The role of FOXP3+ regulatory T cells in human autoimmune and inflammatory diseases

Altered X-chromosome inactivation predisposes to autoimmunity

In mammals, males and females show marked differences in immune responses. Males are globally more sensitive to infectious diseases, while females are more susceptible to systemic autoimmunity. X-chromosome inactivation (XCI), the epigenetic mechanism ensuring the silencing of one X in females, may participate in these sex biases. We perturbed the expression of the trigger of XCI, the noncoding RNA Xist, in female mice. This resulted in reactivation of genes on the inactive X, including members of the Toll-like receptor 7 (TLR7) signaling pathway, in monocyte/macrophages and dendritic and B cells. Consequently, female mice spontaneously developed inflammatory signs typical of lupus, including anti-nucleic acid autoantibodies, increased frequencies of age-associated and germinal center B cells, and expansion of monocyte/macrophages and dendritic cells. Mechanistically, TLR7 signaling is dysregulated in macrophages, leading to sustained expression of target genes upon stimulation. These findings provide a direct link between maintenance of XCI and female-biased autoimmune manifestations and highlight altered XCI as a cause of autoimmunity.

Are Gender Differences Important for Autoimmune Liver Diseases?

Gender Medicine has had an enormous expansion over the last ten years. Autoimmune liver diseases include several conditions, i.e., autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and conditions involving the liver or biliary tree overlapping with AIH, as well as IgG4-related disease. However, little is known about the impact of sex in the pathogenesis and natural history of these conditions. The purpose of this review is to provide an update of the gender disparities among the autoimmune liver diseases by reviewing the data published from 1999 to 2023. The epidemiology of these diseases has been changing over the last years, due to the amelioration of knowledge in their diagnosis, pathogenesis, and treatment. The clinical data collected so far support the existence of sex differences in the natural history of autoimmune liver diseases. Notably, their history could be longer than that which is now known, with problems being initiated even at a pediatric age. Moreover, gender disparity has been observed during the onset of complications related to end-stage liver disease, including cancer incidence. However, there is still an important debate among researchers about the impact of sex and the pathogenesis of these conditions. With this review, we would like to emphasize the urgency of basic science and clinical research to increase our understanding of the sex differences in autoimmune liver diseases.

Sex differences in CD8+ T cell responses during adaptive immunity

Biological sex is an important variable that influences the immune system's susceptibility to infectious and non-infectious diseases and their outcomes. Sex dimorphic features in innate and adaptive immune cells and their activities may help to explain sex differences in immune responses. T lymphocytes in the adaptive immune system are essential to providing protection against infectious and chronic inflammatory diseases. In this review, T cell responses are discussed with focus on the current knowledge of biological sex differences in CD8+ T cell mediated adaptive immune responses in infectious and chronic inflammatory diseases. Future directions aimed at investigating the molecular and cellular mechanisms underlying sex differences in diverse T cell responses will continue to underscore the significance of understanding sex differences in protective immunity at the cellular level, to induce appropriate T cell-based immune responses in infection, autoimmunity, and cancer. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology.

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.

Targeting HIF-1α alleviates the inflammatory responses and rebuilds the CD4+ T cell subsets balance in the experimental autoimmune myasthenia gravis inflammation model via regulating cellular and humoral immunity

BACKGROUND

Cells and tissues in an inflammatory state are usually hypoxic. The hypoxic environment can affect the differentiation of immune cells and produce Hypoxia-inducible Factor-1α (HIF-1α). Inflammation is also a major contributor to the development and deterioration of Myasthenia Gravis (MG). There are limited studies on the immunopathological mechanism and targeted therapy associated with MG exacerbated with inflammation. This research aimed to explore whether BAY 87-2243 (HIF-1α inhibitor) ameliorates the symptoms of the Experimental Autoimmune Myasthenia Gravis (EAMG) inflammation model and study its regulatory mechanism on cellular immunity and humoral immunity.

METHODS

We first establish the EAMG inflammation model using Lipopolysaccharide (LPS), BAY 87-2243 was applied to the EAMG inflammation model and its therapeutic effects were evaluated in vivo and in vitro experiments.

RESULTS

The proportion of Treg cells was increased whereas Th1, Th17, and Th1/17 cells were decreased in BAY 87-2243-treated EAMG inflammation model. BAY 87-2243 ameliorated the acetylcholine receptors (AChRs) loss and the complement deposited at the neuromuscular junction of the EAMG inflammation model, declined the levels of IFN-γ, IL-17, and IL-6 in serum, and further attenuated responses in the germinal center and reduced the antibody levels by inhibiting the IL-6-dependent STAT3 axis.

CONCLUSION

BAY 87-2243 restored the balance of CD4+T cell subsets and reduced the production of the pro-inflammatory cytokines, thus acting as both an immune imbalance regulator and anti-inflammatory. The current study suggests that HIF-1α might be a potential target for the treatment of MG exacerbated with inflammation.

The Current Status and Future Direction of Extracellular Nano-vesicles in the Alleviation of Skin Disorders

Exosomes are extracellular vesicles (EVs) that originate from endocytic membranes. The transfer of biomolecules and biological compounds such as enzymes, proteins, RNA, lipids, and cellular waste disposal through exosomes plays an essential function in cell-cell communication and regulation of pathological and physiological processes in skin disease. The skin is one of the vital organs that makes up about 8% of the total body mass. This organ consists of three layers, epidermis, dermis, and hypodermis that cover the outer surface of the body. Heterogeneity and endogeneity of exosomes is an advantage that distinguishes them from nanoparticles and liposomes and leads to their widespread usage in the remedy of dermal diseases. The biocompatible nature of these extracellular vesicles has attracted the attention of many health researchers. In this review article, we will first discuss the biogenesis of exosomes, their contents, separation methods, and the advantages and disadvantages of exosomes. Then we will highlight recent developments related to the therapeutic applications of exosomes in the treatment of common skin disorders like atopic dermatitis, alopecia, epidermolysis bullosa, keloid, melanoma, psoriasis, and systemic sclerosis.

Hematopoietic cell-based and non-hematopoietic cell-based strategies for immune tolerance induction in living-donor renal transplantation: A systematic review

INTRODUCTION

Despite its use to prevent acute rejection, lifelong immunosuppression can adversely impact long-term patient and graft outcomes. In theory, immunosuppression withdrawal is the ultimate goal of kidney transplantation, and is made possible by the induction of immunological tolerance. The purpose of this paper is to review the safety and efficacy of immune tolerance induction strategies in living-donor kidney transplantation, both chimerism-based and non-chimerism-based. The impact of these strategies on transplant outcomes, including acute rejection, allograft function and survival, cost, and immune monitoring, will also be discussed.

MATERIALS AND METHODS

Databases such as PubMed, Scopus, and Web of Science, as well as additional online resources such as EBSCO, were exhaustively searched. Adult living-donor kidney transplant recipients who developed chimerism-based tolerance after concurrent bone marrow or hematopoietic stem cell transplantation or those who received non-chimerism-based, non-hematopoietic cell therapy using mesenchymal stromal cells, dendritic cells, or regulatory T cells were studied between 2000 and 2021. Individual sources of evidence were evaluated critically, and the strength of evidence and risk of bias for each outcome of the transplant tolerance study were assessed.

