CD4+ Tregs and immune control

Cytotoxic T-Cells in Peripheral Blood in Women with Endometriosis

Aim: The etiology of endometriosis remains unknown, but increasing evidence suggests that immune regulation may be important. Our study aimed to evaluate peripheral blood lymphocyte subpopulations during the menstrual cycle in women with peritoneal and ovarian endometriosis relative to healthy women. Methods: In this study, 65 women with endometriosis (37 in the follicular phase and 28 in the luteal phase of the menstrual cycle) and 61 healthy women (33 in the follicular phase and 28 in the luteal phase) were enrolled. Flow cytometric analysis measured peripheral blood lymphocyte subpopulations. The serum levels of cortisol were also determined. Results: In healthy controls, we detected an increased concentration of cytotoxic (CD8⁺) T cells and activated (HLA-DR) T cells in the luteal phase compared with the follicular phase of the menstrual cycle (p = 0.020 and p = 0.045), whereas no such fluctuation was detected in endometriosis. However, a marked increase in regulatory T-cell concentration in the luteal phase was detected only in endometriosis patients (p = 0.005). Women with endometriosis had higher levels of serum cortisol (p = 0.022), which correlated with the concentration of regulatory T cells (p = 0.048). Conclusions: Women with endometriosis do not exhibit fluctuations in the concentrations of cytotoxic and activated peripheral blood lymphocytes during the menstrual cycle. The marked fluctuation of regulatory T cells detected in endometriosis could be attributed to altered immune response.

Dendritic-cell-based therapeutic cancer vaccines

The past decade has seen tremendous developments in novel cancer therapies through the targeting of tumor-cell-intrinsic pathways whose activity is linked to genetic alterations and the targeting of tumor-cell-extrinsic factors, such as growth factors. Furthermore, immunotherapies are entering the clinic at an unprecedented speed after the demonstration that T cells can efficiently reject tumors and that their antitumor activity can be enhanced with antibodies against immune-regulatory molecules (checkpoint blockade). Current immunotherapy strategies include monoclonal antibodies against tumor cells or immune-regulatory molecules, cell-based therapies such as adoptive transfer of ex-vivo-activated T cells and natural killer cells, and cancer vaccines. Herein, we discuss the immunological basis for therapeutic cancer vaccines and how the current understanding of dendritic cell and T cell biology might enable the development of next-generation curative therapies for individuals with cancer.

The majority of HIV type 1 DNA in circulating CD4+ T lymphocytes is present in non-gut-homing resting memory CD4+ T cells

Memory CD4(+) T lymphocytes in peripheral blood that express integrins α4ß7 preferentially recirculate through gut-associated lymphoid tissue (GALT), a proposed site of significant HIV-1 replication. Tregs and activated CD4(+) T cells in GALT could also be particularly susceptible to infection. We therefore hypothesized that infection of these subsets of memory CD4(+) T cells may contribute disproportionately to the HIV-1 reservoir. A cross-sectional study of CD4(+) T cell subsets of memory CD45RO(+) cells in peripheral blood mononuclear cells (PBMCs) was conducted using leukapheresis from eight subjects with untreated chronic HIV-1 infection. Real-time polymerase chain reaction (PCR) was used to quantify total and integrated HIV-1 DNA levels from memory CD4(+) T cells sorted into integrin β7(+) vs. β7(-), CD25(+)CD127(low) Treg vs. CD127(high), and activated CD38(+) vs. CD38(-). More than 80% of total HIV-1 DNA was found to reside in the integrin β7-negative non-gut-homing subset of CD45RO(+) memory CD4(+) T cells. Less than 10% was found in highly purified Tregs or CD38(+) activated memory cells. Similarly, integrated HIV-1 DNA copies were found to be more abundant in resting non-gut-homing memory CD4(+) T cells (76%) than in their activated counterparts (23%). Our investigations showed that the majority of both total and integrated HIV-1 DNA was found within non-gut-homing resting CD4(+) T cells.

FOXP3 expression and nodal metastasis of breast cancer

PURPOSE

T regulatory cells, a subset of T lymphocytes, function to suppress immune responses. FOXP3, a member of the forkhead family of transcription factors, is a good marker for T regulatory cells. Since sentinel nodes are important sites of immunomodulation in breast cancer, we studied the association between T regulatory cells and nodal metastasis using FOXP3 expression in sentinel nodes with and without metastatic breast carcinoma.

METHODS

Following sample size calculations, we selected 140 sentinel nodes from breast cancer patients; 70 with metastasis (sentinel node+) and 70 without metastasis (sentinel node-). FOXP3 expression in sentinel nodes was studied by immunohistochemistry. Cortical cells expressing FOXP3 were counted in 10 high power fields.

RESULTS

In the evaluable cases, the node positive (n = 66) and negative (n = 69) groups were well balanced for all clinicopathological parameters except histological type. The mean number of T regulatory cells expressing FOXP3 (per 10 hpf) was 139 in the node positive and 132 in the node negative group (P = 0.540). The mean number of T regulatory cells was 162 in patients ≤35 years of age (n = 8) compared to 133 in older patients (P = 0.250). Primary tumor pathological characteristics like tumor type, grade, size, and ER, PR, and HER2 status did not correlate with FOXP3 expression.

CONCLUSIONS

The number of FOXP3-expressing T regulatory cells does not differ significantly between sentinel node+ and sentinel node- samples. It was also not affected by primary tumor characteristics like tumor type, grade, size, hormone receptor, and HER2 status.

DNA vaccines targeting human papillomavirus-associated diseases: progresses in animal and clinical studies

Human papillomavirus (HPV) infection is a major cause of cervical cancer and its precancerous diseases. Cervical cancer is the second deadliest cancer killer among women worldwide. Moreover, HPV is also known to be a causative agent of oral, pharyngeal, anal and genital cancer. Recent application of HPV structural protein (L1)-targeted prophylactic vaccines (Gardasil® and Cervarix®) is expected to reduce the incidence of HPV infection and cervical cancer, and possibly other HPV-associated cancers. However, the benefit of the prophylactic vaccines for treating HPV-infected patients is unlikely, underscoring the importance of developing therapeutic vaccines against HPV infection. In this regard, numerous types of therapeutic vaccine approaches targeting the HPV regulatory proteins, E6 and E7, have been tested for their efficacy in animals and clinically. In this communication, we review HPV vaccine types, in particular DNA vaccines, their designs and delivery by electroporation and their immunologic and antitumor efficacy in animals and humans, along with the basics of HPV and its pathogenesis.

Impairment of regulatory T-cell function in autoimmune thyroid disease

BACKGROUND

Autoimmune thyroid disease (AITD) pathogenesis may result from a loss of immune tolerance to thyroid antigens. Regulatory T cells (Tregs) control immune responses, prevent excessive inflammation, and may be dysfunctional in AITD. We investigated the role of Tregs in Hashimoto's thyroiditis (HT) and Graves' disease (GD), complicated by Down syndrome (DS). Our goal was to identify differences in CD4(+)CD25(high) Treg function or number in patients with GD and HT, compared to healthy controls (HC).

METHODS

Treg number was assessed by flow cytometric analysis in samples from 20 AITD patients (seven GD, 13 HT), nine HC, and seven individuals with DS, a genetic disorder associated with multiple autoimmune disorders including AITD. Treg function was assessed by the inhibition of proliferation (radioactive thymidine incorporation into DNA) of blood-derived T effector (Teff) cells by Tregs in a coculture. Various methods of stimulation were contrasted. Cytokine levels were determined in conditioned media from the co-cultures.

RESULTS

No differences were found in the frequency of Tregs as a percentage of CD4(+) cells between AITD and HC. AITD Tregs were less capable of inhibiting the proliferation of Teff cells when compared to HC; however, the impairment was dependent on the type of stimulation used. DS patients without AITD exhibited normal Treg function. We observed few differences in cytokine production between HC and AITD patients.

