Lineage-specific silencing of human IL-10 gene expression by promoter methylation in cervical cancer cells

Methylation levels of the IL10 gene in peripheral blood are related to the intractability of Graves' disease

The prognosis of autoimmune thyroid diseases (AITDs), including Hashimoto's disease (HD) and Graves' disease (GD), is difficult to predict. DNA methylation regulates gene expression of immune mediating factors. Interleukin (IL)-10 is a Th2 cytokine that downregulates inflammatory cytokines produced by Th1 cells. To clarify the role of methylation of the IL10 gene in the prognosis of AITD, we evaluated the methylation levels of two CpG sites in the IL10 promoter using pyrosequencing. The methylation levels of the -185 CpG site of the IL10 gene were related to age and GD intractability in GD patients. Furthermore, the C carrier of the IL10-592 A/C polymorphism was related to low methylation levels of the -185 CpG site. The methylation levels of the IL10-185 CpG site of the IL10 gene were related to the intractability of GD and were lower in individuals with the C allele of the IL10-592 A/C polymorphism.

IL10 hypomethylation is associated with the risk of gastric cancer

Interleukin-10 (IL10), a pleiotropic cytokine secreted by type-2 helper (Th2) T cells, contributes to the oncogenic activation or inactivation of tumor-suppressor genes. The present study investigated whether hypomethylation of IL10 CpG island (CGI) was associated with the risk of developing gastric cancer (GC) and the prognosis of patients with GC. A fragment (hg18, chr1: 206945638-206945774) at the CGI of IL10 was selected for the present methylation assay. Quantitative methylation-specific PCR was used to evaluate the methylation of IL10 CGI in 117 tumor samples from patients with GC. The results demonstrated that IL10 CGI methylation was significantly lower in the tumor tissues compared with that in the paired adjacent non-tumor tissues (median percentage of methylated reference, 29.16 vs. 42.82%, respectively; P=4×10⁻⁸). Furthermore, results from receiver operating characteristic curve analysis identified a significant area under the curve of 0.706, with a sensitivity and a specificity of 77.8 and 58.1%, respectively, between cancer tissues and paired adjacent non-tumor tissues. Furthermore, the methylation of IL10 CGI was significantly associated with patients' age at diagnosis (r=−0.201; P=0.03). Subgroup analyses demonstrated that the association between IL10 CGI hypomethylation and the risk of GC was specific for patients with low differentiation (P=1×10⁻⁷) and Borrmann types III+IV (P=1×10⁻⁷). In addition, IL10 CGI hypomethylation was significantly associated with the risk of GC for patients without smoking history (P=3×10⁻⁷) or a family history of cancer (P=2×10⁻⁷). The results from Kaplan-Meier survival analysis demonstrated that IL10 CGI hypomethylation was associated with a significantly shorter overall survival of patients with GC (P=0.041). Similar results were identified for patients with GC who did not have smoking history (P=0.037) or a family history of cancer (P=0.049). The results from this study demonstrated that IL10 CGI hypomethylation may be considered as a potential biomarker for the diagnosis and prognosis of patients with GC in the Chinese population.

Prostaglandin E2 Reverses the Effects of DNA Methyltransferase Inhibitor and TGFB1 on the Conversion of Naive T Cells to iTregs

Naturally occurring regulatory T cells (nTregs) are produced under thymic (tTregs) or peripherally induced (pTregs) conditions in vivo. On the other hand, Tregs generated from naive T cells in vitro under some circumstances, such as treatment with transforming growth factor-β (TGFB), are called induced Tregs (iTregs). Tregs are especially characterized by FOXP3 expression, which is mainly controlled by DNA methylation. nTregs play important roles in the suppression of immune response and self-tolerance. The prostaglandin E2 (PGE2) pathway was reported to contribute to regulatory functions of tumor-infiltrating nTregs. In this study, we examined whether PGE2 contributes to the formation of iTregs treated with TGFB1 and 5-aza-2'-deoxycytidine (5-aza-dC), which is a DNA methyltransferase inhibitor. We found that the protein and gene expression levels of FOXP3 and IL-10 were increased in 5-aza-dC and TGFB1-treated T cells in vitro. However, the addition of PGE2 to these cells reversed these increments significantly. In CFSE-based cell suppression assays, we demonstrated that PGE2 decreased the suppressive functions of 5-aza-dC and TGFB1-treated T cells.

