Transcriptional regulation of Th1/Th2 polarization

Lentiviral-mediated GATA-3 RNAi decreases allergic airway inflammation and hyperresponsiveness

GATA-3 is the key transcriptional factor for Th2 commitment in T cells and is strongly associated with asthma and allergic disease. We studied the silencing of the GATA-3 gene expression using RNA interference (RNAi) delivered by a lentiviral vector, to evaluate the therapeutic role of GATA-3 short hairpin RNAs (shRNAs) in a murine model of asthma. Mice were sensitized with OVA and instilled intratracheally (IT) with GATA-3 shRNAs lentiviral vector (Lenti-si-GATA-3) once, 48 hours before challenge. After three challenges with the OVA antigen, the mice were assessed for airway hyperresponsiveness (AHR) and inflammation. With infection of Lenti-si-GATA-3 in EL-4 cells, GATA-3 gene expression was abrogated and downstream Th2 cytokines, such as interleukin-4 (IL-4) and IL-5, were also significantly inhibited. IT delivery of Lenti-si-GATA-3 in OVA-immunized mice resulted in a strong inhibition of local GATA-3 gene expression. Treatment with Lenti-si-GATA-3 successfully alleviated OVA-induced airway eosinophilia and Th2 cytokine release. While evaluating AHR by means of enhanced pause (Penh) and pulmonary resistance (R(L)) using body plethysmography, it was found that the administration of Lenti-si-GATA-3 had significantly decreased AHR in OVA-immunized mice. These results suggest that inhibition of GATA-3 gene expression by shRNAs lentiviral vectors strongly attenuates antigen-induced airway inflammation and hyper-responsiveness in mice.

Effects of pollen and nasal glucocorticoid on FOXP3+, GATA-3+ and T-bet+ cells in allergic rhinitis

BACKGROUND

T-regulatory cells (Treg) affect the balance of T(H)2 and T(H)1 cells. Treg, T(H)2 and T(H)1 cells are regulated by the FOXP3, GATA-3 and T-bet transcription factors respectively. Our aim was to determine the number of FOXP3(+), GATA-3(+) and T-bet(+) cells in nasal mucosa in symptom-free allergic rhinitis (AR) patients vs healthy controls, as well as the effects of natural pollen exposure and concomitant nasal glucocorticoid treatment on these cells.

METHODS

Nasal biopsies were taken from healthy controls and patients with grass-pollen AR preseason. The AR patients were randomized to receive treatment with either fluticasone propionate (FP) or a placebo, and additional biopsies were taken during the pollen season. FOXP3(+), GATA-3(+) and T-bet(+) cells in nasal mucosa were quantified by immunohistochemistry.

RESULTS

The number of FOXP3(+) and GATA-3(+) cells, but not T-bet(+) cells, was significantly higher in AR patients vs controls preseason. The number of FOXP3(+) cells remained unchanged in the former group after the pollen season but decreased significantly in the nasal mucosa as a result of FP treatment. The pollen season substantially increased the number of GATA-3(+) cells, which was inhibited by FP. The number of T-bet(+) cells was not affected by pollen or FP.

CONCLUSION

These data suggest that nasal glucocorticoids attenuate the allergic inflammation partly by reducing the number of T(H)2 cells, but not by means of local upregulation of Treg cells. The local relationship between T(H)1 and T(H)2 cells as well as between Treg and T(H)2 is maintained by nasal glucocorticoid treatment.

Phenotypic and functional features of human Th17 cells

T helper (Th) 17 cells represent a novel subset of CD4+ T cells that are protective against extracellular microbes, but are responsible for autoimmune disorders in mice. However, their properties in humans are only partially known. We demonstrate the presence of Th17 cells, some of which produce both interleukin (IL)-17 and interferon (IFN)-γ (Th17/Th1), in the gut of patients with Crohn's disease. Both Th17 and Th17/Th1 clones showed selective expression of IL-23R, CCR6, and the transcription factor RORγt, and they exhibited similar functional features, such as the ability to help B cells, low cytotoxicity, and poor susceptibility to regulation by autologous regulatory T cells. Interestingly, these subsets also expressed the Th1-transcription factor T-bet, and stimulation of these cells in the presence of IL-12 down-regulated the expression of RORγt and the production of IL-17, but induced IFN-γ. These effects were partially inhibited in presence of IL-23. Similar receptor expression and functional capabilities were observed in freshly derived IL-17–producing peripheral blood and tonsillar CD4+ T cells. The demonstration of selective markers for human Th17 cells may help us to understand their pathogenic role. Moreover, the identification of a subset of cells sharing features of both Th1 and Th17, which can arise from the modulation of Th17 cells by IL-12, may raise new issues concerning developmental and/or functional relationships between Th17 and Th1.

Cytopiloyne, a polyacetylenic glucoside, prevents type 1 diabetes in nonobese diabetic mice

Some polyacetylenes from the plant Bidens pilosa have been reported to treat diabetes. In this study, we report that the cytopiloyne from B. pilosa, which is structurally different from the above-mentioned polyacetylenes and inhibits CD4(+) T cell proliferation, effectively prevents the development of diabetes in nonobese diabetic mice as evidenced by a normal level of blood glucose and insulin and normal pancreatic islet architecture. Cytopiloyne also suppresses the differentiation of type 1 Th cells but promotes that of type 2 Th cells, which is consistent with it enhancing GATA-3 transcription. Also, long-term application of cytopiloyne significantly decreases the level of CD4(+) T cells inside pancreatic lymph nodes and spleens but does not compromise total Ab responses mediated by T cells. Coculture assays imply that this decrease in CD4(+) T cells involves the Fas ligand/Fas pathway. Overall, our results suggest that cytopiloyne prevents type 1 diabetes mainly via T cell regulation.

TH2 and TH1 lung inflammation induced by airway allergen sensitization with low and high doses of double-stranded RNA

BACKGROUND

Although respiratory viral infections in early childhood can enhance the development of airway allergen sensitization, the exact mechanisms of the effects of viral infections on the adaptive immune response to inhaled allergens are controversial.

OBJECTIVE

We sought to evaluate the effects of double-stranded RNA (dsRNA) on airway sensitization to inhaled allergens.

METHODS

Novel mouse models were created through simultaneous airway sensitization to an allergen and low or high doses of dsRNA. The mouse models were applied to Toll-like receptor 3-, IL-13-, IL-4-, signal transducer and activator of transcription (STAT) 6-, IFN-gamma-, and T-box expressed in T cells (T-bet)-deficient mice to evaluate underlying pathophysiologic mechanisms in the development of allergic lung inflammation.

RESULTS

We found that airway allergen sensitization with dsRNA induced lung inflammation that was not present in Toll-like receptor 3-deficient mice. Moreover, lung inflammation enhanced by low-dose dsRNA was impaired in IL-13-deficient mice, whereas lung inflammation by high-dose dsRNA was impaired in IFN-gamma-deficient mice. The models also demonstrated that low-dose dsRNA enhanced IL-4 expression during allergen sensitization and that inflammation enhanced by low-dose dsRNA was not present in IL-4- or STAT6-deficient mice. In contrast, the present study showed that high-dose dsRNA enhanced IFN-gamma expression during allergen sensitization and that the development of lung inflammation enhanced by high-dose dsRNA was impaired in T-bet-deficient mice.

CONCLUSION

These findings suggest that airway allergen exposure during respiratory viral infections might induce asthma induced by both T(H)1 and T(H)2 immune responses to inhaled allergens.

CLINICAL IMPLICATIONS

Targeting both T(H)1 and T(H)2 lung inflammation might be important in the treatment of virus-associated asthma.

