Emerging possibilities in the development and function of regulatory T cells

Clinical Study on the Efficacy of Bevacizumab in Combination with Pembrolizumab on Cellular Immune Function in the Treatment of Driver Gene-Negative Stage IV Lung Adenocarcinoma

Purpose. To explore the efficacy of bevacizumab in combination with PD-1 immune drug pembrolizumab on cellular immune function in the treatment of driver gene-negative stage IV lung adenocarcinoma and its short-term survival effect. Methods. From February 2020 to December 2021, 85 patients with driver gene-negative stage IV lung adenocarcinoma were admitted to our hospital and treated with first-line therapy, and their clinical records were reviewed retrospectively. According to the treatments, the patients were separated into two groups the combination group (n = 45) and the control group (n = 40). The treatment regimen of the control group was an AP chemotherapy regimen (pemetrexed combined with cisplatin) + PD-1 immune drug pembrolizumab. The treatment regimen of the combination group was AP chemotherapy regimen + PD-1 immune drug pembrolizumab combined with bevacizumab. We evaluated the pre- and post-treatment cellular immunological function of the two patient groups and discussed the difference between them. Results. There was a substantial difference in the overall effective rate and the disease control rate between the two groups, with the former being 27.50% compared to 48.89% and the latter being 72.50% compared to 93.33% among these 85 patients studied. The KPS for the combination group improved and stayed at 91.11% after treatment, which is considerably better than the KPS for the control group, which was 42.50% (χ2 = 23.09, $P<0.05$ ). There was no significant difference ( $P>0.05$ ) in the numbers of CD3+, CD4+, CD19+, CD8+, or CD4+/CD8+ cells pretreatment between the two groups, but after treatment, the combination group had significantly higher numbers of all these cells. Neither the CD8+ nor the CD19+ level was significantly different between the control and combination groups ( $P>0.05$ ). Furthermore, the incidence of common clinical side effects was similar between the two groups ( $P>0.05$ ). Proteinuria, tiredness, increased alanine aminotransferase, hypertension, immunological pneumonia, muscle pain, arthralgia, hypothyroidism, etc. were the most common side effects reported among both groups throughout therapy. A grade IV side effect is rare. After follow-up until March 2022, the median PFS for the control group was 9.00 ± 1.65 months (95% CI, 5.76–12.24) and the mean PFS was 11.48 ± 0.91 months (95% CI, 9.69–13.26). Comparison of the median PFS of the combination group (13.00 ± 1.10) months (95% CI: 10.84–15.16) with the average PFS of the group (15.52 ± 0.88) months (95% CI = 13.79–17.25) reveals a statistically significant difference ( $P<0.05$ ). Conclusion. Combining bevacizumab with the PD-1 immune medication pembrolizumab to treat patients with stage IV lung adenocarcinoma improves the quality of life, short-term therapeutic effectiveness, immune function, and PFS.

Understanding the immune response and the current landscape of immunotherapy in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumor with high lethality. Even with surgery, radiotherapy, chemotherapy, and other locoregional or systemic therapies, the survival rates for PDAC are low and have not significantly changed in the past decades. The special characteristics of the PDAC's microenvironment and its complex immune escape mechanism need to be considered when designing novel therapeutic approaches in this disease. PDAC is characterized by chronic inflammation with a high rate of tumor-associated macrophages and myeloid-derived suppressor cells and a low rate of natural killer and effector T cells. The pancreatic microenvironment is a fibrotic, microvascularized stroma that isolates the tumor from systemic vascularization. Immunotherapy, a novel approach that has demonstrated effectiveness in certain solid tumors, has failed to show any practice-changing results in pancreatic cancer, with the exception of PDACs with mismatch repair deficiency and high tumor mutational burden, which show prolonged survival rates with immunotherapy. Currently, numerous clinical trials are attempting to assess the efficacy of immunotherapeutic strategies in PDAC, including immune checkpoint inhibitors, cancer vaccines, and adoptive cell transfer, alone or in combination with other immunotherapeutic agents, chemoradiotherapy, and other targeted therapies. A deep understanding of the immune response will help in the development of new therapeutic strategies leading to improved clinical outcomes for patients with PDAC.

Regulatory T-Cells and Multiple Myeloma: Implications in Tumor Immune Biology and Treatment

Multiple myeloma (MM) is associated with both cellular and humoral immune deficiencies and, despite significant advances in treatment, remains an incurable disease. Regulatory T-cells (Tregs) represent a critical subset of CD4 T-cells, characterized by CD4 + CD25+ Forkhead box P3+ (FoxP3+) phenotype, able to control peripheral tolerance and responses to foreign and tumor antigens. Tregs are elevated in various types of cancer, including hematological malignancies; in MM, data regarding Tregs function and numbers and their correlation with survival parameters are controversial. Advances in cancer biology have shown that the tumor microenvironment plays an important role in tumor progression. In MM, the highly immunosuppressive nature of the bone marrow microenvironment has been significantly elucidated in the past decade and it is now well acknowledged that targeting only the tumor clone may not be able to cure MM. Tregs within the tumor microenvironment might play a significant role in the suppression of antitumor immune responses against cancer cells and are considered to predict poor outcome in cancer patients; nonetheless the exact prognostic significance of this cell subpopulation in malignancies is still a matter of debate. In this review, we discuss the role of Tregs as an essential cell population of the MM immune microenvironment.

The extract of black cumin, licorice, anise, and black tea alleviates OVA-induced allergic rhinitis in mouse via balancing activity of helper T cells in lung

Background

A formulation of black cumin (Nigella sativa L.), licorice (Glycyrrhiza glabra L.), anise (Pimpinella anisum L.) and tea (Camellia sinensis (L.) Kuntze) (denoted BLAB tea) is traditionally used to relief allergy reaction including allergic rhinitis. However, little is known about its underlining mechanism of anti-allergic effects.

Methods

To investigate the anti-allergenic mechanism of BLAB tea, we treated ovalbumin (OVA)-induced allergic rhinitis (AR) model of mice with BLAB tea, and elucidated its possible mechanism of action. Mice in the control group were treated with phosphate-buffered saline only. Subsequently, the infiltration of different inflammatory cells was measured. In addition, histopathological changes in the nasal mucosa, and the levels of allergen-specific cytokines and OVA-specific immunoglobulins were measured.

Results

The aqueous extract of BLAB significantly alleviated the nasal symptoms and reduced the accumulation of inflammatory cells in the nasal mucosa and nasal lavage fluid of AR model of mice.

Conclusion

The aqueous extract of BLAB induced the production of Th1 and Treg cytokines and inhibited the release of Th2 cytokines and histamine in nasal mucosa and serum of mice while decreasing the serum levels of OVA-specific IgE, IgG1, and IgG2a. These results suggest the potential of the aqueous extract of BLAB as a treatment option for allergic diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00587-6.

