HIV/Mtb Co-Infection: From the Amplification of Disease Pathogenesis to an “Emerging Syndemic”

High prevalence and risk factors of positive sputum smear in newly diagnosed pulmonary tuberculosis patients in Vietnam

Objectives

To assess the prevalence and identify risk factors associated with smear-positive tuberculosis (acid-fast bacilli [AFB]-positive) in newly diagnosed patients in Vietnam.

Methods

A retrospective study was conducted on patients newly diagnosed with pulmonary tuberculosis (PTB) from August 2023 to August 2024. Patients were classified as smear-positive if at least one respiratory sample tested positive with AFB before starting anti-tuberculosis treatment. Smear-negative individuals had to submit a minimum of two sputum samples, all of which had to test negative before treatment initiation.

Results

379 PTB patients were included with 48.3% being AFB-positive. The proportion of hemoptysis was significantly higher in AFB-positive than in AFB-negative patients (9.8% versus 4.1%, p=0.04). AFB-negative patients had a significantly higher rate of fatigue and crackles compared to AFB-positive patients with 85.7% versus 77.0%, p=0.03 and 36.2% versus 25.7%, p=0.03, respectively. Cavitary lung lesions were significantly more common in AFB-positive patients (48.6% versus 29.1%, p<0.0001). In multivariate analysis, patients with diabetes mellitus and those with long-term corticosteroid use were respectively three times and six times more likely to be AFB-positive (OR=2.71, p=0.002 and OR=6.15, p=0.009) more likely to. Cavitation in chest-x-ray was also associated with 2.5 times of risk for smear-positive (OR=2.53, p <0.0001). All of three HIV-coinfected patients were AFB-negative.

Conclusion

Our findings emphasize the importance of screening and early diagnosis of PTB in individuals with diabetes mellitus and in those on long-term corticosteroid therapy. Strengthening TB control efforts, particularly among high-risk populations, is crucial to reducing the burden of smear-positive TB and preventing further transmission.

Host-Directed Therapies Based on Protease Inhibitors to Control Mycobacterium tuberculosis and HIV Coinfection

Despite continuous and extensive global efforts in the fight against tuberculosis (TB), this infectious disease continues to exert a tremendous burden on public health concerns and deaths worldwide. TB, caused by the bacterial species Mycobacterium tuberculosis, is highly frequent in people living with HIV. The continuing epidemics of both chronic infections and the emergence of antimicrobial resistance, as well as the lack of effective diagnostic tools and drug-drug interactions, pose major challenges in the fight against these pathogens. Developing a wide range of host-directed therapies may improve treatment outcomes, helping alleviate the morbidity and mortality associated with both infections. In this review, we discuss the identification and development of new host-directed strategies based on protease inhibitors and their clinical relevance as adjunctive treatment. In the context of therapeutic agents with novel mechanisms, selective protease inhibitors, including saquinavir (SQV) and cystatins (CstC and CstF), are valuable targets that may provide effective therapeutic solutions for controlling Mtb and HIV coinfection.

Historical examination of tuberculosis; from ancient affliction to modern challenges

Tuberculosis (TB), white plague, many other definitions is an ancient deadly infection that humans dealt with after creation. The first hypothesis refers to 150 million years ago about the appearance of TB in the Jurassic era before human creation, but documents show 9000 years ago for first appearance in human society. In 1882, Robert Koch was able to identify and describe the best possible agent of TB. After the discovery of TB's agent [Mycobacterium tuberculosis], progress was made in diagnosis and treatment rapidly, and invasive operations such as surgery were replaced with drug treatment and chemical compounds hired for treatment that were so effective before drug resistance occurrence. In this review authors done their tries to describe all aspects of TB [identification, epidemics, diagnostics, drug development, etc.] in history from ancient records to the present condition and give insight into the future of TB ending in 2030 and 2050.

