Effects of rooibos tea extract on antigen-specific antibody production and cytokine generation in vitro and in vivo.

Rooibos tea contains a large amount of flavonoids and acts as a potent antioxidant. In this study, we examined the effects of Rooibos tea extract on antigen-specific antibody production and cytokine generation in vitro and in vivo. The primary in vitro anti-ovalbumin (anti-OVA) or sheep red blood cell (SRBC) antibody production in murine splenocytes was markedly stimulated by the addition of the tea extract at concentrations of 1-100 microg/ml. On the other hand, a nonspecific antibody response elicited with lipopolysaccharide (LPS) in purified splenic B-cells was not modified by the extract. Rooibos tea extract caused an increase in the generation of interleukin 2 (IL-2) both in OVA- and anti-CD3-primed splenocytes at concentrations ranging from 10 microg/ml to 1000 microg/ml. In contrast, this tea extract suppressed the generation of interleukin 4 (IL-4) in OVA-primed splenocytes. Moreover, the reduction of OVA-induced antibody production in serum of the cyclosporin A (CyA) -treated rats can be significantly restored and the IL-2 generation in murine splenocytes was stimulated, following oral administrations of Rooibos tea extract. Thus, our findings suggested that Rooibos tea extract may facilitate the antigen-specific antibody production through selective augmentation of IL-2 generation both in vitro and in vivo. Collectively, Rooibos tea intake may be of value in prophylaxis of the diseases involving a severe defect in Th1 immune response such as cancer, allergy, AIDS, and other infections.     

Comparative study on the modulation of IgE and cytokine production by Phellinus linteus grown on germinated brown Rice, Phellinus Linteus and germinated brown rice in murine splenocytes

We compared the immunomodulating activities in mice of extracts from Phellinus linteus grown on germinated brown rice (PB), Phellinus linteus (PL) alone, and germinated brown rice (BR) alone. The PL, BR and PB-treated mice were administered with the respective extract (2 mg/head/day) by oral gavage for 4 weeks. All extracts markedly decreased the IgE production and allergic responses in serum and splenocytes. PL and PB increased the proportion of CD4(+) but not CD8(+) T cells in splenocytes. Cytokine production was significantly augmented in all treated mice; the concentration of IFN-gamma was greater in the PL, BR and PB mice than in the control group. The concentration of IL-10 was lower in the BR group than in the other groups. These results may be related to the suppression of IgE production. We conclude that PB modulated the immune responses of IgE production and Th1/Th2 cytokine secretion in murine splenocytes.     

Mushroom acidic glycosphingolipid induction of cytokine secretion from murine T cells and proliferation of NK1.1 alpha/beta TCR-double positive cells in vitro

Interferon (IFN)-γ and interleukin (IL)-4 regulate many types of immune responses. Here we report that acidic glycosphingolipids (AGLs) of Hypsizigus marmoreus and Pleurotus eryngii induced secretion of IFN- γ and IL-4 from T cells in a CD11c-positive cell-dependent manner similar to that of α-galactosylceramide (α-GalCer) and isoglobotriaosylceramide (iGb3), although activated T cells by AGLs showed less secretion of cytokine than those activated by α-GalCer. In addition, stimulation of these mushroom AGLs induced proliferation of NK1.1 α/β TCR-double positive cells in splenocytes. Administration of a mixture of α-GalCer and AGLs affected the stimulation of α-GalCer and generally induced a subtle Th1 bias for splenocytes but induced an extreme Th2 bias for thymocytes. These results suggested that edible mushroom AGLs contribute to immunomodulation.     

Relationship between the Quality of Konjac Flour and the Molecular Matter Nature of Konjac Mannan

We compared the immunomodulating activities in mice of extracts from Phellinus linteus grown on germinated brown rice (PB), Phellinus linteus (PL) alone, and germinated brown rice (BR) alone. The PL, BR and PB-treated mice were administered with the respective extract (2 mg/head/day) by oral gavage for 4 weeks. All extracts markedly decreased the IgE production and allergic responses in serum and splenocytes. PL and PB increased the proportion of CD4⁺ but not CD8⁺ T cells in splenocytes. Cytokine production was significantly augmented in all treated mice; the concentration of IFN-γ was greater in the PL, BR and PB mice than in the control group. The concentration of IL-10 was lower in the BR group than in the other groups. These results may be related to the suppression of IgE production. We conclude that PB modulated the immune responses of IgE production and Th1/Th2 cytokine secretion in murine splenocytes.     