CCR6 blockade on regulatory T cells ameliorates experimental model of multiple sclerosis

Regulatory T cells (Tregs) play a significant role in limiting damage of tissue affected by autoimmune process, which has been demonstrated in various experimental models for multiple sclerosis (MS) (mostly experimental autoimmune encephalomyelitis – EAE), rheumatoid arthritis, and type 1 diabetes. In this study, we demonstrated that Tregs increasingly migrate to central nervous system (CNS) during subsequent phases of EAE (preclinical, initial attack, and remission). In contrast, in peripheral tissues (blood, lymph nodes, and spleen), a significant accumulation of Tregs is mostly present during EAE remission. Moreover, an increased expression of CCR6 on Tregs in the CNS, blood, lymph nodes, and spleen in all phases of EAE was observed. The highest expression of CCR6 on Tregs from the CNS, lymph nodes, and spleen was noted during the initial attack of EAE, whereas in the blood, the peak expression of CCR6 was detected during the preclinical phase. The presence of Tregs in the CNS during EAE was confirmed by immunohistochemistry. To analyze additional functional significance of CCR6 expression on Tregs for EAE pathology, we modulated the clinical course of this MS model using Tregs with blocked CCR6. EAE mice, which received CCR6-deficient Tregs showed significant amelioration of disease severity. This observation suggests that CCR6 on Tregs may be a potential target for future therapeutic interventions in MS.

Vaccine Potential of Mycobacterial Antigens against Asthma

Asthma is a cause of substantial burden of disease in the world, including both premature deaths and reduced quality of life. A leading hypothesis to explain the worldwide increase of asthma is the "hygiene hypothesis," which suggests that the increase in the prevalence of asthma is due to the reduction in exposure to infections/microbial antigens. In allergic asthma, the most common type of asthma, antigen-specific T helper (Th)2 and Th17 cells and their cytokines are primary mediators of the pathological consequences. In contrast, Th1 and T regulatory (Treg) cells and their cytokines play a protective role. This article aims to review the information on the effect of mycobacteria and their antigens in modulating Th2/Th17 responses towards Th1/Treg responses and protection against asthma in humans and animal models.

Regulatory T cells: Possible mediators for the anti-inflammatory action of statins

Statins beside their main effect on reducing the progression of cardiovascular disease through pharmacological inhibition of the endogenous cholesterol synthesis, have additional pleiotropic effects including antiinflammatory effects mediated through the induction of suppressor regulatory T cells (Tregs). Statin-induced expansion of Tregs reduces chronic inflammation and may have beneficial effects in autoimmune diseases. However, statins could represent a double-edged sword in immunomodulation. Drugs that act by increasing the concentration of Tregs could enhance the risk of cancers, particularly in the elderly and may have adverse effects in neurodegenerative disorders and infectious diseases. In the present paper, we review the experimental studies that evaluate the effects of statins on Treg cells in autoimmune and inflammatory diseases and we discuss potential therapeutic applications of statins in this setting.

[Analyses of Foxp3+ Treg cells and Tr1 cells in subcutaneous immunotherapy-treated allergic individuals in humans and mice]

Subcutaneous immunotherapy (SCIT) is a causative treatment for allergic diseases. More recently, it has become clear that regulatory T (Treg) cells are increased by SCIT. Treg cells are generally divided into two main groups: 1) CD25⁺ Foxp3⁺ CD4⁺ T cells (Foxp3⁺ Treg cells) and 2) IL-10-producing Foxp3^- CD4⁺ T cells (Tr1 cells). We demonstrated that the number of Tr1 cells in peripheral blood mononuclear cells in SCIT-treated pollinosis patients were significantly higher than that in non-SCIT-treated patients, but Foxp3⁺ Treg cells were not. Consistent with the results of human peripheral blood, Tr1 cells were increased in the lungs of asthmatic mice by SCIT, but Foxp3⁺ Treg cells were not. Moreover, in vitro-induced Tr1 cells were responded to the antigen to produce a large amount of IL-10 in in vitro and in vivo. Adoptive transfer of the induced Tr1 cells significantly suppressed the development of asthma. In any species of human and mouse, the increase in Tr1 cells rather than Foxp3⁺ Treg cells could be important for the effects of SCIT. The increased Tr1 cells by SCIT functionally suppressed allergic asthma probably via production of IL-10 in response to the specific antigen. Therefore, analyses of the induction mechanisms of Tr1 cells and search for compounds which induce Tr1 cells are thought to lead to development of more efficient SCIT.

Ethanol extract of Dryopteris crassirhizoma alleviates allergic inflammation via inhibition of Th2 response and mast cell activation in a murine model of allergic rhinitis

ETHNOPHARMACOLOGICAL RELEVANCE

Dryopteris crassirhizoma (DC) is used as a traditional herbal remedy to treat various diseases, the tapeworm infection, common cold, and cancer in Korea, Japan, and China. DC also has the antioxidant anti-inflammatory and antibacterial activities. However, the anti-allergic inflammatory effect of DC and some of its mechanisms in allergic rhinitis model are unknown well.

AIM OF THIS STUDY

The purpose of this study is to investigate the anti-allergic inflammatory effect of DC on the allergic rhinitis model, mast cell activation and histamine release.

MATERIALS AND METHODS

Allergic rhinitis was induced in BALB/c mice by sensitization and challenge with ovalbumin (OVA). Different concentration of DC and dexamethasone was administrated by oral gavage on 1 h before the OVA challenge. Mice of the control group were treated with saline only. Then mice were evaluated for the presence of nasal mucosa inflammation, the production of allergen-specific cytokine response and the histology of nasal mucosa.

RESULTS

DC significantly ameliorated the nasal symptoms and the inflammation of nasal mucosa. DC also reduced the infiltration of eosinophils and mast cells in these tissues and the release of histamine in blood. Meanwhile, DC evidently inhibited the overproduction of Th2 cytokines and increased the Th1 and Treg cytokines in nasal lavage fluid by OVA. DC also reduced the levels of OVA-specific IgE, IgG1 and IgG2a in blood.

CONCLUSIONS

This study suggests that DC has a significant anti-allergic inflammatory effect in the nasal cavity. DC may have the therapeutic effect of allergic rhinitis.

LAT alleviates Th2/Treg imbalance in an OVA-induced allergic asthma mouse model through LAT-PLC-γ1 interaction

INTRODUCTION

Low expression of linker for activation of T cells (LAT) is observed in asthma. LAT and its downstream regulator, phospholipase C-gamma 1 (PLC-γ1) play important roles in the T cell antigen receptor signaling pathway, and their interaction is associated with CD4⁺ cell polarization. Here, we investigated whether LAT can alleviate the imbalance among CD4⁺ cell subgroups and the possible mechanism.

METHODS

An ovalbumin-induced allergic asthma mouse model was established and LAT plasmid was delivered. The pathological changes in lung were evaluated by hematoxylin and eosin and periodic acid-Schiff staining. The typical cytokines released by T helper 2 (Th2) and regulatory T (Treg) cells were measured using enzyme-linked immunosorbent assay and the number of Th1, Th2, and Treg cells were determined using flow cytometry. Lung CD4⁺ T cells were isolated by magnetic isolation. The mRNA expression of LAT and PLC-γ1 was determined by real-time PCR. Co-Immunoprecipitation was performed to confirm the interaction between LAT and PLC-γ1. The protein expression of LAT, PLC-γ1 and corresponding downstream signaling factors were determined by western blotting.