CONCLUSIONS

Tregs from AITD patients are partly dysfunctional, possibly explaining their autoimmunity. Future work will elucidate the diagnostic potential and pathophysiology of Tregs in AITD.

Schedule-dependent therapeutic efficacy of L19mTNF-α and melphalan combined with gemcitabine

L19-tumor necrosis factor alpha (L19mTNF-α; L), a fusion protein consisting of mouse TNFα and the human antibody fragment L19 directed to the extra domain-B (ED-B) of fibronectin, is able to selectively target tumor vasculature and to exert a long-lasting therapeutic activity in combination with melphalan (M) in syngeneic mouse tumor models. We have studied the antitumor activity of single L19mTNF-α treatment in combination with melphalan and gemcitabine (G) using different administration protocols in two histologically different murine tumor models: WEHI-164 fibrosarcoma and K7M2 osteosarcoma. All responding mice showed significant reduction in myeloid-derived suppressor cells (MDSCs) and an increase in CD4⁺ and CD8⁺ T cells in the tumor infiltrates, as well as significant reduction in regulatory T cells (Treg) at the level of draining lymph nodes. What is important is that all cured mice rejected tumor challenge up to 1 year after therapy. Targeted delivery of L19mTNF-α synergistically increases the antitumor activity of melphalan and gemcitabine, but optimal administration schedules are required. This study provides information for designing clinical studies using L19mTNF-α in combination with chemotherapeutic drugs.

Targeted delivery of L19mTNF-α synergistically increases the antitumor activity of melphalan and gemcitabine, but optimal administration schedule requires a pretreatment with L19mTNF-α otherwise an antagonistic effect could occur. This study provides information for designing clinical studies using L19mTNF-α in combination with chemotherapeutic drugs.

A bystander cell-based GM-CSF secreting vaccine synergized with a low dose of cyclophosphamide presents therapeutic immune responses against murine hepatocellular carcinoma

Granulocyte-macrophage colony-stimulating factor (GM-CSF) secreting cellular tumor vaccines contribute to the induction of potent antitumor immune responses in murine models and patients suffering from cancers. Hepatocellular carcinoma (HCC) is one of the most frequent and malignant cancers in China. We describe, for the first time, a GM-CSF releasing vaccine strategy that represents a step toward combating this type of cancer. In this study, a bystander cell-based GM-CSF secreting vaccine against murine HCC, Hepa1-6/B78H1-GM-CSF, was co-administered with a low dose of cyclophosphamide (CY). After challenging with tumor and vaccination, immunological assays demonstrated that the cellular antitumor immune responses were efficiently activated and that tumor development was significantly retarded, which was dependent on synergy with CY. The promising outcome of the anti-HCC vaccine in the murine model demonstrates the feasibility of a future clinical application for this treatment in HCC patients.

Multifaceted roles of PGE2 in inflammation and cancer

Prostaglandin E(2) (PGE(2)) is a bioactive lipid that elicits a wide range of biological effects associated with inflammation and cancer. PGE(2) exerts diverse effects on cell proliferation, apoptosis, angiogenesis, inflammation, and immune surveillance. This review concentrates primarily on gastrointestinal cancers, where the actions of PGE(2) are most prominent, most likely due to the constant exposure to dietary and environmental insults and the intrinsic role of PGE(2) in tissue homeostasis. A discussion of recent efforts to elucidate the complex and interconnected pathways that link PGE(2) signaling with inflammation and cancer is provided, supported by the abundant literature showing a protective effect of NSAIDs and the therapeutic efficacy of targeting mPGES-1 or EP receptors for cancer prevention. However, suppressing PGE(2) formation as a means of providing chemoprotection against all cancers may not ultimately be tenable, undoubtedly the situation for patients with inflammatory bowel disease. Future studies to fully understand the complex role of PGE(2) in both inflammation and cancer will be required to develop novel strategies for cancer prevention that are both effective and safe.

In vitro restoration of Th17 response during HIV infection with an antiretroviral drug and Th17 differentiation cytokines

The Th17 subset is preferentially depleted as compared to the Th1 subset in chronically HIV-infected patients, even after successful antiretroviral therapy. In this study, we have established an in vitro system utilizing primary human CD4 T cell cultures that recapitulates the dramatic loss of Th17 response upon HIV-1 infection that is accompanied with a less profound Th1 decrease. With this experimental system, we showed that blocking viral entry with CCR5 ligands or TAK779 reduced the infection and enhanced Th17 response but not Th1 response. Antiretroviral drug 3TC (lamivudine), given at the time of infection, completely prevented the loss of Th17 and Th1 responses but was ineffective when given after infection was already established. Only when Th17 differentiation cytokines were given along with 3TC to the cultures with established HIV infection was Th17 response fully restored and virus replication kept suppressed. Finally, a significant increase of Th17 response was achieved in peripheral lymphocytes of HIV-infected patients on antiretroviral therapy after treatment with Th17 differentiation cytokines. These data demonstrate the presence of CD4 T cells remaining capable of mounting Th17 response during HIV infection and indicate the potential use of immunotherapeutic modalities to supplement antiretroviral drugs for restoring Th17 response in chronically HIV-infected patients.

Cellular constituents of immune escape within the tumor microenvironment

Established tumors are complex masses that contain not only neoplastic cells but also nontransformed cellular elements such as stromal cells, the neovasculature, and the full gamut of immune cells. However, evidence suggests that, unlike cells found in lymphoid organs that productively respond to acute infections, immune cells in tumors are dysregulated and functionally impaired. Tumor masses can contain regulatory lymphocytes, myeloid-derived suppressor cells, alternatively activated macrophages, and dendritic cells. Ablation or reprogramming of this aberrant microenvironment might dramatically augment cancer therapies, and this strategy is currently being deployed in a variety of clinical trials. A better understanding of the cellular constituents of tumors and the mechanisms involved in immune evasion may help guide the next generation of innovative cancer immunotherapies.

Persistent inflammation and immunosuppression: a common syndrome and new horizon for surgical intensive care

Surgical intensive care unit (ICU) stay of longer than 10 days is often described by the experienced intensivist as a "complicated clinical course" and is frequently attributed to persistent immune dysfunction. "Systemic inflammatory response syndrome" (SIRS) followed by "compensatory anti-inflammatory response syndrome" (CARS) is a conceptual framework to explain the immunologic trajectory that ICU patients with severe sepsis, trauma, or emergency surgery for abdominal infection often traverse, but the causes, mechanisms, and reasons for persistent immune dysfunction remain unexplained. Often involving multiple-organ failure (MOF) and death, improvements in surgical intensive care have altered its incidence, phenotype, and frequency and have increased the number of patients who survive initial sepsis or surgical events and progress to a persistent inflammation, immunosuppression, and catabolism syndrome (PICS). Often observed, but rarely reversible, these patients may survive to transfer to a long-term care facility only to return to the ICU, but rarely to self-sufficiency. We propose that PICS is the dominant pathophysiology and phenotype that has replaced late MOF and prolongs surgical ICU stay, usually with poor outcome. This review details the evolving epidemiology of MOF, the clinical presentation of PICS, and our understanding of how persistent inflammation and immunosuppression define the pathobiology of prolonged intensive care. Therapy for PICS will involve innovative interventions for immune system rebalance and nutritional support to regain physical function and well-being.

