Treg Cell Population Research Articles

Regulatory T cells and immune tolerance in the intestine.

A fundamental role of the mammalian immune system is to eradicate pathogens while minimizing immunopathology. Instigating and maintaining immunological tolerance within the intestine represents a unique challenge to the mucosal immune system. Regulatory T cells are critical for continued immune tolerance in the intestine through active control of innate and adaptive immune responses. Dynamic adaptation of regulatory T-cell populations to the intestinal tissue microenvironment is key in this process. Here, we discuss specialization of regulatory T-cell responses in the intestine, and how a breakdown in these processes can lead to chronic intestinal inflammation.

Eosinophilic/T-Cell Chorionic Vasculitis and Chronic Villitis Involve Regulatory T Cells and Often Occur Together

Eosinophilic/T-cell chorionic vasculitis (ETCV) is characterized by mixed T-cell, eosinophilic, and histiocytic infiltrates within the chorionic vessel wall. We sought to better characterize this lesion with respect to other pathologic correlates and the T-cell populations involved. Epidemiologic data and other pathologic diagnoses, including concurrent chronic villitis (CV), were tabulated for each case of ETCV diagnosed at our institution over a 6-year period. CD3, CD25, FOXP3, and dual FOXP3-CD3 immunostains were used to identify regulatory T-cell populations in ETCV and CV. Cells positive for CD3, FOXP3, and CD25 were quantitated by manual counts of ×40 fields at the sites of ETCV and CV, and FOXP3∶CD3 and CD25∶CD3 ratios were calculated. Digital analysis of ETCV and CV using the dual FOXP3-CD3 immunostain was also performed on select cases. Of 31 ETCV cases, 10 (32%) were accompanied by CV and 13 (42%) by a thrombus in the vessel affected by ETCV. The mean Treg cell marker∶CD3 ratios in ETCV ranged from 0.18 to 0.26 by manual count and digital analysis, but the counts did not statistically differ by method. The mean Treg cell marker∶CD3 ratios in CV ranged from 0.37 to 0.39 by manual count and 0.19 by digital analysis, but these counts also did not statistically differ by method. Chronic villitis was seen in one-third of ETCV cases. FOXP3+ and CD25+ regulatory T cells represent a significant subpopulation of T cells in ETCV and CV, suggesting that they may play a role in these entities.

Changes in the balance between Treg and Th17 cells in patients with chronic hepatitis B

The purpose of this study was to explore the role of Treg cells, Th17 cells and cytokines associated with Treg/Th17 differentiation in the occurrence, development and outcome of chronic hepatitis B (CHB). To do so, we detected populations of Treg and Th17 cells and their associated cytokines in the peripheral blood of CHB patients. The populations of Treg cells (CD4+CD25highCD127low T cells) and Th17 cells (CD3+CD8-IL-17+ T cells) were analyzed in 46 patients with low to moderate chronic hepatitis B (CHB-LM), 24 patients with severe chronic hepatitis B (CHB-S) and 20 healthy controls (HC) using flow cytometry. The levels of cytokines associated with Treg/Th17 differentiation, including IL-10, TGF-β1, IL-17 and IL-23, were measured by enzyme-linked immunosorbent assay (ELISA). Our study showed that the imbalance of Treg and Th17 cells might play an important role in the occurrence, development and outcome of CHB.

Pathogen-Specific Treg Cells Expand Early during Mycobacterium tuberculosis Infection but Are Later Eliminated in Response to Interleukin-12

Thymically derived Foxp3⁺ regulatory T (Treg) cells have a propensity to recognize self-peptide:MHC complexes, but their ability to respond to epitope-defined foreign antigens during infectious challenge has not been demonstrated. Here we show that pulmonary infection with Mycobacterium tuberculosis (Mtb), but not Listeria monocytogenes (Lm), induced robust lymph node expansion of a highly activated population of pathogen-specific Treg cells from the pre-existing pool of thymically derived Treg cells. These antigen-specific Treg cells peaked in numbers 3 weeks after infection but subsequently underwent selective elimination driven, in part, by interleukin-12-induced intrinsic expression of the Th1-cell-promoting transcription factor T-bet. Thus, the initial Mtb-induced inflammatory response promotes pathogen-specific Treg cell proliferation, but these cells are actively culled later, probably to prevent suppression during later stages of infection. These findings have important implications for the prevention and treatment of tuberculosis and other chronic diseases in which antigen-specific Treg cells restrict immunity.

