Identification, Isolation, and Functional Assay of Regulatory T Cells

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis

OBJECTIVES

Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues.

SUBJECTS

The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications.

RESULTS

Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD.

CONCLUSION

Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Roles of Regulatory T Cell-Derived Extracellular Vesicles in Human Diseases

Regulatory T (Treg) cells play crucial roles in maintaining immune self-tolerance and immune homeostasis, and closely associated with many human diseases. Recently, Treg cells-derived extracellular vesicles (Treg-EVs) have been demonstrated as a novel cell-contact independent inhibitory mechanism of Treg cells. Treg-EVs contain many specific biological molecules, which are delivered to target cells and modulate immune responses by inhibiting T cell proliferation, inducing T cell apoptosis, and changing the cytokine expression profiles of target cells. The abnormal quantity or function of Treg-EVs is associated with several types of human diseases or conditions, such as transplant rejection, inflammatory diseases, autoimmune diseases, and cancers. Treg-EVs are promising novel potential targets for disease diagnosis, therapy, and drug transport. Moreover, Treg-EVs possess distinct advantages over Treg cell-based immunotherapies. However, the therapeutic potential of Treg-EVs is limited by some factors, such as the standardized protocol for isolation and purification, large scale production, and drug loading efficiency. In this review, we systematically describe the structure, components, functions, and basic mechanisms of action of Treg-EVs and discuss the emerging roles in pathogenesis and the potential application of Treg-EVs in human diseases.

Immunotherapy with regulatory T and B cells in periodontitis

Periodontitis (PD), also known as gum disease, is a condition causing inflammatory bone resorption and tooth loss. Regulatory T cells (Tregs) and regulatory B cells (Bregs) are vital in controlling the immune response and hence play a role in infections and peripheral tolerance adjustment. These cells have immunosuppressive and tissue-repairing capabilities that are important for periodontal health; however, in inflammatory circumstances, Tregs may become unstable and dysfunctional, accelerating tissue deterioration. In recent years, Regulatory cell-mediated immunotherapy has been shown to be effective in many inflammatory diseases. Considering the roles of Tregs and Bregs in shaping immune responses, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the role of regulatory T and B cells, as well as their therapeutic applications in PD.

Inflammatory Markers Related to Innate and Adaptive Immunity in Atherosclerosis: Implications for Disease Prediction and Prospective Therapeutics

Several lines of evidence have linked a dysregulated inflammatory setting to the pathogenesis of atherosclerosis, which is a form of chronic vascular inflammation. Various inflammatory biomarkers have been associated with inflammation and are recognized as potential tools to monitor the progression of atherosclerosis. A well-studied inflammatory marker in the context of cardiovascular diseases is C-reactive protein (CRP) or, more accurately, highly sensitive-CRP (hs-CRP), which has been established as an inflammatory biomarker for atherosclerotic events. In addition, a growing body of investigations has attempted to disclose the potential of inflammatory cytokines, enzymes, and genetic polymorphisms related to innate and adaptive immunity as biomarkers for predicting the development of atherosclerosis. In this review article, we clarify both traditional and novel inflammatory biomarkers related to components of the innate and adaptive immune system that may mirror the progression or phases of atherosclerotic inflammation/lesions. Furthermore, the contribution of the inflammatory biomarkers in developing potential therapeutics against atherosclerotic treatment will be discussed.

Association of Foxp3 rs3761548 polymorphism with cytokines concentration in gastric adenocarcinoma patients