RESULTS

From 28,173 citations, 245 studies were retrieved after suitable exclusion and duplicate removal. Of these, 22 studies (2 RCTs, 11 cohort studies, 6 case-control studies, and 3 case reports) explicitly related to both interventions (chimerism- and non-chimerism-based immune tolerance) were used in the final review process and were critically appraised. According to the findings, chimerism-based strategies fostered immunotolerance, allowing for the safe withdrawal of immunosuppressive medications. Cell-based therapy, on the other hand, frequently did not induce tolerance except for minimising immunosuppression. As a result, the rejection rates, renal allograft function, and survival rates could not be directly compared between these two groups. While chimerism-based tolerance protocols posed safety concerns due to myelosuppression, including infections and graft-versus-host disease, cell-based strategies lacked these adverse effects and were largely safe. There was a lack of direct comparisons between HLA-identical and HLA-disparate recipients, and the cost implications were not examined in several of the retrieved studies. Most studies reported successful immunosuppressive weaning lasting at least 3 years (ranging up to 11.4 years in some studies), particularly with chimerism-based therapy, while only a few investigators used immune surveillance techniques. The studies reviewed were often limited by selection, classification, ascertainment, performance, and attrition bias.

CONCLUSIONS

This review demonstrates that chimerism-based hematopoietic strategies induce immune tolerance, and a substantial number of patients are successfully weaned off immunosuppression. Despite the risk of complications associated with myelosuppression. Non-chimerism-based, non-hematopoietic cell protocols, on the other hand, have been proven to facilitate immunosuppression minimization but seldom elicit immunological tolerance. However, the results of this review must be interpreted with caution because of the non-randomised study design, potential confounding, and small sample size of the included studies. Further validation and refinement of tolerogenic protocols in accordance with local practice preferences is also warranted, with an emphasis on patient selection, cost ramifications, and immunological surveillance based on reliable tolerance assays.

From aging to long COVID: exploring the convergence of immunosenescence, inflammaging, and autoimmunity

The process of aging is accompanied by a dynamic restructuring of the immune response, a phenomenon known as immunosenescence. This mini-review navigates through the complex landscape of age-associated immune changes, chronic inflammation, age-related autoimmune tendencies, and their potential links with immunopathology of Long COVID. Immunosenescence serves as an introductory departure point, elucidating alterations in immune cell profiles and their functional dynamics, changes in T-cell receptor signaling, cytokine network dysregulation, and compromised regulatory T-cell function. Subsequent scrutiny of chronic inflammation, or "inflammaging," highlights its roles in age-related autoimmune susceptibilities and its potential as a mediator of the immune perturbations observed in Long COVID patients. The introduction of epigenetic facets further amplifies the potential interconnections. In this compact review, we consider the dynamic interactions between immunosenescence, inflammation, and autoimmunity. We aim to explore the multifaceted relationships that link these processes and shed light on the underlying mechanisms that drive their interconnectedness. With a focus on understanding the immunological changes in the context of aging, we seek to provide insights into how immunosenescence and inflammation contribute to the emergence and progression of autoimmune disorders in the elderly and may serve as potential mediator for Long COVID disturbances.

Adjuvant physiochemistry and advanced nanotechnology for vaccine development

Vaccines comprising innovative adjuvants are rapidly reaching advanced translational stages, such as the authorized nanotechnology adjuvants in mRNA vaccines against COVID-19 worldwide, offering new strategies to effectively combat diseases threatening human health. Adjuvants are vital ingredients in vaccines, which can augment the degree, extensiveness, and longevity of antigen specific immune response. The advances in the modulation of physicochemical properties of nanoplatforms elevate the capability of adjuvants in initiating the innate immune system and adaptive immunity, offering immense potential for developing vaccines against hard-to-target infectious diseases and cancer. In this review, we provide an essential introduction of the basic principles of prophylactic and therapeutic vaccination, key roles of adjuvants in augmenting and shaping immunity to achieve desired outcomes and effectiveness, and the physiochemical properties and action mechanisms of clinically approved adjuvants for humans. We particularly focus on the preclinical and clinical progress of highly immunogenic emerging nanotechnology adjuvants formulated in vaccines for cancer treatment or infectious disease prevention. We deliberate on how the immune system can sense and respond to the physicochemical cues (e.g., chirality, deformability, solubility, topology, and chemical structures) of nanotechnology adjuvants incorporated in the vaccines. Finally, we propose possible strategies to accelerate the clinical implementation of nanotechnology adjuvanted vaccines, such as in-depth elucidation of nano-immuno interactions, antigen identification and optimization by the deployment of high-dimensional multiomics analysis approaches, encouraging close collaborations among scientists from different scientific disciplines and aggressive exploration of novel nanotechnologies.

Circulating Regulatory T Cell Subsets in Patients with Sarcoidosis

Over recent years, many researchers have supported the autoimmune theory of sarcoidosis. The presence of uncontrolled inflammatory response on local and system levels in patients with sarcoidosis did not define that the immunoregulatory mechanisms could be affected. The aim of this study was to evaluate the distribution and the disturbance circulating Treg cell subsets in the peripheral blood in patients with sarcoidosis.

MATERIALS AND METHODS

A prospective comparative study was performed in 2016-2018 (34 patients with sarcoidosis (men (67.6%), women (32.3%)) were examined). Healthy subjects-the control group (n = 40). The diagnosis of pulmonary sarcoidosis was performed according to the standard criteria. We used two ten-color combinations of antibodies for Treg immunophenotyping. The first one contained CD39-FITC, CD127-PE, CCR4-PE/Dazzle™ 594, CD25-PC5.5, CD161-PC7, CD4-APC, CD8-APC-AF700, CD3-APC/Cy7, HLA-DR-PacBlue, and CD45 RA-BV 510™, while the second consisted of CXCR3-Alexa Fluor 488, CD25-РЕ, CXCR5-РЕ/Dazzle™ 594, CCR4-PerСP/Сy5.5, CCR6-РЕ/Cy7, CD4-АPC, CD8 АPC-AF700, CD3-АPC/Cy7, CCR7-BV 421, and CD45 RA-BV 510. The flow cytometry data were analyzed by using Kaluza software v2.3. A statistical analysis was performed with Statistica 7.0 and GraphPad Prism 8 software packages.

RESULTS OF THE STUDY

Primarily, we found that patients with sarcoidosis had decreased absolute numbers of Treg cells in circulation. We noted that the level of CCR7-expressing Tregs decreased in patients with sarcoidosis vs. the control group (65.55% (60.08; 70.60) vs. 76.93% (69.59; 79.86) with p < 0.001). We noticed that the relative numbers of CD45RA-CCR7+ Tregs decreased in patients with sarcoidosis (27.11% vs. 35.43%, p < 0.001), while the frequency of CD45 RA-CCR7- and CD45RA+ CCR7- Tregs increased compared to the control group (33.3% vs. 22.73% and 0.76% vs. 0.51% with p < 0.001 and p = 0.028, respectively). CXCR3-expressing Treg cell subsets-Th1-like CCR60078CXCR3+ Tregs and Th17.1-like CCR6+ CXCR3+ Tregs-significantly increased in patients with sarcoidosis vs. the control group (14.4% vs. 10.5% with p < 0.01 and 27.9% vs. 22.8% with p < 0.01, respectively). Furthermore, the levels of peripheral blood EM Th17-like Tregs significantly decreased in the sarcoidosis group vs. the control group (36.38% vs. 46.70% with p < 0.001). Finally, we found that CXCR5 expression was increased in CM Tregs cell subsets in patients with sarcoidosis.

CONCLUSIONS

Our data indicated a decrease in circulating Tregs absolute numbers and several alterations in Treg cell subsets. Moreover, our results highlight the presence of increased levels of CM CXCR5+ follicular Tregs in the periphery that could be linked with the imbalance of follicular Th cell subsets and alterations in B cell, based on the immune response. The balance between the two functionally distinct Treg cell populations-Th1-like and Th17-like Tregs-could be used in sarcoidosis diagnosis and the determination of prognosis and disease outcomes. Furthermore, we want to declare that analysis of Treg numbers of phenotypes could fully characterize their functional activity in peripherally inflamed tissues.

