CD4+CD69+ T cells and CD4+CD25+FoxP3+ Treg cells imbalance in peripheral blood, spleen and peritoneal lavage from pristane-induced systemic lupus erythematosus (SLE) mice

Abstract Background: Adaptive immune cells, including CD4+CD69+ and CD4+CD25+FoxP3+ regulatory T (Treg) cells, are important for maintaining immunological tolerance. In human systemic lupus erythematosus (SLE), CD4+CD25+FoxP3+ Treg cells are reduced, whereas CD69 expression is increased, resulting in a homeostatic immune imbalance that may intensify autoreactive T cell activity. To analyze the mechanisms implicated in autotolerance failure, we evaluated CD4+CD69+ and CD4+CD25+FoxP3+ T cells and interleukin profiles in a pristane-induced SLE experimental model. Methods: For lupus induction, 26 female Balb/c mice received a single intraperitoneal 0.5 ml dose of pristane, and 16 mice received the same dose of saline. Blood and spleen samples were collected from euthanized mice 90 and 120 days after pristane or saline inoculation. Mononuclear cells from peripheral blood (PBMC), peritoneal lavage (PL) and splenocytes were obtained by erythrocyte lysis and cryopreserved for further evaluation by flow cytometry using the GuavaEasyCyte TM HT. After thawing, cells were washed and stained with monoclonal antibodies against CD3, CD4, CD8, CD25, CD28, CD69, FoxP3, CD14 and Ly6C (BD Pharmingen TM). Interleukins were quantified using Multiplex® MAP. The Mann-Whitney test and the Pearson coefficient were used for statistical analysis, and p < 0.05 considered significant. Results: Compared with the controls, SLE-induced animals presented increased numbers of CD4+CD69+ T cells in the blood on T90 and T120 (p = 0.022 and p = 0.008) and in the spleen on T120 (p = 0.049), but there were decreased numbers in the PL (p = 0.049) on T120. The percentage of Treg was lower in blood (p < 0.005 and p < 0.012) on T90 and T120, in spleen (p = 0.043) on T120 and in PL (p = 0.001) on T90. Increased numbers of CD4+ CD69+ T cells in the PL were positively associated with high IL-2 (p = 0.486) and IFN-γ (p = 0.017) levels, whereas reduced Treg cells in the blood were negatively correlated with TNFα levels (p = 0.043) and positively correlated with TGFβ1 (p = 0.038). Conclusion: Increased numbers of CD4+CD69+ T cells and reduced numbers of CD4+CD25+FoxP3+ Treg cells with an altered interleukin profile suggests loss of autotolerance in pristane-induced lupus mice, which is similar to human lupus. Therefore, this model is useful in evaluating mechanisms of cellular activation, peripheral tolerance and homeostatic immune imbalance involved in human SLE.

Differential expression of CC chemokines (CCLs) and receptors (CCRs) by human T lymphocytes in response to different Aggregatibacter actinomycetemcomitans serotypes

In Aggregatibacter actinomycetemcomitans, different serotypes have been described based on LPS antigenicity. Recently, our research group has reported a differential immunogenicity when T lymphocytes were stimulated with these different serotypes. In particular, it was demonstrated that the serotype b of A. actinomycetemcomitans has a stronger capacity to trigger Th1- and Th17-type cytokine production.Objective This study aimed to quantify the expression of different CC chemokines (CCLs) and receptors (CCRs) in T lymphocytes stimulated with the differentA. actinomycetemcomitans serotypes. In addition, the expression of the transcription factors T-bet, GATA-3, RORC2, and Foxp3, master-switch genes implied in the Th1, Th2, Th17, and T-regulatory differentiation, respectively, was analysed in order to determine T-cell phenotype-specific patterns of CCL and CCR expression upon A. actinomycetemcomitans stimulation.Material and Methods Human naïve CD4+ T lymphocytes were obtained from healthy subjects and stimulated with autologous dendritic cells primed with the differentA. actinomycetemcomitans serotypes. The expression levels for the chemokines CCL1, CCL2, CCL3, CCL5, CCL11, CCL17, CCL20, CCL21, CCL25, and CCL28, as well as the chemokine receptors CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 were quantified by qPCR. Similarly, the expression levels for the transcription factors T-bet, GATA-3, RORC2, and Foxp3 were quantified and correlated with the CCL and CCR expression levels.Results Higher expression levels of CCL2, CCL3, CCL5, CCL20, CCL21, CCL28, CCR1, CCR2, CCR5, CCR6, CCR7, and CCR9 were detected in T lymphocytes stimulated with the serotype b of A. actinomycetemcomitans compared with the other serotypes. In addition, these higher expression levels of CCLs and CCRs positively correlated with the increased levels of T-bet and RORC2 when T lymphocytes were stimulated with the serotype b.Conclusion A T-lymphocyte response biased towards a Th1- and Th17-pattern of CCL and CCR expression was detected under stimulation with the serotype b ofA. actinomycetemcomitans.

