Cornerstone of peripheral tolerance: naturally occurring CD4+CD25+ regulatory T cells

Spatial heterogeneity of infiltrating immune cells in the tumor microenvironment of non-small cell lung cancer

Tumor-infiltrating lymphocytes (TILs) are essential components of the tumor microenvironment (TME) of non-small cell lung cancer (NSCLC). Still, it is difficult to describe due to their heterogeneity. In this study, five cell markers from NSCLC patients were analyzed. We segmented tumor cells (TCs) and TILs using Efficientnet-B3 and explored their quantitative information and spatial distribution. After that, we simulated multiplex immunohistochemistry (mIHC) by overlapping continuous single chromogenic IHCs slices. As a result, the proportion and the density of programmed cell death-ligand 1 (PD-L1)-positive TCs were the highest in the core. CD8+ T cells were the closest to the tumor (median distance: 41.71 μm), while PD-1+T cells were the most distant (median distance: 62.2μm), and our study found that most lymphocytes clustered together within the peritumoral range of 10-30 μm where cross-talk with TCs could be achieved. We also found that the classification of TME could be achieved using CD8+ T-cell density, which is correlated with the prognosis of patients. In addition, we achieved single chromogenic IHC slices overlap based on CD4-stained IHC slices. We explored the number and spatial distribution of cells in heterogeneous TME of NSCLC patients and achieved TME classification. We also found a way to show the co-expression of multiple molecules economically.

Treg Cell Therapeutic Strategies for Breast Cancer: Holistic to Local Aspects

Regulatory T cells (Tregs) play a key role in maintaining immune homeostasis and preventing autoimmunity through their immunosuppressive function. There have been numerous reports confirming that high levels of Tregs in the tumor microenvironment (TME) are associated with a poor prognosis, highlighting their role in promoting an immunosuppressive environment. In breast cancer (BC), Tregs interact with cancer cells, ultimately leading to the suppression of immune surveillance and promoting tumor progression. This review discusses the dual role of Tregs in breast cancer, and explores the controversies and therapeutic potential associated with targeting these cells. Researchers are investigating various strategies to deplete or inhibit Tregs, such as immune checkpoint inhibitors, cytokine antagonists, and metabolic inhibition. However, the heterogeneity of Tregs and the variable precision of treatments pose significant challenges. Understanding the functional diversity of Tregs and the latest advances in targeted therapies is critical for the development of effective therapies. This review highlights the latest approaches to Tregs for BC treatment that both attenuate Treg-mediated immunosuppression in tumors and maintain immune tolerance, and advocates precise combination therapy strategies to optimize breast cancer outcomes.

Spatial cell interplay networks of regulatory T cells predict recurrence in patients with operable non-small cell lung cancer

BACKGROUND

The interplay between regulatory T cells (Tregs) and neighboring cells, which is pivotal for anti-tumor immunity and closely linked to patient prognosis, remains to be fully elucidated.

METHODS

Tissue microarrays of 261 operable NSCLC patients were stained by multiplex immunofluorescence (mIF) assay, and the interaction between Tregs and neighboring cells in the tumor microenvironment (TME) was evaluated. Employing various machine learning algorithms, we developed a spatial immune signature to predict the prognosis of NSCLC patients. Additionally, we explored the interplay between programmed death-1/programmed death ligand-1 (PD-1/PD-L1) interactions and their relationship with Tregs.

RESULTS

Survival analysis indicated that the interplay between Tregs and neighboring cells in the invasive margin (IM) and tumor center was associated with recurrence in NSCLC patients. We integrated the intersection of the three algorithms to identify four crucial spatial immune features [P(CD8+Treg to CK) in IM, P(CD8+Treg to CD4) in IM, N(CD4+Treg to CK) in IM, N(CD4+Tcon to CK) in IM] and employed these characteristics to establish SIS, an independent prognosticator of recurrence in NSCLC patients [HR = 2.34, 95% CI (1.53, 3.58), P < 0.001]. Furthermore, analysis of cell interactions demonstrated that a higher number of Tregs contributed to higher PD-L1+ cells surrounded by PD-1+ cells (P < 0.001) with shorter distances (P = 0.004).

CONCLUSION

We dissected the cell interplay network within the TME, uncovering the spatial architecture and intricate interactions between Tregs and neighboring cells, along with their impact on the prognosis of NSCLC patients.

Immunoregulation via Cell Density and Quorum Sensing-like Mechanisms: An Underexplored Emerging Field with Potential Translational Implications

Quorum sensing (QS) was historically described as a mechanism by which bacteria detect and optimize their population density via gene regulation based on dynamic environmental cues. Recently, it was proposed that QS or similar mechanisms may have broader applications across different species and cell types. Indeed, emerging evidence shows that the mammalian immune system can also elicit coordinated responses on a population level to regulate cell density and function, thus suggesting that QS-like mechanisms may also be a beneficial trait of the immune system. In this review, we explore and discuss potential QS-like mechanisms deployed by the immune system to coordinate cellular-level responses, such as T cell responses mediated via the common gamma chain (γc) receptor cytokines and the aryl hydrocarbon receptors (AhRs). We present evidence regarding a novel role of QS as a multifunctional mechanism coordinating CD4⁺ and CD8⁺ T cell behavior during steady state and in response to infection, inflammatory diseases, and cancer. Successful clinical therapies such as adoptive cell transfer for cancer treatment may be re-evaluated to harness the effects of the QS mechanism(s) and enhance treatment responsiveness. Moreover, we discuss how signaling threshold perturbations through QS-like mediators may result in disturbances of the complex crosstalk between immune cell populations, undesired T cell responses, and induction of autoimmune pathology. Finally, we discuss the potential therapeutic role of modulating immune-system-related QS as a promising avenue to treat human diseases.

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.

Role of the Immune System Elements in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a relatively rare disease, but, today, its incidence tends to increase. The severe course of the disease and poor patient survival rate make PAH a major diagnostic and therapeutic challenge. For this reason, a thorough understanding of the pathogenesis of the disease is essential to facilitate the development of more effective therapeutic targets. Research shows that the development of PAH is characterized by a number of abnormalities within the immune system that greatly affect the progression of the disease. In this review, we present key data on the regulated function of immune cells, released cytokines and immunoregulatory molecules in the development of PAH, to help improve diagnosis and targeted immunotherapy.