Innate and adaptive immune abnormalities underlying autoimmune diseases: the genetic connections

With the exception of an extremely small number of cases caused by single gene mutations, most autoimmune diseases result from the complex interplay between environmental and genetic factors. In a nutshell, etiology of the common autoimmune disorders is unknown in spite of progress elucidating certain effector cells and molecules responsible for pathologies associated with inflammatory and tissue damage. In recent years, population genetics approaches have greatly enriched our knowledge regarding genetic susceptibility of autoimmunity, providing us with a window of opportunities to comprehensively re-examine autoimmunity-associated genes and possible pathways. In this review, we aim to discuss etiology and pathogenesis of common autoimmune disorders from the perspective of human genetics. An overview of the genetic basis of autoimmunity is followed by 3 chapters detailing susceptibility genes involved in innate immunity, adaptive immunity and inflammatory cell death processes respectively. With such attempts, we hope to expand the scope of thinking and bring attention to lesser appreciated molecules and pathways as important contributors of autoimmunity beyond the 'usual suspects' of a limited subset of validated therapeutic targets.

Regulatory T cells-centered regulatory networks of skeletal muscle inflammation and regeneration

As the understanding of skeletal muscle inflammation is increasingly clarified, the role of Treg cells in the treatment of skeletal muscle diseases has attracted more attention in recent years. A consensus has been reached that the regulation of Treg cells is the key to completing the switch of inflammation and repair of skeletal muscle, whose presence directly determine the repairing quality of the injured skeletal muscle. However, the functioning process of Treg cells remains unreported, thereby making it necessary to summarize the current role of Treg cells in skeletal muscle. In this review, the characteristics, origins, and cellular kinetics of these Treg cells are firstly described; Then, the relationship between Treg cells and muscle satellite cells (MuSCs), conventional T cells (Tconv) is discussed (the former is involved in the entire repair and regeneration process, while the latter matters considerably in causing most skeletal muscle autoimmune diseases); Next, focus is placed on the control of Treg cells on the phenotypic switch of macrophages, which is the key to the switch of inflammation; Finally, factors regulating the functional process of Treg cells are analyzed, and a regulatory network centered on Treg cells is summarized. The present study summarizes the cell-mediated interactions in skeletal muscle repair over the past decade, and elucidates the central role of regulatory T cells in this process, so that other researchers can more quickly and comprehensively understand the development and direction of this very field. It is believed that the hereby proposed viewpoints and problems can provide fresh visions for the latecomers.

Ginkgo biloba Extract Attenuates the Disruption of Pro- and Anti-inflammatory Balance of Peripheral Blood in Arsenism Patients by Decreasing Hypermethylation of the Foxp3 Promoter Region

Coal-burning type of arsenism, a chronic arsenism caused by environmental arsenic pollution, found firstly at Guizhou Province of China, manifested as the disruption of pro- and anti-inflammatory T cell balance and multiple organ damage, while no specific treatment for the arsenism patients. The effect of methylation of the forkhead box P3 (Foxp3) promoter region on arsenic-induced disruption of pro- and anti-inflammatory T cell balance was first evaluated in this study, between the control and arsenism groups. The results show that arsenic can induce the hypermethylation of 6 sites in the Foxp3 promoter by upregulating the expression of recombinant DNA Methyltransferase 1 (Dnmt1) mRNA, leading to the downregulation of Foxp3 mRNA, Tregs, and interleukin 10 (IL-10, anti-inflammatory cytokine) levels, and increased the levels of interleukin 17 (IL-17, pro-inflammatory cytokine) in the peripheral blood of patients with arsenic poisoning. Further randomized controlled double-blind experiments (including the placebo control groups and the Ginkgo biloba extract (GBE) intervention groups) showed that compared to the placebo control group or before GBE intervention, the levels of Dnmt1 mRNA, Foxp3 methylation, and IL-17 in the peripheral blood of the GBE intervention group were significantly decreased after intervention (P < 0.05), but the levels of regulatory T cells (Tregs) and IL-10 were significantly increased (P < 0.05). Our study provides some limited evidence that GBE can attenuate the disruption of pro- and anti-inflammatory balance of peripheral blood in arsenism patients by decreasing hypermethylation of the Foxp3 promoter region. This study provides scientific basis for further understanding a possible natural medicinal plant, GBE, as a more effective measure to prevent and control the disruption of pro- and anti-inflammatory balance caused by coal-burning type of arsenism.

Aplastic Anemia as a Roadmap for Bone Marrow Failure: An Overview and a Clinical Workflow

In recent years, it has become increasingly apparent that bone marrow (BM) failures and myeloid malignancy predisposition syndromes are characterized by a wide phenotypic spectrum and that these diseases must be considered in the differential diagnosis of children and adults with unexplained hematopoiesis defects. Clinically, hypocellular BM failure still represents a challenge in pathobiology-guided treatment. There are three fundamental topics that emerged from our review of the existing data. An exogenous stressor, an immune defect, and a constitutional genetic defect fuel a vicious cycle of hematopoietic stem cells, immune niches, and stroma compartments. A wide phenotypic spectrum exists for inherited and acquired BM failures and predispositions to myeloid malignancies. In order to effectively manage patients, it is crucial to establish the right diagnosis. New theragnostic windows can be revealed by exploring BM failure pathomechanisms.

Expression of IL-37 Induces a Regulatory T-Cell-like Phenotype and Function in Jurkat Cells

The anti-inflammatory cytokine interleukin-37 (IL-37) plays a key role in inhibiting innate and adaptive immunity. Past results have shown that IL-37 is elevated in human Treg cells compared to other T cell subsets and contributes to enhancing the Treg transcription factor, forkhead box protein P3 (FOXP3). However, it is unknown if ectopic expression of IL-37 in non-Treg CD4+ T cells can lead to the development of Treg phenotype and function. In the present study, we used a PrimeFlow® RNA assay and confirmed elevated IL37 expression in human Treg cells. We then stably transfected the non-Treg CD4+ T cell leukemia cell line, E6 Jurkat cells, with IL37 and found significant induction of the Treg phenotype. These IL-37-expressing Jurkat cells had elevated CTLA-4 and FOXP3 and produced IL-10. In conjunction with the Treg phenotype, IL-37-expressing Jurkat cells suppressed T cell activation/proliferation, comparable to human primary Treg cells. The creation of this stable human Treg-like cell line has the potential to provide further assistance for in vitro studies of human Treg cells, as it is more convenient than the use of primary human Treg cells. Furthermore, it provides insights into Treg cell biology and function.

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases II: Pathogens

In our continuing examination of the role of exposomes in autoimmune disease, we use this review to focus on pathogens. Infections are major contributors to the pathophysiology of autoimmune diseases through various mechanisms, foremost being molecular mimicry, when the structural similarity between the pathogen and a human tissue antigen leads to autoimmune reactivity and even autoimmune disease. The three best examples of this are oral pathogens, SARS-CoV-2, and the herpesviruses. Oral pathogens reach the gut, disturb the microbiota, increase gut permeability, cause local inflammation, and generate autoantigens, leading to systemic inflammation, multiple autoimmune reactivities, and systemic autoimmunity. The COVID-19 pandemic put the spotlight on SARS-CoV-2, which has been called “the autoimmune virus.” We explore in detail the evidence supporting this. We also describe how viruses, in particular herpesviruses, have a role in the induction of many different autoimmune diseases, detailing the various mechanisms involved. Lastly, we discuss the microbiome and the beneficial microbiota that populate it. We look at the role of the gut microbiome in autoimmune disorders, because of its role in regulating the immune system. Dysbiosis of the microbiota in the gut microbiome can lead to multiple autoimmune disorders. We conclude that understanding the precise roles and relationships shared by all these factors that comprise the exposome and identifying early events and root causes of these disorders can help us to develop more targeted therapeutic protocols for the management of this worldwide epidemic of autoimmunity.

