BCG-induced trained immunity: history, mechanisms and potential applications

Methylation and transcriptomic profiling reveals short term and long term regulatory responses in polarized macrophages

Macrophage plasticity allows the adoption of distinct functional states in response to environmental cues. While unique transcriptomic profiles define these states, focusing solely on transcription neglects potential long-term effects. The investigation of epigenetic changes can be used to understand how temporary stimuli can result in lasting effects. Epigenetic alterations play an important role in the pathophysiology of macrophages, including their trained innate immunity, enabling faster and more efficient inflammatory responses upon subsequent encounters to the same pathogen or insult. In this study, we used a multi-omics approach to elucidate the interplay between gene expression and DNA-methylation, to explore the potential long-term effects of diverse polarizing environments on macrophage activity. We identified a common core set of genes that are differentially methylated regardless of exposure type, indicating a potential common fundamental mechanism for adaptation to various stimuli. Functional analysis revealed that processes requiring rapid responses displayed transcriptomic regulation, whereas functions critical for long-term adaptations exhibited co-regulation at both transcriptomic and epigenetic levels. Our study uncovers a novel set of genes linked to the long-term effects of macrophage polarization. This discovery underscores the potential of epigenetics in elucidating how macrophages establish long-term memory and influence health outcomes.

Early transcriptomic response of innate immune cells to subcutaneous BCG vaccination of mice

OBJECTIVES

Current data suggests that Bacille Calmette-Guerin (BCG) vaccination contributes to nonspecific enhancement of resistance to various infections. Thus, BCG vaccination induces both specific immunity against mycobacteria and non-specific "trained immunity" against various pathogens. To understand the fundamental mechanisms of "trained" immunity, studies of transcriptome changes occurring during BCG vaccination in innate immunity cells, as well as in their precursors, are necessary. Furthermore, this data possesses important significance for practical applications associated with the development of recombinant BCG strains aimed to enhance innate immunity against diverse infectious agents.

DATA DESCRIPTION

We performed RNA sequencing of innate immune cells derived from murine bone marrow and spleen three days after subcutaneous BCG vaccination. Using fluorescence-activated cell sorting we obtained three cell populations for each mouse from both control and BCG vaccinated groups: bone marrow monocytes and neutrophils and splenic NK-cells. Then double-indexed cDNA libraries for Illumina sequencing from the collected samples were prepared, the resulting cDNA library mix was subjected to NovaSeq 6000 sequencing. This paper describes the collection of 24 RNA sequencing samples comprising 4 sets of immune cell populations obtained from subcutaneously BCG-vaccinated and control mice.

Postinfectious Pulmonary Complications: Establishing Research Priorities to Advance the Field: An Official American Thoracic Society Workshop Report

Continued improvements in the treatment of pulmonary infections have paradoxically resulted in a growing challenge of individuals with postinfectious pulmonary complications (PIPCs). PIPCs have been long recognized after tuberculosis, but recent experiences such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic have underscored the importance of PIPCs following other lower respiratory tract infections. Independent of the causative pathogen, most available studies of pulmonary infections focus on short-term outcomes rather than long-term morbidity among survivors. In this document, we establish a conceptual scope for PIPCs with discussion of globally significant pulmonary pathogens and an examination of how these pathogens can damage different components of the lung, resulting in a spectrum of PIPCs. We also review potential mechanisms for the transition from acute infection to PIPC, including the interplay between pathogen-mediated injury and aberrant host responses, which together result in PIPCs. Finally, we identify cross-cutting research priorities for the field to facilitate future studies to establish the incidence of PIPCs, define common mechanisms, identify therapeutic strategies, and ultimately reduce the burden of morbidity in survivors of pulmonary infections.

Epigenetic changes associated with Bacillus Calmette-Guerin (BCG) treatment in bladder cancer

Bacillus Calmette-Guérin (BCG) treatment for non-muscle invasive bladder cancer (NMIBC) is an established immunotherapeutic, however, a significant portion of patients do not respond to treatment. Despite extensive research into the therapeutic mechanism of BCG, gaps remain in our understanding. This review specifically focuses on the epigenomic contributions in the immune microenvironment, in the context of BCG treatment for NMIBC. We also summarise the current understanding of NMIBC epigenetic characteristics, and discuss how future targeted strategies for BCG therapy should incorporate epigenomic biomarkers in conjunction with genomic biomarkers.

