Mechanisms of human FoxP3+ Treg cell development and function in health and disease

Long non-coding RNA TMEM51-AS1 inhibits colorectal cancer progression

Colorectal cancer (CRC) is the third most common cause of death worldwide and has high mortality and a poor prognosis. Long non-coding RNAs (lncRNAs) are non-coding RNAs longer than 200 nucleotides that play roles in cancer through multiple mechanisms. TMEM51-AS1 is a newly discovered 40,650 bp lncRNA. Our results showed that TMEM51-AS1 expression was significantly downregulated in CRC tissues (fold change = 0.74, P < 0.0001). This finding was confirmed in 20 pairs of CRC carcinoma and paracancerous tissues (fold change = 0.5, P < 0.001). Additionally, TMEM51-AS1 expression was found to be significantly reduced in CRC cell lines compared to normal human intestinal epithelial cells (P < 0.001). Bioinformatic analysis revealed that TMEM51-AS1 expression was associated with immune escape, RNA methylation, and DNA damage and repair. TMEM51-AS1 may also activate energy metabolism pathways to participate in cancer development. Drug sensitivity analysis confirmed that several drugs are more effective in CRC patients with high expression of TMEM51-AS1. In conclusion, our study demonstrates that TMEM51-AS1 can suppress the progression of CRC.

A synthetic review: natural history of amniote reproductive modes in light of comparative evolutionary genomics

There is a current lack of consensus on whether the ancestral parity mode was oviparity (egg-laying) or viviparity (live-birth) in amniotes and particularly in squamates (snakes, lizards, and amphisbaenids). How transitions between parity modes occur at the genomic level has primary importance for how science conceptualises the origin of amniotes, and highly variable parity modes in Squamata. Synthesising literature from medicine, poultry science, reproductive biology, and evolutionary biology, I review the genomics and physiology of five broad processes (here termed the 'Main Five') expected to change during transitions between parity modes: eggshell formation, embryonic retention, placentation, calcium transport, and maternal-fetal immune dynamics. Throughout, I offer alternative perspectives and testable hypotheses regarding proximate causes of parity mode evolution in amniotes and squamates. If viviparity did evolve early in the history of lepidosaurs, I offer the nucleation site hypothesis as a proximate explanation. The framework of this hypothesis can be extended to amniotes to infer their ancestral state. I also provide a mechanism and hypothesis on how squamates may transition from viviparity to oviparity and make predictions about the directionality of transitions in three species. After considering evidence for differing perspectives on amniote origins, I offer a framework that unifies (i) the extended embryonic retention model and (ii) the traditional model which describes the amniote egg as an adaptation to the terrestrial environment. Additionally, this review contextualises the origin of amniotes and parity mode evolution within Medawar's paradigm. Medawar posited that pregnancy could be supported by immunosuppression, inertness, evasion, or immunological barriers. I demonstrate that this does not support gestation or gravidity across most amniotes but may be an adequate paradigm to explain how the first amniote tolerated internal fertilization and delayed egg deposition. In this context, the eggshell can be thought of as an immunological barrier. If serving as a barrier underpins the origin of the amniote eggshell, there should be evidence that oviparous gravidity can be met with a lack of immunological responses in utero. Rare examples of two species that differentially express very few genes during gravidity, suggestive of an absent immunological reaction to oviparous gravidity, are two skinks Lampropholis guichenoti and Lerista bougainvillii. These species may serve as good models for the original amniote egg. Overall, this review grounds itself in the historical literature while offering a modern perspective on the origin of amniotes. I encourage the scientific community to utilise this review as a resource in evolutionary and comparative genomics studies, embrace the complexity of the system, and thoughtfully consider the frameworks proposed.

The autoimmune architecture of childhood idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome, the most common glomerular disorder in children, has long been considered an immune-mediated disease based on the efficacy of glucocorticoids at inducing remission. Nevertheless, the immune processes leading to podocytopathy have largely remained elusive. The success of B-cell depletion with rituximab, descriptions of B-cell dysregulation during active disease, and the most recent discovery of autoantibodies targeting the major podocyte antigen nephrin point to an autoimmune humoral etiology for idiopathic nephrotic syndrome. Investigations of the immune factors involved in idiopathic nephrotic syndrome pathogenesis have uncovered common features with other autoimmune disorders that will aid in prognostication and in guiding the expansion of our glucocorticoid-sparing therapeutic arsenal. In this review, we discuss the emerging autoimmune architecture of idiopathic nephrotic syndrome, with a specific focus on pediatric steroid-sensitive disease, including the podocyte-reactive B-cell response that causes anti-podocyte antibodies, the predisposing genetic factors that shape the podocyte-reactive immune landscape, and the immune triggers driving active disease.

Anti-PD-1 amplifies costimulation in melanoma-infiltrating Th1-like Foxp3+ regulatory T cells to alleviate local immunosuppression

BACKGROUND

Immune checkpoint inhibitors targeting programmed cell death protein-1 (PD-1) are the first line of treatment for many solid tumors including melanoma. PD-1 blockade enhances the effector functions of melanoma-infiltrating CD8+ T cells, leading to durable tumor remissions. However, 55% of patients with melanoma do not respond to treatment. As Foxp3+ regulatory T (Treg) cells play an important role in tumor-induced immunosuppression and express PD-1, we hypothesized that anti-PD-1 also increases the functions of melanoma-infiltrating Treg cells, which could be detrimental to treatment efficacy.

METHODS

The cellular and functional dynamics of Treg cells were evaluated in C57Bl/6 Foxp3-reporter mice bearing highly immunogenic and PD-1 blockade-sensitive Yale University Mouse Melanoma Exposed to Radiation 1.7 (YUMMER1.7) tumors. Treg cell responses in tumors and lymphoid compartments were examined throughout tumor growth or therapy and were assessed ex vivo by multiparametric flow cytometry analysis, with in vitro suppression assays using tumor-infiltrating lymphocytes isolated by fluorescence-activated cell sorting (FACS) and in situ through spatial proteomic and transcriptomic profiling.

RESULTS

In this highly immunogenic melanoma model, anti-PD-1 monotherapy yielded high responders (HRs) and low responders (LRs). We show that the potent CD8+ T cell responses characteristic of HR tumors paradoxically coincide with the expansion of highly-activated, Helios-expressing Treg cells. In both HRs and LRs, Treg cells co-localize with CD8+ T cells in immunogenic regions of the tumor and display potent suppressive capacity in vitro. Further characterization revealed that melanoma-infiltrating Treg cells progressively acquire T-bet and interferon gamma expression, exclusively in HRs, and induction of this T helper cell 1 (Th1)-like phenotype in vitro led to CD8+ T cell evasion from Treg cell-mediated suppression. Using spatial proteomic and transcriptomic profiling, we demonstrate that Treg cells display an increased activity of PI3K/Akt signaling in regions of HR tumors with an elevated CD8:Treg cell ratio.

CONCLUSIONS

PD-1 blockade promotes the expansion of a subset of highly-activated Treg cells coexpressing PD-1 and Helios. While these cells are potently suppressive outside tumor environments, costimulatory and inflammatory signals present in the tumor microenvironment lead to their local acquisition of Th1-like characteristics and loss of suppression of effector T cells.

The IL-2 SYNTHORIN molecule promotes functionally adapted Tregs in a preclinical model of type 1 diabetes

Deficits in IL-2 signaling can precipitate autoimmunity by altering the function and survival of FoxP3+ regulatory T cells (Tregs) while high concentrations of IL-2 fuel inflammatory responses. Recently, we showed that the non-beta IL-2 SYNTHORIN molecule SAR444336 (SAR'336) can bypass the induction of autoimmune and inflammatory responses by increasing its reliance on IL-2 receptor α chain subunit (CD25) to provide a bona fide IL-2 signal selectively to Tregs, making it an attractive approach for the control of autoimmunity. In this report, we further demonstrate that SAR'336 can support non-beta IL-2 signaling in murine Tregs and limit NK and CD8+ T cells' proliferation and function. Using a murine model of spontaneous type 1 diabetes, we showed that the administration of SAR'336 slows the development of disease in mice by decreasing the degree of insulitis through the expansion of antigen-specific Tregs over Th1 cells in pancreatic islets. Specifically, SAR'336 promoted the differentiation of IL-33-responsive (ST2+), IL-10-producing GATA3+ Tregs over other Treg subsets in the pancreas, demonstrating the ability of this molecule to further orchestrate Treg adaptation. These results offer insight into the capacity of SAR'336 to generate highly specialized, tissue-localized Tregs that promote restoration of homeostasis during ongoing autoimmune disease.

