Regulatory T Cells in Mycobacterium tuberculosis Infection

Interactions Between HDL and CD4+ T Cells: A Novel Understanding of HDL Anti-Inflammatory Properties

Several studies in animal models and human cohorts have recently suggested that HDLs (high-density lipoproteins) not only modulate innate immune responses but also adaptative immune responses, particularly CD4+ T cells. CD4+ T cells are central effectors and regulators of the adaptive immune system, and any alterations in their homeostasis contribute to the pathogenesis of cardiovascular diseases, autoimmunity, and inflammatory diseases. In this review, we focus on how HDLs and their components affect CD4+ T-cell homeostasis by modulating cholesterol efflux, immune synapsis, proliferation, differentiation, oxidative stress, and apoptosis. While the effects of apoB-containing lipoproteins on T cells have been relatively well established, this review focuses specifically on new connections between HDL and CD4+ T cells. We present a model where HDL may modulate T cells through both direct and indirect mechanisms.

The regulation and potential role of interleukin-32 in tuberculous pleural effusion

The possible protective effect of interleukin-32 (IL-32) in Mycobacterium tuberculosis (Mtb) infection has been indicated. However, few studies have been focused on IL-32 in tuberculosis patients. Additionally, the regulation of IL-32 production has rarely been reported. In the present study, the production, regulation, and role of IL-32 in tuberculous pleurisy (TBP) were investigated. We found that the content of IL-32 in tuberculous pleural effusion (TPE) was higher than the level in the malignant pleural effusion and transudative pleural effusion. The level of IL-32 mRNA in pleural fluid mononuclear cells (PFMCs) was higher than that in peripheral blood mononuclear cells (PBMCs) of patients with TBP, and this difference was mainly reflected in the splice variants of IL-32α, IL-32β, and IL-32γ. Compared with the PBMCs, PFMCs featured higher IL-32β/IL-32γ and IL-32α/IL-32γ ratios. In addition, lipopolysaccharide (LPS), Bacillus Calmette-Guérin (BCG), and H37Ra stimulation could induce IL-32 production in the PFMCs. IL-32 production was positively correlated with the TNF-α, IFN-γ, and IL-1Ra levels in TPE, whereas IFN-γ, but not TNF-α or IL-1Ra, could induce the production of IL-32 in PFMCs. Furthermore, IL-32γ could induce the TNF-α production in PFMCs. Monocytes and macrophages were the main sources of IL-32 in PFMCs. Nevertheless, direct cell-cell contact between lymphocytes and monocytes/macrophages plays an important role in enhancing IL-32 production by monocyte/macrophage cells. Finally, compared with the non-tuberculous pleural effusion, the purified CD4+ and CD8+ T cells in TPE expressed higher levels of intracellular IL-32. Our results suggested that, as a potential biomarker, IL-32 may play an essential role in the protection against Mtb infection in patients with TBP. However, further studies need to be carried out to clarify the functions and mechanisms of the IFN-γ/IL-32/TNF-α axis in patients with TBP.

Production and Evaluation of Ag85B:HspX:hFcγ1 Immunogenicity as an Fc Fusion Recombinant Multi-Stage Vaccine Candidate Against Mycobacterium tuberculosis

An urgent need is to introduce an effective vaccine against Mycobacterium tuberculosis (M.tb) infection. In the present study, a multi-stage M.tb immunodominant Fcγ1 fusion protein (Ag85B:HspX:hFcγ1) was designed and produced, and the immunogenicity of purified protein was evaluated. This recombinant fusion protein was produced in the Pichia pastoris expression system. The HiTrap-rPA column affinity chromatography purified and confirmed the fusion protein using ELISA and Western blotting methods. The co-localisation assay was used to confirm its proper folding and function. IFN-γ, IL-12, IL-4, and TGF-β expression in C57BL/6 mice then evaluated the immunogenicity of the construct in the presence and absence of BCG. After expression optimisation, medium-scale production and the Western blotting test confirmed suitable production of Ag85B:HspX:hFcγ1. The co-localisation results on antigen-presenting cells (APCs) showed that Ag85B:HspX:hFcγ1 properly folded and bound to hFcγRI. This strong co-localisation with its receptor can confirm inducing proper Th1 responses. The in vivo immunisation assay showed no difference in the expression of IL-4 but a substantial increase in the expression of IFN-γ and IL-12 (P ≤ 0.02) and a moderate increase in TGF-β (P = 0.05). In vivo immunisation assay revealed that Th1-inducing pathways have been stimulated, as IFN-γ and IL-12 strongly, and TGF-β expression moderately increased in Ag85B:HspX:hFcγ1 group and Ag85B:HspX:hFcγ1+BCG. Furthermore, the production of IFN-γ from splenocytes in the Ag85B:HspX:hFcγ1 group was enormously higher than in other treatments. Therefore, this Fc fusion protein can make a selective multi-stage delivery system for inducing appropriate Th1 responses and is used as a subunit vaccine alone or in combination with others.

Exploring the Role of Extracellular Vesicles in the Pathogenesis of Tuberculosis

Tuberculosis (TB) remains a significant global health concern, necessitating accurate diagnosis and treatment monitoring. Extracellular vesicles (EVs), including exosomes, play crucial roles in disease progression, with their associated genes serving as potential biomarkers and therapeutic targets. Leveraging publicly available RNA-Seq datasets of TB patients and healthy controls (HCs), to identify differentially expressed genes (DEGs) and their associated protein-protein interaction networks and immune cell profiles, the common EV-related DEGs were identified and validated in the GSE42830 and GSE40553 datasets. We have identified nine common EV-related DEGs (SERPINA1, TNFAIP6, MAPK14, STAT1, ITGA2B, VAMP5, CTSL, CEACAM1, and PLAUR) upregulated in TB patients. Immune cell infiltration analysis revealed significant differences between TB patients and HCs, highlighting increased proportions of various immune cells in TB patients. These DEGs are involved in crucial cellular processes and pathways related to exocytosis and immune response regulation. Notably, VAMP5 exhibited excellent diagnostic performance (AUC-0.993, sensitivity-93.8%, specificity-100%), with potential as a novel biomarker for TB. The EV-related genes can serve as novel potential biomarkers that can distinguish between TB and HCs. VAMP5, which functions in exosome biogenesis and showed significant upregulation in TB, can be targeted for therapeutic interventions and treatment outcomes.

Bacteriophage therapy for the treatment of Mycobacterium tuberculosis infections in humanized mice

The continuing emergence of new strains of antibiotic-resistant bacteria has renewed interest in phage therapy; however, there has been limited progress in applying phage therapy to multi-drug resistant Mycobacterium tuberculosis (Mtb) infections. In this study, we show that bacteriophage strains D29 and DS6A can efficiently lyse Mtb H37Rv in 7H10 agar plates. However, only phage DS6A efficiently kills H37Rv in liquid culture and in Mtb-infected human primary macrophages. We further show in subsequent experiments that, after the humanized mice were infected with aerosolized H37Rv, then treated with DS6A intravenously, the DS6A treated mice showed increased body weight and improved pulmonary function relative to control mice. Furthermore, DS6A reduces Mtb load in mouse organs with greater efficacy in the spleen. These results demonstrate the feasibility of developing phage therapy as an effective therapeutic against Mtb infection.

Mechanisms underlying immunosuppression by regulatory cells

Regulatory cells, such as regulatory T cells (Tregs), regulatory B cells (Bregs), and myeloid-derived suppressor cells (MDSCs), play a crucial role in preserving immune tolerance and controlling immune responses during infections to prevent excessive immune activation. However, pathogens have developed strategies to hijack these regulatory cells to decrease the overall effectiveness of the immune response and persist within the host. Consequently, therapeutic targeting of these immunosuppressive mechanisms during infection can reinvigorate the immune response and improve the infection outcome. The suppressive mechanisms of regulatory cells are not only numerous but also redundant, reflecting the complexity of the regulatory network in modulating the immune responses. The context of the immune response, such as the type of pathogen or tissue involved, further influences the regulatory mechanisms involved. Examples of these immunosuppressive mechanisms include the production of inhibitory cytokines such as interleukin 10 (IL-10) and transforming growth factor beta (TGF-β) that inhibit the production of pro-inflammatory cytokines and dampen the activation and proliferation of effector T cells. In addition, regulatory cells utilize inhibitory receptors like cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) to engage with their respective effector cells, thereby suppressing their function. An alternative approach involves the modulation of metabolic reprogramming in effector immune cells to limit their activation and proliferation. In this review, we provide an overview of the major mechanisms mediating the immunosuppressive effect of the different regulatory cell subsets in the context of infection.

The clinical significance of plasma sCD25 as valuable biomarker for progression and prognosis of tuberculosis

BACKGROUND

sCD25 is an important immune molecule for T cell regulation. Tracking the detection of plasma sCD25 plays an important role in the evaluation of immune function, progression, and prognosis of tuberculosis (TB) patients. This study analyzed the association of plasma sCD25 levels with clinical, laboratory, CT imaging characteristics, and clinical outcome of TB patients.

