Search

MicroRNAs (miRs) are important posttranscriptional regulators of cell fate in both normal and disease states. miR-211 has previously been shown to be a direct regulator of metabolism in BRAFV600E-mutant melanoma cells in vitro. Here, we report that miR-211 expression promotes the aggressive growth of BRAFV600E-mutant melanoma xenografts in vivo. miR-211 promoted proliferation through the posttranscriptional activation of extracellular signal–regulated kinase (ERK) 5 signaling, which has recently been implicated in the resistance to BRAF and MAPK/ERK kinase inhibitors. We therefore examined whether miR-211 similarly modulated melanoma resistance to the BRAF inhibitor vemurafenib and the MAPK/ERK kinase inhibitor cobimetinib. Consistent with this model, miR-211 expression increased melanoma cell resistance to both the inhibitors, and this resistance was associated with an increased ERK5 phosphorylation. miR-211 mediates these effects by directly inhibiting the expression of DUSP6, an ERK5 pathway–specific phosphatase and now shown to be an miR-211 target gene. These results dissect the role of the miR-211–DUSP6-ERK5 axis in melanoma tumor growth and suggest a mechanism for the development of drug-resistant tumors and a target for overcoming resistance.

The clinical management of malignant melanoma remains a challenge because these tumors are intrinsically aggressive and prone to therapeutic resistance. Micro-RNA (miR)-211 is an emerging melanoma oncogene. Melanoma metabolism adapts to promote survival, including in response to BRAF(V600E) inhibition, but how miR-211 participates in this process is unknown. Here we generated miR-211 loss-of-function cell lines using CRISPR/Cas9 technology and show that miR-211 loss slowed growth and invasion in vitro, inhibited phosphoinositol-3-kinase (PI3K) signaling, and inhibited melanoma growth in vivo. MiR-211 deficiency rendered melanoma cells metabolically vulnerable by attenuating mitochondrial respiration and tricarboxylic acid (TCA) cycling. MiR-211 was upregulated by the BRAF inhibitor vemurafenib and in vemurafenib-resistant melanoma cells, with miR-211 loss rendering them more drug sensitive. MiR-211 loss represents a “two-pronged” anti-cancer strategy by inhibiting both critical growth-promoting cell signaling pathways and rendering cells metabolically vulnerable, making it an extremely attractive and specific candidate combinatorial therapeutic target in melanoma.

Inhibitors that block the programmed cell death-1 (PD-1) pathway can potentiate endogenous antitumor immunity and have markedly improved cancer survival rates across a broad range of indications. However, these treatments work for only a minority of patients. The efficacy of anti-PD-1 inhibitors may be extended by cytokines, however, the incorporation of cytokines into therapeutic regimens has significant challenges. In their natural form when administered as recombinant proteins, cytokine treatments are often associated with low response rates. Most cytokines have a short half-life which limits their exposure and efficacy. In addition, cytokines can activate counterregulatory pathways, in the case of immune-potentiating cytokines this can lead to immune suppression and thereby diminish their potential efficacy. Improving the drug-like properties of natural cytokines using protein engineering can yield synthetic cytokines with improved bioavailability and tissue targeting, allowing for enhanced efficacy and reduced off-target effects. Using structure guided engineering we have designed a novel class of antibody-cytokine fusion proteins consisting of a PD-1 targeting antibody fused together with an interleukin-21 (IL-21) cytokine mutein. Our bifunctional fusion proteins can block PD-1/programmed death-ligand 1 (PD-L1) interaction whilst simultaneously delivering IL-21 cytokine to PD-1 expressing T cells. Targeted delivery of IL-21 can improve T cell function in a manner that is superior to anti-PD-1 monotherapy. Fusion of engineered IL-21 variants to anti-PD1 antibodies can improve the drug-like properties of IL-21 cytokine leading to improved cytokine serum half-life allowing for less frequent dosing. In addition, we show that targeted delivery of IL-21 can minimize any potential detrimental effect on local antigen-presenting cells. A highly attenuated IL-21 mutein variant (R9E:R76A) fused to a PD-1 antibody provides protection in a humanized mouse model of cancer that is refractory to anti-PD-1 monotherapy. Collectively, our preclinical data demonstrate that this approach may improve upon and extend the utility of anti-PD-1 therapeutics currently in the clinic.

Background Cinnamomum cassia bark is the outer skin of an evergreen tall tree belonging to the family Lauraceae containing several active components such as essential oils (cinnamic aldehyde and cinnamyl aldehyde), tannin, mucus and carbohydrate. They have various biological functions including anti-oxidant, anti-microbial, anti-inflammation, anti-diabetic and anti-tumor activity. Previously, we have reported that anti-cancer effect of cinnamon extracts is associated with modulation of angiogenesis and effector function of CD8+ T cells. In this study, we further identified that anti-tumor effect of cinnamon extracts is also link with enhanced pro-apoptotic activity by inhibiting the activities NFκB and AP1 in mouse melanoma model. Methods Water soluble cinnamon extract was obtained and quality of cinnamon extract was evaluated by HPLC (High Performance Liquid Chromatography) analysis. In this study, we tested anti-tumor activity and elucidated action mechanism of cinnamon extract using various types of tumor cell lines including lymphoma, melanoma, cervix cancer and colorectal cancer in vitro and in vivo mouse melanoma model. Results Cinnamon extract strongly inhibited tumor cell proliferation in vitro and induced active cell death of tumor cells by up-regulating pro-apoptotic molecules while inhibiting NFκB and AP1 activity and their target genes such as Bcl-2, BcL-xL and survivin. Oral administration of cinnamon extract in melanoma transplantation model significantly inhibited tumor growth with the same mechanism of action observed in vitro. Conclusion Our study suggests that anti-tumor effect of cinnamon extracts is directly linked with enhanced pro-apoptotic activity and inhibition of NFκB and AP1 activities and their target genes in vitro and in vivo mouse melanoma model. Hence, further elucidation of active components of cinnamon extract could lead to development of potent anti-tumor agent or complementary and alternative medicine for the treatment of diverse cancers.

