Tregs in immunotherapy: opportunities and challenges

Deregulated phenotype of autoreactive Th17 and Treg clone cells in pemphigus vulgaris after in-vitro treatment with desmoglein antigen (Dsg-3)

The loss of balance between regulatory T (Treg) and T helper 17 (Th17) causes loss of tolerance against desmoglein (Dsg)-3 leading to pemphigus vulgaris (PV), an autoimmune bullous skin disorder associated with autoantibodies against Dsg-3. We aimed to elucidate the complex relationship of Th17 and Treg cells, their molecules, and the underlying mechanism in the development of PV disease. Using cytokine secretion assays, Th17 and Treg cells were sorted by FACS Aria-III within Dsg-3-responsive PBMC population and homogeneous T cell clones were generated in-vitro. Different cell surface molecules like CD25, GITR, CD122, CD152, CD45RO, IL-23R, STAT3, STAT5, CD127, HLA-DR, CCR4, CCR5, CCR6 and CCR7 were studied. The functional response of Th17 and Treg cells were elucidated by measuring the levels of various cytokines released by IL-10 and IL-17 T cells. The mRNA expression of transcription factors (FoxP3 and RORγt) was also analyzed. IL-17 secreting (Th17) cells with phenotype CD4⁺IL-17⁺ were greatly increased and IL-10 secreting (Treg) cells with phenotype CD4⁺IL-10⁺ were reduced in PV cases than healthy controls. The qPCR analysis showing high expression of retinoic acid receptor-related orphan receptor gamma (RORγt) mRNA in comparison to forkhead box P3 (FoxP3) mRNA confirmed the development of pro-inflammatory Th17 response in PV. Further, the cytokine profile of pro-inflammatory and anti-inflammatory cytokines suggested defective suppressive functions in Treg cells with high inflammatory response. Our findings indicate that autoantigen Dsg-3 specifically allows the proliferation of IL-17 secreting T cells though has a negative effect on IL-10 secreting T cells leading to dysregulation of immunity in PV patients. This antagonistic relationship between Dsg-3-specific Th17 and Treg cells may be critical for the onset and persistence of inflammation in PV cases.

The molecular basis of immuno-radiotherapy

PURPOSE

Radiotherapy (RT) and immunotherapy are powerful anti-tumor treatment modalities. Experimental research has demonstrated an important interplay between the cytotoxic effects of RT and the immune system. This systematic review provides an overview of the basics of anti-tumor immunity and focuses on the mechanisms underlying the interplay between RT and immune anti-tumor response that set the molecular basis of immuno-RT.

CONCLUSIONS

An 'immunity acquired equilibrium' mimicking tumor dormancy can be achieved post-irradiation treatment, with the balance shifted toward tumor eradication or regrowth when immune cells' cytotoxic effects or cancer proliferation rate prevail, respectively. RT has both immunosuppressive and immune-enhancing properties. The latter effect is also known as radio-vaccination. Its mechanisms involve up- or down-regulation of membrane molecules, such as PD-L1, HLA-class-I, CD80/86, CD47, and Fas/CD95, that play a vital role in immune checkpoint pathways and increased cytokine expression (e.g. INFα,β,γ, IL1,2, and TNFα) by cancer or immune cells. Moreover, the interactions of radiation with the tumor microenvironment (fibroblasts, tumor-infiltrating lymphocytes, monocytes, and dendritic cells are also an important component of radio-vaccination. Thus, RT may have anti-tumor vaccine properties, whose sequels can be exploited by immunotherapy agents to treat different cancer subtypes effectively.

TB and COVID-19: An Exploration of the Characteristics and Resulting Complications of Co-infection

