Treatment Of Human Tuberculosis Research Articles

Recognition of Mycobacterium tuberculosis by macrophage Toll-like receptor and its role in autophagy.

The pathogen responsible for tuberculosis is called Mycobacterium tuberculosis. Its interaction with macrophages has a significant impact on the onset and progression of the disease. The respiratory pathway allows Mycobacterium tuberculosis to enter the body's lungs where it battles immune cells before being infected latently or actively. In the progress of tuberculosis, Mycobacterium tuberculosis activates the body's immune system and creates inflammatory factors, which cause tissue inflammation to infiltrate and the creation of granulomas, which seriously harms the body. Toll-like receptors of macrophage can mediate host recognition of Mycobacterium tuberculosis, initiate immune responses, and participate in macrophage autophagy. New host-directed therapeutic approaches targeting autophagy for drug-resistant Mycobacterium tuberculosis have emerged, providing new ideas for the effective treatment of tuberculosis. In-depth understanding of the mechanisms by which macrophage autophagy interacts with intracellular Mycobacterium tuberculosis, as well as the study of potent and specific autophagy-regulating molecules, will lead to much-needed advances in drug discovery and vaccine design, which will improve the prevention and treatment of human tuberculosis.

Lung microenvironments harbor Mycobacterium tuberculosis phenotypes with distinct treatment responses.

Tuberculosis lung lesions are complex and harbor heterogeneous microenvironments that influence antibiotic effectiveness. Major strides have been made recently in understanding drug pharmacokinetics in pulmonary lesions, but the bacterial phenotypes that arise under these conditions and their contribution to drug tolerance are poorly understood. A pharmacodynamic marker called the RS ratio® quantifies ongoing rRNA synthesis based on the abundance of newly synthesized precursor rRNA relative to mature structural rRNA. Application of the RS ratio in the C3HeB/FeJ mouse model demonstrated that Mycobacterium tuberculosis populations residing in different tissue microenvironments are phenotypically distinct and respond differently to drug treatment with rifampin, isoniazid, or bedaquiline. This work provides a foundational basis required to address how anatomic and pathologic microenvironmental niches may contribute to long treatment duration and drug tolerance during the treatment of human tuberculosis.

Harnessing Innate Immunity to Treat Mycobacterium tuberculosis Infections: Heat-Killed Caulobacter crescentus as a Novel Biotherapeutic.

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is a serious and devastating infectious disease worldwide. Approximately a quarter of the world population harbors latent Mtb infection without pathological consequences. Exposure of immunocompetent healthy individuals with Mtb does not result in active disease in more than 90% individuals, suggesting a defining role of host immunity to prevent and/or clear early infection. However, innate immune stimulation strategies have been relatively underexplored for the treatment of tuberculosis. In this study, we used cell culture and mouse models to examine the role of a heat-killed form of a non-pathogenic microbe, Caulobacter crescentus (HKCC), in inducing innate immunity and limiting Mtb infection. We also examined the added benefits of a distinct chemo-immunotherapeutic strategy that incorporates concurrent treatments with low doses of a first-line drug isoniazid and HKCC. This therapeutic approach resulted in highly significant reductions in disseminated Mtb in the lungs, liver, and spleen of mice compared to either agent alone. Our studies demonstrate the potential of a novel innate immunotherapeutic strategy with or without antimycobacterial drugs in controlling Mtb infection in mice and open new avenues for the treatment of tuberculosis in humans.

Gastrointestinal microbiota composition predicts peripheral inflammatory state during treatment of human tuberculosis

The composition of the gastrointestinal microbiota influences systemic immune responses, but how this affects infectious disease pathogenesis and antibiotic therapy outcome is poorly understood. This question is rarely examined in humans due to the difficulty in dissociating the immunologic effects of antibiotic-induced pathogen clearance and microbiome alteration. Here, we analyze data from two longitudinal studies of tuberculosis (TB) therapy (35 and 20 individuals) and a cross sectional study from 55 healthy controls, in which we collected fecal samples (for microbiome analysis), sputum (for determination of Mycobacterium tuberculosis (Mtb) bacterial load), and peripheral blood (for transcriptomic analysis). We decouple microbiome effects from pathogen sterilization by comparing standard TB therapy with an experimental TB treatment that did not reduce Mtb bacterial load. Random forest regression to the microbiome-transcriptome-sputum data from the two longitudinal datasets reveals that renormalization of the TB inflammatory state is associated with Mtb pathogen clearance, increased abundance of Clusters IV and XIVa Clostridia, and decreased abundance of Bacilli and Proteobacteria. We find similar associations when applying machine learning to peripheral gene expression and microbiota profiling in the independent cohort of healthy individuals. Our findings indicate that antibiotic-induced reduction in pathogen burden and changes in the microbiome are independently associated with treatment-induced changes of the inflammatory response of active TB, and the response to antibiotic therapy may be a combined effect of pathogen killing and microbiome driven immunomodulation.

