Regulation of Th2 cytokine gene transcription

Recent progress on pathophysiology, inflammation and defense mechanism of mast cells against invading microbes: inhibitory effect of IL-37

Mast cells (MCs) have historically been considered masters of allergy, but there is substantial evidence supporting their contribution to tissue microorganism clearance. Their activation through the cross-linking of bound IgE provokes mast cell degranulation and activates tyrosine kinase (Syk and Lyn), leading to cytokine/chemokine generation and release. Current consensus holds that mast cells participate in the body’s defense against numerous pathogens, including bacteria, fungi, viruses and parasites, but also contribute to the inflammatory response induced by these biological agents. In the light of the latest findings, we describe the cross-talk between mast cells and pathogenic microorganisms. This review summarizes our current understanding of the host immune response, with emphasis on the roles of MCs and the cytokine/chemokine network in provoking inflammation and generating protective immunity.

This review addresses the ability of microorganisms to activate MCs provoking inflammation. We describe some MC-specific biological activities related to infections and discuss the evidence of MC mechanisms involved in the microbial activation which cause cytokine/chemokine generation-mediated inflammation, and provide a description of novel functions of mast cells during microbial infection.

Interleukin (IL)-37 binds the α chain of the IL-18 receptor and suppresses MyD88-mediated inflammatory responses. IL-37 plays a pathological role in certain infections by inhibiting the production of pro-inflammatory cytokines, such as IL-1 and TNF. Here we report the interrelationship between IL-37, inflammatory cytokines and mast cells.

Our report offers opportunities for the design of new therapeutic interventions in inflamed tissue induced by microorganism infections, acting on manipulation of mast cells and/or inflammatory cytokine blockage.

Eicosapentaenoic acid and docosahexaenoic acid suppress Th2 cytokine expression in RBL-2H3 basophilic leukemia cells

It is known that the intake of omega-3 fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), is beneficial for preventing and/or treating allergic diseases. The pathogenesis of allergic diseases is associated with overactivation of Th2-skewed immunity. Basophils generate large amounts of Th2 cytokines such as interleukin (IL)-4 and IL-13, which are critically involved in allergic inflammation. We investigated how EPA and DHA affect Th2 cytokine expression in phorbol 12-myristate 13-acetate- and ionomycin (PI)-activated RBL-2H3 basophilic leukemia cells. EPA and DHA induced a dramatic decrease in the production of IL-4 and IL-13 and their transcription in a dose-dependent manner. Luciferase assays of RBL-2H3 cells stably expressing Il4 and Il13 promoter-reporter plasmids demonstrated a significant suppression of PI-induced promoter activation. Analysis of certain transcription factors revealed that nuclear expression of c-Fos and the mRNA expression were suppressed by EPA and DHA. Furthermore, they significantly inhibited the nuclear expression and translocation of nuclear factor of activated T cells (NF-AT)1. In contrast, the expression levels of nuclear factor kappa-B (NF-κB), GATA-binding proteins (GATAs), and CCAAT/enhancer binding protein alpha (C/EBPα) were not significantly affected by EPA and DHA. Phosphorylation of extracellular signal-related kinase was inhibited by EPA and DHA, and phosphorylation of p38 mitogen-activated protein kinase was decreased by DHA, but not by EPA. Taken together, our data suggest that EPA and DHA may suppress Th2-skewed allergic immune responses by inhibiting the expression of basophilic IL-4 and IL-13.

