Transforming growth factor beta (TGF-beta)-dependent inhibition of T helper cell 2 (Th2)-induced autoimmunity by self-major histocompatibility complex (MHC) class II-specific, regulatory CD4(+) T cell lines

Regulatory T Cells Conditioned Media Stimulates Migration in HaCaT Keratinocytes: Involvement of Wound Healing

Purpose

Regulatory T (Treg) cells, a type of immune cell, play a very important role in the immune response as a subpopulation of T cells. In this study, we investigated the effects of Treg cells conditioned media (CM) on cell migration. Various cytokines and growth factors of Treg cells CM can effect on re-epithelialization stage during the wound healing.

Methods

Isolated CD4+CD25+ Treg cells from Peripheral Blood Mononuclear Cells (PBMCs) were cultured and CM obtained. HaCaT keratinocytes were treated with various concentration of Treg cells CM. Cell migration, proliferation and expression of proteins that are related to the Epithelial-Mesenchymal Transition (EMT) process, matrix metalloproteinase-1 (MMP-1) were analyzed.

Results

Above 90% CD4+CD25+ Treg cells were obtained from CD8+ depleted PBMCs and the CM have various cytokines and growth factors.One percent and 5% concentration of Treg cells CM increased HaCaT keratinocytes migration. The Treg cells CM stimulated EMT, which led to the down-regulation of E-cadherin in the HaCaT keratinocytes at the wound edge. The Treg cells CM increased MMP-1, which is involved in tissue remodeling.

Conclusion

Our results suggest that Treg cells CM which has various cytokines and growth factors promote wound healing by stimulating HaCaT keratinocytes migration.

Assessment of soluble cytotoxic T lymphocyte-associated antigen-4, transforming growth factor β1, and platelet-derived microparticles during dasatinib therapy for patients with chronic myelogenous leukemia

BACKGROUND

The outcome for chronic myelogenous leukemia (CML) patients presented in the chronic phase has changed dramatically since the introduction of tyrosine kinase inhibitor (TKI) therapy. Notably, an increased incidence of large granular lymphocytes (LGLs), which is related to immunological conditions, appears to be predictive of a favorable outcome for dasatinib therapy. We therefore examined the immunological characteristics of CML patients during dasatinib therapy by determining the plasma concentrations of five different biomarkers.

METHODS

The plasma levels of biomarkers, specifically interleukin-6, platelet-derived microparticles (PDMPs), soluble vascular cell adhesion molecule 1 (sVCAM-1), transforming growth factor (TGF) β1, and soluble cytotoxic T lymphocyte-associated antigen-4 (sCTLA-4), were measured by ELISA at baseline and after 2 and 6 months of TKI treatment. The incidence of LGLs was estimated by microscopic examination.

RESULTS

The levels of PDMPs, sVCAM-1, and TGFβ1 were significantly elevated in patients with CML. Dasatinib treatment was associated with a significant reduction in the levels of these markers and with an increased incidence of LGLs compared with imatinib or nilotinib treatment. In addition, an increased incidence of LGLs was significantly correlated with a decreased sCTLA-4 level during dasatinib therapy.

CONCLUSION

The assessment of the levels of specific biomarkers may be beneficial to understand the immunological conditions of patients with CML during dasatinib treatment.

Long-term effects: Galectin-1 and specific immunotherapy for allergic responses in the intestine

BACKGROUND AND AIMS

Mast cell activation interferes with the effects of allergen-specific immunotherapy (SIT). Galectin-1 (Gal-1) is capable of regulating immune cells' functions. This study tests the hypothesis that administration of Gal-1 promotes and prolongs the efficacy of SIT via suppressing mast cell activation.

METHODS

An intestinal allergy mouse model was developed. The coadministration of SIT and Gal-1 on suppression of the allergic responses, prevention of mast cell activation, and generation of antigen-specific regulatory T cells (Treg) in the intestine was observed in sensitized mice.

RESULTS

The coadministration of Gal-1 and SIT markedly suppressed the allergic responses in the mouse intestine vs the use of either SIT alone or Gal-1 alone. The Gal-1 binds to the IgE/FcɛRI complexes on the surface of mast cells to prevent mast cell activation during SIT. Gal-1 promoted the SIT-generated allergen-specific Tregs in the intestine of sensitized mice. Coadministration of Gal-1 and SIT significantly enhanced the efficacy of immunotherapy in suppressing allergic responses in the intestine, which lasted for at least for 12 months.

CONCLUSIONS

Long-term effects of specific immunotherapy on intestinal allergy can be achieved with Gal-1/SIT therapy by inhibiting mast cell activation and facilitating Treg development.

Downregulation of TGF-β Receptor-2 Expression and Signaling through Inhibition of Na/K-ATPase

Transforming growth factor-beta (TGF-β) is a multi-functional cytokine implicated in the control of cell growth and differentiation. TGF-β signals through a complex of TGF-β receptors 1 and 2 (TGFβR1 and TGFβR2) that phosphorylate and activate Smad2/3 transcription factors driving transcription of the Smad-target genes. The Na+/K+-ATPase is an integral plasma membrane protein critical for maintaining the electro-chemical gradient of Na+ and K+ in the cell. We found that inhibition of the Na+/K+ ATPase by ouabain results in a dramatic decrease in the expression of TGFβR2 in human lung fibrobalsts (HLF) at the mRNA and protein levels. This was accompanied by inhibition of TGF-β-induced Smad phosphorylation and the expression of TGF-β target genes, such as fibronectin and smooth muscle alpha-actin. Inhibition of Na+/K+ ATPase by an alternative approach (removal of extracellular potassium) had a similar effect in HLF. Finally, treatment of lung alveolar epithelial cells (A549) with ouabain also resulted in the downregulation of TGFβR2, the inhibition of TGF-β-induced Smad phosphorylation and of the expression of mesenchymal markers, vimentin and fibronectin. Together, these data demonstrate a critical role of Na+/K+-ATPase in the control of TGFβR2 expression, TGF-β signaling and cell responses to TGF-β.

TGF-β Signal Transduction in Oro-facial Health and Non-malignant Disease (Part I)

The transforming growth factor-beta (TGF-β) family of cytokines consists of multi-functional polypeptides that regulate a variety of cell processes, including proliferation, differentiation, apoptosis, extracellular matrix elaboration, angiogenesis, and immune suppression, among others. In so doing, TGF-β plays a key role in the control of cell behavior in both health and disease. In this report, we review what is known about the mechanisms of activation of the peptide, together with details of TGF-β signal transduction pathways. This review summarizes the evidence implicating TGF-β in normal physiological processes of the craniofacial complex—such as palatogenesis, tooth formation, wound healing, and scarring—and then evaluates its role in non-malignant disease processes such as scleroderma, submucous fibrosis, periodontal disease, and lichen planus.

The correlation between plasma cytokine levels in jaundice-free children with biliary atresia

BACKGROUND

T helper (Th) cell cytokines modulate inflammation and play a role in biliary atresia (BA). The aim of the study is a cross-sectional assessment of the levels of Th cytokines in the jaundice-free post Kasai procedure patients.

METHODS

There were 40 jaundice-free patients with BA and 28 normal controls enrolled. Patients were divided into 3 groups, including normal liver function, impaired liver function, and portal hypertension. Plasma concentration of Th1 [interferon-γ (INF-γ), interleukin (IL)-2], Th2 (IL-4, IL-10), Th3 [transforming growth factor-β1 (TGF-β1)], Th17 (IL-17) cytokines, and stromal cell-derived factor-1α (SDF-1α) were investigated.