Epigenetic mechanisms shape the underlining expression regulatory mechanisms of the STAT3 in multiple sclerosis disease

Objectives

Immunological tolerance is mediated by CD4⁺CD25⁺ regulatory T (Treg) cells. Studies have shown that thymic and peripheral generations of Treg cells depend on the CD28 signaling pathway. T helper 17 (Th17) cells are involved in the pathophysiology of various inflammatory diseases. Cytokines, such as interleukin (IL)-6 and TGF-β, regulate the reciprocal development of Th17 and Treg cells. In CD4⁺ T cells, signal transducer and activator of transcription 3 (STAT3) play a critical role in the induction of Th17 cell differentiation and inhibition of Treg cell development.

Results

In this study, we investigated the STAT3 methylation and gene expression status in patients with MS. Our study demonstrated that the level of STAT3 methylation decreased in relapsing–remitting MS patient compared to control groups, which the decreases were statistically significant. STAT3 gene expression increased in patient group relative to healthy one, and the increases were found to be statistically significant. According to our findings, it can be suggested that DNA hypermethylation of STAT3 affects the gene expression. In addition, there is a strong and significant negative correlation between the methylation status and mRNA level of STAT3.

LC3B in Malignant Cells Correlates With Immune Infiltrate in Hypopharyngeal Squamous Cell Carcinoma

The objective of this study was to investigate the between autophagy activity and local immune response in hypopharyngeal squamous cell carcinoma (HSCC). Herein, we observed the expression of autophagy marker microtubule-associated protein light chain 3B (MAP1LC3B), CD8 cytotoxic T lymphocytes (CTLs), CD39 (regulatory T cells Tregs) and CD163 (tumor-associated macrophages TAMs) in HSCC, and determined the prognostic roles of CD8⁺/CD39⁺ and CD8⁺/CD163⁺ in patients with HSCC. The expression of light chain 3B (LC3B) and CD8⁺/CD39⁺ was found to be significantly lower in HSCC tissues than in adjacent non-tumor mucosa tissue samples; LC3B expression was positively correlated with the infiltration rate of CD8⁺/CD39⁺ in HSCC. Further studies revealed that the ratio of CD8⁺/CD39⁺ immune cells was negatively correlated with tumor lymph node metastasis and TNM classification, while the ratio of CD8⁺/CD163⁺ immune cells was negatively correlated with TNM classification. Moreover, the expression of LC3B was analyzed and the patients were grouped according to their immune infiltration characteristics. The 5-year cumulative survival rates of LC3B⁺, CD8⁺/CD39⁺, and CD8⁺/CD163⁺ patients were significantly higher than those of other group patients. Collectively, our studies indicated that the expression of LC3B in HSCC was correlated with the infiltration ratio of immune cells, and a change in autophagy activity may affect the cellular immunity in HSCC. The ratios of tCD8⁺/CD39⁺ and tCD8⁺/CD163⁺ may serve as prognostic factors for HSCC.

Adoptive transfer of type 1 regulatory T cells suppressed the development of airway hyperresponsiveness in ovalbumin-induced airway inflammation model mice

Type 1 regulatory T (Tr1) cells are CD4⁺ T cells that produce a large amount of IL-10, an anti-inflammatory cytokine. However, it has not been fully elucidated whether Tr1 cells suppress allergic asthma. In this study, the effects of adoptive transfer of in vitro-induced Tr1 cells on allergic asthma were evaluated. Splenocytes from ovalbumin (OVA)-sensitized BALB/c mice were cultured with OVA, IL-21, IL-27, and TGF-β. After culture, IL-10-producing CD4⁺ T cells were isolated by Dynabeads mouse CD4 and IL-10 secretion assay, and analyzed by flow cytometry. Purified Tr1 cells (IL-10⁺ CD4⁺ T cells) were intravenously injected into OVA-sensitized BALB/c mice. The recipient mice were intratracheally challenged with OVA. Airway hyperresponsiveness to methacholine was assessed by the forced oscillation technique, followed by bronchoalveolar lavage (BAL). Almost all of the induced IL-10-producing CD4⁺ T cells were negative for interferon-γ, IL-4, IL-17A, and forkhead box P3, suggesting that the cells were Tr1 cells. The adoptive transfer of Tr1 cells significantly suppressed the development of airway hyperresponsiveness, and increases in IL-5, eosinophils, and neutrophils in BAL fluid. In conclusion, we demonstrated that Tr1 cells suppressed allergic asthma in mice.

[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.

Epstein-Barr virus-positive pyothorax-associated lymphoma expresses CCL17 and CCL22 chemokines that attract CCR4-expressing regulatory T cells

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphomas associated with chronic inflammation (DLBCL-CI) develop in patients with chronic inflammation but without any predisposing immunodeficiency. Given the expression of the EBV latent genes, DLBCL-CI should have mechanisms for evasion of host antitumor immunity. EBV-positive pyothorax-associated lymphoma (PAL) is a prototype of DLBCL-CI and may provide a valuable model for the study of immune evasion by DLBCL-CI. This study demonstrates that PAL cell lines express and secrete CCL17 and/or CCL22 chemokines, the ligands of C-C motif chemokine receptor 4 (CCR4), in contrast to EBV-negative DLBCL cell lines. Accordingly, culture supernatants of PAL cell lines efficiently attracted CCR4-positive regulatory T (Treg) cells in human peripheral blood mononuclear cells. PAL cells injected into mice also attracted CCR4-expressing Treg cells. Furthermore, this study confirmed that CCR4-expressing Treg cells were abundantly present in primary PAL tissues. Collectively, these findings provide new insight into the mechanisms of immune evasion by PAL, and further studies are warranted on whether such mechanisms eventually lead to the development of DLBCL-CI.

Dopamine inhibits human CD8+ Treg function through D1-like dopaminergic receptors

CD8+ T regulatory/suppressor cells (Treg) affect peripheral tolerance and may be involved in autoimmune diseases as well as in cancer. In view of our previous data showing the ability of DA to affect adaptive immune responses, we investigated the dopaminergic phenotype of human CD8+ Treg as well as the ability of DA to affect their generation and activity. Results show that CD8+ T cells express both D₁-like and D₂-like dopaminergic receptors (DR), tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of DA, and vesicular monoamine transporter (VMAT) 2 and contain high levels of intracellular DA. Preferential upregulation of DR mRNA levels in the CD8+CD28- T cell compartment occurs during generation of CD8+ Treg, which is reduced by DA and by the D₁-like DR agonist SKF-38393. DA and SKF-38393 also reduce the suppressive activity of CD8+ Treg on human peripheral blood mononuclear cells. Treg are crucial for tumor escape from the host immune system, thus the ability of DA to inhibits Treg function supports dopaminergic pathways as a druggable targets to develop original and innovative antitumor strategies.

