Induced CD8+FoxP3+ Treg cells in rheumatoid arthritis are modulated by p38 phosphorylation and monocytes expressing membrane tumor necrosis factor α and CD86

Role of Treg cell subsets in cardiovascular disease pathogenesis and potential therapeutic targets

In the genesis and progression of cardiovascular diseases involving both innate and adaptive immune responses, inflammation plays a pivotal and dual role. Studies in experimental animals indicate that certain immune responses are protective, while others exacerbate the disease. T-helper (Th) 1 cell immune responses are recognized as key drivers of inflammatory progression in cardiovascular diseases. Consequently, the CD4+CD25+FOXP3+ regulatory T cells (Tregs) are gaining increasing attention for their roles in inflammation and immune regulation. Given the critical role of Tregs in maintaining immune-inflammatory balance and homeostasis, abnormalities in their generation or function might lead to aberrant immune responses, thereby initiating pathological changes. Numerous preclinical studies and clinical trials have unveiled the central role of Tregs in cardiovascular diseases, such as atherosclerosis. Here, we review the roles and mechanisms of Treg subsets in cardiovascular conditions like atherosclerosis, hypertension, myocardial infarction and remodeling, myocarditis, dilated cardiomyopathy, and heart failure. While the precise molecular mechanisms of Tregs in cardiac protection remain elusive, therapeutic strategies targeting Tregs present a promising new direction for the prevention and treatment of cardiovascular diseases.

Harnessing CD8+CD28- Regulatory T Cells as a Tool to Treat Autoimmune Disease

T regulatory cell therapy presents a novel therapeutic strategy for patients with autoimmune diseases or who are undergoing transplantation. At present, the CD4⁺ Treg population has been extensively characterized, as a result of defined phenotypic and functional readouts. In this review article, we discuss the development and biology of CD8⁺ Tregs and their role in murine and human disease indications. A subset of CD8⁺ Tregs that lack the surface expression of CD28 (CD8⁺CD28⁻ Treg) has proved efficacious in preclinical models. CD8⁺CD28⁻ Tregs are present in healthy individuals, but their impaired functionality in disease renders them less effective in mediating immunosuppression. We primarily focus on harnessing CD8⁺ Treg cell therapy in the clinic to support current treatment for patients with autoimmune or inflammatory conditions.

Regulatory T Cell Plasticity and Stability and Autoimmune Diseases

CD4⁺CD25⁺ regulatory T cells (Tregs) are a class of CD4⁺ T cells with immunosuppressive functions that play a critical role in maintaining immune homeostasis. However, in certain disease settings, Tregs demonstrate plastic differentiation, and the stability of these Tregs, which is characterized by the stable expression or protective epigenetic modifications of the transcription factor Foxp3, becomes abnormal. Plastic Tregs have some features of helper T (Th) cells, such as the secretion of Th-related cytokines and the expression of specific transcription factors in Th cells, but also still retain the expression of Foxp3, a feature of Tregs. Although such Th-like Tregs can secrete pro-inflammatory cytokines, they still possess a strong ability to inhibit specific Th cell responses. Therefore, the plastic differentiation of Tregs not only increases the complexity of the immune circumstances under pathological conditions, especially autoimmune diseases, but also shows an association with changes in the stability of Tregs. The plastic differentiation and stability change of Tregs play vital roles in the progression of diseases. This review focuses on the phenotypic characteristics, functions, and formation conditions of several plastic Tregs and also summarizes the changes of Treg stability and their effects on inhibitory function. Additionally, the effects of Treg plasticity and stability on disease prognosis for several autoimmune diseases were also investigated in order to better understand the relationship between Tregs and autoimmune diseases.

Molecular Markers of Regulatory T Cells in Cancer Immunotherapy with Special Focus on Acute Myeloid Leukemia (AML) - A Systematic Review