Tuberculosis (TB) and Coronavirus Disease-19 (COVID-19) infection are two respiratory diseases that are of particular concern epidemiologically. Tuberculosis is one of the oldest diseases recorded in the history of mankind dating back thousands of years. It is estimated that approximately one quarter of the world’s population is infected with latent Mycobacterium tuberculosis (LTBI). This contrasts with COVID-19, which emerged in late 2019. Data continues to accumulate and become available on this pathogen, but the long-term side effect of fibrotic damage in COVID-19 patients evokes parallels between this novel coronavirus and its ancient bacterial affiliate. This similarity as well as several others may incite inquiries on whether coinfection of individuals with latent TB and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lead to excessive fibrosis in the lungs and thus the emergence of an active TB infection. While it is well understood how TB leads to structural and immunological lung complications including granuloma formation, fibrosis, and T cell exhaustion, less is known about the disease course when coinfection with SARS-CoV-2 is present. Past and present research demonstrate that IL-10, TNF-α, IFN class I-III, TGF-β, IL-35, and Regulatory T cells (T-regs) are all important contributors of the characteristics of host response to mycobacterium tuberculosis. It has also been noted with current research that IL-10, TNF-α, IFN class I, II, and III, TGF-β, ACE-2, and T-regs are also important contributors to the host response to the SARS-CoV-2 virus in different ways than they are to the TB pathogen. Both pathogens may lead to an unbalanced inflammatory immune response, and together a shared dysregulation of immune response suggests an increased risk of severity and progression of both diseases. We have reviewed 72 different manuscripts between the years 1992 and 2021. The manuscripts pertaining to the SARS-COV-2 virus specifically are from the years 2020 and 2021. Our literature review aims to explore the biomolecular effects of these contributors to pathogenicity of both diseases along with current publications on TB/COVID-19 coinfection, focusing on the pathogenicity of SARS-CoV-2 infection with both latent and active TB, as well as the challenges in treating TB during the COVID-19 pandemic. The compiled material will then aid the latticework foundation of knowledge for future research leading to a hopeful improved system of therapeutic strategies for coinfection.

Evaluation of miR-200c-3p and miR-421-5p levels during immune responses in the admitted and recovered COVID-19 subjects

Angiotensin-converting enzyme 2 (ACE2) acts as a key receptor for the spike of SARS-CoV-2. Two main microRNAs (miRs), miR-200c-3p and miR-421-5p, are considered to modulate the expression of ACE2 gene and alterations in the expression of these miRNAs may influence the outcomes of COVID-19 infection. Accordingly, we examined whether miRNAs directing ACE2 expression altered in the SARS-CoV-2 infection. 30 patients with COVID-19 included in the study. At the time of admission and discharge, the expression of miR-200c-3p and miR-421-5p, inflammatory cytokine IL-6, and regulatory T cells' expression profiles (CD4, CD25, and Foxp3) were examined using quantitative real-time PCR method. At the time of admission, the expression levels of miR-200c-3p and miR-421-5p as well as CD4, CD25, and Foxp3 significantly decreased while IL-6 expression notably enhanced. However, by the time of discharge, the expression levels of the genes were opposite to the time of admission. Moreover, Pearson correlation analysis indicated that IL-6 expression negatively correlated with Foxp3 and miR-200c-3p expressions despite miR-421-5p and miR-200c-3p positively correlated at admission time. By manipulating miR-200c-3p and miR-421-5p expressions and controlling the ACE2 level, it is plausible to modulate the inflammation by reducing IL-6 and maintenance tolerance hemostasis during COVID-19 infection.

Secretome screening reveals immunomodulating functions of IFNα-7, PAP and GDF-7 on regulatory T-cells

Regulatory T cells (Tregs) are the key cells regulating peripheral autoreactive T lymphocytes. Tregs exert their function by suppressing effector T cells. Tregs have been shown to play essential roles in the control of a variety of physiological and pathological immune responses. However, Tregs are unstable and can lose the expression of FOXP3 and suppressive functions as a consequence of outer stimuli. Available literature suggests that secreted proteins regulate Treg functional states, such as differentiation, proliferation and suppressive function. Identification of secreted proteins that affect Treg cell function are highly interesting for both therapeutic and diagnostic purposes in either hyperactive or immunosuppressed populations. Here, we report a phenotypic screening of a human secretome library in human Treg cells utilising a high throughput flow cytometry technology. Screening a library of 575 secreted proteins allowed us to identify proteins stabilising or destabilising the Treg phenotype as suggested by changes in expression of Treg marker proteins FOXP3 and/or CTLA4. Four proteins including GDF-7, IL-10, PAP and IFNα-7 were identified as positive regulators that increased FOXP3 and/or CTLA4 expression. PAP is a phosphatase. A catalytic-dead version of the protein did not induce an increase in FOXP3 expression. Ten interferon proteins were identified as negative regulators that reduced the expression of both CTLA4 and FOXP3, without affecting cell viability. A transcriptomics analysis supported the differential effect on Tregs of IFNα-7 versus other IFNα proteins, indicating differences in JAK/STAT signaling. A conformational model experiment confirmed a tenfold reduction in IFNAR-mediated ISG transcription for IFNα-7 compared to IFNα-10. This further strengthened the theory of a shift in downstream messaging upon external stimulation. As a summary, we have identified four positive regulators of FOXP3 and/or CTLA4 expression. Further exploration of these Treg modulators and their method of action has the potential to aid the discovery of novel therapies for both autoimmune and infectious diseases as well as for cancer.