METHODS

The clinical data of 303 TB patients treated in the Fifth People's Hospital of Suzhou from October 2019 to January 2022 were retrospectively analyzed. The levels of sCD25 in plasma were detected by ELISA. According to the cut-off threshold of plasma sCD25 levels, the patients were divided into a low-value group (Group TB1) and a high-value group (Group TB2). The association of plasma sCD25 levels with clinical, laboratory, and CT imaging characteristics of TB patients, as well as their TB treatment outcome were analyzed.

RESULTS

The levels of plasma sCD25 of patients with TB patients were higher than that of the healthy control group (P < 0.01). Among the 303 TB patients, the levels were increased in Group TB2 patients (0.602 ± 0.216 vs. 1.717 ± 0.604 ng/ml, P < 0.001), and there was a progressive reduction after anti-TB treatment. Furthermore, patients in Group TB2 showed higher positive rates in sputum smear (52.0% vs. 34.3%; P = 0.003), sputum culture (69.7% vs. 56.9%; P = 0.032), Xpert MTB/RIF (66.3% vs. 51.2%; P = 0.013) and TB-DNA (51.5% vs. 31.2%; P = 0.001) than those in Group TB1. Patients in Group TB2 had higher incidence in cough (78.8% vs. 62.3%; P = 0.004), expectoration (64.4% vs. 45.1%; P = 0.001), concomitant extrapulmonary TB (14.1% vs. 5.9%; P = 0.016), cavities (47.9% vs. 34.0%; P = 0.022), and unfavorable outcomes after anti-TB treatment.

CONCLUSION

The clinical, laboratory and radiological manifestations of TB patients with high plasma sCD25 levels indicate that the disease is more severe. Tracking plasma sCD25 detection of TB patients has evident clinical significance. It is noteworthy that when the plasma sCD25 levels are significantly elevated, patients should be cautious of the TB progression and disease severity.

Immune mechanisms of granuloma formation in sarcoidosis and tuberculosis

Sarcoidosis is a complex immune-mediated disease characterized by clusters of immune cells called granulomas. Despite major steps in understanding the cause of this disease, many questions remain. In this Review, we perform a mechanistic interrogation of the immune activities that contribute to granuloma formation in sarcoidosis and compare these processes with its closest mimic, tuberculosis, highlighting shared and divergent immune activities. We examine how Mycobacterium tuberculosis is sensed by the immune system; how the granuloma is initiated, formed, and perpetuated in tuberculosis compared with sarcoidosis; and the role of major innate and adaptive immune cells in shaping these processes. Finally, we draw these findings together around several recent high-resolution studies of the granuloma in situ that utilized the latest advances in single-cell technology combined with spatial methods to analyze plausible disease mechanisms. We conclude with an overall view of granuloma formation in sarcoidosis.

Dominant negative biologics normalise the tumour necrosis factor (TNF-α) induced angiogenesis which exploits the Mycobacterium tuberculosis dissemination

BACKGROUND

Tumor necrosis factor (TNF) is known to promote T cell migration and increase the expression of vascular endothelial growth factor (VEGF) and chemokines. The administration of Xpro-1595, a dominant-negative TNF (DN-TNF) engineered to selectively inactivate soluble TNF (solTNF), has been extensively studied and proven effective in reducing TNF production without suppressing innate immunity during infection. The literature also supports the involvement of glutamic acid-leucine-arginine (ELR+) chemokines and VEGF in angiogenesis and the spread of infections.

MATERIALS AND METHODS

In this study, we administered Xpro-1595 to guinea pigs to selectively inhibit solTNF, aiming to assess its impact on Mycobacterium tuberculosis (M.tb) dissemination, bacterial growth attenuation, and immunological responses. We conducted immunohistochemical analyses, immunological assays, and colony enumeration to comprehensively study the effects of Xpro-1595 by comparing with anti-TB drugs treated M.tb infected guinea pigs. Throughout the infection and treatment period, we measured the levels of Interleukin-12 subunit alpha (IL-12), Interferon-gamma (IFN-γ), TNF, Tumor growth factor (TGF), and T lymphocytes using ELISA.

RESULTS

Our findings revealed a reduction in M.tb dissemination and inflammation without compromising the immune response during Xpro-1595 treatment. Notably, Xpro-1595 therapy effectively regulated the expression of VEGFA and ELR + chemokines, which emerged as key factors contributing to infection dissemination. Furthermore, this treatment influenced the migration of CD4 T cells in the early stages of infection, subsequently leading to a reduced T cell response and controlled proinflammatory signalling, thus mitigating inflammation.

CONCLUSION

Our study underscores the pivotal role of solTNF in the dissemination of M.tb to other organs. This preliminary investigation sheds light on the involvement of solTNF in the mechanisms underlying M.tb dissemination, although further in-depth research is warranted to fully elucidate its role in this process.

Immunomodulatory biomaterials against bacterial infections: Progress, challenges, and future perspectives

Bacterial infectious diseases are one of the leading causes of death worldwide. Even with the use of multiple antibiotic treatment strategies, 4.95 million people died from drug-resistant bacterial infections in 2019. By 2050, the number of deaths will reach 10 million annually. The increasing mortality may be partly due to bacterial heterogeneity in the infection microenvironment, such as drug-resistant bacteria, biofilms, persister cells, intracellular bacteria, and small colony variants. In addition, the complexity of the immune microenvironment at different stages of infection makes biomaterials with direct antimicrobial activity unsatisfactory for the long-term treatment of chronic bacterial infections. The increasing mortality may be partly attributed to the biomaterials failing to modulate the active antimicrobial action of immune cells. Therefore, there is an urgent need for effective alternatives to treat bacterial infections. Accordingly, the development of immunomodulatory antimicrobial biomaterials has recently received considerable interest; however, a comprehensive review of their research progress is lacking. In this review, we focus mainly on the research progress and future perspectives of immunomodulatory antimicrobial biomaterials used at different stages of infection. First, we describe the characteristics of the immune microenvironment in the acute and chronic phases of bacterial infections. Then, we highlight the immunomodulatory strategies for antimicrobial biomaterials at different stages of infection and their corresponding advantages and disadvantages. Moreover, we discuss biomaterial-mediated bacterial vaccines' potential applications and challenges for activating innate and adaptive immune memory. This review will serve as a reference for future studies to develop next-generation immunomodulatory biomaterials and accelerate their translation into clinical practice.

Ex vivo and in vivo evidence that cigarette smoke-exposed T regulatory cells impair host immunity against Mycobacterium tuberculosis

Introduction

A strong epidemiologic link exists between cigarette smoke (CS) exposure and susceptibility to tuberculosis (TB). Macrophage and murine studies showed that CS and nicotine impair host-protective immune cells against Mycobacterium tuberculosis (MTB) infection. While CS and nicotine may activate T regulatory cells (Tregs), little is known about how CS may affect these immunosuppressive cells with MTB infection.

Methods

We investigated whether CS-exposed Tregs could exacerbate MTB infection in co-culture with human macrophages and in recipient mice that underwent adoptive transfer of Tregs from donor CS-exposed mice.

Results

We found that exposure of primary human Tregs to CS extract impaired the ability of unexposed human macrophages to control an MTB infection by inhibiting phagosome-lysosome fusion and autophagosome formation. Neutralizing CTLA-4 on the CS extract-exposed Tregs abrogated the impaired control of MTB infection in the macrophage and Treg co-cultures. In Foxp3+GFP+DTR+ (Thy1.2) mice depleted of endogenous Tregs, adoptive transfer of Tregs from donor CS-exposed B6.PL(Thy1.1) mice with subsequent MTB infection of the Thy1.2 mice resulted in a greater burden of MTB in the lungs and spleens than those that received Tregs from air-exposed mice. Mice that received Tregs from donor CS-exposed mice and infected with MTB had modest but significantly reduced numbers of interleukin-12-positive dendritic cells and interferon-gamma-positive CD4+ T cells in the lungs, and an increased number of total programmed cell death protein-1 (PD-1) positive CD4+ T cells in both the lungs and spleens.

Discussion

Previous studies demonstrated that CS impairs macrophages and host-protective T effector cells in controlling MTB infection. We now show that CS-exposed Tregs can also impair control of MTB in co-culture with macrophages and in a murine model.

The functional response of human monocyte-derived macrophages to serum amyloid A and Mycobacterium tuberculosis infection

Introduction

In the course of tuberculosis (TB), the level of major acute phase protein, namely serum amyloid A (hSAA-1), increases up to a hundredfold in the pleural fluids of infected individuals. Tubercle bacilli infecting the human host can be opsonized by hSAA-1, which affects bacterial entry into human macrophages and their intracellular multiplication.

Methods

We applied global RNA sequencing to evaluate the functional response of human monocyte-derived macrophages (MDMs), isolated from healthy blood donors, under elevated hSAA-1 conditions and during infection with nonopsonized and hSAA-1-opsonized Mycobacterium tuberculosis (Mtb). In the same infection model, we also examined the functional response of mycobacteria to the intracellular environment of macrophages in the presence and absence of hSAA-1. The RNASeq analysis was validated using qPCR. The functional response of MDMs to hSAA-1 and/or tubercle bacilli was also evaluated for selected cytokines at the protein level by applying the Milliplex system.