Prevention of autoantibody-mediated Graves'-like hyperthyroidism in mice with IL-4, a Th2 cytokine

Graves' hyperthyroidism has long been considered to be a Th2-type autoimmune disease because it is directly mediated by autoantibodies against the thyrotropin receptor (TSHR). However, several lines of evidence have recently challenged this concept. The present study evaluated the Th1/Th2 paradigm in Graves' disease using a recently established murine model involving injection of adenovirus expressing the TSHR (AdCMVTSHR). Coinjection with adenovirus expressing IL-4 (AdRGDCMVIL-4) decreased the ratio of Th1/Th2-type anti-TSHR Ab subclasses (IgG2a/IgG1) and suppressed the production of IFN-gamma by splenocytes in response to TSHR Ag. Importantly, immune deviation toward Th2 was accompanied by significant inhibition of thyroid-stimulating Ab production and reduction in hyperthyroidism. However, in a therapeutic setting, injection of AdRGDCMVIL-4 alone or in combination with AdCMVTSHR into hyperthyroid mice had no beneficial effect. In contrast, coinjection of adenoviruses expressing IL-12 and the TSHR promoted the differentiation of Th1-type anti-TSHR immune responses as demonstrated by augmented Ag-specific IFN-gamma secretion from splenocytes without changing disease incidence. Coinjection of adenoviral vectors expressing IL-4 or IL-12 had no effect on the titers of anti-TSHR Abs determined by ELISA or thyroid-stimulating hormone-binding inhibiting Ig assays, suggesting that Ab quality, not quantity, is responsible for disease induction. Our observations demonstrate the critical role of Th1 immune responses in a murine model of Graves' hyperthyroidism. These data may raise a cautionary note for therapeutic strategies aimed at reversing Th2-mediated autoimmune responses in Graves' disease in humans.     

A soluble lymphocyte activation gene-3 molecule used as a vaccine adjuvant elicits greater humoral and cellular immune responses to both particulate and soluble antigens

The lymphocyte activation gene-3 (LAG-3) product is a MHC class II ligand that has been used in vivo to stimulate MHC class II+ APCs to increase tumor-specific immune responses. We investigated whether LAG-3 could also play an adjuvant role in vivo for the induction of humoral and CD4 or CD8 cell-mediated immune responses when immunizing mice with a particulate (hepatitis B surface Ag) or soluble (OVA) Ag. In both cases, coadministration of 1 microg of a soluble fusion protein between murine LAG-3 and the Fc fraction of a murine IgG2a mAb (mLAG-3Ig) as a vaccine adjuvant induced or increased CTL responses to the corresponding MHC class I-restricted peptide. In addition, splenocytes of mice vaccinated with either the particulate or soluble Ag plus mLAG-3Ig exhibited a significantly greater proliferative response than did splenocytes of mice immunized with Ag and a control Ig molecule. Similarly, these splenocytes had a greater Th1- but not Th2-type cytokine response. Finally, mice immunized with Ag plus mLAG-3Ig produced higher titers of Abs than mice immunized with Ag and a control Ig molecule. Thus, these data provide evidence of a novel means of improving the immunogenicity of subunit vaccines.     

Alteration of Cytokine Production during Visceral Larva Migrans by Toxascaris leonina in Mice

To determine alteration of immune responses during visceral larva migrans (VLM) caused by Toxascaris leonina at several time points, we experimentally infected mice with embryonated eggs of T. leonina and measured T-helper (Th) cell-related serial cytokine production after infection. At day 5 post infection (PI), most larvae were detected from the lungs, spleen, intestine, and muscle. Expression of thymic stromal lymphopoietin (TSLP) and CCL11 (eotaxin) showed a significant increase in most infected organs, except the intestine. However, expression of the CXCL1 (Gro-α) gene was most highly enhanced in the intestine at day 14 PI. Th1-related cytokine secretion of splenocytes showed increases at day 28 PI, and the level showed a decrease at day 42 PI. Th2-related cytokine secretion of splenocytes also showed an increase after infection; in particular, IL-5 level showed a significant increase at day 14 PI, and the level showed a decrease at day 28 PI. However, levels of Th17-related cytokines, IL-6 and IL-17A, showed gradual increases until day 42 PI. In conclusion, Th1, Th2, and Th17-related cytokine production might be important in immune responses against T. leonina VLM in experimental mice.     