Immunological Changes in Pregnancy and Prospects of Therapeutic Pla-Xosomes in Adverse Pregnancy Outcomes

Stringent balance of the immune system is a key regulatory factor in defining successful implantation, fetal development, and timely parturition. Interference in these primary regulatory mechanisms, either at adolescence or prenatal state led to adverse pregnancy outcomes. Fertility restoration with the help of injectable gonadotrophins/progesterone, ovulation-inducing drugs, immunomodulatory drugs (corticosteroids), and reproductive surgeries provides inadequate responses, which manifest its own side effects. The development of a potential diagnostic biomarker and an effectual treatment for adverse pregnancy outcomes is a prerequisite to maternal and child health. Parent cell originated bi-layered-intraluminal nano-vesicles (30-150 nm) also known as exosomes are detected in all types of bodily fluids like blood, saliva, breast milk, urine, etc. Exosomes being the most biological residual structures with the least cytotoxicity are loaded with cargo in the form of RNAs (miRNAs), proteins (cytokines), hormones (estrogen, progesterone, etc.), cDNAs, and metabolites making them chief molecules of cell-cell communication. Their keen involvement in the regulation of biological processes has portrayed them as the power shots of cues to understand the disease's pathophysiology and progression. Recent studies have demonstrated the role of immunexosomes (immunomodulating exosomes) in maintaining unwavering immune homeostasis between the mother and developing fetus for a healthy pregnancy. Moreover, the concentration and size of the exosomes are extensively studied in adverse pregnancies like preeclampsia, gestational diabetes mellitus (GDM), and preterm premature rupture of membrane (pPROMs) as an early diagnostic marker, thus giving in-depth information about their pathophysiology. Exosomes have also been engineered physically as well as genetically to enhance their encapsulation efficiency and specificity in therapy for cancer and adverse pregnancies. Successful bench to bedside discoveries and interventions in cancer has motivated developmental biologists to investigate the role of immunexosomes and their active components. Our review summarizes the pre-clinical studies for the use of these power-shots as therapeutic agents. We envisage that these studies will pave the path for the use of immunexosomes in clinical settings for reproductive problems that arise due to immune perturbance in homeostasis either at adolescence or prenatal state.

Study Design: HLA-A*02-Chimeric Antigen Receptor Regulatory T Cells in Renal Transplantation

Introduction

Cell therapy with regulatory T cells (Tregs) in solid organ transplantation is a promising approach for the prevention of graft rejection and induction of immunologic tolerance. Previous clinical studies have demonstrated the safety of Tregs in renal transplant recipients. Antigen-specific Tregs, such as chimeric antigen receptor (CAR)-Tregs, are expected to be more efficacious than polyclonal Tregs in homing to the target antigen. We have developed an autologous cell therapy (TX200-TR101) where a human leukocyte antigen (HLA) class I molecule A^∗02 (HLA-A^∗02)-CAR is introduced into autologous naive Tregs from a patient with HLA-A^∗02-negative end-stage renal disease (ESRD) awaiting an HLA-A^∗02-positive donor kidney.

Methods

This article describes the design of the STEADFAST study, a first-in-human, phase I/IIa, multicenter, open-label, single-ascending dose, dose-ranging study to assess TX200-TR101 in living-donor renal transplant recipients. Up to 15 transplant recipients will receive TX200-TR101 and will be followed up for a total of 84 weeks post-transplant, alongside a control cohort of up to 6 transplant recipients. All transplant recipients will receive a standard of care immunosuppressive regimen, with the intent of intensified tapering of the regimen in the TX200-TR101 cohort.

Results

The primary end point is the incidence and severity of treatment-emergent adverse events (AEs) within 28 days post–TX200-TR101 infusion. Other end points include additional safety parameters, clinical and renal outcome parameters, and the evaluation of biomarkers.

Conclusion

The STEADFAST study represents the next frontier in adoptive cell therapies. TX200-TR101 holds great potential to prevent immune-mediated graft rejection and induce immunologic tolerance after HLA-A^∗02-mismatched renal transplantation.

The aberrant expression of CD45 isoforms and levels of sex hormones in systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is a common autoimmune disease with significant gender bias in women, and sex hormones are considered to play an important role in the regulation of immune activity. The CD45 isoforms generated through alternative splicing of mRNA identify different functional status of lymphocytes and also are suggested as a biomarker for assessing the progression of SLE, while the modulation of CD45 expression in SLE patients is not clear.

METHODS

In this study, the peripheral blood sera of 46 SLE patients and 15 health individuals were collected for detecting the levels of sex hormones and immune associated factors. The expression of CD45 isoforms and the status of CD45 DNA methylation of the peripheral mononuclear blood cells were detected by flow cytometry and bisulfite sequencing PCR, respectively.

RESULTS

The levels of complement C3 and IgA decreased, especially decline of the serum IgA to the level of selective immunoglobulin A deficiency, and the C-reactive protein increased in SLE patients when compared with healthy controls, which manifested the abnormal immune activity of the SLE patients. Sex hormones detection showed a decreased testosterone and increased prolactin in SLE. An accelerated expression of CD45RO, reduced CD45RA and CD45RB, and a relative hypermethylation of CD45 DNA in SLE were also identified that provided a clue to explain the possible regulatory mechanism for the immune function in SLE.

CONCLUSION

The results indicated that the aberrant CD45 isoforms, DNA methylation and hormone levels might be correlated with the imbalanced immune activity of SLE patients. Key Points • Selective immunoglobulin A deficiency was significantly higher in SLE than in healthy individuals. • SLE patients had decreased testosterone and increased prolactin in the sera. • An aberrant expression of CD45 isoforms and CD45 DNA methylation were identified in SLE.

Altered Phenotype of Circulating Dendritic Cells and Regulatory T Cells from Patients with Acute Myocarditis

Dendritic cells (DCs) and regulatory T cells (Tregs) play an essential role in myocarditis. However, a particular DC phenotype in this disease has not been assessed. Herein, we aim to evaluate myeloid (mDCs) and plasmacytoid DC (pDC) phenotype, as well as Treg levels from myocarditis patients and healthy controls. Using multiparametric flow cytometry, we evaluated the levels of myeloid DCs (mDCs), plasmacytoid DCs (pDCs), and Tregs in peripheral blood from myocarditis patients (n = 16) and healthy volunteers (n = 16) and performed correlation analysis with clinical parameters through Sperman test. DCs from myocarditis patients showed a higher expression of costimulatory molecules while a diminished expression of the inhibitory receptors, ILT2 and ILT4. Even more, Treg cells from myocarditis patients displayed higher levels of FOXP3 compared to controls. Clinically, the increased levels of mDCs and their higher expression of costimulatory molecules correlate with a worse myocardial function, higher levels of acute phase reactants, and higher cardiac enzymes. This study shows an activating phenotype of circulating DCs from myocarditis patients. This proinflammatory status may contribute to the pathogenesis and immune deregulation in acute myocarditis.

