scholarly journals Induction of IL-12p40 and type 1 immunity by Toxoplasma gondii in the absence of the TLR-MyD88 signaling cascade

2021 ◽  
Vol 17 (10) ◽  
pp. e1009970
Author(s):  
Lindsay M. Snyder ◽  
Claire M. Doherty ◽  
Heather L. Mercer ◽  
Eric Y. Denkers
Keyword(s):  
T Cells ◽  
T Cell ◽  
Toxoplasma Gondii ◽  
Immune Responses ◽  
Myeloid Cell ◽  
Lymphoid Cells ◽  
Type I ◽  
Compensatory Response ◽  
Ifn Γ

Toxoplasma gondii is an orally acquired pathogen that induces strong IFN-γ based immunity conferring protection but that can also be the cause of immunopathology. The response in mice is driven in part by well-characterized MyD88-dependent signaling pathways. Here we focus on induction of less well understood immune responses that do not involve this Toll-like receptor (TLR)/IL-1 family receptor adaptor molecule, in particular as they occur in the intestinal mucosa. Using eYFP-IL-12p40 reporter mice on an MyD88-/- background, we identified dendritic cells, macrophages, and neutrophils as cellular sources of MyD88-independent IL-12 after peroral T. gondii infection. Infection-induced IL-12 was lower in the absence of MyD88, but was still clearly above noninfected levels. Overall, this carried through to the IFN-γ response, which while generally decreased was still remarkably robust in the absence of MyD88. In the latter mice, IL-12 was strictly required to induce type I immunity. Type 1 and type 3 innate lymphoid cells (ILC), CD4+ T cells, and CD8+ T cells each contributed to the IFN-γ pool. We report that ILC3 were expanded in infected MyD88-/- mice relative to their MyD88+/+ counterparts, suggesting a compensatory response triggered by loss of MyD88. Furthermore, bacterial flagellin and Toxoplasma specific CD4+ T cell populations in the lamina propria expanded in response to infection in both WT and KO mice. Finally, we show that My88-independent IL-12 and T cell mediated IFN-γ production require the presence of the intestinal microbiota. Our results identify MyD88-independent intestinal immune pathways induced by T. gondii including myeloid cell derived IL-12 production, downstream type I immunity and IFN-γ production by ILC1, ILC3, and T lymphocytes. Collectively, our data reveal an underlying network of immune responses that do not involve signaling through MyD88.

Plasmacytoid DCs regulate recall responses by rapid induction of IL-10 in memory T cells

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3369-3376 ◽  
Author(s):  
Espen O. Kvale ◽  
Yngvar Fløisand ◽  
Fridtjof Lund-Johansen ◽  
Halvor Rollag ◽  
Lorant Farkas ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Large Fraction ◽  
Cell Mediated Immunity ◽  
Type I ◽  
Rapid Induction ◽  
Recall Antigen ◽  
Plasmacytoid Dcs ◽  
Ifn Γ

Abstract Dendritic cells (DCs) are believed to regulate T cell-mediated immunity primarily by directing differentiation of naive T cells. Here, we show that a large fraction of CD4+ memory cells produce IL-10 within the first hours after interaction with plasmacytoid DCs (PDCs). In contrast, CD11c+ DCs induce IFN-γ and little IL-10. IL-10–secreting T cells isolated after 36 hours of culture with PDCs suppressed antigen-induced T-cell proliferation by an IL-10–dependent mechanism, but were distinct from natural and type 1 regulatory T cells. They proliferated strongly and continued to secrete IL-10 during expansion with PDCs, and after restimulation with immature monocyte-derived DCs or CD11c+ DCs. The IL-10–producing T cells acquired the ability to secrete high levels of IFN-γ after isolation and subsequent coculture with PDCs or CD11c+ DCs. Compared to CD11c+ DCs, PDCs were superior in their ability to selectively expand T cells that produced cytokines on repeated antigenic challenge. The DC-dependent differences in cytokine profiles were observed with viral recall antigen or staphylococcal enterotoxin B and were independent of extracellular type I interferon or IL-10. Our results show that DCs can regulate memory responses and that PDCs rapidly induce regulatory cytokines in effector T cells that can suppress bystander activity.

