Protection mediated by chemokine CXCL10 in BALB/c mice infected by Leishmania infantum

BACKGROUND Visceral leishmaniasis (VL) caused by Leishmania infantum is characterised by the loss of the ability of the host to generate an effective immune response. Chemokines have a direct involvement in the pathogenesis of leishmaniasis, causing a rapid change in the expression of these molecules during infection by Leishmania. OBJECTIVES Herein, it was investigated the role of CXCL10 in controlling infection by L. infantum. METHODS RAW 264.7 macrophages were infected with L. infantum in vitro and treated or not with CXCL10 (25, 50 and 100 ng/mL). Parasite load, as well as nitric oxide (NO), IL-4 and IL-10 production were assessed at 24 and 48 h after infection. In vivo, BALB/c mice were infected and treated or not with CXCL10 (5 μg/kg) at one, three and seven days of infection. Parasite load, IFN-g, IL-4, TGF-β and IL-10 were evaluated one, seven and 23 days post treatment. FINDINGS In vitro, CXCL10 reduced parasitic load, not dependent on NO, and inhibited IL-10 and IL-4 secretion. In vivo, CXCL10 was able to reduce the parasite load in both liver and spleen, four weeks after infection, representing a higher decrease in the number of parasites in these organs, also induced IFN-γ at day 23 after treatment, correlating with the decrease in parasite load, and reduced IL-10 and TGF-β. MAIN CONCLUSIONS This study suggests a partial protective role of CXCL10 against L. infantum, mediated by IFN-g, not dependent on NO, and with suppression of IL-10 and TGF-β. These data may provide information for the development of new approaches for future therapeutic interventions for VL.

Aureobasidium-Derived Soluble Branched (1,3-1,6) beta-Glucan (Sophy beta-glucan) Enhances Natural Killer Activity in Leishmania amazonensis-Infected Mice

The beta-glucans derived from yeast cell walls have been reported for having many immunomodulatory activities in vivo and in vitro. In this study, Aureobasidium-derived soluble branched (1,3-1,6) beta-glucan (Sophy beta-glucan) was checked for natural killer (NK) activity and for the production of IFN-gamma and IL-4 in Leishmania amazonensis infection. The main experiment was performed with a group of female C57BL/6 and BALB/c mice, orally supplemented with 5% of Sophy beta-glucan and infected with promastogotes of L. amazonensis (1 x 10(7)) into the footpad. Increase in the footpad thickness with time was observed in BALB/c mice in spite of the oral Sophy beta-glucan supplement, but it was less in C57BL/6 mice. The difference in overall mean footpad thickness between 'infection only' versus 'infection + glucan' groups was statistically significant (P < 0.001). High NK activity in C57BL/6 than BALB/c mice was observed in 'glucan only' group compared to the control group and also in 'infection + glucan' group compared to 'infection only' group. The difference in the NK activity among these groups was significant (P < 0.05). The IFN-gamma level increased at weeks 7 and 8 post-infection in C57BL/6 mice and was significantly high in 'infection + glucan' group compared to the 'infection only' group (P < 0.05). IL-4 levels did not increase up to detectable levels throughout the study. The results led a conclusion that Sophy beta-glucan enhances NK activity and cellular immunity in L. amazonensis-infected mice.

Interferon gamma (IFNgamma) & interleukin-4 (IL-4) gene variants & cytokine levels in pulmonary tuberculosis.