Utilization of leukapheresis and CD4 positive selection in Treg isolation and the ex-vivo expansion for a clinical application in transplantation and autoimmune disorders

Adoptive transfer of T regulatory cells (Tregs) is of great interest as a novel immunosuppressive therapy in autoimmune disorders and transplantation. Obtaining a sufficient number of stable and functional Tregs generated according to current Good Manufacturing Practice (cGMP) requirements has been a major challenge in introducing Tregs as a clinical therapy. Here, we present a protocol involving leukapheresis and CD4⁺ cell pre-enrichment prior to Treg sorting, which allows a sufficient number of Tregs for a clinical application to be obtained. With this method there is a decreased requirement for ex-vivo expansion. The protocol was validated in cGMP conditions. Our final Treg product passed all release criteria set for clinical applications. Moreover, during expansion Tregs presented their stable phenotype: percentage of CD4⁺CD25^hiCD127⁻ and CD4⁺FoxP3⁺ Tregs was > 95% and > 80%, respectively, and Tregs maintained proper immune suppressive function in vitro. Our results suggest that utilization of leukapheresis and CD4 positive selection during Treg isolation improves the likelihood of obtaining a sufficient number of high quality Treg cells during subsequent ex-vivo expansion and they can be applied clinically.

ImmunoMap: A Bioinformatics Tool for T-cell Repertoire Analysis

Despite a dramatic increase in T-cell receptor (TCR) sequencing, few approaches biologically parse the data in a fashion that both helps yield new information about immune responses and may guide immunotherapeutic interventions. To address this issue, we developed a method, ImmunoMap, that utilizes a sequence analysis approach inspired by phylogenetics to examine TCR repertoire relatedness. ImmunoMap analysis of the CD8 T-cell response to self-antigen (K^b-TRP2) or to a model foreign antigen (K^b-SIY) in naïve and tumor-bearing B6 mice showed differences in the T-cell repertoire of self- versus foreign antigen-specific responses, potentially reflecting immune pressure by the tumor, and also detected lymphoid organ-specific differences in TCR repertoires. When ImmunoMap was used to analyze clinical trial data of tumor-infiltrating lymphocytes from patients being treated with anti-PD-1, ImmunoMap, but not standard TCR sequence analyses, revealed a clinically predicative signature in pre- and posttherapy samples. Cancer Immunol Res; 6(2); 151-62. ©2017 AACR.

Morphine and ketamine inhibit immune function of gastric cancer patients by increasing percentage of CD4(+)CD25(+)Foxp3(+) regulatory T cells in vitro

BACKGROUND

There is conflicting evidence regarding effects of anesthetic and analgesic drugs on immune function of cancer patients. This study was designed to observe changes of T cell subpopulations in the gastric cancer (GC) patients and to assess effects of morphine and ketamine on the CD4(+) T cells, CD8(+) T cells, and regulatory T cells (Tregs) populations obtained from the GC patients in vitro.

METHODS

The peripheral blood samples from 20 GC patients and 20 healthy volunteers were obtained. The peripheral blood mononuclear cells were isolated and incubated in a solution containing phorbol-myristate-acetate and ionomycin (2 μL/mL) in the presence or absence of morphine (50 ng/mL) or different-concentration ketamine (25, 50, and 100 μM). The CD4(+) T cells, CD8(+) T cells, and Tregs were determined using the flow cytometric assay.

RESULTS

The percentages of CD8(+) T cells were significantly decreased, but the ratio of CD4(+)/CD8(+) T cells and Tregs populations was significantly increased in the GC control group compared with the normal control group (P < 0.05). The ratio of CD4(+)/CD8(+) T cells was significantly increased in the groups M and K3 compared with the control group (P < 0.05) but was significantly decreased in the group K1 compared with the group K3. The percentage of Tregs was significantly increased in the groups M, K1, K2, and K3 compared with the control group. With the increased concentrations, ketamine increased the number of Tregs.

CONCLUSIONS

GC shifts the balance of CD4(+)/CD8(+) T cells toward CD4(+) T cells and increases the Tregs populations by inducing immune responses. Morphine increases the ratio of CD4(+)/CD8(+) T cells and Tregs populations. Ketamine affects the ratio of CD4(+)/CD8(+) T cells and Tregs populations in a dose-dependent model.

Cell-to-cell distances between tumor-infiltrating inflammatory cells have the potential to distinguish functionally active from suppressed inflammatory cells

Beyond their mere presence, the distribution pattern of inflammatory cells is of special interest. Our hypothesis was that random distribution may be a clear indicator of being non-functional as a consequence of lack of interaction. Here, we have assessed the implication of cell-to-cell distances among inflammatory cells in anal squamous cell carcinoma and a possible association with survival data. Thirty-eight patients suffering from anal carcinoma were studied using tissue microarrays, double staining immunohistochemistry, whole slide scanning and image analysis software. Therapy consisted of concurrent radiochemotherapy. Numbers of stromal and intraepithelial tumor-infiltrating inflammatory cells (TIC) and the distances between cells were quantified. Double-staining of FoxP3(+) cells with either CD8(+), CD1a(+) or CD20(+) cells was performed. Measured cell-to-cell distances were compared to computer simulated cell-to-cell distances leading to the assumption of non-randomly distributed and therefore functional immune cells. Intraepithelial CD1a(+) and CD20(+) cells were randomly distributed and therefore regarded as non-functional. In contrary, stromal CD20(+) cells had a non-random distribution pattern. A non-random distance between CD20(+) and FoxP3(+) cells was associated with a clearly unfavorable outcome. Measured distances between FoxP3(+) cells were distinctly shorter than expected and indicate a functional active state of the regulatory T cells (Treg). Analysis of cell-to-cell distances between TIC has the potential to distinguish between suppressed non-functional and functionally active inflammatory cells. We conclude that in this tumor model most of the CD1a(+) cells are non-functional as are the intraepithelial CD20(+) cells, while stromal CD20(+) cells and FoxP3(+) cells are functional cells.

CD4+CD25+CD127 regulatory cells play multiple roles in maintaining HIV-1 p24 production in patients on long-term treatment: HIV-1 p24-producing cells and suppression of anti-HIV immunity

BACKGROUND

A major question when attempting to eradicate and treat HIV-1 infection is how to reactivate latent proviruses. Stimulating HIV-1-specific cytolytic T lymphocytes (CTL) has been shown to facilitate the elimination of the latent viral reservoir after viral reactivation. Regulatory T (Treg) cells are known to be capable of lowering both HIV-specific immunoreactions and general immune activation during HIV-1 infection. It was hypothesized that the depletion of Treg cells could increase the HIV-1-specific cytolytic T lymphocyte response and reactivate HIV-1 p24 production.