scholarly journals Innate cell microenvironments in lymph nodes shape the generation of T cell responses during type I inflammation

2021 ◽  
Vol 6 (56) ◽  
pp. eabb9435
Author(s):  
Joseph M. Leal ◽  
Jessica Y. Huang ◽  
Karan Kohli ◽  
Caleb Stoltzfus ◽  
Miranda R. Lyons-Cohen ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Lymph Nodes ◽  
Critical Role ◽  
Myeloid Cell ◽  
T Cell Responses ◽  
Type I ◽  
Cell Responses ◽  
Inflammatory Monocytes ◽  
Cell Effector

Microanatomical organization of innate immune cells within lymph nodes (LNs) is critical for the generation of adaptive responses. In particular, steady-state LN-resident dendritic cells (Res cDCs) are strategically localized to intercept lymph-draining antigens. Whether myeloid cell organization changes during inflammation and how that might affect the generation of immune responses are unknown. Here, we report that during type I, but not type II, inflammation after adjuvant immunization or viral infection, antigen-presenting Res cDCs undergo CCR7-dependent intranodal repositioning from the LN periphery into the T cell zone (TZ) to elicit T cell priming. Concurrently, inflammatory monocytes infiltrate the LNs via local blood vessels, enter the TZ, and cooperate with Res cDCs by providing polarizing cytokines to optimize T cell effector differentiation. Monocyte infiltration is nonuniform across LNs, generating distinct microenvironments with varied local innate cell composition. These spatial microdomains are associated with divergent early T cell effector programming, indicating that innate microenvironments within LNs play a critical role in regulating the quality and heterogeneity of T cell responses. Together, our findings reveal that dynamic modulation of innate cell microenvironments during type I inflammation leads to optimized generation of adaptive immune responses to vaccines and infections.

AB0268 HUMAN T-CELL LEUKAEMIA VIRUS TYPE 1 MAY INVALIDATE T-SPOT.TB RESULTS AMONG RHEUMATOID ARTHRITIS PATIENTS: A RETROSPECTIVE OBSERVATIONAL STUDY

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1432.1-1433
Author(s):  
K. Umekita ◽  
Y. Hashiba ◽  
R. Kudou ◽  
S. Miyauchi ◽  
M. Kimura ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Virus Type ◽  
Peripheral Blood ◽  
Medical Records ◽  
Cell Leukaemia ◽  
Leukaemia Virus ◽  
Human T Cell ◽  
Ifn Γ

