Search

We previously reported that regulatory T (Treg) cells expressing CTLA-4 on the cell surface are abundant in head and neck squamous cell carcinoma (HNSCC). The role of expanded Treg cells in the tumor microenvironment of HNSCC remains unclear. In this study, we revealed that the tumor microenvironment of HNSCC is characterized by the high expression of genes related to Treg cells, dendritic cells (DCs), and interleukin (IL)-17-related molecules. Increased expression of IL17A, IL17F, or IL23A contributes to a favorable prognosis of HNSCC. In the tumor microenvironment of HNSCC, IL23A and IL12B are expressed in mature dendritic cells enriched in regulatory molecules (mregDCs). The mregDCs in HNSCC are a migratory and mature phenotype; their signature genes strongly correlate with Treg signature genes in HNSCC. We also observed that IL17A was highly expressed in Th17 cells and exhausted CD8

Photochemotherapy with psoralen and ultraviolet A (PUVA) is widely used for refractory skin diseases. Bathwater delivery of 8-methoxypsoralen (8-MOPS) with subsequent UVA irradiation (bath-PUVA) or oral administration of 8-MOPS with UVA is used to treat mycosis fungoides. We retrospectively analyzed 62 patients with mycosis fungoides (8 stage IA, 30 stage IB, 5 stage IIB, 18 stage IIIA, and 1 stage IVA2) treated with bath-PUVA at the Dermatology Clinic of Nagoya City University Hospital from November 2004 to December 2013. A complete response was achieved in 37 (59.7%) patients, a partial response was achieved in 16 (25.8%), and stable disease was achieved in 6 (9.7%). Progressive disease was observed in 3 (4.8%) patients. Almost all patients in stage IA/IB achieved a complete response. Of the 5 stage IIB patients, 2 achieved a partial response, 1 achieved stable disease, and 2 had progressive disease. The serum concentrations of soluble interleukin-2 receptor and lactate dehydrogenase decreased significantly following treatment with bath-PUVA (p

FOXP3+ regulatory T (Treg) cells suppress anti-tumor immunity. The suppression of Treg cells is regulated by cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), whose expression on the cell surface is tightly regulated. Here we found that Treg cells expressing abundant CTLA-4 on the cell surface (surface-CTLA-4+ Treg) were expanded in human head and neck cancer tissues. RNA sequencing of surface-CTLA-4+ and surface-CTLA-4- Treg cells infiltrating human head and neck cancer tissues revealed that surface-CTLA-4+ Treg cells have a previously undescribed gene expression profile correlating to cell cycle, cell proliferation, and DNA replication. Moreover, surface-CTLA-4+ Treg cells were PD-1+ , actively proliferated and associated with CD45RA- FOXP3high Treg cells with strong suppressive function. Thus, surface-CTLA-4+ Treg cells with a proliferative gene expression signature and phenotype are key features of head and neck cancer. Targeting surface-CTLA-4+ Treg cells might be new strategies to evoke effective immune responses to head and neck cancer.

Summary Ezh2, a well-established epigenetic repressor, can down-regulate leukocyte inflammatory responses, but its role in cutaneous health remains elusive. Here we demonstrate that Ezh2 controls cutaneous tolerance by regulating Langerhans cell (LC) transmigration across the epidermal basement membrane directly via Talin1 methylation. Ezh2 deficiency impaired disassembly of adhesion structures in LCs, leading to their defective integrin-dependent emigration from the epidermis and failure in tolerance induction. Moreover, mobilization of Ezh2-deficient Langerin– dermal dendritic cells (dDCs) via high-dose treatment with a weak allergen restored tolerance, which is associated with an increased tolerogenic potential of Langerin– dDCs likely due to epigenetic de-repression of Aldh in the absence of Ezh2. Our data reveal novel roles for Ezh2 in governing LC- and dDC-mediated host protection against cutaneous allergen via distinct mechanisms., Graphical Abstract, Highlights • Ezh2 regulates LC transmigration across basement membrane via Talin1 methylation • Ezh2-mediated LC migration is required for cutaneous tolerance induction • Ezh2 represses Aldh epigenetically in dermal DCs • Ezh2-deficient dermal DCs exhibit increased tolerogenicity, Dermatology; Biological Sciences; Immunology

