scholarly journals Chlamydia Lipooligosaccharide Has Varied Direct and Indirect Roles in Evading both Innate and Adaptive Host Immune Responses

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Xisheng Wang ◽  
Daniel D. Rockey ◽  
Brian P. Dolan
Keyword(s):  
Immune Responses ◽  
Cytotoxic T Cell ◽  
Innate Immune Responses ◽  
Content Type ◽  
E Coli ◽  
Host Immune Responses ◽  
Cell Responses ◽  
Direct Delivery ◽  
Cytotoxic T Cell Responses

ABSTRACT Chlamydia bacteria are obligate intracellular pathogens which can cause a variety of disease in humans and other vertebrate animals. To successfully complete its life cycle, Chlamydia must evade both intracellular innate immune responses and adaptive cytotoxic T cell responses. Here, we report on the role of the chlamydial lipooligosaccharide (LOS) in evading the immune response. Chlamydia infection is known to block the induction of apoptosis. However, when LOS synthesis was inhibited during Chlamydia trachomatis infection, HeLa cells regained susceptibility to apoptosis induction following staurosporine treatment. Additionally, the delivery of purified LOS to the cytosol of cells increased the levels of the antiapoptotic protein survivin. An increase in survivin levels was also detected following C. trachomatis infection, which was reversed by blocking LOS synthesis. Interestingly, while intracellular delivery of lipopolysaccharide (LPS) derived from Escherichia coli was toxic to cells, LOS from C. trachomatis did not induce any appreciable cell death, suggesting that it does not activate pyroptosis. Chlamydial LOS was also a poor stimulator of maturation of bone marrow-derived dendritic cells compared to E. coli LPS. Previous work from our group indicated that LOS synthesis during infection was necessary to alter host cell antigen presentation. However, direct delivery of LOS to cells in the absence of infection did not alter antigenic peptide presentation. Taken together, these data suggest that chlamydial LOS, which is remarkably conserved across the genus Chlamydia, may act both directly and indirectly to allow the pathogen to evade the innate and adaptive immune responses of the host.

scholarly journals Vaccinia-specific cytotoxic T-cell responses in the context of H-2 antigens not encountered in thymus may reflect aberrant recognition of a virus-H-2 complex.

1979 ◽  
Vol 149 (1) ◽  
pp. 150-157 ◽  
Author(s):  
P C Doherty ◽  
J C Bennink
Keyword(s):  
T Cells ◽  
T Cell ◽  
Vaccinia Virus ◽  
T Cell Responses ◽  
Cytotoxic T Cell ◽  
Cell Responses ◽  
Antigen Complex ◽  
Infected Cells ◽  
Cytotoxic T Cell Responses

BALB/c (H-2Kd-Dd) spleen and lymph node populations were specifically depleted of alloreactive potential by filtration through H-2 different, irradiated recipients. These negatively selected T cells were then stimulated with vaccinia virus in mice expressing the foreign H-2 determinants encountered previously in the filter environment. Strong virus-immune cytotoxic T-cell responses were seen in the context of H-2Kk and H-2Ks, but not 2H-2Kb. The T cells generated were not cross-reactive for the H-2Kk and H-2Kd alleles, and responsiveness was independent of concurrent presence of effector populations operating at H-2D. These findings are consisent with the idea that recognition is mediated via a complex receptor, part of which is specific for virus and part for self H-2. The capacity to interact with allogeneic, virus-infected cells may then reflect aberrant recognition of a virus-H-2-antigen complex by this single, large binding site. For instance, the T cell which would normally recognize H-2Kd-virus x, or H-2Dd-minor histocompatibility antigen Z, may now show specificity for H-2Kk-vaccinia virus. Implications for both the selective role of the thymus and for mechanisms of tolerance are discussed.

scholarly journals Killer artificial antigen-presenting cells: a novel strategy to delete specific T cells

Blood ◽  
2008 ◽  
Vol 111 (7) ◽  
pp. 3546-3552 ◽  
Author(s):  
Christian Schütz ◽  
Martin Fleck ◽  
Andreas Mackensen ◽  
Alessia Zoso ◽  
Dagmar Halbritter ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Fas Ligand ◽  
T Cell Responses ◽  
Antigen Presenting Cells ◽  
Cytotoxic T Cell ◽  
Cell Responses ◽  
Cytotoxic T Cell Responses ◽  
Antigen Presenting