The Expression of Forkhead Box P3 T Regulatory Lymphocytes as a Prognostic Factor in Malignant Melanomas

Since transcription factor Forkhead Box P3 (FoxP3) was identified as a specific regulatory T cell (Treg) marker, researchers have scrutinized its value as a potential novel therapeutic target or a prognostic factor in various types of cancer with inconsistent results. The present analysis was performed to assess the influence of Treg FoxP3 expression on the prognosis of primary melanoma and to evaluate the correlations with various clinicopathological prognostic factors. We analyzed all eligible patients with stage pT3 primary malignant melanomas treated in a tertiary cancer center. Immunohistochemical staining for Treg FoxP3 expression was performed on retrospectively identified paraffin blocks and subsequently correlated with the outcomes of the patients. A total of 81% of the patients presented a positive Treg FoxP3 expression, being correlated with a higher risk of lymph node metastasis, tumor relapse, and death. Moreover, positive expression was statistically associated with a shorter OS. The tumor relapse rate was estimated at 36.7%. A positive expression of Treg FoxP3 and lymph node metastasis were associated with a higher risk of death based on multivariate analysis. Treg FoxP3 expression may be used as an independent prognostic factor in patients with malignant melanoma to evaluate tumor progression and survival.

CD4+ Foxp3+ Regulatory T-cells in Modulating Inflammatory Microenvironment in Chronic Rhinosinusitis with Nasal Polyps: Progress and Future Prospect

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a subtype of chronic rhinosinusitis (CRS) characterized by the presence of nasal polyps (NP) in the paranasal mucosa. Despite the complex etiology, NP is believed to result from chronic inflammation. The long-term aftermath of the type 2 response is responsible for symptoms seen in NP patients, i.e. rhinorrhea, hyposmia, and nasal obstruction. Immune cellular tolerogenic mechanisms, particularly CD4 + Foxp3 + regulatory T cells (Tregs), are crucial to curtail inflammatory responses. Current evidence suggests impaired Treg activity is the main reason underlying the compromise of self-tolerance, contributing to the onset of CRSwNP. There is compelling evidence that tumor necrosis factor 2 (TNFR2) is preferentially expressed by Tregs, and TNFR2 is able to identify the most potent suppressive subset of Tregs. Tumor necrosis factor (TNF)-TNFR2 interaction plays a decisive role in the activation and expansion of Tregs. This review summarizes current understanding of Tregs biology, focusing on the discussion of the recent advances in the study of TNF-TNFR2 axis in the upregulation of Treg function as a negative feedback mechanism in the control of chronic inflammation. The role of dysregulation of Tregs in the immunopathogenesis of CRSwNP will be analyzed. The future perspective on the harnessing Tregs-mediated self-tolerant mechanism in the management of CRSwNP will be introduced.

Optimizing cancer therapy: a review of the multifaceted effects of metronomic chemotherapy

Metronomic chemotherapy (MCT), characterized by the continuous administration of chemotherapeutics at a lower dose without prolonged drug-free periods, has garnered significant attention over the last 2 decades. Extensive evidence from both pre-clinical and clinical settings indicates that MCT induces distinct biological effects than the standard Maximum Tolerated Dose (MTD) chemotherapy. The low toxicity profile, reduced likelihood of inducing acquired therapeutic resistance, and low cost of MCT render it an attractive chemotherapeutic regimen option. One of the most prominent aspects of MCT is its anti-angiogenesis effects. It has been shown to stimulate the expression of anti-angiogenic molecules, thereby inhibiting angiogenesis. In addition, MCT has been shown to decrease the regulatory T-cell population and promote anti-tumor immune response through inducing dendritic cell maturation and increasing the number of cytotoxic T-cells. Combination therapies utilizing MCT along with oncolytic virotherapy, radiotherapy or other chemotherapeutic regimens have been studied extensively. This review provides an overview of the current status of MCT research and the established mechanisms of action of MCT treatment and also offers insights into potential avenues of development for MCT in the future.

Low-dose IL-2 therapy in autoimmune diseases: An update review

Regulatory T (Treg) cells are essential for maintaining self-immune tolerance. Reduced numbers or functions of Treg cells have been involved in the pathogenesis of various autoimmune diseases and allograft rejection. Therefore, the approaches that increase the pool or suppressive function of Treg cells in vivo could be a general strategy to treat different autoimmune diseases and allograft rejection. Interleukin-2 (IL-2) is essential for the development, survival, maintenance, and function of Treg cells, constitutively expressing the high-affinity receptor of IL-2 and sensitive response to IL-2 in vivo. And low-dose IL-2 therapy in vivo could restore the imbalance between autoimmune response and self-tolerance toward self-tolerance via promoting Treg cell expansion and inhibiting follicular helper T (Tfh) and IL-17-producing helper T (Th17) cell differentiation. Currently, low-dose IL-2 treatment is receiving extensive attention in autoimmune disease and transplantation treatment. In this review, we summarize the biology of IL-2/IL-2 receptor, the mechanisms of low-dose IL-2 therapy in autoimmune diseases, the application in the progress of different autoimmune diseases, including Systemic Lupus Erythematosus (SLE), Type 1 Diabetes (T1D), Rheumatoid Arthritis (RA), Autoimmune Hepatitis (AIH), Alopecia Areata (AA), Immune Thrombocytopenia (ITP) and Chronic graft-versus-host-disease (GVHD). We also discuss the future directions to optimize low-dose IL-2 treatments.

Prediction of Th17/Treg cell balance on length of stay in intensive care units of patients with sepsis

Background

Prolonged length of stay (LOS) of sepsis can drain a hospital's material and human resources. This study investigated the correlations between T helper type 17 (Th17) and regulatory T (Treg) balance with LOS in sepsis.

Methods

A prospective clinical observational study was designed in Changhai Hospital affiliated to Naval Medical University in Shanghai, China, from January to October 2020. The patients diagnosed with sepsis and who met the inclusion and exclusion criteria were recruited and whether the levels of cytokines, procalcitonin, subtypes, and biomarkers of T cells in the peripheral blood were detected. We analyzed the correlation between these and LOS.

Results

Sixty septic patients were classified into two groups according to whether their intensive care unit (ICU) stay exceeded 14 days. The patients with LOS ≥14 days were older ([72.6±7.5] years vs. [63.3±10.4] years, P=0.015) and had higher Sequential Organ Failure Assessment (SOFA) (median [interquartile range]: 6.5 [5.0-11.0] vs. 4.0 [3.0-6.0], P=0.001) and higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (16.0 [13.0-21.0] vs. 8.5 [7.0-14.0], P=0.001). There was no difference in other demographic characteristics and cytokines, interleukin-6, tumor necrosis factor-α, and interleukin-10 between the two groups. The Th17/Treg ratio of sepsis with LOS <14 days was considerably lower (0.48 [0.38-0.56] vs. 0.69 [0.51-0.98], P=0.001). For patients with LOS ≥14 days, the area under the receiver operating characteristic curve for the Th17/Treg ratio was 0.766. It improved to 0.840 and 0.850 when combined with the SOFA and APACHE II scores, respectively.

Conclusions

The Th17/Treg ratio was proportional to septic severity and can be used as a potential predictor of ICU stay in sepsis, presenting a new option for ICU practitioners to better care for patients with sepsis.

The Potential of FOXP3 in Predicting Survival and Treatment Response in Breast Cancer

Background

Breast cancer (BC) continues to pose a substantial challenge to global health, necessitating an enhanced understanding of its fundamental mechanisms. Among its various pathological classifications, breast invasive carcinoma (BRCA) is the most prevalent. The role of the transcription factor forkhead box P3 (FOXP3), associated with regulatory T cells, in BRCA's diagnosis and prognosis remains insufficiently explored, despite its recognized importance.

Methods

We examined the mRNA expression profile of FOXP3 in BRCA patients, assessing its correlation with disease detection, patient survival, immune checkpoint alterations, and response to anticancer drugs.

