IRF4 regulates IL-10 gene expression in CD4+ T cells through differential nuclear translocation

Molecular Mechanisms Driving IL-10- Producing B Cells Functions: STAT3 and c-MAF as Underestimated Central Key Regulators?

Regulatory B cells (Bregs) have been highlighted in very different pathology settings including autoimmune diseases, allergy, graft rejection, and cancer. Improving tools for the characterization of Bregs has become the main objective especially in humans. Transitional, mature B cells and plasma cells can differentiate into IL-10 producing Bregs in both mice and humans, suggesting that Bregs are not derived from unique precursors but may arise from different competent progenitors at unrestricted development stages. Moreover, in addition to IL-10 production, regulatory B cells used a broad range of suppressing mechanisms to modulate the immune response. Although Bregs have been consistently described in the literature, only a few reports described the molecular aspects that control the acquisition of the regulatory function. In this manuscript, we detailed the latest reports describing the control of IL-10, TGFβ, and GZMB production in different Breg subsets at the molecular level. We focused on the understanding of the role of the transcription factors STAT3 and c-MAF in controlling IL-10 production in murine and human B cells and how these factors may represent an important crossroad of several key drivers of the Breg response. Finally, we provided original data supporting the evidence that MAF is expressed in human IL-10- producing plasmablast and could be induced in vitro following different stimulation cocktails. At steady state, we reported that MAF is expressed in specific human B-cell tonsillar subsets including the IgD⁺ CD27⁺ unswitched population, germinal center cells and plasmablast.

IL-10 in glioma

The prognosis for patients with glioblastoma (GBM), the most common and malignant type of primary brain tumour, is very poor, despite current standard treatments such as surgery, radiotherapy and chemotherapy. Moreover, the immunosuppressive tumour microenvironment hinders the development of effective immunotherapies for GBM. Cytokines such as interleukin-10 (IL-10) play a major role in modulating the activity of infiltrating immune cells and tumour cells in GBM, predominantly conferring an immunosuppressive action; however, in some circumstances, IL-10 can have an immunostimulatory effect. Elucidating the function of IL-10 in GBM is necessary to better strategise and improve the efficacy of immunotherapy. This review discusses the immunostimulatory and immunosuppressive roles of IL-10 in the GBM tumour microenvironment while considering IL-10-targeted treatment strategies. The molecular mechanisms that underlie the expression of IL-10 in various cell types are also outlined, and how this resulting information might provide an avenue for the improvement of immunotherapy in GBM is explored.

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

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

BATF Regulates T Regulatory Cell Functional Specification and Fitness of Triglyceride Metabolism in Restraining Allergic Responses

Preserving appropriate function and metabolism in regulatory T (Treg) cells is crucial for controlling immune tolerance and inflammatory responses. Yet how Treg cells coordinate cellular metabolic programs to support their functional specification remains elusive. In this study, we report that BATF couples the T_H2-suppressive function and triglyceride (TG) metabolism in Treg cells for controlling allergic airway inflammation and IgE responses. Mice with Treg-specific ablation of BATF developed an inflammatory disorder characterized by T_H2-type dominant responses and were predisposed to house dust mite-induced airway inflammation. Loss of BATF enabled Treg cells to acquire T_H2 cell-like characteristics. Moreover, BATF-deficient Treg cells displayed elevated levels of cellular TGs, and repressing or elevating TGs, respectively, restored or exacerbated their defects. Mechanistically, TCR/CD28 costimulation enhanced expression and function of BATF, which sustained IRF4 activity to preserve Treg cell functionality. Thus, our studies reveal that BATF links Treg cell functional specification and fitness of cellular TGs to control allergic responses, and suggest that therapeutic targeting of TG metabolism could be used for the treatment of allergic disease.

Tolerogenic and immunogenic states of Langerhans cells are orchestrated by epidermal signals acting on a core maturation gene module

Langerhans cells (LCs), residing in the epidermis, are able to induce potent immunogenic responses and also to mediate immune tolerance. We propose that tolerogenic and immunogenic responses of LCs are directed by signaling from the epidermis and involve counter-acting gene circuits that are coupled to a core maturation gene module. We base our analysis on recent genetic and genomic findings facilitating the understanding of the molecular mechanisms controlling these divergent immune functions. Comparing gene regulatory network (GRN) analyses of various types of dendritic cells (DCs) including LCs we integrate signaling-dependent (TGFβ, EpCAM, β-Catenin) and transcription factor (IRF4, IRF1, NFκB) regulated gene circuits that appear to orchestrate the distinctive LC functional states. Our model proposes, that while epidermal signaling in the steady-state promotes LC tolerogenic function, the disruption of cell-cell contacts coupled with inflammatory signaling induces LC immunogenic programing. The conceptual framework emphasizes the sensing of discrete epidermal and inflammatory cues by resident LCs in dictating their genomic programing and cell state dynamics.