Findings

Transcriptomes of MDMs cultured in the presence of hSAA-1 or infected with Mtb showed a high degree of similarity for both upregulated and downregulated genes involved mainly in processes related to cell division and immune response, respectively. Among the most induced genes, across both hSAA-1 and Mtb infection conditions, CXCL8, CCL15, CCL5, IL-1β, and receptors for IL-7 and IL-2 were identified. We also observed the same pattern of upregulated pro-inflammatory cytokines (TNFα, IL-6, IL-12, IL-18, IL-23, and IL-1) and downregulated anti-inflammatory cytokines (IL-10, TGFβ, and antimicrobial peptide cathelicidin) in the hSAA-1 treated-MDMs or the phagocytes infected with tubercle bacilli. At this early stage of infection, Mtb genes affected by the inside microenvironment of MDMs are strictly involved in iron scavenging, adaptation to hypoxia, low pH, and increasing levels of CO2. The genes for the synthesis and transport of virulence lipids, but not cholesterol/fatty acid degradation, were also upregulated.

Conclusion

Elevated serum hSAA-1 levels in tuberculosis enhance the response of host phagocytes to infection, including macrophages that have not yet been in contact with mycobacteria. SAA induces antigen processing and presentation processes by professional phagocytes reversing the inhibition caused by Mtb infection.

Tweaking host immune responses for novel therapeutic approaches against Mycobacterium tuberculosis

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

Next-Generation TB Vaccines: Progress, Challenges, and Prospects

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is a prevalent global infectious disease and a leading cause of mortality worldwide. Currently, the only available vaccine for TB prevention is Bacillus Calmette-Guérin (BCG). However, BCG demonstrates limited efficacy, particularly in adults. Efforts to develop effective TB vaccines have been ongoing for nearly a century. In this review, we have examined the current obstacles in TB vaccine research and emphasized the significance of understanding the interaction mechanism between MTB and hosts in order to provide new avenues for research and establish a solid foundation for the development of novel vaccines. We have also assessed various TB vaccine candidates, including inactivated vaccines, attenuated live vaccines, subunit vaccines, viral vector vaccines, DNA vaccines, and the emerging mRNA vaccines as well as virus-like particle (VLP)-based vaccines, which are currently in preclinical stages or clinical trials. Furthermore, we have discussed the challenges and opportunities associated with developing different types of TB vaccines and outlined future directions for TB vaccine research, aiming to expedite the development of effective vaccines. This comprehensive review offers a summary of the progress made in the field of novel TB vaccines.

Tuberculosis and COVID-19 Dually Affect Human Th17 Cell Immune Response

COVID-19 infection not only profoundly impacts the detection of tuberculosis infection (Tbc) but also affects modality in tuberculosis patient immune response. It is important to determine immune response alterations in latent tuberculosis infection as well as in SARS-CoV-2-infected tuberculosis patients. Such changes may have underlying effects on the development and course of further tuberculosis. Here, we aimed to review the characteristics of immune response in TB patients or convalescent COVID-19 patients with latent TB infection (LTBI).

MATERIALS AND METHODS

We analyzed the features of immune response in tuberculosis and COVID-19 patients. For this, we analyzed publications released from December 2019 to March 2023; those which were published in accessible international databases ("Medline", "PubMed", "Scopus") and with keywords such as "COVID-19", "SARS-CoV-2", "tuberculosis", "pulmonary tuberculosis", "latent tuberculosis infection", "Treg", "follicular Treg", and "Treg subsets", we considered.

RESULTS

Through our analysis, we found that tuberculosis patients who had been infected with COVID-19 previously and elevated Th1 and Th2 cell levels. High levels of Th1 and Th2 cells may serve as a positive marker, characterizing activated immune response during TB infection. COVID-19 or post-COVID-19 subjects showed decreased Th17 levels, indicating a lack of tuberculosis development. Moreover, the typical course of tuberculosis is associated with an increase in Treg level, but COVID-19 contributes to a hyperinflammatory response.

CONCLUSION

According to the data obtained, the course of tuberculosis proceeds in a dissimilar way due to the distinct immune response, elicited by SARS-CoV-2. Importantly, the development of active tuberculosis with a severe course is associated with a decline in Treg levels. Both pathogens lead to disturbed immune responses, increasing the risk of developing severe TB. The insights and findings of this paper may be used to improve the future management of individuals with latent and active tuberculosis.

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

T cells in health and disease

T cells are crucial for immune functions to maintain health and prevent disease. T cell development occurs in a stepwise process in the thymus and mainly generates CD4⁺ and CD8⁺ T cell subsets. Upon antigen stimulation, naïve T cells differentiate into CD4⁺ helper and CD8⁺ cytotoxic effector and memory cells, mediating direct killing, diverse immune regulatory function, and long-term protection. In response to acute and chronic infections and tumors, T cells adopt distinct differentiation trajectories and develop into a range of heterogeneous populations with various phenotype, differentiation potential, and functionality under precise and elaborate regulations of transcriptional and epigenetic programs. Abnormal T-cell immunity can initiate and promote the pathogenesis of autoimmune diseases. In this review, we summarize the current understanding of T cell development, CD4⁺ and CD8⁺ T cell classification, and differentiation in physiological settings. We further elaborate the heterogeneity, differentiation, functionality, and regulation network of CD4⁺ and CD8⁺ T cells in infectious disease, chronic infection and tumor, and autoimmune disease, highlighting the exhausted CD8⁺ T cell differentiation trajectory, CD4⁺ T cell helper function, T cell contributions to immunotherapy and autoimmune pathogenesis. We also discuss the development and function of γδ T cells in tissue surveillance, infection, and tumor immunity. Finally, we summarized current T-cell-based immunotherapies in both cancer and autoimmune diseases, with an emphasis on their clinical applications. A better understanding of T cell immunity provides insight into developing novel prophylactic and therapeutic strategies in human diseases.

Beneficial or detrimental activity of regulatory T cells, indoleamine 2,3-dioxygenase, and heme oxygenase-1 in the lungs is influenced by the level of virulence of Mycobacterium tuberculosis strain infection

Tuberculosis (TB) caused by the complex Mycobacterium tuberculosis (Mtb) is the main cause of death by a single bacterial agent. Last year, TB was the second leading infectious killer after SARS-CoV-2. Nevertheless, many biological and immunological aspects of TB are not completely elucidated, such as the complex process of immunoregulation mediated by regulatory T cells (Treg cells) and the enzymes indoleamine 2,3-dioxygenase (IDO) and heme oxygenase 1 (HO-1). In this study, the contribution of these immunoregulatory factors was compared in mice infected with Mtb strains with different levels of virulence. First Balb/c mice were infected by intratracheal route, with a high dose of mild virulence reference strain H37Rv or with a highly virulent clinical isolate (strain 5186). In the lungs of infected mice, the kinetics of Treg cells during the infection were determined by cytofluorometry and the expression of IDO and HO-1 by RT-PCR and immunohistochemistry. Then, the contribution of immune-regulation mediated by Treg cells, IDO and HO-1, was evaluated by treating infected animals with specific cytotoxic monoclonal antibodies for Treg cells depletion anti-CD25 (PC61 clone) or by blocking IDO and HO-1 activity using specific inhibitors (1-methyl-D,L-tryptophan or zinc protoporphyrin-IX, respectively). Mice infected with the mild virulent strain showed a progressive increment of Treg cells, showing this highest number at the beginning of the late phase of the infection (28 days), the same trend was observed in the expression of both enzymes being macrophages the cells that showed the highest immunostaining. Animals infected with the highly virulent strain showed lower survival (34 days) and higher amounts of Treg cells, as well as higher expression of IDO and HO-1 one week before. In comparison with non-treated animals, mice infected with strain H37Rv with depletion of Treg cells or treated with the enzymes blockers during late infection showed a significant decrease of bacilli loads, higher expression of IFN-g and lower IL-4 but with a similar extension of inflammatory lung consolidation determined by automated morphometry. In contrast, the depletion of Treg cells in infected mice with the highly virulent strain 5186 produced diffuse alveolar damage that was similar to severe acute viral pneumonia, lesser survival and increase of bacillary loads, while blocking of both IDO and HO-1 produced high bacillary loads and extensive pneumonia with necrosis. Thus, it seems that Treg cells, IDO and HO-1 activities are detrimental during late pulmonary TB induced by mild virulence Mtb, probably because these factors decrease immune protection mediated by the Th1 response. In contrast, Treg cells, IDO and HO-1 are beneficial when the infection is produced by a highly virulent strain, by regulation of excessive inflammation that produced alveolar damage, pulmonary necrosis, acute respiratory insufficiency, and rapid death.