Foxp3+CD25+CD4+ regulatory T (Treg) cells constitute about 10% of peripheral CD4+ T cells and suppress a variety of immune responses in mice and humans (1). Our recent report (2) shows that proenkephalin (PENK)-expressing Treg cells expanded by ultraviolet B (UVB) exposure promoted wound healing. The Letter from Slominski et al. (3) points out that skin-resident cells produce enkephalins and other neuropeptides and that skin neuroendocrine activity exerted by keratinocytes, fibroblasts, and melanocytes was detected early after UVB irradiation within a day (3⇓⇓–6), although they did not address possible roles of PENK produced by skin T cells (3⇓⇓– … [↵][1]2To whom correspondence may be addressed. Email: yamazas{at}med.nagoya-cu.ac.jp. [1]: #xref-corresp-1-1

JEM has been a launching pad for scientific careers since its inception. Here is a collection of testimonials attesting to the diversity of the scientific community it serves.

Regulatory T (Treg) cells, expressing CD25 (interleukin-2 receptor α chain) and Foxp3 transcription factor, maintain immunological self-tolerance and suppress various immune responses. Here we report a feature of skin Treg cells expanded by ultraviolet B (UVB) exposure. We found that skin Treg cells possessing a healing function are expanded by UVB exposure with the expression of an endogenous opioid precursor, proenkephalin (PENK). Upon UVB exposure, skin Treg cells were expanded with a unique TCR repertoire. Also, they highly expressed a distinctive set of genes enriched in “wound healing involved in inflammatory responses” and the “neuropeptide signaling pathway,” as indicated by the high expression of Penk. We found that not only was PENK expression at the protein level detected in the UVB-expanded skin Treg (UVB-skin Treg) cells, but that a PENK-derived neuropeptide, methionine enkephalin (Met-ENK), from Treg cells promoted the outgrowth of epidermal keratinocytes in an ex vivo skin explant assay. Notably, UVB-skin Treg cells also promoted wound healing in an in vivo wound closure assay. In addition, UVB-skin Treg cells produced amphiregulin (AREG), which plays a key role in Treg-mediated tissue repair. Identification of a unique function of PENK(+) UVB-skin Treg cells provides a mechanism for maintaining skin homeostasis.

Skin dendritic cells (DCs) are divided into several subsets with distinctive functions. This study shows a previously unappreciated role of dermal CD11b-type Langerin− DCs in maintaining immunological self-tolerance after UVB exposure. After UVB exposure, dermal CD11b-type Langerin− DCs upregulated surface CD86 expression, induced proliferation of Foxp3+ regulatory T (Treg) cells without exogenous Ags, and upregulated a set of genes associated with immunological tolerance. This Treg-expansion activity was significantly hampered by CD80/CD86 blockade in vivo. These results indicate that CD11b-type Langerin− DCs from the UVB-exposed skin are specialized to expand Treg cells in the skin, which suppress autoimmunity.

Chronic low-grade inflammation can cause several metabolic syndromes. Patients with psoriasis, a chronic immunological skin inflammation, often develop diabetes. However, it is not clear to date how psoriasis leads to, or is correlated with, glucose intolerance. Here, we investigate whether psoriasis itself is correlated with hyperglycemia in humans and mice. In patients, the severity of psoriasis was correlated with high blood glucose levels, and treatment of psoriasis by phototherapy improved insulin secretion. Imiquimod-induced systemic and cutaneous inflammation in mice, with features of human psoriasis, also resulted in hyperglycemia. Although it should be determined if psoriasis-like cutaneous inflammation alone can induce hyperglycemia, imiquimod-treated mice showed impairment of insulin secretion without significant islet inflammation. Administration of anti-IL-17A monoclonal antibody improved hyperglycemia in patients with psoriasis and imiquimod-treated mice with psoriasiform features. These results suggest that hyperglycemia is highly associated with psoriasis, mainly through IL-17.

Skin dendritic cells (DCs) are divided into several subsets with distinctive functions. This study shows a previously unappreciated role of dermal CD11b-type Langerin

