The subpopulation of CD4+CD25+ splenocytes that delays adoptive transfer of diabetes expresses L-selectin and high levels of CCR7

Local administration of myeloid-derived suppressor cells prevents progression of immune-mediated dry eye disease

Myeloid derived suppressor cells (MDSCs) are a heterogenous population of immature hematopoietic precursors with known immunoregulatory functions. The immunosuppressive role of MDSCs has been highlighted in several inflammatory ophthalmic disorders; however, their therapeutic application in suppressing the immune-mediated changes in dry eye disease (DED) has not been studied. We observed significant reduction in antigen presenting cell (APC) frequencies and their maturation in the presence of MDSCs. Moreover, co-culturing MDSCs with T helper 17 cells (Th17) resulted in reduced Th17 frequencies and their IL-17 expression. On the contrary, MDSCs maintained regulatory T cell frequencies and enhanced their function in-vitro. Furthermore, we delineated the role of interleukin-10 (IL-10) secreted by MDSCs in their immunoregulatory functions. We confirmed these results by flow cytometry analysis and observed that treatment with MDSCs in DED mice effectively suppressed the maturation of APCs, pathogenic Th17 response, and maintained Treg function and significantly ameliorated the disease. The results in this study highlight the potential therapeutic application of MDSCs in treating refractory DED.

Multiply restimulated human cord blood-derived Tregs maintain stabilized phenotype and suppressive function and predict their therapeutic effects on autoimmune diabetes

BACKGROUND

Regulatory T cells (Tregs) are involved in the maintenance of immune homeostasis and immune regulation. Clinical trials on the adoptive transfer of Tregs have been ongoing for > 10 years. However, many unresolved issues remain in the production of readymade Treg products and selection of patients. Hence, this study aimed to develop a method to expand off-the-shelf Tregs derived from umbilical cord blood (UCB-Tregs) in vitro without changing their phenotype and inhibitory function. In addition, the study intended to design an approach to precisely select patients who are more likely to benefit from the adoptive Treg transfer therapy.

METHODS

UCB-Tregs were isolated and cultured in a medium containing human recombinant IL-2 and rapamycin and then multiply restimulated with human T-activator CD3/CD28 dynabeads. The phenotype and suppressive capacity of Tregs were assessed on days 18 and 42. The relationship between the suppressive function of UCB-Tregs in vitro and clinical indicators was analyzed, and the ability of the in vitro suppressive capacity to predict the in vivo therapeutic effects was evaluated.

RESULTS

UCB-Tregs expanded 123-fold and 5,981-fold at 18 and 42 days, respectively. The suppressive function of UCB-Tregs on the proliferation of immune cells at 42 days was not significantly different compared with that of UCB-Tregs obtained at 18 days. The suppression rate of UCB-Tregs to PBMCs was negatively correlated with the course of diabetes. Moreover, the high-suppression group exhibited a better treatment response than the low-suppression group during the 12-month follow-up period.

CONCLUSIONS

Multiply restimulated UCB-Tregs expanded at a large scale without any alterations in their classical phenotypic features and inhibitory functions. The suppressive function of Tregs in vitro was negatively correlated with the disease duration. The present study revealed the possibility of predicting the in vivo therapeutic effects via the in vitro inhibition assay. Thus, these findings provided a method to obtain off-the-shelf Treg products and facilitated the selection of patients who are likely to respond to the treatment, thereby moving toward the goal of precision treatment.

CD4+CD25+ regulatory T cells ex vivo generated from autologous naïve CD4+ T cells suppress EAE progression

CD4+CD25+ regulatory T cells (Tregs) play an important role in maintaining immune homeostasis in multiple sclerosis (MS). Hence, we aimed to explore the therapeutic efficacy and safety of adoptive cell therapy (ACT) utilizing induced antigen-specific Tregs in an animal model of MS, that is, in an experimental autoimmune encephalomyelitis (EAE) model. B cells from EAE model that were activated with soluble CD40L were used as antigen-presenting cells (APCs) to induce the differentiation of antigen-specific Tregs from naïve CD4 precursors, and then, a stepwise isolation of CD4+CD25highCD127low Tregs was performed using a flow sorter. All EAE mice were divided into Treg-treated group (2 × 104 cells in 0.2 mL per mouse, n = 14) and sham-treated group (0.2 mL normal saline (NS), n = 20), which were observed daily for clinical assessment, and for abnormal appearance for 6 weeks. Afterward, histological analysis, immunofluorescence and real-time PCR were performed. Compared to sham-treated mice, Treg-treated mice exhibited a significant decrease in disease severity scores and reduced inflammatory infiltration and demyelination in the spinal cord. Additionally, Tregs-treated mice demonstrated higher CCN3 protein and mRNA levels than sham-treated mice. The results of this preclinical study further support the therapeutic potential of this ACT approach in the treatment of MS.

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

Human CD4+CD25+CD127lowFOXP3+ regulatory T lymphocytes and CD4+CD25-FOXP3- conventional T lymphocytes: a differential transcriptome profile

CD4+CD25+ FOXP3+ regulatory T cells (Tregs) represent a subpopulation of CD4+ T cells central for the suppression of physiological and pathological immune reactions. Although distinct cell surface antigens are expressed in regulatory T cells, those components are also present on the surface of activated CD4+CD25- FOXP3-T cells, thus making the discrimination between Tregs and conventional CD4+ T difficult and isolation of Tregs complex. Yet, the molecular components driving Tregs' function are still not fully characterized. Aiming at unraveling molecular components specifically marking Tregs, and upon using quantitative real-time PCR (qRT-PCR) followed by bioinformatics analysis, we identified, in this study, differential transcriptional profiles, in peripheral blood CD4 + CD25 + CD127low FOXP3+ Tregs versus CD4 + CD25-FOXP3- conventional T cells, for set of genes with distinct immunological roles. In conclusion, this study identifies some novel genes that appeared to be differentially transcribed in CD4+ Tregs versus conventional T cells. The identified genes could serve as novel molecular targets relevant to Tregs' function and isolation.

Engineered Treg cells as putative therapeutics against inflammatory diseases and beyond

Regulatory T (Treg) cells ensure tolerance against self-antigens, limit excessive inflammation, and support tissue repair processes. Therefore, Treg cells are currently attractive candidates for the treatment of certain inflammatory diseases, autoimmune disorders, or transplant rejection. Early clinical trials have proved the safety and efficacy of certain Treg cell therapies in inflammatory diseases. We summarize recent advances in engineering Treg cells, including the concept of biosensors for inflammation. We assess Treg cell engineering possibilities for novel functional units, including Treg cell modifications influencing stability, migration, and tissue adaptation. Finally, we outline perspectives of engineered Treg cells going beyond inflammatory diseases by using custom-designed receptors and read-out systems, aiming to use Treg cells as in vivo diagnostic tools and drug delivery vehicles.

