Making sense of regulatory T cell suppressive function

Regulatory T Cells in Tumor Microenvironment: Therapeutic Approaches and Clinical Implications

Regulatory T cells (Tregs), previously referred to as suppressor T cells, represent a distinct subset of CD4+ T cells that are uniquely specialized for immune suppression. They are characterized by the constitutive expression of the transcription factor FoxP3 in their nuclei, along with CD25 (the IL-2 receptor α-chain) and CTLA-4 on their cell surface. Tregs not only restrict natural killer cell-mediated cytotoxicity but also inhibit the proliferation of CD4+ and CD8+ T-cells and suppress interferon-γ secretion by immune cells, ultimately impairing an effective antitumor immune response. Treg cells are widely recognized as a significant barrier to the effectiveness of tumor immunotherapy in clinical settings. Extensive research has consistently shown that Treg cells play a pivotal role in facilitating tumor initiation and progression. Conversely, the depletion of Treg cells has been linked to a marked delay in tumor growth and development.

The liver as a central "hub" of the immune system: pathophysiological implications

The purpose of this review is to describe the immune function of the liver, guiding the reader from the homeostatic tolerogenic status to the aberrant activation demonstrated in chronic liver disease. An extensive description of the pathways behind the inflammatory modulation of the healthy liver will be provided focusing on the complex immune cell network residing within the liver. The limit of tolerance will be presented in the context of organ transplantation, seizing the limits of homeostatic mechanisms that fail in accepting the graft, progressing eventually toward rejection. The triggers and mechanisms behind chronic activation in metabolic liver conditions and viral hepatitis will be discussed. The last part of the review will be dedicated to one of the greatest paradoxes for a tolerogenic organ, developing autoimmunity. Through the description of the three most common autoimmune liver diseases, the autoimmune reaction against hepatocytes and biliary epithelial cells will be dissected.

Short-Chain Fatty Acids: Promising Therapeutic Targets for Respiratory Syncytial Virus Infection

The intestinal microbiota is a complex community of organisms present in the human gastrointestinal tract, some of which can produce short-chain fatty acids (SCFAs) through the fermentation of dietary fiber. SCFAs play a major role in mediating the intestinal microbiota's regulation of host immunity and intestinal homeostasis. Respiratory syncytial virus (RSV) can cause an imbalance between anti-inflammatory and proinflammatory responses in the host. In addition, changes in SCFA levels and the structure of the intestinal microbiota have been observed after RSV infection. Therefore, there may be a link between SCFAs and RSV infection, and SCFAs are expected to be therapeutic targets for RSV infection.

Therapeutic potential of natural coumarins in autoimmune diseases with underlying mechanisms

Autoimmune diseases encompass a wide range of disorders characterized by disturbed immunoregulation leading to the development of specific autoantibodies, which cause inflammation and multiple organ involvement. However, its pathogenesis remains unelucidated. Furthermore, the cumulative medical and economic burden of autoimmune diseases is on the rise, making these diseases a ubiquitous global phenomenon that is predicted to further increase in the coming decades. Coumarins, a class of aromatic natural products with benzene and alpha-pyrone as their basic structures, has good therapeutic effects on autoimmune diseases. In this review, we systematically highlighted the latest evidence on coumarins and autoimmune diseases data from clinical and animal studies. Coumarin acts on immune cells and cytokines and plays a role in the treatment of autoimmune diseases by regulating NF-κB, Keap1/Nrf2, MAPKs, JAK/STAT, Wnt/β-catenin, PI3K/AKT, Notch and TGF-β/Smad signaling pathways. This systematic review will provide insight into the interaction of coumarin and autoimmune diseases, and will lay a groundwork for the development of new drugs for autoimmune diseases.

A review of the safety evidence on recombinant human lactoferrin for use as a food ingredient

Published studies on the glycosylation, absorption, distribution, metabolism, excretion, and safety outcomes of orally ingested recombinant human lactoferrin (rhLF) were reviewed in the context of unanswered safety questions, including alloimmunization, allergenicity, and immunotoxicity potential of rhLF during repeated exposure. The primary objective was to summarize current safety data of rhLF produced in transgenic host expression systems. Overall, results from animal and human studies showed that rhLF was well tolerated and safe. Animal data showed no significant toxicity-related outcomes among any safety or tolerability endpoints. The no observed adverse effect levels (NOAEL) were at the highest level tested in both iron-desaturated and -saturated forms of rhLF. Although one study reported outcomes of rhLF on immune parameters, no animal studies directly assessed immunogenicity or immunotoxicity from a safety perspective. Data from human studies were primarily reported as adverse events (AE). They showed no or fewer rhLF-related AE compared to control and no evidence of toxicity, dose-limiting toxicities, or changes in iron status in various subpopulations. However, no human studies evaluated the immunomodulatory potential of rhLF as a measure of safety. Following this review, a roadmap outlining preclinical and clinical studies with relevant safety endpoints was developed to address the unanswered safety questions.

Regulatory T cells: A suppressor arm in post-stroke immune homeostasis

The activation of the immune system and the onset of pro- and anti-inflammatory responses play crucial roles in the pathophysiological processes of ischaemic stroke (IS). CD4+ regulatory T (Treg) cells is the main immunosuppressive cell population that is studied in the context of peripheral tolerance, autoimmunity, and the development of chronic inflammatory diseases. In recent years, more studies have focused on immune modulation after IS, and Treg cells have been demonstrated to be essential in the remission of inflammation, nerve regeneration, and behavioural recovery. However, the exact effects of Treg cells in the context of IS remain controversial, with some studies suggesting a negative correlation with stroke outcomes. In this review, we aim to provide a comprehensive overview of the current understanding of Treg cell involvement in post-stroke homeostasis. We summarized the literature focusing on the temporal changes in Treg cell populations after IS, the mechanisms of Treg cell-mediated immunomodulation in the brain, and the potential of Treg cell-based therapies for treatment. The purposes of the current article are to address the importance of Treg cells and inspire more studies to help physicians, as well as scientists, understand the whole map of immune responses during IS.

Comparative study on the impacts of visnagin and its methoxy derivative khellin on human lymphocyte proliferation and Th1/Th2 balance

BACKGROUND

Visnagin is a phenolic and natural compound in turmeric and fenugreek, and its anti-inflammatory effect has been indicated. Therefore, this study aimed to investigate and compare the anti-inflammatory properties of visnagin and its methoxy derivative khellin on human lymphocytes.

METHODS

Human lymphocytes were treated with khellin, visnagin (10, 30, and 100 µM), and dexamethasone (0.1 mM) in the presence of phytohemagglutinin (PHA). The levels of cell proliferation, nitric oxide (NO), glutathione (GSH), malondialdehyde (MDA), and MDA/GSH ratio were measured using biochemistry methods. Furthermore, the mRNA levels of interferon-γ (IFN-γ), interleukin (IL)-4, and IL-10 were assessed using real-time PCR, while IFN-γ/IL-4(Th₁/Th₂), IFN-γ/IL-10(Th₁/T_reg), and IL-4/IL-10(Th₂/T_reg) ratios were made by dividing their exact values.

RESULTS

In the PHA-stimulated group, GSH and IFN-γ/IL-4 levels were markedly diminished, but other variables were significantly elevated compared to the control group. Khellin and visnagin significantly declined the levels of cell proliferation, MDA, MDA/GSH ratio, and NO production. Khellin and visnagin concentration-dependently diminished IFN-γ and IL-4 levels and increased IL-10 levels compared to the PHA-stimulated group. Two higher concentrations of khellin and visnagin (30 and 100 μM) considerably diminished the IFN-γ, IFN-γ/IL-10, and IL-4/IL-10 values compared to the PHA-stimulated group. However, 100 µM of khellin and visnagin significantly increased GSH level compared to the PHA-stimulated group.

