Leishmania braziliensis enhances monocyte responses to promote anti-tumor activity

Innate immune cells can undergo long-term functional reprogramming after certain infections, a process called trained immunity (TI). Here, we focus on antigens of Leishmania braziliensis, which induced anti-tumor effects via trained immunity in human monocytes. We reveal that monocytes exposed to promastigote antigens of L. braziliensis develop an enhanced response to subsequent exposure to Toll-like receptor (TLR)2 or TLR4 ligands. Mechanistically, the induction of TI in monocytes by L. braziliensis is mediated by multiple pattern recognition receptors, changes in metabolism, and increased deposition of H3K4me3 at the promoter regions of immune genes. The administration of L. braziliensis exerts potent anti-tumor capabilities by delaying tumor growth and prolonging survival of mice with non-Hodgkin lymphoma. Our work reveals mechanisms of TI induced by L. braziliensis in vitro and identifies its potential for cancer immunotherapy.

Corticosteroid-induced chromatin loop dynamics at the FKBP5 gene

FKBP5 is a 115-kb-long glucocorticoid-inducible gene implicated in psychiatric disorders. To investigate the complexities of chromatin interaction frequencies at the FKBP5 topologically associated domain (TAD), we deployed 15 one-to-all chromatin capture viewpoints near gene promoters, enhancers, introns, and CTCF-loop anchors. This revealed a "one-TAD-one-gene" structure encompassing the FKBP5 promoter and its enhancers. The FKBP5 promoter and its two glucocorticoid-stimulated enhancers roam the entire TAD while displaying subtle cell type-specific interactomes. The FKBP5 TAD consists of two nested CTCF loops that are coordinated by one CTCF site in the eighth intron of FKBP5 and another beyond its polyadenylation site, 61 kb further. Loop extension correlates with transcription increases through the intronic CTCF site. This is efficiently compensated for, since the short loop is restored even under high transcription regimes. The boundaries of the FKBP5 TAD consist of divergent CTCF site patterns, harbor multiple smaller genes, and are resilient to glucocorticoid stimulation. Interestingly, both FKBP5 TAD boundaries harbor H3K27me3-marked heterochromatin blocks that may reinforce them. We propose that cis-acting genetic and epigenetic polymorphisms underlying FKBP5 expression variation are likely to reside within a 240-kb region that consists of the FKBP5 TAD, its left sub-TAD, and both its boundaries.

The decylTPP mitochondria-targeting moiety lowers electron transport chain supercomplex levels in primary human skin fibroblasts

Attachment of cargo molecules to lipophilic triphenylphosphonium (TPP⁺) cations is a widely applied strategy for mitochondrial targeting. We previously demonstrated that the vitamin E-derived antioxidant Trolox increases the levels of active mitochondrial complex I (CI), the first complex of the electron transport chain (ETC), in primary human skin fibroblasts (PHSFs) of Leigh Syndrome (LS) patients with isolated CI deficiency. Primed by this finding, we here studied the cellular effects of mitochondria-targeted Trolox (MitoE10), mitochondria-targeted ubiquinone (MitoQ10) and their mitochondria-targeting moiety decylTPP (C₁₀-TPP⁺). Chronic treatment (96 h) with these molecules of PHSFs from a healthy subject and an LS patient with isolated CI deficiency (NDUFS7-V122M mutation) did not greatly affect cell number. Unexpectedly, this treatment reduced CI levels/activity, lowered the amount of ETC supercomplexes, inhibited mitochondrial oxygen consumption, increased extracellular acidification, altered mitochondrial morphology and stimulated hydroethidine oxidation. We conclude that the mitochondria-targeting decylTPP moiety is responsible for the observed effects and advocate that every study employing alkylTPP-mediated mitochondrial targeting should routinely include control experiments with the corresponding alkylTPP moiety.

An integrative genomics approach identifies KDM4 as a modulator of trained immunity

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.

The role of sirtuin 1 on the induction of trained immunity

Sirtuin 1 (SIRT1) has been described to modify immune responses by modulation of gene transcription. As transcriptional reprogramming is the molecular substrate of trained immunity, a de facto innate immune memory, we investigated the role of SIRT1 in the induction of trained immunity. We identified various SIRT1 genetic single nucleotide polymorphisms affecting innate and adaptive cytokine production of human peripheral blood mononuclear cells (PBMCs) in response to various stimuli on the one hand, and in vitro induction of trained immunity on the other hand. Furthermore, inhibition of SIRT1 upregulated pro-inflammatory innate cytokine production upon stimulation of PBMCs. However, inhibition of SIRT1 in vitro had no effect on cytokine responses upon induction of trained immunity, while activation of SIRT1 mildly modified trained immunity responses. In conclusion, SIRT1 modifies innate cytokine production by PBMCs in response to various microbes, but has only a secondary role for BCG and β-glucan-induced trained immunity responses.

