Evaluation of human first trimester decidual and telomerase-transformed endometrial stromal cells as model systems of in vitro decidualization

BACKGROUND

Decidualization, the differentiation process of maternal uterine stromal cells into secretory decidual cells, is a prerequisite for successful implantation and progression of pregnancy. For in vitro differentiation mostly primary human endometrial stromal cells (HESC) isolated from uterine samples after hysterectomy for benign gynaecological diseases are utilised. However, a continuous supply of endometrial tissue is often lacking. Hence, we analysed whether cultivated human decidual stromal cells (HDSC) prepared from first trimester pregnancy terminations may represent an alternative model system for in vitro decidualization. Moreover, based on the expression of critical marker genes these cells were compared to a previously established endometrial stromal cell line during in vitro differentiation.

METHODS

HDSC isolated from decidual tissue attached to first trimester placentae, and telomerase-transformed human endometrial stromal cells (THESC) were characterised by immunofluorescence and differentiated in vitro using either cyclic adenosine monophosphate (cAMP) and/or estrogen (E2)/progesterone (P4). Proliferation was measured by analyzing cumulative cell numbers. Expression of mRNAs encoding progesterone receptor (PR), prolactin (PRL), insulin-like growth factor binding protein-1 (IGFBP1), and Dickkopf-1 (DKK1) was evaluated using quantitative PCR after 3, 6, 9 and 12 days of in vitro differentiation. PRL and IGFBP-1 protein expression was investigated by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. Furthermore, forkhead box O1A (FOXO1A), a critical transcription factor in decidualization, was analysed by immunofluorescence and Western blotting at two different time points of differentiation.

RESULTS

Treatment with cAMP provoked morphological changes and growth arrest of THESC and HDSC, the latter showing loss of cells after 6 days of treatment. E2P4 stimulation did neither affect cell morphology nor proliferation of THESC and HDSC. Upon cAMP stimulation PR mRNA was suppressed in HDSC but not in THESC, whereas E2P4 did not alter transcript levels in both cell types. Protein expression of PR-A and PR-B was detectable in HDSC and diminished under cAMP, whereas THESC failed to produce the nuclear receptors. Supplementation of cAMP induced mRNA and protein expression of PRL and IGFBP-1 in both cell types at day 3, 6, 9, and 12 of treatment. In HDSC stimulation with E2P4 increased PRL and IGFBP-1 mRNA and protein production, whereas hormone treatment did not induce the two factors in THESC. E2P4 increased DKK1 mRNA at all time points in HDSC and cAMP provoked induction at day 9 and 12 of differentiation. In contrast, cAMP suppressed DKK1 mRNA in THESC, whereas E2P4 was ineffective. In both cell types combined treatments with cAMP and E2P4 provoked higher expression levels of PRL and IGFBP1 mRNA and protein as compared to cAMP stimulation alone. FOXO1A protein and its nuclear abundance were increased by cAMP in both cell types. However, reduction of its nuclear localisation upon E2P4 treatment could only be observed in HDSC.

CONCLUSION

Both HDSC and THESC may represent suitable model systems for cAMP-dependent in vitro decidualization. Since cAMP decreases cell viability of HDSC after 6 days of incubation, this substance should be preferentially used in short-term experiments. Progesterone treatment of THESC might not be applicable since these cells lack progesterone response and PR protein. In contrast, stimulation of PR-expressing HDSC with E2P4 or cAMP/E2P4 may represent an appropriate protocol for human in vitro decidualization inducing and maintaining expression of critical marker genes in a time-dependent manner.

Induction of CD4(+)CD25(+)FOXP3(+) regulatory T cells during human hookworm infection modulates antigen-mediated lymphocyte proliferation

Hookworm infection is considered one of the most important poverty-promoting neglected tropical diseases, infecting 576 to 740 million people worldwide, especially in the tropics and subtropics. These blood-feeding nematodes have a remarkable ability to downmodulate the host immune response, protecting themselves from elimination and minimizing severe host pathology. While several mechanisms may be involved in the immunomodulation by parasitic infection, experimental evidences have pointed toward the possible involvement of regulatory T cells (Tregs) in downregulating effector T-cell responses upon chronic infection. However, the role of Tregs cells in human hookworm infection is still poorly understood and has not been addressed yet. In the current study we observed an augmentation of circulating CD4(+)CD25(+)FOXP3(+) regulatory T cells in hookworm-infected individuals compared with healthy non-infected donors. We have also demonstrated that infected individuals present higher levels of circulating Treg cells expressing CTLA-4, GITR, IL-10, TGF-β and IL-17. Moreover, we showed that hookworm crude antigen stimulation reduces the number of CD4(+)CD25(+)FOXP3(+) T regulatory cells co-expressing IL-17 in infected individuals. Finally, PBMCs from infected individuals pulsed with excreted/secreted products or hookworm crude antigens presented an impaired cellular proliferation, which was partially augmented by the depletion of Treg cells. Our results suggest that Treg cells may play an important role in hookworm-induced immunosuppression, contributing to the longevity of hookworm survival in infected people.