Induction of antigen-specific Treg cells in treating autoimmune uveitis via bystander suppressive pathways without compromising anti-tumor immunity

BACKGROUND

Induction of autoantigen-specific Treg cells that suppress tissue-specific autoimmunity without compromising beneficial immune responses is the holy-grail for immunotherapy to autoimmune diseases.

METHODS

In a model of experimental autoimmune uveitis (EAU) that mimics human uveitis, ocular inflammation was induced by immunization with retinal antigen interphotoreceptor retinoid-binding protein (IRBP). Mice were given intraperitoneal injection of αCD4 antibody (Ab) after the onset of disease, followed by administration of IRBP. EAU was evaluated clinically and functionally. Splenocytes, CD4⁺CD25^- and CD4⁺CD25⁺ T cells were sorted and cultured with IRBP or αCD3 Ab. T cell proliferation and cytokine production were assessed.

FINDINGS

The experimental approach resulted in remission of ocular inflammation and rescue of visual function in mice with established EAU. Mechanistically, the therapeutic effect was mediated by induction of antigen-specific Treg cells that inhibited IRBP-driven Th17 response in TGF-β and IL-10 dependent fashion. Importantly, the Ab-mediated immune tolerance could be achieved in EAU mice by administration of retinal autoantigens, arrestin but not limited to IRBP only, in an antigen-nonspecific bystander manner. Further, these EAU-suppressed tolerized mice did not compromise their anti-tumor T immunity in melanoma model.

INTERPRETATION

We successfully addressed a specific immunotherapy of EAU by in vivo induction of autoantigen-specific Treg cells without compromising host overall T cell immunity, which should have potential implication for patients with autoimmune uveitis.

FUNDING

This study was supported by the Natural Science Foundation of Guangdong Province and the Fundamental Research Fund of the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center.

Modular immune-homeostatic microparticles promote immune tolerance in mouse autoimmune models

The therapeutic goal for autoimmune diseases is disease antigen-specific immune tolerance without nonspecific immune suppression. However, it is a challenge to induce antigen-specific immune tolerance in a dysregulated immune system. In this study, we developed immune-homeostatic microparticles (IHMs) that treat multiple mouse models of autoimmunity via induction of apoptosis in activated T cells and reestablishment of regulatory T cells. Specifically, in an experimental model of colitis, IHMs rapidly released monocyte chemotactic protein-1 after intravenous administration, which recruited activated T cells and then induced their apoptosis by conjugated Fas ligand on the IHM surface. This triggered professional macrophages to ingest apoptotic T cells and produce high quantities of transforming growth factor-β, which drove regulatory T cell differentiation. Furthermore, the modular design of IHMs allowed IHMs to be engineered with the autoantigen peptides that can reduce disease in an experimental autoimmune encephalomyelitis mouse model and a nonobese diabetic mouse model. This was accomplished by sustained release of the autoantigens after induction of T cell apoptosis and transforming growth factor-β production by macrophages, which promoted to establish an immune tolerant environment. Thus, IHMs may be an efficient therapeutic strategy for autoimmune diseases through induction of apoptosis and reestablishment of tolerant immune responses.

Synthesis of norisoboldine derivatives and bioactivity assay for inducing the generation of regulatory T cells

In this study, we used chemical modification to improve the pharmacological activity of norisoboldine (NOR). A new NOR-benzoic acid derivative, named DC-01, showed more potent induction of Treg cell differentiation than NOR. The in vitro effective concentration of DC-01 (1 μM) is about an order of magnitude lower than that of NOR (10 μM). DC-01 (28, 56 mg/kg) showed better amelioration of dextran sodium sulfate-induced colitis in mice than NOR (20, 40 mg/kg), and DC-01 (28 mg/kg) increased the number of Treg cells slightly better than NOR (20 mg/kg). In summary, DC-01 exerts more potent induction of Treg cell generation, which might be a candidate drug for the treatment of inflammation- and immune-related diseases.

Association of FOXP3 gene polymorphisms with chronic immune thrombocytopenia in a Chinese Han population

INTRODUCTION

Forkhead box P3 (Foxp3) is encoded by the human FOXP3, an X-chromosome gene, and is a transcription factor that regulates regulatory T-cell (Treg) development and function. FOXP3 gene polymorphisms have recently been investigated as candidate risk factors in various autoimmune diseases. This study aimed to investigate the possible influence of FOXP3 gene polymorphisms on genetic predisposition to chronic immune thrombocytopenia (ITP).