BACKGROUND & OBJECTIVES: Cytokine gene polymorphisms may alter Th1/Th2 balance with major implications in tuberculosis. The aim of our study was to find out whether Interferon gamma +874A and IL-4 -590T polymorphisms were associated with susceptibility to pulmonary tuberculosis as well as the level of IFNgamma and IL-4 in south Indian population. METHODS: Interferon gamma +874A and IL-4 -590T promoter polymorphisms were studied in 129 pulmonary tuberculosis (PTB) patients and 127 normal healthy subjects (NHS) and were associated with culture filtrate and live Mycobacterium tuberculosis induced IFNgamma and IL-4 production in peripheral blood mononuclear cells (PBMCs). IL-4 gene variants were also associated with IgG antibody levels against M. tuberculosis culture filtrate antigen. RESULTS: The variant IFNgamma genotypes and IFNgamma levels between genotypes did not differ significantly in patients and controls. Significantly increased frequency of variant IL-4 'CT' genotype in PTB patients (P<0.05) and 'CC' genotype in control group (P<0.01) was observed. IL-4 levels were detectable in very few subjects and the IgG levels did not differ between the three IL-4 genotypes. INTERPRETATION & CONCLUSION: The study suggests a lack of functional association of Interferon gamma +874A polymorphism in tuberculosis in south Indian population. The higher frequency of IL-4 'CT' genotype in PTB suggests a possible association of IL-4 -590T promoter polymorphism with susceptibility to tuberculosis, and the 'CC' genotype may be associated with protection.

The effect of Panax ginseng on forced immobility time & immune function in mice.

BACKGROUND & OBJECTIVES: Panax ginseng has been used as a traditional medicine for many years mainly among Asian peoples for developing physical strength. We undertook this study to determine the immune-enhancement effect of P. ginseng using a forced swimming test (FST) and by measuring cytokine production in MOLT-4 cell culture and mouse peritoneal macrophages. METHODS: P. ginseng was orally administered to mice once a day for 7 days. The anti-immobility effect of P. ginseng on the FST and blood biochemical parameters related to fatigue, glucose (Glc); blood urea nitrogen (BUN); latic dehydrogenase (LDH); total protein (TP) and production of cytokines in human T cell line, MOLT-4 cells and mouse peritoneal macrophages were investigated. RESULTS: After two and seven days, the immobility time was decreased in the P. ginsengadministrated mice as compared to the control group; however, this reduction was not significant. In addition, the amount of TP in the blood serum was significantly increased. However, the levels of Glc, BUN, and LDH did not show a significant change. P. ginseng significantly (P<0.05) increased interferon (IFN)-gamma production and expression as compared to control at 48 h in MOLT-4 cells. P. ginseng plus recombinant IFN-gamma instead of P. ginseng alone significantly increased the production of the tumour necrosis factor (TNF)-alpha in the mouse peritoneal macrophages. INTERPRETATION & CONCLUSION: Our results suggest that P. ginseng may be useful for an immune promoter. Further studies are needed to understand the mechanism of its action.

Overexpression of CIITA in T Cells Aggravates Th2-Mediated Colitis in Mice

The MHC class II transactivator (CIITA) is the master transcriptional regulator of genes involved in MHC class II restricted antigen presentation. Previously we suggested another role of CIITA in Th1/Th2 balance by demonstrating that forced expression of CIITA in murine T cells repressed Th1 immunity both in vitro and in vivo. However, the results were contradictory to the report that CIITA functioned to suppress the production of Th2 cytokine by CD4+T cells in CIITA deficient mice. In this study, we investigated the influence of constitutive expression of CIITA in T cells on Th2 immune response in vivo using murine experimental colitis model. In the dextran sodium sulfate-induced acute colitis, a disease involving innate immunity, CIITA transgenic mice and wild type control mice showed similar progression of the disease. However, the development of oxazolone-induced colitis, a colitis mediated by predominantly Th2 immune response, was aggravated in CIITA-transgenic mice. And, CD4+T cells from the mesenteric lymph node of CIITA-transgenic mice treated with oxazolone exhibited a high level of IL-4 secretion. Together, these data demonstrate that constitutive expression of CIITA in T cells skews immune response to Th2, resulting in aggravation of Th2-mediated colitis in vivo.

