scholarly journals Insights on the mechanisms of the protective immunity in the brain from the studies on infection with an intracellular microorganism, Toxoplasma gondii

2021 ◽  
Vol 9 (11) ◽  
Author(s):  
Yasuhiro Suzuki
Keyword(s):  
T Cells ◽  
Toxoplasma Gondii ◽  
Cd8 T Cells ◽  
Protective Immunity ◽  
Early Stage ◽  
Cytotoxic T Cells ◽  
Host Cells ◽  
Protective Mechanism ◽  
Dependent Manner ◽  
The Brain

The immune system operates the protection against infections by selecting efficient pathways depending on the pathogen. Toxoplasma gondii, an obligate intracellular protozoan parasite, has two lifecycle stages, tachyzoite and cyst, in intermediate hosts including humans. Tachyzoite is the acute stage form that quickly proliferates within host cells. Cyst is the chronic stage form that can slowly grow into more than 100 mm in diameter by containing hundreds to thousands of bradyzoites. Our studies on the IFN-g-mediated protective immunity against cerebral tachyzoite growth revealed that IFN-g production by brain-resident cells is not only required for upregulation of the innate protective immunity to limit cerebral tachyzoite proliferation during the early stage of the tachyzoite growth but also crucial for recruiting immune T cells from the periphery and activation of the recruited T cells to ultimately prevent the tachyzoite growth. Since IFN-g is crucial for the protective immunity against various intracellular microorganisms in the brain, it is possible that IFN-gproduced by brain-resident cells plays a key first line defense role by orchestrating both the innate and T cell-mediated protective immunity to control not only T. gondii but also the other intracellular pathogens. Our studies on the protective immunity against T. gondii cysts uncovered the capability of cytotoxic T cells to penetrate into the target in a perforin-dependent manner for its elimination. After penetrating into the target, the cytotoxic T cells secrete granzyme B, which associates with an accumulation of phagocytes to eliminate the parasite. Since the presence of tumor-infiltrating CD8+ T cells in solid cancers is an indicator of positive prognosis of cancer patients, the perforin-mediated penetration of CD8+ T cells and an accumulation of phagocytes could function as a powerful protective mechanism against not only T. gondiicysts but also targets of large mass in general such as solid cancers.

scholarly journals Selective Upregulation of Transcripts for Six Molecules Related to T Cell Costimulation and Phagocyte Recruitment and Activation among 734 Immunity-Related Genes in the Brain during Perforin-Dependent, CD8+ T Cell-Mediated Elimination of Toxoplasma gondii Cysts

mSystems ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Jenny Lutshumba ◽  
Eri Ochiai ◽  
Qila Sa ◽  
Namrata Anand ◽  
Yasuhiro Suzuki
Keyword(s):  
T Cells ◽  
T Cell ◽  
Toxoplasma Gondii ◽  
Molecular Mechanisms ◽  
Cytotoxic T Cells ◽  
Scid Mice ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Content Type ◽  
Immune Related Genes

ABSTRACT We recently found that an invasion of CD8+ cytotoxic T cells into tissue cysts of Toxoplasma gondii initiates an elimination of the cysts in association with an accumulation of microglia and macrophages. In the present study, we compared mRNA levels for 734 immune-related genes in the brains of infected SCID mice that received perforin-sufficient or -deficient CD8+ immune T cells at 3 weeks after infection. At 7 days after the T cell transfer, mRNA levels for only six genes were identified to be greater in the recipients of the perforin-sufficient T cells than in the recipients of the perforin-deficient T cells. These six molecules included two T cell costimulatory molecules, inducible T cell costimulator receptor (ICOS) and its ligand (ICOSL); two chemokine receptors, C-X-C motif chemokine receptor 3 (CXCR3) and CXCR6; and two molecules related to an activation of microglia and macrophages, interleukin 18 receptor 1 (IL-18R1) and chitinase-like 3 (Chil3). Consistently, a marked reduction of cyst numbers and upregulation of ICOS, CXCR3, CXCR6, IL-18R1, and Chil3 mRNA levels were also detected when the perforin-sufficient CD8+ immune T cells were transferred to infected SCID mice at 6 weeks after infection, indicating that the CD8+ T cell-mediated protective immunity is capable of eliminating mature T. gondii cysts. These results together suggest that ICOS-ICOSL interactions are crucial for activating CD8+ cytotoxic immune T cells to initiate the destruction of T. gondii cysts and that CXCR3, CXCR6, and IL-18R are involved in recruitment and activation of microglia and macrophages to the T cell-attacked cysts for their elimination. IMPORTANCE T. gondii establishes a chronic infection by forming tissue cysts, which can grow into sizes greater than 50 μm in diameter as a consequence of containing hundreds to thousands of organisms surrounded by the cyst wall within infected cells. Our recent studies using murine models uncovered that CD8+ cytotoxic T cells penetrate into the cysts in a perforin-dependent manner and induce their elimination, which is accompanied with an accumulation of phagocytic cells to the T cell-attacked target. This is the first evidence of the ability of the T cells to invade into a large target for its elimination. However, the mechanisms involved in anticyst immunity remain unclear. Immune profiling analyses of 734 immune-related genes in the present study provided a valuable foundation to initiate elucidating detailed molecular mechanisms of the novel effector function of the immune system operated by perforin-mediated invasion of CD8+ T cells into large targets for their elimination.