Protocol for analyzing BCG-induced trained immunity in murine bone marrow-derived macrophages

Bacillus Calmette-Guérin (BCG), the only licensed tuberculosis vaccine, provides non-specific protection against non-tuberculosis diseases that is mediated by trained immunity, a functional reprogramming mediated by innate immune memory. Here, we present a protocol for analyzing BCG-induced trained immunity in murine bone marrow-derived macrophages (BMDMs). We describe steps for preparing BCG single bacterial suspensions, isolating BMDM cells, and the training process. This protocol can assist researchers to conveniently utilize BMDM cells to study trained immunity. For complete details on the use and execution of this protocol, please refer to Xu et al.1.

Weight loss-induced adipose macrophage memory improves local Staphylococcus aureus clearance in male mice

Different stimuli can induce innate immune memory to improve pathogen defense or worsen cardiometabolic disease. However, it is less clear if the same stimuli can induce both the protective and detrimental effects of innate immune memory. We previously showed that weight loss induces innate immune memory in adipose macrophages that correlates with worsened diabetes risk after weight regain. In this study, we investigated the effect of weight loss on macrophage cytokine production and overall survival in a mouse model of infection. Male C57Bl/6J mice were put on high-fat or low-fat diets over 18 weeks to induce weight gain or weight loss. Lean mice served as controls. All mice were then infected IV with 2.5×10^6 CFU Staphylococcus aureus . Tissues were collected from 10 mice/group at day 3 and the remaining animals were followed for survival. Weight gain mice had the highest blood neutrophils and the highest bacterial burden in the kidney. However, there was no significant difference in survival. The weight loss group had the highest plasma TNF-α and a significant reduction in bacterial burden in the adipose tissue that correlated with increased adipose macrophage cytokine production. Thus, weight loss-induced adipose macrophage memory may both improve local S.aureus clearance and worsen diabetes risk upon weight regain. Collectively, these findings support the notion that innate immune memory is an evolutionarily protective mechanism that also contributes to the development of cardiometabolic diseases.

Macrophage plasticity: signaling pathways, tissue repair, and regeneration

Macrophages are versatile immune cells with remarkable plasticity, enabling them to adapt to diverse tissue microenvironments and perform various functions. Traditionally categorized into classically activated (M1) and alternatively activated (M2) phenotypes, recent advances have revealed a spectrum of macrophage activation states that extend beyond this dichotomy. The complex interplay of signaling pathways, transcriptional regulators, and epigenetic modifications orchestrates macrophage polarization, allowing them to respond to various stimuli dynamically. Here, we provide a comprehensive overview of the signaling cascades governing macrophage plasticity, focusing on the roles of Toll-like receptors, signal transducer and activator of transcription proteins, nuclear receptors, and microRNAs. We also discuss the emerging concepts of macrophage metabolic reprogramming and trained immunity, contributing to their functional adaptability. Macrophage plasticity plays a pivotal role in tissue repair and regeneration, with macrophages coordinating inflammation, angiogenesis, and matrix remodeling to restore tissue homeostasis. By harnessing the potential of macrophage plasticity, novel therapeutic strategies targeting macrophage polarization could be developed for various diseases, including chronic wounds, fibrotic disorders, and inflammatory conditions. Ultimately, a deeper understanding of the molecular mechanisms underpinning macrophage plasticity will pave the way for innovative regenerative medicine and tissue engineering approaches.

Trained immunity inducers in cancer immunotherapy

While most of the cancer immunotherapy strategies engage adaptive immunity, especially tumor-associated T cells, the small fraction of responding patients and types of cancers amenable, and the possibility of severe adverse effects limit its usage. More effective and general interventions are urgently needed. Recently, a de facto innate immune memory, termed 'trained immunity', has become a new research focal point, and promises to be a powerful tool for achieving long-term therapeutic benefits against cancers. Trained immunity-inducing agents such as BCG and fungal glucan have been shown to be able to avert the suppressive tumor microenvironment (TME), enhance T cell responses, and eventually lead to tumor regression. Here, we review the current understating of trained immunity induction and highlight the critical roles of emergency granulopoiesis, interferon γ and tissue-specific induction. Preclinical and clinical studies that have exploited trained immunity inducers for cancer immunotherapy are summarized, and repurposed trained immunity inducers from other fields are proposed. We also outline the challenges and opportunities for trained immunity in future cancer immunotherapies. We envisage that more effective cancer vaccines will combine the induction of trained immunity with T cell therapies.

