Importance Of Foxp3 Research Articles

CD4+FoxP3+CD73+ regulatory T cell promotes cardiac healing post-myocardial infarction.

Rationale: Despite recent studies indicating a crucial role of ecto-5′-nucleotidase (CD73) on T cells in cardiac injury after ischemia/reperfusion, the involvement of CD73+ regulatory T cells (Tregs) in cardiac repair post-myocardial infarction (MI) remains unclear. We sought to investigate the contribution of CD73 on Tregs to the resolution of cardiac inflammation and remodeling after MI.Methods: Cardiac function, tissue injury, Tregs percentage in injured hearts, and purinergic signaling changes in cardiac FoxP3+ Tregs were analyzed after permanent descending coronary artery ligation. CD73 knockout Tregs were used to determine the function of CD73 on Tregs. Peripheral blood mononuclear cells (PBMCs) from acute myocardial infarction (AMI) patients and matched non-MI subjects were assessed via flow cytometry.Results: Cardiac Tregs exhibited distinction of purinergic signaling post MI with dramatically high level of CD73 compared to the sham Tregs. CD73 deficiency decreased the tissue tropism, and impaired the immunosuppressive and protective function of Tregs in cardiac healing. Administration of low-dose of IL-2/anti-IL-2 complex resulted in FoxP3+CD73+Tregs expansion in the heart and contributed to the recovery of cardiac function. CD73 derived from FoxP3+Tregs could bind to FoxP3- effector T-cells and inhibit the production of multiple inflammatory cytokines. In AMI patients, CD73 expressions on both CD4+ cells and FoxP3+Tregs decreased in PBMCs. Moreover, CD73 expressions on CD4+ T cells were negatively correlated with the levels of NT pro-BNP and myocardial zymogram in serum.Conclusions: Our findings indicated the importance of FoxP3+CD73+Tregs in inflammation resolution and cardiac healing post-MI.

The Regulatory/Cytotoxic T Cell Profiles in Blood of Pediatric Kidney-Transplant Recipients with Acute Rejection

Background: The equilibrium between regulatory cells and cytotoxic cells may define graft consequence. We investigated the relationship between the expression of main regulatory and cytotoxic markers (i.e., FOXP3 and granzyme B (GZM-B), respectively) and acute rejection (AR) in the peripheral blood of pediatric renal transplant recipients. Methods: In this retrospective study, FOXP3 mRNA expression and serum GZM-B levels in peripheral blood samples from 47 first-time pediatric kidney-transplant recipients were measured, with 17 children classified as possessing AR; whereas the remaining 30 children had functionally stabilized allografts. Results: Levels of the FOXP3 mRNA vs. the expression levels GADPH mRNA (FOXP3 mRNA/GADPH mRNA) were significantly elevated in children with AR than those with stabilized renal allograft (0.48 ± 0.26 vs.0.23 ± 0.18, respectively, P=0.002) Also, serum GZM-B levels in the AR group were elevated than those in the functionally stabilized children (120.07 ± 91.42p g/ml and, 60.16 ± 46.29 pg/ml respectively, P=0.01). ROC curve evidenced that measuring FOXP3 mRNA may have a scope as a decision-taking agent in clinical proceedings to diagnose AR. Measuring peripheral blood FOXP3 mRNA elucidated scope to help in the noninvasive diagnosis of AR. Conclusions: Our results emphasize FOXP3 mRNA as a biomarker for AR in pediatrics. Assessment of regulatory/cytotoxic profiles in the peripheral blood of pediatric renal transplant recipients is a potentially useful tool for patient selection and early detection of rejection. Depending on many variables, such as the method of sample normalization, the technique used, the extent of graft inflammation, the immunosuppression regimen, depletion/ repletion of T-lymphocyte component, the importance of FOXP3 may differ.