The microRNA MIR211 is an important regulator of melanoma tumor cell behavior. Previous studies suggested that in certain tumors, MIR211 acted as a tumor suppressor while in others it behaved as an oncogenic regulator. When MIR211 is expressed in BRAFV600E-mutant A375 melanoma cells in mouse xenografts, it promotes aggressive tumor growth accompanied by increased cellular proliferation and angiogenesis. We demonstrate that MIR211 is transferred to adjacent cells in the tumor micro-environment via exosomes. Cross-species genome-wide transcriptomic analysis showed that human tumor-derived MIR211 interacts with the mouse transcriptome in the tumor microenvironment, and activates ERK5 signaling in human tumor cells via the modulation of a feedback loop. Human miR211 directly inhibits human DUSP6 protein phosphatase at the post-transcriptional level. We provide support for the hypothesis that DUSP6 inhibition conferred resistance of the human tumor cells to the BRAF inhibitor vemurafenib and to the MEK inhibitor cobimetinib, with associated increases in ERK5 phosphorylation. These findings are consistent with a model in which MIR211 regulates melanoma tumor proliferation and BRAF inhibitor resistance by inducing ERK5 signaling within the complex tumor microenvironment. We propose that the MIR211-ERK5 axis represents an important and sensitive regulatory arm in melanoma with potential theranostic applications.

Clinical relapse and metastases are the major causes of death in melanoma. Currently, adoptive T cell therapy using tumor-infiltrating lymphocytes rich in cytotoxic CD8+ T cells (CTLs) is one of the promising approaches that helps overcome this major challenge in melanoma; however, CTL cell transfer alone does not improve clinical response, suggesting a supportive role of helper CD4+ T cells. There is increasing evidence on the potential contribution of tumor-infiltrated CD4+ T follicular helper (Tfh) cells and intratumoral lymphoid structure formation in tumor eradication; however to date, the role of Tfh cells in anti-tumor immunity has not been clearly elucidated. Remarkably, using a murine melanoma model, we found that the percentage of intratumoral Tfh cells negatively correlates with melanoma growth. In addition, we observed enhanced tumor growth in Bcl6 T-cell conditional knockout mice, which lack Tfh cells as compared to wild-type mice, suggesting that Tfh cells might play a protective role in tumor growth and could serve as a marker for tumor regression. Importantly, in support of mouse studies, in melanoma patients the number of Tfh cells correlate with the rate of patient survival. Importantly, adoptive transfer of antigen specific Tfh cells into tumor bearing mice results in increased number of intratumoral CTLs, as well as in an efficient tumor eradication, indicating the essential role of Tfh cells in promoting CTL expansion and anti-tumor reactivity. Our results thus, for the first time, indicate the therapeutic potential of Tfh cells in promoting CTL-mediated anti-tumor immunity against melanoma and provide the basis for potential usage of these cells to improve current immunotherapy approaches.

T-cell tolerance is a major obstacle to successful cancer immunotherapy; thus, developing strategies to break immune tolerance is a high priority. Here we show that expression of the E3 ubiquitin ligase Grail is upregulated in CD8+ T cells that have infiltrated into transplanted lymphoma tumours, and Grail deficiency confers long-term tumour control. Importantly, therapeutic transfer of Grail-deficient CD8+ T cells is sufficient to repress established tumours. Mechanistically, loss of Grail enhances anti-tumour reactivity and functionality of CD8+ T cells. In addition, Grail-deficient CD8+ T cells have increased IL-21 receptor (IL-21R) expression and hyperresponsiveness to IL-21 signalling as Grail promotes IL-21R ubiquitination and degradation. Moreover, CD8+ T cells isolated from lymphoma patients express higher levels of Grail and lower levels of IL-21R, compared with CD8+ T cells from normal donors. Our data demonstrate that Grail is a crucial factor controlling CD8+ T-cell function and is a potential target to improve cytotoxic T-cell activity., Grail is an E3 ubiquitin ligase that inhibits T-cell receptor signalling in CD4+ T cells. Here the authors show Grail also limits IL-21 receptor expression and function in CD8+ T cells, is overactive in these cells in patients with lymphoma, and promotes tumour development in a lymphoma transplant mouse model.

Vitiligo is a common, chronic skin disorder characterized by loss of epidermal melanocytes and progressive depigmentation. Vitiligo has complex immune, genetic, environmental, and biochemical etiology, but the exact molecular mechanisms of vitiligo development and progression, particularly those related to metabolic control, are poorly understood. Here we characterized the human vitiligo cell line PIG3V and the normal human melanocytes, HEM-l by RNA-sequencing (RNA-seq), targeted metabolomics, and shotgun lipidomics. Melanocyte-enriched miR-211, a known metabolic switch in non-pigmented melanoma cells, was severely downregulated in vitiligo cell line PIG3V and skin biopsies from vitiligo patients, while its predicted targets transcriptional co-activator PGC1-α (PPARGC1A), ribonucleotide reductase regulatory subunit M2 (RRM2), and serine-threonine protein kinase TAO1 (TAOK1) were reciprocally upregulated. miR-211 binds to PGC1-α 3’UTR locus and represses it. Although mitochondrial numbers were constant, mitochondrial complexes I, II, and IV and respiratory responses were defective in vitiligo cells. Nanoparticle-coated miR-211 partially augmented the oxygen consumption rate in PIG3V cells. The lower oxygen consumption rate, changes in lipid and metabolite profiles, and increased reactive oxygen species production observed in vitiligo cells appear to be partly due to abnormal regulation of miR-211 and its target genes. These genes represent potential biomarkers and therapeutic targets in human vitiligo.

The lncRNA SPRIGHTLY interacts with the intronic regions of unprocessed mRNA precursors of its target mRNAs., Molecular mechanisms by which long noncoding RNA (lncRNA) molecules may influence cancerous condition are poorly understood. The aberrant expression of SPRIGHTLY lncRNA, encoded within the drosophila gene homolog Sprouty-4 intron, is correlated with a variety of cancers, including human melanomas. We demonstrate by SHAPE-seq and dChIRP that SPRIGHTLY RNA secondary structure has a core pseudoknotted domain. This lncRNA interacts with the intronic regions of six pre-mRNAs: SOX5, SMYD3, SND1, MEOX2, DCTN6, and RASAL2, all of which have cancer-related functions. Hemizygous knockout of SPRIGHTLY by CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 in melanoma cells significantly decreases SPRIGHTLY lncRNA levels, simultaneously decreases the levels of its interacting pre-mRNA molecules, and decreases anchorage-independent growth rate of cells and the rate of in vivo tumor growth in mouse xenografts. These results provide the first demonstration of an lncRNA’s three-dimensional coordinating role in facilitating cancer-related gene expression in human melanomas.

