tTregs, pTregs, and iTregs: similarities and differences

Deep sequencing of the TCR-β repertoire of human forkhead box protein 3 (FoxP3)+ and FoxP3- T cells suggests that they are completely distinct and non-overlapping

Maintenance of peripheral tolerance requires a balance between autoreactive conventional T cells (T_conv ) and thymically derived forkhead box protein 3 (FoxP3)⁺ regulatory T cells (tT_regs ). Considerable controversy exists regarding the similarities/differences in T cell receptor (TCR) repertoires expressed by T_conv and tT_regs . We generated highly purified populations of human adult and cord blood T_conv and tT_regs based on the differential expression of CD25 and CD127. The purity of the sorted populations was validated by intracellular staining for FoxP3 and Helios. We also purified an overlap group of CD4 T cells from adult donors to ensure that considerable numbers of shared clonotypes could be detected when present. We used deep sequencing of entire TCR-β CDR3 sequences to analyse the TCR repertoire of T_conv and tT_regs . Our studies suggest that both neonatal and adult human T_conv and tT_reg cells are, in fact, entirely distinct CD4 T cell lineages.

In Vitro Differentiation of Human CD4+FOXP3+ Induced Regulatory T Cells (iTregs) from Naïve CD4+ T Cells Using a TGF-β-containing Protocol

Regulatory T cells (Tregs) are an integral part of peripheral tolerance, suppressing immune reactions against self-structures and thus preventing autoimmune diseases. Clinical approaches to adoptively transfer Tregs, or to deplete Tregs in cancer, are underway with promising first outcomes. Because the number of naturally occurring Tregs (nTregs) is very limited, studying certain Treg features using in vitro induced Tregs (iTregs) can be advantageous. To date, the best although not absolutely specific protein marker to delineate Tregs is the transcription factor FOXP3. Despite the importance of Tregs including non-redundant roles of peripherally induced Tregs, the protocols to generate iTregs are currently controversial, particularly for human cells. This protocol therefore describes the in vitro differentiation of human CD4+FOXP3+ iTregs from human naïve T cells using a range of Treg-inducing factors (TGF-β plus IL-2 only, or their combination with retinoic acid, rapamycin or butyrate) in parallel. It also describes the phenotyping of these cells by flow cytometry and qRT-PCR. These protocols result in reproducible expression of FOXP3 and other Treg signature genes and enable the study of general FOXP3-regulatory mechanisms as well as protocol-specific effects to delineate the impact of certain factors. iTregs can be utilized to study various phenotypic aspects as well as molecular mechanisms of Treg induction. Detailed molecular studies are facilitated by relatively large cell numbers that can be obtained. A limitation for the application of iTregs is the relative instability of FOXP3 expression in these cells compared to nTregs. iTregs generated by these protocols can also be used for functional assays such as studying their suppressive function, in which iTregs induced by TGF-β plus retinoic acid and rapamycin display superior suppressive activity. However, the suppressive capacity of iTregs can differ from nTregs and the use of appropriate controls is crucial.

Development and function of Foxp3(+) regulatory T cells

Regulatory T cells (Tregs) have been recognized as having a major role in maintaining peripheral tolerance and preventing and limiting autoimmune and chronic inflammatory diseases. Tregs derive from the thymus and also develop peripherally. In this review, we discuss recent progress in our understanding of the basic mechanisms involved in Treg development and function in protecting against autoimmunity in the periphery, including thymic selection, peripheral induction and the many mechanisms of Treg suppression. Specifically in kidney disease, Tregs have been shown to play a role in limiting injury and may potentially have a therapeutic role.

TGF-β Affects the Differentiation of Human GM-CSF+ CD4+ T Cells in an Activation- and Sodium-Dependent Manner

The cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is involved in the pathogenesis of chronic inflammatory diseases such as multiple sclerosis. However, the environmental cues promoting differentiation of GM-CSF producing T cells are unclear. Herein, we performed a broad experimental screening of cytokines and data-driven analysis assessing their ability to induce human GM-CSF⁺ CD4⁺ T cells and their subpopulations. TGF-β was discovered to induce GM-CSF production independently of proliferation and IL-2 signaling including STAT5. In contrast, IL-6 and IL-23 decreased GM-CSF production. On the population level, GM-CSF induction was highly correlated with expression of FOXP3 across cytokine stimulations but not with that of IL-17. However, on single-cell level GM-CSF and IFN-γ expression were most correlated, independently of the cytokine environment. Importantly, under low sodium conditions in the medium or upon stimulation with plate-bound instead of bead-bound anti-CD3 and anti-CD28 antibodies, the effects of TGF-β on GM-CSF, but not on FOXP3, were reversed. Our analysis indicates a novel role for TGF-β in generating GM-CSF⁺ subsets of human CD4⁺ T cells. These results are important for understanding of autoimmune disease and therapeutic considerations.

Ex-vivo iTreg differentiation revisited: Convenient alternatives to existing strategies

Ex-vivo differentiation of regulatory T cells (Tregs) from naïve CD4⁺ T-cells has been widely used in immunological research. Isolation of a highly pure naïve T cell population is the key factor that determines the efficiency of subsequent Treg differentiation. Currently, this step relies mostly on FACS sorting, which is often costly, time consuming, and inconvenient. Alternatively, magnetic separation of T-cells can be performed; yet, available protocols fail to reach sort level purity and consequently result in low Treg differentiation efficiency. Here, we present the results of a comprehensive side-by-side comparison of various magnetic separation strategies and FACS sorting in multiple levels. Additionally, we propose a novel optimized custom made magnetic separation protocol, which not only yields sort level purity and Treg differentiation but also lowers the reagent costs up to 75% compared to the commercially available purification kits. The highly pure naïve CD4⁺ T-cell population obtained by this versatile method can also be used for differentiation of other T-cell subsets; therefore this protocol may have broad applications in T-cell research.

Functional defects in CD4+ CD25high FoxP3+ regulatory cells in ankylosing spondylitis

Forkhead box P3 (FoxP3)-positive regulatory T cells (Tregs) play a pivotal role in the preservation of self-tolerance, and Treg dysfunction has been implicated in many autoimmune diseases. Whether and how Tregs participate in the pathogenesis of ankylosing spondylitis (AS) has not been fully elucidated. Here, we investigated Treg function and found that Tregs in peripheral blood (PB) from patients with active AS had lower FoxP3 mean fluorescence intensity (MFI) than those from healthy controls and could not fully suppress naïve T cell (Tn) proliferation. We also studied the mechanisms underlying PB Treg dysfunction in this context and found that PB Tregs failed to effectively utilize IL-2 and had relatively little STAT5 phosphorylation in active AS. Moreover, PB Tregs from patients with active AS exhibited greater CpG island methylation in the CNS2 region of the FOXP3 gene. Therefore, our findings indicate that functional defects in Tregs are present in AS. Abnormal IL-2 signalling and aberrant CNS2 epigenetic control induced functional defects in PB Tregs and represents a potential new mechanism for AS pathogenesis. These findings may aid the design of new treatment approaches for AS.