T regulatory cells (Tregs) and related-cytokines are effectively engaged in the process of tumor immune escape and functionally inhibit immune response against the tumor. This study aimed to investigate the association of Foxp3 gene single nucleotide polymorphism (SNP) (rs3761548) with serum IL-35, IL-10, and TGF-β levels in gastric adenocarcinoma (GA) patients. The blood samples were obtained from 150 GA patients and 166 control subjects. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was done to genotyping of Foxp3 gene polymorphism (rs3761548). The serum cytokines levels were measured using the ELISA method. According to genotyping, the AA, and AC genotypes and A allele demonstrated significantly greater risk of GA. Considering the Lauren classification, our results revealed a greater risk of GA progression in patients with AC + AA genotype compared to CC genotype. Moreover, significantly increased levels of IL-10, IL-35, and TGF-β were observed in GA patients compared to controls and also in diffuse-type compared to the intestinal type of GA patients. The IL-35, IL-10 concentrations in GA patients displayed significant differences between the participants with CC, AC and AA genotypes. Further analysis indicated the prognostic role of serum IL-35, IL-10, and TGF-β levels in GA patients. Our results confirmed that the Foxp3 polymorphism (rs3761548) could influence the predisposition to GA and the serum IL-10, IL-35, and TGF-β levels. Thus, this polymorphism might be involved in the GA progression through influencing Tregs function and the secretion of immunomodulatory cytokines.

Dawn of Monitoring Regulatory T Cells in (Pre-)clinical Studies: Their Relevance Is Slowly Recognised

Regulatory T cells (Tregs) have a prominent role in the control of immune homeostasis. Pharmacological impact on their activity or balance with effector T cells could contribute to (impaired) clinical responses or adverse events. Monitoring treatment-related effects on T cell subsets may therefore be part of (pre-)clinical studies for medicinal products. However, the extent of immune monitoring performed in studies for marketing authorisation and the degree of correspondence with data available in the public domain is not known. We evaluated the presence of T cell immunomonitoring in 46 registration dossiers of monoclonal antibodies indicated for immune-related disorders and published scientific papers. We found that the depth of Treg analysis in registration dossiers was rather small. Nevertheless, data on treatment-related Treg effects are available in public academia-driven studies (post-registration) and suggest that Tregs may act as a biomarker for clinical responses. However, public data are fragmented and obtained with heterogeneity of experimental approaches from a diversity of species and tissues. To reveal the potential added value of T cell (and particular Treg) evaluation in (pre-)clinical studies, more cell-specific data should be acquired, at least for medicinal products with an immunomodulatory mechanism. Therefore, extensive analysis of T cell subset contribution to clinical responses and the relevance of treatment-induced changes in their levels is needed. Preferably, industry and academia should work together to obtain these data in a standardised manner and to enrich our knowledge about T cell activity in disease pathogenesis and therapies. This will ultimately elucidate the necessity of T cell subset monitoring in the therapeutic benefit-risk assessment.

Shikonin Controls the Differentiation of CD4+CD25+ Regulatory T Cells by Inhibiting AKT/mTOR Pathway

CD4⁺CD25⁺ regulatory T (Treg) cells maintain the function of immune tolerance and the balance of immune cells. Defects in the number and function of Treg cells can induce the development and progression of inflammatory disease. Shikonin, the main active ingredient of Lithospermum, has anti-inflammatory and anti-tumor effects. Shikonin is also an effective drug for the treatment of psoriasis, which is a chronic inflammatory skin disease. However, the underlying mechanism is not yet clear. To evaluate the role of shikonin on the induction of Treg cells, we tested the number and function of Treg cells in vivo and in vitro. Shikonin can effectively promote the differentiation of iTreg cells by inhibiting the AKT/mTOR pathway in vitro. Moreover, in vivo, intragastrically administered shikonin effectively improved lesions in mice with imiquimod-induced psoriasis and increased the number of iTreg cells in the spleen and their secretion. Shikonin significantly increases the expression of Foxp3mRNA in skin of the psorisic mice. Therefore, we expect that shikonin can prevent the development of inflammation and treat psoriasis by regulating iTreg cells. Novel ideas for the treatment of psoriasis are also proposed.