Identification of a distant T-bet enhancer responsive to IL-12/Stat4 and IFNgamma/Stat1 signals

T-bet plays a critical role in controlling IFNgamma expression, Th1 polarization, and CD8 cytolytic development. Its regulation has been demonstrated to be mostly IFNgamma/Stat1 dependent while IL-12/Stat4 independent. Here we show that IL-12/Stat4 binds to a distant highly conserved STAT-responsive T-bet enhancer, and induces IFNgamma/Stat1-independent T-bet expression in CD8 T cells. Luciferase reporter assay showed that both Stat4 and Stat1 activate reporter gene expression from constructs containing a wild-type but not mutated T-bet enhancer. Studies in virus-infected mice demonstrated that the IL-12/Stat4/T-bet cascade operates in vivo and regulates IFNgamma in CD8 T cells. Together, we provide a novel mechanism for T-bet regulation, and suggest that IL-12/Stat4/T-bet play an important role in CD8 effector responses.

Fatty acids isolated from royal jelly modulate dendritic cell-mediated immune response in vitro

Royal jelly (RJ), especially its protein components, has been shown to possess immunomodulatory activity. However, almost nothing is known about the influence of RJ fatty acids on the immune system. In this work we studied the effect of 10-hydroxy-2-decanoic acid (10-HDA) and 3,10-dihydroxy-decanoic acid (3,10-DDA), isolated from RJ, on the immune response using a model of rat dendritic cell (DC)-T-cell cocultures. Both fatty acids, at higher concentrations, inhibited the proliferation of allogeneic T cells. The effect of 10-HDA was stronger and was followed by a decrease in interleukin-2 (IL-2) production and down-regulation of IL-2 receptor expression. Spleen DC, cultivated with 10 microg/ml of fatty acids down-regulated the expression of CD86 and the production of IL-12, but up-regulated the production of IL-10. In contrast, DC, pretreated with 100 microg/ml of 3,10-DDA, up-regulated the expression of CD86 and augmented the proliferation of allogeneic T cells. The highest dose (200 microg/ml) of both fatty acids which was non-apoptotic for both T cells and DC, down-regulated the expression of MHC class II and CD86, decreased the production of IL-12 and made these DC less allostimulatory. The immunosuppressive activity of 3,10-DDA was also confirmed in vivo, using a model of Keyhole lymphet hemocyanine immunization of rats. In conclusion, our results showed the immunomodulatory activity of RJ fatty acids and suggest that DC are a significant target of their action.

Cytokine-mediated control of lipopolysaccharide-induced activation of small intestinal epithelial cells

Cytokines with anti-inflammatory properties have been implicated in the prevention of inappropriate immune activation by commensal bacteria in the intestinal tract. Here, we analysed receptor expression, cellular signalling, and the inhibitory activity of interleukin (IL)-4, -10, -11, and -13 as well as of transforming growth factor-beta on lipopolysaccharide-mediated small intestinal epithelial cell activation. Only IL-4 and IL-13 had a significant inhibitory effect on chemokine secretion and nitric oxide (NO) production in differentiated and polarized cells. Reverse transcription-polymerase chain reaction of primary intestinal epithelial cells obtained by laser-microdissection confirmed expression of the type II IL-4 receptor consisting of the IL-4 receptor alpha and the IL-13 receptor alpha1. Also, IL-4 or IL-13 led to rapid signal transducer and activator of transcription 6 phosphorylation, diminished inducible NO synthase expression, and enhanced the antagonistic arginase 1 activity. In conclusion, cytokines such as IL-4 and IL-13 affect intestinal epithelial cells and exhibit a modulating activity on Toll-like receptor-4-mediated epithelial cell activation.

Generation of clinical grade dendritic cells with capacity to produce biologically active IL-12p70

Background

For optimal T cell activation it is desirable that dendritic cells (DCs) display peptides within MHC molecules as signal 1, costimulatory molecules as signal 2 and, in addition, produce IL-12p70 as signal 3. IL-12p70 polarizes T cell responses towards CD4⁺ T helper 1 cells, which then support the development of CD8⁺ cytotoxic T lymphocytes. We therefore developed new maturation cocktails allowing DCs to produce biologically active IL-12p70 for large-scale cancer vaccine development.

Methods

After elutriation of leukapheresis products in a closed bag system, enriched monocytes were cultured with GM-CSF and IL-4 for six days to generate immature DCs that were then matured with cocktails, containing cytokines, interferon-gamma, prostaglandin E2, and a ligand for Toll-like receptor 8, with or without poly (I:C).

Results

Mature DCs expressed appropriate maturation markers and the lymph node homing chemokine receptor, CCR7. They retained full maturity after culture for two days without maturation cocktails and following cryopreservation. TLR ligand stimulation induced DCs capable of secreting IL-12p70 in primary cultures and after one day of coculture with CD40L-expressing fibroblasts, mimicking an encounter with T cells. DCs matured with our new cocktails containing TLR8 ligand, with or without poly (I:C), induced alloresponses and stimulated virus-specific T cells after peptide-pulsing. DCs matured in cocktails containing TLR8 ligand without poly (I:C) could also be loaded with RNA as a source of antigen, whereas DCs matured in cocktails containing poly (I:C) were unable to express proteins following RNA transfer by electroporation.

Conclusion

Our new maturation cocktails allowed easy DC harvesting, stable maturation and substantial recoveries of mature DCs after cryopreservation. Our procedure for generating DCs is easily adaptable for GMP-compliance and yields IL-12p70-secreting DCs suitable for development of cancer vaccines using peptides or RNA as sources of immunizing antigens.

Suppression of early IL-4 production underlies the failure of CD4 T cells activated by TLR-stimulated dendritic cells to differentiate into Th2 cells

Dendritic cells (DCs) activated through TLRs provide a potent negative signal for Th2 cell development that is independent of positive signals for Th1 cell development such as IL-12 and IFN-gamma. In this study we demonstrate that the ability of TLR-activated DCs to suppress Th2 cell development is Ag dose-independent and unique to DCs that have been activated through TLRs vs by cytokines. We show that TLR-activated DCs inhibit early IL-4 production by CD4 T cells and thus inhibit their ability to subsequently increase GATA-3 expression and commit to the Th2 lineage. This occurs independently of expression of the GATA-3 antagonist T-bet. Although CD4 T cells activated by TLR-activated DCs make IL-2, they are not capable of phosphorylating STAT5 in response to this cytokine. This inhibition of responsiveness to IL-2 appears to underlie the failure to make early IL-4. Our findings suggest that DCs provide instructional signals for T cell differentiation before cytokine-mediated Th cell selection and outgrowth.

Th1/Th2 cytokine ratio in tissue transudates from patients with oral lichen planus

OBJECTIVE

The characteristics of oral lichen planus (OLP) provoke investigators to explore possible biomarkers by which to monitor disease activity and therapeutic efficacy. Oral fluids may provide an accessible medium for analysis of such biomarkers. Previous studies have shown that activation of nuclear factor-kappa B (NF-kappa B) plays an important role in the pathogenesis of oral lichen planus (OLP), which is a chronic inflammatory disorder mediated by T cells. Prior to the present investigation, reports of the levels of NF-kappa B and its dependent cytokines in oral fluids have not been forthcoming. The purpose of this study was to detect the level of NF-kappa B dependent cytokines, TNF-alpha, IL-1-alpha, IL-6, and IL-8 in tissue transudates directly from lesions of OLP, and explore the feasibility of the data for clinical application.

STUDY DESIGN

Thirteen definitively diagnosed OLP subjects were enrolled in the study as were 13 age-sex matched controls. In each subject, lesion tissue transudates (TTs) were collected by a novel collection technique with a filter paper. The level of cytokines, TNF-alpha, IL-1-alpha, IL-6, and IL-8 in three types of oral fluids were determined by ELISA.

RESULTS

In the tissue transudate(TT), there were significantly higher level of cytokines TNF-alpha, IL-1-alpha, IL-6, and IL-8 detected in OLP patients than in controls: (TT: 40.0 +/- 9.8 versus 4.5 +/- 0.7, 710 +/- 114 versus 305 +/- 78, 150 +/- 25 versus 1.7 +/- 0.5, 2800 +/- 260 versus 1450 +/- 130, P < .0001; unit: pg/mL).

CONCLUSIONS

These results indicate that NF-kappa B dependent inflammatory cytokines may be detected at increased levels in oral lesion tissue transudates which may have diagnostic and prognostic potentials for monitoring disease activity and making therapeutic decisions in patients with OLP.

