenheimer Complex (MC) metabolites identified in mammals. Identification of these new metabolites required the optimization of our original method for enhancing the selectivity between isobaric metabolites as well as for ensuring optimal stability for H₂PBTZ analyses. Sample preparation methods were also developed for plasma and urine, followed by extensive quantitative validation in accordance with international bioanalytical method recommendations, which include selectivity, linearity, qualitative and quantitative matrix effect, trueness, precision and the establishment of accuracy profiles using β-expectation tolerance intervals for known and newer analytes. The newly optimized methods have been applied in a subsequent Phase Ib clinical trial conducted in our University Hospital with healthy subjects. H₂PBTZ was found to be the most abundant species circulating in plasma, underscoring the importance of measuring accurately and precisely this unprecedented metabolite. Low concentrations were found in urine for all monitored analytes, suggesting extensive metabolism before renal excretion.

Cysteamine/Cystamine Exert Anti-Mycobacterium abscessus Activity Alone or in Combination with Amikacin

Host-directed therapies are emerging as a promising tool in the curing of difficult-to-treat infections, such as those caused by drug-resistant bacteria. In this study, we aim to test the potential activity of the FDA- and EMA-approved drugs cysteamine and cystamine against Mycobacterium abscessus. In human macrophages (differentiated THP-1 cells), these drugs restricted M. abscessus growth similar to that achieved by amikacin. Here, we use the human ex vivo granuloma-like structures (GLS) model of infection with the M. abscessus rough (MAB-R) and smooth (MAB-S) variants to study the activity of new therapies against M. abscessus. We demonstrate that cysteamine and cystamine show a decrease in the number of total GLSs per well in the MAB-S and MAB-R infected human peripheral blood mononuclear cells (PBMCs). Furthermore, combined administration of cysteamine or cystamine with amikacin resulted in enhanced activity against the two M. abscessus morpho variants compared to treatment with amikacin only. Treatment with cysteamine and cystamine was more effective in reducing GLS size and bacterial load during MAB-S infection compared with MAB-R infection. Moreover, treatment with these two drugs drastically quenched the exuberant proinflammatory response triggered by the MAB-R variant. These findings showing the activity of cysteamine and cystamine against the R and S M. abscessus morphotypes support the use of these drugs as novel host-directed therapies against M. abscessus infections.

Chitinase and indoleamine 2, 3-dioxygenase are prognostic biomarkers for unfavorable treatment outcomes in pulmonary tuberculosis

Introduction

Chitinase, Indoleamine 2,3-dioxygenesae-1 (IDO-1) and heme oxygenase-1 (HO-1) are candidate diagnostic biomarkers for tuberculosis (TB). Whether these immune markers could also serve as predictive biomarkers of unfavorable treatment outcomes in pulmonary TB (PTB) is not known.

Methods

A cohort of newly diagnosed, sputum culture-positive adults with drug-sensitive PTB were recruited. Plasma chitinase protein, IDO protein and HO-1 levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 108 control individuals who had recurrence-free cure.

Results

Plasma chitinase and IDO protein levels but not HO-1 levels were lower in cases compared to controls. The low chitinase and IDO protein levels were associated with increased risk of unfavourable outcomes in unadjusted and adjusted analyses. Receiver operating characteristic analysis revealed that chitinase and IDO proteins exhibited high sensitivity and specificity in differentiating cases vs controls as well as in differentiating treatment failure vs controls and recurrence vs controls, respectively. Classification and regression trees (CART) were used to determine threshold values for these two immune markers.

Discussion

Our study revealed a plasma chitinase and IDO protein signature that may be used as a tool for predicting adverse treatment outcomes in PTB.

Potential Use of Mycobacterium paragordonae for Antimycobacterial Drug Screening Systems

Our recent genome-based study indicated that Mycobacterium paragordonae (Mpg) has evolved to become more adapted to an intracellular lifestyle within free-living environmental amoeba and its enhanced intracellular survival within Acanthamoeba castellanii was also proved. Here, we sought to investigate potential use of Mpg for antimycobacterial drug screening systems. Our data showed that Mpg is more susceptible to various antibiotics compared to the close species M. marinum (Mmar) and M. gordonae, further supporting its intracellular lifestyle in environments, which would explain its protection from environmental insults. In addition, we developed two bacterial whole-cell-based drug screening systems using a recombinant Mpg stain harboring a luciferase reporter vector (rMpg-LuxG13): one for direct application to rMpg-LuxG13 and the other for drug screening via the interaction of rMpg-LuxG13 with A. castellanii. Direct application to rMpg-LuxG13 showed lower inhibitory concentration 50 (IC50) values of rifampin, isoniazid, clarithromycin, and ciprofloxacin against Mpg compared to Mmar. Application of drug screening system via the interaction of rMpg-LuxG13 with A. castellanii also exhibited lower IC50 values for rifampin against Mpg compared to Mmar. In conclusion, our data indicate that Mpg is more susceptible to various antibiotics than other strains. In addition, our data also demonstrate the feasibility of two whole cell-based drug screening systems using rMpg-LuxG13 strain for the discovery of novel anti-mycobacterial drugs.

Gene expression profiling identifies candidate biomarkers for new latent tuberculosis infections. A cohort study

Objective

To determine the gene expression profile in individuals with new latent tuberculosis infection (LTBI), and to compare them with people with active tuberculosis (TB) and those exposed to TB but not infected.

Design

A prospective cohort study. Recruitment and follow-up were conducted between September 2016 to December 2018. Gene expression and data processing and analysis from April 2019 to April 2021.

Setting

Two male Colombian prisons.

Participants

15 new tuberculin skin test (TST) converters (negative TST at baseline that became positive during follow-up), 11 people that continued with a negative TST after two years of follow-up, and 10 people with pulmonary ATB.

