Pharmacologic Co-Blockade of IFNγR and IL6R Pathways to Prevent and Treat GvHD

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3353-3353 ◽  
Author(s):  
Jaebok Choi ◽  
Matthew L Cooper ◽  
Kiran R. Vij ◽  
Bing Wang ◽  
Julie Ritchey ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Hematopoietic Stem ◽  
Therapeutic Benefits ◽  
In Vivo Administration ◽  
Jak2 Inhibitors

Abstract The therapeutic benefits of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for hematologic malignancies are primarily derived from an anti-leukemia effect that is mediated by T cells in donor grafts. Unfortunately, these T cells also mediate graft-versus-host disease (GvHD), the major complication of allo-HSCT. We have previously published that in vivo administration of JAK1/JAK2 inhibitors to murine allo-HSCT recipients of interferon gamma receptor deficient (IFNγR-/-) T cells results in 100% survival in a fully MHC-mismatched B6 to Balb/c allo-HSCT model (Choi et al., 2014, PLoS ONE). Since the infusion of IFNγR-/- T cells alone is associated with only ~70% survival, we hypothesize that JAK1/JAK2 inhibitors have either additional off-target effects or are inhibiting other non-IFNγR signaling pathways which are themselves dependent on JAK1/JAK2. The major other cytokine receptor signaling pathway mediated via both JAK1 and JAK2 is the interleukin 6 receptor (IL6R) signaling pathway. Thus, it is possible that JAK1/JAK2 inhibitors also block signaling through IL6R in addition to IFNγR. In addition, Alam et al. have recently reported that single nucleotide polymorphisms of donor IFNγ and IL6 are closely linked to gastrointestinal GvHD in patients (2015, BMT). Therefore, we examined if blockade of both IFNγR and IL6R signaling results in complete elimination of GvHD after a fully MHC-mismatched allo-HSCT in which B6 (H-2b) T cell-depleted bone marrow cells (5x106) along with B6 pan T cells (5x105) are intravenously injected into lethally irradiated Balb/c mice (H-2d). As shown in Fig. 1, we have found that blocking both IFNγR (IFNγR-/- T cells) and IL6R (α-IL6R Ab) signaling dramatically reduces GvHD and results in >95% survival. In addition, we found that blocking both IFNγR and IL6R signaling significantly increased regulatory T cells (Tregs) in peripheral blood (23.2% Foxp3+ in CD4+ T cells (n=17) vs 2.5% in WT T cell control (n=16) at day 27 after allo-HSCT), suggesting that increase in Tregs might be a potential mechanism underlying the reduced GvHD after dual blockade of IFNγR and IL6R signaling. Baricitinib is a potent and balanced JAK1/JAK2 inhibitor currently being clinically developed by Eli Lilly for the treatment of inflammatory diseases. We hypothesize that baricitinib will optimally block both IFNγR and IL6R signaling pathways and prevent GvHD. We found that that baricitinib is a potent suppressor of GvHD in B6 to Balb/c allo-HSCT models (100% survival), superior to ruxolitinib and similar to blockade of both IFNγR and IL6R signaling (Fig. 2A). Baricitinib increases Tregs in vivo (Fig. 2B) and reduces the ratio of IL5 (Th2 cytokine) to IL2 (cytokine for Treg induction) in plasma (p=0.0046), a potential diagnostic marker for GvHD (Fujii et al., 2006, Int J Mol Med), significantly better than ruxolitinib. Lastly, we found that baricitinib inhibits the expression of T-bet (Fig. 2C), which is the master transcription factor of Th1 cells, that are primary effector T cells in inducing GvHD. These data suggest that the suppression of GvHD by baricitinib results from increased Tregs and decreased Th1 and Th2 cells. We next examined if the prevention of GvHD by baricitinib is dependent on natural regulatory T cells (Tregs) in donor grafts. Tregs were depleted from donor pan T cells before allo-HSCT (B6 to Balb/c). We found that in vivo administration of baricitinib resulted in 70% survival (0% control, p<0.0001; 100% Treg-replete T cells + baricitinib. In addition, based on clinical GvHD score when recipients of Treg-replete T cells were compared with those of Treg-deplete T cells, the beneficial effect of Tregs in the donor grafts for the prevention of GvHD was observed only for the first two weeks after allo-HSCT (p≤0.01). Lastly, we examined whether baricitinib can cure ongoing GvHD by administering baricitinib starting at day 10 after allo-HSCT when GvHD is established (B6 to Balb/c). We found that baricitinib treatment results in a significant reduction of GvHD and 100% survival (10% control, p<0.0001). All of these data suggest that pharmacologic co-blockade of IFNγR and IL6R pathways is a promising therapeutic strategy to prevent and effectively treat established GvHD. The inhibitory effect of baricitinib, ruxolitinib, and blockade of IFNγR and IL6R on JAK-STAT signaling using JAK/STAT phosphorylation antibody arrays is currently being investigated and will be presented. Disclosures DiPersio: Incyte Corporation: Research Funding.