Chimeric antigen receptor T cells in solid tumors: a war against the tumor microenvironment

Chimeric antigen receptor (CAR) T cell is a novel approach, which utilizes anti-tumor immunity for cancer treatment. As compared to the traditional cell-mediated immunity, CAR-T possesses the improved specificity of tumor antigens and independent cytotoxicity from major histocompatibility complex molecules through a monoclonal antibody in addition to the T-cell receptor. CAR-T cell has proven its effectiveness, primarily in hematological malignancies, specifically where the CD 19 CAR-T cells were used to treat B-cell acute lymphoblastic leukemia and B-cell lymphomas. Nevertheless, there is little progress in the treatment of solid tumors despite the fact that many CAR agents have been created to target tumor antigens such as CEA, EGFR/EGFRvIII, GD2, HER2, MSLN, MUC1, and other antigens. The main obstruction against the progress of research in solid tumors is the tumor microenvironment, in which several elements, such as poor locating ability, immunosuppressive cells, cytokines, chemokines, immunosuppressive checkpoints, inhibitory metabolic factors, tumor antigen loss, and antigen heterogeneity, could affect the potency of CAR-T cells. To overcome these hurdles, researchers have reconstructed the CAR-T cells in various ways. The purpose of this review is to summarize the current research in this field, analyze the mechanisms of the major barriers mentioned above, outline the main solutions, and discuss the outlook of this novel immunotherapeutic modality.

Regulatory T cells for amyotrophic lateral sclerosis/motor neuron disease: A clinical and preclinical systematic review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by neuronal degeneration and inflammation in the nerves. The role of the immune system has been concentrated by researchers in the etiopathogenesis of the disease. Given the inhibitory roles of regulatory T cells (Tregs), it is expected that increasing or activating their populations in patients with ALS can have significant therapeutic effects. Here we searched databases, including CENTRAL, MEDLINE, CINAHL Plus, clinicaltrials.gov, and ICTRP for randomized clinical trials (RCTs) and non-RCTs until March 2019. For preclinical studies, we searched PubMed, Scopus, and Google Scholar up to June 2019. We also included preclinical studies, due to the lack of clinical information available, which used Tregs (or directly targeting them) for treating mice models of ALS. We identified 29 records (CENTRAL 7, MEDLINE 4, CINAHL Plus 8, and clinicaltrials.gov 10) and removed 10 duplicated publications. After screening, we identified one RCT which had been published as an abstract, three non-RCTs, and four ongoing studies. We also identified 551 records (PubMed 446, Google Scholar 68, and Scopus 37) for preclinical studies and performed a meta-analysis. Finally, we found three papers that matched our inclusion criteria for preclinical studies. Results indicated the effectiveness of the application of Tregs in the treatment of ALS. Our meta-analysis on preclinical studies revealed that Tregs significantly prolonged survival in mice models of ALS. Overall, our analysis testified that exertion of Tregs in the treatment of ALS is a promising approach, that notwithstanding, requires further evaluations.

Chronic Hepatitis C Infection Has No Effect on Peripheral CD4+CD25+ Tregulatory Cells in Patients with End-Stage Renal Disease

Background: T regulatory cells (Tregs), through variable mechanisms, play a crucial role in Hepatitis C virus (HCV) chronicity and infection tolerance. A great speculation is posed regarding the level, role of Tregs in end-stage renal disease (ESRD), and the presence of associated factors that could influence the Tregs population. Accordingly, we aimed at studying the effect of HCV infection on peripheral CD4⁺CD25⁺Tregs population among patients on hemodialysis (HD) as well as the effect of other comorbidities on these cells.Patients and methods: A group of 77 patients on HD (32 were HD HCV⁺ and 45 were HD HCV^-) and 80 healthy controls (HCs) were included in the study. Flow cytometric analysis was performed for identification and quantification of peripheral CD4⁺ CD25⁺Tregs.Results: The frequency of CD4⁺ CD25⁺Tregs increased significantly in HD patients compared to the HCs (p = <.0001 each). HCV posed no effect on peripheral CD4+ CD25+ Tregs in ESRD patients, when comparing HD HCV- and HD HCV+ groups. In the hypertensive HD HCV-, Tregs percentage was higher than that in the non-hypertensive. However, the difference was not statistically significant. No significant difference was detected between HD HCV- and HD HCV+ patients on the count and percentages of Tregs according to the duration of dialysis.Conclusion: Demonstrating that chronic HCV infection has no effect on CD4+ CD25+ Tregs cells levels in ESRD patients is of great importance to the success of future allografts in such patients.

