scholarly journals Conversion of T-Effector Cells to Immunosuppressive T-Regulatory-like Cells By CRISPR/Cas9-Mediated Integration of a FOXP3 Transgene

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3490-3490 ◽  
Author(s):  
Yuchi Honaker ◽  
Yufei Xiang ◽  
Logan Fisher ◽  
Karen Sommer ◽  
Troy R. Torgerson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Autoimmune Disease ◽  
Regulatory T Cells ◽  
Peripheral Blood ◽  
Gene Editing ◽  
Ex Vivo ◽  
Foxp3 Expression ◽  
Self Tolerance ◽  
Equity Ownership

Abstract Regulatory T cells (Treg) are distinct among T cell subtypes, having the primary role of suppressing adaptive immune responses. The importance of these cells in immune self-tolerance is underscored by the genetically inherited syndrome IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked), which is caused by an inactivating mutation in FOXP3. FOXP3 is a transcription factor that is a determinant of regulatory T cell function. Patients with IPEX syndrome suffer from the rapid and severe onset of multi-organ autoimmunity, including severe enteropathy, Type I diabetes, thyroiditis, skin inflammation and other features. In mouse models of IPEX, neonatal transplantation of wild-type Tregs is sufficient to prevent the development of disease. Less-severe Treg defects have also been implicated in the etiology of a variety of prevalent autoimmune diseases. It is possible that the pivotal role for Tregs in self-tolerance could be exploited clinically to improve therapies for autoimmunity and other diseases of tolerance. However, the use of autologous ex vivo expanded Treg as a clinical cell therapy is problematic: Tregs are present in low numbers in the peripheral blood, they expand slowly in culture ex vivo, and they may lack antigen specificities necessary for efficient suppression in specialized tissues. They may also down-regulate FOXP3 expression and lose functional activity in vivo in the setting of chronic inflammation. Additionally, autologous Tregs from patients with autoimmune disease may exhibit cell intrinsic dysfunction, while IPEX patients do not even have Tregs. To overcome these issues, we developed a gene editing approach to enforce stable expression of FOXP3 in primary human CD4+ peripheral blood T cells. CRISPR/Cas9 ribonucleoprotein and an AAV6-delivered donor template were developed to target a MND promoter-FOXP3 cDNA expression cassette (linked to a cell surface LNGFR tag by a 2A ribosome skip peptide) to the FOXP3 locus by homology directed repair (HDR). Highly efficient HDR rates were achieved across multiple donors (~34%; 5 donors in 9 experiments). For therapy of IPEX caused by FOXP3 missense mutations, integration of the functional coding sequence simultaneously abolishes endogenous FOXP3 expression. Following gene editing, expression of FOXP3 was sufficient to drive Treg-like phenotypic changes, including the up-regulation of CD25 and inhibitory receptors and down-regulation of CD127 and inflammatory cytokines. Further, consistent with the translatability of this approach into clinical manufacturing, FOXP3+ cells could be enriched to >90% purity by a simple LNGFR antibody column and expanded 20-fold within one week. Importantly, transfer of these edited Treg-like cells (edTreg) to NOD-scid-IL2Rγ-/- mice prevented xeno-graft vs. host disease (xeno-GvHD) mediated by co-transferred autologous effector T cells; xeno-GvHD protection correlated with long-term survival of the edTregs, and a marked reduction in effector T cell expansion and tissue infiltration. These data support the development of edited regulatory T cells for the treatment of IPEX and other autoimmune disease. Disclosures Scharenberg: Generation Bio: Equity Ownership; Casebia Therapeutics: Employment; Alpine Immune Sciences: Equity Ownership.

scholarly journals Signaling through C5a receptor and C3a receptor diminishes function of murine natural regulatory T cells

2013 ◽  
Vol 210 (2) ◽  
pp. 257-268 ◽  
Author(s):  
Wing-hong Kwan ◽  
William van der Touw ◽  
Estela Paz-Artal ◽  
Ming O. Li ◽  
Peter S. Heeger
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Cell Function ◽  
Foxp3 Expression ◽  
C5a Receptor ◽  
Self Tolerance ◽  
T Cell Immune Responses