The Set7 Lysine Methyltransferase Regulates Plasticity in Oxidative Phosphorylation Necessary for Trained Immunity Induced by β-Glucan

Trained immunity confers a sustained augmented response of innate immune cells to a secondary challenge, via a process dependent on metabolic and transcriptional reprogramming. Because of its previous associations with metabolic and transcriptional memory, as well as the importance of H3 histone lysine 4 monomethylation (H3K4me1) to innate immune memory, we hypothesize that the Set7 methyltransferase has an important role in trained immunity induced by β-glucan. Using pharmacological studies of human primary monocytes, we identify trained immunity-specific immunometabolic pathways regulated by Set7, including a previously unreported H3K4me1-dependent plasticity in the induction of oxidative phosphorylation. Recapitulation of β-glucan training in vivo additionally identifies Set7-dependent changes in gene expression previously associated with the modulation of myelopoiesis progenitors in trained immunity. By revealing Set7 as a key regulator of trained immunity, these findings provide mechanistic insight into sustained metabolic changes and underscore the importance of characterizing regulatory circuits of innate immune memory.

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Set7 regulates enhanced cytokine production in trained immunity in vitro

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Set7 knockout mice are unable to mount trained immunity against endotoxin challenge

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Set7 modulates cellular respiration in β-glucan-trained macrophages

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Set7-dependent histone methylation regulates MDH2 and SDHB in trained cells

Lysine methyltransferase G9a is an important modulator of trained immunity

Objectives

Histone methyltransferase G9a, also known as Euchromatic Histone Lysine Methyltransferase 2 (EHMT2), mediates H3K9 methylation which is associated with transcriptional repression. It possesses immunomodulatory effects and is overexpressed in multiple types of cancer. In this study, we investigated the role of G9a in the induction of trained immunity, a de facto innate immune memory, and its effects in non‐muscle‐invasive bladder cancer (NMIBC) patients treated with intravesical Bacillus Calmette‐Guérin (BCG).

Methods

EHMT2 expression was assessed upon induction of trained immunity by RNA sequencing and Western blotting. G9a inhibitor BIX‐01294 was used to investigate the effect on trained immunity responses in vitro. Subsequent cytokine production was measured by ELISA, epigenetic modifications were measured by ChIP‐qPCR, Seahorse technology was used to measure metabolic changes, and a luminescence assay was used to measure ROS release. RNA sequencing was performed on BIX‐01294‐treated monocytes ex vivo.

Results

The expression of EHMT2 mRNA and protein decreased in monocytes during induction of trained immunity. G9a inhibition by BIX‐01294 induced trained immunity and amplified trained immunity responses evoked by various microbial ligands in vitro. This was accompanied by decreased H3K9me2 at the promoters of pro‐inflammatory genes. G9a inhibition was also associated with amplified ex vivo trained immunity responses in circulating monocytes of NMIBC patients. Additionally, altered RNA expression of inflammatory genes in monocytes of NMIBC patients was observed upon ex vivo G9a inhibition. Furthermore, intravesical BCG therapy decreased H3K9me2 at the promoter of pro‐inflammatory genes.

Conclusion

Inhibition of G9a is important in the induction of trained immunity, and G9a may represent a novel therapeutic target in NMIBC patients.

Comparative host transcriptome in response to pathogenic fungi identifies common and species-specific transcriptional antifungal host response pathways

Candidiasis, aspergillosis, and mucormycosis cause the majority of nosocomial fungal infections in immunocompromised patients. Using an unbiased transcriptional profiling in PBMCs exposed to the fungal species causing these infections, we found a core host response in healthy individuals that may govern effective fungal clearance: it consists of 156 transcripts, involving canonical and non-canonical immune pathways. Systematic investigation of key steps in antifungal host defense revealed fungal-specific signatures. As previously demonstrated, Candida albicans induced type I and Type II interferon-related pathways. In contrast, central pattern recognition receptor, reactive oxygen species production, and host glycolytic pathways were down-regulated in response to Rhizopus oryzae, which was associated with an ER-stress response. TLR5 was identified to be uniquely regulated by Aspergillus fumigatus and to control cytokine release in response to this fungus. In conclusion, our data reveals the transcriptional profiles induced by C. albicans, A. fumigatus, and R. oryzae, and describes both the common and specific antifungal host responses that could be exploited for novel therapeutic strategies.

