Home About us Contact
|
Home About us Contact | ||
|
|
||
OVA
Kinds of OVA Terms modified by OVA Selected AbstractsChitin induces upregulation of B7-H1 on macrophages and inhibits T-cell proliferationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2010Claudia J. Wagner Abstract Chitin is a highly abundant glycopolymer, which serves as structural component in fungi, arthropods and crustaceans but is not synthesized by vertebrates. However, vertebrates express chitinases and chitinase-like proteins, some of which are induced by infection with helminths suggesting that chitinous structures may be targets of the immune system. The chitin-induced modulations of the innate and adaptive immune responses are not well understood. Here, we demonstrate that intranasal administration of OVA and chitin resulted in diminished T-cell expansion and Th2 polarization as compared with OVA administration alone. Chitin did not promote nor attenuate Th2 polarization in vitro. Chitin-exposed macrophages inhibited proliferation of CD4+ T cells in a cell,cell contact-dependent manner. Chitin induced upregulation of the inhibitory ligand B7-H1 (PD-L1) on macrophages independently of MyD88, TRIF, TLR2, TLR3, TLR4 and Stat6. Inhibition of T-cell proliferation was largely dependent on B7-H1, as the effect was not observed in cocultures with cells from B7-H1-deficient mice. [source] T-cell tolerance induced by repeated antigen stimulation: Selective loss of Foxp3, conventional CD4 T cells and induction of CD4 T-cell anergyEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2009Lena Eroukhmanoff Abstract Repeated immunization of mice with bacterial superantigens induces extensive deletion and anergy of reactive CD4 T cells. Here we report that the in vitro proliferation anergy of CD4 T cells from TCR transgenic mice immunized three times with staphylococcal enterotoxin B (SEB) (3× SEB) is partially due to an increased frequency of Foxp3+ CD4 T cells. Importantly, reduced number of conventional CD25, Foxp3, cells, rather than conversion of such cells to Foxp3+ cells, was the cause of that increase and was also seen in mice repeatedly immunized with OVA (3× OVA) and OVA,peptide (OVAp) (3× OVAp). Cell-transfer experiments revealed profound but transient anergy of CD4 T cells isolated from 3× OVAp and 3× SEB mice. However, the in vivo anergy was CD4 T-cell autonomous and independent of Foxp3+ Treg. Finally, proliferation of transferred CD4 T cells was inhibited in repeatedly immunized mice but inhibition was lost when transfer was delayed, despite the maintenance of elevated frequency of Foxp3+ cells. These data provide important implications for Foxp3+ cell-mediated tolerance in situations of repeated antigen exposure such as human persistent infections. [source] Neonatal exposure to staphylococcal superantigen improves induction of oral tolerance in a mouse model of airway allergyEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2009Anna Lönnqvist Abstract The hygiene hypothesis suggests that lack of microbial stimulation in early infancy may lead to allergy, but it has been difficult to identify particular protective microbial exposures. We have observed that infants colonised in the first week(s) of life with Staphylococcus aureus have lower risk of developing food allergy. As many S. aureus strains produce superantigens with T-cell stimulating properties, we here investigate whether neonatal mucosal exposure to superantigen could influence the capacity to develop oral tolerance and reduce sensitisation and allergy. BALB/c mice were exposed to staphylococcal enterotoxin A (SEA) as neonates and fed with OVA as adults, prior to sensitisation and i.n. OVA challenge. Our results show that SEA pre-treated mice are more efficiently tolerised by OVA feeding, as shown by lower lung-cell infiltration and antigen-specific IgE response in the SEA pre-treated mice, compared with sham-treated mice. This was not due to deletion or anergy of lymphocytes by SEA treatment, because the SEA pre-treated mice that were fed with PBS showed similar inflammatory response as the sham-treated PBS-fed mice. Our results suggest that strong T-cell activation in infancy conditions the mucosal immune system and promotes development of oral tolerance. [source] APRIL (TNFSF13) regulates collagen-induced arthritis, IL-17 production and Th2 responseEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2008Yanping Xiao Abstract A proliferation-inducing ligand (APRIL or TNFSF13) shares receptors with B-cell activation factor of the TNF family (BAFF) on B and T cells. Although much is known about the function of APRIL in B cells, its role in T cells remains unclear. Blocking both BAFF and APRIL suggested that BAFF and/or APRIL contributed to collagen-induced arthritis (CIA); however, the role of APRIL alone in CIA remained unresolved. We show here that, in vitro, our newly generated APRIL,/, mice exhibited increased T-cell proliferation, enhanced Th2 cytokine production under non-polarizing conditions, and augmented IL-13 and IL-17 production under Th2 polarizing conditions. Upon immunization with OVA and aluminum potassium sulfate, APRIL,/, mice