The microRNA miR-211 is an established participant in melanomagenesis, but controversy exists as to whether it acts as a bone fide tumor suppressor or oncogene. Here we ectopically expressed miR-211 in the BRAF v600E-mutant A375 melanoma cell line and examined its effect in xenografts in vivo. The miR-211 ectopic expression promoted aggressive tumor xenograft growth with extensive cell proliferation, and angiogenesis. ChIP-seq and single cell sequencing analysis of xenograft tissues demonstrated that aggressive tumor formation is partly associated with H3K27me3 and H3K4me3, and migration of cells from mouse tissues to tumor locus. Interrogation of xenograft transcriptomics data revealed activation of the ERK5 pathway, itself negatively regulated by miR-211 target genes, BIRC2 and DUSP6, further confirmed as direct miR-211 target genes by RNA immunopurification with RNA-seq (RIP-seq) and site-directed mutagenesis. miR-211 conferred resistance to the BRAF inhibitor vemurafenib, and MEK inhibitor cobimetinib with corresponding increases in ERK5 phosphorylation. The miR-211-ERK5 axis may represent a novel therapeutic target, but however, miR-211 is exquisitely pleiotropic in the complex in vivo tumor environment and its context must be considered carefully in diagnostic and therapeutic development. Citation Format: Bongyong Lee, Anupama Sahoo, Junko Sawada, Dimitrios G. Zisoulis, John Marchica, Sanjay Sahoo, Fabiana I Alves De Lima Layng, Darren Finlay, Joseph Mazar, Piyush Joshi, Masanobu Komatsu, Kristiina Vuori, Garth Powis, Petrus R. de Jong, Animesh Ray, Ranjan J. Perera. microRNA-211 promotes aggressive melanoma growth in vivo by epigenetic modification, and contributes to BRAFV600E inhibitor resistance via ERK5 signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3550.

Clinical relapse and metastases are the major causes of death in melanoma. Currently, adoptive T cell therapy using tumor-infiltrating lymphocytes rich in cytotoxic CD8+ T cells (CTLs) is one of the promising approaches that helps overcome this major challenge in melanoma; however CTL cell transfer alone does not improve clinical response suggesting a role of helper CD4+ T cells. Recently, it has been noted that infiltration of a CD4+ T helper subset, named as T follicular helper (Tfh) cells into tumor sites correlates with increased survival of cancer patients; however their role in tumor immunity has not been clearly elucidated till date. In our hands, both pre-clinical murine tumor studies and patient studies show correlation between increased number of intratumoral Tfh cells and reduced melanoma tumor growth and improved survival, suggesting the novel function of Tfh cells in promoting anti-tumor immunity against melanoma. Remarkably, transfer of tumor antigen-specific Tfh cells in melanoma tumor-bearing mice results in increased intratumoral CTL number and function, as well as in more efficient tumor eradication, indicating the role of Tfh cells in antitumor immunity by promoting CTL expansion and/or activity. Moreover, we determined that Tfh derived cytokine interleukin (IL)-21 contributes to intratumoral CTL activity. Our results thus for first time indicate the therapeutic potential of Tfh cells in promoting anti-tumor immunity against melanoma and provide the basis for potential usage of these cells to improve current immunotherapy approaches.

T follicular helper (Tfh) cells play a key role in providing help to B cells during germinal center (GC) reactions. The generation and function of Tfh cells is regulated by multiple checkpoints including their early priming stage in T zones and throughout the effector stage of differentiation in GCs. Signaling pathways activated downstream of cytokine and costimulatory receptors as well as consequent activation of subset-specific transcriptional factors are essential steps for Tfh cell generation. While to date early signaling events for fate committed differentiation of Tfh cells are sufficiently studied, mechanisms allowing Tfh cells to maintain their commitment/programming are still unclear. Here we report that signal transducer and activator of transcription 1 (STAT1) deficiency in CD4+ T cells leads to a diminished number of Tfh cells at day 7 and 14 days after antigen immunization, while at day 3–4, number of Tfh cells was comparable between STAT1-sufficient and STAT1 deficient mice, suggesting the role of STAT1 in Tfh lineage maintenance rather than in Tfh cell priming. In fact, in both mouse and human Tfh cells interleukin (IL)-21 mRNA and protein expression is dependent on the presence of STAT1. Functionally, STAT1 in cooperation with STAT3, Batf, and IRF4 triggers IL-21 production in Tfh cells by directly binding to and activation of the IL-21 gene locus. Moreover, utilizing gene knockout approach, we have determined that Batf is a crucial connector to form STAT1/STAT3/Batf/IRF4 active complex for triggering IL-21 transcription. Our results thus indicate functional contribution of STAT1 towards regulation of IL-21 expression and Tfh lineage maturation/maintenance.

T follicular helper (Tfh) cells are specialized subset of T helper (Th) cells necessary for germinal center reaction, affinity maturation and the differentiation of germinal center B cells to antibody-producing plasma B cells and memory B cells. The differentiation of Tfh cells is a multistage, multifactorial process involving a variety of cytokines, surface molecules and transcription factors. While Tfh cells are critical components of protective immune responses against pathogens, regulation of these cells is crucial to prevent autoimmunity and airway inflammation. Recently, it has been noted that Tfh cells could be potentially implicated either in cancer progression or prevention. Thus, the elucidation of the mechanisms that regulate Tfh cell differentiation, function and fate should highlight potential targets for novel therapeutic approaches. In this review, we summarize the latest advances in our understanding of the regulation of Tfh cell differentiation and their role in health and disease.

Type 2 immunity is characterized by expression of the cytokines interleukin (IL)-4, IL-5, IL-9 and IL-13, which can function in mediating protective immunity in the host or possess a pathogenic role. T helper (Th) 2 cells have emerged to play a beneficial role in mediating anti-parasitic immunity and are also known to be key players in mediating allergic diseases. In addition to the Th2 cells, recent studies have identified T follicular helper (Tfh) cells as an alternative source of IL-4 to regulate type 2 humoral immune responses, indicating that Th2 and Tfh cells exhibit overlapping phenotypical and functional characteristics. Th2 and Tfh cells appear to utilize unique mechanisms for regulation of IL-4 expression; however unlike Th2 cells, the regulation and function of Tfh-derived IL-4 is not yet fully understood. Understanding of the molecular mechanisms for IL-4 expression and function in both cell subsets will lead to development of pharmacological approaches to regulate the function of IL-4 in different disease settings.

