HIV-1 and the Mycobacterium tuberculosis granuloma: A systematic review and meta-analysis

Comparing gene expression profiles of adults with isolated spinal tuberculosis to disseminated spinal tuberculosis identified by 18FDG-PET/CT at time of diagnosis, 6- and 12-months follow-up: classifying clinical stages of spinal tuberculosis and monitoring treatment response (Spinal TB X cohort study)

BACKGROUND

Tuberculosis (TB) is one of the top ten causes of death worldwide, with approximately 10 million cases annually. Focus has been on pulmonary TB, while extrapulmonary TB (EPTB) has received little attention. Diagnosis of EPTB remains challenging due to the invasive procedures required for sample collection. Spinal TB (STB) accounts for 10% of EPTB and often leads to lifelong debilitating disease due to devastating spinal deformation and compression of neural structures. Little is known about the extent of disease, although both isolated STB and a disseminated form of STB have been described. In our Spinal TB X cohort study, we aim to describe the clinical phenotype of STB using whole-body 18FDG-PET/CT, identify a specific gene expression profile for different stages of dissemination and compare findings to previously described gene expression signatures for latent and active pulmonary TB.

METHODS

A single-centre, prospective cohort study will be established to describe the distributional pattern of STB detected by whole-body 18FDG-PET/CT and gene expression profile of patients with suspected STB on magnetic resonance imaging (MRI) at point of diagnosis, six months, and 12 months. Blood biobanking will be performed at these time points. Specimens for microbiology will be obtained from sputum/urine, from easily accessible sites of disease (e.g., lymph nodes, abscess) identified in the first 18FDG-PET/CT, from CT-guided biopsy and/or surgery. Clinical parameters and functional scores will be collected at every physical visit. Data will be entered into RedCap® database; data cleaning, validation and analysis will be performed by the study team. The University of Cape Town Ethics Committee approved the protocol (243/2022).

DISCUSSION

The Spinal TB X cohort study is the first prospective cohort study using whole-body 18FDG-PET/CT scans in patients with microbiologically confirmed spinal tuberculosis. Dual imaging techniques of the spine using 18FDG-PET/CT and magnetic resonance imaging as well as tissue diagnosis (microbiology and histopathology) will allow us to develop a virtual biopsy model. If successful, a distinct gene-expression profile will aid in blood-based diagnosis (point of care testing) as well as treatment monitoring and would lead to earlier diagnosis of this devastating disease.

TRIAL REGISTRATION

The study has been registered on ClinicalTrials.gov (NCT05610098).

Multi-level tuberculosis of the spine identified by 18 F-FDG-PET/CT and concomitant urogenital tuberculosis: a case report from the spinal TB X cohort

BACKGROUND

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb) and typically infects the lungs. However, extrapulmonary forms of TB can be found in approximately 20% of cases. It is suggested, that up to 10% of extrapulmonary TB affects the musculoskeletal system, in which spinal elements (spinal tuberculosis, STB) are involved in approximately 50% of the cases. STB is a debilitating disease with nonspecific symptoms and diagnosis is often delayed for months to years. In our Spinal TB X Cohort, we aim to describe the clinical phenotype of STB using whole-body 18 F-fluorodeoxyglucose positron emission tomography computed tomography (PET/CT) and to identify a specific gene expression profile for the different stages of dissemination on PET/CT. Here we report on the first patient recruited into our cohort who underwent PET/CT before treatment initiation, at 6-months and at 12-months - time of TB treatment completion.

CASE PRESENTATION

A 27-year-old immunocompetent male presented with severe thoracolumbar back pain for 9 months with severe antalgic gait and night sweats. Magnetic resonance imaging (MRI) of the whole spine revealed multilevel spinal disease (T5/6, T11/12, L3/4) in keeping with STB. After informed consent and recruitment into the Spinal TB X Cohort, the patient underwent PET/CT as per protocol, which revealed isolated multilevel STB (T4-7, T11/12, L3/4) with no concomitant lung or urogenital lesion. However, sputum and urine were Xpert MTB/RIF Ultra positive and Mtb was cultured from the urine sample. CT-guided biopsy of the T11/12 lesion confirmed drug-sensitive Mtb on Xpert MTB/RIF Ultra and the patient was started on TB treatment according to local guidelines for 12 months. The 6-month follow-up PET/CT revealed new and existing spinal lesions with increased FDG-uptake despite significant improvement of clinical features and laboratory markers. After 9 months of treatment, the patient developed an acute urethral stricture, most likely due to urogenital TB, and a suprapubic catheter was inserted. The 12-month PET/CT showed significantly decreased PET/CT values of all lesions, however, significant persistent spinal inflammation was present at the end of TB treatment. Clinically, the patient was considered cured by the TB control program and currently awaits urethroplasty.

CONCLUSIONS

In our case, PET/CT emerged as a valuable imaging modality for the initial assessment, surpassing MRI by revealing more comprehensive extensive disease. Subsequent PET/CT scans at 6-month uncovered new lesions and increased inflammation in existing ones, while by the end of TB treatment, all lesions exhibited improvement. However, the interpretation of FDG avidity remains ambiguous, whether it correlates with active infection and viable Mtb. or fibro- and osteoblast activity indicative of the healing process. Additionally, the absence of extraspinal TB lesions on PET/CT despite positive microbiology from sputum and urine maybe explained by paucibacillary, subclinical infection of extraspinal organs. The Spinal TB X Cohort endeavours to shed light on whole-body imaging patterns at diagnosis, their evolution midway through TB treatment, and upon treatment completion. Ultimately, this study aims to advance our understanding of the biology of this complex disease.

A TNF-IL-1 circuit controls Yersinia within intestinal pyogranulomas

Tumor necrosis factor (TNF) is a pleiotropic inflammatory cytokine that mediates antimicrobial defense and granuloma formation in response to infection by numerous pathogens. We previously reported that Yersinia pseudotuberculosis colonizes the intestinal mucosa and induces the recruitment of neutrophils and inflammatory monocytes into organized immune structures termed pyogranulomas (PG) that control Yersinia infection. Inflammatory monocytes are essential for the control and clearance of Yersinia within intestinal PG, but how monocytes mediate Yersinia restriction is poorly understood. Here, we demonstrate that TNF signaling in monocytes is required for bacterial containment following enteric Yersinia infection. We further show that monocyte-intrinsic TNFR1 signaling drives the production of monocyte-derived interleukin-1 (IL-1), which signals through IL-1 receptors on non-hematopoietic cells to enable PG-mediated control of intestinal Yersinia infection. Altogether, our work reveals a monocyte-intrinsic TNF-IL-1 collaborative inflammatory circuit that restricts intestinal Yersinia infection.

Mitochondrial Metabolism in Alveolar Macrophages of Patients Infected with HIV, Tuberculosis, and HIV/Tuberculosis

Tuberculosis (TB) is one of the most common opportunistic infections and is a leading cause of mortality in patients with HIV and AIDS. HIV infection causes serious defects in the host immune system and increases the risk of active TB. TB infection promotes HIV replication and aggravates host damage in patients with HIV/AIDS. Alveolar macrophages (AMs) are essential immune cells during TB and HIV infections. AMs undergo a shift in mitochondrial metabolism during TB or HIV infection, that is, metabolic reprogramming, allowing them to act in the form of classical activated macrophages (M1) and alternative activated macrophages (M2) at different stages of infection. We reviewed the alterations in the mitochondrial energy metabolism of AMs in patients with HIV, TB, and HIV/TB to provide ideas for further research on the role of metabolic reprogramming by AMs in the pathogeneses of HIV, TB, and HIV/TB coinfection.