Pulmonary Immunocompromise in Human Immunodeficiency Virus Disease

The spectrum of pulmonary disease in people with human immunodeficiency virus (PWH) across the lifespan has shifted from acute, infectious, and acquired immunodeficiency syndrome (AIDS)-defining illnesses to a greater burden of chronic, non-communicable processes. Here, the authors review the epidemiology and risk factors of pulmonary disease in PWH across the lifespan during the contemporary antiretroviral therapy era. The authors focus on recommendations for clinical care of pulmonary disease relevant to PWH, including emerging data from recent and ongoing clinical trials.

Spatial transcriptomic analysis of HIV and tuberculosis coinfection in a humanized mouse model reveals specific transcription patterns, immune responses and early morphological alteration signaling

Mycobacterium tuberculosis (Mtb) and human immunodeficiency virus (HIV) coinfection is one of the biggest public health concerns worldwide. Both pathogens are adept at modulating immune response and, in the case of Mtb, even inducing structural modification of the affected tissue. The present study aimed at understanding the early phenotypical and functional changes in immune cell infiltration in the affected organ, using a humanized mouse model. The humanized mice were infected with either HIV or Mtb in single infection, or with both pathogens in coinfection. Three weeks after the infection, lung samples were collected, and spatial transcriptomics analysis was performed. This analysis revealed high infiltration of CD4+ T cells in Mtb infection, but not in HIV or coinfection. Coinfected mice also showed a minimal number of NK cells compared to the other groups. In addition to infection status, histological features also influenced the immune cell infiltration pattern in the lungs. Two distinct airway regions with distinct immune cell abundance patterns were detected by spatial transcriptome profiling. A lymphoid cell aggregate detected in coinfection lung exhibited distinct transcript profile. The cellular architecture in the lymphoid cell aggregate did not follow the spatial patterns seen in mature granulomas. However, lymphoid cell aggregates exhibited granuloma gene expression signatures, and pathways associated with reactive oxygen species production, oxidative phosphorylation, and TGFβ and interferon signaling similar to granulomas. This study revealed specific transcription patterns, immune responses and morphological alteration signaling in the early stage of HIV and Mtb infections.

BCG's role in strengthening immune responses: Implications for tuberculosis and comorbid diseases

The BCG vaccine represents a significant milestone in the prevention of tuberculosis (TB), particularly in children. Researchers have been developing recombinant BCG (rBCG) variants that can trigger lasting memory responses, thereby enhancing protection against TB in adults. The breakdown of immune surveillance is a key link between TB and other communicable and non-communicable diseases. Notably, TB is more prevalent among people with comorbidities such as HIV, diabetes, cancer, influenza, COVID-19, and autoimmune disorders. rBCG formulations have the potential to address both TB and HIV co-pandemics. TB increases the risk of lung cancer and immunosuppression caused by cancer can reactivate latent TB infections. Moreover, BCG's efficacy extends to bladder cancer treatment and blood glucose regulation in patients with diabetes and TB. Additionally, BCG provides cross-protection against unrelated pathogens, emphasizing the importance of BCG-induced trained immunity in COVID-19 and other respiratory diseases. Furthermore, BCG reduced the severity of pulmonary TB-induced influenza virus infections. Recent studies have proposed innovations in BCG delivery, revaccination, and attenuation techniques. Disease-centered research has highlighted the immunomodulatory effects of BCG on TB, HIV, cancer, diabetes, COVID-19, and autoimmune diseases. The complex relationship between TB and comorbidities requires a nuanced re-evaluation to understand the shared attributes regulated by BCG. This review assessed the interconnected relationships influenced by BCG administration in TB and related disorders, recommending the expanded use of rBCG in healthcare. Collaboration among vaccine research stakeholders is vital to enhance BCG's efficacy against global health challenges.