Genetics of sarcoidosis: candidate genes and genome scans

Human leukocyte antigen class II allele associations and T-cell receptor beta chain bias in sarcoidosis suggest a specific disease-triggering antigen exposure in a genetically susceptible host. The cause of sarcoidosis has been elusive, but genetics provides one of the few promising avenues to further our understanding. We review the association studies and genome scans used to identify the genes involved in sarcoidosis.

Fractalkine in rheumatoid arthritis and allied conditions

Leukocyte adhesion and trafficking at the endothelium requires both adhesion molecules and chemotactic factors. Fractalkine (CX3C) is a unique chemokine, and is expressed on tumor necrosis factor-alpha- and interleukin-1-activated endothelial cells (ECs). Fractalkine receptor, CX3CR1, is expressed on NK cells, monocytes, and some portion of CD4- and CD8-positive T cells. Interactions between fractalkine and CX3CR1 can mediate not only chemotaxis, but also cell adhesion in the absence of substrates for other adhesion molecules. Furthermore, fractalkine activates NK cells, leading to increased cytotoxicity and interferon-gamma production. Recently, accumulating evidence has shown that fractalkine is involved in the pathogenesis of rheumatoid arthritis and allied conditions. This review examines new concepts underlying fractalkine-mediated leukocyte migration and tissue damage, focusing primarily on the pathophysiological roles of fractalkine in rheumatic diseases.

Modulation of adipokines and cytokines in gestational diabetes and macrosomia

CONTEXT/OBJECTIVE

Not much is known about the implication of adipokines and different cytokines in gestational diabetes mellitus (GDM) and macrosomia. The purpose of this study was to assess the profile of these hormones and cytokines in macrosomic babies, born to gestational diabetic women.

DESIGN/SUBJECTS

A total of 59 women (age, 19-42 yr) suffering from GDM with their macrosomic babies (4.35 +/- 0.06 kg) and 60 healthy age-matched pregnant women and their newborns (3.22 +/- 0.08 kg) were selected.

METHODS

Serum adipokines (adiponectin and leptin) were quantified using an obesity-related multiple ELISA microarray kit. The concentrations of serum cytokines were determined by ELISA.

RESULTS

Serum adiponectin levels were decreased, whereas the concentrations of leptin, inflammatory cytokines, such as IL-6 and TNF-alpha, were significantly increased in gestational diabetic mothers compared with control women. The levels of these adipocytokines were diminished in macrosomic babies in comparison with their age-matched control newborns. Serum concentrations of T helper type 1 (Th1) cytokines (IL-2 and interferon-gamma) were decreased, whereas IL-10 levels were significantly enhanced in gestational diabetic mothers compared with control women. Macrosomic children exhibited high levels of Th1 cytokines and low levels of IL-10 compared with control infants. Serum IL-4 levels were not altered between gestational diabetic mothers and control mothers or the macrosomic babies and newborn control babies.

CONCLUSIONS

GDM is linked to the down-regulation of adiponectin along with Th1 cytokines and up-regulation of leptin and inflammatory cytokines. Macrosomia was associated with the up-regulation of Th1 cytokines and the down-regulation of the obesity-related agents (IL-6 and TNF-alpha, leptin, and adiponectin).

Concurrent exposure to thermal stress and oral Ag induces intestinal sensitization in the mouse by a mechanism of regulation of IL‐12 expression

The mechanism of food allergy remains unclear. The absorption of intact protein Ag into the intestinal tissue is a prerequisite in the development of intestinal sensitization. Previous studies indicate that thermal stress compromises the intestinal barrier function. Mice were concurrently exposed to thermal stress and oral Ag. Intestinal sensitivity, levels of serum-specific IgE, IL-4 and INF-gamma were assessed. Intestinal dendritic cell, Th1 and Th2 functions were determined. The mice that were treated with thermal stress and oral Ag showed high levels of serum Ag-specific IgE, intestinal mast cell activation in response to oral Ag challenge, suppression of IL-12 expression in the intestinal dendritic cells, inhibition of T-bet expression and Th1 function and marked increases in (GATA)3 expression and Th2 function. Mice exposed to thermal stress alone or oral Ag alone did not show any signs of the intestinal sensitization. Pretreatment with IL-12 inhibited the intestinal sensitization induced by the concurrent exposure to thermal stress and Ag gavage. We conclude that although Ag absorption is essential, Ag absorption alone is insufficient; other accessory factors that can disturb the local immune homeostasis are also required for the induction of intestinal sensitization. The present study illustrates that concurrent exposure to thermal stress and oral Ag can prove to be a factor in the induction of intestinal sensitization by a mechanism of regulating IL-12 expression.

1-Methyl-tryptophan can interfere with TLR signaling in dendritic cells independently of IDO activity

The compound 1-methyl-tryptophan (1-MT) is a competitive inhibitor of IDO that can break tolerance and induce fetus, graft, and tumor rejection. Because of its broad effect on immune-related mechanisms, the direct action of 1-MT on human monocyte-derived dendritic cells (DC) was analyzed. It is shown here that the effect of 1-MT on DC is dependent on the maturation pathway. Although 1-MT had no effect on DC stimulated by the TLR3 ligand poly(I:C), it strongly enhanced the Th1 profile of DC stimulated with TLR2/1 or TLR2/6 ligands. Drastic changes in the function of DC stimulated by the TLR4 ligand LPS were induced by 1-MT. These cells could still activate allogeneic and syngeneic T cells but stimulation yielded T cells secreting IL-5 and IL-13 rather than IFN-gamma. This action of 1-MT correlated with an increased phosphorylation of p38 and ERK MAPKs and sustained activation of the transcription factor c-Fos. Inhibiting p38 and ERK phosphorylation with synthetic inhibitors blocked the effect of 1-MT on LPS-stimulated DC. Thus, 1-MT can modulate DC function depending on the maturation signal and independently of its action on IDO. This is consistent with previous observations and will help further understanding the mechanisms of DC polarization.

Characterization of RNA helicase A as component of STAT6-dependent enhanceosome

Signal transducer and activator of transcription 6 (STAT6) is a regulator of transcription for interleukin-4 (IL-4)-induced genes. The ability of STAT6 to activate transcription depends on functional interaction with other transcription factors and coactivators. We have characterized the mechanism of STAT6-mediated transcriptional activation by identifying STAT6 transcription activation domain (TAD) interacting nuclear proteins. The first of the identified proteins was coactivator protein p100, which regulates IL-4-induced transcription by connecting STAT6 with other transcriptional regulators. Here, we describe RNA helicase A (RHA) as a novel component of STAT6 transcriptosome. In vitro and in vivo experiments indicated that RHA did not directly interact with STAT6, but p100 protein was found to mediate the assembly of the ternary complex of STAT6-p100-RHA. In chromatin immunoprecipitation studies RHA together with p100 enhanced the binding of STAT6 on the human Igɛ promoter after IL-4 stimulation. RHA enhanced the IL-4-induced transcription, and the participation of RHA in IL-4-regulated transcription was supported by RNAi experiments. Our results suggest that RHA has an important role in the assembly of STAT6 transcriptosome. As RHA is also known to interact with chromatin modifying proteins, the RHA containing protein complexes may facilitate the entry of transcriptional apparatus to the IL-4 responsive promoters.