Uncovering the Bronchoalveolar Single-Cell Landscape of Patients With Pulmonary Tuberculosis With Human Immunodeficiency Virus Type 1 Coinfection

BACKGROUND

Coinfection of human immunodeficiency virus type 1 (HIV-1) is the most significant risk factor for tuberculosis (TB). The immune responses of the lung are essential to restrict the growth of Mycobacterium tuberculosis and avoid the emergence of the disease. Nevertheless, there is still limited knowledge about the local immune response in people with HIV-1-TB coinfection.

METHODS

We employed single-cell RNA sequencing (scRNA-seq) on bronchoalveolar lavage fluid from 9 individuals with HIV-1-TB coinfection and 10 with pulmonary TB.

RESULTS

A total of 19 058 cells were grouped into 4 major cell types: myeloid cells, T/natural killer (NK) cells, B cells, and epithelial cells. The myeloid cells and T/NK cells were further divided into 10 and 11 subsets, respectively. The proportions of dendritic cell subsets, CD4+ T cells, and NK cells were lower in the HIV-1-TB coinfection group compared to the TB group, while the frequency of CD8+ T cells was higher. Additionally, we identified numerous differentially expressed genes between the CD4+ and CD8+ T-cell subsets between the 2 groups.

CONCLUSIONS

HIV-1 infection not only affects the abundance of immune cells in the lungs but also alters their functions in patients with pulmonary TB.

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.

Antibody response to mycobacterial Rpf B protein and its immunodominant peptides in HIV-TB co-infected individuals

Diagnosis of TB at early stages of HIV infection may lead to timely intervention for improving patient outcome. Antibodies to Mycobacterium tuberculosis recombinant RpfB protein and two immunodominant peptides of Rpf B protein were evaluated in the sera of HIV +TB+, HIV+ and HIV- pulmonary TB patients by ELISA. Serum antibodies from 90 % and 65 % of HIV+TB+ patients reacted to recombinant RpfB protein and synthetic peptide RpfP1 respectively. Overall, this study shows that resuscitation promoting factor B elicits humoral antibody response in HIV+TB+ co-infected individuals and be proposed as a potential biomarker for diagnosis of HIV+TB+ patients, however further longitudinal follow up studies are warranted.

Cutaneous tuberculosis. Part I: Pathogenesis, classification, and clinical features

Tuberculosis is an ancient disease that continues to affect an estimated 10 million people per year and is responsible for 1.4 million deaths per year. Additionally, the HIV epidemic and multidrug resistance present challenges to disease control. Cutaneous tuberculosis is an uncommon, often indolent, manifestation of mycobacterial infection that has a varied presentation. Its diagnosis is challenging, as lesions mimic other, more common conditions and microbiological confirmation is often not possible. Cutaneous tuberculosis can be broadly categorized into multibacillary and paucibacillary forms. Approximately one-third of skin tuberculosis is associated with systemic involvement. By recognizing cutaneous tuberculosis early, dermatologists can play an important role in disease control. The first article in this 2-part continuing medical education series describes the latest epidemiology, microbiology, and pathogenesis of tuberculosis. Furthermore, we review the classification, clinical manifestations, common clinical differentials, and systemic involvement that occur in cutaneous tuberculosis.

Prevalence and risk factors of tuberculosis among people living with HIV/AIDS in China: a systematic review and meta-analysis

OBJECTIVE

To estimate the prevalence and risk factors associated with tuberculosis (TB) among people living with human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) in China.

METHODS

A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. After the literature was screened based on the inclusion and exclusion criteria, STATA® version 17.0 software was used for the meta-analysis. The heterogeneity among study data was assessed using I2 statistics. Subgroup analysis and meta-regressions were performed to further explore the source of heterogeneity.

RESULTS

A total of 5241 studies were retrieved. Of these, 44 studies were found to be eligible. The pooled prevalence of HIV/TB co-infection was 6.0%. The risk factors for HIV/TB co-infection included a low CD4+ T cell count, smoking, intravenous drug use and several other sociodemographic and clinical factors. Bacillus Calmette-Guérin (BCG) vaccination history was a protective factor.

CONCLUSION

A high prevalence of TB was observed among people living with HIV/AIDS in China. Low CD4+ T cell count, smoking, and intravenous drug use were the primary risk factors for HIV/TB co-infection, whereas BCG vaccination history was a protective factor. Checking for TB should be prioritized in HIV screening and healthcare access.

SYSTEMATIC REVIEW REGISTRATION

Registered on PROSPERO, Identifier: CRD42022297754.

A high proportion of caseous necrosis, abscess, and granulation tissue formation in spinal tuberculosis

The special blood circulation, anatomy, and tissue structure of the spine may lead to significant differences in pathological features and drug resistance between spinal tuberculosis and pulmonary tuberculosis. Here, we collected 168 spinal tuberculosis cases and 207 pulmonary tuberculosis cases, and compared their clinical and pathological features as well as drug resistance. From the anatomical location, the highest incidence was of lumbar tuberculosis, followed by thoracic tuberculosis. PET-CT scans showed increased FDG uptake in the diseased vertebrae, discernible peripheral soft tissue shadow, visible internal capsular shadow, and an abnormal increase in FDG uptake. MRI showed infectious lesions in the diseased vertebral body, formation of paravertebral and bilateral psoas muscle abscess, and edema of surrounding soft tissues. As with control tuberculosis, the typical pathological features of spinal tuberculosis were chronic granulomatous inflammation with caseous necrosis. The incidence of granulomas was not statistically different between the groups. However, the proportions of caseous necrosis, acute inflammation, abscess, exudation, and granulation tissue formation in the spinal tuberculosis group were all significantly increased relative to the control tuberculosis group. Compared to the control tuberculosis group, the incidences of resistance to rifampicin (RFP) + isoniazid (INH) + streptomycin (STR) and INH + ethambutol (EMB) were lower in the spinal tuberculosis group, while the incidences of resistance to RFP + INH + EMB and RFP + EMB were higher. Moreover, we also found some differences in drug-resistance gene mutations. In conclusion, there are noticeable differences between spinal Mycobacterium tuberculosis and pulmonary tuberculosis in pathological characteristics, drug resistance, and drug resistance gene mutations.

Mycobacterium tuberculosis disease associates with higher HIV-1-specific antibody responses

Mycobacterium tuberculosis (Mtb) is the most common infection among people with HIV (PWH). Mtb disease-associated inflammation could affect HIV-directed immune responses in PWH. We show that HIV antibodies are broader and more potent in PWH in the presence as compared to the absence of Mtb disease. With co-existing Mtb disease, the virus in PWH also encounters unique antibody selection pressure. The Mtb-linked HIV antibody enhancement associates with specific mediators important for B cell and antibody development. This Mtb humoral augmentation does not occur due to cross-reactivity, a generalized increase in all antibodies, or differences in duration or amount of antigen exposure. We speculate that the co-localization of Mtb and HIV in lymphatic tissues leads to the emergence of potent HIV antibodies. PWH's Mtb disease status has implications for the future use of HIV broadly neutralizing antibodies as prophylaxis or treatment and the induction of better humoral immunity.

