Epigenetic remodeling of the immune landscape in cancer: therapeutic hurdles and opportunities

The tumor immune microenvironment represents a sophisticated ecosystem where various immune cell subtypes communicate with cancer cells and stromal cells. The dynamic cellular composition and functional characteristics of the immune landscape along the trajectory of cancer development greatly impact the therapeutic efficacy and clinical outcome in patients receiving systemic antitumor therapy. Mounting evidence has suggested that epigenetic mechanisms are the underpinning of many aspects of antitumor immunity and facilitate immune state transitions during differentiation, activation, inhibition, or dysfunction. Thus, targeting epigenetic modifiers to remodel the immune microenvironment holds great potential as an integral part of anticancer regimens. In this review, we summarize the epigenetic profiles and key epigenetic modifiers in individual immune cell types that define the functional coordinates of tumor permissive and non-permissive immune landscapes. We discuss the immunomodulatory roles of current and prospective epigenetic therapeutic agents, which may open new opportunities in enhancing cancer immunotherapy or overcoming existing therapeutic challenges in the management of cancer.

Analysis of the Prognosis Prediction Ability of a Necroptosis-Related Gene Signature and its Relationship With the Hepatocellular Carcinoma Immune Microenvironment Using Bioinformatics Analysis and Experimental Validation

Background: Hepatocellular carcinoma (HCC) is one of the most malignant cancers and has a poor prognosis. The immune microenvironment is closely related to the drug sensitivity of a tumor. Necroptosis was reported to be a key factor for HCC. The prognostic value of necroptosis-related genes and their association with the tumor immune microenvironment are still unknown. Methods: Necroptosis-related genes that could comprise a signature for predicting the prognosis of HCC cases were identified using univariate analysis and least absolute shrinkage and selection operator Cox regression analysis. The association between this prognosis prediction signature and HCC immune microenvironment was analyzed. The immunological activities and drug sensitivities were compared between different risk score groups identified using the prognosis prediction signature. The expression levels of the five genes comprising the signature were validated using RT-qPCR. Results: A prognosis prediction signature consisting of five necroptosis-related genes was constructed and validated. Its risk score was = (0.1634 × PGAM5 expression) + (0.0134 × CXCL1 expression) - (0.1007 × ALDH2 expression) + (0.2351 × EZH2 expression) - (0.0564 × NDRG2 expression). The signature was found to be significantly associated with the infiltration of B cells, CD4⁺ T cells, neutrophils, macrophages, and myeloid dendritic cells into the HCC immune microenvironment. The number of infiltrating immune cells and the expression levels of immune checkpoints in the immune microenvironment of high-risk score patients were higher. Sorafenib and immune checkpoint blockade were determined to be ideally suited for treating high-risk score patients and low-risk score patients, respectively. Finally, RT-qPCR results confirmed that the expression levels of EZH2, NDRG2, and ALDH2 were significantly down-regulated in HuH7 and HepG2 cells compared to those in LO2 cells. Conclusion: The necroptosis-related gene signature developed herein can classify patients with HCC according to prognosis risk well and is associated with infiltration of immune cells into the tumor immune microenvironment.

EZH2: Its regulation and roles in immune disturbance of SLE

The pathogenesis of systemic lupus erythematosus (SLE) is related to immune homeostasis imbalance. Epigenetic mechanisms have played a significant role in breaking immune tolerance. Enhancer of zeste homolog 2 (EZH2), the specific methylation transferase of lysine at position 27 of histone 3, is currently found to participate in the pathogenesis of SLE through affecting multiple components of the immune system. This review mainly expounds the mechanisms underlying EZH2-mediated disruption of immune homeostasis in SLE patients, hoping to provide new ideas in the pathogenesis of SLE and new targets for future treatment.

Histone Methylation Related Therapeutic Challenge in Cardiovascular Diseases

The epidemic of cardiovascular diseases (CVDs) is predicted to spread rapidly in advanced countries accompanied by the high prevalence of risk factors. In terms of pathogenesis, the pathophysiology of CVDs is featured by multiple disorders, including vascular inflammation accompanied by simultaneously perturbed pathways, such as cell death and acute/chronic inflammatory reactions. Epigenetic alteration is involved in the regulation of genome stabilization and cellular homeostasis. The association between CVD progression and histone modifications is widely known. Among the histone modifications, histone methylation is a reversible process involved in the development and homeostasis of the cardiovascular system. Abnormal methylation can promote CVD progression. This review discusses histone methylation and the enzymes involved in the cardiovascular system and determine the effects of histone methyltransferases and demethylases on the pathogenesis of CVDs. We will further demonstrate key proteins mediated by histone methylation in blood vessels and review histone methylation-mediated cardiomyocytes and cellular functions and pathways in CVDs. Finally, we will summarize the role of inhibitors of histone methylation and demethylation in CVDs and analyze their therapeutic potential, based on previous studies.