RESULTS

The IFN-γ level was significantly higher in the BA patients with impaired liver function and portal hypertension than controls (P<0.0001 and P<0.0001, respectively). There was a significantly increase of TGF-ß1 in all BA groups compared with controls (P=0.003). The reduction of SDF-1α expression was found in BA groups (P<0.0001). IL-10 levels significantly correlated with aspartate aminotransferase to platelet ratio index (r=0.496, P=0.001). For the cytokine correlations, there were no correlations of Th1, Th2 and Th17 cytokine with the other measured cytokines, but TGF-ß1 was negatively correlated with SDF-1α levels (r=-0.327, P=0.039).

CONCLUSIONS

IFN-γ and IL-10 are likely to be involved in the disease progression in BA. Besides, TGF-β1 is found to be a suppression marker associated with SDF-1α levels and reduced production of TGF-β1 may be associated with the disease progression.

TGFβ(1) and sCTLA-4 levels are increased in eltrombopag-exposed patients with ITP

Some thrombopoietin receptor-agonists (TPR-As) have been developed and shown to be highly effective in the treatment of immune thrombocytopenic purpura (ITP). Soluble cytotoxic T-lymphocyte-associated antigen 4 (sCTLA-4) can modulate and terminate the immune response. Several reports have shown that sCTLA-4 levels are elevated in patients with some autoimmune disorders. However, sCTLA-4 levels have not previously been investigated in TPR-A exposed patients with ITP. We investigated the levels of transforming growth factor (TGF) β(1) and sCTLA-4 in ITP patients to determine the clinical association with TGFβ(1) and sCTLA-4 in TPR-A-exposed patients with ITP. Thirty-seven ITP patients were divided into 2 groups (TPR-A-exposed: 13 patients; unexposed: 24 patients). Doses of eltrombopag ranging from 12.5mg to 50mg were administered daily, and biochemical data obtained before and after eltrombopag administration were compared. Eltrombopag therapy significantly increased sCTLA-4 and TGFβ(1) levels relative to baseline in patients with ITP. In addition, plasma TGFβ(1) was positively correlated with platelet counts and sCTLA-4 in patients with ITP in the eltrombopag-exposed group. However, no significant change in the detection rate for anti-glycoprotein antibody was observed before and 24 weeks after eltrombopag treatment. These results suggest that eltrombopag can partially modulate some immune responses by TGFβ(1) and sCTLA-4, but it does not induce immune tolerance by 24 weeks after treatment.

Reduced expression of transforming growth factor-β1 and correlated elevation of interleukin-17 and interferon-γ in pediatric patients with chronic primary immune thrombocytopenia (ITP)

BACKGROUND

Dysregulated T helper (Th) cells are considered important in the pathophysiology of chronic primary immune thrombocytopenia (ITP). The present study investigated whether levels of Th cytokines in pediatric patients with chronic ITP were different compared with healthy controls.

PROCEDURES

Fifty-seven pediatric patients with chronic ITP and 28 healthy controls were enrolled. Patients were divided into three groups based on their platelet counts at the time of the study: (i) active disease <50 × 10(9) /l (n = 23), (ii) stable disease 50-150 × 10(9) /l (n = 23), and (iii) in remission >150 × 10(9) /l (n = 11). Plasma concentration of Th1 [interferon gamma (INF-γ), interleukin 2 (IL-2)], Th2 (IL-4, IL-10), Th3 [transforming growth factor-β1 (TGF-β1)], and Th17 (IL-17) cytokines were investigated by enzyme-linked immunosorbent assay.

RESULTS

IFN-γ was increased in patients with active (P < 0.001) and stable disease (P = 0.026) when compared with controls. The IL-17 level was significantly higher in all of the 3 patient groups. In addition, there was a positive correlation between IL-17 and IFN-γ levels in chronic ITP patients (r = 0.640, P < 0.001). Reduced TGF-β1 expression was observed in patients with active (P < 0.001) and stable disease (P = 0.001) in comparison with controls. Moreover, TGF-β1 level in patients was positively correlated with the platelet count (r = 0.355, P = 0.007).

CONCLUSIONS

Elevation of IL-17 and IFN-γ may be an important dysregulation of cellular immunity in pediatric patients with chronic ITP. The disease activity is associated with reduced production of TGF-β1.

Imunopatologia da dermatite de contato alérgica

A dermatite de contato alérgica é consequência de uma reação imune mediada por células T contra químicos de baixo peso molecular, denominados haptenos. É uma condição frequente que ocorre em todas as raças e faixas etárias e afeta a qualidade de vida de seus portadores. O mecanismo imunológico desta doença vem sendo revisto nas últimas décadas com significativo avanço no seu entendimento. A metabolização e o caminho dos haptenos, bem como a formação e o mecanismo de ação das células responsáveis tanto pela reação quanto pelo seu término, são discutidos neste artigo

RFXB and its splice variant RFXBSV mediate the antagonism between IFNgamma and TGFbeta on COL1A2 transcription in vascular smooth muscle cells

Cytokines secreted by infiltrating immune cells during atherogenesis modulate vascular remodeling. One exemplary event is the antagonism between transformed growth factor (TGF-β) and interferon gamma (IFN-γ) on the transcriptional control of type I collagen gene (COL1A2). Previously we have reported that IFN-γ up-regulates regulatory factor for X-box B (RFXB) to repress collagen transcription while down-regulates the expression of RFXBSV, a splice variant of RFXB that blocks collagen repression in fibroblasts. Here we demonstrate that TGF-β abrogated COL1A2 repression by IFN-γ through altering the relative expression of RFXB and RFXBSV. Unlike RFXB, RFXBSV did not bind to the collagen promoter and competed with RFXB for the co-repressor histone deacetylase 2 (HDAC2), limiting HDAC2 recruitment to the collagen transcription start site as evidenced by chromatin immunoprecipitation assays. Over-expression of RFXB by lentiviral infection in HASMCs enhanced HDAC2 enlistment, promoted histone deacetylation surrounding the collagen site by IFN-γ, and blocked the TGF-β antagonism, a pattern reversed by RFXBSV infection. On the contrary, silencing of RFXB, but not both RFXB and RFXBSV, expression promoted the TGF-β antagonism. Thus, we have identified a novel mechanism whereby TGF-β antagonizes the IFN-γ repression of collagen transcription in HASMCs and as such provided new insights into antiatherogenic strategies.

The impact of immune gene polymorphisms in kidney and liver transplantation

Since the completion of the Human Genome Project, it has become clear that genetic variation exists among individuals that can affect functional gene expression. This finding raises the possibility that differences in genetic phenotypes may account for the interindividual responses seen in the context of the alloimmune response. This review highlights studies examining the relative role of immunologic gene polymorphism in the context of renal and liver transplant outcomes (eg, acute rejection and graft survival). Furthermore, it examines the limitations and pitfalls in the study designs and concludes with the potential of single nucleotide polymorphism analysis in the future care of transplant recipients.

