Corticosteroids as an adjunct to tuberculosis therapy

Diabetes and tuberculosis: An emerging dual threat to healthcare

Tuberculosis (TB) remains a huge global healthcare challenge even in the 21^st century though the prevalence has dropped in developed countries in recent decades. Diabetes mellitus (DM) is an important risk factor for the development and perpetuation of TB owing to the immune dysfunction in patients with DM. The coexistence of both diseases in the same individual also aggravates disease severity, complications, and chance of treatment failure because of gross immune alterations posed by DM as well as TB. Various complex cellular and humoral immunological factors are involved in the dangerous interaction between TB and DM, some of which remain unknown even today. It is highly important to identify the risk factors for TB in patients with DM, and vice versa, to ensure early diagnosis and management to prevent complications from this ominous coexistence. In their research study published in the recent issue of the World Journal of Diabetes, Shi et al elaborate on the factors associated with the development of TB in a large cohort of DM patients from China. More such research output from different regions of the world is expected to improve our knowledge to fight the health devastation posed by TB in patients with diabetes.

The advances in adjuvant therapy for tuberculosis with immunoregulatory compounds

Tuberculosis (TB) is a chronic bacterial disease, as well as a complex immune disease. The occurrence, development, and prognosis of TB are not only related to the pathogenicity of Mycobacterium tuberculosis (Mtb), but also related to the patient's own immune state. The research and development of immunotherapy drugs can effectively regulate the body's anti-TB immune responses, inhibit or eliminate Mtb, alleviate pathological damage, and facilitate rehabilitation. This paper reviews the research progress of immunotherapeutic compounds for TB, including immunoregulatory compounds and repurposing drugs, and points out the existing problems and future research directions, which lays the foundation for studying new agents for host-directed therapies of TB.

Diagnosis and management of severe pulmonary and extrapulmonary tuberculosis in critically ill patients: A mini review for clinicians

Among critically ill patients, severe pulmonary and extrapulmonary tuberculosis has high morbidity and mortality. Yet, it is a diagnostic challenge given its nonspecific clinical symptoms and signs in early stages of the disease. In addition, management of severe pulmonary and extrapulmonary tuberculosis is complicated given the high risk of drug-drug interactions, drug-disease interactions, and adverse drug reactions. To help clinicians acquire an up-to-date approach to severe tuberculosis, this paper will provide a narrative review of contemporary diagnosis and management of severe pulmonary and extrapulmonary tuberculosis in critically ill patients.

Testing novel strategies for patients hospitalised with HIV-associated disseminated tuberculosis (NewStrat-TB): protocol for a randomised controlled trial

BACKGROUND

HIV-associated tuberculosis (TB) contributes disproportionately to global tuberculosis mortality. Patients hospitalised at the time of the diagnosis of HIV-associated disseminated TB are typically severely ill and have a high mortality risk despite initiation of tuberculosis treatment. The objective of the study is to assess the safety and efficacy of both intensified TB treatment (high dose rifampicin plus levofloxacin) and immunomodulation with corticosteroids as interventions to reduce early mortality in hospitalised patients with HIV-associated disseminated TB.

METHODS

This is a phase III randomised controlled superiority trial, evaluating two interventions in a 2 × 2 factorial design: (1) high dose rifampicin (35 mg/kg/day) plus levofloxacin added to standard TB treatment for the first 14 days versus standard tuberculosis treatment and (2) adjunctive corticosteroids (prednisone 1.5 mg/kg/day) versus identical placebo for the first 14 days of TB treatment. The study population is HIV-positive patients diagnosed with disseminated TB (defined as being positive by at least one of the following assays: urine Alere LAM, urine Xpert MTB/RIF Ultra or blood Xpert MTB/RIF Ultra) during a hospital admission. The primary endpoint is all-cause mortality at 12 weeks comparing, first, patients receiving intensified TB treatment to standard of care and, second, patients receiving corticosteroids to those receiving placebo. Analysis of the primary endpoint will be by intention to treat. Secondary endpoints include all-cause mortality at 2 and 24 weeks. Safety and tolerability endpoints include hepatoxicity evaluations and corticosteroid-related adverse events.

DISCUSSION

Disseminated TB is characterised by a high mycobacterial load and patients are often critically ill at presentation, with features of sepsis, which carries a high mortality risk. Interventions that reduce this high mycobacterial load or modulate associated immune activation could potentially reduce mortality. If found to be safe and effective, the interventions being evaluated in this trial could be easily implemented in clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04951986. Registered on 7 July 2021 https://clinicaltrials.gov/study/NCT04951986.