Chimeric Regulatory T cells Enhance HSC Engraftment in An Antigen-Specific Fashion.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2424-2424
Author(s):  
Yiming Huang ◽  
Larry D Bozulic ◽  
Thomas Miller ◽  
Hong Xu ◽  
Yujie Wen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Third Party ◽  
T Cell Proliferation ◽  
Hematopoietic Stem ◽  
Mixed Chimeras

Abstract Abstract 2424 Poster Board II-401 We previously reported that CD8+TCR- facilitating cells (FC) induce the generation of chimeric regulatory T cells (Treg) in vivo. Transplantation of a mixture of CD8+/TCR- FC and hematopoietic stem cells (HSC) into ablated recipients results in chimerism and tolerance. Treg harvested from the spleen of chimeras (chimeric Treg) potently increase long-term donor chimerism in secondary NOD recipient mice. Here, we evaluated whether chimeric Treg enhance engraftment of hematopoietic stem cells (HSC) in an antigen-specific manner. To prepare mixed chimeras (B6 → NOD), NOD recipients were conditioned with 950 cGy TBI and transplanted with 10,000 B6 HSC and 1,000 NOD HSC plus 45,000 CD8+TCR- B6 FC. At 5 weeks, CD8-CD4+CD25bright chimeric Treg were sorted from spleens of the mixed chimeras (B6 → NOD). 100,000 chimeric Treg were then mixed with 10,000 B6 HSC (donor-specific) + 10,000 B10.BR HSC (third-party) and transplanted into conditioned NOD recipients in competitive repopulation assays. NOD mice given HSC plus nonchimeric naïve B6 Treg or HSC alone served as controls. Two of the four animals that received HSC alone engrafted and exhibited an average of 6.7% donor B6 chimerism at 30 days, 11.2% at 60 days, and 10.6% at 90 days. Three of five animals given HSC plus naïve B6 Treg engrafted with 21.3% donor B6 chimerism at 30 days, 28.8% at 60 days, and 28.9% at 90 days. In contrast, eight of nine recipients of HSC + chimeric Treg engrafted. These animals exhibited a significantly higher level of donor B6 chimerism, ranging from 56.3% at 30 days, 75.4% at 60 days to 85% at 90 days (P = 0.034). None of the recipients engrafted with the MHC-disparate third-party B10.BR HSC. We then assessed the suppressive function of chimeric Tregin vitro by using MLR suppressor cell assays. CD8-/CD4+/CD25bright Treg were sorted from chimeric spleens 5 wks to 12 wks after HSC + FC transplantation. As shown in the Figure 1, Treg from naïve B6 mice resulted in 1.9 fold; 1.3 fold and 1.1 fold inhibition of proliferation at 1:1, 1:0.25, 1:0.125 responder/Treg ratios (n = 3). In contrast, chimeric Treg potently suppressed T cell proliferation by 10.5 fold; 3.2 fold; and 1.7 fold at responder/Treg ratios of 1:1, 1:0.25, 1:0.125 (n = 4). Chimeric Treg significantly suppressed T cell proliferation at responder/Treg ratios of 1:1 and 1:0.25 compared with naïve B6 Treg (P < 0.05). NOD responder splenocytes remained hypoproliferative in response to B6 stimulator and chimeric Treg compared with stimulator plus B6 Treg, suggesting that chimeric Treg are significantly more potent than naïve B6 Treg in suppressing effector T cell proliferation in vitro. These data show that chimeric Treg enhance donor B6 HSC engraftment but not third-party B10.BR HSC, demonstrating that chimeric Treg function in vivo in an antigen-specific fashion. These data also show that the mechanism of FC function in vivo is associated with the establishment of an antigen-specific regulatory feedback loop. Figure 1 Figure 1. Disclosures: Bozulic: Regenerex: Employment. Ildstad:Regenerex: Equity Ownership.