Abstract 4690: FoxP3+T cells program/re-program the prostatic tumor microenvironment

Abstract Foxp3+ T cells play a critical role in maintaining immunological tolerance by regulating functions of other immune cells, thus preventing autoimmunity. Previous studies have demonstrated the importance of Foxp3+ T cells in the tumor, however, the role increasingly recruited FoxP3+ T cells in the programming of prostatic tumor microenvironment is not well illustrated. Therefore, in this study, we have investigated the role of Foxp3+ T cells in the prostatic tumor microenvironment with the notion that increased Foxp3+ T cells facilitate tumor growth. To accomplish this, we carried out tumor induction studies in C57/BL-6 mice using transgenic adenocarcinoma of mouse prostate (TRAMP cell lines: -C1, -C2 and -C3) as tumor models. Mice were administered with TRAMP (C1-3) cells using the Matrigel system. TRAMP-C3 cells are non-tumorigenic while TRAMP-C1 and TRAMP-C2 cells form tumors. Mice were sacrificed by cervical dislocation when tumor sizes reached ~18-20mm in diameter. To prepare single cell suspension, spleen and tumor were dissected out and cells were stained with various cell surface as well as intracellular immune markers to determine the number of Foxp3+ T cells and other immune cells in the prostatic tumor microenvironment. Our findings suggest that the high number of Foxp3+ T cells was found in the spleen and tumor of TRAMP-C1 and TRAMP-C2 mice than the spleen and tiny tumor of TRAMP-C3 mice. Furthermore, the number of cytotoxic T lymphocytes and NK cells were also observed to be low in the tumorigenic TRAMP-C1 and -C2 mice as compared to non-tumorigenic mice (TRAMP-C3). Therefore, our findings suggest that the number of Foxp3+ T cells may play a critical role in shaping the prostatic tumor microenvironment. Citation Format: Sanjay Kumar, James Stoke III, Shalie Malik, Udai P. Singh, Selvarangan Ponnazhagan, Upender Manne, Manoj K. Mishra. FoxP3+T cells program/re-program the prostatic tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4690.

IL-1β promotes Th17 differentiation by inducing alternative splicing of FOXP3.

CD4+FOXP3+ regulatory T (Treg) cells are essential for maintaining immunological self-tolerance. Treg cell development and function depend on the transcription factor FOXP3, which is present in several distinct isoforms due to alternative splicing. Despite the importance of FOXP3 in the proper maintenance of Treg cells, the regulation and functional consequences of FOXP3 isoform expression remains poorly understood. Here, we show that in human Treg cells IL-1β promotes excision of FOXP3 exon 7. FOXP3 is not only expressed by Treg cells but is also transiently expressed when naïve T cells differentiate into Th17 cells. Forced splicing of FOXP3 into FOXP3Δ2Δ7 strongly favored Th17 differentiation in vitro. We also found that patients with Crohn’s disease express increased levels of FOXP3 transcripts lacking exon 7, which correlate with disease severity and IL-17 production. Our results demonstrate that alternative splicing of FOXP3 modulates T cell differentiation. These results highlight the importance of characterizing FOXP3 expression on an isoform basis and suggest that immune responses may be manipulated by modulating the expression of FOXP3 isoforms, which has broad implications for the treatment of autoimmune diseases.

Cellular and molecular determinants for the development of natural and induced regulatory T cells.

Regulation of immune responses to self and foreign antigens is critically dependent on suppressive CD4(+) T cells characterized by expression of Foxp3. The large majority of regulatory T (Treg) cells develop in the thymus as a stable suppressive lineage. However, under the proper physiological conditions, conventional peripheral CD4(+) T lymphocytes also develop into Treg cells, particularly in the gut mucosa and inflammatory tissue sites. This review will focus on our current understanding of the immunological and molecular signals controlling the development of thymic derived natural (n)Treg and peripheral converted induced (i)Treg cells. Given the importance of Foxp3 in the development of these cells, particular attention is placed on how such signals are integrated to induce and maintain the expression of this signature transcriptional regulator of Treg cells.

Foxp3+ regulatory T cells, immune stimulation and host defence against infection

The immune system is intricately regulated allowing potent effectors to expand and become rapidly mobilized after infection, while simultaneously silencing potentially detrimental responses that averts immune-mediated damage to host tissues. This relies in large part on the delicate interplay between immune suppressive regulatory CD4+ T (Treg) cells and immune effectors that without active suppression by Treg cells cause systemic and organ-specific autoimmunity. Although these beneficial roles have been classically described as counterbalanced by impaired host defence against infection, newfound protective roles for Treg cells against specific viral pathogens (e.g. herpes simplex virus 2, lymphocytic choriomeningitis virus, West Nile virus) have been uncovered using transgenic mice that allow in vivo Treg-cell ablation based on Foxp3 expression. In turn, Foxp3+ Treg cells also provide protection against some parasitic (Plasmodium sp., Toxoplasma gondii) and fungal (Candida albicans) pathogens. By contrast, for bacterial and mycobacterial infections (e.g. Listeria monocytogenes, Salmonella enterica, Mycobacterium tuberculosis), experimental manipulation of Foxp3+ cells continues to indicate detrimental roles for Treg cells in host defence. This variance is probably related to functional plasticity in Treg cell suppression that shifts discordantly following infection with different types of pathogens. Furthermore, the efficiency whereby Treg cells silence immune activation coupled with the plasticity in Foxp3+ cell activity suggest that overriding Treg-mediated suppression represents a prerequisite ‘signal zero’ that together with other stimulation signals [T-cell receptor (signal 1), co-stimulation (signal 2), inflammatory cytokines (signal 3)] are essential for T-cell activation in vivo. Herein, the importance of Foxp3+ Treg cells in host defence against infection, and the significance of infection-induced shifts in Treg-cell suppression are summarized.

