BACKGROUNDInduction of innate immune memory, also termed trained immunity, by the antituberculosis vaccine bacillus Calmette-Guérin (BCG) contributes to protection against heterologous infections. ...However, the overall impact of BCG vaccination on the inflammatory status of an individual is not known; while induction of trained immunity may suggest increased inflammation, BCG vaccination has been epidemiologically associated with a reduced incidence of inflammatory and allergic diseases.METHODSWe investigated the impact of BCG (BCG-Bulgaria, InterVax) vaccination on systemic inflammation in a cohort of 303 healthy volunteers, as well as the effect of the inflammatory status on the response to vaccination. A targeted proteome platform was used to measure circulating inflammatory proteins before and after BCG vaccination, while ex vivo Mycobacterium tuberculosis- and Staphylococcus aureus-induced cytokine responses in peripheral blood mononuclear cells were used to assess trained immunity.RESULTSWhile BCG vaccination enhanced cytokine responses to restimulation, it reduced systemic inflammation. This effect was validated in 3 smaller cohorts, and was much stronger in men than in women. In addition, baseline circulating inflammatory markers were associated with ex vivo cytokine responses (trained immunity) after BCG vaccination.CONCLUSIONThe capacity of BCG to enhance microbial responsiveness while dampening systemic inflammation should be further explored for potential therapeutic applications.FUNDINGNetherlands Organization for Scientific Research, European Research Council, and the Danish National Research Foundation.
The antituberculosis vaccine Bacillus Calmette–Guérin (BCG) induces nonspecific protection against heterologous infections, at least partly through induction of innate immune memory (trained ...immunity). The amplitude of the response to BCG is variable, but the factors that influence this response are poorly understood. Metabolites, either released by cells or absorbed from the gut, are known to influence immune responses, but whether they impact BCG responses is not known. We vaccinated 325 healthy individuals with BCG, and collected blood before, 2 weeks and 3 months after vaccination, to assess the influence of circulating metabolites on the immune responses induced by BCG. Circulating metabolite concentrations after BCG vaccination were found to have a more pronounced impact on trained immunity responses, such as the increase in IL-1β and TNF-α production upon
Staphylococcus aureus
stimulation, than on specific adaptive immune memory, assessed as IFN-γ production in response to
Mycobacterium tuberculosis
. Circulating metabolites at baseline were able to predict trained immunity responses at 3 months after vaccination and enrichment analysis based on the metabolites positively associated with trained immunity revealed enrichment of the tricarboxylic acid (TCA) cycle and glutamine metabolism, both of which were previously found to be important for trained immunity. Several new metabolic pathways that influence trained immunity were identified, among which taurine metabolism associated with BCG-induced trained immunity, a finding validated in functional experiments. In conclusion, circulating metabolites are important factors influencing BCG-induced trained immunity in humans. Modulation of metabolic pathways may be a novel strategy to improve vaccine and trained immunity responses.
Background
Understanding the complex orchestrated inflammation in atopic dermatitis (AD), one of the most common chronic inflammatory diseases worldwide, is essential for therapeutic approaches. ...However, a comparative analysis on the single‐cell level of the inflammation signatures correlated with the severity is missing so far.
Methods
We applied single‐cell RNA and T‐cell receptor (TCR) sequencing on immune cells enriched from skin biopsies and matched blood samples of AD in comparison with psoriasis (PS) patients.
Results
Clonally propagated skin‐derived T cells showed disease‐specific TCR motifs shared between patients which was more pronounced in PS compared to AD. The disease‐specific T‐cell clusters were mostly of a Th2/Th22 sub‐population in AD and Th17/Tc17 in PS, and their numbers were associated with severity scores in both diseases. Herein, we provide for the first time a list that associates cell type‐specific gene expression with the severity of the two most common chronic inflammatory skin diseases. Investigating the cell signatures in the patients´ PBMCs and skin stromal cells, a systemic involvement of type‐3 inflammation was clearly detectable in PS circulating cells, while in AD inflammatory signatures were most pronounced in fibroblasts, pericytes, and keratinocytes. Compositional and functional analyses of myeloid cells revealed the activation of antiviral responses in macrophages in association with disease severity in both diseases.
Conclusion
Different disease‐driving cell types and subtypes which contribute to the hallmarks of type‐2 and type‐3 inflammatory signatures and are associated with disease activities could be identified by single‐cell RNA‐seq and TCR‐seq in AD and PS.
We applied single‐cell RNA and TCR sequencing on immune‐cells enriched from skin biopsies and matched blood samples of atopic dermatitis and psoriasis patients. We uncovered disease specific Th2/Th22 and Th17/Tc17 sub‐populations in atopic dermatitis and psoriasis, respectively, and associated their numbers with severity scores in both diseases. The disease specific signatures contributed to the hallmarks of type‐2 and type‐3 inflammatory signatures and were associated with disease activitiesAbbreviations: DC, dendritic cell; TCR, T‐cell receptor; Th, T‐helper cell; Tc17, T‐cytotoxic 17 cell
Abstract
Background
Metformin, the most widely administered diabetes drug, has been proposed as a candidate adjunctive host-directed therapy for tuberculosis, but little is known about its effects on ...human host responses to Mycobacterium tuberculosis.
