Immunosuppressive Features of the Microenvironment in Lymph Nodes Granulomas from Tuberculosis and HIV-Co-Infected Patients

Bird's Eye View on Mycobacterium tuberculosis-HIV Coinfection: Understanding the Molecular Synergism, Challenges, and New Approaches to Therapeutics

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is the most common secondary infection in the Human Immunodeficiency Virus (HIV) infected population, accounting for more than one-fourth of deaths in people living with HIV (PLWH). Reciprocally, HIV infection increases the susceptibility to primary TB or reactivation of latent TB by several folds. The synergistic interactions between M.tb and HIV not only potentiate their deleterious impact but also complicate the clinical management of both the diseases. M.tb-HIV coinfected patients have a high risk of failure of accurate diagnosis, treatment inefficiency for both TB and HIV, concurrent nontuberculous mycobacterial infections, other comorbidities such as diabetes mellitus, severe cytotoxicity due to drug overburden, and immune reconstitution inflammatory syndrome (IRIS). The need of the hour is to understand M.tb-HIV coinfection biology and their collective impact on the host immunocompetence and to think of out-of-the-box treatment perspectives, including host-directed therapy under the rising view of homeostatic medicines. This review aims to highlight the molecular players, both from the pathogens and host, that facilitate the synergistic interactions and host-associated proteins/enzymes regulating immunometabolism, underlining potential targets for designing and screening chemical inhibitors to reduce the burden of both pathogens concomitantly during M.tb-HIV coinfection. To appreciate the necessity of revisiting therapeutic approaches and research priorities, we provide a glimpse of anti-TB and antiretroviral drug-drug interactions, project the gaps in our understanding of coinfection biology, and also enlist some key research initiatives that will help us deal with the synergistic epidemic of M.tb-HIV coinfection.

Co-Infections and Their Prognostic Impact on Melioidosis Mortality: A Systematic Review and Individual Patient Data Meta-Analysis

Objectives: This study aimed to evaluate the prognostic impact of coinfections and other clinical factors on mortality in melioidosis patients, providing a comprehensive analysis through systematic review and meta-analysis. Methods: A systematic search was conducted in PubMed, Embase, Scopus, and other sources for studies published from their inception to August 2023. Studies reporting mortality outcomes in melioidosis patients with and without coinfections were included. Mixed-effects logistic regression models were used to estimate the causal association of each prognostic factor on the outcome. Directed acyclic graphs (DAGs) were used to guide confounding adjustment, and missing data were handled using multiple imputations. Results: A total of 346 studies involving 509 patients were analyzed. Coinfections were observed in 10.8% of patients with tuberculosis and Leptospira spp. being the most common. Disseminated disease significantly increased the odds of death (OR 4.93, 95% CI: 2.14-11.37, p < 0.001). Coinfections were associated with a higher mortality rate, but the association was not statistically significant (OR 2.70, 95% CI: 0.53-13.90, p = 0.172). Sensitivity analyses confirmed the robustness of the findings. Other factors, including diabetes mellitus and agricultural occupation, were evaluated for their associations with mortality. Conclusions: Disseminated melioidosis remains a significant factor influencing prognosis. Although less common, coinfections may contribute to worsen patient outcomes, emphasizing the importance of immediate and accurate diagnosis and comprehensive management.

Multiomic analysis identifies suppressive myeloid cell populations in human TB granulomas