A Comprehensive Review of HIV-Associated Tuberculosis: Clinical Challenges and Advances in Management

Human immunodeficiency virus (HIV) and tuberculosis (TB) are two of the most pressing global health issues, each contributing significantly to morbidity and mortality worldwide. This review provides a comprehensive analysis of HIV-associated TB (HIV-TB), focusing on the clinical challenges and advancements in its management. HIV-positive individuals are at a heightened risk of developing active TB due to the immunosuppressive effects of the virus, which complicates both diagnosis and treatment. The interplay between these two diseases exacerbates health outcomes, presenting unique challenges related to drug interactions, adherence to treatment regimens, and management of adverse effects. This review explores the current diagnostic approaches, including advances in testing technologies and screening strategies, and examines treatment protocols, highlighting the integration of antiretroviral therapy with TB treatment. Special considerations for managing HIV-TB in various populations, such as children, pregnant women, and the elderly, are discussed. Additionally, the review addresses public health strategies for prevention and the impact of socio-economic and healthcare system factors on disease management. Finally, it highlights recent research innovations and future directions aimed at improving outcomes for individuals with HIV-TB. By synthesizing the latest evidence and clinical practices, this review aims to enhance understanding and guide effective management of this critical co-infection, ultimately contributing to reduced global burden and improved patient care.

T Cell Responses during Human Immunodeficiency Virus/Mycobacterium tuberculosis Coinfection

Coinfection with Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) is a significant public health concern. Individuals infected with Mtb who acquire HIV are approximately 16 times more likely to develop active tuberculosis. T cells play an important role as both targets for HIV infection and mediators of the immune response against both pathogens. This review aims to synthesize the current literature and provide insights into the effects of HIV/Mtb coinfection on T cell populations and their contributions to immunity. Evidence from multiple in vitro and in vivo studies demonstrates that T helper responses are severely compromised during coinfection, leading to impaired cytotoxic responses. Moreover, HIV's targeting of Mtb-specific cells, including those within granulomas, offers an explanation for the severe progression of the disease. Herein, we discuss the patterns of differentiation, exhaustion, and transcriptomic changes in T cells during coinfection, as well as the metabolic adaptations that are necessary for T cell maintenance and functionality. This review highlights the interconnectedness of the immune response and the pathogenesis of HIV/Mtb coinfection.

Cystatin F Depletion in Mycobacterium tuberculosis-Infected Macrophages Improves Cathepsin C/Granzyme B-Driven Cytotoxic Effects on HIV-Infected Cells during Coinfection

Cystatin F (CstF) is a protease inhibitor of cysteine cathepsins, including those involved in activating the perforin/granzyme cytotoxic pathways. It is targeted at the endolysosomal pathway but can also be secreted to the extracellular milieu or endocytosed by bystander cells. CstF was shown to be significantly increased in tuberculous pleurisy, and during HIV coinfection, pleural fluids display high viral loads. In human macrophages, our previous results revealed a strong upregulation of CstF in phagocytes activated by interferon γ or after infection with Mycobacterium tuberculosis (Mtb). CstF manipulation using RNA silencing led to increased proteolytic activity of lysosomal cathepsins, improving Mtb intracellular killing. In the present work, we investigate the impact of CstF depletion in macrophages during the coinfection of Mtb-infected phagocytes with lymphocytes infected with HIV. The results indicate that decreasing the CstF released by phagocytes increases the major pro-granzyme convertase cathepsin C of cytotoxic immune cells from peripheral blood-derived lymphocytes. Consequently, an observed augmentation of the granzyme B cytolytic activity leads to a significant reduction in viral replication in HIV-infected CD4+ T-lymphocytes. Ultimately, this knowledge can be crucial for developing new therapeutic approaches to control both pathogens based on manipulating CstF.

Clinical-epidemiological profile and factors associated with viral non-suppression in patients living with HIV/AIDS assisted at the Integrated Treatment Center at the Maputo Military Hospital (CITRA/MMH), 2019 to 2020

BACKGROUND

HIV remains a critical global public health challenge. In 2022, it was estimated that approximately 39.0 million people worldwide were living with HIV, and of these, around 29.8 million were receiving antiretroviral therapy (ART). The objective was to evaluate the clinical and epidemiological profile and factors associated with viral load (VL) non-suppression in people living with HIV/AIDS at the Maputo Military Hospital (CITRA/MMH).