Insertion and deletion evolution reflects antibiotics selection pressure in a Mycobacterium tuberculosis outbreak.

In genome evolution, genetic variants are the source of diversity, which natural selection acts upon. Treatment of human tuberculosis (TB) induces a strong selection pressure for the emergence of antibiotic resistance-conferring variants in the infecting Mycobacterium tuberculosis (MTB) strains. MTB evolution in response to treatment has been intensively studied and mainly attributed to point substitutions. However, the frequency and contribution of insertions and deletions (indels) to MTB genome evolution remains poorly understood. Here, we analyzed a multi-drug resistant MTB outbreak for the presence of high-quality indels and substitutions. We find that indels are significantly enriched in genes conferring antibiotic resistance. Furthermore, we show that indels are inherited during the outbreak and follow a molecular clock with an evolutionary rate of 5.37e-9 indels/site/year, which is 23 times lower than the substitution rate. Inherited indels may co-occur with substitutions in genes along related biological pathways; examples are iron storage and resistance to second-line antibiotics. This suggests that epistatic interactions between indels and substitutions affect antibiotic resistance and compensatory evolution in MTB.

Macrophage-Mycobacteria Interaction: Exploration of Proteomic Signatures

Tuberculosis (TB) has overburdened humans for ages and continues to be a major health problem worldwide. Mycobacterium tuberculosis, a facultative intracellular pathogen, is the causative agent of human TB. M. tuberculosis has an enormous capacity to survive and multiply inside host macrophages (MΦs), which are one of the most hostile cell types of the host. MΦs play a central role(s) as an effecter cell in host defense against mycobacterial infections. Soon after the inhalation of droplet-nuclei containing M. tuberculosis by the host, MΦsare the first cells to interact with mycobacteria, leading to the onset of primary events which later ensue in the development of TB. MΦs, all by themselves, are not sufficient to provide protective immunity; they require interaction with other cells (e. g. T-cells) to mount an enhanced protective immune response against the pathogen. The cytokines such as interferon gamma and tumor necrosis factor alpha etc. Play a major role in the regulation of interactions among different cells of the immune system to augment immunity. In this review, we focus on various functional roles of cytokines which serve as a link between innate and adaptive immunity, and discuss their potential use as biomarker(s) or biosignatures for the diagnosis, to monitor the progression of disease, and to determine the success of the treatment of human TB.

Isoniazid: an Update on the Multiple Mechanisms for a Singular Action

Isoniazid (INH) is one of the most commonly used drugs in treatment of human tuberculosis and the most efficient. Although it has been 60 years since isoniazid was introduced in anti-tubercular therapy and despite the simplicity of its chemical structure (C₆H₇N₃O) with few functional groups, its exact mechanism of action, which could account for its specificity and exceptional potency against Mycobacterium tuberculosis and justify all profiles of INH-resistance, remains elusive and debatable. This complexity can find an explanation in the high reactivity of INH and also in the possibility that multiple targets and pathways could co-exist for this medicinal agent. Indeed, since the discovery of isoniazid's anti-tubercular potency, several propositions for its mode of action have been reported, including its conversion, by a catalase peroxidase within M. tuberculosis, into an active metabolite able, after reaction with NAD, to inhibit an enzyme (InhA) crucial to M. tuberculosis survival. This represents the most consensual mechanism described to date. Nevertheless, none of the proposed mechanisms considered independently can explain the singular and privileged action of the isoniazid structure on the tubercle bacillus, or all the profiles of resistance. The aim of this paper is to reconsider the literature reporting the different modes of action described for isoniazid in the light of the present and most relevant knowledge, with special attention to understanding the molecular mechanistic aspects of the drug's action.