METHODS

The study cohort comprised 329 chronic ITP patients and 279 healthy controls, who were genotyped for three polymorphisms in the promoter region of FOXP3 gene, -6054 del/ATT, -3279 A/C, and -924 A/G.

RESULTS

Of the three polymorphisms identified, the -3279 AA genotype was more frequent in female patients with chronic ITP than in female controls (P = .035, OR 0.434, 95% CI 0.223-0.846), and the -3279 A carrier was shown to be associated with the risk of chronic ITP in female cohort (P = .003, OR 0.610, 95% CI 0.437-0.851). Furthermore, the female patients with chronic ITP had remarkably more frequent haplotype -6054 del/-3279 A/-924 A (P = .027, OR 3.584, 95% CI 1.148-11.186) and less haplotype -6054 del/-3279 C/-924 G (P = .039, OR 0.445, 95% CI 0.204-0.973) in comparison with female healthy controls. Although there were no significant differences in the male cohort, when the combined alleles and haplotypes of the two genders were analyzed, the results obtained were similar to those of females.

CONCLUSION

According to our data, the -3279 A/C polymorphism of FOXP3 gene may be associated with the susceptibility to chronic ITP in Chinese Han population.

Altered Gene Expression Encoding Cytochines, Grow Factors and Cell Cycle Regulators in the Endometrium of Women with Chronic Endometritis

To evaluate the expression of genes encoding cytokines, grow factors and cell cycle regulators in the proliferative endometrium of women with chronic endometritis (CE) compared to controls. We performed a case-control study on seven women with CE as diagnosed by hysteroscopy and histology (Cases) compared to six women without CE (Controls). All women underwent diagnostic hysteroscopy plus endometrial biopsy during the mid-proliferative phase of the menstrual cycle. Endometrial samples were divided into two different aliquots for histological and molecular analyses. The endometrial expression profile of 16 genes encoding proteins involved in the inflammatory process, proliferation and cell cycle regulation/apoptosis was assessed by using high-throughput qPCR. Study endpoints were between-group differences in the expression of VEGF A, VEGF B, VEGF C, EGF, TNF, TGF B1, IFNG, TP73, TP73L, BAXva, CDC2, CDC2va, CCND3, CCNB1, BAX and IL12. RESULTS: VEGF A, VEGF B, VEGF C, EGF, TNF, TGF B1, IFNG, TP73, TP73L, BAXva, CDC2, CDC2va, CCND3, CCNB1 were significantly overexpressed in women with CE compared to controls, while BAX and IL12 had similar expression between groups. In women with CE, we found an altered endometrial expression of genes involved in inflammatory, cell proliferation, and apoptosis processes. The dominance of proliferative and anti-apoptotic activity in CE may potentially promote the development of polyps and hyperplastic lesions.

Lymphopenia and intratumoral lymphocytic balance in the era of cancer immuno-radiotherapy

INTRODUCTION

The immune response has been recognized as a major tumor-eradication component of radiotherapy.

OBJECTIVE

This review studies, under a clinical perspective, two contrasting effects of radiotherapy, namely immunosuppression and radiovaccination.

MATERIALS AND METHODS

We critically reviewed the available clinical and experimental experience on radiotherapy-induced lymphopenia.

RESULTS

Radiation-induced tumor damage promotes radio-vaccination, enhances cytotoxic immune responses, and potentiates immunotherapy. Nevertheless, radiotherapy induces systemic and intratumoral lymphopenia. The above effects are directly related to radiotherapy fractionation and field size/location, and tumor characteristics.

DISCUSSION

Hypofractionated stereotactic and accelerated irradiation better promotes radio-vaccination and produces less severe lymphopenia. Adopting cytoprotective policies and combining lympho-stimulatory agents or agents blocking regulatory lymphocyte activity are awaited to unmask the radio-vaccination effect, enhancing the efficacy immuno-radiotherapy.

CONCLUSION

Radiation-induced lymphopenia and immunosuppression are important issues that should be considered in the design of immuno-radiotherapy clinical trials.