Dendritic cells (DCs) are central modulators of immune responses and, therefore, interesting target cells for the induction of antitumor immune responses. Ag delivery to select DC subpopulations via targeting Abs to DC inhibitory receptor 2 (DCIR2, clone 33D1) or to DEC205 was shown to direct Ags specifically to CD11c+CD8− or CD11c+CD8+ DCs, respectively, in vivo. In contrast to the increasing knowledge about the induction of immune responses by efficiently cross-presenting CD11c+CD8+ DCs, little is known about the functional role of Ag-presenting CD11c+CD8− DCs with regard to the initiation of protective immune responses. In this study, we demonstrate that Ag targeting to the CD11c+CD8− DC subpopulation in the presence of stimulating anti-CD40 Ab and TLR3 ligand polyinosinic-polycytidylic acid induces protective responses against rapidly growing tumor cells in naive animals under preventive and therapeutic treatment regimens in vivo. Of note, this immunization protocol induced a mixed Th1/Th2-driven immune response, irrespective of which DC subpopulation initially presented the Ag. Our results provide important information about the role of CD11c+CD8− DCs, which have been considered to be less efficient at cross-presenting Ags, in the induction of protective antitumor immune responses.

Background Bath-psoralen plus ultraviolet light A (PUVA) therapy is an effective, safe, and inexpensive treatment for psoriasis. Psoriasis might be due to an unbalanced ratio of Th17 cells and regulatory T cells (Treg). The Treg functional ratio is significantly lower in patients with psoriasis compared with controls and is inversely correlated with the Psoriasis Area and Severity Index score. We previously reported that bath-PUVA therapy significantly increases the number of Treg and restores Treg function to almost normal in most patients with psoriasis. Objectives We examined the effects of bath-PUVA therapy on three distinct Foxp3 + subsets: activated Treg (aTreg), resting Treg (rTreg), and cytokine-secreting non-suppressive T cells. Methods We enrolled 15 patients with psoriasis and 11 healthy controls. We examined aTreg, rTreg, and cytokine-secreting non-suppressive T cells in peripheral blood obtained from the psoriasis patients before and after every fifth bath-PUVA therapy session. Results Levels of aTreg, which are considered to have the strongest suppressive activity in patients with psoriasis, were significantly increased in the early bath-PUVA therapy sessions, and then diminished. Levels of rTreg were lower in psoriasis patients than in healthy controls, and increased during bath-PUVA therapy. Conclusions Bath-PUVA therapy induced aTreg and rTreg concomitantly with an improvement in the psoriatic lesions, suggesting a mechanism for the effectiveness of bath-PUVA therapy for psoriasis patients.

Regulatory T cells (Treg) are a subpopulation of CD4(+) lymphocytes that maintain immunological self-tolerance in the periphery. Treg also regulate or suppress other classes of immune response such as allograft rejection, allergy, tumor immunity, and responses to microbes. Treg express the Foxp3 transcription factor and CD25, the high affinity interleukin-2 receptor (IL-2R). Treg are divided into two types: naturally occurring Treg derived from thymus (natural Treg) and Treg induced from Foxp3(-) CD4(+) T cells in the periphery (induced Treg). It would be valuable to understand how to control the generation of antigen-specific Treg, which could also provide a new approach to treat autoimmunity, allergy or allograft rejection without suppressing immune responses to tumor and microbes. In this review, we will discuss the role of dendritic cells (DCs) in controlling antigen-specific natural Treg and induced Treg. Natural Treg are anergic upon T cell receptor stimulation generally, however, we found that the antigen-specific natural Treg can be expanded by antigen-presenting mature bone marrow-derived dendritic cells (BM-DCs). Furthermore, recent studies showed that antigen-specific Treg can be induced from Foxp3(-) CD25(-) CD4(+) T cells by antigen-presenting DCs, particularly select subsets of DCs in the periphery. These findings need to be pursued to develop novel immune suppressive therapies using antigen-specific Treg educated by DCs.

Foxp3(+)CD25(+)CD4(+) regulatory T cells (Treg) mediate immunological self-tolerance and suppress immune responses. A subset of dendritic cells (DCs) in the intestine is specialized to induce Treg in a TGF-beta- and retinoic acid-dependent manner to allow for oral tolerance. In this study we compare two major DC subsets from mouse spleen. We find that CD8(+) DEC-205/CD205(+) DCs, but not the major fraction of CD8(-) DC inhibitory receptor-2 (DCIR2)(+) DCs, induce functional Foxp3(+) Treg from Foxp3(-) precursors in the presence of low doses of Ag but without added TGF-beta. CD8(+)CD205(+) DCs preferentially express TGF-beta, and the induction of Treg by these DCs in vitro is blocked by neutralizing Ab to TGF-beta. In contrast, CD8(-)DCIR2(+) DCs better induce Foxp3(+) Treg when exogenous TGF-beta is supplied. In vivo, CD8(+)CD205(+) DCs likewise preferentially induce Treg from adoptively transferred, Ag-specific DO11.10 RAG(-/-) Foxp3(-)CD4(+) T cells, whereas the CD8(-)DCIR2(+) DCs better stimulate natural Foxp3(+) Treg. These results indicate that a subset of DCs in spleen, a systemic lymphoid organ, is specialized to differentiate peripheral Foxp3(+) Treg, in part through the endogenous formation of TGF-beta. Targeting of Ag to these DCs might be useful for inducing Ag-specific Foxp3(+) Treg for treatment of autoimmune diseases, transplant rejection, and allergy.