CD4+CD25highCD127low regulatory T cells in peripheral blood are not an independent factor for chronic graft-versus-host disease after allogeneic stem cell transplantation

Background. The therapeutic efficacy of allogeneic hemopoietic stem cell transplantation (HSCT) largely relies on the graft-versus-leukemia (GVL) effect. Uncontrolled graft-versus-host disease (GVHD) is a feared complication of HSCT. Regulatory T cells (Treg) are a subset of CD4+ T-helper cells believed to maintain tolerance after HSCT. It remains unclear whether low peripheral blood Treg have an impact on the risk for acute (aGVHD) and chronic GVHD (cGVHD). Methods. In this paper we enumerated the CD4+CD25highCD127low Treg in the peripheral blood of 84 patients after at least 150 days from HSCT and in 20 healthy age-matched controls. Results. Although similar mean lymphocyte counts were found in patients and controls, CD3+CD4+ T-cell counts were significantly lower in patients. Patients also had significantly lower Treg percentages among lymphocytes as compared to controls. Patients with cGVHD had even higher percentages of Treg if compared to patients without cGVHD. In multivariate analysis, Treg percentages were not an independent factor for cGVHD. Conclusions. This paper did not show a relation between deficient peripheral blood Treg and cGVHD, therefore cGVHD does not seem to occur as a result of peripheral Treg paucity.

Chronically HIV-1 Infected Patients Exhibit Low Frequencies of CD25+ Regulatory T Cells

The characterization of regulatory T cells (Treg) during HIV infection has become of particular interest considering their potential role in the pathogenesis of the acquired immunodeficiency syndrome. Different reports on Tregs in HIV-infected patients vary greatly, depending on the state of disease progression, anatomical compartment, and the phenotypic markers used to define this cell subpopulation. To determine the frequency of Tregs we included paired samples from peripheral blood and rectal biopsies from controls and chronic HIV patients with or without detectable viral load. Tregs were determined by flow cytometry using three different protocols: CD4⁺Foxp3⁺; CD4⁺Foxp3⁺CD127^Low/-, and CD4⁺CD25⁺CD127^Low/-. In addition, and with the purpose to compare the different protocols we also characterized Tregs in peripheral blood of HIV negative individuals with influenza like symptoms. Here, we report that Treg characterization in HIV-infected patients as CD4⁺Foxp3⁺ and CD4⁺Foxp3⁺CD127^Low/- cells was similar, indicating that both protocols represent a suitable method to determine the frequency of Tregs in peripheral blood mononuclear cells (PBMC) and gut associated lymphoid tissue (GALT). In contrast, in HIV but not in flu-like patients, detection of Tregs as CD4⁺CD25⁺CD127^Low/- cells resulted in a significantly lower percentage of these cells. In both, HIV patients and controls the frequency of Treg was significantly higher in GALT compared to PBMC. The frequency of Tregs in PBMC and GALT using CD4⁺Foxp3⁺ and CD4⁺Foxp3⁺CD127^Low/- was higher in HIV patients than in controls. Similarly, the frequency of Treg using any protocol was higher in flu-like patients compared to controls. The results suggest that relying on the expression of CD25 could be unsuitable to characterize Tregs in PBMC and GALT samples from a chronic infection such as HIV.

Immune interactions in endometriosis

Endometriosis is a common, complex gynecologic disorder characterized by the presence of endometrial glands and stroma at extrauterine (ectopic) sites. In women who develop this disease, alterations in specific biological processes involving both the endocrine and immune systems have been observed, which may explain the survival and growth of displaced endometrial tissue in affected women. In the past decade, a considerable amount of research has implicated a role for alterations in progesterone action at both eutopic and ectopic sites of endometrial growth which may contribute to the excessive inflammation associated with progression of endometriosis; however, it remains unclear whether these anomalies induce the condition or are simply a consequence of the disease process. In this article, we summarize current knowledge of alterations within the immune system of endometriosis patients and discuss how endometrial cells from women with this disease not only have the capacity to escape immunosurveillance, but also use inflammatory mechanisms to promote their growth within the peritoneal cavity. Finally, we discuss evidence that exposure to an environmental endocrine disruptor, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, can mediate the development of an endometrial phenotype that exhibits both reduced progesterone responsiveness and hypersensitivity to proinflammatory stimuli mimicking the endometriosis phenotype. Future studies in women with endometriosis should consider whether a heightened inflammatory response within the peritoneal microenvironment contributes to the development and persistence of this disease.

VIP Regulates the Development & Proliferation of Treg in vivo in spleen

BACKGROUND

Mounting evidence supports a key role for VIP as an anti-inflammatory agent and promoter of immune tolerance. It suppresses TNF-α and other inflammatory cytokines and chemokines, upregulates anti-inflammatory IL-10, and promotes immune tolerant cells called T regulatory (Treg) cells. VIP KO mice have recently been demonstrated to have spontaneous airway and pulmonary perivascular inflammatory responses, as part of asthma-like and pulmonary hypertension phenotypes, respectively. Both inflammatory responses are correctable with VIP. Focusing on this model, we have now investigated the influence of VIP not only on inflammatory cells but also on Treg cells.

METHODS

Using flow cytometric analysis, we examined the relative preponderance of CD25+CD4+ cells and anti-inflammatory Treg cells, in extracts of thymus and spleen from VIP KO mice (5 VIP KO; 5 VIP KO+ VIP; 10 wild-type). This method allowed antibody-based flow cytometric identification of Treg cells using surface markers CD25 and CD4, along with the: 1) intracellular activation marker FoxP3; and 2) Helios, which distinguishes cells of thymic versus splenic derivation.

CONCLUSIONS

Deletion of the VIP gene results in: 1) CD25+CD4- cell accumulation in the thymus, which is corrected by VIP treatment; 2) more Treg in thymus lacking Foxp3 expression, suggesting VIP is necessary for immune tolerance; and, 3) a tendency towards deficiency of Treg cells in the spleen, which is normalized by VIP treatment. Treg lacking Helios are induced by VIP intrasplenically rather than by migration from the thymus. These results confirm the dual role of VIP as an anti-inflammatory and immune tolerance-promoting agent.

Manipulating Immune Tolerance with Micro-RNA Regulated Gene Therapy

The success of in vivo gene therapy greatly depends on the ability to control the immune response toward the therapeutic transgene. Over the last decade several vector-based and pharmacological approaches have been explored to control the immune-mediated clearance of transgene-expressing cells after viral delivery. One important outcome from these studies is the concept that expression of a transgene in tolerance-promoting organs, such as the liver and tolerogenic antigen-presenting cells, can help safeguard transgene-expressing cells from immune-mediated clearance. Gene therapists are now manipulating vectors to target naturally occurring tolerogenic properties of the body by: (i) incorporating tissue/cell specific promoters for targeted expression, (ii) using viral-capsid engineering to alter tropism and avoid pre-existing immunity, and (iii) regulating cell and activation dependent expression by including micro-RNA (miR) targets into expression cassettes. The combination of these three layers of vector regulation greatly enhances the targeting of tolerogenic cells and limits off-target expression of the transgene, which can lead to the induction of transgene-specific pathogenic effector T cells. In this review, we discuss the application of using miR transgene regulation to generate tolerogenic responses and speculate on possible mechanisms used by the liver to induce the transgene-specific regulatory T cells.

Upregulated expression of indoleamine 2, 3-dioxygenase in primary breast cancer correlates with increase of infiltrated regulatory T cells in situ and lymph node metastasis

IDO has been reported to induce immunotolerance and promote metastasis in solid malignancy, but the mechanisms involved were not fully understood. In this study, the expression of IDO in primary breast cancer was examined and the correlation between the expression levels of IDO and the densities of Foxp3⁺ Tregs in situ was studied. The IDO stably-expressing CHO cells(IDO/CHO) were generated to evaluate the induction of Foxp3⁺ Tregs after coculturing with CD3⁺ T cells in vitro. The IDO expression in cancer was higher than that in benign diseases both at RNA and protein levels. The IDO expression was significantly upregulated in tumors of more advanced stages and with more extensive lymph node metastasis, and displayed positive linear correlation with the density of Foxp3⁺ Tregs. We further demonstrated that CD4⁺CD25⁺CD127⁻ Tregs could be amplified by coculturing CD3⁺ T cells with IDO/CHO cells in vitro which displayed increasing Foxp3 expression both at mRNA and protein levels. Our results implied that up-regulation of IDO in primary breast cancer may inhibit local immune surveillance and promote metastasis by favoring development and infiltration of Foxp3⁺ Tregs in the tumor microenvironment.

