scholarly journals Antroquinonol Exerts Immunosuppressive Effect on CD8+ T Cell Proliferation and Activation to Resist Depigmentation Induced by H2O2

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Cuiping Guan ◽  
Qingtian Li ◽  
Xiuzu Song ◽  
Wen Xu ◽  
Liuyu Li ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Hair Follicle ◽  
T Cell Proliferation ◽  
Skin Thickness ◽  
T Cell Infiltration ◽  
Tyrosinase Expression

Antroquinonol was investigated as antioxidant and inhibition of inflammatory responses. Our study was to evaluate its immunosuppressive effect on CD8+ T cells and protective effect on depigmentation. CD8+ T cells were treated with antroquinonol in vitro, and C57BL/6 mice were treated with antroquinonol with or without H2O2 in vivo for 50 consecutive days. We found antroquinonol could inhibit proliferation of CD8+ T cells and suppress the production of cytokines IL-2 and IFN-γ and T cell activation markers CD69 and CD137 in vitro. H2O2 treatment induced depigmentation and reduced hair follicle length, skin thickness, and tyrosinase expression in vivo. Whereas, antroquinonol obviously ameliorated depigmentation of mice skin and resisted the reduction of hair follicle length, skin thickness, and tyrosinase expression induced by H2O2. Antroquinonol decreased CD8+ T cell infiltration in mice skin, inhibited the production of IL-2 and IFN-γ, and decreased the expression of CXCL10 and CXCR3. Summarily, our data shows antroquinonol inhibits CD8+ T cell proliferation in vitro. It also reduces CD8+ T cell infiltration and proinflammatory cytokine secretion and suppresses the thinning of epidermal layer in vivo. Our findings suggest that antroquinonol exerts immunosuppressive effects on CD8+ T cell proliferation and activation to resist depigmentation induced by H2O2.

Abstract 457: Selective Epidermal Growth Factor Receptor Inhibition in Cd4+ T Cells Induces Anergy and Limits Atherosclerosis Development

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Lynda Zeboudj ◽  
Mikael Maître ◽  
Lea Guyonnet ◽  
Ludivine Laurans ◽  
Jeremie Lemarie ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Growth Factor Receptor ◽  
T Cell Proliferation ◽  
T Cell Infiltration ◽  
T Cell Anergy ◽  
Atherosclerosis Development

Background: Several Epidermal Growth Factor receptor (EGFR) inhibitors have been successfully developed for the treatment of cancer. They inhibit tumor cell survival, proliferation and migration. EGFR is also expressed by leukocytes, but little is known about its role in the modulation of the immune response. We aimed to determine whether EGF-R expressed on CD4 + T cells is functional, and to address the consequences of EGF-R inhibition in atherosclerosis, a T cell-mediated chronic inflammatory disease of the vascular wall. Method and Results: Mouse CD4 + T cells expressed Egfr, and the EGFR tyrosine kinase inhibitor AG-1478 blocked in vitro T cell proliferation and Th1/Th2 cytokine production. In vivo , treatment of Ldlr -/- mice with the Egfr inhibitor Erlotinib for 8 weeks induced T cell anergy, reduced T cell infiltration within atherosclerotic lesions and protected against atherosclerosis. Selective deletion of Egfr in CD4 + T cells resulted in decreased T cell proliferation and activation both in vitro and in vivo , as well as reduced IFN-γ, IL-17A, IL-4 and IL-10 production. Atherosclerotic lesion size was reduced by 2-fold in irradiated Ldlr -/- mice reconstituted with bone marrow from Cd4Cre Egfr lox/lox mouse, compared to Cd4Cre Egfr +/+ chimeric mice, after 4, 6 and 12 weeks of high fat diet, associated with marked reduction in T cell infiltration in atherosclerotic plaques. Finally, human blood T cells expressed EGFR and EGFR inhibition reduced T cell proliferation both in vivo and in vitro . Conclusion: EGFR is expressed by human and mouse CD4 + T cells. EGFR pharmacological inhibition or genetic invalidation induced T cell anergy in vitro and in vivo , and reduced atherosclerosis development. Our results suggest that targeting EGFR may be a novel strategy to combat atherosclerosis.