Stratified approaches to the treatment of asthma

While asthma is a chronic inflammatory disorder that is managed with inhaled controller and reliever drugs, there remains a large unmet need at the severe end of the disease spectrum. Here, a novel stratified approach to its treatment is reviewed, based upon identification of causal pathways, with a focus on biologics. A systematic search of the literature was made using Medline, and publications were selected on the basis of their relevance to the topic. Despite strong preclinical data for many of the more recently identified asthma targets, especially those relating to the T-helper 2 allergic pathway, clinical trials with specific biologics in moderate to severe asthma as a group have been disappointing. However, subgroup analyses based upon pathway-specific biomarkers suggest specific endotypes that are responsive. Application of hypothesis-free analytical approaches (the 'omics') to well-defined phenotypes is leading to the stratification of asthma along causal pathways. Refinement of this approach is likely to be the future for diagnosing and treating this group of diseases, as well as helping to define new causal pathways. The identification of responders and nonresponders to targeted asthma treatments provides a new way of looking at asthma diagnosis and management, especially with biologics that are costly. The identification of novel biomarkers linked to well-phenotyped patients provides a stratified approach to disease management beyond simple disease severity and involving causal pathways. In order to achieve this effectively, a closer interaction will be required between industry (therapeutic and diagnostic), academia and health workers.

Omega-3 fatty acids suppress Th2-associated cytokine gene expressions and GATA transcription factors in mast cells

Because the interaction between omega-3 fatty acids and mast cells has remained largely unknown in allergies, we investigated whether omega-3 fatty acids affect the activation of mast cells by examining Th2-associated cytokine production and possible molecular mechanisms. Alpha-linolenic acid and its metabolites including eicosapentaenoic acid and decosahexaenoic acid induced a dramatic decrease in the production of interleukin (IL)-4, IL-5 and IL-13 in a dose-dependent manner, as well as mRNA expression of their genes, in activated MC/9 mast cells and bone marrow-derived mast cells. The effects were comparable to those of cyclosporin A (1 μM), a well-known immunosuppressive agent. Nuclear expression of GATA binding protein-1 (GATA-1) and GATA binding protein-2 (GATA-2), essential transcription factors for mast cell activation, was also greatly suppressed. However, their mRNA expressions were not affected. In P815 mast cells, which do not express GATA-1, the suppressive effects on cytokines were abolished. On the contrary, omega-3 fatty acids had less significant effects on IL-4 and IL-5 and resulted in a slight decrease in IL-13 production in EL-4 T cells. Finally, oral administration of fish oil containing high level of omega-3 fatty acids significantly reduced the severity of dermatitis and the thickening of epidermis/dermis in a NC/Nga murine atopic model. The number of cells expressing CD117(+) and FcεRIα(+) was greatly decreased and GATA-1 expression in the cells was also diminished. Taken together, omega-3 fatty acids might target mast cells to a greater extent than T cells to suppress Th2 cytokine expression by inhibiting GATAs for alleviation of allergic disease.

Deficient dopamine D2 receptor function causes renal inflammation independently of high blood pressure

Renal dopamine receptors participate in the regulation of blood pressure. Genetic factors, including polymorphisms of the dopamine D(2) receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood. Mice lacking Drd2 (D(2)-/-) have elevated blood pressure, increased renal expression of inflammatory factors, and renal injury. We tested the hypothesis that decreased dopamine D(2) receptor (D(2)R) function increases vulnerability to renal inflammation independently of blood pressure, is an immediate cause of renal injury, and contributes to the subsequent development of hypertension. In D(2)-/- mice, treatment with apocynin normalized blood pressure and decreased oxidative stress, but did not affect the expression of inflammatory factors. In mouse RPTCs Drd2 silencing increased the expression of TNFα and MCP-1, while treatment with a D(2)R agonist abolished the angiotensin II-induced increase in TNF-α and MCP-1. In uni-nephrectomized wild-type mice, selective Drd2 silencing by subcapsular infusion of Drd2 siRNA into the remaining kidney produced the same increase in renal cytokines/chemokines that occurs after Drd2 deletion, increased the expression of markers of renal injury, and increased blood pressure. Moreover, in mice with two intact kidneys, short-term Drd2 silencing in one kidney, leaving the other kidney undisturbed, induced inflammatory factors and markers of renal injury in the treated kidney without increasing blood pressure. Our results demonstrate that the impact of decreased D(2)R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension. Deficient renal D(2)R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D(2)R expression and function.