Counterattacking drug-resistant tuberculosis: molecular strategies and future directions

Counterattacking drug-resistant tuberculosis: molecular strategies and future directions

Cathepsin G and Neutrophil Elastase Contribute to Lung-Protective Immunity against Mycobacterial Infections in Mice

The neutrophil serine proteases cathepsin G (CG) and neutrophil elastase (NE) are involved in immune-regulatory processes and exert antibacterial activity against various pathogens. To date, their role and their therapeutic potential in pulmonary host defense against mycobacterial infections are poorly defined. In this work, we studied the roles of CG and NE in the pulmonary resistance against Mycobacterium bovis bacillus Calmette-Guérin (BCG). CG-deficient mice and even more pronounced CG/NE-deficient mice showed significantly impaired pathogen elimination to infection with M. bovis BCG in comparison to wild-type mice. Moreover, granuloma formation was more pronounced in M. bovis BCG-infected CG/NE-deficient mice in comparison to CG-deficient and wild-type mice. A close examination of professional phagocyte subsets revealed that exclusively neutrophils shuttled CG and NE into the bronchoalveolar space of M. bovis BCG-infected mice. Accordingly, chimeric wild-type mice with a CG/NE-deficient hematopoietic system displayed significantly increased lung bacterial loads in response to M. bovis BCG infection. Therapeutically applied human CG/NE encapsulated in liposomes colocalized with mycobacteria in alveolar macrophages, as assessed by laser scanning and electron microscopy. Importantly, therapy with CG/NE-loaded liposomes significantly reduced mycobacterial loads in the lungs of mice. Together, neutrophil-derived CG and NE critically contribute to deceleration of pathogen replication during the early phase of antimycobacterial responses. In addition, to our knowledge, we show for the first time that liposomal encapsulated CG/NE exhibit therapeutic potential against pulmonary mycobacterial infections. These findings may be relevant for novel adjuvant approaches in the treatment of tuberculosis in humans.

Evaluation of a Mouse Model of Necrotic Granuloma Formation Using C3HeB/FeJ Mice for Testing of Drugs against Mycobacterium tuberculosis

Persistence of Mycobacterium tuberculosis remains a significant challenge for the effective treatment of tuberculosis in humans. In animals that develop necrotic lung lesions following infection with M. tuberculosis, drug-tolerant bacilli are present and persist in an extracellular microenvironment within the necrotic cores. In this study, we examined the efficacy of drug treatment in C3HeB/FeJ (Kramnik) mice that develop lesions with liquefactive necrosis, in comparison to BALB/c mice that develop nonnecrotic lesions following aerosol challenge. To accomplish this, Kramnik and BALB/c mice were infected by aerosol with M. tuberculosis and treated for 7 to 8 weeks with monotherapy using drugs with different modes of action. The efficacy of drug therapy was quantified by enumeration of bacterial load. The progression of disease and location and distribution of bacilli within lesions were visualized using various staining techniques. In the late stages of infection, Kramnik mice developed fibrous encapsulated lung lesions with central liquefactive necrosis containing abundant extracellular bacilli, whereas BALB/c mice formed nonnecrotic lesions with primarily intracellular bacilli. Necrotic lesions in Kramnik mice showed evidence of hypoxia by pimonidazole staining. Kramnik mice were significantly more refractory to drug therapy, especially for pyrazinamide. Metronidazole showed no bactericidal activity in either model. There were significantly higher numbers of drug-resistant colonies isolated from the Kramnik mice compared to BALB/c mice. These results suggest that the Kramnik mouse model will be a valuable model to test antituberculosis drugs, especially against bacilli that persist within necrotic lesions.

Medicinal plants used in the treatment of Tuberculosis in humans and animals by Idom Tribe of North Central Nigeria

Medicinal plants used in the treatment of Tuberculosis in humans and animals by Idom Tribe of North Central Nigeria

Augmentation Treatment of Psychotherapy for Anxiety Disorders with D‐Cycloserine

Anxiety disorders are among the most common mental disorders. One of the most effective strategies to treat anxiety disorders is exposure therapy with or without cognitive intervention. Fear reduction in exposure therapy is similar to extinction learning. Preclinical studies suggest that extinction learning can be blocked by antagonists at the glutamatergic N-methyl-D-aspartate (NMDA) receptor, and facilitated with D-cycloserine (DCS), a partial agonist at the glycine recognition site of the NMDA receptor in the amygdala. DCS is an established antibiotic drug for the chronic treatment of tuberculosis in humans, but has only recently been investigated as an augmentation therapy for psychological treatment procedures. The review of the literature provides preliminary support for the use of acute dosing of DCS as an adjunctive intervention to exposure therapy for anxiety disorders, including specific phobia and social anxiety disorder. Negative results have recently been reported in the treatment of subclinical fears of animals. These studies suggest that DCS needs to be administered on an acute rather than a chronic dosing schedule, include sufficient time for memory consolidation, and be administered together with psychological treatment that leaves sufficient room for further improvement. It remains to be seen whether these highly promising findings represent reliable pharmacological strategies to enhance exposure therapy of anxiety disorders.