Background:In clinical rheumatology, interferon-γ release assays (IGRAs) have been reported as a useful diagnostic test for latent tuberculosis infection (LTBI) before beginning the administration of biologics such as anti-TNF therapies (1). CD4-positive T cells are the main target in Human T-cell leukaemia virus type 1 (HTLV-1) infection. Several reports suggest that the reaction of tuberculin skin test (TST) is attenuated in HTLV-1-positive individuals compared with that in HTLV-1-negative individuals (2). However, it remains unclear whether IGRAs are reliable for detecting TB infection among HTLV-1-positive RA patients.Objectives:The present study aimed to investigate the usefulness of the T-SPOT.TBassay in HTLV-1-positive RA patients. In addition, the association between the existence of IFN-γ producing T cells and HTLV-1 proviral loads (PVLs) in HTLV-1-positive RA patients was analysed on the basis of the T-SPOT.TBassay results.Methods:We reviewed the medical records of 75 HTLV-1-negative and 29 HTLV-1-positive RA patients were suspected cases of LTBI and evaluated using the T-SPOT.TBassay as a clinical practice from April 2012 to July 2019. The results of T-SPOT.TBwere collected from medical records, retrospectively. Peripheral blood samples were obtained from HTLV-1-positive RA patients for the analysis of HTLV-1 PVLs values. The study protocol was approved by the research ethics committees of our hospitals.Results:Approximately 55% of the HTLV-1-positive RA patients showed invalid results for the T-SPOT.TBassay (p < 0.0001); the cause of invalid results was a spot-forming count of >10 spots in the negative controls of the T-SPOT.TBassay among HTLV-1-positive RA patients. Among HTLV-1-positive RA patients, HTLV-1 PVL values were significantly higher in 16 patients who showed invalid results than in 13 patients who did not (p = 0.003). There were no between-group differences in female patient ratio, age, RA disease activity and therapeutic regimens. IFN-γ producing cells were detected in the peripheral blood of HTLV-1-positive RA patients without stimulation with TB-specific antigens.Conclusion:The incidence of invalid results for the T-SPOT.TBassay has been reported to be as low as 0.6% (3). The results of this assay for screening of LTBI in HTLV-1-positive RA patients should be interpreted with caution. Furthermore, our results show that an increase in IFN-γ producing T cell numbers due to HTLV-1 infection in RA patients may affect the pathogenesis of RA.References:[1]Iannone, F., et al.J. Rheumatol. Suppl.91, 41-46 (2014).[2]Tachibana, N., et al.Int. J. Cancer42, 829-831 (1988).[3]Rego, K., et al.Tuberculosis (Edinb.)108, 178-185 (2018).Acknowledgments:We would like to thank Dr Yuki Hashikura and Ms Yuki Kaseda of the University of Miyazaki for their technical support in this work. We would also like to acknowledge Ms Yumiko Kai at the Institute of Rheumatology, Zenjinkai Shimin-no-Mori Hospital, for her help in data management.A part this work was supported by a grant from the Practical Research Project for Rare/Intractable Diseases of the Japan Agency for Medical Research and Development (Grant No. JP19ek0109356), a Health and Labor Sciences Research Grant on Rare and Intractable Diseases from the Ministry of Health, Labor and Welfare of Japan (Grant No. 19FC1007), and a Grant-in-Aid for Clinical Research from Miyazaki University Hospital.Disclosure of Interests:Kunihiko Umekita Paid instructor for: Astellas Pharma Inc. Chugai Pharma Inc. Tanabe-Mitsubishi Pharma Inc., Speakers bureau: Bristol-Myers Squibb, Yayoi Hashiba: None declared, Risa Kudou: None declared, Shunichi Miyauchi: None declared, Masatoshi Kimura: None declared, Motohiro Matsuda: None declared, Chihiro Iwao: None declared, Yumi Kariya: None declared, Takeshi Kawaguchi: None declared, Katoko Takajo: None declared, Koushou Iwao: None declared, Yuuki Rikitake: None declared, Ichiro Takajo: None declared, Toshihiko Hidaka Paid instructor for: Astellas Pharma Inc. Chugai Pharma Inc. Tanabe-Mitsubishi Pharma Inc., Speakers bureau: Astellas Pharma Inc. Chugai Pharma Inc. Tanabe-Mitsubishi Pharma Inc., Akihiko Okayama: None declared

scholarly journals The E3 ubiquitin ligase MARCH1 regulates antimalaria immunity through interferon signaling and T cell activation

2020 ◽  
pp. 202004332 ◽  
Author(s):  
Jian Wu ◽  
Lu Xia ◽  
Xiangyu Yao ◽  
Xiao Yu ◽  
Keyla C. Tumas ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
T Cell Activation ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Plasmodium Yoelii ◽  
Cell Populations ◽  
Eqtl Analysis ◽  
Type I ◽  
Ifn Γ