Methods
We investigated in vitro and in vivo effects of metformin in humans.
Results
Metformin added to peripheral blood mononuclear cells from healthy volunteers enhanced in vitro cellular metabolism while inhibiting the mammalian target of rapamycin targets p70S6K and 4EBP1, with decreased cytokine production and cellular proliferation and increased phagocytosis activity. Metformin administered to healthy human volunteers led to significant downregulation of genes involved in oxidative phosphorylation, mammalian target of rapamycin signaling, and type I interferon response pathways, particularly following stimulation with M. tuberculosis, and upregulation of genes involved in phagocytosis and reactive oxygen species production was increased. These in vivo effects were accompanied by a metformin-induced shift in myeloid cells from classical to nonclassical monocytes. At a functional level, metformin lowered ex vivo production of tumor necrosis factor α, interferon γ, and interleukin 1β but increased phagocytosis activity and reactive oxygen species production.
Conclusion
Metformin has a range of potentially beneficial effects on cellular metabolism, immune function, and gene transcription involved in innate host responses to M. tuberculosis.
Metformin has shown beneficial effects in a murine model of tuberculosis. Using in-vitro and in-vivo studies we show that metformin has beneficial effects on cellular metabolism, immune function and genetranscription involved in innate host responses to M. tuberculosis in humans.
The bacillus Calmette-Guérin (BCG) vaccine protects against tuberculosis and heterologous infections but elicits high inter-individual variation in specific and nonspecific, or trained, immune ...responses. While the gut microbiome is increasingly recognized as an important modulator of vaccine responses and immunity in general, its potential role in BCG-induced protection is largely unknown.
Stool and blood were collected from 321 healthy adults before BCG vaccination, followed by blood sampling after 2 weeks and 3 months. Metagenomics based on de novo genome assembly reveals 43 immunomodulatory taxa. The nonspecific, trained immune response is detected by altered production of cytokines IL-6, IL-1β, and TNF-α upon ex vivo blood restimulation with Staphylococcus aureus and negatively correlates with abundance of Roseburia. The specific response, measured by IFN-γ production upon Mycobacterium tuberculosis stimulation, is associated positively with Ruminococcus and Eggerthella lenta. The identified immunomodulatory taxa also have the strongest effects on circulating metabolites, with Roseburia affecting phenylalanine metabolism. This is corroborated by abundances of relevant enzymes, suggesting alternate phenylalanine metabolism modules are activated in a Roseburia species-dependent manner.
Variability in cytokine production after BCG vaccination is associated with the abundance of microbial genomes, which in turn affect or produce metabolites in circulation. Roseburia is found to alter both trained immune responses and phenylalanine metabolism, revealing microbes and microbial products that may alter BCG-induced immunity. Together, our findings contribute to the understanding of specific and trained immune responses after BCG vaccination.
Induction of trained immunity by Bacille-Calmette-Guérin (BCG) vaccination mediates beneficial heterologous effects, but the mechanisms underlying its persistence and magnitude remain elusive. In ...this study, we show that BCG vaccination in healthy human volunteers induces a persistent transcriptional program connected to myeloid cell development and function within the hematopoietic stem and progenitor cell (HSPC) compartment in the bone marrow. We identify hepatic nuclear factor (HNF) family members 1a and b as crucial regulators of this transcriptional shift. These findings are corroborated by higher granulocyte numbers in BCG-vaccinated infants, HNF1 SNP variants that correlate with trained immunity, and elevated serum concentrations of the HNF1 target alpha-1 antitrypsin. Additionally, transcriptomic HSPC remodeling was epigenetically conveyed to peripheral CD14+ monocytes, displaying an activated transcriptional signature three months after BCG vaccination. Taken together, transcriptomic, epigenomic, and functional reprogramming of HSPCs and peripheral monocytes is a hallmark of BCG-induced trained immunity in humans.
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•Human BCG vaccination induces a persistent innate immune training of CD14+ monocytes•BCG vaccination imprints a persistent transcriptomic myeloid bias on human HSPCs•Hepatic nuclear factors are regulators of BCG-induced trained immunity in HSPCs•BCG induces persistent epigenetic changes in peripheral CD14+ monocytes
Cirovic and de Bree et al. investigate the effects of BCG vaccination in humans and reveal the induction of a transcriptomic rewiring of human stem and progenitor cells toward the myeloid cell lineage, instructed by hepatic nuclear factors, resulting in epigenetic and functional changes within CD14+ peripheral monocytes.