Low TLR4 expression by liver dendritic cells correlates with reduced capacity to activate allogeneic T cells in response to endotoxin

Signaling via TLRs results in dendritic cell (DC) activation/maturation and plays a critical role in the outcome of primary immune responses. So far, no data exist concerning TLR expression by liver DC, generally regarded as less immunostimulatory than secondary lymphoid tissue DC. Because the liver lies directly downstream from the gut, it is constantly exposed to bacterial LPS, a TLR4 ligand. We examined TLR4 expression by freshly isolated, flow-sorted C57BL/10 mouse liver DC compared with spleen DC. Real-time PCR revealed that liver CD11c+CD8alpha- (myeloid) and CD11c+CD8alpha+ ("lymphoid-related") DC expressed lower TLR4 mRNA compared with their splenic counterparts. Lower TLR4 expression correlated with reduced capacity of LPS (10 ng/ml) but not anti-CD40-stimulated liver DC to induce naive allogeneic (C3H/HeJ) T cell proliferation. By contrast to LPS-stimulated splenic DC, these LPS-activated hepatic DC induced alloantigen-specific T cell hyporesponsiveness in vitro, correlated with deficient Th1 (IFN-gamma) and Th2 (IL-4) responses. When higher LPS concentrations (> or =100 ng/ml) were tested, the capacity of liver DC to induce proliferation of T cells and Th1-type responses was enhanced, but remained inferior to that of splenic DC. Hepatic DC activated by LPS in vivo were inferior allogeneic T cell stimulators compared with splenic DC, whereas adoptive transfer of LPS-stimulated (10 ng/ml) liver DC induced skewing toward Th2 responses. These data suggest that comparatively low expression of TLR4 by liver DC may limit their response to specific ligands, resulting in reduced or altered activation of hepatic adaptive immune responses.     

In vitro effects of genistein and resveratrol on the production of interferon-gamma (IFNgamma) and interleukin-10 (IL-10) by stimulated murine splenocytes.

Phytoestrogens are a group of plant-derived biologically active substances with a chemical structure that resembles that of 17beta-estradiol (E2). As the presence of estrogen receptors (ER) has been identified in several immune cells, phytoestrogens may also have a great impact on the immune system. The aim of our study was to determine the in vitro effects of genistein and resveratrol on the production of interferon-gamma (IFNgamma) and interleukin-10 (IL-10) by stimulated murine splenocytes and compare them with the effects of natural E2. Phorbol 12-miristate 13-acetate (PMA) together with ionomycin was used to stimulate the cells. E2 and genistein did not show any significant effects on the stimulated production of IFNgamma. Resveratrol had a mild inhibitory effect on IFNgamma production at the concentration of 10(-7)M; however, this difference did not reach statistical significance (p>0.05). IL-10 levels in the splenocytes culture supernatants were found to be increased in the presence of E2, genistein and resveratrol; however, these effects were also not statistically significant. To determine whether the exposure to our studied phytoestrogens induced a shift in the T-helper 1/T-helper 2 (Th1/Th2) balance, we calculated the ratio between the production of IFNgamma, the prototypic Th1 cytokine, and the production of IL-10, the prototypic Th2 cytokine, at different concentrations of our tested substances. Genistein at the concentrations of 10(-6) and 10(-7)M and resveratrol at the concentrations of 10(-6)M decreased significantly the IFNgamma/IL-10 ratio. This decrease was comparable to that of E2 at the concentrations of 10(-7)M. From our in vitro experiments we conclude that genistein and resveratrol, similarly to E2, by decreasing the IFNgamma/IL10 ratio may shift the Th1/Th2 balance towards the Th2 response.     