CXCL11-armed oncolytic adenoviruses enhance CAR-T cell therapeutic efficacy and reprogram tumor microenvironment in glioblastoma

Glioblastoma (GBM) is the most aggressive primary malignant brain cancer and urgently requires effective treatments. Chimeric antigen receptor T (CAR-T) cell therapy offers a potential treatment method, but it is often hindered by poor infiltration of CAR-T cells in tumors and highly immunosuppressive tumor microenvironment (TME). Here, we armed an oncolytic adenovirus (oAds) with a chemokine CXCL11 to increase the infiltration of CAR-T cells and reprogram the immunosuppressive TME, thus improving its therapeutic efficacy. In both immunodeficient and immunocompetent orthotopic GBM mice models, we showed that B7H3-targeted CAR-T cells alone failed to inhibit GBM growth but, when combined with the intratumoral administration of CXCL11-armed oAd, it achieved a durable antitumor response. Besides, oAd-CXCL11 had a potent antitumor effect and reprogramed the immunosuppressive TME in GL261 GBM models, in which increased infiltration of CD8+ T lymphocytes, natural killer (NK) cells, and M1-polarized macrophages, while decreased proportions of myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs) and M2-polarized macrophages were observed. Furthermore, the antitumor effect of the oAd-CXCL11 was CD8+ T cell dependent. Our findings thus revealed that CXCL11-armed oAd can improve immune-virotherapy and can be a promising adjuvant of CAR-T therapy for GBM.

CD3e-immunotoxin spares CD62Llo Tregs and reshapes organ-specific T-cell composition by preferentially depleting CD3ehi T cells

CD3-epsilon(CD3e) immunotoxins (IT), a promising precision reagent for various clinical conditions requiring effective depletion of T cells, often shows limited treatment efficacy for largely unknown reasons. Tissue-resident T cells that persist in peripheral tissues have been shown to play pivotal roles in local and systemic immunity, as well as transplant rejection, autoimmunity and cancers. The impact of CD3e-IT treatment on these local cells, however, remains poorly understood. Here, using a new murine testing model, we demonstrate a substantial enrichment of tissue-resident Foxp3+ Tregs following CD3e-IT treatment. Differential surface expression of CD3e among T-cell subsets appears to be a main driver of Treg enrichment in CD3e-IT treatment. The surviving Tregs in CD3e-IT-treated mice were mostly the CD3e^dimCD62L^lo effector phenotype, but the levels of this phenotype markedly varied among different lymphoid and nonlymphoid organs. We also found notable variations in surface CD3e levels among tissue-resident T cells of different organs, and these variations drive CD3e-IT to uniquely reshape T-cell compositions in local organs. The functions of organs and anatomic locations (lymph nodes) also affected the efficacy of CD3e-IT. The multi-organ pharmacodynamics of CD3e-IT and potential treatment resistance mechanisms identified in this study may generate new opportunities to further improve this promising treatment.

CD28 Superagonist D665-mediated activation of mouse regulatory T cells maintains their phenotype without loss of suppressive quality

Regulatory T cells (Tregs) maintain immune homeostasis by regulating the activation of other immune cells. Preclinical studies show that the infusion of Tregs can promote immunological tolerance to allografts and prevent or cure multiple autoimmune diseases. However, Treg therapy is limited by high numbers of cells required to induce tolerance. In this study, we aimed at improving the in vitro expansion of sort purified mouse Tregs using the CD28 Superagonist (CD28-SA) D665 and comparing it to the conventional expansion using anti-CD3/anti-CD28 Dynabeads®. CD28-SA-stimulated Tregs expanded more than Dynabead®-stimulated Tregs while maintaining their phenotype by expressing the same level of CD4, CD25 and Foxp3. CD28-SA-expanded Tregs produced comparable amounts of IL-10 and TGFβ while showing a slightly superior suppressive capacity compared to Dynabead®-stimulated Tregs. Thus, stimulating murine Tregs with the CD28-SA is a promising alternative since it maintains their suppressive capacity without altering their phenotype and yields a higher fold expansion within 14 days.

Improving the Efficacy of Regulatory T Cell Therapy

Autoimmunity is caused by an unbalanced immune system, giving rise to a variety of organ-specific to system disorders. Patients with autoimmune diseases are commonly treated with broad-acting immunomodulatory drugs, with the risk of severe side effects. Regulatory T cells (Tregs) have the inherent capacity to induce peripheral tolerance as well as tissue regeneration and are therefore a prime candidate to use as cell therapy in patients with autoimmune disorders. (Pre)clinical studies using Treg therapy have already established safety and feasibility, and some show clinical benefits. However, Tregs are known to be functionally impaired in autoimmune diseases. Therefore, ex vivo manipulation to boost and stably maintain their suppressive function is necessary when considering autologous transplantation. Similar to autoimmunity, severe coronavirus disease 2019 (COVID-19) is characterized by an exaggerated immune reaction and altered Treg responses. In light of this, Treg-based therapies are currently under investigation to treat severe COVID-19. This review provides a detailed overview of the current progress and clinical challenges of Treg therapy for autoimmune and hyperinflammatory diseases, with a focus on recent successes of ex vivo Treg manipulation.

Age-Related Changes in Thymic Central Tolerance

Thymic epithelial cells (TECs) and hematopoietic antigen presenting cells (HAPCs) in the thymus microenvironment provide essential signals to self-reactive thymocytes that induce either negative selection or generation of regulatory T cells (Treg), both of which are required to establish and maintain central tolerance throughout life. HAPCs and TECs are comprised of multiple subsets that play distinct and overlapping roles in central tolerance. Changes that occur in the composition and function of TEC and HAPC subsets across the lifespan have potential consequences for central tolerance. In keeping with this possibility, there are age-associated changes in the cellular composition and function of T cells and Treg. This review summarizes changes in T cell and Treg function during the perinatal to adult transition and in the course of normal aging, and relates these changes to age-associated alterations in thymic HAPC and TEC subsets.

Identifying potential biomarkers of nonalcoholic fatty liver disease via genome-wide analysis of copy number variation

BACKGROUND

The prevalence of Non-alcoholic fatty liver disease (NAFLD) is increasing and emerging as a global health burden. In addition to environmental factors, numerous studies have shown that genetic factors play an important role in the development of NAFLD. Copy number variation (CNV) as a genetic variation plays an important role in the evaluation of disease susceptibility and genetic differences. The aim of the present study was to assess the contribution of CNV to the evaluation of NAFLD in a Chinese population.

METHODS

Genome-wide analysis of CNV was performed using high-density comparative genomic hybridisation microarrays (ACGH). To validate the CNV regions, TaqMan real-time quantitative PCR (qPCR) was utilized.

RESULTS

A total of 441 CNVs were identified, including 381 autosomal CNVs and 60 sex chromosome CNVs. By merging overlapping CNVs, a genomic CNV map of NAFLD patients was constructed. A total of 338 autosomal CNVRs were identified, including 275 CNVRs with consistent trends (197 losses and 78 gains) and 63 CNVRs with inconsistent trends. The length of the 338 CNVRs ranged from 5.7 kb to 2.23 Mb, with an average size of 117.44 kb. These CNVRs spanned 39.70 Mb of the genome and accounted for ~ 1.32% of the genome sequence. Through Gene Ontology and genetic pathway analysis, we found evidence that CNVs involving nine genes may be associated with the pathogenesis of NAFLD progression. One of the genes (NLRP4 gene) was selected and verified by quantitative PCR (qPCR) method with large sample size. We found the copy number deletion of NLRP4 was related to the risk of NAFLD.

