Lymphocyte Activation Response Research Articles

Exercise And Lymphocyte Activation Responses In Patients With Post-covid-19 Syndrome: An Exploratory Analysis From “Exer-covid” Trial

Exercise And Lymphocyte Activation Responses In Patients With Post-covid-19 Syndrome: An Exploratory Analysis From “Exer-covid” Trial

Negative Clinical Evolution in COVID-19 Patients Is Frequently Accompanied With an Increased Proportion of Undifferentiated Th Cells and a Strong Underrepresentation of the Th1 Subset.

The severity of SARS-CoV-2 infection has been related to uncontrolled inflammatory innate responses and impaired adaptive immune responses mostly due to exhausted T lymphocytes and lymphopenia. In this work we have characterized the nature of the lymphopenia and demonstrate a set of factors that hinder the effective control of virus infection and the activation and arming of effector cytotoxic T CD8 cells and showing signatures defining a high-risk population. We performed immune profiling of the T helper (Th) CD4+ and T CD8+ cell compartments in peripheral blood of 144 COVID-19 patients using multiparametric flow cytometry analysis. On the one hand, there was a consistent lymphopenia with an overrepresentation of non-functional T cells, with an increased percentage of naive Th cells (CD45RA+, CXCR3-, CCR4-, CCR6-, CCR10-) and persistently low frequency of markers associated with Th1, Th17, and Th1/Th17 memory-effector T cells compared to healthy donors. On the other hand, the most profound alteration affected the Th1 subset, which may explain the poor T cells responses and the persistent blood virus load. Finally, the decrease in Th1 cells may also explain the low frequency of CD4+ and CD8+ T cells that express the HLA-DR and CD38 activation markers observed in numerous patients who showed minimal or no lymphocyte activation response. We also identified the percentage of HLA-DR+CD4+ T cells, PD-1+CD+4/CD8+ T cells in blood, and the neutrophil/lymphocyte ratio as useful factors for predicting critical illness and fatal outcome in patients with confirmed COVID-19.

Human ovarian cancer intrinsic mechanisms regulate lymphocyte activation in response to immune checkpoint blockade

Immune checkpoint blocking antibodies are currently being tested in ovarian cancer (OC) patients and have shown some responses in early clinical trials. However, it remains unclear how human OC cancer cells regulate lymphocyte activation in response to therapy. In this study, we have established and optimised an in vitro tumour-immune co-culture system (TICS), which is specifically designed to quantify the activation of multiple primary human lymphocyte subsets and human cancer cell killing in response to PD-1/L1 blockade. Human OC cell lines and treatment naïve patient ascites show differential effects on lymphocyte activation and respond differently to PD-1 blocking antibody nivolumab in TICS. Using paired OC cell lines established prior to and after chemotherapy relapse, our data reveal that the resistant cells express low levels of HLA and respond poorly to nivolumab, relative to the treatment naïve cells. In accordance, knockdown of IFNγ receptor expression compromises response to nivolumab in the treatment naïve OC cell line, while enhanced HLA expression induced by a DNA methyltransferase inhibitor promotes lymphocyte activation in TICS. Altogether, our results suggest a ‘cross resistance’ model, where the acquired chemotherapy resistance in cancer cells may confer resistance to immune checkpoint blockade therapy through down-regulation of antigen presentation machinery. As such, agents that can restore HLA expression may be a suitable combination partner for immunotherapy in chemotherapy-relapsed human ovarian cancer patients.

Effect of a high and low dose of caffeine on human lymphocyte activation in response to antigen stimulation.

This study investigated the effect of caffeine on antigen-stimulated lymphocyte activation. Six males rested for 3.5 h after ingesting 0 (PLA), 2, or 6 (6CAF) mg·kg(-1) body mass of caffeine. The number of antigen-stimulated NK CD69(+) cells increased in 6CAF at 1 h compared with PLA (P = 0.021). Caffeine did not influence the number of antigen-stimulated CD69(+) T cells or the geometric mean fluorescence intensity expression of CD69 on antigen-stimulated lymphocytes, suggesting caffeine has little effect on antigen-stimulated lymphocyte activation.

Inhibition of Lymphocyte Activation in Response to HLA Derived Peptides in Renal Transplant Recipients.