Epigenetical Targeting of the FOXP3 Gene by S-Adenosylmethionine Diminishes the Suppressive Capacity of Regulatory T Cells Ex Vivo and Alters the Expression Profiles

Regulatory T cells (Treg cells), a subgroup of CD4 lymphocytes, play a crucial role in serving as an immune suppressor and in maintaining peripheral tolerance. As the accumulation of Treg cells in the tumor microenvironment is significantly associated with a decreased survival time of patients, they are considered as an important therapeutic target in the immunotherapy of human cancers. These cells are either derived from the thymus, which are called (CD4CD25CD127) natural Treg cells (nTreg cells), or they are generated from CD4CD25 naive T cells by transforming growth factor-beta 1 and interleukin 2 (IL-2) in the periphery, which are called induced Treg cells (iTreg cells). Although iTreg cells are unstable, nTreg cells stably express forkhead box P3 (FOXP3) protein. Moreover, nTreg cells can be classified as memory (CD45RA) and naive (CD45RA) Treg cells, and this classification is based on the expression of CD45RA. FOXP3, which is a master regulator transcription factor, is essential for the functions of Treg cells, and it is mainly controlled by epigenetic mechanisms. The cyclooxygenase 2 (COX2)/prostaglandin E2 (PGE2) pathway is also reported to contribute to the regulatory functions of tumor-infiltrating Treg cells. As a new approach, we investigated whether S-adenosylmethionine (SAM), a substrate of DNA methyltransferase, attenuates the immune-suppressive capacity of the naive subtype of nTreg cells (CD4CD25CD127CD45RA). Moreover, we examined the effects of PGE2/COX2 pathway blockers on the suppressive capacity of Treg cells. We found that SAM diminished the suppression competency of Treg cells by decreasing the FOXP3 mRNA and protein levels in a dose-dependent manner. SAM increased the DNA methylation of FOXP3 at the first intron site. In addition, SAM decreased the mRNA and protein levels of the IL-10 cytokine, which has suppressive roles in the immune system. Moreover, mRNA levels of interferon gamma (IFNG) were found to be increased. COX2 inhibition and blockage of PGE2 receptors also reduced the protein and mRNA levels of IL-10, but they did not exhibit any significant effect on Treg cells' suppression in the coculture system. Our results show that SAM might be considered and investigated as a promising agent for immunotherapy in the future.

IL-10 promoter hypomethylation is associated with increased IL-10 expression and poor survival in hepatocellular carcinoma

Background

Epigenetic alterations of tumor-associated genes contribute to the pathogenesis of virtually all cancer types. We evaluated the methylation status of the interleukin-10 (IL-10) gene promoter and assessed its association with IL-10 mRNA expression and clinical prognosis in hepatocellular carcinoma (HCC) patients.

Methods

Methylation-specific polymerase chain reaction (MSP) and real-time polymerase chain reaction (PCR) were used to define the methylation index (MI) of the IL-10 gene and quantify IL-10 mRNA expression in 120 HCC samples and paired non-tumor tissues.

Results

Mean MI was 0.47 in HCC specimens and 0.59 in non-tumor controls, and was associated with metastasis classification and serum α-fetoprotein (AFP) levels. IL-10 mRNA levels [mean –∆∆Ct of 1.678 in HCC cases with hypomethylation (∆MI ≤0) and –0.18 in HCC cases with hypermethylation (∆MI >0)] also correlated with metastasis classification and serum AFP. An association was detected between IL-10 mRNA and its gene’s MI in HCC. Also, an association was found between IL-10 hypomethylation, but not IL-10 mRNA expression and reduced postoperative HCC survival.

Conclusions

These results indicate that IL-10 promoter hypomethylation is associated with increased IL-10 mRNA levels and indicative of poor survival in HCC.

5-azacytidine promotes an inhibitory T-cell phenotype and impairs immune mediated antileukemic activity

Demethylating agent, 5-Azacytidine (5-Aza), has been shown to be active in treatment of myeloid malignancies. 5-Aza enhances anticancer immunity, by increasing expression of tumor-associated antigens. However, the impact of 5-Aza immune responses remains poorly understood. Here, T-cell mediated tumor immunity effects of 5-Aza, are investigated in vitro and in vivo. T-cells from healthy donors were treated with 5-Aza and analyzed by qRT-PCR and flow cytometry for changes in gene expression and phenotype. Functionality was assessed by a tumor lysis assay. Peripheral blood from patients treated with 5-Aza after alloSCT was monitored for changes in T-cell subpopulations. 5-Aza treatment resulted in a decrease in CD8+ T-cells, whereas CD4+ T-cells increased. Furthermore, numbers of IFN-γ+ T-helper 1 cells (Th1) were reduced, while Treg-cells showed substantial increase. Additionally, CD8+ T-cells exhibited limited killing capacity against leukemic target cells. In vivo data confirm the increase of Treg compartment, while CD8+ T-effector cell numbers were reduced. 5-Aza treatment results in a shift from cytotoxic to regulatory T-cells with a functional phenotype and a major reduction in proinflammatory Th1-cells, indicating a strong inhibition of tumor-specific T-cell immunity by 5-Aza.

