Cutting edge: changes in histone acetylation at the IL-4 and IFN-gamma loci accompany Th1/Th2 differentiation

Transcriptional re-programming of liver-resident iNKT cells into T-regulatory type-1-like liver iNKT cells involves extensive gene de-methylation

Unlike conventional CD4+ T cells, which are phenotypically and functionally plastic, invariant NKT (iNKT) cells generally exist in a terminally differentiated state. Naïve CD4+ T cells can acquire alternative epigenetic states in response to different cues, but it remains unclear whether peripheral iNKT cells are epigenetically stable or malleable. Repetitive encounters of liver-resident iNKT cells (LiNKTs) with alpha-galactosylceramide (αGalCer)/CD1d-coated nanoparticles (NPs) can trigger their differentiation into a LiNKT cell subset expressing a T regulatory type 1 (TR1)-like (LiNKTR1) transcriptional signature. Here we dissect the epigenetic underpinnings of the LiNKT-LiNKTR1 conversion as compared to those underlying the peptide-major histocompatibility complex (pMHC)-NP-induced T-follicular helper (TFH)-to-TR1 transdifferentiation process. We show that gene upregulation during the LINKT-to-LiNKTR1 cell conversion is associated with demethylation of gene bodies, inter-genic regions, promoters and distal gene regulatory elements, in the absence of major changes in chromatin exposure or deposition of expression-promoting histone marks. In contrast, the naïve CD4+ T cell-to-TFH differentiation process involves extensive remodeling of the chromatin and the acquisition of a broad repertoire of epigenetic modifications that are then largely inherited by TFH cell-derived TR1 cell progeny. These observations indicate that LiNKT cells are epigenetically malleable and particularly susceptible to gene de-methylation.

Comprehensive pan-cancer analysis of inflammatory age-clock-related genes as prognostic and immunity markers based on multi-omics data

Inflammatory age (iAge) is a vital concept for understanding the intricate interplay between chronic inflammation and aging in the context of cancer. However, the importance of iAge-clock-related genes (iAge-CRGs) across cancers remains unexplored. This study aimed to explore the mechanisms and applications of these genes across diverse cancer types. We analyzed profiling data from over 10,000 individuals, covering 33 cancer types, 750 small molecule drugs, and 24 immune cell types. We focused on DCBLD2's function at the single-cell level and computed an iAge-CRG score using GSVA. This score was correlated with cancer pathways, immune infiltration, and survival. A signature was then derived using univariate Cox and LASSO regression, followed by ROC curve analysis, nomogram construction, decision curve analysis, and immunocytochemistry. Our comprehensive analysis revealed epigenetic, genomic, and immunogenomic alterations in iAge-CRGs, especially DCBLD2, leading to abnormal expression. Aberrant DCBLD2 expression strongly correlated with cancer-associated fibroblast infiltration and prognosis in multiple cancers. Based on GSVA results, we developed a risk model using five iAge-CRGs, which proved to be an independent prognostic index for uveal melanoma (UVM) patients. We also systematically evaluated the correlation between the iAge-related signature risk score and immune cell infiltration. iAge-CRGs, particularly DCBLD2, emerge as potential targets for enhancing immunotherapy outcomes. The strong correlation between abnormal DCBLD2 expression, cancer-associated fibroblast infiltration, and patient survival across various cancers underscores their significance. Our five-gene risk signature offers an independent prognostic tool for UVM patients, highlighting the crucial role of these genes in suppressing the immune response in UVM.Kindly check and confirm whether the corresponding affiliation is correctly identified.I identified the affiliation is correctly.thank you.Per style, a structured abstract is not allowed so we have changed the structured abstract to an unstructured abstract. Please check and confirm.I confirm the abstract is correctly ,thank you.

Food Allergy Risk: A Comprehensive Review of Maternal Interventions for Food Allergy Prevention

Food allergy represents a global health problem impacting patients' and caregivers' quality of life and contributing to increased healthcare costs. Efforts to identify preventive measures starting from pregnancy have recently intensified. This review aims to provide an overview of the role of maternal factors in food allergy prevention. Several studies indicate that avoiding food allergens during pregnancy does not reduce the risk of developing food allergies. International guidelines unanimously discourage avoidance diets due to potential adverse effects on essential nutrient intake and overall health for both women and children. Research on probiotics and prebiotics during pregnancy as preventive measures is promising, though evidence remains limited. Consequently, guidelines lack specific recommendations for their use in preventing food allergies. Similarly, given the absence of conclusive evidence, it is not possible to formulate definitive conclusions on the supplementation of vitamins, omega-3 fatty acids (n-3 PUFAs), and other antioxidant substances. A combination of maternal interventions, breastfeeding, and early introduction of foods to infants can reduce the risk of food allergies in the child. Further studies are needed to clarify the interaction between genetics, immunological pathways, and environmental factors.

Epigenetic reprogramming of T cells: unlocking new avenues for cancer immunotherapy

T cells, a key component of cancer immunotherapy, undergo a variety of histone modifications and DNA methylation changes since their bone marrow progenitor stages before developing into CD8+ and CD4+ T cells. These T cell types can be categorized into distinct subtypes based on their functionality and properties, such as cytotoxic T cells (Tc), helper T cells (Th), and regulatory T cells (Treg) as subtypes for CD8+ and CD4+ T cells. Among these, the CD4+ CD25+ Tregs potentially contribute to cancer development and progression by lowering T effector (Teff) cell activity under the influence of the tumor microenvironment (TME). This contributes to the development of therapeutic resistance in patients with cancer. Subsequently, these individuals become resistant to monoclonal antibody therapy as well as clinically established immunotherapies. In this review, we delineate the different epigenetic mechanisms in cancer immune response and its involvement in therapeutic resistance. Furthermore, the possibility of epi-immunotherapeutic methods based on histone deacetylase inhibitors and histone methyltransferase inhibitors are under investigation. In this review we highlight EZH2 as the principal driver of cancer cell immunoediting and an immune escape regulator. We have addressed in detail how understanding T cell epigenetic regulation might bring unique inventive strategies to overcome drug resistance and increase the efficacy of cancer immunotherapy.

Per-cell histone acetylation is associated with terminal differentiation in human T cells

BACKGROUND

Epigenetic remodeling at effector gene loci has been reported to be critical in regulating T cell differentiation and function. However, efforts to investigate underlying epigenetic mechanisms that control T cell behaviors have been largely hindered by very limited experimental tools, especially in humans.

RESULTS

In this study, we employed a flow cytometric assay to analyze histone acetylation at single-cell level in human T cells. The data showed that histone acetylation was increased during T cell activation. Among T cell subsets, terminally differentiated effector memory T (TEMRA) cells robustly producing effector cytokines were hyper-acetylated. Conversely, these TEMRA cells had lower expression levels of TCF-1, a key transcription factor for maintaining stem cell features. Pharmaceutical inhibition of histone acetylation using a small molecule C646 restrained the production of effector molecules, but retained stem cell-like properties in T cells after expansion.

