Primed Antigen-Specific CD4+ T Cells Are Required for NK Cell Activation In Vivo upon Leishmania major Infection

Abstract The small guanine nucleotide binding proteins of the Ras family, including in mammals the highly homologous H-ras, N-ras, and K-ras isoforms, are rapidly activated on ligation of the T-cell antigen receptor (TCR), but whether each isoform plays specific roles in T cells is largely unknown. Here, we show, with the use of mice specifically lacking H-ras or N-ras, that these isoforms are dispensable for thymocyte development and mature T-cell activation. By contrast, CD4+ T cells from Ras-deficient mice exhibited markedly decreased production of the Th1 signature cytokine IFN-γ early after TCR stimulation, concomitantly with impaired induction of the Th1-specific transcription factor T-bet. Accordingly, Ras-deficient mice failed to mount a protective Th1 response in vivo against the intracellular parasite Leishmania major, although they could be rendered resistant to infection if a Th1-biased milieu was provided during parasite challenge. Collectively, our data indicate that the TCR recruits distinct Ras isoforms for signal transduction in developing and mature T cells, thus providing a mechanism for differential signaling from the same surface receptor. Furthermore, we demonstrate for the first time that H-ras and N-ras act as critical controllers of Th1 responses, mostly by transmitting TCR signals for Th1 priming of CD4+ T cells.

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Identification of distinct immune activation profiles in adult humans

Scientific Reports ◽

10.1038/s41598-020-77707-6 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Renaud Cezar ◽

Audrey Winter ◽

Delphine Desigaud ◽

Manuela Pastore ◽

Lucy Kundura ◽

...

Keyword(s):

T Cells ◽

Immune Activation ◽

Cell Activation ◽

Immune Cell ◽

Nk Cell ◽

Liver Steatosis ◽

Treg Cells ◽

Microbial Translocation ◽

Color Flow

AbstractLatent infectious agents, microbial translocation, some metabolites and immune cell subpopulations, as well as senescence modulate the level and quality of activation of our immune system. Here, we tested whether various in vivo immune activation profiles may be distinguished in a general population. We measured 43 markers of immune activation by 8-color flow cytometry and ELISA in 150 adults, and performed a double hierarchical clustering of biomarkers and volunteers. We identified five different immune activation profiles. Profile 1 had a high proportion of naïve T cells. By contrast, Profiles 2 and 3 had an elevated percentage of terminally differentiated and of senescent CD4+ T cells and CD8+ T cells, respectively. The fourth profile was characterized by NK cell activation, and the last profile, Profile 5, by a high proportion of monocytes. In search for etiologic factors that could determine these profiles, we observed a high frequency of naïve Treg cells in Profile 1, contrasting with a tendency to a low percentage of Treg cells in Profiles 2 and 3. Moreover, Profile 5 tended to have a high level of 16s ribosomal DNA, a direct marker of microbial translocation. These data are compatible with a model in which specific causes, as the frequency of Treg or the level of microbial translocation, shape specific profiles of immune activation. It will be of interest to analyze whether some of these profiles drive preferentially some morbidities known to be fueled by immune activation, as insulin resistance, atherothrombosis or liver steatosis.

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In Vivo Detection of Dendritic Cell Antigen Presentation to CD4+ T Cells

Journal of Experimental Medicine ◽

10.1084/jem.185.12.2133 ◽

1997 ◽

Vol 185 (12) ◽

pp. 2133-2141 ◽

Cited By ~ 380

Author(s):

Elizabeth Ingulli ◽

Anna Mondino ◽

Alexander Khoruts ◽

Marc K. Jenkins

Keyword(s):

T Cells ◽

T Cell ◽

Lymph Nodes ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Delayed Type Hypersensitivity ◽