Reprogramming of bone marrow myeloid progenitor cells in patients with severe coronary artery disease

Atherosclerosis is the major cause of cardiovascular disease (CVD). Monocyte-derived macrophages are the most abundant immune cells in atherosclerotic plaques. In patients with atherosclerotic CVD, leukocytes have a hyperinflammatory phenotype. We hypothesize that immune cell reprogramming in these patients occurs at the level of myeloid progenitors. We included 13 patients with coronary artery disease due to severe atherosclerosis and 13 subjects without atherosclerosis in an exploratory study. Cytokine production capacity after ex vivo stimulation of peripheral blood mononuclear cells (MNCs) and bone marrow MNCs was higher in patients with atherosclerosis. In BM-MNCs this was associated with increased glycolysis and oxidative phosphorylation. The BM composition was skewed towards myelopoiesis and transcriptome analysis of HSC/GMP cell populations revealed enrichment of neutrophil- and monocyte-related pathways. These results show that in patients with atherosclerosis, activation of innate immune cells occurs at the level of myeloid progenitors, which adds exciting opportunities for novel treatment strategies.

Aldosterone induces trained immunity: the role of fatty acid synthesis

AIMS

Supranormal levels of aldosterone are associated with an increased cardiovascular risk in humans, and with accelerated atherosclerosis in animal models. Atherosclerosis is a low-grade inflammatory disorder, with monocyte-derived macrophages as major drivers of plaque formation. Monocytes can adopt a long-term pro-inflammatory phenotype after brief stimulation with microbial pathogens or endogenous atherogenic lipoproteins via a process termed trained immunity. In this study, we aimed to investigate whether aldosterone can induce trained immunity in primary human monocytes in vitro and explored the underlying mechanism.

METHODS AND RESULTS

We exposed human monocytes to aldosterone for 24 h, after which they were rested to differentiate into monocyte-derived macrophages for 5 days, and re-stimulated with toll-like receptor 2 and 4 ligands on day 6. We demonstrated that aldosterone augments pro-inflammatory cytokine production and reactive oxygen species production in monocyte-derived macrophages after re-stimulation, via the mineralocorticoid receptor. Fatty acid synthesis was identified as a crucial pathway necessary for this induction of trained immunity and pharmacological inhibition of this pathway blunted aldosterone-induced trained immunity. At the level of gene regulation, aldosterone promoted enrichment of the transcriptionally permissive H3K4me3 modification at promoters of genes central to the fatty acid synthesis pathway.

CONCLUSION

Aldosterone induces trained immunity in vitro, which is dependent on epigenetically mediated up-regulation of fatty acid synthesis. These data provide mechanistic insight into the contribution of aldosterone to inflammation, atherosclerosis, and cardiovascular disease.

BCG Vaccination in Humans Elicits Trained Immunity via the Hematopoietic Progenitor Compartment

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.

Correction to: Rewiring of glucose metabolism defines trained immunity induced by oxidized low-density lipoprotein

The correct name of the 17th Author is presented in this paper.

Catecholamines Induce Trained Immunity in Monocytes In Vitro and In Vivo

RATIONALE

Exposure to high catecholamine levels is associated with inflammatory changes of myeloid cells and atherosclerosis, but the underlying mechanisms are only partly understood.

OBJECTIVE

To investigate whether the proinflammatory effects of noradrenaline and adrenaline can, in part, be explained by the induction of an immunologic memory in innate immune cells, termed trained immunity.