Immunologic significance of HLA class I genes in measles virus-specific IFN-γ and IL-4 cytokine immune responses

The variability of immune responses modulated by human leukocyte antigen (HLA) genes and secreted cytokines is a significant factor in the development of a protective effect of measles vaccine. We studied the association between type 1 helper T cells (Th1)- and Th2-like cytokine immune responses and HLA class I alleles among 339 schoolchildren who previously received two doses of the measles vaccine. Median values for measles-specific interferon gamma (IFN-γ) and interleukin-4 (IL-4) cytokines were 40.7 pg/ml [interquartile range (IQR) 8.1–176.7] and 9.7 pg/ml (IQR 2.8–24.3), respectively. Class I HLA-A (*0101 and *3101) and HLA-Cw (*0303 and *0501) alleles were significantly associated with measles-virus-induced IFN-γ secretion. HLA-A*3101 and Cw*0303 were associated with a higher median IFN-γ response, while A*0101 and Cw*0501 were associated with lower measles-specific IFN-γ response. We found limited associations between HLA class I gene polymorphisms and Th2-like (IL-4) immune responses after measles vaccination, indicating that HLA class I molecules may have a limited effect on measles-vaccine-induced IL-4 secretion. Understanding the genetic factors that influence variations in cytokine secretion following measles vaccination will provide insight into the factors that influence both cell-mediated and humoral immunity to measles.     

IL-18 is redundant in T-cell responses and in joint inflammation in antigen-induced arthritis

IL-18 is an important cofactor in Th1 immune responses and it has additional roles in inflammation. Recent reports suggest the contribution of IL-18 to immune responses may vary between mouse strains and immune contexts. We investigated the contribution of IL-18 to T-cell activation and joint inflammation in Ag-induced arthritis (AIA) in C57Bl/6 mice. AIA and cutaneous delayed-type hypersensitivity (DTH) reactions were induced in wild-type (WT) and IL-18-/- C57Bl/6 mice, and Ag-specific T-cell proliferation and IFN-gamma and IL-4 production were measured. The humoral immune response was measured as serum antibody to the disease-initiating Ag, methylated BSA (mBSA). Splenocyte production of IL-6 was measured by ELISA. To confirm the dependence of this model on Th1-cell-mediated immunity, IL-12p40-/- mice were similarly studied. WT mice developed synovitis, joint effusion, cartilage destruction and bone damage associated with induction of DTH, and in vitro Ag-specific T-cell proliferation and IFN-gamma production. Unexpectedly, IL-18-/- mice developed AIA and indices of T-cell activation were similar to those of WT mice. In contrast, IL-12p40-/- mice did not develop AIA, DTH or T-cell activation. WT and IL-18-/- mice, but not IL-12p40-/- mice, developed significantly increased serum antibody to mBSA compared with naive controls. WT and IL-18-/- splenocytes produced high levels of IL-6, whereas IL-12p40-/- cells had significantly lower IL-6 production compared with both. In conclusion, IL-18 is redundant both as a Th1 response cofactor and inflammatory cytokine, whereas IL-12p40-/- is a key cytokine, in AIA in C57Bl/6 mice.     

Anti-CD3 antibody induces unresponsiveness to IL-2 in Th1 clones but not in Th2 clones

Culture of murine T cells with immobilized (platebound) anti-CD3 antibody results in autocrine growth factor secretion in both Th1 (IL-2 producing) and Th2 (IL-4 producing) cells. Using a panel of murine T cell clones, we demonstrate that the IL-2-induced proliferation of Th1 clones is dramatically inhibited by immobilized anti-CD3 antibody, whereas that of Th2 clones is not. This unresponsiveness of Th1 clones to IL-2 is not due to decreases in IL-2R expression. Supernatants from Th1 or Th2 cell cultures fail to alter the effects of anti-CD3 on the two types of clones, suggesting that unresponsiveness induced in Th1 clones or the lack thereof in Th2 clones is not mediated by a stable cytokine(s). Accessory cells enhance the proliferation of Th1 cells exposed to low concentrations of anti-CD3, but the unresponsiveness induced by high concentrations of anti-CD3 is not prevented by accessory cells. Finally, soluble anti-CD4 antibody prevents the induction of the unresponsive state even at high concentrations of anti-CD3. These experiments demonstrate that two subsets of cloned CD4+ T cells differ in their responses to anti-CD3, and that CD4 molecules may play a critical role in regulating the outcome of receptor-mediated stimulation.     