Vitamin D and IFN-β Modulate the Inflammatory Gene Expression Program of Primary Human T Lymphocytes

IFN-β treatment is a commonly used therapy for relapsing-remitting multiple sclerosis (MS), while vitamin D deficiency correlates with an increased risk of MS and/or its activity. MS is a demyelinating chronic inflammatory disease of the central nervous system, in which activated T lymphocytes play a major role, and may represent direct targets of IFN-β and vitamin D activities. However, the underlying mechanism of action of vitamin D and IFN-β, alone or in combination, remains incompletely understood, especially when considering their direct effects on the ability of T lymphocytes to produce inflammatory cytokines. We profiled the expression of immune-related genes and microRNAs in primary human T lymphocytes in response to vitamin D and IFN-β, and we dissected the impact of these treatments on cytokine production and T cell proliferation. We found that the treatments influenced primarily memory T cell plasticity, rather than polarization toward a stable phenotype. Moreover, our data revealed extensive reprogramming of the transcriptional output of primary T cells in response to vitamin D and IFN-β and provide the bases for further mechanistic insights into these commonly used treatments.

Functions and regulation of T cell-derived interleukin-10

Interleukin (IL)-10 is an essential anti-inflammatory cytokine and functions as a negative regulator of immune responses to microbial antigens. IL-10 is particularly important in maintaining the intestinal microbe-immune homeostasis. Loss of IL-10 promotes the development of inflammatory bowel disease (IBD) as a consequence of an excessive immune response to the gut microbiota. IL-10 also functions more generally to prevent excessive inflammation during the course of infection. Although IL-10 can be produced by virtually all cells of the innate and adaptive immune system, T cells constitute a non-redundant source for IL-10 in many cases. The various roles of T cell-derived IL-10 will be discussed in this review. Given that IL-10 is at the center of maintaining the delicate balance between effective immunity and tissue protection, it is not surprising that IL-10 expression is highly dynamic and tightly regulated. We summarize the environmental signals and molecular pathways that regulate IL-10 expression. While numerous studies have provided us with a deep understanding of IL-10 biology, the majority of findings have been made in murine models, prompting us to highlight gaps in our knowledge about T cell-derived IL-10 in the human system.

Epigenetic and transcriptional mechanisms for the regulation of IL-10

IL-10 is a critical immunoregulatory cytokine expressed in virtually all immune cell types. Maintaining a delicate balance between effective immune response and tolerance requires meticulous and dynamic control of IL-10 expression both epigenetically and transcriptionally. In this Review, we describe the epigenetic mechanisms controlling IL-10 expression, including chromatin remodeling, 3D chromatin loops, histone modification and DNA methylation. We discuss the role of transcription factors in directing chromatin modifications, with a special highlight on the emerging concept of pioneer transcription factors in setting up the chromatin landscape in T helper cells for IL-10 induction. Besides summarizing the recent progress on transcriptional regulation in specialized IL-10 producers such as type 1 regulatory T cells, regulatory B cells and regulatory innate lymphoid cells, we also discuss common transcriptional mechanisms for IL-10 regulation that are shared with other IL-10 producing cells.

An activating mutation of interferon regulatory factor 4 (IRF4) in adult T-cell leukemia