Identification of biomarkers, pathways and potential therapeutic target for docetaxel resistant prostate cancer

Docetaxel has been proved to provide survival benefit for advanced prostate cancer (PCa) patients. Resistance to docetaxel further reduces the survival of these patients. Herein, we performed a comprehensive bioinformatic analysis to identify differentially expressed genes (DEGs) between docetaxel sensitive and resistant PCa (DRPC) cell based on Gene Expression Omnibus (GEO) database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were applied for functional and pathway analysis of DEGs. The STRING database, cytoscape software and plug-in 'cytoHubba' were used to construct protein-protein interaction (PPI) networks and identify hub genes. Survival analysis were performed via GEPIA database. Finally, we conducted immune infiltration analysis by TIMER. A total of 460 DEGs were identified. GO functional analysis showed that these DEGs are mainly enriched in chemotaxis, negative regulation of intracellular signal transduction, and regulation of cell adhesion, positive regulation of inflammatory response, regulation of response to cytokine stimulus. According to the results of KEGG pathway analysis, these DEGs are mainly involved in signaling by Rho GTPases, Miro GTPases and RHOBTB3; interferon Signaling; arginine biosynthesis; PI3K-Akt signaling pathway; cytokine-cytokine receptor interaction; MAPK signaling pathway. Finally, CCNB1 and EZH2 were identified as prognostic hub genes and the expression of these two genes were associated with immune infiltration. The present study may helps to improve the understanding of the molecular mechanisms of DRPC and facilitate the selection of therapeutic and prognostic biomarkers for DRPC.

DZNep attenuates allergic airway inflammation in an ovalbumin-induced murine model

BACKGROUND

Growing evidence shows that enhancer of zeste homolog 2 (EZH2) plays a role in various physiological functions and cancer pathogenesis. However, its contribution to allergic diseases remains controversial. We sought to investigate the role of EZH2 in the pathogenesis of allergic airway inflammation.

METHODS

3-Deazaneplanocin A (DZNep), an indirect inhibitor of EZH2, was administered via intraperitoneal injection in an ovalbumin (OVA)-induced murine model of allergic airway inflammation. The expression of EZH2 in the allergic airway tissues was examined by immunohistochemistry (IHC) and western blot. The inflammatory cell infiltration and the goblet cell hyperplasia in the murine nose and lung were detected by hematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining. Levels of cytokines, including IL-4, IFN-γ, IL-6, and IL-10, were evaluated in the bronchoalveolar lavage fluid (BALF) using Enzyme-linked immune sorbent assay (ELISA).

RESULTS

EZH2 expression was inhibited by DZNep treatment (P < 0.05). The administration of DZNep significantly inhibited the inflammatory cell infiltration (P < 0.0001) and goblet cell hyperplasia (P < 0.001). Moreover, it suppressed the secretion of IL-4 (P < 0.0001) and IL-6 (P < 0.01) in the BALF.

CONCLUSIONS

Our findings demonstrate that DZNep attenuates allergic airway inflammation and could be a new therapeutic option for allergic rhinitis and asthma.

Inhibition of EZH2 ameliorates bacteria-induced liver injury by repressing RUNX1 in dendritic cells

Fulminant hepatic failure (FHF) is a clinical syndrome characterized by a sudden and severe impairment in liver function. However, the precise mechanism of immune dysregulation that is significant to FHF pathogenesis remains unclear. Enhancer of zeste homolog 2 (EZH2) has been implicated in inflammation as a regulator of immune cell function. In this study, we investigated the role of EZH2 in an animal model of human FHF induced by Propionibacterium acnes (P. acnes) and lipopolysaccharide (LPS). We demonstrated that EZH2 depletion in dendritic cells (DCs) and pharmacological inhibition of EZH2 using GSK126 both significantly ameliorated liver injury and improved the survival rates of mice with P. acnes plus LPS-induced FHF, which could be attributed to the decreased infiltration and activation of CD4⁺ T cells in the liver, inhibition of T helper 1 cells and induction of regulatory T cells. The expression of EZH2 in DCs was increased after P. acnes administration, and EZH2 deficiency in DCs suppressed DC maturation and prevented DCs from efficiently stimulating CD4⁺ T-cell proliferation. Further mechanistic analyses indicated that EZH2 deficiency directly increased the expression of the transcription factor RUNX1 and thereby suppressed the immune functions of DCs. The functional dependence of EZH2 on RUNX1 was further illustrated in DC-specific Ezh2-deficient mice. Taken together, our findings establish that EZH2 exhibits anti-inflammatory effects through inhibition of RUNX1 to regulate DC functions and that inhibition of EZH2 alleviates P. acnes plus LPS-induced FHF, probably by inhibiting DC-induced adaptive immune responses. These results highlight the effect of EZH2 on DCs, serving as a guide for the development of a promising immunotherapeutic strategy for FHF.