AB0076 Study of physiological activity of cd4+cd25+ cells during adjuvant arthritis prior to and after introduction of cryopreserved placental cells

BackgroundAn important role in the development of autoimmune reactions during rheumatoid arthritis (RA) is played by CD4+CD25+ T-regulatory cells (Treg) possessing a suppressive activity. The ability of placental structures to...

A Variable CD3+ T-Cell Frequency in Peripheral Blood Lymphocytes Associated with Type 1 Diabetes Mellitus Development in the LEW.1AR1-iddm Rat

PurposeThe LEW.1AR1-iddm rat is an animal model of human type 1 diabetes mellitus (T1DM), which arose through a spontaneous mutation within the MHC-congenic inbred strain LEW.1AR1 (RT1r2). In contrast to the diabetes-resistant LEW.1AR1 background strain in LEW.1AR1-iddm rats a highly variable T-cell frequency could be observed in peripheral blood lymphocytes (PBLs).MethodsIn this study we therefore characterised the T-cell repertoire within the PBLs of the two strains by flow cytometry analysis and identified the CD3+ T-cell phenotype and its possible linkage to diabetes susceptibility. To map loci conferring susceptibility to variable CD3+ T-cell frequency, backcross strains (N2) were generated with the genetically divergent BN and PAR rats for microsatellite analysis.ResultsThe LEW.1AR1-iddm rat strain was characterised by a higher variability of CD3+ T-cells in PBLs along with a slightly decreased mean value compared to the LEW.1AR1 background strain. The reason for this reduction was a decrease in the CD4+ T-cell count while the CD8+ T-cell proportion remained unchanged. However, both T-cell subpopulations showed a high variability. This resulted in a lower CD4+/CD8+ T-cell ratio than in LEW.1AR1 rats. Like LEW.1AR1-iddm rats all animals of the backcross populations, N2 BN and N2 PAR rats, also showed large variations of the CD3+ T-cell frequency. The phenotype of variable CD3+ T-cell frequency mapped to the telomeric region of chromosome 1 (RNO1), which is identical with the already known Iddm8 diabetes susceptibility region. The data indicate that a variable CD3+ T-cell frequency in PBLs is genetically linked to diabetes susceptibility in the LEW.1AR1-iddm rat.ConclusionThe T-cell variability in PBLs could be related to the previously reported imbalance between regulatory and effector T-cell populations which results in beta-cell autoimmunity. Since similar T-cell phenotypes have also been described in human T1DM the identification of the functional role of the observed variable CD3+ T-cell frequency may help to understand the mechanisms of autoimmunity in T1DM.

CD4+CD25+ T regulatory cells dampen inflammatory responses in murine mycoplasma pneumonia and are associated with promotion of IL-17 AND IFN-γ production, but not IL-10 or TGF-β. (P3055)

Abstract Mycoplasmas cause respiratory diseases characterized by persistent infection and chronic airway inflammation. Mycoplasma lung disease is immunopathologic, with Th cells determining disease severity and resistance to infection. Th2 cell responses promote immunopathology; Th1 cells confer resistance to infection. However, little is known about the role of Treg cells in mycoplasma respiratory diseases. We hypothesized Treg cells control the severity of the inflammatory lesions and may also promote persistence of infection, as found in other diseases. To examine this, mice, given anti-CD25 antibody to deplete Treg cells, had increased disease severity due to Mycoplasma pulmonis infection. There was however no affect on mycoplasma numbers recovered from the lungs. Treg cells promote the secretion of IFN-γ and IL-17 mycoplasma-specific CD4+ T cell responses in vitro. We were unable to detect significant changes in IL-10 and TGF-β production. In addition, Treg cell depletion increased Th2 (IL-13) responses. Populations of Treg cells from lymph nodes had increased expression of IFN-γ or IL-17 after infection. Thus, Treg cells play an important role in controlling damaging immune responses in mycoplasma respiratory infection but do not influence the level of mycoplasma infection. It appears that Treg cells dampen mycoplama inflammatory disease through a novel mechanism mediated production of IFN-γ and IL-17.