CONCLUSIONS

This study indicate the copy number variation is associated with NAFLD. The copy number deletion of NLRP4 was related to the risk of NAFLD. These results could prove valuable for predicting patients at risk of developing NAFLD.

Pigment Epithelium-Derived Factor Enhances the Suppressive Phenotype of Regulatory T Cells in a Murine Model of Dry Eye Disease

Pigment epithelium-derived factor (PEDF) is a widely expressed 50-kDa glycoprotein belonging to the serine protease inhibitor family, with well-established anti-inflammatory functions. Recently, we demonstrated the immunoregulatory role played by PEDF in dry eye disease (DED) by suppressing the maturation of antigen-presenting cells at the ocular surface following exposure to the desiccating stress. In this study, we evaluated the effect of PEDF on the immunosuppressive characteristics of regulatory T cells (Tregs), which are functionally impaired in DED. In the presence of PEDF, the in vitro cultures prevented proinflammatory cytokine (associated with type 17 helper T cells)-induced loss of frequency and suppressive phenotype of Tregs derived from normal mice. Similarly, PEDF maintained the in vitro frequency and enhanced the suppressive phenotype of Tregs derived from DED mice. On systemically treating DED mice with PEDF, moderately higher frequencies and significantly enhanced suppressive function of Tregs were observed in the draining lymphoid tissues, leading to the efficacious amelioration of the disease. Our results demonstrate that PEDF promotes the suppressive capability of Tregs and attenuates their type 17 helper T-cell-mediated dysfunction in DED, thereby playing a role in the suppression of DED.

Case Report: IL-21 and Bcl-6 Regulate the Proliferation and Secretion of Tfh and Tfr Cells in the Intestinal Germinal Center of Patients With Inflammatory Bowel Disease

Objective: This study aimed to investigate the effect of interleukin (IL)-21 and B cell lymphoma protein-6 on germinal center follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells and its relationship with the clinical features of inflammatory bowel disease (IBD).

Methods: The expression of peripheral blood cytokines IL-21 and Bcl-6 mRNA was detected by reverse transcription–polymerase chain reaction. The distribution characteristics of Tfh and Tfr cells were detected using the triple immunofluorescence staining analysis.

Results: The expression of IL-21 and Bcl-6 mRNA was upregulated in the ulcerative colitis (UC) and Crohn disease (CD) groups compared with that in the control group. Triple immunofluorescence staining showed that the number of Tfh cells in the intestinal germinal center obviously increased in the UC and CD groups compared with that in the control group, whereas the number of Tfr cells reduced.

Conclusion: This study suggested that the Tfr and Tfh cells might be involved in the regulation of IBD. Bcl-6 and IL-21 can regulate the Tfh/Tfr ratio in the intestinal germinal center, promoting the occurrence and development of IBD.

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

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

RelB regulates the homeostatic proliferation but not the function of Tregs

Background

RelB, a member of the NF-κB family, plays a critical role in the development of T cells. However, the role of RelB in Foxp3⁺ regulatory T cells (Tregs) remains controversial.

Results

Using a bone marrow chimeric mouse model, we demonstrated that the expansion of Foxp3⁺ Tregs in vivo could be mediated by extrinsic mechanisms. RelB plays an important role in inhibiting the homeostatic proliferation of Tregs, but not their survival. Even with the heightened expansion, RelB^−/− Treg cells displayed normal suppressive function in vitro. Among the expanded populations of Treg cells, most were nTreg cells; however, the population of iTregs did not increase. Mechanistically, RelB seems to regulate Treg proliferation independently of the signal transducer and activator of transcription 5 (STAT5) pathway.

Conclusions

These data suggest that RelB regulates Treg proliferation independently of the STAT5 pathway, but does not alter the function of Tregs. Further studies are warranted to uncover such mechanisms.

Guidance factors orchestrating regulatory T cell positioning in tissues during development, homeostasis, and response

Over their lifetime, regulatory T cells (Treg) recalibrate their expression of trafficking receptors multiple times as they progress through development, respond to immune challenges, or adapt to the requirements of functioning in various non-lymphoid tissue environments. These trafficking receptors, which include chemokine receptors and other G-protein coupled receptors, integrins, as well as selectins and their ligands, enable Treg not only to enter appropriate tissues from the bloodstream via post-capillary venules, but also to navigate these tissues to locally execute their immune-regulatory functions, and finally to seek out the right antigen-presenting cells and interact with these, in part in order to receive the signals that sustain their survival, proliferation, and functional activity, in part in order to execute their immuno-regulatory function by altering antigen presenting cell function. Here, we will review our current knowledge of when and in what ways Treg alter their trafficking properties. We will focus on the chemokine system and try to identify specialized, non-redundant roles of individual receptors as well as similarities and differences to the conventional T cell compartment.

Role of NF-kappaB2-p100 in regulatory T cell homeostasis and activation

The immunological roles of the nuclear factor-kappaB (NF-κB) pathway are mediated via the canonical components in immune responses and via non-canonical components in immune organogenesis and homeostasis, although the two components are capable of crosstalk. Regulatory CD4 T cells (Tregs) are homeostatically functional and represent an interesting potential meeting point of these two NF-κB components. We show that mice deficient in the non-canonical NF-κB component gene Nfkb2 (p100) had normal thymic development and suppressive function of Tregs. However, they had enhanced frequencies of peripheral 'effector-phenotype' Tregs (eTregs). In bi-parental chimeras of wild-type (WT) and Nfkb2-/- mice, the Nfkb2-/- genotype was over-represented in Tregs, with a further increase in the relative prominence of eTregs. Consistent with distinct properties of eTregs, the Nfkb2-/- genotype was more prominent in Tregs in extra-lymphoid tissues such as liver in the bi-parental chimeras. The Nfkb2-/- Tregs also displayed greater survival, activation and proliferation in vivo. These Nfkb2-/- Tregs showed higher nuclear NF-κB activity mainly comprising of RelB-containing dimers, in contrast to the prominence of cRel- and RelA-containing dimers in WT Tregs. Since p100 is an inhibitor of RelB activation as well as a participant as cleaved p52 in RelB nuclear activity, we tested bi-parental chimeras of WT and Relb-/- mice, and found normal frequencies of Relb-/- Tregs and eTregs in these chimeric mice. Our findings confirm and extend recent data, and indicate that p100 normally restrains RelB-mediated Treg activation, and in the absence of p100, p50-RelB dimers can contribute to Treg activation.

Protease Activated Receptor 4 as a Novel Modulator of Regulatory T Cell Function

Regulatory T cells (Tregs) are a subpopulation of T cells that maintain immunological tolerance. In inflammatory responses the function of Tregs is tightly controlled by several factors including signaling through innate receptors such as Toll like receptors and anaphylatoxin receptors allowing an effective immune response to be generated. Protease-activated receptors (PARs) are another family of innate receptors expressed on multiple cell types and involved in the pathogenesis of autoimmune disorders. Whether proteases are able to directly modulate Treg function is unknown. Here, we show using two complimentary approaches that signaling through PAR-4 influences the expression of CD25, CD62L, and CD73, the suppressive capacity, and the stability of Tregs, via phosphorylation of FoxO1 and negative regulation of PTEN and FoxP3. Taken together, our results demonstrate an important role of PAR4 in tuning the function of Tregs and open the possibility of targeting PAR4 to modulate immune responses.