Malaria infection induces complex and diverse immune responses. To elucidate the mechanisms underlying host–parasite interaction, we performed a genetic screen during early (24 h) Plasmodium yoelii infection in mice and identified a large number of interacting host and parasite genes/loci after transspecies expression quantitative trait locus (Ts-eQTL) analysis. We next investigated a host E3 ubiquitin ligase gene (March1) that was clustered with interferon (IFN)-stimulated genes (ISGs) based on the similarity of the genome-wide pattern of logarithm of the odds (LOD) scores (GPLS). March1 inhibits MAVS/STING/TRIF-induced type I IFN (IFN-I) signaling in vitro and in vivo. However, in malaria-infected hosts, deficiency of March1 reduces IFN-I production by activating inhibitors such as SOCS1, USP18, and TRIM24 and by altering immune cell populations. March1 deficiency increases CD86+DC (dendritic cell) populations and levels of IFN-γ and interleukin 10 (IL-10) at day 4 post infection, leading to improved host survival. T cell depletion reduces IFN-γ level and reverse the protective effects of March1 deficiency, which can also be achieved by antibody neutralization of IFN-γ. This study reveals functions of MARCH1 (membrane-associated ring-CH–type finger 1) in innate immune responses and provides potential avenues for activating antimalaria immunity and enhancing vaccine efficacy.

scholarly journals Splicing factor SRSF1 limits IFN-γ production via RhoH and ameliorates experimental nephritis

Rheumatology ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 420-429
Author(s):  
Takayuki Katsuyama ◽  
Hao Li ◽  
Suzanne M Krishfield ◽  
Vasileios C Kyttaris ◽  
Vaishali R Moulton
Keyword(s):  
T Cells ◽  
T Cell ◽  
Molecular Mechanisms ◽  
Elevated Serum ◽  
Splicing Factor ◽  
Type I ◽  
Human T Cells ◽  
Experimental Nephritis ◽  
Ifn Γ

Abstract Objective CD4 T helper 1 (Th1) cells producing IFN-γ contribute to inflammatory responses in the pathogenesis of SLE and lupus nephritis. Moreover, elevated serum type II IFN levels precede the appearance of type I IFNs and autoantibodies in patient years before clinical diagnosis. However, the molecules and mechanisms that control this inflammatory response in SLE remain unclear. Serine/arginine-rich splicing factor 1 (SRSF1) is decreased in T cells from SLE patients, and restrains T cell hyperactivity and systemic autoimmunity. Our objective here was to evaluate the role of SRSF1 in IFN-γ production, Th1 differentiation and experimental nephritis. Methods T cell-conditional Srsf1-knockout mice were used to study nephrotoxic serum-induced nephritis and evaluate IFN-γ production and Th1 differentiation by flow cytometry. RNA sequencing was used to assess transcriptomics profiles. RhoH was silenced by siRNA transfections in human T cells by electroporation. RhoH and SRSF1 protein levels were assessed by immunoblots. Results Deletion of Srsf1 in T cells led to increased Th1 differentiation and exacerbated nephrotoxic serum nephritis. The expression levels of RhoH are decreased in Srsf1-deficient T cells, and silencing RhoH in human T cells leads to increased production of IFN-γ. Furthermore, RhoH expression was decreased and directly correlated with SRSF1 in T cells from SLE patients. Conclusion Our study uncovers a previously unrecognized role of SRSF1 in restraining IFN-γ production and Th1 differentiation through the control of RhoH. Reduced expression of SRSF1 may contribute to pathogenesis of autoimmune-related nephritis through these molecular mechanisms.

scholarly journals Safety Profile of a Virus-Like Particle-Based Vaccine Targeting Self-Protein Interleukin-5 in Horses

Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 213 ◽  
Author(s):  
Sigridur Jonsdottir ◽  
Victoria Fettelschoss ◽  
Florian Olomski ◽  
Stephanie C. Talker ◽  
Jelena Mirkovitch ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Mononuclear Cells ◽  
Clinical Signs ◽  
T Cell Response ◽  
Type I ◽  
Cell Responses ◽  
Virus Like Particle ◽  
Ifn Γ