Immunology of mercury

The heavy metal mercury is ubiquitously distributed in the environment resulting in permanent low-level exposure in human populations. Mercury can be encountered in three main chemical forms (elemental, inorganic, and organic) which can affect the immune system in different ways. In this review, we describe the effects of these various forms of mercury exposure on immune cells in humans and animals. In genetically susceptible mice or rats, subtoxic doses of mercury induce the production of highly specific autoantibodies as well as a generalized activation of the immune system. We review studies performed in this model and discuss their implications for the role of environmental chemicals in human autoimmunity.

Brothers and sisters: molecular insights into arterial-venous heterogeneity

The molecular differences between arteries and veins are genetically predetermined and are evident even before the first embryonic heart beat. Although ephrinB2 and EphB4 are expressed in cells that will ultimately differentiate into arteries and veins, respectively, many other genes have been shown to play a significant role in cell fate determination. The expression patterns of ephrinB2 and EphB4 are restricted to arterial-venous boundaries, and Eph/ephrin signaling provides repulsive cues at arterial-venous boundaries that are thought to prevent intermixing of arterial- and venous-fated cells. However, the maintenance of arterial-venous fate is susceptible to some degree of plasticity. Thus, in response to signals from the ambient microenvironment and shear stress, there is flow-mediated intercalation of the arteries and veins that ultimately leads to the formation of a functional, closed-loop circulation. In addition, cells in the blood vessels of each organ undergo epigenetic, morphological, and functional adaptive changes that are specific to the proximate function of their cognate organ(s). These adaptive changes result in an interorgan and intraorgan vessel heterogeneity that manifest clinically in a disparate response of different organs to identical risk factors and injury in the same animal. In this review, we focus on the molecular and physiological factors influencing arterial-venous heterogeneity between and within different organ(s). We explore arterial-venous differences in selected organs, as well as their respective endothelial cell architectural organization that results in their inter- and intraorgan heterogeneity.

Genetic variants in T helper cell type 1, 2 and 3 pathways and gastric cancer risk in a Polish population

Host immune responses are known determinants of gastric cancer susceptibility. We previously reported an increased gastric cancer risk associated with common variants of several T helper type 1 (Th1) cytokine genes in a population-based case-control study in Warsaw, Poland. In the present study, we augmented our investigation to include additional Th1 genes as well as key genes in the Th2 and Th3 pathways. Analysis of 378 cases and 435 age- and sex-matched controls revealed associations for polymorphisms in the Th1 IL7R gene and one polymorphism in the Th2 IL5 gene. The odd ratios (ORs) for IL7R rs1494555 were 1.4 [95% confidence interval (CI), 1.0-1.9] for A/G and 1.5 (95% CI, 1.0-2.4) for G/G carriers relative to A/A carriers (P = 0.04). The ORs for IL5 rs2069812 were 0.9 (95% CI, 0.7-1.3) for C/T and 0.6 (95% CI, 0.3-1.0) T/T carriers compared with C/C carriers (P = 0.03). These results suggest that IL5 rs2069812 and IL7R rs1389832, rs1494556 and rs1494555 polymorphisms may contribute to gastric cancer etiology.

Regulatory immune cells in kidney disease

Lymphocytes and macrophages act as effector immune cells in the initiation and progression of renal injury. Recent data have shown that subpopulations of these immune cells (regulatory T lymphocytes and alternately-activated or regulatory macrophages) are potent modulators of tissue injury and repair in renal disease. Recent animal studies examining the therapeutic effect of these cells raise the exciting possibility that strategies targeting these cell types may be effective in treating and preventing kidney disease in humans. This review will describe their biological role in experimental kidney disease and therapeutic potential in clinical nephrology.

Reduced incidence of insect-bite hypersensitivity in Icelandic horses is associated with a down-regulation of interleukin-4 by interleukin-10 and transforming growth factor-beta1

Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by IgE-mediated reactions to bites of insects of the genus Culicoides. IBH does not occur in Iceland due to the absence of Culicoides. However, Icelandic horses exported to mainland Europe as adults (1st generation) have a > or =50% incidence of developing IBH. In contrast, their progeny (2nd generation) has a <10% incidence of IBH. Here we show that peripheral blood mononuclear cells (PBMC) from Icelandic horses born in mainland Europe and belonging either to the IBH or healthy subgroup produce less interleukin (IL)-4 after polyclonal or allergen-specific stimulation when compared with counterparts from horses born in Iceland. We examined a role of IL-10 and transforming growth factor (TGF)-beta1 in down-regulation of IL-4 in healthy 2nd generation Icelandic horses. Supernatants of PBMC from 2nd generation healthy horses down-regulated the proportion of IL-4-producing cells and IL-4 production in stimulated cultures of PBMC from 1st generation IBH. This inhibition was mimicked by a combination of IL-10 and TGF-beta1 but not by the single cytokines. Cultures of stimulated PBMC of healthy 2nd generation horses produced a low level of IL-4, but IL-4 production was increased by anti-equine IL-10 and anti-human TGF-beta1. This shows for the first time that in horses, IL-10 and TGF-beta1 combined regulate IL-4 production in vitro. It is suggested that in this naturally occurring IgE-mediated allergy, IL-10 and TGF-beta1 have a role in the down-regulation of IL-4-induced allergen-specific Th2 cells, thereby reducing the incidence of IBH.

Adaptive TGF-beta-dependent regulatory T cells control autoimmune diabetes and are a privileged target of anti-CD3 antibody treatment

Previous results have shown that CD4(+)CD25(+) regulatory T cells (Tregs) control autoimmunity in a spontaneous model of type 1 diabetes, the nonobese diabetic (NOD) mouse. Moreover, anti-CD3 reverses diabetes in this setting by promoting Tregs that function in a TGF-beta-dependent manner. This finding contrasts with a large body of work suggesting that CD4(+)CD25(high) Tregs act in a cytokine-independent manner, thus suggesting that another type of Treg is operational in this setting. We sought to determine the basis of suppression both in untreated NOD mice and in those treated with anti-CD3. Our present results show that a subset of foxP3(+) cells present within a CD4(+)CD25(low) lymphocyte subset suppresses T cell immunity in spontaneously diabetic NOD mice in a TGF-beta-dependent manner, a functional property typical of "adaptive" regulatory T cells. This distinct Treg subset is evident in NOD, but not normal, mice, suggesting that the NOD mice may generate these adaptive Tregs in an attempt to regulate ongoing autoimmunity. Importantly, in two distinct in vivo models, these TGF-beta-dependent adaptive CD4(+)CD25(low) T cells can be induced from peripheral CD4(+)CD25(-) T lymphocytes by anti-CD3 immunotherapy which correlates with the restoration of self-tolerance.

Transforming growth factor-beta and T-cell-mediated immunoregulation in the control of autoimmune diabetes

It is now well-established that CD4+ regulatory T cells are instrumental in controlling immune responses both to self-antigens and to non-self-antigens. However, the precise modalities involved in their differentiation and survival, their mode of action and their antigen specificity are only partially understood. We have been particularly interested in the study of regulatory T cells controlling autoimmune insulin-dependent diabetes. Here, we provide evidence to support the phenotypic and functional diversity of regulatory T cells mediating transferable 'active' or 'dominant' peripheral tolerance in the non-obese diabetic mouse model (NOD). They include natural and adaptive regulatory T cells that are operational both in unmanipulated NOD mice and in animals undergoing treatments aimed at inducing/restoring tolerance to self-beta-cell antigens. At least in our hands, the differential cytokine-dependency appears as a major distinctive feature of regulatory T cells subsets. Among immunoregulatory cytokines, transforming growth factor-beta(TGF-beta) appeared to play a key role. Herein we discuss these results and the working hypothesis they evoke in the context of the present literature, where the role of TGF-beta-dependent T-cell-mediated immunoregulation is still debated.