HLA-Class II Artificial Antigen Presenting Cells in CD4+ T Cell-Based Immunotherapy

CD4+ T cells differentiate into various T helper subsets characterized by distinct cytokine secreting profiles that confer them effector functions adapted to a variety of infectious or endogenous threats. Regulatory CD4+ T cells are another specialized subset that plays a fundamental role in the maintenance of immune tolerance to self-antigens. Manipulating effector or regulatory CD4+ T cells responses is a promising immunotherapy strategy for, respectively, chronical viral infections and cancer, or severe autoimmune diseases and transplantation. Adoptive cell therapy (ACT) is an emerging approach that necessitates defining robust and efficient methods for the in vitro expansion of antigen-specific T cells then infused into patients. To address this challenge, artificial antigen presenting cells (AAPCs) have been developed. They constitute a reliable and easily usable platform to stimulate and amplify antigen-specific CD4+ T cells. Here, we review the recent advances in understanding the functions of CD4+ T cells in immunity and in immune tolerance, and their use for ACT. We also describe the characteristics of different AAPC models and the way to improve their stimulating functions. Finally, we discuss the potential interest of these AAPCs, both as fundamental tools to decipher CD4+ T cell responses and as reagents to generate clinical grade antigen-specific CD4+ T cells for immunotherapy.

Immune and genomic signatures in oral (head and neck) cancer

Head and neck squamous cell carcinoma (HNSCC) is responsible for a large number of deaths each year. Oral cancer is the most frequent subtype of HNSCC. Historically, oral cancer has been associated with an increase in the consumption of tobacco and alcohol products, seen especially in the Asian subcontinent. It has also been associated with infection by the human papilloma virus (HPV), particularly strain HPV16. Treatment usually involves a multidisciplinary approach of surgery combined with chemotherapy and radiation. The advent of immunotherapy has broadened the scope for treatment. A better immune response to the tumour can also elicit the action of other therapeutic approaches. A heightened immune response, on the other hand, can lead to resistant tumour formation through the process of immunoediting. Molecular profiling of the tumour microenvironment (TME) can provide us with better insight into the mechanism and progression of the disease, ultimately opening up new therapeutic options. High-throughput molecular profiling techniques over the past decade have enabled us to appreciate the heterogeneity of the TME. In this review, we will be describing the clinicopathological role of the immune and genomic landscape in oral cancer. This study will update readers on the several immunological and genetic factors that can play an important function as predictive and prognostic biomarkers in various forms of head and neck cancer, with a special emphasis on oral carcinoma.

Human regulatory T cells undergo self-inflicted damage via granzyme pathways upon activation

Tregs hold great promise as a cellular therapy for multiple immunologically mediated diseases, given their ability to control immune responses. The success of such strategies depends on the expansion of healthy, suppressive Tregs ex vivo and in vivo following the transfer. In clinical studies, levels of transferred Tregs decline sharply in the blood within a few days of the transfer. Tregs have a high rate of apoptosis. Here, we describe a new mechanism of Treg self-inflicted damage. We show that granzymes A and -B (GrA and GrB), which are highly upregulated in human Tregs upon stimulation, leak out of cytotoxic granules to induce cleavage of cytoplasmic and nuclear substrates, precipitating apoptosis in target cells. GrA and GrB substrates were protected from cleavage by inhibiting granzyme activity in vitro. Additionally, we show - by using cytometry by time of flight (CYTOF) - an increase in GrB-expressing Tregs in the peripheral blood and renal allografts of transplant recipients undergoing rejection. These GrB-expressing Tregs showed an activated phenotype but were significantly more apoptotic than non-GrB expressing Tregs. This potentially novel finding improves our understanding of Treg survival and suggests that manipulating Gr expression or activity might be useful for designing more effective Treg therapies.

Stimulation of osteoclast migration and bone resorption by C-C chemokine ligands 19 and 21

Osteoclasts are responsible for the bone erosion associated with rheumatoid arthritis (RA). The upregulation of the chemokines CCL19 and CCL21 and their receptor CCR7 has been linked to RA pathogenesis. The purpose of this study was to evaluate the effects of CCL19 and CCL21 on osteoclasts and to reveal their underlying mechanisms. The expression of CCL19, CCL21 and CCR7 was higher in RA patients than in osteoarthritis patients. In differentiating osteoclasts, tumor necrosis factor-α, interleukin-1β and lipopolysaccharide stimulated CCR7 expression. CCL19 and CCL21 promoted osteoclast migration and resorption activity. These effects were dependent on the presence of CCR7 and abolished by the inhibition of the Rho signaling pathway. CCL19 and CCL21 promoted bone resorption by osteoclasts in an in vivo mice calvarial model. These findings demonstrate for the first time that CCL19, CCL21 and CCR7 play important roles in bone destruction by increasing osteoclast migration and resorption activity. This study also suggests that the interaction of CCL19 and CCL21 with CCR7 is an effective strategic focus in developing therapeutics for alleviating inflammatory bone destruction.

The attenuation of renal fibrosis by histone deacetylase inhibitors is associated with the plasticity of FOXP3+IL-17+ T cells

BACKGROUND

The histone deacetylase (HDAC) inhibitor, which has potential effects on epigenetic modifications, had been reported to attenuate renal fibrosis. CD4⁺ forkhead box P3 (FOXP3)⁺ T regulatory (Treg) cells may be converted to inflammation-associated T helper 17 cells (Th17) with tissue fibrosis properties. The association between FOXP3⁺IL-17⁺ T cells and the attenuation of renal fibrosis by the HDAC inhibitor is not clear.

METHODS

This study evaluated the roles of the HDAC inhibitor, Treg cells and their differentiation into Th17 cells, which aggravate chronic inflammation and renal fibrosis in a unilateral ureteral obstruction (UUO) mouse model. The study groups included control and UUO mice that were monitored for 7, 14 or 21 days.

RESULTS

Juxtaglomerular (JG) hyperplasia, angiotensin II type 1 receptor (AT1R) expression and lymphocyte infiltration were observed in renal tissues after UUO but were decreased after trichostatin A (TSA) treatment, a HDAC inhibitor. The number of CD4⁺FOXP3⁺ T cells increased progressively, along with the number of FOXP3⁺interleukin (IL)-17⁺ T cells, after 14 days, and their numbers then progressively decreased with increasing CD4⁺IL-17⁺ T cell numbers, as demonstrated by double immunohistochemistry. Progressive renal fibrosis was associated with the loss of CD4⁺FOXP3⁺IL-17⁺ T cells in splenic single-cell suspensions. FOXP3⁺IL-17⁺ T cells expressed TGF-β1 both in vitro and in vivo, and TGF-β1 expression was significantly knockdown by IL-17 siRNA in vitro. These cells were found to play a role in converting Tregs into IL-17- and TGF-β1-producing cells.