The Role of Mesenchymal Stem Cells in Atherosclerosis: Prospects for Therapy via the Modulation of Inflammatory Milieu

Atherosclerosis is a chronic, inflammatory disease that mainly affects the arterial intima. The disease is more prevalent in middle-age and older individuals with one or more cardiovascular risk factors, including dyslipidemia, hypertension, diabetes, smoking, obesity, and others. The beginning and development of atherosclerosis has been associated with several immune components, including infiltration of inflammatory cells, monocyte/macrophage-derived foam cells, and inflammatory cytokines and chemokines. Mesenchymal stem cells (MSCs) originate from several tissue sources of the body and have self-renewal and multipotent differentiation characteristics. They also have immunomodulatory and anti-inflammatory properties. Recently, it was shown that MSCs have a regulatory role in plasma lipid levels. In addition, MSCs have shown to have promising potential in terms of treatment strategies for several diseases, including those with an inflammatory component. In this regard, transplantation of MSCs to patients with atherosclerosis has been proposed as a novel strategy in the treatment of this disease. In this review, we summarize the current advancements regarding MSCs for the treatment of atherosclerosis.

Is it true that gut microbiota is considered as panacea in cancer therapy?

Recent studies demonstrated that a combination of the gut microbiome has the vital effect on the efficacy of anticancer immune therapies. Regulatory effects of microbiota have been shown in different types of cancer therapies such as chemotherapy and immunotherapy. Immune-checkpoint-blocked therapies are the recent efficient cancer immunotherapy strategies. The target of immune-checkpoint blocking is cytotoxic T lymphocyte protein-4 (CTLA-4) or blockade of programmed death-1 (PD-1) protein and its ligand programmed death ligand 1 (PD-L1) that they have been considered as cancer immunotherapy in recent years. In the latest studies, it have been demonstrated that several gut bacteria such as Akkermansia muciniphila, Bifidobacterium spp., Faecalibacterium spp., and Bacteroides fragilis have the regulatory effects on PD-1, PD-L1, and CTLA-4 blocked anticancer therapy outcome.

Immunomodulatory function of Treg-derived exosomes is impaired in patients with relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease which is characterized by neuroaxonal degeneration in the central nervous system. Impaired function of regulatory T cells (Tregs) is believed to be an underlying pathogenic mechanism in MS. Tregs is able to release exosomes, which contain a considerable amount of protein and RNA. Exosomes are capable of transporting their content to other cells where the released content exerts biological functions. Here, we investigated whether Tregs exosomes of RRMS patients or healthy controls might regulate the proliferation or survival of T lymphocytes. Regulatory T cells derived from MS patients or healthy controls were cultured for 3 days and exosomes were purified from supernatants. Treg-derived exosomes were co-cultured with conventional T cells (Tconv). The percentages of Tconv proliferation and apoptosis were measured. Our findings showed that the percentage of proliferation suppression induced by exosomes in patients compared to healthy controls was 8.04 ± 1.17 and 12.5 ± 1.22, respectively, p value = 0.035. Moreover, the rate of Tconv apoptosis induced by exosome of MS patient was less than healthy controls (0.68 ± 0.12 vs. 1.29 ± 0.13; p value = 0.015). Overall, Treg-derived exosomes from MS patients and healthy controls suppressed the proliferation and induced apoptosis in Tconv. However, the effect of MS-derived exosomes was significantly less than healthy controls. Our results point to an alternative Treg inhibitory mechanism which might be important in immunopathogenesis of MS. Although, the cause of the exosomal defect in MS patients is unclear, manipulation of patients' Treg-derived exosomes to restore their suppressive activity might be considered as a potential therapeutic approach. Graphical abstract ᅟ.