Results

Our analysis revealed significantly elevated FOXP3 mRNA levels in BRCA patients, with a 95.7% accuracy for BRCA detection based on the area under the curve. High FOXP3 mRNA levels were positively correlated with overall survival and showed significant associations with CTLA4, CD274, PDCD1, TMB, and immune cell infiltration status. Furthermore, FOXP3 mRNA expression was linked to the efficacy of anticancer drugs and the tumor inflammation signature.

Discussion

These findings suggest that FOXP3 serves as a promising biomarker for BRCA, offering valuable insights into its diagnosis and prognosis. The correlation between FOXP3 expression and immune checkpoint alterations, along with its predictive value for treatment response, underscores its potential in guiding therapeutic strategies.

Conclusion

FOXP3 stands out as an influential factor in BRCA, highlighting its diagnostic accuracy and prognostic value. Its association with immune responses and treatment efficacy opens new avenues for research and clinical applications, positioning FOXP3 as a vital target for further investigation in BRCA management.

Deciphering the developmental trajectory of tissue-resident Foxp3+ regulatory T cells

Foxp3+ TREG cells have been at the focus of intense investigation for their recognized roles in preventing autoimmunity, facilitating tissue recuperation following injury, and orchestrating a tolerance to innocuous non-self-antigens. To perform these critical tasks, TREG cells undergo deep epigenetic, transcriptional, and post-transcriptional changes that allow them to adapt to conditions found in tissues both at steady-state and during inflammation. The path leading TREG cells to express these tissue-specialized phenotypes begins during thymic development, and is further driven by epigenetic and transcriptional modifications following TCR engagement and polarizing signals in the periphery. However, this process is highly regulated and requires TREG cells to adopt strategies to avoid losing their regulatory program altogether. Here, we review the origins of tissue-resident TREG cells, from their thymic and peripheral development to the transcriptional regulators involved in their tissue residency program. In addition, we discuss the distinct signalling pathways that engage the inflammatory adaptation of tissue-resident TREG cells, and how they relate to their ability to recognize tissue and pathogen-derived danger signals.

Insufficient phosphorylation of STAT5 in Tregs inhibits the expression of BLIMP-1 but not IRF4, reduction the proportion of Tregs in pediatric aplastic anemia

Deficiency in regulatory T cells (Tregs) is an important mechanism underlying the pathogenesis of pediatric aplastic anemia, but its specific mechanism is unclear. In our study, we aimed to investigate whether IL-2/STAT5 can regulate the proliferation of Tregs in aplastic anemia (AA) by regulating their expression of B lymphocyte-induced mature protein-1 (BLIMP-1) or interferon regulatory factor 4 (IRF4). Through clinical research and animal experiments, we found that poor activation of the IL-2/STAT5 signaling pathway may leads to low expression of BLIMP-1 in Tregs of children with AA, which leads to defects in the differentiation and proliferation of Tregs in AA. In AA model mice, treatment with IL-2c reversed the decrease in Treg proportions and reduction in Blimp-1 expression in Tregs by increasing the phosphorylation of Stat5 in Tregs. In AA, deficiency of IRF4 expression in Tregs is closely related to the deficiency of Tregs, but is not regulated by the IL-2/STAT5 pathway.

Crucial Role of Foxp3 Gene Expression and Mutation in Systemic Lupus Erythematosus, Inferred from Computational and Experimental Approaches

The impaired suppressive function of regulatory T cells is well-understood in systemic lupus erythematosus. This is likely due to changes in Foxp3 expression that are crucial for regulatory T-cell stability and function. There are a few reports on the correlation between the Foxp3 altered expression level and single-nucleotide polymorphisms within the Foxp3 locus. Moreover, some studies showed the importance of Foxp3 expression in the same diseases. Therefore, to explore the possible effects of single-nucleotide polymorphisms, here, we evaluated the association of IVS9+459/rs2280883 (T>C) and -2383/rs3761549 (C>T) Foxp3 polymorphisms with systemic lupus erythematosus. Moreover, through machine-learning and deep-learning methods, we assessed the connection of the expression level of the gene with the disease. Single-nucleotide polymorphisms of Foxp3 (IVS9+459/rs2280883 (T>C) and -2383/rs3761549 (C>T)) were, respectively, genotyped using allele-specific PCR and direct sequencing and polymerase chain reaction-restriction fragment length polymorphism, in 199 systemic lupus erythematosus patients and 206 healthy age- and sex-matched controls. The Statistical Package for the Social Sciences version 19 and Fisher's exact and chi-square tests were used to analyze the data. Moreover, six machine-learning models and two sequential deep-learning models were designed to classify patients from normal people in the E-MTAB-11191 dataset through the expression level of Foxp3 and its correlated genes. The allele and genotype frequencies of both polymorphisms in question were found to be significantly associated with an increased risk of systemic lupus erythematosus. Furthermore, both of the two single-nucleotide polymorphisms were associated with some systemic-lupus-erythematosus-related risk factors. Three SVM models and the logistic regression model showed an 81% accuracy in classification problems. In addition, the first deep-learning model showed an 83% and 89% accuracy for the training and validation data, respectively, while the second model had an 85% and 79% accuracy for the training and validation datasets. In this study, we are prompted to represent the predisposing loci for systemic lupus erythematosus pathogenesis and strived to provide evidence-based support to the application of machine learning for the identification of systemic lupus erythematosus. It is predicted that the recruiting of machine-learning algorithms with the simultaneous measurement of the applied single nucleotide polymorphisms will increased the diagnostic accuracy of systemic lupus erythematosus, which will be very helpful in providing sufficient predictive value about individual subjects with systemic lupus erythematosus.

Role of tissue markers associated with tumor microenvironment in the progression and immune suppression of oral squamous cell carcinoma

Head and neck cancers (HNC) continues to dominate major cancers contributing to  mortality worldwide. Squamous cell carcinoma is the major type of HNC. Oral Squamous Cell Carcinoma grouped under HNC is a malignant tumor occurring in the oral cavity. The primary risk factors of OSCC are tobacco, alcohol consumption, etc. This review focuses on modulations, mechanisms, growth and differentiation of oral squamous cell carcinoma. Cancer cell surrounds itself with a group of elements forming a favorable environment known as tumor microenvironment (TME). It consists of numerous cells which includes immune cells, blood cells and acellular components that are responsible for the progression, immunosuppression, metastasis and angiogenesis of cancer. This review highlights the most important tissue biomarkers (mTOR, CAF, FOXp3, CD163, CD33, CD34) that are associated with TME cells. mTOR remains as the primary regulator responsible in cancer and its importance towards immune-suppression is highlighted. Tumor-associated macrophages associated with cancer development and its relationship with immunomodulatory mechanism and Tregs, which are potential blockers of immune response and its mechanism and aberrations are discussed. Cancer-associated fibroblasts that are a part of TME and their role in evading the immune response and myeloid derived suppressor cells that have slight control over the immune response and their mechanism in the tumor progression is further explained. These markers have been emphasised as therapeutic targets and are currently in different stages of clinical trials.

Development and function of FOXP3+ regulators of immune responses

The Forkhead Box P3 (FOXP3) protein is an essential transcription factor for the development and function of regulatory T cells (Tregs), involved in the maintenance of immunological tolerance. Although extensive research over the last decade has investigated the critical role of FOXP3+ cells in preserving immune homeostasis, our understanding of their specific functions remains limited. Therefore, unveiling the molecular mechanisms underpinning the up- and downstream transcriptional regulation of and by FOXP3 is crucial for developing Treg-targeted therapeutics. Dysfunctions in FOXP3+ Tregs have also been found to be inherent drivers of autoimmune disorders and have been shown to exhibit multifaceted functions in the context of cancer. Recent research suggests that these cells may also be involved in tissue-specific repair and regeneration. Herein, we summarize current understanding of the thymic-transcriptional regulatory landscape of FOXP3+ Tregs, their epigenetic modulators, and associated signaling pathways. Finally, we highlight the contributions of FOXP3 on the functional development of Tregs and reflect on the clinical implications in the context of pathological and physiological immune responses.

CD4+ and CD8+ regulatory T cell characterization in the rat using a unique transgenic Foxp3-EGFP model

BACKGROUND

Regulatory T cells (Treg) in diverse species include CD4⁺ and CD8⁺ T cells. In all species, CD8⁺ Treg have been only partially characterized and there is no rat model in which CD4⁺ and CD8⁺ FOXP3⁺ Treg are genetically tagged.