Physical Interaction

Although lymphoid dendritic cells (DC) are thought to play an essential role in T cell activation, the initial physical interaction between antigen-bearing DC and antigen-specific T cells has never been directly observed in vivo under conditions where the specificity of the responding T cells for the relevant antigen could be unambiguously assessed. We used confocal microscopy to track the in vivo location of fluorescent dye-labeled DC and naive TCR transgenic CD4+ T cells specific for an OVA peptide–I-Ad complex after adoptive transfer into syngeneic recipients. DC that were not exposed to the OVA peptide, homed to the paracortical regions of the lymph nodes but did not interact with the OVA peptide-specific T cells. In contrast, the OVA peptide-specific T cells formed large clusters around paracortical DC that were pulsed in vitro with the OVA peptide before injection. Interactions were also observed between paracortical DC of the recipient and OVA peptide-specific T cells after administration of intact OVA. Injection of OVA peptide-pulsed DC caused the specific T cells to produce IL-2 in vivo, proliferate, and differentiate into effector cells capable of causing a delayed-type hypersensitivity reaction. Surprisingly, by 48 h after injection, OVA peptide-pulsed, but not unpulsed DC disappeared from the lymph nodes of mice that contained the transferred TCR transgenic population. These results demonstrate that antigen-bearing DC directly interact with naive antigen-specific T cells within the T cell–rich regions of lymph nodes. This interaction results in T cell activation and disappearance of the DC.

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Leishmania promastigotes evade interleukin 12 (IL-12) induction by macrophages and stimulate a broad range of cytokines from CD4+ T cells during initiation of infection.

Journal of Experimental Medicine ◽

10.1084/jem.179.2.447 ◽

1994 ◽

Vol 179 (2) ◽

pp. 447-456 ◽

Cited By ~ 231

Author(s):

S L Reiner ◽

S Zheng ◽

Z E Wang ◽

L Stowring ◽

R M Locksley

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Leishmania Major ◽

Interleukin 12 ◽

Insect Vector ◽

T Helper 1 ◽

Ifn Gamma ◽

Effector Cells

Leishmania major are intramacrophage parasites whose eradication requires the induction of T helper 1 (Th1) effector cells capable of activating macrophages to a microbicidal state. Interleukin 12 (IL-12) has been recently identified as a macrophage-derived cytokine capable of mediating Th1 effector cell development, and of markedly enhancing interferon gamma (IFN-gamma) production by T cells and natural killer cells. Infection of macrophages in vitro by promastigotes of L. major caused no induction of IL-12 p40 transcripts, whereas stimulation using heat-killed Listeria or bacterial lipopolysaccharide induced readily detectable IL-12 mRNA. Using a competitor construct to quantitate a number of transcripts, a kinetic analysis of cytokine induction during the first few days of infection by L. major was performed. All strains of mice examined, including susceptible BALB/c and resistant C57BL/6, B10.D2, and C3H/HeN, had the appearance of a CD4+ population in the draining lymph nodes that contained transcripts for IL-2, IL-4, and IFN-gamma (and in some cases, IL-10) that peaked 4 d after infection. In resistant mice, the transcripts for IL-2, IL-4, and IL-10 were subsequently downregulated, whereas in susceptible BALB/c mice, these transcripts were only slightly decreased, and IL-4 continued to be reexpressed at high levels. IL-12 transcripts were first detected in vivo by 7 d after infection, consistent with induction by intracellular amastigotes. Challenge of macrophages in vitro confirmed that amastigotes, in contrast to promastigotes, induced IL-12 p40 mRNA. Reexamination of the cytokine mRNA at 4 d revealed expression of IL-13 in all strains analyzed, suggesting that IL-2 and IL-13 may mediate the IL-12-independent production of IFN-gamma during the first days after infection. Leishmania have evolved to avoid inducing IL-12 from host macrophages during transmission from the insect vector, and cause a striking induction of mRNAs for IL-2, IL-4, IL-10, and IL-13 in CD4+ T cells. Each of these activities may favor survival of the organism.

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The lymphoproliferative defect in CTLA-4–deficient mice is ameliorated by an inhibitory NK cell receptor

Blood ◽

10.1182/blood.v99.12.4509 ◽

2002 ◽

Vol 99 (12) ◽

pp. 4509-4516 ◽

Cited By ~ 8

Author(s):