RESULTS

The delivery of LAT DNA to the lung could suppress an overactive Th2 response by decreasing allergic response and Th2 cytokine secretion, and by increasing Treg cytokine secretion. The Th2/Treg imbalance in lung and decreased phosphorylated PLC-γ1 expression in lung CD4⁺ T cells were rectified by LAT DNA delivery. Excessive activation of the Raf-MEK-ERK and PI3K-AKT-CREB pathways after asthma is attenuated by LAT.

CONCLUSION

The site-specific delivery of LAT DNA to the lung could suppress an overactive Th2 response and rectify the Th2/Treg imbalance in asthmatic mouse model. LAT-PLC-γ1 interaction may contribute to LAT activity in vivo and LAT protects against asthma partly via Raf-MEK-ERK and PI3K-AKT-CREB pathways. The delivery of LAT DNA could offer a novel and safe strategy for asthma prevention.

Myeloid-derived suppressor cells and myeloid regulatory cells in cancer and autoimmune disorders

Myeloid-derived suppressor cells (MDSCs) were originally described as a heterogeneous population of immature cells derived from myeloid progenitors with immune-suppressive functions in tumor-bearing hosts. In recent years, increasing number of studies have described various populations of myeloid cells with MDSC-like properties in murine models of cancer and autoimmune diseases. These studies have observed that the populations of MDSCs are increased during inflammation and autoimmune conditions. In addition, MDSCs can effectively suppress T cell responses and modulate the activity of natural killer cells and other myeloid cells. MDSCs have also been implicated in the induction of regulatory T cell production. Furthermore, these cells have the potential to suppress the autoimmune response, thereby limiting tissue injury. Myeloid regulatory cells (Mregs) are recently attracting increasing attention, since they function in proinflammatory and immune suppression in autoimmune diseases, as well as in various types of cancer. Currently, research focus is directed from MDSCs to Mregs in cancer and autoimmune diseases. The present study reviewed the suppressive roles of MDSCs in various autoimmune murine models, the immune modulation of MDSCs to T helper 17 lymphocytes, as well as the proinflammatory and immunosuppressive roles of Mregs in various types of cancer and autoimmune diseases.

Advances in Diagnosis and Treatments for Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired hemorrhagic condition characterized by the accelerated clearance of platelets caused by antiplatelet autoantibodies. A platelet count in peripheral blood <100 × 10⁹/L is the most important criterion for the diagnosis of ITP. However, the platelet count is not the sole diagnostic criterion, and the diagnosis of ITP is dependent on additional findings. ITP can be classified into three types, namely, acute, subchronic, and persistent, based on disease duration. Conventional therapy includes corticosteroids, intravenous immunoglobulin, splenectomy, and watch-and-wait. Second-line treatments for ITP include immunosuppressive therapy [eg, anti-CD20 (rituximab)], with international guidelines, including rituximab as a second-line option. The most recently licensed drugs for ITP are the thrombopoietin receptor agonists (TRAs), such as romiplostim and eltrombopag. TRAs are associated with increased platelet counts and reductions in the number of bleeding events. TRAs are usually considered safe, effective treatments for patients with chronic ITP at risk of bleeding after failure of first-line therapies. Due to the high costs of TRAs, however, it is unclear if patients prefer these agents. In addition, some new agents are under development now. This manuscript summarizes the pathophysiology, diagnosis, and treatment of ITP. The goal of all treatment strategies for ITP is to achieve a platelet count that is associated with adequate hemostasis, rather than a normal platelet count. The decision to treat should be based on the bleeding severity, bleeding risk, activity level, likely side effects of treatment, and patient preferences.

Treatment with a neutralising anti-rat interleukin-17 antibody after multiple-trauma reduces lung inflammation

BACKGROUND

It has been well recognised that a deficit of numbers and function of CD4(+)CD25(+)Foxp3(+) cells (Treg) is attributed to the development of autoimmune diseases and inflammatory diseases; additionally, IL-17-producing cells (Th17) have a pro-inflammatory role. The balance between Th17 and Treg may be essential for maintaining immune homeostasis and has long been thought as one of the important factors in the development/prevention of autoimmune diseases and inflammatory diseases. In our previous research, we explored that cytokines (IL-17) and the balance of Treg/Th17 had a significant relevance with tissue (lung) inflammation and injury in acute-phase after multiple-trauma.

OBJECTIVE

To more verify whether an imbalance of Treg/Th17 is characteristic of rats suffering from multiple trauma.

METHODS AND SUBJECTIVE

Using IL-17 monoclonal antibody (IL-17mAb)-treated multiple-trauma rat, we tested the pathogenic role of IL-17 in the development of multiple-trauma. Rat models were treated respectively with IL-17mAb or rat IgG 2A isotype control or phosphate-buffered solution after model was established. Normal rats only received anaesthesia and cannulation were taken as sham. Rats in each group were killed respectively at the end of 1h, 4h, 8h after injection. Collected serum and lung samples for assessment dynamically of MPO, IL-17, IL-6, and TGF-β-mRNA, and cytokine (IL-17, IL-6, TGF-β) and lung tissue for pulmonary histological analysis.

RESULTS

Neutralisation of IL-17 with anti-IL-17 can decrease serum IL-17 level and the IL-17-mRNA transcript level in lung, and ameliorate tissue inflammatory, defer disease course.

CONCLUSION

Our data suggest that IL-17 is crucially involved in the pathogenesis of multiple-trauma in rat, IL-17 inhibition might ameliorate the lung inflammation in acute-phase after multiple-trauma.

EMSA Eritin Drives Expansion of Regulatory T Cells and Promotes T Cells Differentiation in Irradiated Mice

Sublethal irradiation therapy in cancer treatment causes generalized immunosuppression, which results in a range of DNA damage. We examined the significance of a polyherbal medicine called "EMSA Eritin" on immunological responses in sublethally irradiated mice focusing on the involvement of Treg, naïve T cell, and also the development and differentiation of T cells in thymus. Normal BALB/c mice were sublethally irradiated with dose of 600 rad. The irradiated mice were then orally administered by EMSA Eritin once a day at different doses: 1.04, 3.12, 9.37 mg/g body weight. The treatment was performed for 14 days. On day 15, immunological responses were observed by analyzing the status of Treg and differentiation of T cells in thymus. The administration of EMSA Eritin to irradiated mice resulted in a significant increase of pre T cells, Treg cells, and naïve T cells, which in general could maintain and normalize healthy condition in mice.