Host Immunity to Mycobacterium tuberculosis Infection Is Similar in Simian Immunodeficiency Virus (SIV)-Infected, Antiretroviral Therapy-Treated and SIV-Naïve Juvenile Macaques

Pre-existing HIV infection increases tuberculosis (TB) risk in children. Antiretroviral therapy (ART) reduces, but does not abolish, this risk in children with HIV. The immunologic mechanisms involved in TB progression in both HIV-naive and HIV-infected children have not been explored. Much of our current understanding is based on human studies in adults and adult animal models. In this study, we sought to model childhood HIV/Mycobacterium tuberculosis (Mtb) coinfection in the setting of ART and characterize T cells during TB progression. Macaques equivalent to 4 to 8 year-old children were intravenously infected with SIVmac239M, treated with ART 3 months later, and coinfected with Mtb 3 months after initiating ART. SIV-naive macaques were similarly infected with Mtb alone. TB pathology and total Mtb burden did not differ between SIV-infected, ART-treated and SIV-naive macaques, although lung Mtb burden was lower in SIV-infected, ART-treated macaques. No major differences in frequencies of CD4+ and CD8+ T cells and unconventional T cell subsets (Vγ9+ γδ T cells, MAIT cells, and NKT cells) in airways were observed between SIV-infected, ART-treated and SIV-naive macaques over the course of Mtb infection, with the exception of CCR5+ CD4+ and CD8+ T cells which were slightly lower. CD4+ and CD8+ T cell frequencies did not differ in the lung granulomas. Immune checkpoint marker levels were similar, although ki-67 levels in CD8+ T cells were elevated. Thus, ART treatment of juvenile macaques, 3 months after SIV infection, resulted in similar progression of Mtb and T cell responses compared to Mtb in SIV-naive macaques.

Healthcare workers' knowledge and practice of the South African national tuberculosis management guidelines

BACKGROUND

Tuberculosis (TB) remains a global public health concern. The 2014 South African (SA) national TB management guidelines were developed to decrease the burden of TB, but implementation remains a challenge.

OBJECTIVES

 To estimate healthcare workers' level of knowledge about the national TB management guidelines and to assess the implementation of these guidelines.

METHODS

A cross-sectional descriptive study was conducted in four randomly selected health facilities in Dr Kenneth Kaunda district, North West Province, SA. We administered a TB knowledge questionnaire and reviewed TB registers and 204 patient files.

RESULTS

 A total of 38 participants completed the TB knowledge questionnaire. The majority were professional nurses (89%). The participants' mean (standard deviation) age was 46 (8) years, and the median (interquartile range) career length was 10 (8 - 17) years. Inadequate knowledge of the national TB management guidelines was revealed in 12 participants (32%). The review of the TB register showed that 163 153 patients were screened for TB. Of these, 9 308 (6%) had presumptive TB, 8 116 (87%) had an Xpert test and 1 292 (16%) had positive Xpert results. Overall, 1 150 (12%) of the patients with presumptive TB were diagnosed with drug-sensitive TB and started treatment based on laboratory results and a clinical diagnosis. Of this sample, 999 patients (87%) were treated successfully. The patient file review showed that a total of 197 patients (97%) received the correct treatment dose according to body weight and treatment phase. Smear microscopy was consistently done throughout the intensive and continuation phases of TB treatment. Body weight was monitored in 199 patients (98%). Contact investigation was conducted for 133 patients (65%), and there was evidence that child contacts aged <5 years were started on isoniazid preventive therapy. Only 110 patients (54%) had documented HIV status. Of these, 66 (60%) were HIV positive, and 39 (59%) of them received antiretroviral therapy. Body mass index was monitored in 55 patients (27%). Eighty (39%) of the patients with TB were women of childbearing potential, and only 8 (10%) of them had their pregnancy test results recorded. Treatment side-effects were reported in 17 patient files (8%); 13 (76%) were managed and 8 (62%) had resolved side-effects.

CONCLUSION

Most participants had adequate knowledge of the national TB management guidelines. A high TB treatment success rate was noted, along with some good practices. The study also highlights several knowledge and practice gaps that can be overcome by measures such as quality audits to improve record keeping. Adequate training of healthcare workers, sustaining and updating knowledge through continuous training, and strengthened supervision mechanisms to ensure compliance with the guidelines are recommended.

The value of bone marrow examinations performed in the investigation of HIV infected patients with cytopenias

INTRODUCTION

Bone marrow examination (BME) is a reliable and effective tool in the diagnosis of many haematological and non-haematological diseases and may be used to investigate unexplained cytopenia in human immunodeficiency virus (HIV) infected patients. The objective of this study was to determine the diagnoses made, diagnostic yield and unique diagnostic yield of BMEs performed to investigate cytopenias in HIV infected patients.

METHOD

A retrospective cross-sectional descriptive study was performed involving all BMEs performed on HIV-infected adult patients with the main indication of unexplained cytopenia over a period of 5 years and 4 months. Data was extracted from the National Health Laboratory Service's laboratory information system and clinicians' BME request forms.

RESULTS

The study included 128 BMEs, performed on 124 patients. The diagnostic yield was 32% and the unique diagnostic yield was 30.5%. The most common diagnosis was pure red cell aplasia (10.9%), followed by immune thrombocytopenic purpura (ITP) (7%), iron deficiency anaemia (6.3%), malignancy (4.7%) and disseminated infection (3.9%).

CONCLUSION

BME is a useful investigation for unexplained cytopenia in HIV-infected patients. Less invasive investigations to exclude haematinic deficiencies, haemolysis and sepsis are recommended on an individualised basis prior to BME. In HIV-infected patients with therapy refractory ITP or ITP with atypical clinicopathological findings, BME is strongly recommended. As Mycobacterial and other infections are common in this group of patients, staining and culture of specimens are advised if BME is undertaken.

A TNF-IL-1 circuit controls Yersinia within intestinal granulomas

Tumor necrosis factor (TNF) is a pleiotropic inflammatory cytokine that mediates antimicrobial defense and granuloma formation in response to infection by numerous pathogens. Yersinia pseudotuberculosis colonizes the intestinal mucosa and induces recruitment of neutrophils and inflammatory monocytes into organized immune structures termed pyogranulomas that control the bacterial infection. Inflammatory monocytes are essential for control and clearance of Yersinia within intestinal pyogranulomas, but how monocytes mediate Yersinia restriction is poorly understood. Here, we demonstrate that TNF signaling in monocytes is required for bacterial containment following enteric Yersinia infection. We further show that monocyte-intrinsic TNFR1 signaling drives production of monocyte-derived interleukin-1 (IL-1), which signals through IL-1 receptor on non-hematopoietic cells to enable pyogranuloma-mediated control of Yersinia infection. Altogether, our work reveals a monocyte-intrinsic TNF-IL-1 collaborative circuit as a crucial driver of intestinal granuloma function, and defines the cellular target of TNF signaling that restricts intestinal Yersinia infection.

Mycobacterium bovis naturally infected calves present a higher bacterial load and proinflammatory response than adult cattle

Granulomas are characteristic bovine tuberculosis lesions; studying this structure has improved our understanding of tuberculosis pathogenesis. However, the immune response that develops in granulomas of young cattle naturally infected with Mycobacterium bovis (M. bovis) has not been fully studied. Our previous work described an atypical pattern in granulomatous lesions of cattle younger than 4 months (calves) naturally infected previously M. bovis that did not correspond to the histological classification previously proposed. Histologically, granulomas from calves lack a connective tissue capsule and have fewer multinucleated giant cells (MGCs) and more acid-fast bacilli (AFB) than the classic tuberculosis lesions found in cattle older than 1 year (adults); this suggests a deficient immune response against M. bovis infection in young animals. Therefore, we used IHC and digital pathology analysis to characterize the in situ immune response of granulomas from young and adult cattle. The immunolabeling quantification showed that granulomas from calves had more mycobacteria, CD3⁺ cells, IFN-γ, TNF-α, and inducible nitric oxide synthase (iNOS) than those of adult cattle. Furthermore, calf granulomas showed lower immunolabeling of MAC387⁺, CD79⁺, and WC1⁺ cells without connective tissue surrounding the lesion and were associated with less vimentin, Alpha Smooth Muscle Actin (α-SMA), and TGF-β compared with granulomas from adult cattle. Our results suggest that the immune responses in granulomas of cattle naturally infected with M. bovis may be age dependent. This implies that an exacerbated proinflammatory response may be associated with active tuberculosis, producing more necrosis and a lower microbicidal capacity in the granulomas of calves naturally infected with M. bovis.