Donor Requirements For CD4+CD25+FoxP3+ Regulatory T Cells Capable Of Suppressing CD4+ and CD8+ Conventional T Cell Proliferation and Graft Versus Host Disease

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4484-4484 ◽  
Author(s):  
Antonio Pierini ◽  
Lucrezia Colonna ◽  
Maite Alvarez ◽  
Dominik Schneidawind ◽  
Byung-Su Kim ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Animal Models ◽  
Graft Versus Host Disease ◽  
Third Party ◽  
T Cell Proliferation ◽  
Graft Versus Host

Adoptive transfer of CD4+CD25+FoxP3+ regulatory T cells (Tregs) prevents graft versus host disease (GvHD) in several animal models and following allogeneic hematopoietic cell transplantation (HCT) in clinical trials. In these models donor derived Tregs have been mainly used as they share the same major histocompatibility complex (MHC) with conventional CD4+ and CD8+ T cells (Tcons) that are primarily responsible for GvHD onset and persistence. Third-party derived Tregs are a promising alternative tool for cellular therapy as they can be prepared in advance, screened for pathogens and activity and banked. In this study we explored MHC disparities between Tregs and Tcons in HCT to evaluate the impact of these different cell populations in GvHD prevention and survival after transplant. Methods and Results We evaluated the ability of highly purified Treg to suppress proliferation of C57BL/6 (H-2b) Tcons following exposure to irradiated splenocytes from BALB/C (H-2d) mice in vitro in a mixed lymphocyte reaction (MLR). Either donor derived C57BL/6 (H-2b) or third party FVB (H-2q) Tregs suppressed Tcon proliferation at the Treg/Tcon ratios of 1:2 and 1:4. The same Treg population effectively suppressed different MHC derived Tcons where BALB/C (H-2d) or FVB (H-2q, third-party) Tcons were incubated with irradiated splenocytes from C57BL/6 (H-2b) mice and were effectively suppressed with BALB/C (H-2d) Tregs. In the MLR, third-party Tregs present the same activation molecule expression patterns as MHC matched Tregs: CTLA4 and LAG3 expression is enhanced after stimulation with interleukin-2 (IL-2) and anti-CD3/CD28 beads, while MHC class II molecule expression is increased after 3-4 days of culture with Tcons and irradiated splenocytes. Furthermore third-party and MHC matched Tregs express the same levels of interleukin-10 (IL-10). We translated these results to in vivo studies in animal models. In these studies T cell depleted bone marrow (TCD BM) from C57BL/6 (H-2b) mice was injected into lethally irradiated (total body irradiation, 8 Gy) BALB/C (H-2d) recipient mice. 2 days later GvHD was induced by injecting luc+ donor derived Tcons (1x106/mouse). Using this model GvHD was evaluated following the adoptive transfer of freshly isolated CD4+CD25+FoxP3+ Tregs derived from BALB/C (H-2d, host type), C57BL/6 (H-2b, donor type), FVB (H-2q, third-party) or BALB/B (H-2b, minor mismatched with the donor, major mismatched with the host) mice at the different Treg/Tcon ratios of 1:1, 1:2 and 1:4. As expected, donor Tregs exerted the strongest dose dependent GvHD protection (p = 0.028), while host Tregs did not improve mouse survival (p = 0.58). Third-party and minor mismatched with the donor Tregs improved mouse survival (third-party and minor mismatched with the donor respectively, p = 0.028 and p = 0.17) but mice had worse GvHD score profiles (both p< 0.001) and could not recover their weight as well as mice treated with donor Tregs (both p< 0.001). In vivoTcon bioluminescent imaging confirmed these results showing a reduced Tcon proliferation in mice treated with donor, third-party and minor mismatched with the donor Tregs, the first exerting the strongest effect (after 6 weeks of observation, p< 0.001). Conclusions Our studies indicate that MHC disparities between Tregs and Tcons do not represent an insurmountable barrier for Treg function. In vitro and in vivo data strongly suggest that Tregs can suppress Tcon proliferation without requiring MHC matching. In vivo GvHD prevention efficiency was affected by MHC disparities with donor derived Treg being the most effective, however, third party Treg also resulted in GvHD attenuation. These studies indicate that both donor and third party Treg could be effective in clinical application raising the possibility of screening and banking Treg for use. Further, these studies highlight the need for activation of the Treg on host tissues to effectively suppress conventional T cell proliferation and GvHD induction. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Targeting Antigen Presenting   Cells to Treat Autoimmune  Inflammation