The next-generation immunotherapy can only be effective if researchers have an in-depth understanding of the function and regulation of Treg cells in antitumor immunity combined with the discovery of new immunity targets. This can enhance clinical efficacy of future and novel therapies and reduces any adverse reactions arising from the latter. This review discusses tumor treatment strategies using regulatory T (Treg) cell therapy in a Tumor Microenvironment (TME). It also discusses factors affecting TME instability as well as relevant treatments to prevent future immune disorders. It is prognosticated that PD-1 inhibitors are risky and their adverse effects should be taken into account when they are administered to treat Acute Myeloid Leukemia (AML), lung adenocarcinoma, and prostate adenocarcinoma. In contrast, Treg molecular markers FoxP3 and CD25 analyzed here have stronger expression in almost all kinds of cancers compared with normal people. However, CD25 inhibitors are more effective compared to FoxP3 inhibitors, especially in combination with TGF-β blockade, in predicting patient survival. According to the data obtained from the Cancer Genome Atlas, we then concentrate on AML immunotherapy and discuss different therapeutic strategies including anti-CD25/IL-2, anti-CTLA-4, anti-IDO, antityrosine kinase receptor, and anti-PI3K therapies and highlight the recent advances and clinical achievements in AML immunotherapy. In order to prognosticate the risk and adverse effects of key target inhibitors (namely against CTLA-4, FoxP3, CD25, and PD-1), we finally analyzed and compared the Cancer Genome Atlas derived from ten common cancers. This review shows that Treg cells are strongly increased in AML and the comparative review of key markers shows that Tregbased immunotherapy is not effective for all kinds of cancer. Therefore, blocking CD25(+)FoxP3(+) Treg cells is suggested in AML more than other kinds of cancer; meanwhile, Treg markers studied in other cancers have also great lessons for AML immunotherapy.

Inhibition of two-pore channels in antigen-presenting cells promotes the expansion of TNFR2-expressing CD4+Foxp3+ regulatory T cells

CD4+Foxp3+ regulatory T cells (Tregs) are pivotal for the inhibition of autoimmune inflammatory responses. One way to therapeutically harness the immunosuppressive actions of Tregs is to stimulate the proliferative expansion of TNFR2-expressing CD4+Foxp3+ Tregs via transmembrane TNF (tmTNF). Here, we report that two-pore channel (TPC) inhibitors markedly enhance tmTNF expression on antigen-presenting cells. Furthermore, injection of TPC inhibitors including tetrandrine, or TPC-specific siRNAs in mice, increases the number of Tregs in a tmTNF/TNFR2-dependent manner. In a mouse colitis model, inhibition of TPCs by tetrandrine markedly attenuates colon inflammation by expansion of Tregs Mechanistically, we show that TPC inhibitors enhance tmTNF levels by disrupting surface expression of TNF-α-converting enzyme by regulating vesicle trafficking. These results suggest that the therapeutic potential of TPC inhibitors is mediated by expansion of TNFR2-expressing Tregs and elucidate the basis of clinical use in the treatment of autoimmune and other inflammatory diseases.

Future prospects for CD8+ regulatory T cells in immune tolerance

CD8⁺ Tregs have been long described and significant progresses have been made about their phenotype, their functional mechanisms, and their suppressive ability compared to conventional CD4⁺ Tregs. They are now at the dawn of their clinical use. In this review, we will summarize their phenotypic characteristics, their mechanisms of action, the similarities, differences and synergies between CD8⁺ and CD4⁺ Tregs, and we will discuss the biology, development and induction of CD8⁺ Tregs, their manufacturing for clinical use, considering open questions/uncertainties and future technically accessible improvements notably through genetic modifications.

Advances on CD8+ Treg Cells and Their Potential in Transplantation

Although cluster of differentiation (CD)8 regulatory T (Treg) cells have been in the last 20 years more studied since evidences of their role in tolerance as been demonstrated in transplantation, autoimmune diseases and cancer, their characteristics are still controversial. In this review, we will focus on recent advances on CD8 Treg cells and description of a role for CD8 Treg cells in tolerance in both solid organ transplantation and graft-versus-host disease and their potential for clinical trials.

Monocytes in rheumatoid arthritis: Circulating precursors of macrophages and osteoclasts and, their heterogeneity and plasticity role in RA pathogenesis