Thymus-derived (natural) CD4+ FoxP3+ regulatory T cells (nT reg cells) are required for immune homeostasis and self-tolerance, but must be stringently controlled to permit expansion of protective immunity. Previous findings linking signals transmitted through T cell–expressed C5a receptor (C5aR) and C3a receptor (C3aR) to activation, differentiation, and expansion of conventional CD4+CD25− T cells (T conv cells), raised the possibility that C3aR/C5aR signaling on nT reg cells could physiologically modulate nT reg cell function and thereby further impact the induced strength of T cell immune responses. In this study, we demonstrate that nT reg cells express C3aR and C5aR, and that signaling through these receptors inhibits nT reg cell function. Genetic and pharmacological blockade of C3aR/C5aR signal transduction in nT reg cells augments in vitro and in vivo suppression, abrogates autoimmune colitis, and prolongs allogeneic skin graft survival. Mechanisms involve C3a/C5a-induced phosphorylation of AKT and, as a consequence, phosphorylation of the transcription factor Foxo1, which results in lowered nT reg cell Foxp3 expression. The documentation that C3a/C3aR and C5a/C5aR modulate nT reg cell function via controlling Foxp3 expression suggests targeting this pathway could be exploited to manipulate pathogenic or protective T cell responses.

CD8+ Treg - From Mouse To Man

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3474-3474 ◽  
Author(s):  
Tobias A.W. Holderried ◽  
Hye-Jung Kim ◽  
Philipp A Lang ◽  
Harvey Cantor
Keyword(s):  
T Cells ◽  
Transcription Factor ◽  
T Cell ◽  
Autoimmune Disease ◽  
Regulatory T Cells ◽  
Cd8 T Cells ◽  
Human Homologue ◽  
Cd8 Cells ◽  
Tfh Cells ◽  
Self Tolerance

Abstract T cell-mediated regulation of the immune response to self and foreign antigens is essential to maintain immune homeostasis and prevent autoimmune tissue destruction. The majority of studies addressing this issue, both in mice and humans, have focused on the contribution of CD4+CD25+FOXP3+ regulatory T cells. The contribution of regulatory CD8+ T cells has not been appreciated until recently. Recent studies have identified a small subset of IL-15 dependent CD8+ regulatory T cells (Treg) that is essential for maintenance of self- tolerance and prevention of autoimmune disease in mice. Expression of a triad of cell surface markers – CD44+CD122+Ly49+ – has been used to distinguish and purify CD8+Treg (Kim et al., Nature 2010; Kim et al., PNAS 2011). Here we have defined the human homologue of CD8+ Treg. The Ly49 receptor, identified as a stable surface marker on CD8+ Treg, is a member of a multigenic/multiallelic receptor family recognizing classical MHC class I molecules. The functional homologue of murine Ly49 is the killer cell immunoglobulin-like receptor (KIR). Our analysis has revealed that, while expression of KIR subtype combinations appears to be stochastic and co-expression of these KIR receptors is random, the inhibitory KIR2DL2/3 and KIR3DL1 subtypes are dominantly expressed by human CD3+CD8+ T cells. Similar to murine CD8+ Treg, CD8+ T cells that express KIR2DL2/3 or KIR3DL1 also express CD44 and CD122. Moreover, consistent with murine CD8+ Treg, incubation with IL-15 results in activation and proliferation of KIR+CD8+ T cells that maintain a stable surface phenotype. Gene array analyses in mice has indicated that Helios, a highly conserved zinc finger transcription factor and member of the Ikaros family of transcription factors, is expressed by CD44+CD122+Ly49+ CD8+ Treg. Helios is involved in T cell development and expressed by ∼70% of FoxP3+CD4+ Treg but not by mature B cells, dendritic cells or myeloid cells. Our analyses identified a Helios+ subset in the CD8+ Treg population, which (compared to the Helios- subset) embodies many of the functional characteristics of CD8+ Treg in mice. Co-expression of Helios is also apparent in some KIR+CD8+ T cells in human samples. In mice, we have shown that CD8+ Treg target CD4 TFH cells and thus maintain self-tolerance. In vitro suppression assays revealed that KIR+CD8+ cells but not KIR–CD8+ cells confer inhibitory activity on CD4+CXCR5+ TFHtarget cells in humans. Taken together, our findings implicate KIR+CD8+ cells as the human homologue of murine CD8+ Treg, including expression of transcription factor Helios, responsiveness to IL-15 and suppression of CD4+ TFH cells. Understanding the genetic and biological features of this CD8+ T cell subset in humans opens the possibility of exploiting their regulatory activity for the development of immunotherapy in the context of autoimmune disease and cancer. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Defined Expansion Protocol Supports Ex Vivo Expansion of Gene Edited Hematopoietic Stem Cells to the Single Cell Level