METHODS

Treg cells were isolated by isolation kit according to the surface marker of Treg cells. Real-time PCR method was used to quantify HIV-1 DNA. P24 antigens in the cell culture supernatant was done by ELISA. Cells activation and HIV specific HIV-1 CD8+ T cells were analyses using a FACSCalibur flow cytometer and CELLQUEST software.

RESULTS

This study included both HIV-infected patients who were antiviral treatment-naïve and patients with sustained viral responses to antiretroviral therapy (ART) for 1 or 5 years. It was found that the HIV-DNA levels in Treg cells were approximately 10-fold higher than those in non-Treg CD4+ cells and that the depletion of Treg cells could enhance the frequency of HIV-1-specific CTL and immune activation after 5 years of effective ART.

CONCLUSIONS

CD4+CD25+CD127 regulatory cells play multiple roles in maintaining HIV-1 p24 production in long-term ART patients. Treg cells may be a target for eliminating the latent HIV reservoir after effective long-term ART.

IL-35 expression in peripheral blood CD4(+) T cells from chronic hepatitis B virus-infected patients directly correlates with virus load

Interleukin 35 (IL-35) functions in an anti-inflammatory fashion by inhibiting T-cell proliferation, whereas CD4(+) T cells play an important role in cellular immunity. In a hepatitis B virus (HBV) infection, the viral proteins stimulate the immune system to generate antiviral molecules, which correlate to HBV DNA load. We investigated the impact of HBV DNA load on the expression of IL-35 mRNA in CD4(+) T cells, and the expression of IL-35 cytokine in serum of the patients with chronic HBV infection. Here we report that the frequency of circulating CD4(+) T cells correlates with the HBV DNA load in the serum of chronic hepatitis B (CHB) patients. An increased number of CD4(+) T cells were found in those patients with higher levels of HBV DNA. Regulatory T cells (T regs) also showed this trend, but circulating cytotoxic lymphocytes (CTLs) showed a negative correlation with serum HBV DNA load. In addition, significantly more IL-35 mRNA was found in the CD4(+) T cells of CHB patients, compared to healthy controls. Patients in the high viral load group showed increased levels of IL-35 mRNA, compared with those in the low viral load group. The level of IL-35 cytokine in the serum of CHB patients was significantly higher than in the healthy controls and in those infected with HBV, the patients with a higher viral load had more serum IL-35 cytokines, compared to those with a lower viral load. Our study suggests that increased serum IL-35 could be directly related to increased levels of IL-35 mRNA in CD4(+) T cells and HBV DNA load in CHB patients. The possible role of IL-35 as an immune regulator in chronic HBV infection should be investigated further.

Sertoli cells--immunological sentinels of spermatogenesis

Testicular germ cells, which appear after the establishment of central tolerance, express novel cell surface and intracellular proteins that can be recognized as 'foreign antigens' by the host's immune system. However, normally these germ cells do not evoke an auto-reactive immune response. The focus of this manuscript is to review the evidence that the blood-testis-barrier (BTB)/Sertoli cell (SC) barrier along with the SCs ability to modulate the immune response is vital for protecting auto-antigenic germ cells. In normal testis, the BTB/SC barrier protects the majority of the auto-antigenic germ cells by limiting access by the immune system and sequestering these 'new antigens'. SCs also modulate testis immune cells (induce regulatory immune cells) by expressing several immunoregulatory factors, thereby creating a local tolerogenic environment optimal for survival of nonsequesetred auto-antigenic germ cells. Collectively, the fortress created by the BTB/SC barrier along with modulation of the immune response is pivotal for completion of spermatogenesis and species survival.

Critical role of spatial interaction between CD8⁺ and Foxp3⁺ cells in human gastric cancer: the distance matters

PURPOSE

In various cancer types, an abundance of FoxP3(+) regulatory T cells (Treg) has been associated with an unfavorable outcome. Yet, the role of Treg on cancer immunity has been shown to be complex. In single cell marker technique, other tumor-infiltrating lymphocytes (TILs) such as cytotoxic CD8(+) T cells (CTL) also influenced prognosis. This study for the first time investigates the concurrent spatial distribution pattern of CD8(+) and FoxP3(+) TILs and their prognostic impact in human gastric cancer.

MATERIALS AND METHODS

Tumor tissue microarrays of 50 patients with surgically treated adenocarcinoma of the cardia were studied. An immunohistochemical double staining of CD8(+) and FoxP3(+) TILs was performed. Cell counts and cell-to-cell distances in tumor epithelium and stroma were evaluated with image-processing software. Metastasis-free survival, no-evidence-of-disease survival, and overall survival were investigated (mean follow-up time 6.9 years).

RESULTS

High intraepithelial infiltration of CD8(+) and FoxP3(+) TIL was associated with the improved 10-year metastasis-free survival (83 vs. 54%, p = 0.04 and 85 vs. 59%, p = 0.09, respectively). Considering cell-to-cell distance and comparing patients with functional (30-110 μm) versus nonfunctional distances of CD8(+) and FoxP3(+) TILs, 10-year survival rates differed between 89 and 55% (p = 0.009), respectively.

CONCLUSION

Prognostic influence of tumor-infiltrating immune cells in gastric cancer critically depends on their cell-to-cell distance. FoxP3(+) TILs must be located within a distance between 30 and 110 μm of CD8(+) T cells to positively impact on prognosis.

The anti-tumor effect and increased tregs infiltration mediated by rAAV-SLC vector

To explore the anti-tumor effect and immune mechanism mediated by a new recombinant adeno-associated virus (rAAV) encoding secondary lymphoid tissue chemokine (SLC) mature peptide gene. AAV Helper-Free system was used for rAAV-SLC package. The anti-tumor effect of SLC was detected by bearing tumor established from Hepal-6 cells both in C57BL/6J and nude mice. Flow cytometry analysis and IHC for Tumor-infiltrating T cells and CD11c+DCs were also investigated to explore the immunological mechanism. rAAV-SLC was successfully packaged in AAV293 cells and transfected Hepal-6 tumor cells at high efficiency. The anti-tumor effect was demonstrated by less tumor weight and longer survival outcome. Coincident with the anti-tumor response, local elaboration of SLC within the tumor bed elicited a heavy infiltration of CD4+, CD8+T cells and CD11c+ dendritic cells into the tumor sites. More importantly, there was higher infiltration of Foxp3+ regulatory T cells (Tregs). Local elaboration of SLC mediated by rAAV-SLC has strong T cell mediated anti-tumor effect. The study also suggested that Tregs in the tumor microenvironment tampered the anti-tumor effect.