The regulation of allergy and asthma

Allergic diseases and asthma are caused by exaggerated T-helper 2 (Th2)-biased immune responses in genetically susceptible individuals. Tolerance to allergens is a mechanism that normally prevents such responses, but the specific immunological events that mediate tolerance in this setting are poorly understood. A number of recent studies indicate that regulatory T cells (Tregs) play an important role in controlling such Th2-biased responses. Tregs involved in regulating allergy and asthma consist of a family of related types of T cells, including natural CD25+ Tregs as well as inducible forms of antigen-specific adaptive Tregs. Impaired expansion of natural and/or adaptive Tregs is hypothesized to lead to the development of allergy and asthma, and treatment to induce allergen-specific Tregs could provide curative therapies for these problems.

Foxp3-transduced polyclonal regulatory T cells protect against chronic renal injury from adriamycin

Chronic proteinuric renal injury is a major cause of ESRD. Adriamycin nephropathy is a murine model of chronic proteinuric renal disease whereby chemical injury is followed by immune and structural changes that mimic human disease. Foxp3 is a gene that induces a regulatory T cell (Treg) phenotype. It was hypothesized that Foxp3-transduced Treg could protect against renal injury in Adriamycin nephropathy. CD4+ T cells were transduced with either a Foxp3-containing retrovirus or a control retrovirus. Foxp3-transduced T cells had a regulatory phenotype by functional and phenotypic assays. Adoptive transfer of Foxp3-transduced T cells protected against renal injury. Urinary protein excretion and serum creatinine were reduced (P<0.05), and there was significantly less glomerulosclerosis, tubular damage, and interstitial infiltrates (P<0.01). It is concluded that Foxp3-transduced Treg cells may have a therapeutic role in protecting against immune injury and disease progression in chronic proteinuric renal disease.

LF 15-0195 Treatment Protects against Central Nervous System Autoimmunity by Favoring the Development of Foxp3-Expressing Regulatory CD4 T Cells

Experimental autoimmune encephalomyelitis (EAE) is an instructive model for the human demyelinating disease multiple sclerosis. Lewis (LEW) rats immunized with myelin-basic protein (MBP) develop EAE characterized by a single episode of paralysis, from which they recover spontaneously and become refractory to a second induction of disease. LF 15-0195 is a novel molecule that has potent immunosuppressive effects in several immune-mediated pathological manifestations, including EAE. In the present study, we show that a 30-day course of LF 15-0195 treatment not only prevents MBP-immunized LEW rats from developing EAE but also preserves their refractory phase to reinduction of disease. This effect is Ag driven since it requires priming by the autoantigen during the drug administration. In contrast to other immunosuppressive drugs, short-term treatment with this drug induces a persistent tolerance with no rebound of EAE up to 4 mo after treatment withdrawal. This beneficial effect of LF 15-0195 on EAE does not result from the deletion of MBP-specific Vbeta8.2 encephalitogenic T cells. In contrast, this drug favors the differentiation of MBP-specific CD4 T cells into Foxp3-expressing regulatory T cells that, upon adoptive transfer in syngeneic recipients, prevent the development of actively induced EAE. Finally, we demonstrate that the tolerance induced by LF 15-0195 treatment is not dependent on the presence of TGF-beta. Together, these data demonstrate that short-term treatment with LF 15-0195 prevents MBP-immunized LEW rats from EAE by favoring the development of Foxp-3-expressing regulatory CD4 T cells.

Regulatory T cells in the control of autoimmune diabetes: the case of the NOD mouse

Over the last few years, there has been a revival of the concept of suppressor/regulatory T cells being central players in the control of various immune responses, including autoimmune responses and immune response to transplants, tumors, and infectious agents. It appears that regulatory T cells are diverse in their phenotypes, antigen specificity, and modes of action. Here we summarize studies from various groups, including our own, demonstrating that specialized subsets of regulatory T cells are pivotal in the control of autoimmune diabetes as well shown by the compelling evidence accumulated using the non-obese diabetic (NOD) mouse model. We also provide a discussion of the evidence showing that some biological products (such as CD3-specific monoclonal antibodies) are representatives of a new category of immunotherapeutic agents endowed with unique capacities to promote immunological tolerance (an antigen-specific unresponsiveness in the absence of long-term generalized immunosuppression) through their ability to induce immunoregulatory T cells.

IFNbeta-1a treatment and reestablishment of Th1 regulation in MS patients: dose effects

The authors evaluated the relationships between clinical and pharmacologic parameters and the Th1/Th2/Th3 cytokine network in patients with relapsing-remitting multiple sclerosis treated with differing doses of interferon-beta1a (IFN-beta1a). Their results show that low doses are ineffective but that high doses restore Th1 regulation of the maturation and activation of monocytes, T cells, immature dendritic cells, dendritic cells, and T regulatory cells for central and peripheral self-tolerance. Interaction between interleukin (IL)-10, IL-12 p70, and IL-6 production appears to play an important role in the control of the maturation and activation states of dendritic cells and T regulatory cells, and is at the basis of the benefit of high doses. The results also indicate that the physiologic mechanisms involved in aging help immunologic reestablishment in IFNbeta-1a-treated patients. Finally, it would appear that the failure of IFNbeta-1a therapy to resolve multiple sclerosis completely is due to the suppression of IL-12 p70 mechanisms (responsible for the physiologic deletion of self-reactive cells) in activation conditions, probably by IFNbeta-1a itself.

The Relative Importance of Cytokine Gene Polymorphisms in the Development of Early and Late Acute Rejection and Six-Month Renal Allograft Pathology

BACKGROUND

Acute rejection episodes and 6-month protocol biopsy acute pathology are highly correlated with long-term outcomes in renal transplant recipients. Recurrent, vascular, and late rejections are particularly deleterious.

METHODS

We determined the relative contribution of human leukocyte antigen matching, cytokine genotypes, delayed graft function (DGF), and baseline immunosuppression to the development of acute rejection and allograft pathology in 118 renal transplant recipients.

RESULTS

Multivariate logistic regression modeling demonstrated that the adjusted odds ratio and 95% confidence interval for recurrent (> or =2) early rejections (0-3 months) increased linearly for high (H) > intermediate (I) > low (L) interferon-gamma (1.8; 1.1-3.2) and tumor necrosis factor (TNF)alpha (3.0; 1.3-6.9) genotype, whereas every 1 microg/L increase in the cyclosporine A level was protective (0.991; 0.984-0.999). The odds ratio for recurrent late rejections (4-6 months) increased for H > I > L TNFalpha (5.1; 1.8-14.7) genotype and DGF (7.1; 1.6-30.2), whereas H > I/L transforming growth factor-beta1 genotype decreased the relative risk (0.09: 0.02-0.49). Vascular rejection was only predicted by H > I > L TNFalpha phenotype (3.0; 1.2-7.9). The odds ratio for the 6-month Banff Acute Score (6A > or= 4) increased for H > I > L TNFalpha (2.7; 1.1-6.7) and interleukin-10 (3.4; 1.2-6.2) genotype, and DGF (3.4; 1.1-11.5). Treatment of early subclinical rejection decreased the relative risk (0.20; 0.07-0.62).