CONCLUSIONS

Per-cell histone acetylation is associated with terminal differentiation and poor stemness in human T cells. These observations suggest a new approach to enhance the stem cell-like properties of T cells and improve the efficacy of immunotherapy.

Grandmaternal allergen sensitization reprograms epigenetic and airway responses to allergen in second-generation offspring

Asthma susceptibility is influenced by environmental, genetic, and epigenetic factors. DNA methylation is one form of epigenetic modification that regulates gene expression and is both inherited and modified by environmental exposures throughout life. Prenatal development is a particularly vulnerable time period during which exposure to maternal asthma increases asthma risk in offspring. How maternal asthma affects DNA methylation in offspring and what the consequences of differential methylation are in subsequent generations are not fully known. In this study, we tested the effects of grandmaternal house dust mite (HDM) allergen sensitization during pregnancy on airway physiology and inflammation in HDM-sensitized and challenged second-generation mice. We also tested the effects of grandmaternal HDM sensitization on tissue-specific DNA methylation in allergen-naïve and -sensitized second-generation mice. Descendants of both allergen- and vehicle-exposed grandmaternal founders exhibited airway hyperreactivity after HDM sensitization. However, grandmaternal allergen sensitization significantly potentiated airway hyperreactivity and altered the epigenomic trajectory in second-generation offspring after HDM sensitization compared with HDM-sensitized offspring from vehicle-exposed founders. As a result, biological processes and signaling pathways associated with epigenetic modifications were distinct between lineages. A targeted analysis of pathway-associated gene expression found that Smad3 was significantly dysregulated as a result of grandmaternal allergen sensitization. These data show that grandmaternal allergen exposure during pregnancy establishes a unique epigenetic trajectory that reprograms allergen responses in second-generation offspring and may contribute to asthma risk.NEW & NOTEWORTHY Asthma susceptibility is influenced by environmental, genetic, and epigenetic factors. This study shows that maternal allergen exposure during pregnancy promotes unique epigenetic trajectories in second-generation offspring at baseline and in response to allergen sensitization, which is associated with the potentiation of airway hyperreactivity. These effects are one mechanism by which maternal asthma may influence the inheritance of asthma risk.

Neuroprotective protein ADNP-dependent histone remodeling complex promotes T helper 2 immune cell differentiation

Type 2 immune responses are critical in tissue homeostasis, anti-helminth immunity, and allergy. T helper 2 (Th2) cells produce interleukin-4 (IL-4), IL-5, and IL-13 from the type 2 gene cluster under regulation by transcription factors (TFs) including GATA3. To better understand transcriptional regulation of Th2 cell differentiation, we performed CRISPR-Cas9 screens targeting 1,131 TFs. We discovered that activity-dependent neuroprotector homeobox protein (ADNP) was indispensable for immune reactions to allergen. Mechanistically, ADNP performed a previously unappreciated role in gene activation, forming a critical bridge in the transition from pioneer TFs to chromatin remodeling by recruiting the helicase CHD4 and ATPase BRG1. Although GATA3 and AP-1 bound the type 2 cytokine locus in the absence of ADNP, they were unable to initiate histone acetylation or DNA accessibility, resulting in highly impaired type 2 cytokine expression. Our results demonstrate an important role for ADNP in promoting immune cell specialization.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

Transcriptional and Epigenetic Regulation of Context-Dependent Plasticity in T-Helper Lineages

Th cell lineage determination and functional specialization are tightly linked to the activation of lineage-determining transcription factors (TFs) that bind cis-regulatory elements. These lineage-determining TFs act in concert with multiple layers of transcriptional regulators to alter the epigenetic landscape, including DNA methylation, histone modification and three-dimensional chromosome architecture, in order to facilitate the specific Th gene expression programs that allow for phenotypic diversification. Accumulating evidence indicates that Th cell differentiation is not as rigid as classically held; rather, extensive phenotypic plasticity is an inherent feature of T cell lineages. Recent studies have begun to uncover the epigenetic programs that mechanistically govern T cell subset specification and immunological memory. Advances in next generation sequencing technologies have allowed global transcriptomic and epigenomic interrogation of CD4+ Th cells that extends previous findings focusing on individual loci. In this review, we provide an overview of recent genome-wide insights into the transcriptional and epigenetic regulation of CD4+ T cell-mediated adaptive immunity and discuss the implications for disease as well as immunotherapies.

The Role of Systems Biology in Deciphering Asthma Heterogeneity

Asthma is one of the most common and lifelong and chronic inflammatory diseases characterized by inflammation, bronchial hyperresponsiveness, and airway obstruction episodes. It is a heterogeneous disease of varying and overlapping phenotypes with many confounding factors playing a role in disease susceptibility and management. Such multifactorial disorders will benefit from using systems biology as a strategy to elucidate molecular insights from complex, quantitative, massive clinical, and biological data that will help to understand the underlying disease mechanism, early detection, and treatment planning. Systems biology is an approach that uses the comprehensive understanding of living systems through bioinformatics, mathematical, and computational techniques to model diverse high-throughput molecular, cellular, and the physiologic profiling of healthy and diseased populations to define biological processes. The use of systems biology has helped understand and enrich our knowledge of asthma heterogeneity and molecular basis; however, such methods have their limitations. The translational benefits of these studies are few, and it is recommended to reanalyze the different studies and omics in conjugation with one another which may help understand the reasons for this variation and help overcome the limitations of understanding the heterogeneity in asthma pathology. In this review, we aim to show the different factors that play a role in asthma heterogeneity and how systems biology may aid in understanding and deciphering the molecular basis of asthma.

Focus on long non-coding RNA MALAT1: Insights into acute and chronic lung diseases

Acute lung injury (ALI) is a pulmonary illness with a high burden of morbidity and mortality around the world. Chronic lung diseases also represent life-threatening situations. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a type of long non-coding RNA (lncRNA) and is highly abundant in lung tissues. MALAT1 can function as a competitive endogenous RNA (ceRNA) to impair the microRNA (miRNA) inhibition on targeted messenger RNAs (mRNAs). In this review, we summarized that MALAT1 mainly participates in pulmonary cell biology and lung inflammation. Therefore, MALAT1 can positively or negatively regulate ALI and chronic lung diseases (e.g., chronic obstructive pulmonary disease (COPD), bronchopulmonary dysplasia (BPD), pulmonary fibrosis, asthma, and pulmonary hypertension (PH)). Besides, we also found a MALAT1-miRNA-mRNA ceRNA regulatory network in acute and chronic lung diseases. Through this review, we hope to cast light on the regulatory mechanisms of MALAT1 in ALI and chronic lung disease and provide a promising approach for lung disease treatment.