Prolidase deficiency, a rare inborn error of immunity, clinical phenotypes, immunological features, and proposed treatments in twins

Background

Prolidase deficiency (PD) is an autosomal recessive inborn multisystemic disease caused by mutations in the PEPD gene encoding the enzyme prolidase D, leading to defects in turnover of proline-containing proteins, such as collagen. PD is categorized as a metabolic disease, but also as an inborn error of immunity. PD presents with a range of findings including dysmorphic features, intellectual disabilities, recurrent infections, intractable skin ulceration, autoimmunity, and splenomegaly. Despite symptoms of immune dysregulation, only very limited immunologic assessments have been reported and standard therapies for PD have not been described. We report twin females with PD, including comprehensive immunologic profiles and treatment modalities used.

Case presentation

Patient 1 had recurrent infections in childhood. At age 13, she presented with telangiectasia, followed by painful, refractory skin ulcerations on her lower limbs, where skin biopsy excluded vasculitis. She had typical dysmorphic features of PD. Next-generation sequencing revealed pathogenic compound heterozygous mutations (premature stop codons) in the PEPD gene. Patient 2 had the same mutations, typical PD facial features, atopy, and telangiectasias, but no skin ulceration. Both patients had imidodipeptiduria. Lymphocyte subset analysis revealed low-normal frequency of T_reg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4⁺ T_EM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17⁺ CD8⁺ T_EM cells in both patients and overexpression of the activation marker HLA-DR on CD4⁺ T_EM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4⁺CXCR5⁺ T_fh cells and low class-switched memory B cells. Plasma IL-18 levels were exceptionally high.

Conclusions

Immunologic abnormalities including skewed frequencies of activated inflammatory CD4⁺ and CD8⁺ T_EM cells, decreased CTLA-4 expression, and defects in memory B cells may be a feature of immune dysregulation associated with PD; however, a larger sample size is required to validate these findings. The high IL-18 plasma levels suggest underlying autoinflammatory processes.

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.

Emerging Roles of Myeloid-Derived Suppressor Cells in Diabetes

Diabetes is a syndrome characterized by hyperglycemia with or without insulin resistance. Its etiology is attributed to the combined action of genes, environment and immune cells. Myeloid-derived suppressor cell (MDSC) is a heterogeneous population of immature cells with immunosuppressive ability. In recent years, different studies have debated the quantity, activity changes and roles of MDSC in the diabetic microenvironment. However, the emerging roles of MDSC have not been fully documented with regard to their interactions with diabetes. Here, the manifestations of MDSC and their subsets are reviewed with regard to the incidence of diabetes and diabetic complications. The possible drugs targeting MDSC are discussed with regard to their potential of treating diabetes. We believe that understanding MDSC will offer opportunities to explain pathological characteristics of different diabetes. MDSC also will be used for personalized immunotherapy of diabetes.

Immunological Networks Defining the Heterogeneity of Inflammatory Bowel Diseases

Current practice in IBD is to classify patients based on clinical signs and symptoms and provide treatments accordingly. However, the response of IBD patients to available treatments is highly variable, highlighting clinically significant heterogeneity among patients. Thus, more accurate patient stratification is urgently needed to more effectively target therapeutic interventions to specific patients. Here we review the degree of heterogeneity in IBD, discussing how the microbiota, genetics, and immune system may contribute to the variation among patients. We highlight how molecular heterogeneity may relate to clinical phenotype, but in other situations may be independent of clinical phenotype, encouraging future studies to fill the gaps. Finally, we discuss novel stratification methodologies as a foundation for precision medicine, in particular a novel stratification strategy based on conserved genes across species. All of these dimensions of heterogeneity have potential to provide strategies for patient stratification and move IBD practice towards personalised medicine.

Deregulation of circ_003912 contributes to pathogenesis of erosive oral lichen planus by via sponging microRNA-123, -647 and -31 and upregulating FOXP3

Background

The FOXP3/miR-146a/NF-κB axis was previously reported to modulate the induction and function of CD4+ Treg cells to alleviate oral lichen planus. Also, other signaling pathways including microRNA-155-IFN-γ loop and FOXP3/miR-146a/TRAF6 pathways were reported to be involved in the pathogenesis of oral lichen planus. In this study, we aimed to investigate the molecular mechanism underlying the pathogenesis of EOLP.

Method

CircRNA microarray was used to observe the expression of candidate circRNAs in CD4+ T-cells collected from different groups. Real-time PCR and Western blot were conducted to observe the changes in the expression of different miRNAs, mRNAs and proteins. Flow cytometry was performed to compare the counts of Treg cells in the HC and EOLP groups, and ELISA was performed to evaluate the changes in the expression of inflammatory cytokines.

Result

No obvious differences were seen between the HC and EOLP groups in terms of age and gender. Among all candidate circRNAs, the expression of circ_003912 was most dramatically elevated in CD4+ T-cells collected from the EOLP group. The levels of miR-1231, miR-31, miR-647, FOXP3 mRNA and miR-146a were decreased while the expression of TRAF6 mRNA was increased in CD4+ T-cells collected from the EOLP group. The count of Treg cells in the EOLP group was dramatically increased. The levels of inflammatory cytokines including IL-4 IFN-γ, IL-10 and IL-2 were influenced by the presence of circ_003912. In CD4+ T-cells in the EOLP group, the levels of IL-4 and IL-10 were decreased while the levels of IFN-γ and IL-2 were increased. The presence of miR-1231, miR-31 and miR-647 all obviously inhibited the expression of circ_003912, which was validated to sponge the expression of above miRNAs. Also, FOXP3 mRNA was proved to be targeted by miR-1231, miR-31 and miR-647. Transfection of circ_003912 up-regulated the expression of circ_003912, miR-146a and FOXP3 mRNA/protein while down-regulating the expression of miR-1231, miR-31, miR-647, and TRAF6 mRNA/protein. The levels of inflammatory cytokines including IL-4 IFN-γ, IL-10 and IL-2 as well as the speed of cell proliferation were influenced by circ_003912.

Conclusion

In this study, we investigated the molecular mechanisms underlying the pathogenesis of EOLP which involved the functioning of circ_003912. We first demonstrated that circ_003912 was up-regulated in CD4+ T-cells of the EOLP group. And miRNAs including miR-1231, miR-31 and miR-647 were sponged by circ_003912 and down-regulated in CD4+ T cells of the EOLP group, which subsequently up-regulated the expression of FOXP3 and miR-146a, and resulted in the inhibition of NF-kB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00382-4.

Glucose Metabolism Reprogramming of Regulatory T Cells in Concanavalin A-Induced Hepatitis

Autoimmune hepatitis (AIH) is an inflammatory liver disease caused by a dysregulated immune response. Although the pathogenesis of AIH remains unclear, impaired regulatory T cells (Tregs) have been considered a driver of AIH development. Unlike autoreactive T cells, Tregs mainly utilize oxidative phosphorylation (OXPHOS) as their energy supply. Elevated glycolysis has been reported to limit the suppressive functions of Tregs. However, whether glucose metabolism reprogramming in Tregs is involved in AIH etiology remains unknown. The aim of this study was to examine alternations in Treg numbers and functions in AIH patients and concanavalin A (Con A)-induced hepatitis, while exploring associations between impaired Tregs and glucose metabolism. The frequency of Tregs was decreased in the peripheral blood but increased in liver biopsies of AIH patients. Moreover, immunosuppressive therapy rescued circulating Tregs in AIH. In Con A-induced immune hepatitis, enhanced intrahepatic Treg accumulation was observed over time, accompanied by reduced splenic Treg numbers. To investigate whether functional impairment of Tregs occurs in AIH, Tregs were isolated from experimental AIH (EAH) model mice and normal controls and the former displayed downregulated mRNA levels of FOXP3, CTLA4, CD103, TIGIT, CD39, and CD73. EAH model-derived Tregs also produced fewer anti-inflammatory mediators (TGF-β and IL-35) than control Tregs. Moreover, enhanced glycolysis and reduced OXPHOS were found in Tregs from EAH model mice, as reflected by elevated levels of key glycolytic enzymes (HK2, PK-M2, and LDH-A) and a decreased ATP concentration. This study revealed a decreased peripheral Treg frequency and abnormal intrahepatic Treg infiltration in AIH. It is first reported that glucose metabolism reprogramming is associated with decreases and functional impairments in the Treg population, promoting AIH development. Targeting glucose metabolism may provide novel insights for the treatment of AIH.