Tuberculosis (TB) remains a major global health challenge, particularly in the context of multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb). Host-directed therapies (HDTs) have been proposed as adjunctive therapy to enhance immune control of infection. Recently, one such HDT, pharmacologic modulation of myeloid-derived suppressor cells (MDSCs), has been proposed to treat MDR-TB. While MDSCs have been well characterized in cancer, their role in TB pathogenesis remains unclear. To investigate whether MDSCs or other myeloid suppressor populations contribute to TB granuloma microenvironments (GME), we performed spatial transcriptional profiling and single-cell immunophenotyping on eighty-four granulomas in lung specimens from three individuals with active disease. Granulomas were histologically classified based on H&E staining, and transcriptional signatures were compared across regions of interest (ROIs) at different states of granuloma maturation. Our analysis revealed that immune suppression within granuloma was not primarily driven by classical MDSCs but rather by multiple myeloid cell subsets, including dendritic cells expressing indoleamine 2,3 dioxygenase-1 expressing (IDO1+ DCs). IDO1+ DCs were the most frequently observed suppressive myeloid cells, particularly in cellular regions, and their spatial proximity to activated T cells suggested localized immunosuppression. Importantly, granulomas at different stages contained distinct proportions of suppressor myeloid cells, with necrotic and cellular regions showing different myeloid phenotypes that may influence granuloma progression. Gene set enrichment analysis (GSEA) further indicated that elevated IDO1 expression was associated with a complex immune response that balanced suppressive signaling, immune activation, and cellular metabolism. These findings suggest that classical MDSCs, as defined in tumor microenvironments, likely play a minor role in TB, whereas IDO1+ DCs may be key regulators of immune suppression in granulomas influencing local Mtb control in infected lung. A deeper understanding of the role of IDO1+ suppressive myeloid cells in TB granulomas is essential to assessing their potential as therapeutic targets in TB treatment.

Two Cases of Testicular Tuberculosis and Review of the Recent Literature

In this review, two cases of testicular tuberculosis (TB) are presented, and another 58 cases published in PubMed between January 1, 2012, and July 31, 2023, are reviewed. Testicular TB remains a disease mainly of the developing world, with one notable exception - the infections caused as a result of Bacillus Calmette-Guérin infusion immunotherapy for bladder cancer. Its clinical course is subacute; however, it might get disseminated and become life-threatening; therefore, prompt diagnosis is very important. The diagnosis can be quite challenging, and testicular tissue is the sample with the highest diagnostic yield, either for microbiological or histopathological diagnosis. On the other hand, its treatment follows the standard guidelines for TB treatment; however, the avoidance of an unnecessary orchiectomy is important.

Histopathologic patterns of female genital tuberculosis with clinical correlation: a 10-year (2013-2022) retrospective cross-sectional study

OBJECTIVE

Underdiagnosis of female genital tuberculosis (FGTB) often leads to infertility. In this study, we aimed to determine the site and histopathologic patterns of FGTB and its correlation with clinical presentation and acid-fast bacilli (AFB) status.

METHODS

A retrospective cross-sectional study was conducted on 122 patients with a histopathological diagnosis of FGTB at the Department of Pathology, College of Health Sciences (CHS), Tikur Anbessa Specialized Hospital (TASH), Addis Ababa University (AAU), from January 1, 2013, to August 30, 2022.

RESULTS

Female genital tuberculosis was found in 0.94% of the gynecology specimens examined. The most common presentations were menstrual disturbance, abdominopelvic pain, and infertility. Among patients with FGTB, 4.6% exhibited misleading clinical and radiologic findings, leading to suspicion of malignancy and subsequent aggressive surgical management. The endometrium was the most frequently affected organ, followed by the fallopian tube, ovary, cervix, and vulva. In the majority of tuberculous endometritis cases (53.3%), histopathology revealed early-stage granulomas. Acid-fast bacilli were found in a significant proportion (42.6%) of FGTB tissues with TB histopathology. The ovary had the highest rate of AFB detection, followed by the fallopian tube, endometrium, and cervix.

CONCLUSION

Female genital tuberculosis should be considered in reproductive-age women presenting with menstrual irregularities, abdominopelvic pain, infertility, or an abdominopelvic mass. The endometrium is commonly affected, displaying early granulomas with low AFB positivity.