Inhibition of Histone Methylation Arrests Ongoing Graft-Versus-Host Diseases in Mice by Selectively Inducing Apoptosis of Alloreactive Effector T Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 820-820
Author(s):  
Shan He ◽  
Jina Wang ◽  
Koji Kato ◽  
Fang Xie ◽  
Sooryanarayana Varambally ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Histone Methylation ◽  
Effector T Cells ◽  
Hematopoietic Stem ◽  
Graft Versus Host ◽  
Alloreactive T Cells ◽  
Novel Approaches ◽  
In Vivo Administration

Abstract Abstract 820 Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment option for patients with hematological malignancies. However, its success is limited by life-threatening graft-versus-host disease (GVHD). Novel approaches are needed to control GVHD. Recent studies have shown the importance of histone methylation in regulating the expression of genes associated with effector T cell differentiation and proliferation. Using several mouse models of allo-HSCT, we report that in vivo administration of the histone methylation inhibitor 3-Deazaneplanocin A (DZNep) arrested ongoing GVHD while preserving graft-versus-leukemia activity (GVL). To assess the therapeutic effect of pharmacologic modulation of histone methylation on GVHD, we administered DZNep to BALB/c mice receiving major histocompatibility-mismatched C57BL/6 mouse T cells 7 days after transplantation, in which GVHD had been fully established. Notably, injection of 12 doses of DZNep controlled the disease in these recipients, with approximately 80% of them surviving long-term without significant clinical signs of GVHD. We found that in vivo administration of DZNep caused selective apoptosis in alloantigen-activated T cells, but did not impair the generation of effector T cells that produced inflammatory cytokines (e.g., TNF-α, IFN-γ and IL-17) and cytotoxic molecules (e.g., granzyme B and Fas ligand). As a result, alloreactive T cells retained potent GVL activity, leading to improved overall survival of the recipients challenged by leukemic cells. These data suggest that DZNep-mediated inhibition of GVHD may be accounted for by reduced number of alloreactive effector T cells. In vitro culture assays showed that DZNep treatment induced apoptosis in T cells activated by anti-CD3/CD28 antibodies but not in naive T cells stimulated by IL-2 or IL-7. This effect was associated with DZNep's ability to selectively reduce trimethylation of histone H3 lysine 27 (H3K27), deplete the histone methyltranferase Ezh2 that specifically catalyzes trimethylation of H3K27, and activate Ezh2-repressed pro-apoptotic gene Bim. Inactivation of Bim partially protected alloreactive T cells from DZNep-mediated apoptosis. Importantly, unlike DNA methylation inhibitors, inhibition of histone methylation by DZNep had no toxicities to hematopoietic cells or impairment on the reconstitution of hematopoiesis and thymopoiesis. Our findings indicate that modulation of histone methylation may have significant implications in the development of novel approaches to treat established GVHD and other T cell-mediated inflammatory disorders in a broad context. Disclosures: No relevant conflicts of interest to declare.

Anti-Thymocyte Globulin (ATG) Differentially Depletes naïve and Memory T Cells and Permits Memory-Type Regulatory T Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4670-4670
Author(s):  
Chang-Qing Xia ◽  
Anna Chernatynskaya ◽  
Clive Wasserfall ◽  
Benjamin Looney ◽  
Suigui Wan ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Cd8 T Cells ◽  
Peripheral Blood ◽  
Memory T Cells ◽  
Conflicts Of Interest ◽  
T Cell Subsets ◽  
Hematopoietic Stem