METHODS

A retrospective cross-sectional analytical study was conducted on 9105 people aged 15 years and over. We use secondary data from participants on ART for at least 2 years being followed up between the years 2019-2020 at CITRA/MMH. Those recently enrolled (on ART < 1 year) were excluded and data analysis was performed using STATA version 16. Pearson's chi-square test and logistic regression were used for statistical modeling of viral non-suppression with a 95%/CI confidence interval and p < 0.05.

RESULTS

Among a total of 9105 HIV participants included, 52.8% (n = 4808) were female and 13.6% (n = 1235) were military personnel. The average age was 47.9 years (standard deviation ± 12.1), with the most prevalent age group being individuals aged between 25 and 59, totalizing 7,297 (80.2%) participants. Only 5395 (100%) participants had VL results. Among these, 23.1% (n = 1247) had a result VL non-suppressed. Single marital status (Adjusted Odds Ratio [AOR] = 4.8, 95%CI: 3.93-5.76, p < 0.001), with active tuberculosis (AOR = 4.6, 95%CI: 3.15-6.63, p < 0.001) and current ART regimen in categories TDF + 3TC + EFV (AOR = 12.7, 95%CI: 9.74-16.63, p < 0.001), AZT + 3TC + NVP (AOR = 21.8, 95% CI: 14.13-33.59, p < 0.001) and "other" regimens (AOR = 25.8, 95%CI: 18.58-35.80, p < 0.001), when compared to the TDF + 3TC + DTG regime, were statistically significant for viral non- suppression.

CONCLUSION

The study highlights the crucial role of ART adherence and ongoing monitoring to achieve viral suppression, particularly among adults aged 25 to 59. It underscores the need for transitioning eligible individuals to DTG-based regimens and addressing the implications of single marital status and comorbid conditions like active tuberculosis. The study emphasizes the importance of ARV adherence and continuous monitoring to meet the UNAIDS 95-95-95 targets and improve clinical outcomes for people living with HIV/AIDS.

Role of Type I Interferons during Mycobacterium tuberculosis and HIV Infections

Tuberculosis and AIDS remain two of the most relevant human infectious diseases. The pathogens that cause them, Mycobacterium tuberculosis (Mtb) and HIV, individually elicit an immune response that treads the line between beneficial and detrimental to the host. Co-infection further complexifies this response since the different cytokines acting on one infection might facilitate the dissemination of the other. In these responses, the role of type I interferons is often associated with antiviral mechanisms, while for bacteria such as Mtb, their importance and clinical relevance as a suitable target for manipulation are more controversial. In this article, we review the recent knowledge on how these interferons play distinct roles and sometimes have opposite consequences depending on the stage of the pathogenesis. We highlight the dichotomy between the acute and chronic infections displayed by both infections and how type I interferons contribute to an initial control of each infection individually, while their chronic induction, particularly during HIV infection, might facilitate Mtb primo-infection and progression to disease. We expect that further findings and their systematization will allow the definition of windows of opportunity for interferon manipulation according to the stage of infection, contributing to pathogen clearance and control of immunopathology.

Decreased IL-1 β Secretion as a Potential Predictor of Tuberculosis Recurrence in Individuals Diagnosed with HIV