Radiofrequency Ablation Does Not Induce the Significant Increase of CD4+CD25+Foxp3+ Regulatory T Cells Compared with Surgical Resection in Hepal-6 Tumor Model

Surgical resection (SR) and radiofrequency ablation (RFA) are all currently recognized as important and effective treatment in solid tumors. This study aimed to investigate change in level of CD4(+) CD25(+) Foxp3(+) regulatory T (Treg) cells in tumor-bearing mice after SR vs. RFA and the relationship of this level with tumor progression. Hepa1-6 tumor cells were inoculated subcutaneously into C57BL/6J mice. The population of Treg cells was measured by flow cytometry at selected post-SR or post-RFA times. Tumor growth was measured by rechallenge in the contralateral flank. The tumor volume was calculated and compared with that of a control group. The correlation between the population of Treg cells and tumor volume was analyzed. A significant increase in Treg cells was observed after SR compared with the preoperative level, while the level after RFA was relatively stable. A significant difference in tumor growth between the SR and RFA groups was observed in the initial postoperative phase but not in the later phase. A correlation was found between tumor volume and level of Treg cells. Our study revealed that RFA stabilizes the level of Treg during postoperative recovery, whereas SR activates the immunosuppressive reaction by upregulating the level of such cells, promoting tumor growth.

The G protein-coupled estrogen receptor (GPER) agonist G-1 expands the regulatory T-cell population under TH17-polarizing conditions.

The transcription factor Foxp3 is critical to the suppressive phenotype of CD4+ regulatory T cells. Studies have clearly shown that numerous autoimmune diseases are marked by the presence of activated CD4+ T cells within the setting of chronic inflammation. Therefore, drugs capable of inducing Foxp3 expression in activated CD4+ T cells could be of great therapeutic interest. We have previously shown that the small molecule G-1, an agonist directed against the membrane-bound G protein-coupled estrogen receptor, can induce IL10 expression in naive CD4+ T cells. In addition, we and others have demonstrated that G-1 attenuates disease in an animal model of experimental autoimmune encephalomyelitis. Using ex vivo cultures of purified CD4+ T cells, we show that G-1 can elicit Foxp3 expression under TH17-polarizing conditions, which mimic the in situ inflammatory milieu of several autoimmune diseases. These findings build upon previous results demonstrating the immunosuppressive properties of the novel estrogenic small molecule G-1.

Triptolide-Conditioned Dendritic Cells Induce Allospecific T-Cell Regulation and Prolong Renal Graft Survival

ABSTRACTBackground: Previous studies show that triptolide (TPT), a diterpenoid isolated from the Chinese herb Tripterygium wilfordii Hook.f, inhibits dendritic cell (DCs) maturation. Whether TPT-conditioned DCs (TPT-DCs) may regulate allospecific immune responses remains unclear. In this study, we investigated the effects of TPT on allostimulatory function and phenotype of rat bone marrow-derived DCs (BMDCs). Methods: Brown Norway rats BMDCs were cultured with or without TPT and then stimulated with lipopolysaccharide (LPS). IL-10 in supernatants was quantitatively measured, and the cells were analyzed by flow cytometry and used as stimulators in mixed leukocyte reaction in which naive Lewis rat T lymphocytes were used as responders. The tolerogenic potential of TPT-BMDCs was evaluated in vivo in a rat model of MHC fully mismatched kidney transplantation. Results: After treatment with TPT, BMDCs remained immature with low expression of CD80 and CD86 in the presence of LPS. At low concentrations of TPT (1 and 2.5 nM), BMDCs produced higher levels of IL-10 than the untreated cells (431 and 205.4 pg/ml, respectively, vs. 122.9 pg/ml, p < .05). T cells cocultured with TPT-BMDCs were hyporesponsive in allogeneic mixed lymphocyte reaction. The CD25+foxp3+Treg cell populations increased from 19.9% to 29.7% in the coculture system. Without immunosuppressive therapy, infusion of TPT-BMDCs in recipients before transplantation prolonged rat kidney allograft survival (18.8 ± 1.30 days). Conclusions: Our findings demonstrate that TPT inhibits the maturation and allogenicity of BMDCs and promotes the expansion of CD25+foxp3+ regulatory T cells. It suggests that TPT-DCs are potentially useful for preventing kidney transplant rejection.

