Th1-inducing Cytokine Research Articles

P295 - MBL level and deficiency is not associated with either Crohn's disease or ulcerative colitis, disease phenotype, CRP, serology profile and NOD2/CARD15 genotype in a large Hungarian IBD cohort, but was associated to the lack of TLR4 variants in CD

P295 - MBL level and deficiency is not associated with either Crohn's disease or ulcerative colitis, disease phenotype, CRP, serology profile and NOD2/CARD15 genotype in a large Hungarian IBD cohort, but was associated to the lack of TLR4 variants in CD

Type-1 polarized dendritic cells primed for high IL-12 production show enhanced activity as cancer vaccines

While multiple pathways of dendritic cell (DC) maturation result in transient production of IL-12, fully mature DCs show reduced ability to produce IL-12p70 upon a subsequent interaction with Ag-specific T cells, limiting their in vivo performance as vaccines. Such "DC exhaustion" can be prevented by the presence of IFNgamma during the maturation of human DCs (type-1-polarization), resulting in improved induction of tumor-specific Th1 and CTL responses in vitro. Here, we show that type-1 polarization of mouse DCs strongly enhances their ability to induce CTL responses against a model tumor antigen, OVA, in vivo, promoting the induction of protective immunity against OVA-expressing EG7 lymphoma. Interestingly, in contrast to the human system, the induction of mouse DC1s requires the participation of IL-4, a nominal Th2-inducing cytokine. The current data help to explain the previously reported Th1-driving and anti-tumor activities of IL-4, and demonstrate that type-1 polarization increases in vivo activity of DC-based vaccines.

Increased serum levels of IL‐22 in patients with nickel contact dermatitis

Nickel can elicit both Th1-type andTh2-type responses in vitro (1) inpatients with nickel allergic contactdermatitis,butthiscomplexcytokinecascade has still to be clarified. Therecently discovered Th17 subset,which has crucial functions in hostdefence against infections and hasbeen implicated in the developmentofautoimmunediseases(2),hasbeensupposed to play an important rolein some inflammatory and autoim-mune skin disorders, such as contacthypersensitivity(3)andpsoriasis(4),respectively. Th17 cells are charac-terized by expression of interleukin(IL)-6, tumour necrosis factor-a,granulocyte–macrophage colony-stimulating factor, IL-17A, IL-17F,IL-21, IL-22, and IL-26 (5).Among these cytokines, IL-22,a member of the IL-10 cytokine fam-ily, described as having proinflam-matory activities on liver, pancreas,intestine, and skin (reviewed in 6),has been demonstrated to have a cru-cial function in the development ofdermal inflammation and epidermalacanthosis induced by IL-23 in mice(4). Moreover, IL-22 seems to beinvolved in the pathogenesis of psori-asis in humans, as demonstrated bythehighserumlevelsshowedbypsori-atic patients and the high levels pro-duced by T cells isolated by psoriaticskin (6), where the IL-22 receptor isexpressed on a variety of epithelialtissues(4).However,nodataareavail-ableon thepossibleroleplayed byIL-22in nickel contacthypersensitivityinhumans, thus we measured the circu-latinglevelsofthiscytokineinpatientswith allergic nickel contact dermatitis.We enrolled 31 female patientsaffected by allergic contact dermatitisto nickel (mean age 31.9 years; range17–64 years) diagnosed followingpatch testing in accordance withthe International Contact DermatitisResearch Group guidelines. Bloodsamples were collected after patchtesting during a period of clinicalremission 1 month after nickel con-tact avoidance.15 sex- and age-matched blooddonors, with no contact dermatitisand negative patch tests, were re-cruited as controls. Each subject gavepreviously used written, informedconsent to the study.Serum IL-22 was measured usingan enzyme-linked immunosorbentassay kit (R&D System Europe,Abingdon, UK). All samples wereanalysed in duplicate.Differences in IL-22 blood levelswere assessed by the Student’s t-testfor unpaired comparison, assumingunequal variances. Data were ex-pressed as mean standard devia-tion. A P value <0.05 was consideredto be significant.IL-22 serum levels were signifi-cantly higher in patients affected bycontact dermatitis compared withcontrols (17.10 9.50 pg/ml versus8.61 7.25 pg/ml, P ¼ 0.002)(Fig. 1). No correlation between IL-22 levels and age was found.About 10 years ago, it was demon-stratedthatnickel-specificCD4Tcellsexpressing the cutaneous lymphocyte-associated antigen skin-homingrecep-tor can synthesize and release IL-17and that IL-17 modulates variousproinflammatory functions of kerati-nocytes, especially when actingtogether with interferon-g and IL-4(7). Zheng et al. have recently demon-strated that the injection of IL-23(a Th17-inducing cytokine) into miceears induces a model of psoriasis-likelesions characterized by epidermalacanthosis with inflammatory cellularinfiltration mediated by IL-17 andIL-22. These features decrease inIL-22-deficient mice (4), and theadministration of IL-22 neutralizingautoantibodies reduces acanthosis,inflammatory infiltrates, and expres-sion of Th17 cytokines (8). However,thehistologicalfeaturesfoundinthesemurine models are not exclusivelycharacteristic of psoriasis but of aller-gic contact dermatitis as well.*Theseauthorscontributedequallytothis work.