Lenalidomide-Associated ITP

Lenalidomide is a potent immunomodulatory agent being used increasingly for treatment of hematologic malignancies including multiple myeloma and myelodysplasia. The common toxicities of lenalidomide, including dose-limiting myelosuppression, are well described. However, the immunomodulatory properties of lenalidomide may give rise to unexpected autoimmune complications. Herein, we describe a case of immune thrombocytopenic purpura (ITP) associated with use of lenalidomide.

Pulmonary and systemic inflammatory responses to intra-amniotic IL-1α in fetal sheep

Clinical and epidemiological studies implicate IL-1 as an important mediator of perinatal inflammation. We tested the hypothesis that intra-amniotic IL-1α would induce pulmonary and systemic fetal inflammatory responses. Sheep with singleton fetuses were given an intra-amniotic injection of recombinant sheep IL-1α (100 μg) and were delivered 1, 3, or 7 days later, at 124 ± 1 days gestation (n=5-8/group). A separate group of sheep were given two intra-amniotic IL-1α injections (100 μg dose each): 7 days and again 1 day prior to delivery. IL-1α induced a robust increase in monocytes, neutrophils, lymphocytes, and IL-8 protein in bronchoalveolar lavage fluid. H(2)O(2) secretion was increased in inflammatory cells isolated from lungs of IL-1α-exposed lambs upon LPS challenge in vitro compared with control monocytes. T lymphocytes were recruited to the lung. IL-1β, cyclooxygenase-1, and cyclooxygenase-2 mRNA expression increased in the lung 1 day after intra-amniotic IL-1α exposure. Lung volumes increased 7 days after intra-amniotic IL-1α exposure, with minimal anatomic changes in air space morphology. The weight of the posterior mediastinal lymph node draining the lung and the gastrointestinal tract doubled, inducible nitric oxide synthase (NOSII)-positive cells increased, and Foxp3-positive T-regulatory lymphocytes decreased in the lymph node after IL-1α exposure. In the blood, neutrophil counts and plasma haptoglobin increased after IL-1α exposure. Compared with a single exposure, exposure to intra-amniotic IL-1α 7 days and again 1 day before delivery had a variable effect (increases in some inflammatory markers, but not pulmonary cytokines). IL-1α is a potent mediator of the fetal inflammatory response syndrome.

Immune regulation in Chandipura virus infection: characterization of CD4+ T regulatory cells from infected mice

BACKGROUND

Chandipura virus produces acute infection in mice. During infection drastic reduction of CD4+, CD8+ and CD19 + cell was noticed. Depletion of lymphocytes also noticed in spleen. The reduction may be due to the regulatory mechanism of immune system to prevent the bystander host tissue injury. There are several mechanisms like generation of regulatory cells, activation induced cell death (ACID) etc were indicated to control the activation and maintain cellular homeostasis. Role of regulatory cells in homeostasis has been described in several viral diseases. This study was undertaken to characterize CD4+T regulatory cells from the infected mice.

METHOD

In this study we purified the CD4+ T cells from Chandipura virus infected susceptible Balb/c mice. CD4+ T regulatory cells were identified by expression of cell surface markers CD25, CD127 and CTLA-4 and intracellular markers Foxp3, IL-10 and TGF-beta. Antigen specificity and ability to suppress the proliferation of other lymphocytes were studied in vitro by purified CD4+CD25+T regulatory cells from infected mice. The proliferation was calculated by proliferation module of Flow Jo software. Expression of death receptors on regulatory cells were studied by flowcytometer.

RESULTS

The CD4+ T cells isolated from infected mice expressed characteristic markers of regulatory phenotype at all post infective hours tested. The CD4+ T regulatory cells were proliferated when stimulated with Chandipura virus antigen. The regulatory cells did not suppress the proliferation of splenocytes stimulated with anti CD3 antibody when co cultured with them. Interesting observation was, while purification of CD4+ T cells by negative selection, the population of cells negative for CD4 also co purified along with CD4+ T cell. Flow cytometry analysis and light microscopy revealed that CD4 negative cells were of different size and shape (atypical) compared to the normal lymphocytes. Greater percentage of these atypical lymphocytes expressed Fas Ligand and Programmed Death1 (PD-1) receptor.

CONCLUSION

From these results we concluded that virus specific CD4+T regulatory cells are generated during Chandipura virus infection in mice and these cells might control the activated lymphocytes during infection by different mechanism.

Efficacy of rabbit anti-thymocyte globulin in severe aplastic anemia

BACKGROUND

A combination of horse anti-thymocyte globulin and cyclosporine produces responses in 60-70% of patients with severe aplastic anemia. We performed a phase II study of rabbit anti-thymocyte globulin and cyclosporine as first-line therapy for severe aplastic anemia.

DESIGN AND METHODS

Twenty patients with severe aplastic anemia treated with rabbit anti-thymocyte globulin were compared to 67 historical control cases with matched clinical characteristics treated with horse anti-thymocyte globulin.

RESULTS

Response rates at 3, 6 and 12 months were similar for patients treated with rabbit anti-thymocyte globulin or horse anti-thymocyte globulin: 40% versus 55% (P=0.43), 45% versus 58% (P=0.44) and 50% versus 58% (P=0.61), respectively. No differences in early mortality rates or overall survival were observed. We then performed multivariable analyses of response at 6 months and overall survival and identified the presence of a paroxysmal nocturnal hemoglobinuria clone (P=0.01) and a pretreatment absolute reticulocyte count greater than 30×10(9)/L (P=0.007) as independent predictors of response and younger age (P=0.003), higher pretreatment absolute neutrophil (P=0.02) and absolute lymphocyte counts (P=0.03) as independent predictors of overall survival. None of the immunogenetic polymorphisms studied was predictive of response to immunosupressive therapy.

CONCLUSIONS

Despite reports suggesting differences in biological activity of different anti-thymocyte globulin preparations, rabbit and horse anti-thymocyte globulin appear to have a similar efficacy for up-front treatment of severe aplastic anemia. Clinicaltrial.gov: NCT01231841).

T-cell responses in two unrelated hemophilia A inhibitor subjects include an epitope at the factor VIII R593C missense site

BACKGROUND

Development of neutralizing anti-factor (F)VIII antibodies ('inhibitors') is a serious clinical problem in hemophilia A. Increased inhibitor risk has been associated with certain FVIII missense substitutions, including R593C in the A2 domain.

OBJECTIVES

The aim of the present study was to identify T-cell epitopes in FVIII and characterize T-cell responses in two unrelated hemophilia A subjects sharing F8-R593C and HLA-DRB1*1101 genotypes. We hypothesized that the hemophilic substitution site coincides with an important T-cell epitope.

PATIENTS/METHODS

The binding affinities of peptides for recombinant HLA-DR proteins were measured and compared with epitope prediction results. CD4+ T cells were stimulated using peptides and stained with fluorescent, peptide-loaded tetramers.

RESULTS

The inhibitor subjects, but not HLA-matched controls, had high-avidity HLA-DRB1*1101-restricted T-cell responses against FVIII(589-608), which contains the hemophilic missense site. Antigen-specific T cells secreted Th1 and Th2 cytokines and proliferated in response to FVIII and FVIII(592-603). FVIII(589-608) bound with physiologically relevant (micromolar) IC(50) values to recombinant DR0101, DR1101 and DR1501 proteins.

CONCLUSIONS

Hemophilia A patients with R593C missense substitutions and these HLA haplotypes had an increased incidence of inhibitors in our cohorts, supporting a paradigm in which presentation of FVIII epitopes containing the wild-type R593 influences inhibitor risk in this hemophilia A sub-population.