Langerin CD207 is a type II transmembrane protein. It is responsible for the formation of Birbeck granules, which are intracellular organelles within Langerhans cells, the dendritic cells of stratified squamous epithelia like the epidermis. Because current anti-CD207 antibodies have limitations, we prepared new monoclonals by immunizing rats with the extracellular region of mouse Langerin followed by a boost with enriched Langerhans cells (LCs). We secured a large panel of mAbs, most of which reacted with the carboxy terminal carbohydrate recognition domain. These mAbs could be used to immunoblot and immunoprecipitate mouse Langerin and to stain the cell surface and intracellular pools of CD207 by FACS analysis. Labeling of Birbeck granules was also achieved by immunoelectron microscopy. Anti-CD207 identified LCs in the epidermis and skin draining lymph nodes of BALB/c and C57BL/6 mice, but BALB/c mice had an additional Langerin(+) population in spleen, thymus and mesenteric lymph node. This additional subset had higher levels of CD8 and CD205 than epidermal LCs, and also had a less mature phenotype, i.e., lower MHC II, CD40 and CD86. Subcutaneous injection of IgG but not IgM forms of these new anti-CD207 mAbs led to rapid and selective labeling of the Langerin(+) cells in skin draining lymph nodes as well as spleen. The new IgG anti-CD207 mAbs should be useful for further research on LCs and dendritic cells including an evaluation of the consequences of antigen delivery within anti-CD207 mAbs in vivo.

A cytosolic role for the histone methyltransferase Ezh2 in regulating lymphocyte activation has been suggested, but the molecular mechanisms underpinning this extranuclear function have remained unclear. Here we found that Ezh2 regulated the integrin signaling and adhesion dynamics of neutrophils and dendritic cells (DCs). Ezh2 deficiency impaired the integrin-dependent transendothelial migration of innate leukocytes and restricted disease progression in an animal model of multiple sclerosis. Direct methylation of talin, a key regulatory molecule in cell migration, by Ezh2 disrupted the binding of talin to F-actin and thereby promoted the turnover of adhesion structures. This regulatory effect was abolished by targeted disruption of the interactions of Ezh2 with the cytoskeletal-reorganization effector Vav1. Our studies reveal an unforeseen extranuclear function for Ezh2 in regulating adhesion dynamics, with implications for leukocyte migration, immune responses and potentially pathogenic processes. NMRC (Natl Medical Research Council, S’pore) MOE (Min. of Education, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version

To determine whether strong CD4+ T cell immunity could be induced to a nonmutated self protein that is important for tumorigenesis, we selectively targeted the xenogeneic form of survivin, a survival protein overexpressed in tumors, to maturing dendritic cells in lymphoid tissues. Dendritic cell targeting via the DEC205 receptor in the presence of anti-CD40 and poly(I:C) as maturation stimuli, induced strong human and mouse survivin-specific CD4+ T cell responses, as determined by IFN-γ, TNF-α, and IL-2 production, as well as the development of lytic MHC class II-restricted T cells and memory. Immunity was enhanced further by depletion of CD25+foxp3+ cells before vaccination. anti-DEC205-human survivin was superior in inducing CD4+ T cell responses relative to other approaches involving survivin plasmid DNA or survivin peptides with adjuvants. However, we were unable to induce CD8+ T cell immunity to survivin by two doses of DEC205-targeted survivin or the other strategies. Therefore, significant CD4+ T cell immunity to a self protein that is overexpressed in most human cancers can be induced by DEC205 targeting of the Ag in its xenogeneic form to maturing DCs.