Apigenin, a non-mutagenic dietary flavonoid, suppresses lupus by inhibiting autoantigen presentation for expansion of autoreactive Th1 and Th17 cells

IntroductionLupus patients need alternatives to steroids and cytotoxic drugs. We recently found that apigenin, a non-mutagenic dietary flavonoid, can sensitize recurrently activated, normal human T cells to apoptosis by inhibiting nuclear factor-kappa-B (NF-κB)-regulated Bcl-xL, cyclooxygenase 2 (COX-2), and cellular FLICE-like inhibitory protein (c-FLIP) expression. Because sustained immune activation and hyperexpression of COX-2 and c-FLIP contribute to lupus, we treated SNF1 mice that spontaneously develop human lupus-like disease with apigenin.MethodsSNF1 mice with established lupus-like disease were injected with 20 mg/kg of apigenin daily and then monitored for development of severe nephritis. Histopathologic changes in kidneys, IgG autoantibodies to nuclear autoantigens in serum and in cultures of splenocytes, along with nucleosome-specific T helper 1 (Th1) and Th17 responses, COX-2 expression, and apoptosis of lupus immune cells were analyzed after apigenin treatment.ResultsApigenin in culture suppressed responses of Th1 and Th17 cells to major lupus autoantigen (nucleosomes) up to 98% and 92%, respectively, and inhibited the ability of lupus B cells to produce IgG class-switched anti-nuclear autoantibodies helped by these Th cells in presence of nucleosomes by up to 82%. Apigenin therapy of SNF1 mice with established lupus suppressed serum levels of pathogenic autoantibodies to nuclear antigens up to 97% and markedly delayed development of severe glomerulonephritis. Apigenin downregulated COX-2 expression in lupus T cells, B cells, and antigen-presenting cells (APCs) and caused their apoptosis. Autoantigen presentation and Th17-inducing cytokine production by dendritic cells were more sensitive to the inhibitory effect of apigenin in culture, as evident at 0.3 to 3 μM, compared with concentrations (10 to 100 μM) required for inducing apoptosis.ConclusionsApigenin inhibits autoantigen-presenting and stimulatory functions of APCs necessary for the activation and expansion of autoreactive Th1 and Th17 cells and B cells in lupus. Apigenin also causes apoptosis of hyperactive lupus APCs and T and B cells, probably by inhibiting expression of NF-κB-regulated anti-apoptotic molecules, especially COX-2 and c-FLIP, which are persistently hyperexpressed by lupus immune cells. Increasing the bioavailability of dietary plant-derived COX-2 and NF-κB inhibitors, such as apigenin, could be valuable for suppressing inflammation in lupus and other Th17-mediated diseases like rheumatoid arthritis, Crohn disease, and psoriasis and in prevention of inflammation-based tumors overexpressing COX-2 (colon, breast).