Rheumatoid arthritis (RA) is a chronic systemic, autoimmune and inflammatory disease represented as synovitis, pannus formation, adjacent bone erosions, and joint destruction. The major cells involved in the perpetuation of RA pathogenesis are CD4⁺ T-cells (mainly Th1 cells and Th17 cells), fibroblasts like synoviocytes (FLS), macrophages and B cells. Other autoimmune cells such as dendritic cells, neutrophils, mast cells, and monocytes also contribute to RA pathogenesis. Monocytes are mainly bone marrow (BM) derived cells in the circulation. The chemokine receptors CCR2 and CX3CR1 expressed by monocytes interact with chemokine ligands CCL2 (MCP-1) and CX3CL1 (fractalkine) respectively produced by FLS and this interaction promotes their migration and recruitment into RA synovium. Activated monocytes on their surface exhibit upregulated antigenic expressions such as CD14, CD16, HLA-DR, toll-like receptors (TLRs), and adhesion molecules B1 and B2 integrins. RA monocytes interconnect with other cells in a positive loop manner in the propagation of the rheumatoid process. They skew towards mainly intermediate monocyte subsets (CD14⁺⁺ CD16⁺) which produce proinflammatory cytokines such as TNF-α, IL-1β, and IL-6. Moreover, the predominant intermediate monocytes in RA differentiate into M1-macrophages which play a major role in synovial inflammation. Demonstrations suggest monocytes with CD14⁺ and CD16^- expression (classical monocytes?) differentiate to osteoclasts which are the cells responsible for bone erosion in RA synovial joints. Th17 cells induce the production of RANKL by FLS which promotes osteoclastogenesis. Cytokines mainly TNF-α, IL-1β, and IL-6 amplify osteoclastogenesis. Hence, monocytes are the circulating precursors of macrophages and osteoclasts in RA. AIM OF THE REVIEW: To enlighten the identity of monocytes, the antigenic expression on monocyte surface and their cytokines role in RA. We also emphasize about the chemokine receptors expressed by monocytes subsets and chemotaxis of circulating monocytes into RA synovium. Additionally, we review monocytes as the circulating precursors of macrophages and osteoclasts in RA joints and their heterogeneity and plasticity role in RA.

The role of vitamin D testing and replacement in fibromyalgia: a systematic literature review

BACKGROUND

Fibromyalgia is a debilitating condition, characterized by extensive muscular pain and fatigue. Vitamin D is essential for overall health, with ubiquitous involvement in various inflammatory and pain pathways. Little is known about its role in fibromyalgia. We performed a systematic literature review to determine if vitamin D contributes to the pathology and disability of patients with fibromyalgia, and to assess the role of vitamin D supplementation in disease management.

METHODS

We searched Medline, EMBASE and the Cochrane Library for clinical studies and randomized controlled trials published in English during January 2000 to June 2017, using the terms vitamin D or hypovitaminosis D combined with fibromyalgia or FMS. References were reviewed manually and articles were only included if they were specific in their diagnosis of fibromyalgia and used appropriate control groups.

RESULTS

Four hundred and sixty-six studies were retrieved, of which fourteen fulfilled the inclusion criteria. Six studies, of which two had the best quality evidence, found that patients with fibromyalgia have low levels of vitamin D compared to healthy controls. Conflicting results were obtained on the effect of vitamin D on pain or symptom control, with no clear consensus as to the role of supplementation in the management of fibromyalgia.

CONCLUSIONS

Our results highlight an association between vitamin D deficiency and fibromyalgia. However, its role in the pathophysiology of fibromyalgia and the clinical relevance of identifying and treating this requires further elucidation with appropriately controlled studies.

Providence of the CD25+ KIR+ CD127- FOXP3- CD8+ T-cell subset determines the dynamics of tumor immune surveillance

CD8⁺ T-regulatory (Treg) cells are emerging as crucial components of immune system. Previous studies have reported the presence of FOXP3⁺ CD8⁺ Treg cells, similar to CD4⁺ Tregs, in cancer patients which produce high levels of the immunosuppressive cytokines, IL10 and TGFβ. At an early stage of tumor development, we have identified a subset of FOXP3^- CD8⁺ CD25⁺ KIR⁺ CD127^- Treg-like cells, which are IFNγ⁺ . However, this early-induced CD8⁺ CD25⁺ CD127^- T-cell subset is certainly distinct from the IFNγ⁺ CD8⁺ T-effector cells. These CD8⁺ CD25⁺ CD127^- T cells express other FOXP3^- CD8⁺ Treg cell signature markers, and can selectively suppress autoreactive HLA-E⁺ T_FH cells as well as tumor-induced CD4⁺ Treg cells. In contrast to FOXP3⁺ CD8⁺ Tregs, this subset does not inhibit effector T-cell proliferation or their functions as they are HLA-E^- . Adoptive transfer of this early-CD8⁺ Treg-like subset restrained tumor growth and inhibited CD4⁺ Treg generation that impedes the immune surveillance and impairs cancer immunotherapy. At the late stage of tumor development, when CD4⁺ Treg cells dominate the tumor-microenvironment, CD4⁺ Tregs mediate the clonal deletion of these tumor-suppressive FOXP3^- IFNγ⁺ CD8⁺ CD25⁺ CD127^- T cells and ensure tumor immune evasion. Our findings suggest that at an early stage of the tumor, this tumor-induced IFNγ-producing FOXP3^- CD8⁺ CD25⁺ CD127^- T-cell subset can potentiate immune surveillance by targeting HLA-E-restricted CD4⁺ Treg cells while leaving the effector T-cell population unaffected. Hence, manipulating their profile can open up a new avenue in cancer immunotherapy.