The Ikaros family of zinc-finger proteins

Ikaros represents a zinc-finger protein family important for lymphocyte development and certain other physiological processes. The number of family members is large, with alternative splicing producing various additional isoforms from each of the five homologous genes in the family. The functional forms of Ikaros proteins could be even more diverse due to protein–protein interactions readily established between family members. Emerging evidence suggests that targeting Ikaros proteins is feasible and effective in therapeutic applications, although the exact roles of Ikaros proteins remain elusive within the intricate regulatory networks in which they are involved. In this review we collect existing knowledge as to the functions, regulatory pathways, and molecular mechanisms of this family of proteins in an attempt to gain a better understanding through the comparison of activities and interactions among family members.

Regulatory T cells and potential inmmunotherapeutic targets in lung cancer

Lung cancer and metastasis are two of the most lethal diseases globally and seldom have effective therapies. Immunotherapy is considered as one of the powerful alternatives. Regulatory T cells (Tregs) can suppress the activation of the immune system, maintain immune tolerance to self-antigens, and contribute to immunosuppression of antitumor immunity, which is critical for tumor immune evasion in epithelial malignancies, including lung cancer. The present review gives an overview of the biological functions and regulations of Tregs associated with the development of lung cancer and metastasis and explores the potentials of Treg-oriented therapeutic targets. Subsets and features of Tregs mainly include naturally occurring Tregs (nTregs) (CD4(+) nTregs and CD8(+) nTregs) and adaptive/induced Tregs (CD4(+) iTregs and CD8(+) iTregs). Tregs, especially in circulation or regional lymph nodes, play an important role in the progress and metastasis of lung cancer and are considered as therapeutic targets and biomarkers to predict the survival length and recurrence of lung cancer. Increasing understanding of Tregs' functional mechanisms will lead to a number of clinical trials on the discovery and development of Treg-oriented new therapies. Tregs play important roles in lung cancer and metastasis, and the understanding of Tregs becomes more critical for clinical applications and therapies. Thus, Tregs and associated factors can be potential therapeutic targets for lung cancer immunotherapy.

Ontogeny of Tumor-associated CD4+CD25+Foxp3+ T-regulatory Cells

The critical contribution of CD4+CD25+Foxp3+ T-regulatory cells (Treg) to immune suppression in the tumor microenvironment is well-established. Whereas the mechanisms that drive the generation and accumulation of Treg in tumors have been an active area of study, the information on their origin and population dynamics remains limited. In this review, we discuss the ontogeny of tumor-associated Treg in light of the recently identified lineage markers.

Interaction between Treg cells and tumor-associated macrophages in the tumor microenvironment of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. Inflammatory cells in the EOC microenvironment play a key role in tumor progression. In the present study, we investigated the mechanism of the accumulation of regulatory T cells (Tregs) induced by interleukin-10 (IL-10) derived from tumor-associated macrophages (TAMs) in the EOC microenvironment. The frequency of Tregs and TAMs was detected by immunofluorescence in 40 EOC tissues and 20 benign ovarian tumors, as well as the expression of IL-10 which was assessed by immunohistochemistry. It was found that the frequency of Treg cells and TAMs was significantly higher in the EOC than those in the benign ovarian tumors. The expression of IL-10 was also found to be higher in the EOC than that in the benign tumors. EOC patients with a high frequency of Tregs exhibited a significantly shorter overall survival time compared to those with a low frequency of Tregs. In addition, the expression of IL-10 in ascites and blood serum and the IL-10 released in the co-cultured system supernatants were detected by ELISA. Following CD4+ T-cell co-culturing with macrophages and IL-10, it was observed by flow cytometric analysis that the frequency of Treg cells was increased in the presence of IL-10. It was also established that IL-10 released in the co-cultured supernatants was increased. We also detected the mechanism of Treg cells induced by IL-10 in vivo. The SKOV3 cell tumor volume and weight were much higher in the presence of IL-10 in a mouse subcutaneous model. These data suggest that IL-10 secreted by TAMs increase the frequency of Treg cells through the activation of Foxp3 during T-cell differentiation and promotes tumor progression.

mTORC1-Activated Monocytes Increase Tregs and Inhibit the Immune Response to Bacterial Infections

The TSC1/2 heterodimer, a key upstream regulator of the mTOR, can inhibit the activation of mTOR, which plays a critical role in immune responses after bacterial infections. Monocytes are an innate immune cell type that have been shown to be involved in bacteremia. However, how the mTOR pathway is involved in the regulation of monocytes is largely unknown. In our study, TSC1 KO mice and WT mice were infected with E. coli. When compared to WT mice, we found higher mortality, greater numbers of bacteria, decreased expression of coactivators in monocytes, increased numbers of Tregs, and decreased numbers of effector T cells in TSC1 KO mice. Monocytes obtained from TSC1 KO mice produced more ROS, IL-6, IL-10, and TGF-β and less IL-1, IFN-γ, and TNF-α. Taken together, our results suggest that the inhibited immune functioning in TSC1 KO mice is influenced by mTORC1 activation in monocytes. The reduced expression of coactivators resulted in inhibited effector T cell proliferation. mTORC1-activated monocytes are harmful during bacterial infections. Therefore, inhibiting mTORC1 signaling through rapamycin administration could rescue the harmful aspects of an overactive immune response, and this knowledge provides a new direction for clinical therapy.

Tregs and kidney: From diabetic nephropathy to renal transplantation

Kidney transplantation is recognised as the most effective treatment for patients with end-stage renal disease (ESRD). Kidney transplantation continues to face several challenges including long-term graft and patient survival, and the side effects of immunosuppressive therapy. The tendency in kidney transplantation is to avoid the side effects of immunosuppresants and induce immune tolerance. Regulatory T-cells (Tregs) contribute to self-tolerance, tolerance to alloantigen and transplant tolerance, mainly by suppressing the activation and function of reactive effector T-cells. Additionally, Tregs are implicated in the pathogenesis of diabetes, which is the leading cause of ESRD, suggesting that these cells play a role both in the pathogenesis of chronic kidney disease and the induction of transplant tolerance. Several strategies to achieve immunological tolerance to grafts have been tested experimentally, and include combinations of co-stimulatory blockade pathways, T-cell depletion, in vivo Treg-induction and/or infusion of ex-vivo expanded Tregs. However, a successful regimen that induces transplant tolerance is not yet available for clinical application. This review brings together certain key studies on the role of Tregs in ESRD, diabetes and kidney transplantation, only to emphasize that many more studies are needed to elucidate the clinical significance and the therapeutic applications of Tregs.