Analysis of the Mechanism for the Development of Allergic Skin Inflammation and the Application for Its Treatment: Establishment of a Modified Allergic Dermatitis Model in Mouse Ear Lobes by Application of 12-O-Tetradecanoyl Phorbol 13-Acetate: Putative Involvement of Thymic Stromal Lymphopoietin and Roles of Histamine

We established a novel allergic dermatitis model in mouse ear lobes in which antigen-nonspecific inflammation was induced by painting 12-O-tetradecanoylphorbol 13-acetate (TPA) between sensitization and challenge with picryl chloride (PiCl). This model has an advantage for analyzing atopic dermatitis-like inflammation within a short period. Analysis of the time course changes in the PiCl-induced swelling showed that the allergic inflammation was shifted from a delayed-type response to a biphasic response consisting of a weak immediate-phase response and a late-phase response by painting with TPA. The application of TPA increased the PiCl-induced infiltration of eosinophils and mast cells at the inflammatory site and shifted the cytokine milieu from Th1 to Th2. The expression of the Th2-inducing cytokine thymic stromal lymphopoietin (TSLP) mRNA was also increased by TPA. These findings suggested that the induction of antigen-nonspecific inflammation by TPA before the antigen challenge enhanced the Th2 response and modified the PiCl-induced delayed type-hypersensitivity. Using this model, we clarified that histamine plays significant roles in the early-phase swelling via H(1) receptors and the late-phase swelling via H(3)/H(4) receptors. Thus, we suggested the usefulness of the combined treatment with an H(1) antagonist and an H(4) antagonist for the suppression of atopic dermatitis.

Influence ofSlc11a1(formerlyNramp1) on DSS-induced colitis in mice

Multiple genetic studies in humans indicate a role for solute carrier family 11a member 1 [SLC11A1; formerly natural resistance-associated macrophage protein 1 (NRAMP1)] in autoimmune disease susceptibility, including ulcerative colitis. Murine Slc11a1 has many pleiotropic effects on macrophage activation and proinflammatory responses. To determine which of these are important in ulcerative colitis, we established a phenotype for oral dextran sulfate sodium (DSS)-induced acute colitis in congenic Slc11a1 wild-type (wt) and mutant (mt) mice on a B10 background. For over 7 days of treatment with 2% DSS in the drinking water, Slc11a1 wt mice showed enhanced acute ulcerative colitis, as demonstrated by significantly greater body weight loss and reduction in colon length, as well as a marked increase in monocyte/macrophage inflammatory infiltrates and histopathology changes in the colon. This was accompanied by a clear, inverse relationship between IFN-gamma and IL-10 responses in Slc11a1 wt compared with mt mice, resulting in a significantly higher ratio of IFN-gamma:IL-10 in wt compared with mt mice in lymph node and splenic T cells. RNase protection assays confirmed the presence of significantly higher IFN-gamma at the RNA level in the colons of wt compared with mt mice at Day 7 of treatment. Interestingly this was accompanied by significantly enhanced RNA levels for the acute-phase protein IL-6, which is known to inhibit the generation of forkhead box P3+ regulatory T cells and help to drive the differentiation of Th17 from naive T cells and not by differences in RNA for IL-12p35 or IL-12p40 molecules that dimerize to form the Th1-inducing cytokine IL-12.