T-box proteins differentially activate the expression of the endogenous interferon γ gene versus transfected reporter genes in non-immune cells

The T-box transcription factor T-bet is expressed in a number of hematopoetic cell types and plays an essential role in the lineage determination of Th1 T-helper cells. In the absence of T-bet, CD4(+) T-cells fail to induce IFNgamma, the cytokine whose expression characterizes Th1 cells. Here we show that, surprisingly, T-bet induces the expression of endogenous IFNgamma in non-immune human cells, including 293 and other cell lines. Thus T-bet can induce IFNgamma expression independently of its role in T-cell lineage determination. In addition, mutations in T-bet, and chimeras of T-bet with other transcription factors including the T-box transcription factor, TBX2, differentially affect the ability of T-bet to activate expression of endogenous IFNgamma versus a T-site regulated reporter gene. A truncated T-betVp16 fusion protein strongly activates the T-site reporter but fails to activate endogenous IFNgamma. Conversely, native T-bet strongly activates endogenous IFNgamma expression but only weakly activates the reporter gene. Fusion of the Vp16 activation domain to full-length T-bet greatly increases its activation of both endogenous IFNgamma and transfected T-site reporter gene expression. In contrast, TBX2Vp16 potently activates the T-site reporter but has a negligible effect on endogenous IFNgamma expression. Butyrate treatment of T-bet expressing cells potentiates the expression of endogenous IFNgamma but weakly represses expression of the T-site reporter gene. These data indicate that induction of endogenous IFNgamma can be uncoupled from differentiation into the Th1 lineage and that the expression of endogenous IFNgamma versus a T-site reporter gene is differentially regulated by T-bet and other T-box proteins.

Mechanism of T cell hyporesponsiveness to HBcAg is associated with regulatory T cells in chronic hepatitis B

AIM

To study the mechanisms of hyporesponsiveness of HBV-specific CD4+ T cells by testing TH1 and TH2 commitment and regulatory T cells.

METHODS

Nine patients with chronic hepatitis B were enrolled. Peripheral blood mononuclear cells were stimulated with HBcAg or HBsAg to evaluate their potential to commit to TH1 and TH2 differentiation. HBcAg-specific activity of regulatory T cells was evaluated by staining with antibodies to CD4, CD25, CTLA-4 and interleukin-10. The role of regulatory T cells was further assessed by treatment with anti-interleukin-10 antibody and depletion of CD4+CD25+ cells.

RESULTS

Level of mRNAs for T-bet, IL-12R beta2 and IL-4 was significantly lower in the patients than in healthy subjects with HBcAg stimulation. Although populations of CD4+CD25highCTLA-4+ T cells were not different between the patients and healthy subjects, IL-10 secreting cells were found in CD4+ cells and CD4+CD25+ cells in the patients in response to HBcAg, and they were not found in cells which were stimulated with HBsAg. Addition of anti-IL-10 antibody recovered the amount of HBcAg-specific TH1 antibody compared with control antibody (P < 0.01, 0.34% +/- 0.12% vs 0.15% +/- 0.04%). Deletion of CD4+CD25+ T cells increased the amount of HBcAg-specific TH1 antibody when compared with lymphocytes reconstituted using regulatory T cells (P < 0.01, 0.03% +/- 0.02% vs 0.18% +/- 0.05%).

CONCLUSION

The results indicate that the mechanism of T cell hyporesponsiveness to HBcAg includes activation of HBcAg-induced regulatory T cells in contrast to an increase in TH2-committed cells in response to HBsAg.

Regulation of GATA-3, c-maf and T-bet mRNA expression in bronchoalveolar lavage cells and bronchial biopsies after segmental allergen challenge

BACKGROUND

GATA-3 (GATA binding protein 3) and the proto-oncogene c-maf are Th2-regulating transcription factors that control the expression of interleukin (IL)-4 and IL-5, while T-bet (T-box expressed in T cells) is a Th1-specific transcription factor that controls the expression of interferon (IFN-gamma). Allergen provocation in asthmatics induces a Th2-dominated cytokine profile, but so far it is unknown whether the skewed cytokine expression is reflected by the expression of the respective transcriptional regulators.

OBJECTIVE

The aim of this study was to determine the regulation of Th1- and Th2-specific transcription factors and cytokines in 10 atopic subjects with mild asthma and 5 nonatopic healthy controls at baseline and after segmental sham and allergen challenge.

METHODS

The mRNA expression of GATA-3, c-maf and T-bet was determined by real-time polymerase chain reaction in bronchoalveolar lavage (BAL) cells and bronchial biopsies. The percentage of IL-4+, IL-5+ and IFN-gamma+ BAL T cells was determined by flow cytometry, and BAL levels of these cytokines were measured by ELISA.

RESULTS

In BAL cells of asthmatics, the mRNA expression of all transcription factors was increased after allergen challenge. In bronchial biopsies, the basal expression of GATA-3 was increased in asthmatics compared to healthy controls but decreased after allergen challenge. Compared to sham challenge, the percentage of IL-5+/CD4+ BAL T cells was increased after allergen challenge in asthmatics while the percentage of IFN-gamma+/CD4+ and IFN-gamma+/CD8+ T cells was decreased. Expression of c-maf mRNA in BAL cells correlated with IL-4+/CD4+ BAL cells and BAL IL-5 levels.

CONCLUSIONS

Segmental allergen challenge in asthmatics leads to increased GATA-3, c-maf and T-bet expression in BAL cells but not in bronchial biopsies.

Differential expression of genes involved in skin homing, proliferation, and apoptosis in CD4+ T cells of patients with atopic dermatitis

CD4+ T cells play a critical role in allergic diseases, both in the affected tissue as well as systemically. Our objective was to investigate the in vivo activation state of peripheral blood CD4+ T cells of atopic dermatitis (AD) patients by analyzing gene expression profiles of unstimulated CD4+ T cells. mRNA samples from blood CD4+ T cells, isolated from five AD patients and seven healthy controls (HC), were analyzed using oligonucleotide arrays. Differentially regulated genes were validated by quantitative PCR (Q-PCR) in a larger group of patients with AD, in a group of patients with allergic asthma (AA), and HC subjects. In addition, "typical" T helper type 1 (Th1)- and Th2-related genes were analyzed by Q-PCR. Microarray analysis revealed differential expression of 52 genes in AD patients. Q-PCR confirmed several differentially regulated genes in AD, including CCR10, CRTH2, C-JUN, and NR4A2. Two groups of genes with highly correlating gene expression levels involved in tissue homing and proliferation or apoptosis, respectively, were identified. No marked differences were found in gene expression levels of typical Th1 or Th2 genes in AD or in AA patients. This study demonstrates that peripheral blood, unstimulated CD4+ T cells in AD patients show differentially expressed genes involved in tissue homing, proliferation, and apoptosis. No marked expression differences of "typical" atopy genes were found.

T-bet, a Th1 transcription factor, is up-regulated in T cells from patients with aplastic anemia

In aplastic anemia, immune destruction of hematopoietic cells results in bone marrow failure. Type 1 cytokines, especially IFN-gamma, have been implicated in the pathophysiology of T-cell-mediated, Fas-mediated stem cell apoptosis of hematopoietic cells. Here, we show that the transcription factor T-bet (T-box expressed in T cells) is increased in T cells from patients with aplastic anemia. Patients' T-bet bound directly to the proximal site of the IFN-gamma promoter without any prior stimulation, in contrast to healthy controls. Increased levels of Itk kinase participated in T-bet up-regulation and active transcription of the IFN-gamma gene observed in these patients. Blocking PKC-, a kinase that lies downstream of Itk kinase, decreased T-bet protein and IFN-gamma intracellular levels. These data suggest that the increased IFN-gamma levels observed in aplastic anemia patients are the result of active transcription of the IFN-gamma gene by T-bet. Blocking the transcription of the IFN-gamma gene with kinase inhibitors might lead to the development of novel therapeutic agents for patients with aplastic anemia and other autoimmune diseases.

STAT4 expression in human T cells is regulated by DNA methylation but not by promoter polymorphism

STAT4, which plays a pivotal role in Th1 immune responses, enhances IFN-gamma transcription in response to the interaction of IL-12 with the IL-12R. Mice deficient in STAT4 lack IL-12-induced IFN-gamma production and Th1 differentiation and display a predominantly Th2 phenotype. Although these findings indicate that STAT4 expression levels are important for the development of cytokine-producing Th1 cells, the transcriptional and posttranscriptional mechanisms regulating STAT4 expression are unknown. We sought to identify and characterize the transcriptional regulatory elements in the promoter region of the human STAT4 gene. We found that disruption of multiple transcriptional regions covering the CREB, OCT1, and SP1 motifs significantly reduced STAT4 promoter activity. However, genomic DNA isolated from 91 patients with asthma or rheumatoid arthritis showed no evidence of mutations in the defined STAT4 essential promoter region. The 5' flanking region of the promoter was found to contain a -149A/G change in approximately 20-35% of patients, but this polymorphism had no effect on promoter activity. Interestingly, STAT4 expression was drastically increased in human T cells following treatment with a DNA methyltransferase inhibitor, and truncation of methylation sites in the proximal regulatory elements of the STAT4 promoter markedly enhanced transcriptional activity. Thus, our findings provide molecular insight into STAT4 expression and suggest that, in human T cells, STAT4 expressional regulation is associated with DNA hypermethylation, but not promoter polymorphisms.