Main outcome measures

Gene expression profile using RNA sequencing from PBMC samples. The differential expression was assessed using the DESeq2 package in Bioconductor. Genes with |logFC| >1.0 and an adjusted p-value < 0.1 were differentially expressed. We analyzed the differences in the enrichment of KEGG pathways in each group using InterMiner.

Results

The gene expression was affected by the time of incarceration. We identified group-specific differentially expressed genes between the groups: 289 genes in people with a new LTBI and short incarceration (less than three months of incarceration), 117 in those with LTBI and long incarceration (one or more years of incarceration), 26 in ATB, and 276 in the exposed but non-infected individuals. Four pathways encompassed the largest number of down and up-regulated genes among individuals with LTBI and short incarceration: cytokine signaling, signal transduction, neutrophil degranulation, and innate immune system. In individuals with LTBI and long incarceration, the only enriched pathway within up-regulated genes was Emi1 phosphorylation.

Conclusions

Recent infection with MTB is associated with an identifiable RNA pattern related to innate immune system pathways that can be used to prioritize LTBI treatment for those at greatest risk for developing active TB.

Tuberculosis Treatment Monitoring and Outcome Measures: New Interest and New Strategies

Despite the advent of new diagnostics, drugs and regimens, tuberculosis (TB) remains a global public health threat. A significant challenge for TB control efforts has been the monitoring of TB therapy and determination of TB treatment success. Current recommendations for TB treatment monitoring rely on sputum and culture conversion, which have low sensitivity and long turnaround times, present biohazard risk, and are prone to contamination, undermining their usefulness as clinical treatment monitoring tools and for drug development. We review the pipeline of molecular technologies and assays that serve as suitable substitutes for current culture-based readouts for treatment response and outcome with the potential to change TB therapy monitoring and accelerate drug development.

Immunologic and imaging signatures in post tuberculosis lung disease

Post Tuberculosis Lung Disease (PTLD) affects millions of tuberculosis survivors and is a global health burden. The immune mechanisms that drive PTLD are complex and have historically been under investigated. Here, we discuss two immune-mediated paradigms that could drive human PTLD. We review the characteristics of a fibrotic granuloma that favors the development of PTLD via an abundance of T-helper-2 and T-regulatory cells and an upregulation of TGF-β mediated collagen deposition. Next, we discuss the post-primary tuberculosis paradigm and the complex mixture of caseous pneumonia, cavity formation and fibrosis that can also lead to PTLD. We review the delicate balance between cellular subsets and cytokines of the innate and adaptive immune system in conjunction with host-derived proteases that can perpetuate the parenchymal lung damage seen in PTLD. Next, we discuss the role of novel host directed therapies (HDT) to limit the development of PTLD and in particular, the recent repurposing of established medications such as statins, metformin and doxycycline. Finally, we review the emerging role of novel imaging techniques as a non-invasive modality for the early recognition of PTLD. While access to computed tomography imaging is unlikely to be available widely in countries with a high TB burden, its use in research settings can help phenotype PTLD. Due to a lack of disease-specific biomarkers and controlled clinical trials, there are currently no evidence-based recommendations for the management of PTLD. It is likely that an integrated antifibrotic strategy that could simultaneously target inflammatory and pro-fibrotic pathways will probably emerge as a successful way to treat this complex condition. In a disease spectrum as wide as PTLD, a single immunologic or radiographic marker may not be sufficient and a combination is more likely to be a successful surrogate that could aid in the development of successful HDTs.

Tapping into the antitubercular potential of 2,5-dimethylpyrroles: A structure-activity relationship interrogation

An exploration of the chemical space around a 2,5-dimethylpyrrole scaffold of antitubercular hit compound 1 has led to the identification of new derivatives active against Mycobacterium tuberculosis and multidrug-resistant clinical isolates. Analogues incorporating a cyclohexanemethyl group on the methyleneamine side chain at C3 of the pyrrole core, including 5n and 5q, exhibited potent inhibitory effects against the M. tuberculosis strains, substantiating the essentiality of the moiety to their antimycobacterial activity. In addition, selected derivatives showed promising cytotoxicity profiles against human pulmonary fibroblasts and/or murine macrophages, proved to be effective in inhibiting the growth of intracellular mycobacteria, and elicited either bactericidal effects, or bacteriostatic activity comparable to 1. Computational studies revealed that the new compounds bind to the putative target, MmpL3, in a manner similar to that of known inhibitors BM212 and SQ109.

Correlation of serum amyloid A1 and interleukin-1beta in response to anti-tubercular therapy

BACKGROUND

Host biomarkers are needed to monitor the response to anti-tubercular therapy (ATT) for ensuring effective therapy and preventing drug-resistant tuberculosis. We sought to find the correlation between the serum levels of SAA1 and IL-1beta in response to ATT in adult patients with pulmonary TB (PTB) or extra-pulmonary TB (EPTB).

METHODS

Blood samples of 32 patients with PTB and 28 patients with EPTB were analyzed. The blood samples were collected at baseline, two months and six months following treatment initiation. SAA1 and IL-1beta levels were measured by enzyme linked immunosorbent assay (ELISA).

RESULTS

In the PTB group, the mean levels of SAA1 decreased significantly (p <0.001) after the intensive phase (two months) and continuous phase (six months) of ATT in comparison with the baseline value. IL-1beta values also decreased significantly (p = 0.005) after the intensive phase (two months) compared with the baseline values. In the EPTB group, there was a significant reduction in the mean serum level of SAA1 (p <0.001) and IL-1beta (p = 0.001) after the intensive phase (two months) in comparison with the baseline value, whereas the reduction at six months was not significant.

CONCLUSIONS

SAA1 and IL-1beta may be useful potential treatment-monitoring biomarkers, especially in the intensive phase of therapy for both PTB and EPTB.