The human T-cell leukemia virus-1 (HTLV-1) oncoprotein Tax drives cell proliferation and resistance to apoptosis early in the pathogenesis of adult T-cell leukemia (ATL). Subsequently, probably as a result of specific immunoediting, Tax expression is down-regulated and functionally replaced by somatic driver mutations of the host genome. Both amplification and point mutations of interferon regulatory factor 4 (IRF4) have been previously detected in ATL., K59R is the most common single-nucleotide variation of IRF4 and is found exclusively in ATL. High-throughput whole-exome sequencing revealed recurrent activating genetic alterations in the T-cell receptor, CD28, and NF-κB pathways. We found that IRF4, which is transcriptionally activated downstream of these pathways, is frequently mutated in ATL. IRF4 RNA, protein, and IRF4 transcriptional targets are uniformly elevated in HTLV-1-transformed cells and ATL cell lines, and IRF4 was bound to genomic regulatory DNA of many of these transcriptional targets in HTLV-1-transformed cell lines. We further noted that the K59R IRF4 mutant is expressed at higher levels in the nucleus than WT IRF4 and is transcriptionally more active. Expression of both WT and the K59R mutant of IRF4 from a constitutive promoter in retrovirally transduced murine bone marrow cells increased the abundance of T lymphocytes but not myeloid cells or B lymphocytes in mice. IRF4 may represent a therapeutic target in ATL because ATL cells select for a mutant of IRF4 with higher nuclear expression and transcriptional activity, and overexpression of IRF4 induces the expansion of T lymphocytes in vivo.

Promoter H3K4 methylation dynamically reinforces activation-induced pathways in human CD4 T cells

The epigenetic determinants driving the responses of CD4 T cells to antigen are currently an area of active research. Much has been done to characterize helper T-cell subsets and their associated genome-wide epigenetic patterns. In contrast, little is known about the dynamics of histone modifications during CD4 T-cell activation and the differential kinetics of these epigenetic marks between naive and memory T cells. In this study, we have detailed the dynamics of genome-wide promoter H3K4me2 and H3K4me3 over a time course during activation of human naive and memory CD4 T cells. Our results demonstrate that changes to H3K4 methylation occur relatively late after activation (5 days) and reinforce activation-induced upregulation of gene expression, affecting multiple pathways important to T-cell activation, differentiation and function. The dynamics and mapped pathways of H3K4 methylation are distinctly different in memory cells, which have substantially more promoters marked by H3K4me3 alone, reinforcing their more differentiated state. Our study provides the first data examining genome-wide histone modification dynamics during CD4 T-cell activation, providing insight into the cross talk between H3K4 methylation and gene expression, and underscoring the impact of these marks upon key pathways integral to CD4 T-cell activation and function.

Tim-3 protects decidual stromal cells from toll-like receptor-mediated apoptosis and inflammatory reactions and promotes Th2 bias at the maternal-fetal interface

Toll-like receptors (TLRs) are important in mediating immune responses against various pathogens during pregnancy. However, uncontrolled TLR-triggered inflammation will endanger normal pregnancy, resulting in pregnancy loss. Therefore, maintenance of a moderate inflammatory response is crucial for successful pregnancy under conditions of infection. Here, we demonstrated significantly lowered expression of T-cell immunoglobulin and mucin domain 3 (Tim-3) in miscarried decidual stromal cells (DSCs), indicating that Tim-3 might play important roles in maintaining successful pregnancies. Activation of TLR signaling induced pro-inflammatory cytokine production and apoptosis of DSCs, which was accompanied by up-regulated Tim-3 expression. Tim-3, in turn, protected DSCs from TLR-mediated apoptosis in an ERK1/2 pathway-dependent manner. In addition, Tim-3 inhibited TLR signaling-induced inflammatory cytokine production by DSCs through suppressing NF-κB activation. Tim-3 increased production of T helper 2 (Th2)-type cytokines by DSCs and reversed the inhibitory effect of LPS on Th2 cytokine generation by up-regulation of interferon regulatory factor 4 expression. Tim-3 blockade abolished the effect of Tim-3 on the inflammatory response to LPS stimulation. Thus, Tim-3 signaling could represent a “self-control” mechanism in TLR-triggered inflammation during pregnancy. These findings identify Tim-3 as a key regulator of DSCs and suggest its potential as a target for the treatment of spontaneous abortion.