Naturally occurring CD25(+)CD4(+) regulatory T cells are engaged in the maintenance of immunological self-tolerance and down-regulation of various immune responses. Recent studies with mice showed that Foxp3, which encodes the transcription factor Scurfin, is a master regulatory gene for the development and function of CD25(+)CD4(+) regulatory T cells. Here we examined the role of FOXP3 in human CD25(+)CD4(+) regulatory T cells. The FOXP3 gene and its protein product were preferentially expressed in peripheral CD25(+)CD4(+) T cells, in particular CD25(+)CD45RO(+)CD4(+) T cells in normal individuals and, interestingly, in some human T cell leukemia virus type 1-infected T cell lines, which constitutively express CD25. TCR stimulation of CD25(-)CD45RO(-)CD4(+) naive T cells failed to elicit FOXP3 expression at the gene or protein level. Ex vivo retroviral gene transfer of FOXP3, on the other hand, converted peripheral CD25(-)CD45RO(-)CD4(+) naive T cells into a regulatory T cell phenotype similar to CD25(+)CD4(+) regulatory T cells. For example, FOXP3-transduced T cells exhibited impaired proliferation and production of cytokines including IL-2 and IL-10 upon TCR stimulation, up-regulated the expression of regulatory T cell-associated molecules such as CD25 and CTL-associated antigen-4 and suppressed in vitro proliferation of other T cells in a cell-cell contact-dependent manner. Thus, human FOXP3 is a crucial regulatory gene for the development and function of CD25(+)CD4(+) regulatory T cells, and can be used as their reliable marker. Furthermore, regulatory T cells de novo produced from normal naive T cells by FOXP3 transduction can be instrumental for treatment of autoimmune/inflammatory diseases and negative control of various immune responses.

In the nonobese diabetic (NOD) mouse model of type 1 diabetes, the immune system recognizes many autoantigens expressed in pancreatic islet β cells. To silence autoimmunity, we used dendritic cells (DCs) from NOD mice to expand CD25+ CD4+ suppressor T cells from BDC2.5 mice, which are specific for a single islet autoantigen. The expanded T cells were more suppressive in vitro than their freshly isolated counterparts, indicating that DCs from autoimmune mice can increase the number and function of antigen-specific, CD25+ CD4+ regulatory T cells. Importantly, only 5,000 expanded CD25+ CD4+ BDC2.5 T cells could block autoimmunity caused by diabetogenic T cells in NOD mice, whereas 105 polyclonal, CD25+ CD4+ T cells from NOD mice were inactive. When islets were examined in treated mice, insulitis development was blocked at early (3 wk) but not later (11 wk) time points. The expanded CD25+ CD4+ BDC2.5 T cells were effective even if administered 14 d after the diabetogenic T cells. Our data indicate that DCs can generate CD25+ CD4+ T cells that suppress autoimmune disease in vivo. This might be harnessed as a new avenue for immunotherapy, especially because CD25+ CD4+ regulatory cells responsive to a single autoantigen can inhibit diabetes mediated by reactivity to multiple antigens.

Rheumatoid arthritis (RA), which afflicts about 1% of the world population, is a chronic systemic inflammatory disease of unknown aetiology that primarily affects the synovial membranes of multiple joints. Although CD4(+) T cells seem to be the prime mediators of RA, it remains unclear how arthritogenic CD4(+) T cells are generated and activated. Given that highly self-reactive T-cell clones are deleted during normal T-cell development in the thymus, abnormality in T-cell selection has been suspected as one cause of autoimmune disease. Here we show that a spontaneous point mutation of the gene encoding an SH2 domain of ZAP-70, a key signal transduction molecule in T cells, causes chronic autoimmune arthritis in mice that resembles human RA in many aspects. Altered signal transduction from T-cell antigen receptor through the aberrant ZAP-70 changes the thresholds of T cells to thymic selection, leading to the positive selection of otherwise negatively selected autoimmune T cells. Thymic production of arthritogenic T cells due to a genetically determined selection shift of the T-cell repertoire towards high self-reactivity might also be crucial to the development of disease in a subset of patients with RA.