CONCLUSIONS

TSA treatment decreased JG hyperplasia, the percentage of FOXP3⁺IL-17⁺ cells and the degree of fibrosis, suggesting that therapeutic benefits may result from epigenetic modifications.

Chemokines and Their Receptors in Islet Allograft Rejection and as Targets for Tolerance Induction

Graft rejection is a major barrier to successful outcome of transplantation surgery. Islet transplantation introduces insulin secreting tissue into type 1 diabetes mellitus recipients, relieving patients from exogenous insulin injection. However, insulitis of grafted tissue and allograft rejection prevent long-term insulin independence. Leukocyte trafficking is necessary for the launch of successful immune responses to pathogen or allograft. Chemokines, small chemotactic cytokines, direct the migration of leukocytes through their interaction with chemokine receptors found on cell surfaces of immune cells. Unique receptor expression of leukocytes, and the specificity of chemokine secretion during various states of immune response, suggest that the extracellular chemokine milieu specifically homes certain leukocyte subsets. Thus, only those leukocytes required for the current immune task are attracted to the inflammatory site. Chemokine blockade, using antagonists and monoclonal antibodies directed against chemokine receptors, is an emerging and specific immunosuppressive strategy. Importantly, chemokine blockade may potentiate tolerance induction regimens to be used following transplantation surgery, and prevent the need for life-long immunosuppression of islet transplant recipients. Here, the role for chemokine blockade in islet transplant rejection and tolerance is reviewed.

Enrichment of Human CCR6+ Regulatory T Cells with Superior Suppressive Activity in Oral Cancer

Human oral squamous cell carcinoma (OSCC) constitutes an inflammatory microenvironment enriched with chemokines such as CCL20, which promote cancer cell invasion and tumor progression. We found that in OSCC there is a correlation between the expression of CCL20 and FOXP3 mRNA. Therefore, we hypothesized that OSCC may favor the recruitment and retention of regulatory T (Treg) cells that express the CCL20 receptor, CCR6. Interestingly, most (∼60%) peripheral blood Treg cells express CCR6, and CCR6⁺ Treg cells exhibit an activated effector/memory phenotype. In contrast, a significant portion (>30%) of CCR6^- Treg cells were found to be CD45RA⁺ naive Treg cells. Compared to CCR6^- naive or memory Treg cells, CCR6⁺ Treg cells exhibit stronger suppressive activity and display higher FOXP3 expression along with lower methylation at the Treg-specific demethylated region of the FOXP3 gene. This predominance of CCR6⁺ Treg cells was also found in the draining lymph nodes and tumor-infiltrating lymphocytes of OSCC patients with early or late clinical staging. Moreover, CCR6⁺ Treg cells isolated from tumor-infiltrating lymphocytes or draining lymph nodes maintained similar phenotypic and suppressive characteristics ex vivo as did their counterparts isolated from peripheral blood. These results suggest that CCR6 marks activated effector or memory Treg phenotypes with superior suppressive activity in humans.

Review: The function of regulatory T cells at the ocular surface

Regulatory T cells (Tregs) are critical modulators of immune homeostasis. Tregs maintain peripheral tolerance to self-antigens, thereby preventing autoimmune disease. Furthermore, Tregs suppress excessive immune responses deleterious to the host. Recent research has deepened our understanding of how Tregs function at the ocular surface. This manuscript describes the classification, the immunosuppressive mechanisms, and the phenotypic plasticity of Tregs. We review the contribution of Tregs to ocular surface autoimmune disease, as well as the function of Tregs in allergy and infection at the ocular surface. Finally, we review the role of Tregs in promoting allotolerance in corneal transplantation.

Skin-derived TSLP systemically expands regulatory T cells

Regulatory T cells (Tregs) are a subset of CD4+ T cells with suppressive function and are critical for limiting inappropriate activation of T cells. Hence, the expansion of Tregs is an attractive strategy for the treatment of autoimmune diseases. Here, we demonstrate that the skin possesses the remarkable capacity to systemically expand Treg numbers by producing thymic stromal lymphopoietin (TSLP) in response to vitamin D receptor stimulation. An ∼2-fold increase in the proportion and absolute number of Tregs was observed in mice treated topically but not systemically with the Vitamin D3 analog MC903. This expansion of Tregs was dependent on TSLP receptor signaling but not on VDR signaling in hematopoietic cells. However, TSLP receptor expression by Tregs was not required for their proliferation. Rather, skin-derived TSLP promoted Treg expansion through dendritic cells. Importantly, treatment of skin with MC903 significantly lowered the incidence of autoimmune diabetes in non-obese diabetic mice and attenuated disease score in experimental autoimmune encephalomyelitis. Together, these data demonstrate that the skin has the remarkable potential to control systemic immune responses and that Vitamin D-mediated stimulation of skin could serve as a novel strategy to therapeutically modulate the systemic immune system for the treatment of autoimmunity.

CCR7 and CXCR4 Expression in Primary Head and Neck Squamous Cell Carcinomas and Nodal Metastases – a Clinical and Immunohistochemical Study

Background: Squamous cell carcinomas (SCCs) are common head and neck malignancies demonstrating lymph node LN involvement. Recently chemokine receptor overxpression has been reported in many cancers. Of particular interest, CCR7 appears to be a strong mediator of LN metastases, while CXCR4 may mediate distant metastases. Any relations between their expression in primary HNSCCs and metastatic lymph nodes need to be clarified. Aims: To investigate CCR7 andCXCR4 expression in primary HNSCCs of all tumor sizes, clinical stages and histological grades, as well as involved lymph nodes, then make comparisons, also with control normal oral epithelium. Materials and Methods: The sample consisted of 60 formalin-fixed, paraffin-embedded specimens of primary HNSCCs, 77 others of metastasi-positive lymph nodes, and 10 of control normal oral epithelial tissues. Sections were conventionally stained with H&E and immunohistochemically with monoclonal anti-CCR7 and monoclonal anti-CXCR4 antibodies. Positive cells were counted under microscopic assessment in four fields (X40) per case. Results: There was no variation among primary HNSCC tumors staining positive for CCR7 and CXCR4 with tumor size of for CCR7 with lymph node involvement. However, a difference was noted between primary HNSCC tumors stained by CXCR4 with a single as compared to more numerous node involvement. CXCR4 appear to vary with the clinical stagebut no links were noted with histological grades. Staining for primary HNSCC tumors and metastatic lymph nodes correlated.