scholarly journals Host ER–parasitophorous vacuole interaction provides a route of entry for antigen cross-presentation in Toxoplasma gondii–infected dendritic cells

2009 ◽  
Vol 206 (2) ◽  
pp. 399-410 ◽  
Author(s):  
Romina S. Goldszmid ◽  
Isabelle Coppens ◽  
Avital Lev ◽  
Pat Caspar ◽  
Ira Mellman ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Toxoplasma Gondii ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Parasitophorous Vacuole ◽  
Host Cells ◽  
Class I ◽  
Cross Presentation ◽  
Infected Cells

Toxoplasma gondii tachyzoites infect host cells by an active invasion process leading to the formation of a specialized compartment, the parasitophorous vacuole (PV). PVs resist fusion with host cell endosomes and lysosomes and are thus distinct from phagosomes. Because the parasite remains sequestered within the PV, it is unclear how T. gondii–derived antigens (Ag’s) access the major histocompatibility complex (MHC) class I pathway for presentation to CD8+ T cells. We demonstrate that recruitment of host endoplasmic reticulum (hER) to the PV in T. gondii–infected dendritic cells (DCs) directly correlates with cross-priming of CD8+ T cells. Furthermore, we document by immunoelectron microscopy the transfer of hER components into the PV, a process indicative of direct fusion between the two compartments. In strong contrast, no association between hER and phagosomes or Ag presentation activity was observed in DCs containing phagocytosed live or dead parasites. Importantly, cross-presentation of parasite-derived Ag in actively infected cells was blocked when hER retrotranslocation was inhibited, indicating that the hER serves as a conduit for the transport of Ag between the PV and host cytosol. Collectively, these findings demonstrate that pathogen-driven hER–PV interaction can serve as an important mechanism for Ag entry into the MHC class I pathway and CD8+ T cell cross-priming.

scholarly journals Naïve CD8 T cell IFNγ responses to a vacuolar antigen are regulated by an inflammasome-independent NLRP3 pathway and Toxoplasma gondii ROP5

2020 ◽  
Author(s):  
Angel K. Kongsomboonvech ◽  
Felipe Rodriguez ◽  
Anh L. Diep ◽  
Brandon M. Justice ◽  
Brayan E. Castallanos ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Toxoplasma Gondii ◽  
Cd8 T Cells ◽  
Immune Cell ◽  
Cd8 T Cell ◽  
Inflammasome Activation ◽  
Phenotypic Variance ◽  
Dependent Manner ◽  
Presentation Pathway