Systems biology approaches to investigate the role of granulomas in TB-HIV coinfection

The risk of active tuberculosis disease is 15-21 times higher in those coinfected with human immunodeficiency virus-1 (HIV) compared to tuberculosis alone, and tuberculosis is the leading cause of death in HIV+ individuals. Mechanisms driving synergy between Mycobacterium tuberculosis (Mtb) and HIV during coinfection include: disruption of cytokine balances, impairment of innate and adaptive immune cell functionality, and Mtb-induced increase in HIV viral loads. Tuberculosis granulomas are the interface of host-pathogen interactions. Thus, granuloma-based research elucidating the role and relative impact of coinfection mechanisms within Mtb granulomas could inform cohesive treatments that target both pathogens simultaneously. We review known interactions between Mtb and HIV, and discuss how the structure, function and development of the granuloma microenvironment create a positive feedback loop favoring pathogen expansion and interaction. We also identify key outstanding questions and highlight how coupling computational modeling with in vitro and in vivo efforts could accelerate Mtb-HIV coinfection discoveries.

Contributions of GeneXpert® to TB diagnosis in Myanmar

BACKGROUND: Xpert^® MTB/RIF, a rapid, molecular TB diagnostic assay, can detect Mycobacterium tuberculosis and rifampin resistance directly from clinical sputum samples in <2 h with high sensitivity and specificity. The added diagnostic value of Xpert over smear microscopy at a national level in Myanmar has not been previously reported.METHODS: We evaluated 339,358 Xpert and demographic records captured from January 2015 to December 2018 as part of the Myanmar National TB Program Data Utilization and Connectivity Project to examine the additional diagnostic yield of Xpert relative to smear for the detection of M. tuberculosis for TB diagnosis in Myanmar, with a focus on people living with HIV (PLHIV) and sample type.RESULTS: Use of Xpert increased TB case detection by 40% compared to smear microscopy results. Among PLHIV, use of Xpert increased TB case detection by almost 100% compared to smear microscopy results.CONCLUSION: Xpert testing identified more patients with TB than smear microscopy alone, particularly in cohorts with significant proportions of PLHIV. The use of Xpert as a screening tool in countries with a high burden of TB could lead to significantly increased diagnosis of TB at a regional and national level.

Spontaneous Control of SIV Replication Does Not Prevent T Cell Dysregulation and Bacterial Dissemination in Animals Co-Infected with M. tuberculosis

Individuals co-infected with HIV and Mycobacterium tuberculosis (Mtb) are more likely to develop severe tuberculosis (TB) disease than HIV-naive individuals. To understand how a chronic pre-existing Simian immunodeficiency virus (SIV) infection impairs the early immune response to Mtb, we used the Mauritian cynomolgus macaque (MCM) model of SIV/Mtb co-infection. We examined the relationship between peripheral viral control and Mtb burden, Mtb dissemination, and T cell function between SIV+ spontaneous controllers, SIV+ non-controllers, and SIV-naive MCM who were challenged with a barcoded Mtb Erdman strain 6 months post-SIV infection and necropsied 6 weeks post-Mtb infection. Mycobacterial burden was highest in the SIV+ non-controllers in all assessed tissues. In lung granulomas, the frequency of TNF-α-producing CD4+ T cells was reduced in all SIV+ MCM, but IFNγ-producing CD4+ T cells were only lower in the SIV+ non-controllers. Further, while all SIV+ MCM had more PD1+ and TIGIT+ T cells in the lung granulomas relative to SIV-naive MCM, SIV+ controllers exhibited the highest frequency of cells expressing these markers. To measure the effect of SIV infection on within-host bacterial dissemination, we sequenced the molecular barcodes of Mtb present in each tissue and characterized the Mtb population complexity. While Mtb population complexity was not associated with SIV infection group, lymph nodes had increased complexity when compared with lung granulomas across all groups. These results provide evidence that SIV+ animals, independent of viral control, exhibit a dysregulated T cell immune response and enhanced dissemination of Mtb, likely contributing to the poor TB disease course across all SIV/Mtb co-infected animals. IMPORTANCE HIV and TB remain significant global health issues, despite the availability of treatments. Individuals with HIV, including those who are virally suppressed, are at an increased risk to develop and succumb to severe TB disease when compared with HIV-naive individuals. Our study aims to understand the relationship between the extent of SIV replication, mycobacterial growth, and T cell function in the tissues of co-infected Mauritian cynomolgus macaques during the first 6 weeks of Mtb infection. Here we demonstrate that increased viral replication is associated with increased bacterial burden in the tissues and impaired T cell responses, and that the immunological damage attributed to virus infection is not fully eliminated when animals spontaneously control virus replication.

In the Thick of It: Formation of the Tuberculous Granuloma and Its Effects on Host and Therapeutic Responses

The defining pathology of tuberculosis is the granuloma, an organized structure derived from host immune cells that surrounds infecting Mycobacterium tuberculosis. As the location of much of the bacteria in the infected host, the granuloma is a central point of interaction between the host and the infecting bacterium. This review describes the signals and cellular reprogramming that drive granuloma formation. Further, as a central point of host-bacterial interactions, the granuloma shapes disease outcome by altering host immune responses and bacterial susceptibility to antibiotic treatment, as discussed herein. This new understanding of granuloma biology and the signaling behind it highlights the potential for host-directed therapies targeting the granuloma to enhance antibiotic access and tuberculosis-specific immune responses.

Indications and diagnostic value of bone marrow examination in HIV-positive individuals: A 3-year review at Tygerberg Hospital

Background

Bone marrow examination is a useful diagnostic tool in human immunodeficiency virus (HIV)-positive patients presenting with cytopenias and fever. However, its role in the afebrile and asymptomatic patient presenting with an isolated cytopenia is not well established. This study was conducted to determine the indications for bone marrow examination and its diagnostic yield, in HIV-positive patients at Tygerberg Hospital.

Methods

A retrospective, cross-sectional descriptive study was performed over a 3-year period from 01 September 2015 to 31 August 2018. The bone marrow examination reports for the HIV-positive patients who had a bone marrow examination during the study period were retrieved. Clinical and laboratory information was captured.

Results

Altogether 374 bone marrow reports for HIV-positive patients were found. The indication of the bone marrow examination included investigation of unexplained cytopenias, suspected haematological malignancies, follow-up examination for patients with known haematological diseases, staging of haematological or non-haematological malignancies and investigation of suspected disseminated infection. The patients' median age was 43 years and the interquartile range was 27-60 years. There was a slight female predominance with females 51% and males 49%. The diagnostic yield was 33.7%. Acute leukaemia and lymphoma were the most common diagnoses. Haematinic deficiency and pure red cell aplasia were found in the majority of cases with isolated anaemia. All cases with isolated thrombocytopenia were due to immune thrombocytopenia.

Conclusion

Bone marrow examination is a useful investigation for HIV-positive patients with cytopenias, suspected haematological malignancy and lymphoma staging. However, its early use in patients with isolated anaemia and isolated thrombocytopenia is questionable.