Selective Activation of Tumor Necrosis Factor Receptor II Induces Antiinflammatory Responses and Alleviates Experimental Arthritis

OBJECTIVE

Treg cells modulate immune responses and can suppress the development of autoimmune diseases. Tumor necrosis factor receptor II (TNFRII) has been recognized as a key receptor on these cells that facilitates expansion and stabilization of CD4+ Treg cells. The purpose of the present study was to investigate the therapeutic activity of a novel TNFRII agonist in experimental arthritis as well as the role of different Treg cell subsets.

METHODS

A novel mouse TNFRII-selective fusion protein (EHD2-sc-mTNF_R2 ) was generated by genetic engineering. Mouse T cells were incubated together with interleukin-2 and/or EHD2-sc-mTNF_R2 , and the effects on Treg cells were analyzed by flow cytometry. Mice with collagen-induced arthritis (CIA) were treated with EHD2-sc-mTNF_R2 or saline, and the therapeutic effects were monitored and characterized.

RESULTS

Selective activation of TNFRII was found to expand both CD4+ and CD8+ Treg cells. Moreover, TNFRII activation elevated the number of CD4+CD25+ and CD8+CD25+ Treg cells and increased the number of FoxP3-expressing cells in CD8+, but not CD4+, Treg cells, indicating different mechanisms of TNFRII-induced expansion of diverse T cell subsets with suppressive activity. In the CIA model, we demonstrated that administration of the TNFRII agonist EHD2-sc-mTNF_R2 led to the expansion of both CD4+ and CD8+ Treg cells in vivo and induced antiinflammatory responses that alleviated arthritis.

CONCLUSION

Our findings support the use of TNFRII-selective therapeutics as an effective approach to the treatment of arthritic disease and possibly other inflammatory and autoimmune diseases.

Infliximab relieves blood retinal barrier breakdown through the p38 MAPK pathway in a diabetic rat model

AIM

To clarify the mechanism of infliximab treatment in diabetic macular edema (DME) and to provide a new alternative therapy for DME.

METHODS

Rats were randomly divided into the control group, the model group and the infliximab treatment group. A diabetic rat model was created. The concentration of TNF-α in the vitreous body was detected by ELISA. The expressions of B-Raf, p38, claudin-1 and occludin in the retina were detected by Western blot. The integrity of the blood retinal barrier (BRB) was measured using Evan's blue as a tracer.

RESULTS

After three months and six months of the diabetes model, the vitreous TNF-α level in the model group was higher than that of the control group. It was also higher in treated group than that of the control group but was lower than that of the model group. The differences among the three groups were statistically significant (at 3mo, F=857.098, P<0.001; 6mo, F=1261.897, P<0.001). The retina B-Raf and p38 levels in the model group were higher than that of the control group. They were also higher in treated group than that of the control group but were lower than that of the model group. The differences among the three groups were statistically significant (B-Raf at 3mo, F=106.596, P<0.001 and at 6mo, F=200.681, P<0.001; p38 at 3mo, F=41.662, P<0.001 and at 6mo, F=67.979, P<0.001). The retina claudin-1 and occludin levels in the model group were lower than that of the control group. They were also lower in treated group than that of the control group but were higher than that of the model group. The differences among three groups were statistically significant (claudin-1 at 3mo, F=139.088, P<0.001 and at 6mo, F=128.415, P<0.001; occludin at 3mo, F=92.733, P<0.001 and at 6mo, F=104.478, P<0.001). The retinal Evans blue leakage in the model group was higher than that of the control group. It was also higher in treated group than that of the control group but was lower than that of the model group. The differences among the three groups were statistically significant (at 3mo, F=447.946, P<0.001; at 6mo, F=1610.732, P<0.001).

CONCLUSION

In a diabetic rat model, infliximab may relieve TNF-α induced BRB breakdown via the B-Raf and p38 signaling pathway.