Metabolic control of the Treg/Th17 axis

The interplay of the immune system with other aspects of physiology is continually being revealed and in some cases studied in considerable mechanistic detail. A prime example is the influence of metabolic cues on immune responses. It is well appreciated that upon activation, T cells take on a metabolic profile profoundly distinct from that of their quiescent and anergic counterparts; however, a number of recent breakthroughs have greatly expanded our knowledge of how aspects of cellular metabolism can shape a T-cell response. Particularly important are findings that certain environmental cues can tilt the delicate balance between inflammation and immune tolerance by skewing T-cell fate decisions toward either the T-helper 17 (Th17) or T-regulatory (Treg) cell lineage. Recognizing the unappreciated immune-modifying potential of metabolic factors and particularly those involved in the generation of these functionally opposing T-cell subsets will likely add new and potent therapies to our repertoire for treating immune mediated pathologies. In this review, we summarize and discuss recent findings linking certain metabolic pathways, enzymes, and by-products to shifts in the balance between Th17 and Treg cell populations. These advances highlight numerous opportunities for immune modulation.

TLR-2 Activation Induces Regulatory T Cells and Long-Term Suppression of Asthma Manifestations in Mice

Asthma is a chronic inflammatory disease of the airways characterized by variable airway obstruction and airway hyperresponsiveness (AHR). The T regulatory (Treg) cell subset is critically important for the regulation of immune responses. Adoptive transfer of Treg cells has been shown to be sufficient for the suppression of airway inflammation in experimental allergic asthma. Intervention strategies aimed at expanding the Treg cell population locally in the airways of sensitized individuals are therefore of high interest as a potential therapeutic treatment for allergic airway disease. Here, we aim to test whether long-term suppression of asthma manifestations can be achieved by locally expanding the Treg cell subset via intranasal administration of a TLR-2 agonist. To model therapeutic intervention aimed at expanding the endogenous Treg population in a sensitized host, we challenged OVA-sensitized mice by OVA inhalation with concomitant intranasal instillation of the TLR-2 agonist Pam3Cys, followed by an additional series of OVA challenges. Pam3Cys treatment induced an acute but transient aggravation of asthma manifestations, followed by a reduction or loss of AHR to methacholine, depending on the time between Pam3Cys treatment and OVA challenges. In addition, Pam3Cys-treatment induced significant reductions of eosinophils and increased numbers of Treg cells in the lung infiltrates. Our data show that, despite having adverse acute effects, TLR2 agonist treatment as a therapeutic intervention induces an expansion of the Treg cell population in the lungs and results in long-term protection against manifestation of allergic asthma upon subsequent allergen provocation. Our data indicate that local expansion of Tregs in allergic airway disease is an interesting therapeutic approach that warrants further investigation.

Intravenous Methylprednisolone Pulse Therapy Target CD8+ Regulatory T Cell in Lupus Nephritis with Refractory Proteinuria

