scholarly journals CD4+ T Cells and Toll-Like Receptors Recognize Salmonella Antigens Expressed in Bacterial Surface Organelles

2005 ◽  
Vol 73 (3) ◽  
pp. 1350-1356 ◽  
Author(s):  
Molly A. Bergman ◽  
Lisa A. Cummings ◽  
Sara L. Rassoulian Barrett ◽  
Kelly D. Smith ◽  
J. Cano Lara ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Membrane Vesicles ◽  
Surface Modifications ◽  
Immune Recognition ◽  
Toll Like Receptors ◽  
Bacterial Surface ◽  
Host Immune Responses ◽  
Adaptive Immune ◽  
Host Tissues

ABSTRACT A better understanding of immunity to infection is revealed from the characteristics of microbial ligands recognized by host immune responses. Murine infection with the intracellular bacterium Salmonella generates CD4+ T cells that specifically recognize Salmonella proteins expressed in bacterial surface organelles such as flagella and membrane vesicles. These natural Salmonella antigens are also ligands for Toll-like receptors (TLRs) or avidly associated with TLR ligands such as lipopolysaccharide (LPS). PhoP/PhoQ, a regulon controlling Salmonella virulence and remodeling of LPS to resist innate immunity, coordinately represses production of surface-exposed antigens recognized by CD4+ T cells and TLRs. These data suggest that genetically coordinated surface modifications may provide a growth advantage for Salmonella in host tissues by limiting both innate and adaptive immune recognition.

scholarly journals Opa+ and Opa− Isolates of Neisseria meningitidis and Neisseria gonorrhoeae Induce Sustained Proliferative Responses in Human CD4+ T Cells

2009 ◽  
Vol 77 (11) ◽  
pp. 5170-5180 ◽  
Author(s):  
Abdel-Rahman Youssef ◽  
Michiel van der Flier ◽  
Silvia Estevão ◽  
Nico G. Hartwig ◽  
Peter van der Ley ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Neisseria Meningitidis ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Activated T Cells ◽  
Bacterial Surface ◽  
Host Immune Responses ◽  
Cell Functions

ABSTRACT T cells may interact with a number of bacterial surface antigens, an encounter which has the potential to downmodulate host immune responses. Neisseria meningitidis, a human colonizer and an agent of septicemia and meningitis, expresses Opa proteins which interact with the CEACAM1 receptor expressed on activated T cells. Since CEACAM1 can act as an inhibitory receptor and T cells in subepithelial tissues may encounter whole bacteria, which often express Opa proteins in vivo, this study assessed primarily if Opa proteins expressed on meningococci affect T-cell functions. In addition, Opa-containing outer membrane vesicles (OMV) have been used as vaccine antigens, and therefore Opa+ and Opa− OMV were also studied. While Opa+ bacteria adhered to CEACAM-expressing T cells, both the Opa+ and Opa− phenotypes induced no to a small transient depression, followed by a prolonged increase in proliferation as well as cytokine production. Such responses were also observed with heat-killed bacteria or OMV. In addition, while anti-CEACAM antibodies alone inhibited proliferation, on coincubation of T cells with bacteria and the antibodies, bacterial effects predominated and were Opa independent. Thus, while Opa proteins of N. meningitidis can bind to T-cell-expressed CEACAM1, this is not sufficient to overcome the T-cell recognition of bacterial factors, which results in a proliferative and cytokine response, an observation consistent with the ability of the host to establish lasting immunity to Opa-expressing meningococci that it frequently encounters. The data also imply that Opa-proficient vaccine preparations may not necessarily inhibit T-cell functions via CEACAM1 binding.

scholarly journals Severe Symptomatic Primary Human Cytomegalovirus Infection despite Effective Innate and Adaptive Immune Responses

2016 ◽  
Vol 91 (5) ◽  
Author(s):  
Raphaëlle Riou ◽  
Céline Bressollette-Bodin ◽  
David Boutoille ◽  
Katia Gagne ◽  
Audrey Rodallec ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Human Cytomegalovirus ◽  
Hcmv Infection ◽  
Cytokine Production ◽  
Lymphocyte Activation ◽  
Adaptive Immune Responses ◽  
Host Immune Responses ◽  
Adaptive Immune ◽  
Cell Compartments