Tobacco smoke exposure recruits inflammatory airspace monocytes that establish permissive lung niches for Mycobacterium tuberculosis

Tobacco smoking doubles the risk of active tuberculosis (TB) and accounts for up to 20% of all active TB cases globally. How smoking promotes lung microenvironments permissive to Mycobacterium tuberculosis (Mtb) growth remains incompletely understood. We investigated primary bronchoalveolar lavage cells from current and never smokers by performing single-cell RNA sequencing (scRNA-seq), flow cytometry, and functional assays. We observed the enrichment of immature inflammatory monocytes in the lungs of smokers compared with nonsmokers. These monocytes exhibited phenotypes consistent with recent recruitment from blood, ongoing differentiation, increased activation, and states similar to those with chronic obstructive pulmonary disease. Using integrative scRNA-seq and flow cytometry, we identified CD93 as a marker for a subset of these newly recruited smoking-associated lung monocytes and further provided evidence that the recruitment of monocytes into the lung was mediated by CCR2-binding chemokines, including CCL11. We also show that these cells exhibit elevated inflammatory responses upon exposure to Mtb and accelerated intracellular growth of Mtb compared with mature macrophages. This elevated Mtb growth could be inhibited by anti-inflammatory small molecules, providing a connection between smoking-induced pro-inflammatory states and permissiveness to Mtb growth. Our findings suggest a model in which smoking leads to the recruitment of immature inflammatory monocytes from the periphery to the lung, which results in the accumulation of these Mtb-permissive cells in the airway. This work defines how smoking may lead to increased susceptibility to Mtb and identifies host-directed therapies to reduce the burden of TB among those who smoke.

Glue ablation of Rasmussen's aneurysm in a case of epituberculosis

A woman in her 40s presented with massive haemoptysis and breathlessness for 1 day. She had been diagnosed with pulmonary tuberculosis based on sputum CBNAAT (Cartridge Based Nucleic Acid Amplification Test) and was on antitubercular treatment for previous 2 weeks. Her chest X-ray showed right middle lobe lateral segment dense consolidation with bilateral nodular infiltrates. CT pulmonary angiography (CTPA) revealed a well-defined homogenously enhancing vascular lesion of size 10×11×13 mm in the right hilar region communicating with the descending branch of right pulmonary artery, suggesting a Rasmussen's aneurysm. It was in close proximity to the segmental bronchus that was almost completely occluded, suggesting epituberculosis. Transvenous pulmonary artery glue embolisation successfully achieved complete ablation of the aneurysm with preserved arterial flow. She has later completed 6 months of antitubercular treatment and is cured with no recurrence of haemoptysis. Her lung infiltrates have resolved with some lung scarring.

Pneumonia in the Pandemic: Not Always COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has changed the way we manage patients, especially those with respiratory illnesses. Clinical manifestations, chest imaging, and reverse-transcription polymerase chain reaction (RT-PCR) play major roles in diagnosing respiratory infections during a pandemic. However, several infections can mimic COVID-19 regarding its clinical signs, symptoms, and imaging appearance. Diagnosing pneumonia other than COVID-19 is a big challenge in developing countries, given the limited resources available. We presented a case of a 25-year-old female with clinical symptoms and radiological characteristics typical of COVID-19 but a repeated negative RT-PCR test. Further workups found lung tuberculosis as her primary diagnosis. Our patient continued treatment with an antituberculosis agent and a short course of steroids, with a remission of symptoms.

Tweaking host immune responses for novel therapeutic approaches against Mycobacterium tuberculosis

In TB, combat between the human host and Mycobacterium tuberculosis involves intricate interactions with immune cells. M. tuberculosis has evolved a complex evasion system to circumvent immune cells, leading to persistence and limiting its clearance by the host. Host-directed therapies are emerging approaches to modulate host responses, including inflammatory responses, cytokine responses, and autophagy, by using small molecules to curb mycobacterial infections. Targeting host immune pathways reduces the chances of antibiotic resistance to M. tuberculosis because, unlike antibiotics, this approach acts directly on the cells of the host. In this review, we discuss the role of immune cells during M. tuberculosis proliferation, provide a updated understanding of immunopathogenesis, and explore the range of host-modulating options for the clearance of this pathogen.

What Came First: Malnutrition or Severe Disease?