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 48-49
Author(s):  
Hans Jiro Jiro Becker ◽  
Masatoshi Sakurai ◽  
Satoshi Yamazaki
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
Single Cell ◽  
Peripheral Blood ◽  
Gene Editing ◽  
Ex Vivo ◽  
Scid Mice ◽  
Hematopoietic Stem ◽  
Hematopoietic Reconstitution

Background The application of gene editing in hematopoietic stem cells (HSCs) holds great promise for the treatment of genetic blood disorders such as severe combined immunodeficiency (SCID). However, one critical bottleneck is that edited HSCs cannot easily be expanded ex vivo without concomitant loss of self-renewal. This limitation excludes the possibility of growing functional HSCs from single cells, which would enable the selection of desired clones based on sequence verification of relevant on- and off-target modifications. We recently reported on a defined, serum-free, polymer-based culture protocol that selectively facilitates in vitro proliferation of murine HSCs [1]. In the current study, we aimed to expand functional, CRISPR/Cas9-edited HSCs from bulk cell populations as well as from cloned, single HSCs to generate grafts capable of hematopoietic reconstitution. We show that HSCs from the murine PrkdcSCID model, which harbors a point mutation in the Prkdc gene leading to B and T cell deficiency, can be edited and expanded to correct the immunodeficient phenotype after transplantation. Furthermore, we demonstrate that single, gene-edited HSCs can be cloned and expanded using our system to generate functional HSCs for SCT. Methods CD150+CD201+c-Kit+Lin- (CD150+CD201+KL) HSCs from C.B17/Icr-PrkdcSCID (SCID) mice were isolated and cultured in polymer-based medium supplemented with recombinant cytokines. Gene editing was performed with Cas9 protein and appropriate gRNAs delivered as ribonucleoprotein complexes (RNPs) via electroporation. HDR donors were supplied as single-strand oligonucleotides (ssODNs). Stem cell transplantations (SCTs) were carried out after lethal irradiation with 2.5 Gy. Results To demonstrate that edited HSCs can be expanded as a bulk population and efficiently engraft to correct a disease phenotype, SCID mouse-derived donor HSCs were subjected to Cas9-mediated gene editing at the Prkdc locus (Fig. 1a). Total cells and primitive CD201+CD150+cKit+Lin-(KL) cells expanded 70- and 10-fold, respectively, over seven days after which bulk populations were transplanted into SCID mice. Inference of CRISPR edits (ICE) analysis performed at the time of SCT indicated an HDR frequency of 29%±10%. The emergence of B and T cells in peripheral blood samples was observed from four weeks after transplantation (B220+: 21±7%, CD4+: 27±4%, CD8+: 4±1%; Fig 1b). We also confirmed the presence of B and T cells in the spleen and thymus of transplanted mice. Immunization experiments showed immunoglobulin titer levels equal to healthy control mice after challenge with a T-dependent antigen. We conclude that expansion and autologous SCT of edited HSCs restores a functional B and T cell compartment in SCID mice. We next inquired whether our system could be used to expand single, edited HSC clones. To this end, we sorted single, edited CD150+CD201+KL clones by flow cytometry and expanded them for two weeks. Genomic DNA was sampled from growing colonies and editing outcomes at the Prkdc locus were individually assessed to screen for corrected HSCs (Fig. 2a). After transplantation of the selected clones, B and T cells could be detected starting from 4 weeks and 8 weeks, respectively, in peripheral blood (Fig. 2b), suggesting that functional HSCs could be expanded from edited clones. Interestingly, we found that engraftment was associated with high expression of EPCR in the CD150+KL populations of single cell-derived HSC colonies. Conclusion We have shown that functional, Cas9-edited SCID and wildtype HSCs can be expanded in our defined culture system. Corrected SCID HSCs contributed to hematopoietic reconstitution of B and T lineages conferring restored immunity in vivo. Furthermore, we were able to generate transplantable HSCs from single edited clones. This approach has important applications in HSC gene editing and has potential to overcome marker-based selection strategies since individual clones can be interrogated and selected for targeted gene editing events prior to transplantation. Our expansion system will serve as a tool to further the development of targeted gene therapeutic strategies. [1] Wilkinson et al., Nature 571, 117-121 (2019) Disclosures No relevant conflicts of interest to declare.

scholarly journals Regulatory T Cells Fail to Suppress Fast Homeostatic Proliferation In Vitro