Abstract Abstract 4670 Anti-thymocyte globulin (ATG) has been used in clinic for the treatment of allograft rejection and autoimmune diseases. However, its mechanism of action is not fully understood. To our knowledge, how ATG therapy affects naïve and memory T cells has not been well investigated. In this study, we have employed nonobese diabetic mouse model to investigate how administration of anti-thymocyte globulin (ATG) affects memory and naïve T cells as well as CD4+CD25+Foxp3+ regulatory T cells in peripheral blood and lymphoid organs; We also investigate how ATG therapy affects antigen-experienced T cells. Kinetic studies of peripheral blood CD4+ and CD8+ T cells post-ATG therapy shows that both populations decline to their lowest levels at day 3, while CD4+ T cells return to normal levels more rapidly than CD8+ T cells. We find that ATG therapy fails to eliminate antigen-primed T cells, which is consistent with the results that ATG therapy preferentially depletes naïve T cells relative to memory T cells. CD4+ T cell responses post-ATG therapy skew to T helper type 2 (Th2) and IL-10-producing T regulatory type 1 (Tr1) cells. Intriguingly, Foxp3+ regulatory T cells (Tregs) are less sensitive to ATG depletion and remain at higher levels following in vivo recovery compared to controls. Of note, the frequency of Foxp3+ Tregs with memory-like immunophenotype is significantly increased in ATG-treated animals, which might play an important role in controlling effector T cells post ATG therapy. In summary, ATG therapy may modulate antigen-specific immune responses through modulation of naïve and memory T cell pools and more importantly through driving T cell subsets with regulatory activities. This study provides important data for guiding ATG therapy in allogenieic hematopoietic stem cell transplantation and other immune-mediated disorders. Disclosures: No relevant conflicts of interest to declare.

Functional Comparison of Freshly Isolated and Ex-Vivo Expanded CD4+CD25+Foxp3+ Regulatory T Cells in Suppressing Murine Acute GvHD

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 812-812 ◽  
Author(s):  
Emanuela I Sega ◽  
Dennis Leveson-Gower ◽  
Vu H. Nguyen ◽  
Robert Negrin
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Acute Gvhd ◽  
Bone Marrow Cells ◽  
Ex Vivo ◽  
Allogeneic Bone ◽  
Cell Reactivity ◽  
Hematopoietic Stem

Abstract Graft versus host disease (GVHD) is a major complication of hematopoietic stem cell transplantation resulting from donor T cell reactivity against host tissue antigens. CD4+CD25+Foxp3+ regulatory T cells (Treg) are known to be important in maintaining self tolerance and preventing autoimmunity. Using murine models of acute GVHD in which allogeneic bone marrow cells are transplanted into lethally irradiated hosts, we and others have shown that donor Treg are able to suppress GVHD induced by donor allogeneic T cells and dramatically improve survival. Treg are rare and suppression of GVHD requires adequate numbers of Treg in relation to the number of conventional T cells (Tcon). To overcome this problem, expansion of Treg has been performed, however there has not been a head to head comparison of the function of expanded vs fresh Treg. Highly purified CD4+CD25+Foxp3+ T cells (>98% purity) were expanded using anti-CD3/anti-CD28 dynabeads and 1000 U/ml IL-2. Under these conditions, after five days Treg expanded up to 13 fold while maintaining high Foxp3 expression levels (85–90%). Longer expansion periods result in more T cell expansion but an overgrowth of Foxp3 negative T cells. In a mixed lymphocyte reaction assay, the ex-vivo expanded Treg efficiently suppressed the proliferation of alloreactive T cells. The expanded Treg were evaluated in an in vivo acute GVHD mouse model in direct comparison with freshly isolated Treg using a novel bioluminescent imaging assay that allowed for assessment of Tcon proliferation in addition to traditional metrics of GVHD severity including weight gain, survival and GVHD score. Initial experiments show that, similar to freshly isolated Treg, the ex-vivo expanded Treg suppress GVHD symptoms and improve survival, although a greater number of expanded Treg were required comparable to freshly isolated Treg. The mean GVHD score for the Tcon alone group was 5.8±1.02. Fresh Treg added at 1:1 ratio decreased the GVHD score to 0.75±0.25 (p=0.0036). Ex-vivo expanded Treg demonstrated a dose-dependent decrease in GVHD score, although four times more expanded Treg were needed to obtain a similar reduction in GVHD score (0.50±0.5, p=0.0036). This observed difference in potency was not due to the ex-vivo expanded Treg being short-lived when infused in mice. Bioluminescence imaging of luciferase positive (luc+) cultured Treg showed the same in vivo persistence as freshly isolated Treg. The ability to expand ex-vivo generated Treg is greater than the difference in potency, making ex-vivo expanded Treg potentially a viable option for treatment of GVHD, however, increased ratios of Treg:Tcon are likely to be required.