responded with an increased antigen-specific IgG1 response. We also show that in APRIL,/, mice, the incidence of CIA was significantly reduced compared with WT mice in parallel with diminished levels of antigen-specific IgG2a autoantibody and IL-17 production. Our data indicate that APRIL plays an important role in the regulation of cytokine production and that APRIL-triggered signals contribute to arthritis. Blockade of APRIL thus may be a valuable adjunct in the treatment of rheumatoid arthritis. [source] Mast cell regulation of epithelial TSLP expression plays an important role in the development of allergic rhinitisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2008Masanori Miyata Abstract Epithelial cell-derived thymic stromal lymphopoietin (TSLP) is a master switch for asthma or atopic dermatitis by inducing a dendritic cell-mediated Th2-type allergic inflammation. Allergic rhinitis is also pathologically characterized by Th2-type allergic inflammation. This study demonstrates that mast cells regulate the epithelial TSLP expression in allergic rhinitis. TSLP expression was found to be up-regulated predominantly in the nasal epithelium in the ovalbumin (OVA)-sensitized and -nasally challenged mouse model of allergic rhinitis, which was abolished in mast cell-deficient WBB6F1-W/Wv in comparison with control WBB6F1-+/+ mice. Similarly, the epithelial TSLP expression was reduced in Fc receptor , chain (Fc,R)-deficient mice, where the high-affinity IgE receptor (Fc,RI) is not expressed on mast cells, in comparison with control C57BL/6 mice. Furthermore, the administration of neutralizing TSLP antibody during the challenge phase of OVA inhibited the development of allergic rhinitis. These results suggest that the direct stimulation of epithelial cells by antigens alone may not be sufficient to induce TSLP expression in the nasal epithelium, and that mast cell regulation of epithelial TSLP expression, possibly via Fc,RI, plays an important role in the development of allergic rhinitis. [source] Impairment of dendritic cell function by excretory-secretory products: A potential mechanism for nematode-induced immunosuppressionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2007Mariela Segura Abstract To determine whether helminth-derived products modulate dendritic cell (DC) function, we investigated the effects of excretory-secretory products (ES) and adult worm homogenate (AWH) derived from the gastrointestinal nematode Heligmosomoides polygyrus (Hp) on murine bone marrow-derived DC (BMDC). Compared to the TLR9 ligand CpG, Hp-derived products alone failed to induce DC activation. ES, but not AWH, inhibited BMDC cytokine and chemokine production and co-stimulatory molecule expression (CD40, CD86 and MHC class,II) induced by TLR ligation. TLR ligand-independent, PMA-induced DC activation was unaffected by ES. Recipients of ES-treated BMDC pulsed with OVA had suppressed Ab responses in vivo, irrespective of the Th1 or Th2 isotype affiliation, compared to recipients of control OVA-pulsed BMDC. Importantly, suppression occurred even in the presence of the potent type,1 adjuvant CpG. In contrast to untreated OVA-pulsed BMDC, ES-treated BMDC pulsed with OVA had reduced co-stimulatory molecule and cytokine expression. CD4+CD25+Foxp3, T cells, which secreted high IL-10 levels, were generated in co-cultures of OT-II OVA-specific TCR-transgenic CD4+ T cells and ES-treated BMDC. These IL-10-secreting T cells suppressed effector CD4+ T cell proliferation and IFN-, production, the latter effect mediated by an IL-10-dependent mechanism. Together, these results demonstrate that nematode ES impaired DC function and suppressed both Th1 and Th2 adaptive immune responses possibly by inducing regulatory T cells. [source] The Shiga toxin B-subunit targets antigen in vivo to dendritic cells and elicits anti-tumor immunityEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2006Benoit Vingert Abstract The non-toxic B-subunit of Shiga toxin (STxB) interacts with the glycolipid Gb3, which is preferentially expressed on dendritic cells (DC) and B cells. After administration of STxB chemically coupled to OVA (STxB-OVA) in mice, we showed that the immunodominant OVA257,264 peptide restricted by Kb molecules is specifically presented by CD11c+CD8,, DC, some of them displaying a mature phenotype. Using mice carrying a transgene encoding a diphtheria toxin receptor (DTR) under the control of the murine CD11c promoter, which allows inducible ablation of DC, we showed that DC are required for efficient priming of CTL after STxB-OVA vaccination. Immunization of mice with STxB-OVA induced OVA-specific CD8+ T cells detected ex vivo; these cells were long lasting, since they could be detected even 91,days after the last immunization and were composed of both central and memory T cells. Vaccination of mice with STxB-OVA and STxB coupled to E7, a protein derived from HPV16, inhibited tumor growth in prophylactic and therapeutic experiments. This effect was mainly mediated by CD8+ T cells. STxB therefore appears to be a powerful carrier directly targeting DC in vivo, resulting in a strong and durable CTL