scholarly journals Pathogen-encoded evasion of CXCL10 and T cell responses

2019 ◽  
Author(s):  
Alejandro L. Antonia ◽  
Monica I. Alvarez ◽  
Esme Trahair ◽  
Kyle D. Gibbs ◽  
Kelly J. Pittman ◽  
...  

AbstractClearance of intracellular pathogens, such asLeishmania (L.) major, depends on a well-regulated adaptive T cell response. Here we describe a pathogen-encoded mechanism to alter T cell recruitment by suppressing CXCL10, a chemokine that recruits CD4+ and CD8+ T cells by signaling through the CXCR3 receptor.L. majorsuppresses CXCL10 through the virulence factor and protease, glycoprotein-63(gp63).GP63 cleaves CXCL10 after amino acid A81, impairing T-cell chemotaxisin vitro.GP63 from either extracellular promastigotes or intracellular amastigotes is capable of cleaving CXCL10. Consistent with CXCL10 cleavage during infection, we observed GP63-mediated impairment of activated CD8+ T-cells in the draining lymph nodes of C57BL/6JWTmice. Correspondingly, in C57BL/6JWTmice,gp63deletion resulted in slower lesion development and a smaller maximum lesion size. However, infection in C57BL/6Jcxcr3−/−mice revealed the delay to lesion development required CXCR3 signaling. Finally,Salmonella entericaandChlamydia trachomatisinfection also suppress CXCL10, demonstrating convergent evolution of this immune evasion strategy in diverse intracellular pathogens. Understanding mechanisms of CXCL10 evasion may facilitate the development of novel therapeutic strategies to treat intracellular pathogens.Author SummaryLeishmaniasis is an infectious disease that affects over one million people annually. It is caused by intracellular parasites that have evolved to evade the host’s attempts to eliminate the parasite. The most common form of disease, cutaneous leishmaniasis, causes disfiguring skin lesions if the host immune system does not appropriately respond to the infection. A family of molecules called chemokines are critical for the recruitment of specific subsets of immune cells required to eliminate infection. Here, we demonstrate a novel mechanism that the parasiteLeishmania (L.) majoremploys to disrupt the immune response by interfering with chemokine signaling. By this strategy,L. majoruses a protease to cleave chemokines known to recruit T-cells required for fighting off infection. We show thatL. majorcleavage of these immune signals changes the recruitment of CD8+ T-cells and alters disease progression in mice. Finally, we observe that multiple common human intracellular pathogens, includingChlamydia trachomatisandSalmonella enterica, interfere with the same chemokines, suggesting a strong selective pressure to avoid this component of the immune response. Our study provides new insights into how intracellular pathogens interact with the host immune response to enhance pathogen survival and exacerbate disease outcomes.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. 11563-11563 ◽  
Author(s):  
Elias Obeid ◽  
Chun Zhou ◽  
Alexander Macfarlane ◽  
R. Katherine Alpaugh ◽  
Cecilia McAleer ◽  
...  

11563 Background: Correlative studies to determine the effect of combining chemotherapy (CT) simultaneously with checkpoint inhibition on the peripheral immune response are planned as part of a clinical trial in MTNB. The trial design is a Safety run-in, into a randomized phase II trial of combination pembrolizumab (P) with carboplatin (C) and gemcitabine (G) in patients with mTNBC. One key concern is that CT may suppress immune cell function, thereby diminishing the efficacy of PD-1 blockade. Methods: Patients with a diagnosis of mTNBC are recruited to this trial with a Safety Run-in (N = 6-12 subjects), followed by a randomized design of C + G with/without P (2:1 randomization, N = 75). Safety run-in consists of P 200 mg on day 1 of each 21-day cycle, and C (AUC2) + G (800mg/m2) on days 1 and 8. Patients are consented for a peripheral blood (PB) collection pre-cycle 1 and on day 1 of cycle 3, in order to phenotype immune system changes by flow-cytometry. Results: Six patients have been recruited as of this interim analysis. Data from PB analysis of 3 on-treatment patients is available. In 2 subjects, the activation marker CD69 increased on CD4+ and CD8+ T cells from baseline, indicating enhanced T cell function. Also the ratio of CD8+ T cells to regulatory T cells (CD25high CD127low) has increased. Both patients expressed PD-1 on T cells at baseline. The 2 subjects with evidence for enhanced immune response have a continued clinical benefit (12 cycles subject 1, 8 cycles subject 2). In contrast, subject 3 (who discontinued P and received corticosteroids for grade a 2 immune-related hepatitis during cycle 2) lacked expression of PD-1 on T cells and did not exhibit these immune changes, and her disease clinically progressed after 4 cycles of CT. Conclusions: Although comprising a very limited number of patients, early analysis from our correlative studies of combining CT with the PD-1 blockade revealed evidence for effective immune stimulation in two subjects. Furthermore, immune changes accompanied a lasting clinical response. Although early, we conclude that combining CT with checkpoint blockade can achieve its goal of unleashing an anti-tumor immune response in mTNBC patients. Clinical trial information: NCT02755272.