Regulatory T Cells Do Not Affect Human Hematopoietic Stem Cell Engraftment and Prevent T Cell Alloreactivity Against CD34+ Cells: A Preclinical Study.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4870-4870
Author(s):  
Dolores Mahmud ◽  
Sandeep Chunduri ◽  
Nadim Mahmud ◽  
Lennert Van Den Dries ◽  
John J. Maciejewski ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Regulatory T Cells ◽  
Hematopoietic Stem ◽  
Cell Engraftment ◽  
Cd34 Cells ◽  
Intracellular Expression

Abstract We have previously demonstrated that allogeneic blood T cells stimulate cord blood (CB) CD34+ cell differentiation into professional antigen presenting cells (APC) in-vitro and in-vivo (Abbasian J, Blood2006:108:203–208). In this study we immunomagnetically selected human CD4+CD25+ regulatory T cells (Tregs) and showed that >80% of these cells were positive for FoxP3 intracellular expression. Then we tested whether Tregs may affect CB CD34+ cell clonogenic activity in-vitro an in-vivo, and if co-incubation of Tregs and CD34+ cells may modify the phenotype and function of Tregs. A colony-forming cells (CFU-C) assay performed with CD34+ cells mixed with allogeneic Tregs at 1:2 ratio resulted in comparable numbers of Granulocyte- Macrophage CFU (CFU-GM), burst-forming unit-erythroid (BFU-E) and CFU-Mix as compared to cultures with CD34+ cells alone (p=0.2, p=0.5 and p=0.5, respectively)(n=3 exps). Human CD34+ cells were co-transplanted with human CD4+CD25+ allogeneic Tregs into NOD/SCID mice at 1:1 and 1:2 ratio. After 6 weeks mice marrow was harvested and showed a 1.3±1.1% (n=3 mice) and 1.6±0.8% (n=4 mice) engraftment of huCD45+ cells, respectively, which was comparable to the engraftment observed in control animals transplanted with CD34+ cells alone (1.4±0.4). In addition, among the engrafted huCD45+ cells similar proportion of CD33+ myeloid cells, CD14+ monocytes and CD1c+ dendritic cells were observed in the three groups of animals. Mixed lymphocyte culture (MLC) experiments showed that irradiated CD34+ cells stimulated brisk proliferative responses of CD4+CD25- cells (S:R=1:2), but did not induce any proliferation of Tregs (n=3 exps). After incubation with CD34+ cells in the presence of IL2, on average >80% CD4+CD25+ cells maintained the intracellular expression of FoxP3 and surface expression of CD62L and CD152 (n=3 exps). Then, Tregs autologous to CD34+ cells were isolated from the CB CD34- cell fraction while allogeneic Tregs were isolated from healthy individuals’ peripheral blood. When 2.5 x 104 autologous or allogeneic Tregs were added to an MLC with 2.5 x 104 irradiated CD34+ stimulator cells and allogeneic responders at 1:2 ratio, they suppressed T cell alloreactivity to CD34+ cells on average by 68±14% and 41±16%, respectively (n=3 exps). Our findings suggest that co-transplantation of CD34+ cells and autologous or allogeneic Tregs may allow normal stem cell engraftment while limiting T cell alloreactivity. These results will prompt the design of new strategies in allogeneic hematopoietic stem cell transplantation, particularly in an HLA incompatible setting.