METHODS AND RESULTS

In vitro, we exposed human primary monocytes to (nor)adrenaline for 24 hours, after which cells were rested and differentiated to macrophages over 5 days. After restimulation with lipopolysaccharide on day 6, (nor)adrenaline-exposed cells showed increased TNF-α (tumor necrosis factor-α) production. This coincided with an increase in glycolysis and oxidative phosphorylation measured with Seahorse technology on day 6 before restimulation. Inhibition of the β-adrenoreceptor-cAMP signaling pathway prevented the induction of training. In vivo, we studied the functional, transcriptional, and epigenetic impact of peak-wise exposure to high catecholamine levels on monocytes isolated from pheochromocytoma/paraganglioma (PHEO) patients. In PHEO patients (n=10), the peripheral blood cell composition showed a myeloid bias and an increase of the inflammatory CD14++CD16+ (cluster of differentiation) intermediate monocyte subset compared with controls with essential hypertension (n=14). Ex vivo production of proinflammatory cytokines was higher in PHEO patients. These inflammatory changes persisted for 4 weeks after surgical removal of PHEO. Transcriptome analysis of circulating monocytes at baseline showed various differentially expressed genes in inflammatory pathways in PHEO patients; epigenetic profiling of the promoters of these genes suggests enrichment of the transcriptionally permissive chromatin mark H3K4me3 (trimethylation of lysine 4 on histone H3), indicative of in vivo training.

CONCLUSIONS

Catecholamines induce long-lasting proinflammatory changes in monocytes in vitro and in vivo, indicating trained immunity. Our data contribute to the understanding of pathways driving inflammatory changes in conditions characterized by high catecholamine levels and propose that trained immunity underlies the increased cardiovascular event rate in PHEO patients.

The role of Toll-like receptor 10 in modulation of trained immunity

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.

OR04-2 Aldosterone Induces Trained Immunity via Fatty Acid Synthesis

Hyperaldosteronism is associated with an increased cardiovascular risk in humans. Animal models show that aldosterone accelerates the development of atherosclerotic plaques, and suggest that this is, at least in part, mediated by activation of innate immune cells by aldosterone (1). Human data are scarce. We recently showed that monocytes can adopt a long-term pro-inflammatory phenotype after brief stimulation, which has been termed ‘trained immunity’ (2). Therefore, we tested the hypothesis that aldosterone induces ‘trained immunity’ by investigating the functional, immunometabolic and epigenetic effects of aldosterone on human monocytes in vitro. Human monocytes were exposed to vehicle, aldosterone (10nM) or serum obtained from patients with primary hyperaldosteronism (PA) with and without addition of a mineralocorticoid receptor (MR) antagonist for 24 hours, and differentiated to macrophages. We assessed the ability of these cells to produce ROS and cytokines upon re-stimulation. Changes in immunometabolism were assessed via extracellular flux measurements with Seahorse XF technology and further explored at the genome level with RNA microarray. Chromatin immunoprecipitation was performed to assess histone modifications in aldosterone-exposed cells. In vitro exposure of human monocytes with both aldosterone and PA serum induced a trained immunity phenotype characterized by augmented IL-6 and TNF-α responses, as well as ROS production to re-stimulation, an effect that was prevented by the MR antagonist spironolactone. Aldosterone-trained cells showed no differences in glycolysis or oxidative phosphorylation compared to vehicle treated cells. Instead, RNA microarray showed upregulation of the fatty acid synthesis (FAS) pathway, which we validated with qPCR. Pharmacological inhibition of FAS abolished the induction of training by aldosterone. Moreover, the aldosterone-trained phenotype was associated with enrichment of the transcriptionally-permissive histone mark H3K4me3, at the level of the promoters of central genes in the fatty acid synthesis pathway. In conclusion, aldosterone induces a form of trained immunity which is dependent on activation of the MR and induction of fatty acid synthesis. This novel pathway of immune activation uncovers potential pharmacological targets for patients with hyperaldosteronism. To translate these findings, we have recruited 15 patients with proven primary hyperaldosteronism and 15 matched patients with essential hypertension and comprehensively assessed systemic inflammation and monocyte phenotype as well as vascular wall inflammation with fluorodeoxyglucose-positron emission tomography. The results of these analyses will be available at the time of ENDO 2019. (1) van der Heijden et al. Cardiovasc Res. 2018 Jun 1;114(7):944-953. (2) Netea et al. Science. 2016 Apr 22;352(6284)

High pneumococcal density correlates with more mucosal inflammation and reduced respiratory syncytial virus disease severity in infants

Background

Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in infants. A small percentage of the infected infants develops a severe infection, while most of these severely ill patients were previously healthy. It remains unclear why these children develop severe RSV infections. In this study, we investigate whether pneumococcal nasopharyngeal carriage patterns correlate with mucosal inflammation and severity of disease.