Micro-Computed Tomography Analysis of the Human Tuberculous Lung Reveals Remarkable Heterogeneity in Three-dimensional Granuloma Morphology

Rationale: Our current understanding of tuberculosis (TB) pathophysiology is limited by a reliance on animal models, the paucity of human TB lung tissue, and traditional histopathological analysis, a destructive two-dimensional approach that provides limited spatial insight. Determining the three-dimensional (3D) structure of the necrotic granuloma, a characteristic feature of TB, will more accurately inform preventive TB strategies.Objectives: To ascertain the 3D shape of the human tuberculous granuloma and its spatial relationship with airways and vasculature within large lung tissues.Methods: We characterized the 3D microanatomical environment of human tuberculous lungs by using micro computed tomography, histopathology, and immunohistochemistry. By using 3D segmentation software, we accurately reconstructed TB granulomas, vasculature, and airways in three dimensions and confirmed our findings by using histopathology and immunohistochemistry.Measurements and Main Results: We observed marked heterogeneity in the morphology, volume, and number of TB granulomas in human lung sections. Unlike depictions of granulomas as simple spherical structures, human necrotic granulomas exhibit complex, cylindrical, branched morphologies that are connected to the airways and shaped by the bronchi. The use of 3D imaging of human TB lung sections provides unanticipated insight into the spatial organization of TB granulomas in relation to the airways and vasculature.Conclusions: Our findings highlight the likelihood that a single, structurally complex lesion could be mistakenly viewed as multiple independent lesions when evaluated in two dimensions. In addition, the lack of vascularization within obstructed bronchi establishes a paradigm for antimycobacterial drug tolerance. Lastly, our results suggest that bronchogenic spread of Mycobacterium tuberculosis reseeds the lung.

The Manifesto of Pharmacoenosis: Merging HIV Pharmacology into Pathocoenosis and Syndemics in Developing Countries

Pathocoenosis and syndemics theories have emerged in the last decades meeting the frequent need of better understanding interconnections and reciprocal influences that coexistent communicable and non-communicable diseases play in a specific population. Nevertheless, the attention to pharmacokinetic and pharmacodynamics interactions of co-administered drugs for co-present diseases is to date limitedly paid to alert against detrimental pharmacological combos. Low and middle-income countries are plagued by the highest burden of HIV, tuberculosis, malaria, and helminthiasis, and they are experiencing an alarming rise in non-communicable disorders. In these settings, co-infections and comorbidities are common, but no tailored prescribing nor clinical trials are used to assess and exploit existing opportunities for the simultaneous and potentially synergistic treatment of intertwined diseases. Pharmacoenosis is the set of interactions that take place within a host as well as within a population due to the compresence of two or more diseases and their respective treatments. This framework should pilot integrated health programmes and routine clinical practice to face drug–drug interaction issues, avoiding negative co-administrations but also exploiting potential favourable ones to make the best out of the worst situations; still, to date, guiding data on the latter possibility is limited. Therefore, in this narrative review, we have briefly described both detrimental and favourable physiopathological interactions between HIV and other common co-occurring pathologies (malaria, tuberculosis, helminths, and cardiovascular disorders), and we have presented examples of advantageous potential pharmacological interactions among the drugs prescribed for these diseases from a pharmacokinetics, pharmacodynamics, and pharmacogenetics standpoint.

Pathology of TB/COVID-19 Co-Infection: The phantom menace

Tuberculosis (TB) and coronavirus disease 2019 (COVID-19) are currently the two main causes of death among infectious diseases. There is an increasing number of studies trying to elucidate the interactions between Mycobacterium tuberculosis and SARS-CoV-2. Some of the first case reports point to a worsening of respiratory symptoms in co-infected TB/COVID-19 individuals. However, data from the cohort studies has shown some conflicting results. This study proposes to conduct a systematic review on the current literature on TB/COVID-19 co-infection cohorts, evaluating clinical and epidemiological data, focusing on its implications to the immune system. From an immunological perspective, the TB/COVID-19 co-infection has the potential to converge in a "perfect storm". The disorders induced by each pathogen to the immunomodulation tend to induce an unbalanced inflammatory response, which can promote the progression and worsening of both diseases. Understanding the nature of the interactions between M. tuberculosis and SARS-CoV-2 will be crucial for the development of therapeutic strategies against co-infection.

Replication of Small Ruminant Lentiviruses in Aluminum Hydroxide-Induced Granulomas in Sheep: a Potential New Factor for Viral Dissemination

Aluminum (Al)-based salts are widely used adjuvants in ruminants and other species to strengthen the immune response elicited against vaccine antigen(s). However, they can lead to the formation of long-lasting granulomas composed of abundant activated macrophages. Small ruminant lentiviruses (SRLV) are widely distributed macrophage-tropic retroviruses that cause persistent infections in sheep and goats. Infected monocytes/macrophages and dendritic cells establish an inflammatory microenvironment that eventually leads to clinical manifestations. The aim of this work was to study the effect of Al-induced granulomas in the replication and pathogenesis of SRLV. Eleven adult, naturally SRLV-infected sheep showing clinical arthritis were distributed in vaccine (n = 6), adjuvant-only (n = 3), and control (n = 2) groups and inoculated with commercial Al-based vaccines, Al hydroxide adjuvant alone, or phosphate-buffered saline, respectively. In vitro studies demonstrated viral replication in Al-induced granulomas in 5 out of 10 sheep. Immunohistochemistry (IHC) evinced granular, intracytoplasmic SRLV presence in macrophages within granulomas. Viral sequences obtained from granulomas, blood monocytes, and other tissues were highly similar in most animals, suggesting virus circulation among body compartments. However, notable differences between isolated strains in granulomas and other tissues in specific animals were also noted. Interestingly, the B2 subtype was the most commonly found SRLV genotype, reaching a wider body distribution than previously described. Recombination events between genotypes B2 and A3 along the gag region were identified in two sheep. Our results indicate that Al-hydroxide-derived granulomas may represent an ideal compartment for SRLV replication, perhaps altering natural SRLV infection by providing a new, suitable target tissue.IMPORTANCE Granulomas are inflammation-derived structures elicited by foreign bodies or certain infections. Aluminum adjuvants included in vaccines induce granulomas in many species. In sheep, these are persistent and consist of activated macrophages. Small ruminant lentiviruses (SRLV), which are macrophage-tropic lentiviruses, cause a chronic wasting disease affecting animal welfare and production. Here, we studied the occurrence of SRLV in postvaccination granulomas retrieved from naturally infected ewes after vaccination or inoculation with aluminum only. SRLV infection was confirmed in granulomas by identification of viral proteins, genomic fragments, and enzymatic activity. The infecting SRLV strain, previously found exclusively in carpal joints, reached the central nervous system, suggesting that occurrence of SRLV in postvaccination granulomas may broaden tissue tropism. SRLV recombination was detected in inoculated animals, a rare event in sheep lentiviruses. Potentially, virus-host interactions within granulomas may modify viral pathogenesis and lead to more widespread infection.

Pathogenesis of Human Immunodeficiency Virus-Mycobacterium tuberculosis Co-Infection

Given that infection with Mycobacterium tuberculosis (Mtb) is the leading cause of death amongst individuals living with HIV, understanding the complex mechanisms by which Mtb exacerbates HIV infection may lead to improved treatment options or adjuvant therapies. While it is well-understood how HIV compromises the immune system and leaves the host vulnerable to opportunistic infections such as Mtb, less is known about the interplay of disease once active Mtb is established. This review explores how glutathione (GSH) depletion, T cell exhaustion, granuloma formation, and TNF-α upregulation, as a result of Mtb infection, leads to an increase in HIV disease severity. This review also examines the difficulties of treating coinfected patients and suggests further research on the clinical use of GSH supplementation.

Incidence and Presentation of Sarcoidosis With and Without HIV Infection

Background

Case reports describe incident sarcoidosis in persons with HIV (PWH). The association between HIV and risk of sarcoidosis, and differences in presentation in PWH, have not been systematically assessed.