Bacteriophage therapy for the treatment of Mycobacterium tuberculosis infections in humanized mice

The continuing emergence of new strains of antibiotic-resistant bacteria has renewed interest in phage therapy; however, there has been limited progress in applying phage therapy to multi-drug resistant Mycobacterium tuberculosis (Mtb) infections. In this study, we tested three bacteriophage strains for their Mtb-killing activities and found that two of them efficiently lysed Mtb H37Rv in 7H10 agar plates. However, only phage DS6A efficiently killed H37Rv in liquid culture and in Mtb-infected human primary macrophages. In subsequent experiments, we infected humanized mice with aerosolized H37Rv, then treated these mice with DS6A intravenously to test its in vivo efficacy. We found that DS6A treated mice showed increased body weight and improved pulmonary function relative to control mice. Furthermore, DS6A reduced Mtb load in mouse organs with greater efficacy in the spleen. These results demonstrated the feasibility of developing phage therapy as an effective therapeutic against Mtb infection.

Research progress on specific and non-specific immune effects of BCG and the possibility of BCG protection against COVID-19

Bacille Calmette-Guérin (BCG) is the only approved vaccine for tuberculosis (TB) prevention worldwide. BCG has an excellent protective effect on miliary tuberculosis and tuberculous meningitis in children or infants. Interestingly, a growing number of studies have shown that BCG vaccination can induce nonspecific and specific immunity to fight against other respiratory disease pathogens, including SARS-CoV-2. The continuous emergence of variants of SARS-CoV-2 makes the protective efficiency of COVID-19-specific vaccines an unprecedented challenge. Therefore, it has been hypothesized that BCG-induced trained immunity might protect against COVID-19 infection. This study comprehensively described BCG-induced nonspecific and specific immunity and the mechanism of trained immunity. In addition, this study also reviewed the research on BCG revaccination to prevent TB, the impact of BCG on other non-tuberculous diseases, and the clinical trials of BCG to prevent COVID-19 infection. These data will provide new evidence to confirm the hypotheses mentioned above.

Evaluation of Mycobacterium avium subsp. paratuberculosis isocitrate lyase (IcL) and ABC transporter (BacA) knockout mutants as vaccine candidates

There has been little success in controlling Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis, due to suboptimal diagnostics and the ineffectiveness of available vaccines. By knocking out BacA and IcL, genes required for MAP survival in dairy calves, two live-attenuated vaccine candidates were created. This study evaluated the host-specific attenuation of MAP IcL and BacA mutants in mouse and calf models, as well as the elicited immune responses. Deletion mutants were generated in MAP strain A1-157 through specialized transduction and found viable in vitro. First, the mutants' attenuation and elicited cytokine secretion were assessed in a mouse model, 3 weeks after intraperitoneal inoculation with MAP strains. Later, vaccine strains were assessed in a natural host infection model where calves received 10⁹CFU oral dose of MAP wild-type or mutant strains at 2 weeks old. Transcription levels of cytokines in PBMCs were evaluated at 12-, 14-, and 16-weeks post-inoculation (WPI) and MAP colonization in tissue was assessed at 4.5 months after inoculation. Whereas both vaccine candidates colonized mouse tissues similarly to wild-type strain, both failed to persist in calf tissues. In either mouse or calf models, gene deletion did not reduce immunogenicity. Instead, inoculation with ΔBacA induced a greater upregulation of proinflammatory cytokines than ΔIcL and wild-type in both models and a greater expansion of cytotoxic and memory T-cells than uninfected control in calves. ΔBacA and wild-type strains significantly increased secretion of IP-10, MIG, TNFα, and RANTES in mice serum compared to uninfected control. This agreed with upregulation of IL-12, IL-17, and TNFα in calves inoculated with ΔBacA at all time points. The ΔBacA also gave rise to greater populations of CD4+CD45RO+, and CD8+ cells than uninfected control calves at 16 WPI. Low survival rate of MAP in macrophages co-incubated with PBMCs isolated from the ΔBacA group indicated that these cell populations are capable of killing MAP. Overall, the immune response elicited by ΔBacA is stronger compared to ΔIcL and it is maintained over two different models and over time in calves. Further investigation is warranted to evaluate the BacA mutant's protection against MAP infection as a live attenuated vaccine candidate.

Mouse Models for Mycobacterium tuberculosis Pathogenesis: Show and Do Not Tell

Science has been taking profit from animal models since the first translational experiments back in ancient Greece. From there, and across all history, several remarkable findings have been obtained using animal models. One of the most popular models, especially for research in infectious diseases, is the mouse. Regarding research in tuberculosis, the mouse has provided useful information about host and bacterial traits related to susceptibility to the infection. The effect of aging, sexual dimorphisms, the route of infection, genetic differences between mice lineages and unbalanced immunity scenarios upon Mycobacterium tuberculosis infection and tuberculosis development has helped, helps and will help biomedical researchers in the design of new tools for diagnosis, treatment and prevention of tuberculosis, despite various discrepancies and the lack of deep study in some areas of these traits.

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.

Mice with lung airway ciliopathy develop persistent Mycobacterium abscessus lung infection and have a proinflammatory lung phenotype associated with decreased T regulatory cells

Introduction

Human pulmonary infection with non-tuberculous mycobacteria (NTM) such as Mycobacterium abscessus (Mabs) occurs in seemingly immunocompetent patients with underlying structural lung disease such as bronchiectasis in which normal ciliary function is perturbed. In addition to alterations in mucociliary clearance, the local immunologic milieu may be altered in patients with structural lung disease, but the nature of these changes and how they relate to NTM persistence remain unclear.

Methods

We used a mouse strain containing a conditional floxed allele of the gene IFT88, which encodes for the protein Polaris. Deletion of this gene in adult mice reportedly leads to loss of cilia on lung airway epithelium and to the development of bronchiectasis. In a series of experiments, IFT88 control mice and IFT88 KO mice received different preparations of Mabs lung inocula with lung CFU assessed out to approximately 8 weeks post-infection. In addition, cytokine levels in bronchoalveolar lavage (BAL) fluid, lung T cell subset analysis, and lung histopathology and morphometry were performed at various time points.

Results

Mabs embedded in agarose beads persisted in the lungs of IFT88 KO mice out to approximately 8 weeks (54 days), while Mabs agarose beads in the lungs of IFT88 control mice was cleared from the lungs of all mice at this time point. T cells subset analysis showed a decrease in the percentage of CD4⁺FoxP3⁺ T cells in the total lymphocyte population in the lungs of IFT88 KO mice relative to IFT88 control mice. Proinflammatory cytokines were elevated in the BAL fluid from infected IFT88 KO mice compared to infected IFT88 control mice, and histopathology showed an increased inflammatory response and greater numbers of granulomas in the lungs of infected IFT88 KO mice compared to the lungs of infected IFT88 control mice. Scanning lung morphometry did not show a significant difference comparing lung airway area and lung airway perimeter between IFT88 KO mice and IFT88 control mice.

Discussion

Persistent lung infection in our model was established using Mabs embedded in agarose beads. The utility of using IFT88 mice is that a significant difference in Mabs lung CFU is observed comparing IFT88 KO mice to IFT88 control mice thus allowing for studies assessing the mechanism(s) of Mabs lung persistence. Our finding of minimal differences in lung airway area and lung airway diameter comparing IFT88 KO mice to IFT88 control mice suggests that the development of a proinflammatory lung phenotype in IFT88 KO mice contributes to Mabs lung persistence independent of bronchiectasis. The contribution of cilia to immune regulation is increasingly recognized, and our results suggest that ciliopathy associated with structural lung disease may play a role in NTM pulmonary infection via alteration of the local immunologic lung milieu.

Dynamics of Mycobacterium tuberculosis-Specific and Nonspecific Immune Responses in Women with Tuberculosis Infection during Pregnancy

The immune control of tuberculosis (TB) infection could be influenced by pregnancy. To elucidate this, we longitudinally characterized Mycobacterium tuberculosis (Mtb)-specific and nonspecific immune responses in women during pregnancy and postpartum. HIV-uninfected women without past or current active TB, and with blood samples available from the 1st/2nd trimester, 3rd trimester, and 9 months postpartum, were identified at Ethiopian antenatal care clinics. Twenty-two TB+ women and 10 TB- women, defined according to Mtb-stimulated interferon-γ levels (≥0.35 and <0.20 IU/mL, respectively, in the Quantiferon-TB Gold-Plus assay), were included in the study. Longitudinal dynamics of six cytokines (IL-1ra, IL-2, IP-10, MCP-2, MCP-3, and TGF-β1) were analyzed in supernatants from Mtb-stimulated and unstimulated whole blood. In TB+ women, Mtb-specific expression of IL-2 and IP-10 was higher at 3rd compared to 1st/2nd trimester (median 139 pg/mL versus 62 pg/mL, P = 0.006; 4,999 pg/mL versus 2,310 pg/mL, P = 0.031, respectively), whereas level of Mtb-triggered TGF-β1 was lower at 3rd compared to 1st/2nd trimester (-6.8 ng/mL versus 2.3 ng/mL, P = 0.020). Unstimulated IL-2, IP-10, and MCP-2 levels were increased postpartum, compared with those noted during pregnancy, in TB+ women. Additionally, postpartum levels of proinflammatory cytokines in unstimulated blood were higher in TB+ women, than in TB- women. None of the women developed active TB during follow-up. Taken together, dynamic changes of Mtb-specific cytokine expression revealed during the 3rd trimester in TB+ women indicate increased Mtb-antigen stimulation at later stages of pregnancy. This could reflect elevated bacterial activity, albeit without transition to active TB, during pregnancy. IMPORTANCE Tuberculosis (TB) is globally one of the most common causes of death, and a quarter of the world's population is estimated to have TB infection. The risk of active TB is increased in connection to pregnancy, a phenomenon that could be due to physiological immune changes. Here, we studied the effect of pregnancy on immune responses triggered in HIV-uninfected women with TB infection, by analyzing blood samples obtained longitudinally during pregnancy and after childbirth. We found that the dynamics of Mtb-specific and nonspecific immune responses changed during pregnancy, especially in later stages of pregnancy, although none of the women followed in this study developed active TB. This suggests that incipient TB, with elevated bacterial activity, occurs during pregnancy, but progression of infection appears to be counteracted by Mtb-specific immune responses. Thus, this study sheds light on immune control of TB during pregnancy, which could be of importance for future intervention strategies.