Foal Monocyte-Derived Dendritic Cells Become Activated uponRhodococcus equiInfection

Susceptibility of foals to Rhodococcus equi pneumonia is exclusive to the first few months of life. The objective of this study was to investigate the immediate immunologic response of foal and adult horse antigen-presenting cells (APCs) upon infection with R. equi. We measured the activation of the antigen-presenting major histocompatibility complex (MHC) class II molecule, costimulatory molecules CD40 and CD86, the cytokine interleukin-12 (IL-12), and the transcriptional factor interferon regulatory factor 1 (IRF-1) in monocyte-derived macrophages (mMOs) and dendritic cells (mDCs) of adult horses and foals of different ages (from birth to 3 months of age) infected with virulent R. equi or its avirulent, plasmid-cured derivative. Infection with virulent or avirulent R. equi induced (P <or= 0.01) the expression of IL-12p35 and IL-12p40 mRNAs in foal mMOs and mDCs at different ages. This response was likely mediated by the higher (P=0.008) expression of IRF-1 in foal mDCs at birth than in adult horse mDCs. R. equi infection promoted comparable expression of costimulatory molecules CD86 and CD40 in foal and adult horse cells. The cytokine and costimulatory response by foal mDCs was not accompanied by robust MHC class II molecule expression. These data suggest that foal APCs detect the presence of R. equi and respond with the expression of the Th1-inducing cytokine IL-12. Nevertheless, there seems to be a limitation to MHC class II molecule expression which we hypothesize may compromise the efficient priming of naïve effector cells in early life.

IL-23 Promotes Maintenance but Not Commitment to the Th17 Lineage

IL-23 plays a critical role establishing inflammatory immunity and enhancing IL-17 production in vivo. However, an understanding of how it performs those functions has been elusive. In this report, using an IL-17-capture technique, we demonstrate that IL-23 maintains the IL-17-secreting phenotype of purified IL-17(+) cells without affecting cell expansion or survival. IL-23 maintains the Th17 phenotype over multiple rounds of in vitro stimulation most efficiently in conjunction with IL-1beta. However, in contrast to Th1 and Th2 cells, the Th17 phenotype is not stable and when long-term IL-23-stimulated Th17 cultures are exposed to Th1- or Th2-inducing cytokines, the Th17 genetic program is repressed and cells that previously secreted IL-17 assume the cytokine secreting profile of other Th subsets. Thus, while IL-23 can maintain the Th17 phenotype, it does not promote commitment to an IL-17-secreting lineage.

Synthesis and In Vivo Evaluation of 4-Deoxy-4,4-difluoro-KRN7000

The synthesis of 4-deoxy-4,4-difluoro-KRN7000 starting from phytosphingosine is described. Key steps include a regioselective benzylation of azidophytosphingosine and a deoxofluor-mediated fluorination of the corresponding 4-ketone. This fluorination failed completely when the adjacent 3-OH was protected as benzyl ether but proceeded well when a benzoyl group was used. The biological evaluation reveals a bias toward Th1 cytokine induction upon Natural Killer T cell activation.

Dual role of shikonin in early and late stages of collagen type II arthritis

To investigate the anti-inflammatory or immunomodulatory effect of shikonin on early stage and established murine collagen-induced arthritis (CIA). Mouse were injected intraperitoneally with shikonin (5 mg/kg) for 10 days along before or after the onset of CIA. The arthritis response was monitored visually by macroscopic scoring. Reverse transcription-polymerase chain reaction and western blotting were employed to determine the mRNA and protein expression of cytokine in patella with adjacent synovium in CIA mouse. Histology of knee was used to assess the occurrence of cartilage destruction and bone erosion. Shikonin (5 mg/kg) treatment along had no effect on macroscopic score and incidence of arthritis on early stage of CIA. However, a pronounced amelioration of macroscopic score and cartilage destruction was found in mouse treated with shikonin on established CIA for 10 days. Moreover, The mRNA levels of Th1 cytokines [tumor necrosis factor-alpha and interleukin (IL)-12] was significantly inhibited both in the synovial tissue and in the articular cartilage in treated groups compared with those in control groups, whereas the mRNA and protein levels of Th2 cytokines (IL-10 and IL-4) remained elevated throughout the treatment period. Moreover, the inflammatory cytokine, the mRNA and protein levels of IL-6 was down-regulated in mice with established CIA after treatment with shikonin. T-box expressed in T cells (T-bet) mRNA levels were decreased in shikonin compared with control group, and GATA-3 mRNA levels were higher than that in control group. Shikonin treatment on established CIA can inhibit Th1 cytokines expression and induce Th2 cytokines expression in mice with established CIA. The inhibited effect of shikonin on Th1 cytokines expression may be mediated not only by inhibiting Th1 responses through T-bet mechanism, but also by inducing anti-inflammatory mediators such as IL-10 and IL-4 through a GATA-3 dependent mechanism.

