scholarly journals Targeting of Cdc42 GTPase in regulatory T cells unleashes anti-tumor T cell immunity

2021 ◽  
Author(s):  
Khalid W Kalim ◽  
Jun-Qi Yang ◽  
Mark Wunderlich ◽  
Vishnu Modur ◽  
Phuong Nguyen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Treg Cell ◽  
Cell Function ◽  
Treg Cells ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Cell Plasticity ◽  
Effector T Cell ◽  
Cell Immunity

Regulatory T (Treg) cells play an important role in maintaining immune tolerance through inhibiting effector T cell function. In the tumor microenvironment, Treg cells are utilized by tumor cells to counteract effector T cell-mediated tumor killing. Targeting Treg cells may thus unleash the anti-tumor activity of effector T cells. While systemic depletion of Treg cells can cause excessive effector T cell responses and subsequent autoimmune diseases, controlled targeting of Treg cells may benefit cancer patients. Here we show that Treg cell-specific heterozygous deletion or pharmacological targeting of Cdc42 GTPase does not affect Treg cell numbers but induces Treg cell plasticity, leading to anti-tumor T cell immunity without detectable autoimmune reactions. Cdc42 targeting potentiates an immune checkpoint blocker anti-PD-1 antibody-mediated T cell response against mouse and human tumors. Mechanistically, Cdc42 targeting induces Treg cell plasticity and unleashes anti-tumor T cell immunity through carbonic anhydrase I-mediated pH changes. Thus, rational targeting of Cdc42 in Treg cells holds therapeutic promises in cancer immunotherapy.

scholarly journals Graded RhoA GTPase Expression in Treg Cells Distinguishes Tumor Immunity From Autoimmunity

2021 ◽  
Vol 12 ◽  
Author(s):  
Khalid W. Kalim ◽  
Jun-Qi Yang ◽  
Vishnu Modur ◽  
Phuong Nguyen ◽  
Yuan Li ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Treg Cell ◽  
Tumor Immunity ◽  
Th17 Cell ◽  
Treg Cells ◽  
Effector T Cells ◽  
Conditional Knockout ◽  
Cell Plasticity ◽  
Cell Homeostasis

RhoA of the Rho GTPase family is prenylated at its C-terminus. Prenylation of RhoA has been shown to control T helper 17 (Th17) cell-mediated colitis. By characterizing T cell-specific RhoA conditional knockout mice, we have recently shown that RhoA is required for Th2 and Th17 cell differentiation and Th2/Th17 cell-mediated allergic airway inflammation. It remains unclear whether RhoA plays a cell-intrinsic role in regulatory T (Treg) cells that suppress effector T cells such as Th2/Th17 cells to maintain immune tolerance and to promote tumor immune evasion. Here we have generated Treg cell-specific RhoA-deficient mice. We found that homozygous RhoA deletion in Treg cells led to early, fatal systemic inflammatory disorders. The autoimmune responses came from an increase in activated CD4+ and CD8+ T cells and in effector T cells including Th17, Th1 and Th2 cells. The immune activation was due to impaired Treg cell homeostasis and increased Treg cell plasticity. Interestingly, heterozygous RhoA deletion in Treg cells did not affect Treg cell homeostasis nor cause systemic autoimmunity but induced Treg cell plasticity and an increase in effector T cells. Importantly, heterozygous RhoA deletion significantly inhibited tumor growth, which was associated with tumor-infiltrating Treg cell plasticity and increased tumor-infiltrating effector T cells. Collectively, our findings suggest that graded RhoA expression in Treg cells distinguishes tumor immunity from autoimmunity and that rational targeting of RhoA in Treg cells may trigger anti-tumor T cell immunity without causing autoimmune responses.