β-cell-specific IL-35 therapy suppresses ongoing autoimmune diabetes in NOD mice

IL-35 is a recently identified cytokine exhibiting potent immunosuppressive properties. The therapeutic potential and effects of IL-35 on pathogenic T effector cells (Teff) and Foxp3⁺ Treg, however, are ill defined. We tested the capacity of IL-35 to suppress ongoing autoimmunity in NOD mice. For this purpose, an adeno-associated virus vector in which IL-35 transgene expression is selectively targeted to β cells via an insulin promoter (AAV8mIP-IL35) was used. AAV8mIP-IL35 vaccination of NOD mice at a late preclinical stage of type 1 diabetes (T1D) suppressed β-cell autoimmunity and prevented diabetes onset. Numbers of islet-resident conventional CD4⁺ and CD8⁺ T cells, and DCs were reduced within 4 weeks of AAV8mIP-IL35 treatment. The diminished islet T-cell pool correlated with suppressed proliferation, and a decreased frequency of IFN-γ-expressing Teff. Ectopic IL-35 also reduced islet Foxp3⁺ Treg numbers and proliferation, and protection was independent of induction/expansion of adaptive islet immunoregulatory T cells. These findings demonstrate that IL-35-mediated suppression is sufficiently robust to block established β-cell autoimmunity, and support the use of IL-35 to treat T1D and other T-cell-mediated autoimmune diseases.

Mechanisms of T cell organotropism

Protective immunity relies upon T cell differentiation and subsequent migration to target tissues. Similarly, immune homeostasis requires the localization of regulatory T cells (Tregs) to the sites where immunity takes place. While naïve T lymphocytes recirculate predominantly in secondary lymphoid tissue, primed T cells and activated Tregs must traffic to the antigen rich non-lymphoid tissue to exert effector and regulatory responses, respectively. Following priming in draining lymph nodes, T cells acquire the 'homing receptors' to facilitate their access to specific tissues and organs. An additional level of topographic specificity is provided by T cells receptor recognition of antigen displayed by the endothelium. Furthermore, co-stimulatory signals (such as those induced by CD28) have been shown not only to regulate T cell activation and differentiation, but also to orchestrate the anatomy of the ensuing T cell response. We here review the molecular mechanisms supporting trafficking of both effector and regulatory T cells to specific antigen-rich tissues.

Differences in phenotype, homing properties and suppressive activities of regulatory T cells induced by epicutaneous, oral or sublingual immunotherapy in mice sensitized to peanut

Allergen-specific immunotherapy has been proposed as an attractive strategy to actively treat food allergy using the following three different immunotherapy routes: oral (OIT), sublingual (SLIT) and epicutaneous (EPIT) immunotherapy. Regulatory T cells (Tregs) have been shown to have a pivotal role in the mechanisms of immunotherapy. The aim of this study was to compare the phenotype and function of Tregs induced in peanut-sensitized BALB/c mice using these three routes of treatment. We show that although EPIT, OIT and SLIT were all able to effectively desensitize peanut-sensitized mice, they induced different subsets of Tregs. Foxp3+ Tregs were induced by the three treatment routes but with greater numbers induced by EPIT. EPIT and OIT also increased the level of LAP+ Tregs, whereas SLIT induced IL-10+ cells. The suppressive activity of EPIT-induced Tregs did not depend on IL-10 but required CTLA-4, whereas OIT acted through both mechanisms and SLIT was strictly dependent on IL-10. Moreover, the three routes influenced the homing properties of induced Tregs differently, with a larger repertoire of chemokine receptors expressed by EPIT-induced Tregs compared with OIT- and SLIT- induced cells, resulting in different protective consequences against allergen exposure. Furthermore, whereas OIT- or SLIT-induced Tregs lost their suppressive activities after treatment was discontinued, the suppressive activities of EPIT-induced Tregs were still effective 8 weeks after the end of treatment, suggesting the induction of a more long-lasting tolerance. In summary, EPIT, OIT and SLIT mediated desensitization through the induction of different subsets of Tregs, leading to important differences in the subsequent protection against allergen exposure and the possible induction of tolerance.

Reduced interleukin-2 responsiveness impairs the ability of Treg cells to compete for IL-2 in nonobese diabetic mice

Enhancement of regulatory T cell (Treg cell) frequency and function is the goal of many therapeutic strategies aimed at treating type 1 diabetes (T1D). The interleukin-2 (IL-2) pathway, which has been strongly implicated in T1D susceptibility in both humans and mice, is a master regulator of Treg cell homeostasis and function. We investigated how IL-2 pathway defects impact Treg cells in T1D-susceptible nonobese diabetic (NOD) mice in comparison with protected C57BL/6 and NOD congenic mice. NOD Treg cells were reduced in frequency specifically in the lymph nodes and expressed lower levels of CD25 and CD39/CD73 immunosuppressive molecules. In the spleen and blood, Treg cell frequency was preserved through expansion of CD25(low), effector phenotype Treg cells. Reduced CD25 expression led to decreased IL-2 signaling in NOD Treg cells. In vivo, treatment with IL-2-anti-IL-2 antibody complexes led to effective upregulation of suppressive molecules on NOD Treg cells in the spleen and blood, but had reduced efficacy on lymph node Treg cells. In contrast, NOD CD8(+) and CD4(+) effector T cells were not impaired in their response to IL-2 therapy. We conclude that NOD Treg cells have an impaired responsiveness to IL-2 that reduces their ability to compete for a limited supply of IL-2.

Blockade of CCR7 leads to decreased dendritic cell migration to draining lymph nodes and promotes graft survival in low-risk corneal transplantation

The chemokine receptor CCR7 is essential for migration of mature dendritic cells (DCs) to the regional lymph nodes, and it has been shown that blocking of CCR7 improves graft survival after high-risk corneal transplantation in vascularized recipient corneas. However, it is so far unknown whether blocking of CCR7 reduces migration of DCs from the avascular cornea to the draining lymph nodes and whether this leads to improved graft survival also in the low-risk setting of corneal transplantation, which accounts for the majority of perforating transplantations performed. Therefore, in this study, pellets containing Freund's adjuvant and bovine serum albumin (BSA) conjugated to Alexa488 fluorescent dye were implanted into the corneal stroma of BALB/c mice to analyze antigen uptake by corneal DCs and their migration to the regional lymph nodes. After pellet implantation, mice were either treated by local administration of a CCR7 blocking fusion protein that consisted of CCL19 fused to the Fc part of human IgG1 or a control-IgG. In vivo fluorescence microscopy showed uptake of Alexa488-conjugated BSA by corneal DCs within 8 h. Furthermore, analysis of single cell suspensions of draining lymph nodes prepared after 48 h revealed that 2.1 ± 0.3% of CD11c(+) cells were also Alexa488(+). Importantly, DC migration was significantly reduced after topical administration of CCL19-IgG (1.2 ± 0.2%; p < 0.05). To test the effect of CCR7 blockade on graft rejection after allogeneic low-risk keratoplasty, corneal transplantations were performed using C57BL/6-mice as donors and BALB/c-mice as recipients. Treatment mice received two intraperitoneal loading doses of CCL19-IgG prior to transplantation, followed by local treatment with CCL19-IgG containing eye drops for the first two weeks after transplantation. Control mice received same amounts of control-IgG. Kaplan-Meier survival analysis showed that in the CCL19-IgG treated group, 76% of the grafts survived through the end of the 8 week observation period, whereas 38% of the grafts survived in the control group (p < 0.05). Taken together, our study shows that blockade of CCR7 reduces the migration of mature corneal DCs to the draining lymph nodes and leads to improved graft survival in low-risk corneal transplantation.