Comparative evaluation of interleukin-10, transforming growth factor-β, and interleukin-17 in gastrointestinal tuberculosis and crohn's disease

Background

Gastrointestinal tuberculosis (GITB) and Crohn's disease (CD) are close mimickers and difficult to discriminate. Recent work has focused on the immunological differences between GITB and CD based on cytokines related to T-regulatory cells and Th17 cells. In the present cross-sectional study, suspected cases of GITB or CD underwent extensive clinical, radiological, endoscopic, histological, and microbiological assessment. The diagnosis was based on standard criteria and response to antitubercular therapy endoscopically.

Methods

Interleukin (IL)-10, transforming growth factor-β (TGF-β), and IL-17 were measured and compared between GITB and CD along with other parameters. Fisher's exact test and Mann-Whitney U test were used as per the data type.

Results

Of the 27 patients, 11 had CD, 9 had GITB, and 7 had other conditions. Chronic diarrhea, involvement of left and long segments of the colon, and aphthous ulcers were significantly more frequent in CD; however, transverse ulcers were in GITB. IL-10 was reduced in both GITB (median-interquartile range [IQR] 9.54 [3.65-24.04]) and CD (median-IQR 13.28 [6.91-22.50]) compared to control (median-IQR 26.72 [10.34-35.43]). TGF-β showed little variation, but IL-17 was below the detection limit in most cases. None of these cytokines were significantly different between CD and GITB. The sensitivity and specificity of multiplex Mycobacterium tuberculosis-polymerase chain reaction were 44.44% and 100%, respectively.

Conclusion

Serum cytokine profiling (IL-10, IL-17, and TGF-β) could not significantly differentiate GITB and CD. Moreover, extensive molecular, transcriptomic, chemokines, and cytokine analyses may shed light on these aspects.

Myeloid-derived suppressor cells and vaccination against pathogens

It is widely accepted that the immune system includes molecular and cellular components that play a role in regulating and suppressing the effector immune response in almost any process in which the immune system is involved. Myeloid-derived suppressor cells (MDSCs) are described as a heterogeneous population of myeloid origin, immature state, with a strong capacity to suppress T cells and other immune populations. Although the initial characterization of these cells was strongly associated with pathological conditions such as cancer and then with chronic and acute infections, extensive evidence supports that MDSCs are also involved in physiological/non-pathological settings, including pregnancy, neonatal period, aging, and vaccination. Vaccination is one of the greatest public health achievements and has reduced mortality and morbidity caused by many pathogens. The primary goal of prophylactic vaccination is to induce protection against a potential pathogen by mimicking, at least in a part, the events that take place during its natural interaction with the host. This strategy allows the immune system to prepare humoral and cellular effector components to cope with the real infection. This approach has been successful in developing vaccines against many pathogens. However, when the infectious agents can evade and subvert the host immune system, inducing cells with regulatory/suppressive capacity, the development of vaccines may not be straightforward. Notably, there is a long list of complex pathogens that can expand MDSCs, for which a vaccine is still not available. Moreover, vaccination against numerous bacteria, viruses, parasites, and fungi has also been shown to cause MDSC expansion. Increases are not due to a particular adjuvant or immunization route; indeed, numerous adjuvants and immunization routes have been reported to cause an accumulation of this immunosuppressive population. Most of the reports describe that, according to their suppressive nature, MDSCs may limit vaccine efficacy. Taking into account the accumulated evidence supporting the involvement of MDSCs in vaccination, this review aims to compile the studies that highlight the role of MDSCs during the assessment of vaccines against pathogens.

Interleukin 32 as a Potential Marker for Diagnosis of Tuberculous Pleural Effusion

Accurate differential diagnosis is the key to choosing the correct treatment for pleural effusion. The present study aimed to assess whether interleukin 32 (IL-32) could be a new biomarker of tuberculous pleural effusion (TPE) and to explore the biological role of IL-32 in TPE. IL-32 levels were evaluated in the pleural effusions of 131 patients with undetermined pleural effusion from Wuhan and Beijing cohorts using an enzyme-linked immunosorbent assay method. Macrophages from TPE patients were transfected with IL-32-specific small interfering RNA (siRNA), and adenosine deaminase (ADA) expression was determined by real-time PCR and colorimetric methods. With a cutoff value of 247.9 ng/mL, the area under the curve of the receiver operating characteristic (ROC) curve for IL-32 was 0.933 for TPE, and the sensitivity and specificity were 88.4% and 93.4%, respectively. A multivariate logistic regression model with relatively good diagnostic performance was established. IL-32-specific siRNA downregulated ADA expression in macrophages, and IL-32γ treatment significantly induced ADA expression. Our results indicate that IL-32 in pleural effusion may be a novel biomarker for identifying patients with TPE. In addition, our multivariate model is acceptable to rule in or rule out TPE across diverse prevalence settings. Furthermore, IL-32 may modulate ADA expression in the tuberculosis microenvironment. (This study has been registered at ChiCTR under registration number ChiCTR2100051112 [https://www.chictr.org.cn/index.aspx].) IMPORTANCE Tuberculous pleural effusion (TPE) is a common form of extrapulmonary tuberculosis, with manifestations ranging from benign effusion with spontaneous absorption to effusion with pleural thickening, empyema, and even fibrosis, which can lead to a lasting impairment of lung function. Therefore, it is of great significance to find a rapid method to establish early diagnosis and apply antituberculosis therapy in the early stage. This study indicates that interleukin 32 (IL-32) in pleural effusion is a new high-potency marker to distinguish TPE from pleural effusions with other etiologies. A multivariate model combining age, adenosine deaminase (ADA), lactic dehydrogenase, and IL-32 may reliably rule in TPE in intermediate- or high-prevalence areas. Additionally, we observed that IL-32 might regulate ADA expression in macrophages in the tuberculosis microenvironment. Therefore, this study provides new insights into the role of IL-32 in the tuberculosis microenvironment.

Clinical Significance of Negative Costimulatory Molecule PD-1/PD-L1 on Peripheral Blood Regulatory T Cell Levels among Patients with Pulmonary Tuberculosis

Objective. This study aimed to investigate the expression and clinical significance of negative costimulatory molecules programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) on CD4+CD25+CD127low regulatory T cells (Tregs) in peripheral blood of patients with active pulmonary tuberculosis (TB). Methods. A total of 30 patients with active pulmonary TB and 20 healthy controls were enrolled. The proportions of peripheral blood CD4+CD25+CD127low Tregs and the expression of PD-1 and PD-L1 on CD4+CD25+CD127low Tregs were detected among active pulmonary TB patients using flow cytometry. The associations of proportions of CD4+CD25+CD127low Tregs with the demographic and clinical characteristics of active pulmonary TB patients were evaluated, and the correlation between PD-1/PD-L1 expression and proportions of peripheral blood CD4+CD25+CD127low Tregs was examined among patients with active pulmonary TB using Pearson correlation analysis. Results. Flow cytometry detected a significantly higher proportion of peripheral blood CD4+CD25+CD127low Tregs in the TB group than in the control group (9.14% ± 2.66% vs. 6.39% ± 1.73%; t = 4.067, $P<0.001$ ), and a higher proportion of peripheral blood CD4+CD25+CD127low Tregs among active pulmonary TB patients with a positive anti-M. tuberculosis antibody than in those with a negative antibody (Figure 2(a)); however, there were no gender, M. tuberculosis culture, tuberculin test, CT examination, or sputum smear test-specific proportions of CD4+CD25+CD127low Tregs among patients with active pulmonary TB. The PD-1 (6.13% ± 3.53% vs. 24.78% ± 7.73%, $P<0.05$ ) and PD-L1 levels (2.97% ± 2.00% vs. 9.23% ± 5.76%, $P<0.05$ ) were lower on peripheral blood CD4+CD25+CD127low Tregs among the TB group than in the control group. In addition, Pearson correlation analysis revealed a positive correlation between PD-1 and PD-L1 expression on peripheral blood CD4+CD25+CD127low Tregs among patients with active pulmonary TB (r = 0.435, $P=0.016$ ) and a negative correlation between the proportion of peripheral blood CD4+CD25+CD127low Tregs and PD-1 (r = ‒0.344, $P=0.024$ ) and PD-L1 expression among patients with active pulmonary TB (r = ‒0.310, $P=0.043$ ). Conclusion. The proportion of CD4+CD25+CD127low Tregs is higher in patients with active pulmonary TB than in healthy controls, and the negative costimulatory signal PD-1/PD-L1 expression is downregulated among active pulmonary TB patients. Our findings provide insights into the illustration of pathogenic mechanisms and immunotherapy of active pulmonary TB.