Effects of resveratrol on the expression and DNA methylation of cytokine genes in diabetic rat aortas

This paper studies the expression of proinflammatory cytokines such as IL-1β, IL-6, TNF-α, and IFN-γ and anti-inflammatory cytokines such as IL-10 in diabetic rat aortas, the effects of resveratrol on these cytokines, and the potential epigenetic mechanisms involved. The experiment was performed on rats divided into four groups: normal group (NC), normal interventional group (NB), diabetic group (DM), and diabetic interventional group (DB). The NB and DB groups were treated with resveratrol. After more than 3 months, the rats' aortas were removed and analyzed for cytokines by using immunohistochemistry, Western blotting, real-time PCR, and methylation-specific PCR. Histological localization of these cytokines was mainly found in the arterial intima of diabetic rats. The protein and mRNA expression levels of IL-1β, IL-6, TNF-α, and IFN-γ were significantly higher in the DM group than in the NC group (p < 0.05), whereas in the resveratrol-treated groups (NB and DB), the levels were relatively lower than those in the corresponding groups. The DM group showed reduced levels of DNA methylation at the specific cytosine phosphate guanosine sites of IL-1β, IL-6, TNF-α, and IFN-γ, relative to those in the NC group (p < 0.01), and these levels were increased by resveratrol. In contrast, IL-10 was dramatically methylated and showed decreased expression in response to high glucose, and resveratrol reversed this effect. These results demonstrate that the inflammatory response is involved in diabetic macroangiopathy. Resveratrol inhibits the expression of proinflammatory cytokines and thus may have a protective effect on the aorta in hyperglycemia. Thus, DNA methylation, an epigenetic gene silencing signal, may be responsible for these two phenomena.

Epigenetic control of cytokine gene expression: regulation of the TNF/LT locus and T helper cell differentiation

Epigenetics encompasses transient and heritable modifications to DNA and nucleosomes in the native chromatin context. For example, enzymatic addition of chemical moieties to the N-terminal "tails" of histones, particularly acetylation and methylation of lysine residues in the histone tails of H3 and H4, plays a key role in regulation of gene transcription. The modified histones, which are physically associated with gene regulatory regions that typically occur within conserved noncoding sequences, play a functional role in active, poised, or repressed gene transcription. The "histone code" defined by these modifications, along with the chromatin-binding acetylases, deacetylases, methylases, demethylases, and other enzymes that direct modifications resulting in specific patterns of histone modification, shows considerable evolutionary conservation from yeast to humans. Direct modifications at the DNA level, such as cytosine methylation at CpG motifs that represses promoter activity, are another highly conserved epigenetic mechanism of gene regulation. Furthermore, epigenetic modifications at the nucleosome or DNA level can also be coupled with higher-order intra- or interchromosomal interactions that influence the location of regulatory elements and that can place them in an environment of specific nucleoprotein complexes associated with transcription. In the mammalian immune system, epigenetic gene regulation is a crucial mechanism for a range of physiological processes, including the innate host immune response to pathogens and T cell differentiation driven by specific patterns of cytokine gene expression. Here, we will review current findings regarding epigenetic regulation of cytokine genes important in innate and/or adaptive immune responses, with a special focus upon the tumor necrosis factor/lymphotoxin locus and cytokine-driven CD4+ T cell differentiation into the Th1, Th2, and Th17 lineages.

The pathogenesis of vitiligo

BACKGROUND

Vitiligo is a commonly encountered pigmentary disorder. Numerous studies and investigations from all over the world have attempted to determine the mechanisms behind this disease; however, the pathogenesis of vitiligo remains elusive.

OBJECTIVE

n this comprehensive review article, we present the findings behind the five overarching theories of what causes this disfiguring and psychologically debilitating disease.

METHOD

We begin our discussion with the role of genetic predisposition and move onward to the neural theory first proposed in the 1950s. Next we discuss the autoimmune hypothesis, followed by the reactive oxygen species model, and conclude by describing the findings of the more recent melanocytorrhagy hypothesis.

CONCLUSION

Although the exact pathogenesis of vitiligo is uncertain, each of these theories likely plays a role. Understanding each theory would pave the way for therapeutic advances for this disease.