Inhibition of Lymphocyte Activation in Response to HLA Derived Peptides in Renal Transplant Recipients.

Human Papillomavirus E7 Oncoprotein Increases Production of the Anti-Inflammatory Interleukin-18 Binding Protein in Keratinocytes

Human papillomavirus (HPV) can successfully evade the host immune response to establish a persistent infection. We show here that expression of the E7 oncoprotein in primary human keratinocytes results in increased production of interleukin-18 (IL-18) binding protein (IL-18BP). This anti-inflammatory cytokine binding protein is a natural antagonist of IL-18 and is necessary for skin homeostasis. We map increased IL-18BP production to the CR3 region of E7 and demonstrate that this ability is shared among E7 proteins from different HPV types. Furthermore, mutagenesis shows that increased IL-18BP production is mediated by a gamma-activated sequence (GAS) in the IL-18BP promoter. Importantly, the increased IL-18BP levels seen in E7-expressing keratinocytes are capable of diminishing IL-18-mediated CD4 lymphocyte activation. This study provides the first evidence for a virus protein that targets IL-18BP and further validates E7 as a key component of the HPV immune evasion armor. Infection with human papillomavirus is a leading cause of morbidity and mortality worldwide. This study demonstrates that the E7 protein increases production of the anti-inflammatory IL-18BP, a major regulator of epithelial homeostasis. A number of E7 proteins can increase IL-18BP production, and a region within the CR3 of E7 is necessary for mediating the increase. A consequence of increased IL-18BP production is a reduction in CD4-positive lymphocyte activation in response to IL-18 costimulation. These findings may shed light on the immune evasion abilities of HPV.

Analyzing actin dynamics during the activation of the B cell receptor in live B cells

Actin reorganization has been shown to be important for lymphocyte activation in response to antigenic stimulation. However, methods for quantitative analysis of actin dynamics in live lymphocytes are still underdeveloped. In this study, we describe new methods to examine the actin dynamics in B cells induced by antigenic stimulation. Using the A20 B cell line expressing GFP–actin, we analyzed in real time the redistribution of F-actin and the lateral mobility of actin flow in the surface of B cells in response to soluble and/or membrane associated antigens. Using fluorescently labeled G-actin, we identified the subcellular location and quantified the level of de novo actin polymerization sites in primary B cells. Using A20 B cells expressing G-actin fused with the photoconvertible protein mEos, we examined the kinetics of actin polymerization and depolymerization at the same time. Our studies present a set of methods that are capable of quantitatively analyzing the role of actin dynamics in lymphocyte activation.

Construction of a Salmonella Gallinarum ghost as a novel inactivated vaccine candidate and its protective efficacy against fowl typhoid in chickens

In order to develop a novel, safe and immunogenic fowl typhoid (FT) vaccine candidate, a Salmonella Gallinarum ghost with controlled expression of the bacteriophage PhiX174 lysis gene E was constructed using pMMP99 plasmid in this study. The formation of the Salmonella Gallinarum ghost with tunnel formation and loss of cytoplasmic contents was observed by scanning electron microscopy and transmission electron microscopy. No viable cells were detectable 24 h after the induction of gene E expression by an increase in temperature from 37 °C to 42 °C. The safety and protective efficacy of the Salmonella Gallinarum ghost vaccine was tested in chickens that were divided into four groups: group A (non-immunized control), group B (orally immunized), group C (subcutaneously immunized) and group D (intramuscularly immunized). The birds were immunized at day 7 of age. None of the immunized animals showed any adverse reactions such as abnormal behavior, mortality, or signs of FT such as anorexia, depression, or diarrhea. These birds were subsequently challenged with a virulent Salmonella Gallinarum strain at 3 weeks post-immunization (wpi). Significant protection against the virulent challenge was observed in all immunized groups based on mortality and post-mortem lesions compared to the non-immunized control group. In addition, immunization with the Salmonella Gallinarum ghosts induced significantly high systemic IgG response in all immunized groups. Among the groups, orally-vaccinated group B showed significantly higher levels of secreted IgA. A potent antigen-specific lymphocyte activation response along with significantly increased percentages of CD4+ and CD8+ T lymphocytes found in all immunized groups clearly indicate the induction of cellular immune responses. Overall, these findings suggest that the newly constructed Salmonella Gallinarum ghost appears to be a safe, highly immunogenic, and efficient non-living bacterial vaccine candidate that protects against FT.