FOXO1 is required for binding of PR on IRF4, novel transcriptional regulator of endometrial stromal decidualization

The forkhead box O1A (FOXO1) is an early-induced target of the protein kinase A pathway during the decidualization of human endometrial stromal cells (HESCs). In this study we identified the cistrome and transcriptome of FOXO1 and its role as a transcriptional regulator of the progesterone receptor (PR). Direct targets of FOXO1 were identified by integrating RNA sequencing with chromatin immunoprecipitation followed by deep sequencing. Gene ontology analysis demonstrated that FOXO1 regulates a subset of genes in decidualization such as those involved in cancer, p53 signaling, focal adhesions, and Wnt signaling. An overlap of the FOXO1 and PR chromatin immunoprecipitation followed by deep sequencing intervals revealed the co-occupancy of FOXO1 in more than 75% of PR binding intervals. Among these intervals were highly enriched motifs for the interferon regulatory factor member 4 (IRF4). IRF4 was determined to be a genomic target of both FOXO1 and PR and also to be differentially regulated in HESCs treated with small interfering RNA targeting FOXO1 or PR prior to decidualization stimulus. Ablation of FOXO1 was found to abolish binding of PR to the shared binding interval downstream of the IRF4 gene. Finally, small interfering RNA-mediated ablation of IRF4 was shown to compromise morphological transformation of decidualized HESCs and to attenuate the expression of the decidual markers IGFBP1, PRL, and WNT4. These results provide the first evidence that FOXO1 is functionally required for the binding of PR to genomic targets. Most notably, FOXO1 and PR are required for the regulation of IRF4, a novel transcriptional regulator of decidualization in HESCs.

Grail controls Th2 cell development by targeting STAT6 for degradation

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 IL-4-signaling components, 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.

6-Methoxyflavone inhibits NFAT translocation into the nucleus and suppresses T cell activation

NFAT plays a crucial role in the immune system by regulating the transcription of inducible genes during immune responses. In T cells, NFAT proteins govern various cellular events related to T cell development, activation, tolerance induction, and differentiation. We previously reported the NFAT1-dependent enhancer activity of conserved noncoding sequence (CNS)-9, a distal cis-acting element, in the regulation of IL-10 transcription in T cells. In this study, we developed a T cell-based reporter system to identify compounds that modulate the regulatory activity of CNS-9. Among the identified candidates, 6-methoxyflavone (6-MF) significantly inhibited the enhancer activity of CNS-9, thereby reducing IL-10 expression in T cells without affecting cell viability. 6-MF also downregulated the transcription of NFAT1 target genes such as IL-4, IL-13, and IFN-γ. Treatment of 6-MF inhibited the translocation of NFAT1 into the nucleus, which consequently interrupted NFAT1 binding to the target loci, without affecting the expression or dephosphorylation of NFAT1. Treatment of 6-MF to CD4(+) T cells or B cells isolated from mice with atopic dermatitis significantly reduced disease-associated cytokine production, as well as the levels of IgE. In addition, oral administration of 6-MF to atopic dermatitis mice ameliorated disease symptoms by reducing serum IgE levels and infiltrating lymphocytes. Conclusively, our results suggest that 6-MF can be a potential candidate for the development of an effective immunomodulator via the suppression of NFAT-mediated T cell activation.

Role of Blimp-1 in programing Th effector cells into IL-10 producers

The transcriptional regulator Blimp-1 is absolutely required for IL-10 production in Th1 cells and limits inflammatory effector T cell responses downstream of IL-12 and IL-27.

Secretion of the immunosuppressive cytokine interleukin (IL) 10 by effector T cells is an essential mechanism of self-limitation during infection. However, the transcriptional regulation of IL-10 expression in proinflammatory T helper (Th) 1 cells is insufficiently understood. We report a crucial role for the transcriptional regulator Blimp-1, induced by IL-12 in a STAT4-dependent manner, in controlling IL-10 expression in Th1 cells. Blimp-1 deficiency led to excessive inflammation during Toxoplasma gondii infection with increased mortality. IL-10 production from Th1 cells was strictly dependent on Blimp-1 but was further enhanced by the synergistic function of c-Maf, a transcriptional regulator of IL-10 induced by multiple factors, such as the Notch pathway. We found Blimp-1 expression, which was also broadly induced by IL-27 in effector T cells, to be antagonized by transforming growth factor (TGF) β. While effectively blocking IL-10 production from Th1 cells, TGF-β shifted IL-10 regulation from a Blimp-1–dependent to a Blimp-1–independent pathway in IL-27–induced Tr1 (T regulatory 1) cells. Our findings further illustrate how IL-10 regulation in Th cells relies on several transcriptional programs that integrate various signals from the environment to fine-tune expression of this critical immunosuppressive cytokine.