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.

Functional Role of miR-155 in the Pathogenesis of Diabetes Mellitus and Its Complications

Substantial evidence indicates that microRNA-155 (miR-155) plays a crucial role in the pathogenesis of diabetes mellitus (DM) and its complications. A number of clinical studies reported low serum levels of miR-155 in patients with type 2 diabetes (T2D). Preclinical studies revealed that miR-155 partakes in the phenotypic switch of cells within the islets of Langerhans under metabolic stress. Moreover, miR-155 was shown to regulate insulin sensitivity in liver, adipose tissue, and skeletal muscle. Dysregulation of miR-155 expression was also shown to predict the development of nephropathy, neuropathy, and retinopathy in DM. Here, we systematically describe the reports investigating the role of miR-155 in DM and its complications. We also discuss the recent results from in vivo and in vitro models of type 1 diabetes (T1D) and T2D, discussing the differences between clinical and preclinical studies and shedding light on the molecular pathways mediated by miR-155 in different tissues affected by DM.

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.

Biological functions of IL-17-producing cells in mycoplasma respiratory infection

Mycoplasmas are the smallest and simplest bacteria that lack a cell wall but have the capability of self-replication. Among them, Mycoplasma pneumoniae is one of the most common causes of community-acquired pneumonia. The hallmark of mycoplasma respiratory diseases is the persistence of lung inflammation that involves both innate and adaptive immune responses. In recent years, a growing body of evidence demonstrates that IL-17 plays an important role in respiratory mycoplasma infection, and associates with the pathologic outcomes of infection, such as pneumonitis and asthma. Numerous studies have shown that a variety of cells, in particular Th17 cells, in the lung can secrete IL-17 during respiratory mycoplasma infection. In this article, we review the biological functions of distinct IL-17-producing cells in mycoplasma respiratory infection with a focus on the effect of IL-17 on the outcomes of infection.

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.

Protective Effect of the α7 Nicotinic Receptor Agonist PNU-282987 on Dopaminergic Neurons Against 6-Hydroxydopamine, Regulating Anti-neuroinflammatory and the Immune Balance Pathways in Rat

Neuroinflammation and inner immune dysfunction are increasingly accepted as important components of the etiopathogenesis of Parkinson’s disease (PD). According to emerging evidence, a7 nicotinic acetylcholine receptor (α7nAChR), a ligand-gated ion channel, plays an important role in inflammatory reactions and is also expressed on the surface of T cells. In particular, regulatory T cells (Tregs) are critical for the maintenance of immunological tolerance. In the present study, we investigated the roles of α7nAChR in inhibiting inflammation and maintaining the immune balance in rats with 6-hydroxydopamine (6-OHDA)-induced lesions and the possible mechanisms regulating the proportion of Tregs in vivo. Adult male Wistar rats (n = 90) were subjected to a unilateral injection of 6-OHDA into the left medial forebrain bundle, and PNU-282987, an α7nAChR agonist, was intraperitoneally injected 2 h prior to the induction of lesions by 6-OHDA and again at days 1, 7, and 13 postlesion. Behavioral tests and immunohistochemical staining to detect the expression of tyrosine hydroxylase (TH) in the bilateral substantial nigra (SN) were performed. Subsequently, CD4+ T lymphocytes and the expression of forkhead/winged helix transcription factor p3 (Foxp3, which is a marker of Treg cells) in the SN were also assessed using immunofluorescence staining. The expression of glial fibrillary acidic protein (GFAP) in the SN was determined by performing immunohistochemical staining. Additionally, the protein levels of α7nAChR, extracellular signal-regulated kinase (Erk) phosphorylated-Erk (p-Erk) and Foxp3 in the ventral midbrain were determined using Western blotting, and the relative expression of the TNF-α, IL-1β, and IL-10 mRNAs were detected using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). We found that PNU-282987 significantly improved the motor deficits induced by 6-OHDA, reduced the loss of TH in the SN, suppressed the overactivation of GFAP+ cells and expression of related inflammatory cytokines, and increased the number of Foxp3+ cells. In addition, we also showed that PNU-282987 significantly increased the protein expression of the a7nAchR, p-Erk, and Foxp3 in 6-OHDA-lesioned rats (p < 0.05). These results indicated that α7nAChR activation could exert an anti-inflammatory effect and participate in the process of modulating the immune balance during 6-OHDA-induced injury, potentially through the α7nAChR/p-Erk/Foxp3 signaling pathway.

The Effect of Age on T-Regulatory Cell Number and Function in Patients With Asthma

T-regulatory cells (Tregs) play a key role in suppressing effector cells and maintaining self-tolerance. Studies of younger adults and children suggest that insufficient differentiation and functional defects of Tregs may contribute to the development of asthma; however, data from older patients with asthma are limited. To address the effects of aging on the relationship of Treg frequency and function with clinical outcomes, we collected induced sputum (differential cell count and Treg frequency) and peripheral blood (Treg function and frequency) from aged (> 60 years of age) and younger (20–40 years old) patients with asthma. In younger patients, low Treg suppression was associated with significantly higher mean numbers of emergency department (ED) (1.8 vs. 0.17, P = 0.02) and urgent care visits (2.3 vs. 0.17, P = 0.01) for asthma, and decreased asthma control (mean Asthma Control Test [ACT] score, 17 vs. 21.3, P = 0.01) compared to those with high Treg suppression. In older patients, however, a lower Treg function was not significantly associated with ACT scores (18.2 vs. 13.4, P = 0.10), or the number of ED (P = 0.9) or urgent care visits (P = 0.2). Our data suggest that Tregs have a weak relationship with asthma control and clinical asthma outcomes in older patients and differ from findings in younger patients, where Tregs are more likely to play a protective role.

Regulatory T Cells: Concept, Classification, Phenotype, and Biological Characteristics

Regulatory T cells (Treg) play an indispensable role in maintaining the body's immune nonresponse to self-antigens and suppressing the body's unwarranted and potentially harmful immune responses. Their absence, reduction, dysfunction, transformation, and instability can lead to numerous autoimmune diseases. There are several distinct subtypes of the Treg cells, although they share certain biological characteristics and have unique phenotypes with different regulatory functions, as well as mechanistic abilities. In this book chapter, we introduce the latest advances in Treg cell subtypes pertaining to classification, phenotype, biological characteristics, and mechanisms. We also highlight the relationship between Treg cells and various diseases, including autoimmune, infectious, as well as tumors and organ transplants.

Breakdown of T-cell ignorance: The tolerance failure responsible for mainstream autoimmune diseases?

This article explores the possibility that the major autoimmune diseases come about because of the breakdown of T lymphocyte ignorance – that state in which antigen and lymphocyte have never come together in such a way as to induce tolerance or an immune response. By use of transgenic technique to place a foreign antigen/peptide in various mouse tissues the widespread occurrence of ignorance has been observed and information obtained on when it is likely to occur. Now, with the advent of tetramer technique to enrich specific T cells and the recognition of lymphocyte markers indicating whether or not antigen interaction has taken place, ignorance of genuine self-antigens is being examined in mouse and man. In the absence of thymic deletion it seems that tolerance to self-antigens is brought about either by T cell ignorance or T cell regulatory control. The initiating factor in these major diseases is likely to be a change in the condition of the antigen leading to tolerance failure. There is evidence that it is ignorance that breaks down in Type 1 diabetes and systemic lupus erythematosus. If this proves a general rule, it may be because ignorance is the tolerance mechanism most vulnerable to subversion.