Predominance of type 1 CD4+ T cells in human abdominal aortic aneurysm

The functional repertoire of T cells in abdominal aortic aneurysm (AAA) and the exact nature of aortic wall adaptive cellular immune responses still remains a matter of debate. In this study, we sought to determine whether type 1 or type 2 responses occur predominantly in human aneurysmal aortic lesions. We first examined the phenotype and cytokine secretion profile of T lymphocytes freshly isolated from aneurysmal aortic wall for comparison with their circulating counterparts using flow cytometry. We found that both populations of infiltrating CD4(+) and CD8(+)T cells displayed a unique activated memory phenotype. In addition, we identified the presence in human aneurysmal aortic lesion of CD4(+)T cells producing high levels of interferon (IFN)-gamma but not interleukin (IL)-4, reflecting their type 1 nature. Quantitative analysis of cytokine gene expression confirmed increased IFN-gamma transcript levels in infiltrating cells compared to controls. We next analysed aortic wall responses using LightCycler-based quantitative real-time reverse transcription-polymerase chain reaction. Compared to control non-diseased aortic samples, we demonstrated that whole AAA tissues exhibited high mRNA levels of IFN-gamma but not IL-4. Overexpression of the transcription factor T-bet in the absence of significant GATA-3 expression further assessed the type 1 polarization of aortic wall immune responses. These findings indicate that type 1 CD4(+)T cells predominate in human AAA lesions. This study has important implications for the pathogenesis of aneurysm disease. Through the production of IFN-gamma, T cells may indeed contribute to orchestrate extracellular matrix remodelling.

Increased GILZ expression in transgenic mice up-regulates Th-2 lymphokines

GILZ (glucocorticoid-induced leucine zipper), a gene induced by dexamethasone, is involved in control of T lymphocyte activation and apoptosis. In the present study, using Gilz transgenic mice (TG), which overexpress GILZ in the T-cell lineage, we demonstrate that Gilz is implicated in T helper-2 (Th-2) response development. After in vitro stimulation by CD3/CD28 antibodies, peripheral naive CD4+ T cells from TG mice secrete more Th-2 cytokines such as interleukin-4 (IL-4), IL-5, IL-13, and IL-10, and produce less Th-1 cytokines such as interferon-gamma (IFN-gamma) than wild-type mice (WT). CD4+ TG lymphocytes up-regulated Th-2 cytokine expression in the specific response to ovalbumin chicken egg (OVA) antigen immunization. Up-regulation correlated with increased expression of GATA-3 and signal transducer and activator of transcription 6 (Stat6), Th-2-specific transcription factors and decreased expression of T-bet, a transcription factor involved in Th-1 differentiation. Finally, in TG mice delayed-type hypersensitivity, a Th-1 response, was inhibited and bleomycin-induced pulmonary fibrosis, a Th-2 mediated disease, was more severe. These results indicate that Gilz contributes to CD4+ commitment toward a Th-2 phenotype and suggest this contribution may be another mechanism accounting for glucocorticoid immunomodulation.

All-trans retinoic acid biases immune response induced by DNA vaccine in a Th2 direction

Vitamin A deficiency diminishes Th2-mediated Ab responses. Providing Vitamin A or its active metabolites reverses this defect. All-trans retinoic acid (ATRA), an acid derivation of Vitamin A, regulates the balance of immune response induced by TR421-hCGbeta DNA vaccine. Compared to DNA vaccine alone or treatment with vehicle, significantly higher level of antibody against the protein encoded by DNA vaccine was observed in mice 6 weeks after the first immunization. The IgG2a/IgG1 ratio was lower in mice treated with ATRA. We also found that treatment with ATRA also diminishes specific cellular immune response induced by gene immunization by measuring the marker of cellular immune response. We conclude that ATRA biases the immune response to Th2 direction induced by DNA vaccine and acts as a candidate adjuvant and immunomodulatory molecule.

Automated classification and analysis of the calcium response of single T lymphocytes using a neural network approach

The gene activities in T lymphocytes that regulate immune responses are influenced by Ca2+ ([Ca2+]i). The intracellular calcium signals are highly heterogeneous and vitally important in determining the immune outcome. The signals in individual cells can be measured using fluorescence microscopy but to group the cells into classes with similar signal kinetics is currently laborious. Here, we demonstrate a method for the automated classification of the responses into four categories formerly identified by an expert's inspection. This method comprises characterising the response by a second-order model, performing frequency analysis, and using derived features as inputs to two multilayer perceptron neural networks (NNs). We compare the algorithm's performance on an example data set against the human classification: it was found to classify identically more than 70% of the data, despite small sample sizes in two categories and significant overlap between the other two classes. The group characterized by an oscillating signal showed the presence of a number of frequencies, which may be important in determining gene activation. A classification threshold enables the automatic identification of patterns with a low-classification certainty. Future refinement of the algorithm may allow the identification of more classes, which may be important in different immune responses associated with disease.

Retinoic acid and polyriboinosinic:polyribocytidylic acid stimulate robust anti-tetanus antibody production while differentially regulating type 1/type 2 cytokines and lymphocyte populations

Retinoic acid (RA), a bioactive retinoid, and polyriboinosinic:polyribocytidylic acid (PIC) are known to promote immunity in vitamin A-deficient animals. In this study, we hypothesized that RA, PIC, and the combination can provide significant immunoadjuvant activity even in the vitamin A-adequate state. Six-week-old C57BL/6 mice were immunized with tetanus toxoid (TT) and treated with RA and/or PIC at priming in three independent studies of short and long duration. RA and PIC differentially regulated both primary and secondary anti-TT IgG isotypes, whereas the combination of RA + PIC stimulated the highest level of anti-TT IgG production and, concomitantly, a ratio of IgG1 to IgG2a similar to that of the control group. The regulation of Ab response was strongly associated with type 1/type 2 cytokine gene expression. Whereas RA reduced type 1 cytokines (IFN-gamma and IL-12), PIC enhanced both type 1 and type 2 cytokines (IL-4 and IL-12) and cytokine-related transcription factors. Despite the presence of PIC, the IL-4:IFN-gamma ratio was significantly elevated by RA. In addition, RA and/or PIC modulated NK/NKT cell populations and the level of expression of the costimulatory molecules CD80/CD86, evident 3 days after priming. Notably, the NKT:NK and CD80:CD86 ratios were correlated with the IL-4:IFN-gamma ratio, indicative of multiple converging modes of regulation. Overall, RA, PIC, and RA + PIC rapidly and differentially shaped the anti-tetanus Ig response. The robust, durable, and proportionate increase in all anti-TT IgG isotypes induced by RA + PIC suggests that this combination is promising as a means to enhance the Ab response to TT and similar vaccines.

Differential effects of three antibiotics on T helper cell cytokine expression

OBJECTIVES

To test whether ciprofloxacin, moxifloxacin and clarithromycin affect the expression of the T helper (Th) cell cytokines, interferon-gamma and interleukin-4. Quinolone and macrolide antibiotics are routinely used for the treatment of critically ill patients with sepsis. These antibiotics modulate some aspects of immune cell function. Alteration in the profile of Th cell cytokine expression will affect the T helper cell ratio and subsequent immune responses.

METHODS

Following ethics committee approval and informed consent, mononuclear cells were isolated from 20 healthy volunteers using single density gradient centrifugation. Cells were incubated with ciprofloxacin (0--100 mg/L), moxifloxacin (0--50 mg/L) or clarithromycin (0--125 mg/L) and stimulated with phorbol myristate acetate and ionomycin. For flow cytometric analysis, cells were stained with antibodies to CD3 and CD4, prior to permeabilization with saponin and intracellular staining with anti-interleukin-4 and anti-interferon-gamma.