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

Background

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

Methods

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

Results

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

Conclusions

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

Suppressive myeloid cells in SARS-CoV-2 and Mycobacterium tuberculosis co-infection

Epidemiologic data show that both current and previous tuberculosis (TB) increase the risk of in-hospital mortality from coronavirus disease-2019 (COVID-19), and there is a similar trend for poor outcomes from Mycobacterium tuberculosis (Mtb) infection after recent SARS-CoV-2. A shared dysregulation of immunity explains the dual risk posed by co-infection, but the specific mechanisms are being explored. While initial attention focused on T cell immunity, more comprehensive analyses revealed a dysfunctional innate immune response in COVID-19, characterized by reduced numbers of dendritic cells, NK cells and a redistribution of mononuclear phagocytes towards intermediate myeloid subsets. During hyper- or chronic inflammatory processes, activation signals from molecules such as growth factors and alarmins lead to the expansion of an immature population of myeloid cells called myeloid-deprived suppressor cells (MDSC). These cells enter a state of pathological activation, lose their ability to rapidly clear pathogens, and instead become broadly immunosuppressive. MDSC are enriched in the peripheral blood of patients with severe COVID-19; associated with mortality; and with higher levels of inflammatory cytokines. In TB, MDSC have been implicated in loss of control of Mtb in the granuloma and ineffective innate and T cell immunity to the pathogen. Considering that innate immune sensing serves as first line of both anti-bacterial and anti-viral defence mechanisms, we propose MDSC as a crucial mechanism for the adverse clinical trajectories of TB-COVID-19 coinfection.

Spoligotyping of the Mycobacterium tuberculosis complex using on-Chip PCR

AIMS

The aim of this study was to develop a rapid PCR-based method for spoligotyping of Mycobacteria in the microarray format and to compare it to conventional spoligotyping by hybridization.

METHODS AND RESULTS

The method employs the on-Chip PCR technique with primers specific for 43 spacers that separate direct repeats (DRs) in the DR region of mycobacterial DNA. The primers were immobilized on gel-based microarrays, and PCR was performed directly on the chips. The PCR fluorescence images were acquired and processed using a portable fluorescence analyzer equipped with dedicated software. Analysis takes 1.5-2 hours and can be carried out on clinical samples without additional handling. The analytical sensitivity of the method was 103 copies of target DNA. The spoligotyping results of 51 samples produced by the proposed method and by conventional reverse hybridization approach were in full concordance.

CONCLUSIONS

High throughput capacity, computerized data analysis, compact equipment, and reliable results make the on-Chip PCR an attractive alternative to intra- and interspecific spoligotyping of Mycobacterium tuberculosis complex bacteria.

SIGNIFICANCE AND IMPACT OF STUDY

Fast microarray-based spoligotyping technique using on-Chip PCR was developed.

Reinventing the human tuberculosis (TB) granuloma: Learning from the cancer field

Tuberculosis (TB) remains one of the deadliest infectious diseases in the world and every 20 seconds a person dies from TB. An important attribute of human TB is induction of a granulomatous inflammation that creates a dynamic range of local microenvironments in infected organs, where the immune responses may be considerably different compared to the systemic circulation. New and improved technologies for in situ quantification and multimodal imaging of mRNA transcripts and protein expression at the single-cell level have enabled significantly improved insights into the local TB granuloma microenvironment. Here, we review the most recent data on regulation of immunity in the TB granuloma with an enhanced focus on selected in situ studies that enable spatial mapping of immune cell phenotypes and functions. We take advantage of the conceptual framework of the cancer-immunity cycle to speculate how local T cell responses may be enhanced in the granuloma microenvironment at the site of Mycobacterium tuberculosis infection. This includes an exploratory definition of "hot", immune-inflamed, and "cold", immune-excluded TB granulomas that does not refer to the level of bacterial replication or metabolic activity, but to the relative infiltration of T cells into the infected lesions. Finally, we reflect on the current knowledge and controversy related to reactivation of active TB in cancer patients treated with immune checkpoint inhibitors such as PD-1/PD-L1 and CTLA-4. An understanding of the underlying mechanisms involved in the induction and maintenance or disruption of immunoregulation in the TB granuloma microenvironment may provide new avenues for host-directed therapies that can support standard antibiotic treatment of persistent TB disease.