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T cell ignorance or regulation maintain self-tolerance when thymic deletion is absent.

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Increased antigen availability is the likely initiator of major autoimmune diseases.

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Altered antigen availability may result in breakdown of T cell ignorance.

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Loss of ignorance will lead to autoimmune disease unless T cell regulation steps in.

Role of the adaptive immune system in atherosclerosis

Atherosclerosis, the pathology underlying heart attacks, strokes and peripheral artery disease, is a chronic inflammatory disease of the artery wall initiated by elevated low-density lipoprotein (LDL) cholesterol levels. LDL accumulates in the artery wall, where it can become oxidized to oxLDL. T cell responses to ApoB, a core protein found in LDL and other lipoproteins, are detectable in healthy mice and people. Most of the ApoB-specific CD4T cells are FoxP3+ regulatory T cells (Treg). In the course of atherosclerosis development, the number of ApoB-reactive T cells expands. At the same time, their phenotype changes, showing cell surface markers, transcription factors and transcriptomes resembling other T-helper lineages like Th17, Th1 and follicular helper (TFH) cells. TFH cells enter germinal centers and provide T cell help to B cells, enabling antibody isotype switch from IgM to IgG and supporting affinity maturation. In people and mice with atherosclerosis, IgG and IgM antibodies to oxLDL are detectable. Higher IgM antibody titers to oxLDL are associated with less, IgG antibodies with more atherosclerosis. Thus, both T and B cells play critical roles in atherosclerosis. Modifying the adaptive immune response to ApoB holds promise for preventing atherosclerosis and reducing disease burden.

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.

Low-Zone IL-2 Signaling: Fusion Proteins Containing Linked CD25 and IL-2 Domains Sustain Tolerogenic Vaccination in vivo and Promote Dominance of FOXP3+ Tregs in vitro

Low-zone IL-2 signaling is key to understanding how CD4⁺ CD25^high FOXP3⁺ regulatory T cells (Tregs) exhibit dominance and overgrow conventional effector T cells (Tcons) that typically express lower levels of the IL-2 receptor alpha chain (i.e., CD25). Thus, modalities such as low-dose IL-2 or IL-2/anti-IL-2 antibody complexes have been advanced in the clinic to selectively expand Treg populations as a treatment for chronic inflammatory autoimmune diseases. However, more effective reagents that efficiently lock IL-2 signaling into a low signaling mode are needed to validate and exploit the low-zone IL-2 signaling niche of Tregs. This study focuses on CD25-IL2 and IL2-CD25 fusion proteins (FPs) that were approximately 32 and 320-fold less potent than IL-2. These FPs exhibited transient binding to transmembrane CD25 on human embryonic kidney (HEK) cells, had partially occluded IL-2 binding sites, and formed higher order multimeric conformers that limited the availability of bioactive IL-2. These FPs exhibited broad bell-shaped concentration ranges that favored dominant Treg outgrowth during continuous culture and were used to derive essentially pure long-term Treg monocultures (∼98% Treg purity). FP-induced Tregs had canonical Treg suppressive activity in that these Tregs suppressed antigen-specific proliferative responses of naïve CD4⁺ T cells. The in vivo administration of CD25-IL2/Alum elicited robust increases in circulating Tregs and selectively augmented CD25 expression on Tregs but not on Tcons. A single injection of a Myelin Oligodendrocyte Glycoprotein (MOG35-55)-specific tolerogenic vaccine elicited high levels of circulating MOG-specific Tregs in vivo that waned after 2–3 weeks, whereas boosting with CD25-IL2/Alum maintained MOG-specific CD25^high Tregs throughout the 30-day observation period. However, these FPs did not antagonize free monomeric IL-2 and lacked therapeutic efficacy in experimental autoimmune encephalomyelitis (EAE). In conclusion, these data reveal that CD25-IL2 FPs can be used to select essentially pure long-term lines of FOXP3⁺ CD25^high Tregs. This study also shows that CD25-IL2 FPs can be administered in vivo in synergy with tolerogenic vaccination to maintain high circulating levels of antigen-specific Tregs. Because tolerogenic vaccination and Treg-based adoptive immunotherapy are limited by gradual waning of Tregs, these FPs have potential utility in sustaining tolerogenic Treg responses in vivo.

Human mesenchymal stem cell-derived exosomes accelerate wound healing of mice eczema

INTRODUCTION

The aim of our study was to investigate the therapeutic effect of Mesenchymal stem cell-derived exosomes (MSC-exs) on eczema mice model.

METHODS

Eczema mice were established by 2, 4-two nitrochlorobenzene. Human umbilical cords cells and exosomes were harvested. In eczema mice model, the effect of MSC-ex on eczema was evaluated by severity score, atopic dermatitis score and histopathological analysis of dermis. MTT tests were performed to assess PBMC proliferation. Treg was identified by flow cytometry. The angiogenesis was analyzed by endothelial cell tube formation assay.

RESULTS

Compared with PBS, the wound closure of animals treated with MSC-exs was faster. After MSC-exs treatment, there were more new epidermis and dermis, and less scar formation of the lesion. There were significant differences in the integral score of skin injury and the number of lymphocyte infiltration in the skin between the treatment group and the PBS group (p < .01). MSC-exs significantly inhibit Peripheral blood mononuclear cell proliferation, promote the transformation of Treg and the formation of endothelial tube.

CONCLUSION

MSC-ex accelerated wounds healing in mice eczema model by inhibiting inflammatory cell infiltration and promoting vascular formation.

Tolerogenic vaccines: Targeting the antigenic and cytokine niches of FOXP3+ regulatory T cells

FOXP3+ regulatory T cells (Tregs) constitute a critical barrier that enforces tolerance to both the self-peptidome and the extended-self peptidome to ensure tissue-specific resistance to autoimmune, allergic, and other inflammatory disorders. Here, we review intuitive models regarding how T cell antigen receptor (TCR) specificity and antigen recognition efficiency shape the Treg and conventional T cell (Tcon) repertoires to adaptively regulate T cell maintenance, tissue-residency, phenotypic stability, and immune function in peripheral tissues. Three zones of TCR recognition efficiency are considered, including Tcon recognition of specific low-efficiency self MHC-ligands, Treg recognition of intermediate-efficiency agonistic self MHC-ligands, and Tcon recognition of cross-reactive high-efficiency agonistic foreign MHC-ligands. These respective zones of TCR recognition efficiency are key to understanding how tissue-resident immune networks integrate the antigenic complexity of local environments to provide adaptive decisions setting the balance of suppressive and immunogenic responses. Importantly, deficiencies in the Treg repertoire appear to be an important cause of chronic inflammatory disease. Deficiencies may include global deficiencies in Treg numbers or function, subtle 'holes in the Treg repertoire' in tissue-resident Treg populations, or simply Treg insufficiencies that are unable to counter an overwhelming molecular mimicry stimulus. Tolerogenic vaccination and Treg-based immunotherapy are two therapeutic modalities meant to restore dominance of Treg networks to reverse chronic inflammatory disease. Studies of these therapeutic modalities in a preclinical setting have provided insight into the Treg niche, including the concept that intermediate-efficiency TCR signaling, high IFN-β concentrations, and low IL-2 concentrations favor Treg responses and active dominant mechanisms of immune tolerance. Overall, the purpose here is to assimilate new and established concepts regarding how cognate TCR specificity of the Treg repertoire and the contingent cytokine networks provide a foundation for understanding Treg suppressive strategy.