Adenosine production: a common path for mesenchymal stem-cell and regulatory T-cell-mediated immunosuppression

Adenosine is an important molecule that exerts control on the immune system, by signaling through receptors lying on the surface of immune cells. This nucleotide is produced, in part, by the action of the ectoenzymes CD39 and CD73. Interestingly, these proteins are expressed on the cell surface of regulatory T-cells (Tregs) and mesenchymal stromal cells (MSCs)-two cell populations that have emerged as potential therapeutic tools in the field of cell therapy. In fact, the production of adenosine constitutes a mechanism used by both cell types to control the immune response. Recently, great scientific progress was obtained regarding the role of adenosine in the inflammatory environment. In this context, the present review focuses on the advances related to the impact of adenosine production over the immune modulatory activity of Tregs and MSCs, and how this nucleotide controls the biological functions of these cells. Finally, we mention the main challenges and hurdles to bring such molecule to clinical settings.

Weight Gain Alters Adiponectin Receptor 1 Expression on Adipose Tissue-Resident Helios+ Regulatory T Cells

Adipose tissue produces multiple mediators that modulate the immune response. Adiponectin is an adipocyte-derived cytokine that exhibits metabolic and anti-inflammatory effects. Adiponectin acts through binding to adiponectin receptor 1 and 2 (AdipoR1/AdipoR2). AdipoR1 is ubiquitously expressed, whereas AdipoR2 is restricted to skeletal muscle and liver. AdipoR1 expression has been reported on a small percentage of T cells; nevertheless, it is still unknown whether Foxp3(+) regulatory T cells (Tregs) express AdipoR1. Recently, it has been shown that Tregs accumulate in adipose tissue and that they play a potential role in modulating adipose tissue inflammation. Our aim was to evaluate AdipoR1 expression in adipose tissue-resident Tregs and to evaluate the effect of weight gain on this expression. Male C57BL/6 mice were fed with a high-fat diet for 14 weeks (to develop overweight) or 21 weeks (to develop obesity). Mice on a standard diet were used as age-matched controls. Helios expression was evaluated as a marker to discriminate thymic-derived from peripherally induced Tregs. The majority of Tregs in both adipose tissue and the spleen expressed Helios. Adipose tissue Tregs expressed higher levels of AdipoR1 than Tregs in the spleen. AdipoR1 expression on adipose tissue Helios(+) Tregs was negatively correlated with epididymal fat. Overall, we show that AdipoR1 is expressed on adipose tissue-resident Tregs, mainly Helios(+) Tregs, and that this expression is dependent on weight and fat accumulation. Because both adiponectin and Tregs play roles in anti-inflammatory mechanisms, our data propose a new mechanism through which weight gain might alter immunoregulation.

Modulation of Alloimmunity by Heat Shock Proteins

The immunological mechanisms that evolved for host defense against pathogens and injury are also responsible for transplant rejection. Host rejection of foreign tissue was originally thought to be mediated mainly by T cell recognition of foreign MHC alleles. Management of solid organ transplant rejection has thus focused mainly on inhibition of T cell function and matching MHC alleles between donor and host. Recently, however, it has been demonstrated that the magnitude of the initial innate immune responses upon transplantation has a decisive impact on rejection. The exact mechanisms underlying this phenomenon have yet to be characterized. Ischemic cell death and inflammation that occur upon transplantation are synonymous with extracellular release of various heat shock proteins (Hsps), many of which have been shown to have immune-modulatory properties. Here, we review the impact of Hsps upon alloimmunity and discuss the potential use of Hsps as accessory agents to improve solid organ transplant outcomes.

Analysis of allergic immune responses in humanized mice

Nowadays, more than 25% of the population in industrial countries are affected by IgE-mediated (atopic) allergic diseases such as allergic rhinitis, asthma and atopic eczema. Due to intensive research on basis of in vitro studies with human immune cells and different murine in vivo models of allergy fundamental mechanisms of allergic immune responses have been elucidated during the last years. However, human studies are restricted and the immune system of mice differs from the human immune system in several aspects so that the transferability of experimental results from mice to men is limited. Humanized mice represent a new tool to analyze the interaction of human immune cells under physiological conditions as far as possible, particularly to test novel therapeutic strategies. This review summarizes the impact of humanized mouse models for the investigation and treatment of allergic diseases.

Exploring the induction of preproinsulin-specific Foxp3(+) CD4(+) Treg cells that inhibit CD8(+) T cell-mediated autoimmune diabetes by DNA vaccination

DNA vaccination is a promising strategy to induce effector T cells but also regulatory Foxp3⁺ CD25⁺ CD4⁺ Treg cells and inhibit autoimmune disorders such as type 1 diabetes. Little is known about the antigen requirements that facilitate priming of Treg cells but not autoreactive effector CD8⁺ T cells. We have shown that the injection of preproinsulin (ppins)-expressing pCI/ppins vector into PD-1- or PD-L1-deficient mice induced K^b/A12-21-monospecific CD8⁺ T cells and autoimmune diabetes. A pCI/ppinsΔA12-21 vector (lacking the critical K^b/A12-21 epitope) did not induce autoimmune diabetes but elicited a systemic Foxp3⁺ CD25⁺ Treg cell immunity that suppressed diabetes induction by a subsequent injection of the diabetogenic pCI/ppins. TGF-β expression was significantly enhanced in the Foxp3⁺ CD25⁺ Treg cell population of vaccinated/ppins-primed mice. Ablation of Treg cells in vaccinated/ppins-primed mice by anti-CD25 antibody treatment abolished the protective effect of the vaccine and enabled diabetes induction by pCI/ppins. Adoptive transfer of Treg cells from vaccinated/ppins-primed mice into PD-L1^−/− hosts efficiently suppressed diabetes induction by pCI/ppins. We narrowed down the Treg-stimulating domain to a 15-residue ppins76–90 peptide. Vaccine-induced Treg cells thus play a crucial role in the control of de novo primed autoreactive effector CD8⁺ T cells in this diabetes model.

