Transforming growth factor-β1-induced CD4+CD25+ regulatory T cells in vitro reverse and prevent a murine lupus-like syndrome of chronic graft-versus-host disease

Mechanisms of Epstein-Barr virus nuclear antigen 1 favor Tregs accumulation in nasopharyngeal carcinoma

Background

Documented reports proved that Epstein‐Barr virus (EBV) infection increased infiltration of Tregs in malignancy. However, the mechanism of EBV recruitment Tregs into nasopharyngeal carcinoma (NPC) tissues has not been detailed discussion.

Methods

Expression of EBV nuclear antigen 1 (EBNA1) and Foxp3 in NPC tissue samples was detected by immunohistochemistry. EBNA1+ NPC cell lines were used to coculture with PBMC, naïve T cells, Tregs, and monocytes. Percent of Treg was detected by flow cytometry.

Results

EBNA1 protein was overexpressed in NPC tissues, and was associated with a number of infiltrated Tregs. EBNA1+ NPC cells converted naïve T cells into Tregs by up‐regulated TGF‐β1. Enhanced CCL20 production in EBNA1‐expressed tumor cells increased Tregs migration. Polarized‐M2 macrophages by EBNA1 expression cells converted naïve T cells into Tregs.

Conclusions

EBNA1 favors accumulation of Tregs in NPC through: (a) upregulated TGF‐β1 converted naïve T cell into Treg; (b) upregulated CCL20 increased Treg migration; and (c) polarized‐M2 macrophage converted naïve T cell into Treg.

Interleukin-2-inducible T-cell kinase expression and relation to disease severity in systemic lupus erythematosus

BACKGROUND

Interleukin-2 inducible T-cell kinase (ITK) is expressed in T cells, and plays an important role in autoimmune inflammatory diseases through regulating the balance of Th17/Treg. However, its role in human systemic lupus erythematosus (SLE) remains unclear. The present study aims to measure the activation status of ITK in T cells from SLE patients and healthy controls, and identify its possible correlation to disease severity. We also discuss the serum levels of Th17, Treg related cytokines including IL-17, IL-21, IL-22, IL-10, analyzing correlation between ITK and Th17/Treg related cytokines.

METHODS

Peripheral blood samples were drawn from 42 patients with SLE and 43 healthy blood donors, and the phosphorylation of ITK protein was studied in T cells using flow cytometry. In addition, serum levels of Th17/Treg related cytokines were studied with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Percentages of CD4⁺pITK⁺ T cells, CD8⁺pITK⁺ T cells were higher in SLE patients compared with controls, and were positively related to disease activity, some clinical and laboratory parameters. Percentages of CD4⁺pITK⁺ T cells, CD8⁺pITK⁺ T cells were more prominent in active SLE patients compared with less active patients. Serum levels of Th17 and Treg related cytokines were higher in patients compared with controls. CD4⁺pITK⁺ T cells were related to levels of IL-17, IL-21.

CONCLUSION

These data indicate that increased ITK expression could act as a disease activity marker and as a risk factor for involvement in SLE, but it still needs further study to confirm.

TGF-β-Induced Regulatory T Cells Directly Suppress B Cell Responses through a Noncytotoxic Mechanism

Foxp3(+) regulatory T cells (Treg) playing a crucial role in the maintenance of immune tolerance and prevention of autoimmune diseases consist of thymus-derived naturally occurring CD4(+)Foxp3(+) Treg cells (nTreg) and those that can be induced ex vivo with TGF-β (iTreg). Although both Treg subsets share similar phenotypes and functional characteristics, they also have potential biologic differences on their biology. The role of iTreg in regulating B cells remains unclear so far. The suppression assays of Treg subsets on activation, proliferation, and Abs production of B cells were measured using a Treg and B cell coculture system in vitro. Transwell and Ab blockade experiments were performed to assess the roles of cell contact and soluble cytokines. Treg were adoptively transferred to lupus mice to assess in vivo effects on B cells. Like nTreg, iTreg subset also directly suppressed activation and proliferation of B cells. nTreg subset suppressed B cell responses through cytotoxic manner related to expression of granzyme A, granzyme B, and perforin, whereas the role of iTreg subset on B cells did not involve in cytotoxic action but depending on TGF-β signaling. Furthermore, iTreg subset can significantly suppress Ab produced by lupus B cells in vitro. Comparison experiments using autoantibodies microarrays demonstrated that adoptive transfer of iTreg had a superior effect than nTreg subset on suppressing lupus B cell responses in vivo. Our data implicate a role and advantage of iTreg subset in treating B cell-mediated autoimmune diseases, boosting the translational potential of these findings.