Life ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 245
Author(s):  
Daniil Shevyrev ◽  
Valeriy Tereshchenko ◽  
Elena Blinova ◽  
Nadezda Knauer ◽  
Ekaterina Pashkina ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Autoimmune Diseases ◽  
Peripheral Blood ◽  
Treg Cells ◽  
Homeostatic Proliferation ◽  
Suppressive Activity ◽  
Healthy Donors

Homeostatic proliferation (HP) is a physiological process that reconstitutes the T cell pool after lymphopenia involving Interleukin-7 and 15 (IL-7 and IL-15), which are the key cytokines regulating the process. However, there is no evidence that these cytokines influence the function of regulatory T cells (Tregs). Since lymphopenia often accompanies autoimmune diseases, we decided to study the functional activity of Tregs stimulated by HP cytokines from patients with rheumatoid arthritis as compared with that of those from healthy donors. Since T cell receptor (TCR) signal strength determines the intensity of HP, we imitated slow HP using IL-7 or IL-15 and fast HP using a combination of IL-7 or IL-15 with anti-CD3 antibodies, cultivating Treg cells with peripheral blood mononuclear cells (PBMCs) at a 1:1 ratio. We used peripheral blood from 14 patients with rheumatoid arthritis and 18 healthy volunteers. We also used anti-CD3 and anti-CD3 + IL-2 stimulation as controls. The suppressive activity of Treg cells was evaluated in each case by the inhibition of the proliferation of CD4+ and CD8+ cells. The phenotype and proliferation of purified CD3+CD4+CD25+CD127lo cells were assessed by flow cytometry. The suppressive activity of the total pool of Tregs did not differ between the rheumatoid arthritis and healthy donors; however, it significantly decreased in conditions close to fast HP when the influence of HP cytokines was accompanied by anti-CD3 stimulation. The Treg proliferation caused by HP cytokines was lower in the rheumatoid arthritis (RA) patients than in the healthy individuals. The revealed decrease in Treg suppressive activity could impact the TCR landscape during lymphopenia and lead to the proliferation of potentially self-reactive T cell clones that are able to receive relatively strong TCR signals. This may be another explanation as to why lymphopenia is associated with the development of autoimmune diseases. The revealed decrease in Treg proliferation under IL-7 and IL-15 exposure can lead to a delay in Treg pool reconstitution in patients with rheumatoid arthritis in the case of lymphopenia.

scholarly journals FOXP3 expression accurately defines the population of intratumoral regulatory T cells that selectively accumulate in metastatic melanoma lesions

Blood ◽  
2008 ◽  
Vol 112 (13) ◽  
pp. 4953-4960 ◽  
Author(s):  
Mojgan Ahmadzadeh ◽  
Aloisio Felipe-Silva ◽  
Bianca Heemskerk ◽  
Daniel J. Powell ◽  
John R. Wunderlich ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Microenvironment ◽  
Metastatic Melanoma ◽  
Treg Cell ◽  
Peripheral Blood ◽  
Ex Vivo ◽  
Production Capacity ◽  
Biological Marker ◽  
Foxp3 Expression ◽  
Treg Cells

Abstract Regulatory T (Treg) cells are often found in human tumors; however, their functional characteristics have been difficult to evaluate due to low cell numbers and the inability to adequately distinguish between activated and Treg cell populations. Using a novel approach, we examined the intracellular cytokine production capacity of tumor-infiltrating T cells in the single-cell suspensions of enzymatically digested tumors to differentiate Treg cells from effector T cells. Similar to Treg cells in the peripheral blood of healthy individuals, tumor-infiltrating FOXP3+CD4 T cells, unlike FOXP3− T cells, were unable to produce IL-2 and IFN-γ upon ex vivo stimulation, indicating that FOXP3 expression is a valid biological marker for human Treg cells even in the tumor microenvironment. Accordingly, we enumerated FOXP3+CD4 Treg cells in intratumoral and peritumoral sections of metastatic melanoma tumors and found a significant increase in proportion of FOXP3+CD4 Treg cells in the intratumoral compared with peritumoral areas. Moreover, their frequencies were 3- to 5-fold higher in tumors than in peripheral blood from the same patients or healthy donors, respectively. These findings demonstrate that the tumor-infiltrating CD4 Treg cell population is accurately depicted by FOXP3 expression, they selectively accumulate in tumors, and their frequency in peripheral blood does not properly reflect tumor microenvironment.

scholarly journals Itolizumab As a Potential Therapeutic for the Prevention and Treatment of Graft Vs Host Disease