1998 ◽  
Vol 187 (9) ◽  
pp. 1395-1402 ◽  
Author(s):  
M.F.C. Callan ◽  
L. Tan ◽  
N. Annels ◽  
G.S. Ogg ◽  
J.D.K. Wilson ◽  
...  

Primary infection with virus can stimulate a vigorous cytotoxic T cell response. The magnitude of the antigen-specific component versus the bystander component of a primary T cell response remains controversial. In this study, we have used tetrameric major histocompatibility complex–peptide complexes to directly visualize antigen-specific cluster of differentration (CD)8+ T cells during the primary immune response to Epstein-Barr virus (EBV) infection in humans. We show that massive expansion of activated, antigen-specific T cells occurs during the primary response to this virus. In one individual, T cells specific for a single EBV epitope comprised 44% of the total CD8+ T cells within peripheral blood. The majority of the antigen-specific cells had an activated/memory phenotype, with expression of human histocompatibility leukocyte antigen (HLA) DR, CD38, and CD45RO, downregulation of CD62 leukocyte (CD62L), and low levels of expression of CD45RA. After recovery from AIM, the frequency of antigen-specific T cells fell in most donors studied, although populations of antigen-specific cells continued to be easily detectable for at least 3 yr.


2008 ◽  
Vol 205 (3) ◽  
pp. 669-684 ◽  
Author(s):  
Andrew G. Evans ◽  
Janice M. Moser ◽  
Laurie T. Krug ◽  
Veranika Pozharskaya ◽  
Ana L. Mora ◽  
...  

Little is known about herpesvirus modulation of T cell activation in latently infected individuals or the implications of such for chronic immune disorders. Murine gammaherpesvirus 68 (MHV68) elicits persistent activation of CD8+ T cells bearing a Vβ4+ T cell receptor (TCR) by a completely unknown mechanism. We show that a novel MHV68 protein encoded by the M1 gene is responsible for Vβ4+ CD8+ T cell stimulation in a manner reminiscent of a viral superantigen. During infection, M1 expression induces a Vβ4+ effector T cell response that resists functional exhaustion and appears to suppress virus reactivation from peritoneal cells by means of long-term interferon-γ (IFNγ) production. Mice lacking an IFNγ receptor (IFNγR−/−) fail to control MHV68 replication, and Vβ4+ and CD8+ T cell activation by M1 instead contributes to severe inflammation and multiorgan fibrotic disease. Thus, M1 manipulates the host CD8+ T cell response in a manner that facilitates latent infection in an immunocompetent setting, but promotes disease during a dysregulated immune response. Identification of a viral pathogenecity determinant with superantigen-like activity for CD8+ T cells broadens the known repertoire of viral immunomodulatory molecules, and its function illustrates the delicate balance achieved between persistent viruses and the host immune response.


Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2655
Author(s):  
Inesa Navasardyan ◽  
Benjamin Bonavida

The T cell-mediated immune response is primarily involved in the fight against infectious diseases and cancer and its underlying mechanisms are complex. The anti-tumor T cell response is regulated by various T cell subsets and other cells and tissues in the tumor microenvironment (TME). Various mechanisms are involved in the regulation of these various effector cells. One mechanism is the iNOS/.NO that has been reported to be intimately involved in the regulation and differentiation of the various cells that regulate the anti-tumor CD8 T cells. Both endogenous and exogenous .NO are implicated in this regulation. Importantly, the exposure of T cells to .NO had different effects on the immune response, depending on the .NO concentration and time of exposure. For instance, iNOS in T cells regulates activation-induced cell death and inhibits Treg induction. Effector CD8 T cells exposed to .NO result in the upregulation of death receptors and enhance their anti-tumor cytotoxic activity. .NO-Tregs suppress CD4 Th17 cells and their differentiation. Myeloid-derived suppressor cells (MDSCs) expressing iNOS inhibit T cell functions via .NO and inhibit anti-tumor CD8 T cells. Therefore, both .NO donors and .NO inhibitors are potential therapeutics tailored to specific target cells that regulate the T cell effector anti-tumor response.


2015 ◽  
Vol 112 (10) ◽  
pp. 3050-3055 ◽  
Author(s):  
Rama S. Akondy ◽  
Philip L. F. Johnson ◽  
Helder I. Nakaya ◽  
Srilatha Edupuganti ◽  
Mark J. Mulligan ◽  
...  

CD8 T cells are a potent tool for eliminating intracellular pathogens and tumor cells. Thus, eliciting robust CD8 T-cell immunity is the basis for many vaccines under development. However, the relationship between antigen load and the magnitude of the CD8 T-cell response is not well-described in a human immune response. Here we address this issue by quantifying viral load and the CD8 T-cell response in a cohort of 80 individuals immunized with the live attenuated yellow fever vaccine (YFV-17D) by sampling peripheral blood at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90. When the virus load was below a threshold (peak virus load < 225 genomes per mL, or integrated virus load < 400 genome days per mL), the magnitude of the CD8 T-cell response correlated strongly with the virus load (R2∼ 0.63). As the virus load increased above this threshold, the magnitude of the CD8 T-cell responses saturated. Recent advances in CD8 T-cell–based vaccines have focused on replication-incompetent or single-cycle vectors. However, these approaches deliver relatively limited amounts of antigen after immunization. Our results highlight the requirement that T-cell–based vaccines should deliver sufficient antigen during the initial period of the immune response to elicit a large number of CD8 T cells that may be needed for protection.


2016 ◽  
Vol 23 (9) ◽  
pp. 785-794 ◽  
Author(s):  
Kimberly A. Hofmeyer ◽  
Malcolm S. Duthie ◽  
John D. Laurance ◽  
Michelle A. Favila ◽  
Neal Van Hoeven ◽  
...  

ABSTRACTImmunization strategies that generate either CD4 or CD8 T cell responses are relatively well described, but less is known with regard to optimizing regimens to induce both CD4 and CD8 memory T cells. Considering the importance of both CD4 and CD8 T cells in the control of intracellular pathogens such asLeishmania donovani, we wanted to identify vaccines that could raise both CD4 and CD8 T cell responses and determine how to configure immunization strategies to generate the best combined protective T cell response. We examined responses generated against theLeishmaniavaccine antigen F3 following its administration in either recombinant form with the Toll-like receptor 4 (TLR4) agonist-containing adjuvant formulation GLA-SE (F3+GLA-SE) or as a gene product delivered in an adenoviral vector (Ad5-F3). Homologous immunization strategies using only F3+GLA-SE or Ad5-F3 preferentially generated either CD4 or CD8 T cells, respectively. In contrast, heterologous strategies generated both antigen-specific CD4 and CD8 T cells. Administration of F3+GLA-SE before Ad5-F3 generated the greatest combined CD4 and CD8 responses. Cytotoxic CD8 T cell responses were highest when Th1 cells were generated prior to their induction by Ad5-F3. Finally, a single immunization with a combination of F3+GLA-SE mixed with Ad5-F3 was found to be sufficient to provide protection against experimentalL. donovaniinfection. Taken together, our data delineate immunization regimens that induce antigen-specific CD4 and CD8 T cell memory responses, and identify a single immunization strategy that could be used to rapidly provide protection against intracellular pathogens in regions where access to health care is limited or sporadic.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1281-1281
Author(s):  
Fátima de la Cruz Vicente ◽  
Omar BenMarzouk-Hidalgo ◽  
Irene Gracia-Ahufinger ◽  
Raul García-Lozano ◽  
Manuela Aguilar-Guisado ◽  
...  