Background: Insect bite hypersensitivity (IBH) is an eosinophilic allergic dermatitis of horses caused by type I/IVb reactions against mainly Culicoides bites. The vaccination of IBH-affected horses with equine IL-5 coupled to the Cucumber mosaic virus-like particle (eIL-5-CuMVTT) induces IL-5-specific auto-antibodies, resulting in a significant reduction in eosinophil levels in blood and clinical signs. Objective: the preclinical and clinical safety of the eIL-5-CuMVTT vaccine. Methods: The B cell responses were assessed by longitudinal measurement of IL-5- and CuMVTT-specific IgG in the serum and plasma of vaccinated and unvaccinated horses. Further, peripheral blood mononuclear cells (PBMCs) from the same horses were re-stimulated in vitro for the proliferation and IFN-γ production of specific T cells. In addition, we evaluated longitudinal kidney and liver parameters and the general blood status. An endogenous protein challenge was performed in murine IL-5-vaccinated mice. Results: The vaccine was well tolerated as assessed by serum and cellular biomarkers and also induced reversible and neutralizing antibody titers in horses and mice. Endogenous IL-5 stimulation was unable to re-induce anti-IL-5 production. The CD4+ T cells of vaccinated horses produced significantly more IFN-γ and showed a stronger proliferation following stimulation with CuMVTT as compared to the unvaccinated controls. Re-stimulation using E. coli-derived proteins induced low levels of IFNγ+CD4+ cells in vaccinated horses; however, no IFN-γ and proliferation were induced following the HEK-eIL-5 re-stimulation. Conclusions: Vaccination using eIL-5-CuMVTT induces a strong B-cell as well as CuMVTT-specific T cell response without the induction of IL-5-specific T cell responses. Hence, B-cell unresponsiveness against self-IL-5 can be bypassed by inducing CuMVTT carrier-specific T cells, making the vaccine a safe therapeutic option for IBH-affected horses.

scholarly journals Multifunctional Human Immunodeficiency Virus (HIV) Gag-Specific CD8+ T-Cell Responses in Rectal Mucosa and Peripheral Blood Mononuclear Cells during Chronic HIV Type 1 Infection

2007 ◽  
Vol 81 (11) ◽  
pp. 5460-5471 ◽  
Author(s):  
J. William Critchfield ◽  
Donna Lemongello ◽  
Digna H. Walker ◽  
Juan C. Garcia ◽  
David M. Asmuth ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Rectal Mucosa ◽  
Peripheral Blood Mononuclear ◽  
Tnf Α ◽  
Immunodeficiency Virus ◽  
Ifn Γ ◽  
Hiv 1

ABSTRACT The intestinal tract is a lymphocyte-rich site that undergoes severe depletion of memory CD4+ T cells within days of simian immunodeficiency virus or human immunodeficiency virus type 1 (HIV-1) infection. An ensuing influx of virus-specific CD8+ T cells, which persist throughout the chronic phase of infection, has also been documented in the gastrointestinal tract. However, little is known of the functionality of these effector cells or their relationship to the disease course. In this study, we measured CD8+ T-cell responses to HIV-1 peptides in paired rectal and blood samples from chronically infected patients. In both blood and rectum, there was an immunodominant CD8+ T-cell response to HIV Gag compared to Pol and Env (P < 0.01). In contrast, cytomegalovirus pp65 peptides elicited gamma interferon (IFN-γ) secretion strongly in peripheral blood mononuclear cells (PBMC) but weakly in rectal CD8+ T cells (P = 0.015). Upon stimulation with HIV peptides, CD8+ T cells from both sites were capable of mounting complex responses including degranulation (CD107 expression) and IFN-γ and tumor necrosis factor alpha (TNF-α) production. In rectal tissue, CD107 release was frequently coupled with production of IFN-γ or TNF-α. In patients not on antiretroviral therapy, the magnitude of Gag-specific responses, as a percentage of CD8+ T cells, was greater in the rectal mucosa than in PBMC (P = 0.054); however, the breakdown of responding cells into specific functional categories was similar in both sites. These findings demonstrate that rectal CD8+ T cells are capable of robust and varied HIV-1-specific responses and therefore likely play an active role in eliminating infected cells during chronic infection.