Assessment of changes in immune measures of multiple sclerosis patients treated with laquinimod

Laquinimod is a novel orally active agent with immunomodulatory properties that was shown to be effective in suppressing disease activity in relapsing-remitting multiple sclerosis patients. Though many mechanisms of action of laquinimod have been described, little is known about the in vivo effects of laquinimod on the functionality of circulating human peripheral blood mononuclear cell populations. We assessed both phenotypical and functional measures of PBMC in a prospective longitudinal analysis comparing laquinimod and placebo treated cohorts. We determined that there were no significant changes in the relative proportion of T-cells, B-cells, monocytes & macrophages, NK-cells, dendritic cells or FoxP3(+) CD25(hi) T-regs in laquinimod treated patients. There were also no significant differences in the proliferative response to PHA or tetanus antigen, or in the inflammatory cytokine bias of these responses. These data demonstrated that there were no significant changes in immune function of PBMC in patients receiving two years of continuous laquinimod therapy who retained a full complement of the major populations of circulating PBMC and retained their capacity to respond to immunologic stimuli.

PLG scaffold delivered antigen-specific regulatory T cells induce systemic tolerance in autoimmune diabetes

Islet transplantation is a promising treatment for human type 1 diabetes mellitus. Transplantation requires systemic immunosuppression, which has numerous deleterious side effects. Islet antigen-specific regulatory T cells (Tregs) have been shown to protect islet grafts from autoimmune destruction in the nonobese diabetic (NOD) model when co-localized in the kidney capsule. An extra-hepatic transplant site was established by transplanting islet-loaded microporous poly (lactide-co-glycolide) (PLG) scaffolds into abdominal fat. This study examined an autoimmune transplantation model and determined whether co-localized Tregs could protect islet grafts in an extra-hepatic and extra-renal transplant site. Normoglycemia was restored, and co-transplanted Tregs extended graft survival, including several instances of indefinite protection. Transplanted Tregs were replaced by recipient-derived Tregs over time, indicating that islet antigen-specific Tregs induce tolerance to islet grafts through host-derived Tregs. Thus, Tregs provided protection against a diverse repertoire of autoreactive T-cell-receptor specificities mediating diabetes in the NOD model, possibly through a phenomenon previously described as infectious tolerance. Interestingly, the infiltration by Tregs protected a second islet transplant, indicating systemic tolerance to islet antigens. In summary, PLG scaffolds can serve as an alternative delivery system for islet transplantation that allows for the co-localization of immunomodulatory cells within islet grafts and induces long-term graft survival in an autoimmune diabetes model. This method of co-localizing immunomodulatory cells with islets in a clinically translatable transplant site to affect the immune system on a local and systemic level has potential therapeutic implications for human islet transplantation.

Protection conferred by heterologous vaccination against tuberculosis is dependent on the ratio of CD4(+) /CD4(+) Foxp3(+) cells

CD4(+) Foxp3(+) regulatory T cells inhibit the production of interferon-γ, which is the major mediator of protection against Mycobacterium tuberculosis infection. In this study, we evaluated whether the protection conferred by three different vaccines against tuberculosis was associated with the number of spleen and lung regulatory T cells. We observed that after homologous immunization with the 65 000 molecular weight heat-shock protein (hsp 65) DNA vaccine, there was a significantly higher number of spleen CD4(+) Foxp3(+) cells compared with non-immunized mice. Heterologous immunization using bacillus Calmette-Guérin (BCG) to prime and DNA-hsp 65 to boost (BCG/DNA-hsp 65) or BCG to prime and culture filtrate proteins (CFP)-CpG to boost (BCG/CFP-CpG) induced a significantly higher ratio of spleen CD4(+) /CD4(+) Foxp3(+) cells compared with non-immunized mice. In addition, the protection conferred by either the BCG/DNA-hsp 65 or the BCG/CFP-CpG vaccines was significant compared with the DNA-hsp 65 vaccine. Despite the higher ratio of spleen CD4(+) /CD4(+) Foxp3(+) cells found in BCG/DNA-hsp 65-immunized or BCG/CFP-CpG-immunized mice, the lungs of both groups of mice were better preserved than those of DNA-hsp 65-immunized mice. These results confirm the protective efficacy of BCG/DNA-hsp 65 and BCG/CFP-CpG heterologous prime-boost vaccines and the DNA-hsp 65 homologous vaccine. Additionally, the prime-boost regimens assayed here represent a promising strategy for the development of new vaccines to protect against tuberculosis because they probably induce a proper ratio of CD4(+) and regulatory (CD4(+) Foxp3(+) ) cells during the immunization regimen. In this study, this ratio was associated with a reduced number of regulatory cells and no injury to the lungs.

Dendritic cells control CD4+CD25+ Treg cell suppressor function in vitro through juxtacrine delivery of IL-2

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) restrict inflammatory responses to self and nonself. Aberrant Treg activity is pathologic: Insufficient Treg activity is implicated in autoimmunity, allergy, and graft-versus-host-disease; overabundant activity is implicated in chronic infection and cancer. Tregs require IL-2 for their expansion and acquisition/execution of suppressor function; however, because Tregs cannot produce IL-2, they depend on IL-2 from an exogenous source. Until now, that IL-2 source had not been established. We asked whether dendritic cells (DCs) could supply IL-2 to Tregs and, if so, what was required for that delivery. We used flow cytometry, IL-2 ELISPOT, RT-qPCR, and IL-2 promoter-driven reporter assays to measure intracytoplasmic IL-2, secreted protein, IL-2 message and IL-2 promoter activity in bone marrow-derived (BMDC) and splenic DCs. We examined conjugate formation between Tregs, conventional CD4(+) cells, and IL-2-expressing DCs. We measured Treg levels of CD25, Foxp3, and suppressor function after co-culture with IL-2 sufficient and IL-2(-/-) DCs. We generated IL-2-mCherry-expressing DCs and used epifluorescence microscopy and flow cytometry to track IL-2 transfer to Tregs and test requirements for transfer. Between 0.7 to 2.4% of DCs constitutively produced IL-2 and diverted IL-2 secretion to Tregs by preferentially forming conjugates with them. Uptake of DC IL-2 by Tregs required cell-cell contact and CD25. Tregs increased levels of CD25 and Foxp3 from baseline and showed greater suppressor function when co-cultured with IL-2-sufficient DCs, but not when co-cultured with IL-2(-/-) DCs. Exogenous IL-2, added in excess of 500 U/ml to co-cultures with IL-2(-/-) DCs, restored Treg suppressor function. These data support a model of juxtacrine delivery of IL-2 from DCs to Tregs and suggest that a subset of DCs modulates Treg function through controlled, spatial delivery of IL-2. Knowledge of how DCs regulate Tregs should be integrated into the design of interventions intended to alter Treg function.