Increased expression of Notch 1 in a rat liver transplantation model

Liver transplantation is the standard treatment for end‑stage liver failure; however, rejection can result in allograft failure. In order to investigate the role of Notch 1 during rejection, the present study evaluated Notch 1 expression, as well as the levels of immune reactivity, in rat liver allografts. A heterotopic liver transplantation model was established using Dark Agouti (DA) rats as donors and Lewis rats as recipients (DA/Lewis), with DA recipient rats serving as controls (DA/DA). The concentration levels of immune reactivity markers and serum Notch 1 were measured on days 3, 5, and 7. The overall survival was significantly shorter (<10 days) in the DA/Lewis group, as compared with the DA/DA group (P<0.0001). The concentration levels of serum alanine aminotransferase and total bilirubin were significantly higher 5 and 7 days following transplantation in the DA/Lewis group, as compared with the DA/DA group (P<0.001). The concentration levels of serum Notch 1 were significantly higher in the DA/Lewis group, as compared with the DA/DA group on days 3, 5, and 7 following transplantation (P<0.0001). These results indicate that the expression levels of serum Notch 1 significantly increase during liver allograft rejection, suggesting that Notch 1 is involved in the mechanism underlying liver allograft rejection. Notch 1 may serve as a marker of acute rejection in a rat liver transplantation model.

Type 1 diabetes and T regulatory cells

T-regulatory cells (Tregs) play a fundamental role in the creation and maintenance of peripheral tolerance. Deficits in the numbers and/or function of Tregs may be an underlying cause of human autoimmune diseases including type 1 Diabetes Mellitus (T1D), whereas an over-abundance of Tregs can hinder immunity against cancer or pathogens. The importance of Tregs in the control of autoimmunity is well established in a variety of experimental animal models. In mice, manipulating the numbers and/or function of Tregs can decrease pathology in a wide range of contexts, including autoimmunity and it is widely assumed that similar approaches will be possible in humans. T1D, the most prevalent human autoimmune disease, has been a focus of interventions either through direct and indirect in vivo proliferations or through adoptive transfer of the in vitro generated antigen specific and non specific Treg. Some challenges still need to be addressed, including a more specific phenotype marker for Tregs; the reproducibility of satisfactory animal results in human and the reconcile of discrepancies between in vitro and in vivo studies. In this article, we will highlight the role of Tregs in autoimmune disease in general with a special focus on T1D, highlighting progress made and challenges ahead in developing Treg-based therapies.

Intratumoral myeloid cells regulate responsiveness and resistance to antiangiogenic therapy

Antiangiogenic therapy is commonly used in the clinic, but its beneficial effects are short-lived, leading to tumor relapse within months. Here, we found that the efficacy of angiogenic inhibitors targeting the VEGF/VEGFR pathway was dependent on induction of the angiostatic and immune-stimulatory chemokine CXCL14 in mouse models of pancreatic neuroendocrine and mammary tumors. In response, tumors reinitiated angiogenesis and immune suppression by activating PI3K signaling in all CD11b+ cells, rendering tumors nonresponsive to VEGF/VEGFR inhibition. Adaptive resistance was also associated with an increase in Gr1+CD11b+ cells, but targeting Gr1+ cells was not sufficient to further sensitize angiogenic blockade because tumor-associated macrophages (TAMs) would compensate for the lack of such cells and vice versa, leading to an oscillating pattern of distinct immune-cell populations. However, PI3K inhibition in CD11b+ myeloid cells generated an enduring angiostatic and immune-stimulatory environment in which antiangiogenic therapy remained efficient.

Low TCR signal strength induces combined expansion of Th2 and regulatory T cell populations that protect mice from the development of type 1 diabetes

AIMS/HYPOTHESIS

Weak stimulation of CD4(+) T cells induces expansion of CD4(+) forkhead box P3(+) regulatory T cells (Tregs) and can also promote T helper (Th) 2 responses, which have demonstrable beneficial effects on autoimmune diabetes. This study explored the feasibility of combined Treg/Th2 expansion for immunotherapy of type 1 diabetes in NOD mice.

METHODS

We compared Treg and Th responses to dendritic cells (DC) presenting scaled antigen doses to islet-specific NOD CD4(+) T cells. Flow cytometric and Luminex analyses were performed to determine the phenotype and cytokine profile of expanded T cells. The ability of expanded T cells to prevent type 1 diabetes was tested in an adoptive transfer model.

RESULTS

In vitro studies revealed a hierarchical, selective expansion of Treg and T effector (Teff) populations at different antigen doses. Thus, a single low dose produced a mixture of Tregs Th2 and type 1 regulatory (Tr1) cells, which prevented diabetes in NOD-SCID mice and increased the ratio of Treg/Teff cells infiltrating the pancreatic islets. Subcutaneous injection of DC, previously shown to prevent diabetes in NOD mice, induced expansion of the same mixture of Tregs Tr1 and Th2 cells. Low-dose expansion of Treg required MHC-T cell receptor interaction and was partly dependent on T cell derived TGF-β and IL-2. Autocrine IFN-γ was required for the promotion of diabetogenic Th1 cells at high antigen doses.

CONCLUSIONS/INTERPRETATION

Weak stimulation of CD4(+) T cells with DC and low-dose antigen expands a combination of antigen-specific Tregs Th2 and Tr1 cells that prevent autoimmunity, without the need to target or purify specific Treg populations.

Role of IL-17A and IL-10 in the antigen induced inflammation model by Mycoplasma pneumoniae

BACKGROUND

Mycoplasma pneumoniae is one of the causative organisms of community-acquired pneumonia which is found commonly in younger patients. Extrapulmonary complications similar to autoimmune disease are caused by M. pneumoniae following the initial infection. The mechanism and pathology of onset is not clear, but it is considered that excessive host immunoreactions play a part in the onset of mycoplasmal pneumonia and its extrapulmonary complications. In this study, we investigated the participation of the immune response, excluding the participation of Th1 and Th2 which has previously been investigated.

RESULTS

In this study, the host immune response of an antigen induced inflammation model using SPF mice repeatedly sensitized with M. pneumoniae antigens was analyzed. The specificity of M. pneumoniae antigens in the Th17 response of murine lymphocytes in vitro was also examined. Frequent and concentrated sensitization induced exacerbation of lung inflammation immunologically and pathologically, and evoked intrapulmonary IL-17A and IL-10 production. M. pneumoniae antigen stimulation induced proliferation of mouse lymphocytes and caused production of IL-17A and IL-10. In addition, it was shown that IL-17A and IL-10 production was increased in the presence of IL-6 and TGF-β1.

CONCLUSIONS

It was shown that M. pneumoniae antigens induced potent immunoreaction and enhanced the Th17 cell response both in vivo and in vitro, and that both Treg and IL-10 are involved in the suppression of IL-17A production. This raises the possibility that breakdown of the immune balance may be part of the process leading to subsequent development of extrapulmonary mycoplasmal pneumonia.