Engineered antigen-specific regulatory T cells for autoimmune skin conditions

Regulatory T cells (Tregs) are a subset of T cells responsible for the regulation of immune responses, thereby maintaining immune homeostasis and providing immune tolerance to both self and non-self-antigens. An increasing number of studies revealed Treg numbers and functions in a variety of autoimmune diseases. Treg deficiency can cause the development of several autoimmune skin diseases including vitiligo, alopecia areata, pemphigoid and pemphigus, psoriasis, and systemic sclerosis. Many clinical trials have been performed for autoimmune conditions using polyclonal Tregs, but efficiency can be significantly improved using antigen-specific Tregs engineered using T cell receptor (TCR) or chimeric antigen receptor (CAR) constructs. In this review, we systematically reviewed altered frequencies, impaired functions, and phenotypic features of Tregs in autoimmune skin conditions. We also summarized new advances in TCR and CAR based antigen-specific Tregs tested both in animal models and in clinics. The advantages and limitations of each approach were carefully discussed emphasizing possible clinical relevance to patients with autoimmune skin diseases. Moreover, we have reviewed potential approaches for engineering antigen-specific Tregs, and strategies for overcoming possible hurdles in clinical applications. Thereby, antigen-specific Tregs can be infused using autologous adoptive cell transfer to restore Treg numbers and to provide local immune tolerance for autoimmune skin disorders.

Soluble recombinant human thrombomodulin suppresses inflammation-induced gastrointestinal tumor growth in a murine peritonitis model

Regulatory T cells (Tregs) and transforming growth factor β (TGF-β) are believed to play key roles in both postoperative pro-inflammatory and anti-inflammatory responses of malignancies. Recombinant human thrombomodulin (rTM) is implied to inhibit the interaction between TGF-β and Tregs. The aim of this study is to evaluate the antitumor effects of rTM against gastrointestinal tumors under systemic inflammation. Mice were subjected to cecal ligation and puncture and percutaneous allogeneic tumor implantation. rTM were introduced by percutaneous injection into the abdominal cavity. The effects of rTM were evaluated by weight of implanted tumor, proportion of Tregs in peripheral blood lymphocytes (PBL) and tumor infiltrating lymphocytes (TIL) and temporal evaluation of serum cytokines. The effect of rTM was also evaluated on the in vitro differentiation of naïve T cells into induced Tregs induced by TGF-β and interleukin (IL) -2. rTM significantly inhibited the proliferation of the implanted tumor cells in an inflammation-dependent manner. rTM also reduced the fractions of regulatory T cells and induced regulatory T cells among both PBL and TIL. Temporal evaluation of serum cytokine levels in the model mice showed that rTM significantly suppressed the increases in the serum levels of IL-2 and TGF-β. An in vitro differentiation assay revealed that rTM inhibited the differentiation of naïve T cells into Tregs triggered by IL-2- and TGF-β. rTM has suppressive effects on inflammation-induced gastrointestinal tumor growth by suggestively affecting differentiation of Tregs.

The impact on T-regulatory cell related immune responses in rural women exposed to polycyclic aromatic hydrocarbons (PAHs) in household air pollution in Gansu, China: A pilot investigation

Previous studies found associations between impairments of immune functions and exposure to polycyclic aromatic hydrocarbons (PAHs) in ambient air pollution in the U. S. and China. However, the results remain inconclusive due to the limitations of these studies. In this study, we aimed to examine the direction and magnitude of immune changes related to PAH exposure from household air pollution among rural women living in Gansu, China. Healthy village women (n = 34) were recruited and enrolled in the study. Questionnaires were administered. Blood and urine samples were collected and analyzed during non-heating (September 2017, "summer") and heating (January 2018, "winter") seasons. Urinary 1-hydroxypyrene (1-OHP) was quantified as the biomarker of PAH exposure. To evaluate Treg cell related immune functions, we examined immunoglobulin E (IgE), percent of T-regulatory (Treg) cells, and gene expression of following: forkhead box transcription factor 3 (Foxp3), transforming growth factor-β (TGF-β), interleukin 10 (IL-10), and interleukin 35 (IL-35), composed of interleukin-12 alpha (IL-12α) and Epstein-Barr-virus-induced gene 3 (EBi3). Urinary 8-hydroxy-2-deoxyguanosine (8-OHdG) was measured to evaluate oxidative DNA damage. The results showed that the concentration of 1-OHP increased from 0.90 to 17.4 μmol mol-Cr ^-1 from summer to winter (p < 0.001). Meanwhile, average percent of Treg cells decreased from 5.01% to 1.15% (p < 0.001); IgE and mRNA expressions of Foxp3, TGF-β, IL-10, IL-12α and EBi3 all significantly decreased (p < 0.001); Urinary 8-OHdG increased from 12.7 to 30.3 ng mg-Cr ^-1 (p < 0.001). The changes in 8-OHdG, Foxp3 and TGF-β were significantly associated with the increase of 1-OHP. The results suggested that we observed a substantial increase of PAH exposure in winter, which was significantly associated with the repression on Treg cell function and oxidative DNA damage. Exposure to PAHs in household air pollution possibly induced immune impairments among rural women in northwest China.