CONCLUSIONS

In PHA-stimulated lymphocytes, representing Th₂ dominant allergic diseases, khellin and visnagin provides more specific anti-oxidant, anti-inflammatory, and immunomodulatory functions than dexamethasone. In addition, the effects of khellin were more prominent than visnagin.

The immunomodulation role of Th17 and Treg in renal transplantation

Kidney transplantation (KT) is an ultimate treatment of end-stage chronic kidney disease, which can meet a lot of complications induced by immune system. With under-controlled immunosuppression, the patient will obtain a good prognosis. Otherwise, allograft disfunction will cause severe organ failure and even immune collapse. Acute or chronic allograft dysfunction after KT is related to Th17, Treg, and Th17/Treg to a certain extent. Elevated Th17 levels may lead to acute rejection or chronic allograft dysfunction. Treg mainly plays a protective role on allografts by regulating immune response. The imbalance of the two may further aggravate the balance of immune response and damage the allograft. Controlling Th17 level, improving Treg function and level, and adjusting Th17/Treg ratio may have positive effects on longer allograft survival and better prognosis of receptors.

Inflammation-mediated changes in haemostatic variables of pulmonary tuberculosis patients during treatment

Tuberculosis (TB) disease is usually marked by inflammation which is closely linked to haemostasis both in health and disease. Close monitoring of haemostatic response to inflammatory changes during treatment is important to improve TB management. Here we studied associations between haemostatic markers and inflammatory cytokines in 60 TB-infected individuals, aged 18-65 years who received anti-TB therapy. They were recruited before commencement of therapy and followed up till completion of therapy after 6-months. The TNF-α, IL-6, IL-2 (pro-inflammatory cytokines) and P-selectin, GP IIb/IIIa, thrombopoietin (haemostatic variables) were significantly increased at 2 month into therapy compared to pre-treatment values and decreased at 6 month into therapy. Also at 6 month into therapy in comparison to 2-month into therapy, there were significant increase in IL-10 and TGF-β (anti-inflammatory cytokines) as well as a significant decline in PF-4. There were significant positive correlations between GP IIb/IIIa and TNF-α, IL-6 and PSEL, IL-6 and TPO, PF4 and TGF-β. Conclusively, the changes in the TNF-α, IL-6, IL-2 aligned with changes in the levels of P-selectin, GP IIb/IIIa, and TPO in the course of TB therapy. This may suggest that the levels of inflammatory cytokines are linked to the levels of these haemostatic variables in TB individuals.

Multi-tissue scRNA-seq reveals immune cell landscape of turbot (Scophthalmus maximus)

In vertebrates, bony fishes possess not only innate immune cells but also T and B cells that are equivalent to those in mammals. However, the precise sub-cluster of immune cells in teleost fish remains largely unknown. Herein, we developed a dynamic bacterial infection model in turbot (Scophthalmus maximus) and created a fish immune cell landscape (FICL) for a primary lymphoid organ (head kidney), a secondary lymphoid organ (spleen), and barrier tissues (gills and posterior intestine). Moreover, through comprehensive characterization of the expression profiles of 16 clusters, including dendritic cells-like (DCs-like), macrophages (MΦs), neutrophils, NK cells, as well as 12 sub-clusters of T and B cells, we found that CD8+ CTLs, CD4-CD8- T, Th17 and ILC3-2 like cells possess a bifunctional role associated with cytotoxicity and immunoregulation during bacterial infection. To our knowledge, these results could provide a useful resource for a better understanding of immune cells in teleost fish and could act as a comprehensive knowledge base for assessing the evolutionary mechanism of adaptive immunity in vertebrates.

IMMUNE RESPONSE UPON THE ADMINISTRATION OF RECOMBINANT PROTEIN ANTIBODIES Ag-38 KDa Mycobacterium tuberculosis AND RIFAMPICIN EX-VIVO

Background

Development a granuloma model resembling latent tuberculosis in vitro is needed with a fast and efficient time to be used as an effective therapy. This study aimed to form efficient granulomas, increase cellular immunity and humoral immunity, and evaluate growth on media using recombinant protein antibody Ag38kDa, Rifampicin, and a combination of both. Peripheral Blood Mononuclear Cell (PBMC) in vitro is derived from a healthy individual separated from monocytes and lymphocytes.

Materials and methods

Monocytes are matured into macrophages and then combined macrophages and lymphocytes to the Roswell Park Memorial Institute (RPMI) medium. Flow cytometry analysis was used to count the number of cells, and cytokine levels were measured using ELISA. The result from the treatment was planted on the Lowenstein-Jensen medium.

Results

Granulomas-like aggregates was formed after one-day post-infection with Mycobacterium tuberculosis (M.tb). A significant increase in immune response occurred in the number of macrophages, Th1, and Tregs in the combination group compared to the Mtb infection group. The number of Th2 and Th17 cells in the combination group was compared with the control but not significantly. TNF-α cytokine levels increased in the combination group compared to Mtb infection, while in IL-4, we found between all groups, there was no significant difference. Bacterial colonies on culture in the Lowenstein-Jensen medium were only seen in positive controls.

Conclusion

Our study concluded that administration of a combination between Ag38kDa recombinant antibody and rifampicin could inhibit granuloma formation and enhance immune response.

Regulatory T cells in ischemic stroke

Recent evidence shows that when ischemic stroke (IS) occurs, the BBB would be destructed, thereby promoting the immune cells to migrate into the brain, suggesting that the immune responses can play a vital role in the pathology of IS. As an essential subpopulation of immunosuppressive T cells, regulatory T (Treg) cells are involved in maintaining immune homeostasis and suppressing immune responses in the pathophysiological conditions of IS. During the past decades, the regulatory role of Treg cells has attracted the interest of numerous researchers. However, whether they are beneficial or detrimental to the outcomes of IS remains controversial. Moreover, Treg cells exert distinctive effects in the different stages of IS. Therefore, it is urgent to elucidate how Treg cells modulate the immune responses induced by IS. In this review, we describe how Treg cells fluctuate and play a role in the regulation of immune responses after IS in both experimental animals and humans, and summarize their biological functions and mechanisms in both CNS and periphery. We also discuss how Treg cells participate in poststroke inflammation and immunodepression and the potential of Treg cells as a novel therapeutic approach.

The small intestine epithelium exempts Foxp3+ Tregs from their IL-2 requirement for homeostasis and effector function

Foxp3⁺ Tregs are potent immunosuppressive CD4⁺ T cells that are critical to maintain immune quiescence and prevent autoimmunity. Both the generation and maintenance of Foxp3⁺ Tregs depend on the cytokine IL-2. Hence, the expression of the IL-2 receptor α-chain (CD25) is not only considered a specific marker, but also a nonredundant requirement for Tregs. Here, we report that Foxp3⁺ Tregs in the small intestine (SI) epithelium, a critical barrier tissue, are exempt from such an IL-2 requirement, since they had dramatically downregulated CD25 expression, showed minimal STAT5 phosphorylation ex vivo, and were unable to respond to IL-2 in vitro. Nonetheless, SI epithelial Tregs survived and were present at the same frequency as in other lymphoid organs, and they retained potent suppressor function that was associated with high levels of CTLA-4 expression and the production of copious amounts of IL-10. Moreover, adoptive transfer experiments of Foxp3⁺ Tregs revealed that such IL-2–independent survival and effector functions were imposed by the SI epithelial tissue, suggesting that tissue adaptation is a mechanism that tailors the effector function and survival requirements of Foxp3⁺ Tregs specific to the tissue environment.