ABSTRACTHost resistance to Toxoplasma gondii relies on CD8 T cell IFNγ responses, which if modulated by the host or parasite could influence chronic infection and parasite transmission between hosts. Since host-parasite interactions that govern this response are not fully elucidated, we investigated requirements for eliciting naïve CD8 T cell IFNγ responses to a vacuolar resident antigen of T. gondii, TGD057. Naïve TGD057 antigen-specific CD8 T cells (T57) were isolated from transnuclear mice and responded to parasite-infected bone marrow-derived macrophages (BMDMs) in an antigen-dependent manner, first by producing IL-2 and then IFNγ. T57 IFNγ responses to TGD057 were independent of the parasite’s protein export machinery ASP5 and MYR1. Instead, host immunity pathways downstream of the regulatory Immunity-Related GTPases (IRG), including partial dependence on Guanylate-Binding Proteins, are required. Multiple T. gondii ROP5 isoforms and allele types, including ‘avirulent’ ROP5A from clade A and D parasite strains, were able to suppress CD8 T cell IFNγ responses to parasite-infected BMDMs. Phenotypic variance between clades B, C, D, F, and A strains suggest T57 IFNγ differentiation occurs independently of parasite virulence or any known IRG-ROP5 interaction. Consistent with this, removal of ROP5 is not enough to elicit maximal CD8 T cell IFNγ production to parasite-infected cells. Instead, macrophage expression of the pathogen sensors, NLRP3 and to a large extent NLRP1, were absolute requirements. Other members of the conventional inflammasome cascade are only partially required, as revealed by decreased but not abrogated T57 IFNγ responses to parasite-infected ASC, caspase-1/11, and gasdermin D deficient cells. Moreover, IFNγ production was only partially reduced in the absence of IL-12, IL-18 or IL-1R signaling. In summary, T. gondii effectors and host machinery that modulate parasitophorous vacuolar membranes, as well as NLR-dependent but inflammasome-independent pathways, determine the full commitment of CD8 T cells IFNγ responses to a vacuolar antigen.AUTHOR SUMMARYParasites are excellent “students” of our immune system as they can deflect, antagonize and confuse the immune response making it difficult to vaccinate against these pathogens. In this report, we analyzed how a widespread parasite of mammals, Toxoplasma gondii, manipulates an immune cell needed for immunity to many intracellular pathogens, the CD8 T cell. Host pathways that govern CD8 T cell production of the immune protective cytokine, IFNγ, were also explored. We hypothesized the secreted Toxoplasma virulence factor, ROP5, work to inhibit the MHC 1 antigen presentation pathway therefore making it difficult for CD8 T cells to see T. gondii antigens sequestered inside a parasitophorous vacuole. However, manipulation through T. gondii ROP5 does not fully explain how CD8 T cells commit to making IFNγ in response to infection. Importantly, CD8 T cell IFNγ responses to T. gondii require the pathogen sensor NLRP3 to be expressed in the infected cell. Other proteins associated with NLRP3 activation, including members of the conventional inflammasome activation cascade pathway, are only partially involved. Our results identify a novel pathway by which NLRP3 regulates T cell function and underscore the need for inflammasome-activating adjuvants in vaccines aimed at inducing CD8 T cell IFNγ responses to parasites.

scholarly journals Cytotoxic activities of CD8+ T cells collaborate with macrophages to protect against blood-stage murine malaria

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Takashi Imai ◽  
Hidekazu Ishida ◽  
Kazutomo Suzue ◽  
Tomoyo Taniguchi ◽  
Hiroko Okada ◽  
...  
Keyword(s):  
T Cells ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
Protective Immunity ◽  
Molecular Mechanisms ◽  
Blood Stage ◽  
Class I ◽  
Cytotoxic Activities ◽  
Dependent Manner ◽  
Blood Stage Malaria

The protective immunity afforded by CD8+ T cells against blood-stage malaria remains controversial because no MHC class I molecules are displayed on parasite-infected human erythrocytes. We recently reported that rodent malaria parasites infect erythroblasts that express major histocompatibility complex (MHC) class I antigens, which are recognized by CD8+ T cells. In this study, we demonstrate that the cytotoxic activity of CD8+ T cells contributes to the protection of mice against blood-stage malaria in a Fas ligand (FasL)-dependent manner. Erythroblasts infected with malarial parasites express the death receptor Fas. CD8+ T cells induce the externalization of phosphatidylserine (PS) on the infected erythroblasts in a cell-to-cell contact-dependent manner. PS enhances the engulfment of the infected erythroid cells by phagocytes. As a PS receptor, T-cell immunoglobulin-domain and mucin-domain-containing molecule 4 (Tim-4) contributes to the phagocytosis of malaria-parasite-infected cells. Our findings provide insight into the molecular mechanisms underlying the protective immunity exerted by CD8+ T cells in collaboration with phagocytes.

scholarly journals Removal of Toxoplasma gondii Cysts from the Brain by Perforin-Mediated Activity of CD8+ T Cells