Regulatory Dendritic Cells Induced by Mesenchymal Stem Cells Ameliorate Dextran Sodium Sulfate-Induced Chronic Colitis in Mice

Background/Aims

Regulatory dendritic cells (rDCs), which can be induced by mesenchymal stem cells (MSCs), play an important role in inducing and maintaining homeostasis of regulatory T cells and exhibit anti-inflammatory functions. In this study, we investigated whether MSCs could differentiate DCs into rDCs and compared the therapeutic effects of rDCs and MSCs on dextran sodium sulfate (DSS)-induced chronic colitis mice.

Methods

Immature DCs (imDCs) and lipopolysaccharide (LPS)-treated mature DCs (mDCs) were co-cultured with MSCs for 48 hours, and then the profiles of surface markers and cytokines and regulatory roles of these DCs for primary splenocytes were analyzed. In addition, the therapeutic effects of MSCs and DCs co-cultured with MSCs were compared in chronic colitis mice.

Results

After co-culture of imDCs (MSC-DCs) or LPS-treated mDCs (LPS+MSC-DCs) with MSCs, the expression of CD11c, CD80, CD86, interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), was decreased, but that of CD11b, IL-10, and transforming growth factor-β (TGF-β) was increased. Furthermore, MSC-DCs and LPS+MSC-DCs induced the expression of CD4, CD25, and Foxp3 in primary splenocytes isolated from mice. In DSS-induced colitis mice, MSCs and MSC-DCs increased colon length, body weight, and survival rate and induced histological improvement. Moreover, in the colon tissues, the expression of IL-6, TNF-α, and IFN-γ decreased, but that of IL-10, TGF-β, and Foxp3 increased in the MSC- and MSC-DC-injected groups.

Conclusions

Our data suggest that MSCs differentiate DCs into rDCs, which ameliorate chronic colitis. Thus, rDCs stimulated by MSCs may be therapeutically useful for the treatment of chronic inflammatory diseases.

Effect of artemisinin and neurectomy of pterygoid canal in ovalbumin-induced allergic rhinitis mouse model

Background

Allergic rhinitis (AR), characterized by sneezing, nasal itching and rhinorrhea, affects a large number of population. This study aimed to explore the effects of artemisinin alone or combined with neurectomy of pterygoid canal in ovalbumin-induced AR mouse model and illustrate the underlying mechanisms.

Methods

Allergic symptoms were evaluated to verify inhibitory effect of artemisinin alone or combined with neurectomy of pterygoid canal on AR. Serum levels of histamine, immunoglobulin E (IgE) and inflammatory factors TNF, INF-γ, IL-1β IL-10, IL-4 and IL-5 were measured by ELISA. The mRNA levels of TNF, INF-γ, IL-1β and IL-10 in local lymph nodes were measured by RT-qPCR. The total and phosphorylated levels of ERK and JNK were assessed by Western blot. CD4⁺CD25⁺Foxp3⁺ T (Treg) cells were analyzed by flow cytometry.

Results

Artemisinin significantly relieved the behavior symptoms of AR mice. The administration of artemisinin strikingly suppressed the expression of histamine, IgE and inflammatory factors. An increased Treg cell proportion and inhibited ERK phosphorylation were observed in artemisinin-treated groups as compared to those in the AR group. Moreover, artemisinin plus neurectomy of pterygoid almost abolished the behavioral score increase in AR mice.

Conclusions

These results indicated that artemisinin exhibited anti-allergic effect by inhibiting ERK activation and increasing Treg cell proportion, which subsequently decreased the expressions of allergic mediators. In addition, artemisinin combined with neurectomy of pterygoid showed better efficacy than artemisinin alone.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0249-6) contains supplementary material, which is available to authorized users.

The role of regulatory T cells in immunopathogenesis and immunotherapy of viral infections

Two hepatotropic viruses hepatitis C virus (HCV) and hepatitis B virus (HBV) have been considered as the main cause of chronic viral infections. In addition, human immunodeficiency virus (HIV) attacks the immune system by eradication of some white blood cell (T-helper cell). The role of Tregs in HCV, HBV and HIV infections ranges from suppressing antiviral T cell responses to protecting tissues as liver and immune cells from immune mediated injury. In this review, we discuss the influence of regulatory T cells in immunopathology of specific viral infections including HCV, HBV and HIV by focusing on targeting Tregs as novel approach in vaccinology against viral infections.