Sputum lipoarabinomannan (LAM) as a biomarker to determine sputum mycobacterial load: exploratory and model-based analyses of integrated data from four cohorts

Background

Despite the high global disease burden of tuberculosis (TB), the disease caused by Mycobacterium tuberculosis (Mtb) infection, novel treatments remain an urgent medical need. Development efforts continue to be hampered by the reliance on culture-based methods, which often take weeks to obtain due to the slow growth rate of Mtb. The availability of a “real-time” measure of treatment efficacy could accelerate TB drug development. Sputum lipoarabinomannan (LAM; an Mtb cell wall glycolipid) has promise as a pharmacodynamic biomarker of mycobacterial sputum load.

Methods

The present analysis evaluates LAM as a surrogate for Mtb burden in the sputum samples from 4 cohorts of a total of 776 participants. These include those from 2 cohorts of 558 non-TB and TB participants prior to the initiation of treatment (558 sputum samples), 1 cohort of 178 TB patients under a 14-day bactericidal activity trial with various mono- or multi-TB drug therapies, and 1 cohort of 40 TB patients with data from the first 56-day treatment of a standard 4-drug regimen.

Results

Regression analysis demonstrated that LAM was a predictor of colony-forming unit (CFU)/mL values obtained from the 14-day treatment cohort, with well-estimated model parameters (relative standard error ≤ 22.2%). Moreover, no changes in the relationship between LAM and CFU/mL were observed across the different treatments, suggesting that sputum LAM can be used to reasonably estimate the CFU/mL in the presence of treatment. The integrated analysis showed that sputum LAM also appears to be as good a predictor of time to Mycobacteria Growth Incubator Tube (MGIT) positivity as CFU/mL. As a binary readout, sputum LAM positivity is a strong predictor of solid media or MGIT culture positivity with an area-under-the-curve value of 0.979 and 0.976, respectively, from receiver-operator curve analysis.

Conclusions

Our results indicate that sputum LAM performs as a pharmacodynamic biomarker for rapid measurement of Mtb burden in sputum, and thereby may enable more efficient early phase clinical trial designs (e.g., adaptive designs) to compare candidate anti-TB regimens and streamline dose selection for use in pivotal trials.

Trial registration NexGen EBA study (NCT02371681)

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07308-3.

Olfactomedin 4 Is a Biomarker for the Severity of Infectious Diseases

Biomarkers of infectious diseases are essential tools for patient monitoring, diagnostics, and prognostics. Here we review recent advances in our understanding of olfactomedin 4 (OLFM4) in neutrophil biology and of OLFM4 as a new biomarker for certain infectious diseases. OLFM4 is a neutrophil-specific granule protein that is expressed in a subset of human and mouse neutrophils. OLFM4 expression is upregulated in many viral and bacterial infections, as well as in malaria. OLFM4 appears to play an important role in regulating host innate immunity against bacterial infection. Further, higher expression of OLFM4 is associated with severity of disease for dengue virus, respiratory syncytial virus, and malaria infections. In addition, higher expression of OLFM4 or a higher percentage of OLFM4 + neutrophils is associated with poorer outcomes in septic patients. OLFM4 is a promising biomarker and potential therapeutic target in certain infectious diseases.

Therapeutic Role of Antimicrobial Peptides in Diabetes Mellitus

Antimicrobial peptides (AMPs) have recently become widely publicized because they have the potential to function in alternative therapies as “natural” antibiotics, with their main advantage being a broad spectrum of activity. The potential for antimicrobial peptides to treat diabetes mellitus (DM) has been reported. In diabetes mellitus type I (T1D), cathelicidin-related antimicrobial peptide (CRAMP), cathelicidin antimicrobial peptide (CAMP) and mouse-β- defensin 14 (mBD14) are positively affected. Decreased levels of LL-37 and human neutrophil peptide 1-3 (HNP1-3) have been reported in diabetes mellitus type II (T2D) relative to healthy patients. Moreover, AMPs from amphibians and social wasps have antidiabetic effects. In infections occurring in patients with tuberculosis-diabetes or diabetic foot, granulysin, HNP1, HNP2, HNP3, human beta-defensin 2 (HBD2), and cathelicidins are responsible for pathogen clearance. An interesting alternative is also the use of modified M13 bacteriophages containing encapsulated AMPs genes or phagemids.

Design, synthesis and biological evaluation of nitrofuran-1,3,4-oxadiazole hybrids as new antitubercular agents

Three series of novel nitrofuran-1,3,4-oxadiazole hybrids were designed and synthesized as new anti-TB agents. The structure activity relationship study indicated that the linkers and the substituents on the oxadiazole moiety greatly influence the activity, and the substituted benzenes are more favoured than the cycloalkyl or heterocyclic groups. Besides, the optimal compound in series 2 was active against both MTB H₃₇Rv strain and MDR-MTB 16883 clinical isolate and also displayed low cytotoxicity, low inhibition of hERG and good oral PK, indicating its promising potential to be a lead for further structural modifications.

Interleukin-13 overexpressing mice represent an advanced pre-clinical model for detecting the distribution of anti-mycobacterial drugs within centrally necrotizing granulomas

The Mycobacterium tuberculosis-harboring granuloma with a necrotic center surrounded by a fibrous capsule is the hallmark of tuberculosis (TB). For a successful treatment, antibiotics need to penetrate these complex structures to reach their bacterial targets. Hence, animal models reflecting the pulmonary pathology of TB patients are of particular importance to improve the preclinical validation of novel drug candidates. M. tuberculosis-infected interleukin-13-overexpressing (IL-13^tg) mice develop a TB pathology very similar to patients and, in contrast to other mouse models, also share pathogenetic mechanisms. Accordingly, IL-13^tg animals represent an ideal model for analyzing the penetration of novel anti-TB drugs into various compartments of necrotic granulomas by matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI-MS imaging). In the present study, we evaluated the suitability of BALB/c IL-13^tg mice for determining the antibiotic distribution within necrotizing lesions. To this end, we established a workflow based on the inactivation of M. tuberculosis by gamma irradiation while preserving lung tissue integrity and drug distribution, which is essential for correlating drug penetration with lesion pathology. MALDI-MS imaging analysis of clofazimine, pyrazinamide, and rifampicin revealed a drug-specific distribution within different lesion types, including cellular granulomas, developing in BALB/c wild-type mice, and necrotic granulomas in BALB/c IL-13^tg animals, emphasizing the necessity of preclinical models reflecting human pathology. Most importantly, our study demonstrates that BALB/c IL-13^tg mice recapitulate the penetration of antibiotics into human lesions. Therefore, our workflow in combination with the IL-13^tg mouse model provides an improved and accelerated evaluation of novel anti-TB drugs and new regimens in the preclinical stage.