Abstract Abstract 1281 Background: Cytomegalovirus (CMV) end-organ disease is a serious complication after allogeneic stem cell transplantation (Allo-SCT). The quality of the post-transplant immune reconstitution plays a crucial role in the development of both, post-transplant infections and relapse of the underlying disease, two of the main factors conditioning post-transplant mortality and hence final survival. The relationship between viral replication and CMV specific immune reconstitution has not been completely unveiled. This knowledge would allow identifying patients at risk for developing CMV disease and eventually improving their clinical management. Objectives: to analyze the relationship between CMV replication and specific CMV immune reconstitution and the potential influence of this relationship in main clinical outcomes. Patients and Methods: A prospective study of consecutive recipients of Allo-SCT was performed from June 2008 through December 2009 at a single institution. Blood samples were collected from one week before transplant, weekly during the first three months after transplant, every other week from month three to six and monthly from month seven to complete one year of follow up. CMV viral load was determined by real time PCR and CMV-specific T cell response was determined by flow cytometry with surface markers and intracellular cytokine staining. The percentage of activated CD4+, CD8+ and CD3+ T cells expressing CD69 were considered positive when IFN-’Y cytokine secretion was over 0.25%. Chimerism of the isolated CD8+ T cell subpopulation was determined by PCR. CD69 expression and cytokine secretion were compared in both CD4+ and CD8+ T cells between the different time points and both subsets of patients by the Wilcoxon test. CMV viral load reduction without treatment administration was compared by Wilcoxon test. Differences were considered statistically significant for p-values < 0.05. All statistical analyses were performed using SPSS 16.0 software (Chicago, IL). Results: Twenty-six patients were enrolled in the study with a median age of 33 years (range:15-61). We identified two groups of patients. A first group of 18 (69.2%) patients developed CMV infection and acquired CMV-specific T cell response by median week 8 (range:1-22; Figure 1A). The decline in the incidence of CMV replication episodes correlated with the acquisition of CMV-specific T cell response (Linear regresion r2=0.781, Pearson correlation p=0.01). A second group of 8 patients (30.8%) never developed CMV infection after the transplant, with a median value of 2 weeks (range:1-7; Figure 1B). The time of the acquisition of CMV-specific T cell response for the group with viremia and for the non-viremic group (week 2 vs. week 8) was statistically different (p= 0.01). Fifteen per cent of the patients (n=4) developed end-organ disease. Three out of five patients with end-organ disease developed replication CMV episodes over 10,000 copies/ml, while only 1 out of 13 patients with no end-organ disease developed viral loads under 10,000 copies/ml (p=0.04). The percentage of positive CD8+ T cells expressing IFN-γ in the patients that developed disease tended to be lower than in the patients that did not develop disease (median percentage of IFN-g positive CD8 T cells 0.3 vs. 0.5, respectively). The chimerism of the CD8+ T cells subpopulation after acquiring the specific immune response was of complete donor origin for all the patients. Conclusions: Developing donor-derived T-cell mediated CMV-specific immune response within the following two weeks after the transplant is inversely associated with the development CMV infection. The level of CMV viral load may predict end-organ disease. The use of a tool to determine T-cell mediated CMV-specific immune response in the clinical practice may help to improve the management of these patients, avoiding unnecessary treatments, and predicting clinical outcomes. Disclosures: No relevant conflicts of interest to declare.


Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 68
Author(s):  
Yifan Wang ◽  
Fugang Duan ◽  
Zhu Zhu ◽  
Meng Yu ◽  
Xiaodong Jia ◽  
...  