Cotransfection with IL-10 and TGF-β1 into immature dendritic cells enhances immune tolerance in a rat liver transplantation model

Dendritic cells transfected with interleukin (IL)-10 and transforming growth factor-β1 (TGF-β1) enhance T cell immunity and tolerance. However, no quantitative studies have investigated the suppressive functions of immature dendritic cells (imDC) cotransfected with IL-10 and TGF-β1. The effects of imDC cotransfected with IL-10 and TGF-β1 (IL-10-TGF-β1-imDC) on immune tolerance induction in a rat transplantation model were investigated. In addition, effects of IL-10-TGF-β1-imDC relative to IL-10-transfected imDC (IL-10-imDC) and TGF-β1-transfected imDC (TGF-β1-imDC) were compared. The infusion of IL-10-TGF-β1-imDC into recipients prolonged liver graft survival, which was sustained for >90 days. IL-12 serum levels decreased, whereas alanine transaminase and total bilirubin slightly increased in rats infused with IL-10-TGF-β1-imDC compared with the IL-10-imDC and TGF-β1-imDC groups. Furthermore, a higher percentage of terminal transferase-mediated UTP nick end-labeling-positive cells was observed, and histological analysis of the allografts indicated a rejection activity index of mild acute rejection. Our results suggest infusion of IL-10 and TGF-β1 cotransfected imDC induces alloantigen-specific T cell hyporesponsiveness, inhibits antigen-specific immunological responses to liver allografts, prolongs liver allograft survival, and enhances the immune tolerance. This approach may provide a promising alternative for enhancing donor-specific tolerance during liver transplantation.

Dendritic cell subsets in type 1 diabetes: friend or foe?

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease characterized by immune mediated destruction of the insulin-producing β cells in the islets of Langerhans. Dendritic cells (DC) have been implicated in the pathogenesis of T1D and are also used as immunotherapeutic agents. Plasmacytoid (p)DC have been shown to have both protective and pathogenic effects and a newly described merocytic DC population has been shown to break tolerance in the mouse model of T1D, the non-obese diabetic (NOD) mouse. We have used DC populations to prevent the onset of T1D in NOD mice and clinical trials of DC therapy in T1D diabetes have been initiated. In this review we will critically examine the recent published literature on the role of DC subsets in the induction and regulation of the autoimmune response in T1D.

Mechanisms Underlying CD4+ Treg Immune Regulation in the Adult: From Experiments to Models

To maintain immunological balance the organism has to be tolerant to self while remaining competent to mount an effective immune response against third-party antigens. An important mechanism of this immune regulation involves the action of regulatory T-cell (Tregs). In this mini-review, we discuss some of the known and proposed mechanisms by which Tregs exert their influence in the context of immune regulation, and the contribution of mathematical modeling for these mechanistic studies. These models explore the mechanisms of action of regulatory T cells, and include hypotheses of multiple signals, delivered through simultaneous antigen-presenting cell (APC) conjugation; interaction of feedback loops between APC, Tregs, and effector cells; or production of specific cytokines that act on effector cells. As the field matures, and competing models are winnowed out, it is likely that we will be able to quantify how tolerance-inducing strategies, such as CD4-blockade, affect T-cell dynamics and what mechanisms explain the observed behavior of T-cell based tolerance.

The imbalance between regulatory and IL-17-secreting CD4⁺T cells in multiple-trauma rat

BACKGROUND

It has been well recognised that a deficit of numbers and function of CD4(+)CD25(+)Foxp3(+)cells (Treg) is attributed to the development of auto-immune diseases, inflammatory diseases, tumour and rejection of transplanted tissue; however, there are controversial data regarding the suppressive effect of Treg cells on the T-cell response in auto-immune diseases. Additionally, interleukin-17 (IL-17)-producing cells (Th17) have a pro-inflammatory role. The balance between Th17 and Treg may be essential for maintaining immune homeostasis and has long been thought as one of the important factors in the development/prevention of auto-immune diseases, inflammatory diseases, tumour and rejection of transplanted tissue, but their role in multiple trauma remains unclear.

OBJECTIVE

This study aims to investigate whether an imbalance of Treg and Th17 effector cells is characteristic of rats suffering from multiple trauma.

METHODS AND SUBJECTIVE

Sixty Sprague-Dawley (SD) rats were randomly divided into three groups. The control group (n=20, group I) no received procedures (normal). The sham group (n=20, group II) only received anaesthesia, cannulation and observation. The bilateral femoral shaft fractures with haemorrhagic shock groups (n=20, group III). Rats in groups II and III were killed at the end of 4h after models were established. Peripheral blood samples were collected for assessment of Treg cells, Th17 cells and cytokines (IL-17, IL-6, IL-2, transforming growth factor beta (TGF-β)) and intestine tissue was collected for intestine histological analysis.

RESULTS

We observed decreased Treg/Th17 ratios in CD4(+)T cells in rats with multiple trauma and a strong inverse correlation with disease activity (intestinal histological scores).

CONCLUSION

We suggest a role for immune imbalance in the pathogenesis and development of multiple trauma. The alteration of the index of Treg/Th17 cells likely indicates the therapeutic response and progress in the clinic.

The stromal compartments in pancreatic cancer: are there any therapeutic targets?

Pancreatic ductal adenocarcinoma (PDAC) is characterised by an abundant stromal response also known as a desmoplastic reaction. Pancreatic Stellate Cells have been identified as playing a key role in pancreatic cancer desmoplasia. There is accumulating evidence that the stroma contributes to tumour progression and to the low therapeutic response of PDAC patients. In this review we described the main actors of the desmoplastic reaction within PDAC and novel therapeutic approaches that are being tested to block the detrimental function of the stroma.

CD4(+)CD62L(+) central memory T cells can be converted to Foxp3(+) T cells

The peripheral Foxp3(+) Treg pool consists of naturally arising Treg (nTreg) and adaptive Treg cells (iTreg). It is well known that naive CD4(+) T cells can be readily converted to Foxp3(+) iTreg in vitro, and memory CD4(+) T cells are resistant to conversion. In this study, we investigated the induction of Foxp3(+) T cells from various CD4(+) T-cell subsets in human peripheral blood. Though naive CD4(+) T cells were readily converted to Foxp3(+) T cells with TGF-β and IL-2 treatment in vitro, such Foxp3(+) T cells did not express the memory marker CD45RO as do Foxp3(+) T cells induced in the peripheral blood of Hepatitis B Virus (HBV) patients. Interestingly, a subset of human memory CD4(+) T cells, defined as CD62L(+) central memory T cells, could be induced by TGF-β to differentiate into Foxp3(+) T cells. It is well known that Foxp3(+) T cells derived from human CD4(+)CD25(-) T cells in vitro are lack suppressive functions. Our data about the suppressive functions of CD4(+)CD62L(+) central memory T cell-derived Foxp3(+) T cells support this conception, and an epigenetic analysis of these cells showed a similar methylation pattern in the FOXP3 Treg-specific demethylated region as the naive CD4(+) T cell-derived Foxp3(+) T cells. But further research showed that mouse CD4(+) central memory T cells also could be induced to differentiate into Foxp3(+) T cells, such Foxp3(+) T cells could suppress the proliferation of effector T cells. Thus, our study identified CD4(+)CD62L(+) central memory T cells as a novel potential source of iTreg.