Cell type-specific regulation of IL-10 expression in inflammation and disease

IL-10 plays an essential part in controlling inflammation and instructing adaptive immune responses. Consequently, dysregulation of IL-10 is linked with susceptibility to numerous infectious and autoimmune diseases in mouse models and in humans. It has become increasingly clear that appropriate temporal/spatial expression of IL-10 may be the key to how IL-10 contributes to the delicate balance between inflammation and immunoregulation. The mechanisms that govern the cell type- and receptor-specific induction of IL-10, however, remain unclear. This is due largely to the wide distribution of cellular sources that express IL-10 under diverse stimulation conditions and in a variety of tissue compartments. Further complicating the issue is the fact that human IL-10 expression patterns appear to be under genetic influence resulting in differential expression and disease susceptibility. In this review, we discuss the cellular sources of IL-10, their link to disease phenotypes and the molecular mechanisms implicated in IL-10 regulation.

Abnormal DNA methylation in peripheral blood mononuclear cells from patients with vitiligo

BACKGROUND

Vitiligo is a skin disorder characterized by the destruction of melanocytes by autoreactive lymphocytes. The genetic and environmental factors that trigger the autoimmune response are poorly understood. However, alterations to epigenetic DNA methylation patterns contribute to many other autoimmune diseases.

OBJECTIVES

To investigate genomic and gene-specific DNA methylation levels in peripheral blood mononuclear cells (PBMCs) of patients with vitiligo and to relate any changes to the expression of genes that regulate methylation, as well as the autoimmune-related gene IL10.

METHODS

We quantified global methylcytosine levels in PBMCs from 20 patients with vitiligo and 20 healthy controls. mRNA levels of DNA methyltransferases (DNMTs), methyl-DNA binding domain proteins (MBDs) and interleukin (IL)-10 were measured by real-time reverse transcriptase-polymerase chain reaction. Methylation of an IL10 regulatory element domain was determined by bisulphite genomic sequencing.

RESULTS

Genomic DNA methylation in PBMCs of patients with vitiligo was increased relative to healthy controls (P = 0·012). DNMT1, MBD1, MBD3, MBD4 and MeCP2 expression was significantly higher than in control PBMCs (P = 0·013, 0·001, 0·005, 0·001 and 0·001, respectively). MBD1 and MBD3 expression correlated positively with global DNA methylation in vitiligo PBMCs (MBD1: r = 0·519, P = 0·019; MBD3: r = 0·529, P = 0·016). IL10 expression was significantly decreased (P = 0·030), and an IL-10 enhancer region was hypermethylated in vitiligo PBMCs compared with controls (P = 0·014).

CONCLUSIONS

These data show that levels of DNA methylation are altered in PBMCs of patients with vitiligo, and this may contribute to disease activity by affecting the expression of autoimmunity-related genes.

Regulation of NF-kappaB responses by epigenetic suppression of IkappaBalpha expression in HCT116 intestinal epithelial cells

Intestinal epithelial cells play critical roles in regulating mucosal immunity. Since epigenetic factors such as DNA methylation and histone modifications are implicated in aging, carcinogenesis, and immunity, we set out to assess any role for epigenetic factors in the regulation of intestinal epithelial cell immune responses. Experiments were conducted using the HCT116 cell line, and a subclone was genetically engineered to lack DNA methyltransferases (DNMT). The induction of the chemokine interleukin-8 and the antiapoptotic protein cFLIP by tumor necrosis factor-alpha were markedly less in HCT116 cells lacking DNMT than in parental cells. These effects were accompanied by lower monocyte chemotaxis and higher caspase signaling in HCT116 cells lacking DNMT than parental cells. Tumor necrosis factor-alpha-induced NF-kappaB activation was blocked and IkappaBalpha expression was higher in HCT116 cells lacking DNMT than in parental cells. A CpG island in the IkappaBalpha gene promoter region was found to contain variable levels of methylation in parental HCT116 cells. Chromatin immunoprecipitation analysis of histone proteins bound to the IkappaBalpha gene promoter revealed that higher levels of IkappaBalpha expression in HCT116 cells lacking DNMT compared with parental cells were accompanied by more chromatin marks permissive to gene transcription. These findings show that epigenetic factors influence the NF-kappaB system in intestinal epithelial cells, resulting in a previously unrecognized mechanism of innate immune regulation.

Epigenetic alterations in cervical carcinogenesis

During cervical carcinogenesis, the major etiologic factor, the persistent oncogenic HPV infection itself is not sufficient to immortalize and transform the epithelial host cells. Together with further genetic and epigenetic alterations disrupting the cell cycle control, the host cell acquires immortal phenotype and progresses further to an overt malignant and invasive phenotype. Here, we discuss how cancer-associated epigenetic alterations can affect the expression of papillomaviral as well as host genes in relation to stages representing the multistep process of carcinogenesis. Biomarker roles in clinical diagnosis and prognosis might be assigned to the epigenetic pattern of the involved genes.