The Absence of CC-Chemokine Receptor 8 on Donor Regulatory T Cells Impairs Their Ability to Prevent Lethal Acute Gvhd.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3743-3743 ◽  
Author(s):  
James M. Coghill ◽  
Michelle L. West ◽  
Donald N. Cook ◽  
Jonathan S. Serody
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Fluorescence Microscopy ◽  
Chemokine Receptor ◽  
Recipient Site ◽  
Hematopoietic Stem ◽  
Cc Chemokine

Abstract Abstract 3743 CC-Chemokine receptor 8 (CCR8) is a chemokine receptor expressed on the surfaces of activated effector T cells (Teffs) and resting regulatory T cells (Tregs). CCR8 has previously been shown to play a role in the trafficking of memory T cells into cutaneous and possibly pulmonary sites, and to contribute to the ability of Tregs to properly interact with antigen presenting cells within secondary lymphoid tissue. Since the lungs and in particular the skin are frequent sites of tissue injury in those developing graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT), we set out to study the contribution of CCR8 to GVHD pathogenesis using a haploidentical murine HSCT model. Given the emerging utilization of therapeutic donor Treg infusions as a means for preventing GVHD, we also explored the role that CCR8 plays in the protective immunosuppressive function of Tregs in the HSCT setting. Methods: For our studies we used a haplotype-matched murine transplant model. C57BL/6 mice (B6; H-2b) functioned as donors, and B6 × DBA2 (B6D2; H-2bxd) mice served as recipients. For Teff studies, B6D2 mice were lethally irradiated to 950 rads on transplant day -1, and then administered 3×106 T cell depleted (TCD) B6 bone marrow (BM) cells +/− 4×106 CD25− Teffs isolated from the spleens of wild-type (WT) or CCR8−/− B6 mice on day 0. For studies involving regulatory T cells, B6D2 animals were lethally irradiated on day -1 and administered WT B6 TCD BM cells +/− 1–1.25×106 CD4+CD25+ Tregs isolated from WT or CCR8−/− B6 mice on day 0. 4×106 WT B6 Teffs were then administered on transplant day +2. For some transplants, WT B6 and CCR8−/− animals transgenic for enhanced green-fluorescent protein (eGFP+) were used as Teff and/or Treg donors in order to study T cell trafficking following HSCT. Both stereo-fluorescence microscopy and anti-eGFP ELISA approaches were utilized for these in vivo trafficking experiments. The in vitro suppressive potential of WT and CCR8−/− Tregs was evaluated by examining their ability to inhibit Teff proliferation in a one way mixed lymphocyte reaction (MLR). Results: CCR8 was not required for the induction of lethal GVHD, with recipients of CCR8−/− Teffs demonstrating a 100% mortality rate by transplant day +32. However, CCR8 was important for Treg function. In vivo, CCR8−/− Tregs were significantly less effective at preventing GVHD lethality than WT Tregs (see figure; P=0.013 for day +70 survival proportion comparison using Fisher's exact test). When we evaluated donor Treg trafficking on transplant days 6–7 using eGFP+ cells, no significant differences were noted between those animals receiving WT versus CCR8−/− Tregs. By transplant days 9–10, however, a generally higher eGFP signal was observed by stereo-fluorescence microscopy within the lymph nodes of those animals receiving WT eGFP+ Tregs compared to those given CCR8−/− eGFP+ Tregs. In addition, significantly more eGFP was detected by ELISA in the spleens and colons of WT eGFP+ Treg recipients (P=0.0015 and 0.021 respectively for mean total eGFP comparison between WT and CCR8−/− Treg groups by student's t test), and a strong trend for greater WT Treg accumulation was noted within host livers and lungs (P=0.059 and 0.066 respectively). Finally, CCR8−/− Tregs were relatively impaired in their ability to suppress T cell proliferation in vitro compared to WT cells, particularly at higher dilutions. Conclusions: CCR8 is not required for donor Teffs to induce lethal GVHD in our HSCT model. However, CCR8 expression does appear to be important for the function of Tregsin vitro and in vivo, particularly at limiting Treg dilutions. CCR8 is not required for the accumulation of donor Tregs within any one recipient site. Rather, CCR8 appears to globally potentiate the accumulation of donor Tregs within most recipient tissues, with the extent of this effect increasing over time. Future experiments will focus on elucidating a mechanism for this finding. Disclosures: No relevant conflicts of interest to declare.