Chronic heat stress inhibits immune responses to H5N1 vaccination through regulating CD4⁺ CD25⁺ Foxp3⁺ Tregs

Chronic heat stress (CHS) is known to have negative impacts on the immune responses in animals and increases their susceptibility to infections including the highly pathogenic avian influenza virus H5N1. However, the role of regulatory T cells (Tregs) in CHS immunosuppression remains largely undefined. In this study, we demonstrated a novel mechanism by which CHS suppressed both Th1 and Th2 immune responses and dramatically decreased the protective efficacy of the formalin-inactivated H5N1 vaccine against H5N1 influenza virus infection. This suppression was found to be associated with the induced generation of CD4⁺CD25⁺FoxP3⁺ Tregs and the increased secretions of IL-10 and TGF-β in CD4⁺ T cells. Adoptive transfer of the induced Tregs also suppressed the protective efficacy of formalin-inactivated H5N1 virus immunization. Collectively, this study identifies a novel mechanism of CHS immunosuppression mediated by regulating CD4⁺CD25⁺Foxp3⁺ Tregs.

Immune evasion and the evolution of molecular mimicry in parasites

Parasites that are molecular mimics express proteins which resemble host proteins. This resemblance facilitates immune evasion because the immune molecules with the specificity to react with the parasite also cross-react with the host's own proteins, and these lymphocytes are rare. Given this advantage, why are not most parasites molecular mimics? Here we explore potential factors that can select against molecular mimicry in parasites and thereby limit its occurrence. We consider two hypotheses: (1) molecular mimics are more likely to induce autoimmunity in their hosts, and hosts with autoimmunity generate fewer new infections (the "costly autoimmunity hypothesis"); and (2) molecular mimicry compromises protein functioning, lowering the within-host replication rate and leading to fewer new infections (the "mimicry trade-off hypothesis"). Our analysis shows that although both hypotheses may select against molecular mimicry in parasites, unique hallmarks of protein expression identify whether selection is due to the costly autoimmunity hypothesis or the mimicry trade-off hypothesis. We show that understanding the relevant selective forces is necessary to predict how different medical interventions will affect the proportion of hosts that experience the different infection types, and that if parasite evolution is ignored, interventions aimed at reducing infection-induced autoimmunity may ultimately fail.

Partial depletion of regulatory T cells does not influence the inflammation caused by high dose hemi-body irradiation

There is clinical interest in the modulation of regulatory T cells for cancer therapy. The safety of these therapies in combination with conventional anti-cancer therapies, including radiation therapy, can be studied in animal models. The effects of partial depletion of regulatory T (Treg) cells with an anti-CD25 antibody in conjunction with ionizing radiation on inflammation and tissue injury were analyzed in C57BL/6 mice. An anti-CD25 antibody (PC61) was administered 3 days prior to 13 Gy lower-half hemi-body irradiation (HBI). The blood, spleen, mesenteric lymph nodes (mLNs) and inguinal lymph nodes (iLNs) were harvested at various times thereafter. Alterations in the proportion of leukocyte subsets including CD4⁺ T cells, CD8⁺ T cells, Treg cells, B cells, NK cells, NK1.1⁺ T cells, macrophages and granulocytes were analyzed by FACS. The lungs, liver, pancreas, stomach, jejunum, duodenum, ileum, colon and kidney were harvested and studied by H&E staining. Expression of inflammatory mediators in plasma and tissue were investigated by ELISA. HBI significantly decreased the leukocyte pool though the various leukocyte subsets had different sensitivities to HBI. The administration of PC61 significantly decreased the proportion of Treg cells in spleen, iLN, mLN and blood (reduction of approximately 60%). Irradiation significantly increased the proportion of Treg cells in the spleen, iLN and mLN. HBI induced a systemic inflammatory reaction as demonstrated by increased plasma levels of IL-6, KC/CXCL1 and circulating granulocytes in the blood. Neutrophils also infiltrated the small bowel. The same general patterns were observed whether or not Treg cells were partially depleted with PC61 prior to HBI. These data demonstrate that partial depletion of Treg cells in these mice does not influence HBI-induced inflammatory response and tissue injury, and that combining anti-CD25 therapy with radiation may be safe and well tolerated in a clinical setting.

ST2 gene-deletion reveals a role of Foxp3+ regulatory T cells in diabetes modulation in BALB/c mice

BALB/c mice are resistant to diabetes induced by multiple low doses of streptozotocin (MLD-STZ; 5 × 40 mg/kg body weight [b.w.]) regimen in contrast to C57/BL6 mice. The deletion of ST2 gene renders BALB/c mice susceptible to diabetes induction. Cyclophosphamide (CY) in the dose of 175 mg/kg b.w. eliminated CD4+Foxp3+ regulatory T cells (Tregs) and enhanced disease severity in C57/BL6 mice, but it did not overcome resistance to diabetes in BALB/c mice and did not affect diabetes progression in ST2 knock-out (ST2KO) mice. We argued that a lower dose of CY may selectively eliminate Tregs while sparing effector T cells in BALB/c mice. Indeed, only a very low dose of CY (50 mg/kg b.w.) enhanced diabetes severity in ST2KO mice. This treatment eliminated Tregs in pancreatic lymph nodes in ST2KO mice, while markedly increasing the influx of CD8+, CD4+TNF-α+, and CD4+IFN-γ+ effector T cells (Teffs) in pancreata. Also, the aggravation of diabetes was accompanied with increased serum levels of TNF-α, IFN-γ, and IL-17. Taken together, our data suggest that the prevailing Th2 immune response in BALB/c mice may be responsible for the resistance to MLD-STZ diabetes and that ST2 gene deletion reveals the role of highly cyclophosphamide sensitive CD4+Foxp3+ regulatory T cells in the pancreatic lymph nodes in diabetes modulation.

The effect of ionizing radiation on the homeostasis and functional integrity of murine splenic regulatory T cells

OBJECTIVE

Radiotherapy affects antitumor immune responses; therefore, it is important to study radiation effects on various compartments of the immune system. Here we report radiation effects on the homeostasis and function of regulatory T (Treg) cells, which are important in down-regulating antitumor immune responses.

METHODS

C57Bl/6 mice were irradiated with 2 Gy and alterations in splenic lymphocyte fractions analyzed at different intervals.

RESULTS

Total CD4+ numbers showed stronger decrease after irradiation than CD4+Foxp3+ Tregs. Tregs were less prone to radiation-induced apoptosis than CD4+Foxp3- T cells. The ratio of CD4+Foxp3- and CD4+Foxp3+ fractions within the proliferating CD4+ pool progressively changed from 74:26 in control animals to 59:41 eleven days after irradiation, demonstrating a more dynamic increase in the proliferation and regeneration of the Treg pool. The CD4+Foxp3+ fraction expressing cell-surface CTLA4, an antigen associated with Treg cell activation increased from 5.3 % in unirradiated mice to 10.5 % three days after irradiation. The expression of IL-10 mRNA was moderately upregulated, while TGF-β expression was not affected. On the other hand, irradiation reduced Treg capacity to suppress effector T cell proliferation by 2.5-fold.