RESULTS

We generated a Foxp3-EGFP rat transgenic line in which FOXP3 gene was expressed and controlled EGFP. CD4⁺ and CD8⁺ T cells were the only cells that expressed EGFP, in similar proportion as observed with anti-FOXP3 antibodies and co-labeled in the same cells. CD4⁺EGFP⁺ Treg were 5-10 times more frequent than CD8⁺EGFP⁺ Treg. The suppressive activity of CD4⁺ and CD8⁺ Treg was largely confined to EGFP⁺ cells. RNAseq analyses showed similarities but also differences among CD4⁺ and CD8⁺ EGFP⁺ cells and provided the first description of the natural FOXP3⁺CD8⁺ Treg transcriptome. In vitro culture of CD4⁺ and CD8⁺ EGFP^- cells with TGFbeta and IL-2 generated induced EGFP⁺ Treg. CD4⁺ and CD8⁺ EGFP⁺ Treg were expanded upon in vivo administration of a low dose of IL-2.

CONCLUSIONS

This new and unique rat line constitutes a useful model to identify and isolate viable CD4⁺ and CD8⁺ FOXP3⁺ Treg. Additionally, it allows to identify molecules expressed in CD8⁺ Treg that may allow to better define their phenotype and function not only in rats but also in other species.

The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases

The adaptive immune system and associated inflammation are vital in surveillance and host protection against internal and external threats, but can secondarily damage host tissues. The central nervous system is immune-privileged and largely protected from the circulating inflammatory pathways. However, T cell involvement and the disruption of the blood-brain barriers have been linked to several neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Under normal physiological conditions, regulatory T cells (Treg cells) dampen the inflammatory response of effector T cells. In the pathological states of many neurodegenerative disorders, the ability of Treg cells to mitigate inflammation is reduced, and a pro-inflammatory environment persists. This perspective review provides current knowledge on the roles of T cell subsets (e.g., effector T cells, Treg cells) in neurodegenerative and ocular diseases, including uveitis, diabetic retinopathy, age-related macular degeneration, and glaucoma. Many neurodegenerative and ocular diseases have been linked to immune dysregulation, but the cellular events and molecular mechanisms involved in such processes remain largely unknown. Moreover, the role of T cells in ocular pathologies remains poorly defined and limited literature is available in this area of research. Adoptive transfer of Treg cells appears to be a vital immunological approach to control ocular pathologies. Similarities in T cell dysfunction seen among non-ocular neurodegenerative diseases suggest that this area of research has a great potential to develop better therapeutic agents for ocular diseases and warrants further studies. Overall, this perspective review article provides significant information on the roles of T cells in numerous ocular and non-ocular neurodegenerative diseases.

Restoring tolerance to β-cells in Type 1 diabetes: Current and emerging strategies

Type 1 diabetes (T1D) results from insulin insufficiency due to islet death and dysfunction following T cell-mediated autoimmune attack. The technical feasibility of durable, functional autologous islet restoration is progressing such that it presents the most likely long-term cure for T1D but cannot succeed without the necessary counterpart of clinically effective therapeutic strategies that prevent grafted islets' destruction by pre-existing anti-islet T cells. While advances have been made in broad immunosuppression to lower off-target effects, the risk of opportunistic infections and cancers remains a concern, especially for well-managed T1D patients. Current immunomodulatory strategies in development focus on autologous Treg expansion, treatments to decrease antigen presentation and T effector (Teff) activation, and broad depletion of T cells with or without hematopoietic stem cell transplants. Emerging strategies harnessing the intensified DNA damage response present in expanding T cells, exacerbating their already high sensitivity to apoptosis to abate autoreactive Teff cells.

Biomarkers in oral immunotherapy

Food allergy (FA) is a global health problem that affects a large population, and thus effective treatment is highly desirable. Oral immunotherapy (OIT) has been showing reasonable efficacy and favorable safety in most FA subjects. Dependable biomarkers are needed for treatment assessment and outcome prediction during OIT. Several immunological indicators have been used as biomarkers in OIT, such as skin prick tests, basophil and mast cell reactivity, T cell and B cell responses, allergen-specific antibody levels, and cytokines. Other novel indicators also could be potential biomarkers. In this review, we discuss and assess the application of various immunological indicators as biomarkers for OIT.

Regulatory T cells in skeletal muscle repair and regeneration: recent insights

Skeletal muscle repair and regeneration after injury is a multi-stage process, involving a dynamic inflammatory microenvironment consisting of a complex network formed by the interaction of immune cells and their secreted cytokines. The homeostasis of the inflammatory microenvironment determines whether skeletal muscle repair tissues will ultimately form scar tissue or regenerative tissue. Regulatory T cells (Tregs) regulate homeostasis within the immune system and self-immune tolerance, and play a crucial role in skeletal muscle repair and regeneration. Dysregulated Tregs function leads to abnormal repair. In this review, we discuss the role and mechanisms of Tregs in skeletal muscle repair and regeneration after injury and provide new strategies for Treg immunotherapy in skeletal muscle diseases.

Natural medicines of targeted rheumatoid arthritis and its action mechanism

Rheumatoid arthritis (RA) is an autoimmune disease involving joints, with clinical manifestations of joint inflammation, bone damage and cartilage destruction, joint dysfunction and deformity, and extra-articular organ damage. As an important source of new drug molecules, natural medicines have many advantages, such as a wide range of biological effects and small toxic and side effects. They have become a hot spot for the vast number of researchers to study various diseases and develop therapeutic drugs. In recent years, the research of natural medicines in the treatment of RA has made remarkable achievements. These natural medicines mainly include flavonoids, polyphenols, alkaloids, glycosides and terpenes. Among them, resveratrol, icariin, epigallocatechin-3-gallate, ginsenoside, sinomenine, paeoniflorin, triptolide and paeoniflorin are star natural medicines for the treatment of RA. Its mechanism of treating RA mainly involves these aspects: anti-inflammation, anti-oxidation, immune regulation, pro-apoptosis, inhibition of angiogenesis, inhibition of osteoclastogenesis, inhibition of fibroblast-like synovial cell proliferation, migration and invasion. This review summarizes natural medicines with potential therapeutic effects on RA and briefly discusses their mechanisms of action against RA.

TFNR2 in Ischemia-Reperfusion Injury, Rejection, and Tolerance in Transplantation

Tumor necrosis factor receptor 2 (TNFR2) has been shown to play a crucial role in CD4+ T regulatory cells (CD4+Tregs) expansion and suppressive function. Increasing evidence has also demonstrated its role in a variety of immune regulatory cell subtypes such as CD8+ T regulatory cells (CD8+ Tregs), B regulatory cells (Bregs), and myeloid-derived suppressor cells (MDSCs). In solid organ transplantation, regulatory immune cells have been associated with decreased ischemia-reperfusion injury (IRI), improved graft survival, and improved overall outcomes. However, despite TNFR2 being studied in the context of autoimmune diseases, cancer, and hematopoietic stem cell transplantation, there remains paucity of data in the context of solid organ transplantation and islet cell transplantation. Interestingly, TNFR2 signaling has found a clinical application in islet transplantation which could guide its wider use. This article reviews the current literature on TNFR2 expression in immune modulatory cells as well as IRI, cell, and solid organ transplantation. Our results highlighted the positive impact of TNFR2 signaling especially in kidney and islet transplantation. However, further investigation of TNFR2 in all types of solid organ transplantation are required as well as dedicated studies on its therapeutic use during induction therapy or treatment of rejection.

Functional Diversities of Regulatory T Cells in the Context of Cancer Immunotherapy

Regulatory T cells (Tregs) are a subset of CD4+ T cells with their immunosuppressive activities to block abnormal or excessive immune responses to self and non-autoantigens. Tregs express the transcription factor Foxp3, maintain the immune homeostasis, and prevent the initiation of anti-tumor immune effects in various ways as their mechanisms to modulate tumor development. Recognition of different phenotypes and functions of intratumoral Tregs has offered the possibilities to develop therapeutic strategies by selectively targeting Tregs in cancers with the aim of alleviating their immunosuppressive activities from anti-tumor immune responses. Several Treg-based immunotherapeutic approaches have emerged to target cytotoxic T lymphocyte antigen-4, glucocorticoid-induced tumor necrosis factor receptor, CD25, indoleamine-2, 3-dioxygenase-1, and cytokines. These immunotherapies have yielded encouraging outcomes from preclinical studies and early-phase clinical trials. Further, dual therapy or combined therapy has been approved to be better choices than single immunotherapy, radiotherapy, or chemotherapy. In this short review article, we discuss our current understanding of the immunologic characteristics of Tregs, including Treg differentiation, development, therapeutic efficacy, and future potential of Treg-related therapies among the general cancer therapy.