IL-9 regulates diverse inflammatory immune responses. Although the functional importance of IL-9 has been investigated in various pathophysiological conditions, molecular mechanisms by which TCR stimulation induced IL-9 gene expression are still unclear. In this study, we investigated the functional importance of the NFAT1 and NF-κB (p65) in IL-9 gene transcription in CD4(+) T cells. In vivo binding of NFAT1 and NF-κB (p65) to the IL-9 promoter was observed. NFAT1 binding induced a transcriptionally active chromatin configuration at the IL-9 promoter locus, whereas NF-κB (p65) binding transactivated the IL-9 promoter. Mouse deficient in NFAT1 shows a significant down-regulation of IL-9 expression that resulted from an inaccessible chromatin configuration at the IL-9 promoter. In parallel, knockdown of NF-κB (p65) also resulted in reduced IL-9 expression. In this process, NFAT1 plays a pivotal role as a core protein that creates an accessible platform for the assembly of transcription activators. The presence of NFAT1 correlates with recruitment of NF-κB (p65), p300, and active histone markers on the IL-9 promoter, resulting in a transcriptionally competent promoter. NFAT1 deficiency significantly reduced the recruitment of the above activation complex to the IL-9 promoter. In summary, our data suggest that functional cooperation of NFAT1 and NF-κB synergistically enhances IL-9 transcription in CD4(+) T cells.

IL-10 is a multifunctional cytokine that plays a crucial role in immunity and tolerance. IL-10 is produced by diverse immune cell types, including B cells and subsets of T cells. Although Th1 produce IL-10, their expression levels are much lower than Th2 cells under conventional stimulation conditions. The potential role of E26 transformation-specific 1 (Ets-1) transcription factor as a negative regulator for Il10 gene expression in CD4+ T cells has been implicated previously. In this study, we investigated the underlying mechanism of Ets-1–mediated Il10 gene repression in Th1 cells. Compared with wild type Th1 cells, Ets-1 knockout Th1 cells expressed a significantly higher level of IL-10, which is comparable with that of wild type Th2 cells. Upregulation of IL-10 expression in Ets-1 knockout Th1 cells was accompanied by enhanced chromatin accessibility and increased recruitment of histone H3 acetylation at the Il10 regulatory regions. Reciprocally, Ets-1 deficiency significantly decreased histone deacetylase 1 (HDAC1) enrichment at the Il10 regulatory regions. Treatment with trichostatin A, an inhibitor of HDAC family, significantly increased Il10 gene expression by increasing histone H3 acetylation recruitment. We further demonstrated a physical interaction between Ets-1 and HDAC1. Coexpression of Ets-1 with HDAC1 synergistically repressed IL-10 transcription activity. In summary, our data suggest that an interaction of Ets-1 with HDAC1 represses the Il10 gene expression in Th1 cells.

Interleukin-24 (IL-24) belongs to the IL-10 family of cytokines and is well known for its tumor suppressor activity. This cytokine is released by both immune and nonimmune cells and acts on non-hematopoietic tissues such as skin, lung and reproductive tissues. Apart from its ubiquitous tumor suppressor function, IL-24 is also known to be involved in the immunopathology of autoimmune diseases like psoriasis and rheumatoid arthritis. Although the cellular sources and functions of IL-24 are being increasingly investigated, the molecular mechanisms of IL-24 gene expression at the levels of signal transduction, epigenetics and transcription factor binding are still unclear. Understanding the specific molecular events that regulate the production of IL-24 will help to answer the remaining questions that are important for the design of new strategies of immune intervention involving IL-24. Herein, we briefly review the signaling pathways and transcription factors that facilitate, induce, or repress production of this cytokine along with the cellular sources and functions of IL-24.

CD4(+) T cells play critical roles in the generation of protective immunity against a variety of pathogens. The main two types of effector CD4(+) T cells, Th1 and Th2 are characterized by their ability to produce signature cytokines. Among them, IL-10 is a multi-functional cytokine that plays a crucial role in maintaining the balance between immunity and tolerance. Although IL-10 is produced by both differentiated primary Th1 and Th2 cells, Th2 cells produce much higher levels of IL-10 upon stimulation. However, little information is available on the molecular mechanisms of IL-10 gene regulation at the transcriptional level. Interferon regulatory factor IRF4 is a member of the IRF family of transcription factors and plays critical roles in the development of CD4(+) T cells into Th2 cells. In this present study, we elucidate the underlying mechanism of IRF4 mediated IL-10 gene transcription in primary CD4(+) T cells. Th2 specific binding of IRF4 to the IRF4 responsive elements in IL-10 locus potentiated IL-10 expression in Th2 cells. Knockdown of IRF4 by siRNA decreased IL-10 expression level in Th2 cells. Nuclear translocation of IRF4 was much higher in Th2 cells upon stimulation, which contribute to maintain IL-10(high) phenotype of Th2 cells. Collectively, our results suggest that stimulation driven quantitative differences of IRF4 in the nucleus and its binding to IL-10 regulatory elements are crucial mechanisms to induce IL-10(high) gene expression in Th2 cells.

To date, B cells are believed to play a central role in pathogenesis of various autoimmune diseases as loss of B-cell tolerance with emergence of autoreactive B cells and pathogenic autoantibodies are the hallmark features of autoimmune disorders; however the intrinsic mechanisms that underlie initial breaks in B cell tolerance have not been completely defined. GRAIL, gene related to anergy in lymphocytes (encoded by Rnf128) is an E3 ubiquitin ligase associated with CD4+ and CD8+ T cell tolerance. Our data for first time show GRAIL expression in both mouse and human B cells, with higher expression in anergic B cells and that GRAIL deficiency in B cells leads to impaired B cell peripheral tolerance induction and greater susceptibility to autoimmune diseases. GRAIL deficient B cells exhibited hyperresponsivness in terms of proliferation and antibody production upon antigen stimulation in vitro and in vivo. Concomitantly, GRAIL-deficient B cells were less efficient in downregulation of IgM after B cell receptor (BCR) crosslinking and exhibited increased CD79a expression and activation leading to elevated activation of proximal BCR-signaling components and Ca2+mobilization; GRAIL expression promoted CD79a ubiquitination and degradation. Interestingly, GRAIL expression is also essential to control antigen-presenting property of B cells towards T helper 1 (Th1), Th2, Th17 and follicular helper T (Tfh) cells; since GRAIL deficiency in B cells leads to augmented development and function of Th1, Th2, Th17 and Tfh cells in vitro and in vivo. Thus, our results indicate that GRAIL is a crucial intrinsic factor controlling B cell activation and tolerance by targeting of BCR component CD79a for degradation.

