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.

Immune development in HIV-exposed uninfected children born to HIV-infected women

ABSTRACT Immunological and clinical findings suggestive of some immune dysfunction have been reported among HIV-exposed uninfected (HEU) children and adolescents. Whether these defects are persistent or transitory is still unknown. HEU pediatric population at birth, 12 months, 6-12 years were evaluated in comparison to healthy age-matched HIV-unexposed controls. Plasma levels of LPS, sCD14, cytokines, lymphocyte immunophenotyping and T-cell receptor excision circles (TREC) were assessed. HEU and controls had similar LPS levels, which remained low from birth to 6-12 years; for plasma sCD14, IL-2, IL-6, IL-7, IL-10, IL-12p70, IL-13, IL-17, IFN-γ, TNF-α, G-CSF, GM-CSF and MCP-1, which increased from birth to 12 months and then decreased at 6-12 years; and for TREC/106 PBMC at birth in HEU and controls. By contrast, plasma MIP-1β levels were lower in HEU than in controls (p=0.009) at 12 months, and IL-4 levels were higher in HEU than controls (p=0.04) at 6-12 years. Immune activation was higher in HEU at 12 months and at 6-12 years than controls based on frequencies of CD38+HLA-DR+CD8+T cells (p=0.05) and of CD38+HLA-DR+CD4+T cells (p=0.006). Resting memory and activated mature B cells increased from birth to 6-12 years in both groups. The development of the immune system in vertically HEU individuals is comparable to the general population in most parameters, but subtle or transient differences exist. Their role in influencing clinical incidences in HEU is unknown.

Comparison of dengue infection in human mononuclear leukocytes with mosquito C6/36 and mammalian Vero cells using flow cytometry to detect virus antigen

Fluorescent activated cell sorter (FACS) analysis is useful for the detection of cellular surface antigens and intracellular proteins. We used this methodology in order to detect and quantify dengue antigens in highly susceptible cells such as clone C6/36 (Aedes albopictus) and Vero cells (green monkey kidney). Additionally, we analyzed the infection in vitro of human peripheral blood mononuclear leukocytes (PBML). FACS analysis turned out to be a reliable technique to quantify virus growth in traditional cell cultures of C6/36 as well as Vero cells. High rates of infection were achieved with a good statistical correlation between the virus amount used in infection and the percentage of dengue antigen containing cells detected in infected cultures. We also showed that human monocytes (CD14+) are preferred target cells for in vitro dengue infection among PBML. Monocytes were much less susceptible to virus infection than cell lines but they displayed dengue antigens detected by FACS five days after infection. In contrast, lymphocytes showed no differences in their profile for dengue specific immunofluorescence. Without an animal model to reproduce dengue disease, alternative assays have been sought to correlate viral virulence with clinical manifestations and disease severity. Study of in vitro interaction of virus and host cells may highlight this relationship.