Functional Ambivalence of Dendritic Cells: Tolerogenicity and Immunogenicity

Dendritic cells (DCs) are the most potent professional antigen-presenting cells (APCs) and inducers of T cell-mediated immunity. Although DCs play a central role in promoting adaptive immune responses against growing tumors, they also establish and maintain peripheral tolerance. DC activity depends on the method of induction and/or the presence of immunosuppressive agents. Tolerogenic dendritic cells (tDCs) induce immune tolerance by activating CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cells and/or by producing cytokines that inhibit T cell activation. These findings suggest that tDCs may be an effective treatment for autoimmune diseases, inflammatory diseases, and infertility.

Regulatory T Cells for the Induction of Transplantation Tolerance

Organ transplantation is the optimal treatment for terminal and irreversible organ failure. Achieving transplantation tolerance has long been the ultimate goal in the field of transplantation. Regulatory T cell (Treg)-based therapy is a promising novel approach for inducing donor organ-specific tolerance. Tregs play critical roles in the maintenance of immune homeostasis and self-tolerance, by promoting transplantation tolerance through a variety of mechanisms on different target cells, including anti-inflammatory cytokine production, induction of apoptosis, disruption of metabolic pathways, and mutual interaction with dendritic cells. The continued success of Treg-based therapy in the clinical setting is critically dependent on preclinical studies that support its translational potential. However, although some initial clinical trials of adoptive Treg therapy have successively demonstrated safety and efficacy for immunosuppressant minimization and transplantation tolerance induction, most Treg-based hematopoietic stem cell and solid organ clinical trials are still in their infancy. These clinical trials have not only focused on safety and efficacy but also included optimization and standardization protocols of good manufacturing practice regarding cell isolation, expansion, dosing, timing, specificity, quality control, concomitant immunosuppressants, and post-administration monitoring. We herein report a brief introduction of Tregs, including their phenotypic and functional characterization, and focus on the clinical translation of Treg-based therapeutic applications in the setting of transplantation.

The Complex Role of Regulatory T Cells in Immunity and Aging

The immune system is a tightly regulated network which allows the development of defense mechanisms against foreign antigens and tolerance toward self-antigens. Regulatory T cells (Treg) contribute to immune homeostasis by maintaining unresponsiveness to self-antigens and suppressing exaggerated immune responses. Dysregulation of any of these processes can lead to serious consequences. Classically, Treg cell functions have been described in CD4⁺ T cells, but other immune cells also harbour the capacity to modulate immune responses. Regulatory functions have been described for different CD8⁺ T cell subsets, as well as other T cells such as γδT cells or NKT cells. In this review we describe the diverse populations of Treg cells and their role in different scenarios. Special attention is paid to the aging process, which is characterized by an altered composition of immune cells. Treg cells can contribute to the development of various age-related diseases but they are poorly characterized in aged individuals. The huge diversity of cells that display immune modulatory functions and the lack of universal markers to identify Treg make the expanding field of Treg research complex and challenging. There are still many open questions that need to be answered to solve the enigma of regulatory T cells.

ORMDL3 and Asthma: Linking Sphingolipid Regulation to Altered T Cell Function

Orosomucoid like 3 (ORMDL3) encodes an ER-resident transmembrane protein that regulates the activity of serine palmitoyltransferase (SPT), the first and rate-limiting enzyme for sphingolipid biosynthesis in cells. A decade ago, several genome wide association studies revealed single nucleotide polymorphisms associated with increased ORMDL3 protein expression and susceptibility to allergic asthma. Since that time, numerous studies have investigated how altered ORMDL3 expression might predispose to asthma and other autoimmune/inflammatory diseases. In this brief review, we focus on growing evidence suggesting that heightened ORMDL3 expression specifically in CD4⁺ T lymphocytes, the central orchestrators of adaptive immunity, constitutes a major underlying mechanism of asthma pathogenesis by skewing their differentiation and function. Furthermore, we explore how sphingolipid modulation in T cells might be responsible for these effects, and how further studies may interrogate this intriguing hypothesis.

Stability of regulatory T cells in T helper 2-biased allergic airway diseases

Regulatory T (Treg) cells potentially suppress the deleterious activities of effector T cells and maintain a state of tolerance against antigens in the airway mucosa. A decrease in the number and function of Treg cells is observed in T helper 2 (Th2)-biased allergic airway diseases. However, adoptive transfer of naturally occurring Treg (tTreg) cells or peripherally derived Treg (pTreg) cells in asthmatic mouse models did not yield satisfactory results in any previous studies. Here, we review the recent progress in the identification and plasticity of tTreg and pTreg cells in Th2-biased airway diseases and summarize the factors affecting the stability and function of Treg cells. This review may serve as foundation for understanding the molecular mechanisms underlying the stability of tTreg and pTreg cells and development of effective strategies for treating allergic airway diseases.

Deficient Resident Memory T Cell and CD8 T Cell Response to Commensals in Inflammatory Bowel Disease

BACKGROUND AND AIMS

The intestinal microbiota is closely associated with resident memory lymphocytes in mucosal tissue. We sought to understand how acquired cellular and humoral immunity to the microbiota differ in health versus inflammatory bowel disease [IBD].

METHODS

Resident memory T cells [Trm] in colonic biopsies and local antibody responses to intraepithelial microbes were analysed. Systemic antigen-specific immune T and B cell memory to a panel of commensal microbes was assessed.

RESULTS

Systemically, healthy blood showed CD4 and occasional CD8 memory T cell responses to selected intestinal bacteria, but few memory B cell responses. In IBD, CD8 memory T cell responses decreased although B cell responses and circulating plasmablasts increased. Possibly secondary to loss of systemic CD8 T cell responses in IBD, dramatically reduced numbers of mucosal CD8+ Trm and γδ T cells were observed. IgA responses to intraepithelial bacteria were increased. Colonic Trm expressed CD39 and CD73 ectonucleotidases, characteristic of regulatory T cells. Cytokines/factors required for Trm differentiation were identified, and in vitro-generated Trm expressed regulatory T cell function via CD39. Cognate interaction between T cells and dendritic cells induced T-bet expression in dendritic cells, a key mechanism in regulating cell-mediated mucosal responses.

CONCLUSIONS

A previously unrecognised imbalance exists between cellular and humoral immunity to the microbiota in IBD, with loss of mucosal T cell-mediated barrier immunity and uncontrolled antibody responses. Regulatory function of Trm may explain their association with intestinal health. Promoting Trm and their interaction with dendritic cells, rather than immunosuppression, may reinforce tissue immunity, improve barrier function, and prevent B cell dysfunction in microbiota-associated disease and IBD aetiology.