A population of naive-like CD4+ T cells stably polarized to the TH 1 lineage

T-bet is the lineage-specifying transcription factor for CD4+ TH 1 cells. T-bet has also been found in other CD4+ T cell subsets, including TH 17 cells and Treg, where it modulates their functional characteristics. However, we lack information on when and where T-bet is expressed during T cell differentiation and how this impacts T cell differentiation and function. To address this, we traced the ontogeny of T-bet-expressing cells using a fluorescent fate-mapping mouse line. We demonstrate that T-bet is expressed in a subset of CD4+ T cells that have naïve cell surface markers and transcriptional profile and that this novel cell population is phenotypically and functionally distinct from previously described populations of naïve and memory CD4+ T cells. Naïve-like T-bet-experienced cells are polarized to the TH 1 lineage, predisposed to produce IFN-γ upon cell activation, and resist repolarization to other lineages in vitro and in vivo. These results demonstrate that lineage-specifying factors can polarize T cells in the absence of canonical markers of T cell activation and that this has an impact on the subsequent T-helper response.

Repositioning TH cell polarization from single cytokines to complex help

When helper T (T_H) cell polarization was initially described three decades ago, the T_H cell universe grew dramatically. New subsets were described based on their expression of few specific cytokines. Beyond T_H1 and T_H2 cells, this led to the coining of various T_H17 and regulatory (T_reg) cell subsets as well as T_H22, T_H25, follicular helper (T_FH), T_H3, T_H5 and T_H9 cells. High-dimensional single-cell analysis revealed that a categorization of T_H cells into a single-cytokine-based nomenclature fails to capture the complexity and diversity of T_H cells. Similar to the simple nomenclature used to describe innate lymphoid cells (ILCs), we propose that T_H cell polarization should be categorized in terms of the help they provide to phagocytes (type 1), to B cells, eosinophils and mast cells (type 2) and to non-immune tissue cells, including the stroma and epithelium (type 3). Studying T_H cells based on their helper function and the cells they help, rather than phenotypic features such as individual analyzed cytokines or transcription factors, better captures T_H cell plasticity and conversion as well as the breadth of immune responses in vivo.

Local induction of bladder Th1 responses to combat urinary tract infections

Given the high frequency of urinary tract infections (UTIs) and their recurrence, there is keen interest in developing effective UTI vaccines. Currently, most vaccine studies, including those in humans, involve parenteral vaccination aimed at evoking and sustaining elevated levels of systemic antibody directed at the uropathogens. In view of recent reports of aberrant Th2-biased bladder immune responses to infection, we hypothesized that immunizing mice intravesically with antigens from uropathogenic Escherichia coli (UPEC) combined with a Th1-skewing adjuvant could correct this defect and promote protection against UTIs. Here we report that compared with mice immunized subcutaneously with this vaccine combination, intravesically immunized mice were markedly more protected from UTIs because of their distinctive ability to recruit Th1 cells into the bladder. This mode of vaccination was effective even in mice that experienced multiple UTIs and displayed pronounced aberrant bladder immune responses. Thus, intravesical vaccination with one or more UPEC antigens to induce bladder Th1 responses represents a superior strategy to combat UTIs, especially in UTI-prone subjects.

Polyamine metabolism is a central determinant of helper T cell lineage fidelity

Polyamine synthesis represents one of the most profound metabolic changes during T cell activation, but the biological implications of this are scarcely known. Here, we show that polyamine metabolism is a fundamental process governing the ability of CD4+ helper T cells (TH) to polarize into different functional fates. Deficiency in ornithine decarboxylase, a crucial enzyme for polyamine synthesis, results in a severe failure of CD4+ T cells to adopt correct subset specification, underscored by ectopic expression of multiple cytokines and lineage-defining transcription factors across TH cell subsets. Polyamines control TH differentiation by providing substrates for deoxyhypusine synthase, which synthesizes the amino acid hypusine, and mice in which T cells are deficient for hypusine develop severe intestinal inflammatory disease. Polyamine-hypusine deficiency caused widespread epigenetic remodeling driven by alterations in histone acetylation and a re-wired tricarboxylic acid (TCA) cycle. Thus, polyamine metabolism is critical for maintaining the epigenome to focus TH cell subset fidelity.

Re-Programming Autoreactive T Cells Into T-Regulatory Type 1 Cells for the Treatment of Autoimmunity

Systemic delivery of peptide-major histocompatibility complex (pMHC) class II-based nanomedicines can re-program cognate autoantigen-experienced CD4+ T cells into disease-suppressing T-regulatory type 1 (TR1)-like cells. In turn, these TR1-like cells trigger the formation of complex regulatory cell networks that can effectively suppress organ-specific autoimmunity without impairing normal immunity. In this review, we summarize our current understanding of the transcriptional, phenotypic and functional make up of TR1-like cells as described in the literature. The true identity and direct precursors of these cells remain unclear, in particular whether TR1-like cells comprise a single terminally-differentiated lymphocyte population with distinct transcriptional and epigenetic features, or a collection of phenotypically different subsets sharing key regulatory properties. We propose that detailed transcriptional and epigenetic characterization of homogeneous pools of TR1-like cells will unravel this conundrum.

Interferon-γ: teammate or opponent in the tumour microenvironment?

Cancer immunotherapy offers substantive benefit to patients with various tumour types, in some cases leading to complete tumour clearance. However, many patients do not respond to immunotherapy, galvanizing the field to define the mechanisms of pre-existing and acquired resistance. Interferon-γ (IFNγ) is a cytokine that has both protumour and antitumour activities, suggesting that it may serve as a nexus for responsiveness to immunotherapy. Many cancer immunotherapies and chemotherapies induce IFNγ production by various cell types, including activated T cells and natural killer cells. Patients resistant to these therapies commonly have molecular aberrations in the IFNγ signalling pathway or express resistance molecules driven by IFNγ. Given that all nucleated cells can respond to IFNγ, the functional consequences of IFNγ production need to be carefully dissected on a cell-by-cell basis. Here, we review the cells that produce IFNγ and the different effects of IFNγ in the tumour microenvironment, highlighting the pleiotropic nature of this multifunctional and abundant cytokine.