response associated with tumor protection. [source] The fate of heterologous CD4+ T,cells during Leishmania donovani infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2005Rosalind Polley Abstract Little is currently understood about the consequences of chronic parasitic infection for the fate of memory CD4+ T,cells that recognize heterologous antigens, e.g. resulting from prior infections or vaccination. Here, we address how Leishmania donovani infection affected the fate of non-cross-reactive (OVA)-specific memory CD4+ T,cells. DO11 cells were adoptively transferred into naive recipient mice, which were then immunized to generate memory DO11 cells. After 6,weeks, mice were infected with L. donovani and the fate of DO11 cells was determined. L. donovani infection stimulated an approximately threefold expansion in the total number of CD4+ T,cells and DO11 cells, compared to that observed in uninfected mice. DO11 T,cells were more actively dividing in infected mice, as judged by 5-bromo-2, deoxyuridine labeling, whereas their rate of apoptosis in control and infected mice was identical. Both CD45RBhiCD44lo naive T,cells and to a greater extent CD45RBloCD44hi memory DO11 cells increased in number in the spleens of infected mice, whereas no changes occurred to DO11 cell number or phenotype in the draining lymph nodes. These data indicate that heterologous CD4+ T,cells may actively divide during chronic infectious diseases, with important implications for how chronic infection may impact on heterologous immunity. [source] A CIITA-independent pathway that promotes expression of endogenous rather than exogenous peptides in immune-privileged sitesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2004Carolina Abstract A CIITA-independent pathway of MHC class II expression has been found in the eye and the brain, both immune-privileged sites. Although corneal endothelial cells were unable to express MHC class,II in response to IFN-, alone, these cells readily expressed MHC class,II molecules via a CIITA-independent pathway when triggered by simultaneous exposure to IFN-, and TNF-,. CIITA-independent expression of MHCclass,II molecules enabled corneal endothelial cells to present cytosolic, but not endosomal, ovalbumin (OVA) to OVA-primed T,cells. To determine whether CIITA-independentexpression of MHC class,II is relevant in vivo, minor,H-only-incompatible corneal allografts prepared from CIITA knockout (KO) mice, MHC class,II KO mice or wild-type donors were placed ineyes of normal mice. Cornea allografts from wild-type and CIITA KO mice suffered similar rejection fates, whereas far fewer class,II-deficient corneas were rejected. In addition, MHC class,II-bearing macrophages were observed in cuprizone-induced inflammatory and demyelinating brain lesions of CIITA KO mice. We conclude that class,II expression via the CIITA-independent pathway enhances the vulnerability to rejection of corneal grafts expressing minor antigens. The potential relevance of CIITA-independent MHC class,II expression at immune-privileged sites is discussed in relation to tolerance to strong autoantigens. [source] Characterization of HLA DR3/DQ2 transgenic mice: a potential humanized animal model for autoimmune disease studiesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2003Dan Chen Abstract Linkage studies indicate close associations of certain HLA alleles with autoimmune diseases. To better understand how specific HLA alleles are related to disease pathogenesis, we have generated an HLA DR3/DQ2 transgenic mouse utilizing a 550-kb yeast artificial chromosome (YAC) construct containing the complete DR,, DR,1, DR,3, DQ,, and DQ, regions. The transgenic mouse (4D1/C2D) in an I-A,o background appears healthy with no signs of autoimmune diseases. Lymphoid tissues as well as CD4+ T cells develop normally. Characterization of the transgene expression demonstrates that ,90% of B cells express high levels of DR3 and 50,70% of B cells express DQ2. CD11c+ dendritic cells express high levels of DR and DQ. Approximately12,18% of resting T cells are positive for DR expression, and further up-regulation to 40,50% expression is seen upon activation with anti-CD3/anti-CD28 mAb. These results suggest that the transgenic construct confers a high fidelity to the normal human temporal and spatial expression profile. Analysis of T cell receptor repertoire in transgenic mice confirms that DR3/DQ2 are able to mediate thymic selection. Furthermore, transgenic mice respond to a DR3-restricted antigen, demonstrating antigen processing and presentation by antigen-presenting cells (APC). Purified T cells from ovalbumin (OVA)-immunized 4D1 mice respond to human APC co-cultured with OVA, suggesting appropriate antigen/DR3 or DQ2 recognition by murine T cells. Immunoglobulin isotype switching is also observed, indicating functional T-B cognate interactions. Thus, the DR3/DQ2 transgenic mouse has normal lymphoid development and functionality that are mediated by HLA transgenes and can be used to investigate HLA-associated immunological questions. [source] NKT cells are dispensable in the induction of oral tolerance but are indispensable