Cynthia A. Chambers ◽

Joonsoo Kang ◽

Yongjian Wu ◽

Werner Held ◽

David H. Raulet ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Nk Cell ◽

T Cell Homeostasis ◽

Cell Homeostasis ◽

Cell Responses ◽

Deficient Mice

T-cell responses are regulated by activating and inhibiting signals. CD28 and its homologue, cytotoxic T-lymphocyte antigen 4 (CTLA-4), are the primary regulatory molecules that enhance or inhibit T-cell activation, respectively. Recently it has been shown that inhibitory natural killer (NK) cell receptors (NKRs) are expressed on subsets of T cells. It has been proposed that these receptors may also play an important role in regulating T-cell responses. However, the extent to which the NKRs modulate peripheral T-cell homeostasis and activation in vivo remains unclear. In this report we show that NK cell inhibitory receptor Ly49A engagement on T cells dramatically limits T-cell activation and the resultant lymphoproliferative disorder that occurs in CTLA-4–deficient mice. Prevention of activation and expansion of the potentially autoreactive CTLA-4−/− T cells by the Ly49A-mediated inhibitory signal demonstrates that NKR expression can play an important regulatory role in T-cell homeostasis in vivo. These results demonstrate the importance of inhibitory signals in T-cell homeostasis and suggest the common biochemical basis of inhibitory signaling pathways in T lymphocytes.

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Critical Contribution of Ox40 Ligand to T Helper Cell Type 2 Differentiation in Experimental Leishmaniasis

Journal of Experimental Medicine ◽

10.1084/jem.191.2.375 ◽

2000 ◽

Vol 191 (2) ◽

pp. 375-380 ◽

Cited By ~ 176

Author(s):

Hisaya Akiba ◽

Yasushi Miyahira ◽

Machiko Atsuta ◽

Kazuyoshi Takeda ◽

Chiyoko Nohara ◽

...

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Leishmania Major ◽

Critical Role ◽

Flow Cytometric Analysis ◽

Th2 Cells ◽

Mouse Strains ◽

T Helper

Infection of inbred mouse strains with Leishmania major is a well characterized model for analysis of T helper (Th)1 and Th2 cell development in vivo. In this study, to address the role of costimulatory molecules CD27, CD30, 4-1BB, and OX40, which belong to the tumor necrosis factor receptor superfamily, in the development of Th1 and Th2 cells in vivo, we administered monoclonal antibody (mAb) against their ligands, CD70, CD30 ligand (L), 4-1BBL, and OX40L, to mice infected with L. major. Whereas anti-CD70, anti-CD30L, and anti–4-1BBL mAb exhibited no effect in either susceptible BALB/c or resistant C57BL/6 mice, the administration of anti-OX40L mAb abrogated progressive disease in BALB/c mice. Flow cytometric analysis indicated that OX40 was expressed on CD4+ T cells and OX40L was expressed on CD11c+ dendritic cells in the popliteal lymph nodes of L. major–infected BALB/c mice. In vitro stimulation of these CD4+ T cells showed that anti-OX40L mAb treatment resulted in substantially reduced production of Th2 cytokines. Moreover, this change in cytokine levels was associated with reduced levels of anti–L. major immunoglobulin (Ig)G1 and serum IgE. These results indicate that anti-OX40L mAb abrogated progressive leishmaniasis in BALB/c mice by suppressing the development of Th2 responses, substantiating a critical role of OX40–OX40L interaction in Th2 development in vivo.

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A Dynamic Map of Antigen Recognition by CD4 T Cells at the Site of Leishmania major Infection

Cell Host & Microbe ◽

10.1016/j.chom.2009.04.014 ◽

2009 ◽

Vol 6 (1) ◽

pp. 23-33 ◽

Cited By ~ 62

Author(s):

Orchidée Filipe-Santos ◽

Pascale Pescher ◽

Béatrice Breart ◽

Christoph Lippuner ◽

Toni Aebischer ◽

...

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Leishmania Major ◽

Antigen Recognition ◽

Major Infection ◽

Dynamic Map

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MHC Class II Expression Restricted to CD8α+ and CD11b+ Dendritic Cells Is Sufficient for Control of Leishmania major

Journal of Experimental Medicine ◽

10.1084/jem.20030795 ◽

2004 ◽

Vol 199 (5) ◽

pp. 725-730 ◽

Cited By ~ 52

Author(s):