An important pathway for immune tolerance is provided by thymic-derived CD25+ CD4+ T cells that suppress other CD25− autoimmune disease–inducing T cells. The antigen-presenting cell (APC) requirements for the control of CD25+ CD4+ suppressor T cells remain to be identified, hampering their study in experimental and clinical situations. CD25+ CD4+ T cells are classically anergic, unable to proliferate in response to mitogenic antibodies to the T cell receptor complex. We now find that CD25+ CD4+ T cells can proliferate in the absence of added cytokines in culture and in vivo when stimulated by antigen-loaded dendritic cells (DCs), especially mature DCs. With high doses of DCs in culture, CD25+ CD4+ and CD25− CD4+ populations initially proliferate to a comparable extent. With current methods, one third of the antigen-reactive T cell receptor transgenic T cells enter into cycle for an average of three divisions in 3 d. The expansion of CD25+ CD4+ T cells stops by day 5, in the absence or presence of exogenous interleukin (IL)-2, whereas CD25− CD4+ T cells continue to grow. CD25+ CD4+ T cell growth requires DC–T cell contact and is partially dependent upon the production of small amounts of IL-2 by the T cells and B7 costimulation by the DCs. After antigen-specific expansion, the CD25+ CD4+ T cells retain their known surface features and actively suppress CD25− CD4+ T cell proliferation to splenic APCs. DCs also can expand CD25+ CD4+ T cells in the absence of specific antigen but in the presence of exogenous IL-2. In vivo, both steady state and mature antigen-processing DCs induce proliferation of adoptively transferred CD25+ CD4+ T cells. The capacity to expand CD25+ CD4+ T cells provides DCs with an additional mechanism to regulate autoimmunity and other immune responses.

CD25+CD4+ regulatory T cells in normal animals are engaged in the maintenance of immunological self-tolerance. We show here that glucocorticoid-induced tumor necrosis factor receptor family–related gene (GITR, also known as TNFRSF18)—a member of the tumor necrosis factor–nerve growth factor (TNF-NGF) receptor gene superfamily—is predominantly expressed on CD25+CD4+ T cells and on CD25+CD4+CD8− thymocytes in normal naive mice. We found that stimulation of GITR abrogated CD25+CD4+ T cell–mediated suppression. In addition, removal of GITR-expressing T cells or administration of a monoclonal antibody to GITR produced organ-specific autoimmune disease in otherwise normal mice. Thus, GITR plays a key role in dominant immunological self-tolerance maintained by CD25+CD4+ regulatory T cells and could be a suitable molecular target for preventing or treating autoimmune disease.

Accumulating evidence shows that immunological tolerance induced by Ag administration together with UVB irradiation is dependent on Foxp3+ CD4+ regulatory T (Treg) cells. However, the mechanisms by which UVB controls Treg cells in the skin are currently unclear. In this study, we have shown that exposure to UVB induced expansion of Treg cells up to 50–60% of the CD4+ T cells in the irradiated skin. The Treg cell expansion in the skin lasted for 2 wk after exposure, which contributed to homeostasis of Treg cells in the periphery later. UVB-expanded Treg cells formed clusters with dendritic cells and proliferated in situ. Furthermore, the expanded Treg cells appeared to derive from neuropilin 1+ thymus-derived Treg (tTreg) cells in the periphery because UVB-expanded Treg cells possessed Treg cell–specific CpG hypomethylation pattern, as seen in tTreg cells. These results collectively indicate that homeostasis of tTreg cells is controlled by UVB exposure in the skin. UVB therapy may be useful for not only inflammatory skin disorders, but also autoimmunity, transplantation, and allergy.

T cells that mediate autoimmune diseases such as rheumatoid arthritis (RA) are difficult to characterize because they are likely to be deleted or inactivated in the thymus if the self antigens they recognize are ubiquitously expressed. One way to obtain and analyze these autoimmune T cells is to alter T cell receptor (TCR) signaling in developing T cells to change their sensitivity to thymic negative selection, thereby allowing their thymic production. From mice thus engineered to generate T cells mediating autoimmune arthritis, we isolated arthritogenic TCRs and characterized the self antigens they recognized. One of them was the ubiquitously expressed 60 S ribosomal protein L23a (RPL23A), with which T cells and autoantibodies from RA patients reacted. This strategy may improve our understanding of the underlying drivers of autoimmunity.

There is accumulating evidence that T-cell-mediated dominant control of self-reactive T-cells contributes to the maintenance of immunologic self-tolerance and its alteration can cause autoimmune disease. Efforts to delineate such a regulatory T-cell population have revealed that CD25+ cells in the CD4+ population in normal naive animals bear the ability to prevent autoimmune disease in vivo and, upon antigenic stimulation, suppress the activation/proliferation of other T cells in vitro. The CD25+ CD4+ regulatory T cells, which are naturally anergic and suppressive, appear to be produced by the normal thymus as a functionally distinct subpopulation of T cells. They play critical roles not only in preventing autoimmunity but also in controlling tumor immunity and transplantation tolerance.