Cytokines produced by CD4+ T cells against a synthetic GTF-I (1301-1322) peptide of Streptococcus mutans in naturally sensitized humans

Streptococcus mutans (S. mutans) es el principal agente etiologico de la caries dental. Las proteínas PAc y glucosiltransferasas (GTFs) son factores de virulencia de este microorganismo relacionados con su fisiopatogenia y han sido usados en investigaciones de una vacuna para la caries dental. El objetivo de este estudio fue observar si GTFs (1301-1322) tiene la capacidad de activar las células T CD4+ en CMSP de humanos naturalmente sensibilizados, identificar el tipo de respuesta y establecer su relación con la caries dental. 30 individuos clasificados en los siguientes 3 grupos, fueron estudiados: caries activa (AC), historia de caries (HC) y libres de caries (H). Muestras de sangre fueron tomadas de cada individuo. La estimulación antígeno específico y la citometría de flujo fueron usadas para determinar las células productoras de citoquina IFN-y (citoquinas tipo 1) e IL-13 (citoquinas tipo 2). Se encontró respuesta de memoria celular frente a GTF-I (1301-1322) en humanos naturalmente sensibilizados. Tres tipos de respuesta fueron detectados: TH0, TH1 y NR. Se encontró un mayor porcentaje de LTCD4+ productores de IFN-y que de IL-13 (p=0.006). No se encontraron diferencias estadísticamente significativas para las otras variables estudiadas para los tres grupos (p<0.05). Se concluye que la respuesta inmune celular específica frente al péptido sintético GTF-I (1301-1322) de S, mutans, no es diferente entre los individuos sensibilizados naturalmente, resistentes a caries y con caries.

Activated peripheral lymphocytes with increased expression of cell adhesion molecules and cytotoxic markers are associated with dengue fever disease

The immune mechanisms involved in dengue fever and dengue hemorrhagic/dengue shock syndrome are not well understood. The ex vivo activation status of immune cells during the dengue disease in patients was examined. CD4and CD8 T cells were reduced during the acute phase. Interestingly, CD8 T cells co-expressing activation marker HLA-DR, Q, P, and cytolytic granule protein-Tia-1 were significantly higher in dengue patients than in controls. Detection of adhesion molecules indicated that in dengue patients the majority of T cells (CD4 and CD8) express the activation/memory phenotype, characterized as CD44HIGH and lack the expression of the naïve cell marker, CD62L LOW. Also, the levels of T cells co-expressing ICAM-1 (CD54), VLA-4, and LFA-1 (CD11a) were significantly increased. CD8 T lymphocytes expressed predominantly low levels of anti-apoptotic molecule Bcl-2 in the acute phase, possibly leading to the exhibition of a phenotype of activated/effector cells. Circulating levels of IL-18, TGF-b1 and sICAM-1 were significantly elevated in dengue patients. Early activation events occur during acute dengue infection which might contribute to viral clearance. Differences in expression of adhesion molecules among CD4 and CD8 T cells might underlie the selective extravasation of these subsets from blood circulation into lymphoid organs and/or tissues. In addition, activated CD8 T cells would be more susceptible to apoptosis as shown by the alteration in Bcl-2 expression. Cytokines such as IL-18, TGF-b1, and sICAM-1 may be contributing by either stimulating or suppressing the adaptative immune response, during dengue infection, thereby perhaps establishing a relationship with disease severity.

Low-cost CD4 enumeration in HIV-infected patients in Thailand.

In Thailand, over one million people have been infected with HIV since the beginning of the epidemic. This has created a great burden on the country's limited health care budget. Monitoring CD4+ T-lymphocytes is important to determine the success of any antiretroviral therapy as well as HIV vaccine trials. However, the high cost of CD4 counts makes monitoring of every HIV-infected patient impossible in Thailand. Therefore, the development of affordable strategies is necessary in order to allow more HIV infected persons to access CD4 testing to control the disease. The current standard methods for enumeration of CD4+ T-lymphocytes are performed on whole blood by flow cytometric immunophenotyping using the 6-tube 2-color and 3-tube 3-color panels recommended by the Centers for Diseases Control (CDC). In this study, percentage CD4+ T-lymphocyte values (from 142 HIV-seropositive patients and 26 anti-HIV negative adult blood donors) generated by the use of just 2 reagents (CD45/CD4) in a 1-tube 2-color panel employing side scatter/CD45 morphospectral gating were compared to those obtained by state of the art methods. We also compared the use of generic monoclonal antibody reagents with commercial reagents and found the results to be comparable with an overall correlation coefficient (r) of more than 0.95 for both CD4+ and CD8+ T-lymphocytes. Bland-Altman analysis of the mean CD4 values plotted against the difference in values between the generic reagents and the commercial reagents showed no bias. The 1-tube 2-color method using generic monoclonal antibody reagents potentially permits more affordable but reliable CD4 testing and therefore could increase access for more HIV-infected patients in resource-poor countries.

Human immune responses to dengue viruses.

Dengue fever (DF) and dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS) are major public health problems in many areas of the world. We are analyzing the human immune responses to dengue viruses, in order to understand the mechanism of recovery from dengue virus infections and the pathogenesis of DHF/DSS. Human natural killer (NK) cells lyse dengue virus-infected cells to a greater degree than uninfected cells. Antibodies to dengue viruses augment the lysis of dengue virus-infected cells by NK cells. Dengue virus-infected monocytes produce high levels of interferon alpha (IFN alpha). DR+ lymphocytes also produce high levels of IFN alpha after contact with dengue virus-infected monocytes. The IFN alpha produced protects uninfected monocytes from dengue virus infection. These results suggest that NK cells and IFN alpha may play an important role in controlling primary dengue virus infection. Dengue virus-specific CD4+CD8(-)T lymphocytes and CD4(-)CD8+T lymphocytes are present in the peripheral blood mononuclear cell population from donors who were infected with dengue virus. Most of CD4+T lymphocytes are dengue serotype-crossreactive. They lyse dengue virus-infected autologous cells in an HLA class II-restricted fashion, and produce interferon gamma (IFN gamma). IFN gamma augments dengue virus infection of monocytic cells in the presence of antidengue virus antibodies by increasing the number of Fc gamma receptors. Dengue virus-specific CD8+T lymphocytes lyse dengue virus-infected autologous cells in an HLA class I-restricted fashion. These CD8+T lymphocytes are also dengue serotype-crossreactive.(ABSTRACT TRUNCATED AT 250 WORDS)