Distribution and clinical significance of circulating CD8+CD28- regulatory T cells in the peripheral blood of patients with pulmonary tuberculosis

Background

Regulatory T cells (Treg cells) in the peripheral blood of patients with pulmonary tuberculosis (PTB) may be closely related to the progression of PTB. In this study, the distribution characteristics and clinical importance of CD8⁺CD28⁻ Treg cells in patients with tuberculosis were systematically analyzed, and the role and importance of CD8⁺CD28⁻ Treg cells in influencing the immune response and progression of tuberculosis were discussed, which will provide immunological indices and reference values for the clinical diagnosis of tuberculosis.

Methods

Flow cytometry, sputum smears and computed tomography imaging were used to analyze the distribution characteristics of CD8⁺CD28⁻ Treg cells in the peripheral blood of patients with PTB and the correlation between CD8⁺CD28⁻Treg cells and clinical and immune indices.

Results

The percentages of CD4⁺CD25^high and CD8⁺CD28⁻ Treg cells in the peripheral blood of patients with PTB were significantly higher than those in the healthy control (HC) group. Further analysis showed that the percentage of CD4⁺CD25^highTreg cells in the Stage II group was significantly higher than that in the HC group. The percentages of CD4⁺CD25^high and CD8⁺CD28⁻ Treg cells increased significantly in patients in the Stage II group. The proportion of CD8⁺CD28⁻ Treg cells was directly proportional to the degree of positivity in sputum smears, while CD4⁺CD25^highTreg cells did not exhibit this trend.

The correlations between the percentage of CD4⁺CD25^high and CD8⁺CD28⁻ Treg cells and the percentage of lymphocyte subsets were examined. The percentage of CD8⁺CD28⁻ Treg cells was negatively correlated with the percentage of CD4⁺T cells and positively correlated with the CD8⁺T cell percentage in the HC and PTB groups. The percentage of CD4 + CD25^highTreg cells was positively correlated with the percentage of CD4⁺T cells only in the PTB group.

Conclusions

This study was the first to show that the proportion of CD8⁺CD28⁻ Treg cells in the peripheral blood of patients with PTB was significantly increased, and the increase in CD8⁺CD28⁻ Treg cells was related to the progression of PTB, which may affect the proportion of immune cell subsets by inhibiting the immune response, resulting in the progression of PTB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02088-7.

Mycobacterium intracellulare induces a Th17 immune response via M1-like macrophage polarization in canine peripheral blood mononuclear cells

Mycobacterium avium-intracellulare complex (MAC) is one of the most prevalent pathogenic nontuberculous mycobacteria that cause chronic pulmonary disease. The prevalence of MAC infection has been rising globally in a wide range of hosts, including companion animals. MAC infection has been reported in dogs; however, little is known about interaction between MAC and dogs, especially in immune response. In this study, we investigated the host immune response driven by M. intracellulare using the co-culture system of canine T helper cells and autologous monocyte-derived macrophages (MDMs). Transcriptomic analysis revealed that canine MDMs differentiated into M1-like macrophages after M. intracellulare infection and the macrophages secreted molecules that induced Th1/Th17 cell polarization. Furthermore, canine lymphocytes co-cultured with M. intracellulare-infected macrophages induced the adaptive Th17 responses after 5 days. Taken together, our results indicate that M. intracellulare elicits a Th17 response through macrophage activation in this system. Those findings might help the understanding of the canine immune response to MAC infection and diminishing the potential zoonotic risk in One Health aspect.

Concurrent Tuberculous Meningoencephalitis and Anti-NMDAR Encephalitis: A Case Report

Background

Cases of tuberculosis triggering the development of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis are absent.

Case Presentation

Herein, we report, for the first time, the case of a patient who developed anti-NMDAR encephalitis likely due to tuberculosis. The patient, a 33-year-old man, experienced weight loss during the previous 2 years, along with acute headache, fever, cognitive deficits, and right ophthalmoplegia. Based on these findings and on data from magnetic resonance imaging and cerebrospinal fluid antibody analysis, tuberculous meningoencephalitis combined with anti-NMDAR encephalitis was diagnosed. Marked clinical and brain imaging improvement were observed after antituberculosis and high-dose corticosteroid treatment initiation, which persisted during the 3 months of follow-up.

Conclusions

This case suggests that anti-NMDAR encephalitis may arise after tuberculosis infection. Therefore, clinicians must be aware of this possibility, especially when cognitive and new neurological symptoms suddenly occur.

Adjunctive Zoledronate+IL-2 administrations enhance anti-tuberculosis Vγ2Vδ2 T-effector populations, and improve treatment outcome of multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is a refractory disease with high mortality rate due to no or few choices of antibiotics. Adjunctive immunotherapy may help improve treatment outcome of MDR-TB. Our decade-long studies demonstrated that phosphoantigen-specific Vγ2Vδ2 T cells play protective roles in immunity against TB. Here, we hypothesized that enhancing protective Vγ2Vδ2 T-effector cells could improve treatment outcome of MDR-TB. To address this, we employed clinically approved drugs Zoledronate (ZOL) and IL-2 to induce anti-TB Vγ2Vδ2 T-effector cells as adjunctive immunotherapy against MDR-TB infection of macaques. We found that adjunctive ZOL/IL-2 administrations during TB drugs treatment of MDR-TB-infected macaques significantly expanded Vγ2Vδ2 T cells and enhanced/sustained Vγ2Vδ2 T-effector subpopulation producing anti-TB cytokines until week 21. ZOL/IL-2 administrations, while expanding Vγ2Vδ2 T cells, significantly increased/sustained numbers of circulating CD4⁺ Th1 and CD8⁺ Th1-like effector populations, with some γδ T- or αβ T-effector populations trafficking to airway at week 3 until week 19 or 21 after MDR-TB infection. Adjunctive ZOL/IL-2 administrations after MDR-TB infection led to lower bacterial burdens in lungs than TB drugs alone, IL-2 alone or saline controls, and resulted in milder MDR-TB pathology/lesions. Thus, adjunctive Zoledronate + IL-2 administrations can enhance anti-TB Vγ2Vδ2 T- and αβ T-effector populations, and improve treatment outcome of MDR-TB.

M, Saurabh A, Zarin S, Mitra DK, Hasnain SE, Ehtesham NZ. Mycobacterium tuberculosis Methyltransferase Rv1515c Can Suppress Host Defense Mechanisms by Modulating Immune Functions Utilizing a Multipronged Mechanism

Mycobacterium tuberculosis (M. tb) gene Rv1515c encodes a conserved hypothetical protein exclusively present within organisms of MTB complex and absent in non-pathogenic mycobacteria. In silico analysis revealed that Rv1515c contain S-adenosylmethionine binding site and methyltransferase domain. The DNA binding and DNA methyltransferase activity of Rv1515c was confirmed in vitro. Knock-in of Rv1515c in a model mycobacteria M. smegmatis (M. s_Rv1515c) resulted in remarkable physiological and morphological changes and conferred the recombinant strain with an ability to adapt to various stress conditions, including resistance to TB drugs. M. s_Rv1515c was phagocytosed at a greater rate and displayed extended intra-macrophage survival in vitro. Recombinant M. s_Rv1515c contributed to enhanced virulence by suppressing the host defense mechanisms including RNS and ROS production, and apoptotic clearance. M. s_Rv1515c, while suppressing the phagolysosomal maturation, modulated pro-inflammatory cytokine production and also inhibited antigen presentation by downregulating the expression of MHC-I/MHC-II and co-stimulatory signals CD80 and CD86. Mice infected with M. s_Rv1515c produced more Treg cells than vector control (M. s_Vc) and exhibited reduced effector T cell responses, along-with reduced expression of macrophage activation markers in the chronic phase of infection. M. s_Rv1515c was able to survive in the major organs of mice up to 7 weeks post-infection. These results indicate a crucial role of Rv1515c in M. tb pathogenesis.

Immunotherapeutic Effects of Different Doses of Mycobacterium tuberculosis ag85a/b DNA Vaccine Delivered by Electroporation

Background

Tuberculosis (TB) is a major global public health problem. New treatment methods on TB are urgently demanded.