Lidocaine depresses splenocyte immune functions following trauma-hemorrhage in mice

Traumatic and/or surgical injury as well as hemorrhage induces profound suppression of cellular immunity. Although local anesthetics have been shown to impair immune responses, it remains unclear whether lidocaine affects lymphocyte functions following trauma-hemorrhage (T-H). We hypothesized that lidocaine will potentiate the suppression of lymphocyte functions after T-H. To test this, we randomly assigned male C3H/HeN (6–8 wk) mice to sham operation or T-H. T-H was induced by midline laparotomy and 90 min of hemorrhagic shock (blood pressure 35 mmHg), followed by fluid resuscitation (4x shed blood volume in the form of Ringer lactate). Two hours later, the mice were killed and splenocytes and bone marrow cells were isolated. The effects of lidocaine on concanavalin A-stimulated splenocyte proliferation and cytokine production in both sham-operated and T-H mice were assessed. The effects of lidocaine on LPS-stimulated bone marrow cell proliferation and cytokine production were also assessed. The results indicate that T-H suppresses cell proliferation, Th1 cytokine production, and MAPK activation in splenocytes. In contrast, cell proliferation, cytokine production, and MAPK activation in bone marrow cells were significantly higher 2 h after T-H compared with shams. Lidocaine depressed immune responses in splenocytes; however, it had no effect in bone marrow cells in either sham or T-H mice. The enhanced immunosuppressive effects of lidocaine could contribute to the host's enhanced susceptibility to infection following T-H. shock; bone marrow cells     

Differential effects of positive and negative proliferative stimuli on murine cytolytic and helper T-cell clones

Studies were performed to determine whether substances could be identified which exhibited differential regulatory effects--either positive or negative--on the growth of murine alloreactive cytolytic (Tc) and helper (Th) cloned T-cell lines. The following lines of evidence suggested that Tc and Th proliferate in response to the same growth factor (GF). (1) When GF-containing fluids from cultures of phorbol myristic acetate (PMA)-activated EL4 thymoma were fractionated by a variety of biochemical techniques. Tc and Th eluted together. (2) Absorption of GF-containing supernatants with either cloned Tc or cloned Th depleted GF activity for each to a similar extent, and GF eluted from either Tc or Th to which it had adsorbed supported the proliferation of Tc and Th equally well. (3) Lectin-depleted supernatants from cultures of concanavalin A (Con A)-activated Th stimulated the proliferation of Th as well as Tc. (4) Recombinant human interleukin (IL-2) supported the growth of Tc and Th with equal efficiency. On the other hand, the following observations indicated that Tc and Th differed in their responses to inhibitors of GF-driven proliferation. (1) Con A at greater than or equal to 0.3 micrograms/ml inhibited the GF-driven proliferation of each of three Th lines but not either of two Tc lines. To the contrary, Con A enhanced GF-dependent proliferation of Tc. (2) Like Con A, allogeneic splenocytes selectively depressed GF-driven proliferation of Th but not Tc. (3) A substance generated during the acid elution of GF from cells, possibly a modified fetal calf serum component, greatly reduced the GF-driven proliferation of Tc but not Th. These results suggest that differential control of the proliferation of Tc and Th in cellular immune responses may be achieved via negative regulatory signals and raise the possibility that substances which can selectively depress the proliferation of specific T-cell subsets might be found which would be of therapeutic value.     

Does leptin mediate the effect of photoperiod on immune function in mice?