We evaluated whether Intravenous methyl-prednisolone (IVMP) administration in patients with active class III/IV lupus nephritis (LN) is related to changes in CD8+FoxP3+ regulatory T (Treg) cell population, enhance CD8+Treg suppressive function in peripheral blood mononuclear cells (PBMCs) and renal tissues. Fourty patients with class III/IV lupus nephritis were treated with IVMP. PBMCs were isolated from patients before and after two weeks of IVMP. IVMP therapy significantly increased CD8+Foxp3+ Treg cells expression with intracellular IL-10 and granzyme B in PBMCs. IVMP-treated CD8+CD25+ Treg cells directly suppressed CD4+ T cell proliferation and induced CD4+CD45RO+ cell apoptosis. Histologically, a few of both CD4+FoxP3+ and CD8+FoxP3+ Treg cells in renal tissue of LN patients before IVMP by double immunohistochemical stain. CD8+FoxP3+ Treg cells increased in ten cases of follow-up renal biopsy specimens after IVMP. Difference of CD8+CD25+FoxP3+Treg cells in PBMCs before and two weeks after IVMP correlated with decrease of Δ daily urine protein and anti-ds DNA Ab titers. siRNA of FoxP3 significantly suppressed granzyme B expression and decreasing CD8+CD25+Treg cell induced CD4+CD45RO+cell apoptosis. IVMP therapy induces immunomodulatory effect partly by inducing CD8+CD25+Treg cell function, and hence may have therapeutic impact on treatment of LN.

The immunosuppressive tumour network: myeloid‐derived suppressor cells, regulatory T cells and natural killer T cells

Myeloid-derived suppressor cells (MDSC) and regulatory T (Treg) cells are major components of the immune suppressive tumour microenvironment (TME). Both cell types expand systematically in preclinical tumour models and promote T-cell dysfunction that in turn favours tumour progression. Clinical reports show a positive correlation between elevated levels of both suppressors and tumour burden. Recent studies further revealed that MDSCs can modulate the de novo development and induction of Treg cells. The overlapping target cell population of Treg cells and MDSCs is indicative for the importance and flexibility of immune suppression under pathological conditions. It also suggests the existence of common pathways that can be used for clinical interventions aiming to manipulate the TME. Elimination or reprogramming of the immune suppressive TME is one of the major current challenges in immunotherapy of cancer. Interestingly, recent findings suggest that natural killer T (NKT) cells can acquire the ability to convert immunosuppressive MDSCs into immunity-promoting antigen-presenting cells. Here we will review the cross-talk between MDSCs and other immune cells, focusing on Treg cells and NKT cells. We will consider its impact on basic and applied cancer research and discuss how targeting MDSCs may pave the way for future immunocombination therapies.

Neem Leaf Glycoprotein Activates CD8+ T Cells to Promote Therapeutic Anti-Tumor Immunity Inhibiting the Growth of Mouse Sarcoma

In spite of sufficient data on Neem Leaf Glycoprotein (NLGP) as a prophylactic vaccine, little knowledge currently exists to support the use of NLGP as a therapeutic vaccine. Treatment of mice bearing established sarcomas with NLGP (25 µg/mice/week subcutaneously for 4 weeks) resulted in tumor regression or dormancy (Tumor free/Regressor, 13/24 (NLGP), 4/24 (PBS)). Evaluation of CD8+ T cell status in blood, spleen, TDLN, VDLN and tumor revealed increase in cellular number. Elevated expression of CD69, CD44 and Ki67 on CD8+ T cells revealed their state of activation and proliferation by NLGP. Depletion of CD8+ T cells in mice at the time of NLGP treatment resulted in partial termination of tumor regression. An expansion of CXCR3+ and CCR5+ T cells was observed in the TDLN and tumor, along with their corresponding ligands. NLGP treatment enhances type 1 polarized T-bet expressing T cells with downregulation of GATA3. Treg cell population was almost unchanged. However, T∶Treg ratios significantly increased with NLGP. Enhanced secretion/expression of IFNγ was noted after NLGP therapy. In vitro culture of T cells with IL-2 and sarcoma antigen resulted in significant enhancement in cytotoxic efficacy. Consistently higher expression of CD107a was also observed in CD8+ T cells from tumors. Reinoculation of sarcoma cells in tumor regressed NLGP-treated mice maintained tumor free status in majority. This is correlated with the increment of CD44hiCD62Lhi central memory T cells. Collectively, these findings support a paradigm in which NLGP dynamically orchestrates the activation, expansion, and recruitment of CD8+ T cells into established tumors to operate significant tumor cell lysis.