Adoptive cell transfer in autoimmune hepatitis

Adoptive cell transfer is an intervention in which autologous immune cells that have been expanded ex vivo are re-introduced to mitigate a pathological process. Tregs, mesenchymal stromal cells, dendritic cells, macrophages and myeloid-derived suppressor cells have been transferred in diverse immune-mediated diseases, and Tregs have been the focus of investigations in autoimmune hepatitis. Transferred Tregs have improved histological findings in animal models of autoimmune hepatitis and autoimmune cholangitis. Key challenges relate to discrepant findings among studies, phenotypic instability of the transferred population, uncertain side effects and possible need for staged therapy involving anti-inflammatory drugs. Future investigations must resolve issues about the purification, durability and safety of these cells and consider alternative populations if necessary.

Transforming growth factor-β1-induced Treg cells inhibit the absorption of tissue-engineered cartilage caused by endogenous IFN-γ and TNF-α

BACKGROUND

In a previous study, we showed that IFN-γ and TNF-α induce bone marrow mesenchymal stem cell (BMMSC) apoptosis and absorption of tissue-engineered cartilage, but the induced regulatory T cells (iTreg) inhibit the function of IFN-γ and TNF-α. In this study, we investigated the effect of iTreg cells on the absorption of tissue-engineered cartilage caused by endogenous IFN-γ and TNF-α.

METHODS

We transfected the TGF-β1 gene into BMMSCs co-cultured with CD4(+) T lymphocytes. Then, we assessed the expression of iTreg cell markers (Foxp3, CD25 and CD 39) and IFN-γ and TNF-α and the level of apoptosis of BMMSCs. In addition, we characterized chondrogenic-committed cells from TGF-β1(+)BMMSCs and explored the role of iTreg cells.

RESULTS

IFN-γ and TNF-α were detected in the groups with CD4(+) T cells. In the group in which TGF-β1(+)BMMSCs were co-cultured with CD4(+) T cells, we observed Foxp3(+)Treg/ CD25(+)CD39(+) (17.58 ± 0.45%) cells as well as significant inhibition of BMMSC apoptosis and tissue-engineered cartilage absorption.

CONCLUSIONS

CD4(+) T cells led to the absorption of tissue-engineered cartilage through the secretion of endogenous IFN-γ and TNF-α, whose inflammatory functions were concomitantly suppressed by iTreg cells converted from CD4(+) T cells. This study is clinically relevant and adds to our understanding of the mechanism of tissue-engineered cartilage absorption.

Induced Foxp3(+) regulatory T cells: a potential new weapon to treat autoimmune and inflammatory diseases?

Foxp3(+) T regulatory cells (Tregs) consisting of natural and induced Treg subsets play a crucial role in the maintenance of immune homeostasis against self-antigen. The actions designed to correct defects in numbers or functions of Tregs may be therapeutic in the treatment of autoimmune diseases. While recent studies demonstrated that natural Tregs are instable and dysfunctional in the inflammatory condition, induced Tregs (iTregs) may have a different feature. Here we review the progress of iTregs, particularly focus on their stability and function in the established autoimmune diseases. The advantage of iTregs as therapeutics used under inflammatory conditions is highlighted. Proper generation and manipulation of iTregs used for cellular therapy may provide a promise for the treatment of many autoimmune and inflammatory diseases.

Antileukemia and antitumor effects of the graft-versus-host disease: a new immunovirological approach

In leukemic mice, the native host's explicit and well-defined immune reactions to the leukemia virus (a strong exogenous antigen) and to leukemia cells (pretending in their native hosts to be protected "self" elements) are extinguished and replaced in GvHD (graft-versus-host disease) by those of the immunocompetent donor cells. In many cases, the GvHD-inducer donors display genetically encoded resistance to the leukemia virus. In human patients only antileukemia and anti-tumor cell immune reactions are mobilized; thus, patients are deprived of immune reactions to a strong exogenous antigen (the elusive human leukemia-sarcoma retroviruses). The innate and adaptive immune systems of mice have to sustain the immunosuppressive effects of leukemia-inducing retroviruses. Human patients due to the lack of leukemiainducing retroviral pathogens (if they exist, they have not as yet been discovered), escape such immunological downgrading. After studying leukemogenic retroviruses in murine and feline (and other mammalian) hosts, it is very difficult to dismiss retroviral etiology for human leukemias and sarcomas. Since no characterized and thus recognized leukemogenic-sarcomagenic retroviral agents are being isolated from the vast majority of human leukemias-sarcomas, the treatment for these conditions in mice and in human patients vastly differ. It is immunological and biological modalities (alpha interferons; vaccines; adoptive lymphocyte therapy) that dominate the treatment of murine leukemias, whereas combination chemotherapy remains the main remission-inducing agent in human leukemias-lymphomas and sarcomas (as humanized monoclonal antibodies and immunotoxins move in). Yet, in this apparently different backgrounds in Mus and Homo, GvHD, as a treatment modality, appears to work well in both hosts, by replacing the hosts' anti-leukemia and anti-tumor immune faculties with those of the donor. The clinical application of GvHD in the treatment of human leukemias-lymphomas and malignant solid tumors remains a force worthy of pursuit, refinement and strengthening. Graft engineering and modifications of the inner immunological environment of the recipient host by the activation or administration of tumor memory T cells, selected Treg cells and natural killer (NKT) cell classes and cytokines, and the improved pharmacotherapy of GvHD without reducing its antitumor efficacy, will raise the value of GvHD to the higher ranks of the effective antitumor immunotherapeutical measures. Clinical interventions of HCT/HSCT (hematopoietic cell/stem cell transplants) are now applicable to an extended spectrum of malignant diseases in human patients, being available to elderly patients, who receive non-myeloablative conditioning, are re-enforced by post-transplant donor lymphocyte (NK cell and immune T cell) infusions and post-transplant vaccinations, and the donor cells may derive from engineered grafts, or from cord blood with reduced GvHD, but increased GvL/GvT-inducing capabilities (graft-versus leukemia/tumor). Post-transplant T cell transfusions are possible only if selected leukemia antigen-specific T cell clones are available. In verbatim quotation: "Ultimately, advances in separation of GvT from GvHD will further enhance the potential of allogeneic HCT as a curative treatment for hematological malignancies" (Rezvani, A.R. and Storb, R.F., Journal of Autoimmunity 30:172-179, 2008 (see in the text)). It may be added: for cure, a combination of the GvL/T effects with new targeted therapeutic modalities, as elaborated on in this article, will be necessary.