in the abrogation of oral tolerance by prostaglandin EEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2003Ryotaro Ishimitsu Abstract NK1.1+ ,,, T cells (NKT cells) regulate the Th1/Th2 balance in response to dietary Ag, which may be involved in regulation of oral tolerance. OVA-specific IgE and IgG1 Ab levels were significantly lower following an i.p. injection of OVA (in CFA) in C57BL/6 mice orally given a single, high dose (25,mg) of OVA than in those orally given PBS. The oral tolerance was normally induced in J,281,/, mice which lack V,14+ NKT cells, suggesting that NKT cells are dispensable for induction of oral tolerance. Treatment with PGE1 or PGE2 abrogated the oral tolerance in J,281+/+ mice; this abrogation was accompanied by an OVA-specific Th2-dominant response. The abrogation of oral tolerance by PGE1 was not evident in J,281,/, mice. Treatment with PGE1 induced an early increase in IL-4 production by liver NKT cells in normal mice and neutralization of the early IL-4 by administration of anti-IL-4 mAb abolished PGE1 -induced abrogation of oral tolerance. These results suggest that liver NKT cells producing IL-4 are responsible for the down-regulation of oral tolerance that is caused by the PGE molecules. [source] CNS-irrelevant T-cells enter the brain, cause blood,brain barrier disruption but no glial pathologyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2007Alina Smorodchenko Abstract Invasion of autoreactive T-cells and alterations of the blood,brain barrier (BBB) represent early pathological manifestations of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). Non-CNS-specific T-cells are also capable of entering the CNS. However, studies investigating the spatial pattern of BBB alterations as well as the exact localization and neuropathological consequences of transferred non-CNS-specific cells have been thus far lacking. Here, we used magnetic resonance imaging and multiphoton microscopy, as well as histochemical and high-precision unbiased stereological analyses to compare T-cell transmigration, localization, persistence, relation to BBB disruption and subsequent effects on CNS tissue in a model of T-cell transfer of ovalbumin (OVA)- and proteolipid protein (PLP)-specific T-cells. BBB alterations were present in both EAE-mice and mice transferred with OVA-specific T-cells. In the latter case, BBB alterations were less pronounced, but the pattern of initial cell migration into the CNS was similar for both PLP- and OVA-specific cells [mean (SEM), 95 × 103 (7.6 × 103) and 88 × 103 (18 × 103), respectively]. Increased microglial cell density, astrogliosis and demyelination were, however, observed exclusively in the brain of EAE-mice. While mice transferred with non-neural-specific cells showed similar levels of rhodamine-dextran extravasation in susceptible brain regions, EAE-mice presented huge BBB disruption in brainstem and moderate leakage in cerebellum. This suggests that antigen specificity and not the absolute number of infiltrating cells determine the magnitude of BBB disruption and glial pathology. [source] NKT cells play critical roles in the induction of oral tolerance by inducing regulatory T cells producing IL-10 and transforming growth factor ,, and by clonally deleting antigen-specific T cellsIMMUNOLOGY, Issue 1 2006Hyun Jung Kim Summary Oral tolerance is the systemic unresponsiveness induced by orally administered proteins. To explore the roles of natural killer T (NKT) cells in oral tolerance, we induced oral tolerance to ovalbumin (OVA) in NKT cell-deficient mice. In CD1d,/, mice, the induction of tolerance to orally administered high- or low-dose OVA was impaired. Dendritic cells (DCs) in the Peyer's patches (PPs) of CD1d,/, mice fed OVA showed high expression of major histocompatibility complex (MHC) class II and B7 molecules, whereas DCs of control mice fed OVA expressed low levels of these molecules. The adoptive transfer of NKT cells restored oral tolerance and induction of tolerogenic DCs in the PPs and spleens of CD1d,/, mice. Moreover, interleukin (IL)-10 and transforming growth factor (TGF)-,1 production in vitro were reduced in cells from the spleen and PPs of CD1d,/, mice compared with those of control mice fed OVA. The numbers of OVA-specific CD4+ KJ1-26+ T cells were significantly reduced in the PPs and spleens of DO11·10 mice fed OVA. In contrast, OVA-specific CD4+ KJ1-26+ T cells were not deleted in the PPs or spleens of DO11·10 CD1d,/, mice. In conclusion, NKT cells were found to play an indispensable role in oral tolerance by inducing regulatory T cells, and clonally deleting antigen-specific CD4+ T cells. [source] A novel model of sensitization and oral tolerance to peanut proteinIMMUNOLOGY, Issue 3 2004Jessica Strid Summary The prevalence of food allergic diseases is rising and poses an increasing clinical problem. Peanut allergy affects around 1% of the population and is a common food allergy associated with severe clinical manifestations. The exact route of primary sensitization is unknown although the gastrointestinal immune system is likely to play an important role. Exposure of the gastrointestinal tract