T cell exhaustion implications during transplantation

Exhaustion of lymphocyte function, particularly T cell exhaustion, due to prolonged exposure to a high load of foreign antigen is commonly seen during chronic viral infection as well as antitumor immune responses. This phenomenon has been associated with a determined molecular mechanism and phenotypic manifestations on the cell surface. In spite of investigation of exhaustion, mostly about CD8 responses toward viral infections, recent studies have reported that chronic exposure to antigen may develop exhaustion in CD4 + T cells, B cells, and NK cells. Little is known with respect to lymphocyte exhaustion during transplantation and its effect on aberrant anti-graft responses. Through a same mechanobiology observed during chronic exposure of foreign viral antigens, alloantigen persistence mediated by allograft could develop a favorable circumstance for exhaustion of T cells responding to allograft. However, to achieve better manipulation approaches of this event to reduce the complications during transplantation, we need to be armed with a bulk of knowledge with regard to quality and quantity of T cell exhaustion occurring in various allografts, the kinetics of exhaustion development, the impression of immunosuppressive agents on the exhaustion, and the influence of exhaustion on graft survival and immune tolerance.

Interleukin-33 Contributes to the Induction of Th9 Cells and Antitumor Efficacy by Dectin-1-Activated Dendritic Cells

We recently discovered that dectin-1-activated dendritic cells (DCs) drive potent T helper (Th) 9 cell responses and antitumor immunity. However, the underlying mechanisms need to be further defined. The cytokine microenvironment is critical for Th cell differentiation. Here, we show that dectin-1 activation enhances interleukin (IL)-33 expression in DCs. We found that blocking IL-33/ST2 inhibits dectin-1-activated DC-induced Th9 cell differentiation. More importantly, the addition of IL-33 further promotes Th9 cell priming and antitumor efficacy induced by dectin-1-activated DCs. Mechanistically, in addition to the promotion of Th9 and Th1 cells, dectin-1-activated DCs combined with IL-33 abolish the activity of IL-33 in the induction of regulatory T cells. Furthermore, the combined treatment of dectin-1-activated DCs and IL-33 increases the frequencies of CD4⁺ T cells by fostering their proliferation and inhibiting their exhaustive differentiation. Thus, our results demonstrate the important role of IL-33 in dectin-1-activated DC-induced Th9 cell differentiation and antitumor efficacy, and suggest that the combination of dectin-1-activated DCs and IL-33 may present a new effective modality of DC-based vaccines in tumor immunotherapy.

Using marker gene analysis instead of mixed lymphocyte reaction assay for identification of functional CD4+FOXP3+ regulatory T cells

OBJECTIVE

To establish a quick analytical method using quantitative PCR for marker gene analysis to identify the functions of iTreg cells and subsequently curtail the harvest time for iTreg cells.

RESULTS

The data from the marker gene analysis indicated that varying proportions of iTreg cells could reveal the various expression levels of these genes. FoxP3 expression increased to a considerable degree. By using the same iTreg population, the mixed lymphocyte reaction assay was conducted for 5 days. The suppression percentage of T-cells was dependent on the proportion of iTreg cells, indicating that gene expression levels can represent the biological functions of iTreg cells. By using human peripheral blood mononuclear cells for Treg cell induction, the marker gene expression analysis showed a difference between iTreg cells and uninduced T cells.

CONCLUSION

Marker gene analysis requires only 1 day to identify the functions of human iTreg cells can save time in clinical application and might prevent graft-versus-host disease occurrence effectively.

Mucosal immune tolerance at the ocular surface in health and disease

The ocular surface is constantly exposed to environmental irritants, allergens and pathogens, against which it can mount a prompt immune response to preserve its integrity. But to avoid unnecessary inflammation, the ocular surface's mucosal immune system must also discriminate between harmless and potentially dangerous antigens, a seemingly complicated task. Despite its unique features, the ocular surface is a mucosal lining, and as such, it shares some homeostatic and pathophysiological mechanisms with other mucosal surfaces. The purpose of this review is to explore the mucosal homeostatic immune function of the ocular surface in both the healthy and diseased states, with a special focus on mucosal immunology concepts. The information discussed in this review has been retrieved by PubMed searches for literature published from January 1981 to October 2016.