RESULTS

Both moxifloxacin and ciprofloxacin dose-dependently decreased interferon-gamma and interleukin-4 expression by Th cells (both P<0.0001). Only interleukin-4 expression however, was affected by clarithromycin (P=0.04). There was no change in the Th1/Th2 ratio for moxifloxacin or ciprofloxacin, but the Th1/Th2 ratio increased with increasing concentrations of clarithromycin, from a median [range] of 5.3 [1.3--16.0] without antibiotic to 9.1 [1.8--18.8] at 125 mg/L (P=0.017).

CONCLUSIONS

Moxifloxacin and ciprofloxacin had pronounced effects on both Th1 and Th2 cytokine expression, without altering Th1/Th2 ratios. However, clarithromycin decreased only interleukin-4 expression such that the Th1/Th2 ratio increased. Since a Th1 profile is considered favourable for resolution of infection, elucidation of immunomodulatory profiles of antibiotics may permit more rational antibiotic choice in future.

Cytokines locally produced by lymphocytes removed from the hypertrophic nasopharyngeal and palatine tonsils

OBJECTIVE

Human palatine tonsils and the nasopharyngheal tonsil are the largest components of the Waldeyer's ring. Subepithelial and intraepithelial lymphocytes of human adenoids and tonsils are responsible for the local and the systemic immune response. We studied the cytokine production by lymphoid cells isolated from 16 nasopharyngeal tonsils (adenoid) and 9 palatine tonsils surgically removed by from 25 children (aged from 4 to 15 years) suffering from tonsil hypertrophy.

METHODS

We evaluated (by the cytometry method, using BD Bioscience kits, San Diego, CA) the concentration of IL-2, IL-4, IL-5, IL-10, TNF(alpha) and IFN(gamma) released from human peripheral blood mononuclear cells (MC) (activated or not activated by phytohaemagglutinin (PHA)) cultured in vitro during 72 h. The fluorescence-activated cell sorter (FACS) analysis was also performed and the percentage of mononuclear cells (unstimulated or activated by phorbol acetate during 24 h) stained with the monoclonal antibodies anti-CD3 containing the intracellular cytokines was calculated.

RESULTS

The increased secretion of IL-2, IL-4, IL-5, TNF(alpha) and IFN(gamma) from PHA activated palatine origin immune cell cultures, as compared to adenoids, was revealed. The higher mobilization (Delta%) of CD3+ T-lymphocytes containing IL-12 in palatine cell cultures (798.5+/-276.29%), in comparison with to the adenoids (298.5+/-49.16%; p< or =0.05), was also noted.

CONCLUSION

In palatine tonsils, as compared to adenoids, the cellular immune (Th1) response dominates over humoral immune (Th2) reaction.

Ras-ERK MAPK cascade regulates GATA3 stability and Th2 differentiation through ubiquitin-proteasome pathway

Differentiation of naive CD4 T cells into Th2 cells requires protein expression of GATA3. Interleukin-4 induces STAT6 activation and subsequent GATA3 transcription. Little is known, however, on how T cell receptor-mediated signaling regulates GATA3 and Th2 cell differentiation. Here we demonstrated that T cell receptor-mediated activation of the Ras-ERK MAPK cascade stabilizes GATA3 protein in developing Th2 cells through the inhibition of the ubiquitin-proteasome pathway. Mdm2 was associated with GATA3 and induced ubiquitination on GATA3, suggesting its role as a ubiquitin-protein isopeptide ligase for GATA3 ubiquitination. Thus, the Ras-ERK MAPK cascade controls GATA3 protein stability by a post-transcriptional mechanism and facilitates GATA3-mediated chromatin remodeling at Th2 cytokine gene loci leading to successful Th2 cell differentiation.

Transcriptional control of impaired Th1 responses in patent lymphatic filariasis by T-box expressed in T cells and suppressor of cytokine signaling genes

T-bet (T-box expressed in T cells) and GATA-3 are transcription factors that play a critical role in the development of Th1 and Th2 cells, as do genes of the SOCS (suppressor of cytokine signaling) family, albeit indirectly. Another transcription factor, Foxp3, is a master regulator of natural regulatory T cells (Tregs). To identify the role of these factors in impaired Th1 responses of patent filarial infection, analysis of cytokine, SOCS, and transcription factor mRNA expression was performed on purified T cells of filaria-infected individuals (n = 6) and uninfected controls (n = 6). As expected (and in contrast to cells of uninfected individuals), there was a significant depression of gamma interferon (IFN-gamma) and a concomitant increase in interleukin-4 (IL-4), IL-5, and IL-10 mRNA expression following stimulation with parasite antigen (BmA) but not with a polyclonal T-cell (anti-CD3) stimulus. T-bet (but not GATA-3) was expressed at significantly lower levels in cells of filaria-infected individuals in response to BmA compared with those from the uninfected group, accounting, at least partially, for the diminished IFN-gamma expression. Second, we found no significant differences in expression of Foxp3 between the two groups, although induction of Foxp3 expression correlated with induced expression levels of IL-10, implicating Tregs in the IL-10 expression seen. Finally, parasite-specific T-cell expression of SOCS-1, SOCS-5, and SOCS-7 was significantly diminished among infected patients; in contrast, expression of SOCS-3 increased. Our data therefore indicate that the impaired Th1 responses observed in patent lymphatic filariasis are associated with decreased expression of T-bet, SOCS-1, SOCS-5, and SOCS-7 and increased expression of SOCS-3 in T cells.

Effects of dietary n-3 polyunsaturated fatty acids on T-cell membrane composition and function

Dietary n-3 PUFA have been shown to attenuate T-cell-mediated inflammation, in part, by suppressing T-cell activation and proliferation. n-3 PUFA have also been shown to promote apoptosis, another important mechanism for the prevention of chronic inflammation by maintaining T-cell homeostasis through the contraction of populations of activated T cells. Recent studies have specifically examined Fas death receptor-mediated activation-induced cell death (AICD), since it is the form of apoptosis associated with peripheral T-cell deletion involved in immunological tolerance and T-cell homeostasis. Data from our laboratory indicate that n-3 PUFA promote AICD in T helper 1 polarized cells, which are the mediators of chronic inflammation. Since Fas and components of the death-inducing signaling complex are recruited to plasma membrane microdomains (rafts), the effect of dietary n-3 PUFA on raft composition and resident protein localization has been the focus of recent investigations. Indeed, there is now compelling evidence that dietary n-3 PUFA are capable of modifying the composition of T-cell membrane microdomains (rafts). Because the lipids found in membrane microdomains actively participate in signal transduction pathways, these results support the hypothesis that dietary n-3 PUFA influence signaling complexes and modulate T-cell cytokinetics in vivo by altering T-cell raft composition.

HPV16, HPV18, and HIV infection may influence cervical cytokine intralesional levels

Infection with oncogenic human papillomavirus (HPV) is considered to be the major risk to cervical cancer. This study analyzed the influence of HPV infection on cytokine intralesional levels in cervical lesion in the presence or not of HIV infection. Cervical biopsies from 42 women were studied. HPV detection and typing were performed using amplified DNA hybridized with sequence-specific primers, and cytokine intralesional levels were detected using ELISA. HPV16+ biopsies exhibited increased IFN-gamma and IL-10 when compared to HPV16- (P = 0.03 and 0.04, respectively). HPV18+ biopsies exhibited decreased TNF-alpha (P = 0.009) and IFN- gamma (P = 0.01) when compared to HPV18-. In accordance to HIV status, HIV-/HPV16+ patients exhibited increased IFN-gamma when compared to those presenting HIV-/HPV16- (P = 0.007). HIV-/HPV18+ patients presented decreased IFN-gamma when compared to HIV-/HPV18- (P = 0.02). These results suggest that the presence of HPV16 infection may influence cervical lesion installation, and irrespective of HIV status, HPV18 infection may be more aggressive than HPV-16.