Seasonal fluctuations in immune status have been documented for avian and mammalian populations. During the late summer and early fall, immune function is bolstered to help animals cope with the more physiologically demanding winter. The environmental cue for these seasonal changes is apparently decreasing photoperiod. In the present study, we determined the potential role of leptin in mediating the effect of photoperiod on cell-mediated immune responses in male mice. Leptin-deficient (ob/ob) and littermate control mice were housed for 10 wk in either a short (8L:16D) or a long (16L:8D) photoperiod beginning at 6 wk of age. After the mice were killed, immune and reproductive organs were weighed and splenocytes isolated. The proliferative and cytokine responses (interleukin [IL]-2 and IL-4) of splenocytes to the T-cell mitogen, concanavalin A (Con A; 0-40 microg/ml), were determined. Body weights were elevated and both testes and seminal vesicle weights subnormal in ob/ob mice (by ANOVA, main effect of leptin deficiency), but thymuses and spleens were of normal size. Serum leptin levels were at minimum detection limits in ob/ob mice, but leptin levels in control mice housed at 8L:16D were higher than in control mice housed at 16L:8D. The proliferative response of splenocytes from ob/ob mice to Con A was subnormal (by ANOVA, main effect of leptin deficiency), but photoperiod had no effect on this response. Production of IL-2 in splenocytes of ob/ob mice was subnormal (by ANOVA, main effect of leptin deficiency) irrespective of photoperiod, but cells from mice housed at 8L:16D (by ANOVA, main effect of photoperiod) produced more IL-2 than cells from animals housed at 16L:8D. In contrast, a leptin deficiency did not alter IL-4 production, but cells from animals (ob/ob and controls) housed at 16L:8D produced less IL-4 than cells from animals housed at 8L:16D (by ANOVA, main effect of photoperiod). The present study suggests that both photoperiod and leptin have mutually independent effects on the proliferation of lymphocytes and cytokine production profiles. The data do not provide definitive support for the hypothesis that photoperiod-induced changes in leptin secretion mediate the effects of season on immune status.     

Interactions of Haemophilus ducreyi and purified cytolethal distending toxin with human monocyte-derived dendritic cells, macrophages and CD4+ T cells

To evaluate the early stages of the host response to chancroid bacterium Haemophilus ducreyi, we investigated the in vitro responses of monocyte-derived dendritic cells (DCs) and macrophages (MQs) to this pathogen and Haemophilus influenzae. The phagocytic activities and pro-inflammatory cytokine secretion profiles of the antigen-presenting cells (APCs) were analyzed after exposure to gentamycin-killed bacteria, H. ducreyi lipooligosaccharide (LOS), and purified cytolethal distending toxin (HdCDT). T-cell proliferation and cytokine release were examined after co-culturing isolated autologous CD4+ T cells with antigen-pulsed APCs. Both the DCs and MQs phagocytosed H. ducreyi and H. influenzae, as estimated by flow cytometry. All of the strains induced APC secretion of TNF-alpha, IL-6, IL-8, and IL-12, as measured by ELISA. Other human cells, particularly endothelial cells and fibroblasts, also produced cytokines when stimulated with these bacteria. Purified LOS at concentration 1 microg/ml induced two to threefold lower levels of cytokines than the whole bacteria, which indicates that other components are involved in immune activation. HdCDT inhibited partially the production of the aforementioned cytokines. High levels of IFN-gamma, but not of IL-4 and IL-13, were secreted by T cells after activation by either DCs or MQs that were pre-exposed to bacteria, indicating the Th1 nature of the immune response. The levels of T-cell proliferation induced by H. ducreyi were lower than those induced by H. influenzae. HdCDT-treated APCs did not display cytokine responses or T-cell proliferation. These results indicate that HdCDT intoxication, which results in progressive apoptosis of APCs, may hamper early stage immune responses.     

Schistosoma mansoni and alpha-galactosylceramide: prophylactic effect of Th1 Immune suppression in a mouse model of Graves' hyperthyroidism