A 20-year-old female with depression presented to the emergency department with chronic weight loss, weakness, fatigue, hair loss, rash, palpitations, and 2 weeks of cough. Initial history revealed that she had disordered eating habits with dietary restriction, experienced a 50-pound unintentional weight loss over 2 years despite reported adherence to nutritional supplementation, and had a normal gastrointestinal workup. On examination, she was markedly cachectic with a BMI of 10.3kg/m2 and hypotensive (84/69 mmHg). Her cardiovascular examination revealed a regular rate and rhythm without a murmur. Her breath sounds were diminished in the upper lobes bilaterally. A skin examination showed diffuse hair loss, skin breakdown, and peeling with a tender, erythematous, papular rash over the bilateral ankles, and nonpitting edema. A chest radiograph showed a right upper lobe opacity and lucent lesions in the left proximal humerus. A focused assessment with sonography for trauma examination showed a large pericardial effusion. Chest computed tomography revealed a right upper lobe opacity with an associated cavitation. Though she began improving with rifampin, isoniazid, pyrazinamide, ethambutol, levofloxacin, azithromycin, and nutritional rehabilitation, her clinical course was complicated by an acute worsening nearly 1 month into her hospitalization with persistent high fevers, worsening cough, development of a murmur, and worsening consolidation on chest computed tomography. Adolescent Medicine, Infectious Diseases, Gastroenterology, and Allergy and Immunology were consulted to guide the diagnostic evaluation and management of this patient's complex clinical course.

[Tuberculosis-Update 2022]

According to the annual global reports from the Word Health Organization (WHO), children under 15 years of age represent 11% of all cases of tuberculosis (TB) globally. Nearly 50% of these cases are children below 5 years old. This continuing medical education (CME) article provides an overview of the current recommendations and innovations based on the revised WHO guidelines on TB management in children and adolescents published in 2022.

Pulmonary tuberculosis associated acute fibrinous and organizing pneumonia: A case report and literature review

BACKGROUND

Acute fibrinous and organizing pneumonia (AFOP) is a rare histological interstitial pneumonia pattern characterized by patches of "fibrin balls" distributed within the alveoli and organizing pneumonia. Currently, there is no consensus on the diagnosis and treatment of this disease.

METHODS

We present the case of a 44-year-old male with AFOP secondary to Mycobacterium tuberculosis. We have further reviewed organizing pneumonia (OP) and AFOP caused by tuberculosis.

CONCLUSION

Tuberculosis secondary to OP or AFOP is rare and challenging to diagnose. We need to constantly adjust the treatment plan based on the patient's symptoms, test results, and response to treatment in order to arrive at an accurate diagnosis and maximize treatment efficacy.

Massive generalised lymphadenopathy: a rare presentation of tuberculosis with a favourable outcome

We present a case of massive generalised necrotic lymphadenopathy due to tuberculosis (TB) without any solid organ involvement. An immunocompetent man in his early 30s presented 1 year ago with weight loss, cough and a solitary cervical node. Contrast-enhanced CT scan thorax showed massive enlargement of almost all groups of mediastinal nodes with large areas of necrosis. Ultrasound examination revealed multiple necrotic abdominal nodes. Core biopsy of the supraclavicular node confirmed TB by histopathology and molecular testing. His Mantoux test was negative suggesting tuberculin anergy. Biopsy of deep nodes was avoided. He responded well to standard antitubercular treatment in weight-corrected doses along with systemic steroids which were prescribed to prevent further breakdown/rupture of nodes. After the extended TB treatment for 12 months, he is asymptomatic and has gained weight, with complete resolution of cervical node and near complete resolution of all deep nodes.

Inflammation-mediated tissue damage in pulmonary tuberculosis and host-directed therapeutic strategies

Treatment of tuberculosis (TB) involves the administration of anti-mycobacterial drugs for several months. The emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb, the causative agent) together with increased disease severity in people with co-morbidities such as diabetes mellitus and HIV have hampered efforts to reduce case fatality. In severe disease, TB pathology is largely attributable to over-exuberant host immune responses targeted at controlling bacterial replication. Non-resolving inflammation driven by host pro-inflammatory mediators in response to high bacterial load leads to pulmonary pathology including cavitation and fibrosis. The need to improve clinical outcomes and reduce treatment times has led to a two-pronged approach involving the development of novel antimicrobials as well as host-directed therapies (HDT) that favourably modulate immune responses to Mtb. HDT strategies incorporate aspects of immune modulation aimed at downregulating non-productive inflammatory responses and augmenting antimicrobial effector mechanisms to minimise pulmonary pathology and accelerate symptom resolution. HDT in combination with existing antimycobacterial agents offers a potentially promising strategy to improve the long-term outcome for TB patients. In this review, we describe components of the host immune response that contribute to inflammation and tissue damage in pulmonary TB, including cytokines, matrix metalloproteinases, lipid mediators, and neutrophil extracellular traps. We then proceed to review HDT directed at these pathways.