Alternative splicing of mRNA enables functionally diverse protein isoforms to be expressed from a single gene, allowing transcriptome diversification. Interleukin (IL)-24/MDA-7 is a member of the IL-10 gene family, and FISP (IL-4-induced secreted protein), its murine homologue, is selectively expressed and secreted by T helper 2 lymphocytes. A novel splice variant of mouse IL-24/FISP, designated FISP-sp, lacks 29 nucleotides from the 5′-end of exon 4 of FISP. The level of FISP-sp expression is 10% of the level of total primary FISP transcription. Unlike FISP, FISP-sp does not induce growth inhibition and apoptosis. FISP-sp is exclusively localized in endoplasmic reticulum, and its expression is up-regulated by endoplasmic reticulum stress. Our results suggest that the novel splicing variant FISP-sp dimerizes with FISP and blocks its secretion and inhibits FISP-induced apoptosis in vivo.

Apart from T helper (Th)-2 cells, T follicular helper (Tfh) cells are a major class of IL-4-producing T cells, required for regulation of type 2 humoral immunity; however, transcriptional control of IL-4 production in Tfh cells remains mainly unknown. Here, we show that the basic leucine zipper transcription factor ATF-like, Batf is important for IL-4 expression in Tfh cells rather than in canonical Th2 cells. Functionally, Batf in cooperation with interferon regulatory factor (IRF) 4 along with Stat3 and Stat6 trigger IL-4 production in Tfh cells by directly binding to and activation of the CNS2 region in the IL-4 locus. In addition, Batf-to-c-Maf signalling is an important determinant of IL-4 expression in Tfh cells. Batf deficiency impairs the generation of IL-4-producing Tfh cells that results in protection against allergic asthma. Our results thus indicate a positive role of Batf in promoting the generation of pro-allergic IL-4-producing Tfh cells., T follicular helper cells are a distinct subtype of CD4 T helper cells, which contributes to the regulation of type 2 humoral immunity by producing IL-4. Here, the authors identify Batf as an important transcription factor regulating IL-4 expression in T follicular helper cells but not in Th2 cells.

T follicular helper (Tfh) cells are a specialized subset of T helper cells necessary for germinal center reaction, affinity maturation, and the differentiation of germinal center B cells to antibody-producing plasma B cells and memory B cells. The differentiation of Tfh cells is a multistage, multifactorial process involving a variety of cytokines, surface molecules and transcription factors. While to date early signaling events for fate committed differentiation of Tfh cells are sufficiently studied, mechanisms allowing Tfh cells to maintain their commitment/programming are still unclear. Here we report that STAT1 deficiency in CD4+ T cells leads to diminished number of Tfh cells at day 7 and 14 days after antigen immunization, while at day 3–4, number of Tfh cell were comparable between STAT1-sufficient and STAT1-deficient mice, suggesting the role of STAT1 in Tfh lineage maintenance rather than in Tfh cell priming. Interestingly STAT 1 deficiency in both mouse and human Tfh cells leads to significant drop in IL-21 expression, while the expression of Tfh-specific genes such as Bcl6, CXCR5 and c-Maf was not affected. Functionally, STAT1 in cooperation with STAT3 triggers IL-21 production in Tfh cells by directly binding to and activation of the IL-21 gene locus. In addition, STAT1/STAT3 cooperation influences the expression of transcriptional factor Batf as well as determines Batf-driven IL-21 expression in Tfh cells. Our results thus indicate STAT1 dependent mechanism for IL-21 expression and Tfh lineage maturation and maintenance.

T helper (Th)-2 cells are the major players in allergic asthma; however, the mechanisms that control Th2-mediated inflammation are poorly understood. Here we find that enhanced expression of Grail, an E3 ubiquitin ligase, in Th2 cells depends on interleukin (IL)-4-signalling components, signal transducer and activator of transcription 6 (Stat6) and Gata3, that bind to and transactivate the Grail promoter. Grail deficiency in T cells leads to increased expression of Th2 effector cytokines in vitro and in vivo and Grail-deficient mice are more susceptible to allergic asthma. Mechanistically, the enhanced effector function of Grail-deficient Th2 cells is mediated by increased expression of Stat6 and IL-4 receptor α-chain. Grail interacts with Stat6 and targets it for ubiquitination and degradation. Thus, our results indicate that Grail plays a critical role in controlling Th2 development through a negative feedback loop.

Development of immunological tolerance has emerged as a critical mechanism for prevention of inflammatory and autoimmune diseases. Of the T helper (Th) subsets, the Th2 cells are the major players in allergic airway inflammation. Work in the past decade has been focused on active regulators of the Th2 differentiation program; however, the mechanisms that control Th2-mediated inflammation are poorly understood. E3 ubiquitin ligases (Cbl-b, Itch and GRAIL) which are implicated in T cell tolerance induction have been acknowledged as crucial factors in controlling the development and function of pro-allergic Th2 cells. Understanding of the molecular mechanisms underlying the function of these ligases in Th2 cells will lead to development of pharmacological approaches to promote the tolerance state in Th2 cells in order to treat allergic inflammation.

T cells are the master regulators of adaptive immune responses and maintenance of their tolerance is critical to prevent autoimmunity. However, in the case of carcinogenesis, the tumor microenvironment aids T-cell tolerance, which contributes to uncontrolled tumor growth. Recently, there has been significant progress in understanding the intrinsic extracellular (positive and negative costimulatory molecules on APCs) and intracellular mechanisms (E3 ubiquitin ligases, transcriptional and epigenetic repressors), as well as extrinsic mechanisms (Tregs and tolerogenic dendritic cells) that are required for the implementation and maintenance of T-cell tolerance. Ultimately, understanding and manipulating T-cell tolerance will help to break the tolerance state in cancer.