Dendritic cells and immunity against cancer

T cells can reject established tumours when adoptively transferred into patients, thereby demonstrating the power of the immune system for cancer therapy. However, it has proven difficult to maintain adoptively transferred T cells in the long term. Vaccines have the potential to induce tumour-specific effector and memory T cells. However, clinical efficacy of current vaccines is limited, possibly because tumours skew the immune system by means of myeloid-derived suppressor cells, inflammatory type 2 T cells and regulatory T cells (Tregs), all of which prevent the generation of effector cells. To improve the clinical efficacy of cancer vaccines in patients with metastatic disease, we need to design novel and improved strategies that can boost adaptive immunity to cancer, help overcome Tregs and allow the breakdown of the immunosuppressive tumour microenvironment. This can be achieved by exploiting the fast increasing knowledge about the dendritic cell (DC) system, including the existence of distinct DC subsets that respond differentially to distinct activation signals, (functional plasticity), both contributing to the generation of unique adaptive immune responses. We foresee that these novel cancer vaccines will be used as monotherapy in patients with resected disease and in combination with drugs targeting regulatory/suppressor pathways in patients with metastatic disease.

Natural regulatory T cells in autoimmunity

The suppressive/immunomodulatory function of CD4(+)CD25(+)FOXP3(+) regulatory T (Treg) cells is crucial for the maintenance of immune homeostasis, which helps to prevent autoimmunity and reduce the inflammation induced by pathogens and environmental insults. This review summarizes the current knowledge on the types and mechanisms of action of Treg cells and their role in the immune tolerance to self-antigens, with a particular focus on naturally occurring Treg cells.

Regulatory T cells suppress antigen-driven CD4 T cell reactivity following injury

Injury initiates local and systemic host responses and is known to increase CD4 Treg activity in mice and humans. This study uses a TCR transgenic T cell adoptive transfer approach and in vivo Treg depletion to determine specifically the in vivo influence of Tregs on antigen-driven CD4 T cell reactivity following burn injury in mice. We report here that injury in the absence of recipient and donor Tregs promotes high antigen-driven CD4 T cell expansion and increases the level of CD4 T cell reactivity. In contrast, CD4 T cell expansion and reactivity were suppressed significantly in injured Treg-replete mice. In additional experiments, we found that APCs prepared from burn- or sham-injured, Treg-depleted mice displayed significantly higher antigen-presenting activity than APCs prepared from normal mice, suggesting that Tregs may suppress injury responses by controlling the intensity of APC activity. Taken together, these findings demonstrate that Tregs can actively control the in vivo expansion and reactivity of antigen-stimulated, naïve CD4 T cells following severe injury.

Follicular lymphoma prognostic factors in the modern era: what is clinically meaningful?

Follicular lymphomas (FL) account for 30% of non-Hodgkin's lymphomas (NHL). Their evolution is heterogeneous. Some patients present with indolent forms undergoing several relapses while in other patients the disease evolves abruptly toward aggressive NHL. This is why accurate prognostic indices are required so that treatment strategies may be optimized for each patient and so that trials may be conducted in groups of patients that are as homogeneous as possible. The Follicular Lymphoma International Prognostic Index (FLIPI) has been designed to separate patients into 3 groups with significantly different hazard ratios for death. Its accuracy has been confirmed in several studies. The FLIPI2 was designed more recently to separate patients with significantly different hazard ratios for progression/relapse in the era of anti-CD20 monoclonal antibody treatments. Gene profile studies have shown that the prognosis of FL is mainly related to the type, number, and activation of immune cells in the microenvironment of lymphomatous follicles. Immunohistochemical studies suggest that macrophages, CD4+ T cells and among them T-regulatory cells (T-regs) and programed death-1 cells (PD-1 cells) play a major role in the outcome of FLs. However, additional confirmatory studies are required due to discrepancies in results. Up to now, these biological study results are more useful for approaching the pathophysiology of FL rather than to be used as prognostic tools in clinical practice.

Interactions between lymphocytes and myeloid cells regulate pro- versus anti-tumor immunity

Tumor-associated myeloid cells have been implicated in regulating many of the “hallmarks of cancer” and thus fostering solid tumor development and metastasis. However, the same innate leukocytes also participate in anti-tumor immunity and restraint of malignant disease. While many factors regulate the propensity of myeloid cells to promote or repress cancerous growths, polarized adaptive immune responses by B and T lymphocytes have been identified as regulators of many aspects of myeloid cell biology by specifically regulating their functional capabilities. Here, we detail the diversity of heterogeneous B and T lymphocyte populations and their impacts on solid tumor development through their abilities to regulate myeloid cell function in solid tumors.

Effective depletion of regulatory T cells allows the recruitment of mesothelin-specific CD8 T cells to the antitumor immune response against a mesothelin-expressing mouse pancreatic adenocarcinoma

Vaccine-induced CD8(+) T-cell responses can eradicate developing tumors in vivo in mouse models. Translating these successes into approved treatments for cancer patients has been challenging, since many of these models lack expression of clinically proven/relevant tumor antigens. We have shown that mesothelin is a clinically relevant CD8(+) T-cell target in human pancreas cancer, which is also highly conserved among species. Here, we utilize the murine mesothelin-expressing pancreatic tumor model (Panc02) to identify the immune-relevant mesothelin-derived peptides and study interventions that enhance the antitumor response. We first screened overlapping peptides of the entire murine mesothelin protein to identify two new CD8(+) mesothelin-restricted epitopes. These peptides were then evaluated for recognition by vaccine-induced T cells from mice treated with vaccine in sequence with low-dose cyclophosphamide (CY) and an anti-CD25 IL-2Ralpha monoclonal antibody (PC61). These treatments are both known to deplete subpopulations of T regulatory cells (Tregs). Our findings demonstrate that combined Treg-depleting therapies synergize to enhance vaccine efficacy. Furthermore, our data supports mesothelin as a relevant antigen in murine and clinical models and the use of Panc02 as a clinically relevant murine model of pancreatic cancer for evaluating antigen-targeted immunotherapies in immune-tolerant hosts.

Immunotherapy for melanoma: current status and perspectives

Immunotherapy is an important modality in the therapy of patients with malignant melanoma. As our knowledge about this disease continues to expand, so does the immunotherapeutic armamentarium. Nevertheless, successful preclinical models do not always translate into clinically meaningful results. The authors give a comprehensive analysis of most recent advances in the immune anti-melanoma therapy, including interleukins, interferons, other cytokines, adoptive immunotherapy, biochemotherapy, as well as the use of different vaccines. We also present the fundamental concepts behind various immune enhancement strategies, passive immunotherapy, as well as the use of immune adjuvants. This review brings into discussion the results of newer and older clinical trials, as well as potential limitations and drawbacks seen with the utilization of various immune therapies in malignant melanoma. Development of novel therapeutic approaches, along with optimization of existing therapies, continues to hold a great promise in the field of melanoma therapy research. Use of anti-CTLA4 and anti-PD1 antibodies, realization of the importance of co-stimulatory signals, which translated into the use of agonist CD40 monoclonal antibodies, as well as activation of innate immunity through enhanced expression of co-stimulatory molecules on the surface of dendritic cells by TLR agonists are only a few items on the list of recent advances in the treatment of melanoma. The need to engineer better immune interactions and to boost positive feedback loops appear crucial for the future of melanoma therapy, which ultimately resides in our understanding of the complexity of immune responses in this disease.

Inhaled vasoactive intestinal peptide exerts immunoregulatory effects in sarcoidosis

RATIONALE

Previous studies suggest an important immunoregulatory role of vasoactive intestinal peptide (VIP) in experimental models of chronic noninfectious inflammation. Sarcoidosis is characterized by noncaseating epitheloid cell granulomas, where excessive tumor necrosis factor-alpha production by pulmonary macrophages plays a critical role in granuloma formation and disease progression, which may lead to fatal organ dysfunction.

OBJECTIVES

To test whether inhaled VIP has an immunoregulatory role. Sarcoid alveolitis was used as a prototype of immune-mediated chronic lung inflammation.

METHODS

In an open clinical phase II study, we treated 20 patients with histologically proved sarcoidosis and active disease with nebulized VIP for 4 weeks.