From the regulatory functions of B cells to the identification of cytokine-producing plasma cell subsets

B lymphocytes have a unique role as antibody-producing cells. Antibodies are key mediators of humoral immunity against infections, and are thought to account for the protection afforded by successful vaccines. B cells can also secrete cytokines and subsequently regulate immune responses mediated by T and innate cells. Remarkably, recent studies identified plasma blasts/plasma cells as the main types of activated B cells producing the cytokines interleukin (IL)-10, IL-35, tumor necrosis factor (TNF)-α, IL-17, and GM-CSF in various contexts in mice. Here, we discuss these observations, which suggest the existence of various subsets of plasma blast/plasma cells distinguishable through their cytokine expression pattern.

Murine gammaherpesvirus M2 protein induction of IRF4 via the NFAT pathway leads to IL-10 expression in B cells

Reactivation of the gammaherpesviruses Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV68) from latently infected B cells has been linked to plasma cell differentiation. We have previously shown that the MHV68 M2 protein is important for virus reactivation from B cells and, when expressed alone in primary murine B cells, can drive B cell differentiation towards a pre-plasma cell phenotype. In addition, expression of M2 in primary murine B cells leads to secretion of high levels of IL-10 along with enhanced proliferation and survival. Furthermore, the absence of M2 in vivo leads to a defect in the appearance of MHV68 infected plasma cells in the spleen at the peak of MHV68 latency. Here, employing an inducible B cell expression system, we have determined that M2 activates the NFAT pathway in a Src kinase-dependent manner – leading to induction of the plasma cell-associated transcription factor, Interferon Regulatory Factor-4 (IRF4). Furthermore, we show that expression of IRF4 alone in a B cell line up-regulates IL-10 expression in culture supernatants, revealing a novel role for IRF4 in B cell induced IL-10. Consistent with the latter observation, we show that IRF4 can regulate the IL-10 promoter in B cells. In primary murine B cells, addition of cyclosporine (CsA) resulted in a significant decrease in M2-induced IL-10 levels as well as IRF4 expression, emphasizing the importance of the NFAT pathway in M2- mediated induction of IL-10. Together, these studies argue in favor of a model wherein M2 activation of the NFAT pathway initiates events leading to increased levels of IRF4 – a key player in plasma cell differentiation – which in turn triggers IL-10 expression. In the context of previous findings, the data presented here provides insights into how M2 facilitates plasma cell differentiation and subsequent virus reactivation.

The human viruses Epstein-Barr Virus (EBV) and Kaposi's Sarcoma-associated herpesvirus (KSHV) are members of the gammaherpesvirus family – pathogens that are associated with cancers of lymphoid tissues. Murine gammaherpesvirus 68 (MHV68) infection of laboratory mice provides a small animal model to study how this family of viruses chronically infects their host. The gammaherpesvirus establish a quiescent infection (termed latency) for the lifetime of the individual. However, they are capable of producing progeny virus (termed reactivation) in response to a variety of immune or environmental stimuli. Differentiation of latently infected B cells into plasma cells (the cells producing antibodies) has been associated with reactivation from latency. Notably, the MHV68 M2 protein plays a role in driving differentiation of MHV68 infected B cells to plasma cells. Furthermore, M2 expression results in increased levels of IL-10 (an immune-regulatory cytokine). Here we show that M2 mediated IL-10 production occurs through induction of IRF4 expression, a key player in plasma cell differentiation. This process involves Src kinases and NFAT – both components of B cell receptor signaling. Additionally, mice lacking IRF4 in infected cells show a significant defect in virus reactivation, thereby identifying IRF4 as a crucial component of M2 mediated functions.

Nucleotide-binding oligomerization domain 2 signaling promotes hyperresponsive macrophages and colitis in IL-10-deficient mice