ABSTRACT Primary human cytomegalovirus (HCMV) infection usually goes unnoticed, causing mild or no symptoms in immunocompetent individuals. However, some rare severe clinical cases have been reported without investigation of host immune responses or viral virulence. In the present study, we investigate for the first time phenotypic and functional features, together with gene expression profiles in immunocompetent adults experiencing a severe primary HCMV infection. Twenty primary HCMV-infected patients (PHIP) were enrolled, as well as 26 HCMV-seronegative and 39 HCMV-seropositive healthy controls. PHIP had extensive lymphocytosis marked by massive expansion of natural killer (NK) and T cell compartments. Interestingly, PHIP mounted efficient innate and adaptive immune responses with a deep HCMV imprint, revealed mainly by the expansion of NKG2C+ NK cells, CD16+ Vδ2(−) γδ T cells, and conventional HCMV-specific CD8+ T cells. The main effector lymphocytes were activated and displayed an early immune phenotype that developed toward a more mature differentiated status. We suggest that both massive lymphocytosis and excessive lymphocyte activation could contribute to massive cytokine production, known to mediate tissue damage observed in PHIP. Taken together, these findings bring new insights into the comprehensive understanding of immune mechanisms involved during primary HCMV infection in immunocompetent individuals. IMPORTANCE HCMV-specific immune responses have been extensively documented in immunocompromised patients and during in utero acquisition. While it usually goes unnoticed, some rare severe clinical cases of primary HCMV infection have been reported in immunocompetent patients. However, host immune responses or HCMV virulence in these patients has not so far been investigated. In the present study, we show massive expansion of NK and T cell compartments during the symptomatic stage of acute HCMV infection. The patients mounted efficient innate and adaptive immune responses with a deep HCMV imprint. The massive lymphocytosis could be the result of nonadapted or uncontrolled immune responses limiting the effectiveness of the specific responses mounted. Both massive lymphocytosis and excessive lymphocyte activation could contribute to massive cytokine production, known to mediate tissue damage. Furthermore, we cannot exclude a delayed immune response caused by immune escape established by HCMV strains.

scholarly journals Multiomic Immunophenotyping of COVID-19 Patients Reveals Early Infection Trajectories

2020 ◽  
Author(s):  
Yapeng Su ◽  
Daniel Chen ◽  
Christopher Lausted ◽  
Dan Yuan ◽  
Jongchan Choi ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Immune Responses ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Surface Proteins ◽  
Host Immune Responses ◽  
Therapeutic Development ◽  
Clinical Measures ◽  
Whole Transcriptome

SUMMARYHost immune responses play central roles in controlling SARS-CoV2 infection, yet remain incompletely characterized and understood. Here, we present a comprehensive immune response map spanning 454 proteins and 847 metabolites in plasma integrated with single-cell multi-omic assays of PBMCs in which whole transcriptome, 192 surface proteins, and T and B cell receptor sequence were co-analyzed within the context of clinical measures from 50 COVID19 patient samples. Our study reveals novel cellular subpopulations, such as proliferative exhausted CD8+ and CD4+ T cells, and cytotoxic CD4+ T cells, that may be features of severe COVID-19 infection. We condensed over 1 million immune features into a single immune response axis that independently aligns with many clinical features and is also strongly associated with disease severity. Our study represents an important resource towards understanding the heterogeneous immune responses of COVID-19 patients and may provide key information for informing therapeutic development.

scholarly journals STING: a master regulator in the cancer-immunity cycle

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Yuanyuan Zhu ◽  
Xiang An ◽  
Xiao Zhang ◽  
Yu Qiao ◽  
Tongsen Zheng ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Immune Responses ◽  
Type I Interferons ◽  
Type I ◽  
Type I Ifn ◽  
Negative Effects ◽  
Independent Manner ◽  
Adaptive Immune ◽  
Cancer Immunity

Abstract The aberrant appearance of DNA in the cytoplasm triggers the activation of cGAS-cGAMP-STING signaling and induces the production of type I interferons, which play critical roles in activating both innate and adaptive immune responses. Recently, numerous studies have shown that the activation of STING and the stimulation of type I IFN production are critical for the anticancer immune response. However, emerging evidence suggests that STING also regulates anticancer immunity in a type I IFN-independent manner. For instance, STING has been shown to induce cell death and facilitate the release of cancer cell antigens. Moreover, STING activation has been demonstrated to enhance cancer antigen presentation, contribute to the priming and activation of T cells, facilitate the trafficking and infiltration of T cells into tumors and promote the recognition and killing of cancer cells by T cells. In this review, we focus on STING and the cancer immune response, with particular attention to the roles of STING activation in the cancer-immunity cycle. Additionally, the negative effects of STING activation on the cancer immune response and non-immune roles of STING in cancer have also been discussed.

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