MEASUREMENTS AND MAIN RESULTS

VIP inhalation was safe, well-tolerated, and significantly reduced the production of tumor necrosis factor-alpha by cells isolated from bronchoalveolar lavage fluids of these patients. VIP treatment significantly increased the numbers of bronchoalveolar lavage CD4(+)CD127(-)CD25(+) T cells, which showed regulatory activities on conventional effector T cells. In vitro experiments demonstrated the capacity of VIP to convert naive CD4(+)CD25(-) T cells into CD4(+)CD25(+)FoxP3(+) regulatory T cells, suggesting the generation of peripheral regulatory T cells by VIP treatment.

CONCLUSIONS

This study is the first to show the immunoregulatory effect of VIP in humans, and supports the notion of inhaled VIP as an attractive future therapy to dampen exaggerated immune responses in lung disorders. Thus, the inhalation of neuropeptides may be developed into a new therapeutic principle for chronic inflammatory lung disorders in humans.

Designing the optimal vaccine: the importance of cytokines and dendritic cells

Many vaccines existing today provide strong protection against a wide variety of infectious organisms, and these consist of either live attenuated or inactivated microorganisms. Most of these vaccines were developed empirically and there has not been a clear understanding of the immunological principles that contribute to this success. Recent advances in systems biology are being applied to the study of vaccines in order to determine which immunological parameters are the best predictors of success. New approaches to vaccine development include the identification of peptide epitopes and the manipulation of the immune response to generate the most appropriate response. Vaccines are being developed to prevent and/or treat such conditions as cancer and autoimmunity in addition to infectious diseases. Vaccines targeting this diverse group of diseases may need to elicit very different types of immune responses. Recent advances in our understanding of the functions of dendritic cells (DC) and cytokines in orchestrating qualitatively different immune responses has allowed the design of vaccines that can elicit immune responses appropriate for cancer, autoimmunity or infectious organisms. This review will focus on recent advances in the ways DC and cytokines can be used to develop the most appropriate and effective vaccines.

CD46-induced human Treg enhance B-cell responses

Regulatory CD4(+) T cells (Treg) are important modulators of the immune response. Different types of Treg have been identified based on whether they are thymically derived (natural Treg) or induced in the periphery (adaptive Treg). We recently reported on an adaptive Treg phenotype that can be induced by the concomitant stimulation of human CD4(+) T cells through CD3 and the membrane complement regulator CD46. These complement (CD46)-induced regulatory T cells (cTreg) potently inhibit bystander T-cell proliferation through high-level secretion of IL-10. In addition, cTreg express granzyme B and exhibit cytotoxic effects toward activated effector T cells. Here, we analyzed the effect of cTreg on B-cell functions in a co-culture system. We found that cTreg enhance B-cell Ab production. This B-cell support is dependent on cell/cell contact as well as cTreg-derived IL-10. In addition, we show that T cells from a CD46-deficient patient are not capable of promoting B-cell responses, whereas CD46-deficient B cells have no intrinsic defect in Ig production. This finding may relate to a subset of CD46-deficient patients, who present with common variable immunodeficiency. Thus, the lack of cTreg function in optimizing B-cell responses could explain why some CD46-deficient patients develop common variable immunodeficiency.

The relationship between CD4+CD25+CD127- regulatory T cells and inflammatory response and outcome during shock states

Introduction

Although regulatory T lymphocytes (Tregs) have a pivotal role in preventing autoimmune diseases and limiting chronic inflammatory conditions, they may also block beneficial immune responses by preventing sterilizing immunity to certain pathogens.

Methods

To determine whether naturally occurring Treg cells have a role in inflammatory response and outcome during shock state we conducted an observational study in two adult ICUs from a university hospital. Within 12 hours of admission, peripheral whole blood was collected for the measurement of cytokines and determination of lymphocyte count. Sampling was repeated at day three, five and seven. Furthermore, an experimental septic shock was induced in adult Balb/c mice through caecal ligation and puncture.

Results

Forty-three patients suffering from shock (26 septic, 17 non septic), and 7 healthy volunteers were included. The percentage of Tregs increased as early as 3 days after the onset of shock, while their absolute number remained lower than in healthy volunteers. A similar pattern of Tregs kinetics was found in infected and non infected patients. Though there was an inverse correlation between severity scores and Tregs percentage, the time course of Tregs was similar between survivors and non survivors. No relation between Tregs and cytokine concentration was found. In septic mice, although there was a rapid increase in Treg cells subset among splenocytes, antibody-induced depletion of Tregs before the onset of sepsis did not alter survival.

Conclusions

These data argue against a determinant role of Tregs in inflammatory response and outcome during shock states.

The immunology of fibrosis: innate and adaptive responses

Fibrosis is an important health problem, and its pathogenetic principles are still largely unknown. It can develop either spontaneously, or, more frequently, as a consequence of various underlying diseases. Irrespective of the primary cause, however, fibrotic tissue is always infiltrated by mononuclear immune cells. In most instances the reason for the attraction of these cells to fibrotic tissue and their proliferation remains to be determined; however their cytokine profile shows clear-cut proinflammatory and profibrotic characteristics. In this review, we discuss the innate and adaptive immune reactions associated with the development of fibrosis and the molecular basis of the profibrotic mechanisms taking place in systemic sclerosis (scleroderma), arteriosclerosis and peri-silicone mammary implant fibrosis.

STAT3 signaling in CD4+ T cells is critical for the pathogenesis of chronic sclerodermatous graft-versus-host disease in a murine model

Donor CD4+ T cells are thought to be essential for inducing delayed host tissue injury in chronic graft-versus-host disease (GVHD). However, the relative contributions of distinct effector CD4+ T cell subpopulations and the molecular pathways influencing their generation are not known. We investigated the role of the STAT3 pathway in a murine model of chronic sclerodermatous GVHD. This pathway integrates multiple signaling events during the differentiation of naive CD4+ T cells and impacts their homeostasis. We report that chimeras receiving an allograft containing STAT3-ablated donor CD4+ T cells do not develop classic clinical and pathological manifestations of alloimmune tissue injury. Analysis of chimeras showed that abrogation of STAT3 signaling reduced the in vivo expansion of donor-derived CD4+ T cells and their accumulation in GVHD target tissues without abolishing antihost alloreactivity. STAT3 ablation did not significantly affect Th1 differentiation while enhancing CD4+CD25+Foxp3+ T cell reconstitution through thymus-dependent and -independent pathways. Transient depletion of CD25+ T cells in chimeras receiving STAT3-deficient T cells resulted in delayed development of alloimmune gut and liver injury. This delayed de novo GVHD was associated with the emergence of donor hematopoietic stem cell-derived Th1 and Th17 cells. These results suggest that STAT3 signaling in graft CD4+ T cells links the alloimmune tissue injury of donor graft T cells and the emergence of donor hematopoietic stem cell-derived pathogenic effector cells and that both populations contribute, albeit in different ways, to the genesis of chronic GVHD after allogenic bone marrow transplantation in a murine model.

Resolving lung injury: a new role for Tregs in controlling the innate immune response

Inflammation-associated lung injury is a major cause of morbidity and mortality for patients in intensive care units. Although the cellular and molecular events that initiate lung inflammation are now well understood, the mechanisms that promote its resolution remain poorly defined. In this issue of the JCI, D'Alessio et al. show in a mouse model that recovery from acute lung injury is not simply a passive process, but involves Tregs in an active resolution program (see the related article beginning on page 2898).