Maria P. Lemos ◽

Fatima Esquivel ◽

Phillip Scott ◽

Terri M. Laufer

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Cell ◽

Antigen Presentation ◽

Cd4 T Cells ◽

Leishmania Major ◽

Cd4 T Cell ◽

Major Infection ◽

Mhc Ii ◽

Antigen Presenting

Control of the intracellular protozoan, Leishmania major, requires major histocompatibility complex class II (MHC II)–dependent antigen presentation and CD4+ T cell T helper cell 1 (Th1) differentiation. MHC II–positive macrophages are a primary target of infection and a crucial effector cell controlling parasite growth, yet their function as antigen-presenting cells remains controversial. Similarly, infected Langerhans cells (LCs) can prime interferon (IFN)γ–producing Th1 CD4+ T cells, but whether they are required for Th1 responses is unknown. We explored the antigen-presenting cell requirement during primary L. major infection using a mouse model in which MHC II, I-Aβb, expression is restricted to CD11b+ and CD8α+ dendritic cells (DCs). Importantly, B cells, macrophages, and LCs are all MHC II–negative in these mice. We demonstrate that antigen presentation by these DC subsets is sufficient to control a subcutaneous L. major infection. CD4+ T cells undergo complete Th1 differentiation with parasite-specific secretion of IFNγ. Macrophages produce inducible nitric oxide synthase, accumulate at infected sites, and control parasite numbers in the absence of MHC II expression. Therefore, CD11b+ and CD8α+ DCs are not only key initiators of the primary response but also provide all the necessary cognate interactions for CD4+ T cell Th1 effectors to control this protozoan infection.

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Novel APC-like properties of human NK cells directly regulate T cell activation

10.1101/016816 ◽

2015 ◽

Author(s):

Jacob Hanna ◽

Ofer Mandelboim

Keyword(s):

T Cells ◽

T Cell ◽

Nk Cells ◽

Mhc Class Ii ◽

T Cell Activation ◽

Cell Activation ◽

Nk Cell ◽

Adaptive Immune Response ◽

Antigen Uptake

Initiation of the adaptive immune response is dependent on the priming of naive T cells by APCs. Proteomic analysis of unactivated and activated human NK cell membrane-enriched fractions demonstrated that activated NK cells can efficiently stimulate T cells, since they upregulate MHC class II molecules and multiple ligands for TCR costimulatory molecules. Furthermore, by manipulating antigen administration, we show that NK cells possess multiple independent unique pathways for antigen uptake. These results highlight NK cell-mediated cytotoxicity and specific ligand recognition by cell surface-activating receptors on NK cells as unique mechanisms for antigen capturing and presentation. In addition, we analyzed the T cell-activating potential of human NK cells derived from different clinical conditions, such as inflamed tonsils and noninfected and CMV-infected uterine decidual samples, and from transporter-associated processing antigen 2–deficient patients. This in vivo analysis revealed that proinflammatory, but not immune-suppressive, microenvironmental requirements can selectively dictate upregulation of T cell-activating molecules on NK cells. Taken together, these observations offer new and unexpected insights into the direct interactions between NK and T cells and suggest novel APC-like activating functions for human NK cells.

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DOCK2 sets the threshold for entry into the virtual memory CD8+ T cell compartment by negatively regulating tonic TCR triggering

10.1101/582486 ◽

2019 ◽

Cited By ~ 1

Author(s):

Ezana Demissie ◽

Vinay S Mahajan ◽

Faisal Alsufyani ◽

Sudha Kumari ◽

Grace J Yuen ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Activation ◽

Nk Cell ◽

Ex Vivo ◽

Virtual Memory ◽

Actin Dynamics ◽

Immune Functions ◽

Cell Compartment

AbstractThe control of cytoskeletal dynamics by Dedicator of cytokinesis 2 (DOCK2), a hematopoietic cell-specific actin effector protein, has been implicated in TCR signaling and T cell migration. Biallelic mutations in Dock2 have been identified in patients with a recessive form of combined immunodeficiency with defects in T, B and NK cell activation. Surprisingly, we show here that certain immune functions of CD8+ T cells are enhanced in the absence of DOCK2. Dock2-deficient mice have a pronounced expansion of their memory T cell compartment. Bone marrow chimera and adoptive transfer studies indicate that these memory T cells develop in a cell-intrinsic manner following thymic egress. Transcriptional profiling, TCR repertoire analyses and cell surface marker expression indicate that Dock2-deficient naive CD8+ T cells directly convert into virtual memory cells without clonal effector T cell expansion. This direct conversion to memory is associated with a selective increase in TCR sensitivity to selfpeptide MHC in vivo and an enhanced response to weak agonist peptides ex vivo. In contrast, the response to strong agonist peptides remains unaltered in Dock2-deficient T cells. Collectively, these findings suggest that the regulation of the actin dynamics by DOCK2 enhances the threshold for entry into the virtual memory compartment by negatively regulating tonic TCR triggering in response to weak agonists.

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