Foxp3(+) regulatory T cells are expanded in severe atopic dermatitis patients

Regulatory T cells (Tregs) are known to play critical roles in homeostasis and immune responses in the skin. Whether Treg frequencies are altered in atopic dermatitis (AD) patients has been addressed by several studies, leading to conflicting results. The detection of Tregs by FOXP3 expression may lead to false-positive results as activated T cells without regulatory function may transiently upregulate this transcription factor. In contrast, measurement of the DNA methylation status of a region within the FOXP3 locus that is selectively demethylated only in bona fide Tregs (Treg-specific demethylated region, TSDR) represents a reliable method to quantify Tregs. Here, we measured circulating Treg frequencies of adult patients and detected a positive correlation with disease severity. Subsequent surface marker analysis revealed higher frequencies of CD45RA(+) CCR7(-) tissue-homing Tregs in the patient group with a tendency of reduced expression of CD39 compared with healthy donors, a marker for the highly suppressive TREM subtype.

Lymph node trafficking of regulatory T cells is prerequisite for immune suppression

Regulatory T cells have a crucial role in health and disease because of their immune regulation function. However, the anatomic sites where regulatory T cells exert optimal immune regulation are open to debate. In our current study with the use of a shear-stress flow assay, we found that regulatory T cells exhibited significantly decreased adhesion to either activated endothelial monolayer or intercellular adhesion molecule 1 or E-selectin-coated surfaces compared with activated effector T cells. The less transmigration capacity of the regulatory T cells prompted our speculation of preferential lymph node localization for the regulatory T cells that endowed these cells with immune regulation function in the most efficient manner. To test this hypothesis, the role of lymph node localization in regulatory T cell-mediated immune suppression was evaluated with a footpad inflammation model. We found that adoptively transferred regulatory T cells inhibited the development of footpad inflammation. In addition, although blockage of CCR7 or CD62L had no effect on the immune suppressive function of the regulatory T cells per se, pretreatment of the regulatory T cells with either CCR7 or CD62L blocking antibodies prevented their recruitment into draining lymph nodes and concomitantly abrogated the immune suppressive effects of adoptively transferred regulatory T cells during footpad inflammation. Our data demonstrate the crucial role of lymph node localization in regulatory T cell-mediated immune suppression and suggest a probable hierarchy in the anatomic sites for optimal immune regulation. Elucidating the relationships between the transmigration characteristics of the regulatory T cells and their immune regulation function will provide insightful information for regulatory T cell-based cell therapy.

The CD4(+) AT2R(+) T cell subpopulation improves post-infarction remodelling and restores cardiac function

Myocardial infarction (MI) is a major condition causing heart failure (HF). After MI, the renin angiotensin system (RAS) and its signalling octapeptide angiotensin II (Ang II) interferes with cardiac injury/repair via the AT1 and AT2 receptors (AT1R, AT2R). Our study aimed at deciphering the mechanisms underlying the link between RAS and cellular components of the immune response relying on a rodent model of HF as well as HF patients. Flow cytometric analyses showed an increase in the expression of CD4(+) AT2R(+) cells in the rat heart and spleen post-infarction, but a reduction in the peripheral blood. The latter was also observed in HF patients. The frequency of rat CD4(+) AT2R(+) T cells in circulating blood, post-infarcted heart and spleen represented 3.8 ± 0.4%, 23.2 ± 2.7% and 22.6 ± 2.6% of the CD4(+) cells. CD4(+) AT2R(+) T cells within blood CD4(+) T cells were reduced from 2.6 ± 0.2% in healthy controls to 1.7 ± 0.4% in patients. Moreover, we characterized CD4(+) AT2R(+) T cells which expressed regulatory FoxP3, secreted interleukin-10 and other inflammatory-related cytokines. Furthermore, intramyocardial injection of MI-induced splenic CD4(+) AT2R(+) T cells into recipient rats with MI led to reduced infarct size and improved cardiac performance. We defined CD4(+) AT2R(+) cells as a T cell subset improving heart function post-MI corresponding with reduced infarction size in a rat MI-model. Our results indicate CD4(+) AT2R(+) cells as a promising population for regenerative therapy, via myocardial transplantation, pharmacological AT2R activation or a combination thereof.

Regulatory T cells with CD62L or TNFR2 expression in young type 1 diabetic patients: relation to inflammation, glycemic control and micro-vascular complications

BACKGROUND

Alteration of regulatory T cells (Tregs) may contribute to ineffective suppression of proinflammatory cytokines in type 1 diabetes.

AIM

We determined the percentage of Tregs expressing CD62L or tumor necrosis factor receptor type 2 (TNFR2) in 70 young type 1 diabetic patients compared with 30 controls and assessed their relation to inflammation, glycemic control and micro-vascular complications.

METHODS

High-sensitivity C-reactive protein (hs-CRP), hemoglobin A1c (HbA1c), tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) were assessed with flow cytometric analysis of Tregs, Tregs expressing CD62L or TNFR2.

RESULTS

The percentage of CD4(+)CD25(high) T cells and CD4(+)CD25(high)CD62L(high) cells were significantly decreased while CD4(+)CD25(high)TNFR2(+) T cells were elevated in patients with micro-vascular complications than those without and controls (p<0.001). ROC curve revealed that the cutoff values of Tregs, Tregs expressing CD62L and Tregs expressing TNFR2 (7.46%, 24.2% and 91.9%, respectively) could detect micro-vascular complications. Significant negative correlations were observed between Tregs expressing CD62L and disease duration, FBG, HbA1c, urinary albumin excretion and hs-CRP, whereas, positive correlations were found between Tregs expressing TNFR2 and these variables (p<0.05). TNF-α was significantly increased while IL-10 was decreased among patients with micro-vascular complications than those without (p<0.05).

CONCLUSIONS

Alteration in the frequency of Tregs and Tregs expressing CD62L or TNFR2 in type 1 diabetes is associated with increased inflammation, poor glycemic control and risk of micro-vascular complications.

Organ-specific and memory treg cells: specificity, development, function, and maintenance

Foxp3⁺ regulatory T cells (Treg cells) are essential for establishing and maintaining self-tolerance, and also inhibit immune responses to innocuous environmental antigens. Imbalances and dysfunction in Treg cells lead to a variety of immune-mediated diseases, as deficits in Treg cell function contribute to the development autoimmune disease and pathological tissue damage, whereas overabundance of Treg cells can promote chronic infection and tumorigenesis. Recent studies have highlighted the fact that Treg cells themselves are a diverse collection of phenotypically and functionally specialized populations, with distinct developmental origins, antigen-specificities, tissue-tropisms, and homeostatic requirements. The signals directing the differentiation of these populations, their specificities and the mechanisms by which they combine to promote organ-specific and systemic tolerance, and how they embody the emerging property of regulatory memory are the focus of this review.