to soluble antigens normally leads to a state of antigen-specific systemic hyporesponsiveness (oral tolerance). A deviation from this process is thought to be responsible for food-allergic diseases. In this study, we have developed a murine model to investigate immunoregulatory processes after ingestion of peanut protein and compared this to a model of oral tolerance to chicken egg ovalbumin (OVA). We demonstrate that oral tolerance induction is highly dose dependent and differs for the allergenic proteins peanut and OVA. Tolerance to peanut requires a significantly higher oral dose than tolerance to OVA. Low doses of peanut are more likely to induce oral sensitization and increased production of interleukin-4 and specific immunoglobulin E upon challenge. When tolerance is induced both T helper 1 and 2 responses are suppressed. These results show that oral tolerance to peanut can be induced experimentally but that peanut proteins have a potent sensitizing effect. This model can now be used to define regulatory mechanisms following oral exposure to allergenic proteins on local, mucosal and systemic immunity and to investigate the immunomodulating effects of non-oral routes of allergen exposure on the development of allergic sensitization to peanut and other food allergens. [source] Interleukin-15 is not required for the induction or maintenance of orally induced peripheral toleranceIMMUNOLOGY, Issue 3 2004Owain R. Millington Summary Orally induced tolerance is a physiologically relevant form of peripheral tolerance, which is believed to be important for the prevention of pathological immune responses in the gut. Of several mechanisms proposed to mediate oral tolerance, one that has received much attention recently is the concept of regulatory CD4+ T cells. As recent studies have suggested that interleukin (IL)-15 may be important for the differentiation and maintenance of regulatory CD4+ T cells, we have examined the role of IL-15 in oral tolerance, using a soluble form of the IL-15 receptor (sIL-15R) which blocks the biological effects of IL-15 in vivo. Oral tolerance induced by feeding mice ovalbumin (OVA) in a low-dose regimen believed to induce regulatory T cell activity was not affected by the administration of sIL-15R during either the induction or maintenance phase of tolerance. Thus, oral tolerance does not involve an IL-15-dependent mechanism. [source] Interleukin-18 plays a role in both the alum-induced T helper 2 response and the T helper 1 response induced by alum-adsorbed interleukin-12IMMUNOLOGY, Issue 2 2003Kevin G. J. Pollock Summary Previous studies have shown that the antigen-specific T helper 2 (Th2) response induced by alum adjuvants is interleukin (IL)-4 independent. As a role for IL-18 in Th2 induction has recently been described, in addition to its role in enhancing Th1 responses, we have studied the Th2 response induced by ovalbumin (OVA) adsorbed to alum in wild-type and IL-18-deficient mice. Our results indicate that while endogenous IL-18 facilitates alum-induced IL-4 production, OVA-specific immunoglobulin G1 (IgG1) and IgE production remain unaffected. Furthermore, antigen-specific Th1 responses induced with alum/IL-12-adsorbed OVA were demonstrated to be highly IL-18 dependent. Despite these observations, injection of BALB/c mice with exogenous IL-18 adsorbed to alum/OVA did not alter IL-4 or interferon-, production by T cells and had little effect on the relative production of IgG1/IgG2a antibody subclasses compared with alum/OVA inoculated mice. However, the previously described synergism between IL-12 and IL-18 in Th1 induction was evident as the Th1-promoting activity of alum/IL-12 against adsorbed OVA was greatly augmented by the coadministration of IL-18. These results indicate that while alum-induced IL-18 can facilitate Th2 induction, the addition of exogenous IL-18 cannot further enhance the alum-induced Th2 response. [source] Mechanism of antigen presentation after hypertonic loading of soluble antigensIMMUNOLOGY, Issue 4 2002Georg A. Enders Summary Hypertonic loading of proteins into cells has been used to introduce soluble proteins into the major histocompatibility complex class I pathway of antigen presentation followed by cytotoxic T-lymphocyte (CTL) induction. The precise mechanism for this pathway is not completely understood. The antigen is either processed and presented by/on the same cell or by professional antigen-presenting cells (APC) after taking up the antigen from damaged or apoptotic cells. After loading labelled ovalbumin (OVA), it could be co-precipitated with the proteasome complex, supporting the role of this pathway for antigen processing. The processing speed however, appeared to be slow since intact OVA could be detected inside the cells even after 18 hr. This corresponded well with the processing of OVA by isolated proteasomes. On the other hand, enough peptides for recognition of target cells by CTLs were generated in this reaction. One reason for the low level of processing might be that hypertonic loading may damage the cells and inhibit direct processing. In fact, at least 50% of the cells became positive for Annexin