Genome wide DNA methylation landscape reveals glioblastoma's influence on epigenetic changes in tumor infiltrating CD4+ T cells

CD4+ helper T (Th) cells play a critical role in shaping anti-tumor immunity by virtue of their ability to differentiate into multiple lineages in response to environmental cues. Various CD4+ lineages can orchestrate a broad range of effector activities during the initiation, expansion, and memory phase of endogenous anti-tumor immune response. In this clinical corelative study, we found that Glioblastoma (GBM) induces multi- and mixed-lineage immune response in the tumor microenvironment. Whole-genome bisulfite sequencing of tumor infiltrating and blood CD4+ T-cell from GBM patients showed 13571 differentially methylated regions and a distinct methylation pattern of methylation of tumor infiltrating CD4+ T-cells with significant inter-patient variability. The methylation changes also resulted in transcriptomic changes with 341 differentially expressed genes in CD4+ tumor infiltrating T-cells compared to blood. Analysis of specific genes involved in CD4+ differentiation and function revealed differential methylation status of TBX21, GATA3, RORC, FOXP3, IL10 and IFNG in tumor CD4+ T-cells. Analysis of lineage specific genes revealed differential methylation and gene expression in tumor CD4+ T-cells. Interestingly, we observed dysregulation of several ligands of T cell function genes in GBM tissue corresponding to the T-cell receptors that were dysregulated in tumor infiltrating CD4+ T-cells. Our results suggest that GBM might induce epigenetic alterations in tumor infiltrating CD4+ T-cells there by influencing anti-tumor immune response by manipulating differentiation and function of tumor infiltrating CD4+ T-cells. Thus, further research is warranted to understand the role of tumor induced epigenetic modification of tumor infiltrating T-cells to develop effective anti-GBM immunotherapy.

Yin and yang of immunological memory in controlling infections: Overriding self defence mechanisms

Immunological memory is critical for host immunity and decisive for individual to respond exponentially to previously encountered infection. Both T and B cell memory are known to orchestrate immunological memory with their central and effector memory arms contributing in prolonged immunity/defence mechanisms of host. While central memory helps in maintaining prolonged immunity for a particular infection, effector memory helps in keeping local/seasonal infection in control. In addition to this, generation of long-lived plasma cells is pivotal for generating neutralizing antibodies which can enhance recall and B cell memory to control re-infection. In view of this, scaling up memory response is one of the major objectives for the expected outcome of vaccination. In this line, this review deals with the significance of memory cells, molecular pathways of their development, maintenance, epigenetic regulation and negative regulation in various infections. We have also highlighted the significance of both T and B cell memory responses in the vaccination approaches against range of infections which is not fully explored so far.[Box: see text].

Comparative Analysis of Global Proteome and Lysine Acetylome Between Naive CD4+ T Cells and CD4+ T Follicular Helper Cells

As a subgroup of CD4⁺ T helper cells, follicular helper T (Tfh) cells provide help to germinal center B cells and mediate the development of long-lived humoral immunity. Dysregulation of Tfh cells is associated with several major autoimmune diseases. Although recent studies showed that Tfh cell differentiation is controlled by the transcription factor Bcl6, cytokines, and cell-cell signals, limited information is available on the proteome and post-translational modifications (PTMs) of proteins in human Tfh cells. In the present study, we investigated quantitative proteome and acetylome in human naive CD4⁺ T cells and in vitro induced Tfh (iTfh) cells using the tandem mass tag (TMT) labeling technique, antibody-based affinity enrichment, and high-resolution liquid chromatography-mass spectrometry (LC-MS)/mass spectrometry (MS) analysis. In total, we identified 802 upregulated proteins and 598 downregulated proteins at the threshold of 1.5-fold in iTfh cells compared to naive CD4⁺ T cells. With the aid of intensive bioinformatics, the biological process, the cellular compartment, the molecular function, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and protein–protein interaction of these differentially expressed proteins were revealed. Moreover, the acetylome data showed that 22 lysine (K) acetylated proteins are upregulated and 26 K acetylated proteins are downregulated in iTfh cells compared to the naive CD4⁺ T cells, among which 11 differentially acetylated K residues in core histones were identified, indicating that protein acetylation and epigenetic mechanism are involved in regulating Tfh cell differentiation. The study provides some important clues for investigating T cell activation and Tfh cell differentiation.

The potency of lncRNA MALAT1/miR-155/CTLA4 axis in altering Th1/Th2 balance of asthma

Objectives: The present study examined if the metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-155/CTLA-4 axis was involved in modifying Th1/Th2 balance, a critical indicator for asthma progression. Methods: Altogether 772 asthma patients and 441 healthy controls were recruited, and their blood samples were collected to determine expressional levels of MALAT1, miR-155, CTLA-4, T-bet, GATA3, Th1-type cytokines and Th2-type cytokines. The CD⁴⁺ T cells were administered with pcDNA3.1-MALAT1, si-MALAT1, miR-155 mimic and miR-155 inhibitor to assess their effects on cytokine release. The luciferase reporter gene assay was also adopted to evaluate the sponging relationships between MALAT1 and miR-155, as well as between miR-155 and CTLA-4. Results: Over-expressed MALAT1 and under-expressed miR-155 were more frequently detected among asthma patients who showed traits of reduced forced expiratory failure volume in 1 s (FEV1), FEV1/forced vital capacity (FVC) and FEV1% of predicted (P<0.05). Moreover, MALAT1 expression was negatively expressed with the Th1/Th2 and T-bet/GATA3 ratios, yet miR-155 expression displayed a positively correlation with the ratios (P<0.05). Additionally, the IFN-γ, IL-2 and T-bet levels were reduced under the influence of pcDNA3.1-MALAT1 and miR-155 inhibitor, while levels of IL-4, IL-10 and GATA3 were raised under identical settings (P<0.05). Furthermore, MALAT1 constrained expression of miR-155 within CD⁴⁺ T cells by sponging it, and CTLA-4 could interfere with the effects of MALAT1 and miR-155 on Th1/Th2 balance and T-bet/Gata3 ratio (P<0.05). Conclusion: MALAT1 sponging miR-155 was involved with regulation of Th1/Th2 balance within CD⁴⁺ T cells, which might aid to develop therapies for amelioration of asthmatic inflammation.

Epigenetic regulation of T cell adaptive immunity

The conceptualization of adaptive immunity, founded on the observation of immunological memory, has served as the basis for modern vaccination and immunotherapy approaches. This fundamental concept has allowed immunologists to explore mechanisms that enable humoral and cellular lymphocytes to tailor immune response functions to a wide array of environmental insults and remain poised for future pathogenic encounters. Until recently, for T cells it has remained unclear how memory differentiation acquires and sustains a gene expression program that grants a cell with a capacity for a heightened recall response. Recent investigations into this critical question have identified epigenetic programs as a causal molecular mechanism governing T cell subset specification and immunological memory. Here, we outline the studies that have illustrated this concept and posit on how insights into T cell adaptive immunity can be applied to improve upon existing immunotherapies.