NLRP3 negatively regulates Treg differentiation through Kpna2-mediated nuclear translocation

Naïve CD4⁺ T cells in the periphery differentiate into regulatory T cells (Tregs) in which Foxp3 is expressed for their suppressive function. NLRP3, a pro-inflammatory molecule, is known to be involved in inflammasome activation associated with several diseases. Recently, the expression of NLRP3 in CD4⁺ T cells, as well as in myeloid cells, has been described; however, a role of T cell-intrinsic NLRP3 in Treg differentiation remains unknown. Here, we report that NLRP3 impeded the expression of Foxp3 independent of inflammasome activation in Tregs. NLRP3-deficient mice elevate Treg generation in various organs in the de novo pathway. NLRP3 deficiency increased the amount and suppressive activity of Treg populations, whereas NLRP3 overexpression reduced Foxp3 expression and Treg abundance. Importantly, NLRP3 interacted with Kpna2 and translocated to the nucleus from the cytoplasm under Treg-polarizing conditions. Taken together, our results identify a novel role for NLRP3 as a new negative regulator of Treg differentiation, mediated via its interaction with Kpna2 for nuclear translocation.

Decrease in Secondary Neck Vessels in Multiple Sclerosis: A 5-year Longitudinal Magnetic Resonance Angiography Study

BACKGROUND

Studies have previously shown greater arterial and venous extracranial vascular changes in persons with multiple sclerosis (PwMS) when compared to healthy controls (HCs).

OBJECTIVES

To determine the change in the number and size of secondary neck vessels in PwMS and HCs over a 5-year follow-up period.

METHODS

Both at baseline and follow-up, 83 PwMS and 25 HCs underwent magnetic resonance angiography (MRA) imaging and analysis. The number and cross-sectional area (CSA) of all secondary neck vessels (excluding the common/internal carotid, vertebral artery, and internal jugular vein) measured at levels from C2-T1 were determined by semi-automated edge detection/ contouring software. The longitudinal change in the number and CSA of the secondary neck vessels from the PwMS and HCs were analyzed by non-parametric Wilcoxon repeated measure. Benjamini-Hochberg procedure adjusted for false discovery rate (FDR).

RESULTS

For over 5 years, PwMS demonstrated a consistent longitudinal decrease in both the number of secondary neck vessels (Z-change between -3.3 and -5.4, q=0.001) and their CSA (Zchange between -2.9 and -5.2, q=0.004). On the contrary, the HCs did not demonstrate a significant longitudinal change in secondary neck vessels over the follow-up period. Due to the longitudinal decrease, the PwMS showed a lower number of secondary neck vessels when compared to HCs measured at follow-up (p<0.029, except for C4 with trending p=0.071). The PwMS changes were also corroborated within each MS phenotype.

CONCLUSION

PwMS demonstrate a significant mid-term decrease in the number and the size of the secondary neck vessels. The clinical relevance of these findings and the effect on intracranial blood flow are currently unknown.

The significance role of regulatory T cells in the persistence of infections by intracellular bacteria

Regulatory T cells (Treg cells), are considered as effective immune cells playing a key role in immune response during cancers, autoimmune and infectious diseases. Regulatory T lymphocytes are divided into two main subgroups: natural Treg cells that generated during maturation in the thymus and have the suppressive activity that is critical for the establishment and maintenance of homeostasis in the body and induced Treg cells (iTreg) that are originated from naive T cells following the self-antigen recognition. In recent years, the roles of Treg in immune responses to microbial infections have received increased attention in researches. Several reports suggested the pivotal role of Treg cells in controlling responses to bacterial infections and demonstrated the impact of regulatory cells on one or more stages in the pathogenesis of bacterial infections. In this review, we describe the significance of regulatory T cells in the immunopathology of bacterial infections by focusing on specific bacterial infections including Mycobacteria, Listeria monocytogenes, and Bordetella pertussis. Moreover, suppressive mechanisms of regulatory T cells during bacterial infection including cell-cell contact, local secretion of inhibitory cytokines and local competition for growth factors will be discussed.

Auraptene regulates Th1/Th2/TReg balances, NF-κB nuclear localization and nitric oxide production in normal and Th2 provoked situations in human isolated lymphocytes

BACKGROUND

Auraptene as member of dietary coumarins, is found in citrus fruits. Former studies have demonstrated its anti-inflammatory and anti-cancer activity.

PURPOSE

The mechanism of action and immune-modulatory property of this compound on human lymphocytes are greatly unknown.

STUDY DESIGN/METHODS

The effect of three concentrations (10, 30 and 90 µM) of auraptene or dexamethasone (0.1 mM) were evaluated on percentage of cell proliferation and nitric oxide (NO) production as well as secretion and gene expression of cytokines, and NF-κB level in PHA-stimulated and non-stimulated lymphocytes.

RESULTS

In non-stimulated cells, all three concentrations of auraptene significantly increased the gene expression index of IL-10 (P < 0.05-0.001). The IFN-γ gene expression index, IFN-γ/IL-4 and IL-10/IL-4 gene expression ratio were significantly increased due to the high concentration (90 µM) of auraptene treatment compared to control group (P < 0.05-0.001). In PHA stimulation, all three concentrations of the extract significantly decreased proliferation, cytokines (IL-4, IL-10 and IFN-γ) and NF-κB level as well as NO production, but IFN-γ/IL-4 and IL-10/IL-4 ratio were significantly increased compared control group (P < 0.05-0.001). Gene expression of IL-10 and IL-4 was decreased but that of IFN-γ as well as FN-γ/IL-4 and IL-10/IL-4 ratio were significantly increased due to all three concentrations of auraptene.

CONCLUSION

The results showed promoting effects of auraptene on T cell subsets toward Th1 (IFN-γ) and Treg (IL-10), which suggest its therapeutic value for treatment of Th2 cells predominant diseases including allergic disease such as asthma and atopic dermatitis as well as cancers.

Chronic stress induced duration dependent alterations in immune system and their reversibility in rats

The objective was to find out whether severity of stress effects on immunity increases with duration of exposure and recovery depends on duration of exposure. Adult male rats (n = 30) were subjected to restraint (1 h) followed by forced swimming exercise (15 min) after a gap of 4 h daily for 2, 4 and 8 weeks and allowed to recover for 6 weeks after each exposure period. Exposure of rats to stress resulted in duration dependent significant decreases in leukocyte count, phagocytic indices of neutrophils, number of bone marrow stem cells and serum levels of IL-12 and increases in apoptotic index of peripheral blood mononuclear cells and serum levels of IL-10. The alterations in counts of neutrophils, total immunoglobulin content, phagocytic index, apoptotic index of peripheral blood mononuclear cells and serum levels of IL-10 returned to control levels in recovery group rats of 2 and 4 weeks exposure but not in that of 8 weeks exposure. However, alterations in number and apoptotic index of bone marrow stem cells returned to control levels in 2, 4 and 8 weeks stress recovery groups. The results for the first time reveal that increase in duration of exposure results in more severe damage in immune system and that shorter the exposure period, faster the recovery. In addition, in vitro study for the first time showed that corticosterone causes apoptosis of peripheral blood mononuclear cells and bone marrow stem cells in dose dependent manner. Hence death of leukocytes and their stem cells is the major cause of stress induced immune dysfunction.