IL-10 contributes to the maintenance of intestinal homeostasis via the regulation of inflammatory responses to enteric bacteria. Loss of IL-10 signaling results in spontaneous colitis in mice and early onset enterocolitis in humans. Nucleotide-binding oligomerization domain (NOD) 2 is an intracellular receptor of bacterial peptidoglycan products, and, although NOD2 mutations are associated with Crohn's disease, the precise role of NOD2 in the development of intestinal inflammation remains undefined. To determine the role of NOD2 in the development of colitis on the clinically relevant genetic background of IL-10-deficient signaling, we generated mice lacking IL-10 and NOD2 (IL-10(-/-)NOD2(-/-)). Loss of NOD2 in IL-10(-/-) mice resulted in significant amelioration of chronic colitis, indicating that NOD2 signaling promotes the development of intestinal inflammation in IL-10(-/-) mice. Contrary to previous reports investigating immune function in NOD2(-/-) mice, T cell proliferative capacity and IL-2 production were not impaired, and immune polarization toward type 1 immunity was not affected. However, loss of NOD2 in IL-10-deficient macrophages reduced IL-6, TNF-α, and IL-12p40 production in response to bacterial stimulation. Further analysis of the intrinsic macrophage response before the onset of inflammation revealed that, in the absence of IL-10, synergistic signaling between various TLRs and NOD2 resulted in hyperresponsive, proinflammatory macrophages, thus providing the appropriate immune environment for the development of colitis. Data presented in this study demonstrate that NOD2 signaling contributes to intestinal inflammation that arises through loss of IL-10 and provides mechanistic insight into the development of colitis in inflammatory bowel disease patients with impaired IL-10 signaling.

An integrative computational systems biology approach identifies differentially regulated dynamic transcriptome signatures which drive the initiation of human T helper cell differentiation

Background

A proper balance between different T helper (Th) cell subsets is necessary for normal functioning of the adaptive immune system. Revealing key genes and pathways driving the differentiation to distinct Th cell lineages provides important insight into underlying molecular mechanisms and new opportunities for modulating the immune response. Previous computational methods to quantify and visualize kinetic differential expression data of three or more lineages to identify reciprocally regulated genes have relied on clustering approaches and regression methods which have time as a factor, but have lacked methods which explicitly model temporal behavior.

Results

We studied transcriptional dynamics of human umbilical cord blood T helper cells cultured in absence and presence of cytokines promoting Th1 or Th2 differentiation. To identify genes that exhibit distinct lineage commitment dynamics and are specific for initiating differentiation to different Th cell subsets, we developed a novel computational methodology (LIGAP) allowing integrative analysis and visualization of multiple lineages over whole time-course profiles. Applying LIGAP to time-course data from multiple Th cell lineages, we identified and experimentally validated several differentially regulated Th cell subset specific genes as well as reciprocally regulated genes. Combining differentially regulated transcriptional profiles with transcription factor binding site and pathway information, we identified previously known and new putative transcriptional mechanisms involved in Th cell subset differentiation. All differentially regulated genes among the lineages together with an implementation of LIGAP are provided as an open-source resource.

Conclusions

The LIGAP method is widely applicable to quantify differential time-course dynamics of many types of datasets and generalizes to any number of conditions. It summarizes all the time-course measurements together with the associated uncertainty for visualization and manual assessment purposes. Here we identified novel human Th subset specific transcripts as well as regulatory mechanisms important for the initiation of the Th cell subset differentiation.

Role of interleukin 10 transcriptional regulation in inflammation and autoimmune disease

Interleukin 10 (IL-10) is a cytokine with potent anti-inflammatory properties that plays a central role in limiting host immune response to pathogens, thereby preventing damage to the host and maintaining normal tissue homeostasis. Dysregulation of IL-10 is associated with enhanced immunopathology in response to infection as well as increased risk for development of many autoimmune diseases. Thus a fundamental understanding of IL-10 gene expression is critical for our comprehension of disease progression and resolution of host inflammatory response. In this review, we discuss modes of regulation of IL-10 gene expression in immune effector cell types, including signal transduction, epigenetics, promoter architecture, and post-transcriptional regulation, and how aberrant regulation contributes to immunopathology and disease progression.

Identification of tripartite motif-containing 22 (TRIM22) as a novel NF-κB activator

Increasing evidence suggests that TRIM family proteins may play important roles in the regulation of innate immune signaling pathways. Here we report TRIM22 is involved in the activation of NF-κB. It was found that overexpression of TRIM22 could dose-dependently activate NF-κB as demonstrated by reporter gene assay and electrophoretic mobility shift assay, but had no effect on the activity of other transcription factors, including NF-AT, AP-1, C/EBP and IRFs. Further study showed that both the N-terminal RING domain and C-terminal SPRY domain were crucial for TRIM22-mediated NF-κB activation. Moreover, our results revealed that TRIM22 overexpression could significantly induce the secretion of pro-inflammatory cytokines by human macrophage cell line U937 in an NF-κB-dependent manner. These data suggested that TRIM22 was a positive regulator of NF-κB-mediated transcription.