Host-Directed Targeting of LincRNA-MIR99AHG Suppresses Intracellular Growth of Mycobacterium tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) kills 1.6 million people worldwide every year, and there is an urgent need for targeting host-pathogen interactions as a strategy to reduce mycobacterial resistance to current antimicrobials. Noncoding RNAs are emerging as important regulators of numerous biological processes and avenues for exploitation in host-directed therapeutics. Although long noncoding RNAs (lncRNAs) are abundantly expressed in immune cells, their functional role in gene regulation and bacterial infections remains understudied. In this study, we identify an immunoregulatory long intergenic noncoding RNA, lincRNA-MIR99AHG, which is upregulated in mouse and human macrophages upon IL-4/IL-13 stimulation and downregulated after clinical Mtb HN878 strain infection and in peripheral blood mononuclear cells from active TB patients. To evaluate the functional role of lincRNA-MIR99AHG, we used antisense locked nucleic acid (LNA) GapmeR-mediated antisense oligonucleotide (ASO) lncRNA knockdown experiments. Knockdown of lincRNA-MIR99AHG with ASOs significantly reduced intracellular Mtb growth in mouse and human macrophages and reduced pro-inflammatory cytokine production. In addition, in vivo treatment of mice with MIR99AHG ASOs reduced the mycobacterial burden in the lung and spleen. Furthermore, in macrophages, lincRNA-MIR99AHG is translocated to the nucleus and interacts with high affinity to hnRNPA2/B1 following IL-4/IL-13 stimulation and Mtb HN878 infection. Together, these findings identify lincRNA-MIR99AHG as a positive regulator of inflammation and macrophage polarization to promote Mtb growth and a possible target for adjunctive host-directed therapy against TB.

Adjunctive corticosteroid therapy in patients with pulmonary tuberculosis

OBJECTIVES

In tuberculosis treatment, corticosteroids are used as adjuvants, especially in meningeal/pericardial tuberculosis. In other forms of the disease, especially in severe tuberculosis requiring mechanical ventilation, its use is controversial. The aim of the present study is to assess whether the use of corticosteroids in the treatment of pulmonary tuberculosis patients in mechanical ventilation is associated with in-hospital mortality.

METHODS

This is a retrospective cohort study. Tuberculosis patients >18 years requiring mechanical ventilation, admitted to the emergency department or intensive care unit, were included. Data on corticosteroid use and mortality were collected.

RESULTS

In total, 467 patients were included in the analysis; 399 used corticosteroids and 68 were noncorticosteroid users. The mortality rate was higher among corticosteroid users (59.9%) than in noncorticosteroid users (41.2%) (p=0.010). The total dose of corticosteroid in prednisone equivalents was not different between survivors and nonsurvivors (median [interquartile range]: 80 mg [5-56.6 mg] vs. 80 mg [50-135 mg]; p=0.881).

CONCLUSIONS

Tuberculosis patients in mechanical ventilation who used corticosteroids had a higher mortality rate than those who did not use corticosteroids. The role of corticosteroids in pulmonary tuberculosis, especially in critically ill patients, remains unclear and needs further evaluation in prospective studies.

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.

Musculoskeletal Tuberculosis: New Insights on Diagnosis Strategy and Treatment

BACKGROUND/ OBJECTIVE

Skeletal tuberculosis (TB) is rare. We aimed to report on diagnostic strategy and treatment of skeletal TB.

METHODS

In this multidisciplinary single-center medical records review study, all adult patients admitted between January 2009 and December 2019 with microbiologically proven skeletal TB were included. Demographic, medical history, laboratory, imaging, pathologic findings, treatment, and follow-up data were extracted from medical records.

RESULTS

Among 184 patients identified with TB, 21 (16 women, 42 years [27, 48 years]) had skeletal involvement. Skeletal TB included spondylitis (n = 11), lytic bone lesions (n = 7), sacroiliitis (n = 5), arthritis (n = 3), osteitis (n = 2), and diffuse muscle abscesses without bone lesion (n = 1). Lytic lesions involved both axial and peripheral skeleton at multiple sites in most cases. 18F-fluorodeoxyglucose positron emission tomography was performed in 13 patients and helped to detect multifocal asymptomatic lesions and to target biopsy. All patients were treated with anti-TB therapy for 7 to 18 months. Fifteen patients (71.4%) received steroids as an adjunct therapy. Eleven patients needed an orthopedic immobilization corset, and 3 patients underwent surgery. All patients clinically improved under treatment, but 2 relapsed over a median follow-up of 24 months (12-30 months). No patient died or suffered long-term disabilities.

CONCLUSION

Our study emphasizes the diversity of skeletal involvement in TB. 18F-fluorodeoxyglucose positron emission tomography scanner at diagnosis is key to assess the extension of skeletal involvement and guide extraskeletal biopsy. Neurological complications might be prevented by adding corticosteroids to anti-TB therapy.