Atopic dermatitis and food allergy: More than sensitization

The increased risk of food allergy in infants with atopic dermatitis (AD) has long been recognized; an epidemiologic phenomenon termed "the atopic march." Current literature supports the hypothesis that food antigen exposure through the disrupted skin barrier in AD leads to food antigen-specific immunoglobulin E production and food sensitization. However, there is growing evidence that inflammation in the skin drives intestinal remodeling via circulating inflammatory signals, microbiome alterations, metabolites, and the nervous system. We explore how this skin-gut axis helps to explain the link between AD and food allergy beyond sensitization.

Microbial cancer immunotherapy reprograms hematopoietic stem cells to enhance anti-tumor immunity

Mycobacterium bovis BCG is the vaccine against tuberculosis and an immunotherapy for bladder cancer. When administered intravenously, BCG reprograms bone marrow hematopoietic stem and progenitor cells (HSPCs), leading to heterologous protection against infections. Whether HSPC-reprogramming contributes to the anti-tumor effects of BCG administered into the bladder is unknown. We demonstrate that BCG administered in the bladder in both mice and humans reprograms HSPCs to amplify myelopoiesis and functionally enhance myeloid cell antigen presentation pathways. Reconstitution of naive mice with HSPCs from bladder BCG-treated mice enhances anti-tumor immunity and tumor control, increases intratumor dendritic cell infiltration, reprograms pro-tumorigenic neutrophils, and synergizes with checkpoint blockade. We conclude that bladder BCG acts systemically, reprogramming HSPC-encoded innate immunity, highlighting the broad potential of modulating HSPC phenotypes to improve tumor immunity.

Neuropathological lesions in intravenous BCG-stimulated K18-hACE2 mice challenged with SARS-CoV-2

In the wake of the COVID-19 pandemic caused by SARS-CoV-2, questions emerged about the potential effects of Bacillus Calmette-Guérin (BCG) vaccine on the immune response to SARS-CoV-2 infection, including the neurodegenerative diseases it may contribute to. To explore this, an experimental study was carried out in BCG-stimulated and non-stimulated k18-hACE2 mice challenged with SARS-CoV-2. Viral loads in tissues determined by RT-qPCR, histopathology in brain and lungs, immunohistochemical study in brain (IHC) as well as mortality rates, clinical signs and plasma inflammatory and coagulation biomarkers were assessed. Our results showed BCG-SARS-CoV-2 challenged mice presented higher viral loads in the brain and an increased frequency of neuroinvasion, with the greatest differences observed between groups at 3-4 days post-infection (dpi). Histopathological examination showed a higher severity of brain lesions in BCG-SARS-CoV-2 challenged mice, mainly consisting of neuroinflammation, increased glial cell population and neuronal degeneration, from 5 dpi onwards. This group also presented higher interstitial pneumonia and vascular thrombosis in lungs (3-4 dpi), BCG-SARS-CoV-2 mice showed higher values for TNF-α and D-dimer values, while iNOS values were higher in SARS-CoV-2 mice at 3-4 dpi. Results presented in this study indicate that BCG stimulation could have intensified the inflammatory and neurodegenerative lesions promoting virus neuroinvasion and dissemination in this experimental model. Although k18-hACE2 mice show higher hACE2 expression and neurodissemination, this study suggests that, although the benefits of BCG on enhancing heterologous protection against pathogens and tumour cells have been broadly demonstrated, potential adverse outcomes due to the non-specific effects of BCG should be considered.

BCG vaccination and multiple sclerosis risk: A Norwegian cohort study

INTRODUCTION

Bacillus Calmette-Guérin (BCG) vaccination induces long-lasting effects on the adaptive and innate immune systems and prevents development of experimental autoimmune encephalomyelitis and possibly also inflammatory disease activity in multiple sclerosis (MS).

OBJECTIVE

The objective is to examine if BCG given in early adulthood decreases MS risk.