Methods

In total, 105 infants hospitalized with RSV infection were included and recovery samples were taken from 42 patients. The presence and density of Streptococcus pneumoniae was determined by RT qPCR to study its relation to viral load, inflammation (MMP-9 and IL-6) and severity of RSV disease.

Results

We show that pneumococcal presence or absence in the nasopharynx does not correlate with viral load, inflammation or severity of disease. However, when pneumococcus is present in patients, a higher nasopharyngeal pneumococcal density was correlated with a higher RSV load, higher MMP-9 levels and a less severe course of disease.

Conclusions

Our results show correlations between S. pneumoniae density and viral load, inflammation and disease severity, suggesting that pneumococcal density may be an indicator for severity in paediatric RSV disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1454-x) contains supplementary material, which is available to authorized users.

Glucocorticoid receptor and nuclear factor kappa-b affect three-dimensional chromatin organization

Background

The impact of signal-dependent transcription factors, such as glucocorticoid receptor and nuclear factor kappa-b, on the three-dimensional organization of chromatin remains a topic of discussion. The possible scenarios range from remodeling of higher order chromatin architecture by activated transcription factors to recruitment of activated transcription factors to pre-established long-range interactions.

Results

Using circular chromosome conformation capture coupled with next generation sequencing and high-resolution chromatin interaction analysis by paired-end tag sequencing of P300, we observed agonist-induced changes in long-range chromatin interactions, and uncovered interconnected enhancer–enhancer hubs spanning up to one megabase. The vast majority of activated glucocorticoid receptor and nuclear factor kappa-b appeared to join pre-existing P300 enhancer hubs without affecting the chromatin conformation. In contrast, binding of the activated transcription factors to loci with their consensus response elements led to the increased formation of an active epigenetic state of enhancers and a significant increase in long-range interactions within pre-existing enhancer networks. De novo enhancers or ligand-responsive enhancer hubs preferentially interacted with ligand-induced genes.

Conclusions

We demonstrate that, at a subset of genomic loci, ligand-mediated induction leads to active enhancer formation and an increase in long-range interactions, facilitating efficient regulation of target genes. Therefore, our data suggest an active role of signal-dependent transcription factors in chromatin and long-range interaction remodeling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0832-9) contains supplementary material, which is available to authorized users.

The role of ZmpC in the clinical manifestation of invasive pneumococcal disease

INTRODUCTION

The clinical severity and course of invasive pneumococcal disease (IPD) differs substantially between patients. Streptococcus pneumoniae harbors large genetic variability. Zinc metalloproteinase C (ZmpC), a secreted pneumococcal protein involved in neutrophil extravasation, inflammation and tissue remodeling, is present in a minority of IPD isolates. We investigated whether the presence of zmpC was associated with the clinical manifestation of IPD.

MATERIAL AND METHODS

IPD patients admitted to two Dutch hospitals between 2000 and 2013 were included in the study. Detailed clinical data were collected and the serotype and presence of zmpC were determined in the corresponding blood culture isolates.

RESULTS

ZmpC was present in 21% of the 542 included IPD cases and was mainly associated with serotypes 8, 4, 33A/F and 11A/D. Infection with S. pneumoniae positive for zmpC was more frequently observed in females (p=0.048) and patients with a history of smoking (p=0.033). Although no relation to clinical syndrome was observed, zmpC positive cases more often presented with cough, dyspnea and sepsis (p-values 0.026, 0.001 and 0.018), and more frequently required ICU admission (p=0.011) compared to zmpC negative cases.

CONCLUSION

The presence of zmpC was associated with a more severe clinical manifestation of IPD. This study demonstrates that information on pneumococcal genetic background may be useful to identify vulnerable individuals, to monitor clinical presentation and to predict the course of IPD.

Development of a titanium alloy suitable for an optimized coating with hydroxyapatite

By means of the metallurgical method of alloying, the thermal expansion coefficient of commercially pure titanium was adapted to that of hydroxyapatite (HA) in order to produce a tailored composite material with a maximum adhesion strength of HA to the metallic material. The alloying element chosen was manganese, which is an important trace element in the human organism. With the alloy TiMn6 a good compromise concerning the expansion coefficient, the mechanical properties and the biocompatible behaviour was found. With this alloy coatings with an extremely high adhesion strength could be produced, especially when the sol-gel process was used for HA precipitation. In addition, these layers fulfil the requirements of favourable thin coatings according to theoretical considerations.