Regulatory T-cells in chronic lymphocytic leukemia and autoimmune diseases

Regulatory T-cells (Tregs) constitute a small subset of cells that are actively involved in maintaining self-tolerance, in immune homeostasis and in antitumor immunity. They are thought to play a significant role in the progression of cancer and are generally increased in patient with chronic lymphocytic leukemia (CLL). Their number correlates with more aggressive disease status and is predictive of the time to treatment, as well. Moreover, it is now clear that dysregulation in Tregs cell frequency and/or function may result in a plethora of autoimmune diseases, including multiple sclerosis, type 1 diabetes mellitus, myasthenia gravis, systemic lupus erythematosus, autoimmune lymphoproliferative disorders, rheumatoid arthritis, and psoriasis. Efforts are made aiming to develop approaches to deplete Tregs or inhibit their function in cancer and autoimmune disorders, as well.

Autoimmune dysregulation and purine metabolism in adenosine deaminase deficiency

Genetic defects in the adenosine deaminase (ADA) gene are among the most common causes for severe combined immunodeficiency (SCID). ADA-SCID patients suffer from lymphopenia, severely impaired cellular and humoral immunity, failure to thrive, and recurrent infections. Currently available therapeutic options for this otherwise fatal disorder include bone marrow transplantation (BMT), enzyme replacement therapy with bovine ADA (PEG-ADA), or hematopoietic stem cell gene therapy (HSC-GT). Although varying degrees of immune reconstitution can be achieved by these treatments, breakdown of tolerance is a major concern in ADA-SCID. Immune dysregulation such as autoimmune hypothyroidism, diabetes mellitus, hemolytic anemia, and immune thrombocytopenia are frequently observed in milder forms of the disease. However, several reports document similar complications also in patients on long-term PEG-ADA and after BMT or GT treatment. A skewed repertoire and decreased immune functions have been implicated in autoimmunity observed in certain B-cell and/or T-cell immunodeficiencies, but it remains unclear to what extent specific mechanisms of tolerance are affected in ADA deficiency. Herein we provide an overview about ADA-SCID and the autoimmune manifestations reported in these patients before and after treatment. We also assess the value of the ADA-deficient mouse model as a useful tool to study both immune and metabolic disease mechanisms. With focus on regulatory T- and B-cells we discuss the lymphocyte subpopulations particularly prone to contribute to the loss of self-tolerance and onset of autoimmunity in ADA deficiency. Moreover we address which aspects of immune dysregulation are specifically related to alterations in purine metabolism caused by the lack of ADA and the subsequent accumulation of metabolites with immunomodulatory properties.

The impact of CD4+ CD25+ T cells in the tumor microenvironment of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common liver cancer. Therapeutic results are usually unsatisfactory because liver tumors recur often. Immunologic factors may be related to the recurrence of HCC; however, this possibility is mentioned only rarely.

METHODS

Thirty HCC patients undergoing hepatectomies were divided into 3 groups according to the diameters of their HCCs: group A (n = 8), diameter ≤3 cm; group B (n = 8), diameter >3 cm and ≤5 cm; and group C (n = 14), diameter >5 cm. T-lymphocytes from peripheral blood, nontumor liver tissue, and the HCC were analyzed.

RESULTS

The percentage of CD25+ in the CD4+ T cells did not differ between the peripheral blood and the nontumor liver tissue among the 3 groups. CD25+ cells were increased in the tumor tissue in group C patients (range, 6-41%; median, 22.9%; P = .003), compared to group A patients. The percentage of CD25+ in the CD4+ T cells in tumor tissue was positively correlated with tumor sizes (r = 0.556). These CD4+ CD25+ lymphocytes produced transforming growth factor-β and interferon-γ but not interleukin-10, and were anergic to plate-coated monoclonal antibodies (anti-CD3/anti-CD28). The characteristics of these antibodies were comparable to those of regulatory T cells. When the infiltration lymphocytes including CD4+ CD25+ T cells were added to the mixed lymphocyte reaction activated by autologous tumor lysate-pulsed dendritic cells, the proliferation of lymphocytes was inhibited.

CONCLUSION

The increase of CD4+ CD25+ T cells in the tumor microenvironment correlates with tumor sizes. These CD4+ CD25+ regulatory T cells appeared to suppress the immune response activated by dendritic cells.

Advancing islet transplantation: from engraftment to the immune response

The promise and progress of islet transplantation for treating type 1 diabetes has been challenged by obstacles to patient accessibility and long-term graft function that may be overcome by integrating emerging technologies in biomaterials, drug delivery and immunomodulation. The hepatic microenvironment and traditional systemic immunosuppression stress the vulnerable islets and contribute to the limited success of transplantation. Locally delivering extracellular matrix proteins and trophic factors can enhance transplantation at extrahepatic sites by promoting islet engraftment, revascularisation and long-term function while avoiding unintended systemic effects. Cell- and cytokine-based therapies for immune cell recruitment and reprogramming can inhibit local and systemic immune system activation that normally attacks transplanted islets. Combined with antigen-specific immunotherapies, states of operational tolerance may be achievable, reducing or eliminating the long-term pharmaceutical burden. Integration of these technologies to enhance engraftment and combat rejection may help to advance the therapeutic efficacy and availability of islet transplantation.

Sensitization to gliadin induces moderate enteropathy and insulitis in nonobese diabetic-DQ8 mice

Celiac disease (CD) is frequently diagnosed in patients with type 1 diabetes (T1D), and T1D patients can exhibit Abs against tissue transglutaminase, the auto-antigen in CD. Thus, gliadin, the trigger in CD, has been suggested to have a role in T1D pathogenesis. The objective of this study was to investigate whether gliadin contributes to enteropathy and insulitis in NOD-DQ8 mice, an animal model that does not spontaneously develop T1D. Gliadin-sensitized NOD-DQ8 mice developed moderate enteropathy, intraepithelial lymphocytosis, and barrier dysfunction, but not insulitis. Administration of anti-CD25 mAbs before gliadin-sensitization induced partial depletion of CD25(+)Foxp3(+) T cells and led to severe insulitis, but did not exacerbate mucosal dysfunction. CD4(+) T cells isolated from pancreatic lymph nodes of mice that developed insulitis showed increased proliferation and proinflammatory cytokines after incubation with gliadin but not with BSA. CD4(+) T cells isolated from nonsensitized controls did not response to gliadin or BSA. In conclusion, gliadin sensitization induced moderate enteropathy in NOD-DQ8 mice. However, insulitis development required gliadin-sensitization and partial systemic depletion of CD25(+)Foxp3(+) T cells. This humanized murine model provides a mechanistic link to explain how the mucosal intolerance to a dietary protein can lead to insulitis in the presence of partial regulatory T cell deficiency.