Chronic graft-specific cell-mediated immune response toward candidate xenogeneic biomaterial

Despite rabbits becoming an increasingly popular animal model, a flow cytometry panel that combines T cell markers (CD3, CD4, CD8, CD25, FOXP3) with a method for monitoring proliferation is lacking in this species. It has been shown that the rabbit model can be used to identify xenoantigens within bovine pericardium (BP), a common biological heart valve replacement material; however, these methods rely on monitoring the humoral immune response. The development of a rabbit T cell proliferation assay has utility in monitoring graft-specific cell-mediated immune responses toward bovine pericardium. Isolation and culture conditions were optimized to avoid cell death, red blood cell contamination, and non-specific proliferation. Effect of cell culture and stimulation on distribution and intensity of T cell markers was analyzed and compared between cells isolated from naïve and BP-immunized rabbits. Submaximal levels (0.25 μg/mL) of concavalin A were used to stimulate proliferation toward BP extract, with resultant proliferation compared between naïve and BP-immunized rabbits. Density stratification followed by ammonium potassium chloride (ACK) lysis yielded the greatest number of viable peripheral blood mononuclear cells with the least amount of erythrocyte contamination. Flat-bottomed plates were necessary to reduce non-specific proliferation in culture. T cells responded appropriately to maximal mitogenic stimulation (5 μg/mL concavalin A). Interestingly, immunization increased the intensity of FOXP3 in T regulatory cells compared to cells from naïve animals. With addition of submaximal levels of concavalin A, T cells from immunized rabbits proliferated in response to BP protein extract, while cells from naïve rabbits did not. In immunized rabbits, not only did more CD4⁺ T cells proliferate in response to BP re-stimulation, but the intensity of CD25 was increased indicating cell activation. This research provides a functional cell-mediated screening assay for assessment of BP-based biomaterials in rabbits, overcoming the limitations of previous humoral immune system-based assessments of biomaterial antigenicity in this important experimental animal species.

Increased Th17 functions are accompanied by Tregs activities in lupoid leishmaniasis

The immunopathogenesis of lupoid leishmaniasis is challenging. Although an appropriate immune response is critical for controlling these parasites, inappropriate inflammatory reactions can also promote increased pathology. The role of immune modulatory effect of the main transcription factors and cytokines of T regulatory and Th17 cells in pathogenesis of leishmaniasis chronicity was investigated in this study. The gene expression of interleukin-10 (IL-10), transforming growth factor-β (TGF-β1), forkhead box P3 (Foxp3), interleukin-17(IL-17A) and retinoic acid-related orphan receptor gamma t (ROrC) was assessed in peripheral blood mononuclear cells of eighty blood samples from cutaneous leishmaniasis (CL) patients with usual lesions (n = 31), lupoid lesions (n = 29) and healthy volunteers (n = 20). Quantitative relative real-time PCR (qRT-PCR) was performed using the Taqman and Sybergreen methods for expression of target genes. Expression of Foxp3 (P = .013), IL-10 (P < .001) and IL-17A (P < .001) was significantly higher in lupoid patient compare to the nonlupoid group. Expression of Foxp3 (P < .001), IL-10 (P < .001) and IL-17A (P = .033) was significantly more in nonlupoid subjects than in healthy volunteers, except for RORγt. These findings suggest that Foxp3+ cells, IL-10 and IL-17 play important roles in the immunopathogenesis of CL and that these roles differ depending on the causal leishmania species and different body compartments.

Regulatory T Cells and Ocular Graft Versus Host Disease: A Novel Treatment Approach

Graft Versus Host Disease (GVHD) is an inflammatory immune disease, mediated by the donor's immune cells and can arise after allogeneic Hematopoietic Stem Cell Transplantation (HSCT) for the treatment of hematologic malignancies. It can lead to destructive manifestations in various tissues, particularly dermatological, gastrointestinal, and ocular tissues. The most common ocular morbidity is dry eyes, which is often the first manifestation of GVHD. Regulatory T cells (Tr) can be broadly classified as natural or adaptive (induced). After Bone-Marrow Transplantation (BMT), excessively increased levels of type 1 Tr (Tr1) are generally observed with absence of a GVHD, while low levels are seen with severe GVHD. Treatment of patients, undergoing BMT with Interleukin-10 (IL-10)-anergized donor T cells, led to immune reconstitution without the development of GVHD, which resulted in protection against infection and against the return of the cancer. Surprisingly, in both naive syngeneic mouse models of skin and cardiac allografts, graft retention was augmented after infusion of in vitro generated double-negative Tr (DN Tr). In addition, GVHD was reduced in mice with a genetic deficiency in the IL-27 receptor (IL-27R-/-) and in mice treated with anti-IL-27p28-specific antibody. Considering above mentioned findings we would suggest carrying out experiments, using animal models of GVHD, in order to evaluate the potential role of Tr, as an innovative approach to overcome severe ocular morbidity caused by ocular GVHD.

The Role of Transforming Growth Factor Beta-1 in the Progression of HIV/AIDS and Development of Non-AIDS-Defining Fibrotic Disorders

Even after attainment of sustained viral suppression following implementation of highly active antiretroviral therapy, HIV-infected persons continue to experience persistent, low-grade, systemic inflammation. Among other mechanisms, this appears to result from ongoing microbial translocation from a damaged gastrointestinal tract. This HIV-related chronic inflammatory response is paralleled by counteracting, but only partially effective, biological anti-inflammatory processes. Paradoxically, however, this anti-inflammatory response not only exacerbates immunosuppression but also predisposes for development of non-AIDS-related, non-communicable disorders. With respect to the pathogenesis of both sustained immunosuppression and the increased frequency of non-AIDS-related disorders, the anti-inflammatory/profibrotic cytokine, transforming growth factor-β1 (TGF-β1), which remains persistently elevated in both untreated and virally suppressed HIV-infected persons, may provide a common link. In this context, the current review is focused on two different, albeit related, harmful activities of TGF-β1 in HIV infection. First, on the spectrum of anti-inflammatory/immunosuppressive activities of TGF-β1 and the involvement of this cytokine, derived predominantly from T regulatory cells, in driving disease progression in HIV-infected persons via both non-fibrotic and profibrotic mechanisms. Second, the possible involvement of sustained elevations in circulating and tissue TGF-β1 in the pathogenesis of non-AIDS-defining cardiovascular, hepatic, pulmonary and renal disorders, together with a brief comment on potential TGF-β1-targeted therapeutic strategies.

Impaired Function of Bone Marrow Mesenchymal Stem Cells from Immune Thrombocytopenia Patients in Inducing Regulatory Dendritic Cell Differentiation Through the Notch-1/Jagged-1 Signaling Pathway

Immune thrombocytopenia (ITP) is an autoimmune disease in which dendritic cells (DCs) play a crucial role in the breakdown of self-tolerance. Studies have identified the function of mesenchymal stem cells (MSCs) in promoting the development of regulatory DCs (regDCs). Our previous work revealed that MSCs in ITP exerted senescence, apoptosis, and impaired immunosuppressive effects on T and B cells. However, it is unclear whether the effects of MSCs on regDC induction are altered in ITP. Our data demonstrated that MSCs in ITP were impaired in inhibiting CD1a⁺ DC and CD14⁺ DC differentiation from CD34⁺ hematopoietic progenitor cells (CD34⁺ HPCs). DCs differentiated with MSCs in ITP exhibited an increased expression of costimulatory molecules CD80/CD86 and secretion of proinflammatory interleukin-12 (IL-12). Accordingly, the tolerogenic characteristics were deficient in DCs induced by MSCs in ITP. DCs differentiated with MSCs in ITP exhibited an impaired ability to inhibit CD3⁺ T cell proliferation, to suppress T helper (Th)1 cell differentiation, and to induce anergic and regulatory T cells (Tregs). The expression of Notch signaling components was measured in MSCs in ITP. Reduced expression of the ligand Jagged-1, the receptor Notch-1 intracellular domain (NICD-1), and the target gene Hes-1 was identified in MSCs in ITP. The addition of biologically active Jagged-1 to CD34⁺ HPCs was observed to promote regDC differentiation. When cultured on Jagged-1-coated plates, MSCs in ITP showed an enhancement of the Notch-1 pathway activation, Jagged-1 expression, and the function in inducing regDCs. Pretreatment with all-trans retinoic acid (ATRA) was found to partially restore the capacity of MSCs in both ITP patients and healthy controls in inducing CD34⁺-derived regDCs. Our data elucidated that MSCs in ITP were impaired in inducing CD34⁺-regDCs, associated with the Notch-1/Jagged-1 signaling pathway. ATRA could partially correct the impairment of MSCs, suggesting that ATRA could serve as a potential therapeutic alternative for ITP.