METHODS

From 791,369 (52% females) Norwegians participating in a national tuberculosis screening program from 1963 to 1975, we collected information on BCG vaccination and tuberculosis disease status. Later, MS disease was ascertained through both the Norwegian MS Registry and Biobank and the Norwegian Death Registry. We used logistic regression models to assess the relationship between BCG vaccination and MS risk.

RESULTS

In those BCG vaccinated, mean age at vaccination was 15.6 (standard deviation (SD) = 5.5) years. A total of 2862 (65% females) MS cases were retrieved. Overall, we found no association between MS risk and BCG vaccination. Compared to non-BCG-vaccinated individuals with no signs of tuberculosis infection, odds ratio (OR) for MS was 1.00 (95% confidence interval (CI) = 0.80-1.25) in the BCG-vaccinated group. In those not BCG vaccinated because of latent tuberculosis infection, the corresponding OR was 0.86 (95% CI = 0.66-1.13).

CONCLUSION

We found no evidence of BCG vaccination or latent tuberculosis infection in young adulthood being linked to MS risk.

Endotoxin tolerance and trained immunity: breaking down immunological memory barriers

For decades, innate immune cells were considered unsophisticated first responders, lacking the adaptive memory of their T and B cell counterparts. However, mounting evidence demonstrates the surprising complexity of innate immunity. Beyond quickly deploying specialized cells and initiating inflammation, two fascinating phenomena - endotoxin tolerance (ET) and trained immunity (TI) - have emerged. ET, characterized by reduced inflammatory response upon repeated exposure, protects against excessive inflammation. Conversely, TI leads to an enhanced response after initial priming, allowing the innate system to mount stronger defences against subsequent challenges. Although seemingly distinct, these phenomena may share underlying mechanisms and functional implications, blurring the lines between them. This review will delve into ET and TI, dissecting their similarities, differences, and the remaining questions that warrant further investigation.

Promising Cytokine Adjuvants for Enhancing Tuberculosis Vaccine Immunity

Tuberculosis, caused by Mycobacterium tuberculosis (M. tuberculosis), remains a formidable global health challenge, affecting a substantial portion of the world's population. The current tuberculosis vaccine, bacille Calmette-Guérin (BCG), offers limited protection against pulmonary tuberculosis in adults, underscoring the critical need for innovative vaccination strategies. Cytokines are pivotal in modulating immune responses and have been explored as potential adjuvants to enhance vaccine efficacy. The strategic inclusion of cytokines as adjuvants in tuberculosis vaccines holds significant promise for augmenting vaccine-induced immune responses and strengthening protection against M. tuberculosis. This review delves into promising cytokines, such as Type I interferons (IFNs), Type II IFN, interleukins such as IL-2, IL-7, IL-15, IL-12, and IL-21, alongside the use of a granulocyte-macrophage colony-stimulating factor (GM-CSF) as an adjuvant, which has shown effectiveness in boosting immune responses and enhancing vaccine efficacy in tuberculosis models.

Bacillus Calmette-Guérin (BCG)-Induced Protection in Brain Disorders

The Bacille Calmette-Guerin (BCG) vaccine is one of the most widely used vaccines in the world for the prevention of tuberculosis. Its immunological capacity also includes epigenetic reprogramming, activation of T cells and inflammatory responses. Although the main usage of the vaccine is the prevention of tuberculosis, different works have shown that the effect of BCG can go beyond the peripheral immune response and be linked to the central nervous system by modulating the immune system at the level of the brain. This review therefore aims to describe the BCG vaccine, its origin, its relationship with the immune system, and its involvement at the brain level.

The human MIF polymorphism CATT7 enhances pro-inflammatory macrophage polarization in a clinically relevant model of allergic airway inflammation

High level expression of the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) has been associated with severe asthma. The role of MIF and its functional promotor polymorphism in innate immune training is currently unknown. Using novel humanized CATT7 MIF mice, this study is the first to investigate the effect of MIF on bone marrow-derived macrophage (BMDM) memory after house dust mite (HDM) challenge. CATT7 BMDMs demonstrated a significant primed increase in M1 markers following HDM and LPS stimulation, compared to naive mice. This M1 signature was found to be MIF-dependent, as administration of a small molecule MIF inhibitor, SCD-19, blocked the induction of this pro-inflammatory M1-like phenotype in BMDMs from CATT7 mice challenged with HDM. Training naive BMDMs in vitro with HDM for 24 h followed by a rest period and subsequent stimulation with LPS led to significantly increased production of the pro-inflammatory cytokine TNFα in BMDMs from CATT7 mice but not WT mice. Addition of the pan methyltransferase inhibitor MTA before HDM training significantly abrogated this effect in BMDMs from CATT7 mice, suggesting that HDM-induced training is associated with epigenetic remodelling. These findings suggest that trained immunity induced by HDM is under genetic control, playing an important role in asthma patients with the high MIF genotypes (CATT6/7/8).