Downregulation of TIGIT Expression in FOXP3+Regulatory T Cells in Acute Coronary Syndrome

Objective

Little is currently known on the role of T-cell immunoglobulin and ITIM domain (TIGIT) expression in Foxp3+ regulatory T cells (TIGIT+Tregs) in acute coronary syndrome (ACS) patients. The aim of this study was to investigate the role and alterations of TIGIT+Tregs in ACS patients.

Methods

We enrolled 117 subjects, including 61 ACS patients, 26 chronic coronary syndrome (CCS) patients, and 30 control subjects without coronary artery disease. The quantification of TIGIT+Tregs was determined by flow cytometry; serum interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) were also measured.

Results

TIGIT+Tregs expression was significantly lower in ACS patients compared with CCS and control patients (P<0.05). The expression of TIGIT+Tregs was comparable in patients with and without traditional risk factors (P>0.05). Logistic regression analysis revealed that TIGIT+Tregs levels are independent predictors of ACS (P<0.01). Receiver-operating characteristic (ROC) curve analysis showed the expression levels of TIGIT+Tregs had a discriminative power for ACS (P<0.01). IL-6 levels were increased (P<0.01), while TGF-β was decreased in ACS patients compared with CCS and control patients (P<0.01). Meanwhile, an inverse correlation between IL-6 and TIGIT+Tregs was observed (P<0.01), while a positive correlation between TGF-β and TIGIT+Tregs was found (P<0.05).

Conclusion

TIGIT+Tregs levels are significantly reduced in ACS, accompanied by upregulated IL-6 and downregulated TGF-β expression. The downregulated TIGIT+Tregs are independent predictors of ACS. These findings suggest that TIGIT+Tregs may have an anti-inflammatory and protective effect on ACS, and its decreased expression may be associated with atherosclerotic plaque destabilization.

Dose-dependent effects of oleuropein administration on regulatory T-cells in patients with rheumatoid arthritis: An in vitro approach

Introduction:

Rheumatoid arthritis (RA) is an autoimmune disease that is identified with chronic inflammation and progressive destruction of the joints. The defective activity of regulatory T cells (Tregs) plays a crucial role in RA development. Oleuropein (OLEU) is the most common polyphenolic compound in olive leaf extracts with numerous pharmacological activities. In this study, the potential effects of OLEU in shifting CD4⁺ T cells toward Tregs are evaluated in patients with RA.

Methods

32 healthy controls (HC) and 45 RA patients were included in two groups. The immunoturbidometric technique was used to measure serum levels of c-reactive protein (CRP) and rheumatoid factor (RF). Isolated CD4⁺ T cells from peripheral blood mononuclear cells (PBMCs) of HC and RA patients were cultured with appropriate concentrations of OLEU. The cytotoxicity effects of OLEU were determined using the MTT assay at 24, 48, and 72 h. The percentage of CD4⁺CD25 + FoxP3 regulatory T lymphocytes (Tregs) and the expressions of IL-10 and TGF-β were evaluated by flow cytometry and immunoassay techniques after treatment of cells with different concentrations of OLEU for 24 h. The serum levels of RF and CRP in patients with RA were 11.8 ± 5.32 IU/ml and 6.36 ± 5.82 mg/l, respectively.

Results

OLEU had a dose-dependent effect on the CD4⁺ T cells via increasing the frequency of CD4⁺CD25 + FoxP3 Tregs (p = 0.0001). Moreover, it induced the production of IL-10 (p = 0.0001) and TGF-β (p < 0.01) in both HC and RA patients.

Conclusion

The findings of this study suggest that OLEU may have immunomodulatory effects by inducing Tregs, and it might help in developing a novel nutrition strategy for management of autoimmune diseases such as RA.

Interleukin 10 and transforming growth factor-beta 1 plasma levels in atopic dogs before and during immunotherapy

BACKGROUND

Human studies suggest that the cytokines, interleukin 10 (IL-10) and transforming growth factor-beta 1 (TGF-ß1) may play an important role in allergen-specific immunotherapy (ASIT). However, there is little known about the function of these cytokines in atopic dogs. This study compared the plasma levels of IL-10 and TGF-ß1 in atopic and control dogs and investigated their changes during different ASIT approaches.

METHODS

A total of 54 atopic and 32 control dogs were included. Immunotherapy was performed in 30 atopic dogs. The dogs undergoing immunotherapy were allocated to four groups of different ASIT approaches (namely subcutaneous, intralymphatic, sublingual ASIT and subcutaneous ASIT with recombinant allergens). Blood samples were collected at four timepoints throughout the one year of ASIT. Canine atopic dermatitis extent and severity index, pruritus visual analogue scale and medication score were recorded at each timepoint. Commercially available ELISA kits were used to quantify IL-10 and TGF-ß1 in plasma.

RESULTS

There was no significant difference in IL-10 and TGF-ß1 between atopic and control dogs. The IL-10 levels were significantly increased in the intralymphatic group at the end of the study. No significant differences were found in the other groups for both IL-10 and TGF-ß1.

CONCLUSION

The findings of this work suggest that IL-10 and TGF-ß1 cannot be used to monitor the course of the disease during ASIT.

Regulatory T Cells in acute and chronic human Chikungunya infection

Chikungunya virus (CHIKV) infection generates strong immune responses that are associated with the disease pathophysiology. Regulatory T cells (Treg-cluster of differentiation (CD)-4⁺CD25^highforkhead box P3 (FOXP3⁺)) are essential for the induction and maintenance of peripheral tolerance. Thus, they play key roles in determining the patient prognosis by preventing excessive immune responses via different suppression immune mechanisms. However, the regulatory mechanisms involved in human CHIKV infection are still poorly understood. Here, we characterize for the first time the Treg cell molecule-associated-mechanism during acute and chronic human Chikungunya disease. Here, we assessed the Treg cell population and molecule-associated mechanism in the peripheral blood samples of acute and chronic patients with Chikungunya. Our results indicate that CHIKV infection is associated with reduced frequency of Tregs, along with the impaired expression and production of Treg functional markers, including CD39, CD73, perforin, granzyme, programmed death 1 (PD-1), cytotoxic T lymphocyte antigen (CTLA)-4, and transforming growth factor (TGF)-β. This observation suggests that Treg cells possess poor regulatory capacity in both acute and chronic phases of the disease. Taken together, these data provide significant evidence that the imbalanced response of Treg cells plays an essential role in establishing the pathogenesis of Chikungunya.

Successful Milk Oral Immunotherapy Promotes Generation of Casein-Specific CD137+ FOXP3+ Regulatory T Cells Detectable in Peripheral Blood

Background

Oral immunotherapy (OIT) is an emerging treatment for cow's milk protein (CMP) allergy in children. The mechanisms driving tolerance following OIT are not well understood. Regulatory T cells (T_REG) cells are key inhibitors of allergic responses and promoters of allergen-specific tolerance. In an exploratory study, we sought to detect induction of allergen-specific T_REG in a cohort of subjects undergoing OIT.

Methods

Pediatric patients with a history of allergic reaction to cow's milk and a positive Skin Pick Test (SPT) and/or CMP-specific IgE >0.35 kU, as well as a positive oral challenge to CMP underwent OIT with escalating doses of milk and were followed for up to 6 months. At specific milestones during the dose escalation and maintenance phases, casein-specific CD4⁺ T cells were expanded from patient blood by culturing unfractionated PBMCs with casein in vitro. The CD4⁺ T cell phenotypes were quantified by flow cytometry.

Results

Our culture system induced activated casein-specific FOXP3⁺Helios⁺ T_REG cells and FOXP3^- T_EFF cells, discriminated by expression of CD137 (4-1BB) and CD154 (CD40L) respectively. The frequency of casein-specific T_REG cells increased significantly with escalating doses of milk during OIT while casein-specific T_EFF cell frequencies remained constant. Moreover, expanded casein-specific T_REG cells expressed higher levels of FOXP3 compared to polyclonal T_REG cells, suggesting a more robust T_REG phenotype. The induction of casein-specific T_REG cells increased with successful CMP desensitization and correlated with increased frequencies of casein-specific Th1 cells among OIT subjects. The level of casein-specific T_REG cells negatively correlated with the time required to reach the maintenance phase of desensitization.