This report shows that cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) plays a key role in T cell-mediated dominant immunologic self-tolerance. In vivo blockade of CTLA-4 for a limited period in normal mice leads to spontaneous development of chronic organ-specific autoimmune diseases, which are immunopathologically similar to human counterparts. In normal naive mice, CTLA-4 is constitutively expressed on CD25(+)CD4(+) T cells, which constitute 5-10% of peripheral CD4(+) T cells. When the CD25(+)CD4(+) T cells are stimulated via the T cell receptor in vitro, they potently suppress antigen-specific and polyclonal activation and proliferation of other T cells, including CTLA-4-deficient T cells, and blockade of CTLA-4 abrogates the suppression. CD28-deficient CD25(+)CD4(+) T cells can also suppress normal T cells, indicating that CD28 is dispensable for activation of the regulatory T cells. Thus, the CD25(+)CD4(+) regulatory T cell population engaged in dominant self-tolerance may require CTLA-4 but not CD28 as a costimulatory molecule for its functional activation. Furthermore, interference with this role of CTLA-4 suffices to elicit autoimmune disease in otherwise normal animals, presumably through affecting CD25(+)CD4(+) T cell-mediated control of self-reactive T cells. This unique function of CTLA-4 could be exploited to potentiate T cell-mediated immunoregulation, and thereby to induce immunologic tolerance or to control autoimmunity.

Dendritic cells (DCs) are specialized antigen-presenting cells that regulate both immunity and tolerance. DCs in the periphery play a key role in expanding naturally occurring Foxp3(+) CD25(+) CD4(+) regulatory T cells (Natural T-regs) and inducing Foxp3 expression (Induced T-regs) in Foxp3(-) CD4(+) T cells. DCs are phenotypically and functionally heterogeneous, and further classified into several subsets depending on distinct marker expression and their location. Recent findings indicate the presence of specialized DC subsets that act to expand Natural T-regs or induce Foxp3(+) T-regs from Foxp3(-) CD4(+) T cells. For example, two major subsets of DCs in lymphoid organs act differentially in inducing Foxp3(+) T-regs from Foxp3(-) cells or expanding Natural T-regs with model-antigen delivery by anti-DC subset monoclonal antibodies in vivo. Furthermore, DCs expressing CD103 in the intestine induce Foxp3(+) T-regs from Foxp3(-) CD4(+) T cells with endogenous TGF-β and retinoic acid. In addition, antigen-presenting DCs have a capacity to generate Foxp3(+) T-regs in the oral cavity where many antigens and commensals exist, similar to intestine and skin. In skin and skin-draining lymph nodes, at least six DC subsets have been identified, suggesting a complex DC-T-reg network. Here, we will review the specific activity of DCs in expanding Natural T-regs and inducing Foxp3(+) T-regs from Foxp3(-) precursors, and further discuss the critical function of DCs in maintaining tolerance at various locations including skin and oral cavity.

Evidence is accumulating that dendritic cells (DCs) from the intestines have the capacity to induce Foxp3(+)CD4(+) regulatory T cells (T-regs) and regulate immunity versus tolerance in the intestines. However, the contribution of DCs to controlling immunity versus tolerance in the oral cavity has not been addressed. Here, we report that DCs from the oral cavity induce Foxp3(+) T-regs as well as DCs from intestine. We found that oral-cavity-draining cervical lymph nodes contained higher frequencies of Foxp3(+) T-regs and ROR-γt(+) CD4(+)T cells than other lymph nodes. The high frequency of Foxp3(+) T-regs in the oral-cavity-draining cervical lymph nodes was not dependent on the Toll like receptor (TLR) adaptor molecules, Myd88 and TICAM-1 (TRIF). In contrast, the high frequency of ROR-γt(+) CD4(+)T cells relies on Myd88 and TICAM-1. In vitro data showed that CD11c(+) DCs from oral-cavity-draining cervical lymph nodes have the capacity to induce Foxp3(+) T-regs in the presence of antigen. These data suggest that, as well as in the intestinal environment, antigen-presenting DCs may play a vital role in maintaining tolerance by inducing Foxp3(+) T-regs in the oral cavity.