T Regulatory Cell Activation Exists in Pathogenesis of Polycythaemia Vera.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4642-4642
Author(s):  
Xin Wang ◽  
Wenbo Zhao ◽  
Yanxia Liu ◽  
Ying Li
Keyword(s):  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Protein Level ◽  
Treg Cells ◽  
T Cell Immunity ◽  
Polycythaemia Vera ◽  
Cell Immunity ◽  
And Function ◽  
Hematopoietic Activity

Abstract Polycythaemia vera (PV) is a clonal disorder arising from a pluripotent hematopoietic progenitor cell. The etiology of PV remains unknown and there is no consensus as to the optimal therapy for this disorder. T regulatory (Treg) cells play a vital role in the maintenance of self-tolerance, control of auto-immunity and regulation of T-cell homeostasis, and they modulate overall immune responses against a variety of pathogens. Recent studies revealed that Treg cells play a crucial role in the process of hematopoietic activity. However, the effect of Treg cells in PV has not been reported. The Treg cells might participate in the dysfunction of T-cell immunity in PV. The profile and function of Treg cells in PV patients were explored in this study. Peripheral blood was withdrawn from 21 PV patients (Female 8 ; Male 13), as well as 25 age-matched healthy donors (F 9 ; M 16) as controls. All samples were taken after informed consent and collected from PV patients prior to treatment. Diagnoses of PV were made according to clinical and laboratory criteria. The peripheral blood mononuclear cells (PBMCs) were subjected to flow cytometry analyses after labeling with anti-CD4, anti-CD25, and anti-Foxp3 antibodies. Real-time PCR and Western blotting were also performed to identify quantitative FOXP3 mRNA expression and protein level in the PBMCs from PV in comparison to controls. The relationships between the percentage of Treg cells, the expressions for quantitative mRNA and protein, with the clinical data were assessed. The percentage of CD4+ T-cells was significant decreased in the group of PV than in normal control (28.7±7.07% vs 38.6±8.38%, p<0.05). But the percentage of CD4+CD25+FOXP3+ T-cells (Treg cells) in PV patients was significantly increased when compared to the control (10.93±4.02% vs 5.86±1.99%, p<0.05). Moreover, the quantitative mRNA expression of FOXP3 (64.23±18.52 vs 16.06±4.78, p<0.05) and protein expression of FOXP3 (0.74±0.16 vs 0.62±0.10, p<0.05)) were significantly enhanced in PV patients (shown in Figure 1). In conclusion, we showed that patients with PV have enhanced percentage of Treg cells in their peripheral blood. This was substantiated further with the finding that overexpressions of FOXP3 in PV both in mRNA and protein level. These results highlight important Treg-cell abnormalities in patients with PV because natural Treg cells are significantly increased in number and function. The underlying mechanism is still undefined, but the increased frequency and function of Treg cells might account for the abnormal T cell immunity in PV patients. It was suggested that there may be differently suppressive machanisms for Treg in these patients. The elevated Treg cells in PV might be activated and then affect the hematopoietic activity. We believe that Treg cells might involved in the dysfunction of T/NK cells in their disability to downregulate the hematopoietic proliferation in PV. And the expansion of Treg cells may be a feature of PV and associated with the pathogenesis of PV. Further investigation in this abnormality might provide novel therapy clue for this disease. Figure Figure

scholarly journals Lack of CD4+ T Cells Does Not Affect Induction of CD8+ T-Cell Immunity against Encephalitozoon cuniculi Infection

2000 ◽  
Vol 68 (11) ◽  
pp. 6223-6232 ◽  
Author(s):  
Magali Moretto ◽  
Lori Casciotti ◽  
Brigit Durell ◽  
Imtiaz A. Khan
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Cell Mediated Immunity ◽  
Wild Type ◽  
Encephalitozoon Cuniculi ◽  
Cell Immunity ◽  
Mouse Tissues