2021 ◽  
Author(s):  
◽  
Aras Toker
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Mhc Class Ii ◽  
T Cell Proliferation ◽  
Target Cells ◽  
Antigen Presenting

<p>Glatiramer acetate (GA) is approved for the treatment of relapsing-remitting multiple sclerosis (MS), and can suppress experimental autoimmune encephalomyelitis (EAE), a murine model of human MS. GA treatment is associated with the induction of anti-inflammatory TH2 responses and with the antigen specific expansion of regulatory T cells that counteract or inhibit pathogenic events in MS and EAE. These T cell mediated mechanisms of protection are considered to be a result of modulation of antigen presenting cells (APCs) by GA, rather than direct effects on T cells. However, it is unknown if GA preferentially targets a specific APC subset or can act through multiple APCs in vivo. In addition, GA-modulated innate cells may also exhibit direct antigen non-specific suppression of autoreactive cells. One objective of this study was to identify the in vivo target cell population of GA and to assess the potential of the target cells to antigen non-specifically suppress immune responses. Fluorophor-labelled GA bound to monocytes after intravenous injections, suggesting that monocytes may be the primary target of GA in vivo. In addition, intravenous GA treatment enhanced the intrinsic ability of monocytes to suppress T cell proliferation, both in vitro and in vivo. The findings of this study therefore suggest that GA-induced monocytes may contribute to GA therapy through direct mechanisms of antigen non-specific T cell immunosuppression. A further objective of this work was to investigate the potential of an in vivo drug targeting approach. This approach was hypothesised to increase the uptake of GA by the target cells and substantially improve GA treatment through antigen specific mechanisms such as induction of TH2 or regulatory T cells. Targeting antigens to professional APCs with an anti-MHC class II antibody resulted in significantly enhanced T cell proliferation in vitro. However, no EAE suppression occurred when GA was targeted to MHC class II in vivo. In addition, targeting GA specifically to monocytes also failed to suppress EAE. These findings suggest that GA treatment may selectively modulate monocytes to enhance their ability to inhibit autoreactive T cells, which could be part of the mechanism by which GA ameliorates MS. Targeting GA to a specific cell type may not be a powerful approach to improve treatment, because increased proliferation of GA specific T cells is not sufficient for disease suppression, and conjugation to antibodies may functionally reduce GA to a mere antigen devoid of immunomodulatory capacity.</p>

Effect of In Vivo Azacitidine on GvHD and Gvl: Mechanistic Studies

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2537-2537
Author(s):  
Jaebok Choi ◽  
Julie Ritchey ◽  
Jessica Su ◽  
Julie Prior ◽  
Edward Ziga ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Leukemia Cell ◽  
T Cell Proliferation ◽  
Cell Trafficking ◽  
Alloreactive T Cells ◽  
Donor T Cells