Blocking TH17-polarizing cytokines by histone deacetylase inhibitors in vitro and in vivo

Histone deacetylase (HDAC) inhibitors are small molecules inducing cell-cycle arrest, differentiation, and apoptosis, currently undergoing clinical trials as anticancer drugs. In addition, emerging evidence suggests HDAC inhibitors may have anti-inflammatory and immunomodulatory properties as well, although the molecular mechanisms remain poorly defined. Given the central role of dendritic cells (DC) in the induction and maintenance of the inflammatory and immune response, we investigated the effects of HDAC inhibitors on the maturation and activation of human monocyte-derived DC in the presence of LPS and IFN-gamma. Our results show that the production of T(H)1- and T(H)17-inducing cytokines, namely IL-12 and IL-23, was inhibited by trichostatin A (72% and 52%, respectively) and suberoylanilide hydroxamic acid (86% and 83%). Strikingly, HDAC inhibitors were effective if added simultaneously as well as after the proinflammatory challenge, and their effect was not associated to a reduction of expression or function of LPS/IFN-gamma receptors. These findings were confirmed in two different murine models. In addition, HDAC inhibitors selectively blocked the production of T(H)1-attracting chemokines CXCL9, CXCL10, and CXCL11. The reduction of T(H)1- and T(H)17-inducing cytokines as well as T(H)1-attracting chemokines may represent relevant mechanisms through which HDAC inhibitors at nonproapoptotic doses exert their immunomodulatory properties.

CD8+ Th17 Mediate Costimulation Blockade-Resistant Allograft Rejection in T-bet-Deficient Mice

While studying Th responses induced by cardiac transplantation, we observed that mice deficient in the Th1 transcription factor T-bet (T-bet(-/-)) mount both Th1 and Th17 responses, whereas wild-type recipients mount only Th1 responses. Cells producing both IFN-gamma and IL-17 were readily detectable within the rejecting graft of T-bet(-/-) recipients, but were absent from the spleen, indicating that the in vivo microenvironment influences Th function. In addition, disrupting CD40-CD40L costimulatory interactions was highly effective at prolonging allograft survival in WT mice, but ineffective in T-bet(-/-) recipients. In this study, we report that CD8(+) Th17 mediate costimulation blockade-resistant rejection in T-bet(-/-) allograft recipients. Depleting CD8(+) cells or neutralizing IL-17 or the Th17-inducing cytokine IL-6 ablated the Th17 response and reversed costimulation blockade-resistant graft rejection. Neutralizing IL-4 in IFN-gamma(-/-) allograft recipients did not induce Th17, suggesting that T-bet, rather than IL-4 and IFN-gamma (known inhibitors of Th17), plays a critical role in negatively regulating Th17 in the transplant setting.