A genomic and expression study of AP-1 in primary cutaneous T-cell lymphoma: evidence for dysregulated expression of JUNB and JUND in MF and SS

Activator protein 1 (AP-1) consists of a group of transcription factors including the JUN and FOS family proteins with diverse biological functions. This study assessed the genomic and expression status of the AP-1 transcription factors in primary cutaneous T-cell lymphoma (CTCL) by using immunohistochemistry (IHC), Affymetrix expression microarray, real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescent in situ hybridization (FISH). IHC showed JUNB protein expression in tumor cells from 17 of 33 cases of Sezary syndrome (SS) and JUND protein expression in 16 of 23 mycosis fungoides cases. There was no correlation between JUNB and CD30 expression. However, 7 of 12 JUNB-positive SS cases expressed both phosphorylated and total extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK) proteins. Expression microarray showed over threefold increased expression of JUNB in three of six SS patients and similar findings were also noted after re-analysis of previously published data. Real-time RT-PCR confirmed the overexpression of JUNB in four SS cases and of JUND in three of four cases. FISH showed increased JUNB copy number in four of seven SS cases. These findings suggest that deregulation of AP-1 expression in CTCL is the result of aberrant expression of JUNB and possible JUND resulting from genomic amplification and constitutive activation of ERK1/2 MAPK in this type of lymphoma.

Aberrant activation of nuclear factor of activated T cell 2 in lamina propria mononuclear cells in ulcerative colitis

AIM: To investigate the role of nuclear factor of activated T cell 2 (NFAT2), the major NFAT protein in peripheral T cells, in sustained T cell activation and intractable inflammation in human ulcerative colitis (UC).

METHODS: We used two-dimensional gel-electrophoresis, immunohistochemistry, double immunohistochemical staining, and confocal microscopy to inspect the expression of NFAT2 in 107, 15, 48 and 5 cases of UC, Crohn’s disease (CD), non-specific colitis, and 5 healthy individuals, respectively.

RESULTS: Up-regulation with profound nucleo-translocation/activation of NFAT2 of lamina propria mononuclear cells (LPMC) of colonic mucosa was found specifically in the affected colonic mucosa from patients with UC, as compared to CD or NC (P < 0.001, Kruskal-Wallis test). Nucleo-translocation/activation of NFAT2 primarily occurred in CD8+T, but was less prominent in CD4+ T cells or CD20+B cells. It was strongly associated with the disease activity, including endoscopic stage (τ = 0.2145, P = 0.0281) and histologic grade (τ = 0.4167, P < 0.001).

CONCLUSION: We disclose for the first time the nucleo-translocation/activatin of NFAT2 in lamina propria mononuclear cells in ulcerative colitis. Activation of NFAT2 was specific for ulcerative colitis and highly associated with disease activity. Since activation of NFAT2 is implicated in an auto-regulatory positive feedback loop of sustained T-cell activation and NFAT proteins play key roles in the calcium/calcineurin signaling pathways, our results not only provide new insights into the mechanism for sustained intractable inflammation, but also suggest the calcium-calcineurin/NFAT pathway as a new therapeutic target for ulcerative colitis.

Identification of novel genes expressed during mouse tooth development by microarray gene expression analysis

To identify genes heretofore undiscovered as critical players in the biogenesis of teeth, we have used microarray gene expression analysis of the developing mouse molar tooth (DMT) between postnatal day (P) 1 and P10 to identify genes differentially expressed when compared with 16 control tissues. Of the top 100 genes exhibiting increased expression in the DMT, 29 were found to have been previously associated with tooth development. Differential expression of the remaining 71 genes not previously associated with tooth development was confirmed by quantitative reverse transcription-polymerase chain reaction analysis. Further analysis of seven of the latter genes by mRNA in situ hybridization found that five were specific to the developing tooth in the craniofacial region (Rspo4, Papln, Amtn, Gja1, Maf). Of the remaining two, one was found to be more widely expressed (Sp7) and the other was found to be specific to the nasal serous gland, which is close to, but distinct from, the developing tooth (Vrm).