The balance between Foxp3 and Ror-γt expression in peripheral blood is altered by tocilizumab and abatacept in patients with rheumatoid arthritis

Background

The balance between Th17 cells and regulatory T (Treg) cells has been shown to play an important role in the development of rheumatoid arthritis (RA). Recent studies have shown that treatment with abatacept (ABT) or tocilizumab (TCZ) affects Th17 and Treg cell populations. Although not unanimously accepted, several reports have shown that Treg cells are decreased by ABT and increased by TCZ, and that Th17 cells are decreased by TCZ. To further investigate the effects of ABT and TCZ on the skewing of T cell populations, we analyzed the expression of master regulators genes of helper T cell lineages following ABT/TCZ treatment of RA patients.

Methods

Ten patients treated with ABT and 10 patients treated with TCZ were enrolled. Total RNA was extracted from peripheral blood cells at baseline, and after 12 and 24 weeks of therapy. The expression levels of T-bet, GATA3, Foxp3 and Ror-γt were semi-quantified using real-time PCR. The relative expression levels were expressed as the ratios of two genes (T-bet/GATA3, Foxp3/GATA3, Foxp3/T-bet, Foxp3/Ror-γt, Ror-γt/T-bet, Ror-γt/GATA3), and the changes in these ratios with treatment were determined.

Results

The Foxp3/Ror-γt ratio was decreased after ABT therapy (0.67 ± 0.16 at 24 weeks, P = 0.0034) but was increased after TCZ therapy (2.00 ± 1.03 at 24 weeks, P = 0.0013). In addition, the Ror-γt/GATA3 ratio was decreased after TCZ therapy (0.78 ± 0.37 at 24 weeks, P = 0.0008). Except for these ratios, no significant skewing in the expression of these factors was detected. No significant relationship between clinical response to the treatment and change in the ratios of these factors was determined.

Conclusion

Treatment with TCZ or ABT differently affected the balance between Foxp3 and Ror-γt expression in the peripheral blood of patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1137-1) contains supplementary material, which is available to authorized users.

CD8(+) T cells in human autoimmune arthritis: the unusual suspects

CD8(+) T cells are key players in the body's defence against viral infections and cancer. To date, data on the role of CD8(+) T cells in autoimmune diseases have been scarce, especially when compared with the wealth of research on CD4(+) T cells. However, growing evidence suggests that CD8(+) T-cell homeostasis is impaired in human autoimmune diseases. The contribution of CD8(+) T cells to autoimmune arthritis is indicated by the close association of MHC class I polymorphisms with disease risk, as well as the correlation between CD8(+) T-cell phenotype and disease outcome. The heterogeneous phenotype, resistance to regulation and impaired regulatory function of CD8(+) T cells - especially at the target organ - might contribute to the persistence of autoimmune inflammation. Moreover, newly identified populations of tissue-resident CD8(+) T cells and their interaction with antigen-presenting cells might have a key role in disease pathology. In this Review, we assess the link between CD8(+) T cells, autoimmune arthritis and the basis of their homeostatic changes under inflammatory conditions. Improved insight into CD8(+) T cell-specific pathogenicity will be essential for a better understanding of autoimmune arthritis and the identification of new therapeutic targets.

Emerging Therapies for Rheumatoid Arthritis

Diverse strategies to develop novel treatments for rheumatoid arthritis which specifically target those patients who do not respond to available medications, including biologics, are currently being explored. New potential therapeutic approaches which may become available as part of standard therapeutic regimens include the propagation of regulatory T cells and-in the future-of regulatory B cells. New biologic disease-modifying antirheumatic drugs (b-DMARDs) against interleukin-17 and -6, granulocyte-macrophage colony-stimulating factor, and complement component 5 are now standard components of clinical treatment programs. In addition, recent data indicate that bispecific monoclonal antibody therapies may be more effective than monoclonal antibody monotherapies. It is also becoming apparent that the use of more toxic b-DMARDs against B cells, a therapeutic strategy already being applied in the treatment of hematological diseases, may also be efficacious for treating B cell-mediated autoimmune diseases. Undoubtedly, more small molecules will be developed in the future, and combination therapies with, for example, kinase inhibitors and b-DMARDs, will most likely be tested. Finally, immunoproteasome inhibitors will become available for patients with B cell-mediated autoimmunities, which are refractory to currently available treatment options. The new and exciting extension of current treatment options for rheumatoid arthritis, biosimilars, will not be discussed in this review as details on these agents are available in recently published reports.