Coronavirus disease 2019 (COVID-19) is a global infectious disease caused by the SARS-CoV-2 coronavirus. T cells play an essential role in the body’s fighting against the virus invasion, and the T cell receptor (TCR) is crucial in T cell-mediated virus recognition and clearance. However, little has been known about the features of T cell response in convalescent COVID-19 patients. In this study, using 5′RACE technology and PacBio sequencing, we analyzed the TCR repertoire of COVID-19 patients after recovery for 2 weeks and 6 months compared with the healthy donors. The TCR clustering and CDR3 annotation were exploited to discover groups of patient-specific TCR clonotypes with potential SARS-CoV-2 antigen specificities. We first identified CD4+ and CD8+ T cell clones with certain clonal expansion after infection, and then observed the preferential recombination usage of V(D) J gene segments in CD4+ and CD8+ T cells of COVID-19 patients with different convalescent stages. More important, the TRBV6-5-TRBD2-TRBJ2-7 combination with high frequency was shared between CD4+ T and CD8+ T cells of different COVID-19 patients. Finally, we found the dominant characteristic motifs of the CDR3 sequence between recovered COVID-19 and healthy control. Our study provides novel insights on TCR in COVID-19 with different convalescent phases, contributing to our understanding of the immune response induced by SARS-CoV-2.


Blood ◽  
2009 ◽  
Vol 114 (20) ◽  
pp. 4477-4485 ◽  
Author(s):  
Bindu Varghese ◽  
Adam Widman ◽  
James Do ◽  
Behnaz Taidi ◽  
Debra K. Czerwinski ◽  
...  

AbstractWe investigated the ability of CpG-oligodeoxynucleotide to generate an anti-tumor CD8+ T-cell immune response and to synergize with passive antibody therapy. For these studies, we generated an antibody against the idiotype on the A20 B-cell lymphoma line. This antibody caused the regression of established tumors, but ultimately the tumors relapsed. The escaping surface IgG-negative tumor cells were resistant to both antibody-dependent cellular cytotoxicity and signaling-induced cell death. Addition of intratumoral CpG to antibody therapy cured large established tumors and prevented the occurrence of tumor escapees. The failure of the combination therapy in mice deficient for CD8+ T cells demonstrates the critical role of CD8+ T cells in tumor eradication. When mice were inoculated with 2 tumors and treated systemically with antibody followed by intratumoral CpG in just one tumor, both tumors regressed, indicating that a systemic immune response was generated. Although antibody therapy can eliminate tumor cells bearing the target antigen, it frequently selects for antigen loss variants. However, when a poly-specific T-cell response was generated against the tumor by intratumoral CpG, even large established tumors were cured. Such an immune response can prevent the emergence of antibody selected tumor escapees and provide long-lasting tumor protection.


2020 ◽  
Vol 17 ◽  
Author(s):  
Mehreen Ismail ◽  
Zureesha Sajid ◽  
Amjad Ali ◽  
Xiaogang Wu ◽  
Syed Aun Muhammad ◽  
...  

Background: Human Papillomavirus (HPV) is responsible for substantial morbidity and mortality worldwide. We predicted immunogenic promiscuous monovalent and polyvalent T-cell epitopes from the polyprotein of the Human Papillomavirus (HPV) using a range of bioinformatics tools and servers. Methods: We used immunoinformatics and reverse vaccinology-based approaches to design prophylactic peptides by antigenicity analysis, Tcell epitopes prediction, proteasomal and conservancy evaluation, host-pathogen protein interactions, and in silico binding affinity analysis. Results: We found two early proteins (E2 and E6) and two late proteins (L1 and L2) of HPV as potential vaccine candidates. Of these proteins (E2, E6, L1 & L2), 2-epitopes of each candidate protein for multiple alleles of MHC class I and II bearing significant binding affinity (>-6.0 kcal/mole). These potential epitopes for CD4+ and CD8+ T-cells were also linked to design polyvalent construct using GPGPG linkers. Cholera toxin B and mycobacterial heparin-binding hemagglutinin adjuvant with a molecular weight of 12.5 and 18.5 kDa were used for epitopes of CD4+ and CD8+ T-cells respectively. The molecular docking indicated the optimum binding affinity of HPV peptides with MHC molecules. This interaction showed that our predicted vaccine candidates are suitable to trigger the host immune system to prevent HPV infections. Conclusion: The predicted conserved T-cell epitopes would contribute to the imminent design of HPV vaccine candidates, which will be able to induce a broad range of immune-responses in a heterogeneous HLA population.


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