Randomized trial of Metformin with Anti-tuberculosis drugs For Early Sputum Conversion in Adults with Pulmonary Tuberculosis

Background

Metformin, by reducing intracellular Mycobacterium tuberculosis growth, can be considered an adjunctive therapy to anti-tuberculosis treatment (ATT). We determined whether metformin with standard ATT reduces time to sputum culture conversion and tissue inflammation in adults with pulmonary tuberculosis (PTB).

Methods

In a randomized, 8-week, clinical trial, newly diagnosed, culture-positive PTB patients were randomized to standard ATT (HREZ = control arm) or standard ATT plus daily 1000 mg metformin (MET-HREZ = Metformin with Rifampicin [METRIF] arm) for 8 weeks during 2018–2020 at 5 sites in India. The primary end point was time to sputum culture conversion by liquid culture during 8 weeks of ATT. Plasma inflammatory markers were estimated in a subset. A Cox proportional hazard model was used to estimate time and predictors of culture conversion.

Results

Of the 322 patients randomized, 239 (74%) were male, and 212 (66%) had bilateral disease on chest radiograph with 54 (18%) showing cavitation. The median time to sputum culture conversion by liquid culture was 42 days in the METRIF arm and 41 days in the control arm (hazard ratio, 0.8; 95% confidence interval [CI], .624–1.019). After 8 weeks of ATT, cavitary lesions on X-ray (7, 5.3% vs 18, 12.9%; relative risk, 0.42; 95% CI, .18–.96; P = .041) and inflammatory markers were significantly lower in the METRIF arm. Higher body mass index and lower sputum smear grading were associated with faster sputum culture conversion.

Conclusions

The addition of metformin to standard ATT did not hasten sputum culture conversion but diminished excess inflammation, thus reducing lung tissue damage as seen by faster clearance on X-ray and reduced inflammatory markers.

Clinical Trials Registration

Clinical Trial Registry of India (CTRI/2018/01/011176)

Systematic measurement of combination-drug landscapes to predict in vivo treatment outcomes for tuberculosis

Lengthy multidrug chemotherapy is required to achieve a durable cure in tuberculosis. However, we lack well-validated, high-throughput in vitro models that predict animal outcomes. Here, we provide an extensible approach to rationally prioritize combination therapies for testing in in vivo mouse models of tuberculosis. We systematically measured Mycobacterium tuberculosis response to all two- and three-drug combinations among ten antibiotics in eight conditions that reproduce lesion microenvironments, resulting in >500,000 measurements. Using these in vitro data, we developed classifiers predictive of multidrug treatment outcome in a mouse model of disease relapse and identified ensembles of in vitro models that best describe in vivo treatment outcomes. We identified signatures of potencies and drug interactions in specific in vitro models that distinguish whether drug combinations are better than the standard of care in two important preclinical mouse models. Our framework is generalizable to other difficult-to-treat diseases requiring combination therapies. A record of this paper's transparent peer review process is included in the supplemental information.

Plasma Chemokines Are Baseline Predictors of Unfavorable Treatment Outcomes in Pulmonary Tuberculosis

BACKGROUND

Plasma chemokines are biomarkers of greater disease severity, higher bacterial burden, and delayed sputum culture conversion in pulmonary tuberculosis (PTB). Whether plasma chemokines could also serve as biomarkers of unfavorable treatment outcomes in PTB is not known.

METHODS

A cohort of newly diagnosed, sputum smear- and culture-positive adults with drug-sensitive PTB were recruited under the Effect of Diabetes on Tuberculosis Severity study in Chennai, India. Plasma chemokine levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 136 control individuals who had recurrence-free cure. A second validation cohort comprising newly diagnosed, culture-positive adults with drug-sensitive TB was used to measure plasma chemokine levels in 20 cases and 40 controls.

RESULTS

Six chemokines (CCL2, CCL3, CCL4, CXCL8, CXCL10, and CX3CL1) were associated with increased risk, while CXCL1 was associated with decreased risk of unfavorable outcomes in unadjusted and adjusted analyses in the test cohort. Similarly, CCL3, CXCL8, and CXCL10 were associated with increased risk of unfavorable treatment outcomes in the validation cohort. Receiver operating characteristic analysis revealed that combinations of CCL3, CXCL8, and CXCL10 exhibited very high sensitivity and specificity in differentiating cases vs controls.

CONCLUSIONS

Our study reveals a plasma chemokine signature that can be used as a novel biomarker for predicting adverse treatment outcomes in PTB.