Background: The mechanisms of the formation of immunological competence against tuberculosis (TB), and especially those associated with HIV co-infection, remain poorly understood. However, there is an urgent need for risk recurrence predictive biomarkers, as well as for predictors of successful treatment outcomes. The goal of the study was to identify possible immunological markers of TB recurrence in individuals with HIV/TB co-infection. Methods: The plasma levels of IFN-γ, TNF-α, IL-10, and IL-1β (cytokines which play important roles in the immune activation and protection against Mycobacterium tuberculosis) were measured using ELISA EIA-BEST kits. The cytokine concentrations were determined using a standard curve obtained with the standards provided by the manufacturer of each kit. Results: A total of 211 individuals were enrolled in the study as follows: 62 patients with HIV/TB co-infection, 52 with HIV monoinfection, 52 with TB monoinfection, and 45 healthy donors. Out of the 62 patients with HIV/TB, 75.8% (47) of patients were newly diagnosed with HIV and TB, and 24.2% (15) displayed recurrent TB and were newly diagnosed with HIV. Decreased levels of IFN-γ, TNF-α, and IL-10 were observed in patients with HIV/TB when compared with HIV and TB patients. However, there was no difference in IFN-γ, TNF-α, or IL-10 secretion between both HIV/TB groups. At the same time, an almost 4-fold decrease in Il-1β levels was detected in the HIV/TB group with TB recurrence when compared with the HIV/TB group (p = 0.0001); a 2.8-fold decrease when compared with HIV patients (p = 0.001); and a 2.2-fold decrease with newly diagnosed TB patients (p = 0.001). Conclusions: Significantly decreased Il-1β levels in HIV/TB patients' cohort with secondary TB indicate that this cytokine can be a potential biomarker of TB recurrence.

Protein Expression of TLR2, TLR4, and TLR9 on Monocytes in TB, HIV, and TB/HIV

Toll-like receptors (TLRs) have a critical role in recognizing pathogenic patterns and initiating immune responses against TB and HIV. Previously, studies described the gene expression of TLRs in patients with TB and HIV. Here, we demonstrated TLRs protein expressions and their association with clinical status and plasma markers in TB, HIV, and TB/HIV coinfection. The phenotyping of TLR2, TLR4, and TLR9 on CD14+ monocytes and their subsets were determined by multicolor flow cytometry. Host plasma biomarkers and microbial indices were measured using Luminex Multiplex assay and standard of care tools, respectively. TLR2 expression significantly enhanced in TB, slightly increased in HIV but slightly reduced in TB/HIV coinfection compared to apparently health controls (HC). On the other hand, TLR4 expression was significantly increased in TB, HIV, and TB/HIV compared to HC. Expression of TLR4 was equally enhanced on classical and intermediate monocytes while higher TLR2 expression on intermediate than classical monocytes. TLR4 had a positive correlation pattern with plasma biomarkers while TLR2 had an inverse correlation pattern. TLR4 is associated with disease severity while TLR2 is with the immune-competent status of patients. Our findings demonstrated that the pattern of TLR expression is disease as well as monocyte subset specific and distinct factors drive these differences.

The role of ESAT-6 in tuberculosis immunopathology

Despite major global efforts to eliminate tuberculosis, which is caused by Mycobacterium tuberculosis (Mtb), this disease remains as a major plague of humanity. Several factors associated with the host and Mtb interaction favor the infection establishment and/or determine disease progression. The Early Secreted Antigenic Target 6 kDa (ESAT-6) is one of the most important and well-studied mycobacterial virulence factors. This molecule has been described to play an important role in the development of tuberculosis-associated pathology by subverting crucial components of the host immune responses. This review highlights the main effector mechanisms by which ESAT-6 modulates the immune system, directly impacting cell fate and disease progression.

HIV-TB Coinfection: Current Therapeutic Approaches and Drug Interactions

The co-occurrence of human immunodeficiency virus (HIV) and tuberculosis (TB) infection poses a significant global health challenge. Treatment of HIV and TB co-infection often necessitates combination therapy involving antiretroviral therapy (ART) for HIV and anti-TB medications, which introduces the potential for drug-drug interactions (DDIs). These interactions can significantly impact treatment outcomes, the efficacy of treatment, safety, and overall patient well-being. This review aims to provide a comprehensive analysis of the DDIs between anti-HIV and anti-TB drugs as well as potential adverse effects resulting from the concomitant use of these medications. Furthermore, such findings may be used to develop personalized therapeutic strategies, dose adjustments, or alternative drug choices to minimize the risk of adverse outcomes and ensure the effective management of HIV and TB co-infection.