Abstract Several cell-based immunotherapy strategies have been developed to specifically modulate T cell–mediated immune responses. These methods frequently rely on the utilization of tolerogenic cell–based antigen-presenting cells (APCs). However, APCs are highly sensitive to cytotoxic T-cell responses, thus limiting their therapeutic capacity. Here, we describe a novel bead-based approach to modulate T-cell responses in an antigen-specific fashion. We have generated killer artificial APCs (κaAPCs) by coupling an apoptosis-inducing α-Fas (CD95) IgM mAb together with HLA-A2 Ig molecules onto beads. These κaAPCs deplete targeted antigen-specific T cells in a Fas/Fas ligand (FasL)–dependent fashion. T-cell depletion in cocultures is rapidly initiated (30 minutes), dependent on the amount of κaAPCs and independent of activation-induced cell death (AICD). κaAPCs represent a novel technology that can control T cell–mediated immune responses, and therefore has potential for use in treatment of autoimmune diseases and allograft rejection.

scholarly journals Flagellin from Recombinant Attenuated Salmonella enterica Serovar Typhimurium Reveals a Fundamental Role in Chicken Innate Immunity

2012 ◽  
Vol 19 (3) ◽  
pp. 304-312 ◽  
Author(s):  
Zhiming Pan ◽  
Qiuxia Cong ◽  
Shizhong Geng ◽  
Qiang Fang ◽  
Xilong Kang ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Immune Responses ◽  
Salmonella Enterica ◽  
Rational Design ◽  
Bacterial Load ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTRecombinant attenuatedSalmonellavaccines have been extensively studied, with a focus on eliciting specific immune responses against foreign antigens. However, very little is known about the innate immune responses, particularly the role of flagellin, in the induction of innate immunity triggered by recombinant attenuatedSalmonellain chickens. In the present report, we describe twoSalmonella entericaserovar Typhimurium vaccine strains, wild-type (WT) or flagellin-deficient (flhD)Salmonella, both expressing the fusion protein (F) gene of Newcastle disease virus. We examined the bacterial load and spatiotemporal kinetics of expression of inflammatory cytokine, chemokine, and Toll-like receptor 5 (TLR5) genes in the cecum, spleen, liver, and heterophils following oral immunization of chickens with the twoSalmonellastrains. TheflhDmutant exhibited an enhanced ability to establish systemic infection compared to the WT. In contrast, the WT strain induced higher levels of interleukin-1β (IL-1β), CXCLi2, and TLR5 mRNAs in cecum, the spleen, and the heterophils than theflhDmutant at different times postinfection. Collectively, the present data reveal a fundamental role of flagellin in the innate immune responses induced by recombinant attenuatedSalmonellavaccines in chickens that should be considered for the rational design of novel vaccines for poultry.

Role of Toll-like receptors in costimulating cytotoxic T cell responses

2003 ◽  
Vol 33 (6) ◽  
pp. 1465-1470 ◽  
Author(s):  
Katrin Schwarz ◽  
Tazio Storni ◽  
Vania Manolova ◽  
Arnaud Didierlaurent ◽  
Jean-Claude Sirard ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Responses ◽  
Cytotoxic T Cell ◽  
Toll Like Receptors ◽  
Cell Responses ◽  
Cytotoxic T Cell Responses

scholarly journals Estrogen receptors in human bladder cells regulate innate cytokine responses to differentially modulate uropathogenic E. coli colonization

2020 ◽  
Author(s):  
Ayantika Sen ◽  
Anil Kaul ◽  
Rashmi Kaul
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Immune Responses ◽  
Bacterial Colonization ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Human Bladder ◽  
E Coli ◽  
Bladder Cells