An imbalance of esophageal effector and regulatory T cell subsets in experimental eosinophilic esophagitis in mice

We recently reported a critical role for T cells in the induction of eosinophilic esophagitis (EE) in mice; however, the role of specific T cell subsets in disease pathogenesis is not yet understood. In the current study, we tested the hypothesis that allergen-induced EE develops in response to the disproportion of functionally different effector and regulatory T cells in the esophagus. Fluorescence-activated cell sorter analysis was performed to examine activated T cell subsets using the cell surface activation markers CD25 and CD69. A significant increase in activated CD4(+) and CD4(-) T cells was observed in the total esophageal cells isolated from the mouse model of EE. Furthermore, an imbalance in the effector and regulatory T cells was observed in the esophagus. The esophageal CD4(+)CD45RB(high) effector T cells in allergen-challenged mice increased compared with saline-challenged mice (65.4 +/- 3.6 x 10(3) to 44.8 +/- 4.2 x 10(3)), whereas CD4(+)CD45RB(low) mostly regulatory T cells decreased in allergen-challenged mice compared with saline-challenged mice (5.8 +/- 0.9 x 10(3) from 10.2 +/- 1.7 x 10(3)). The functional characteristics were examined by analysis of the pro- and anti-inflammatory cytokine profile of purified low and high CD4(+)CD45RB subsets from the spleen. Additionally, a significantly reduced interleukin (IL)-2 production by CD4(+)CD45RB(low) cells in allergen-challenged mice compared with saline-challenged mice was observed. The reduced IL-2 in the CD4(+)CD45RB(low) subset may be associated with reduction of CD4(+)CD45RB(low) subset. In conclusion, our results suggest that local regulatory interaction of CD45RB(high) and CD45RB(low) CD4(+) T cells may be required for protective and pathogenic immunity in EE.

Impairment of monocyte-derived dendritic cells in idiopathic pulmonary arterial hypertension

BACKGROUND AND AIM

With the development of immunology, the role of immune inflammation in idiopathic pulmonary arterial hypertension (IPAH) has attracted interest. Recently, it was discovered that dendritic cells, which are key players in immune inflammation, are implicated in the pathogenesis of IPAH. To elucidate the role of dendritic cells in human IPAH, we compared the changes in the number and immunological function of monocyte-derived dendritic cells (MoDCs) from the peripheral blood of patients with IPAH and healthy controls.

METHODS

The numbers of MoDC subsets (including plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs)) in circulating peripheral blood mononuclear cells (PBMCs) was analyzed by flow cytometry, and the concentrations of interleukin (IL)-12, IL-10, and tumor necrosis factor-alpha were measured by enzyme-linked immunosorbent serologic assay kits. The morphology, phenotypic expression, and the ability to stimulate T cell proliferation of MoDCs, cultured from PBMCs in vitro with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4, was analyzed by microscopy, flow cytometry, and MTT assay.

RESULTS

The results of the study are as follows: (1) The number of circulating mDCs was lower in IPAH patients than in controls (0.07 +/- 0.01% to 0.14 +/- 0.02%; p < 0.05). (2) IL-12 levels were higher in IPAH patients than in controls (p < 0.05). (3) MoDCs showed higher expression of CD1a (53.34 +/- 7.43% to 19.29 +/- 7.37%; p < 0.05), and lower expression of costimulatory molecule CD86 (64.54 +/- 5.93% to 87.04 +/- 4.82%; p < 0.05), and less ability to simulate T cell proliferation (when the ratio is 1:10) compared to the controls.

CONCLUSIONS

The study shows that it is possible to obtain typical DCs by culturing PBMCs from patients with IPAH with GM-CSF and IL-4, and it demonstrates that patients with IPAH have a significant change in the number of mDC and a marked immune deficiency of MoDCs.

Restricted autoantigen recognition associated with deletional and adaptive regulatory mechanisms

Autoimmune diabetes (T1D) is characterized by CD4(+) T cell reactivity to a variety of islet-associated Ags. At-risk individuals, genetically predisposed to T1D, often have similar T cell reactivity, but nevertheless fail to progress to clinically overt disease. To study the immune tolerance and regulatory environment permissive for such autoreactive T cells, we expressed TCR transgenes derived from two autoreactive human T cells, 4.13 and 164, in HLA-DR4 transgenic mice on a C57BL/6-derived "diabetes-resistant" background. Both TCR are responsive to an immunodominant epitope of glutamic acid decarboxylase 65(555-567), which is identical in sequence between humans and mice, is restricted by HLA-DR4, and is a naturally processed self Ag associated with T1D. Although both TCR use the identical Valpha and Vbeta genes, differing only in CDR3, we found stark differences in the mechanisms utilized in vivo in the maintenance of immune tolerance. A combination of thymic deletion (negative selection), TCR down-regulation, and peripheral activation-induced cell death dominated the phenotype of 164 T cells, which nevertheless still maintain their Ag responsiveness in the periphery. In contrast, 4.13 T cells are much less influenced by central and deletional tolerance mechanisms, and instead display a peripheral immune deviation including differentiation into IL-10-secreting Tr1 cells. These findings indicate a distinct set of regulatory alternatives for autoreactive T cells, even within a single highly restricted HLA-peptide-TCR recognition profile.

Molecular orchestration of differentiation and function of regulatory T cells

During the last decade, a unique mechanism of negative regulation of immune responses and inflammation by a dedicated population of so-called regulatory T cells (Treg) has become a focus of intensive investigation. Through the discovery of transcription factor Foxp3 as a central molecular determinant of differentiation and function of Treg cells, the complex biology of these cells, including maintenance of immunological tolerance to "self" and regulation of immune responses to pathogens, commensals, and tumors, has become amenable to mechanistic studies. In this review, we discuss the molecular aspects of Treg cell lineage commitment, maintenance, and function.

Filarial lymphedema is characterized by antigen-specific Th1 and th17 proinflammatory responses and a lack of regulatory T cells

Background

Lymphatic filariasis can be associated with development of serious pathology in the form of lymphedema, hydrocele, and elephantiasis in a subset of infected patients.

Methods and Findings

To elucidate the role of CD4⁺ T cell subsets in the development of lymphatic pathology, we examined specific sets of cytokines in individuals with filarial lymphedema in response to parasite antigen (BmA) and compared them with responses from asymptomatic infected individuals. We also examined expression patterns of Toll-like receptors (TLR1–10) and Nod-like receptors (Nod1, Nod2, and NALP3) in response to BmA. BmA induced significantly higher production of Th1-type cytokines—IFN-γ and TNF-α—in patients with lymphedema compared with asymptomatic individuals. Notably, expression of the Th17 family of cytokines—IL-17A, IL-17F, IL-21, and IL-23—was also significantly upregulated by BmA stimulation in lymphedema patients. In contrast, expression of Foxp3, GITR, TGFβ, and CTLA-4, known to be expressed by regulatory T cells, was significantly impaired in patients with lymphedema. BmA also induced significantly higher expression of TLR2, 4, 7, and 9 as well Nod1 and 2 mRNA in patients with lymphedema compared with asymptomatic controls.

Conclusion

Our findings implicate increased Th1/Th17 responses and decreased regulatory T cells as well as regulation of Toll- and Nod-like receptors in pathogenesis of filarial lymphedema.

Lymphatic filariasis afflicts over 120 million people worldwide. While the infection is mostly clinically asymptomatic, approximately 40 million people suffer from overt, morbid clinical pathology, characterized by swelling of the scrotal area and lower limbs (hydrocele and lymphedema). Host immunologic factors that determine susceptibility of this subset of individuals to clinically apparent disease is unknown. We addressed this issue by comparing the immunologic response of helper T (Th) cell subsets in lymphedema patients and clinically asymptomatic individuals. Four important subsets of Th cells (CD4⁺ T cells) are: Th1 cells, characterized by production of cytokines IL-2, IFN-γ, and TNF-α; Th2 cells, characterized by production of cytokines IL-4 and IL-13; Th17 cells, characterized by production of cytokines IL-17A, IL-17F, IL-21, and IL-22; and regulatory T cells (Tregs), characterized by the expression of transcription factor Foxp3, as well as other molecules such as GITR, TGFβ, and CTLA-4. We determined that Th1 and Th17 responses are significantly enhanced and Treg responses significantly impaired in lymphedema patients. This is accompanied by increased expression of pattern recognition receptors of the Toll and NOD family. Thus, approaches toward downregulating Th1 and Th17 responses and enhancing Treg responses would be beneficial in protecting against development of lymphatic disease.