ABSTRACT Cell-mediated immunity has been reported to play an important role in defense against Encephalitozoon cuniculi infection. Previous studies from our laboratory have underlined the importance of cytotoxic CD8+ T lymphocytes (CTL) in survival of mice infected with E. cuniculi. In the present study, immune response against E. cuniculi infection in CD4+T-cell-deficient mice was evaluated. Similar to resistant wild-type animals, CD4−/− mice were able to resolve E. cuniculi infection even at a very high challenge dose (5 × 107 spores/mouse). Tissues from infected CD4−/− mice did not exhibit higher parasite loads in comparison to the parental wild-type mice. Conversely, at day 21 postinfection, susceptible CD8−/− mice had 1014 times more parasites in the liver compared to control wild-type mice. Induction of the CD8+ T-cell response in CD4−/− mice against E. cuniculi infection was studied. Interestingly, a normal antigen-specific CD8+T-cell response to E. cuniculi infection was observed in CD4−/− mice (precursor proliferation frequency, 1/2.5 × 104 versus 1/104 in wild-type controls). Lack of CD4+ T cells did not alter the magnitude of the antigen-specific CTL response (precursor CTL frequency; 1/1.4 × 104 in CD4−/− mice versus 1/3 × 104 in control mice). Adoptive transfer of immune CD8+ T cells from both CD4−/− and wild-type animals prevented the mortality in CD8−/− mice.E. cuniculi infection thus offers an example of an intracellular parasitic infection where CD8+ T-cell immunity can be induced in the absence of CD4+ T cells.

scholarly journals Antigen-Specific Inhibition of Effector T Cell Function in Humans after Injection of Immature Dendritic Cells

2001 ◽  
Vol 193 (2) ◽  
pp. 233-238 ◽  
Author(s):  
Madhav V. Dhodapkar ◽  
Ralph M. Steinman ◽  
Joseph Krasovsky ◽  
Christian Munz ◽  
Nina Bhardwaj
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Function ◽  
Cd8 T Cell ◽  
Specific Inhibition ◽  
Killer Activity ◽  
Effector T Cell ◽  
T Cell Function ◽  
Cell Immunity

Immunostimulatory properties of dendritic cells (DCs) are linked to their maturation state. Injection of mature DCs rapidly enhances antigen-specific CD4+ and CD8+ T cell immunity in humans. Here we describe the immune response to a single injection of immature DCs pulsed with influenza matrix peptide (MP) and keyhole limpet hemocyanin (KLH) in two healthy subjects. In contrast to prior findings using mature DCs, injection of immature DCs in both subjects led to the specific inhibition of MP-specific CD8+ T cell effector function in freshly isolated T cells and the appearance of MP-specific interleukin 10–producing cells. When pre- and postimmunization T cells were boosted in culture, there were greater numbers of MP-specific major histocompatibility complex tetramer-binding cells after immunization, but these had reduced interferon γ production and lacked killer activity. These data demonstrate the feasibility of antigen-specific inhibition of effector T cell function in vivo in humans and urge caution with the use of immature DCs when trying to enhance tumor or microbial immunity.

scholarly journals Children and adults with mild COVID-19 symptoms develop memory T cell immunity to SARS-CoV-2

2021 ◽  
Author(s):  
Patricia Kaaijk ◽  
Veronica Olivo Pimentel ◽  
Maarten E. Emmelot ◽  
Martien Poelen ◽  
Alper Cevirgel ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Immune Memory ◽  
Effector Memory ◽  
Longitudinal Assessment ◽  
Memory T Cell ◽  
Cell Immunity