Mycobacterium bovis BCG as immunostimulating agent prevents the severe form of chronic experimental Chagas disease

Introduction

There is currently no vaccine against Chagas disease (ChD), and the medications available confer multiple side effects. Mycobacterium bovis Bacillus Calmette-Guérin (BCG) produces balanced Th1, Th2, and Th17 modulatory immune responses and has improved efficacy in controlling chronic infections through nonspecific immunity. We aimed to improve the response to infection by inducing a stronger immune response and greater protection against the parasite by trained immunity.

Methods

BALB/c mice were immunized with BCG subcutaneously, and 60 days later, they were infected with Trypanosoma cruzi intraperitoneally. An evaluation of the progression of the disease from the acute to the chronic stage, analyzing various aspects such as parasitemia, survival, clinical status, and humoral and cellular immune response, as well as the appearance of visceral megas and the histopathological description of target organs, was performed.

Results

Vaccination reduced parasitemia by 70%, and 100% survival was achieved in the acute stage; although the presentation of clinical signs was reduced, there was no increase in the antibody titer or in the differential production of the isotypes.

Conclusion

Serum cytokine production indicated a proinflammatory response in infected animals, while in those who received BCG, the response was balanced by inducing Th1/Th2-type cytokines, with a better prognosis of the disease in the chronic stage.

Heat-killed Mycobacterium tuberculosis induces trained immunity in vitro and in vivo administered systemically or intranasally

Trained immunity (TI) represents a memory-like process of innate immune cells. TI can be initiated with various compounds such as fungal β-glucan or the tuberculosis vaccine, Bacillus Calmette-Guérin. Nevertheless, considering the clinical applications of harnessing TI against infections and cancer, there is a growing need for new, simple, and easy-to-use TI inducers. Here, we demonstrate that heat-killed Mycobacterium tuberculosis (HKMtb) induces TI both in vitro and in vivo. In human monocytes, this effect represents a truly trained process, as HKMtb confers boosted inflammatory responses against various heterologous challenges, such as lipopolysaccharide (Toll-like receptor [TLR] 4 ligand) and R848 (TLR7/8 ligand). Mechanistically, HKMtb-induced TI relies on epigenetic mechanisms in a Syk/HIF-1α-dependent manner. In vivo, HKMtb induced TI when administered both systemically and intranasally, with the latter generating a more robust TI response. Summarizing, our research has demonstrated that HKMtb has the potential to act as a mucosal immunotherapy that can successfully induce trained responses.

Multi-omics analysis of innate and adaptive responses to BCG vaccination reveals epigenetic cell states that predict trained immunity

Immune responses are tightly regulated yet highly variable between individuals. To investigate human population variation of trained immunity, we immunized healthy individuals with Bacillus Calmette-Guérin (BCG). This live-attenuated vaccine induces not only an adaptive immune response against tuberculosis but also triggers innate immune activation and memory that are indicative of trained immunity. We established personal immune profiles and chromatin accessibility maps over a 90-day time course of BCG vaccination in 323 individuals. Our analysis uncovered genetic and epigenetic predictors of baseline immunity and immune response. BCG vaccination enhanced the innate immune response specifically in individuals with a dormant immune state at baseline, rather than providing a general boost of innate immunity. This study advances our understanding of BCG's heterologous immune-stimulatory effects and trained immunity in humans. Furthermore, it highlights the value of epigenetic cell states for connecting immune function with genotype and the environment.