Identification of the AAV2 Capsid CD8+ T Cell Epitope in C57BL/6 Mice.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3188-3188
Author(s):  
Denise E. Sabatino ◽  
Federico Mingozzi ◽  
Haifeng Chen ◽  
Peter Colosi ◽  
Hildegund C.J. Ertl ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Capsid Protein ◽  
Cd8 T Cells ◽  
Cell Epitope ◽  
T Cell Response ◽  
Cd8 Cells ◽  
Media Control ◽  
Ifn Γ

Abstract Recently, a clinical trial for adeno-associated virus serotype 2 (AAV2) mediated liver directed gene transfer of human Factor IX to subjects with severe hemophilia B revealed that two patients developed transient asymptomatic transaminitis following vector administration. Immunology studies in the second patient demonstrated a transient T cell response to AAV2 capsid peptides suggesting that the immune response to the AAV capsid may be related to the transient transaminitis. We hypothesized that the observations made in the human subjects were due to a CD8 T cell response to AAV2 capsid protein. Preclinical studies in mice and dogs, which are not naturally infected by wild type AAV2 viruses, did not predict these findings in the clinical study. Thus, we developed a mouse model in which we were able to mimic this phenomenon (Blood 102:493a). In an effort to further characterize the immune responses to AAV2 capsid proteins in this mouse model, we identified the T cell epitope in the AAV capsid protein recognized by murine C57Bl/6 CD8 T cells. A peptide library of AAV2 VP1 capsid peptides (n=145) that were synthesized as 15mers overlapping by 10 amino acids were divided into 6 pools each containing 24–25 peptides. C57Bl/6 mice were immunized intramuscularly with an adenovirus expressing AAV2 capsid protein. Nine days later the spleen was harvested and intracellular cytokine staining (ICS) was used to assess release of IFN-γ from CD8 T cells in response to 6 AAV2 capsid peptide pools. ICS demonstrated CD8 cells from mice immunized with Ad-AAV2 produced IFN-γ (3.5% of the CD8 cells) in response to Pool F (amino acid 119–145) while no IFN-γ release in CD8 cells was detected with Pool A to E (mean 0.28%±0.25%) compared to the media control (0.16%). This detection of IFN-γ release from CD8 T cells indicates a specific proliferation to a peptide(s) within this peptide pool (Pool F). A matrix approach was used to further define which peptide(s) contained the immunodominant epitope. Eleven small peptide pools of Pool F were created in which each peptide was represented in 2 pools. ICS of splenocytes from immunized (Ad-AAV2 capsid) C57Bl/6 mice demonstrated IFN-γ response from CD8 cells to 3 of the matrix pools corresponding to peptide 140 (PEIQYTSNYNKSVNV) and 141 (TSNYNKSVNVDFTVD) compared with media controls. To determine the exact peptide sequence that binds to the MHC Class I molecule, 9 amino acid peptides (n=7) were created that overlap peptide 140 and 141. Peptide SNYNKSVNV showed positive staining for both CD8 and IFN- γ(3.2%) compared with the six other peptides (0.14%±0.08%), media control (0.08%) and mice that were not immunized (0.11%). This epitope lies in the C terminus of the AAV2 VP1 capsid protein. Current studies using strains of mice with different MHC H2 haplotypes will allow us to determine which of the C57Bl/6 MHC alleles the epitope binds. These findings will provide us with a powerful tool for assessing immune responses to AAV capsid in the context of gene therapy. Specifically, they will allow us to determine how long immunologically detectable capsid sequences persist in an animal injected with AAV vectors. This in turn will provide a basis for a clinical study in which subjects are transiently immunosuppressed, from the time of vector injection until capsid epitopes are no longer detectable by the immune system.