Host-directed therapy against mycobacterium tuberculosis infections with diabetes mellitus

Tuberculosis (TB) is caused by the bacterial pathogen Mycobacterium tuberculosis (MTB) and is one of the principal reasons for mortality and morbidity worldwide. Currently, recommended anti-tuberculosis drugs include isoniazid, rifampicin, ethambutol, and pyrazinamide. TB treatment is lengthy and inflicted with severe side-effects, including reduced patient compliance with treatment and promotion of drug-resistant strains. TB is also prone to other concomitant diseases such as diabetes and HIV. These drug-resistant and complex co-morbid characteristics increase the complexity of treating MTB. Host-directed therapy (HDT), which effectively eliminates MTB and minimizes inflammatory tissue damage, primarily by targeting the immune system, is currently an attractive complementary approach. The drugs used for HDT are repositioned drugs in actual clinical practice with relative safety and efficacy assurance. HDT is a potentially effective therapeutic intervention for the treatment of MTB and diabetic MTB, and can compensate for the shortcomings of current TB therapies, including the reduction of drug resistance and modulation of immune response. Here, we summarize the state-of-the-art roles and mechanisms of HDT in immune modulation and treatment of MTB, with a special focus on the role of HDT in diabetic MTB, to emphasize the potential of HDT in controlling MTB infection.

Recurrent Spinal Tuberculosis with HIV Infection After Surgery: A Rare Case of Recurrence and Drug Resistance

Tuberculosis (TB) and acquired immunodeficiency syndrome (AIDS) are prevalent infectious diseases that continue to pose a significant global health burden. The co-infection of mycobacterium tuberculosis and human immunodeficiency virus (HIV) represents a substantial public health challenge, particularly in developing nations. In this study, we present an exceptional case of spinal tuberculosis complicated by HIV infection, which exhibited relapse post-surgery necessitating reoperation, along with the emergence of drug resistance. The first operation was lumbar lesion removal, decompression, internal fixation, and bone graft fusion assisted by lumbar discioscopy. The second operation was ultrasound-guided puncture and drainage of right psoas major abscess. The management of patients with HIV/TB co-infection demands specific considerations regarding medication regimens, surgical interventions, and nursing care. However, limited experience exists in treating such individuals, thus further research is imperative to enhance our understanding of HIV/TB co-infection.

Human immunodeficiency virus transmission-Mechanisms underlying the cell-to-cell spread of human immunodeficiency virus

Despite the success of combined antiretroviral therapy in controlling viral load and reducing the risk of human immunodeficiency virus (HIV) transmission, an estimated 1.5 million new infections occurred worldwide in 2021. These new infections are mainly the result of sexual intercourse and thus involve cells present on the genital mucosa, such as dendritic cells (DCs), macrophages (Mø) and CD4+ T lymphocytes. Understanding the mechanisms by which HIV interacts with these cells and how HIV exploits these interactions to establish infection in a new human host is critical to the development of strategies to prevent and control HIV transmission. In this review, we explore how HIV has evolved to manipulate some of the physiological roles of these cells, thereby gaining access to strategic cellular niches that are critical for the spread and pathogenesis of HIV infection. The interaction of HIV with DCs, Mø and CD4+ T lymphocytes, and the role of the intercellular transfer of viral particles through the establishment of the infectious or virological synapses, but also through membrane protrusions such as filopodia and tunnelling nanotubes (TNTs), and cell fusion or cell engulfment processes are presented and discussed.

Viral Load and CD4+ Markers as Determinants of Tuberculosis Coinfection Among People Living with HIV/AIDS in Papua Indonesia

Tuberculosis (TB) infection causes mortality among People Living with HIV (PLHIV), so the treatment of TB-HIV coinfection is crucial. The study aimed to identify the determinants contributing to TB coinfection among PLHIV in Papua. It is a descriptive-analytic study with a cross-sectional design involving 188 PLHIV at the four hospitals in Papua. CD4+ was carried out using CD4+ counter and viral load using the qPCR technique. A logistic regression test and R statistic with a significance level of 0.05 were used to analyze the determinants of TB coinfection among PLHIV. PLHIV having CD4+ count of fewer than 350 cells/mm3 had a 17.8 times higher risk for TB-HIV coinfection, P-value = 0.0. In addition, a viral load of more than 10 000 copies/ml will be 12.1 times more likely to be co-infected with TB-HIV compared to those who have a viral load of fewer than 10 000 copies/ml, P-value = 0.0. CD4+ markers and viral load are factors that play a role in TB coinfection among PLHIV in Papua Province.