CONCLUSION

Tregs are more radioresistant, less prone to radiation-induced apoptosis, and have faster repopulation kinetics than CD4+Foxp3- cells, but irradiated Tregs are functionally compromised, having a reduced suppressive capacity.

HLA-DP genetic variation, proxies for early life immune modulation and childhood acute lymphoblastic leukemia risk

The human leukocyte antigen (HLA) genes are candidate genetic susceptibility loci for childhood acute lymphoblastic leukemia (ALL). We examined the effect of HLA-DP genetic variation on risk and evaluated its potential interaction with 4 proxies for early immune modulation, including measures of infectious exposures in infancy (presence of older siblings, daycare attendance, ear infections) and breastfeeding. A total of 585 ALL cases and 848 controls were genotyped at the HLA-DPA1 and DPB1 loci. Because of potential heterogeneity in effect by race/ethnicity, we included only non-Hispanic white (47%) and Hispanic (53%) children and considered these 2 groups separately in the analysis. Logistic regression analyses showed an increased risk of ALL associated with HLA-DPB1*01:01 (odds ratio [OR] = 1.43, 95% CI, 1.01-2.04) with no heterogeneity by Hispanic ethnicity (P = .969). Analyses of DPB1 supertypes showed a marked childhood ALL association with DP1, particularly for high-hyperdiploid ALL (OR = 1.83; 95% CI, 1.20-2.78). Evidence of interaction was found between DP1 and older sibling (P = .036), and between DP1 and breastfeeding (P = .094), with both showing statistically significant DP1 associations within the lower exposure categories only. These findings support an immune mechanism in the etiology of childhood ALL involving the HLA-DPB1 gene in the context of an insufficiently modulated immune system.

The role of pDC, recipient T(reg) and donor T(reg) in HSC engraftment: Mechanisms of facilitation

Hematopoietic stem cell transplantation (HSCT) has been utilized for treatment of many hematologic malignancies, genetic and metabolic disorders, and hemoglobinopathies such as sickle cell disease and thalassemia. It also induces donor-specific tolerance to organ and tissue transplants. The widespread success of HSCT is hampered by the toxicities of immunosuppression and development of graft-versus-host disease (GVHD). The mechanism of induction of transplantation tolerance (reciprocal donor/host) is still an elusive challenge in allogeneic HSCT. An understanding of the mechanisms for induction of tolerance and the critical cells involved in this process has resulted in novel cell-based therapies poised to be translated to clinical application. The focus of this review is those cells of interest.Bone marrow-derived plasmacytoid dendritic cells induce naïve T cells to differentiate to become antigen-specific regulatory T cells (T(reg)), creating a milieu for the induction of transplantation tolerance. Recently, CD8(+)/TCR(-) facilitating cells (FC), a novel cell population in mouse bone marrow, have been shown to potently enhance engraftment of allogeneic HSC without causing GVHD. The predominant subpopulation of FC resembles plasmacytoid precursor dendritic cells. FC induce antigen-specific T(reg) in vivo. Notably, FC address one major concern that has prevented the implementation of T(reg) cell therapy in the clinic: to expand T(reg) and have them remain tolerogenic in vivo. FC are novel in that they induce an antigen-specific regulatory milieu in vivo. The discovery of FC has opened new alternatives to expanded criteria in bone marrow transplantation that were previously restricted to human leukocyte antigen-matched recipients. The focus of this review is to cover what is currently known about the mechanism of FC action in inducing tolerance and preventing GVHD and hostversus-graft reactivity.

Cell-autonomous and -non-autonomous roles of CTLA-4 in immune regulation

It is controversial how cytotoxic T lymphocyte antigen (CTLA)-4, a co-inhibitory molecule, contributes to immunological tolerance and negative control of immune responses. Its role as an inducer of cell-intrinsic negative signals to activated effector T cells is well documented. However, there is accumulating evidence that CTLA-4 is essential for the function of naturally occurring Foxp3(+) regulatory T (Treg) cells, which constitutively express the molecule. CTLA-4 deficiency in Foxp3(+) Treg cells indeed impairs their in vivo and in vitro suppressive function. Further, Treg cells can modulate the function of CD80- and CD86-expressing antigen-presenting cells via CTLA-4. Here we discuss how CTLA-4 expression by one T cell can influence the activation of another in a cell non-autonomous fashion and thus control immune responses.

Inflammatory bowel disease

This review focuses on the prominent etiological and pathogenetic aspects of inflammatory bowel disease (IBD), with particular attention being paid to the mucosal immune response to commensal micro-organisms in health and disease. Pathogenetic implications for target therapy will also be discussed. The clinical presentation, diagnostic aspects, and currently recommended therapeutic options for the two main types of IBD are also taken into consideration, including manifestations of these conditions in the oral cavity.

Mechanisms of T-cell migration across the BBB

Under physiological conditions, the highly specialized BBB strictly limits the entrance of immune cells into the CNS. By contrast, in the course of neuroinflammation such as that observed in multiple sclerosis, circulating T cells readily breach the BBB and initiate a cascade of events culminating in disease onset. Lymphocyte extravasation across the BBB occurs through a sequential multistep process, orchestrated by chemokines and cell adhesion molecules that precisely regulate the dynamic interaction of T cells with the endothelial cells forming the BBB. In this article, we will discuss the molecular players triggering the sophisticated process of T-cell migration across the BBB during pathological conditions.

Small-cell lung cancer-associated autoantibodies: potential applications to cancer diagnosis, early detection, and therapy

Small-cell lung cancer (SCLC) is the most aggressive lung cancer subtype and lacks effective early detection methods and therapies. A number of rare paraneoplastic neurologic autoimmune diseases are strongly associated with SCLC. Most patients with such paraneoplastic syndromes harbor high titers of antibodies against neuronal proteins that are abnormally expressed in SCLC tumors. These autoantibodies may cross-react with the nervous system, possibly contributing to autoimmune disease development. Importantly, similar antibodies are present in many SCLC patients without autoimmune disease, albeit at lower titers. The timing of autoantibody development relative to cancer and the nature of the immune trigger remain to be elucidated. Here we review what is currently known about SCLC-associated autoantibodies, and describe a recently developed mouse model system of SCLC that appears to lend itself well to the study of the SCLC-associated immune response. We also discuss potential clinical applications for these autoantibodies, such as SCLC diagnosis, early detection, and therapy.

Cytolytic CD4(+) T cells in viral immunity

It is generally believed that the role of CD4(+) T cells is to coordinate the different arms of the adaptive immune system to shape an effective response against a pathogen and regulate nonessential or deleterious activities. However, a growing body of evidence suggests that effector CD4(+) T cells can directly display potent antiviral activity themselves. The presence of cytolytic CD4(+) T cells has been demonstrated in the immune response to numerous viral infections in both humans and in animal models and it is likely that they play a critical role in the control of viral replication in vivo. This article describes the current research on virus-specific cytolytic CD4(+) T cells, with a focus on HIV-1 infection and the implications that this immune response has for vaccine design.