Recent Advances in Host-Directed Therapies for Tuberculosis and Malaria

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, and malaria, caused by parasites from the Plasmodium genus, are two of the major causes of death due to infectious diseases in the world. Both diseases are treatable with drugs that have microbicidal properties against each of the etiologic agents. However, problems related to treatment compliance by patients and emergence of drug resistant microorganisms have been a major problem for combating TB and malaria. This factor is further complicated by the absence of highly effective vaccines that can prevent the infection with either M. tuberculosis or Plasmodium. However, certain host biological processes have been found to play a role in the promotion of infection or in the pathogenesis of each disease. These processes can be targeted by host-directed therapies (HDTs), which can be administered in conjunction with the standard drug treatments for each pathogen, aiming to accelerate their elimination or to minimize detrimental side effects resulting from exacerbated inflammation. In this review we discuss potential new targets for the development of HDTs revealed by recent advances in the knowledge of host-pathogen interaction biology, and present an overview of strategies that have been tested in vivo, either in experimental models or in patients.

Analysis of risk factors for pulmonary tuberculosis with persistent severe inflammation: An observational study

INTRODUCTION

Patients with pulmonary tuberculosis (TB) sometimes show persistent severe inflammation for more than 1 month, even if TB treatment is effective. Although this inflammation can be improved through continuous antituberculous therapy, the risk factors for persistent inflammation remain unclear. Therefore, we sought to study the characteristics of patients with persistent severe inflammation.

MATERIALS AND METHODS

We retrospectively analyzed 147 hospitalized adult patients with C-reactive protein (CRP) levels of 5 mg/dL or more on admission to Fukujuji Hospital from April 2019 to March 2021. The patients were divided into 2 groups: 40 patients (27.2%) had CRP levels of 5 mg/dL or more at 4 weeks after admission (persistent inflammation group), and 107 patients (72.8%) had CRP levels that fell below 5 mg/dL within 4 weeks of admission (improved inflammation group).

RESULTS

The median CRP level on admission in the persistent inflammation group was 10.8 mg/dL (interquartile range 9.1-14.5), which was higher than that in the improved inflammation group (median 8.2 mg/dL [6.5-12.1], P = .002). Patients in the persistent inflammation group had a higher prevalence of large cavities, defined as cavities ≥4 cm in diameter, on chest computed tomography (CT) (n = 20 [50.0%] vs n = 12 [11.2%], P < .001).

DISCUSSION AND CONCLUSIONS

This study showed that 27.2% of patients who had high or moderate inflammation on admission did not achieve low CRP levels within 4 weeks after admission. Risk factors for persistent severe inflammation in patients with TB were presence of a large cavity (cavity diameter ≥4 cm) on chest CT and a high CRP level on admission. Therefore, in a patient with a large cavity on chest CT and/or CRP ≥9.0 mg/dL on admission, long-term inflammation may occur despite antituberculous therapy if other diseases are ruled out.

Tuberculous Pericarditis—Own Experiences and Recent Recommendations

Tuberculous pericarditis (TBP) accounts for 1% of all forms of tuberculosis and for 1–2% of extrapulmonary tuberculosis. In endemic regions, TBP accounts for 50–90% of effusive pericarditis; in non-endemic, it only accounts for 4%. In the absence of prompt and effective treatment, TBP can lead to very serious sequelae, such as cardiac tamponade, constrictive pericarditis, and death. Early diagnosis of TBP is a cornerstone of effective treatment. The present article summarises the authors’ own experiences and highlights the current status of knowledge concerning the diagnostic and therapeutic algorithm of TBP. Special attention is drawn to new, emerging molecular methods used for confirmation of M. tuberculosis infection as a cause of pericarditis.

(R)-(+)-Lasiodiplodin isolated from the endophytic fungus Sordaria tamaensis exhibits potent antimycobacterial and anti-inflammatory activities in vitro and in vivo: a dual approach for the treatment of severe pulmonary tuberculosis

OBJECTIVES

This study aimed to evaluate endophytic fungi isolated from Tocoyena bullata and Humiria balsamifera plant species for their antimycobacterial and anti-inflammatory activities, focusing on severe pulmonary tuberculosis cases which are often associated with exacerbated inflammation.

METHODS

Mycobacterium suspensions were incubated with the samples for 5 days. RAW 264.7 macrophages stimulated with LPS were also incubated with them for 24 h to assess the inhibition of inflammatory mediator production and cytotoxicity. C57BL/6 mice were infected with Mtb M299 and treated for 15 days with lasiodiplodin (Lasio).

KEY FINDINGS

Endophytic fungus Sordaria tamaensis, obtained from T. bullata, was the most promising. Its ethanolic extract impaired mycobacterial growth with MIC50 (µg/ml): 1.5 ± 0.6 (BCG), 66.8 ± 0.1 (H37Rv) and 80.0 ± 0.1 (M299). (R)-(+)-Lasio showed MIC50 92.2 ± 1.8 µg/ml (M299). In addition, Lasio was able to inhibit NO, IL-1β and TNF-α production and was not cytotoxic for macrophages. M. tuberculosis-infected C57BL/6 animals treated by Lasio reduced the number of acid-fast bacilli, lung pathology, leucocyte influx and proinflammatory cytokine production in the lungs. The class IIa fructose 1,6-bisphosphate aldolase was the predicted hypothetical target of Lasio.