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to considerable morbidity/mortality worldwide, but most infections, especially among children, have a mild course. However, it remains largely unknown whether infected children develop cellular immune memory. Methods: To determine whether a memory T cell response is being developed as an indicator for long-term immune protection, we performed a longitudinal assessment of the SARS-CoV-2-specific T cell response by IFN-γ ELISPOT and activation marker expression analyses of peripheral blood samples from children and adults with mild-to-moderate COVID-19. Results: Upon stimulation of PBMCs with heat-inactivated SARS-CoV-2 or overlapping peptides of spike (S-SARS-CoV-2) and nucleocapsid proteins, we found S-SARS-CoV-2-specific IFN-ɣ T cell responses in most infected children (83%) and all adults (100%) that were absent in unexposed controls. Frequencies of SARS-CoV-2-specific T cells were higher in infected adults, especially in those with moderate symptoms, compared to infected children. The S-SARS-CoV-2 IFN-ɣ T cell response correlated with S1-SARS-CoV-2-specific serum IgM, IgG, and IgA antibody concentrations. Predominantly, effector memory CD4+ T cells of a Th1 phenotype were activated upon exposure to SARS-CoV-2 antigens, which persisted for 4-8 weeks after symptom onset. We detected very low frequencies of SARS-CoV-2-reactive CD8+ T cells in these individuals. Conclusions: Our data indicate that an antigen-specific memory CD4+ T cell response is induced in children and adults with mild SARS-CoV-2 infection. T cell immunity induced after mild COVID-19 could contribute to protection against re-infection.

scholarly journals Assessment of T-cell immunity to SARS-CoV-2 in COVID-19 convalescents and vaccinated subjects, using TigraTest® SARS-CoV-2 ELISPOT kit

2021 ◽  
Vol 21 (3) ◽  
pp. 178-192
Author(s):  
D. A. Poteryaev ◽  
S. G. Abbasova ◽  
P. E. Ignatyeva ◽  
O. M. Strizhakova ◽  
S. V. Kolesnik ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Cell Response ◽  
Human Peripheral Blood ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Cell Immunity

With the onset of the COVID-19 pandemic, a number of molecular-based tests have been developed to diagnose SARS-CoV-2 infection. However, numerous available serological tests lack sufficient sensitivity or specificity. They do not detect specific antibodies in a significant proportion of patients with PCR-confirmed COVID-19. There is evidence that some convalescents have a relatively short-lived humoral immunity. In contrast, a number of publications have shown that T-cell response to human coronaviruses, including SARS-CoV-1, MERS, and SARS-CoV-2, can be strong and long-term. Assessment of T-cell immunity to SARS-CoV-2 is important not only for stratification of risks and identification of potentially protected populations with immunity acquired as a result of previous infection, but also for determining immunogenicity and potential efficacy of vaccines under development. The existing methods of quantitative or semi-quantitative assessment of specific T-cell response are mainly used in scientific research and are not standardised. The aim of the study was to develop and verify experimentally a test kit to be used in a standardised procedure for in vitro determination of T-cells specific to SARS-CoV-2 antigens, in human peripheral blood. Materials and methods: the TigraTest® SARS-CoV-2 kit developed by GENERIUM, which determines the number of T-cells secreting interferon gamma in vitro, was tested in the study. Samples of venous blood of volunteers from three different groups were analysed in the study: presumably healthy volunteers; COVID-19 convalescents; individuals vaccinated against SARS-CoV-2. Results: the authors developed the TigraTest® SARS-CoV-2 kit for in vitro determination of T-cells specific to SARS-CoV-2 antigens in human peripheral blood, demonstrated its specificity and performed preliminary assessment of its sensitivity. The study analysed the range and magnitude of the T-cell response in convalescent and vaccinated individuals. A pronounced T-cell response was also shown in some individuals with no symptoms or with unconfirmed diagnosis. It was discovered that the mean T-cell response to peptides of the spike protein (S-protein) was higher in the vaccinated individuals than in the convalescent patients. A correlation was determined between the severity of the disease and the level of T-cell response. Specific contributions of various groups of antigens to the T-cell response after COVID-19 infection were also determined. Conclusions: the TigraTest® SARS-CoV-2 kit is a specific and sensitive tool for the assessment of T-cell immunity to the SARS-CoV-2 virus, which can also be used for vaccinated individuals. The kit may be used in clinical practice for comprehensive assessment of immunity to SARS-CoV-2.

scholarly journals Prior Dengue Virus Exposure Shapes T Cell Immunity to Zika Virus in Humans