A highly polarized TH2 bladder response to infection promotes epithelial repair at the expense of preventing new infections

Urinary tract infections (UTIs) typically evoke prompt and vigorous innate bladder immune responses, including extensive exfoliation of the epithelium. To explain the basis for the extraordinarily high recurrence rates of UTIs, we examined adaptive immune responses in mouse bladders. We found that, following each bladder infection, a highly T helper type 2 (TH2)-skewed immune response directed at bladder re-epithelialization is observed, with limited capacity to clear infection. This response is initiated by a distinct subset of CD301b+OX40L+ dendritic cells, which migrate into the bladder epithelium after infection before trafficking to lymph nodes to preferentially activate TH2 cells. The bladder epithelial repair response is cumulative and aberrant as, after multiple infections, the epithelium was markedly thickened and bladder capacity was reduced relative to controls. Thus, recurrence of UTIs and associated bladder dysfunction are the outcome of the preferential focus of the adaptive immune response on epithelial repair at the expense of bacterial clearance.

Epigenetic Regulation of T Cell Memory: Recalling Therapeutic Implications

Memory T cells possess functional differences from naïve T cells that powerfully contribute to the efficiency of secondary immune responses. These abilities are imprinted during the primary response, linked to the acquisition of novel patterns of gene expression. Underlying this are alterations at the chromatin level (epigenetic modifications) that regulate constitutive and inducible gene transcription. T cell epigenetic memory can persist long-term, contributing to long-lasting immunity after infection or vaccination. However, acquired epigenetic states can also hinder effective tumor immunity or contribute to autoimmunity. The growing understanding of epigenetic gene regulation as it relates to both the stability and malleability of T cell memory may offer the potential to selectively modify T cell memory in disease by targeting epigenetic mechanisms.

Coupling Fluorescence-Activated Cell Sorting and Targeted Analysis of Histone Modification Profiles in Primary Human Leukocytes

Histone posttranslational modifications (PTMs) are essential for regulating chromatin and maintaining gene expression throughout cell differentiation. Despite the deep level of understanding of immunophenotypic differentiation pathways in hematopoietic cells, few studies have investigated global levels of histone PTMs required for differentiation and maintenance of these distinct cell types. Here, we describe an approach to couple fluorescence-activated cell sorting (FACS) with targeted mass spectrometry to define global "epi-proteomic" signatures for primary leukocytes. FACS was used to sort closely and distantly related leukocytes from normal human peripheral blood for quantitation of histone PTMs with a multiple reaction monitoring LC-MS/MS method measuring histone PTMs on histones H3 and H4. We validate cell sorting directly into H₂SO₄ for immediate histone extraction to decrease time and number of steps after FACS to analyze histone PTMs. Relative histone PTM levels vary in T cells across healthy donors, and the majority of PTMs remain stable up to 2 days following initial blood draw. Large differences in the levels of histone PTMs are observed across the mature lymphoid and myeloid lineages, as well as between different types within the same lineage, though no differences are observed in closely related T cell subtypes. The results show a streamlined approach for quantifying global changes in histone PTMs in cell types separated by FACS that is poised for clinical deployment.

Bromodomain inhibitor JQ1 reversibly blocks IFN-γ production

As a class, ‘BET’ inhibitors disrupt binding of bromodomain and extra-terminal motif (BET) proteins, BRD2, BRD3, BRD4 and BRDT, to acetylated histones preventing recruitment of RNA polymerase 2 to enhancers and promoters, especially super-enhancers, to inhibit gene transcription. As such, BET inhibitors may be useful therapeutics for treatment of cancer and inflammatory disease. For example, the small molecule BET inhibitor, JQ1, selectively represses MYC, an important oncogene regulated by a super-enhancer. IFN-γ, a critical cytokine for both innate and adaptive immune responses, is also regulated by a super-enhancer. Here, we show that JQ1 represses IFN-γ expression in TH1 polarized PBMC cultures, CD4+ memory T cells, and NK cells. JQ1 treatment does not reduce activating chromatin marks at the IFNG locus, but displaces RNA polymerase II from the locus. Further, IFN-γ expression recovers in polarized TH1 cultures following removal of JQ1. Our results show that JQ1 abrogates IFN-γ expression, but repression is reversible. Thus, BET inhibitors may disrupt the normal functions of the innate and adaptive immune response.

Polycomb repressive complex 2 is a critical mediator of allergic inflammation

Strategies that intervene with the development of immune-mediated diseases are urgently needed, as current treatments mostly focus on alleviating symptoms rather than reversing the disease. Targeting enzymes involved in epigenetic modifications to chromatin represents an alternative strategy that has the potential to perturb the function of the lymphocytes that drive the immune response. Here, we report that 2 major epigenetic silencing pathways are increased after T cell activation. By specific inactivation of these molecules in the T cell compartment in vivo, we demonstrate that the polycomb repressive complex 2 (PRC2) is essential for the generation of allergic responses. Furthermore, we show that small-molecule inhibition of the PRC2 methyltransferase, enhancer of zeste homolog 2 (Ezh2), reduces allergic inflammation in mice. Therefore, by systematically surveying the pathways involved in epigenetic gene silencing we have identified Ezh2 as a target for the suppression of allergic disease.

Epigenetic Modifications in Placenta are Associated with the Child's Sensitization to Allergens

Prenatal environmental exposures are considered to contribute to the development of allergic sensitization by epigenetic mechanisms. The role of histone acetylation in the placenta has not been examined yet. We hypothesized that placental histone acetylation at the promoter regions of allergy-related immune regulatory genes is associated with the development of sensitization to allergens in the child. Histones H3 and H4 acetylation at the promoter regions of 6 selected allergy-related immune regulatory genes was assessed by a chromatin immunoprecipitation assay in 173 term placentas collected in the prospective birth-cohort ALADDIN. The development of IgE sensitization to allergens in the children was followed from 6 months up to 5 years of age. We discovered significant associations of histone acetylation levels with decreased risk of allergic sensitization in 3 genes. Decreased risk of sensitization to food allergens was associated with higher H3 acetylation levels in placentas at the IFNG and SH2B3 genes, and for H4 acetylation in HDAC4. Higher HDAC4 H4 acetylation levels were also associated with a decreased risk of sensitization to aeroallergens. In conclusion, our results suggest that acetylation of histones in placenta has a potential to predict the development of sensitization to allergens in children.

Multilayer regulation of CD4 T cell subset differentiation in the era of single cell genomics

CD4 T cells are major immune cell types that mediate effector responses appropriate for diverse incoming threats. These cells have been categorized into different subsets based on how they are induced, expression of specific master transcription factors, and the resulting effector cell phenotypes as defined by expression of signature cytokines. However, recent studies assessing the expression of gene modules in single CD4 T cells, rather than expression of one or a few signature genes, have provided a more complex picture in which the canonical model does not fit as cleanly as proposed. Here, we review the concepts of lineage commitment, plasticity and functional heterogeneity in the context of this greater complexity. We then apply our current understanding of CD4 T cell subsets to discuss outstanding questions regarding follicular helper T cells and follicular regulatory T cells with respect to their shared features with other known CD4 T cell subsets.