DC-like cell-dependent activation of human natural killer cells by the bisphosphonate zoledronic acid is regulated by γδ T lymphocytes

AbstractBisphosphonates are mainly used for the inhibition of osteoclast-mediated bone resorption but also have been shown to induce γδ T-cell activation. Using IL-2–primed cultures of CD56+ peripheral blood mononuclear cells, we show here that zoledronic acid (zoledronate) could induce IFN-γ production not only in γδ T lymphocytes but, surprisingly, also in natural killer (NK) cells in a manner that depended on antigen-presenting cells, which share properties of inflammatory monocytes and dendritic cells (DCs; here referred to as DC-like cells). In the presence of γδ T lymphocytes, DC-like cells were rapidly eliminated, and NK cell IFN-γ production was silenced. Conversely, in the absence of γδ T lymphocytes, DC-like cells were spared, allowing NK cell IFN-γ production to proceed. γδ T cell–independent NK cell activation in response to zoledronate was because of downstream depletion of endogenous prenyl pyrophosphates and subsequent caspase-1 activation in DC-like cells, which then provide mature IL-18 and IL-1β for the activation of IL-2–primed NK cells. Pharmacologic inhibition of caspase-1 almost abolished IFN-γ production in NK cells and γδ T lymphocytes, indicating that caspase-1–mediated cytokine maturation is the crucial mechanism underlying innate lymphocyte activation in response to zoledronate.

Interferon type I responses in primary and secondary infections

The mammalian host responds to a microbial infection with a rapid innate immune reaction that is dominated by type I interferon (IFN-I) release. Most cells of vertebrates can respond to microbial attack with IFN-I production, but the cell type responsible for most of the systemic IFN-I release is thought to be plasmacytoid dendritic cells (pDCs). Besides its anti-microbial and especially anti-viral properties IFN-I also exerts a regulatory role on many facets of the sequential adaptive immune response. One of these is being the recently described partial, systemic activation of the vast majority of B and T lymphocytes in mice, irrespective of antigen reactivity. The biological significance of this partial activation of lymphocytes is at present speculative. Secondary infections occurring within a short time span of a primary infection fail to elicit a similar lymphocyte activation response due to a refractory period in systemic IFN-I production. This period of exhaustion in IFN-I responses is associated with an increased susceptibility of the host to secondary infections. The latter correlates with well-established clinical observations of heightened susceptibility of patients to secondary microbial infections after viral episodes.

Osteopontin regulates hindlimb-unloading-induced lymphoid organ atrophy and weight loss by modulating corticosteroid production

Osteopontin (OPN), a multifunctional secreted phosphoglycoprotein, plays diverse roles in bone biology, immune regulation, cell survival, inflammation, and cancer metastasis. Here we show its role in determining lymphocyte homeostasis and body mass in response to hindlimb unloading (HU), a model for evaluating effects of weightlessness on the musculoskeletal and other physiological systems. Using this stress model, we compared OPN(-/-) mice with OPN(+/+) mice subjected to HU for 3 days. Whereas OPN(+/+) mice suffered a marked reduction of body weight and significant spleen and thymus atrophy, OPN(-/-) mice exhibited minor weight loss and much less spleen and thymus atrophy. The HU-induced lymphoid organ atrophy was the result of dramatically diminished numbers, respectively, of T and B cells in the spleen and CD4(+)CD8(+) double-positive cells in the thymus of OPN(+/+) mice. Increased levels of corticosterone, which modulates lymphocyte activation responses and apoptosis during stress, were found only in OPN(+/+) mice. Apoptotic cell death was evident in the spleen and thymus of OPN(+/+) mice subjected to HU but not in OPN(-/-)mice. Importantly, lymphocytes from both OPN(+/+) and OPN(-/-) mice were equally sensitive to corticosteroid-induced apoptosis. These results reveal that OPN is required for enhanced corticosterone production, immune organ atrophy, and weight loss in mice subjected to HU.