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5603-5603 ◽  
Author(s):  
Cherie Tracy Ng ◽  
Jeanette Ampudia ◽  
Robert J. Soiffer ◽  
Jerome Ritz ◽  
Stephen Connelly
Keyword(s):  
Weight Loss ◽  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Research Funding ◽  
Chronic Gvhd ◽  
Vehicle Control ◽  
Control Group ◽  
Employment Equity ◽  
Equity Ownership

Background: CD6 is a co-stimulatory receptor, predominantly expressed on T cells, that binds to activated leukocyte cell adhesion molecule (ALCAM), a ligand expressed on antigen presentation cells and various epithelial and endothelial tissues. The CD6-ALCAM pathway plays an integral role in modulating T cell activation, proliferation, differentiation and trafficking and is central to inflammation. While effector T cell (Teff) are CD6hi and upregulate expression upon activation, regulatory T cells (Treg) remain CD6lo/-, making this an attractive target to modulate Teff activity while preserving Treg activity. Early studies by Soiffer and colleagues demonstrated using T12, an anti-CD6 monoclonal antibody (mAb) that ex-vivo depletion of CD6+ donor cells prior to transplantation decreased the incidence of both acute and chronic GVHD, highlighting the importance of CD6+ cells in GVHD pathogenesis and validating it as a therapeutic target. However, it remains to be shown whether modulating the CD6-ALCAM pathway in vivo can attenuate GVHD. We investigated the use of itolizumab, a humanized anti-CD6 mAb that has demonstrated clinical efficacy in other autoimmune diseases, as both a preventive and therapeutic treatment for GVHD, using a humanized xenograft mouse model. Methods: Humanized xenograft mice were generated by intravenous transfer of 2x10^7 human PBMCs into 6-8 weeks old NOD/SCID IL2rγ-null (NSG). To investigate the ability of itolizumab to prevent GVHD, mice were dosed with either 60μg or 300μg of itolizumab, 150μg of abatacept (CTLA4-Ig), or vehicle, starting one day prior to PBMC transplantation. To investigate the therapeutic effect of itolizumab, mice were dosed with either 150μg of itolizumab or vehicle, starting at Day 5 post-PBMC transfer, when transplanted T cells are already activated. All treatments were administered IP every other day. Weight and disease scores were monitored throughout the study. At Days 18 and 35, peripheral blood was evaluated by flow cytometry to examine T cell prevalence, and tissues were collected for histological examination of pathology and T cell infiltration. Results: When administered as prevention (Day -1), treatment with either 60μg or 300μg of itolizumab significantly decreased mortality compared to the vehicle control (100% vs. 10%); this decrease was similar to the positive control group treated with abatacept (Figure 1). At 60μg, itolizumab-treated mice demonstrated significant reductions in the prevalence of human T cells in peripheral blood vs. vehicle-treated mice at Day 18 (<0.2% vs. 74.5%; p < 0.001). The reduction in peripheral T cells was accompanied by reductions in tissue-infiltrating T cells in lung (85-fold) and gut (9.5-fold), as well as reductions in disease scores and weight loss. When administered therapeutically, treatment with itolizumab was associated with a survival rate of 50% compared to 10% in the control group (Figure 2). Similarly, peripheral T cell prevalence (34.3% vs. 65.1%; p < 0.001), weight loss, and disease scores were inhibited by itolizumab compared to vehicle control mice. Conclusions: These data suggest that systemic treatment with itolizumab can modulate pathogenic Teff cell activity, establishing this antibody as a potential therapeutic for patents with GvHD. A phase I/II study using itolizumab as first line treatment in combination with steroids for patients with aGVHD is currently ongoing (NCT03763318). Disclosures Ng: Equillium: Employment, Equity Ownership. Ampudia:Equillium: Employment. Soiffer:Mana therapeutic: Consultancy; Kiadis: Other: supervisory board; Gilead, Mana therapeutic, Cugene, Jazz: Consultancy; Juno, kiadis: Membership on an entity's Board of Directors or advisory committees, Other: DSMB; Cugene: Consultancy; Jazz: Consultancy. Ritz:Equillium: Research Funding; Merck: Research Funding; Avrobio: Consultancy; TScan Therapeutics: Consultancy; Talaris Therapeutics: Consultancy; Draper Labs: Consultancy; LifeVault Bio: Consultancy; Celgene: Consultancy; Aleta Biotherapeutics: Consultancy; Kite Pharma: Research Funding. Connelly:Equillium: Employment, Equity Ownership.

scholarly journals Ionizing radiation modulates the phenotype and function of human CD4+ induced regulatory T cells