The immunomodulatory effect of probiotics has been shown mainly in gastro-intestinal immune disorders and little information is available on the inflammation of central nervous system. Recently we reported that IRT5 probiotics, a mixture of 5 probiotics, could suppress diverse experimental inflammatory disorders. In this study, we evaluated the prophylactic and therapeutic effects of IRT5 probiotics in experimental autoimmune encephalomyelitis (EAE), a T cell mediated inflammatory autoimmune disease of the central nervous system. Pretreatment of IRT5 probiotics before disease induction significantly suppressed EAE development. In addition, treatment with IRT5 probiotics to the ongoing EAE delayed the disease onset. Administration of IRT5 probiotics inhibited the pro-inflammatory Th1/Th17 polarization, while inducing IL10+ producing or/and Foxp3+ regulatory T cells, both in the peripheral immune system and at the site of inflammation. Collectively, our data suggest that IRT5 probiotics could be applicable to modulate T cell mediated neuronal autoimmune diseases, including multiple sclerosis.

Type II collagen is the major component of articular cartilage and is mainly synthesized by chondrocytes. Repeated sub-culturing of primary chondrocytes leads to reduction of type II collagen gene (Col2a1) expression, which mimics the process of chondrocyte dedifferentiation. Although the functional importance of Col2a1 expression has been extensively investigated, mechanism of transcriptional regulation during chondrocyte dedifferentiation is still unclear. In this study, we have investigated the crosstalk between cis-acting DNA element and transcription factor on Col2a1 expression in primary chondrocytes. Bioinformatic analysis revealed the potential regulatory regions in the Col2a1 genomic locus. Among them, promoter and 3′ untranslated region (UTR) showed highly accessible chromatin architecture with enriched recruitment of active chromatin markers in primary chondrocytes. 3′ UTR has a potent enhancer function which recruits Lef1 (Lymphoid enhancer binding factor 1) transcription factor, leading to juxtaposition of the 3′ UTR with the promoter through gene looping resulting in up-regulation of Col2a1 gene transcription. Knock-down of endogenous Lef1 level significantly reduced the gene looping and subsequently down-regulated Col2a1 expression. However, these regulatory loci become inaccessible due to condensed chromatin architecture as chondrocytes dedifferentiate which was accompanied by a reduction of gene looping and down-regulation of Col2a1 expression. Our results indicate that Lef1 mediated looping between promoter and 3′ UTR under the permissive chromatin architecture upregulates Col2a1 expression in primary chondrocytes.

TCR signaling regulates multiple aspects of T cell function by controlling expression of various cytokine genes. IL-24 is a multifunctional cytokine belonging to the IL-10 family. It displays anticancer effects in diverse cancer cells and regulates immunopathology of psoriasis and rheumatoid arthritis. IL-24 also plays an important role in B cell differentiation. Mouse IL-24 gene is selectively expressed in activated Th2 cells upon TCR stimulation. However, the molecular mechanisms by which TCR stimulation induces IL-24 gene expression are still unclear. In this study, to elucidate the mechanism of Th2 cell-specific expression of IL-24, we identified a proximal promoter region (−157/+95bp) that plays critical role in activating the IL-24 gene in Th2 cells. This region has a Th2 cell-specific open chromatin structure along with permissive histone modifications. In vivo binding of Stat6 and AP-1 (c-Jun) to the IL-24 promoter locus in Th2 cells synergistically transactivated the IL-24 promoter. Stat6 and c-Jun proteins were found to physically cooperate with each other and upregulated IL-24 gene transcription. Knockdown of either Stat6 or c-Jun suppressed endogenous IL-24 gene expression in Th2 cells. In summary, TCR stimulation induces IL-24 expression in Th2 cells by the coordinate action of Stat6 and c-Jun transcription factors at the transcriptional level.

The function and differentiation of induced regulatory T (iTreg) cells are tightly regulated by various signaling cascade. In this study, we have investigated the role of TCR signaling to induce Foxp3 gene expression in cooperation with TGF-β/IL-2 stimulation. Activation of CD4(+) T cells by TCR signaling or TGF-β/IL-2 alone failed to enhance Foxp3 expression. Only when TCR stimulation is coupled together with TGF-β/IL-2, CD4(+) T cells expressed high levels of Foxp3 by maintaining open chromatin structure around its promoter region. Under this condition, stimulation-dependent recruitment of JunB together with c-Rel enhanced Foxp3 expression. Over expression of JunB and c-Rel significantly enhanced Foxp3 promoter activity while treatment of JunB siRNA or inhibition of TCR signaling by MAPK inhibitors significantly reduced Foxp3 expression. Collectively our results suggest that TCR signaling together with TGF-β/IL-2 stimulation cooperatively enhance Foxp3 gene expression by maintaining accessible chromatin structure and by actively recruiting key transcription factors JunB and c-Rel.

Aim of study Placenta extract features as a composition of ointments used for skin beautification, dermatological diseases and skin dryness. However, little evidence has been cited about its underlying mechanisms of action by which it exerts a beneficial role in dermatological diseases in vivo. In this study, we intended to test the effect of topical application of porcine placenta extract in mouse model of contact hypersensitivity and elucidate its mechanism of action. Materials and methods To test the in vitro effect of porcine placenta extract, RAW 264.7 cells were cocultured with porcine placenta extract and stimulated with LPS (1 μg/ml) and the expression of inflammatory mediator TNF-α was estimated by RT-PCR at the mRNA level and by intracellular staining at the protein level. To further test in vivo efficacy, porcine placenta extract was topically applied to the mice with experimental skin hypersensitivity. For in vivo studies placenta extract in gel form was topically applied to ear of DNCB-induced contact hypersensitivity mouse model everyday for 2 weeks and progression of the disease was estimated by following criteria: (a) ear thickness, (b) serum IgE level by ELISA, (c) histological examination of ear tissue by H&E staining and (d) cytokine profile of total cells and CD4+ T cells by real time PCR. Results Topical application of porcine placenta extract on mouse ears with contact hypersensitivity decreased the severity and progression of the disease manifested by reducing ear swelling, inflammation and edema. Histological evaluation showed that placenta extract treatment reduced lymphocyte infiltration in the ear tissues. Protective effect of placenta extract is also associated with down-regulation of serum IgE level and inflammatory cytokine production (IL-1β, IFN-γ, TNF-α, IL-4, IL-12 and IL-17) in total lymph node cells and CD4+ T cells. Conclusions Our data indicate that protective effect of porcine placenta extract in contact hypersensitivity is mediated by inhibition of the inflammatory responses and IgE production, suggesting a potential therapeutic application of porcine placenta extract to modulate skin inflammation.