AbstractThe bladder epithelial cells elicit robust innate immune responses against urinary tract infections (UTIs) for preventing the bacterial colonization. Physiological fluctuations in circulating estrogen levels in women increase the susceptibility to UTI pathogenesis, often resulting in adverse health outcomes. Dr adhesin bearing Escherichia coli (Dr E. coli) cause recurrent UTIs in menopausal women and acute pyelonephritis in pregnant women. Dr E. coli bind to epithelial cells via host innate immune receptor CD55, under hormonal influence. The role of estrogens or estrogen receptors (ERs) in regulating the innate immune responses in the bladder are poorly understood. In the current study, we investigated the role of ERα, ERβ and GPR30 in modulating the innate immune responses against Dr E. coli induced UTI using human bladder epithelial carcinoma 5637 cells (HBEC). Both ERα and ERβ agonist treatment in bladder cells induced a protection against Dr E. coli invasion via upregulation of TNFα and downregulation of CD55 and IL10, and these effects were reversed by action of ERα and ERβ antagoinsts. In contrast, the agonist-mediated activation of GPR30 led to an increased bacterial colonization due to suppression of innate immune factors in the bladder cells, and these effects were reversed by the antagonist-mediated suppression of GPR30. Further, siRNA-mediated ERα knockdown in the bladder cells reversed the protection against bacterial invasion observed in the ERα positive bladder cells, by modulating the gene expression of TNFα, CD55 and IL10, thus confirming the protective role of ERα. We demonstrate for the first time a protective role of nuclear ERs, ERα and ERβ but not of membrane ER, GPR30 against Dr E. coli invasion in HBEC 5637 cells. These findings have many clinical implications and suggest that ERs may serve as potential drug targets towards developing novel therapeutics for regulating local innate immunity and treating UTIs.HighlightsEstrogen receptor (ER) subtypes regulate the gene expression of innate immune molecules, CD55, TNFα and IL10 in human bladder epithelial cells impacting the bacterial colonization by Dr E. coli.Activation of nuclear ER subtypes, ERα and ERβ, upregulate the gene expression of proinflammatory cytokine, TNFα, but downregulate the gene expression of anti-inflammatory cytokine, IL10, and Dr E. coli colonization receptor, CD55, thus leading to efficient bacterial clearance in human bladder cells.In contrast, activation of the membrane ER subtype, GPR30, shows opposite effects to ERα and ERβ that were mediated on TNFα, IL10 and CD55 gene expression, thus leading to impaired bacterial clearance of Dr E. coli in human bladder cells.ER subtypes can serve as potential drug candidates for designing new therapies to boost or modulate the local immunity in the human bladder preventing the establishment of E. coli infections.

scholarly journals Cyclo(Phe-Pro) Produced by the Human Pathogen Vibrio vulnificus Inhibits Host Innate Immune Responses through the NF-κB Pathway

2015 ◽  
Vol 83 (3) ◽  
pp. 1150-1161 ◽  
Author(s):  
Kiwan Kim ◽  
Na-Jeong Kim ◽  
So Young Kim ◽  
In Hwang Kim ◽  
Kun-Soo Kim ◽  
...  
Keyword(s):  
Immune Responses ◽  
Vibrio Vulnificus ◽  
Cell Communication ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Human Pathogen ◽  
Causative Gene ◽  
Content Type ◽  
Iκb Kinase

Cyclo(Phe-Pro) (cFP) is a secondary metabolite produced by certain bacteria and fungi. Although recent studies highlight the role of cFP in cell-to-cell communication by bacteria, its role in the context of the host immune response is poorly understood. In this study, we investigated the role of cFP produced by the human pathogenVibrio vulnificusin the modulation of innate immune responses toward the pathogen. cFP suppressed the production of proinflammatory cytokines, nitric oxide, and reactive oxygen species in a lipopolysaccharide (LPS)-stimulated monocyte/macrophage cell line and in bone marrow-derived macrophages. Specifically, cFP inhibited inhibitory κB (IκB) kinase (IKK) phosphorylation, IκBα degradation, and nuclear factor κB (NF-κB) translocation to the cell nucleus, indicating that cFP affects the NF-κB pathway. We searched for genes that are responsible for cFP production inV. vulnificusand identified VVMO6_03017 as a causative gene. A deletion of VVMO6_03017 diminished cFP production and decreased virulence in subcutaneously inoculated mice. In summary, cFP produced byV. vulnificusactively suppresses the innate immune responses of the host, thereby facilitating its survival and propagation in the host environment.

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