Methods

Ninety-six female BALB/c mice were challenged with 2×10⁴ colony-forming units (CFUs) of MTB H₃₇Rv through tail vein injection, then was treated with 10μg, 50μg, 100μg, and 200μg of Mycobacterium tuberculosis (MTB) ag85a/b chimeric DNA vaccine delivered by intramuscular injection (IM) and electroporation (EP), respectively. The immunotherapeutic effects were evaluated immunologically, bacteriologically, and pathologically.

Results

Compared with the phosphate-buffered saline (PBS) group, the CD4⁺IFN-γ⁺ T cells% in whole blood from 200 µg DNA IM group and four DNA EP groups increased significantly (P<0.05), CD8⁺IFN-γ⁺ T cells% (in 200 μg DNA EP group), CD4⁺IL-4⁺ T cells% (50 μg DNA IM group) and CD8⁺IL-4⁺ T cells% (50 μg and 100 μg DNA IM group, 100 μg and 200 μg DNA EP group) increased significantly only in a few DNA groups (P< 0.05). The CD4⁺CD25⁺ Treg cells% decreased significantly in all DNA vaccine groups (P<0.01). Except for the 10 μg DNA IM group, the lung and spleen colony-forming units (CFUs) of the other seven DNA immunization groups decreased significantly (P<0.001, P<0.01), especially the 100 μg DNA IM group and 50 μg DNA EP group significantly reduced the pulmonary bacterial loads and lung lesions than the other DNA groups.

Conclusions

An MTB ag85a/b chimeric DNA vaccine could induce Th1-type cellular immune reactions. DNA immunization by EP could improve the immunogenicity of the low-dose DNA vaccine, reduce DNA dose, and produce good immunotherapeutic effects on the mouse TB model, to provide the basis for the future human clinical trial of MTB ag85a/b chimeric DNA vaccine.

Ocular mycobacterial lesions in cats

Ocular mycobacterial infections are an under-recognized cause of morbidity in the domestic cat. This study aimed to explore the distribution, histopathological appearance, and severity of feline ocular mycobacterial lesions, and to characterize the immune cell population with immunohistochemistry. Routine histological staining with hematoxylin and eosin, and Masson’s trichrome, was performed to identify ocular lesions and assign an inflammation score based on the number of cells present. Acid-fast bacilli were detected with Ziehl-Neelsen, and immunohistochemistry for ionized calcium-binding adaptor protein-1 (Iba1), calprotectin, cluster of differentiation 3 (CD3), and Pax5 was undertaken on formalin-fixed paraffin-embedded tissue samples from 24 cases of ocular mycobacteriosis. Posterior or panuveitis with concurrent retinitis was identified in 20/24 cases (83%), with retinal detachment in 16/20 (80%) of these cases. Choroidal lesions had the highest median inflammation score. Ziehl-Neelsen-positive organisms were detected in 20/24 cases (83%), with the highest prevalence of acid-fast bacilli detected in choroidal lesions (16/20, 80%). Lesions were typically granulomatous to pyogranulomatous, characterized by abundant numbers of Iba1-positive macrophages, followed by calprotectin-positive granulocytes and monocytes, fewer T cells, and rarer B cells. However, where iritis was identified, inflammation was typically lymphoplasmacytic (11/16 cases, 69%). Where diagnostic testing was performed, tuberculosis (ie, infection with Mycobacterium bovis, Mycobacterium microti, or a nonspeciated Mycobacterium tuberculosis-complex pathogen) was diagnosed in 20/22 cats (91%), with Mycobacterium lepraemurium infection identified in the other 2/22 cats (9%). These results suggest the choroid is the primary site of lesion development in most cases of feline ocular mycobacteriosis, and inflammatory changes are associated with the presence of mycobacteria localized to ocular tissues.

TB and COVID-19: An Exploration of the Characteristics and Resulting Complications of Co-infection

Tuberculosis (TB) and Coronavirus Disease-19 (COVID-19) infection are two respiratory diseases that are of particular concern epidemiologically. Tuberculosis is one of the oldest diseases recorded in the history of mankind dating back thousands of years. It is estimated that approximately one quarter of the world’s population is infected with latent Mycobacterium tuberculosis (LTBI). This contrasts with COVID-19, which emerged in late 2019. Data continues to accumulate and become available on this pathogen, but the long-term side effect of fibrotic damage in COVID-19 patients evokes parallels between this novel coronavirus and its ancient bacterial affiliate. This similarity as well as several others may incite inquiries on whether coinfection of individuals with latent TB and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lead to excessive fibrosis in the lungs and thus the emergence of an active TB infection. While it is well understood how TB leads to structural and immunological lung complications including granuloma formation, fibrosis, and T cell exhaustion, less is known about the disease course when coinfection with SARS-CoV-2 is present. Past and present research demonstrate that IL-10, TNF-α, IFN class I-III, TGF-β, IL-35, and Regulatory T cells (T-regs) are all important contributors of the characteristics of host response to mycobacterium tuberculosis. It has also been noted with current research that IL-10, TNF-α, IFN class I, II, and III, TGF-β, ACE-2, and T-regs are also important contributors to the host response to the SARS-CoV-2 virus in different ways than they are to the TB pathogen. Both pathogens may lead to an unbalanced inflammatory immune response, and together a shared dysregulation of immune response suggests an increased risk of severity and progression of both diseases. We have reviewed 72 different manuscripts between the years 1992 and 2021. The manuscripts pertaining to the SARS-COV-2 virus specifically are from the years 2020 and 2021. Our literature review aims to explore the biomolecular effects of these contributors to pathogenicity of both diseases along with current publications on TB/COVID-19 coinfection, focusing on the pathogenicity of SARS-CoV-2 infection with both latent and active TB, as well as the challenges in treating TB during the COVID-19 pandemic. The compiled material will then aid the latticework foundation of knowledge for future research leading to a hopeful improved system of therapeutic strategies for coinfection.

Dynamics of Macrophage, T and B Cell Infiltration Within Pulmonary Granulomas Induced by Mycobacterium tuberculosis in Two Non-Human Primate Models of Aerosol Infection

Non-human primate models of Tuberculosis (TB) are one of the most commonly used within the experimental TB field because they closely mimic the whole spectrum of disease progression of human TB. However, the early cellular interactions of the pulmonary granuloma are still not well understood. The use of this model allows investigation into the early interactions of cells within pulmonary granulomas which cannot be undertaken in human samples. Pulmonary granulomas from rhesus and cynomolgus macaques from two timepoints post infection were categorised into categories 1 – 6 (early to late stage granulomas) and immunohistochemistry was used to identify CD68+ macrophages, CD3+ T cells and CD20+ B cells. Multinucleated giant cells and acid-fast bacilli were also quantified. At week four post infection, cynomolgus macaques were found to have more CD68+ cells than rhesus in all but category 1 granulomas. Cynomolgus also had a significantly higher percentage of CD20+ B cells in category 1 granulomas. At week twelve post infection, CD68+ cells were most abundant in category 4 and 5 granulomas in both species; however, there were no significant differences between them. CD3+ T cells and CD20+ B cells were significantly higher in the majority of granuloma categories in cynomolgus compared to rhesus. Multinucleated giant cells and acid-fast bacilli were most abundant in categories 5 and 6 at week 12 post challenge in both species. This study has identified the basic cellular composition and spatial distribution of immune cells within pulmonary granulomas in both rhesus and cynomolgus macaques over time. The data from this study will add to the knowledge already gained in this field and may inform future research on vaccines and therapeutics for TB.

Tuberculosis-Specific Antigen/Phytohemagglutinin Ratio Combined With GeneXpert MTB/RIF for Early Diagnosis of Spinal Tuberculosis: A Prospective Cohort Study

Spinal tuberculosis (TB), the most common form of musculoskeletal tuberculosis, is an infection-related disease globally, with paraplegia occurring in severe cases. Therefore, identification of spinal TB at an early stage is important for early intervention and eventual therapy. In this study, we conducted a prospective cohort study in routine clinical practice to investigate the diagnosis of different TB tests. A total of 519 patients were recruited based on the radiology of spinal TB. The diagnostic model was computed by regression analysis and was determined by receiver operating characteristic (ROC) curve analysis. Specificity, sensitivity, predictive value, likelihood ratio, and accuracy were also computed and compared. GeneXpert MTB/RIF showed a higher positive rate compared to that in the acid-fast bacilli smear and Mycobacterium culture. The results also showed that the Mycobacterium tuberculosis-specific antigen/phytohemagglutinin ratio in the T-SPOT assay had a good performance in the preoperative diagnosis and prediction of spinal TB. The diagnostic model based on the ratio of tuberculosis-specific antigen/phytohemagglutinin combined with GeneXpert MTB/RIF showed better efficiency for spinal TB diagnosis. In summary, the tuberculosis-specific antigen/phytohemagglutinin ratio combined with GeneXpert MTB/RIF could provide an early diagnosis of spinal TB.