CONCLUSIONS

(R)-(+)-Lasio stood out as a promising anti-TB compound, exhibiting anti-inflammatory and antimycobacterial effects, as well as low cytotoxicity.

Paradoxical manifestations during tuberculous meningitis treatment among HIV-negative patients: a retrospective descriptive study and literature review

BACKGROUND

Tuberculous meningitis (TBM) is the most frequent, severe, and disabling form of central nervous system (CNS) tuberculosis (TB). TBM paradoxical manifestations are characterized by clinical or paraclinical worsening after 1 month of effective anti-TB treatment in patients who initially responded to treatment despite the use of adjunctive corticosteroids.

METHODS

Retrospective descriptive study of consecutive HIV-negative adult patients (≥ 18 years) with definitive TBM who developed a paradoxical manifestation following anti-TB in a tertiary-care hospital in Mexico from 2009 to 2019; we also conducted a literature review of published cases/series of paradoxical manifestations in HIV-negative patients from 1980 to 2020.

RESULTS

We detected 84 cases of definitive TBM; 55 (68.7%) HIV-negative patients and 29 (36.3%) HIV-infected patients. Among HIV-negative patients, four (7.3%), three female and one male (19-49 years old), developed a paradoxical manifestation within 4-14 weeks following treatment initiation despite receiving adequate corticosteroid doses; Mycobacterium bovis was isolated from the cerebrospinal fluid of three cases and Mycobacterium tuberculosis in one more. Two patients developed vasculopathy-related cerebral infarctions, one severe basilar meningitis, and hydrocephalus, one more a tuberculoma. Two were treated with intravenous cyclophosphamide, and two with steroids. One of the patients treated with steroids died; patients who received cyclophosphamide had a good clinical response.

CONCLUSIONS

This case series illustrates the diverse clinical/radiologic paradoxical manifestations of TBM in HIV-negative patients. Cyclophosphamide may be safe and effective in treating TBM-associated paradoxical manifestations. Specific diagnostic and care protocols for these patients are needed.

Disseminated Tuberculosis With Cardiac Tamponade in an Immunocompetent Individual

We report a case of disseminated tuberculosis with cardiac tamponade in a 26-year-old man from northern Portugal. He was imprisoned for one year before the diagnosis and had no known immunosuppressing conditions. A high level of suspicion with a detailed review of risk factors and exposure history (e.g., in this case, imprisonment is a risk factor for tuberculosis) is necessary when pursuing a diagnosis of extrapulmonary tuberculosis and treatment should be started as soon as possible when life-threatening manifestations occur. We used a 12-month course of antituberculosis agents associated with steroids, in our case. The patient had a good clinical response and no signs of disease at the end of the treatment.

P2x7 Receptor Signaling Blockade Reduces Lung Inflammation and Necrosis During Severe Experimental Tuberculosis

The risk of developing severe forms of tuberculosis has increased by the acquired immunodeficiency syndrome (AIDS) epidemic, lack of effective drugs to eliminate latent infection and the emergence of drug-resistant mycobacterial strains. Excessive inflammatory response and tissue damage associated with severe tuberculosis contribute to poor outcome of the disease. Our previous studies using mice deficient in the ATP-gated ionotropic P2X7 receptor suggested this molecule as a promising target for host-directed therapy in severe pulmonary tuberculosis. In this study, we assessed the effects of P2X7 pharmacological blockade on disease severity. First, we observed an increase in P2RX7 gene expression in the peripheral blood of tuberculosis patients compared to healthy donors. Lung leukocytes of mice infected with hypervirulent mycobacteria also showed increased expression of the P2X7 receptor. P2X7 blockade in mice with advanced tuberculosis recapitulated in many aspects the disease in P2X7-deficient mice. P2X7-directed therapy reduced body weight loss and the development of inflammatory and necrotic lung lesions, as well as delayed mycobacterial growth. Lower TNF-α production by lung cells and a substantial reduction in the lung GR-1⁺ myeloid cell population were observed after P2X7 inhibition. The effector CD4⁺ T cell population also decreased, but IFN-γ production by lung cells increased. The presence of a large population with characteristics of myeloid dendritic cells, as well as the increase in IL-6 production by lung cells, also indicate a qualitative improvement in the pulmonary immune response due to P2X7 inhibition. These findings support the use of drugs that target the P2X7 receptor as a therapeutic strategy to improve the outcome of pulmonary tuberculosis.