Focus on TILs: prognostic significance of tumor infiltrating lymphocytes in human melanoma

Tumors contain variable numbers of lymphocytes, referred to as tumor infiltrating lymphocytes (TILs). In melanoma, the intensity of this lymphocytic infiltrate is believed to correlate with outcome, though there is some debate about the applicability of this finding for all melanomas. Much research has gone into classifying TILs with respect to antigen receptor structure and the antigen to which melanoma-specific T cells react. However, these studies for the most part did not immunophenotype TILs, and recent data has revealed that the composition of tumoral lymphocytes is not homogenous, but rather represents varying contributions from many lymphocytic subsets. Furthermore, the function of TILs is often compromised as a result of the accumulation of immunoregulatory cells and various tumor escape mechanisms. These recent insights stress the need to collect more data on the composition and function of TIL infiltrates before definitive conclusions about the prognostic significance of TILs can be drawn. Advances in immunology have also facilitated the development of immunotherapeutic strategies, examples of which will be discussed with a special emphasis on blocking antibodies against CTLA-4, which are prototypical immunotherapeutic agents. This flurry of novel "biological" therapies will undoubtedly complicate our already incomplete understanding of TIL immunobiology as each of these agents has the potential to uniquely distort the series of immunological events which normally occur in untreated melanoma. Therefore, considerable research is needed to better elucidate the function and prognostic significance of TILs in both untreated melanoma and tumors treated with "biological" therapy.

Polarized immune responses differentially regulate cancer development

Tumor-associated immune responses assert varied responses toward developing neoplasms that can either act to eradicate malignant cells via engagement of potent cytotoxic programs or alternatively enhance tumor growth through release of multifunctional pro-tumor mediators. Seemingly paradoxical, these disparate activities reflect a continuum of polarization (or activation) states possible for distinct leukocyte subsets that demonstrate tissue, organ, and tumor selectivity. Herein, we review clinical and experimental studies investigating cellular and molecular mechanisms utilized by neoplastic tissues to alternatively polarize immune responses that favor either pro- or anti-tumor immunity.

Regulatory T cells and their role in rheumatic diseases: a potential target for novel therapeutic development

Regulatory T cells have an important role in limiting immune reactions and are essential regulators of self-tolerance. Among them, CD4+CD25high regulatory T cells are the best-described subset. In this article, we summarize current knowledge on the phenotype, function, and development of CD4+CD25high regulatory T cells. We also review the literature on the role of these T cells in rheumatic diseases and discuss the potential for their use in immunotherapy.

Human spleen contains different subsets of dendritic cells and regulatory T lymphocytes

Most knowledge about dendritic cells (DCs) and regulatory T cells in humans has been gathered from circulating cells but little is known about their frequency and distribution in lymphoid organs. This report shows the frequency, phenotype and location of DCs and regulatory T cells in deceased organ donors' spleens. As determined by flow cytometry, conventional/myeloid DCs (cDCs) CD11c(high)HLA-DR(+)CD123(-/low) were 2.3 +/- 0.9% and LIN(-) HLA-DR(+)CD11c(high) 2.1 +/- 0.3% of total spleen cells. Mature CD11c(high)HLA-DR(+)CD83(+) were 1.5 +/- 0.8% and 1.0 +/- 1.6% immature CD11c(high)HLA-DR(+)CD83(-) cDC. There were 0.3 +/- 0.3% plasmacytoid DCs (pDC) CD11c(-/low)HLA-DR(+)CD123(high) and 0.3 +/- 0.1% LIN(-)HLA-DR(+)CD123(high). Cells expressing cDCs markers, BDCA-1 and BDCA-3, and pDCs markers BDCA-2 and BDCA-4 were observed in higher frequencies than DCs with other phenotypes evaluated. CD11c(+), CD123(+) and CD83(+) cells were located in subcapsular zone, T cells areas and B-cell follicles. CD4(+)CD25(high) Tregs were 0.2 +/- 0.2% and CD8(+)CD28(-) comprised 11.5 +/- 8.1% of spleen lymphocytes. FOXP3(+) cells were found in T- and B-cell areas. The improvement in cell separation, manipulation and expansion techniques, will facilitate the manipulation of donor spleen cells as a part of protocols for induction and maintenance of allograft tolerance or treatment of autoimmune diseases.

The T-cell pool is anergized in patients with multiple sclerosis in remission

Relapsing-remitting multiple sclerosis (RRMS) is a complex autoimmune disease of the central nervous system with oscillating phases of relapse and remission. RRMS has been considered to be driven by T helper type 1 (Th1) lymphocytes but new data indicate the involvement of Th17 responses. In the present study, blood samples from patients (n=48) and healthy individuals (n=44) were evaluated for their immunological status. T cells from patients with RRMS expressed high levels of the activation marker CD28 (P<0.05) and secreted both interferon-gamma (CD8: P<0.05) and interleukin-17 upon polyclonal mitogen or myelin oligodendrocyte glycoprotein antigen stimulation. However, T cells from patients with RRMS in remission, in contrast to relapse, had poor proliferative capacity (P<0.05) suggesting that they are controlled and kept in anergy. This anergy could be broken with CD28 stimulation that restored the T-cell replication. Furthermore, the patients with RRMS had normal levels of CD4(+) Foxp3(+) T regulatory cells but the frequency of Foxp3(+) cells lacking CD127 (interleukin-7 receptor) was lower in patients with MS (mean 12%) compared to healthy controls (mean 29%). Still, regulatory cells (CD25(+) sorted cells) from patients with RRMS displayed no difference in suppressive capacity. In conclusion, patients in relapse/remission demonstrate in vitro T-cell responses that are both Th1 and Th17 that, while in remission, appear to be controlled by tolerogenic mechanisms yet to be investigated.

Three phase II cytokine working group trials of gp100 (210M) peptide plus high-dose interleukin-2 in patients with HLA-A2-positive advanced melanoma

PURPOSE

High-dose interleukin-2 (IL-2) induces responses in 15% to 20% of patients with advanced melanoma; 5% to 8% are durable complete responses (CRs). The HLA-A2-restricted, modified gp100 peptide (210M) induces T-cell immunity in vivo and has little antitumor activity but, combined with high-dose IL-2, reportedly has a 42% (13 of 31 patients) response rate (RR). We evaluated 210M with one of three different IL-2 schedules to determine whether a basis exists for a phase III trial.

PATIENTS AND METHODS

In three separate phase II trials, patients with melanoma received 210M subcutaneously during weeks 1, 4, 7, and 10 and standard high-dose IL-2 during weeks 1 and 3 (trial 1), weeks 7 and 9 (trial 2), or weeks 1, 4, 7, and 10 (trial 3). Immune assays were performed on peripheral-blood mononuclear cells collected before and after treatment.

RESULTS

From 1998 to 2003, 131 patients with HLA-A2-positive were enrolled. With 60-month median follow-up time, the overall RR for 121 assessable patients was 16.5% (95% CI, 10% to 26%); the RRs were 23.8% in trial 1 (42 patients), 12.5% in trial 2 (40 patients), and 12.8% in trial 3 (39 patients). There were 11 CRs (9%) and nine partial responses (7%), with 11 patients (9%) progression free at >or= 30 months. Immune studies including assays of CD3-zeta expression and numbers of CD4(+)/CD25(+)/FoxP3(+) regulatory T cells, CD15(+)/CD11b(+)/CD14(-) immature myeloid-derived cells, and CD8(+)gp100 tetramer-positive cells in the blood did not correlate with clinical benefit.

CONCLUSION

The results again demonstrate efficacy of high-dose IL-2 in advanced melanoma but did not demonstrate the promising clinical activity reported with vaccine and high-dose IL-2 in any of three phase II trials.