Two-signal blockade with anti-CD45RB and anti-CD154 monoclonal antibodies inhibits graft rejection via CD4-dependent mechanisms in allogeneic skin transplantation

Blockade of signal 1 or 2 for T-cell activation by the use of anti-CD45RB and anti-CD154 monoclonal antibodies (mAb) (two-signal blockade) has been proven effective in preventing or delaying graft rejection. However, the mechanisms of its immunomodulatory effects are clearly unknown and the present studies were performed to determine how the two-signal blockade modulate allogeneic immune responses, especially T-cell mediated cellular immunity, in a murine skin allograft model. We now report on the profound inhibition of alloreactive T cells by two-signal blockade via CD4-dependent mechanisms. C57BL/6 mice of BALB/c skin allograft were treated with anti-CD45RB, anti-CD154, CTLA4-Ig, or their combinations. For depletion of CD4 or CD8 T cells, the recipients received CD4-depleting or CD8-depleting mAb. We confirmed that survival of skin allograft was markedly prolongated in the two-signal blockade-treated group. In depletion study, anti-CD45RB, anti-CD154 and CD4-depleting mAb-treated group showed acute rejection of skin allograft in contrast to CD8-depleting group treated with the two-signal blockade. In the group treated with the two-signal blockade, the proportions of CD4+CD45RB(low)and CD8+CTLA-4 regulatory T cells were increased while effector CD8+ T cells, including IFN-gamma-secreting and CD8+CD62L(low)T cells, were decreased when compared with non-treated group. In contrast, the CD4-depleted group treated with the two-signal blockade resulted in recovery from immunoregulatory effects of two-signal blockade. In addition, results of IL-4 and IL-10 production were also showed CD4-dependence. Therefore, the two-signal blockade is accompanied by CD4-dependent mechanisms in allogeneic skin transplantation.

Murine Model of Buckwheat Allergy by Intragastric Sensitization with Fresh Buckwheat Flour Extract

Food allergies affect about 4% of the Korean population, and buckwheat allergy is one of the most severe food allergies in Korea. The purpose of the present study was to develop a murine model of IgE-mediated buckwheat hypersensitivity induced by intragastric sensitization. Young female C3H/HeJ mice were sensitized and challenged intragastricly with fresh buckwheat flour (1, 5, 25 mg/dose of proteins) mixed in cholera toxin, followed by intragastric challenge. Anaphylactic reactions, antigen-specific antibodies, splenocytes proliferation assays and cytokine productions were evaluated. Oral buckwheat challenges of sensitized mice provoked anaphylactic reactions such as severe scratch, perioral/periorbital swellings, or decreased activity. Reactions were associated with elevated levels of buckwheatspecific IgE antibodies. Splenocytes from buckwheat allergic mice exhibited significantly greater proliferative responses to buckwheat than non-allergic mice. Buckwheat-stimulated IL-4, IL-5, and INF-gamma productions were associated with elevated levels of buckwheat-specific IgE in sensitized mice. In this model, 1 mg and 5 mg dose of sensitization produced almost the same degree of Th2-directed immune response, however, a 25 mg dose showed blunted antibody responses. In conclusion, we developed IgE-mediated buckwheat allergy by intragastric sensitization and challenge, and this model could provide a good tool for future studies.

Interleukin-4 production in BALB/c mice immunized with Anisakis simplex

We investigated the interleukin (IL-4) levels in BALB/c mice immunized with Anisakis extract in single or multiple doses and in mice orally infected with a larva. From animals immunized maximum responses were obtained with the multiple doses with an only IL-4 peak. Conversely, in the mice inoculated with a larva per os, the IL-4 levels showed two peaks of different rates

Ovalbumin fused with diphtheria toxin protects mice from ovalbumin induced anaphylactic shock