Forkhead-box transcription factor 1 affects the apoptosis of natural regulatory T cells by controlling Aven expression

Background

Regulatory T (Treg) cells play important roles in autoimmune diseases, cancer, and organ transplantation. Forkhead box protein o1 (Foxo1) and IL-7Rα(CD127) are closely related to the homeostasis of Treg cells. However, the mechanism underlying Treg proliferation and activation remains unclear. Here, we evaluated how the over-expression of Foxo1 affects Treg cell proliferation via intracellular signaling. nTreg cells were transfected separately with Foxo1 and Aven small-interfering RNA (siRNA) or over-expression plasmid. The expression of signaling pathway genes and CD127 was confirmed using RT-qPCR and western blot analysis. The expression of cell surface molecules and apoptosis was confirmed by Flow Cytometry 3-(4, 5-Dimethylthiazol-2-yl) 2,5- diphenyltetrazolium bromide for cell proliferation assays.

Results

Foxo1 strengthened the proliferative ability of Treg cells by activating IL-7/CD127 signaling. In addition, Foxo1 suppressed Treg cell apoptosis by regulating Aven expression.

Conclusions

The results in this study indicated that Foxo1 is a positive regulatory factor for the proliferation and activity of Treg cells. Foxo1 might be a potential target for the activation of nTreg cells in vivo and in vitro.

Clinical and Histopathologic Characterization of Canine Chronic Ulcerative Stomatitis

Canine chronic ulcerative stomatitis, also known as chronic ulcerative paradental stomatitis, is a painful condition of the oral cavity. The purpose of this study was to determine if there are commonalities in clinical and radiographic features among patients, whether the histopathologic evaluation might inform the pathogenesis, and whether the condition appears similar to human oral mucosal diseases. To do this, we prospectively collected clinical, radiographic, and histopathologic data from 20 dogs diagnosed with the disease. Clinical data were based on a clinical disease activity index, oral and periodontal examination parameters, and full-mouth dental radiographs. The histopathological and immunohistochemical data were based on oral mucosal samples obtained from erosive or ulcerated areas. Our findings revealed that canine chronic stomatitis is clinically characterized by painful oral mucosal ulcers of varying size, pattern, appearance, and distribution, most often associated with teeth with early periodontitis. Histologic examination revealed a subepithelial lichenoid band (interface mucositis) where B cells, T cells, and Forkhead-box protein 3 (FoxP3)- and interleukin-17-expressing cells were present. These cells might play a role in the underlying immune response and an immune-mediated pathogenesis is suspected. The clinical and histopathologic features of this chronic inflammatory mucosal disease in dogs resemble those of oral lichen planus in humans.

The Activation of NF-κB in Infiltrated Mononuclear Cells Negatively Correlates with Treg Cell Frequency in Oral Lichen Planus

Oral lichen planus (OLP) is a T cell-mediated chronic inflammatory mucosal disease with persistent accumulation of T cells in the lamina propria. Nuclear factor-kappa B (NF-κB) is a major regulator of immune responses, and NF-κB-dependent cytokines and pro-inflammatory mediators can be detected in higher levels in the saliva and serum from patients with OLP. CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells play an important role in the prevention of autoimmune pathology by regulating the immune response. To explore the correlation between NF-κB p65 activation and accumulation of Treg cells in patients with OLP, 40 ethnic Chinese patients with OLP and 10 healthy volunteers were recruited. The nuclear expression of NF-κB p65 in infiltrated mononuclear cells and Treg cells in the OLP lesion and the normal oral mucosa (NOM) was analyzed by immunohistochemistry assay. Our results showed that both the nuclear expression of NF-κB p65 and the number of Foxp3(+) Treg were higher in the OLP lesions. Furthermore, the frequency of Treg cells was negatively correlated with NF-κB nuclear expression in subepithelial lymphocytic infiltrate of the OLP lesion. This finding provides a new insight into the pathogenesis of OLP and may contribute to novel therapeutic strategies for the treatment of OLP by modulating the immune system.