Doxycycline host-directed therapy in human pulmonary tuberculosis

BACKGROUNDMatrix metalloproteinases (MMPs) are key regulators of tissue destruction in tuberculosis (TB) and may be targets for host-directed therapy. We conducted a phase II double-blind, randomized, controlled trial investigating doxycycline, a licensed broad-spectrum MMP inhibitor, in patients with pulmonary TB.METHODSThirty patients with pulmonary TB were enrolled within 7 days of initiating anti-TB treatment and randomly assigned to receive either 100 mg doxycycline or placebo twice a day for 14 days, in addition to standard care.RESULTSWhole blood RNA-sequencing demonstrated that doxycycline accelerated restoration of dysregulated gene expression in TB towards normality, rapidly down-regulating type I and II interferon and innate immune response genes, and up-regulating B-cell modules relative to placebo. The effects persisted for 6 weeks after doxycycline discontinuation, concurrent with suppressed plasma MMP-1. Doxycycline significantly reduced sputum MMP-1, -8, -9, -12 and -13, suppressed type I collagen and elastin destruction, reduced pulmonary cavity volume without altering sputum mycobacterial loads, and was safe.CONCLUSIONAdjunctive doxycycline with standard anti-TB treatment suppressed pathological MMPs in PTB patients. Larger studies on adjunctive doxycycline to limit TB immunopathology are merited.TRIAL REGISTRATIONClinicalTrials.gov NCT02774993.FUNDINGSingapore National Medical Research Council (NMRC/CNIG/1120/2014, NMRC/Seedfunding/0010/2014, NMRC/CISSP/2015/009a); the Singapore Infectious Diseases Initiative (SIDI/2013/013); National University Health System (PFFR-28 January 14, NUHSRO/2014/039/BSL3-SeedFunding/Jul/01); the Singapore Immunology Network Immunomonitoring platform (BMRC/IAF/311006, H16/99/b0/011, NRF2017_SISFP09); an ExxonMobil Research Fellowship, NUHS Clinician Scientist Program (NMRC/TA/0042/2015, CSAINV17nov014); the UK Medical Research Council (MR/P023754/1, MR/N006631/1); a NUS Postdoctoral Fellowship (NUHSRO/2017/073/PDF/03); The Royal Society Challenge Grant (CHG\R1\170084); the Sir Henry Dale Fellowship, Wellcome Trust (109377/Z/15/Z); and A*STAR.

Structures of the mycobacterial membrane protein MmpL3 reveal its mechanism of lipid transport

The mycobacterial membrane protein large 3 (MmpL3) transporter is essential and required for shuttling the lipid trehalose monomycolate (TMM), a precursor of mycolic acid (MA)-containing trehalose dimycolate (TDM) and mycolyl arabinogalactan peptidoglycan (mAGP), in Mycobacterium species, including Mycobacterium tuberculosis and Mycobacterium smegmatis. However, the mechanism that MmpL3 uses to facilitate the transport of fatty acids and lipidic elements to the mycobacterial cell wall remains elusive. Here, we report 7 structures of the M. smegmatis MmpL3 transporter in its unbound state and in complex with trehalose 6-decanoate (T6D) or TMM using single-particle cryo-electron microscopy (cryo-EM) and X-ray crystallography. Combined with calculated results from molecular dynamics (MD) and target MD simulations, we reveal a lipid transport mechanism that involves a coupled movement of the periplasmic domain and transmembrane helices of the MmpL3 transporter that facilitates the shuttling of lipids to the mycobacterial cell wall.

Urinary proteomic analysis to identify a potential protein biomarker panel for the diagnosis of tuberculosis

Tuberculosis (TB) is caused by Mycobacterium tuberculosis and is one of the primary causes of death worldwide. Rapid and accurate diagnosis of TB is one of the most direct means to reduce the incidence of TB. In this study, urinary proteomic profiling of TB patients and non-TB individual controls (HCs) was performed, and differentially expressed urinary proteins between TB and HCs were compared and exclusively expressed proteins in TB patients were selected to establish a clinically useful disease marker panel. In total, these top 11 targeted proteins with 265 peptides were scheduled for multiple reaction monitoring validation analysis by using urine samples from 52 TB patients and 52 HCs. The result demonstrated that a three-protein combination out of the five-protein panel (namely P22352, Q9P121, P15151, Q13291, and Q8NDA2) exhibited sensitivity rate of 82.7% in the diagnosis of TB. Furthermore, the three-protein combination could differentiate TB from the latent tuberculosis (LTB) effectively, which exhibited specificity rate of 92.3% for the diagnosis of TB from the LTB category. Although more numbers of clinical samples are required for further verification, the results provided preliminary evidence that this "three-protein combination" out of the five-protein panel could probably be a novel TB diagnostic biomarker in clinical application.

Chemical Classes Presenting Novel Antituberculosis Agents Currently in Different Phases of Drug Development: A 2010-2020 Review

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a curable airborne disease currently treated using a drug regimen consisting of four drugs. Global TB control has been a persistent challenge for many decades due to the emergence of drug-resistant Mtb strains. The duration and complexity of TB treatment are the main issues leading to treatment failures. Other challenges faced by currently deployed TB regimens include drug-drug interactions, miss-matched pharmacokinetics parameters of drugs in a regimen, and lack of activity against slow replicating sub-population. These challenges underpin the continuous search for novel TB drugs and treatment regimens. This review summarizes new TB drugs/drug candidates under development with emphasis on their chemical classes, biological targets, mode of resistance generation, and pharmacokinetic properties. As effective TB treatment requires a combination of drugs, the issue of drug-drug interaction is, therefore, of great concern; herein, we have compiled drug-drug interaction reports, as well as efficacy reports for drug combinations studies involving antitubercular agents in clinical development.