Non-specific protective effects of certain vaccines have been reported, and long-term boosting of innate immunity, termed trained immunity, has been proposed as one of the mechanisms mediating these ...effects. Several epidemiological studies suggested cross-protection between influenza vaccination and COVID-19. In a large academic Dutch hospital, we found that SARS-CoV-2 infection was less common among employees who had received a previous influenza vaccination: relative risk reductions of 37% and 49% were observed following influenza vaccination during the first and second COVID-19 waves, respectively. The quadrivalent inactivated influenza vaccine induced a trained immunity program that boosted innate immune responses against various viral stimuli and fine-tuned the anti-SARS-CoV-2 response, which may result in better protection against COVID-19. Influenza vaccination led to transcriptional reprogramming of monocytes and reduced systemic inflammation. These epidemiological and immunological data argue for potential benefits of influenza vaccination against COVID-19, and future randomized trials are warranted to test this possibility.
BACKGROUNDThe antituberculosis vaccine bacillus Calmette-Guérin (BCG) reduces overall infant mortality. Induction of innate immune memory, also termed trained immunity, contributes toward protection ...against heterologous infections. Since immune cells display oscillations in numbers and function throughout the day, we investigated the effect of BCG administration time on the induction of trained immunity.METHODSEighteen volunteers were vaccinated with BCG at 6 pm and compared with 36 age- and sex-matched volunteers vaccinated between 8 am and 9 am. Peripheral blood mononuclear cells were stimulated with Staphylococcus aureus and Mycobacterium tuberculosis before, as well as 2 weeks and 3 months after, BCG vaccination. Cytokine production was measured to assess the induction of trained immunity and adaptive responses, respectively. Additionally, the influence of vaccination time on induction of trained immunity was studied in an independent cohort of 302 individuals vaccinated between 8 am and 12 pm with BCG.RESULTSCompared with evening vaccination, morning vaccination elicited both a stronger trained immunity and adaptive immune phenotype. In a large cohort of 302 volunteers, early morning vaccination resulted in a superior cytokine production capacity compared with later morning. A cellular, rather than soluble, substrate of the circadian effect of BCG vaccination was demonstrated by the enhanced capacity to induce trained immunity in vitro in morning- compared with evening-isolated monocytes.CONCLUSIONSBCG vaccination in the morning induces stronger trained immunity and adaptive responses compared with evening vaccination. Future studies should take vaccine administration time into account when studying specific and nonspecific effects of vaccines; early morning should be the preferred moment of BCG administration.FUNDINGThe Netherlands Organization for Scientific Research, the European Research Council, and the Danish National Research Foundation.
Summary
The tuberculosis (TB) vaccine Bacillus Calmette‐Guérin (BCG) was introduced 100 years ago, but as it provides insufficient protection against TB disease, especially in adults, new vaccines ...are being developed and evaluated. The discovery that BCG protects humans from becoming infected with Mycobacterium tuberculosis (Mtb) and not just from progressing to TB disease provides justification for considering Mtb infection as an endpoint in vaccine trials. Such trials would require fewer participants than those with disease as an endpoint. In this review, we first define Mtb infection and disease phenotypes that can be used for mechanistic studies and/or endpoints for vaccine trials. Secondly, we review the evidence for BCG‐induced protection against Mtb infection from observational and BCG re‐vaccination studies, and discuss limitations and variation of this protection. Thirdly, we review possible underlying mechanisms for BCG efficacy against Mtb infection, including alternative T cell responses, antibody‐mediated protection, and innate immune mechanisms, with a specific focus on BCG‐induced trained immunity, which involves epigenetic and metabolic reprogramming of innate immune cells. Finally, we discuss the implications for further studies of BCG efficacy against Mtb infection, including for mechanistic research, and their relevance to the design and evaluation of new TB vaccines.
The tuberculosis vaccine bacillus Calmette-Guérin (BCG) protects against some heterologous infections, probably via induction of non-specific innate immune memory in monocytes and natural killer (NK) ...cells, a process known as trained immunity. Recent studies have revealed that the induction of trained immunity is associated with a bias toward granulopoiesis in bone marrow hematopoietic progenitor cells, but it is unknown whether BCG vaccination also leads to functional reprogramming of mature neutrophils. Here, we show that BCG vaccination of healthy humans induces long-lasting changes in neutrophil phenotype, characterized by increased expression of activation markers and antimicrobial function. The enhanced function of human neutrophils persists for at least 3 months after vaccination and is associated with genome-wide epigenetic modifications in trimethylation at histone 3 lysine 4. Functional reprogramming of neutrophils by the induction of trained immunity might offer novel therapeutic strategies in clinical conditions that could benefit from modulation of neutrophil effector function.
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•BCG vaccination of humans induces long-term immunophenotypic changes in neutrophils•BCG increases antimicrobial activity of neutrophils against unrelated pathogens•BCG-induced functional changes associate with modifications in histone methylation•Trained immunity may be a therapeutic target in neutrophil-mediated diseases
Moorlag et al. show that BCG vaccination induces long-lasting functional changes in human neutrophils, characterized by increased expression of activation markers and enhanced antimicrobial function upon secondary stimulation. These findings highlight the potential of trained immunity as a therapeutic target to modulate neutrophil effector function.
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