CONCLUSIONS

High transforming growth factor-beta1 producer phenotype seems to be protective against acute inflammation, whereas H and I interferon-gamma, TNFalpha, and interleukin-10 producer genotypes correlate with adverse outcomes. Cytokine genotyping identifies individuals who may benefit from more intensive surveillance and treatment posttransplant.

Immunological study of IFNbeta-1a-treated and untreated multiple sclerosis patients: clarifying IFNbeta mechanisms and establishing specific dendritic cell immunotherapy

OBJECTIVES

A comparative immunological evaluation of multiple sclerosis (MS) patients receiving IFNbeta treatment and patients who are not receiving treatment may help clarify IFNbeta neurological mechanisms and lead the way to an effective dendritic cell (DC) immunotherapy. This type of study helps clarify the pathological function of T cells and DCs within the TH1/TH2/TH3 network as well as the specific interactions between TH1/TH2/TH3 cytokines implicated in MS pathological mechanisms and determine the best way of reestablishing the TH1/TH2/TH3 network equilibrium.

METHODS

We studied network interactions between TH1/TH2/TH3 cytokine levels in serum and supernatants of whole blood and CD14+ monocyte-derived DCs in the remission phase of the disease and in correlation to the Expanded Disability Status Scale (EDSS).

RESULTS

We found that TH1 dysregulation results in a disruption of the maturation and activation of dendritic and T cells, and a lack of T-regulating cells for the induction of self-tolerance; IFNbeta mechanisms restore regulation by reestablishing the network balance but fail to resolve the disease completely due to in vivo IL12p70 network interactions leading to the deletion of self-aggressive cells.

CONCLUSIONS

Our results indicate that a specific DC immunotherapy could cure rather than treat MS. The best point to reestablish the normal physiological cycle is at the immature DC stage which can be done in vitro with treated peripheral blood CD14+ cells and used in vivo to stimulate the expansion of specific regulatory T cells.

CD30 antigen and multiple sclerosis: CD30, an important costimulatory molecule and marker of a regulatory subpopulation of dendritic cells, is involved in the maintenance of the physiological balance between TH1/TH2 immune responses and tolerance. The role of IFNbeta-1a in the treatment of multiple sclerosis

OBJECTIVES

The immunological effect of CD30 on dendritic cells (DCs) was examined in a comparative study of patients with relapsing-remitting multiple sclerosis (RRMS). The patients were divided into two groups on the basis of interferon (IFN)beta-1a treatment: IFNbeta-1a-treated patients and untreated patients. We have already shown that CD30 is a marker of cells involved in the regulation of the balance between TH1 and TH2 immune responses and so the aim of this study was to confirm this role in DCs and, consequently, to clarify the immunopathological mechanisms of MS and the causes of immunosuppressive drug failure.

METHODS

We studied network interactions between soluble (s) CD30 and TH1/TH2 cytokines in the supernatants of CD14+-derived immature DC (IDC) and DC cultures from treated and untreated patients. Network interactions between the sCD30 and cytokines in IDC and DC supernatants were also evaluated in relation to TH1/TH2 cytokine serum levels.

RESULTS

Our overall results show that CD30 is expressed on IDCs and DCs, indicating an immunological role in resting and activated physiological conditions. This role would appear to be the regulation of the resting and activated physiological balance between the TH1/TH2 immune functions as abnormal increases in sCD30 levels result in impaired regulation. Further studies are undoubtedly required to clarify this situation. IFNbeta-1a treatment was found to determine a fall in sCD30 levels, leading to the restoration of the normal functional selection of IDCs from progenitor cells and the regulation of the TH1/TH2 network balance. However, IFNbeta-1a treatment may also be responsible for the in vivo suppression of CD30-mediated TH1-DC functions in immune activation. TH1-DC functions are involved in the induction of T-regulatory cells for the physiological deletion of self-aggressive cells.

CONCLUSION

We conclude that CD30 is an important costimulatory molecule and marker of a regulatory subpopulation of DCs which induces and modulates immune cells involved in the maintenance of the physiological balance between TH1/TH2 immune responses and tolerance. Elucidating the mechanisms restoring DC and T-regulatory cell function could lead to more effective therapy and strategies for the prevention and treatment of immunopathological conditions such as autoimmunity, transplant rejection, allergy and tumors.

Tolerance induced by low dose D-penicillamine in the brown Norway rat model of drug-induced autoimmunity is immune-mediated

Most patients taking drugs associated with idiosyncratic drug reactions tolerate the drug and do not develop adverse reactions. Understanding the mechanism of tolerance to drugs is important as it could provide insight into why some patients develop idiosyncratic reactions and others do not. The Brown Norway rat model of D-penicillamine-induced autoimmunity was used as a model of idiosyncratic drug-induced autoimmunity. Two weeks of low dose (5 mg/day) D-penicillamine pretreatment completely prevented all clinical signs of autoimmunity normally seen in 60-80% of rats treated with high dose (20 mg/day) D-penicillamine. Low dose pretreatment also prevented the increase in IgE and IL-4 mRNA characteristic of the response to high dose D-penicillamine. Experiments were conducted to determine whether low dose tolerance is metabolic or immunological. It was found that low dose tolerance possesses key characteristics of immune-mediated tolerance: memory, splenocytes that adoptively transfer tolerance, and regulatory cytokine production. To provide an understanding of the factors that can prevent or reverse established tolerance, the conditions for inducing and maintaining tolerance were investigated. Tolerance induction was investigated by manipulating the immune system during the period of low dose exposure. The induction of tolerance was partially prevented by depleting the macrophage subset of antigen presenting cells with clodronate-filled liposomes or by inhibiting T cells with tacrolimus during the period of low dose exposure. As well, the induction of tolerance was completely prevented by repeatedly stimulating the immune system throughout the period of low dose pretreatment with poly I:C. To investigate the permanence of tolerance, the immune system was stimulated after tolerance induction in an attempt to break tolerance. Both LPS and poly I:C reversed tolerance in a dose-dependent manner. These results demonstrate that immune tolerance to D-penicillamine autoimmunity can be induced by short-term low dose pretreatment.

TGF-beta-dependent mechanisms mediate restoration of self-tolerance induced by antibodies to CD3 in overt autoimmune diabetes

CD3-specific antibodies have the unique capacity to restore self-tolerance in established autoimmunity. They induce long-term remission of overt diabetes in nonobese diabetic (NOD) mice and in human type I diabetes. The underlying mechanisms had been unclear until now. Here we report that treatment with CD3epsilon-specific antibodies induces transferable T-cell-mediated tolerance involving CD4+CD25+ cells. However, these CD4+CD25+ T cells are distinct from naturally occurring regulatory T cells that control physiological autoreactivity. CD3-specific antibody treatment induced remission in NOD Cd28-/- mice that were devoid of such regulatory cells. Remission of diabetes was abrogated by coadministration of a neutralizing transforming growth factor (TGF)-beta-specific antibody. The central role of TGF-beta was further suggested by its increased, long-lasting production by CD4+ T cells from tolerant mice. These data explain the intriguing tolerogenic effect of CD3-specific antibodies and position them as the first clinically applicable pharmacological stimulant of TGF-beta-producing regulatory CD4+ T cells.