Abstract Abstract 2537 Introduction: Regulatory T cells (Tregs) have been shown to mitigate graft-versus-host disease (GvHD) while preserving the beneficial graft-versus-leukemia (GvL) effect in animal models of allogeneic bone marrow transplantation (BMT). However, three major obstacles prevent their use in human clinical trials: the low numbers of Tregs, loss of suppressor activity following in vitro expansion, and the lack of Treg-specific markers to purify expanded Tregs. The locus of the Foxp3 gene, the master regulator of Tregs, is unmethylated and expressed only in Tregs. We have recently reported that the hypomethylating agent azacitidine (AzaC) induces FOXP3 expression in non-Tregs, converting them into Tregs in vitro and in vivo when administered after allogeneic BMT completely mitigating GvHD without abrogating GvL (Choi, et al Blood 2010). Three possible mechanisms for these effects include: 1) AzaC induces FOXP3+ Tregs, which in turn mitigate GvHD without abrogating GvL by regulating alloreactive donor T cells, 2) AzaC directly suppresses the proliferation of alloreactive donor T cells reducing GvHD, 3) AzaC alters donor T cell trafficking to GvHD target organs to prevent GvHD without altering interaction of donor T cells with recipient leukemia or trafficking of leukemic cells. Methods: Balb/c (CD45.2+, H-2Kd) were lethally irradiated one day prior to injection of T cell-depleted BM cells isolated from B6 (CD45.1+, H-2Kb) and luciferase-expressing A20 leukemia cells derived from Balb/c. Allogeneic donor T cells isolated from B6 (CD45.2+, H-2Kb) were given 11 days after BMT. AzaC (2 mg/kg) was administrated subcutaneously every other day (4 doses total) starting 4 days after T cell injection. In vivo bioluminescence imaging (BLI) was performed to assess leukemia cell localization. For T cell proliferation/trafficking analyses, Balb/c were lethally irradiated one day prior to injection of T cell-depleted BM cells isolated from B6 (CD45.1+). Allogeneic donor T cells isolated from B6 (CD45.2+) were transduced with Click Beetle Red luciferase and were given 11 days after BMT, followed by AzaC treatment as described above. BLI was performed to track the donor T cells. Results: While neither T cell or leukemia cell trafficking was affected by the AzaC treatment, proliferation of donor T cells was significantly reduced compared to mice treated with PBS. The observed reduced T cell proliferation is not likely due to the direct effect of AzaC on T cells since the AzaC treatment preserved GvL activity comparable with the PBS control group. In addition, T cells isolated from both AzaC and PBS groups were equally reactive against third party antigen presenting cells, based on mixed lymphocyte reactions and cytotoxic T lymphocyte killing assays. These data along with our previous report demonstrating that the AzaC treatment increases Tregs in vivo strongly suggest that the therapeutic effect of AzaC on GvHD and GvL are mediated by the AzaC-induced Tregs which preferentially target alloreactive T cells while preferentially sparing anti-tumor T cells. Currently, secondary transplantation of Treg-depleted/replete T cells isolated from AzaC/PBS-treated recipient mice is underway to further confirm that donor T cells in the AzaC-treated mice are fully functional and that alloresponses of donor T cells are regulated by AzaC-induced Tregs. Conclusions: In vivo administration of AzaC after donor T cell infusion mitigates GvHD while preserving GvL via peripheral conversion of alloreactive donor T cells to FOXP3+ Tregs that preferentially inhibit alloreactive T cells while sparing anti-tumor T cells. These data provides the foundation for future clinical trials using epigenetic therapy aimed at mitigating GvHD without abrogating GvL and overcoming HLA barriers. Disclosures: No relevant conflicts of interest to declare.

Imatinib mesylate inhibits T-cell proliferation in vitro and delayed-type hypersensitivity in vivo

Blood ◽  
2004 ◽  
Vol 104 (4) ◽  
pp. 1094-1099 ◽  
Author(s):  
Allan B. Dietz ◽  
Lina Souan ◽  
Gaylord J. Knutson ◽  
Peggy A. Bulur ◽  
Mark R. Litzow ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Imatinib Mesylate ◽  
Cyclin D3 ◽  
Delayed Type Hypersensitivity ◽  
T Cell Proliferation

Abstract Imatinib mesylate (STI571, imatinib) inhibited DNA synthesis in primary human T cells stimulated with allogeneic mature dendritic cells or phytohemagglutinin (PHA) but did not induce apoptosis. The values for the concentration that inhibits 50% (IC50) of T-cell proliferation stimulated by dendritic cells and PHA were 3.9 μM and 2.9 μM, respectively, that is, within the concentration range found in patients treated with imatinib mesylate. Interestingly, imatinib mesylate did not inhibit expression of T-cell activation markers CD25 and CD69, although it reduced the levels of activated nuclear factor-κB (NF-κB) and changed phosphorylation or protein levels of Lck, ERK1/2, retinoblastoma protein, and cyclin D3. When T cells were washed free of imatinib mesylate, they proliferated in response to PHA, demonstrating that inhibition is reversible. Treatment with imatinib mesylate led to accumulation of the cells in G0/G1 phase of the cell cycle. The in vitro observations were confirmed in vivo in a murine model of delayed-type hypersensitivity (DTH). In mice treated with imatinib mesylate, DTH was reduced in comparison to sham-injected controls. However, the number of splenic T cells was not reduced showing that, similarly to in vitro observations, imatinib mesylate inhibited T-cell response, but did not cause apoptosis. These findings indicate that long-term administration of high-dose imatinib mesylate might affect immunity.

scholarly journals Low-Dose Decitabine Augments the Activation and Anti-Tumor Immune Response of IFN-γ+ CD4+ T Cells Through Enhancing IκBα Degradation and NF-κB Activation