Differential Targeting of Signaling Pathways to Selectively Expand Mouse Regulatory T Cells While Inhibiting Conventional T Cells.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2158-2158
Author(s):  
Atsushi Satake ◽  
Amanda M Schmidt ◽  
Angela Archambault ◽  
Gregory F Wu ◽  
Taku Kambayashi
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Signaling Pathways ◽  
Conflicts Of Interest ◽  
Therapeutic Potential ◽  
Negative Effects ◽  
Tcr Signaling

Abstract Abstract 2158 Regulatory T cells (Tregs) are suppressive T cells with therapeutic potential for ameliorating T cell-mediated diseases. Thus, there has been great interest in revealing the mechanisms by which Tregs proliferate. Recently, we reported that TCR signaling is partially dispensable for Treg proliferation in vivo when exogenous IL-2 is administered. Based on this data, we hypothesized that when given in conjunction with IL-2, pharmacological inhibition of TCR signaling might allow Tregs to expand while simultaneously inhibiting conventional T cell (Tconv) proliferation. Using mutant mice with defective TCR-mediated PLCγ activation, we found that the activation of PLCγ is dispensable for IL-2-mediated Treg proliferation. In contrast, costimulation-derived mTOR signaling was required for IL-2-induced Treg proliferation. We next used Cyclosporine A (CSA; calcineurin inhibitor) and rapamycin (mTOR inhibitor) to differentially target these signaling pathways. Consistent with our hypothesis, while both CSA and rapamycin suppressed antigen-specific Tconv proliferation, only CSA permitted IL-2-induced Treg expansion in vitro and in vivo. Rapamycin, however, did increase the overall Treg:Tconv ratio due to its negative effects on Tconv survival. Given that CSA inhibited antigen-specific Tconv proliferation while maintaining IL-2-induced Treg expansion, we hypothesized that the combination of CSA and IL-2 would be beneficial for attenuating T cell-mediated disease. Indeed, CSA synergized with IL-2 in protection against experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Surprisingly, however, the administration of CSA blocked whereas rapamycin augmented the beneficial effect of IL-2 in graft-versus-host disease (GVHD). These differences potentially results from the overt TCR stimulation that Tregs would receive in the allogeneic (GVHD) vs. syngeneic (EAE) environment. Moreover, inducible Treg (iTreg) generation from allogeneic MHC-stimulated naïve Tconvs contributes greatly to the Treg pool during GVHD. This was consistent with our data showing that rapamycin promotes iTreg generation and allows TCR-enhanced Treg proliferation, whereas CSA inhibited both of these processes. Thus, depending on the disease setting, the signaling pathways contributing to expansion of the Treg pool need to be carefully considered and specifically targeted to increase the Treg:Tconv ratio in treatment of T cell-mediated disorders. Disclosures: No relevant conflicts of interest to declare.

scholarly journals CD4+ regulatory T cells require CTLA-4 for the maintenance of systemic tolerance

2009 ◽  
Vol 206 (2) ◽  
pp. 421-434 ◽  
Author(s):  
Randall H. Friedline ◽  
David S. Brown ◽  
Hai Nguyen ◽  
Hardy Kornfeld ◽  
JinHee Lee ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Cell Function ◽  
Cytotoxic T Lymphocyte ◽  
Critical Role ◽  
Lymphoproliferative Disease ◽  
In Trans ◽  
And Function

Cytotoxic T lymphocyte antigen-4 (CTLA-4) plays a critical role in negatively regulating T cell responses and has also been implicated in the development and function of natural FOXP3+ regulatory T cells. CTLA-4–deficient mice develop fatal, early onset lymphoproliferative disease. However, chimeric mice containing both CTLA-4–deficient and –sufficient bone marrow (BM)–derived cells do not develop disease, indicating that CTLA-4 can act in trans to maintain T cell self-tolerance. Using genetically mixed blastocyst and BM chimaeras as well as in vivo T cell transfer systems, we demonstrate that in vivo regulation of Ctla4−/− T cells in trans by CTLA-4–sufficient T cells is a reversible process that requires the persistent presence of FOXP3+ regulatory T cells with a diverse TCR repertoire. Based on gene expression studies, the regulatory T cells do not appear to act directly on T cells, suggesting they may instead modulate the stimulatory activities of antigen-presenting cells. These results demonstrate that CTLA-4 is absolutely required for FOXP3+ regulatory T cell function in vivo.