Modulation of Cystatin F in Human Macrophages Impacts Cathepsin-Driven Killing of Multidrug-Resistant Mycobacterium tuberculosis

Tuberculosis (TB) treatment relies primarily on 70-year-old drugs, and prophylaxis suffers from the lack of an effective vaccine. Among the 10 million people exhibiting disease symptoms yearly, 450,000 have multidrug or extensively drug-resistant (MDR or XDR) TB. A greater understanding of host and pathogen interactions will lead to new therapeutic interventions for TB eradication. One of the strategies will be to target the host for better immune bactericidal responses against the TB causative agent Mycobacterium tuberculosis (Mtb). Cathepsins are promising targets due to their manipulation of Mtb with consequences such as decreased proteolytic activity and improved pathogen survival in macrophages. We recently demonstrated that we could overcome this enzymatic blockade by manipulating protease inhibitors such as cystatins. Here, we investigate the role of cystatin F, an inhibitor that we showed previously to be strongly upregulated during Mtb infection. Our results indicate that the silencing of cystatin F using siRNA increase the proteolytic activity of cathepsins S, L, and B, significantly impacting pathogen intracellular killing in macrophages. Taken together, these indicate the targeting of cystatin F as a potential adjuvant therapy for TB, including MDR and XDR-TB.

ESAT-6 a Major Virulence Factor of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis (TB), is one of the most successfully adapted human pathogens. Human-to-human transmission occurs at high rates through aerosols containing bacteria, but the pathogen evolved prior to the establishment of crowded populations. Mtb has developed a particular strategy to ensure persistence in the host until an opportunity for transmission arises. It has refined its lifestyle to obviate the need for virulence factors such as capsules, flagella, pili, or toxins to circumvent mucosal barriers. Instead, the pathogen uses host macrophages, where it establishes intracellular niches for its migration into the lung parenchyma and other tissues and for the induction of long-lived latency in granulomas. Finally, at the end of the infection cycle, Mtb induces necrotic cell death in macrophages to escape to the extracellular milieu and instructs a strong inflammatory response that is required for the progression from latency to disease and transmission. Common to all these events is ESAT-6, one of the major virulence factors secreted by the pathogen. This narrative review highlights the recent advances in understanding the role of ESAT-6 in hijacking macrophage function to establish successful infection and transmission and its use as a target for the development of diagnostic tools and vaccines.

Development of Chitosan Particles Loaded with siRNA for Cystatin C to Control Intracellular Drug-Resistant Mycobacterium tuberculosis

The golden age of antibiotics for tuberculosis (TB) is marked by its success in the 1950s of the last century. However, TB is not under control, and the rise in antibiotic resistance worldwide is a major threat to global health care. Understanding the complex interactions between TB bacilli and their host can inform the rational design of better TB therapeutics, including vaccines, new antibiotics, and host-directed therapies. We recently demonstrated that the modulation of cystatin C in human macrophages via RNA silencing improved the anti-mycobacterial immune responses to Mycobacterium tuberculosis infection. Available in vitro transfection methods are not suitable for the clinical translation of host-cell RNA silencing. To overcome this limitation, we developed different RNA delivery systems (DSs) that target human macrophages. Human peripheral blood-derived macrophages and THP1 cells are difficult to transfect using available methods. In this work, a new potential nanomedicine based on chitosan (CS-DS) was efficiently developed to carry a siRNA-targeting cystatin C to the infected macrophage models. Consequently, an effective impact on the intracellular survival/replication of TB bacilli, including drug-resistant clinical strains, was observed. Altogether, these results suggest the potential use of CS-DS in adjunctive therapy for TB in combination or not with antibiotics.