Conclusions

Overall, effective CMP-OIT successfully promoted the expansion of casein-specific, functionally-stable FOXP3⁺ T_REG cells while mitigating Th2 responses in children receiving OIT. Our exploratory study proposes that an in vitro T_REG response to casein may correlate with the time to reach maintenance in CMP-OIT.

Induction of CD4+ regulatory T cells by stimulation with Staphylococcal Enterotoxin C2 through different signaling pathways

As a member of superantigens, Staphylococcal Enterotoxin C2 (SEC2) can potently activate T cells expressing specific Vβ repertoires and has been applied in clinic for tumor immunotherapy in China for more than 20 years. However, excessive activation of T cells by over-stimulation with superantigen are always followed by eliciting regulatory T cells (Tregs) induction and functional immunosuppression, which brings uncertainties to SEC2 application in tumor immunotherapy. In this study, we found that SEC2 could induce CD4+CD25+Foxp3+ Tregs from the murine splenocytes in dose and time related manners. The induced Tregs with high expression of GITR and CTLA-4 and low expression of CD127 were TCR Vβ8.2-specific and have character of IL-10 production in a SEC2 dose-depended manner. Importantly, SEC2-induced CD4+ Tregs showed the potent capacity of suppressing proliferation of intact murine splenocytes response to SEC2. Furthermore, by using specific inhibitors or neutralizing antibody, we proved that the signaling pathways of TCR-NFAT/AP-1, IL-2-STAT5, and TGF-β-Smad3 play crucial roles in Tregs induction by SEC2. These findings will help us better understand the balance of immune stimulation and immunosuppression mediated by SEC2 and provide valuable guidance for SEC2 application in antitumor immunology.

T regulatory cells as a potential therapeutic target in psychosis? Current challenges and future perspectives

Many studies have reported that patients with psychosis, even before drug treatment, have mildly raised levels of blood cytokines relative to healthy controls. In contrast, there is a remarkable scarcity of studies investigating the cellular basis of immune function and cytokine changes in psychosis. The few flow-cytometry studies have been limited to counting the proportion of the major classes of monocyte and lymphocytes without distinguishing their pro- and anti-inflammatory subsets. Moreover, most of the investigations are cross-sectional and conducted with patients on long-term medication. These features make it difficult to eliminate confounding of illness-related changes by lifestyle factors, disease duration, and long exposure to antipsychotics. This article focuses on regulatory T cells (Tregs), cornerstone immune cells that regulate innate and adaptive immune forces and neuro-immune interactions between astrocytes and microglia. Tregs are also implicated in cardio-metabolic disorders that are common comorbidities of psychosis. We have recently proposed that Tregs are hypofunctional ('h-Tregs') in psychosis driven by our clinical findings and other independent research. Our h-Treg-glial imbalance hypothesis offers a new account for the co-occurrence of systemic immune dysregulation and mechanisms of psychosis development. This article extends our recent review, the h-Treg hypothesis, to cover new discoveries on Treg-based therapies from pre-clinical findings and their clinical implications. We provide a detailed characterisation of Treg studies in psychosis, identifying important methodological limitations and perspectives for scientific innovation. The outcomes presented in this article reaffirms our proposed h-Treg state in psychosis and reveals emerging preclinical research suggesting the potential benefit of Treg-enhancing therapies. There is a clear need for longitudinal studies conducted with drug-naïve or minimally treated patients using more sophisticated techniques of flow-cytometry, CyTOF expression markers, and in vitro co-culture assays to formally test the suppressive capacity of Tregs. Investment in Treg research offers major potential benefits in targeting emerging immunomodulatory treatment modalities on person-specific immune dysregulations.

Decoding the proregenerative competence of regulatory T cells through complex tissue regeneration in zebrafish

Regulatory T cells (T_regs ) are specific subtype of T cells that play a central role in sustaining self-antigen tolerance and restricting inflammatory tissue damage. More recently, additional direct functions of T_regs in mammalian tissue repair have emerged, but the regenerative potential of T_regs in non-mammalian vertebrates has not been explored despite the latter possessing a highly developed adaptive immune system. Why complex organs such as the caudal fin, heart, brain, spinal cord and retina regenerate in certain non-mammalian vertebrates, but not in mammals, is an interesting but unresolved question in the field of regenerative biology. Inflammation has traditionally been thought to be an impediment to regeneration due to the formation of scars. Regenerative decline in higher organisms has been speculated to be the evolutionary advent of adaptive immunity. Recent studies, however, have shown that the innate inflammatory response in non-mammalian organisms is required for organ regeneration. It has also been found that highly advanced adaptive immunity is no longer incompatible with regeneration and for that, T_regs are important. Zebrafish regulatory T cells (zT_regs ) migrate rapidly to the injury site in damaged organs, where they facilitate the proliferation of regeneration precursor cells by generating tissue-specific regenerative factors by a process distinct from the canonical anti-inflammatory pathway. We review both reparative and proregenerative roles of T_regs in mammals and zebrafish, respectively, and also give an overview of the forkhead box protein 3 (FoxP3) -dependent immunosuppressive function of T_regs in zebrafish, which makes it a useful model organism for future T_reg biology and research.

Epithelial cell-derived CD83 restores immune tolerance in the airway mucosa by inducing regulatory T-cell differentiation

The mechanism of generation of regulatory T cells (Treg) remains incompletely understood. Recent studies show that CD83 has immune regulatory functions. This study aims to investigate the role of epithelial cell-derived CD83 in the restoration of immune tolerance in the airway mucosa by inducing the Treg differentiation. In this study, CD83 and ovalbumin (OVA)-carrying exosomes were generated from airway epithelial cells. An airway allergy mouse model was developed to test the role of CD83/OVA-carrying exosomes in the suppression of airway allergy by inducing Treg generation. We observed that mouse airway epithelial cells expressed CD83 that could be up-regulated by CD40 ligand. The CD83 deficiency in epithelial cells retarded the Treg generation in the airway mucosa. CD83 up-regulated transforming growth factor-β-inducible early gene 1 expression in CD4+ T cells to promote Foxp3 expression. Exposure of primed CD4+ T cells to CD83/OVA-carrying exosomes promoted antigen-specific Treg generation. Administration of CD83/OVA-carrying exosomes inhibited experimental airway allergic response. In summary, airway epithelial cells express CD83 that is required in the Treg differentiation in the airway mucosa. Administration of CD83/OVA-carrying exosomes can inhibit airway allergy that has the translation potential in the treatment of airway allergic disorders.

Teaching tolerance: Diverse cellular interactions enable healthy maturation

The fetal immune system is distinguishable from the adult immune system by a higher degree of tolerance to foreign antigens. This tolerance is important for fetal development within the 'foreign' maternal environment, and during birth when barrier surfaces are first colonized by microbiota. Immune responses against the wave of newly colonizing microbiota would cause massive damage to barrier tissues, so neonates need suppressed immune responses and instead rely on maternal antibodies for protection. It is becoming clear that the early-life establishment of tolerance could impact immune homeostasis and predisposition to autoimmune diseases throughout life. However, it is not well understood how and when perinatal tolerogenic immune responses switch towards adult-like effector immune responses. Here, we present a new report on the differences between cells from perinatal umbilical cord blood (UCB) and adult peripheral blood mononuclear cells (PBMC), which give mechanistic insights into fetal tolerogenic responses.

X Chromosome Contribution to the Genetic Architecture of Primary Biliary Cholangitis

BACKGROUND & AIMS

Genome-wide association studies in primary biliary cholangitis (PBC) have failed to find X chromosome (chrX) variants associated with the disease. Here, we specifically explore the chrX contribution to PBC, a sexually dimorphic complex autoimmune disease.

METHODS

We performed a chrX-wide association study, including genotype data from 5 genome-wide association studies (from Italy, United Kingdom, Canada, China, and Japan; 5244 case patients and 11,875 control individuals).