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiang Li ◽  
Liang Dong ◽  
Jiejie Liu ◽  
Chunmeng Wang ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Immune Response ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Low Dose ◽  
T Cell Proliferation ◽  
Ifn Γ ◽  
Iκbα Degradation

BackgroundCD4+ T cells play multiple roles in controlling tumor growth and increasing IFN-γ+ T-helper 1 cell population could promote cell-mediated anti-tumor immune response. We have previously showed that low-dose DNA demethylating agent decitabine therapy promotes CD3+ T-cell proliferation and cytotoxicity; however, direct regulation of purified CD4+ T cells and the underlying mechanisms remain unclear.MethodsThe effects of low-dose decitabine on sorted CD4+ T cells were detected both in vitro and in vivo. The activation, proliferation, intracellular cytokine production and cytolysis activity of CD4+ T cells were analyzed by FACS and DELFIA time-resolved fluorescence assays. In vivo ubiquitination assay was performed to assess protein degradation. Moreover, phosphor-p65 and IκBα levels were detected in sorted CD4+ T cells from solid tumor patients with decitabine-based therapy.ResultsLow-dose decitabine treatment promoted the proliferation and activation of sorted CD4+ T cells, with increased frequency of IFN-γ+ Th1 subset and enhanced cytolytic activity in vitro and in vivo. NF-κB inhibitor, BAY 11-7082, suppressed decitabine-induced CD4+ T cell proliferation and IFN-γ production. In terms of mechanism, low-dose decitabine augmented the expression of E3 ligase β-TrCP, promoted the ubiquitination and degradation of IκBα and resulted in NF-κB activation. Notably, we observed that in vitro low-dose decitabine treatment induced NF-κB activation in CD4+ T cells from patients with a response to decitabine-primed chemotherapy rather than those without a response.ConclusionThese data suggest that low-dose decitabine potentiates CD4+ T cell anti-tumor immunity through enhancing IκBα degradation and therefore NF-κB activation and IFN-γ production.

scholarly journals Naive CD8+ T cells differentiate into protective memory-like cells after IL-2–anti–IL-2 complex treatment in vivo

2007 ◽  
Vol 204 (8) ◽  
pp. 1803-1812 ◽  
Author(s):  
Daisuke Kamimura ◽  
Michael J. Bevan
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
T Cell Proliferation ◽  
Memory Phenotype

An optimal CD8+ T cell response requires signals from the T cell receptor (TCR), co-stimulatory molecules, and cytokines. In most cases, the relative contribution of these signals to CD8+ T cell proliferation, accumulation, effector function, and differentiation to memory is unknown. Recent work (Boyman, O., M. Kovar, M.P. Rubinstein, C.D. Surh, and J. Sprent. 2006. Science. 311:1924–1927; Kamimura, D., Y. Sawa, M. Sato, E. Agung, T. Hirano, and M. Murakami. 2006. J. Immunol. 177:306–314) has shown that anti–interleukin (IL) 2 monoclonal antibodies that are neutralizing in vitro enhance the potency of IL-2 in vivo. We investigated the role of IL-2 signals in driving CD8+ T cell proliferation in the absence of TCR stimulation by foreign antigen. IL-2 signals induced rapid activation of signal transducer and activator of transcription 5 in all CD8+ T cells, both naive and memory phenotype, and promoted the differentiation of naive CD8+ T cells into effector cells. IL-2–anti–IL-2 complexes induced proliferation of naive CD8+ T cells in an environment with limited access to self–major histocompatibility complex (MHC) and when competition for self-MHC ligands was severe. After transfer into wild-type animals, IL-2–activated CD8+ T cells attained and maintained a central memory phenotype and protected against lethal bacterial infection. IL-2–anti–IL-2 complex–driven memory-like CD8+ T cells had incomplete cellular fitness compared with antigen-driven memory cells regarding homeostatic turnover and cytokine production. These results suggest that intense IL-2 signals, with limited contribution from the TCR, program the differentiation of protective memory-like CD8+ cells but are insufficient to guarantee overall cellular fitness.

scholarly journals Tocilizumab, but not dexamethasone, prevents CRS without affecting antitumor activity of bispecific antibodies