Donor DC Subsets Polarize Donor T-Cell Immune Responses in Allogeneic BMT.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 573-573
Author(s):  
Jian-Ming Li ◽  
Cynthia Giver ◽  
Doug McMillan ◽  
Wayne Harris ◽  
David L. Jaye ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Peripheral Blood ◽  
Immune Reconstitution ◽  
Hematopoietic Cell ◽  
Post Transplant ◽  
Donor T Cells ◽  
Ifn Γ

Abstract Introduction: Impaired or inappropriate immune reconstitution after allogeneic bone marrow transplantation (BMT) can lead to infection, graft-versus-host disease (GvHD) and leukemia relapse. We have previously reported that BM contains two populations of dendritic cell (DC) subsets, CD11b+ DC and CD11b− DC, and that CD11b depleted donor BM promoted increased donor T-cell chimerism and increased graft-versus-leukemia (GvL) activity in C57BL/6 → B10BR transplants [BBMT, 2004, 10: 540]. To explore the mechanism by which CD11b-depletion improved allo-reactivity, we performed allogeneic hematopoietic cell transplants using defined populations of donor stem cells, DCs, and T-cells in a MHC mis-matched BMT model. Methods: We transplanted FACS purified populations of 50,000 GFP+ CD11b- DC or CD11b+ DC in combination with 5,000 FACS purified Lin- Sca-1+ c-kit+ hematopoietic stem cells (HSC) and 300,000 or 1,000,000 congenic spleen T-cells from C57BL/6 donors into C57BL/6[H-2Kb], B10BR[H-2Kk] and PL/J[H-2Ku] recipients. Proliferation of CFSE stained donor T-cells was measured at 72 hours post-transplant. FACS cytometric bead array and intracellular cytokine staining measured serum and intracellular cytokines in donor T-cells. Results: The initial proliferation and Ki-67 expression of CFSE labeled donor T-cells in allogeneic recipients were much higher than in syngeneic recipients (homeostatic proliferation). Confocal microscopy showed co-localization of donor DC subsets with donor T-cells in the recipient spleens at 3 and 10 days post-transplant. In the allogeneic transplant settings, donor T-cells co-transplanted with CD11b- DC showed increased IFN-γ synthesis at 3 and 10 days post-transplant compared to donor T-cells co-transplanted with HSC plus CD11b+ DC or HSC alone. Increased proliferation of donor T-cells led to increased donor T-cell chimerism at day 10, 30, 60, and day105 post-transplant among recipients of CD11b- DC compared to recipients of HSC alone or HSC plus CD11b+ DC (Figure 1). Transplantation of spleen T-cells and CD11b- DC did not increase GvHD, but was associated with full donor chimerism. In contrast, transplantation of allogeneic CD11b+ DC led to persistence and expansion of residual host T-cells (Figure 2), increased numbers of donor CD4+CD25++Foxp3+ T-cells, and higher serum level of IL-10 supporting early post-transplant expansion of donor T regulatory cells (Treg). Conclusions: Donor CD11b- DC promoted immune reconstitution by polarizing donor T-cells to Th1 immune responses associated with increased IFN-γ synthesis and donor T-cell proliferation, while donor CD11b+ DC suppressed immune reconstitution by inhibiting donor T-cell allogeneic immune responses. These data support a novel paradigm for the regulation of post-transplant immunity and suggest clinical methods to test the hypothesis that manipulation of the DC content of a hematopoietic cell allograft regulates post transplant immunity in the clinical setting. Figure 1. Donor Spleen Derived T-cells in Peripheral Blood [* p<0.05, v.s. recipients of HSC plus CD11b(+)DC and spleen T-cells] Figure 1. Donor Spleen Derived T-cells in Peripheral Blood [* p<0.05, v.s. recipients of HSC plus CD11b(+)DC and spleen T-cells] Figure 2. Host Derived T-cells in Peripheral Blood [* p<0.05, v.s. recipients of HSC plus CD11b(-)DC and spleen T-cells] Figure 2. Host Derived T-cells in Peripheral Blood [* p<0.05, v.s. recipients of HSC plus CD11b(-)DC and spleen T-cells]

Phagocytosis May Be a Regulatory Mechanism for Myeloid Dendritic Cells to Terminate Type 1 CD8+ T Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1654-1654
Author(s):  
Young-June Kim ◽  
Hal E. Broxmeyer
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Cd8 T Cells ◽  
Phagocytic Activity ◽  
Regulatory Mechanism ◽  
Gm Csf ◽  
T Cell Immune Responses ◽  
Ifn Γ