RESULTS

Single-marker association analyses found approximately 100 loci displaying P < 5 × 10-4, with the most significant being a signal within the OTUD5 gene (rs3027490; P = 4.80 × 10-6; odds ratio [OR], 1.39; 95% confidence interval [CI], 1.028-1.88; Japanese cohort). Although the transethnic meta-analysis evidenced only a suggestive signal (rs2239452, mapping within the PIM2 gene; OR, 1.17; 95% CI, 1.09-1.26; P = 9.93 × 10-8), the population-specific meta-analysis showed a genome-wide significant locus in East Asian individuals pointing to the same region (rs7059064, mapping within the GRIPAP1 gene; P = 6.2 × 10-9; OR, 1.33; 95% CI, 1.21-1.46). Indeed, rs7059064 tags a unique linkage disequilibrium block including 7 genes: TIMM17B, PQBP1, PIM2, SLC35A2, OTUD5, KCND1, and GRIPAP1, as well as a superenhancer (GH0XJ048933 within OTUD5) targeting all these genes. GH0XJ048933 is also predicted to target FOXP3, the main T-regulatory cell lineage specification factor. Consistently, OTUD5 and FOXP3 RNA levels were up-regulated in PBC case patients (1.75- and 1.64-fold, respectively).

CONCLUSIONS

This work represents the first comprehensive study, to our knowledge, of the chrX contribution to the genetics of an autoimmune liver disease and shows a novel PBC-related genome-wide significant locus.

Adiponectin-expressing Treg facilitate T lymphocyte development in thymic nurse cell complexes

Adiponectin is a well-known insulin sensitizer and anti-inflammatory molecule, possessing therapeutic potentials in cardiovascular, metabolic and cancer diseases. Results of the present study demonstrate that adiponectin is expressed in a population of regulatory T-cells (Treg) resided within the thymic nurse cell (TNC) complexes. Adoptive transfer of adiponectin-expressing Treg precursors effectively attenuated obesity, improved glucose and insulin tolerance, prevented fatty liver injuries in wild-type mice fed a high-fat diet, and significantly inhibited breast cancer development in MMTV-PyVT transgenic mice. Within the TNC complexes, locally produced adiponectin bound to and regulated the expression as well as the distribution of CD100, a transmembrane lymphocyte semaphorin, in turn modulating the lymphoepithelial interactions to facilitate T-cell development and maturation. In summary, adiponectin plays an important role in the selection and development of T lymphocytes within the TNC complexes. Adiponectin-expressing Treg represent a promising candidate for adoptive cell immunotherapy against obesity-related metabolic and cancer diseases.

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.

The reptilian perspective on vertebrate immunity: 10 years of progress

Ten years ago, ‘Understanding the vertebrate immune system: insights from the reptilian perspective’ was published. At the time, our understanding of the reptilian immune system lagged behind that of birds, mammals, fish and amphibians. Since then, great progress has been made in elucidating the mechanisms of reptilian immunity. Here, I review recent discoveries associated with the recognition of pathogens, effector mechanisms and memory responses in reptiles. Moreover, I put forward key questions to drive the next 10 years of research, including how reptiles are able to balance robust innate mechanisms with avoiding self-damage, how B cells and antibodies are used in immune defense and whether innate mechanisms can display the hallmarks of memory. Finally, I briefly discuss the links between our mechanistic understanding of the reptilian immune system and the field of eco-immunology. Overall, the field of reptile immunology is poised to contribute greatly to our understanding of vertebrate immunity in the next 10 years.

Infection With Clostridioides difficile Attenuated Collagen-Induced Arthritis in Mice and Involved Mesenteric Treg and Th2 Polarization

Objectives

Rheumatoid arthritis is an autoimmune disease with multifactorial etiopathogenesis. Among the environmental factors, mucosal infections and the inducing pathobionts are gaining increasing attention. We here set out to explore the gut-joint-axis and the impact of Clostridioides difficile infection on subsequent arthritis.

Methods

We combined C. difficile infection in DBA/1J × B10.Q F1 mice with collagen induced arthritis (CIA). Mice were infected via oral gavage and infection was monitored by weight loss, colonic histology, and antibodies against bacteria. Scoring of arthritis was performed macroscopically. Intestinal microbiomes were analyzed and immune responses were monitored via quantification of transcription factor-specific mRNA isolated from the inguinal and mesenteric lymph nodes.

Results

Infection with C. difficile VPI 10463 resulted in significant weight loss and severe colitis yet accelerated the reversal towards the original microbiome after antibiotic treatment. Spontaneous clearance of VPI 10463 infection reduced the incidence of subsequent CIA and led to mesenteric T_reg and T_h2 polarization. However, this attenuating effect was abrogated if VPI 10463 was eradicated via vancomycin followed by fecal microbiota transplantation. Moreover, VPI 10463 infection following the onset of CIA lacked therapeutic potential.

Conclusion

Our results demonstrate that infection with C. difficile VPI10463 induced an inflammation of the gut that protected from subsequent arthritis development in mice. Both, microbial changes to the gut and immune cell mobilization and/or polarization may have contributed to arthritis protection. The prospect of potential therapeutic benefits resulting from C. difficile infections or some byproduct thereof call for further experiments that help elucidate exact mechanisms.

Equine Penile Squamous Cell Carcinomas as a Model for Human Disease: A Preliminary Investigation on Tumor Immune Microenvironment

Penile squamous cell carcinomas (SCCs) are common tumors in older horses, with poor prognosis mostly due to local invasion and recurrence. These tumors are thought to be mainly caused by Equus caballus papillomavirus type 2 (EcPV-2). The aim of this study is to characterize the tumor immune environment (TIME) in equine penile tumors. Equine penile epithelial tumors (17 epSCCs; 2 carcinomas in situ, CIS; 1 papilloma, P) were retrospectively selected; immune infiltrate was assessed by histology and immunohistochemistry; RT-qPCR tested the expression of selected chemokines and EcPV-2 DNA and RNA. The results confirmed EcPV-2-L1 DNA in 18/20 (90%) samples. L1 expression was instead retrieved in 13/20 cases (65%). The samples showed an increased infiltration of CD3⁺lymphocytes, macrophages (MAC387; IBA1), plasma cells (MUM1), and FoxP3⁺lymphocytes in the intra/peritumoral stroma when compared to extratumoral tissues (p < 0.05). Only MAC387⁺neutrophils were increased in EcPV-2^high viral load samples (p < 0.05). IL12/p35 was differentially expressed in EcPV^high and EcPV^low groups (p = 0.007). A significant decrease of IFNG and IL2 expression was highlighted in TGFB1-positive samples (p < 0.05). IBA1 and CD20 were intratumorally increased in cases where IL-10 was expressed (p < 0.005). EpSCCs may represent a good spontaneous model for the human counterpart. Further prospective studies are needed in order to confirm these preliminary results.

CCL18 in the Progression of Cancer

A neoplastic tumor consists of cancer cells that interact with each other and non-cancerous cells that support the development of the cancer. One such cell are tumor-associated macrophages (TAMs). These cells secrete many chemokines into the tumor microenvironment, including especially a large amount of CCL18. This chemokine is a marker of the M2 macrophage subset; this is the reason why an increase in the production of CCL18 is associated with the immunosuppressive nature of the tumor microenvironment and an important element of cancer immune evasion. Consequently, elevated levels of CCL18 in the serum and the tumor are connected with a worse prognosis for the patient. This paper shows the importance of CCL18 in neoplastic processes. It includes a description of the signal transduction from PITPNM3 in CCL18-dependent migration, invasion, and epithelial-to-mesenchymal transition (EMT) cancer cells. The importance of CCL18 in angiogenesis has also been described. The paper also describes the effect of CCL18 on the recruitment to the cancer niche and the functioning of cells such as TAMs, regulatory T cells (T_reg), cancer-associated fibroblasts (CAFs) and tumor-associated dendritic cells (TADCs). The last part of the paper describes the possibility of using CCL18 as a therapeutic target during anti-cancer therapy.