2010 ◽  
Vol 176 (4) ◽  
pp. 1607-1613 ◽  
Author(s):  
Yasuhiro Suzuki ◽  
Xisheng Wang ◽  
Benard S. Jortner ◽  
Laura Payne ◽  
Yanyan Ni ◽  
...  
Keyword(s):  
T Cells ◽  
Toxoplasma Gondii ◽  
Cd8 T Cells ◽  
The Brain

The Lymphoid Chemokine CCL21 Enhances the Migration- and CTL-Inducing Functions of Dendritic Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1127-1127
Author(s):  
Cheol Yi Hong ◽  
Pawel Kalinski ◽  
Hyeoung-Joon Kim ◽  
Je-Jung Lee
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Cd8 T Cells ◽  
Conflicts Of Interest ◽  
Cytotoxic T Cells ◽  
Lymphoid Organ ◽  
Lymphoid Organs ◽  
Dependent Manner ◽  
Migratory Capacity ◽  
Secondary Lymphoid Organs

Abstract Abstract 1127 The migration of dendritic cells (DCs) to secondary lymphoid organs is very important to elicit an adaptive immune response in cancer immunotherapy. Here, we show the effect of lymphoid cytokine on the ability of maturing DCs to migrate in response to the lymph node-associated chemokines. The secondary-lymphoid organ chemokine (SLC/CCL21) during DC maturation dramatically enhanced DC migratory capacity responding to CCL21 and CCL19, and, moreover, produced strongly enhanced cytotoxic T cells, although it did not affect the expression of cell surface markers such as CD80, CD83, CD86, and CCR7 and the production of cytokines such as IL-12p70, IL-10, and IL-23. Mature DCs (mDCs) exposed by chemokine produced higher levels of CXCL10 (IP-10) that is one of the chemokines involved in Th1 attraction, but did not affect the production of Th2-attracting cytokine CCL22, compared with unstimulated mDCs. CCL21-exposed DCs induced strongly enhanced numbers of the interferon-g (IFN-g)-expressing antigen-specific CD8+ T cells against tumor-specific antigens in an CXCL10-dependent manner. Cytotoxic CD8+ T cells stimulated with CCL21-exposed DCs expressed higher level of IFN-g than those stimulated with control mDCs. Interestingly, generation of cytotoxic T cells (CTLs) stimulated by TNFa/IL-1b/IL-6/PGE2-treated DCs (sDCs) supplemented with IP-10 produced strong cytotoxic T cells expressing higher level of IFN-g. Tetramer assay showed that CCL21-treated DCs enhanced generation of antigen-specific CTLs. Taken together, our data suggest that mDCs pre-stimulated by chemokine CCL21 enhanced migratory capacity to secondary lymphoid organs and produced strong cytotoxic T cells via IP-10 signaling pathway. Disclosures: No relevant conflicts of interest to declare.

scholarly journals VCAM-1/α4β1 Integrin Interaction Is Crucial for Prompt Recruitment of Immune T Cells into the Brain during the Early Stage of Reactivation of Chronic Infection with Toxoplasma gondii To Prevent Toxoplasmic Encephalitis

2014 ◽  
Vol 82 (7) ◽  
pp. 2826-2839 ◽  
Author(s):  
Qila Sa ◽  
Eri Ochiai ◽  
Tomoko Sengoku ◽  
Melinda E. Wilson ◽  
Morgan Brogli ◽  
...  
Keyword(s):  
T Cells ◽  
Toxoplasma Gondii ◽  
Chronic Infection ◽  
Early Stage ◽  
Toxoplasmic Encephalitis ◽  
Mrna Levels ◽  
Wild Type ◽  
Content Type ◽  
Ifn Γ ◽  
The Brain