Postpartum thyroiditis is associated with fluctuations in transforming growth factor-beta1 serum levels

Postpartum thyroiditis (PPT) is characterized by a rapid evolution and recovery of euthyroidism. Therefore, it can represent a good model to study early cytokine fluctuations in autoimmune thyroid diseases. TGFbeta1 is an immunosuppressive cytokine, as it inhibits T and B cell proliferation, natural killer cell cytotoxic activity, and the generation of T cell cytotoxicity. The aim of this study was to assess serum concentrations of TGFbeta1 during pregnancy and to study possible serum fluctuations of this cytokine during the different phases of PPT. Thyroid biochemical pattern, antithyroid autoantibodies (ATA), and total and active TGFbeta1 (aTGFbeta1) serum concentrations were evaluated in 63 pregnant women. Thirty-four of them were ATA(+), and 29 were ATA(-). Twenty of the 34 ATA(+) women were followed in the postpartum year. Nine of these 20 women developed PPT; 11 remained euthyroid. All of the PPT women became euthyroid during the follow-up. Our results showed 1) detectable serum levels of aTGFbeta1 in 50% of ATA(+) pregnant women, suggesting that the presence of autoantibodies may characterize a favorable condition for TGFbeta1 activation; and 2) decreased total TGFbeta1 and increased aTGFbeta1 serum levels during the active phase of PPT in ATA(+) women. This seems to suggest that inflammation may be responsible for TGFbeta1 activation and autoantibody increase because of antigen release. Although further studies of women with persistent hypothyroidism after the postpartum year are needed, the possibility that the enhanced activation of TGFbeta1 may contribute to resolution of thyroid inflammation postpartum cannot be excluded.

Regulatory T cells under scrutiny

Having been long debated, the notion of suppressor T cells--renamed regulatory T cells--is back on the map, but many questions remain regarding the nature of these regulatory cells. Are they specialized cells? What are their phenotype, antigen specificity, mode of action and, above all, biological (and immunopathological) relevance? The predominant role of naturally occurring CD4+CD25+ T cells has been emphasized recently. Other cell types, however, contribute to immunoregulation also, whether they arise spontaneously during ontogeny or during the course of an adaptive immune response.

T cell regulation as a side effect of homeostasis and competition

We have previously hypothesized that maintaining a balanced peripheral immune system may not be the sole responsibility of a specialized subset of T cells dedicated to immune regulation, but also a side effect of normal competition for shared resources within an intact immune system. Here we show that regulatory activity is correlated with high homeostatic expansion potential, reflecting the avidity for self-peptide:MHC complexes. Monoclonal transgenic T cells with high homeostatic expansion potential and lacking characteristics previously associated with regulatory function were able to regulate wasting disease induced by transfer of a small number of naive CD45RB(hi) CD4 T cells into lymphopenic hosts. Self-regulatory function is also found in the naive polyclonal T cell repertoire depleted of CD25(+) T cells. T cells capable of preventing immune pathology, like the transgenic T cells, express higher than average levels of CD5, an indicator of avidity for self:MHC peptide complexes. We therefore propose that dysregulated expansion of potentially pathogenic T cells in a lymphopenic environment can be prevented by members of the naive T cell repertoire, irrespective of their specificity, as a side effect of their response to homeostatic and antigenic stimulation.

Development of CD4+ T cell lines that suppress an antigen-specific immune response in vivo

It has been suggested for many years that the regulation of the immune system for the maintenance of peripheral tolerance may involve regulatory/suppressor T cells. In the past few years, several investigators have demonstrated that these cells can be generated in vitro. It has also been shown that they can inhibit the progression of various autoimmune disease models when infused into susceptible mice. We have generated two murine T cell lines in the presence of KLH-specific T cell clones from BALB/c or DBA2 mice. The lines are characterized by a low proliferative response to mitogens, the capacity to secrete high amounts of IL-10 and TGF-beta, and small amounts of IFN-gamma. Interestingly, these cells are unable to produce IL-2, IL-4 or IL-5. The study of the surface phenotype of both lines revealed CD4+, CD25high, CD44low and CTLA-4- cells. When injected intravenously in (CBy.D2) F1 mice, these cells were able to inhibit 50-100% of the TNP-specific antibody production, when the hapten was coupled to KLH. In the present study we offer another evidence for the existence of regulatory T cells in the T lymphocyte repertoire, suggesting that they can also regulate immune responses to foreign antigens. Furthermore, we demonstrate an alternative pathway to generate these cells different from approaches used thus far.

The pathogenesis of oral lichen planus

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

Revisiting the "hygiene hypothesis" in gastrointestinal allergy

The "hygiene hypothesis" in its original form hypothesized that infection in early childhood acquired through unhygienic contact with siblings or the mother may prevent the development of allergic disease. Several recent epidemiologic surveys showing an inverse relationship between the frequency of infectious disease and the incidence of allergic diseases lend support to this hypothesis. Allergen sensitization of the immune system can occur early in utero against a background of neonatal commitment to a Th2 immune response involving the production of Th2 cytokines (eg, interleukin (IL)-4, IL-5, IL-13) that are the principal mediators of allergic inflammation. Continued allergen exposure is associated with predominantly CD4+ Th2 cell proliferation but does not exclude a minor Th1 allergen-specific subpopulation that can be further expanded nonspecifically and polyclonally by microbial superantigens or as bystanders, by interferon-gamma (IFN-gamma) and IL-2 released from Th1 effectors responding to antigens associated with infectious pathogens. Th1 cytokines can also subvert allergen-specific Th2 lymphocytes to become allergen-specific Th1 cells-a process reminiscent of the increased tendency of the maturing immune system of growing adults to mount a Th1 response to some environmental and dietary antigens. Unlike Th2 cytokines, IFN-gamma and IL-2 inhibit B-cell production of IgE and, hence, delimit the capacity of mast cells to degranulate and release allergenic mediators. The ability of infectious agents through their danger signals to initiate a Th1 response that deviates the Th2 allergenic bias is the basis of the hygiene hypothesis.

Modulation of a heterologous immune response by the products of Ascaris suum

Helminth infections are among the most potent stimulators of Th2-type immune responses and have been widely demonstrated to modify responsiveness to both nonparasite antigens and other infectious agents in a nonspecific manner in infected animals. We investigated the immunomodulatory properties of pseudocoelomic body fluid from adult Ascaris suum gastrointestinal helminths (ABF) and its defined allergen (ABA-1) by examining their effects on the immune response to a heterologous antigen, ovalbumin. Our results indicate that ABF has potent immunomodulatory activity and that the effects observed are consistent with skewing towards a Th2-type response rather than induction of anergy. Our findings show that the immunomodulatory activities of ABF are associated with components other than the major constituent and putative allergen, ABA-1. Furthermore, the allergic responses to ABA-1 are not a result of an intrinsic allergenicity of the protein but are more a reflection of the wider induction of a Th2 response by the infection. Importantly, the induction of interleukin-10 by ABF also suggests that T regulatory cells may play a role in immunomodulation of immune responses by parasitic helminths.