Molecular events by which dendritic cells promote Th2 immune protection in helmith infection

Helminth parasites are a major cause of global infectious diseases, affecting nearly one quarter of the world's population. The common feature of helminth infections is to skew the immune system towards a T-helper 2 (Th2) response that helps to control disease. Dendritic cells (DCs), which are professional antigen-presenting cells, play a critical role for Th2 skewing against helminth parasites. However, the molecular mechanisms by which helminth antigens activate DCs for Th2 polarization have not yet been clearly defined. This review provides a focused update on the major role of DCs for inducing and/or enhancing Th2 immune responses in helminthic infection and will discuss the main signalling-dependent and independent mechanisms by which helminth antigens activate DCs for Th2 skewing.

The E3 ligase Itch in immune regulation and beyond

Itch or itchy E3 ubiquitin ligase was initially discovered by genetic studies on the mouse coat color changes, and its deletion results in an itchy phenotype with constant skin scratching and multi-organ inflammation. It is a member of the homologous to E6-associated protein C-terminus (HECT)-type family of E3 ligases, with the protein-interacting WW-domains for the recruitment of substrate and the HECT domain for the transfer of ubiquitin to the substrate. Since its discovery, numerous studies have demonstrated that Itch is involved in the control of many aspects of immune responses including T-cell activation and tolerance and T-helper cell differentiation. Itch is also implicated in other biological contexts such as tumorigenesis, development, and stress responses. Many signaling pathways are regulated by Itch-promoted ubiquitylation of diverse target proteins. Itch is also involved in human diseases. Here, we discuss the major progress in understanding the biological significance of Itch-promoted protein ubiquitylation in the immune and other systems and in Itch-mediated regulation of signal transduction.

Immuno-pharmacodynamics for evaluating mechanism of action and developing immunotherapy combinations

Immunotherapy has become a major modality of cancer treatment, with multiple new classes of immunotherapeutics recently entering the clinic and obtaining market approval from regulatory agencies. While the promise of these therapies is great, so is the number of possible combinations not only with each other but also with small molecule therapeutics. Furthermore, the observation of unusual dose-response relationships suggests a critical dependency of drug effectiveness on the dosage regimen (dose and schedule). Clinical pharmacodynamic (PD) biomarkers will be useful endpoints for confirming drug mechanism of action, evaluating combination therapies for synergy or antagonism, and identifying optimal dosage regimens. In contrast to conventional PD in which drug action occurs entirely within a single target cell (ie, is self-contained within the malignant cell), immunotherapy involves a complex mechanism of action with sequential steps that propagate through multiple cell types, both normal and malignant. Its intercellular pharmacology begins with molecular target engagement either on an immune effector cell or a malignant cell, followed by stimulatory biochemical and biological signals in immune effector cells, and then finally ends with activation of cell death mechanisms in malignant cells lying within a certain distance from the activated effector cells (immune cell-tumor cell proximity). Evaluating such "trans-cellular pharmacology," in which different steps of drug action are distributed across multiple cell types, requires novel microscopy and image analysis tools capable of quantifying PD-biomarker responses, mapping the responses onto the cellular geography of the tumor using phenotypic biomarkers to identify specific cell types, and finally analyzing the spatial relationships between biomarkers in the context of each cell's biological role. We have termed this form of nearest neighbor image analysis of drug action "proximity PD microscopy," to indicate the importance of the location of the PD-biomarker response within the cellular landscape of a tumor specimen. We discuss herein the major modes of immunotherapy, and lay out a blueprint for using PD assessment to optimize dosage regimens of single agents and guide development of combination immunotherapy regimens, using PD1/PD-L1 immune checkpoint inhibition as a case study.

Mitochondria, calcium, and tumor suppressor Fus1: At the crossroad of cancer, inflammation, and autoimmunity

Mitochondria present a unique set of key intracellular functions such as ATP synthesis, production of reactive oxygen species (ROS) and Ca²⁺ buffering. Mitochondria both encode and decode Ca²⁺ signals and these interrelated functions have a direct impact on cell signaling and metabolism.

High proliferative potential is a key energy-demanding feature shared by cancer cells and activated T lymphocytes. Switch of a metabolic state mediated by alterations in mitochondrial homeostasis plays a fundamental role in maintenance of the proliferative state. Recent studies show that tumor suppressors have the ability to affect mitochondrial homeostasis controlling both cancer and autoimmunity. Herein, we discuss established and putative mechanisms of calcium–dependent regulation of both T cell and tumor cell activities. We use the mitochondrial protein Fus1 as a case of tumor suppressor that controls immune response and tumor growth via maintenance of mitochondrial homeostasis. We focus on the regulation of mitochondrial Ca²⁺ handling as a key function of Fus1 and highlight the mechanisms of a crosstalk between Ca²⁺ accumulation and mitochondrial homeostasis. Given the important role of Ca²⁺ signaling, mitochondrial Ca²⁺ transport and ROS production in the activation of NFAT and NF-κB transcription factors, we outline the importance of Fus1 activities in this context.

Emerging therapies provide new opportunities to reshape the multifaceted interactions between the immune system and lymphoma cells

The acquisition of a complete neoplastic phenotype requires cancer cells to develop escape mechanisms from the host immune system. This phenomenon, commonly referred to as 'immune evasion,' represents a hallmark of cancers and results from a Darwinian selection of the fittest tumor clones. First reported in solid tumors, cancer immunoescape characterizes several hematological malignancies. The biological bases of cancer immunoescape have recently been disclosed and include: (i) impaired human leukocyte antigen-mediated cancer cell recognition (B2M, CD58, CTIIA, CD80/CD86, CD28 and CTLA-4 mutations); (ii) deranged apoptotic mechanisms (reduced pro-apoptotic signals and/or increased expression of anti-apoptotic molecules); and (iii) changes in the tumor microenvironment involving regulatory T cells and tumor-associated macrophages. These immune-escape mechanisms characterize both Hodgkin and non-Hodgkin (B and T cell) lymphomas and represent a promising target for new anti-tumor therapies. In the present review, the principles of cancer immunoescape and their role in human lymphomagenesis are illustrated. Current therapies targeting these pathways and possible applications for lymphoma treatment are also addressed.