Therapeutic potential of TGF-β-induced CD4(+) Foxp3(+) regulatory T cells in autoimmune diseases

Foxp3(+) T regulatory cell (Treg) subsets play a crucial role in the maintenance of immune homeostasis against self-antigens. The lack or dysfunction of these cells contributes to the pathogenesis and development of many autoimmune diseases. Therefore, manipulation of these cells may provide a novel therapeutic approach to treat autoimmune diseases. In this review, we provide current opinions concerning the classification, developmental, and functional characterization of Treg subsets. Particular emphasis will be focused on the therapeutic role of TGF-β-induced CD4M(+) Foxp3(+) cells (iTregs) in established autoimmune disease. Moreover, the similarity and diversity of iTregs and naturally occurring, thymus-derived CD4(+) CD25(+) Foxp3(+) regulatory T cells (nTregs) will be discussed, including the finding that the pro-inflammatory cytokine IL-6 can convert nTregs to IL-17-producing cells, whereas iTregs induced by TGF-β are resistant to the effects of this cytokine. Understanding these aspects may help to determine how Tregs can be used in the treatment of autoimmune diseases.

Low frequency of CD4+CD25+ Treg in SLE patients: a heritable trait associated with CTLA4 and TGFbeta gene variants

Background

CD4⁺CD25⁺ regulatory T cells play an essential role in maintaining immune homeostasis and preventing autoimmunity. Therefore, defects in Treg development, maintenance or function have been associated with several human autoimmune diseases including Systemic Lupus Erythematosus (SLE), a systemic autoimmune disease characterized by loss of tolerance to nuclear components and significantly more frequent in females.

Results

To investigate the involvement of Treg in SLE pathogenesis, we determined the frequency of CD4⁺CD25⁺CD45RO⁺ T cells, which encompass the majority of Treg activity, in the PBMC of 148 SLE patients (76 patients were part of 54 families), 166 relatives and 117 controls. SLE patients and their relatives were recruited in several Portuguese hospitals and through the Portuguese Lupus Association. Control individuals were blood donors recruited from several regional blood donor centers. Treg frequency was significantly lower in SLE patients than healthy controls (z = -6.161, P < 0.00001) and intermediate in the relatives' group. Remarkably, this T cell subset was also lower in females, most strikingly in the control population (z = 4.121, P < 0.001). We further ascertained that the decreased frequency of Treg in SLE patients resulted from the specific reduction of bona fide FOXP3⁺CD4⁺CD25⁺ Treg. Treg frequency was negatively correlated with SLE activity index (SLEDAI) and titers of serum anti-dsDNA antibodies. Both Treg frequency and disease activity were modulated by IVIg treatment in a documented SLE case. The segregation of Treg frequency within the SLE families was indicative of a genetic trait. Candidate gene analysis revealed that specific variants of CTLA4 and TGFβ were associated with the decreased frequency of Treg in PBMC, while FOXP3 gene variants were associated with affection status, but not with Treg frequency.

Conclusion

SLE patients have impaired Treg production or maintenance, a trait strongly associated with SLE disease activity and autoantibody titers, and possibly resulting from the inability to convert FOXP3⁺CD25^- into FOXP3⁺CD25⁺ T cells. Treg frequency is highly heritable within SLE families, with specific variants of the CTLA4 and TGFβ genes contributing to this trait, while FOXP3 contributes to SLE through mechanisms not involving a modulation of Treg frequency. These findings establish that the genetic components in SLE pathogenesis include genes related to Treg generation or maintenance.