The Innate Immune Response to Mycobacterium tuberculosis Infection

Infection with Mycobacterium tuberculosis causes >1.5 million deaths worldwide annually. Innate immune cells are the first to encounter M. tuberculosis, and their response dictates the course of infection. Dendritic cells (DCs) activate the adaptive response and determine its characteristics. Macrophages are responsible both for exerting cell-intrinsic antimicrobial control and for initiating and maintaining inflammation. The inflammatory response to M. tuberculosis infection is a double-edged sword. While cytokines such as TNF-α and IL-1 are important for protection, either excessive or insufficient cytokine production results in progressive disease. Furthermore, neutrophils-cells normally associated with control of bacterial infection-are emerging as key drivers of a hyperinflammatory response that results in host mortality. The roles of other innate cells, including natural killer cells and innate-like T cells, remain enigmatic. Understanding the nuances of both cell-intrinsic control of infection and regulation of inflammation will be crucial for the successful development of host-targeted therapeutics and vaccines.

[Steroids in infection medicine]

Corticosteroids have been found as useful adjunctive therapy in patients with various infections and hyperinflammation-associated disease. They are recommended in practice guidelines for patients with tuberculous and pneumococcal meningitis and patients with immune reconstitution syndrome associated with antiretroviral therapy. A new indication is severe COVID-19. Evidence from clinical trials is insufficient to allow the routine use of steroids among patients with septic shock, community-acquired pneumonia or tuberculous pericarditis.

The New Frontier of Host-Directed Therapies for Mycobacterium avium Complex

Mycobacterium avium complex (MAC) is an increasingly important cause of morbidity and mortality, and is responsible for pulmonary infection in patients with underlying lung disease and disseminated disease in patients with AIDS. MAC has evolved various virulence strategies to subvert immune responses and persist in the infected host. Current treatment for MAC is challenging, requiring a combination of multiple antibiotics given over a long time period (for at least 12 months after negative sputum culture conversion). Moreover, even after eradication of infection, many patients are left with residual lung dysfunction. In order to address similar challenges facing the management of patients with tuberculosis, recent attention has focused on the development of novel adjunctive, host-directed therapies (HDTs), with the goal of accelerating the clearance of mycobacteria by immune defenses and reducing or reversing mycobacterial-induced lung damage. In this review, we will summarize the evidence supporting specific adjunctive, HDTs for MAC, with a focus on the repurposing of existing immune-modulatory agents targeting a variety of different cellular pathways. We also highlight areas meriting further investigation.

A case of broncho-cutaneous fistula secondary to tuberculosis successfully managed with awake veno-venous extracorporeal membrane oxygenation

A broncho-cutaneous fistula (BCF) is a communicating tract between the bronchus and the cutaneous surface of the thoracic wall and can be the primary presenting sign of several disease processes. It has been associated with positive pressure ventilation (PPV), post pneumonectomy, thoracostomy tubes, perforating chest trauma, neoplasia and chronic empyema. We report a case of a 45-year-old immunocompetent man presenting with severe hypercapnic respiratory failure secondary to a BCF as a result of tuberculosis (TB)-related empyema necessitans. Veno-venous extracorporeal membrane oxygenation (VV ECMO) was employed during spontaneous breathing to mitigate the risks of PPV, to facilitate diagnostics and enable targeted treatment. Awake VV ECMO is an effective supportive therapy for complex, destructive lung pathologies with a known reversible aetiology in which PPV would be potentially detrimental.

The Prospect of Repurposing Immunomodulatory Drugs for Adjunctive Chemotherapy against Tuberculosis: A Critical Review

Tuberculosis (TB) remains a global health emergency, with an estimated 2 billion people infected across the world, and 1.4 million people dying to this disease every year. Many aspects of the causative agent, Mycobacterium tuberculosis, make this disease difficult for healthcare and laboratory researchers to fight against, such as unique pathophysiology, latent infection and long and complex treatment regimens, thus causing patient non-compliance with the treatment. Development of new drugs is critical for tackling these problems. Repurposing drugs is a promising strategy for generating an effective drug treatment whilst circumventing many of the challenges of conventional drug development. In this regard, the incorporation of immunomodulatory drugs into the standard regimen to potentiate frontline drugs is found to be highly appealing. Drugs of diverse chemical classes and drug categories are increasingly being evidenced to possess antitubercular activity, both in vitro and in vivo. This article explores and discusses the molecular entities that have shown promise in being repurposed for use in anti-TB adjunctive therapy and aims to provide the most up-to-date picture of their progress.