V binding after hypertonic loading which indicates severe membrane alterations usually associated with the progress of apoptosis. Annexin V binds to phosphatidylserine residues which also serve as ligand for CD36 expressed on monocytes and some immature dendritic cells. This may direct the phagocytic pathway to hypertonically loaded cells and thus enable professional APCs to present OVA-peptides. Therefore, in addition to the direct processing of OVA, CTLs can be primed by professional APC after uptake of apoptotic, OVA-loaded cells. [source] An investigation of the factors controlling the adsorption of protein antigens to anionic PLG microparticlesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2005James Chesko Abstract This work examines physico-chemical properties influencing protein adsorption to anionic PLG microparticles and demonstrates the ability to bind and release vaccine antigens over a range of loads, pH values, and ionic strengths. Poly(lactide-co-glycolide) microparticles were synthesized by a w/o/w emulsification method in the presence of the anionic surfactant DSS (dioctyl sodium sulfosuccinate). Ovalbumin (OVA), carbonic anhydrase (CAN), lysozyme (LYZ), lactic acid dehydrogenase, bovine serum albumin (BSA), an HIV envelope glyocoprotein, and a Neisseria meningitidis B protein were adsorbed to the PLG microparticles, with binding efficiency, initial release and zeta potentials measured. Protein (antigen) binding to PLG microparticles was influenced by both electrostatic interaction and other mechanisms such as van der Waals forces. The protein binding capacity was directly proportional to the available surface area and may have a practical upper limit imposed by the formation of a complete protein monolayer as suggested by AFM images. The protein affinity for the PLG surface depended strongly on the isoelectric point (pI) and electrostatic forces, but also showed contributions from nonCoulombic interactions. Protein antigens were adsorbed on anionic PLG microparticles with varying degrees of efficiency under different conditions such as pH and ionic strength. Observable changes in zeta potentials and morphology suggest the formation of a surface monolayer. Antigen binding and release occur through a combination of electrostatic and van der Waals interactions occurring at the polymer-solution interface. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2510-2519, 2005 [source] The anti-allergenic properties of milk kefir and soymilk kefir and their beneficial effects on the intestinal microfloraJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2006Je-Ruei Liu Abstract Food allergy is now recognized as a worldwide problem, and like other atopic disorders its incidence appears to be increasing. Kefir is reported to possess the ability to reduce intestinal permeation of food antigens; however, no experimental study has clearly evaluated the relationships between kefir consumption, allergen-specific IgE response, and intestinal microflora. The aim of this study was to evaluate the effect of oral consumption of milk kefir and soymilk kefir on in vivo IgE and IgG1 production induced by ovalbumin (OVA) in mice. The effects of kefir administration on the murine intestinal microflora were also examined. Oral administration of milk kefir and soymilk kefir for 28 days significantly increased the fecal populations of bifidobacteria and lactobacilli, while it significantly decreased those of Clostridium perfringens. Milk kefir and soymilk kefir also significantly decreased the serum OVA-specific IgE and IgG1 levels for both groups, but not those of the IgG2a analogues. Consumption of milk kefir and soymilk kefir suppressed the IgE and IgG1 responses and altered the intestinal microflora in our supplemented group, suggesting that milk kefir and soymilk kefir may be considered among the more promising food components in terms of preventing food allergy and enhancement of mucosal resistance to gastrointestinal pathogen infection. Copyright © 2006 Society of Chemical Industry [source] A viral PAMP double-stranded RNA induces allergen-specific Th17 cell response in the airways which is dependent on VEGF and IL-6ALLERGY, Issue 10 2010J.-P. Choi To cite this article: Choi J-P, Kim Y-S, Tae Y-M, Choi E-J, Hong B-S, Jeon SG, Gho YS, Zhu Z, Kim Y-K. A viral PAMP double-stranded RNA induces allergen-specific Th17 cell response in the airways which is dependent on VEGF and IL-6. Allergy 2010; 65: 1322,1330. Abstract Background:, Innate immune response by a viral pathogen-associated molecular pattern dsRNA modulates the subsequent development of adaptive immune responses. Although virus-associated asthma is characterized by noneosinophilic inflammation, the role of Th17 cell response in the development of virus-associated asthma is still unknown. Objective:, To evaluate the role of the Th17 cell response and its underlying polarizing mechanisms in the development of an experimental virus-associated asthma. Methods:, An experimental virus-associated asthma was created via airway sensitization with ovalbumin (OVA, 75 ,g) and a low (0.1 ,g) or a high (10 ,g) doses of synthetic dsRNA [polyinosine,polycytidylic acid; poly(I:C)]. Transgenic (IL-17-, IL-6-deficient mice) and pharmacologic [a vascular endothelial growth factor receptor (VEGFR) inhibitor] approaches were used to evaluate the roles of Th17 cell responses. Results:, After cosensitization with OVA and low-dose poly(I:C), but not with high-dose poly(I:C), inflammation scores after allergen challenge were lower in IL-17-deficient mice than in wild-type (WT) mice. Moreover, inflammation enhanced by low-dose poly(I:C), but not by high-dose poly(I:C), was impaired in IL-6-deficient mice; this phenotype was accompanied by the down-regulation of IL-17 production from T cells from both lymph nodes and lung tissues. Airway exposure of low-dose poly(I:C) enhanced the production of VEGF and IL-6, and the production of IL-6 was blocked by treatment with a VEGFR inhibitor (SU5416). Moreover, the allergen-specific Th17 cell response and subsequent inflammation in the low-dose poly(I:C) model were impaired by the VEGFR inhibitor treatment during sensitization. Conclusions:, Airway exposure of low-level dsRNA induces an allergen-specific Th17 cell response, which is mainly dependent on VEGF and IL-6. [source] Conversion of Th17-type into Th2-type inflammation by acetyl salicylic acid via the adenosine and uric acid pathway in the lungALLERGY, Issue 9 2010H.-G. Moon To cite this article: Moon H-G, Tae Y-M, Kim Y-S, Gyu Jeon S, Oh S-Y, Song Gho Y, Zhu Z, Kim Y-K. Conversion of Th17-type into Th2-type inflammation by acetyl salicylic acid via the adenosine and uric acid pathway in the lung. Allergy 2010; 65: 1093,1103. Abstract Background:, Allergen-specific T-cell responses orchestrate airway inflammation, which is a characteristic of asthma. Recent evidence suggests that noneosinophilic asthma can be developed by mixed Th1 and Th17 cell responses when exposed to lipopolysaccharide (LPS)-containing allergens. Objective:, To evaluate the therapeutic or adverse effects of acetyl salicylic acid (ASA) on the expression of Th1-type and Th17-type inflammation induced by airway exposure to LPS-containing allergens. Methods:, Th1 + Th17 asthma and Th2 asthma mouse models were generated by intranasal sensitization with ovalbumin (OVA) and LPS and intraperitoneal sensitization with OVA and alum, respectively. Therapeutic or adverse effects were evaluated after allergen challenge using pharmacologic and transgenic approaches. Results:, Lung infiltration of eosinophils was enhanced in OVA/LPS-sensitized mice by ASA treatment, which was accompanied by the enhanced production of eotaxin. These changes were associated with the down-regulation of Th17 cell response, which was partly dependent on adenosine receptor A1 and A3 subtypes, but up-regulation of allergen-specific IL-13 production from T cells. Lung inflammation induced by LPS-containing allergen was markedly reduced in IL-13-deficient mice in the context of ASA treatment, but not without ASA. Meanwhile, adenosine levels in the lung were enhanced by ASA treatment. Moreover, lung infiltration of eosinophils induced by ASA treatment was reversed by co-treatment of a xanthine oxidase inhibitor (allopurinol). Conclusion:, These findings suggest that ASA changes Th17-type into Th2-type inflammation mainly via the adenosine and uric acid metabolic pathway in the lung. [source] Hypersensitivity and oral tolerance in the absence of a secretory immune systemALLERGY, Issue 5 2010M. R. Karlsson To cite this article: Karlsson M-R, Johansen F-E, Kahu H, Macpherson A, Brandtzaeg P. Hypersensitivity and oral tolerance in the absence of a secretory immune system. Allergy 2010; 65: 561,570. Abstract Background:, Mucosal immunity protects the epithelial barrier by immune exclusion of foreign antigens and by anti-inflammatory tolerance mechanisms, but there is a continuing debate about the role of secretory immunoglobulins (SIgs), particularly SIgA, in the protection against allergy and other inflammatory diseases. Lack of secretory antibodies may cause immune dysfunction and affect mucosally induced (oral) tolerance against food antigens. Methods:, We used polymeric Ig receptor (pIgR) knockout (KO) mice, which cannot export SIgA or SIgM, to study oral tolerance induction by ovalbumin (OVA) feeding and for parenteral antigen sensitization in the same animal. Results:, Remarkable systemic hyperreactivity was observed in pIgR KO mice, as 50% died after intradermal OVA challenge, which was not seen in similarly sensitized and challenged wild-type (WT) mice. Oral tolerance induced by OVA completely protected the sensitized pIgR KO mice against anaphylaxis and suppressed antibody levels (particularly IgG1) as well as delayed-type hypersensitivity (DTH) to OVA. Delayed-type hypersensitivity to a bystander antigen, human serum albumin, was also suppressed and T-cell proliferation against OVA in vitro was reduced in tolerized compared with non-tolerized pIgR KO mice. This effect was largely mediated by CD25+ T cells. Adoptive transfer of splenic putative regulatory T cells (CD4+ CD25+) obtained from OVA-fed pIgR KO mice to naďve WT mice mediated suppression of DTH against OVA after sensitization of the