Background Cinnamomum cassia bark is the outer skin of an evergreen tall tree belonging to the family Lauraceae containing several active components such as essential oils (cinnamic aldehyde and cinnamyl aldehyde), tannin, mucus and carbohydrate. They have various biological functions including anti-oxidant, anti-microbial, anti-inflammation, anti-diabetic and anti-tumor activity. Previously, we have reported that anti-cancer effect of cinnamon extracts is associated with modulation of angiogenesis and effector function of CD8+ T cells. In this study, we further identified that anti-tumor effect of cinnamon extracts is also link with enhanced pro-apoptotic activity by inhibiting the activities NFκB and AP1 in mouse melanoma model. Methods Water soluble cinnamon extract was obtained and quality of cinnamon extract was evaluated by HPLC (High Performance Liquid Chromatography) analysis. In this study, we tested anti-tumor activity and elucidated action mechanism of cinnamon extract using various types of tumor cell lines including lymphoma, melanoma, cervix cancer and colorectal cancer in vitro and in vivo mouse melanoma model. Results Cinnamon extract strongly inhibited tumor cell proliferation in vitro and induced active cell death of tumor cells by up-regulating pro-apoptotic molecules while inhibiting NFκB and AP1 activity and their target genes such as Bcl-2, BcL-xL and survivin. Oral administration of cinnamon extract in melanoma transplantation model significantly inhibited tumor growth with the same mechanism of action observed in vitro. Conclusion Our study suggests that anti-tumor effect of cinnamon extracts is directly linked with enhanced pro-apoptotic activity and inhibition of NFκB and AP1 activities and their target genes in vitro and in vivo mouse melanoma model. Hence, further elucidation of active components of cinnamon extract could lead to development of potent anti-tumor agent or complementary and alternative medicine for the treatment of diverse cancers.

Aims We previously reported that Lactobacillus casei (L. casei) has beneficial effects in experimental rheumatoid arthritis (RA) by suppressing inflammatory immune responses. The major purpose of this study was to evaluate therapeutic effects of L. casei on pathological responses in experimental rodent model of osteoarthritis (OA). Main methods Experimental OA was induced by intra-articular injection of monosodium iodoacetate (MIA) in Wistar rats. L. casei alone or together with type II collagen (CII) and glucosamine (Gln) was orally administered into OA rats. The pathophysiological aspects of OA were investigated by analyzing mechanical hyperalgesia and histology of articular tissues. Expression of inflammatory molecules was analyzed in CD4+ T cells, synovial fibroblasts, and chondrocytes by quantitative real-time PCR. Key findings Oral administration of L. casei together with CII and Gln more effectively reduced pain, cartilage destruction, and lymphocyte infiltration than the treatment of Gln or L. casei alone. This co-administration also decreased expression of various pro-inflammatory cytokines (interleukin-1β (IL-1β), IL-2, IL-6, IL-12, IL-17, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ)) and matrix metalloproteinases (MMP1, MMP3, and MMP13), while up-regulating anti-inflammatory cytokines (IL-4 and IL-10). These results are concomitant with reduced translocation of NF-κB into the nucleus and increased expression of the tissue inhibitor of MMP1 (TIMP1) and CII in chondrocytes. Significance Our study provides evidence that L. casei could act as a potent nutraceutical modulator for OA treatment by reducing pain, inflammatory responses, and articular cartilage degradation.

Alternative splicing is a fine-tuned process known for generating multiple functional variants from individual genes leading to protein diversity. The immune system utilizes pre-mRNA splicing to expand its gene function. Numerous immunologically relevant genes have been found to undergo alternative splicing, thus revealing a new source of complexity in the immune gene network. This review attempts to summarize the general features of alternative splicing and its role in the immune system along with a special focus on the available reports of alternative splicing in cytokines, mainly interleukins and their receptors and their regulatory significance.

The beneficial effects of probiotics have been described in many diseases, but the mechanism by which they modulate the immune system is poorly understood. In this study, we identified a mixture of probiotics that up-regulates CD4 + Foxp3 + regulatory T cells (Tregs). Administration of the probiotics mixture induced both T-cell and B-cell hyporesponsiveness and down-regulated T helper (Th) 1, Th2, and Th17 cytokines without apoptosis induction. It also induced generation of CD4 + Foxp3 + Tregs from the CD4 + CD25 − population and increased the suppressor activity of naturally occurring CD4 + CD25 + Tregs. Conversion of T cells into Foxp3 + Tregs is directly mediated by regulatory dendritic cells (rDCs) that express high levels of IL-10, TGF-β, COX-2, and indoleamine 2,3-dioxygenase. Administration of probiotics had therapeutical effects in experimental inflammatory bowel disease, atopic dermatitis, and rheumatoid arthritis. The therapeutical effect of the probiotics is associated with enrichment of CD4 + Foxp3 + Tregs in the inflamed regions. Collectively, the administration of probiotics that enhance the generation of rDCs and Tregs represents an applicable treatment of inflammatory immune disorders.

The forkhead family protein Foxp3 is a unique marker of regulatory T cells and plays a crucial role in the development and function of those cells. Ectopic expression of Foxp3 abolishes the expression of many cytokines in uncommitted cells but there is little information about whether it causes gene silencing in differentiated cells. In this study, we showed that ectopic expression of Foxp3 in primary T helper 2 cells abolished IL-4 gene expression. Foxp3 inhibited nuclear translocation of NFkappaB by increasing the stability of the NFkappaB inhibitor IkappaBalpha, which in turn reduced in vivo binding of NFkappaB to the IL-4 promoter region. Moreover, Foxp3 over-expression induced inactive chromatin structure by decreasing in vivo binding levels of acetylated histone 3 while increasing methylated histone 3 at lysine 9 in the IL-4 genomic locus. Our results suggest that Foxp3 could induce gene silencing by inhibiting NFkappaB activity and by causing its target loci to adopt an inactive chromatin configuration.

Apart from T helper (Th)-2 cells, T follicular helper (Tfh) cells are a major class of IL-4 producing T cells, required for regulation of type 2 humoral immunity. Although the transcriptional control of IL-4 has been an area of extensive investigation, the precise regulation mechanism of IL-4 production in Tfh cells remains mainly unknown. In the current study, we found that the transcription factor Batf, a member of the AP-1/Jun family is essential for IL-4 expression in Tfh cells rather than in canonical Th2 cells. Functionally, Batf in cooperation with interferon regulatory factor (IRF)4 along with Stat3 and Stat6 trigger IL-4 production in Tfh cells by directly binding to and activation of the CNS2 region in the IL-4 locus. Additionally, Batf-to-c-Maf signaling is an important determinant of IL-4 expression in Tfh cells. We also found that in addition to IL-6/STAT3 signaling, IL-4-Stat6 axis could contribute to triggering Batf expression in Tfh cells. Importantly, IL-4-expressing Tfh cells could trigger an allergic inflammation, since deletion of Batf in Tfh cells leads to an IL-4 defect and protects mice from induction of allergic asthma. Our results thus indicate a novel and critical role of Batf in promoting the generation of pro-allergic IL-4 producing Tfh cells; Batf may be targeted in treating allergic inflammatory diseases.