2020 ◽  
Vol 8 (1) ◽  
pp. e000621 ◽  
Author(s):  
Joseph Kauer ◽  
Sebastian Hörner ◽  
Lukas Osburg ◽  
Stefanie Müller ◽  
Melanie Märklin ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Antitumor Activity ◽  
Bispecific Antibodies ◽  
T Cell Proliferation ◽  
Car T Cells ◽  
Car T

Bispecific antibodies (bsAb) and chimeric antigen receptor (CAR) T cells allow for antibody guided recruitment of T cells against tumors. Both are successfully used for treatment of CD19 expressing leukemias, but may cause cytokine release syndrome (CRS) as a major dose-limiting side effect. For CRS prevention, steroids are recommended prior to bsAb treatment, despite their well-known lymphotoxic activity. The IL-6 receptor antibody tocilizumab is established for treatment of CRS induced by CAR T cells, but was not considered for CRS prevention in bsAb therapy. We here compared the influence of dexamethasone and tocilizumab on bsAb-mediated T cell proliferation and tumor lysis in vitro and in vivo and found that dexamethasone profoundly inhibited T cell proliferation and antitumor activity as induced by two different bsAb, particularly at low effector:target ratios, whereas tocilizumab did not affect efficacy. When we applied tocilizumab early during treatment of three patients with a newly developed PSMAxCD3 bsAb, significant CRS attenuation despite high IL-6 serum levels was observed. Thus, early IL-6 blockade may reduce the undesired sequelae of CRS upon bsAb therapy without affecting therapeutic activity, allowing in turn for safe application of effective doses.

scholarly journals Targeting Antigen Presenting   Cells to Treat Autoimmune  Inflammation

2021 ◽  
Author(s):  
◽  
Aras Toker
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Mhc Class Ii ◽  
T Cell Proliferation ◽  
Target Cells ◽  
Antigen Presenting

<p>Glatiramer acetate (GA) is approved for the treatment of relapsing-remitting multiple sclerosis (MS), and can suppress experimental autoimmune encephalomyelitis (EAE), a murine model of human MS. GA treatment is associated with the induction of anti-inflammatory TH2 responses and with the antigen specific expansion of regulatory T cells that counteract or inhibit pathogenic events in MS and EAE. These T cell mediated mechanisms of protection are considered to be a result of modulation of antigen presenting cells (APCs) by GA, rather than direct effects on T cells. However, it is unknown if GA preferentially targets a specific APC subset or can act through multiple APCs in vivo. In addition, GA-modulated innate cells may also exhibit direct antigen non-specific suppression of autoreactive cells. One objective of this study was to identify the in vivo target cell population of GA and to assess the potential of the target cells to antigen non-specifically suppress immune responses. Fluorophor-labelled GA bound to monocytes after intravenous injections, suggesting that monocytes may be the primary target of GA in vivo. In addition, intravenous GA treatment enhanced the intrinsic ability of monocytes to suppress T cell proliferation, both in vitro and in vivo. The findings of this study therefore suggest that GA-induced monocytes may contribute to GA therapy through direct mechanisms of antigen non-specific T cell immunosuppression. A further objective of this work was to investigate the potential of an in vivo drug targeting approach. This approach was hypothesised to increase the uptake of GA by the target cells and substantially improve GA treatment through antigen specific mechanisms such as induction of TH2 or regulatory T cells. Targeting antigens to professional APCs with an anti-MHC class II antibody resulted in significantly enhanced T cell proliferation in vitro. However, no EAE suppression occurred when GA was targeted to MHC class II in vivo. In addition, targeting GA specifically to monocytes also failed to suppress EAE. These findings suggest that GA treatment may selectively modulate monocytes to enhance their ability to inhibit autoreactive T cells, which could be part of the mechanism by which GA ameliorates MS. Targeting GA to a specific cell type may not be a powerful approach to improve treatment, because increased proliferation of GA specific T cells is not sufficient for disease suppression, and conjugation to antibodies may functionally reduce GA to a mere antigen devoid of immunomodulatory capacity.</p>

Monocytic Myeloid-Derived Suppress Cells Restore Adipogenic Bone Marrow Microenvironment in Aplastic Anemia By Inhibiting Intra-BM CD8+ T Cells Proliferation