Naïve T cells, unconventional NK and NKT cells, and highly responsive monocyte-derived macrophages characterize human cord blood

This study compares the human immune systems of neonates and adults. Flow cytometric analysis was used to study the cellular phenotypes of cord blood (CB) and adult peripheral blood (APB). Luminex analysis was used to determine the levels of cytokines in cell culture supernatants. Our findings indicate that T cells in CB were mainly naïve and thus less responsive to PMA/ionomycin with the synthesis of cytokines. The percentages of CD3(+)CD4(+)CD25(high) and of CD3(+)CD4(+)CD25(dim) cells expressing chemokine receptors were different between CB and APB. TLR1, TLR6 and TLR9 expressions on NK and NKT cells also differed between CB and APB. CB monocyte-derived macrophages responded better than APB macrophages to TLR ligands with increased secretion of inflammatory cytokines, especially IL-6. The high levels of the inflammatory cytokines in cell culture supernatants of CB were mainly due to higher numbers of responsive macrophages, since dendritic cell numbers were lower in CB than APB.

pH of drinking water influences the composition of gut microbiome and type 1 diabetes incidence

Nonobese diabetic (NOD) mice spontaneously develop type 1 diabetes (T1D), progression of which is similar to that in humans, and therefore are widely used as a model for understanding the immunological basis of this disease. The incidence of T1D in NOD mice is influenced by the degree of cleanliness of the mouse colony and the gut microflora. In this report, we show that the T1D incidence and rate of disease progression are profoundly influenced by the pH of drinking water, which also affects the composition and diversity of commensal bacteria in the gut. Female NOD mice that were maintained on acidic pH water (AW) developed insulitis and hyperglycemia rapidly compared with those on neutral pH water (NW). Interestingly, forced dysbiosis by segmented filamentous bacteria (SFB)-positive fecal transfer significantly suppressed the insulitis and T1D incidence in mice that were on AW but not in those on NW. The 16S rDNA-targeted pyrosequencing revealed a significant change in the composition and diversity of gut flora when the pH of drinking water was altered. Importantly, autoantigen-specific T-cell frequencies in the periphery and proinflammatory cytokine response in the intestinal mucosa are significantly higher in AW-recipient mice compared with their NW counterparts. These observations suggest that pH of drinking water affects the composition of gut microflora, leading to an altered autoimmune response and T1D incidence in NOD mice.

Chemokines and chemokine receptors: positioning cells for host defense and immunity

Chemokines are chemotactic cytokines that control the migratory patterns and positioning of all immune cells. Although chemokines were initially appreciated as important mediators of acute inflammation, we now know that this complex system of approximately 50 endogenous chemokine ligands and 20 G protein-coupled seven-transmembrane signaling receptors is also critical for the generation of primary and secondary adaptive cellular and humoral immune responses. Recent studies demonstrate important roles for the chemokine system in the priming of naive T cells, in cell fate decisions such as effector and memory cell differentiation, and in regulatory T cell function. In this review, we focus on recent advances in understanding how the chemokine system orchestrates immune cell migration and positioning at the organismic level in homeostasis, in acute inflammation, and during the generation and regulation of adoptive primary and secondary immune responses in the lymphoid system and peripheral nonlymphoid tissue.

β-cell-specific IL-2 therapy increases islet Foxp3+Treg and suppresses type 1 diabetes in NOD mice

Interleukin-2 (IL-2) is a critical cytokine for the homeostasis and function of forkhead box p3-expressing regulatory T cells (Foxp3(+)Tregs). Dysregulation of the IL-2-IL-2 receptor axis is associated with aberrant Foxp3(+)Tregs and T cell-mediated autoimmune diseases such as type 1 diabetes. Treatment with recombinant IL-2 has been reported to enhance Foxp3(+)Tregs and suppress different models of autoimmunity. However, efficacy of IL-2 therapy is dependent on achieving sufficient levels of IL-2 to boost tissue-resident Foxp3(+)Tregs while avoiding the potential toxic effects of systemic IL-2. With this in mind, adeno-associated virus (AAV) vector gene delivery was used to localize IL-2 expression to the islets of NOD mice. Injection of a double-stranded AAV vector encoding IL-2 driven by a mouse insulin promoter (dsAAVmIP-IL2) increased Foxp3(+)Tregs in the islets but not the draining pancreatic lymph nodes. Islet Foxp3(+)Tregs in dsAAVmIP-IL2-treated NOD mice exhibited enhanced fitness marked by increased expression of Bcl-2, proliferation, and suppressor function. In contrast, ectopic IL-2 had no significant effect on conventional islet-infiltrating effector T cells. Notably, β-cell-specific IL-2 expression suppressed late preclinical type 1 diabetes in NOD mice. Collectively, these findings demonstrate that β-cell-specific IL-2 expands an islet-resident Foxp3(+)Tregs pool that effectively suppresses ongoing type 1 diabetes long term.

Chronic follicular bronchiolitis requires antigen-specific regulatory T cell control to prevent fatal disease progression

To study regulatory T (Treg) cell control of chronic autoimmunity in a lymphoreplete host, we created and characterized a new model of autoimmune lung inflammation that targets the medium and small airways. We generated transgenic mice that express a chimeric membrane protein consisting of hen egg lysozyme and a hemoglobin epitope tag under the control of the Clara cell secretory protein promoter, which largely limited transgene expression to the respiratory bronchioles. When Clara cell secretory protein-membrane hen egg lysozyme/hemoglobin transgenic mice were crossed to N3.L2 TCR transgenic mice that recognize the hemoglobin epitope, the bigenic progeny developed dense, pseudo-follicular lymphocytic peribronchiolar infiltrates that resembled the histological pattern of follicular bronchiolitis. Aggregates of activated IFN-γ- and IL-17A-secreting CD4(+) T cells as well as B cells surrounded the airways. Lung pathology was similar in Ifng(-/-) and Il17a(-/-) mice, indicating that either cytokine is sufficient to establish chronic disease. A large number of Ag-specific Treg cells accumulated in the lesions, and Treg cell depletion in the affected mice led to an interstitial spread of the disease that ultimately proved fatal. Thus, Treg cells act to restrain autoimmune responses, resulting in an organized and controlled chronic pathological process rather than a progressive disease.

Regulatory T cells inhibit Th1 cell-mediated bile duct injury in murine biliary atresia

BACKGROUND & AIMS

Biliary atresia (BA) is a pediatric inflammatory disease of the biliary system which leads to cirrhosis and the need for liver transplantation. One theory regarding etiology is that bile duct injury is due to virus-induced autoreactive T cell-mediated inflammation. Regulatory T cell (Treg) abnormalities in BA could result in unchecked bystander inflammation and autoimmunity targeting bile ducts. The aim of this study was to determine if Tregs are dysfunctional in the rotavirus-induced mouse model of BA (murine BA).

METHODS

Murine BA resulted from infection of BALB/c neonates with Rhesus rotavirus (RRV).

RESULTS

Liver Tregs from BA mice were decreased in number, activation marker expression, and suppressive function. Adoptive transfer studies revealed that RRV-infected mice that received Tregs had significantly increased survival (84%) compared to controls (12.5%). In addition, ablation of Tregs in older mice, followed by RRV infection, resulted in increased bile duct injury.

CONCLUSIONS

These studies demonstrate that dysregulation of Tregs is present in murine BA and that diminished Treg function may be implicated in the pathogenesis of human BA.