Making sense of regulatory T cell suppressive function

Several types of regulatory T cells maintain self-tolerance and control excessive immune responses to foreign antigens. The major regulatory T subsets described over the past decade and novel function in transplantation will be covered in this review with a focus on CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells. Multiple mechanisms have been proposed to explain how Treg cells inhibit effector cells but none can completely explain the observed effects in toto. Proposed mechanisms to explain suppressive activity of Treg cells include the generation of inhibitory cytokines, induced death of effector cells by cytokine deprivation or cytolysis, local metabolic perturbation of target cells mediated by changes in extracellular nucleotide/nucleoside fluxes with alterations in intracellular signaling molecules such as cyclic AMP, and finally inhibition of dendritic cell functions. A better understanding of how Treg cells operate at the molecular level could result in novel and safer therapeutic approaches in transplantation and immune-mediated diseases.

Increased frequency of CD4+CD25(high)FoxP3+ regulatory T cells in patients with hepatocellular carcinoma

Accumulating evidence suggests regulatory T cells (Tregs) are associated with impaired antitumor responses. However, the relationship between the CD4(+)CD25(high)FoxP3(+) Treg and hepatocellular carcinoma (HCC) has not been well investigated. Levels of CD4(+)CD25(high)FoxP3(+) Tregs in peripheral blood mononuclear cells (PBMCs) from HCC patients and healthy donors, tumor infiltrating lymphocytes (TILs) extracted from HCC, and hepatic lymphocytes extracted from resected liver were measured by flow cytometry, and their effects on T-cell proliferation was determined by (3)H-thymidine incorporation. Serum levels of interleukin (IL)-10 and transforming growth factor (TGF)-β1 were measured by enzyme linked immunosorbent assay. The frequency of Tregs in PBMCs from HCC patients was higher than that from healthy donors. Similarly, the frequency of Tregs in TILs was higher than that of hepatic lymphocytes. On the other hand, the (3)H-thymidine uptake by TILs and PBMCs from HCC patients was decreased drastically when compared to the counterparts from normal controls. Furthermore, serum IL-10 and TGF-β1 levels increased significantly in HCC patients when compared to the healthy donors. This study identified an increased frequency of CD4(+)CD25(high)FoxP3(+) Tregs in patients with HCC. The elevated serum IL-10, TGF-β1 levels also correlated with impaired antitumor responses in these patients. Further effort is needed to establish new immunotherapeutic strategies designed to modulate Tregs to promote a competent antitumor response.

T(reg) cells: collection, processing, storage and clinical use

T regulatory cells are fundamental in the maintenance of immune homeostasis and self-tolerance. Experimental models suggest the existence of two functional types of T(reg) cells designated naturally occurring and induced. Interest in T(reg) cells increased with evidence from experimental mouse and human models demonstrating that the immunosuppressive potential of these cells can be utilized in the treatment of various pathological conditions. The existence of a subpopulation of suppressive T cells was the subject of significant controversy among immunologists for many years. T regulatory cells limit immune activation through a variety of direct and indirect interactions, many of which are yet to be determined. Fully understanding T(reg) cells biology will lead us to harnessing the capacity of these cells in order to develop strategies to prevent autoimmune disorders and tolerance to transplantation. Efficient isolation, expansion and cryopreservation strategies that comply with Good Manufacturing Practice (GMP) guidelines are prerequisites for the clinical application of human CD4+ CD25+ CD127(low) FOXP3+ regulatory T cells.

Inflammation in gastric adenocarcinoma of the cardia: how do EBV infection, Her2 amplification and cancer progression influence tumor-infiltrating lymphocytes?

Tumor-infiltrating lymphocytes (TILs) in gastric adenocarcinoma show a strong compartmentalization with high numbers of lymphocytes in the stroma and low intraepithelial lymphocyte counts. Our previous study has shown stromal regulatory T cells (Treg) to be associated with a beneficial outcome in intestinal type cancer of the cardia. We undertook the present study to further evaluate the immunogenic and inflammatory environment in intestinal-type gastric adenocarcinoma of the cardia. We assessed CXCR3 expression, Epstein-Barr virus (EBV) status, Her2/ERBB2 status and overexpression/amplification using tissue microarrays (immunohistochemistry and in situ hybridization) of 52 patients. The data were correlated to different TIL subset counts (CD3, CD8, GranzymeB, FoxP3 and CD20) and to infiltrating histiocytes (CD68) both in the tumor and the surrounding stromal tissue that were reported earlier. Her2/ERBB2 overexpression/amplification showed no correlation to tumor stage. Moreover, for the first time, we show here that Her2/ERBB2 overexpression/amplification has no correlation to overall or subset-specific TIL infiltration. EBV infection was seen in four cases and showed a strong association with intratumoral CD8(+) T cell infiltration as well as a moderate correlation to stromal CD8(+) T cell accumulation. Intratumoral CD8(+) T cell infiltration was significantly correlated to intratumoral FoxP3(+) Treg infiltration, and to a lesser extent, to stromal FoxP3(+) Treg counts. Stromal CXCR3(+) T cell infiltration showed an inverse correlation to T category. This highlights the importance of stromal immune processes for cancer growth and suggests a subversion of Th1 immunoresponse in cancer progression and underlines the important role of inflammation for early carcinogenesis.

Regulation of T cell activation by TLR ligands

Regulatory T cells (Treg) maintain peripheral tolerance and play a critical role in the control of the immune response in infection, tumor defense, organ transplantation and allergy. CD4(+)CD25(high) Treg suppress the proliferation and cytokine production of CD4(+)CD25(-) responder T cells. The suppression requires cell-cell-contact and/or production of inhibitory cytokines like IL-10 or TGF-β. The current knowledge about the regulation of Treg suppressive function is limited. Toll-like receptors (TLR) are widely expressed in the innate immune system. They recognize conserved microbial ligands such as lipopolysaccharide, bacterial lipopeptides or viral and bacterial RNA and DNA. TLR play an essential role in innate immune responses and in the initiation of adaptive immune responses. However, certain TLR are also expressed in T lymphocytes, and the respective ligands can directly modulate T cell function. TLR2, TLR3, TLR5 and TLR9 act as costimulatory receptors to enhance proliferation and/or cytokine production of T-cell receptor-stimulated T lymphocytes. In addition, TLR2, TLR5 and TLR8 modulate the suppressive activity of naturally occurring CD4(+)CD25(high) Treg. The direct responsiveness of T lymphocytes to TLR ligands offers new perspectives for the immunotherapeutic manipulation of T cell responses. In this article we will discuss the regulation of Treg and other T cell subsets by TLR ligands.