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1211-1211
Author(s):  
Ying Qu ◽  
Zhengxu Sun ◽  
Yan Yuan ◽  
Fen Wang ◽  
Kunpeng Wu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
T Cell Proliferation ◽  
Immune Balance ◽  
Ifn Γ

Aplastic anemia (AA) is a hematopoietic disorder resulted from immune-related hypocellular hematopoiesis in bone marrow (BM). It has been clearly addressed that the activated T cells contribute to the exhaustion of hematopoietic progenitors and hypo-hematopoiesis. The adipogenic BM is one of the characteristics to make AA diagnosis. However, little is known about the relationship of intra-BM immune imbalance and hematopoietic microenvironment abnormity in this disease entity. Functional hematopoiesis relies on not only abundant hematopoietic stem cells (HSCs) but also the balanced supportive hematopoietic niche. Intra-BM immune balance, at either cellular or cytokine level, is one of the key footstones to maintain hematopoietic microenvironment. Various intra-BM immune cellular components play both sides of one coin. Among them, myeloid-derived suppressive cells (MDSCs) are heterogeneous myeloid progenitor cells characterized by the negative immune response in cancers and other inflammatory diseases. In BM aspiration and biopsy samples from the patients who were diagnosed as AA in our study, massive activated lymphocytes infiltration and adipocytes accumulation were observed. Interestingly, the absolute numbers of immune modulatory MDSCs either in AA patients' PB or in BM of immune-related AA mice were reduced, indicating a potential link between polarized BM adipo-osteogenic microenvironment and immune disorder under AA circumstance. We thus adopted AA mice model to look into the embedded details both in vivo and in vitro. We clarified that BM components were more vulnerable to the attack of CD8+ T cells than that of CD4+ T cells. Taking into the fact that BM adipocytes are more abundant either in AA patients or in AA mice models, we differentiated mesenchymal stromal cells (MSCs), the major BM stroma cells, into osteoblastic or adipogenic lineages to mimic the osteo-adipogenic differentiation in BM microenvironment. Interestingly, CD8+ T cells and interferon-γ(IFN-γ) exerted dramatically adipocytic stimulation on BM-MSCs either in vitro or in vivo, by determination of increasing expression of adipogenetic genes including Ap2, Perilipin, Pparg and Cebpα, as well as staining of Oil Red O and perilipin. To dissect intra-BM cellular immune balance, MDSCs were isolated as representative immune regulating population to investigate their function on osteo-adipogenic balance. Interestingly, not CD11b+Ly6G+Ly6C-granulocytic-MDSCs (gMDSCs) but CD11b+Ly6G-Ly6C+monocytic-MDSCs (mMDSCs) inhibited both T cell proliferation and IFN-γ production. Addition of L-NMMA, the antagonist of iNOS pathway in mMDSCs-containing system restored T cell proliferative curve and cell numbers, whereas Nor-NOHA, the antagonist of Arg-1 pathway didn't abrogate mMDSCs' immune-regulation properties, indicating that mMDSCs inhibited T cell proliferation via iNOS pathway. We then performed single dose or multi-dose injection of mMDSCs in AA mice to see whether mMDSCs are able to reconstitute the impacted hematopoiesis. Single injection of mMDSCs was able to prevent from CTL infiltration in a very short term. However, multi-injection of mMDSCs showed significant benefit in overall survival rate compared to AA mice. We further detected the function of mMDSCs on polarized BM-MSCs adipo-osteogenic differentiation potential. To detect sequential BM adipogenetic progression in AA microenvironment, we performed in vivo fluorescent microscopy on AP2 (Fabp4)-Cre×mT/mG reporting mice at different transfusion time points of T cells and mMDSCs. GFP-expressing AP2+ adipocytes accumulated adjacently to perivascular niches whose boarders were labelled by Dextran-CY5 in a time-dependent manner after T cell infusion. Monocytic MDSCs transfused AA mice showed decreased GFP+ adipocytes which was coincident with our in vitro findings. In conclusion, intra-BM immune balance is one of the environmental factors seesawing by activating and suppressive ends to support functional hematopoiesis. Adoptive transfusion of mMDSCs, the immune-suppressive population might be a novel immune-regulating strategy to treat AA, relying on not only restoring the intra-BM immune balance but also improving stroma's multi-differentiating microenvironment. Figure Disclosures No relevant conflicts of interest to declare.

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