Histone deacetylase function in CD4+ T cells

The differentiation of T helper cell subsets and their acquisition of effector functions are accompanied by changes in gene expression programmes, which in part are regulated and maintained by epigenetic processes. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are key epigenetic regulators that function by mediating dynamic changes in the acetylation of histones at lysine residues. In addition, many non-histone proteins are also acetylated, and reversible acetylation affects their functional properties, demonstrating that HDACs mediate effects beyond the epigenetic regulation of gene expression. In this Review, we discuss studies revealing that HDACs are key regulators of CD4+ T cell-mediated immunity in mice and humans and that HDACs are promising targets in T cell-mediated immune diseases. Finally, we discuss unanswered questions and future research directions to promote the concept that isoform-selective HDAC inhibitors might broaden the clinical application of HDAC inhibitors beyond their current use in certain types of cancer.

Air pollutants and early origins of respiratory diseases

Air pollution is a global health threat and causes millions of human deaths annually. The late onset of respiratory diseases in children and adults due to prenatal or perinatal exposure to air pollutants is emerging as a critical concern in human health. Pregnancy and fetal development stages are highly susceptible to environmental exposure and tend to develop a long-term impact in later life. In this review, we briefly glance at the direct impact of outdoor and indoor air pollutants on lung diseases and pregnancy disorders. We further focus on lung complications in later life with early exposure to air pollutants. Epidemiological evidence is provided to show the association of prenatal or perinatal exposure to air pollutants with various adverse birth outcomes, such as preterm birth, lower birth weight, and lung developmental defects, which further associate with respiratory diseases and reduced lung function in children and adults. Mechanistic evidence is also discussed to support that air pollutants impact various cellular and molecular targets at early life, which link to the pathogenesis and altered immune responses related to abnormal respiratory functions and lung diseases in later life.

Genetic and epigenetic influences on the loss of tolerance in autoimmunity

Immunological tolerance loss is fundamental to the development of autoimmunity; however, the underlying mechanisms remain elusive. Immune tolerance consists of central and peripheral tolerance. Central tolerance, which occurs in the thymus for T cells and bone marrow for B cells, is the primary way that the immune system discriminates self from non-self. Peripheral tolerance, which occurs in tissues and lymph nodes after lymphocyte maturation, controls self-reactive immune cells and prevents over-reactive immune responses to various environment factors. Loss of tolerance results in autoimmune disorders, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D) and primary biliary cirrhosis (PBC). The etiology and pathogenesis of autoimmune diseases are highly complicated. Both genetic predisposition and epigenetic modifications are implicated in the loss of tolerance and autoimmunity. In this review, we will discuss the genetic and epigenetic influences on tolerance breakdown in autoimmunity. Genetic and epigenetic influences on autoimmune diseases, such as SLE, RA, T1D and PBC, will also be briefly discussed.

A cellular and molecular view of T helper 17 cell plasticity in autoimmunity

Since the original identification of the T helper 17 (Th17) subset in 2005, it has become evident that these cells do not only contribute to host defence against pathogens, such as bacteria and fungi, but that they are also critically involved in the pathogenesis of many autoimmune diseases. In contrast to the classic Th1 and Th2 cells, which represent rather stably polarized subsets, Th17 cells display remarkable heterogeneity and plasticity. This has been attributed to the characteristics of the key transcription factor that guides Th17 differentiation, retinoic acid receptor-related orphan nuclear receptor gamma (RORγ). Unlike the 'master regulators' T-bet and GATA3 that orchestrate Th1 and Th2 differentiation, respectively, RORγ controls transcription at relatively few loci in Th17 cells. Moreover, its expression is not stabilized by positive feedback loops but rather influenced by environmental cues, allowing for substantial functional plasticity. Importantly, a subset of IL-17/IFNγ double-producing Th17 cells was identified in both human and mouse models. Evidence is accumulating that these IL-17/IFNγ double-producing cells are pathogenic drivers in autoimmune diseases, including rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease. In addition, IL-17/IFNγ double-producing cells have been identified in disorders in which the role of autoimmunity remains unclear, such as sarcoidosis. The observed plasticity of Th17 cells towards the Th1 phenotype can be explained by extensive epigenetic priming of the IFNG locus in Th17 cells. In fact, Th17 cells display an IFNG chromatin landscape that is remarkably similar to that of Th1 cells. On the other hand, pathogenic capabilities of Th17 cells can be restrained by stimulating IL-10 production and transdifferentiation into IL-10 producing T regulatory type 1 (Tr1) cells. In this review, we discuss recent advances in our knowledge on the cellular and molecular mechanisms involved in Th17 differentiation, heterogeneity and plasticity. We focus on transcriptional regulation of the Th17 expression program, the epigenetic dynamics involved, and how genetic variants associated with autoimmunity may affect immune responses through distal gene regulatory elements. Finally, the implications of Th17 cell plasticity for the pathogenesis and treatment of human autoimmune diseases will be discussed.

HDAC4 is expressed on multiple T cell lineages but dispensable for their development and function

Histone deacetylation, reciprocally mediated by histone deacetylases (HDAC) and acetyltransferases, represents one major form of post-translational modification. Previous research indicates that HDACs play an essential regulatory role in the development of various immune cells. However, the specific function of individual HDACs remains largely unexplored. HDAC4, a member of class II HDACs, profoundly investigated in the nervous system, while the expression profile and function of HDAC4 in T cells are barely known. For the first time, we report here that HDAC4 is expressed in the multiple T cell lineages. Using T-cell-specific HDAC4-deficient mice, we discovered that lack of HDAC4 did not alter the frequencies of conventional T cells, invariant NKT (iNKT) cells or regulatory T cells within both the thymus and secondary lymphoid organs. Moreover, conventional T cells and iNKT cells from wild-type and HDAC4-deficient mice displayed no significant difference in cytokine production. In conclusion, our results imply that under steady stage, HDAC4 is not required for the development and function of multiple T cell lineages, including conventional T cells and iNKT cells.

The environment, epigenome, and asthma

Asthma prevalence has been on the increase, especially in North America compared with other continents. However, the prevalence of asthma differs worldwide, and in many countries the prevalence is stable or decreasing. This highlights the influence of environmental exposures, such as allergens, air pollution, and the environmental microbiome, on disease etiology and pathogenesis. The epigenome might provide the unifying mechanism that translates the influence of environmental exposures to changes in gene expression, respiratory epithelial function, and immune cell skewing that are hallmarks of asthma. In this review we will introduce the concept of the environmental epigenome in asthmatic patients, summarize previous publications of relevance to this field, and discuss future directions.