Mucosal T lymphocytes--peacekeepers and warriors

Normal immune homeostasis of the intestine requires peaceful coexistence with commensal flora, combined with host defense against pathogens. Perhaps as a result of this unique dilemma, distinct populations of regulatory and effector T lymphocytes are found in the lamina propria and epithelium of the intestine. Here we summarize the properties and functions of these unusual T cells, and describe the molecular and cellular interactions that lead to their development and function. Some mucosal T cells, sometimes called type a, are conventional activated/memory T cells that have received instructions to migrate to the intestine during priming by dendritic cells in the mesenteric lymph node and elsewhere. Others, however, particularly subsets residing permanently in the epithelium, are intestine-specific T cell subpopulations generated by an atypical differentiation pathway.

Vitamin D receptor gene polymorphisms, particularly the novel A-1012G promoter polymorphism, are associated with vitamin D3 responsiveness and non-familial susceptibility in psoriasis

Psoriasis is a genetically determined disease characterized by hyperproliferation and disordered maturation of the epidermis. Th1 lymphocytes are implicated in its pathogenesis. The vitamin D receptor (VDR) is a candidate modifying gene, having immunosuppressive effects and being involved in anti-proliferative and pro-differentiation pathways in keratinocytes. There is suggestive evidence that the A allele of the A-1012G polymorphism is associated with down-regulation of the Th1 response, via GATA-3. The F and T alleles of Fok1 and Taq1 have been associated with increased VDR activity. The present study aimed to test the hypothesis that the A allele of A-1012G is protective for occurrence and severity of psoriasis and enhances therapeutic response to vitamin D analogues and that these effects would be additive to those of Fok1 and Taq1. The study group comprised 206 psoriasis patients who had received topical calcipotriol treatment and 80 controls. There was no significant linkage disequilibrium between any pair of the three polymorphic sites (P=0.3-0.8). The A, F and T alleles were positively associated with calcipotriol response: AA genotype (compared to AG/GG), odds ratio (OR)=2.18 (P=0.04); TT, OR=1.97 (P=0.03); AAFF genotype combination, OR=4.11 (P=0.03); AATT, OR=5.64 (P=0.005); and FFTT, OR=3.22 (P=0.01). Comparing patients without, to patients with, a family history of psoriasis, the A allele was under represented (P=0.01) and the AAFF genotype combination even more so (compared to residual genotypes) (OR=0.24; P=0.005). AAFF was also under-represented in patients without a family history compared to controls (OR=0.31; P=0.04). There were no associations of family history with Fok1 and Taq1. There were no associations of severity of psoriasis with any polymorphism. In conclusion, the A-1012G, Fok1 and Taq1 VDR polymorphisms were associated with response to calcipotriol. A-1012G and Fok1 were associated with susceptibility to non-familial psoriasis.

Signaling pathways in Th2 development

In order for an immune response to be successful, it must be of the appropriate type and magnitude. Intracellular residing pathogens require a cell-mediated immune response, whereas extracellular pathogens evoke a humoral immune response. T-helper (Th) cells orchestrate the immune response and are divided into two subsets, Th1 and Th2 cells. Here, we discuss the mechanisms of Th2 development with a focus on signal transduction pathways that influence Th2 differentiation.

Altered T helper 1 reaction but not increase of virus load in patients with dengue hemorrhagic fever

To investigate whether dengue-2 patients with and without dengue hemorrhagic fever had different virus load, immune mediators, or T helper (Th) reaction, we simultaneously measured virus load, immune mediators and the Th1/Th2 transcription factors T-bet/GATA-3 mRNA expression in a large outbreak of dengue-2 infections in Southern Taiwan. Results showed that virus load was not significantly different between patients with and without dengue hemorrhagic fever. Patients with dengue fever had higher IFN-gamma levels, but patients with dengue hemorrhagic fever had significantly higher IL-10 levels. Further studies showed that patients with dengue hemorrhagic fever had a significantly lower T-bet than those with dengue fever, but GATA-3 mRNA expression in peripheral blood leukocytes was not significant difference between both groups. In conclusion, altered Th1 reaction as reflected by lower T-bet mRNA expression associated with higher IL-10 levels might be involved in the pathogenesis of dengue hemorrhagic fever.

The transcriptional co-activator protein p100 recruits histone acetyltransferase activity to STAT6 and mediates interaction between the CREB-binding protein and STAT6

STAT6 is a critical regulator of transcription for interleukin-4 (IL-4)-induced genes. Activation of gene expression involves recruitment of coactivator proteins that function as bridging factors connecting sequence-specific transcription factors to the basal transcription machinery, and as chromatin-modifying enzymes. Coactivator proteins CBP/p300 have been implicated in regulation of transcription in all STATs. CBP is also required for STAT6-mediated gene activation, but the underlying molecular mechanisms are still elusive. In this study we investigated the mechanisms by which STAT6 recruits CBP and chromatin-modifying activities to the promoter. Our results indicate that while STAT1-interacted directly with CBP, the interaction between STAT6 and CBP was found to be mediated through p100 protein, a coactivator protein that has previously been shown to stimulate the transcription of IL-4-induced genes. The staphylococcal nuclease-like (SN)-domains of p100 directly interacted with amino acids 1099-1758 of CBP, while p100 did not associate with SRC-1, another coactivator of STAT6. p100 was found to recruit histone acetyltransferase (HAT) activity to STAT6 in vivo. Chromatin immunoprecipitation studies demonstrated that p100 increases the STAT6-p100-CBP ternary complex formation in the human Igepsilon promoter. p100 also increased the amount of acetylated histone H4 at the Igepsilon promoter, and siRNAs directed against p100 effectively inhibited Igepsilon reporter gene expression. Our results suggest that p100 has an important role in the assembly of STAT6 transcriptosome, and that p100 stimulates IL-4-dependent transcription by mediating interaction between STAT6 and CBP and recruiting chromatin modifying activities to STAT6-responsive promoters.

Transcriptional regulation of interleukin 2 in SLE T cells

Interleukin-2 (IL-2) is a central cytokine required for the activation of T, B, and NK cells. It propagates the immune response and terminates it by promoting the activation induced cell death of T cells. IL-2 production is altered in T cells of patients with systemic lupus erythematosus (SLE). The consequence of reduced IL-2 production in SLE is decreased immune response to infectious agents. Decreased IL-2 production by SLE T cells is the result of transcriptional repression of the IL-2 gene. This article will review the defective transcription regulation of IL-2 in SLE T cells, which is the result of decreased expression of the enhancers NF-kappa B and AP1 and the increased expression of the transcriptional repressor CREM.

TGF-beta suppresses tumor progression in colon cancer by inhibition of IL-6 trans-signaling

Alterations of TGF-beta signaling have been described in colorectal cancer, although the molecular consequences are largely unknown. By using transgenic mice overexpressing TGF-beta or a dominant-negative TGF-betaRII, we demonstrate that TGF-beta signaling in tumor infiltrating T lymphocytes controls the growth of dysplastic epithelial cells in experimental colorectal cancer, as determined by histology and a novel system for high-resolution chromoendoscopy. At the molecular level, TGF-beta signaling in T cells regulated STAT-3 activation in tumor cells via IL-6. IL-6 signaling required tumor cell-derived soluble IL-6R rather than membrane bound IL-6R and suppression of such TGF-beta-dependent IL-6 trans-signaling prevented tumor progression in vivo. Taken together, our data provide novel insights into TGF-beta signaling in colorectal cancer and suggest novel therapeutic approaches for colorectal cancer based on inhibition of TGF-beta-dependent IL-6 trans-signaling.