A focused in situ hybridization screen identifies candidate transcriptional regulators of thymic epithelial cell development and function

Background

Thymic epithelial cells (TECs) are necessary for normal T cell development. Currently, one transcription factor, Foxn1 is known to be necessary for the progression of fetal TEC differentiation. However, some aspects of fetal TEC differentiation occur in Foxn1 mutants, suggesting the existence of additional transcriptional regulators of TEC differentiation. The goal of this study was to identify some of the additional candidate transcription factors that may be involved in the specification and/or differentiation of TECs during fetal development.

Methodology/Principal Findings

We identified candidate fetal TEC transcriptional regulators via data and text mining. From our data mining we selected the transcription factors Foxg1, Isl1, Gata3, Nkx2-5, Nkx2-6 and Sox2 for further studies. Whole mount in situ hybridizations confirmed the expression of these transcription factors within subdomains of the third pharyngeal pouch from E9.5–E10.5. By E11.5 days Foxg1 and Isl1 transcripts were the only mRNAs from this group of genes detected exclusively within the thymus domain of the third pouch. Based on this initial in situ hybridization analysis, we focused on defining the expression of Foxg1 and Isl1 during multiple stages of thymus development and TEC differentiation. We found that Foxg1 and Isl1 are specifically expressed in differentiating TECs during fetal and postnatal stages of thymus development. In addition, we found differential expression of Islet1 and Foxn1 within the fetal and postnatal TEC population.

Conclusions/Significance

Our studies have identified two developmental transcription factors that are excellent candidate regulators of thymic epithelial cell specification and differentiation during fetal development. Our results suggest that Foxg1 and Isl1 may play a role in the regulation of TEC differentiation during fetal and postnatal stages. Our results also demonstrate heterogeneity of TECs marked by the differential expression of transcription factors, potentially providing new insights into the regulation of TEC differentiation.

[Study on expression of Treg cells in attenuated Schistosoma japonicum cercariae immunized BALB/c mice]

OBJECTIVE

To study the expression differences of CD4+CD25+Foxp3+Treg cells between the attenuated cercariae immunized mice and the normal infected mice and discuss the immune protection mechanisms of the mice immunized with attenuated cercariae.

METHODS

Forty female BALB/c mice were divided into 2 groups, group A, the attenuated cercariae immunized group (16 mices) and the group B, the normal cercariae infected group (16 mices), and the last 8 ones served as the blank control. The spleen cells and the ratios of PBMC's CD4+CD25+Foxp3+/CD4+CD25+T cells were compared between the attenuated cercariae immunized mice and normal mice injected by FCM and the Foxp3 expression levels in spleens and livers were assayed by IHC. The transcription factor Foxp3 in the peripheral blood was detected by RT-PCR.

RESULTS

In group A and group B, CD4+CD25+Foxp3+/ CD4+CD25+T ratios in the PBMC 6 weeks post-infection were (14.15 +/- 2.62)% and (7.92 +/- 2.22)%, respectively (P < 0.05); the ratios in the spleen cells were (14.52 +/- 2.98)% and (8.18 +/- 2.84)%, respectively (P < 0.05); 8 weeks post-infection, the ratios in the PBMC were (15.92 +/- 2.98)% and (13.26 +/- 2.64)%, respectively, (P < 0.05); the ratios of the spleen cells were (16.42 +/- 2.46)% and (13.48 +/- 2.36)%, respectively (P < 0.05); 6 weeks post-infection, the Foxp3 expression levels in livers were "+" and "-", respectively, and those in the spleens were "++" and "+", respectively; 8 weeks post-infection, the Foxp3 expression levels in the livers were "++" and "-" respectively, and those in the spleens were "++" and "+", respectively.

CONCLUSIONS

The expression level of attenuated cercariae immunized group's CD4+CD25+Foxp3+Treg cells is higher than that in the control group during the late stages, suggesting that CD4+CD25+Foxp3+Treg in the attenuated cercariae immunized mice may play one of the important roles in its immune protection mechanisms.

Trichinella spiralis antigens prime mixed Th1/Th2 response but do not induce de novo generation of Foxp3+ T cells in vitro

Many parasitic helminth infections induce Th2-type immune responses and engage the regulatory network. In this study, we specifically investigated the influence of antigens derived from different life stages of the helminth Trichinella spiralis on the polarization of naive CD4(+) T cells by dendritic cells. Results obtained from C57BL/6 mice showed that T. spiralis derived antigens have the capacity to induce bone marrow-derived dendritic cells to acquire an incompletely mature phenotype that promotes a significant proliferation of naive CD4(+) T cells and a mixed Th1/Th2 cytokine profile with the predominance of Th2 cytokines. Increased production of IL-4, IL-9, IL-10 and IL-13 accompanied increased IFN-γ. Furthermore, dendritic cells pulsed with T. spiralis antigens did not induce an increase in the population of Foxp3(+) T regulatory cells. Although other helminth antigens have demonstrated the capacity to induce de novo generation of Foxp3(+) T regulatory cells, here our in vitro studies provide no evidence that T. spiralis antigens have this capacity.