Methods

Subjects were selected from the Veterans Aging Cohort Study (VACS), a longitudinal cohort study including veterans with HIV and matched uninfected veterans. This was a prospective observational analysis in which we evaluated both the incidence (via incidence rate ratio) and presentation and treatment (by comparison of rates of organ involvement and use of medications) of sarcoidosis in PWH compared with HIV-negative controls. We also assessed risk factors (via Cox regression) associated with the development of sarcoidosis including CD4 count and viral load trajectory.

Results

Of 1614 patients evaluated via chart review, 875 (54%) had prevalent sarcoidosis and 325 (20%) had confirmed incident sarcoidosis. Incident sarcoidosis occurred in 59 PWH and 266 uninfected. The incidence of sarcoidosis was lower in PWH than uninfected (incidence rate ratio [IRR], 0.61; 95% CI, 0.46-0.81) and especially low in patients with unsuppressed viremia (IRR, 0.04; 95% CI, 0.02-0.08) compared with uninfected). At diagnosis of sarcoidosis, the median CD4 count among PWH was 409 cells/mm³; 77% had HIV-1 RNA <500 copies/mL. No significant differences were observed between PWH and uninfected in terms of organ involvement, disease severity, or use of oral glucocorticoids.

Conclusions

HIV, particularly with persistent viremia, was associated with decreased risk of incident sarcoidosis; severity and treatment were similar between PWH and uninfected.

SIV and Mycobacterium tuberculosis synergy within the granuloma accelerates the reactivation pattern of latent tuberculosis

Human immunodeficiency virus infection is the most common risk factor for severe forms of tuberculosis (TB), regardless of CD4 T cell count. Using a well-characterized cynomolgus macaque model of human TB, we compared radiographic, immunologic and microbiologic characteristics of early (subclinical) reactivation of latent M. tuberculosis (Mtb) infection among animals subsequently infected with simian immunodeficiency virus (SIV) or who underwent anti-CD4 depletion by a depletion antibody. CD4 depleted animals had significantly fewer CD4 T cells within granulomas compared to Mtb/SIV co-infected and Mtb-only control animals. After 2 months of treatment, subclinical reactivation occurred at similar rates among CD4 depleted (5 of 7 animals) and SIV infected animals (4 of 8 animals). However, SIV-induced reactivation was associated with more dissemination of lung granulomas that were permissive to Mtb growth resulting in greater bacterial burden within granulomas compared to CD4 depleted reactivators. Granulomas from Mtb/SIV animals displayed a more robust T cell activation profile (IFN-α, IFN-γ, TNF, IL-17, IL-2, IL-10, IL-4 and granzyme B) compared to CD4 depleted animals and controls though these effectors did not protect against reactivation or dissemination, but instead may be related to increased viral and/or Mtb antigens. SIV replication within the granuloma was associated with reactivation, greater overall Mtb growth and reduced Mtb killing resulting in greater overall Mtb burden. These data support that SIV disrupts protective immune responses against latent Mtb infection beyond the loss of CD4 T cells, and that synergy between SIV and Mtb occurs within granulomas.

Tuberculosis Exacerbates HIV-1 Infection through IL-10/STAT3-Dependent Tunneling Nanotube Formation in Macrophages

The tuberculosis (TB) bacillus, Mycobacterium tuberculosis (Mtb), and HIV-1 act synergistically; however, the mechanisms by which Mtb exacerbates HIV-1 pathogenesis are not well known. Using in vitro and ex vivo cell culture systems, we show that human M(IL-10) anti-inflammatory macrophages, present in TB-associated microenvironment, produce high levels of HIV-1. In vivo, M(IL-10) macrophages are expanded in lungs of co-infected non-human primates, which correlates with disease severity. Furthermore, HIV-1/Mtb co-infected patients display an accumulation of M(IL-10) macrophage markers (soluble CD163 and MerTK). These M(IL-10) macrophages form direct cell-to-cell bridges, which we identified as tunneling nanotubes (TNTs) involved in viral transfer. TNT formation requires the IL-10/STAT3 signaling pathway, and targeted inhibition of TNTs substantially reduces the enhancement of HIV-1 cell-to-cell transfer and overproduction in M(IL-10) macrophages. Our study reveals that TNTs facilitate viral transfer and amplification, thereby promoting TNT formation as a mechanism to be explored in TB/AIDS potential therapeutics.

Individual and clinical variables associated with the risk of Buruli ulcer acquisition: A systematic review and meta-analysis

BACKGROUND

Buruli ulcer (BU) is a necrotizing skin disease, caused by Mycobacterium ulcerans, with poorly understood acquisition risk factors. This review aims at evaluating the importance of individual-sex, age, family ties with history of BU, gene variants-and clinical-Bacillus Calmette-Guérin (BCG) immunization, Human Immunodeficiency Virus (HIV) infection-variables in this process.

METHODS

A systematic review was performed considering the following databases: ClinicalTrials.gov, Cochrane Controlled Register of Trials (CENTRAL), Current Contents Connect, Embase, MEDLINE, SciELO, Scopus and Web of Science. Eligible studies were critically appraised with The Joanna Briggs Institute checklists and heterogeneity was assessed with Cochran Q-test and I2 statistic. Published demographic data was descriptively analysed and clinical data pooled within random-effects modelling for meta-analysis.

RESULTS

A total of 29 studies were included in the systematic review. Two randomized controlled trials (RCTs) and 21 case-control studies were selected for meta-analysis. Studies show that BU mainly affects age extremes, more preponderately males among children. Data pooled from RCTs do not reveal BCG to be protective against BU (odds ratio (OR) = 0.63; 95% CI = 0.38-1.05; I2 = 56%), a finding case-control studies appear to corroborate. HIV infection (OR = 6.80; 95% CI = 2.33-19.85; I2 = 0%) and SLC11A1 rs17235409 A allele (OR = 1.86; 95% CI = 1.25-2.77; I2 = 0%) are associated with increased prevalence of the disease. No definite conclusions can be drawn regarding the influence of previous family history of BU.

DISCUSSION

While available evidence warrants further robustness, these results have direct implications on current interventions and future research programs, and foster the development of more cost-effective preventive and screening measures.

REGISTRATION

The study was registered at PROSPERO with number CRD42019123611.

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.

The Mtb-HIV syndemic interaction: why treating M. tuberculosis infection may be crucial for HIV-1 eradication

Accelerated tuberculosis and AIDS progression seen in HIV-1 and Mycobacterium tuberculosis (Mtb)-coinfected individuals indicates the important interaction between these syndemic pathogens. The immunological interaction between HIV-1 and Mtb has been largely defined by how the virus exacerbates tuberculosis disease pathogenesis. Understanding of the mechanisms by which pre-existing or subsequent Mtb infection may favor the replication, persistence and progression of HIV, is less characterized. We present a rationale for the critical consideration of ‘latent’ Mtb infection in HIV-1 prevention and cure strategies. In support of this position, we review evidence of the effect of Mtb infection on HIV-1 acquisition, replication and persistence. We propose that ‘latent’ Mtb infection may have considerable impact on HIV-1 pathogenesis and the continuing HIV-1 epidemic in sub-Saharan Africa.