Indole Propionic Acid, an Unusual Antibiotic Produced by the Gut Microbiota, With Anti-inflammatory and Antioxidant Properties

Most antibiotics are produced by soil microbes and typically interfere with macromolecular synthesis processes as their antibacterial mechanism of action. These natural products are often large and suffer from poor chemical tractability. Here, we discuss discovery, mechanism of action, and the therapeutic potentials of an unusual antibiotic, indole propionic acid (IPA). IPA is produced by the human gut microbiota. The molecule is small, chemically tractable, and targets amino acid biosynthesis. IPA is active against a broad spectrum of mycobacteria, including drug resistant Mycobacterium tuberculosis and non-tuberculous mycobacteria (NTM). Interestingly, the microbiota-produced metabolite is detectable in the serum of healthy individuals, tuberculosis (TB) patients, and several animal models. Thus, the microbiota in our gut may influence susceptibility to mycobacterial diseases. If a gut-lung microbiome axis can be demonstrated, IPA may have potential as a biomarker of disease progression, and development of microbiota-based therapies could be explored. In addition to its antimycobacterial activity, the molecule displays anti-inflammatory and antioxidant properties. This raises the possibility that IPA has therapeutic potential as both antibiotic and add-on host-directed drug for the treatment of TB in patient populations where disease morbidity and mortality is driven by excessive inflammation and tissue damage, such as TB-associated immune reconstitution inflammatory syndrome, TB-meningitis, and TB-diabetes.

Effects of host-directed therapies on the pathology of tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), has co-evolved with the human immune system and utilizes multiple strategies to persist within infected cells, to hijack several immune mechanisms, and to cause severe pathology and tissue damage in the host. This delays the efficacy of current antibiotic therapy and contributes to the evolution of multi-drug-resistant strains. These challenges led to the development of the novel approach in TB treatment that involves therapeutic targeting of host immune response to control disease pathogenesis and pathogen growth, namely, host-directed therapies (HDTs). Such HDT approaches can (1) enhance the effect of antibiotics, (2) shorten treatment duration for any clinical form of TB, (3) promote development of immunological memory that could protect against relapse, and (4) ameliorate the immunopathology including matrix destruction and fibrosis associated with TB. In this review we discuss TB-HDT candidates shown to be of clinical relevance that thus could be developed to reduce pathology, tissue damage, and subsequent impairment of pulmonary function. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The immunopathogenesis of tuberculous pericarditis

Tuberculous pericarditis is a severe form of extrapulmonary tuberculosis and is the commonest cause of pericardial effusion in high incidence settings. Mortality ranges between 8 and 34%, and it is the leading cause of pericardial constriction in Africa and Asia. Current understanding of the disease is based on models derived from studies performed in the 1940-50s. This review summarises recent advances in the histology, microbiology and immunology of tuberculous pericarditis, with special focus on the effect of Human Immunodeficiency Virus (HIV) and the determinants of constriction.

Matrix Metalloproteinases in Pulmonary and Central Nervous System Tuberculosis-A Review

Tuberculosis (TB) remains the single biggest infectious cause of death globally, claiming almost two million lives and causing disease in over 10 million individuals annually. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes with various physiological roles implicated as key factors contributing to the spread of TB. They are involved in the breakdown of lung extracellular matrix and the consequent release of Mycobacterium tuberculosis bacilli into the airways. Evidence demonstrates that MMPs also play a role in central nervous system (CNS) tuberculosis, as they contribute to the breakdown of the blood brain barrier and are associated with poor outcome in adults with tuberculous meningitis (TBM). However, in pediatric TBM, data indicate that MMPs may play a role in both pathology and recovery of the developing brain. MMPs also have a significant role in HIV-TB-associated immune reconstitution inflammatory syndrome in the lungs and the brain, and their modulation offers potential novel therapeutic avenues. This is a review of recent research on MMPs in pulmonary and CNS TB in adults and children and in the context of co-infection with HIV. We summarize different methods of MMP investigation and discuss the translational implications of MMP inhibition to reduce immunopathology.

The Immune Mechanisms of Lung Parenchymal Damage in Tuberculosis and the Role of Host-Directed Therapy

Impaired lung function is common in people with a history of tuberculosis. Host-directed therapy added to tuberculosis treatment may reduce lung damage and result in improved lung function. An understanding of the pathogenesis of pulmonary damage in TB is fundamental to successfully predicting which interventions could be beneficial. In this review, we describe the different features of TB immunopathology that lead to impaired lung function, namely cavities, bronchiectasis, and fibrosis. We discuss the immunological processes that cause lung damage, focusing on studies performed in humans, and using chest radiograph abnormalities as a marker for pulmonary damage. We highlight the roles of matrix metalloproteinases, neutrophils, eicosanoids and cytokines, like tumor necrosis factor-α and interleukin 1β, as well as the role of HIV co-infection. Finally, we focus on various existing drugs that affect one or more of the immunological mediators of lung damage and could therefore play a role as host-directed therapy.