Lymphocyte activation in response to melanoma: interaction of NK-associated receptors and their ligands.

In recent years, studies on the molecular and cellular mechanisms of immune responses against melanoma have contributed to a better understanding of how these tumours can be recognised by cytotoxic cells and the mechanisms they have developed to escape from innate and adaptive immunity. Lysis of melanoma cells by natural killer (NK) cells and cytolytic T cells is the result of a fine balance between signals transmitted by activating and inhibitory receptors. In addition to the T cell receptor, these were initially described as NK cell-associated receptors (NKRs) and were later also found on subsets of T lymphocytes, particularly effector-memory and terminally differentiated CD8 T cells. An increase of NKR(+)CD8(+) T cells has been found in melanoma patients, correlating with the expansion of differentiated effector CD8(+)CD28(null) CD27(null) T cells. NKRs can regulate the lysis of target cells expressing appropriate ligands. Activating receptors recognise ligands on tumours whereas inhibitory receptors are specific for MHC class I antigens and sense missing self. Altered expression of MHC class I antigens is frequently found on melanoma cells, preventing recognition by specific cytolytic T cells but favouring NK cell recognition. Changes in the expression of NKR-ligands in melanoma contribute in explaining the differences in the capacity of cytotoxic immune cells to control melanoma growth and dissemination.

Role of mitochondria in the immune response to cancer: a central role for Ca2+

This study demonstrates that Ca2+ stimulates mitochondrial energy metabolism during spleen lymphocyte activation in response to the ascitic Walker 256 tumor in rats. Intracellular Ca2+ concentrations, phosphorylated protein kinase C (pPKC) levels, Bcl-2 protein contents, interleukin-2 (IL-2) levels, mitochondrial uncoupling protein-2 (UCP-2) contents and reactive oxygen species (ROS) were significantly elevated in these activated lymphocytes. Mitochondria of activated lymphocytes exhibited high free Ca2+ concentrations in the matrix and enhanced oligomycin-sensitive oxygen consumption, indicating an increased rate of oxidative phosphorylation. The production of ROS was largely decreased by diphenylene iodinium in the activated lymphocytes, suggesting that NADPH oxidase is the prevalent source of these species. Accumulation of UCP-2 and the anti-apoptotic protein Bcl-2 is probably important to prevent mitochondrial dysfunction and cell death elicited by the sustained high levels of intracellular Ca2+ and ROS and may explain the observed higher resistance from activated lymphocytes against the opening of the mitochondrial membrane permeability pore (MPT). All these changes were blocked by pretreatment of the rats with verapamil, an L-type Ca2+ channel antagonist. These data demonstrate a central role of Ca2+ in the control of mitochondrial bioenergetics in spleen lymphocytes during the immune response to cancer.

Type I Interferons Trigger Systemic, Partial Lymphocyte Activation in Response to Viral Infection

The vast majority of both T and B cells in mice were found to up-regulate cell surface expression of the early activation markers CD69 and CD86, but not CD25, within 24 h of infection with Semliki Forest virus. Kinetics and magnitude of activation marker expression was dependent on live virus, dose, and correlated with strain virulence. Activation marker expression declined to baseline levels over the next 96 h. This very early "activation" of such a high percentage of lymphocytes required the presence of type I IFN receptor genes, was inducible with poly(I:C), and correlated with IFN-I levels in serum. We conclude that virus-induced IFN-I release systemically affects most of the hosts T and B cells by triggering them rapidly and independently of Ag-reactivity into a semiactivated state.