The Involvement of Mycobacterium Type III-A CRISPR-Cas System in Oxidative Stress

Type I and type II CRISPR-Cas systems are employed to evade host immunity by targeting interference of bacteria’s own genes. Although Mycobacterium tuberculosis (M. tuberculosis), the causative agent of tuberculosis, possesses integrated type III-A CRISPR-Cas system, its role in mycobacteria remains obscure. Here, we observed that seven cas genes (csm2∼5, cas10, cas6) were upregulated in Mycobacterium bovis BCG under oxidative stress treatment, indicating the role of type III-A CRISPR-Cas system in oxidative stress. To explore the functional role of type III-A CRISPR-Cas system, TCC (Type III-A CRISPR-Cas system, including cas6, cas10, and csm2-6) mutant was generated. Deletion of TCC results in increased sensitivity in response to hydrogen peroxide and reduced cell envelope integrity. Analysis of RNA-seq dataset revealed that TCC impacted on the oxidation-reduction process and the composition of cell wall which is essential for mycobacterial envelop integrity. Moreover, disrupting TCC led to poor intracellular survival in vivo and in vitro. Finally, we showed for the first time that TCC contributed to the regulation of regulatory T cell population, supporting a role of TCC in modulating host immunity. Our finding reveals the important role of TCC in cell envelop homeostasis. Our work also highlights type III-A CRISPR-Cas system as an important factor for intracellular survival and host immunoregulation in mycobacteria, thus may be a potential target for therapy.

Changes of Host Immunity Mediated by IFN-γ+ CD8+ T Cells in Children with Adenovirus Pneumonia in Different Severity of Illness

The host immunity of patients with adenovirus pneumonia in different severity of illness is unclear. This study compared the routine laboratory tests and the host immunity of human adenovirus (HAdV) patients with different severity of illness. A co-cultured cell model in vitro was established to verify the T cell response in vitro. Among 140 patients with confirmed HAdV of varying severity, the number of lymphocytes in the severe patients was significantly reduced to 1.91 × 10⁹/L compared with the healthy control (3.92 × 10⁹/L) and the mild patients (4.27 × 10⁹/L). The levels of IL-6, IL-10, and IFN-γ in patients with adenovirus pneumonia were significantly elevated with the severity of the disease. Compared with the healthy control (20.82%) and the stable patients (33.96%), the percentage of CD8⁺ T cells that produced IFN-γ increased to 56.27% in the progressing patients. Adenovirus infection increased the percentage of CD8⁺ T and CD4⁺ T cells that produce IFN-γ in the co-culture system. The hyperfunction of IFN-γ⁺ CD8⁺ T cells might be related to the severity of adenovirus infection. The in vitro co-culture cell model could also provide a usable cellular model for subsequent experiments.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Dysregulated expression of microRNAs in aqueous humor from intraocular tuberculosis patients

BACKGROUND

Systemic Mycobacterium tuberculosis (Mtb) infection alters microRNA's expression that controls cellular processes and modulates host defense mechanisms. However, the role of miRNAs in intraocular tuberculosis (IOTB) remains unknown. Therefore, this study aims to identify dysregulated miRNAs in the aqueous humor (AH) of patients with IOTB.

METHODS

AH from intraocular tuberculosis patients (n = 2) and cataract controls (n = 2) were used for small RNA deep sequencing using HiSeq Illumina sequencing platform. Differentially expressed miRNAs and their targets were identified by the bioinformatics approach, and their regulatory functions were predicted by pathway enrichment analysis. The expression of selected miRNAs and their binding targets were further validated by real-time quantitative PCR (RT-qPCR).

RESULTS

In total, we identified 56 differentially expressed miRNAs in the AH of intraocular tuberculosis (IOTB) patients compared to controls. We selected four significantly dysregulated miRNAs (miR-423-5p, miR-328-3p, miR-21-5p, and miR-16-5p) based on the RT-qPCR validation and predicted their gene targets. We developed a miRNA-targets regulatory network by combining pathways of interest and genes associated with TB. We identified that these four miRNAs might play an important role in IOTB pathogenesis via tuberculosis-associated pathways; PI3K-Akt signaling, autophagy and MAPK pathway.

CONCLUSIONS

For the first time, this study identifies the dysregulation of four miRNAs in the AH of IOTB patients using the ultra-low input small-RNA sequencing approach. Further target prediction and validation identify the role of these miRNAs in tuberculosis pathogenesis via tuberculosis-related pathways. This study identifies miRNAs as potentially ideal biomarkers in the aqueous humor of IOTB patients.

Differential effects of asymptomatic Ascaris lumbricoides, Schistosoma mansoni or hook worm infection on the frequency and TGF-beta-producing capacity of regulatory T cells during active tuberculosis

Helminth induced expansion of regulatory T cells (Tregs) may take part in suppressing protective host responses during tuberculosis (TB), although Tregs functionality and link to TB disease severity remains unexplored. We investigated the species-specific effect of helminths on frequency and TGF-β producing capacity of Tregs, and possible connection to TB disease severity. 89 pulmonary TB patients (PTB) and 69 community controls (CCs) from Gondar, Ethiopia, were included. Clinical disease severity was graded by TB score, and flow cytometry used to characterize Treg frequency and functionality measured as their TGF-β-producing capacity. In helminth positive PTB patients (Helminth+PTB+) compared to helminth negative PTB or CCs, TGF-β⁺ Tregs were significantly increased mainly in hookworm coinfection whereas S. mansoni increased TGF-β⁺ Tregs in CCs. Treatment of TB and helminths decreased TGF-β⁺ Tregs in Helminth+PTB+ at 2 months follow-up. There were no overall differences in the frequency of Tregs in CCs or PTB unless stratification on TB disease severity was performed. At inclusion Helminth+PTB+ had increased frequency of Tregs already at low disease severity, and TGF-β⁺ Tregs correlated to intermediate-to-high disease severity. In conclusion, helminth specific increase of TGF-β⁺ Tregs in PTB patients was correlated to TB disease severity and was restored following anti-helminth treatment.

Retinoic acid induces antimicrobial peptides and cytokines leading to Mycobacterium tuberculosis elimination in airway epithelial cells

Tuberculosis (TB) is the leading cause of death by a single infectious agent, Mycobacterium tuberculosis (Mtb). Alveolar macrophages and respiratory epithelial cells are the first cells exposed to Mtb during the primary infection, once these cells are activated, secrete cytokines and antimicrobial peptides that are associated with the Mtb contention and elimination. Vitamins are micronutrients that function as boosters on the innate immune system, however, is unclear whether they have any protective activity during Mtb infection. Thus, we investigated the role of vitamin A (retinoic acid), vitamin C (ascorbic acid), vitamin D (calcitriol), and vitamin E (alfa-tocopherol) as inductors of molecules related to mycobacterial infection in macrophages and epithelial cells. Our results showed that retinoic acid promotes the expression of pro- and anti-inflammatory molecules such as Thymic stromal lymphopoietin (TSLP), β-defensin-2, IL-1β, CCL20, β-defensin-3, Cathelicidin LL-37, TGF-β, and RNase 7, whereas calcitriol, ascorbic acid, and α-tocopherol lead to an anti-inflammatory response. Treatment of Mtb-infected epithelial cells and macrophage-like cells with the vitamins showed a differential response, where calcitriol reduced Mtb in macrophages, while retinoic acid reduced infection in epithelial cells. Thereby, we propose that a combination of calcitriol and retinoic acid supplementation can drive the immune response, and promotes the Mtb elimination by increasing the expression of antimicrobial peptides and cytokines, while simultaneously modulating inflammation.

BCG therapy is associated with long-term, durable induction of Treg signature genes by epigenetic modulation

Induction of immunosuppressive T-regulatory cells (Tregs) is a desirable goal in autoimmunity, and perhaps other immune diseases of activation. One promising avenue is with the bacille-calmette-guérin (BCG) vaccine in autoimmune type 1 diabetes (T1D). Its administration is associated with gradual clinical improvements in human autoimmunity over a 2-3 year post-vaccination period. We hypothesize that those improvements, and their unusually long time course to fully materialize, are partially attributable to BCG's induction of Tregs. Here we report on a 3 year-long longitudinal cohort of T1Ds and examine the mechanism by which Treg induction occurs. Using the Human Infinium Methylation EPIC Bead Chip, we show that BCG vaccination is associated with gradual demethylation of most of 11 signature genes expressed in highly potent Tregs: Foxp3, TNFRSF18, CD25, IKZF2, IKZF4, CTLA4, TNFR2, CD62L, Fas, CD45 and IL2; nine of these 11 genes, by year 3, became demethylated at the majority of CpG sites. The Foxp3 gene was studied in depth. At baseline Foxp3 was over-methylated compared to non-diabetic controls; 3 years after introduction of BCG, 17 of the Foxp3 gene's 22 CpG sites became significantly demethylated including the critical TSDR region. Corresponding mRNA, Treg expansion and clinical improvement supported the significance of the epigenetic DNA changes. Taken together, the findings suggest that BCG has systemic impact on the T cells of the adaptive immune system, and restores immune balance through Treg induction.