Trafficking of regulatory T cells in the intestinal immune system

Intestinal tolerance toward dietary antigens and the microbiota critically depends on regulatory T cells (T(reg) cells). To exert their function, T(reg) cells need to get into the proximity of their target cells foremost within lymphoid organs and the lamina propria in the small and large intestines. Thus, T(reg)-cell-mediated immunosuppression is intrinsically linked to cell migration and localization. However, the gut lamina propria not only constitutes an effector site but also actively influences T(reg)-cell function. In particular, gut-resident macrophages take an active role in shaping the T(reg)-cell pool. Here, the author summarizes recent observations to suggest that T(reg)-cell migration not only directs cells to sites of immunosuppression but also allows for the coordinated shaping of the T(reg)-cell population.

TLR3 deficiency induces chronic inflammatory cardiomyopathy in resistant mice following coxsackievirus B3 infection: role for IL-4

Recent findings indicate that TLR3 polymorphisms increase susceptibility to enteroviral myocarditis and inflammatory dilated cardiomyopathy (iDCM) in patients. TLR3 signaling has been found to inhibit coxsackievirus B3 (CVB3) replication and acute myocarditis in mouse models, but its role in the progression from myocarditis to iDCM has not been previously investigated. In this study we found that TLR3 deficiency increased acute (P = 5.9 × 10(-9)) and chronic (P = 6.0 × 10(-7)) myocarditis compared with WT B6.129, a mouse strain that is resistant to chronic myocarditis and iDCM. Using left ventricular in vivo hemodynamic assessment, we found that TLR3-deficient mice developed progressively worse chronic cardiomyopathy. TLR3 deficiency significantly increased viral replication in the heart during acute myocarditis from day 3 through day 12 after infection, but infectious virus was not detected in the heart during chronic disease. TLR3 deficiency increased cytokines associated with a T helper (Th)2 response, including IL-4 (P = 0.03), IL-10 (P = 0.008), IL-13 (P = 0.002), and TGF-β(1) (P = 0.005), and induced a shift to an immunoregulatory phenotype in the heart. However, IL-4-deficient mice had improved heart function during acute CVB3 myocarditis by echocardiography and in vivo hemodynamic assessment compared with wild-type mice, indicating that IL-4 impairs cardiac function during myocarditis. IL-4 deficiency increased regulatory T-cell and macrophage populations, including FoxP3(+) T cells (P = 0.005) and Tim-3(+) macrophages (P = 0.004). Thus, TLR3 prevents the progression from myocarditis to iDCM following CVB3 infection by reducing acute viral replication and IL-4 levels in the heart.

Vedolizumab Does Not Affect the Suppressive Activity of Gut-homing T Regulatory Cells

The α4/β7 integrin is a phenotypic marker of memory T lymphocytes that preferentially migrate through the gut (ie, gut-homing memory T cells). Phenotypically discrete subsets of human gut-homing memory T cells have been identified, including pro-inflammatory TH17 and anti-inflammatory T regulatory (Treg) cells. The activity of these subsets may influence human gastrointestinal homeostasis and disease. Vedolizumab is an investigational humanized monoclonal antibody which binds to the α4/β7 integrin and is being developed for ulcerative colitis (UC) and Crohn's disease (CD). We therefore investigated if vedolizumab modulated the activity of human Treg cells. Total (CD4+CD25+CD127lowFoxP3+) and gut-homing (α4β7highCD4+CD25+CD127lowFoxP3+) populations of Treg cells were identified by flow cytometry in whole blood samples from healthy human volunteers (n = 8). Both populations were subsequently isolated to >95% purity from whole blood by immunomagnetic separation and fluorescence-activated cell sorting. Purified human Treg cells were activated by stimulation with anti-CD2, -CD3 and -CD28 beads, and functional activity was assessed by co-culturing with responder T cells, activated by prior stimulation with phytohemagglutinin or anti-CD3/CD28 beads. Proliferation of responder cells was measured by flow cytometry. Potential effects of vedolizumab were assessed by co-culture of Treg and responder cells with saturating concentrations of vedolizumab. We identified a subset of gut-homing Treg cells which comprise ˜5% of the total gut-homing memory T cell population found in peripheral blood. We isolated these cells and demonstrated that they exhibit suppressive activity that is typical of Treg cells in vitro. Specifically, co-culture of activated responder T cells with the total Treg population, or the gut-homing Treg subset, inhibited proliferation of responder T cells (ie, suppression of pro-inflammatory activity by Treg). This suppressive activity was not affected by exposure to vedolizumab. Incubation of the total Treg population, or the gut-homing Treg subset, with saturating exposures of vedolizumab did not affect the suppression of responder T cells, as compared to vehicle control or an isotype control antibody. There was no effect of vedolizumab on the suppressive activity of the total Treg population or the gut-homing subset of this population found in peripheral blood of healthy volunteers. These data indicate that vedolizumab does not affect potential anti-inflammatory activity of human Treg cells residing in the submucosa.