Quantitative impact of thymic selection on Foxp3+ and Foxp3- subsets of self-peptide/MHC class II-specific CD4+ T cells

It is currently thought that T cells with specificity for self-peptide/MHC (pMHC) ligands are deleted during thymic development, thereby preventing autoimmunity. In the case of CD4(+) T cells, what is unclear is the extent to which self-peptide/MHC class II (pMHCII)-specific T cells are deleted or become Foxp3(+) regulatory T cells. We addressed this issue by characterizing a natural polyclonal pMHCII-specific CD4(+) T-cell population in mice that either lacked or expressed the relevant antigen in a ubiquitous pattern. Mice expressing the antigen contained one-third the number of pMHCII-specific T cells as mice lacking the antigen, and the remaining cells exhibited low TCR avidity. In mice lacking the antigen, the pMHCII-specific T-cell population was dominated by phenotypically naive Foxp3(-) cells, but also contained a subset of Foxp3(+) regulatory cells. Both Foxp3(-) and Foxp3(+) pMHCII-specific T-cell numbers were reduced in mice expressing the antigen, but the Foxp3(+) subset was more resistant to changes in number and TCR repertoire. Therefore, thymic selection of self-pMHCII-specific CD4(+) T cells results in incomplete deletion within the normal polyclonal repertoire, especially among regulatory T cells.

Viral interactions with B-cells contribute to increased regulatory T-cells during chronic HCV infection

Hepatitis C virus (HCV) has a propensity to establish chronic infection that is characterized by attenuated virus-specific T-cell responses. Mechanisms leading to T-cell attenuation are poorly understood and likely involve dysfunctional interactions between antigen-presenting cells (APC) and effector/regulatory T-cells. Reports on dendritic cells (DC) have described only minor dysfunction during HCV infection. However, there is a paucity of reports regarding B-cell function, despite clear associations with B-cell-related secondary sequelae. In this study we evaluated the state of B-cells during chronic HCV infection, and observed a diminished ability to respond to mitogenic stimuli, correlating with increased apoptosis. This was in contrast to their ex vivo phenotype, which indicated ongoing chronic activation in vivo. There was a high association of HCV-positive strand RNA with B-cells in a subset of HCV patients. Interestingly, ex-vivo-derived HCV RNA-positive B-cells induced significantly greater proliferation in allogeneic T-cells than in HCV-negative B-cells, correlating with an increased generation of CD4(+)CD25(+)FOXP3(+) regulatory T-cells (Tregs). In-vitro exposure of healthy peripheral blood mononuclear cells (PBMC) to HCV resulted in robust activation of resting B-cells. These HCV-exposed B-cells also showed an enhanced ability to generate Tregs. Our results provide strong evidence for a novel and paradoxical link between HCV-induced enhanced APC function and the generation of Tregs.

Early short-term antiretroviral therapy is associated with a reduced prevalence of CD8(+)FoxP3(+) T cells in simian immunodeficiency virus-infected controller rhesus macaques

Regulatory T cells contain a mix of CD4 and CD8 T cell subsets that can suppress immune activation and at the same time suppress immune responses, thereby contributing to disease progression. Recent studies have shown that an increased prevalence of CD8(+)FoxP3(+) T regulatory cells was associated with immune suppression and diminished viral control in simian immunodeficiency virus (SIV)-infected rhesus macaques. Preventing an increase in the prevalence of CD8 T regulatory subsets is likely to lead to a better long-term outcome. Here we show that short-term antiretroviral therapy initiated within 1 week after SIV infection was associated with lower viral set point and immune activation after withdrawal of therapy as compared to untreated animals. Early short-term treated controller animals were found to have better SIV-specific immune responses and a significantly lower prevalence of immunosuppressive CD8(+)FoxP3(+) T cells. Lower levels of CD8(+)FoxP3(+) T cells coincided with preservation of CD4(+)FoxP3(+) T cells at homeostatic levels, and significantly correlated with lower immune activation, suggesting a role for viral infection-driven immune activation in the expansion of CD8(+)FoxP3(+) T cells. Interestingly, initiation of continuous therapy later in infection did not reduce the increased prevalence of CD8(+)FoxP3(+) T cells to homeostatic levels. Taken together, our results suggest that early antiretroviral therapy preserves the integrity of the immune system leading to a lower viral set point in controller animals, and prevents alterations in the homeostatic balance between CD4(+) and CD8(+) T regulatory cells that could aid in better long-term outcome.