Off-pump coronary artery bypass grafting does not reduce lymphocyte activation

Objective In this study, we test the hypothesis that off-pump coronary bypass surgery might result in less lymphocyte activation than on-pump coronary surgery. We also study the behavior of lymphocyte activation markers during and after surgery. Background Coronary artery bypass surgery is known to be associated with changes of inflammatory mediators, immune function, and early phase lymphocyte activation, which could cause postoperative lymphopenia and lymphocyte unresponsiveness. Methods We studied lymphocyte activation response in 28 patients randomized to off-pump ( n=13) or on-pump ( n=15) coronary artery bypass surgery. Expression of CD25, CD26, CD69, and DR on T (CD3+) and B (CD19+) lymphocytes on peripheral blood was assessed through flow cytometry. Results The response of T lymphocytes and their activation markers, as well as B lymphocytes and their activation markers, was similar after on- and off-pump surgery. Overall, T lymphocytes decreased to the lowest level 9 h after surgery and tended to increase later. For B lymphocytes, there was early reduction with increase on the 1st postoperative day. There was early activation of CD69+ and late activation of CD25+ on T lymphocytes. For B lymphocytes, there was early activation of CD69+ and late activation of DR+. Conclusions (1) Compared to on-pump cardiopulmonary bypass, off-pump surgery does not reduce lymphocyte activation. (2) Coronary bypass surgery causes the early activation of lymphocytes, as evidenced by the increased expression of lymphocyte activation markers.

Inhibition of natural killer (NK) cell activity against varicella-zoster virus (VZV)-infected fibroblasts and lymphocyte activation in response to VZV antigen by nitric oxide-releasing agents.

The addition of nitric oxide (NO)-releasing agents, S-nitroso-N-acetyl-DL-penicillamine (SNAP), 1-hydroxy-2-oxo-2,3-bis(2-aminoethyl)-1-triazene (NOC18), 30{(+/-)-(E)-ethyl-2'-[(E)-hydroxyimino]-5-nitro-3-hexenecarbam oyl} -pyridine (NOR4) significantly inhibited NK cell activity against VZV-infected cells, while antibody-dependent cell-mediated cytotoxicity (ADCC) against VZV-infected cells was unaffected. Interferon-alpha (IFN-alpha) production by non-adherent peripheral blood mononuclear cells (NPBMC) cultured with VZV-infected cells was decreased by the addition of NO-releasing agents. Lymphocyte proliferation and the expression IL-2 receptor (CD25) in response to VZV antigen were also inhibited by the addition of NO-releasing agents. These results suggest that the production of NO by an inflammatory process may lead to inhibition of NK cell- and T cell-mediated immunity to VZV infection.

Role of regulator of G protein signaling 16 in inflammation-induced T lymphocyte migration and activation.

Chemokine-induced T lymphocyte recruitment to the lung is critical for allergic inflammation, but chemokine signaling pathways are incompletely understood. Regulator of G protein signaling (RGS)16, a GTPase accelerator (GTPase-activating protein) for Galpha subunits, attenuates signaling by chemokine receptors in T lymphocytes, suggesting a role in the regulation of lymphocyte trafficking. To explore the role of RGS16 in T lymphocyte-dependent immune responses in a whole-organism model, we generated transgenic (Tg) mice expressing RGS16 in CD4(+) and CD8(+) cells. rgs16 Tg T lymphocytes migrated to CC chemokine ligand 21 or CC chemokine ligand 12 injection sites in the peritoneum, but not to CXC chemokine ligand 12. In a Th2-dependent model of allergic pulmonary inflammation, CD4(+) lymphocytes bearing CCR3, CCR5, and CXCR4 trafficked in reduced numbers to the lung after acute inhalation challenge with allergen (OVA). In contrast, spleens of sensitized and challenged Tg mice contained increased numbers of CD4(+)CCR3(+) cells producing more Th2-type cytokines (IL-4, IL-5, and IL-13), which were associated with increased airway hyperreactivity. Migration of Tg lymphocytes to the lung parenchyma after adoptive transfer was significantly reduced compared with wild-type lymphocytes. Naive lymphocytes displayed normal CCR3 and CXCR4 expression and cytokine responses, and compartmentation in secondary lymphoid organs was normal without allergen challenge. These results suggest that RGS16 may regulate T lymphocyte activation in response to inflammatory stimuli and migration induced by CXCR4, CCR3, and CCR5, but not CCR2 or CCR7.

Direct ex vivo analysis reveals distinct phenotypic patterns of HIV-specific CD8(+) T lymphocyte activation in response to therapeutic manipulation of virus load.