The Microbial Metabolite Butyrate Induces Expression of Th1-Associated Factors in CD4+ T Cells

Short-chain fatty acids (SCFAs), which are generated by the bacterial fermentation of dietary fibers, promote expansion of regulatory T cells (Tregs). Potential therapeutic value of SCFAs has been recently highlighted in the experimental models of T cell-mediated autoimmunity and allergic inflammation. These studies suggest that physiological intestinal concentrations of SCFAs within the millimolar range are crucial for dampening inflammation-mediated processes. Here, we describe opposing effects of SCFAs on T cell-mediated immune responses. In accordance with published data, lower butyrate concentrations facilitated differentiation of Tregs in vitro and in vivo under steady-state conditions. In contrast, higher concentrations of butyrate induced expression of the transcription factor T-bet in all investigated T cell subsets resulting in IFN-γ-producing Tregs or conventional T cells. This effect was mediated by the inhibition of histone deacetylase activity and was independent of SCFA-receptors FFA2 and FFA3 as well as of Na⁺-coupled SCFA transporter Slc5a8. Importantly, while butyrate was not able to induce the generation of Tregs in the absence of TGF-β1, the expression of T-bet and IFN-γ was triggered upon stimulation of CD4⁺ T cells with this SCFA alone. Moreover, the treatment of germ-free mice with butyrate enhanced the expression of T-bet and IFN-γ during acute colitis. Our data reveal that, depending on its concentration and immunological milieu, butyrate may exert either beneficial or detrimental effects on the mucosal immune system.

Stabilizing human regulatory T cells for tolerance inducing immunotherapy

Many autoimmune diseases develop as a consequence of an altered balance between autoreactive immune cells and suppressive FOXP3⁺ Treg. Restoring this balance through amplification of Treg represents a promising strategy to treat disease. However, FOXP3⁺ Treg might become unstable especially under certain inflammatory conditions, and might transform into proinflammatory cytokine-producing cells. The issue of heterogeneity and instability of Treg has caused considerable debate in the field and has important implications for Treg-based immunotherapy. In this review, we discuss how Treg stability is defined and what the molecular mechanisms underlying the maintenance of FOXP3 expression and the regulation of Treg stability are. Also, we elaborate on current strategies used to stabilize human Treg for clinical purposes. This review focuses on human Treg, but considering that cell-intrinsic mechanisms to regulate Treg stability in mice and in humans might be similar, data derived from mice studies are also discussed in this paper.

Tumor Dormancy and Relapse: From a Natural Byproduct of Evolution to a Disease State

Species evolve by mutations and epigenetic changes acting on individuals in a population; tumors evolve by similar mechanisms at a cellular level in a tissue. This article reviews growing evidence about tumor dormancy and suggests that (i) cellular malignancy is a natural byproduct of evolutionary mechanisms, such as gene mutations and epigenetic modifications, which is manifested in the form of tumor dormancy in healthy individuals as well as in cancer survivors; (ii) cancer metastasis could be an early dissemination event that could occur during malignant dormancy even before primary cancer is clinically detectable; and (iii) chronic inflammation is a key factor in awakening dormant malignant cells at the primary site, leading to primary cancer development, and at distant sites, leading to advanced stage diseases. On the basis of this evidence, it is reasonable to propose that we are all cancer survivors rather than cancer-free individuals because of harboring dormant malignant cells in our organs. A better understanding of local and metastatic tumor dormancy could lead to novel cancer therapeutics for the prevention of cancer. Cancer Res; 77(10); 2564-9. ©2017 AACR.

The influence of dietary immunomodulatory factors on development of food allergy in children

In the last few years many studies have been conducted on the role of dietary and environmental factors in the prevention of allergic diseases among children. Many studies have shown that the diet of pregnant women and children in their early postnatal life, rich in antioxidants, vitamin D, and fatty acids is beneficial as it reduces the risk of allergy in their future life. Moreover, there are many reports about the main role of gut microbiota and probiotics in the allergy prevention, what can indicate new ways of procedures in allergic diseases.

RHS6-mediated chromosomal looping and nuclear substructure binding is required for Th2 cytokine gene expression

Subset-specific gene expression is a critical feature of CD4 T cell differentiation. Th2 cells express Th2 cytokine genes including Il4, Il5, and Il13 and mediate the immune response against helminths. The expression of Th2 cytokine genes is regulated by Rad50 hypersensitive site 6 (RHS6) in the Th2 locus control region; however, the molecular mechanisms of RHS6 action at the chromatin level are poorly understood. Here, we demonstrate that RHS6 is crucial for chromosomal interactions and nuclear substructure binding of the Th2 cytokine locus. RHS6-deficient cells had a marked reduction in chromatin remodeling and in intrachromosomal interactions at the Th2 locus. Deficiency of RHS6-binding transcription factors GATA3, SATB1, and IRF4 also caused a great reduction in chromatin remodeling and long-range chromosomal interactions involving the Th2 locus. RHS6 deficiency abrogated association of the Th2 locus with the nuclear substructure and RNA polymerase II. Therefore, RHS6 serves as a crucial cis-acting hub for coordinate regulation of Th2 cytokine genes by forming chromosomal loops and binding to a nuclear substructure.

Functionality and opposite roles of two interleukin 4 haplotypes in immune cells

Cytokines expression can be influenced by polymorphisms in their respective coding genes. We associated the CTI/TTD haplotype (Hap-1) and TCI/CCI haplotype (Hap-2) in the IL4 gene formed by the -590, +33 and variable number of tandem repeat polymorphisms with the severity of chronic periodontitis in humans. The functionality of these IL4 haplotypes in the response of immune cells to phorbol 12-myristate 13-acetate (PMA) with Ionomycin and IL-1β (as inflammatory stimuli) was evaluated. Gene expression (quantitative real-time PCR), profile of secreted cytokines (multiplex) and phenotypic polarization of T cells (flow cytometry) were the outcomes assessed. Green fluorescent protein reporter plasmid constructs containing specific IL4 haplotype were transiently transfected into JM cells to assess the influence of the individual haplotypes on promoter activity. In response to inflammatory stimuli the immune cells from Hap-1 haplotype had increased expression of anti-inflammatory IL4; conversely, the Hap-2 haplotype showed higher levels of pro-inflammatory cytokines. The haplotype CTI proved to be the most important for the regulation of IL4 promoter, regardless of the nature of the inflammatory stimulation; whereas the polymorphism in the promoter region had the least functional effect. In conclusion, IL4 haplotypes studied are functional and trigger opposite immune responses: anti-inflammatory (Hap-1) and pro-inflammatory (Hap-2). In addition, we identified the CTI haplotype as the main responsible for the regulation of IL4 transcriptional activity.