α‐Lactosylceramide as a Novel “Sugar‐Capped” CD1d Ligand for Natural Killer T Cells: Biased Cytokine Profile and Therapeutic Activities

The invariant natural killer T cells (iNKT) cells have emerged as an important regulator of immunity to infection, cancer, and autoimmune diseases. They can be activated by glycolipids that bind to CD1d. The most effective iNKT ligand reported to date is alpha-galactosylceramide (alpha-GalCer), which stimulates iNKT cells to secrete both Th-1 and Th-2 cytokines. Indiscriminate induction of both types of cytokines could limit the therapeutic potential of iNKT ligands, as Th-1 and Th-2 cytokines play different roles under physiological and pathological conditions. Therefore, a ligand with a biased cytokine-release profile would be highly desirable. Here, we report the synthesis and biological activity of alpha-lactosylceramide (alpha-LacCer). Our data demonstrate that alpha-LacCer can stimulate iNKT cells to proliferate and release cytokines, both in vitro and in vivo. Interestingly, while alpha-LacCer is approximately 1000-times less efficient than alpha-GalCer in inducing Th-1 cytokines, it is as potent as alpha-GalCer in the induction of Th-2 cytokines; therefore, alpha-LacCer is a novel compound that induces a biased cytokine release. Processing by beta-glycosidase was critical for alpha-LacCer activity. Moreover, in vivo experiments suggest that alpha-LacCer is at least as potent as alpha-GalCer in the treatment of tumors and experimental autoimmune encephalomyelitis.

Scottish Thoracic Society Meeting

Introduction: The key pathological features of asthma are eosinophilic airway inflammation, mucus hypersecretion and airway remodelling, mediated by Th2 cytokines (IL-4, IL-5, IL-13). IL-4 or IL-13 administered directly to the airways are sufficient to induce these pathological features independent of antigen (Grunig G et al, Science 1998; Wills-Karp et al, Science 1998). IL-33 is a novel cytokine which binds to the orphan ST2 receptor and induces Th2 cytokine expression (Schmitz et al, Immunity 2005). We hypothesised that IL-33 would be sufficient to induce eosinophilic airway inflammation, and may exacerbate antigen-specific allergic airway inflammation. Methods: The antigen-independent effect of IL-33 was assessed by administering PBS ± recombinant (r)IL-33 intranasally (i.n.) to BALB/c mice for 7 consecutive days. Bronchoalveolar lavage (BAL) was performed 24 h later. Differential cell counts were performed on cytopreps, and the concentration of BAL cytokines and chemokines determined by ELISA. Lungs were obtained for histological assessment. Allergic airway inflammation was induced in BALB/c mice by intraperitoneal (i.p.) sensitisation with ovalbumin (OVA) and alum on day 1, followed by i.n. challenge on days 9 and 11 with OVA ± rIL-33. Mice were analysed as above, and ST2 gene knockout mice were used to demonstrate the specificity of action of rIL-33. Results: rIL-33 induced marked eosinophilic inflammation (fig A). BAL eosinophils (data not shown), cytokines (IL-5 and IL-13, but not IL-4) and chemokines (eotaxin-1, eotaxin-2 and TARC) were increased (table). Airway challenge with OVA following sensitisation induced eosinophilic inflammation, which was increased markedly by rIL-33 (fig B), as were BAL eosinophils, cytokines and chemokines (table). IL-33 had no effect in ST2KO mice in either model. Conclusions: rIL-33 in the absence of antigen induced airway pathology very similar to that of experimental asthma. This was mediated by local induction of Th2 associated cytokines and chemokines, with the exception of IL-4, and was dependent on ST2 expression. In addition, IL-33 exacerbated allergic airway inflammation by a similar mechanism. Thus IL-33/ST2 represents an important mechanism of IL-4-independent airway inflammation, and represents a novel target for therapeutic intervention during both the initiation and maintenance phases of allergic asthma.