2017 ◽  
Vol 91 (24) ◽  
Author(s):  
Alba Grifoni ◽  
John Pham ◽  
John Sidney ◽  
Patrick H. O'Rourke ◽  
Sinu Paul ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Zika Virus ◽  
T Cell Responses ◽  
Cross Reactivity ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Cell Responses ◽  
Cell Immunity

ABSTRACT While progress has been made in characterizing humoral immunity to Zika virus (ZIKV) in humans, little is known regarding the corresponding T cell responses to ZIKV. Here, we investigate the kinetics and viral epitopes targeted by T cells responding to ZIKV and address the critical question of whether preexisting dengue virus (DENV) T cell immunity modulates these responses. We find that memory T cell responses elicited by prior infection with DENV or vaccination with tetravalent dengue attenuated vaccines (TDLAV) recognize ZIKV-derived peptides. This cross-reactivity is explained by the sequence similarity of the two viruses, as the ZIKV peptides recognized by DENV-elicited memory T cells are identical or highly conserved in DENV and ZIKV. DENV exposure prior to ZIKV infection also influences the timing and magnitude of the T cell response. ZIKV-reactive T cells in the acute phase of infection are detected earlier and in greater magnitude in DENV-immune patients. Conversely, the frequency of ZIKV-reactive T cells continues to rise in the convalescent phase in DENV-naive donors but declines in DENV-preexposed donors, compatible with more efficient control of ZIKV replication and/or clearance of ZIKV antigen. The quality of responses is also influenced by previous DENV exposure, and ZIKV-specific CD8 T cells from DENV-preexposed donors selectively upregulated granzyme B and PD1, unlike DENV-naive donors. Finally, we discovered that ZIKV structural proteins (E, prM, and C) are major targets of both the CD4 and CD8 T cell responses, whereas DENV T cell epitopes are found primarily in nonstructural proteins. IMPORTANCE The issue of potential ZIKV and DENV cross-reactivity and how preexisting DENV T cell immunity modulates Zika T cell responses is of great relevance, as the two viruses often cocirculate and Zika virus has been spreading in geographical regions where DENV is endemic or hyperendemic. Our data show that memory T cell responses elicited by prior infection with DENV recognize ZIKV-derived peptides and that DENV exposure prior to ZIKV infection influences the timing, magnitude, and quality of the T cell response. Additionally, we show that ZIKV-specific responses target different proteins than DENV-specific responses, pointing toward important implications for vaccine design against this global threat.

Role of regulatory T-cells in autoimmunity

2009 ◽  
Vol 116 (8) ◽  
pp. 639-649 ◽  
Author(s):  
Richard J. Mellanby ◽  
David C. Thomas ◽  
Jonathan Lamb
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Treg Cell ◽  
Cell Function ◽  
Cell Subset ◽  
Treg Cells ◽  
Self Tolerance

There has been considerable historical interest in the concept of a specialist T-cell subset which suppresses over-zealous or inappropriate T-cell responses. However, it was not until the discovery that CD4+CD25+ T-cells had suppressive capabilities both in vitro and in vivo that this concept regained credibility and developed into one of the most active research areas in immunology today. The notion that in healthy individuals there is a subset of Treg-cells (regulatory T-cells) involved in ‘policing’ the immune system has led to the intensive exploration of the role of this subset in disease resulting in a number of studies concluding that a quantitative or qualitative decline in Treg-cells is an important part of the breakdown in self-tolerance leading to the development of autoimmune diseases. Although Treg-cells have subsequently been widely postulated to represent a potential immunotherapy option for patients with autoimmune disease, several studies of autoimmune disorders have demonstrated high numbers of Treg-cells in inflamed tissue. The present review highlights the need to consider a range of other factors which may be impairing Treg-cell function when considering the mechanisms involved in the breakdown of self-tolerance rather than focussing on intrinsic Treg-cell factors.