Moxifloxacin versus Ethambutol in the First 2 Months of Treatment for Pulmonary Tuberculosis

Moxifloxacin has promising preclinical activity against Mycobacterium tuberculosis, but has not been evaluated in multidrug treatment of tuberculosis in humans. To compare the impact of moxifloxacin versus ethambutol, both in combination with isoniazid, rifampin, and pyrazinamide, on sputum culture conversion at 2 mo as a measure of the potential sterilizing activity of alternate induction regimens. Adults with smear-positive pulmonary tuberculosis were randomized in a factorial design to receive moxifloxacin (400 mg) versus ethambutol given 5 d/wk versus 3 d/wk (after 2 wk of daily therapy). All doses were directly observed. The primary endpoint was sputum culture status at 2 mo of treatment. Of 336 patients enrolled, 277 (82%) were eligible for the efficacy analysis, 186 (67%) were male, 175 (63%) were enrolled at African sites, 206 (74%) had cavitation on chest radiograph, and 60 (22%) had HIV infection. Two-month cultures were negative in 71% of patients (99 of 139) treated with moxifloxacin versus 71% (98 of 138) treated with ethambutol (p = 0.97). Patients receiving moxifloxacin, however, more often had negative cultures after 4 wk of treatment. Patients treated with moxifloxacin more often reported nausea (22 vs. 9%, p = 0.002), but similar proportions completed study treatment (88 vs. 89%). Dosing frequency had little effect on 2-mo culture status or tolerability of therapy. The addition of moxifloxacin to isoniazid, rifampin, and pyrazinamide did not affect 2-mo sputum culture status but did show increased activity at earlier time points.

16α‐Bromoepiandrosterone Restores T Helper Cell Type 1 Activity and Accelerates Chemotherapy‐Induced Bacterial Clearance in a Model of Progressive Pulmonary Tuberculosis

BALB/c mice with pulmonary tuberculosis develop a T helper cell type 1 response that peaks at 3 weeks, temporarily controlling bacterial growth. Then bacterial proliferation recommences, accompanied by increasing interleukin (IL)-4 levels and decreasing interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and inducible nitric oxide synthase (iNOS) levels. These changes mimic those in the human disease. In a previous study, administration of dehydroepiandrosterone (DHEA) beginning on day 60 after infection reversed these changes and protected the mice. However, DHEA is suboptimal for human use, partly because it is readily metabolized into sex steroids. 16alpha-Bromoepiandrosterone (EpiBr; 16alpha -bromo-5alpha -androstan-3beta-ol-17-one) is a synthetic adrenal steroid derivative that does not enter sex steroid pathways. In the present study, when tuberculous BALB/c mice were treated with EpiBr 3 times/week beginning on day 60, inhibition of bacterial proliferation and increased expression of TNF-alpha, IFN-gamma, and iNOS were observed, although decreased expression of IL-4 was also observed. Moreover, when given as an adjunct to conventional chemotherapy, EpiBr enhanced bacterial clearance. Trials for the use of EpiBr in the treatment of human tuberculosis are now justified.

Double-blind placebo-controlled trial of Mycobacterium vaccae immunotherapy for tuberculosis in KwaZulu, South Africa, 1991–1997

To investigate Mycobacterium vaccae immunotherapy in the treatment of human tuberculosis and to assess longer-term outcomes following treatment for tuberculosis patients, a double-blind placebo-controlled Phase-2 clinical trial was set up in the Mseleni and Manguzi health wards in north-eastern KwaZulu, South Africa. In 1991–1993, 204 patients admitted with clinical tuberculosis to the 2 hospitals were allocated to receive single intradermal doses of 0.1 mL M. vaccae NCTC 11659 or 0.1 mL tetanus toxoid alongside standard 6-months chemotherapy with rifampicin, isoniazid, pyrazinamide and ethambutol. The main outcome measures were sputum bacteriology culture conversion to negativity, clinical assessment, weight gain, erythrocyte sedimentation rate and chest radiography. Patients were followed-up after 4 years to determine their health status. M. vaccae cases gained weight more quickly during the first 8 weeks compared with ‘placebo’ patients. Regression analysis found a synergistic relationship between BCG positive scar status and M. vaccae-induced weight gain. No further difference was found between treatment groups. The bacterial conversion rate to negativity at 2 months was much lower than expected (44.8% active, 38.8% placebo). Mortality was considerably higher than expected after treatment (7.1% each group) and after 4 years (25.8% active, 21.0% placebo; death from tuberculosis 14.5% and 16.1%, respectively). Immune sensitization to environmental mycobacteria may explain the geographical variability of M. vaccae efficacy, as occurs with BCG vaccination and occurred with Koch's tuberculins of the late 19th century. Multiple doses of M. vaccae may be more effective. Further work is required to link the ability of M. vaccae to modulate protective cytokine profiles to favourable outcome in clinical studies. The high mortality found in this study suggests urgent reviews of chemotherapy and monitoring of patients are necessary in KwaZulu.