Therapeutic intervention with antiretroviral therapy (ART) enables the modulation of HIV virus load and hence provides a unique opportunity to study the consequences of varying antigen load on the phenotype of virus-specific CD8(+) T lymphocytes in a persistent human viral infection. The recent advent of tetrameric peptide / HLA class I complexes has enabled the direct phenotypic characterization of antigen-specific T cell populations ex vivo. Here, we use this technology to examine directly ex vivo the consequences of therapeutic manipulation of HIV virus load on the phenotype of HIV-specific CTL. Our observations show that: (1) distinct sequential activation patterns of CD8(+) T cells are associated with increasing virus load; (2) T cell receptor (TCR) down-regulation without apoptosis represents an early event during the generation of a T cell response in a natural infection and precedes the emergence of two distinct antigen-specific CD8(+) T cell populations which differ in TCR and CD8 expression levels. Clear differences in surface Annexin V staining were observed between these populations. The observation that CTL activation, demonstrated by TCR and CD8 down-regulation, in response to rising levels of virus load, co-segregates with apoptosis only during later stages of the response indicates that antigen-associated cell death is restricted to distinct subpopulations of CTL.

Autoantibodies to TNFα in HIV-1 infection: prospects for anti-cytokine vaccine therapy

Tumor necrosis factor alpha (TNFα) is a proinflammatory cytokine principally involved in the activation of lymphocytes in response to viral infection. TNFα also stimulates the production of other cytokines, activates NK cells and potentiates cell death and/or lysis in certain models of viral infection. Although TNFα might be expected to be a protective component of an antiviral immune response, several lines of evidence suggest that TNFα and other virally-induced cytokines actually may contribute to the pathogenesis of HIV infection. Based on the activation of HIV replication in response to TNFα, HIV appears to have evolved to take advantage of host cytokine activation pathways. Antibodies to TNFα are present in the serum of normal individuals as well as in certain autoimmune disorders, and may modulate disease progression in the setting of HIV infection. We examined TNFα-specific antibodies in HIV-infected non-progressors and healthy seronegatives; anti-TNFα antibody levels are significantly higher in GRIV seropositive slow/non-progressors ( N = 120, mean = 0.24), compared to seronegative controls ( N = 12, mean = 0.11). TNFα antibodies correlated positively with viral load, ( P = 0.013, r = 0.282), and CD8+ cell count ( P = 0.03, r = 0.258), and inversely with CD4+ cell count ( P = 0.003, r = – 0.246), percent CD4+ cells ( P = 0.008, r = –0.306), and CD4 :CD8 ratio ( P = 0.033, r = – 0.251). TNFα antibodies also correlated positively with antibodies to peptides corresponding to the CD4 binding site of gp160 ( P = 0.001, r = 0.384), the CD4 identity region ( P = 0.016, r = 0.29), the V3 loop ( P = 0.005, r = 0.34), and the amino terminus of Tat ( P = 0.001, r = 0.395); TNFα antibodies also correlated positively with antibodies to Nef protein ( P = 0.008, r = 0.302). The production of anti-TNFα antibodies appears to be an adaptive response to HIV infection and suggests the potential utility of modified cytokine vaccines in the treatment of HIV infections as well as AIDS-related and unrelated autoimmune and CNS disorders.

Les cytokines dans la physiopathologie et l'exploration de la réponse allergique

Allergic reactions are under the control of several events that occur sequentially following allergen exposure, recognition by the immune system, IgE production and their interaction with effector cells bearing Fce receptors. The lymphocyte activation in response to allergens determines the intensity and the nature of the immune response. Cytokines produced by T (and non-T) cells are involved in the polarized development of the specific immune response. In particular, type 1 and type 2 cytokines are responsible for the control of the different steps during allergic reactions. Th-2 cytokines and particularly IL-4 are responsible for switching the immunoglobulin synthesis by B cells to IgE production. They also play a key role in the activation of effector cells that occurs following allergen interaction with fixed specific IgE and participate to the local inflammatory reaction. Cytokine profile determination appears to represent a helpful laboratory parameter in the understanding of the mechanisms underlying allergic diseases. The development of new technological tools may allow the use of cytokine profiles determination in clinical biology. This review aims to analyze the involvement of the cytokine network in the mechanisms leading to IgE production and the involvement of cytokines in effector mechanisms of allergic reactions. It also analyses the potential use of cytokine profile determination for diagnosis purpose and survey of immune desensitization of allergic diseases.