Classification of COVID-19 and Other Pathogenic Sequences: A Dinucleotide Frequency and Machine Learning Approach

The world is grappling with the COVID-19 pandemic caused by the 2019 novel SARS-CoV-2. To better understand this novel virus and its relationship with other pathogens, new methods for analyzing the genome are required. In this study, intrinsic dinucleotide genomic signatures were analyzed for whole genome sequence data of eight pathogenic species, including SARS-CoV-2. The genome sequences were transformed into dinucleotide relative frequencies and classified using the extreme gradient boosting (XGBoost) model. The classification models were trained to a) distinguish between the sequences of all eight species and b) distinguish between sequences of SARS-CoV-2 that originate from different geographic regions. Our method attained 100% in all performance metrics and for all tasks in the eight-species classification problem. Moreover, the models achieved 67% balanced accuracy for the task of classifying the SARS-CoV-2 sequences into the six continental regions and achieved 86% balanced accuracy for the task of classifying SARS-CoV-2 samples as either originating from Asia or not. Analysis of the dinucleotide genomic profiles of the eight species revealed a similarity between the SARS-CoV-2 and MERS-CoV viral sequences. Further analysis of SARS-CoV-2 viral sequences from the six continents revealed that samples from Oceania had the highest frequency of TT dinucleotides as well as the lowest CG frequency compared to the other continents. The dinucleotide signatures of AC, AG,CA, CT, GA, GT, TC, and TG were well conserved across most genomes, while the frequencies of other dinucleotide signatures varied considerably. Altogether, the results from this study demonstrate the utility of dinucleotide relative frequencies for discriminating and identifying similar species.

Unmasking the hidden tuberculosis mortality burden in a large post mortem study in Maputo Central Hospital, Mozambique

Sensitive tools are needed to accurately establish the diagnosis of tuberculosis (TB) at death, especially in low-income countries. The objective of this study was to evaluate the burden of TB in a series of patients who died in a tertiary referral hospital in sub-Saharan Africa using an in-house real time PCR (TB-PCR) and the Xpert MTB/RIF Ultra (Xpert Ultra) assay.

Complete diagnostic autopsies were performed in a series of 223 deaths (56.5% being HIV-positive), including 54 children, 57 maternal deaths and 112 other adults occurring at the Maputo Central Hospital, Mozambique. TB-PCR was performed in all lung, cerebrospinal fluid and central nervous system samples in HIV-positive patients. All samples positive for TB-PCR or showing histological findings suggestive of TB were analysed with the Xpert Ultra assay.

TB was identified as the cause of death in 31 patients: three out of 54 (6%) children, five out of 57 (9%)maternal deaths and 23 out of 112 (21%) other adults. The sensitivity of the main clinical diagnosis to detect TB as the cause of death was 19.4% (95% CI 7.5–37.5) and the specificity was 97.4% (94.0–99.1) compared to autopsy findings. Concomitant TB (TB disease in a patient dying of other causes) was found in 31 additional cases. Xpert Ultra helped to identify 15 cases of concomitant TB. In 18 patients, Mycobacterium tuberculosis DNA was identified by TB-PCR and Xpert Ultra in the absence of histological TB lesions. Overall, 62 (27.8%) cases had TB disease at death and 80 (35.9%) had TB findings.

The use of highly sensitive, easy to perform molecular tests in complete diagnostic autopsies may contribute to identifying TB cases at death that would have otherwise been missed. Routine use of these tools in certain diagnostic algorithms for hospitalised patients needs to be considered. Clinical diagnosis showed poor sensitivity for the diagnosis of TB at death.

This study shows the usefulness of molecular assays in ascertaining TB diagnosis at death. It questions the information of clinical diagnoses obtained from hospital registries as a reliable tool for TB mortality estimation.http://bit.ly/2KrzTBJ

Conformational Switch Driven Membrane Pore Formation by Mycobacterium Secretory Protein MPT63 Induces Macrophage Cell Death

Virulent Mycobacterium tuberculosis (MTB) strains cause cell death of macrophages (Mϕ) inside TB granuloma using a mechanism which is not well understood. Many bacterial systems utilize toxins to induce host cell damage, which occurs along with immune evasion. These toxins often use chameleon sequences to generate an environment-sensitive conformational switch, facilitating the process of infection. The presence of toxins is not yet known for MTB. Here, we show that MTB-secreted immunogenic MPT63 protein undergoes a switch from β-sheet to helix in response to mutational and environmental stresses. MPT63 in its helical form creates pores in both synthetic and Mϕ membranes, while the native β-sheet protein remains inert toward membrane interactions. Using fluorescence correlation spectroscopy and atomic force microscopy, we show further that the helical form undergoes self-association to produce toxic oligomers of different morphology. Trypan blue and flow cytometry analyses reveal that the helical state can be utilized by MTB for killing Mϕ cells. Collectively, our study emphasizes for the first time a toxin-like behavior of MPT63 induced by an environment-dependent conformational switch, resulting in membrane pore formation by toxic oligomers and Mϕ cell death.

HIV prevalence, knowledge and self-perceived risk of HIV infection among tuberculosis patients in Serbia

OBJECTIVE

The aim of the study was to estimate the seroprevalence of HIV infection among TB patients, knowledge, self-perceived risks and testing practices related to HIV.

METHODS

We performed cross-sectional study from 10 May to 15 July 2011. Cluster sampling method was used to select 27 hospitals where 289 TB patients were consecutively recruited. Descriptive statistics and multivariable logistic regression methods were used to identify the factors associated with correct comprehensive knowledge of HIV/AIDS.

RESULTS

HIV prevalence among TB patients was 0.3%. Only 25.2% of the respondents presented comprehensive correct knowledge of HIV/AIDS. The percentage of correct answers to all questions related to knowledge about HIV/AIDS increases with educational status (χ² = 5.42; p &lt; 0.05) and decreases with the age of respondents (χ² = 8.53; p &gt; 0.05). The independent predictors of correct comprehensive knowledge were living without partner (OR = 4.45; CI = 1.59-12.95) and self-awareness of HIV risk (OR = 4.43; CI = 1.20-16.52).

CONCLUSION

HIV prevalence among TB patients is higher than among general population in Serbia. The level of comprehensive correct knowledge of HIV/AIDS is low. There is a need for continuous implementation of public health strategy to successfully manage HIV and HIV/TB co-infection in Serbia.

Novel therapeutic approaches for targeting TB and HIV reservoirs prevailing in lungs

INTRODUCTION

Coinfection with Mycobacterium tuberculosis is the leading cause of death in HIV positive patients. In 2017, about 0.3 million HIV positive people died of tuberculosis. There is high load of mycobacteria and HIV in the lungs and eradication of the same is vital for patient survival.

AREAS COVERED

This review focuses on the pathogenesis of HIV-TB coinfection and the current management approaches of this coinfection. It presents a detailed discussion of current investigations in novel drug delivery systems for effective targeting of HIV-TB lung reservoirs, especially via pulmonary drug delivery. Additionally, emphasis is given to the need of HIV-TB cotargeting, an unmet need in management of HIV-TB coinfection.

EXPERT OPINION

To achieve the goal of complete eradication of HIV-TB reservoirs in lungs requires focused research strategies to be undertaken in the area of pulmonary delivery systems. These endeavors could eventually lead to better patient compliance and improved treatment outcomes. The treatment regimen of HIV-TB coinfection is associated with a major drawback of low therapeutic concentration of drugs in lungs. Nanotechnology provides an excellent platform for delivery of anti-TB and anti-HIV drugs via the pulmonary route thereby serving as a viable and effective means of managing the mycobacterial and HIV reservoirs in the lungs.