The numbers of FoxP3+ lymphocytes in sentinel lymph nodes of breast cancer patients correlate with primary tumor size but not nodal status

Regulatory T cells, lymphocytes marked by expression of the transcription factor Forkhead Box Protein P3 (FoxP3), inhibit the activation of tumor-specific T cells in tumor-draining lymph nodes. Immunohistochemical analyses of sentinel lymph nodes (SLNs) from 104 breast cancer patients showed a significant association (p = .0028, Pearson correlation) between the number of FoxP3+ cells and the size of primary breast invasive ductal carcinoma. In contrast, there was no correlation between the number of FoxP3+ cells and the presence of SLN metastases, or other clinicopathological parameters. These results suggest the presence of an immune suppressive environment in SLNs of larger tumors.

Foxp3 and IL-10 expression correlates with parasite burden in lesional tissues of post kala azar dermal leishmaniasis (PKDL) patients

Background

Post kala-azar dermal leishmaniasis (PKDL), a sequel to visceral leishamaniasis (VL) in 5–15% cases, constitutes a parasite reservoir important in disease transmission. The precise immunological cause of PKDL outcome remains obscure. However, overlapping counter regulatory responses with elevated IFN-γ and IL-10 are reported.

Methodology/Principal Findings

Present study deals with ex-vivo mRNA and protein analysis of natural regulatory T cells (nTreg) markers (Foxp3, CD25 and CTLA-4) and IL-10 levels in lesion tissues of PKDL patients at pre and post treatment stages. In addition, correlation of nTreg markers and IL-10 with parasite load in tissue lesions was investigated. mRNA levels of nTreg markers and IL-10 were found significantly elevated in pre-treatment PKDL cases compared to controls (Foxp3, P = 0.0009; CD25 & CTLA-4, P<0.0001; IL-10, P<0.0001), and were restored after treatment. Analysis of nTreg cell markers and IL-10 in different clinical manifestations of disease revealed elevated levels in nodular lesions compared to macules/papules. Further, Foxp3, CD25 and IL-10 mRNA levels directly correlated with parasite load in lesions tissues.

Conclusion/Significance

Data demonstrated accumulation of nTreg cells in infected tissue and a correlation of both IL-10 and nTreg levels with parasite burden suggesting their role in disease severity in PKDL.

Post kala azar dermal leishamniasis (PKDL), an unusual dermatosis develops in 5–15% of apparently cured visceral leishmaniasis cases in India and in about 60% of cases in Sudan. PKDL cases assume importance since they constitute a major human reservoir for the parasite. Inadequate treatment of VL, genetics, nutrition and immunological mechanisms that allow renewed multiplication of latent parasites or reinfection predispose to PKDL. Immunopathogenesis of PKDL is poorly understood. IL-10 is widely accepted as an immuno-suppressive cytokine and produced by diverse cell populations including, B cells, macrophages and CD4+ T cells. Natural T regulatory (nTreg) cells are subpopulation of CD4+ T cells that inhibit the response of other T cells. In this study we reported the accumulation of nTreg cells in lesion tissues of PKDL patients. Further correlation of Treg markers and IL-10 with parasite load in lesion tissues suggested a role of IL-10 and Treg in parasite establishment or persistence. Further studies are warranted to explore antigen specific IL-10 source in lesion tissues and unravel the concerted induction or accumulation of Treg in PKDL.

The absence of B lymphocytes reduces the number and function of T-regulatory cells and enhances the anti-tumor response in a murine tumor model

Increasing evidence suggests that B lymphocytes play a central role in inhibiting the immune response against certain tumors, but the underlying mechanisms by which B cells facilitate tumor growth are still poorly understood. In this study, we investigated how the presence or absence of B cells affects expansion and function of T-regulatory cells ('T-regs') in a murine breast tumor model (EMT-6). We compared tumor growth, and the number and function of T-reg cells in wild-type immune-competent mice (ICM) and B-cell-deficient mice (BCDM). Mice were either tumor-naive or implanted with EMT-6 mammary adenocarcinoma cells. Tumor growth was markedly inhibited in BCDM, compared to wild-type mice (ICM). Increased T-reg expansion as defined by CD4+/CD25+/FOXP3+ cells was evident following EMT-6 inoculation in ICM in comparison with non-tumor-bearing mice or compared to BCDM in which tumor had been implanted. The percentage and absolute number of T-regs in the spleen, tumor draining lymph nodes, and tumor bed were significantly reduced in BCDM compared to ICM. T-reg function, measured by suppression and proliferation assays, was also reduced in tumor inoculated BCDM compared to ICM. Our studies indicate that absence of B cells may play a role in augmenting the T-cell anti-tumor response, in part due to effects on T-regulatory cell expansion and function.