Graves' hyperthyroidism, an organ-specific autoimmune disease mediated by stimulatory thyrotropin receptor (TSHR) autoantibodies, has been considered a Th2-dominant disease. However, recent data with mouse Graves' models are conflicting. For example, we recently demonstrated that injection of BALB/c mice with adenovirus coding the TSHR induced Graves' hyperthyroidism characterized by mixed Th1 and Th2 immune responses against the TSHR, and that transient coexpression of the Th2 cytokine IL-4 by adenovirus skewed Ag-specific immune response toward Th2 and suppressed disease induction. To gain further insight into the relationship between immune polarization and Graves' disease, we evaluated the effect of Th2 immune polarization by helminth Schistosoma mansoni infection and alpha-galactosylceramide (alpha-GalCer), both known to bias the systemic immune response to Th2, on Graves' disease. S. mansoni infection first induced mixed Th1 and Th2 immune responses to soluble worm Ags, followed by a Th2 response to soluble egg Ags. Prior infection with S. mansoni suppressed the Th1-type anti-TSHR immune response, as demonstrated by impaired Ag-specific IFN-gamma secretion of splenocytes and decreased titers of IgG2a subclass anti-TSHR Abs, and also prevented disease development. Similarly, alpha-GalCer suppressed Ag-specific splenocyte secretion of IFN-gamma and prevented disease induction. However, once the anti-TSHR immune response was fully induced, S. mansoni or alpha-GalCer was ineffective in curing disease. These data support the Th1 theory in Graves' disease and indicate that suppression of the Th1-type immune response at the time of Ag priming may be crucial for inhibiting the pathogenic anti-TSHR immune response.     

Dual modulation of airway smooth muscle contraction by Th2 cytokines via matrix metalloproteinase-1 production

Altered contractility of airway smooth muscle (SM) is one of the main causes of allergic asthma, in which the predominance of Th2 over Th1 cytokines plays a central role. In the present study, we examine the effects of Th2 cytokines on airway SM contraction. Treatment with a low concentration of IL-4 (0.2 ng/ml) for 6 h augmented, whereas higher concentrations (2-20 ng/ml) inhibited, agonist-induced contractions of collagen gels containing bovine tracheal SM cells. Another Th2 cytokine (IL-13) showed an augmentation of gel contraction in the concentration range of 20-200 ng/ml. IL-4 and IL-13 increased mRNA expression and protein secretion of matrix metalloproteinase (MMP)-1, but these cytokines did not affect Ca(2+)-mobilizing properties and phosphorylation levels of myosin L chain in bovine tracheal SM cells. These changes were sensitive to wortmannin, an inhibitor of PI3K, but not to leflunomide, an inhibitor of STAT6. Scanning electron microscope observation revealed that collagen fibers twining around SM cells were completely dissolved in 20 ng/ml IL-4-treated gels and reorganized into basket-like structure in 20 ng/ml IL-13-treated gels. Exogenous application of high and low concentrations of MMP-1 also induced the inhibition and augmentation of gel contraction, respectively. Furthermore, nonselective MMP inhibitor galardin suppressed the effects of IL-4 and IL-13 on gel contraction, and MMP-1-targeted small-interfering RNA reversed the inhibitory effects of IL-4 on gel contraction to the augmentation. This indicates that Th2 cytokines modulate airway contraction without affecting cellular contractility but by secreting MMP-1 from the SM cells via PI3K activation and changing cell-to-matrix interactions.     

Inhibition of Th2-mediated allergic airway inflammatory disease by CD137 costimulation

The engagement of CD137 (4-1BB), an inducible T cell costimulatory receptor and member of the TNF receptor superfamily, by agonistic Abs can promote strong tumor and viral immunity mediated by CD8(+) T cells and stimulate IFN-gamma production. However, its role in Th2-mediated immune responses has not been well defined. To address this issue, we studied the function of CD137 engagement using an allergic airway disease model in which the mice were sensitized with inactivated Schistosoma mansoni eggs followed by S. mansoni egg Ag challenge directly in the airways and Th1/2 cytokine production was monitored. Interestingly, treatment of C57BL/6 mice with agonistic anti-CD137 (2A) during sensitization completely prevents allergic airway inflammation, as shown by a clear inhibition of T cell and eosinophil infiltration into the lung tissue and airways, accompanied by diminished Th2 cytokine production and reduced serum IgE levels, as well as a reduction of airway hyperresponsiveness. At various time points after immunization, restimulated splenocytes from 2A-treated mice displayed reduced proliferation and Th2 cytokine production. In accordance with this, agonistic Ab to CD137 can directly coinhibit Th2 responses in vitro although it costimulates Th1 responses. CD137-mediated suppression of Th2 response is independent of IFN-gamma and T regulatory cells. Our study has identified a novel pathway to inhibit Th2 responses in a CD137-dependent fashion.