Incomplete clonal deletion as prerequisite for tissue-specific minor antigen tolerization

Central clonal deletion has been considered the critical factor responsible for the robust state of tolerance achieved by chimerism-based experimental protocols, but split-tolerance models and the clinical experience are calling this assumption into question. Although clone-size reduction through deletion has been shown to be universally required for achieving allotolerance, it remains undetermined whether it is sufficient by itself. Therapeutic Treg treatment induces chimerism and tolerance in a stringent murine BM transplantation model devoid of myelosuppressive recipient treatment. In contrast to irradiation chimeras, chronic rejection (CR) of skin and heart allografts in Treg chimeras was permanently prevented, even in the absence of complete clonal deletion of donor MHC-reactive T cells. We show that minor histocompatibility antigen mismatches account for CR in irradiation chimeras without global T cell depletion. Furthermore, we show that Treg therapy-induced tolerance prevents CR in a linked suppression-like fashion, which is maintained by active regulatory mechanisms involving recruitment of thymus-derived Tregs to the graft. These data suggest that highly efficient intrathymic and peripheral deletion of donor-reactive T cells for specificities expressed on hematopoietic cells preclude the expansion of donor-specific Tregs and, hence, do not allow for spreading of tolerance to minor specificities that are not expressed by donor BM.

Fine-tuning of the mucosal barrier and metabolic systems using the diet-microbial metabolite axis

The human intestinal microbiota has profound effects on human physiology, including the development and maintenance of the host immune and metabolic systems. Under physiological conditions, the intestinal microbiota maintains a symbiotic relationship with the host. Abnormalities in the host-microbe relationship, however, have been implicated in multiple disorders such as inflammatory bowel diseases (IBDs), metabolic syndrome, and autoimmune diseases. There is a close correlation between dietary factors and the microbial composition in the gut. Long-term dietary habits influence the composition of the gut microbial community and consequently alter microbial metabolic activity. The diet-microbiota axis plays a vital role in the regulation of the host immune system, at least partly through altering microbial metabolism. In this review, we will describe the current findings regarding how dietary factors and microbial metabolites regulate the host immune system.

Helicobacter pylori-Mediated Protection from Allergy Is Associated with IL-10-Secreting Peripheral Blood Regulatory T Cells

Helicobacter pylori infections are usually established in early childhood and continuously stimulate immunity, including T-helper 1 (Th1), Th17, and regulatory T-cell (Treg) responses, throughout life. Although known to be the major cause of peptic ulcer disease and gastric cancer, disease occurs in a minority of those who are infected. Recently, there has been much interest in beneficial effects arising from infection with this pathogen. Published data robustly show that the infection is protective against asthma in mouse models. Epidemiological studies show that H. pylori is inversely associated with human allergy and asthma, but there is a paucity of mechanistic data to explain this. Since Th1 and Treg responses are reported to protect against allergic responses, we investigated if there were links between the human systemic Th1 and Treg response to H. pylori and allergen-specific IgE levels. The human cytokine and T-cell responses were examined using peripheral blood mononuclear cells (PBMCs) from 49 infected and 58 uninfected adult patients. Concentrations of total and allergen-specific plasma IgE were determined by ELISA and ImmunoCAP assays. These responses were analyzed according to major virulence factor genotypes of the patients' colonizing H. pylori strains. An in vitro assay was employed, using PBMCs from infected and uninfected donors, to determine the role of Treg cytokines in the suppression of IgE. Significantly higher frequencies of IL-10-secreting CD4(+)CD25(hi) Tregs, but not H. pylori-specific Th1 cells, were present in the peripheral blood of infected patients. Total and allergen-specific IgE concentrations were lower when there was a strong Treg response, and blocking IL-10 in vitro dramatically restored IgE responses. IgE concentrations were also significantly lower when patients were infected with CagA(+) strains or those expressing the more active i1 form of VacA. The systemic IL-10(+) Treg response is therefore likely to play a role in H. pylori-mediated protection against allergy in humans.

Peripheral phenotype and gene expression profiles of combined liver-kidney transplant patients

BACKGROUND AND AIMS

The beneficial effect of one graft on another has been reported in combined transplantation but the associated mechanisms and biological influence of each graft have not yet been established.

METHODS

In multiple analyses, we explored the PBMC phenotype and signature of 45 immune-related messenger RNAs and 754 microRNAs from a total of 235 patients, including combined liver-kidney transplant recipients (CLK), patients with a liver (L-STA) or kidney (K-STA) graft only under classical immunosuppression and patients with tolerated liver (L-TOL) or kidney grafts (K-TOL).

RESULTS

CLK show an intermediary phenotype with a higher percentage of peripheral CD19(+) CD24(+) CD38(Low) memory B cells and Helios(+) Treg cells, two features associated with tolerance profiles, compared to L-STA and K-STA (P < 0.05, P < 0.01). Very few miRNA were significantly differentially expressed in CLK vs. K-STA and even fewer when compared to L-STA (35 and 8, P < 0.05). Finally, CLK are predicted to share common miRNA targets with K-TOL and even more with L-TOL (344 and 411, P = 0.005). Altogether CLK display an intermediary phenotype and gene profile, which is closer to that of liver transplant patients, with possible similarities with the profiles of tolerant patients.

CONCLUSION

These data suggest that CLK patients show the immunological influence of both allografts with liver having a greater influence.

Levels of regulatory T cells CD69(+)NKG2D(+)IL-10(+) are increased in patients with autoimmune thyroid disorders

Regulatory T (Treg) cells play an important role in the pathogenesis of autoimmune thyroid disorders (AITD). New subsets of CD4(+)CD69(+) and CD4(+)NKG2D(+) T lymphocytes that behave as regulatory cells have been recently reported. The role of these immunoregulatory lymphocytes has not been previously explored in AITD. We analyzed by multi-parametric flow cytometry different Treg cell subsets in peripheral blood from 32 patients with AITD and 19 controls, and in thyroid tissue from seven patients. The suppressive activity was measured by an assay of inhibition of lymphocyte activation. We found a significant increased percentage of CD4(+)CD69(+)IL-10(+), CD4(+)CD69(+)NKG2D(+), and CD4(+)CD69(+)IL-10(+)NKG2D(+) cells, in peripheral blood from GD patients compared to controls. The increase in CD4(+)CD69(+)IL-10(+) and CD4(+)CD69(+)IL-10(+)NKG2D(+) T cells was especially remarkable in patients with active Graves' ophthalmopathy (GO), and a significant positive correlation between GO activity and CD4(+)CD69(+)IL-10(+) or CD4(+)CD69(+)IL-10(+)NKG2D(+) cells was also found. In addition, these cells were increased in patients with a more severe and/or prolonged disease. Thyroid from AITD patients showed an increased proportion of CD69(+) regulatory T cells subpopulations compared to autologous peripheral blood. The presence of CD69(+), NKG2D(+), and IL-10(+) cells was confirmed by immunofluorescence microscopy. In vitro functional assays showed that CD69(+) Treg cells exerted an important suppressive effect on the activation of T effector cells in controls, but not in AITD patients. Our findings suggest that the levels of CD69(+) regulatory lymphocytes are increased in AITD patients, but they are apparently unable to down-modulate the autoimmune response and tissue damage.