For those with allergy, vaccination with a specific allergen has often been used as a major therapeutic measure. However, the universal application of this technique in clinics have been restricted due to its low success rates and the risk of active systemic anaphylactic shock (ASAS). In this regard, we constructed a fusion protein (OVA-DT), ovalbumin (OVA) fused with diphtheria toxin protein (DT), which may exert a specific cytotoxicity to cells bearing OVA-specific IgE. Its therapeutic effect was evaluated in mice (BALB/c) sensitized with OVA (Os-mice). OVA challenges to the OVA-sensitized mice (Os-mice) caused ASAS to death within 30 min, but OVA-DT treatment afforded mice complete protection. When OVA-DT was treated to the Os-mice, none showed the signs of ASAS when re-challenged 48 h after the treatment. OVA-DT itself was not found to be toxic or allergenic in normal mice. The effect of OVA-DT on the biological functions of mast cells was also studied. Binding of OVA-DT to OVA-specific IgE bearing mast cells and the inhibition of histamine release from these cells were observed. In addition, OVA-DT treatment inhibited the proliferation of OVA-specific B cells in mice. In Os-mice treated with OVA-DT, levels of anti-OVA IgG2a in serum and the production of IFN-gamma by splenic lymphocytes were found to increase, but the production of IL-4 by these cells decreased. Re-direction of cytokine profiles from OVA-specific Th2 to OVA-specific Thl is suggested. These results indicate that OVA-DT can protect Os-mice from ASAS due to OVA challenge, because it inactivates OVA-specific IgE-expressing cells, including mast cells and B cells.

Producción de interferón-gamma e interleuquina 4 por células mononucleadas de sangre periférica infectadas con virus respiratorio sincicial y adenovirus / Interferon-gamma and interleukin-4 production by respiratory synctytial virus and adenovirus infected peripheral blood mononuclear cells

Las infecciones respiratorias por virus respiratorio sincicial (VRS) y adenovirus (Ad) son la principal causa de morbimortalidad entre las infecciones respiratorias agudas bajas (RAB) de la infancia. Ambos virus pueden dejas secuelas, al VRS se le ha atribuido desencadenar obstrucción bronquial persistente y al Ad, especialmente el Ad7h, bronquectasias, fibrosis y daño pulmonar crónico. Los mecanismos por los que estos virus pueden producir estas secuelas no se conocen, pero hay evidencias que sugieren que ésta sea causada por un mecanismo inmunológico, dependiente del tipo de virus y de la respuesta del huésped. El objetivo de este trabajo fue determinar el tipo de respuesta inmune frente a la infección por VRS y Ad mediante la cuantificación de interferón-gamma (IFN-gamma) e interleuquina-4 (IL-4), citoquinas marcadas de respuesta inmune celular y humoral respectivamente. Las ILs fueron cuantificadas en el sobrenadante de cultivo de células mononucleadas de sangre periférica infectadas o no infectadas in vitro con VRS, Ad3, Ad7h y control con mitógeno (PHA) y de células mononucleadas de lactantes con infección natural por VRS y grupo control estimuladas o no con mitógenos (PHA y PWN). Los lactantes con IRAB por VRS presentaron una disminución significativa en la producción de IFN-gamma e IL-4 por células mononucleadas no estimuladas y estimuladas con PHA. Esta disminución fue mayor para el IFN-gamma que para la IL-4, por lo que la relación IFN eta/IL-4 fue menor en estos lactantes. La producción de IL-4 pero no la de IFN-eta de los lactantes infectados con VRS que tenían antecedentes de atopia (p< 0,02). Las células mononucleadas de niños sanos infectadas in vitro con Ad estimulan la producción de IFN-gamma pero no la de IL-4 y con Ad7h, responden con una producción de IFN-gamma en este modelo in vitro. Estos resultados sugieren que la respuesta del sistema inmune frente a la infección viral dependerá del tipo de virus infectante y de la variabilidad genética del individuo. Esto demuestra la importancia de estudiar la respuesta inmune de cada virus en los diferentes individuos ya que el resultado de protección o daño dependerá de la interrelación huésped-virus