LOX-1 as a natural IFN-α–mediated signal for apoptotic cell uptake and antigen presentation in dendritic cells

Blood ◽  
2010 ◽  
Vol 115 (8) ◽  
pp. 1554-1563 ◽  
Author(s):  
Stefania Parlato ◽  
Giulia Romagnoli ◽  
Francesca Spadaro ◽  
Irene Canini ◽  
Paolo Sirabella ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Activation ◽  
Apoptotic Cell ◽  
Scavenger Receptor ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
T Cell Immunity ◽  
Cell Immunity

Abstract The identification of molecules responsible for apoptotic cell (AC) uptake by dendritic cells (DCs) and induction of T-cell immunity against AC-associated antigens is a challenge in immunology. DCs differentiated in the presence of interferon-α (IFN-α–conditioned DCs) exhibit a marked phagocytic activity and a special attitude in inducing CD8+ T-cell response. In this study, we found marked overexpression of the scavenger receptor oxidized low-density lipoprotein receptor 1 (LOX-1) in IFN-α–conditioned DCs, which was associated with increased levels of genes belonging to immune response families and high competence in inducing T-cell immunity against antigens derived from allogeneic apoptotic lymphocytes. In particular, the capture of ACs by IFN-α DCs led to a substantial subcellular rearrangement of major histocompatibility complex class I and class II molecules, along with enhanced cross-priming of autologous CD8+ T cells and CD4+ T-cell activation. Remarkably, AC uptake, CD8+ T-cell cross-priming, and, to a lesser extent, priming of CD4+ T lymphocytes were inhibited by a neutralizing antibody to the scavenger receptor LOX-1 protein. These results unravel a novel LOX-1–dependent pathway by which IFN-α can, under both physiologic and pathologic conditions, render DCs fully competent for presenting AC-associated antigens for cross-priming CD8+ effector T cells, concomitantly with CD4+ T helper cell activation.

scholarly journals Lack of Interleukin-12 in p40-Deficient Mice Leads to Poor CD8+ T-Cell Immunity against Encephalitozoon cuniculi Infection

2010 ◽  
Vol 78 (6) ◽  
pp. 2505-2511 ◽  
Author(s):  
Magali M. Moretto ◽  
Elizabeth M. Lawlor ◽  
Imtiaz A. Khan
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
T Cell Response ◽  
Scid Mice ◽  
T Cell Immunity ◽  
Interleukin 12 ◽  
Cell Immune Response ◽  
Encephalitozoon Cuniculi ◽  
Cell Immunity

ABSTRACT A CD8+ T-cell response is critical for protection against Encephalitozoon cuniculi infection. However, the factors responsible for the generation of CD8+ T-cell immunity during E. cuniculi infection and the cytokines involved in this process have not been identified. In the present study, we demonstrated that p40-deficient animals, which are unable to produce interleukin-12 (IL-12), have a serious defect in expansion of the CD8+ T-cell response which compromises the survival of an infected host. Adoptive transfer of CD8+ T cells from immunocompetent donors protected SCID mice infected with E. cuniculi, whereas administration of CD8+ T cells from p40−/− mice failed to protect infected SCID mice. In vitro dendritic cell (DC) cultures from knockout mice pulsed with E. cuniculi spores were unable to develop a robust CD8+ T-cell immune response. Addition of exogenous IL-12 or transfer of CD8+ T cells that were initially primed with DC from p40−/− animals to DC cultures from immunocompetent mice (directly or via transwells) led to optimal expansion of these cells. This IL-12-mediated reinstatement of CD8+ T-effector immunity was independent of gamma interferon (IFN-γ) as addition of antibody to the cultures failed to have an effect. These studies demonstrated that IL-12 plays a predominant role in the expansion of effector CD8+ T-cell immunity against E. cuniculi, which is critical for host survival. These findings are very important for understanding the protective immune mechanisms needed to protect an immunocompromised host against an opportunistic infection and can be extended to other microsporidial pathogens.

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