Reduced IL-2 expression in NOD mice leads to a temporal increase in CD62Llo FoxP3+ CD4+ T cells with limited suppressor activity

IL-2 plays a critical role in the induction and maintenance of FoxP3-expressing regulatory T cells (FoxP3(+) Tregs). Reduced expression of IL-2 is linked to T-cell-mediated autoimmune diseases such as type 1 diabetes (T1D), in which an imbalance between FoxP3(+) Tregs and pathogenic T effectors exists. We investigated the contribution of IL-2 to dysregulation of FoxP3(+) Tregs by comparing wildtype NOD mice with animals congenic for a C57BL/6-derived disease-resistant Il2 allele and in which T-cell secretion of IL-2 is increased (NOD.B6Idd3). Although NOD mice exhibited a progressive decline in the frequency of CD62L(hi) FoxP3(+) Tregs due to an increase in CD62L(lo) FoxP3(+) Tregs, CD62L(hi) FoxP3(+) Tregs were maintained in the pancreatic lymph nodes and islets of NOD.B6Idd3 mice. Notably, the frequency of proliferating CD62L(hi) FoxP3(+) Tregs was elevated in the islets of NOD.B6Idd3 versus NOD mice. Increasing levels of IL-2 in vivo also resulted in larger numbers of CD62L(hi) FoxP3(+) Tregs in NOD mice. These results demonstrate that IL-2 influences the suppressor activity of the FoxP3(+) Tregs pool by regulating the balance between CD62L(lo) and CD62L(hi) FoxP3(+) Tregs. In NOD mice, reduced IL-2 expression leads to an increase in nonsuppressive CD62L(lo) FoxP3(+) Tregs, which in turn correlates with a pool of CD62L(hi) FoxP3(+) Tregs with limited proliferation.

[Imbalance of immunological functions of Treg and TGF-β1 aggravated cerebral ischemia damage in mice]

AIM

To investigate the changes of proportion of CD4(+);CD25(+); regulatory T cells (Treg) in Splenocytes and concentration of serum TGF-β1 in diverse period after transient middle cerebral artery occlusion(tMCAO) in mice and correlation between Treg and TGF-β1, so as to elucidate their roles in the immunological injury of acute ischemic stroke.

METHODS

60 male Kunming mice were randomly divided into six groups, i.e. sham group (24 h, n=10) and five tMCAO groups(ischemia/reperfusion 12 h, 24 h, 48 h, 72 h and 5 d, n=10/group), amount to six groups. The models of tMCAO were established by modified monofilament method; Neurologic deficit score was performed at each time point after tMCAO, and then, to sacrifice mice and measure the volume of cerebral infarction by TTC staining; the expression of Foxp3 in spleen was observed by frozen section and immunofluorescence method; the proportions of Treg in splenocytes were analyzed by flow cytometry(FCM) and the concentrations of serum TGF-β1 were measured by ELISA.

RESULTS

This study observed that there was obvious immunological injury and it was gradually worse. Similarly, TTC staining indicated that the volume of cerebral infarction gradually enlarged and peaked at 48 h following reperfusion, subsequently, exhibited slight decrease. Neurological function gradually improved after reperfusion. There were positive expressions of Foxp3 in the mice spleens and significant different in every groups. FCM indicated, compared with sham group, the percentage of Treg was decrease at 24 h after ischemia/reperfusion (P<0.05), and recovered normal level at 72 h, and significantly increased at 5 d (P<0.05). The level of serum TGF-β1 also showed the similar tendency, the concentration of serum TGF-β1 was lower at 24 h after ischemia/reperfusion than sham group, and recovered to sham's level at 48 h, and was significantly higher at 5 d than sham group (P<0.05). Otherwise, there was a positive correlation between serum level of TGF-β1 and percentage of Treg.

CONCLUSION

The levels of Treg and TGF-β 1 were decrease in the acute period after ischemia/reperfusion, and they were significant increase in the recovery progress, which closely associated with the change of the ischemia volume. Therefore, Imbalance of Treg and TGF-β1 is very likely to play an important role in the immunological injury of acute ischemic stroke.