[Effects of adipose-derived stem cells and non-methylated CpG-oligodeoxynucleotides on peripheral blood CD4+CD25+ regulatory T cells in young mice with food allergy]

OBJECTIVE

To investigate the effects of adipose-derived stem cells (ADSC) and non-methylated CpG-oligodeoxynucleotides (CpG-ODN) on the expression of peripheral blood CD4⁺CD25⁺ regulatory T (Treg) cells in young mice with food allergy, as well as their immune intervention effects.

METHODS

A total of 40 female BALB/c mice were randomly divided into control group, allergic group, ADSC treatment group, and CpG-ODN treatment group, with 10 mice in each group. A mouse model of food allergy was established by intraperitoneal injection and intragastric administration of ovalbumin (OVA) for sensitization and challenge. The mice in the control group were treated with normal saline at the same dose; the mice in the ADSC treatment group were given intraperitoneal injection of ADSC (1×10⁶ cells for each mouse) before and after OVA challenge, and those in the CpG-ODN treatment group were given intraperitoneal injection of non-methylated CpG-ODN solution (40 μg for each mouse) at 1 hour before challenge by gavage. The allergic symptom scores were determined for each group after model establishment. ELISA was used to measure the serum level of OVA-IgE. Flow cytometry was used to measure the percentage of peripheral blood CD4⁺CD25⁺ Treg cells. Hematoxylin and eosin staining was used for the pathological analysis of the jejunum.

RESULTS

The allergic group had significantly higher allergic symptom scores and serum level of OVA-IgE than the control group (P<0.05). There were no significant differences in the allergic symptom score and the serum level of OVA-IgE between the ADSC treatment group and the CpG-ODN treatment group (P>0.05), but these two groups had significantly lower allergic symptom scores and serum level of OVA-IgE than the allergic group and significantly higher allergic symptom scores and serum level of OVA-IgE than the control group (P<0.01). The allergic group had a significantly lower percentage of peripheral blood CD4⁺CD25⁺ Treg cells than the control group (P<0.05). The ADSC treatment group and the CpG-ODN treatment group had a significantly higher percentage of peripheral blood CD4⁺CD25⁺ Treg cells than the allergic group (P<0.05); there were no significant differences between these two groups or between them and the control group (P>0.05). Pathological results showed structural damage and edema in the jejunal villi, a large number of eosinophils, and lymphocyte infiltration in the allergic group, while the ADSC treatment group and the CpG-ODN treatment group had less structural damage and edema in the jejunal villi, a lower number of eosinophils, and less lymphocyte infiltration.

CONCLUSIONS

ADSC and non-methylated CpG-ODN have a certain effect in the treatment of food allergy and can increase the percentage of peripheral blood CD4⁺CD25⁺ Treg cells and reduce the level of OVA-IgE. They may be associated with the induction of immune tolerance and these two treatment have comparable effects. Detailed mechanisms of action still need further investigation.

[Effects of adipose-derived stem cells and non-methylated CpG-oligodeoxynucleotides on peripheral blood CD4+CD25+ regulatory T cells in young mice with food allergy]

OBJECTIVE

To investigate the effects of adipose-derived stem cells (ADSC) and non-methylated CpG-oligodeoxynucleotides (CpG-ODN) on the expression of peripheral blood CD4+CD25+ regulatory T (Treg) cells in young mice with food allergy, as well as their immune intervention effects.

METHODS

A total of 40 female BALB/c mice were randomly divided into control group, allergic group, ADSC treatment group, and CpG-ODN treatment group, with 10 mice in each group. A mouse model of food allergy was established by intraperitoneal injection and intragastric administration of ovalbumin (OVA) for sensitization and challenge. The mice in the control group were treated with normal saline at the same dose; the mice in the ADSC treatment group were given intraperitoneal injection of ADSC (1×106 cells for each mouse) before and after OVA challenge, and those in the CpG-ODN treatment group were given intraperitoneal injection of non-methylated CpG-ODN solution (40 μg for each mouse) at 1 hour before challenge by gavage. The allergic symptom scores were determined for each group after model establishment. ELISA was used to measure the serum level of OVA-IgE. Flow cytometry was used to measure the percentage of peripheral blood CD4+CD25+ Treg cells. Hematoxylin and eosin staining was used for the pathological analysis of the jejunum.

RESULTS

The allergic group had significantly higher allergic symptom scores and serum level of OVA-IgE than the control group (P<0.05). There were no significant differences in the allergic symptom score and the serum level of OVA-IgE between the ADSC treatment group and the CpG-ODN treatment group (P>0.05), but these two groups had significantly lower allergic symptom scores and serum level of OVA-IgE than the allergic group and significantly higher allergic symptom scores and serum level of OVA-IgE than the control group (P<0.01). The allergic group had a significantly lower percentage of peripheral blood CD4+CD25+ Treg cells than the control group (P<0.05). The ADSC treatment group and the CpG-ODN treatment group had a significantly higher percentage of peripheral blood CD4+CD25+ Treg cells than the allergic group (P<0.05); there were no significant differences between these two groups or between them and the control group (P>0.05). Pathological results showed structural damage and edema in the jejunal villi, a large number of eosinophils, and lymphocyte infiltration in the allergic group, while the ADSC treatment group and the CpG-ODN treatment group had less structural damage and edema in the jejunal villi, a lower number of eosinophils, and less lymphocyte infiltration.

CONCLUSIONS

ADSC and non-methylated CpG-ODN have a certain effect in the treatment of food allergy and can increase the percentage of peripheral blood CD4+CD25+ Treg cells and reduce the level of OVA-IgE. They may be associated with the induction of immune tolerance and these two treatment have comparable effects. Detailed mechanisms of action still need further investigation.

Immunological effects of vaccines combined with granulocyte colony-stimulating factor on a murine WEHI-3 leukemia model

Granulocyte colony-stimulating factor (G-CSF) mobilizes regulatory T cells (Tregs) from bone marrow into the peripheral blood, by reducing the expression of stromal cell-derived factor-1α (SDF-1α). However, G-CSF has rarely been studied in acute myeloid leukemia (AML) immunotherapy. The present study performed a Transwell migration assay in vitro to determine the contribution of SDF-1α to the migration of leukemia cells, and the effects of G-CSF were evaluated. The effects of G-CSF on SDF-1α and Tregs in the AML microenvironment were examined, by employing a WEHI-3-grafted BALB/c mouse AML model (AML-M4). It is evident that G-CSF reversed immunosuppression of the AML microenvironment by reducing SDF-1α in bone marrow and elevating Tregs in the peripheral blood in in vivo studies. Furthermore, AML mice treated with vaccines combined with G-CSF achieved a longer survival time than those treated with vaccines without G-CSF, showing the efficiency of the regimen. The present study demonstrates the effects of G-CSF on the mobilization of leukemia cells and Tregs into the peripheral blood. In addition, immunotherapy with G-CSF priming represents a promising therapeutic strategy of targeting the immunosuppression.