Linking of IL‐25 and SCF in allergic airway inflammation

IL‐25 can directly induce Th2 cytokines, IL‐4, 5 and 13, when injected in vivo in mice and has been linked to allergic responses. Using an established model of chronic allergen‐induced airway disease our studies identified elevated IL‐25 expression in the lung. When dispersed lung cells were activated in vitro with rIL‐25, a significant increase in Th2 cytokines was observed in cells from allergic lungs compared to lung cells from non‐allergic mice with the primary cell that was activated by IL‐25 was c‐kit+ (SCF receptor) cells. Our laboratory has previously demonstrated that neutralization of SCF significantly reduces disease, including AHR, airway remodeling and local Th2 cytokine production. The expression of IL‐25 was inhibited by anti‐SCF in allergic mice suggesting that SCF‐mediated pathways were linked to IL‐25. We found that when rIL‐25 was administered into the airways of allergic mice an exacerbation of disease was induced characterized by increased Th2 cytokines. The treatment of mice with anti‐SCF abrogated the response, further indicating a link of IL‐25‐induced disease with SCF. Furthermore, our studies identified that SCF can directly increase IL‐25 expression in the eosinophils and was dependent upon a PI3K‐induced pathway. Altogether, these studies establish a strong link between the developing allergic response, SCF‐mediated pathways, and IL‐25‐induced responses.

IL-13-Mediated Gender Difference in Susceptibility to Autoimmune Encephalomyelitis

Females tend to have stronger Th1-mediated immune responses and are more prone to develop autoimmune diseases, including multiple sclerosis. Macrophages are major effector cells capable of mediating or modulating immune responses in experimental autoimmune encephalomyelitis (EAE). IL-13 and estrogen have opposing roles on macrophages (the former enhancing and the latter inhibiting) in terms of MHC class II (MHC II) up-regulation and, thus, these factors might influence susceptibility to EAE differently in females vs males. In accordance with this hypothesis, females lacking IL-13 displayed lower incidence and milder EAE disease severity than males after immunization with myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide/CFA/pertussis toxin. Female IL-13 knockout (KO) mice with EAE consistently had reduced infiltration of CD11b(+) macrophages in the CNS along with significantly reduced expression of MHC II on these cells. Impaired MHC II expression was further corroborated upon LPS stimulation of female but not male bone marrow-derived CD11b(+) macrophages from IL-13KO mice, with restored expression after IL-13 pretreatment of female but not male macrophages. APCs from IL-13KO females induced less proliferation by MOG-35-55-reactive T cells, and splenocytes from MOG peptide-immunized females had lower expression of IL-12, IFN-gamma, MIP-2, and IFN-gamma-inducible protein 10 than males. In contrast, these splenocytes had higher expression of anti-inflammatory factors, IL-10, TGF-beta1, and FoxP3, a cytokine pattern typical of regulatory type II monocytes. These data suggest that the difference in EAE susceptibility in females is strongly influenced by gender-specific proinflammatory effects of IL-13, mediated in part through up-regulation of Th1-inducing cytokines and MHC II on CD11b(+) macrophages.

A mechanism for the initiation of allergen-induced T helper type 2 responses

Both metazoan parasites and simple protein allergens induce T helper type 2 (TH2) immune responses, but the mechanisms by which the innate immune system senses these stimuli are unknown. In addition, the cellular source of cytokines that control TH2 differentiation in vivo has not been defined. Here we showed that basophils were activated and recruited to the draining lymph nodes specifically in response to TH2-inducing allergen challenge. Furthermore, we demonstrate that the basophil was the accessory cell type required for TH2 induction in response to protease allergens. Finally, we show that basophils were directly activated by protease allergens and produced TH2-inducing cytokines, including interleukin 4 and thymic stromal lymphopoietin, which are involved in TH2 differentiation in vivo.