Multipotent mesenchymal stromal cells express FoxP3: a marker for the immunosuppressive capacity?

Multipotent mesenchymal stromal cells (MSCs) have immunosuppressive capacity but the exact mechanism by which they suppress proliferation of T lymphocytes is not fully understood. Recently, the characteristics and function of regulatory T lymphocytes (Tregs) have become better defined. Tregs and MSCs have immunosuppressive features in common. Here, we looked for a common basis for immunosuppression in these distinct cell types. Forkhead box P3 (FoxP3) and CD39 expression in MSCs was measured by flow cytometry and real-time quantitative polymerase chain reaction. The importance of FoxP3 in MSC-mediated immunosuppression was investigated by siRNA technology and mixed lymphocyte culture (MLC). The effect of 5-azacytidine and other immunosuppressive drugs on FoxP3 expression and immunosuppression by MSCs was explored by flow cytometry, MLC, and real-time quantitative polymerase chain reaction. MSCs express FoxP3 at variable levels, but they do not express CD39. FoxP3 MSCs suppress MLC to a greater extent than cells with lower FoxP3 expression. However, FoxP3-decreased MSCs were found to retain their immunosuppressive properties. 5-azacytitine had no effect on FoxP3 expression or MLC suppression by MSCs. However, immunosuppressive drugs led to increased FoxP3 levels and MLC inhibition in FoxP3 MSCs. This is the first demonstration of FoxP3 expression by MSCs. Although MSCs share several features with Tregs, and FoxP3 MSCs tend to be more immunosuppressive, MSCs do not require functional FoxP3 for their immunosuppressive activity. The increased MSC-mediated suppression of immune responses by immunosuppressive drugs deserves further investigation.

Foxp3 Processing by Proprotein Convertases and Control of Regulatory T Cell Function

Foxp3 is a 47-kDa transcription factor central to regulatory T cell (Treg) function. The importance of Foxp3(+) Tregs in controlling self-reactive T cells and preventing autoimmunity is well established. Our analysis of Foxp3 expression in natural Tregs led to identification of a shorter 41-kDa Foxp3 species in activated Tregs, indicating that Foxp3 may be processed by proteolytic cleavage upon cell activation. Searches of murine and human Foxp3 sequences for potential cleavage sites responsible for the generation of the short Foxp3 species revealed the presence of two RXXR proprotein convertase (PC) motifs, (48)RDLR(51) and (414)RKKR(417), located near the N- and C-terminal ends, respectively. We show, using retroviral expression of Foxp3 in CD4(+) T cells, that Foxp3 is cleaved at both the N- and C-terminal RXXR sites and that mutagenesis of the RXXR motif prevents cleavage. The cleaved forms of Foxp3 are found in the chromatin fraction but not in nuclear or cytoplasmic extracts. CD4(+) T cells expressing Foxp3 species engineered to mimic N-terminally, C-terminally, or N- and C-terminally cleaved Foxp3 forms are functionally distinct, as indicated by differences in expression of key Treg genes, such as interleukin-10 and cytotoxic T-lymphocyte antigen 4 (CTLA-4). In addition, CD4(+) cells expressing C-cleaved Foxp3 are superior to those that express WT Foxp3 in preventing experimental colitis. Coexpression of Foxp3 with PC1 or PC7 results in cleavage of the Foxp3 C terminus. The mechanism by which Foxp3 is processed likely extends to other members of the FoxP subfamily, because Foxp1 and Foxp2 also have N-terminal RXXR proteolytic cleavage motifs at similar locations to Foxp3. Our results indicate that the generation of fully functionally competent Tregs is complex and dependent on the generation of multiple forms of Foxp3 that have differing effects on Treg cytokine production and suppressive function.