Apart from Th2 cells T follicular helper (Tfh) cells are a major class of IL-4 producing T cells, required for regulation of type 2 humoral immune responses. Although the transcriptional control of IL-4 in Th2 cells has been extensively investigated, the precise regulation mechanism(s) of IL-4 production in Tfh cells remains mainly unknown. In the current study, we found that the transcription factor Batf, a member of the AP-1/Jun family is essential for IL-4 expression in Tfh cells. Remarkably, Batf deficiency leads to decreased IL-4 production selectively in Tfh cells but not in conventional Th2 cells and subsequently to reduction in their pro-allergic pathogenicity. Batf in cooperation with Interferon regulatory factor (IRF)4 controls IL-4 production in Tfh cells by directly binding to and activation of the CNS2 region of the IL-4 locus. The transcription factors Stat3 and Stat6 also aid in Batf/IRF4 binding to the CNS2 locus thus playing a crucial role in Batf-mediated regulation of IL-4 in Tfh cells. We also found that enhanced expression of Batf in Tfh cells is largely dependent on IL-4/Stat6 signaling, indicating towards a positive feedback loop in controlling Batf-IL-4 expression in Tfh cells. Our results thus identify a novel and critical role of Batf in promoting the generation of pro-allergic IL-4 producing Tfh cells.

T cell tolerance is the main obstacle to successful cancer immunotherapy; thus, today it is a high priority to develop strategies to break T cell tolerance and thereafter enhance T-cell cytotoxicity towards tumor cells. We, as well as other groups, have acknowledged the E3 ubiquitin ligase, Gene related to anergy in lymphocytes (Grail), as an essential component of T-cell tolerance phenotype. Here we report that Grail expression is highly upregulated in CD8+ T cells infiltrated into the EG-7 tumors compared to T cells in lymphoid tissues, and Grail deficiency confers spontaneous protection against inoculated EG-7 tumors. Importantly, therapeutic transfer of naïve tumor-antigen-specific Grail deficient CD8+ T cells into the wild-type hosts was sufficient to reject established tumors. Mechanistically, Grail deficient CD8+ T cells exhibit augmented effector cytokine expression and enhanced cytolytic function compared to wild-type CD8+ T cells, and are resistant to the suppression mediated by regulatory T cells. Moreover, the elevated cytotoxic function of Grail-deficient CD8+ T cells essentially depends on TCR and IL-21-signaling pathway; Grail promotes IL21R ubiquitination and degradation. Altogether, our data demonstrate that Grail is a crucial factor that controls anti-tumor activity of cytotoxic T cells, thus, inhibition of Grail may be a beneficial immunotherapeutic approach to induce potent immune responses against established tumors.

Lee, C.-G., H.-K. Kwon, A. Sahoo, W. Hwang, J.-S. So, J.-S. Hwang, C.-S. Chae, G.-C. Kim, J.-E. Kim, H.-S. So, E. S. Hwang, R. Grenningloh, I-C. Ho, and S.-H. Im. 2012. Interaction of Ets-1 with HDAC1 represses IL-10 expression in Th1 cells. J. Immunol . 188: [2244–2253][1]. An additional funding

AIM: To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells. METHODS: Cinnamon extract was used to treat murine macrophage cell line (Raw 264.7), mouse primary antigen-presenting cells (APCs, MHCII+) and CD11c+ dendritic cells to analyze the effects of cinnamon extract on APC function. The mechanisms of action of cinnamon extract on APCs were investigated by analyzing cytokine production, and expression of MHC antigens and co-stimulatory molecules by quantitative real-time PCR and flow cytometry. In addition, the effect of cinnamon extract on antigen presentation capacity and APC-dependent T-cell differentiation were analyzed by [H3]-thymidine incorporation and cytokine analysis, respectively. To confirm the anti-inflammatory effects of cinnamon extract in vivo, cinnamon or PBS was orally administered to mice for 20 d followed by induction of experimental colitis with 2,4,6 trinitrobenzenesulfonic acid. The protective effects of cinnamon extract against experimental colitis were measured by checking clinical symptoms, histological analysis and cytokine expression profiles in inflamed tissue. RESULTS: Treatment with cinnamon extract inhibited maturation of MHCII+ APCs or CD11c+ dendritic cells (DCs) by suppressing expression of co-stimulatory molecules (B7.1, B7.2, ICOS-L), MHCII and cyclooxygenase (COX)-2. Cinnamon extract induced regulatory DCs (rDCs) that produce low levels of pro-inflammatory cytokines [interleukin (IL)-1β, IL-6, IL-12, interferon (IFN)-γ and tumor necrosis factor (TNF)-α] while expressing high levels of immunoregulatory cytokines (IL-10 and transforming growth factor-β). In addition, rDCs generated by cinnamon extract inhibited APC-dependent T-cell proliferation, and converted CD4+ T cells into IL-10high CD4+ T cells. Furthermore, oral administration of cinnamon extract inhibited development and progression of intestinal colitis by inhibiting expression of COX-2 and pro-inflammatory cytokines (IL-1β, IFN-γ and TNF-α), while enhancing IL-10 levels. CONCLUSION: Our study suggests the potential of cinnamon extract as an anti-inflammatory agent by targeting the generation of regulatory APCs and IL-10+ regulatory T cells.

The developmental program of T helper and regulatory T cell lineage commitment is governed by both genetic and epigenetic mechanisms. The principal events, signaling pathways and the lineage determining factors involved have been extensively studied in the past ten years. Recent studies have elucidated the important role of chromatin remodeling and epigenetic changes for proper regulation of gene expression of lineage-specific cytokines. These include DNA methylation and histone modifications in epigenomic reprogramming during T helper cell development and effector T cell functions. This review discusses the basic epigenetic mechanisms and the role of transcription factors for the differential cytokine gene regulation in the T helper lymphocyte subsets.