Protection of Mice against Mycobacterium tuberculosis Infection by Immunization with Aqueous Fraction of Triton X‐100‐soluble Cell Wall Proteins

AbstractThe aqueous fraction of Triton X‐100‐soluble proteins (TSP‐Aq) of Mycobacterium tuberculosis cell wall was reported to stimulate T‐cell responses in peripheral blood monocytes from tuberculosis (TB) patients and to induce Th1 cytokines, suggesting presence of protective antigens. In this study, therefore, we examined the protective efficacy of TSP‐Aq against M. tuberculosis infection in a mouse model. C57BL/6 mice were immunized with TSP‐Aq or culture filtrate proteins (CFP) mixed with incomplete Freund’s adjuvant or with BCG followed by i.v. challenge with M. tuberculosis H37Rv. TSP‐Aq induced strong interferon‐γ production by spleen cells, and mice immunized with TSP‐Aq antigens gave a significant reduction in M. tuberculosis CFU counts by 1.17–1.32 log10 CFU in the lungs and 1.31–2.08 log10 CFU in the spleen from 6 to 28 weeks. The degree of protection offered by TSP‐Aq was comparable to that of CFP and of the BCG vaccine. The results demonstrated that the TSP‐Aq antigens confer a significant level of protection against the growth of the organism in the lungs and spleen in a mouse model of TB and indicate that TSP contains major protective antigens of M. tuberculosis.

Overexpression of GATA-3 Protects against the Development of Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is mediated by a Th1 immune response. Transcription factor GATA binding protein-3 (GATA-3) is believed to be a key regulator of Th2 differentiation and thus might play regulatory roles in the pathogenesis of hypersensitivity pneumonitis (HP). We examined the effect of GATA-3 overexpression on the development of HP in mice. Wild-type C57BL/6 mice and GATA-3-overexpressing mice of the same background were used in this study. HP was induced by repeated exposure to Saccharopolyspora rectivirgula, the causative antigen of farmer's lung. Antigen exposure resulted in a marked inflammatory response with enhanced pulmonary expression of T-bet and the Th1 cytokine interferon (IFN)-gamma in wild-type mice. The degree of pulmonary inflammation was much less severe in GATA-3-overexpressing mice. The induction of T-bet and IFN-gamma genes was suppressed, but a significant induction of Th2 cytokines, including IL-5 and IL-13, was observed in the lungs of GATA-3-overexpressing mice after antigen exposure. Supplementation with recombinant IFN-gamma enhanced lung inflammatory responses in GATA-3-overexpressing mice to the level of wild-type mice. Because antigen-induced IFN-gamma production predominantly occurred in CD4+ T cells, nude mice were transferred with CD4+ T cells from either wild-type or GATA-3-overexpressing mice and subsequently exposed to antigen. Lung inflammatory responses were significantly lower in nude mice transferred with CD4+ T cells from GATA-3-overexpressing mice than in those with wild-type CD4+ T cells, with a reduction of lung IFN-gamma level. These results indicate that overexpression of GATA-3 attenuates the development of HP by correcting the Th1-polarizing condition.

In Vitro Th1 Cytokine‐Independent Th2 Suppressive Effects of Bifidobacteria

A comparison between 17 strains of lactic acid bacteria and 15 strains of bifidobacteria indicated that bifidobacteria induced significantly lower levels of interleukin-12 (IL-12) in murine splenic cells. The present study aims to evaluate the effect and mechanism of Bifidobacterium longum BB536, a probiotic strain, in suppressing antigen-induced Th2 immune response in vitro. BB536 suppressed immunoglobulin (Ig) E and IL-4 production by ovalbumin-sensitized splenic cells, but induction of Th1-inducing cytokine production, such as IL-12 and gamma interferon (IFN-gamma) tended to be lower compared with lactic acid bacteria. Neutralization with antibodies to IL-12, IFN-gamma, IL-10 and transforming growth factor beta indicated negative involvement of Th1-inducing cytokines and regulatory cytokines in the suppression of Th2 immune response by BB536, especially when treated at higher doses of BB536 (>10 microg cells/ml). Furthermore, BB536 induced the maturation of immature bone marrow-derived dendritic cells (BM-DCs), and suppressed antigen-induced IL-4 production mediated by BM-DCs. These results suggested that BB536 suppressed Th2 immune responses, partially independent of Th1-inducing cytokines and independent of regulatory cytokines, mediated by antigen-presenting cells such as dendritic cells.