Regular exercise during haemodialysis promotes an anti-inflammatory leucocyte profile

Background

Cardiovascular disease is the most common cause of mortality in haemodialysis (HD) patients and is highly predicted by markers of chronic inflammation. Regular exercise may have beneficial anti-inflammatory effects, but this is unclear in HD patients. This study assessed the effect of regular intradialytic exercise on soluble inflammatory factors and inflammatory leucocyte phenotypes.

Methods

Twenty-two HD patients from a centre where intradialytic cycling was offered thrice weekly and 16 HD patients receiving usual care volunteered. Exercising patients aimed to cycle for 30 min at rating of perceived exertion of ‘somewhat hard’. Baseline characteristics were compared with 16 healthy age-matched individuals. Physical function, soluble inflammatory markers and leucocyte phenotypes were assessed again after 6 months of regular exercise.

Results

Patients were less active than their healthy counterparts and had significant elevations in measures of inflammation [interleukin-6 (IL-6), C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), intermediate and non-classical monocytes; all P < 0.001]. Six months of regular intradialytic exercise improved physical function (sit-to-stand 60). After 6 months, the proportion of intermediate monocytes in the exercising patients reduced compared with non-exercisers (7.58 ± 1.68% to 6.38 ± 1.81% versus 6.86 ± 1.45% to 7.88 ± 1.66%; P < 0.01). Numbers (but not proportion) of regulatory T cells decreased in the non-exercising patients only (P < 0.05). Training had no significant effect on circulating IL-6, CRP or TNF-α concentrations.

Conclusions

These findings suggest that regular intradialytic exercise is associated with an anti-inflammatory effect at a circulating cellular level but not in circulating cytokines. This may be protective against the increased risk of cardiovascular disease and mortality that is associated with chronic inflammation and elevated numbers of intermediate monocytes.

The influence of hydro-ethanolic extract of Portulaca oleracea L. on Th1/Th2 balance in isolated human lymphocytes

ETHNOPHARMACOLOGICAL RELEVANCE

The anti-inflammatory and anti-oxidants activity of Portulaca oleracea L. (P. oleracea) were mentioned in traditional texts. In previous studies, different anti-inflammatory and anti-oxidant effects of P. oleracea were demonstrated. However, the mechanism of action and immunomodulatory property of this plant are greatly unknown. In the present study, the effect of the extract of this plant on IL-4, IL10, IFN-γ and T helper (h)1/Th2 balance in non-stimulated and stimulated human lymphocytes was examined.

MATERIALS AND METHODS

The effect of three concentrations (160, 40 and 10µg/ml) of P. oleracea or dexamethasone were evaluated on percentage of cell proliferation and nitric oxide (NO) production as well as secretion of cytokines (IL-4, IL10 and IFN-γ) in PHA-stimulated and non-stimulated lymphocytes, and compared to control and dexamethasone as positive control (n=15 for each group).

RESULTS

In stimulated cells, dexamethasone significantly inhibited the percentage of cell proliferation, NO production, and secretion of cytokines in comparison to control group (P<0.001 for all cases). The percentage of cell proliferation, NO production, and secretion of cytokines were significantly decreased while Th1/Th2 (IFN-γ/IL-4) and Treg/Th2 (IL-10/IL-4) balances significantly enhanced in treated groups with all three concentrations of extract compared to control group (P<0.001 for all cases). The effect of all concentrations of the extract on cell proliferation, NO production and secretion of cytokines as well as Treg/Th2 balance were significantly lower than dexamethasone (P<0.001 for all cases), but Th1/Th2 ratio obtained in the presence of only low extract concentration was lower than dexamethasone (P<0.01).

CONCLUSION

Different concentrations of extract promoted Th1/Th2 and Treg/Th2 balances which may suggest the therapeutic value of the plant in inflammatory disease associated with decreased Th1/Th2 balance such as asthma or cancers.

Oral administration of a non-absorbable plant cell-expressed recombinant anti-TNF fusion protein induces immunomodulatory effects and alleviates nonalcoholic steatohepatitis

AIM

To evaluate the immunomodulatory effect of oral administration of PRX-106 in the high-fat diet model.

METHODS

For 22 wk, C57BL/6 HFD-fed mice received daily oral treatments with BY-2 cells expressing recombinant anti-tumor necrosis factor alpha fusion protein (PRX-106). Mice were followed for serum liver enzyme and triglyceride levels, liver histology and intrahepatic and systemic FACS.

RESULTS

The orally administered non-absorbable PRX-106 was biologically active. Altered distribution of CD4+CD25+FoxP3+ between the liver and spleen and an increase in the intrasplenic-to-intrahepatic CD4+CD25+FoxP3+ ratio and a decrease in the intrasplenic-to-intrahepatic CD8+CD25+FoxP3+ ratio were observed. An increase in intrahepatic NKT cells and a decrease in the intrasplenic-to-intrahepatic NKT ratio were noted. Assessment of the CD4-to-CD8 ratios showed sequestration of CD8+ lymphocytes in the liver. These effects were associated with a decrease in serum triglyceride levels, decrease in the aspartate aminotransferase levels, serum glucose levels, and HOMA-IR score. A decrease in hepatic triglycerides content was observed in the high dose-treated mice.

CONCLUSION

Orally administered PRX-106 shows biological activity and exerts an immunomodulatory effect, alleviating liver damage. The data suggest that PRX-106 may provide an oral immunotherapy for nonalcoholic steatohepatitis.

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.

GWAS analysis implicates NF-κB-mediated induction of inflammatory T cells in multiple sclerosis

To identify genes and biologically relevant pathways associated with risk to develop multiple sclerosis (MS), the Genome-Wide Association Studies noise reduction method (GWAS-NR) was applied to MS genotyping data. Regions of association were defined based on the significance of linkage disequilibrium blocks. Candidate genes were cross-referenced based on a review of current literature, with attention to molecular function and directly interacting proteins. Supplementary annotations and pathway enrichment scores were generated using The Database for Annotation, Visualization and Integrated Discovery. The candidate set of 220 MS susceptibility genes prioritized by GWAS-NR was highly enriched with genes involved in biological pathways related to positive regulation of cell, lymphocyte and leukocyte activation (P=6.1E-15, 1.2E-14 and 5.0E-14, respectively). Novel gene candidates include key regulators of NF-κB signaling and CD4+ T helper type 1 (Th1) and T helper type 17 (Th17) lineages. A large subset of MS candidate genes prioritized by GWAS-NR were found to interact in a tractable pathway regulating the NF-κB-mediated induction and infiltration of pro-inflammatory Th1/Th17 T-cell lineages, and maintenance of immune tolerance by T-regulatory cells. This mechanism provides a biological context that potentially links clinical observations in MS to the underlying genetic landscape that may confer susceptibility.

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.

Oral immune therapy: targeting the systemic immune system via the gut immune system for the treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are associated with an altered systemic immune response leading to inflammation-mediated damage to the gut and other organs. Oral immune therapy is a method of systemic immune modulation via alteration of the gut immune system. It uses the inherit ability of the innate system of the gut to redirect the systemic innate and adaptive immune responses. Oral immune therapy is an attractive clinical approach to treat autoimmune and inflammatory disorders. It can induce immune modulation without immune suppression, has minimal toxicity and is easily administered. Targeting the systemic immune system via the gut immune system can serve as an attractive novel therapeutic method for IBD. This review summarizes the current data and discusses several examples of oral immune therapeutic methods for using the gut immune system to generate signals to reset systemic immunity as a treatment for IBD.