Foxp3(+) T cells expressing RORγt represent a stable regulatory T-cell effector lineage with enhanced suppressive capacity during intestinal inflammation

Foxp3 (forkhead box P3 transcription factor)-expressing regulatory T cells (Tregs) are essential for immunological tolerance, best illustrated by uncontrolled effector T-cell responses and autoimmunity upon loss of Foxp3 expression. Tregs can adopt specific effector phenotypes upon activation, reflecting the diversity of functional demands in the different tissues of the body. Here, we report that Foxp3(+)CD4(+) T cells coexpressing retinoic acid-related orphan receptor-γt (RORγt), the master transcription factor for T helper type 17 (Th17) cells, represent a stable effector Treg lineage. Transcriptomic and epigenetic profiling revealed that Foxp3(+)RORγt(+) T cells display signatures of both Tregs and Th17 cells, although the degree of similarity was higher to Foxp3(+)RORγt(-) Tregs than to Foxp3(-)RORγt(+) T cells. Importantly, Foxp3(+)RORγt(+) T cells were significantly demethylated at Treg-specific epigenetic signature genes such as Foxp3, Ctla-4, Gitr, Eos, and Helios, suggesting that these cells have a stable regulatory rather than inflammatory function. Indeed, adoptive transfer of Foxp3(+)RORγt(+) T cells in the T-cell transfer colitis model confirmed their Treg function and lineage stability in vivo, and revealed an enhanced suppressive capacity as compared with Foxp3(+)RORγt(-) Tregs. Thus, our data suggest that RORγt expression in Tregs contributes to an optimal suppressive capacity during gut-specific immune responses, rendering Foxp3(+)RORγt(+) T cells as an important effector Treg subset in the intestinal system.

Comparative Analysis of Protocols to Induce Human CD4+Foxp3+ Regulatory T Cells by Combinations of IL-2, TGF-beta, Retinoic Acid, Rapamycin and Butyrate

Regulatory T cells (Tregs) suppress other immune cells and are critical mediators of peripheral tolerance. Therapeutic manipulation of Tregs is subject to numerous clinical investigations including trials for adoptive Treg transfer. Since the number of naturally occurring Tregs (nTregs) is minute, it is highly desirable to develop a complementary approach of inducing Tregs (iTregs) from naïve T cells. Mouse studies exemplify the importance of peripherally induced Tregs as well as the applicability of iTreg transfer in different disease models. Yet, procedures to generate iTregs are currently controversial, particularly for human cells. Here we therefore comprehensively compare different established and define novel protocols of human iTreg generation using TGF-β in combination with other compounds. We found that human iTregs expressed several Treg signature molecules, such as Foxp3, CTLA-4 and EOS, while exhibiting low expression of the cytokines Interferon-γ, IL-10 and IL-17. Importantly, we identified a novel combination of TGF-β, retinoic acid and rapamycin as a robust protocol to induce human iTregs with superior suppressive activity in vitro compared to currently established induction protocols. However, iTregs generated by these protocols did not stably retain Foxp3 expression and did not suppress in vivo in a humanized graft-versus-host-disease mouse model, highlighting the need for further research to attain stable, suppressive iTregs. These results advance our understanding of the conditions enabling human iTreg generation and may have important implications for the development of adoptive transfer strategies targeting autoimmune and inflammatory diseases.

Characterization of Regulatory T-Cell Markers in CD4+ T Cells of the Upper Airway Mucosa

CD4+ T regulatory cells (Tregs) comprise a heterogeneous population of cells the regulate immune responses and prevent autoimmunity. Most reports on human Tregs are derived from studies of peripheral blood, although Tregs mainly exert their functions in the periphery. Here we performed a detailed analysis of Tregs in the human upper airway mucosa under non-inflammatory conditions, and found that 10% of all CD4+ T cells expressed the transcription factor FOXP3 and the memory marker CD45RO, as well as high levels of CTLA-4. The majority of FOXP3+CD4+ T cells co-expressed the transcription factor Helios and produced very little cytokines, compatible with being thymus-derived Tregs. FOXP3+Helios-CD4+ T cells were more heterogeneous. A mean of 24% produced the immunomodulatory cytokine IL-10, whereas a large fraction also produced IL-2, IFN-μ or IL-17. A significant population (6%) of FOXP3-negative T cells also produced IL-10, usually in combination with IFN-μ. Together, we found that CD4+ T cells in the upper airways differed functionally from their counterparts in peripheral blood, including higher expression of IL-10. Moreover, our findings suggest that several subsets of CD4+ T cells with functionally distinct regulatory properties reside in the upper airway mucosa which should be taken into account when targeting Tregs for therapy.

Minipigs in Translational Immunosafety Sciences: A Perspective

The porcine immune system has been studied especially with regard to infectious diseases of the domestic pig, highlighting the economic importance of the pig in agriculture. Recently, in particular, minipigs have received attention as alternative species to dogs or nonhuman primates in drug safety evaluations. The increasing number of new drug targets investigated to modulate immunological pathways has triggered renewed interest to further explore the porcine immune system. Comparative immunological studies of minipigs with other species broaden the translational models investigated in drug safety evaluations. The porcine immune system overall seems functionally similar to other mammalian species, but there are some anatomical, immunophenotypical, and functional differences. Here, we briefly review current knowledge of the innate and adaptive immune system in pigs and minipigs. In conclusion, more systematic and cross-species comparisons are needed to assess the significance of immunological findings in minipigs in the context of translational safety sciences.

Liver sinusoidal endothelial cells induce tolerance of autoreactive CD4+ recent thymic emigrants

The liver is a unique lymphoid organ whose microenvironment is biased towards tolerance induction. We previously found that a proportion of CD4(+) autoreactive recent thymic emigrants (RTEs) retained in the liver after thymic egress and acquired IL-10 producing capability. To investigate the tolerance of these liver persisting CD4(+) RTEs in more detail and to study the liver stromal cell types that facilitate the tolerogenic changes in young T cells, the phenotype and function of liver RTEs were further characterized and the impact of liver sinusoidal endothelial cells (LSECs) and Kupffer cells on RTEs were examined using an in vitro co-culture system. More than 70% of CD4(+) CD44(hi) RTEs in the liver acquired Foxp3(-)LAG3(+) CD49b(-) regulatory phenotype and function. But higher ratio of apoptosis with enhanced FasL and Bim expression was also found in these CD4(+) liver RTEs when compared to those in the lymph nodes and spleen. LSECs played an important role in RTEs' acquisition of tolerogenic and regulatory phenotype. These results indicate an important role of liver microenvironment in enforcing peripheral tolerance to CD4(+) thymic emigrants against self- and gut-derived antigens.