Cytokine profiles of cord and adult blood leukocytes: differences in expression are due to differences in expression and activation of transcription factors

BACKGROUND

Stem cell transplantation as therapy for hematological disorders is often hampered by severe graft-versus-host-disease. This may be reduced by umbilical cord blood transplantation, an effect that has been attributed to qualitative differences between neonatal and adult T cells. We compared levels of secreted proteins and cytokine mRNA induced in cord blood leukocytes (CBL) and adult blood leukocytes (ABL) by various stimuli.

RESULTS

While interleukin-2 (IL-2) levels were similar in CBL and ABL, there was less induction of the Th1 cytokine interferon-gamma in CBL. Production of the Th2 cytokines IL-4, IL-5, and IL-13 and the hematopoietic cytokine IL-3 was much lower in CBL versus ABL after T-cell receptor-mediated stimulation, whereas production of GM-CSF was comparable in the 2 cell types. The lower levels of Th1 and Th2 cytokines were maintained in CBL during a 4-day time-course study, while after 12 hours IL-3 and GM-CSF reached in CBL levels similar to those in ABL. For all cytokines except IFN gamma, the IC50 values for inhibition by cyclosporin A were similar in ABL and CBL. In contrast, there was less expression and activation of transcription factors in CBL. Activation of NF-kappaB by TPA/ionomycin was detected in ABL but not CBL. Furthermore, there was less expression of the Th subset-specific transcription factors T-bet and c-maf in CBL versus ABL, whereas GATA-3 expression was similar. Expression of T-bet and c-maf correlated with expression of the Th1 and Th2 cytokines, respectively. Time course experiments revealed that T-bet expression was stimulated in both cell types, whereas c-maf and GATA-3 were induced only in ABL.

CONCLUSION

The diminished capability of CBL to synthesize cytokines is probably due to decreased activation of NF-kappaB, whereas differences in Th subsets are due to differences in regulation of Th lineage-specific transcriptions factors. We propose that the reduced incidence and severity of GvHD after allogeneic transplantation of umbilical CB cells is due to lesser activation of specific transcription factors and a subsequent reduction in production of certain cytokines.

Activation of the E3 ubiquitin ligase Itch through a phosphorylation-induced conformational change

The E3 ubiquitin (Ub) ligase Itch is a critical regulator of T helper 2 (Th2) cytokine production through its ability to induce Ub-dependent JunB degradation. After T cell receptor engagement, Itch undergoes JNK1-mediated phosphorylation that greatly enhances its enzymatic activity. To investigate how phosphorylation activates an E3 Ub ligase we have identified the JNK1 phosphorylation sites within Itch as S199, S232, and T222, which are located within a Pro-rich region. Phosphorylation of these sites is necessary and sufficient for disrupting an inhibitory interaction between the WW domain of Itch and its catalytic HECT (Homologous to E6-AP C Terminus) domain and induces a conformational change that greatly enhances the catalytic activity of Itch, a HECT E3 ligase found to be directly activated upon its phosphorylation.

Marked differences in human melanoma antigen-specific T cell responsiveness after vaccination using a functional microarray

BACKGROUND

In contrast to many animal model studies, immunotherapeutic trials in humans suffering from cancer invariably result in a broad range of outcomes, from long-lasting remissions to no discernable effect.

METHODS AND FINDINGS

In order to study the T cell responses in patients undergoing a melanoma-associated peptide vaccine trial, we have developed a high-throughput method using arrays of peptide-major histocompatibility complexes (pMHC) together with antibodies against secreted factors. T cells were specifically immobilized and activated by binding to particular pMHCs. The antibodies, spotted together with the pMHC, specifically capture cytokines secreted by the T cells. This technique allows rapid, simultaneous isolation and multiparametric functional characterization of antigen-specific T cells present in clinical samples. Analysis of CD8+ lymphocytes from ten melanoma patients after peptide vaccination revealed a diverse set of patient- and antigen-specific profiles of cytokine secretion, indicating surprising differences in their responsiveness. Four out of four patients who showed moderate or greater secretion of both interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) in response to a gp100 antigen remained free of melanoma recurrence, whereas only two of six patients who showed discordant secretion of IFNgamma and TNFalpha did so.