Vaccinelike and Prophylactic Treatments of EAE with Novel I-Domain Antigen Conjugates (IDAC): Targeting Multiple Antigenic Peptides to APC

The objective of this work is to utilize novel I-domain antigenic-peptide conjugates (IDAC) for targeting antigenic peptides to antigen-presenting cells (APC) to simulate tolerance in experimental autoimmune encephalomyelitis (EAE). IDAC-1 and IDAC-3 molecules are conjugates between the I-domain protein and PLP-Cys and Ac-PLP-Cys-NH(2) peptides, respectively, tethered to N-terminus and Lys residues on the I-domain. The hypothesis is that the I-domain protein binds to ICAM-1 and PLP peptide binds to MHC-II on the surface of APC; this binding event inhibits the formation of the immunological synapse at the APC-T-cell interface to alter T-cell differentiation from inflammatory to regulatory phenotypes. Conjugation of peptides to the I-domain did not change the secondary structure of IDAC molecules as determined by circular dichroism spectroscopy. The efficacies of IDAC-1 and -3 were evaluated in EAE mice by administering iv or sc injections of IDAC in a prophylactic or a vaccinelike dosing schedule. IDAC-3 was better than IDAC-1 in suppressing and delaying the onset of EAE when delivered in prophylactic and vaccinelike manners. IDAC-3 also suppressed subsequent relapse of the disease. The production of IL-17 was lowered in the IDAC-3-treated mice compared to those treated with PBS. In contrast, the production of IL-10 was increased, suggesting that there is a shift from inflammatory to regulatory T-cell populations in IDAC-3-treated mice. In conclusion, the I-domain can effectively deliver antigenic peptides in a vaccinelike or prophylactic manner for inducing immunotolerance in the EAE mouse model.

Trichinella spiralis Infection Suppressed Gut Inflammation with CD4+CD25+Foxp3+T Cell Recruitment

In order to know the effect of pre-existing Trichinella spiralis infection on experimentally induced intestinal inflammation and immune responses, we induced colitis in T. spiralis-infected mice and observed the severity of colitis and the levels of Th1, Th2, and regulatory cytokines and recruitment of CD4+CD25+Foxp3+ T (regulatory T; Treg) cells. Female C57BL/6 mice were infected with 250 muscle larvae; after 4 weeks, induction of experimental colitis was performed using 3% dextran sulfate sodium (DSS). During the induction period, we observed severity of colitis, including weight loss and status of stool, and evaluated the disease activity index (DAI). A significantly low DAI and degree of weight loss were observed in infected mice, compared with uninfected mice. In addition, colon length in infected mice was not contracted, compared with uninfected mice. We also observed a significant increase in production of pro-inflammatory cytokines, IL-6 and IFN-γ, in spleen lymphocytes treated with DSS; however, such an increase was not observed in infected mice treated with DSS. Of particular interest, production of regulatory cytokines, IL-10 and transforming growth factor (TGF)-β, in spleen lymphocytes showed a significant increase in mice infected with T. spiralis. A similar result was observed in mesenteric lymph nodes (MLN). Subsets of the population of Treg cells in MLN and spleen showed significant increases in mice infected with T. spiralis. In conclusion, T. spiralis infection can inhibit the DSS-induced colitis in mice by enhancing the regulatory cytokine and Treg cells recruitment.