The kinases MEKK2 and MEKK3 regulate transforming growth factor-β-mediated helper T cell differentiation

Mitogen-activated protein kinases (MAPKs) are key mediators of the T cell receptor (TCR) signals but their roles in T helper (Th) cell differentiation are unclear. Here we showed that the MAPK kinase kinases MEKK2 (encoded by Map3k2) and MEKK3 (encoded by Map3k3) negatively regulated transforming growth factor-β (TGF-β)-mediated Th cell differentiation. Map3k2(-/-)Map3k3(Lck-Cre/-) mice showed an abnormal accumulation of regulatory T (Treg) and Th17 cells in the periphery, consistent with Map3k2(-/-)Map3k3(Lck-Cre/-) naive CD4(+) T cells' differentiation into Treg and Th17 cells with a higher frequency than wild-type (WT) cells after TGF-β stimulation in vitro. In addition, Map3k2(-/-)Map3k3(Lck-Cre/-) mice developed more severe experimental autoimmune encephalomyelitis. Map3k2(-/-)Map3k3(Lck-Cre/-) T cells exhibited impaired phosphorylation of SMAD2 and SMAD3 proteins at their linker regions, which negatively regulated the TGF-β responses in T cells. Thus, the crosstalk between TCR-induced MAPK and the TGF-β signaling pathways is important in regulating Th cell differentiation.

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.

Retinoic acid and rapamycin differentially affect and synergistically promote the ex vivo expansion of natural human T regulatory cells

Natural T regulatory cells (Tregs) are challenging to expand ex vivo, and this has severely hindered in vivo evaluation of their therapeutic potential. All trans retinoic acid (ATRA) plays an important role in mediating immune homeostasis in vivo, and we investigated whether ATRA could be used to promote the ex vivo expansion of Tregs purified from adult human peripheral blood. We found that ATRA helped maintain FOXP3 expression during the expansion process, but this effect was transient and serum-dependent. Furthermore, natural Tregs treated with rapamycin, but not with ATRA, suppressed cytokine production in co-cultured effector T cells. This suppressive activity correlated with the ability of expanded Tregs to induce FOXP3 expression in non-Treg cell populations. Examination of CD45RA+ and CD45RA− Treg subsets revealed that ATRA failed to maintain suppressive activity in either population, but interestingly, Tregs expanded in the presence of both rapamycin and ATRA displayed more suppressive activity and had a more favorable epigenetic status of the FOXP3 gene than Tregs expanded in the presence of rapamycin only. We conclude that while the use of ATRA as a single agent to expand Tregs for human therapy is not warranted, its use in combination with rapamycin may have benefit.

Correlation between elevated FOXP3 expression and increased lymph node metastasis of gastric cancer

BACKGROUND

FOXP3 was thought to express in the T-cell lineage exclusively until recently when FOXP3 was shown to be expressed by cancer cells. It was indicated that FOXP3 may play a wider role in biology by endowing tumor cells with immune suppressive activity. However, researches between FOXP3 and lymph node metastasis of gastric cancer were relatively infrequent, so the present work was aimed to investigate the relationship between FOXP3 expression and lymph node metastasis in human gastric cancer.

METHODS

A total of 122 gastric cancer patients were enrolled in this study, and gastric tumor specimens and lymph nodes were acquired. Thirty patients who had chronic superficial gastritis diagnosed by gastroscopy contemporaneously in the Peking University People's Hospital were chosen randomly as the control group. Immunohistochemistry was performed to evaluate FOXP3 expression. A survival analysis on the 122 patients was then performed. Then, NCI-N87 cell lines were used to confirm FOXP3 expression in gastric carcinoma cells. Finally, evaluation of FOXP3 expression in gastric tumor and peritumor tissues in 12 patients were conducted using immunohistochemistry and Western blotting. A χ(2) test or Fisher's exact test (bilateral) was conducted to compare the percentage of positive percentage staining between groups. Kaplan-Meier analysis was performed for survival analysis.

RESULTS

FOXP3 was expressed by gastric cancer cells and peritumor epithelial cells. FOXP3 expression was increased in primary tumors (58.2%) than that in control group (26.7%). In the lymph-node metastasis group, the incidence of lymph node metastasis which was less than 60% had a significant upregulation of FOXP3 in primary tumors and lymph nodes. However, the frequency of FOXP3 expression had no relationship with survival.

CONCLUSION

FOXP3 probably has a relationship with lymph node metastasis of gastric cancer.

Early induction of GAD(65)-reactive Th2 response in type 1 diabetic children treated with alum-formulated GAD(65)

BACKGROUND

We have previously shown that two injections of 20 µg alum-formulated glutamic acid decarboxylase 65 (GAD(65)) (GAD-alum; Diamyd(®)) in children with recent-onset type 1 diabetes lead to preservation of residual insulin secretion. In vitro cytokine production at the 15 months' follow-up indicated immunomodulation. In the present study, we took advantage of peripheral blood mononuclear cells, cryopreserved during early follow-ups, to investigate whether the immunomodulatory effect of GAD-alum was apparent earlier after treatment, preceding the changes previously reported at 15 months.