Antigen-specific T regulatory-1 cells are associated with immunosuppression in a chronic helminth infection (onchocerciasis)

Different mechanisms underlie the phenomenon of peripheral tolerance. Recently, a new subset of CD4+ T cells, called T regulatory-1 (Tr1) cells, was described which show suppressor functions in vitro and in vivo and are characterized by a predominant production of IL-10 and/or TGF-beta. Tr1 cells have so far been generated experimentally in an IL-10-rich environment and hold promise for exploitation in the suppression of alloreactions and inflammatory or allergic dispositions. However, these cells have not been characterized in infectious diseases. Here we show that in the chronic helminth infection onchocerciasis (river blindness), where patients have relatively little sign of dermatitis despite the presence of millions of small worms in the skin, T cells can be obtained which bear characteristics of Tr1 cells, producing no IL-2 or IL-4 but substantial amounts of IL-10, variable amounts of IL-5, and some IFN-gamma. These cells display elevated amounts of CTLA-4 after stimulation and are able to inhibit other T cells in coculture, in contrast to Th1 and Th2 clones. This is the first time that this type of suppressor T cell has been cloned as naturally occurring during an infectious disease.

Expression of the integrin alpha Ebeta 7 identifies unique subsets of CD25+ as well as CD25- regulatory T cells

Regulatory CD25(+)CD4(+) T cells are considered as important players in T cell homeostasis and self-tolerance. Here we report that the integrin alpha(E)beta(7), which recognizes epithelial cadherin, identifies the most potent subpopulation of regulatory CD25(+) T cells. Strikingly, CD25-negative alpha(E)+CD4(+) T cells displayed regulatory activity. Both alpha(E)+ subsets, CD25(+) and CD25(-), express CTLA-4, suppress T cell proliferation in vitro, and protect mice from colitis in the severe combined immunodeficient model (SCID) in vivo. Whereas alpha(E)+CD25(+) T cells produce almost no cytokines, alpha(E)+CD25(-) T cells represent a unique subset in which high IL-2, IFN-gamma and T helper 2-cytokine production is linked with suppressive function. Thus, the integrin alpha(E)beta(7) can be regarded as a novel marker for subsets of highly potent, functionally distinct regulatory T cells specialized for crosstalk with epithelial environments.

Tr1 cell-dependent active tolerance blunts the pathogenic effects of determinant spreading

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated autoimmune disease of the CNS. The current study shows that even in an acute episode of disease the autoimmune response spreads from one determinant on myelin basic protein (MBP) to the other linked determinant and that this spread plays a functional role in the pathogenesis of disease. The soluble form of each determinant could be used to induce Ag-specific T cell tolerance and reverse an ongoing disease. We show that the rapid effect of soluble peptide therapy is due to repolarization of autoimmune T cells undergoing activation. We suggest that at least two different types of regulatory T cells participate in the induction of active tolerance. The first, yet to be fully characterized, functions in an IL-4-dependent manner. The second produces high levels of IL-10 and low levels of IL-4 (Tr1). We bring about completing evidence showing that these Tr1 cells play a pivotal role in the regulation of T cell tolerance during determinant spread and that soluble peptide therapy with the determinant to which the autoimmune response spreads amplifies a de novo regulatory mechanism aimed to reduce the pathological consequences of determinant spreading.

Th2-type immunopathological manifestations induced by mercury chloride or gold salts in the rat: signal transduction pathways, cellular mechanisms and genetic control

Heavy metals induce various immunopathological disorders including an increase in serum IgE concentration in predisposed humans. The effects of HgCl2 or gold salts differ depending on the strain of rats tested: they induce Th2-mediated immunopathology in Brown-Norway (BN) rats while HgCl2 triggers an immunosuppression in Lewis (LEW) rats. The disease is due to the emergence of self-MHC class II reactive Th2 cells in BN rats. Autoreactive T cells are also found in HgCl2-injected LEW rats but they produce TGFbeta and IL-10 and have immunoregulatory properties. Hg or Au act on the early steps of T cell activation resulting in IL-4 and IFNgamma gene expression with preferential IL-4 expression in BN rats. Analyzing the effects of HgCl2 on T cells led us to identify a new signaling pathway implicated in IL-4 production. An important feature of this model concerns genetics. Indeed Th2-dependent autoimmunity induced by metals occurs only in BN rats that are genetically committed to develop Th2 responses. Cellular features at play are discussed as well as the identification of loci that control both the Th1/Th2 balance and susceptibility to autoimmunity.

Effect of T-cell peptides derived from Fel d 1 on allergic reactions and cytokine production in patients sensitive to cats: a randomised controlled trial

BACKGROUND

Some patients with asthma who are allergic to cats and are injected intradermally with short, overlapping, T-cell peptides derived from Fel d 1 develop late asthmatic reactions to the peptides, which are associated with a reduction in late-phase skin reactions induced by whole allergens and bronchial hyporesponsiveness to the peptides on the second injection. We aimed to ascertain the effect of multiple injections on the magnitude of the early and late phase skin reactions to intact allergens.

METHODS

After a 9-week run-in period, we randomly assigned patients with asthma and allergies to cats to receive either Fel d 1 peptides (90 microg in increasing divided doses) or placebo. The primary outcome was late-phase cutaneous reactions to whole cat dander. Outcomes were measured at baseline, 4-8 weeks, and 3-9 months. Analysis was by intention to treat.

FINDINGS

16 patients were randomly assigned to the peptides, and eight to placebo. All patients completed the course of injections. Four of the 16 patients on Fel d 1 peptides had initial late asthmatic reactions, but could be desensitised to the higher dose of peptide. Patients in the peptide group but not the placebo group had a significant reduction in the size of their late reaction to whole cat dander between baseline and both follow-ups, but the difference between groups was not significant (first follow-up, difference -422.8 mm(2) [95% CI -1115.0 to 269.4], p=0.43; second follow-up -1180.8 mm(2) [-2216.8 to -144.8], p=0.058). The size of the late reaction to Fel d 1 significantly differed between treatment groups at both follow-ups. At second follow-up, the size of the early reaction to Fel D 1, but not to whole cat dander was significantly reduced in those on peptides compared with those on placebo. The concentration of interferon gamma and of interleukin 4 and 13, and the amount of proliferation, significantly decreased between baseline and second follow-up, and the concentration of interleukin 10 was significantly higher in patients on peptides, however, none of these values differed significantly between groups. Patients on peptides had a significantly greater decrease in the concentration of interferon gamma and interleukin 13, and in the amount of proliferation between baseline and first follow-up than did those on placebo.

INTERPRETATION

Several, short, overlapping Fel d 1 T-cell peptides have potential in treatment of cat allergy.

Induction of autoantibody production is limited in nonautoimmune mice

Many individuals develop a single or a few brief episodes of autoimmunity from which they recover. Mechanisms that quell pathologic autoimmunity following such a breakdown of self-tolerance are not clearly understood. In this study, we show that in nonautoimmune mice, dsDNA-specific autoreactive B cells exist but remain inactive. This state of inactivation in dsDNA-specific B cells could be disrupted by autoreactive Th cells; in this case T cells that react with peptides from the V(H) region of anti-DNA Abs (hereafter called anti-V(H) T cells). Immunization with anti-DNA mAb, its gamma-chain or peptides derived from its V(H) region induced anti-V(H) Th cells, IgG anti-dsDNA Ab, and proteinuria. The breakdown of B cell tolerance in nonautoimmune mice, however, was short-lived: anti-DNA Ab and nephritis subsided despite subsequent immunizations. The recovery from autoimmunity temporally correlated with the appearance of T cells that inhibited anti-DNA Ab production. Such inhibitory T cells secreted TGFbeta; the inhibition of anti-DNA Ab production by these cells was partly abolished by anti-TGFbeta Ab. Even without immunization, nonautoimmune mice possess T cells that can inhibit autoantibody production. Thus, inhibitory T cells in nonautoimmune mice may normally inhibit T-dependent activation of autoreactive B cells and/or reverse such activation following stimulation by Th cells. The induction of such inhibitory T cells may play a role in protecting nonautoimmune mice from developing chronic autoimmunity.