BCG vaccination induces innate immune memory in γδ T cells in humans

Bacillus Calmette-Guérin vaccine is well known for inducing trained immunity in myeloid and natural killer cells, which can explain its cross-protective effect against heterologous infections. Although displaying functional characteristics of both adaptive and innate immunity, γδ T-cell memory has been only addressed in a pathogen-specific context. In this study, we aimed to determine whether human γδ T cells can mount trained immunity and therefore contribute to the cross-protective effect of the Bacillus Calmette-Guérin vaccine. We investigated in vivo induction of innate memory in γδ T cells by Bacillus Calmette-Guérin vaccination in healthy human volunteers by combining single-cell RNA sequencing technology with immune functional assays. The total number of γδ T cells and membrane markers of activation was not influenced by Bacillus Calmette-Guérin vaccination. In contrast, Bacillus Calmette-Guérin changed γδ T cells' transcriptional programs and increased their responsiveness to heterologous bacterial and fungal stimuli, including lipopolysaccharide and Candida albicans, as simultaneously characterized by higher tumor necrosis factor and interferon γ production, weeks after vaccination. Human γδ T cells in adults display the potential to develop a trained immunity phenotype after Bacillus Calmette-Guérin vaccination.

Salmonella enterica and outer membrane vesicles are current and future options for cancer treatment

Conventional cancer therapies have many limitations. In the last decade, it has been suggested that bacteria-mediated immunotherapy may circumvent the restrictions of traditional treatments. For example, Salmonella enterica is the most promising bacteria for treating cancer due to its intrinsic abilities, such as killing tumor cells, targeting, penetrating, and proliferating into the tumor. S. enterica has been genetically modified to ensure safety and increase its intrinsic antitumor efficacy. This bacterium has been used as a vector for delivering anticancer agents and as a combination therapy with chemotherapy, radiotherapy, or photothermic. Recent studies have reported the antitumor efficacy of outer membrane vesicles (OMVs) derived from S. enterica. OMVs are considered safer than attenuated bacteria and can stimulate the immune system as they comprise most of the immunogens found on the surface of their parent bacteria. Furthermore, OMVs can also be used as nanocarriers for antitumor agents. This review describes the advances in S. enterica as immunotherapy against cancer and the mechanisms by which Salmonella fights cancer. We also highlight the use of OMVs as immunotherapy and nanocarriers of anticancer agents. OMVs derived from S. enterica are innovative and promising strategies requiring further investigation.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

Bacterial infection and microbiota in carcinogenesis and tumor development

Microbiota colonize exposed body tissues (e.g., gastrointestinal tract, skin, lungs, female genital tract, and urogenital tracts) and unexposed sites (e.g., breast). Persistent bacterial infection in the host lead to the development of multiple disease. They are implicated in the pathogenesis of various complex diseases, including diabetes, atherosclerosis, autoimmune diseases, Alzheimer's disease, and malignant diseases. Amounting studies have demonstrated the role of bacterial infection in carcinogenesis. The study of microbiota in tumorigenesis is primarily focused on lung cancer, colorectal cancer (CRC), breast cancer, gastric cancer, and gynecologic tumors, and so on. Infection of Helicobacter pylori in gastric cancer carcinogenesis is recognized as class I carcinogen by the World Health Organization (WHO) decades ago. The role of Fusobacterium nucleatum in the development of colorectal cancer is extensively investigated. Variable bacteria have been cultured from the tumor tissues. The identification of microbiota in multiple tumor tissues reveal that bacterial infection and microbiota are associated with tumor development. The microbiota affects multiple aspects of carcinogenesis and tumor development, including favoring epithelial cells proliferation, establishing inflammatory microenvironment, promoting metastasis, and causing resistance to therapy. On the other hand, microbiota can shape a tumor surveillance environment by enhancing cell activity, and sensitize the tumor cells to immune therapy. In the present review, the roles of microbiota in multiple malignancies are summarized, and unraveling the mechanisms of host-microbiota interactions can contribute to a better understanding of the interaction between microbiota and host cells, also the development of potential anti-tumor therapeutic strategies.

Key advances in vaccine development for tuberculosis-success and challenges

Breakthrough findings in the clinical and preclinical development of tuberculosis (TB) vaccines have galvanized the field and suggest, for the first time since the development of bacille Calmette-Guérin (BCG), that a novel and protective TB vaccine is on the horizon. Here we highlight the TB vaccines that are in the development pipeline and review the basis for optimism in both the clinical and preclinical space. We describe immune signatures that could act as immunological correlates of protection (CoP) to facilitate the development and comparison of vaccines. Finally, we discuss new animal models that are expected to more faithfully model the pathology and complex immune responses observed in human populations.