Transcriptional regulator Bhlhe40 works as a cofactor of T-bet in the regulation of IFN-γ production in iNKT cells

Invariant natural killer T (iNKT) cells are a subset of innate-like T cells that act as important mediators of immune responses. In particular, iNKT cells have the ability to immediately produce large amounts of IFN-γ upon activation and thus initiate immune responses in various pathological conditions. However, molecular mechanisms that control IFN-γ production in iNKT cells are not fully understood. Here, we report that basic helix-loop-helix transcription factor family, member e40 (Bhlhe40), is an important regulator for IFN-γ production in iNKT cells. Bhlhe40 is highly expressed in stage 3 thymic iNKT cells and iNKT1 subsets, and the level of Bhlhe40 mRNA expression is correlated with Ifng mRNA expression in the resting state. Although Bhlhe40-deficient mice show normal iNKT cell development, Bhlhe40-deficient iNKT cells show significant impairment of IFN-γ production and antitumor effects. Bhlhe40 alone shows no significant effects on Ifng promoter activities but contributes to enhance T-box transcription factor Tbx21 (T-bet)-mediated Ifng promoter activation. Chromatin immunoprecipitation analysis revealed that Bhlhe40 accumulates in the T-box region of the Ifng locus and contributes to histone H3-lysine 9 acetylation of the Ifng locus, which is impaired without T-bet conditions. These results indicate that Bhlhe40 works as a cofactor of T-bet for enhancing IFN-γ production in iNKT cells.

[Epigenetics in allergic diseases and asthma]

Allergic diseases and asthma are the result of complex interactions between genetic predisposition and environmental factors. Asthma is one of the most prevalent chronic disease among children. In this article we review some environmental factors like: allergen exposition, tobacco, bacteria, microbial components, diet, obesity and stress, which influences during intrauterine and infancy life in the epigenetic regulation of asthma and allergic diseases. The review has been done in three models: in-vitro, animal and human.

Marijuana-derived Δ-9-tetrahydrocannabinol suppresses Th1/Th17 cell-mediated delayed-type hypersensitivity through microRNA regulation

∆(9)-Tetrahydrocannabinol (THC) is one of the major bioactive cannabinoids derived from the Cannabis sativa plant and is known for its anti-inflammatory properties. Delayed-type hypersensitivity (DTH) is driven by proinflammatory T helper cells including the classic inflammatory Th1 lineage as well as the more recently discovered Th17 lineage. In the current study, we investigated whether THC can alter the induction of Th1/Th17 cells involved in mBSA-induced DTH response. THC treatment (20 mg/kg) of C57BL/6 mice with DTH caused decreased swelling and infiltration of immune cells at the site of antigen rechallenge. Additionally, THC treatment decreased lymphocyte activation as well as Th1/Th17 lineage commitment, including reduced lineage-specific transcription factors and cytokines. Interestingly, while DTH caused an overexpression of miR-21, which increases Th17 differentiation via SMAD7 inhibition, and downregulation of miR-29b, an IFN-γ inhibitor, THC treatment reversed this microRNA (miR) dysregulation. Furthermore, when we transfected primary cells from DTH mice with miR-21 inhibitor or miR-29b mimic, as seen with THC treatment, the expression of target gene message was directly impacted increasing SMAD7 and decreasing IFN-γ expression, respectively. In summary, the current study suggests that THC treatment during DTH response can simultaneously inhibit Th1/Th17 activation via regulation of microRNA (miRNA) expression.

KEY MESSAGES

• THC treatment inhibits simultaneous Th1/Th17 driven inflammation. • THC treatment corrects DTH-mediated microRNA dysregulation. • THC treatment regulates proinflammatory cytokines and transcription factors.

The role of nitric oxide in the epigenetic regulation of THP-1 induced by lipopolysaccharide

AIMS

Changes in the gene expression are one of the molecular events involved in the Systemic of Inflammatory Response Syndrome during sepsis. The preconditioning with low doses of lipopolysaccharide (LPS) reduces the expression of pro-inflammatory genes leading to less tissue damage and better outcome. This hyporesponsive state called tolerance is associated to alterations in chromatin structure and nitric oxide (NO) production. In the current study, we demonstrated that tolerance induced by LPS was found to be NO-dependent and related to epigenetic changes.

MAIN METHODS

THP-1 cells were cultivated in RPMI medium (Control), submitted to tolerance (500ng/mL of LPS 24h before challenge with 1000ng/mL of LPS during 24h Tolerant group) and challenge (1000ng/mL of LPS during 24h Directly challenged group). The analyses performed were: cytokines production, histone acetyl transferases/histone deacetylases (HAT/HDAC) activity, nitrosylation of HDAC-2 and -3, expression of acetylated histones H3 and H4. HDAC and Nitric Oxide Synthases (NOS) activities were inhibited with 30mM trichostatin (TSA) and 100μM LNAME, respectively.

KEY FINDINGS

Administration of low doses of LPS repressed the production of IL-6 and IL-10, however this effect was abolished with the inhibition of NOS activity and by TSA in the case of IL-10. Tolerance modulates the activity of HAT and, consequently, the acetylation of histones H3 and H4. Inhibition of NO decreases acetylation of Histones. The HDACs 2 and 3 were nitrosylated after the tolerance induction.

SIGNIFICANCE

The tolerance to LPS regulates the cytokine production by modulating chromatin structure and this event is NO dependent.

Nutritional control of immunity: Balancing the metabolic requirements with an appropriate immune function

The immune system is a highly integrated network of cells sensitive to a number of environmental factors. Interestingly, recent years have seen a dramatic increase in our understanding of how diet makes a crucial contribution to human health, affecting the immune system, secretion of adipocytokines and metabolic pathways. Recent experimental evidence indicates that diet and its components are able to profoundly influence immune responses, thus affecting the development of inflammatory and autoimmune diseases. This review aims to discuss some of the main topics concerning the impact of nutrients and their relative composition on immune cell development and function that may be particularly important for regulating the balance between inflammatory and tolerogenic processes. We also highlight the effects of diet on commensal bacteria and how changes in the composition of the microbiota alter intestinal and systemic immune homeostasis. Finally, we summarize the effects of dietary compounds on epigenetic mechanisms involved in the regulation of several immune related genes.

T cell metabolism drives immunity

Buck et al. discuss the role of lymphocyte metabolism on immune cell development and function.

Lymphocytes must adapt to a wide array of environmental stressors as part of their normal development, during which they undergo a dramatic metabolic remodeling process. Research in this area has yielded surprising findings on the roles of diverse metabolic pathways and metabolites, which have been found to regulate lymphocyte signaling and influence differentiation, function and fate. In this review, we integrate the latest findings in the field to provide an up-to-date resource on lymphocyte metabolism.