Arthroscopic Ankle Arthrodesis for End-Stage Tuberculosis of the Ankle: A 2-Year Follow-Up

Surgical treatment for end-stage ankle joint tuberculosis (TB) has rarely been reported. This study followed cases treated by arthroscopic arthrodesis for ankle joint TB to evaluate its efficacy and safety in the clinic. Patients who underwent arthroscopic ankle arthrodesis for ankle joint TB between April 11, 2010, and December 31, 2016, were followed. Their diagnoses were confirmed by bacterial culture or pathological examination. During arthroscopy, tissue samples were first obtained to further confirm the diagnosis. Then the necrotic tissue, hyperplasia of synovial tissue, and exfoliated cartilage were removed. Ankle joint arthrodesis was performed if the area of articular cartilage damage was >2 cm². Continued nutritional support and standardized anti-TB drug treatment were given after surgery. Follow-up measurements included visual analogue scale score, American Orthopaedic Foot and Ankle Society score, erythrocyte sedimentation rate, and radiographic imaging. All 9 patients in this study, with an average age of 54 (range 37 to 68) years, were followed. The mean follow-up duration was 55.44 ± 31.15 (range 24 to 96) months. There were significant differences in the visual analogue scale scores, American Orthopaedic Foot and Ankle Society scores, and erythrocyte sedimentation rate between before treatment and 18 months postoperatively (p < .05). All patients (100%) showed union at 18 ± 4 weeks. Arthroscopic treatment for ankle joint TB has the advantages of minor trauma and low complications. It can be used to accurately obtain samples from specific areas of TB for further diagnosis. According to the degree of articular cartilage damage, the surgeon can determine whether to perform arthrodesis. Thorough debridement of necrotic tissue and residual articular cartilage on the fusion surface can improve the rate of ankle fusion.

Studies on the safety and the tissue distribution of inhaled high-dose amorphous and crystalline rifampicin in a rat model

Inhaled delivery of rifampicin has the potential to achieve high drug concentrations in the lung and the blood for efficient treatment of tuberculosis (TB). Due to its existence as polymorphs, in vivo evaluation of the respiratory tract safety of inhalable amorphous and crystalline rifampicin particles, at clinically relevant high-dose, is necessary. This study investigates the lung and liver safety and the tissue distribution of rifampicin after intra-tracheal administration of high (≥25 mg/kg) doses of amorphous and crystalline powder formulations to Sprague Dawley rats. Powder formulations were administered by intra-tracheal insufflation to rats. Lung and liver safety were evaluated by histopathology. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) assays were performed to study the hepatic effects. Rifampicin was quantified in the tissues using LC-MS/MS. Intra-tracheal administration of rifampicin decreased the drug burden on the liver compared to oral administration based on its lower serum ALT activity. Repeated-dose intra-tracheal rifampicin was well tolerated by rats, confirmed by the absence of drug or delivery induced complexities. The histopathological evaluation of rat lungs, after both single and repeated drug administration for seven days, suggested the absence of drug-induced toxicity. Following single intra-tracheal delivery of 50 mg/kg doses, comparable rifampicin concentrations to that from same oral dose were observed in lung, liver, heart and brain. Inhaled delivery of high-dose rifampicin was safe to rat lungs and liver suggesting its potential for localized as well as systemic drug delivery without toxicity concerns.

Serum Procalcitonin Levels Predict Mortality Risk in Patients With Pulmonary Tuberculosis: A Single-Center Prospective Observational Study

Globally, tuberculosis is the leading infectious cause of death; discovering biomarkers that predict a high mortality risk may improve treatment outcomes. We prospectively enrolled 252 pulmonary tuberculosis patients who were not coinfected with human immunodeficiency virus and initiated antituberculosis treatment, measured serum procalcitonin levels (PCT), and assessed mortality risk. PCT serum levels higher than 0.13 (day 0), 0.05 (day 7), 0.12 (day 14), or 0.06 (day 28) ng/mL predicted nonsurvivors with odds ratios of 7.9, 14.3, 20.0, and 7.3, respectively (P ≤ .005 for all), respectively. Therefore, serum PCT levels are a promising mortality risk indicator for patients with pulmonary tuberculosis. Main Point. For patients with pulmonary tuberculosis, a promising mortality risk indicator is the level of serum procalcitonin, which is weakly associated with sputum bacterial load and independent of radiographic findings.

Diabetes Mellitus and Tuberculosis Treatment Outcomes in Pune, India

Background

Diabetes mellitus (DM) increases the risk of tuberculosis (TB) disease. Knowledge of the impact of DM on TB treatment outcomes is primarily based on retrospective studies.

Methods

We conducted a prospective cohort study of new pulmonary TB patients with and without DM (TB-DM and TB only) in India. The association of DM with a composite unfavorable TB treatment outcome (failure, recurrence, mortality) over 18 months was determined, and the effect of DM on all-cause mortality and early mortality (death during TB treatment) was assessed.

Results

Of 799 participants, 574 (72%) had TB only and 225 (28%) had TB-DM. The proportion of patients with DM who experienced the composite outcome was 20%, as compared with 21% for TB-only participants (adjusted hazard ratio [aHR], 1.13; 95% CI, 0.75–1.70). Mortality was higher in participants with DM (10% vs 7%), and early mortality was substantially higher among patients with DM (aHR, 4.36; 95% CI, 1.62–11.76).

Conclusions

DM was associated with early mortality in this prospective cohort study, but overall unfavorable outcomes were similar to participants without DM. Interventions to reduce mortality during TB treatment among people with TB-DM are needed.

Comprehensive review on mechanism of action, resistance and evolution of antimycobacterial drugs

Tuberculosis is one of the deadliest infectious diseases existing in the world since ancient times and still possesses serious threat across the globe. Each year the number of cases increases due to high drug resistance shown by Mycobacterium tuberculosis (Mtb). Available antimycobacterial drugs have been classified as First line, Second line and Third line antibiotics depending on the time of their discoveries and their effectiveness in the treatment. These antibiotics have a broad range of targets ranging from cell wall to metabolic processes and their non-judicious and uncontrolled usage in the treatment for years has created a significant problem called multi-drug resistant (MDR) tuberculosis. In this review, we have summarized the mechanism of action of all the classified antibiotics currently in use along with the resistance mechanisms acquired by Mtb. We have focused on the new drug candidates/repurposed drugs, and drug in combinations, which are in clinical trials for either treating the MDR tuberculosis more effectively or involved in reducing the time required for the chemotherapy of drug sensitive TB. This information is not discussed very adequately on a single platform. Additionally, we have discussed the recent technologies that are being used to discover novel resistance mechanisms acquired by Mtb and for exploring novel drugs. The story of intrinsic resistance mechanisms and evolution in Mtb is far from complete. Therefore, we have also discussed intrinsic resistance mechanisms of Mtb and their evolution with time, emphasizing the hope for the development of novel antimycobacterial drugs for effective therapy of tuberculosis.