A suspension of inactivated bacteria used for vaccination against recurrent urinary tract infections increases the phagocytic activity of murine macrophages

Background

Urinary tract infections are a major cause of the consumption of antibiotics in humans.

Methods

We studied the effect of a vaccine (StroVac®, containing inactivated bacteria and used to prevent recurrent urinary tract infections) licensed in Germany on the release of pro-inflammatory cytokines and the phagocytosis of Escherichia (E.) coli in primary murine macrophages and the macrophage cell line J774A.1.

Results

StroVac® increased the release of the cytokines TNF-α, IL-6, IL-12/23 p40, and IL-1β and stimulated the phagocytosis of E. coli in a dose-dependent manner. This effect was independent of LPS as shown by the use of macrophages isolated from LPS-resistant C3H/HeJ mice. At concentrations up to 30 mg/l it was not toxic to bacteria or eukaryotic cells.

Conclusion

StroVac® does not only act via the adaptive but also by stimulating the innate immune system. This stimulation may help to build trained innate immunity against bacterial pathogens involved in recurrent urinary tract infections.

Immunological perturbations, psychiatric disorders and associated therapeutics: a new era for psychiatry?

The three main theories explaining major mental illness, namely mood disorders, psychoses and dementias, have been partially discredited. Alongside this, there are emerging links between perturbations of the immune system and the onset and phenotypic features of these disorders. This article outlines the alternative pathophysiology and suggests potential treatments which could improve disease burden and avoid the need for psychotropic medication, with their associated side effects and relapse following withdrawal.

Impact of aging on immunity in the context of COVID-19, HIV, and tuberculosis

Knowledge of aging biology needs to be expanded due to the continuously growing number of elderly people worldwide. Aging induces changes that affect all systems of the body. The risk of cardiovascular disease and cancer increases with age. In particular, the age-induced adaptation of the immune system causes a greater susceptibility to infections and contributes to the inability to control pathogen growth and immune-mediated tissue damage. Since the impact of aging on immune function, is still to be fully elucidated, this review addresses some of the recent understanding of age-related changes affecting key components of immunity. The emphasis is on immunosenescence and inflammaging that are impacted by common infectious diseases that are characterized by a high mortality, and includes COVID-19, HIV and tuberculosis.

Designing Anti-Viral Vaccines that Harness Intrastructural Help from Prior BCG Vaccination

Vaccines are among the most effective tools for combatting the impact and spread of infectious diseases. However, the effectiveness of a vaccine can be diminished by vaccine inequality, particularly during severe outbreaks of infectious diseases in resource-poor areas. As seen in many developing countries that lack adequate healthcare infrastructure and economic resources, the acquisition and distribution of potentially life-saving vaccines may be limited, leading to prolonged suffering and increased deaths. To improve vaccine equity, vaccine design must take into consideration the logistics needed to implement a successful vaccination drive, particularly among the most vulnerable populations. In the manuscript titled "Exploiting Pre-Existing CD4+ T Cell Help from Bacille Calmette-Guérin Vaccination to Improve Antiviral Antibody Responses" published in the Journal of Immunology, the authors designed a recombinant subunit vaccine against the Ebola virus (EBOV) glycoprotein that can harness the pre-existing T helper cells from prior BCG vaccination. As a recombinant subunit vaccine adjuvanted with alum, this approach has many features that make it well suited for the design of vaccines for developing nations, such as relative ease of production, scalability, and distribution. In addition, the high prevalence of BCG immunization and natural immunity to mycobacteria in many regions of the world endow such vaccines with features that should increase potency and efficacy among populations residing in such regions. As a result of using the helper activity of pre-existing BCG-specific Th cells to drive antibody responses, a lower vaccine dose is needed, which is a major advantage for vaccine manufacture. Furthermore, the BCG-specific Th cells also stimulate immunoglobulin class switching to IgG isotypes that have strong affinities for activating Fc-gamma receptors (FcγRs). Taken together, we propose that the design of subunit vaccines with intrastructural help from BCG-specific Th cells can improve protection against viral infection and represents a vaccine design that can be generally adapted to other emerging viral pathogens for the control and prevention of infection in many developing countries.