CD4(+)HLA-G(+) regulatory T cells: Molecular signature and pathophysiological relevance

The regulation of potentially harmful immune responses by regulatory T (Treg) cells is essential for maintaining peripheral immune tolerance and homeostasis. Especially CD4(+) Treg cells have been regarded as pivotal regulators of autoreactive and inflammatory responses as well as inducers of immune tolerance by using a variety of immune suppressive mechanisms. Besides the well-known classical CD4(+)CD25(+)FoxP3(+) Treg cells, CD4(+) T cells expressing the immune tolerizing molecule human leukocyte antigen G (HLA-G) have been recently described as another potent thymus-derived Treg (tTreg) cell subset. Albeit both tTreg subsets share common molecular characteristics, the mechanisms of their immunosuppressive function differ fundamentally. Dysfunction and numerical abnormalities of classical CD4(+) tTreg cells have been implicated in the pathogenesis of several immune-mediated diseases such as multiple sclerosis (MS). Clearly, a deeper understanding of the various CD4(+) tTreg subsets and also the underlying mechanisms of impaired immune tolerance in these disorders are essential for the development of potential therapeutic strategies. This review focuses on the current knowledge on defining features and functioning of HLA-G(+)CD4(+) tTreg cells as well as their emerging role in various pathologies with special emphasis on the pathogenesis of MS. Furthermore, future research possibilities together with potential therapeutic applications are discussed.

The role of Th17 and Treg responses in the pathogenesis of RSV infection

The respiratory syncytial virus (RSV) represents the leading cause of viral bronchiolitis and pneumonia in children worldwide and is associated with high morbidity, hospitalization rate, and significant mortality rates. The immune response elicited by RSV is one of the main factors contributing to the pathogenesis of the disease. Two subsets of the cellular immune response, the T helper 17 cell (Th17) and the regulatory T-cell (Treg), and more particularly the balance between these two subsets, might play a significant role in the pathogenesis of the RSV infection. The developmental pathways of Th17 and Treg cells are closely and reciprocally interconnected and plasticity has been demonstrated from Treg toward Th17. During an RSV infection, the functions of both subsets are opposed to one another regarding viral clearance and clinical severity. Th17 and Treg cells offer a promising new view on the pathogenesis of an RSV infection and deserve further exploration.

Restoration of Foxp3+ Regulatory T-cell Subsets and Foxp3- Type 1 Regulatory-like T Cells in Inflammatory Bowel Diseases During Anti-tumor Necrosis Factor Therapy

BACKGROUND

A defect in regulatory T cells (Tregs) may be involved in the pathogenesis of inflammatory bowel diseases (IBD). Several subsets of human Foxp3+ Tregs (activated and resting Tregs) have now been identified, as well as an IL-10 and IFN-γ double producing Foxp3 type 1 regulatory-like T cell (Tr1L). We have quantified these Tregs in patients with active IBD and during therapy with infliximab (IFX).

METHODS

Blood samples were obtained from healthy controls (n = 54) and patients with active IBD, either before (n = 62) or during IFX therapy (n = 75). Tregs were identified by immunofluorescent staining and flow cytometry analysis. Resting and activated Foxp3+ Tregs can be differentiated from Foxp3+ effector T cells (Foxp3+ Teff) by the expression of CD45RA. Tr1L are identified as CD4+CD45RA-CD25-CD127-Foxp3- T cells.

RESULTS

A numerical deficiency of circulating resting Tregs, activated Treg cells, and Tr1L was documented in patients with active IBD. Baseline levels of these Treg subsets predicted clinical responses to IFX. We documented an upregulation of all 3 subsets during IFX therapy. Moreover, after therapy, significant differences in Treg subsets were seen between responders and nonresponders to IFX. Restoration of Tregs correlated with the clinical and biological response to IFX therapy. Trough serum levels of IFX positively correlated with the proportion of activated Treg cells and Tr1L during therapy.

CONCLUSIONS

IFX therapy, when successful, results in upmodulation of the different types of Treg cells in the blood of patients with IBD. This effect might be relevant for understanding the mechanism of action of anti-TNF agents.

Withdrawal of immunosuppression in liver transplantation and the mechanism of tolerance

BACKGROUND

Immunosuppression reagents have side effects and cause considerable long-term morbidity and mortality in patients after liver transplantation. Sufficient evidences showed that minimization or withdrawal of immunosuppression reagents does not deteriorate the recipient's immune response and physiological function and therefore, is feasible in some recipients of liver transplantation. However, the mechanisms are not clear. The present review was to update the current status of immunosuppression in liver transplantation and the mechanism of minimization or withdrawal of immunosuppression in liver recipients.

DATA SOURCES

We searched articles in English on minimization or withdrawal of immunosuppression in liver transplantation in PubMed. We focused on the basic mechanisms of immune tolerance in liver transplantation. Studies on immunosuppression minimization or withdrawal protocols and biomarker in tolerant recipients were also analyzed.

RESULTS

Minimization or withdrawal of immunosuppression can be achieved by the induction of immune tolerance, which may not be permanent and can be affected by various factors. However, accurately evaluating immune status post-transplant is a prerequisite to achieve individualized immunosuppression. Numerous mechanisms for immune tolerance have been found, including immunophenotypic shift of memory CD8+ T cells and CD4+ T cell subsets. Activation of the inflammasome through apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) in dendritic cells is associated with rejection after liver transplantation.

CONCLUSIONS

Minimization or withdrawal of immunosuppression can be achieved by the induction of immune tolerance via different mechanisms. This process could be affected by immunophenotypic shift of memory CD8+ T cells and CD4+ T cell subsets, which may be correlated with activation of the inflammasome through ASC in dendritic cells.

Circulating biomarkers of hepatocellular carcinoma response after locoregional treatments: New insights

Hepatocellular cancer is the 5(th) most common cancer in the world and the third cause of death by malignant disease. Locoregional therapies are the most usual treatment of choice for patients with early or intermediate stage of disease. The main diagnostic tools for the detection of recurrence are the radiological techniques such as 4-phase computed tomography or dynamic contrast enhanced magnetic resonance imaging. However, in order to achieve best evaluation of treatment outcome and recurrence rates, there is a great need for the identification of specific and easily measured circulating biomarkers. The aim of this review is to analyze the existing data considering the prognostic significance of changes of serum diagnostic markers such as alpha-fetoprotein, des-gamma-carboxy prothrombin, alpha-fetoprotein-L3, angiogenetic factors (vascular endothelial growth factor, hypoxia inducible factor-1a) and immune parameters before and after radiofrequency ablation or transarterial chemoembolization.

Emerging roles of regulatory T cells in tumour progression and metastasis

The metastasis of cancer is a complex and life-threatening process that is only partially understood. Immune suppressive cells are recognized as important contributors to tumour progression and may also promote the development and growth of tumour metastases. Specifically, regulatory T cells (Tregs) have been found to promote primary tumour progression, and emerging pre-clinical data suggests that Tregs may promote metastasis and metastatic tumour growth. While the precise role that Tregs play in metastatic progression is understudied, recent findings have indicated that by suppressing innate and adaptive anti-tumour immunity, Tregs may shield tumour cells from immune detection, and thereby allow tumour cells to survive, proliferate and acquire characteristics that facilitate dissemination. This review will highlight our current understanding of Tregs in metastasis, including an overview of pre-clinical findings and discussion of clinical data regarding Tregs and therapeutic outcome. Evolving strategies to directly ablate Tregs or to inhibit their function will also be discussed. Improving our understanding of how Tregs may influence tumour metastasis may lead to novel treatments for metastatic cancer.