Lactate Metabolism and Signaling in Tuberculosis and Cancer: A Comparative Review

Infection with Mycobacterium tuberculosis (Mtb) leading to tuberculosis (TB) disease continues to be a major global health challenge. Critical barriers, including but not limited to the development of multi-drug resistance, lack of diagnostic assays that detect patients with latent TB, an effective vaccine that prevents Mtb infection, and infectious and non-infectious comorbidities that complicate active TB, continue to hinder progress toward a TB cure. To complement the ongoing development of new antimicrobial drugs, investigators in the field are exploring the value of host-directed therapies (HDTs). This therapeutic strategy targets the host, rather than Mtb, and is intended to augment host responses to infection such that the host is better equipped to prevent or clear infection and resolve chronic inflammation. Metabolic pathways of immune cells have been identified as promising HDT targets as more metabolites and metabolic pathways have shown to play a role in TB pathogenesis and disease progression. Specifically, this review highlights the potential role of lactate as both an immunomodulatory metabolite and a potentially important signaling molecule during the host response to Mtb infection. While long thought to be an inert end product of primarily glucose metabolism, the cancer research field has discovered the importance of lactate in carcinogenesis and resistance to chemotherapeutic drug treatment. Herein, we discuss similarities between the TB granuloma and tumor microenvironments in the context of lactate metabolism and identify key metabolic and signaling pathways that have been shown to play a role in tumor progression but have yet to be explored within the context of TB. Ultimately, lactate metabolism and signaling could be viable HDT targets for TB; however, critical additional research is needed to better understand the role of lactate at the host-pathogen interface during Mtb infection before adopting this HDT strategy.

Rifampin-resistant/multidrug-resistant Tuberculosis in Alberta, Canada: Epidemiology and treatment outcomes in a low-incidence setting

Treatment of rifampin-monoresistant/multidrug-resistant Tuberculosis (RR/MDR-TB) requires long treatment courses, complicated by frequent adverse events and low success rates. Incidence of RR/MDR-TB in Canada is low and treatment practices are variable due to the infrequent experience and challenges with drug access. We undertook a retrospective cohort study of all RR/MDR-TB cases in Alberta, Canada from 2007-2017 to explore the epidemiology and outcomes in our low incidence setting. We performed a descriptive analysis of the epidemiology, treatment regimens and associated outcomes, calculating differences in continuous and discrete variables using Student's t and Chi-squared tests, respectively. We identified 24 patients with RR/MDR-TB. All patients were foreign-born with the median time to presentation after immigration being 3 years. Prior treatment was reported in 46%. Treatment was individualized. All patients achieved sputum culture conversion within two months of treatment initiation. The median treatment duration after culture conversion was 18 months (IQR: 15-19). The mean number of drugs utilized during the intensive phase was 4.3 (SD: 0.8) and during the continuation phase was 3.3 (SD: 0.9) and the mean adherence to medications was 95%. Six patients completed national guideline-concordant therapy, with many patients developing adverse events (79%). Treatment success (defined as completion of prescribed therapy or cure) was achieved in 23/24 patients and no acquired drug resistance or relapse was detected over 1.8 years of median follow-up. Many cases were captured upon immigration assessment, representing important prevention of community spread. Despite high rates of adverse events and short treatment compared to international guidelines, success in our cohort was very high at 96%. This is likely due to individualization of therapy, frequent use of medications with high effectiveness, intensive treatment support, and early sputum conversion seen in our cohort. There should be ongoing exploration of treatment shortening with well-tolerated, efficacious oral agents to help patients achieve treatment completion.

Control de la tuberculosis en un sistema penitenciario brasileño: un estudio con métodos mixtos

Resumen Objetivo analizar el control de la tuberculosis en un sistema penitenciario de un Estado brasileño. Método estudio mixto explicativo secuencial. Fase I: descriptiva retrospectiva de los casos de tuberculosis en presos del estado de São Paulo en el periodo 2010-2016. Los casos se analizaron con frecuencias simples en el software SPSS 20.0 de la IBM y tendencia temporal en el software Stata/SE 14.0, por auto regresión de Prais-Winsten. Fase II: cualitativa. Se realizó con seis informantes-clave (profesionales sanitarios de una prisión) con base en la Teoría Fundamentada Constructivista. Resultados de 16.640 casos, 95,8% eran pulmonares, la Demanda Ambulatoria posibilitó el diagnóstico del 51,4%, y la curación fue la conclusión de tratamiento más frecuente. La categoría central fue: “Hacer bien su trabajo” y las subcategorías fueron: “Descubrir la enfermedad” e “Implicarse en el tratamiento”. Éstas señalaron las estrategias y acciones desarrolladas por los profesionales para diagnosticar y tratar a los presos enfermos. Conclusión e implicaciones para la práctica los resultados sugieren una importante situación de la tuberculosis en penitenciarías, lo que trae consigo la necesidad de mejor articulación con el equipo de seguridad para un adecuado desarrollo de las estrategias que posibilitan un diagnóstico temprano y un tratamiento adecuado.