IL-17- and IFN-γ-secreting Foxp3+ T cells infiltrate the target tissue in experimental autoimmunity

CD4(+)Foxp3(+) regulatory T cells (Tregs) have been considered crucial in controlling immune system homeostasis, and their derangement is often associated to autoimmunity. Tregs identification is, however, difficult because most markers, including CD25 and Foxp3, are shared by recently activated T cells. We show in this paper that CD4(+)Foxp3(+) T cells are generated in peripheral lymphoid organs on immunization and readily accumulate in the target organ of an autoimmune reaction, together with classical inflammatory cells, constituting up to 50% of infiltrating CD4(+) T cells. Most CD4(+)Foxp3(+) T cells are, however, CD25(-) and express proinflammatory cytokines such as IL-17 and IFN-γ, questioning their suppressive nature. Moreover, in vitro CD4(+) T lymphocytes from naive and autoimmune mice, stimulated to differentiate into Th1, Th2, Th17, and induced Tregs, display early mixed expression of lineage-specific markers. These results clearly point to an unprecedented plasticity of naive CD4(+) T cells, that integrating inflammatory signals may change their fate from the initial lineage commitment to a different functional phenotype.

2-Gy whole-body irradiation significantly alters the balance of CD4+ CD25- T effector cells and CD4+ CD25+ Foxp3+ T regulatory cells in mice

CD4(+)CD25(+) T regulatory (Treg) cells are critical in inducing and maintaining immunological self-tolerance as well as transplant tolerance. The effect of low doses of whole-body irradiation (WBI) on CD4(+)CD25(+)Foxp3(+) Treg cells has not been determined. The proportion, phenotypes and function of CD4(+)CD25(+) Treg cells were investigated 0.5, 5 and 15 days after euthymic, thymectomized or allogeneic bone marrow transplanted C57BL/6 mice received 2-Gy γ-rays of WBI. The 2-Gy WBI significantly enhanced the ratios of CD4(+)CD25(+) Treg cells and CD4(+)CD25(+)Foxp3(+) Treg cells to CD4(+) T cells in peripheral blood, lymph nodes, spleens and thymi of mice. The CD4(+)CD25(+) Treg cells of the WBI-treated mice showed immunosuppressive activities on the immune response of CD4(+)CD25(-) T effector cells to alloantigens or mitogens as efficiently as the control mice. Furthermore, 2-Gy γ-ray WBI significantly increased the percentage of CD4(+)CD25(+)Foxp3(+) Treg cells in the periphery of either thymectomized mice or allogeneic bone marrow transplanted mice. The in vitro assay showed that ionizing irradiation induced less cell death in CD4(+)CD25(+)Foxp3(+) Treg cells than in CD4(+)CD25(-) T cells. Thus, a low dose of WBI could significantly enhance the level of functional CD4(+)CD25(+)Foxp3(+) Treg cells in the periphery of naive or immunized mice. The enhanced proportion of CD4(+)CD25(+)Foxp3(+) Treg cells in the periphery by a low dose of WBI may make hosts more susceptible to immune tolerance induction.

Increased prevalence of regulatory T cells in the tumor microenvironment and its correlation with TNM stage of hepatocellular carcinoma

BACKGROUND AND PURPOSE

Few detailed studies about the correlations among the expanded prevalence, elevated function of Treg cells in tumor microenvironment of hepatocellular carcinoma (HCC), and different clinical tumor stage were reported. The purpose of the present study was to examine the presence and functions of CD4(+)CD25(high) regulatory T cell (Treg cell) in tumor microenvironment from early and late stages and reveal the potential underlying mechanisms that may be responsible.

METHOD

The prevalence of Treg in peripheral blood and fresh tissue samples from 31 patients with HCC after radical hepatectomy and 9 controls was detected. CD127 was selected as a Treg cell maker to test the cell populations and compared its expressions with ICOS. The expressions of FOXP3 mRNA were analyzed. The migration, proliferation, and suppression functions of Treg cell were observed. IFN-γ., IL-10, TGF-ß, CCL-17, CCL-22, and SDF-1 in cell supernatant were detected. Among all of the tests, the relations among the different TNM tumor stages, populations, and functions of Treg cells were evaluated.

RESULTS

The prevalence of Treg cell was significantly higher in the peripheral blood and in tumor tissue compared with those in normal donors. Increased numbers of Treg cell were showed in peripheral blood as well as in tumor tissue. High levels of IL-10 and TGF-ß, but little IFN-γ, were detected in the tumor microenvironment. Treg cells potently suppressed the functions and proliferation of CD4(+)CD25(-) T cells. High levels of SDF-1 were detected in malignant biopsies compared with those in benign regions, significantly increased in stage III. Plasma from the same patient was able to chemoattract Treg cell but that was lesser extent than those in tumor supernatant. Also, supernatant in advanced stage tumors exhibited powerful chemoattractic activity. SDF-1 played an important role in the recruited functions of Treg cell into tumor microenvironment of early and advanced stages. The expressions of Foxp3 mRNA increased in different TNM stages. The increased prevalence and expanded function of Treg cells in the tumor microenvironment of HCC were correlated with the cancer stage.

CONCLUSION

The increase in frequency of Treg cells might play a role in modulation of the immune response against HCC in different TNM stages. The substance secreted in tumor microenvironment recruited CD4(+)CD25(+) Treg cells to tumor sites to contribute to the prosperity and growth of the tumors. The performance of Treg cells in different TNM stages of tumor microenvironment might be acted as the route to evaluate the immunotherapy-based methods, promote therapy effect, and consequently to increase the survival rate in HCC.

Reconstitution of self-tolerance after hematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) is a major complication of allogeneic bone marrow or hematopoietic stem cell transplantation. GVHD is thought to be primarily due to the response of mature T cells transferred along with the bone marrow graft to foreign histocompatibility antigens expressed on host tissues. Recent studies, however, have challenged this paradigm set forth in the 1960s and have suggested that self-MHC class II antigens can be recognized in GVHD. Many questions still remain unanswered particularly in regard to the role of immune reconstitution, the ability to recognize and discriminate self and the re-establishment of self-tolerance. In fact, the failure to re-establish tolerance to self can lead to systemic autoimmunity that may exacerbate or even mimic GVHD. The present review summarizes our studies in autologous GVHD characterizing the underlying immune mechanisms and their potential impact in allogeneic hematopoietic stem cell transplantation.