FOXP3 promotes colorectal carcinoma liver metastases by evaluating MMP9 expression via regulating S-adenosylmethionine metabolism

Background

Growing evidence has proved that Forkhead box protein 3 (FOXP3), which is a master regulatory gene in the development and function of regulatory T-cells, is expressed in human cancer cells. This expression indicates the crucial role FOXP3 takes up as the disease progresses. However, its role in colorectal cancer (CRC) liver metastasis is still mostly unknown. This study set out to explore the molecular characteristics of FOXP3 in driving the liver metastasis within CRC.

Methods

We downloaded the RNA-seq data from the GSE50760. Weighted gene co-expression network analysis (WGCNA)WGCNA and RNA-Seq analysis were applied to find the key gene network associated with colorectal cancer liver metastasis. Then we performed pathway enrichment analysis on liver metastasis-associated gene set. Immunohistochemistry, in vitro and in vivo studies were conducted to test expression and function of FOXP3 in CRC tissues and liver metastasis tissues. Non-targeted metabolomics analysis was performed to identify the alteration of FOXP3 expression in metabolites of colorectal cancer liver metastasis. Western blot was performed to confirm changes of matrix metalloproteinase 9MMP9 expression were downstream events of S-adenosyl-methionine (SAM).

Results

We found that FOXP3 and MMP9 exhibited co-expression relationships and affected liver metastasis in CRC. Upregulation of FOXP3 promotes cell migration and invasion in CRC, which suggests a pro-cancer effect. Moreover, metabolomics analysis showed that knockdown of FOXP3 significantly reduced SAM levels, and changes of MMP9 expression were downstream events of SAM, which is concentration-dependent. Besides, The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Western blot analysis confirmed that overexpression of FOXP3 activates the Wnt pathway to promote colon cancer metastasis.

Conclusions

Our results altogether suggested that FOXP3 expression inhibited the SAM cycle to reduce SAMe levels, resulting in altered MMP9 expression and helped CRC liver metastasis.

Tissue Infiltrating LTi-Like Group 3 Innate Lymphoid Cells and T Follicular Helper Cells in Graves' and Hashimoto's Thyroiditis

Background: Hashimoto's thyroiditis (HT) and Graves' disease (GD) are autoimmune thyroid disorders (AITDs). These conditions have been associated to abnormalities in circulating regulatory T cells (Tregs). We postulated that immune perturbations could be more pronounced at the thyroid tissue level.

Methods: The phenotype of PBMCs and immune cells infiltrating thyroid tissue from 19 patients with HT, 21 patients with GD, and 30 controls has been analyzed by flow cytometry.

Results: We report that blood and thyroid Treg cell subsets are similarly represented in all AITDs patients and controls. Increased Lymphoid tissue inducer (LTi)-like ILC3 and CXCR5⁺ PD-1^hi CD4⁺ T follicular helper cells (Tfh) tissue-infiltrating cells, together with the prevalence of tertiary lymphoid structures (TLS) and germinal centers (GCs) represented a typical immune signature in all HT and 60% of GD patients. In the remaining group of GD patients, the absence of the aforementioned abnormalities was associated with a higher prevalence of ophthalmopathy.

Conclusion: Tissue infiltrating Lymphoid Tissue inducer—like group 3 Innate Lymphoid cells and T follicular helper cells are increased in most thyroid autoimmune disease.

Regulatory T cells in solid organ transplantation

The induction of graft tolerance remains the holy grail of transplantation. This is important as chronic allograft dysfunction and the side effects of immunosuppression regimens place a major burden on the lives of transplant patients and their healthcare systems. This has mandated the need to understand the immunobiology of graft rejection and identify novel therapeutics. Regulatory T (Treg) cells play an important role in modulating pro‐inflammatory microenvironments and maintaining tissue homeostasis. However, there are fundamental unanswered questions regarding Treg cell immunobiology. These cells are a heterogeneous entity with functionally diverse roles. Moreover, the adoption of novel deeper immunophenotyping and genomic sequencing technologies has identified this phenotype and function to be more complex than expected. Hence, a comprehensive understanding of Treg cell heterogeneity is needed to safely and effectively exploit their therapeutic potential. From a clinical perspective, the recent decade has seen different clinical teams commence and complete first‐in‐man clinical trials utilising Treg cells as an adoptive cellular therapy. In this review, we discuss these trials from a translational perspective with an important focus on safety. Finally, we identify crucial knowledge gaps for future study.

Attenuating Neurogenic Sympathetic Hyperreflexia Robustly Improves Antibacterial Immunity After Chronic Spinal Cord Injury

Spinal cord injury (SCI) disrupts critical physiological systems, including the cardiovascular and immune system. Plasticity of spinal circuits below the injury results in abnormal, heightened sympathetic responses, such as extreme, sudden hypertension that hallmarks life-threatening autonomic dysreflexia. Moreover, such sympathetic hyperreflexia detrimentally impacts other effector organs, including the spleen, resulting in spinal cord injury-induced immunodeficiency. Consequently, infection is a leading cause of mortality after SCI. Unfortunately, there are no current treatments that prophylactically limit sympathetic hyperreflexia to prevent subsequent effector organ dysfunction. The cytokine soluble tumor necrosis factor α (sTNFα) is upregulated in the CNS within minutes after SCI and remains elevated. Here, we report that commencing intrathecal administration of XPro1595, an inhibitor of sTNFα, at a clinically feasible, postinjury time point (i.e., 3 d after complete SCI) sufficiently diminishes maladaptive plasticity within the spinal sympathetic reflex circuit. This results in less severe autonomic dysreflexia, a real-time gauge of sympathetic hyperreflexia, for months postinjury. Remarkably, delayed delivery of the sTNFα inhibitor prevents sympathetic hyperreflexia-associated splenic atrophy and loss of leukocytes to dramatically improve the endogenous ability of chronic SCI rats to fight off pneumonia, a common cause of hospitalization after injury. The improved immune function with XPro1595 correlates with less noradrenergic fiber sprouting and normalized norepinephrine levels in the spleen, indicating that heightened, central sTNFα signaling drives peripheral, norepinephrine-mediated organ dysfunction, a novel mechanism of action. Thus, our preclinical study supports intrathecally targeting sTNFα as a viable strategy to broadly attenuate sympathetic dysregulation, thereby improving cardiovascular regulation and immunity long after SCI.SIGNIFICANCE STATEMENT Spinal cord injury (SCI) significantly disrupts immunity, thus increasing susceptibility to infection, a leading cause of morbidity in those living with SCI. Here, we report that commencing intrathecal administration of an inhibitor of the proinflammatory cytokine soluble tumor necrosis factor α days after an injury sufficiently diminishes autonomic dysreflexia, a real time gauge of sympathetic hyperreflexia, to prevent associated splenic atrophy. This dramatically improves the endogenous ability of chronically injured rats to fight off pneumonia, a common cause of hospitalization. This preclinical study could have a significant impact for broadly improving quality of life of SCI individuals.

Rice Components with Immunomodulatory Function

Rice (Oryza sativa) is one of the most important food crops in the world, and the effect of its consumption on human health is of great concern. Evidence has accumulated that rice contains several components, such as γ-oryzanol and rice bran fibers, which modulate the immune system. In addition, rice has other immunologically beneficial characteristics. It has a low allergenic potential and is gluten-free, reducing the risk of development of food allergies and diseases related to gluten sensitivity such as coeliac disease. This review presents the recent advances in our understanding of the immunomodulatory function of rice components.