Effect of proton pump inhibitor alone or in combination with clarithromycin on mycobacterial growth in human alveolar macrophages.

The effect of omeprazole, a clinically used proton pump inhibitor, alone or in combination with clarithromycin was evaluated against Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium tuberculosis, using a human alveolar macrophage model of infection. Omeprazole exhibited no significant effect on the growth of the two M. avium complex strains or on the mycobactericidal activity of clarithromycin against them. In contrast, omeprazole significantly promoted the growth of Mycobacterium tuberculosis and the anti-mycobacterial activity of clarithromycin against it in human alveolar macrophages. It was speculated that intracellular acidic milieu around M. tuberculosis might be one reason for the lower activity of clarithromycin in the treatment of human tuberculosis.

Effect of proton pump inhibitor alone or in combination with clarithromycin on mycobacterial growth in human alveolar macrophages

The effect of omeprazole, a clinically used proton pump inhibitor, alone or in combination with clarithromycin was evaluated against Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium tuberculosis, using a human alveolar macrophage model of infection. Omeprazole exhibited no significant effect on the growth of the two M. avium complex strains or on the mycobactericidal activity of clarithromycin against them. In contrast, omeprazole significantly promoted the growth of Mycobacterium tuberculosis and the anti-mycobacterial activity of clarithromycin against it in human alveolar macrophages. It was speculated that intracellular acidic milieu around M. tuberculosis might be one reason for the lower activity of clarithromycin in the treatment of human tuberculosis.

Studies of bacillary populations in experimental tuberculosis of mice treated by isoniazid.

When mice are infected with a large dose of virulent tubercle bacilli and treated with isoniazid alone after an interval of fifteen days, resistant populations emerge very frequently. This fact, noted by Grumbach, is not confined to isoniazid, but is produced with many other antibacillary agents (1-3). Treatment of established murine tuberculosis under certain conditions thus furnishes a useful experimental model for the quantitative study of resistant populations appearing in m:vo. Similar populations have been observed in vivo in other experimental circumstances (4-8); but up to now precise quantitative studies on their conditions of emergence and their composition arc lacking. Even in man such studies are rare (9, 10). The fact that it is necessary to administer a single antituberculous agent to obtain experimentally resistant populations, when the treatment of human tuberculosis is usually with multiple-drug regimens, does not detract from the utility of ElIch studies, as resistant populations appearing in these two circumstances only differ in one single character, their frequency. The present work is a quantitative and qualitative study of populations of tubercle bacilli founel in the lungs of mice during delayed treatment with isoniazid. Two different doses have been used, one large, the other small, and the evolution of baeillary populations has been studied in relation to the active isoniazid concentration found in blood serum with these two doses of isoniazid. The administration of large doses of isoniazid is of topical interest. The study of the concentration of active isoniazid in blood serum has given rise to much work, and will give rise to more. Although the prineipal aim of the present work is to draw attention to certain fundamental obscurities which persist in our knowledge of the mechanisms of appearance of great resistant populations, the practical implications will also be considereq.

Massive necrosis of the liver following iproniazid.

Excerpt The hydrazine derivatives of isonicotinic acid (isoniazid and iproniazid) have been used effectively in the treatment of human tuberculosis. However, significant side-effects have occurred ...

Advances in the pharmacological study of cerase—A new anti-tuberculous agent

Summary Although several enzymes have previously been tried therapeutically, cerase is the first to show definite antibacterial effect. Low toxicity and highly specific antibacterial activity facilitate clinical research, and the apparent anti-tuberculous activity in both animal and human cases justifies larger scale clinical trials, which are in progress. Besides bibliographical data, this article contains information about the pharmacological properties of cerase, and preliminary observations on its use in the treatment of human tuberculosis.