ABSTRACTReactivation of chronic infection withToxoplasma gondiican cause life-threatening toxoplasmic encephalitis in immunocompromised individuals. We examined the role of VCAM-1/α4β1 integrin interaction in T cell recruitment to prevent reactivation of the infection in the brain. SCID mice were infected and treated with sulfadiazine to establish a chronic infection. VCAM-1 and ICAM-1 were the endothelial adhesion molecules detected on cerebral vessels of the infected SCID and wild-type animals. Immune T cells from infected wild-type mice were treated with anti-α4 integrin or control antibodies and transferred into infected SCID or nude mice, and the animals received the same antibody every other day. Three days later, sulfadiazine was discontinued to initiate reactivation of infection. Expression of mRNAs for CD3δ, CD4, CD8β, gamma interferon (IFN-γ), and inducible nitric oxide synthase (NOS2) (an effector molecule to inhibitT. gondiigrowth) and the numbers of CD4+and CD8+T cells in the brain were significantly less in mice treated with anti-α4 integrin antibody than in those treated with control antibody at 3 days after sulfadiazine discontinuation. At 6 days after sulfadiazine discontinuation, cerebral tachyzoite-specific SAG1 mRNA levels and numbers of inflammatory foci associated with tachyzoites were markedly greater in anti-α4 integrin antibody-treated than in control antibody-treated animals, even though IFN-γ and NOS2 mRNA levels were higher in the former than in the latter. These results indicate that VCAM-1/α4β1 integrin interaction is crucial for prompt recruitment of immune T cells and induction of IFN-γ-mediated protective immune responses during the early stage of reactivation of chronicT. gondiiinfection to control tachyzoite growth.

scholarly journals Lactate potentiates differentiation and expansion of cytotoxic T cells

2019 ◽  
Author(s):  
Helene Rundqvist ◽  
Pedro Veliça ◽  
Laura Barbieri ◽  
Paulo A. Gameiro ◽  
Pedro P. Cunha ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cancer Progression ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Tumour Growth ◽  
Tumour Progression ◽  
Cytotoxic T Cells ◽  
Malignant Tumour ◽  
Dependent Manner

AbstractExercise has a range of effects on metabolism. In animal models, repeated exertion reduces malignant tumour progression, and clinically, exercise can improve outcome for cancer patients. The etiology of the effect of exercise on tumour progression is unclear, as are the cellular actors involved. We show here that exercise-induced reduction in tumour growth is dependent on CD8+ T cells and that lactate, which is produced at high levels during exertion, increases proliferative capacity and cytotoxicity of CD8+ T cells. We found that at elevated levels lactate is used as a fuel during T cell activation. We further found that injection of lactate into animals can reduce malignant tumour growth in a dose-and CD8+ T cell-dependent manner. These data demonstrate that lactate can act to increase the anti-tumour activity of cytotoxic T cells, and in so doing, reduce cancer progression.

scholarly journals Bacterial inhibition of CD8+ T-cells mediated cell death promotes neuroinvasion and within-host persistence

2021 ◽  
Author(s):  
Marc Lecuit ◽  
Claire Maudet ◽  
Marouane Kheloufi ◽  
Sylvain Levallois ◽  
Julien Gaillard ◽  
...  
Keyword(s):  
Central Nervous System ◽  
T Cells ◽  
Cell Death ◽  
Nervous System ◽  
Cd8 T Cells ◽  
Cell Mediated Immunity ◽  
Dependent Manner ◽  
Central Nervous System Infections ◽  
Humanized Mouse Model ◽  
The Brain

Abstract Central nervous system infections are amongst the most severe, yet the mechanisms by which pathogens access the brain remain poorly understood. The model microorganism Listeria monocytogenes (Lm) is a major foodborne pathogen that causes neurolisteriosis, one of the deadliest central nervous system infections. While immunosuppression is a well-established host risk factor for neurolisteriosis, little is known regarding the bacterial factors underlying Lm neuroinvasion. We have developed a clinically-relevant experimental model of neurolisteriosis, using hypervirulent neuroinvasive strains inoculated in a humanized mouse model of infection, and we show that the bacterial protein InlB protects infected monocytes from CD8+ T-cells Fas-mediated cell death, in a c-Met/PI3-kinase/FLIP-dependent manner. This blockade of anti-Lm specific cellular immune response lengthens infected monocytes lifespan, favoring Lm transfer from infected monocytes to the brain. The intracellular niche created by InlB-mediated cell-autonomous immunosuppression also promotes Lm fecal shedding, accounting for its selection as a Lm core virulence gene. Here, we have uncovered an unanticipated specific mechanism by which a bacterial pathogen confers to the cells it infects an increased lifespan by rendering them resistant to cell-mediated immunity. This promotes Lm within-host persistence and dissemination to the central nervous system, and transmission.

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