EZH2: a novel target for cancer treatment

Enhancer of zeste homolog 2 (EZH2) is enzymatic catalytic subunit of polycomb repressive complex 2 (PRC2) that can alter downstream target genes expression by trimethylation of Lys-27 in histone 3 (H3K27me3). EZH2 could also regulate gene expression in ways besides H3K27me3. Functions of EZH2 in cells proliferation, apoptosis, and senescence have been identified. Its important roles in the pathophysiology of cancer are now widely concerned. Therefore, targeting EZH2 for cancer therapy is a hot research topic now and different types of EZH2 inhibitors have been developed. In this review, we summarize the structure and action modes of EZH2, focusing on up-to-date findings regarding the role of EZH2 in cancer initiation, progression, metastasis, metabolism, drug resistance, and immunity regulation. Furtherly, we highlight the advance of targeting EZH2 therapies in experiments and clinical studies.

Genetics and epigenetics of allergy

PURPOSE OF REVIEW

Allergic diseases are prototypic examples for gene × environment-wide interactions. This review considers the current evidence for genetic and epigenetic mechanisms in allergic diseases and highlights barriers and facilitators for the implementation of these novel tools both for research and clinical practice.

RECENT FINDINGS

The value of whole-genome sequencing studies and the use of polygenic risk score analysis in homogeneous well characterized populations are currently being tested. Epigenetic mechanisms are known to play a crucial role in the pathogenesis of allergic disorders, especially through mediating the effects of the environmental factors, well recognized risk modifiers. There is emerging evidence for the immune-modulatory role of probiotics through epigenetic changes. Direct or indirect targeting of epigenetic mechanisms affect expression of the genes favouring the development of allergic diseases and can improve tissue biology. The ability to specifically edit the epigenome, especially using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology, holds the promise of enhancing understanding of how epigenetic modifications function and enabling manipulation of cell phenotype for research or therapeutic purposes.

SUMMARY

Additional research in the role of genetic and epigenetic mechanisms in relation to allergic diseases' endotypes is needed. An international project characterizing the human epigenome in relation to allergic diseases is warranted.

Recent Advances in Clinical Allergy and Immunology 2019

The immune system has vital functions for homeostasis and host defense. Thus, imbalances of the immune system whether associated with allergy, hypersensitivity, or autoimmunity are of great importance, as is manifest from common diseases such as atopic diseases, urticaria, and angioedema, and drug hypersensitivity reactions. These can affect patients' quality of life and can generate high costs for health care. Epidemiological studies have provided evidence for changing patterns of allergic diseases caused by lifestyle and climate changes which have consequences for medical care. Deeper insights into the pathogenesis of allergic/immunologic diseases, combined with novel technologies, provide improved diagnostic options and treatment measures. This review will summarize novel aspects of the epidemiology, pathogenic mechanisms, as well as disease management in the fields of allergy and clinical immunology.

Ten-Eleven Translocation (TET) Enzymes Modulate the Activation of Dendritic Cells in Allergic Rhinitis

Background: The prevalence of allergic rhinitis (AR) has increased in recent decades. Accumulating evidence indicates that aberrant DNA demethylation modulated by enzymes of ten-eleven translocation (TET) promotes an imbalanced immune response.

Objective: This study aimed to explore TETs on the activation of dendritic cells (DCs) in AR.

Methods: The levels of TETs in peripheral blood mononuclear cells (PBMCs), peripheral myeloid DCs (mDCs), and plasmacytoid DCs (pDCs) from house dust mite (HDM)-sensitive AR patients and healthy volunteers (HC) were evaluated by qPCR and flow cytometry. The levels of 5-hydroxymethylcytosine (5hmC) and 5-methylcytosine (5mC) in PBMCs were determined by DNA-5hmC and DNA-5mC ELISA. The major HDM allergen, Dermatophagoides pteronyssinus (Der p 1), was used to stimulate atopic monocyte-derived DCs (moDCs) to assess its effect on the TETs. TET1 knockdown effect on the activation of non-atopic and atopic moDCs was investigated.

Results: TETs and global 5hmC were higher in PBMCs of AR than HC. So was TET1 in peripheral mDCs and pDCs of AR. In vitro, TET1 in atopic moDCs was significantly decreased by allergen challenge. Knockdown of TET1 in moDCs tended to induce CD86, CD80, and CD40 in AR but not in HC. TET1-knockdown moDCs significantly decreased the differentiation of activated regulatory T cells in AR.

Conclusion: DCs from AR patients express higher TET1 and are susceptible to be activated by TET1 decrease, which can be triggered by allergen challenge. Collectively, this suggests a role for TET in the pathogenesis of AR and potential for novel TET1-related, preventive, and therapeutic targets.