Made available in DSpace on 2018-12-11T17:07:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Paracoccidioides spp., which are temperature-dependent dimorphic fungi, are responsible for the most prevalent human systemic mycosis in Latin America, the paracoccidioidomycosis. The aim of this study was to characterise the involvement of elongation factor Tu (EF-Tu) in Paracoccidioides brasiliensis-host interaction. Adhesive properties were examined using recombinant PbEF-Tu proteins and the respective polyclonal anti-rPbEF-Tu antibody. Immunogold analysis demonstrated the surface location of EF-Tu in P. brasiliensis. Moreover, PbEF-Tu was found to bind to fibronectin and plasminogen by enzyme-linked immunosorbent assay, and it was determined that the binding to plasminogen is at least partly dependent on lysine residues and ionic interactions. To verify the participation of EF-Tu in the interaction of P. brasiliensis with pneumocytes, we blocked the respective protein with an anti-rPbEF-Tu antibody and evaluated the consequences on the interaction index by flow cytometry. During the interaction, we observed a decrease of 2- and 3-fold at 8 and 24 h, respectively, suggesting the contribution of EF-Tu in fungal adhesion/invasion. Faculdade de Ciências Farmacêuticas UNESP - Univ Estadual Paulista Departamento de Análises Clínicas Laboratório de Micologia Clínica Instituto de Química UNESP - Univ Estadual Paulista Departamento de Bioquímica e Tecnologia Química Unidade de Sintese Estrutura e Caracterizacao de Peptideos e Proteinas Faculdade de Ciências Farmacéuticas UNESP - Univ Estadual Paulista Departamento de Análises Clínicas Laboratório de Imunologia Clínica Faculdade de Ciências Farmacêuticas UNESP - Univ Estadual Paulista Departamento de Análises Clínicas Laboratório de Micologia Clínica Instituto de Química UNESP - Univ Estadual Paulista Departamento de Bioquímica e Tecnologia Química Unidade de Sintese Estrutura e Caracterizacao de Peptideos e Proteinas Faculdade de Ciências Farmacéuticas UNESP - Univ Estadual Paulista Departamento de Análises Clínicas Laboratório de Imunologia Clínica FAPESP: 2015/03700-9

BACKGROUND: Photo(chemo)therapy is widely used to treat psoriasis, the pathogenesis of which might be caused by an imbalance of Th17 cells/regulatory T cells (Treg). In the present study, we evaluated the effects of photo(chemo)therapy on the Th17/Treg balance and Treg function. METHODS: Peripheral blood was obtained from psoriasis patients treated with bath-psoralen ultraviolet A (UVA, n = 50) or narrowband ultraviolet B (UVB, n = 18), and age-matched healthy volunteers (n = 20). CD3(+)CD4(+)IL-17A(+) or CD4(+)CD25(+)Foxp3(+)cells were analyzed to estimate Th17 or Treg number by fluorescence-activated cell sorting. Moreover, CD4(+) CD25(-) T cells from patients treated with PUVA(n = 14) were incubated in CFSE and activated with or without CD4(+) CD25(+)T cells, and the suppressive function of CD4(+) CD25(+)T cells were analyzed. RESULTS: Photo(chemo)therapy significantly reduced Th17 levels from 5.66 ± 3.15% to 2.96 ± 2.89% in patients with increased Th17 (Th17/CD4>3.01% [mean+SD of controls]). In contrast, photo(chemo)therapy significantly increased Treg levels from 2.77 ± 0.75 to 3.40 ± 1.88% in patients with less than 4.07% Treg level, defined as the mean of controls. Furthermore, while Treg suppressed the CD4(+)CD25(-) T cell proliferation to a greater extent in controls (Treg Functional Ratio 94.4 ± 4.28%) than in patients (70.3±25.1%), PUVA significantly increased Treg Functional Ratio to 88.1 ± 6.47%. Th17 levels in severe patients (>30 PASI) were significantly higher as compared to controls. Th17 levels that were left after treatment in the patients not achieving PASI 50 (3.78 ± 4.18%) were significantly higher than those in the patients achieving PASI 75 (1.83±1.87%). Treg levels in patients achieving PASI 90 (4.89 ± 1.70%) were significantly higher than those in the patients not achieving PASI 90 (3.90 ± 1.66%). Treg levels prior to treatment with Th17 high decreased group (5.16 ± 2.20%) was significantly higher than that with Th17 high increased group (3.33 ± 1.39%). CONCLUSION: These findings indicate that Treg is dysfunctional in psoriasis patients, and photochemotherapy restores those dysfunctional Treg. Photo(chemo)therapy resolved the Th17/Treg imbalance in patients with psoriasis.