Abdominal γ-radiation induces an accumulation of function-impaired regulatory T cells in the small intestine

PURPOSE

To assess the frequency and the functional characteristics of one major component of immune tolerance, the CD4(+)FoxP3(+) regulatory T cells (Tregs) in a mouse model of abdominal irradiation.

METHODS AND MATERIALS

Mice were exposed to a single abdominal dose of γ-radiation (10 Gy). We evaluated small intestine Treg infiltration by Foxp3 immunostaining and the functional suppressive activity of Tregs isolated from mesenteric lymph nodes.

RESULTS

Foxp3 immunostaining showed that radiation induced a long-term infiltration of the intestine by Tregs (levels 5.5 times greater than in controls). Co-culture of Tregs from mesenteric lymph nodes with CD4(+) effector cells showed that the Tregs had lost their suppressive function. This loss was associated with a significant decrease in the levels of Foxp3, TGF-β, and CTLA-4 mRNA, all required for optimal Treg function. At Day 90 after irradiation, Tregs regained their suppressive activity as forkhead box P3 (Foxp3), transforming growth factor beta (TGF-β), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression returned to normal. Analysis of the secretory function of mesenteric lymph node Tregs, activated in vitro with anti-CD3/anti-CD28 Abs, showed that this dysfunction was independent of a defect in interleukin-10 secretion.

CONCLUSION

Radiation caused a long-term accumulation of function-impaired Foxp3(+)CD4(+) Tregs in the intestine. Our study provides new insights into how radiation affects the immune tolerance in peripheral tissues.

IL-2: a two-faced master regulator of autoimmunity

CD4(+) T-cell (Th) cytokines provide important regulatory and effector functions of T-cells. Among them, IL-2 plays a unique role. IL-2 is required for the generation and maintenance of regulatory T-cells (Treg) to provide lifelong protection from autoimmune disease. Whether IL-2 is also required for autoimmune disease development is less clear as Il2(-/)(-) mice themselves spontaneously develop multi-organ inflammation (MOI). In this communication, we discuss evidence that support the thesis that IL-2 is required for the development of autoimmune response, although some aspects of autoimmune response are not regulated by IL-2. Potential IL-2-dependent mechanisms operating at specific stages of the inflammation process are presented. The interplays among Treg, IL-2, autoimmune response and adaptive immunity are discussed. Overall, available information indicates that IL-2 is a two-faced master regulator of autoimmunity: one to prevent autoimmunity while the other promotes autoimmune response. The latter is an unfortunate consequence of IL-2 function that is used to promote the adaptive immune response against foreign antigens and pathogens.

T Lymphocyte Activation Profiles in Peripheral Blood of Long-Versus Short-Term Residents of Kuwait: Comparison with Asthmatics

Introduction: During the Arabian Gulf Wars of 1991 and 2003, the resident population of Kuwait sustained heavy exposure to environmental toxicants introduced by military activities. No comprehensive studies have been conducted to assess how exposure to the wartime and postwar environment may have altered the fundamental patterns of immune reactivity among Kuwaitis in ways that affect pathogenesis of disease. This present study addresses this issue by characterising immunological features of asthma and allergies in a Kuwaiti population that is unique and possibly correlates with toxicant exposures. Materials and Methods: Twenty-five long-term residents of Kuwait afflicted with bronchial asthma concurrent with rhinitis; and 2 healthy control groups: 18 long-term residents and 10 newcomers to Kuwait were evaluated by 2- and 3-colour flow cytometry for peripheral blood T cell subpopulation frequencies. Results: Relative to healthy, long-term residents, significantly elevated frequencies of all activated cell phenotypes were observed in the blood of the asthmatic group (P <0.05 to P <0.001), except for CD8+HLA-DR+ cells and a presumed T-regulatory (Treg) subpopulation: CD4+CD25high. The asthmatic group was also observed to have larger populations of CD3+ (pan-T cells), CD4+ (T helper cells) and CD8+ (cytotoxic T cells), CD3+CD56 (NKT-like cells) and CD56+CD16+ (NK cells) compared to healthy long-term residents. Compared to healthy recent immigrants, the blood of long-term residents contained elevated levels of CD3+CD56+ (NK-like), CD4+CD45RA+/CD45RO+ (Naive-to-Memory Transitional), but lower CD4+CD25+high (Treg) (P <0.05). Conclusions: Elevated representation of natural killer (NKT)-like and memory phenotypes may predispose long-term residents towards enhanced susceptibility for airway disease; while at the same time, reducing representation of Treg cells which are protective against airway disease, and this may increase vulnerability to these syndromes among the residents of Kuwait. These results may provide insight into the features of immunopathogenesis of asthma and allergies in Kuwait that arise as a result of the special environment of the country. Key words: Asthma, Immune reactivity, Kuwait, Rhinitis, T cells

Different radiosensitivity of CD4(+)CD25(+) regulatory T cells and effector T cells to low dose gamma irradiation in vitro

PURPOSE

To determine the radiosensitivity difference of human Cluster of Differentiation (CD)4(+)CD25(+) regulatory T cells (Treg) and effector T cells to low dose gamma ray and elucidate the underlying mechanisms in vitro.

MATERIALS AND METHODS

Blood samples were collected from five health subjects and five patients with advanced hepatocellular carcinoma (HCC). Treg and CD4(+)CD25⁻ T cells were selected using magnetic microbeads. The proliferative profiles, cytokine secretion, and differential expressions of apoptosis-related proteins in Treg and CD4(+)CD25⁻ T cells were compared using [³H]-thymidine incorporation, Luminex assay and flow cytometry when treated with various low doses of γ-ray.

RESULTS

A dose-dependent reduction of proliferation in response to irradiation which paralleled the induction of apoptosis existed in Treg and CD4(+)CD25⁻ T cells. Treg were more radiosensitive to low-dose irradiation (0.94 Gray [Gy]) than effector T cells. The interferon-γ (IFNγ) was significantly upregulated and interleukin 10 (IL-10) was significantly downregulated in irradiated Treg. An enhanced immune response to low dose gamma ray existed in the peripheral blood in patients with advanced HCC. Higher levels of active caspase-3, CD95, B cell lymphoma 2 (Bcl-2)-associated X protein (Bax) expression were observed in Treg compared to CD4(+)CD25⁻ T cells. In addition, gamma irradiation activated CD4(+)CD25⁻ T cells to express CD25.

CONCLUSIONS

These studies revealed that Treg were more radiosensitive than CD4(+)CD25⁻ T cells to low dose irradiation. Higher expressions of apoptosis-related proteins such as caspase-3, CD95 and Bax were observed in Treg when compared to CD4(+)CD25⁻ T cells. Our results suggest that treatment with low doses of gamma irradiation may be a viable strategy to enhance immune response in patients with advanced HCC.