Abstract Abstract 1654 Poster Board I-680 CD8+ cytotoxic T cells are often ‘exhausted’ by programmed death-1 (PD-1) signaling, and subsequently the functions of these cells are terminated especially in a tumor environment or upon chronic HIV or HCV infection. Subsets of myeloid cells referred to as myeloid derived suppressor cells (MDSC) or regulatory dendritic cells (DCs) have been implicated in inducing exhaustion or termination of effector CD8+ T cells. To this end, we developed various myeloid-derived dendritic cell (DC) types in vitro from human CD14+ monocytes using M-CSF or GM-CSF in the presence of IL-4 with/without other cytokines, and characterized these DCs with respect to their capacity to induce PD-1 expression on and exhaustion of CD8+ T cells. We then assessed their impact on longevity of CD8+ T cells following coculture. Myeloid DCs developed in vitro with M-CSF and IL-4 for 5 days (referred to as M-DC) did not express ligand for PD-1 (PD-L1) nor did they induce PD-1 on CD8+ T cells. Thus, using M-DCs as starting cells, we sought determinant factors that could modulate M-DCs to express PD-L1 and thereby induce exhaustion of CD8+ T cells. In order to better monitor exhaustion processes, we incubated human peripheral CD8+ T cells for 5 days in the presence of IL-15, an important cytokine for maintaining viability, before coculture. M-DCs showed little impact on exhaustion or longevity of the CD8+ T cells. IL-10 converted M-DC into a distinct myeloid DC subset (referred to as M-DC/IL-10) with an ability to express PD-L1 as well as to induce PD-1 on cocultured CD8+ T cells. M-DC/IL-10 cells markedly suppressed proliferation of cocultured CD8+ T cells. M-DC/IL-10 cells were morphologically unique with many granules and filamentous structures around the cell periphery. These IL-10 effects on M-DC were completely abrogated in the presence of TNF-á. M-DC/IL-10 cells could be further differentiated into another myeloid DC subset in the presence of IFN-γ (referred to as M-DC/IL-10/IFN-γ) with an ability to express even higher levels of PD-L1 compared to M-DC/IL-10 cells. The most remarkable effect of M-DC/IL-10/IFN-γ cells on cocultured CD8+ T cells was a dramatic loss of CD8+ T cells. Light and confocal microscopic observations indicated that loss of CD8+ T cells was due to phagocytosis by M-DC/IL-10/IFN-γ cells. As IFN-γ, a type 1 cytokine which is induced in CD8+ T cells by IL-12 is essential for phagocytosis, we tested whether IL-12 treatment of CD8+ T cells could further enhance phagocytosis induced by M-DC/IL-10/IFN-γ cells. Indeed, IL-12 treatment greatly increased numbers of phagocytosed CD8+ T cells. In contrast, IL-4 treated CD8+ T cells became resistant to phagocytosis, suggesting IFN-γ producing (type1) CD8+ T cells may be primary target cells for the M-DC/IL-10 cells mediated phagocytosis. CD4+ T cells were not as susceptible as CD8+ T cells to phagocytosis. We failed to detect such phagocytic activity induced by prototype DCs generated with GM-CSF and IL-4. Phagocytic activity was not inhibited by various arginase-1 inhibitors suggesting that nitric oxide signaling may not mediate phagocytic activity. Neutralizing antibody to PD-L1 slightly but significantly lowered phagocytic activity suggesting that PD-L1/PD-1 interaction may be partially involved in this process. Myeloid DCs are thought to be immunogenic, actively inducing T cell immune responses. Our results demonstrate that myeloid DCs may play suppressive roles as well through induction of phagocytic activity, especially against IFN-γ producing CD8+ T cells. This may serve as a regulatory mechanism for type 1 CD8+ T cell immune responses in an IL-10 enriched microenvironment. Disclosures No relevant conflicts of interest to declare.

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