METHODS

Peripheral blood mononuclear cells from 70 type 1 diabetic children, randomly assigned GAD-alum (n = 35) or placebo (n = 35), that had been frozen at baseline (n = 27) and after 1 (n = 58), 3 (n = 67) and 9 (n = 66) months, were stimulated in vitro with GAD(65), tyrosine phosphatase-like protein IA-2 peptide, insulin peptide, GAD-alum, alum formulation or phytohaemagglutinin. Interleukin (IL)-5, -6, -10, -12, -13, -17, tumour necrosis factor and interferon-γ were measured in cell supernatants and serum samples using Luminex. Expression of FOXP3 and transforming growth factor-β was determined by real-time reverse transcription polymerase chain reaction.

RESULTS

Already 1 month after the first injection, GAD(65)-induced IL-5 and IL-13 together with FOXP3 were enhanced in GAD-alum-treated patients compared to those with placebo. The in vitro response at 3 and 9 months was characterized by a broader range of cytokines in the treated group. Notably, only the T-helper 2-associated cytokines IL-5 and IL-13 together with FOXP3 increased continuously over time.

CONCLUSIONS

Treatment with GAD-alum in type 1 diabetic children induced an early T-helper 2 immune enhanced response to GAD(65), followed by a wider spectrum of cytokines at 3 and 9 months.

Expansion of CD25+CD4+ regulatory T cells by natural mature dendritic cells

Because of the anergy of CD25+CD4+ regulatory T cells, it is unclear how the number of these regulatory T cells is sustained and expanded in normal physiologic circumstances. In the present study, we examined the effect of natural allogeneic mature dendritic cells (DCs) on the proliferation and function of CD25+CD4+ T cells. Our data showed that natural allogeneic mature DCs stimulated CD25+CD4+ T-cell growth vigorously, whereas immature DCs had little effect on the proliferation of CD25+CD4+ T cells. After expansion by mature DCs, CD25+CD4+ T cells maintained their expression of Foxp3 and suppressed the proliferation of CD25- CD4+ T cells similar to freshly isolated CD25+CD4+ T cells. Our results introduce a potentially critical role played by natural allogeneic mature DCs, which exist in normal physiologic circumstances, in controlling CD25+CD4+ regulatory T-cell expansion and function.

Mesenchymal stem cells enhance allogeneic islet engraftment in nonhuman primates

OBJECTIVE

To test the graft-promoting effects of mesenchymal stem cells (MSCs) in a cynomolgus monkey model of islet/bone marrow transplantation.

RESEARCH DESIGN AND METHODS

Cynomolgus MSCs were obtained from iliac crest aspirate and characterized through passage 11 for phenotype, gene expression, differentiation potential, and karyotype. Allogeneic donor MSCs were cotransplanted intraportally with islets on postoperative day (POD) 0 and intravenously with donor marrow on PODs 5 and 11. Recipients were followed for stabilization of blood glucose levels, reduction of exogenous insulin requirement (EIR), C-peptide levels, changes in peripheral blood T regulatory cells, and chimerism. Destabilization of glycemia and increases in EIR were used as signs of rejection; additional intravenous MSCs were administered to test the effect on reversal of rejection.

RESULTS

MSC phenotype and a normal karyotype were observed through passage 11. IL-6, IL-10, vascular endothelial growth factor, TGF-β, hepatocyte growth factor, and galectin-1 gene expression levels varied among donors. MSC treatment significantly enhanced islet engraftment and function at 1 month posttransplant (n = 8), as compared with animals that received islets without MSCs (n = 3). Additional infusions of donor or third-party MSCs resulted in reversal of rejection episodes and prolongation of islet function in two animals. Stable islet allograft function was associated with increased numbers of regulatory T-cells in peripheral blood.

CONCLUSIONS

MSCs may provide an important approach for enhancement of islet engraftment, thereby decreasing the numbers of islets needed to achieve insulin independence. Furthermore, MSCs may serve as a new, safe, and effective antirejection therapy.

Naturally occurring CD4+ CD25+ FOXP3+ T-regulatory cells are increased in chronic myeloid leukemia patients not in complete cytogenetic remission and can be immunosuppressive

OBJECTIVE

Clinical presentation of chronic myeloid leukemia (CML) requires not only the deregulated tyrosine kinase BCR-ABL, but also the failure of an immune response against BCR-ABL-expressing cells. T-cell responses against BCR-ABL and other antigens are well-described, but their relevance to the in vivo control of CML is unclear. The suppressive role of naturally occurring T regulatory (T-reg) cells in antitumor immunity is well-established, although little is known about their role in modulating the T-cell response to BCR-ABL.

MATERIALS AND METHODS

Naturally occurring T-reg cells were characterized and quantified by flow cytometry in 39 CML patients and 10 healthy donors. Their function was studied by observing their effect on responses to purified protein derivative, a recall antigen, and on the response of an autologous T-cell line recognizing BCR-ABL.