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Samantha S. Beauford ◽  
Anita Kumari ◽  
Charlie Garnett-Benson
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Ionizing Radiation ◽  
Cancer Cells ◽  
Tumor Immunity ◽  
Foxp3 Expression ◽  
Cytotoxic T Cell ◽  
Suppressive Activity ◽  
Tgf Β1

Abstract Background The use of immunotherapy strategies for the treatment of advanced cancer is rapidly increasing. Most immunotherapies rely on induction of CD8+ tumor-specific cytotoxic T cells that are capable of directly killing cancer cells. Tumors, however, utilize a variety of mechanisms that can suppress anti-tumor immunity. CD4+ regulatory T cells can directly inhibit cytotoxic T cell activity and these cells can be recruited, or induced, by cancer cells allowing escape from immune attack. The use of ionizing radiation as a treatment for cancer has been shown to enhance anti-tumor immunity by several mechanisms including immunogenic tumor cell death and phenotypic modulation of tumor cells. Less is known about the impact of radiation directly on suppressive regulatory T cells. In this study we investigate the direct effect of radiation on human TREG viability, phenotype, and suppressive activity. Results Both natural and TGF-β1-induced CD4+ TREG cells exhibited increased resistance to radiation (10 Gy) as compared to CD4+ conventional T cells. Treatment, however, decreased Foxp3 expression in natural and induced TREG cells and the reduction was more robust in induced TREGS. Radiation also modulated the expression of signature iTREG molecules, inducing increased expression of LAG-3 and decreased expression of CD25 and CTLA-4. Despite the disconcordant modulation of suppressive molecules, irradiated iTREGS exhibited a reduced capacity to suppress the proliferation of CD8+ T cells. Conclusions Our findings demonstrate that while human TREG cells are more resistant to radiation-induced death, treatment causes downregulation of Foxp3 expression, as well as modulation in the expression of TREG signature molecules associated with suppressive activity. Functionally, irradiated TGF-β1-induced TREGS were less effective at inhibiting CD8+ T cell proliferation. These data suggest that doses of radiotherapy in the hypofractionated range could be utilized to effectively target and reduce TREG activity, particularly when used in combination with cancer immunotherapies.

Generation of Regulatory T Cells through Intravenous Delivery of Autologous Apoptotic Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2390-2390
Author(s):  
David Peritt ◽  
Kim Campbell ◽  
Amy Krutsick ◽  
Janine Huber ◽  
Ulrich Thienel ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Ex Vivo ◽  
Contact Hypersensitivity ◽  
Phase Iii ◽  
Apoptotic Cells ◽  
Phase Ii Trials

Abstract Extracorporeal photopheresis (ECP) is approved for the palliative treatment of skin manifestations associated with cutaneous T cell lymphoma. As reported in the literature, ECP has shown promise as a treatment for such immune-mediated inflammatory disorders as graft versus host disease, transplantation rejection, and autoimmune diseases. ECP involves the reinfusion of autologous, apoptotic peripheral blood leukocytes treated ex vivo with 8-methoxypsoralen (8-MOP) and UVA light. The biological mechanism of action of ECP, however, remains unresolved. We have evidence to suggest that delivery of ECP-treated apoptotic cells modulates immune responses, possibly through generation of regulatory T cells. When co-incubated with ECP-treated cells, activated dendritic cells produce reduced levels of proinflammatory cytokines, such as IL-12, while TGFβ levels were modestly increased. Activation of CD4+ T cells in the presence of allogeneic dendritic cells and ECP-treated cells promotes generation of a population of T cells that can suppress proliferation of, and IFNγ production by, naïve syngeneic T cells. To confirm these findings in vivo, we employed a murine contact hypersensitivity model. ECP-treated or control spleen and lymph node cells from mice sensitized with the hapten dinitrofluorobenzene (DNFB) were injected intravenously into naïve recipients. Compared to controls, mice that received ECP-treated cells demonstrated significantly less ear swelling following sensitization and challenge with DNFB. Suppression of ear swelling was specific for DNFB and cell-mediated, as demonstrated by the ability to transfer DNFB tolerance to naïve mice, which could appropriately respond to the unrelated hapten oxazalone. Transfer of this tolerance was abrogated by depletion of either CD4+ or CD25+ T cell populations. Collectively, these results suggest that delivery of ECP-treated cells promotes the generation of regulatory T cells that are capable of modulating immune responses. Therakos sponsored Phase II trials for the prevention and treatment of GvHD are concluding and an international blinded pivotal phase III study is planned for 2005.

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