Manipulating regulatory T cells: a promising strategy to treat autoimmunity

CD4(+)CD25(+)Foxp3(+)regulatory T cells (Treg cells) are extremely important in maintaining immune tolerance. Manipulation of Treg cells, especially autoantigen-specific Treg cells is a promising approach for treatments of autoimmune disease since Treg cells may provide the advantage of antigen specificity without overall immune suppression. However, the clinical application of Treg cells has long been limited due to low numbers of Treg cells and the difficulty in identifying their antigen specificity. In this review, we summarize studies that demonstrate regression of autoimmune diseases using Treg cells as therapeutics. We also discuss approaches to generate polyclonal and autoantigen-specific Treg cells in vitro and in vivo. We also discuss our recent study that describes a novel approach of generating autoantigen-specific Treg cells in vivo and restoring immune tolerance by two steps apoptosis-antigen therapy.

In vivo-generated antigen-specific regulatory T cells treat autoimmunity without compromising antibacterial immune response

Harnessing regulatory T (Treg) cells is a promising approach for treating autoimmune disease. However, inducing antigen-specific Treg cells that target inflammatory immune cells without compromising beneficial immune responses has remained an unmet challenge. We developed a pathway to generate autoantigen-specific Treg cells in vivo, which showed therapeutic effects on experimental autoimmune encephalomyelitis and nonobese diabetes in mice. Specifically, we induced apoptosis of immune cells by systemic sublethal irradiation or depleted B and CD8(+) T cells with specific antibodies and then administered autoantigenic peptides in mice with established autoimmune diseases. We demonstrated mechanistically that apoptotic cells triggered professional phagocytes to produce transforming growth factor-β, under which the autoantigenic peptides directed naïve CD4(+) T cells to differentiate into Foxp3(+) Treg cells instead of into T effector cells in vivo. These antigen-specific Treg cells specifically ameliorated autoimmunity without compromising immune responses to bacterial antigen. We have thus successfully generated antigen-specific Treg cells with therapeutic activity toward autoimmunity. The findings may lead to the development of antigen-specific Treg cell-mediated immunotherapy for multiple sclerosis and type 1 diabetes and also other autoimmune diseases.

The mucosal immune system in the oral cavity-an orchestra of T cell diversity

The mucosal immune system defends against a vast array of pathogens, yet it exhibits limited responses to commensal microorganisms under healthy conditions. The oral-pharyngeal cavity, the gateway for both the gastrointestinal and respiratory tracts, is composed of complex anatomical structures and is constantly challenged by antigens from air and food. The mucosal immune system of the oral-pharyngeal cavity must prevent pathogen entry while maintaining immune homeostasis, which is achieved via a range of mechanisms that are similar or different to those utilized by the gastrointestinal immune system. In this review, we summarize the features of the mucosal immune system, focusing on T cell subsets and their functions. We also discuss our current understanding of the oral-pharyngeal mucosal immune system.

Kv1.3 deletion biases T cells toward an immunoregulatory phenotype and renders mice resistant to autoimmune encephalomyelitis

Increasing evidence suggests ion channels have critical functions in the differentiation and plasticity of T cells. Kv1.3, a voltage-gated K(+) channel, is a functional marker and a pharmacological target for activated effector memory T cells. Selective Kv1.3 blockers have been shown to inhibit proliferation and cytokine production by human and rat effector memory T cells. We used Kv1.3 knockout (KO) mice to investigate the mechanism by which Kv1.3 blockade affects CD4(+) T cell differentiation during an inflammatory immune-mediated disease. Kv1.3 KO animals displayed significantly lower incidence and severity of myelin oligodendrocyte glycoprotein (MOG) peptide-induced experimental autoimmune encephalomyelitis. Kv1.3 was the only K(V) channel expressed in MOG 35-55-specific CD4(+) T cell blasts, and no K(V) current was present in MOG-specific CD4(+) T cell-blasts from Kv1.3 KO mice. Fewer CD4(+) T cells migrated to the CNS in Kv1.3 KO mice following disease induction, and Ag-specific proliferation of CD4(+) T cells from these mice was impaired with a corresponding cell-cycle delay. Kv1.3 was required for optimal expression of IFN-γ and IL-17, whereas its absence led to increased IL-10 production. Dendritic cells from Kv1.3 KO mice fully activated wild-type CD4(+) T cells, indicating a T cell-intrinsic defect in Kv1.3 KO mice. The loss of Kv1.3 led to a suppressive phenotype, which may contribute to the mechanism by which deletion of Kv1.3 produces an immunotherapeutic effect. Skewing of CD4(+) T cell differentiation toward Ag-specific regulatory T cells by pharmacological blockade or genetic suppression of Kv1.3 might be beneficial for therapy of immune-mediated diseases such as multiple sclerosis.