T(reg) stability: to be or not to be

Regulatory T cell (T(reg)) stability has been primarily determined by the maintained expression of the transcription factor Forkhead box P3 (Foxp3). However, T(regs) can exhibit instability while maintaining Foxp3 expression, requiring a re-examination of what defines T(reg) stability. Recent work suggests that the establishment and stability of T(regs) is mediated by a number of mechanisms besides Foxp3 expression, such as epigenetic modifications, Foxo1/3a localization, expression of Eos and signaling via Neuropilin-1. Additional studies may help to define approaches that can undermine T(reg) stability in cancer or enhance T(reg) stability in transplantation, autoimmune or inflammatory diseases and therefore have substantial therapeutic utility. In this review, we will discuss how T(reg) stability is defined and the mechanisms utilized to maintain stability.

IL-12 receptor 1β deficiency with features of autoimmunity and photosensitivity

Primary immunodeficiences are often accompanied by autoimmune phenomena. IL-12 receptor deficiency is a well characterized primary immunodeficiency that leads to propensity to intracellular infections mainly with mycobacteria and Salmonella. We report on two patients with IL-12 receptor β1 deficiency that presented with autoimmune manifestations and photosensitivity dermatitis and describe possible pathogenetic mechanisms leading to development of clinically significant autoimmune phenomena.

Dendritic Cells Induce a Subpopulation of IL-12Rβ2-Expressing Treg that Specifically Consumes IL-12 to Control Th1 Responses

Cytokines secreted from dendritic cells (DCs) play an important role in the regulation of T helper (Th) cell differentiation and activation into effector cells. Therefore, controlling cytokine secretion from DCs may potentially regulate Th differentiation/activation. DCs also induce de-novo generation of regulatory T cells (Treg) that modulate the immune response. In the current study we used the mixed leukocyte reaction (MLR) to investigate the effect of allospecific Treg on IL-12, TNFα and IL-6 secretion by DCs. Treg cells were found to markedly down-regulate IL-12 secretion from DCs following stimulation with TLR7/8 agonist. This down-regulation of IL-12 was neither due to a direct suppression of its production by the DCs nor a result of marked DC death. We found that IL-12 was rather actively consumed by Treg cells. IL-12 consumption was mediated by a subpopulation of IL-12Rβ2-expressing Treg cells and was dependent on MHC class-II expressed on dendritic cells. Furthermore, IL-12 consumption by Tregs increased their suppressive effect on T cell proliferation and Th1 activation. These results provide a new pathway of Th1 response regulation where IL-12 secreted by DCs is consumed by a sub-population of IL-12Rβ2-expressing Treg cells. Consumption of IL-12 by Tregs not only reduces the availability of IL-12 to Th effector cells but also enhances the Treg immunosuppressive effect. This DC-induced IL-12Rβ2-expressing Treg subpopulation may have a therapeutic advantage in suppressing Th1 mediated autoimmunity.

WNT5A transforms intestinal CD8αα⁺ IELs into an unconventional phenotype with pro-inflammatory features

Background

Intestinal intraepithelial lymphocytes that reside within the epithelium of the intestine form one of the main branches of the immune system. A majority of IELs express CD8α homodimer together with other molecules associated with immune regulation. Growing evidence points to the WNT signaling pathway as a pivotal piece in the immune balance and focuses on its direct regulation in intestinal epithelium. Therefore we decided to investigate its role in IELs’ immune status determination.

Method

DSS colitis was induced in male C57BL mice. IELs were isolated from colon samples using mechanical dissociation followed by percoll gradient purification and Magnetic-activated cell sorting. Phenotype and cytokine production and condition with Wnts were analyzed by flow cytometry, real-time PCR or ELISA. Proliferation of lymphocytes were evaluated using CFSE dilution. Cell responses after WNT pathway interference were also evaluated.

Results

Non-canonical WNT pathway elements represented by FZD5, WNT5A and NFATc1 were remarkably elevated in colitis IELs. The non-canonical WNT5A skewed them into a pro-inflammatory category as measured by inhibitory cell surface marker LAG3, LY49E, NKG2A and activated marker CD69 and FASL. Gaining of a pro-inflammatory marker was correlated with increased IFN-γ production but not TNF whilst decreased TGF-β and IL-10. Both interrupting WNT5A/PKC pathway and adding canonical WNT stimulants could curtail its immune-activating effect.

Conclusion

Canonical and non-canonical WNT signals act in opposing manners concerning determining CD8αα⁺ IELs immune status. Targeting non-canonical WNT pathway may be promising in tackling inflammatory bowel disease.

IL-27-induced modulation of autoimmunity and its therapeutic potential

Interleukin-27 (IL-27) is a new member of the IL-12 family. It is produced by activated antigen-presenting cells and plays an important role in the regulation of CD4+ T cell differentiation and immune response. IL-27 activates multiple signaling cascades, including the JAK-STAT and p38 MAPK pathways. Several studies have revealed that IL-27 promotes the differentiation of Th1 and Tr1, but inhibits Th2, Th17, and Treg cells. However, a few studies have shown an opposite effect on certain T cell subsets, such as Treg. IL-27 displays both pro- and anti- inflammatory activities in different autoimmune diseases. Here, we have discussed the role of IL-27 in rheumatoid arthritis, multiple sclerosis, colitis, lupus, psoriasis, type 1 diabetes, and uveitis. Most of this information is derived from experimental models of these autoimmune diseases. The mechanistic basis of the dual role of IL-27 in inflammation and autoimmunity is still not fully defined. In general, the pro-/anti-inflammatory activity of IL-27 is influenced by the underlying immune effector pathways, the phase of the disease, the presence or absence of counter-regulatory cytokines/T cell subsets, and the tissue/cell type under study. Despite a spectrum of outcomes in various autoimmune diseases, mostly anti-inflammatory and immunomodulatory effects of IL-27 have been observed in this category of diseases. Accordingly, IL-27 represents a novel, promising target/agent for the treatment of autoimmune diseases.

Looking beyond the induction of Th2 responses to explain immunomodulation by helminths

Although helminth infections are characteristically associated with Th2-mediated responses that include the production of the prototypical cytokines IL-4, IL-5 and IL-13 by CD4(+) cells, the production of IgE, peripheral blood eosinophilia and mucus production in localized sites, these responses are largely attenuated when helminth infections become less acute. This modulation of the immune response that occurs with chronic helminth infection is often induced by molecules secreted by helminth parasites, by non-Th2 regulatory CD4(+) cells, and by nonclassical B cells, macrophages and dendritic cells. This review will focus on those parasite- and host-mediated mechanisms underlying the modulated T-cell response that occurs as the default in chronic helminth infections.