The application of isatin-based multicomponent-reactions in the quest for new bioactive and druglike molecules

Oxindole derivatives are known for their great interest in the field of Medicinal Chemistry, as they display vast biological activities. Recent efforts concerning the preparation of oxindole derivatives using isatin-based multicomponent reactions (MCRs) constitute a great advance in generating druglike libraries fast and with wide scaffold diversity. In this review, we address those recent developments, exploring the synthetic pathways and biological activities described for these compounds, namely antitumor, antibacterial, antifungal, antiparasitic, antiviral, antioxidant, anti-inflammatory and central nervous system (CNS) pathologies. To add new depth to this work, we used a well-established web-based free tool (SwissADME) to evaluate the most promising scaffolds in what concerns their druglike properties, namely by evaluating their compliance with some of the most valuable rules applied by medicinal chemists in both academia and industrial settings (Lipinski, Ghose, Veber, Egan, Muegge). The aim of this review is to endorse isatin-based MCRs as a valuable synthetic approach to attain new hit compounds bearing the oxindole privileged structure, while critically exploring these scaffolds' druglike properties.

Synthesis and evaluation of thiophene based small molecules as potent inhibitors of Mycobacterium tuberculosis

Herein, we report the synthesis and anti-tubercular studies of novel molecules based on thiophene scaffold. We identified two novel small molecules 4a and 4b, which demonstrated 2-fold higher in vitro activity (MIC₉₉: 0.195 μM) compared to first line TB drug, isoniazid (0.39 μM). The identified leads demonstrated additive effect with front line TB drugs (isoniazid, rifampicin and levofloxacin) and synergistic effect with a recently FDA-approved drug, bedaquiline. Mechanistic studies (i) negated the role of Pks13 and (ii) suggested the involvement of KatG in the anti-tubercular activity of these identified leads.

Association of Plasma Matrix Metalloproteinase and Tissue Inhibitors of Matrix Metalloproteinase Levels With Adverse Treatment Outcomes Among Patients With Pulmonary Tuberculosis

IMPORTANCE

Identifying biomarkers of treatment response is an urgent need in the treatment of tuberculosis (TB). Matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) are potential diagnostic biomarkers in pulmonary TB (PTB).

OBJECTIVE

To assess whether baseline plasma levels of MMPs and TIMPs are also prognostic biomarkers for adverse treatment outcomes in patients with PTB.

DESIGN, SETTING, AND PARTICIPANTS

Two different cohorts (test and validation) of individuals with PTB were recruited from 2 different sets of primary care centers in Chennai, India, and were followed up for treatment outcomes. Participants were individuals with newly diagnosed TB that was sputum smear and culture positive and drug sensitive. A total of 68 cases and 133 controls were in the test cohort and 20 cases and 40 controls were in the validation cohort. A nested case-control study was performed by matching case patients to control participants in a 1:2 ratio for age, sex, and body mass index. Data for the test cohort was taken from a study performed from 2014 to 2019, and data for the validation cohort, from a study performed from 2008 to 2012. The data analysis was performed from November 2019 to May 2020.

INTERVENTIONS

Individuals with PTB were treated with antituberculosis chemotherapy for 6 months and followed up for 1 year after completion of treatment.

MAIN OUTCOMES AND MEASURES

Individuals with PTB with adverse outcomes (treatment failure, all-cause mortality, or recurrent TB) were defined as cases and those with favorable outcomes (recurrence-free cure) were defined as controls. Plasma levels of MMPs and TIMPs were measured before treatment as potential biomarkers.

RESULTS

In all, 68 cases and 133 matched controls were enrolled in the study (170 [85%] males and 31 [15%] females; median age, 45 years [range, 23-73 years]) in the test cohort and 20 cases with 40 matched controls (51 [85%] males and 9 [15%] females; median age, 45 years [range, 19-61 years]) in the validation cohort. Baseline plasma levels of 5 MMPs and 2 TIMPs in the test cohort and 5 MMPs and all 4 TIMPS in the validation cohort were significantly higher in cases vs controls. In the test cohort, the geometric means (GMs), cases vs controls, were as follows: for MMP-1, 3680 vs 2484 pg/mL (P = .008); for MMP-2, 6523 vs 4762 pg/mL (P < .001); for MMP-7, 3346 vs 2100 pg/mL (P < .001); for MMP-8, 1915 vs 1066 pg/mL (P < .001); for MMP-9, 2774 vs 2336 pg/mL (P = .009); for TIMP-1, 4491 vs 2910 pg/mL (P < .001); and for TIMP-2, 3082 vs 2115 pg/mL (P < .001). In the validation cohort, the GMs, cases vs controls were as follows: for MMP-1, 3680 vs 2484 pg/mL (P < .001); for MMP-2, 6523 vs 4762 pg/mL (P < .001); for MMP-7, 3346 vs 2100 pg/mL (P < .001); for MMP-9, 1915 vs 1066 pg/mL (P < .001); for MMP-13, 2774 vs 2336 pg/mL (P < .001); for TIMP-1, 4491 vs 2910 pg/mL (P = .003); for TIMP-2, 3082 vs 2115 pg/mL (P = .003); for TIMP-3, 2066 vs 1020 pg/mL (P < .001); and for TIMP-4, 2130 vs 694 pg/mL (P < .001). Plasma levels of MMPs and TIMPs were associated with increased risk of adverse outcomes according to both univariate and multivariable analysis in the test cohort (eg, univariate analysis: odds ratio [OR] for MMP-8, 2.04; 95% CI, 1.33-3.14; P = .001; multivariable analysis: OR for MMP-8, 2.16; 95% CI, 1.34-3.47; P = .001). Combined receiver operating characteristic analysis revealed significant area under the curve (AUC), with high sensitivity and specificity in both cohorts (eg, for a combination of MMP-2, MMP-7, and TIMP-1 in the test cohort: sensitivity, 84%; specificity, 83%; and AUC, 0.886; for a combination of MMP-2, MMP-7, TIMP-1, and TIMP-2 in the validation cohort: sensitivity, 85%; specificity, 95%; and AUC, 0.944).

CONCLUSIONS AND RELEVANCE

Baseline plasma MMP and TIMP levels may be correlates of risk and prognostic biomarkers for treatment failure, relapse, and death in individuals with PTB and merit further evaluation as predictive biomarkers for stratification of patients to shortened or intensified treatment regimens.