scholarly journals P01.02 TLR-mediated suppression of the CCL22-CCR4 axis as a new target for tumor immunotherapy

2021 ◽  
Vol 9 (Suppl 1) ◽  
pp. A3.2-A4
Author(s):  
J Grün ◽  
I Piseddu ◽  
C Perleberg ◽  
N Röhrle ◽  
S Endres ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
Regulatory T Cells ◽  
Type I ◽  
List Type ◽  
Gm Csf

BackgroundUnmethylated CpG-DNA is a potent ligand for the endosomal Toll-like-receptor-9, important for the immune activation to pathogen-associated molecules.1 CpG and other TLR-ligands show effective immunotherapeutic capacities in cancer treatment by inducing an antitumorigenic immunity.2 They are able to reduce tumor progression by reduction of intratumoral secretion of the immunoregulating chemokine CCL223 and subsequent recruitment of immunosuppressive regulatory T cells (Treg), which express CCR4 the only so far known receptor for CCL22.4 Our recent work has shown that CCL22 secretion by dendritic cells (DC) in the lymph node, mediates tolerance by inducing DC-Treg contacts.5 Indeed, in the absence of CCL22, immune responses to vaccination were stronger and resulted in tumor rejection.6 Therefore, we are aiming to investigate the effects of TLR-ligands on systemic CCL22 levels, elucidating all involved mechanisms to identify new targets for cancer immunotherapy.Materials and MethodsT, B and CD11c+ DCs of wildtype (wt) and RAG1-/- mice were isolated from splenocytes by magnetic-activated cell sorting for in vitro assays. Different co-cultures were incubated with CpG and GM-CSF, known as an CCL22 inducer.5 For in vivo experiments, wt mice were treated with CpG, R484 or poly(I:C) alone and in combination with GM-CSF. CCL22-levels in a number of organs were analyzed.ResultsAnalyzing the different immune cell compartments in vitro, we found that DCs in whole splenocytes secrete CCL22 during culture while DC cultured alone showed no CCL22 secretion. When treated with CpG, CCL22-levels were reduced in splenocytes, while it was induced in DC culture alone. The same results were seen when RAG splenocytes, that lack functional B and T cells, were cultured with CpG. CpG treated B cells were able to suppress CCL22 secretion by DC unlike T cells alone. Co-cultures of T and B cells treated with CpG, however, induced the strongest CCL22 suppression in DC. In vivo, we could show that all TLR ligands tested reduced CCL22 in a number of organs significantly. Furthermore, CpG showed the strongest suppression of CCL22 even in the presence of the CCL22 inducer GM-CSF.5ConclusionsWe could show that B cells with T cells mediate CCL22 suppression by TLR ligands. The fact that CpG was able to reduce CCL22 levels even in the presence of the inducer GM-CSF demonstrates the potent CCL22 suppressive capacity of TLR ligands.ReferencesO’Neill LA, et al. The history of toll-like receptors – redefining innate immunity. Nat Rev Immunol 2013;13(6):453–60.Rothenfusser S, et al. Recent advances in immunostimulatory CpG oligonucleotides. Curr Opin Mol Ther 2003;5(2):98–106.Wang S, et al. Intratumoral injection of a CpG oligonucleotide reverts resistance to PD-1 blockade by expanding multifunctional CD8+ T cells. Proc Natl Acad Sci U S A 2016;113(46): E7240–E7249.Rapp M, et al. CCL22 controls immunity by promoting regulatory T cell communication with dendritic cells in lymph nodes. J Exp Med 2019;216(5):1170–1181.Piseddu I, et al. Constitutive expression of CCL22 is mediated by T cell-derived GM-CSF. J Immunol 2020;205(8):2056–2065.Anz D, et al. Suppression of intratumoral CCL22 by type i interferon inhibits migration of regulatory T cells and blocks cancer progression. Cancer Res 2015;75(21):4483–93.Disclosure InformationJ. Grün: None. I. Piseddu: None. C. Perleberg: None. N. Röhrle: None. S. Endres: None. D. Anz: None.

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