CONCLUSION

Such multiparametric analysis of T cell antigen specificity and function provides a valuable tool with which to dissect the molecular underpinnings of immune responsiveness and how this information correlates with clinical outcome.

Inhibitory activity of a ceramide library on interleukin-4 production from activated T cells

Allergic diseases are hypersensitivity disorders associated with the production of specific immunoglobulin E (IgE) to environmental allergens. Interleukin (IL)-4, produced primarily by CD4(+) T cells, is an important stimulus for the switch of the antibody isotype to IgE in both mice and humans. In this study we investigated the inhibitory activity of IL-4 production in activated T cells by screening ceramide derivatives prepared by solid phase combinatorial chemistry. Many ceramide derivatives significantly inhibited IL-4 production in T cells. In particular, ceramide derivatives with a lauroyl group showed strong inhibitory activities on IL-4 production in both phorbol 12-myristate 13-acetate (PMA)-activated EL4 T cells and antigen-primed cells, suggesting that they can be used as compounds for the development of anti-allergic agents.

Synergistic effect of IL-2, IL-12, and IL-18 on thymocyte apoptosis and Th1/Th2 cytokine expression

In the periphery, IL-18 synergistically induces the expression of the Th1 cytokine IFN-gamma in the presence of IL-12 and the Th2 cytokines IL-5 and IL-13 in the presence of IL-2. Although the expression of these cytokines has been described in the thymus, their role in thymic development and function remains uncertain. We report here that freshly isolated thymocytes from C57BL/6 and BALB/c mice stimulated in vitro with IL-2-plus-IL-18 or IL-12-plus-IL-18 produce large amounts of IFN-gamma and IL-13. Analysis of the thymic subsets, CD4(-)CD8(-) (DN), CD4(+)CD8(+), CD4(+)CD8(-), and CD4(-)CD8(+) revealed that IL-18 in combination with IL-2 or IL-12 induces IFN-gamma and IL-13 preferentially from DN cells. Moreover, DN2 and DN3 thymocytes contained more IFN-gamma(+) cells than cells in the later stage of maturation. Additionally, IL-18 in combination with IL-2 induces CCR4 (Th2-associated) and CCR5 (Th1-associated) gene expression. In contrast, IL-18-plus-IL-12 specifically induced CCR5 expression. The IL-2-plus-IL-18 or IL-12-plus-IL-18 effect on IFN-gamma and IL-13 expression is dependent on Stat4 and NF-kappaB but independent of Stat6, T-bet, or NFAT. Furthermore, IL-12-plus-IL-18 induces significant thymocyte apoptosis when expressed in vivo or in vitro, and this effect is exacerbated in the absence of IFN-gamma. IL-12-plus-IL-18-stimulated thymocytes can also induce IA-IE expression on cortical and medullary thymic epithelial cells in an IFN-gamma-dependent manner. Thus, the combination of IL-2, IL-12, and IL-18 can induce phenotypic and functional changes in thymocytes that may alter migration, differentiation, and cell death of immature T cells inside the thymus and potentially affect the Th1/Th2 bias in peripheral immune compartments.

HIV-1 vaccines and co-infection

Vaccines are an economically efficient means of controlling viral infections, and it is likely that a vaccine against HIV-1 will be the most effective way of controlling the global AIDS crisis. However, an effective vaccine has not yet been attainable and in developing countries co-infection with protozoa and other chronic diseases adds another level of complexity to the design of an HIV-1 vaccine. Helminthic and protozoan infections can result in a constant state of immune activation that is characterised by a dominant T helper (Th)2 type of cytokine profile. Such an immune profile is likely to have an adverse impact on the efficacy of an HIV-1 vaccine CD8 cellular immune response and the corresponding Th1 cytokines that are most likely to be important for clearing viral infections.