Pasteurella multocida Toxin Manipulates T Cell Differentiation

Pasteurella multocida causes various diseases in a broad range of wild and domestic animals. Toxigenic strains of the serotypes A and D produce an AB protein toxin named Pasteurella multocida toxin (PMT). PMT constitutively activates the heterotrimeric G protein subunits Gαq, Gα13, and Gαi through deamidation of a glutamine residue, which results in cytoskeletal rearrangements as well as increased proliferation and survival of the host cell. In human monocytes, PMT alters the lipopolysaccharide (LPS)-induced activation toward a phenotype that suppresses T cell activation. Here we describe that the toxin also modulates CD4-positive T helper (Th) cells directly. PMT amplifies the expansion of Th cells through enhanced cell cycle progression and suppression of apoptosis and manipulates the differentiation of Th subclasses through activation of Signal Transducers and Activators of Transcription (STAT) family members and induction of subtype-specific master transcription factors. A large population of toxin-treated T cells is double-positive for Foxp3 and RORγt, the transcription factors expressed by Treg and Th17 cells, respectively. This suggests that these cells could have the potential to turn into Th17 cells or suppressive Treg cells. However, in terms of function, the PMT-differentiated cells behave as inflammatory Th17 cells that produce IL-17 and trigger T cell proliferation.

Helios Controls a Limited Subset of Regulatory T Cell Functions

A subpopulation (60-70%) of Foxp3(+) regulatory T cells (Tregs) in both mouse and man expresses the transcription factor Helios, but its role in Treg function is still unknown. We generated Treg-specific Helios-deficient mice to examine the function of Helios in Tregs. We show that the selective deletion of Helios in Tregs leads to slow, progressive systemic immune activation, hypergammaglobulinemia, and enhanced germinal center formation in the absence of organ-specific autoimmunity. Helios-deficient Treg suppressor function was normal in vitro, as well as in an in vivo inflammatory bowel disease model. However, Helios-deficient Tregs failed to control the expansion of pathogenic T cells derived from scurfy mice, failed to mediate T follicular regulatory cell function, and failed to control both T follicular helper cell and Th1 effector cell responses. In competitive settings, Helios-deficient Tregs, particularly effector Tregs, were at a disadvantage, indicating that Helios regulates effector Treg fitness. Thus, we demonstrate that Helios controls certain aspects of Treg-suppressive function, differentiation, and survival.

Improving the anti-inflammatory effect of serum eye drops using allogeneic serum permissive for regulatory T cell induction

PURPOSE

To investigate the cytokine composition and anti-inflammatory effects of allogeneic serum preparations for improved use as serum eye drops.

METHODS

Serum of 15 healthy blood donors was extensively screened for cytokines, including IL-1β, IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12p70, IL-13, IL-15, 1L-17A, E and F, IL-21, IL-22, IL-23, IL-27, IL-28A, IL-31, IL-33, granulocyte macrophage colony-stimulating factor (GM-CSF), chemokine ligand 20 (CCL20), tumour necrosis factor (TNF)-α and TNF-β, interferon (IFN)-γ and transforming growth factor (TGF)-β. The levels of cytokines were assessed before and after heat-induced inactivation. Individual serum preparations were tested for their anti-inflammatory effect using an in vitro test to differentiate effector T lymphocytes into anti-inflammatory regulatory T cells.

RESULTS

The anti-inflammatory cytokine TGF-β was readily detected in the serum of all blood donors and was only modestly affected by heat-induced inactivation. Serum containing high amounts of TGF-β was more effective at inducing anti-inflammatory regulatory T cells. The serum of one healthy blood donor displayed high levels of inflammatory cytokines.

CONCLUSION

We propose that serum used as eye drops is screened for its cytokine content, making it possible to correlate the composition to the clinical outcome. Based on the findings in this study, tailored serum eye drops produced from allogeneic donors may provide increased anti-inflammatory effects. This may be superior to autologous serum eye drops, which in many cases are retrieved from patients with inflammatory diseases.

Promises and paradoxes of regulatory T cells in inflammatory bowel disease

Since their discovery two decades ago, CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) have become the subject of intense investigation by immunologists. Unlike other T cells, which promote an immune response, Tregs actively inhibit inflammation when activated by their cognate antigen, thus raising hope that these cells could be engineered into a highly targeted, antigen-specific, immunosuppressant therapy. Although Tregs represent less than 10% of circulating CD4(+)T cells, they have been shown to play an essential role in preventing or limiting inflammation in a variety of animal models and human diseases. In particular, spontaneous intestinal inflammation has been shown to occur in the absence of Tregs, suggesting that there may be a Treg defect central to the pathogenesis of human inflammatory bowel disease (IBD). However, over the past decade, multiple groups have reported no qualitative or quantitative deficits in Tregs from the intestines and blood of IBD patients to explain why these cells fail to regulate inflammation in Crohn's disease and ulcerative colitis. In this review, we will discuss the history of Tregs, what is known about them in IBD, and what progress and obstacles have been seen with efforts to employ them for therapeutic benefit.

LAP TGF-Beta Subset of CD4(+)CD25(+)CD127(-) Treg Cells is Increased and Overexpresses LAP TGF-Beta in Lung Adenocarcinoma Patients

Lung cancer is the leading cause of cancer death worldwide. Adenocarcinoma, the most commonly diagnosed histologic type of lung cancer, is associated with smoking. Cigarette smoke promotes inflammation on the airways, which might be mediated by Th17 cells. This inflammatory environment may contribute to tumor development. In contrast, some reports indicate that tumors may induce immunosuppressive Treg cells to dampen immune reactivity, supporting tumor growth and progression. Thus, we aimed to analyze whether chronic inflammation or immunosuppression predominates at the systemic level in lung adenocarcinoma patients, and several cytokines and Th17 and Treg cells were studied. Higher proportions of IL-17-producing CD4⁺ T-cells were found in smoking control subjects and in lung adenocarcinoma patients compared to nonsmoking control subjects. In addition, lung adenocarcinoma patients increased both plasma concentrations of IL-2, IL-4, IL-6, and IL-10, and proportions of Latency Associated Peptide (LAP) TGF-β subset of CD4⁺CD25⁺CD127⁻ Treg cells, which overexpressed LAP TGF-β. This knowledge may lead to the development of immunotherapies that could inhibit the suppressor activity mediated by the LAP TGF-β subset of CD4⁺CD25⁺CD127⁻ Treg cells to promote reactivity of immune cells against lung adenocarcinoma cells.