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.
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.
Recent evidence suggests that certain vaccines, including Bacillus-Calmette Guérin (BCG), can induce changes in the innate immune system with non-specific memory characteristics, termed 'trained ...immunity'. Here we present the results of a randomised, controlled phase 1 clinical trial in 20 healthy male and female volunteers to evaluate the induction of immunity and protective efficacy of the anti-tuberculosis BCG vaccine against a controlled human malaria infection. After malaria challenge infection, BCG vaccinated volunteers present with earlier and more severe clinical adverse events, and have significantly earlier expression of NK cell activation markers and a trend towards earlier phenotypic monocyte activation. Furthermore, parasitemia in BCG vaccinated volunteers is inversely correlated with increased phenotypic NK cell and monocyte activation. The combined data demonstrate that BCG vaccination alters the clinical and immunological response to malaria, and form an impetus to further explore its potential in strategies for clinical malaria vaccine development.
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.
Summary
Toll‐like receptor 10 (TLR10) is the only member of the human Toll‐like receptor family with an inhibitory function on the induction of innate immune responses and inflammation. However, its ...role in the modulation of trained immunity (innate immune memory) is unknown. In the present study, we assessed whether TLR10 modulates the induction of trained immunity induced by β‐glucan or bacillus Calmette–Guérin (BCG). Interleukin 10 receptor antagonist production was increased upon activation of TLR10 ex vivo after BCG vaccination, and TLR10 protein expression on monocytes was increased after BCG vaccination, whereas anti‐TLR10 antibodies did not significantly modulate β‐glucan or BCG‐induced trained immunity in vitro. A known immunomodulatory TLR10 missense single‐nucleotide polymorphism (rs11096957) influenced trained immunity responses by β‐glucan or BCG in vitro. However, the in vivo induction of trained immunity by BCG vaccination was not influenced by TLR10 polymorphisms. In conclusion, TLR10 has a limited, non‐essential impact on the induction of trained immunity in humans.
Upon induction of trained immunity by bacillus Calmette–Guérin (BCG) vaccination, Toll‐like receptor 10 (TLR10) protein expression on monocytes was increased, and interleukin‐10 receptor antagonist production was increased upon activation of TLR10 ex vivo, whereas anti‐TLR10 antibodies did not significantly modulate β‐glucan or BCG‐induced trained immunity in vitro. A known immunomodulatory TLR10 missense single‐nucleotide polymorphism influenced trained immunity responses by β‐glucan or BCG in vitro. However, the in vivo induction of trained immunity by BCG vaccination was not influenced by TLR10 polymorphisms, showing that TLR10 has a limited, non‐essential impact on the induction of trained immunity in humans.
Innate immune cells are able to build memory characteristics via a process termed “trained immunity.” Host factors that influence the magnitude of the individual trained immunity response remain ...largely unknown. Using an integrative genomics approach, our study aimed to prioritize and understand the role of specific genes in trained immunity responses. In vitro‐induced trained immunity responses were assessed in two independent population‐based cohorts of healthy individuals, the 300 Bacillus Calmette‐Guérin (300BCG; n = 267) and 200 Functional Genomics (200FG; n = 110) cohorts from the Human Functional Genomics Project. Genetic loci that influence cytokine responses upon trained immunity were identified by conducting a meta‐analysis of QTLs identified in the 300BCG and 200FG cohorts. From the identified QTL loci, we functionally validated the role of PI3K‐Akt signaling pathway and two genes that belong to the family of Siglec receptors (Siglec‐5 and Siglec‐14). Furthermore, we identified the H3K9 histone demethylases of the KDM4 family as major regulators of trained immunity responses. These data pinpoint an important role of metabolic and epigenetic processes in the regulation of trained immunity responses, and these findings may open new avenues for vaccine design and therapeutic interventions.
Using an immunogenomics approach, we identify genetic factors explaining interindividual variation in in vitro‐induced trained immunity responses. We highlight novel factors controlling trained immunity, including the KDM4 family of histone demethylases. These findings shed light on mechanisms underlying trained immunity and offer novel avenues for the design of therapeutics.
The Bacillus Calmette-Guérin (BCG) vaccine is administered at birth in tuberculosis (TB) endemic countries. BCG vaccination is also associated with protective non-specific effects against ...non-tuberculous infections. This seems at least in part mediated through induction of innate immune memory in myeloid cells, a process termed trained immunity. β-glucan, a component of the fungal cell wall from Candida albicans, induces a trained immunity phenotype in human monocytes with hyper-responsiveness against unrelated pathogens. We aimed to study the capacity of BCG and β-glucan to induce a similar phenotype by examining cytokine production in cord blood monocytes following re-stimulation. We used a well-known model of in vitro induction of trained immunity. Adherent mononuclear cells from neonates and adults, which consist mainly of monocytes, were stimulated in vitro with BCG or β-glucan for one day, after which the stimulus was washed away. Cells were rested for 5 days, then restimulated with LPS. Cytokine levels were measured using ELISA. Neonate and adult monocytes responded similarly in terms of cytokine production. BCG significantly increased IL-6 responses to LPS in both neonate and adult monocytes, while β-glucan induced increases of IL-6, IL-10 and TNF production capacity. The BCG and β-glucan induced increase in cytokine production, reminiscent of trained immunity, showed similar levelsin neonatal and adult monocytes. BCG mediated changes in cytokine production shows the feasibility of this in vitro assay for further studies regarding non-specific effects of vaccines.
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.
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.
Stimulation of monocytes with microbial and non-microbial products, including oxidized low-density lipoprotein (oxLDL), induces a protracted pro-inflammatory, atherogenic phenotype sustained by ...metabolic and epigenetic reprogramming via a process called
trained immunity
. We investigated the intracellular metabolic mechanisms driving oxLDL-induced trained immunity in human primary monocytes and observed concomitant upregulation of glycolytic activity and oxygen consumption. In two separate cohorts of healthy volunteers, we assessed the impact of genetic variation in glycolytic genes on the training capacity of monocytes and found that variants mapped to glycolytic enzymes
PFKFB3
and
PFKP
influenced trained immunity by oxLDL. Subsequent functional validation with inhibitors of glycolytic metabolism revealed dose-dependent inhibition of trained immunity in vitro. Furthermore, in vivo administration of the glucose metabolism modulator metformin abrogated the ability for human monocytes to mount a trained response to oxLDL. These findings underscore the importance of cellular metabolism for oxLDL-induced trained immunity and highlight potential immunomodulatory strategies for clinical management of atherosclerosis.
Key messages
Brief stimulation of monocytes to oxLDL induces a prolonged inflammatory phenotype.
This is due to upregulation of glycolytic metabolism.
Genetic variation in glycolytic genes modulates oxLDL-induced trained immunity.
Pharmacological inhibition of glycolysis prevents trained immunity.
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