In vitro generation of interleukin 10-producing regulatory CD4(+) T cells is induced by immunosuppressive drugs and inhibited by T helper type 1 (Th1)- and Th2-inducing cytokines

We show that a combination of the immunosuppressive drugs, vitamin D3 and Dexamethasone, induced human and mouse naive CD4(+) T cells to differentiate in vitro into regulatory T cells. In contrast to the previously described in vitro derived CD4(+) T cells, these cells produced only interleukin (IL)-10, but no IL-5 and interferon (IFN)-gamma, and furthermore retained strong proliferative capacity. The development of these IL-10-producing cells was enhanced by neutralization of the T helper type 1 (Th1)- and Th2-inducing cytokines IL-4, IL-12, and IFN-gamma. These immunosuppressive drugs also induced the development of IL-10-producing T cells in the absence of antigen-presenting cells, with IL-10 acting as a positive autocrine factor for these T cells. Furthermore, nuclear factor (NF)-kappaB and activator protein (AP)-1 activities were inhibited in the IL-10-producing cells described here as well as key transcription factors involved in Th1 and Th2 subset differentiation. The regulatory function of these in vitro generated IL-10-producing T cells was demonstrated by their ability to prevent central nervous system inflammation, when targeted to the site of inflammation, and this function was shown to be IL-10 dependent. Generating homogeneous populations of IL-10-producing T cells in vitro will thus facilitate the use of regulatory T cells in immunotherapy.

Reduced transforming growth factor-beta1 production by mononuclear cells from patients with active chronic idiopathic thrombocytopenic purpura

Chronic idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder in which activated T-helper (Th) cells and different Th-cell cytokines might play an important role. We have recently reported that chronic ITP patients in remission had elevated plasma levels of the Th3 cytokine transforming growth factor-beta1 (TGF-beta1), possibly as a part of a bystander immune suppression. In the present study we found that, in ITP patients with active disease [platelet count (plc) < 50 x 10(9)/l], mitogen-stimulated peripheral blood mononuclear cells (PBMC) had a significantly reduced production of TGF-beta1 (444 +/- 178 pg/ml; n = 6) compared with patients with plc 50-150 x 10(9)/l (1293 +/- 374 pg/ml; n = 9; P < 0.05), patients with plc >150 x 10(9)/l (1894 +/- 244 pg/ml; n =12; P <0.005) and healthy controls (1698 +/- 241 pg/ml; n = 10; P < 0.01). Nineteen per cent of ITP patients expressed a platelet-induced PBMC proliferation. Surprisingly, 22% of the ITP patients had a PBMC proliferation below the normal range, i.e. a suppressed proliferation in the presence of platelets; five of these six patients had active disease. In summary, this study demonstrated that chronic ITP patients with active disease had reduced PBMC production of the Th3 cytokine TGF-beta1. This result gives further support to the theory that chronic ITP in active phase is associated with a downregulated Th3-response.

Immunomodulation by metals

Occupational or environmental exposure to metals is believed to affect human health adversely. One mechanism whereby metals can alter health is through modulation of immune homeostasis. Imbalances in immune regulation by metals can lead to inadequate or excessive production of inflammatory cytokines. Alternatively, metals can lead to inappropriate activation of lymphoid subsets involved in acquired immunity to specific antigens. Some resultant pathologies may include chronic inflammatory processes and autoimmune diseases. Metals may change the response repertoire by direct and indirect means by influencing expression of new antigens, new peptides, and/or antigen presentation by modifying the antigen-presenting complex. The differences in metal-induced immune responses between humans and the mechanisms of metal immunomodulation are discussed.

Physical and functional interaction between GATA-3 and Smad3 allows TGF-beta regulation of GATA target genes

BACKGROUND

Members of the GATA family of zinc finger transcription factors are genetically controlled "master" regulators of development in the hematopoietic and nervous systems. Whether GATA factors also serve to integrate epigenetic signals on target promoters is, however, unknown. The transforming growth factor-beta (TGF-beta) superfamily is a large group of phylogenetically conserved secreted factors controlling cell proliferation, differentiation, migration, and survival in multiple tissues.

RESULTS

GATA-3, a key regulator of T helper cell development, was found to directly interact with Smad3, an intracellular signal transducer of TGF-beta. Complex formation required a central region in GATA-3 and the N-terminal domain of Smad3. GATA-3 mediated recruitment of Smad3 to GATA binding sites independently of Smad3 binding to DNA, and the two factors cooperated synergistically to regulate transcription from the IL-5 promoter in a TGF-beta-dependent manner. Treatment of T helper cells with TGF-beta promoted the formation of an endogenous Smad3/GATA-3 nuclear complex and stimulated production of the Th2 cytokine IL-10 in a Smad3- and GATA-3-dependent manner.

CONCLUSIONS

Although Smad proteins are known to interact with a number of general transcription factors, these are insufficient to explain the tissue-specific biology of TGF-beta proteins. Through its interaction with Smad3, GATA-3 is able to integrate a genetic program of cell differentiation with an extracellular signal, providing a molecular framework for the effects of TGF-beta on the development and function of specific subsets of immune cells and possibly other cell types.

TGF-beta1 and donor dendritic cells are common key components in donor-specific blood transfusion and anti-class II heart graft enhancement, whereas tolerance induction also required inflammatory cytokines down-regulation

Heart allograft tolerance in adult recipients can be induced in the LEW.1W to LEW.1A congeneic strain combination by pre-graft donor-specific blood transfusion (DST). Long-term survivors accept LEW.1W graft but reject third party skin grafts. As tolerant recipients of heart allografts showed an increase in anti-donor class II antibodies, we hypothesize that these antibodies could be instrumental in tolerance induction. However, anti-donor MHC class II alone prolonged graft survival but did not induce heart allograft tolerance in this combination. We analyzed the immune response patterns in heart allograft recipients following the injection of anti-donor class II antibodies (prolongation) or DST priming (tolerance). As suggested by the different phenomena, several immunological patterns were strikingly different between the two models. In strong contrast to DST-tolerant recipients, at 5 days after transplantation, neither Th1/Th2 nor inflammatory cytokines were inhibited in recipients treated with anti-donor class II antibodies, in which only prolongation of graft survival was induced. Nevertheless, in both models, depletion of resident dendritic cells (DC) from donor hearts inhibited tolerance induction (DST) or shortened allograft survival (anti-donor class II antibodies). Moreover, TGF-beta1 was not down-regulated and administration of neutralizing anti-TGF-beta1 antibody, which inhibited tolerance induction (DST), also shortened allograft survival (anti-donor class II antibodies). These results suggest that, in these two MHC class II-restricted models, both TGF-beta1 and donor DC have a pivotal role in prolonging graft survival. However, in the days following transplantation, further inhibition of inflammatory cytokine production, particularly Th1 and macrophage-derived cytokines is required for tolerance induction.