Increased Regulatory T Cells Precede the Development of Bronchopulmonary Dysplasia in Preterm Infants

Regulatory T cells (Tregs) are important for the ontogenetic control of immune activation and tissue damage in preterm infants. However, the role of Tregs for the development of bronchopulmonary dysplasia (BPD) is yet unclear. The aim of our study was to characterize CD4+ CD25+ forkhead box protein 3 (FoxP3)+ Tregs in peripheral blood of well-phenotyped preterm infants (n = 382; 23 + 0 – 36 + 6 weeks of gestational age) with a focus on the first 28 days of life and the clinical endpoint BPD (supplemental oxygen for longer than 28 days of age). In a subgroup of preterm infants, we characterized the immunological phenotype of Tregs (n = 23). The suppressive function of Tregs on CD4+CD25- T cells was compared in preterm, term and adult blood. We observed that extreme prematurity was associated with increased Treg frequencies which peaked in the second week of life. Independent of gestational age, increased Treg frequencies were noted to precede the development of BPD. The phenotype of preterm infant Tregs largely differed from adult Tregs and displayed an overall naïve Treg population (CD45RA+/HLA-DR-/Helios+), especially in the first days of life. On day 7 of life, a more activated Treg phenotype pattern (CCR6+, HLA-DR+, and Ki-67+) was observed. Tregs of preterm neonates had a higher immunosuppressive capacity against CD4+CD25- T cells compared to the Treg compartment of term neonates and adults. In conclusion, our data suggest increased frequencies and functions of Tregs in preterm neonates which display a distinct phenotype with dynamic changes in the first weeks of life. Hence, the continued abundance of Tregs may contribute to sustained inflammation preceding the development of BPD. Functional analyses are needed in order to elucidate whether Tregs have potential as future target for diagnostics and therapeutics.

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.

MCL-1 is essential for survival but dispensable for metabolic fitness of FOXP3+ regulatory T cells

FOXP3⁺ regulatory T (Treg) cells are essential for maintaining immunological tolerance. Given their importance in immune-related diseases, cancer and obesity, there is increasing interest in targeting the Treg cell compartment therapeutically. New pharmacological inhibitors that specifically target the prosurvival protein MCL-1 may provide this opportunity, as Treg cells are particularly reliant upon this protein. However, there are two distinct isoforms of MCL-1; one located at the outer mitochondrial membrane (OMM) that is required to antagonize apoptosis, and another at the inner mitochondrial membrane (IMM) that is reported to maintain IMM structure and metabolism via ATP production during oxidative phosphorylation. We set out to elucidate the relative importance of these distinct biological functions of MCL-1 in Treg cells to assess whether MCL-1 inhibition might impact upon the metabolism of cells able to resist apoptosis. Conditional deletion of Mcl1 in FOXP3⁺ Treg cells resulted in a lethal multiorgan autoimmunity due to the depletion of the Treg cell compartment. This striking phenotype was completely rescued by concomitant deletion of the apoptotic effector proteins BAK and BAX, indicating that apoptosis plays a pivotal role in the homeostasis of Treg cells. Notably, MCL-1-deficient Treg cells rescued from apoptosis displayed normal metabolic capacity. Moreover, pharmacological inhibition of MCL-1 in Treg cells resistant to apoptosis did not perturb their metabolic function. We conclude that Treg cells require MCL-1 only to antagonize apoptosis and not for metabolism. Therefore, MCL-1 inhibition could be used to manipulate Treg cell survival for clinical benefit without affecting the metabolic fitness of cells resisting apoptosis.

Gene editing to induce FOXP3 expression in human CD4+ T cells leads to a stable regulatory phenotype and function

Thymic regulatory T cells (tTregs) are potent inhibitors of autoreactive immune responses, and loss of tTreg function results in fatal autoimmune disease. Defects in tTreg number or function are also implicated in multiple autoimmune diseases, leading to growing interest in use of Treg as cell therapies to establish immune tolerance. Because tTregs are present at low numbers in circulating blood and may be challenging to purify and expand and also inherently defective in some subjects, we designed an alternative strategy to create autologous Treg-like cells from bulk CD4+ T cells. We used homology-directed repair (HDR)–based gene editing to enforce expression of FOXP3, the master transcription factor for tTreg. Targeted insertion of a robust enhancer/promoter proximal to the first coding exon bypassed epigenetic silencing, permitting stable and robust expression of endogenous FOXP3. HDR-edited T cells, edTregs, manifested a transcriptional program leading to sustained expression of canonical markers and suppressive activity of tTreg. Both human and murine edTregs mediated immunosuppression in vivo in models of inflammatory disease. Further, this engineering strategy permitted generation of antigen-specific edTreg with robust in vitro and in vivo functional activity. Last, edTreg could be enriched and expanded at scale using clinically relevant methods. Together, these findings suggest that edTreg production may permit broad future clinical application.

Tissue expression of IL-17A and FOXP3 in acne vulgaris patients

BACKGROUND/OBJECTIVES

CD4⁺  T helper (Th) cells through its pro-inflammatory cell type, interleukin-17 (IL-17)-generating cells and its anti-inflammatory category forkhead box P3-positive (FOXP3⁺ ) regulatory T (Treg) cells, play a vital role in the immune balance in inflammatory disorders. Therefore, assessment of both IL-17 and FOXP3 in acne vulgaris (AV), a chronic inflammatory disease of the pilosebaceous unit, could be of value in understanding AV pathogenesis. This study aimed to investigate the immunohistochemical expression of IL-17A and FOXP3 in acne vulgaris lesions versus normal skin.

METHODS

Forty-five AV patients and 25 controls were included in this case-control study. Biopsies from participants were analyzed for IL-17A and FOXP3 immunohistochemical profiles using IL-17A and FOXP3 polyclonal antibodies.

RESULTS

Compared to controls, AV patients exhibited a significant increase of IL-17A percent of expression in epidermis (P ≤ .001), in lymphocytes in papillary dermis (P ≤ .001), and in perifollicular lymphocytic inflammatory infiltrate in AV lesions. Also, there was a significant elevation in FOXP3 percent of expression in epidermis (P = .049) and in lymphocytes in papillary dermis (P ≤ .027) in acne patients than control. A significant positive correlation between IL-17A expression in papillary lymphocytes and in epidermal keratinocyte was observed (r = .537, P = .001). In acne vulgaris patients, the associations between IL-17A and FOXP3 expressions could not reach level of significance.

CONCLUSIONS

There was an up-regulation of IL-17A and FOXP3 in acne vulgaris development, but with independent roles. Moreover, targeting of IL-17A and FOXP3 may open the door for development of new therapeutic agents in acne vulgaris treatment.

Soluble epoxide hydrolase inhibitor, TPPU, increases regulatory T cells pathway in an arthritis model

Epoxyeicosatrienoic acids (EET) and related epoxy fatty acids (EpFA) are endogenous anti‐inflammatory compounds, which are converted by the soluble epoxide hydrolase (sEH) to dihydroxylethersatrienoic acids (DHETs) with lessened biological effects. Inhibition of sEH is used as a strategy to increase EET levels leading to lower inflammation. Rheumatoid arthritis is a chronic autoimmune disease that leads to destruction of joint tissues. This pathogenesis involves a complex interplay between the immune system, and environmental factors. Here, we investigate the effects of inhibiting sEH with 1‐trifluoromethoxyphenyl‐3‐(1‐propionylpiperidin‐4‐yl) urea (TPPU) on a collagen‐induced arthritis model. The treatment with TPPU ameliorates hyperalgesia, edema, and decreases the expression of important pro‐inflammatory cytokines of Th1 and Th17 profiles, while increasing Treg cells. Considering the challenges to control RA, this study provides robust data supporting that inhibition of the sEH is a promising target to treat arthritis.

Mechanisms of TREG cell adaptation to inflammation

Inflammation is an important defense mechanism. In this complex and dynamic process, drastic changes in the tissue micro-environment play key roles in dictating the nature of the evolving immune response. However, uncontrolled inflammation is detrimental, leading to unwanted cellular damage, loss of physiological functions, and even death. As such, the immune system possesses tools to limit inflammation while ensuring rapid and effective clearance of the inflammatory trigger. Foxp3⁺ regulatory T (T_REG ) cells, a potently immunosuppressive CD4⁺ T cell subset, play a crucial role in immune tolerance by controlling the extent of the response to self and non-self Ags, all-the-while promoting a quick return to immune homeostasis. T_REG cells adapt to changes in the local micro-environment enabling them to migrate, proliferate, survive, differentiate, and tailor their suppressive ability at inflamed sites. Several inflammation-associated factors can impact T_REG cell functional adaptation in situ including locally released alarmins, oxygen availability, tissue acidity and osmolarity and nutrient availability. Here, we review some of these key signals and pathways that control the adaptation of T_REG cell function in inflammatory settings.