Silencing T-bet defines a critical role in the differentiation of autoreactive T lymphocytes

As a means of developing therapies that target the pathogenic T cells in multiple sclerosis (MS) without compromising the immune system or eliciting systemic side effects, we investigated the use of T-bet-specific antisense oligonucleotides and small interfering RNAs (siRNA) to silence T-bet expression in autoreactive encephalitogenic T cells and evaluated the biological consequences of this suppression in experimental autoimmune encephalomyelitis, a model for MS. The T-bet-specific AS oligonucleotide and siRNA suppressed T-bet expression, IFNgamma production, and STAT1 levels during antigen-specific T cell differentiation. In vitro suppression of T-bet during differentiation of myelin-specific T cells and in vivo administration of a T-bet-specific antisense oligonucleotide or siRNA inhibited disease. T-bet was shown to bind the IFNgamma and STAT1 promoters, but did not regulate the IL-12/STAT4 pathway. Since T-bet regulates IFNgamma production in CD4(+) T cells, but to a lesser extent in most other IFNgamma-producing cells, T-bet may be a target for therapeutics for Th1-mediated diseases.

Variability in cytokine production and cell proliferation by mitogen-activated ovine peripheral blood mononuclear cells: modulation by interleukin (IL)-10 and IL-12

T-cell reactivity is typically measured by cell proliferation and/or production of cytokines in response to antigenic/mitogenic stimulation. The choice of assays is more limited in ruminants than rodents, and complicated by the variability inherent in outbred populations. We have measured proliferation and production of interferon-gamma (IFN-gamma) by peripheral blood mononuclear cells (PBMC) from 24 sheep, and compared the responses between sheep, within sheep over several sample points, and also drawn comparisons between the two assays. PBMC derived from different sheep varied by as much as ten-fold in both proliferation and IFN-gamma production, though not necessarily at the same sample time. Thus, there was a poor correlation between the two assays and also considerable variation in the responses from the same animal at different time points. Both parameters could be modulated by exogenous recombinant ovine interleukin (IL)-10 and IL-12, but we were unable to correlate IFN-gamma production with endogenous cytokine production in the assays. These data highlight the importance of assay selection for the measurement of immune responsiveness and also demonstrate the variation that can be expected between sheep and over time.

Impaired type I IFN-induced Jak/STAT signaling in FA-C cells and abnormal CD4+ Th cell subsets in Fancc-/- mice

The Fanconi anemia (FA) group C protein, FANCC, interacts with STAT1 following stimulation with IFN-gamma and is required for proper docking of STAT1 at the IFN-gamma receptor alpha-chain (IFN-gammaRalpha, IFN-gammaR1). Consequently, loss of a functional FANCC results in decreased activation of STAT1 following IFN-gamma stimulation. Because type I IFN receptors influence the function of type II receptors, and vice versa, we conducted experiments designed to determine whether type I IFN-induced activation of other STAT proteins is compromised in FA-C cells and found that activation of STAT 1, 3, and 5 is diminished in type I IFN-stimulated cells bearing Fancc-inactivating mutations. We also determined that the reduced activation of STATs was accompanied by significant reduction of type I IFN-induced tyrosine kinase 2 and Jak1 phosphorylation. Because tyrosine kinase 2 plays a role in differentiation of Th cells, we quantified cytokine secretion from CD4+ cells and in vitro generated CD4+ Th cell subsets from splenocytes of Fancc null mice to that of heterozygous mice and discovered reduced CD4+ IFN-gamma secretion in the Fancc-/- mouse, indicating impaired Th1 differentiation. We suggest that Fancc mutations result in a subtle immunological defect owing to the failure of FANCC to normally support Jak/STAT signaling.

c-Maf and JunB mediation of Th2 differentiation induced by the type 2 G protein-coupled receptor (VPAC2) for vasoactive intestinal peptide

Vasoactive intestinal peptide and its G protein-coupled receptors, VPAC(1) and VPAC(2), regulate critical aspects of innate and adaptive immunity. T cell VPAC(2)Rs mediate changes in cytokine generation, which potently increase the Th2/Th1 ratio and consequently shift the effector responses toward allergy and inflammation. To examine mechanisms of VPAC(2) promotion of the Th2 phenotype, we analyzed controls of IL-4 transcription in CD4 T cells from T cell-targeted VPAC(2) transgenic (Tg), VPAC(2) knockout, and wild-type (WT) mice. c-maf and junB mRNA, protein, and activity were significantly up-regulated to a higher level in TCR-stimulated CD4 T cells from Tg mice compared with those from knockout and WT C57BL/6 mice. In contrast, GATA3, T-bet, and NFATc levels were identical in WT and Tg CD4 T cells. Vasoactive intestinal peptide binding to VPAC(2) on CD4 T cells specifically induces an up-regulation of the Th2-type transcription factors c-Maf and JunB, which consequently enhances IL-4 and IL-5 production, leading to a Th2-type phenotype.

A novel polymorphism in the 1A promoter region of the vitamin D receptor is associated with altered susceptibilty and prognosis in malignant melanoma

The association of Taq 1 and Fok 1 restriction fragment length polymorphisms of the vitamin D receptor with occurrence and outcome of malignant melanoma (MM), as predicted by tumour (Breslow) thickness, has been reported previously. We now report a novel adenine–guanine substitution −1012 bp relative to the exon 1a transcription start site (A-1012G), found following screening by single-stranded conformational polymorphism of this promoter region. There was a total of 191 MM cases , which were stratified according to conventional Breslow thickness groups, cases being randomly selected from each group to form a distribution corresponding to the known distribution of Breslow thickness in our area, and this population (n=176) was compared to 80 controls. The A allele was over-represented in MM patients and, with GG as reference, odds ratio (OR) for AG was 2.5, 95% confidence interval (CI) 1.1–5.7, (P=0.03) and AA 3.3, CI 1.4–8.1, (P=0.007). The outcome was known in 171 of 191 patients and the A allele was related to the development of metastasis, the Kaplan–Meier estimates of the probability of metastasis at 5 years being: GG 0%; AG 9%, CI 4–16%; AA 21%, CI 12–36%; (P=0.008), and to thicker Breslow thickness groups (P=0.04). The effect on metastasis was independent of tumour thickness and A-1012G may have predictive potential, additional to Breslow thickness. Neither the Fok 1 nor Taq 1 variants (f and t) were significantly related to the development of metastasis, although there was a strong relationship of fftt with the thickest Breslow thickness group (P=0.005). There was an interaction between the A-1012G and Fok 1 polymorphisms (P=0.025) and the Fok 1 variant enhanced the effect of the A allele of the A-1012G polymorphism on metastasis, the probability of metastasis for AAff at 5 years follow-up being 57%, CI 24–92%.

Transgenic overexpression of GATA-3 in T lymphocytes improves autoimmune glomerulonephritis in mice with a BXSB/MpJ-Yaa genetic background

A T helper 1 (Th1)/Th2 imbalance is thought to contribute to the pathogenesis of autoimmune diseases. The differentiation of T cells into Th1 or Th2 subtypes is under the regulation of several transcription factors. Among these, transcription factor GATA-3 is thought to play an indispensable role in the development of T cells and the differentiation of Th2 cells. To examine how a Th1/Th2 imbalance affects the development of autoimmune disease, GATA-3 was overexpressed in the T lymphocytes of C57BL/6 x BXSB/MpJ-Yaa F(1) (Yaa) mice. Yaa mice developed autoimmune nephritis similarly to BXSB/MpJ-Yaa mice, which are commonly used as a model for Th1-dominant murine lupus. GATA-3 overexpression in T cells improved the 50% mortality incidence time for GATA-3-transgenic Yaa mice (41.6 wk), compared with Yaa mice (30.9 wk), and reduced proteinuria, serum creatinine levels, and the severity of glomerulonephritis in GATA-3-transgenic Yaa mice. GATA-3 overexpression in Yaa mice led to simultaneously elevated Th2 Ig (IgG1) and decreased Th1 Ig (IgG2a and IgG3) production and serum IFN-gamma levels. Although IL-4 production remained unchanged, intracellular cytokine analyses demonstrated that IL-5 was induced and IFN-gamma was suppressed in stimulated T cells from the GATA-3-transgenic Yaa mice. These results indicated that abundant GATA-3 was unable to stimulate complete differentiation of Th2 cells but did counteract the dominance of Th1 cells and alleviated the disease severity in Yaa mice. These data suggest that transcriptional regulation therapy may have potential as an effective strategy for treating autoimmune glomerulonephritis.