RESULTS

T-reg cells were CD4(+), CD25(+), FOXP3(+), CD127(low), and CD62L(high). T-reg numbers in patients in complete cytogenetic remission were significantly lower than in patients not in complete cytogenetic remission (p < 0.01). T-reg cell depletion using anti-CD25 selection enhanced proliferative responses to purified protein derivative. Furthermore, the interferon-γ and/or granzyme-B production of effector cells specific for viral peptides or a BCR-ABL HLA-A3-restricted peptide was inhibited when autologous T-reg cells were present.

CONCLUSIONS

Taken together, these data suggest a role for T-reg cells in limiting immune responses in CML patients and this may include immune responses to BCR-ABL. The increased frequency of T-reg cells in patients with high levels of BCR-ABL transcripts indicates that an immune mechanism may be important in the control of CML.

CD4(+) regulatory T cells in a cynomolgus macaque model of Mycobacterium tuberculosis infection

BACKGROUND

Mycobacterium tuberculosis infection in humans results in either latent infection or active tuberculosis. We sought to determine whether a higher frequency of regulatory T (T(reg)) cells predispose an individual toward active disease or whether T(reg) cells develop in response to active disease.

METHODS

In cynomolgus macaques infected with a low dose of M. tuberculosis, approximately 50% develop primary tuberculosis, and approximately 50% become latently infected. Forty-one animals were monitored for 6-8 months to assess the correlation of the frequency of Foxp3(+) cells in peripheral blood and airways with the outcome of infection.

RESULTS

In all animals, the frequency of T(reg) cells (CD4(+)Foxp3(+)) in peripheral blood rapidly decreased and simultaneously increased in the airways. Latently infected monkeys had a significantly higher frequency of T(reg) cells in peripheral blood before infection and during early infection, compared with monkeys that developed active disease. Monkeys with active disease experienced increased frequencies of T(reg) cells among peripheral blood mononuclear cells as they developed disease.

CONCLUSIONS

Our data suggest that increased frequencies of T(reg) cells in active disease occur in response to increased inflammation rather than act as a causative factor in progression to active disease.

Effect of allogeneic bone marrow-derived mesenchymal stem cells transplantation in a polyI:C-induced primary biliary cirrhosis mouse model

Primary biliary cirrhosis (PBC) is a slowly progressive autoimmune disease of unknown mechanism. We established a PBC animal model by injecting C57BL/6 mice with polyinosinic-polycytidylic acid sodium (polyI:C) to investigate the therapeutic effect of bone marrow-derived mesenchymal stem cells (BM-MSC) on this model. After 6 weeks of MSC infusion, serum aminotransferase and autoimmune antibodies declined, and histological examination by hematoxylin and eosin staining showed significant amelioration of monocytes infiltration around bile ducts of mice treated with BM-MSC. Interestingly, allogeneic BM-MSC transplantation markedly increased CD4(+)Foxp3(+) regulatory T cells in peripheral blood as well as in lymph nodes when analyzed by flow cytometry. Further examination showed serum TGF-β1 increased but IFN-γ decreased significantly in PBC mice treated with MSC, while with no obvious change in IL-10 expression. Our results for the first time suggested that BM-MSC transplantation could regulate systemic immune response and enhance recovery in liver inflammation of PBC mice, raising the possibility for clinical application of allogeneic MSC in treatment of early-stage PBC patients.

MicroRNA-34a induces endothelial progenitor cell senescence and impedes its angiogenesis via suppressing silent information regulator 1

Endothelial progenitor cells (EPCs) play an important role in angiogenesis, which is essential for numerous physiological processes as well as tumor growth. Several microRNAs (miRNAs) have been reported to be involved in angiogenesis. MiR-34a, recently reported as a tumor suppressor, has been found to target silent information regulator 1 (Sirt1), leading to cell cycle arrest or apoptosis. However, the role of miR-34a in EPC-mediated angiogenesis was unknown. The present study tested the hypothesis that miR-34a inhibits EPC-mediated angiogenesis by inducing senescence via suppressing Sirt1. Bone marrow-derived EPCs from adult male Sprague-Dawley rats were used. Results of flow cytometry showed that EPCs after 7 days of culture expressed both stem cell markers CD34 and CD133 and endothelial cell markers VEGFR-2 (flk-1) and VE-cadherin. MiR-34a was expressed in normal EPCs, and overexpression of miR-34a via its mimic transfection significantly increased its expression and impaired in vitro EPC angiogenesis. MiR-34a overexpression led to a significantly increased EPC senescence, paralleled with an approximately 40% Sirt1 reduction. Furthermore, knockdown of Sirt1 by its siRNA resulted in diminished EPC angiogenesis and increased senescence. Finally, overexpression of miR-34a increased the level of Sirt1 effector-acetylated forkhead box O transcription factors 1 (FoxO1), an effect mimicked in EPCs following Sirt1 knockdown. In conclusion, miR-34a impairs EPC-mediated angiogenesis by induction of senescence via inhibiting Sirt1.