The hidden hypothesis: A disseminated tuberculosis case

CASE PRESENTATION

77-year-old former smoker admitted because of fatigue and abdominal distention. Past medical history positive for two previous hospitalizations for pericardial and pleural effusions (no diagnosis achieved). At admission erythrocyte sedimentation rate was 122mm per hour. Baseline investigations revealed ascitic, pleural and pericardial effusion. Effusions were tapped: neoplastic cells and acid-fast bacilli (AFB) were not identified, aerobic and mycobacterial culture resulted negative. QuantiFERON TB-Gold test was negative. Total body PET-CT and autoimmunity panel were negative. A neoplastic process was considered the most likely explanation. Before signing off the patient to comfort care, a reassessment was performed and an exposure to tuberculosis during childhood was documented. Because of constrictive pericarditis, pericardiectomy was performed: histologic examination showed chronic pericardial inflammation without granulomas, but Ziehl-Neelsen stain identified AFB and PCR was positive for Mycobacterium tuberculosis complex. Patient was started on anti-TB therapy with resolution of the effusions in the following months. Genes associated with defects in innate immunity were sequences and dentritic cells were studied, but no alterations were identified.

DISCUSSION

A Bayesian approach to clinical decision making should be recommended. Interpretation of diagnostic tests should take into account the imperfect diagnostic performance of the majority of these tests. Further studies to investigate genetic susceptibility to tuberculosis are needed.

Comparison of Löwenstein-Jensen and BACTEC MGIT 960 culture for Mycobacterium tuberculosis in people living with HIV

OBJECTIVES

The aim of the study was to clarify how HIV infection affects tuberculosis liquid and solid culture results in a resource-limited setting.

METHODS

We used baseline data from the Study on Outcomes Related to Tuberculosis and HIV Drug Concentrations in Uganda (SOUTH), which included 268 HIV/tuberculosis (TB)-coinfected individuals. Culture results from Löwenstein-Jensen (LJ) solid culture and mycobacteria growth indicator tube (MGIT) liquid culture systems and culture-based correlates for bacillary density from the sputum of HIV/TB-coinfected individuals at baseline were analysed.

RESULTS

Of 268 participants, 243 had a CD4 cell count available and were included in this analysis; 72.2% of cultures showed growth on solid culture and 82.2% in liquid culture systems (P < 0.015). A higher CD4 cell count was predictive of LJ positivity [adjusted odds ratio (OR) 1.14; 95% confidence interval (CI) 1.03-1.25 per 50 cells/μL increase; P = 0.008]. The same, but insignificant trend was observed for MGIT positivity (adjusted OR 1.09; 95% CI 0.99-1.211 per 50 cells/μL increase; P = 0.094). A higher CD4 cell count was associated with a higher LJ colony-forming unit grade (adjusted OR 1.14; 95% CI 1.05-1.25 per 50 cells/μL increase; P = 0.011) and a shorter time to MGIT positivity [adjusted hazard ratio (HR) 1.08; 95% CI 1.04-1.12 per 50 cells/μL increase; P < 0.001].

CONCLUSIONS

In a resource-limited setting, the MGIT liquid culture system outperformed LJ solid culture in terms of culture yield and dependence on CD4 cell counts in HIV/TB-coinfected individuals. We therefore suggest considering an adaptation of diagnostic algorithms: when resources allow only one culture method to be performed, we recommend that MGIT liquid culture should be used exclusively in HIV-positive individuals as a first-line culture method, to reduce costs and make TB culture results accessible to more patients in resource-limited settings.

Host-pathogen redox dynamics modulate Mycobacterium tuberculosis pathogenesis

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, encounters variable and hostile environments within the host. A major component of these hostile conditions is reductive and oxidative stresses induced by factors modified by the host immune response, such as oxygen tension, NO or CO gases, reactive oxygen and nitrogen intermediates, the availability of different carbon sources and changes in pH. It is therefore essential for Mtb to continuously monitor and appropriately respond to the microenvironment. To this end, Mtb has developed various redox-sensitive systems capable of monitoring its intracellular redox environment and coordinating a response essential for virulence. Various aspects of Mtb physiology are regulated by these systems, including drug susceptibility, secretion systems, energy metabolism and dormancy. While great progress has been made in understanding the mechanisms and pathways that govern the response of Mtb to the host's redox environment, many questions in this area remain unanswered. The answers to these questions are promising avenues for addressing the tuberculosis crisis.

The Immune Response to Mycobacterium tuberculosis in HIV-1-Coinfected Persons

Globally, about 36.7 million people were living with HIV infection at the end of 2015. The most frequent infection co-occurring with HIV-1 is Mycobacterium tuberculosis-374,000 deaths per annum are attributable to HIV-tuberculosis, 75% of those occurring in Africa. HIV-1 infection increases the risk of tuberculosis by a factor of up to 26 and alters its clinical presentation, complicates diagnosis and treatment, and worsens outcome. Although HIV-1-induced depletion of CD4⁺ T cells underlies all these effects, more widespread immune deficits also contribute to susceptibility and pathogenesis. These defects present a challenge to understand and ameliorate, but also an opportunity to learn and optimize mechanisms that normally protect people against tuberculosis. The most effective means to prevent and ameliorate tuberculosis in HIV-1-infected people is antiretroviral therapy, but this may be complicated by pathological immune deterioration that in turn requires more effective host-directed anti-inflammatory therapies to be derived.

Spinal tuberculosis: review of current management

Tuberculosis (TB) remains endemic in many parts of the developing world and is increasingly seen in the developed world due to migration. A total of 1.3 million people die annually from the disease. Spinal TB is the most common musculoskeletal manifestation, affecting about 1 to 2% of all cases of TB. The coexistence of HIV, which is endemic in some regions, adds to the burden and the complexity of management. This review discusses the epidemiology, clinical presentation, diagnosis, impact of HIV and both the medical and surgical options in the management of spinal TB. Cite this article: Bone Joint J 2018;100-B:425-31.

NeuroAIDS in children

The human immunodeficiency virus-1 (HIV-1) enters the central nervous system compartment within the first few weeks of systemic HIV infection and may cause a spectrum of neurologic complications. Without combination antiretroviral therapy (cART), 50-90% of all HIV-infected infants and children develop some form of neuroAIDS. Of the estimated 2.3 million children less than 15 years of age who were living in sub-Saharan Africa at the end of 2014, only 30% were receiving cART, suggesting that there is a large burden of neuroAIDS among HIV-infected children in sub-Saharan Africa. There is complex interplay between the disease process itself, the child's immune reaction to the disease, the secondary complications, the side-effects of antiretroviral drugs, and inadequate antiretroviral drug uptake into the central nervous system. In addition there is the layering effect from the multiple socioeconomic challenges for children living in low- and middle-income countries. Adolescents may manifest with a range of neurocognitive sequelae from mild neurocognitive disorder through to severe neurocognitive impairment. Neuroimaging studies on white-matter tracts have identified dysfunction, especially in the frontostriatal networks needed for executive function. Psychiatric symptoms of depression, attention deficit hyperactivity disorder, and behavioral problems are also commonly reported in this age group. Antiretroviral drugs may cause treatment-limiting neurologic and neuropsychiatric adverse reactions. The following chapter addresses the neurologic complications known to be, and suspected of being, associated with HIV infection in children and adolescents.

Integrating Lung Physiology, Immunology, and Tuberculosis

Lungs are directly exposed to the air, have enormous surface area, and enable gas exchange in air-breathing animals. They are constantly 'attacked' by microbes from both outside and inside and thus possess a unique, highly regulated local immune defense system which efficiently allows for microbial clearance while minimizing damaging inflammatory responses. As a prototypic host-adapted airborne pathogen, Mycobacterium tuberculosis traverses the lung and has several 'interaction points' (IPs) which it must overcome to cause infection. These interactions are critical, not only from a pathogenesis perspective but also in considering the effectiveness of therapies and vaccines in the lungs. Here we discuss emerging views on immunologic interactions occurring in the lungs for M. tuberculosis and their impact on infection and persistence.