recipients. Conclusion:, Compensatory regulatory T-cell function becomes critical in pIgR-deficient mice to avoid the potentially catastrophic effects of systemic immune hyperreactivity, presumably resulting from defective secretory antibody-mediated immune exclusion of microbial components. [source] Targeting the allergen to oral dendritic cells with mucoadhesive chitosan particles enhances tolerance inductionALLERGY, Issue 7 2009N. Saint-Lu Background:, Sublingual immunotherapy (SLIT) efficacy could be improved by formulations facilitating allergen contact with the oral mucosa and uptake by antigen-presenting cells (APCs). Methods:, Two types of chitosan microparticles, differing in size and surface charge, were tested in vitro for their capacity to improve antigen uptake and presentation by murine bone marrow-derived dendritic cells (BMDCs) or purified oral APCs. T-cell priming in cervical lymph nodes (LNs) was assessed by intravenous transfer of carboxyfluorescein diacetate succinimidyl ester-labelled ovalbumin (OVA)-specific CD4+ T cells and flow cytometry analysis. Ovalbumin-sensitized BALB/c mice were treated sublingually with soluble or chitosan-formulated OVA twice a week for 2 months. Airway hyperresponsiveness (AHR), lung inflammation and T-cell responses in cervical and mediastinal LNs were assessed by whole-body plethysmography, lung histology and Cytometric Bead Array technology, respectively. Results:, Only a mucoadhesive (i.e. highly positively charged) and microparticulate form of chitosan enhances OVA uptake, processing and presentation by murine BMDCs and oral APCs. Targeting OVA to dendritic cells with this formulation increases specific T-cell proliferation and IFN-,/IL-10 secretion in vitro, as well as T-cell priming in cervical LNs in vivo. Sublingual administration of such chitosan-formulated OVA particles enhances tolerance induction in mice with established asthma, with a dramatic reduction of both AHR, lung inflammation, eosinophil numbers in bronchoalveolar lavages, as well as antigen-specific Th2 responses in mediastinal LNs. Conclusions:, Mucoadhesive chitosan microparticles represent a valid formulation for sublingual allergy vaccines. [source] Aluminium per se and in the anti-acid drug sucralfate promotes sensitization via the oral routeALLERGY, Issue 6 2009R. Brunner Background:, Aluminium (ALUM) is used as experimental and clinical adjuvant for parenteral vaccine formulation. It is also contained in anti-acid drugs like sucralfate (SUC). These anti-acids have been shown to cause sensitization to food proteins via elevation of the gastric pH. The aim of this study was to assess the oral adjuvant properties of ALUM, alone or contained in SUC, in a BALB/c mouse model. Methods:, Mice were fed SUC plus ovalbumin (OVA) and compared with groups where ALUM or proton pump inhibitors (PPI) were applied as adjuvants. The humoral and cellular immune responses were assessed on antigen-specific antibody and cytokine levels. The in vivo relevance was investigated in skin tests. Results:, The highest OVA-specific immunoglobulin G1 (IgG1) and IgE antibody levels were found in mice fed with OVA/SUC, followed by OVA/ALUM-treated animals, indicating a T helper 2 (Th2) shift in both groups. Antibody levels in other groups revealed lower (OVA/PPI-group) or baseline levels (control groups). Positive skin tests confirmed an allergic response in anti-acid or adjuvant-treated animals. Conclusions:, Our data show for the first time that ALUM acts as a Th2-adjuvant via the oral route. This suggests that orally applied SUC leads to an enhanced risk for food allergy, not only by inhibiting peptic digestion but also by acting as a Th2-adjuvant by its ALUM content. [source] Inhibition of allergic responses by CD40 gene silencingALLERGY, Issue 3 2009M. Suzuki Background:, Gene silencing using small interfering RNA (siRNA) is a potent method of specifically knocking down molecular targets. Small interfering RNA is therapeutically promising, however, treatment of allergic diseases with siRNA has not been explored in vivo. The aim of this study was to evaluate therapeutic effects of CD40 siRNA on inhibition of allergic responses. Methods:, Mice sensitized with ovalbumin (OVA) and alum were treated with CD40 siRNA, scrambled siRNA, or phosphate buffer saline (PBS) alone, and then challenged intranasally with OVA. Results:, A significant reduction in nasal allergic symptoms was observed in the CD40 siRNA treated OVA-allergic mice compared to the controls of scrambled siRNA and PBS alone, which is correlated with the decrease of local eosinophil accumulation. CD40 siRNA treatment knocked down CD40 expression on dendritic cells (DCs) in vivo and impaired their antigen presenting function. Treatment with CD40 siRNA resulted in inhibition of OVA-specific T cell response and decrease of interleukin-4 (IL-4), IL-5, and interferon-, production from T cells stimulated with OVA. Administration of CD40 siRNA also suppressed CD40 expression on B cells, resulting in down-regulation of OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a levels. Additionally, increased regulatory T cells were observed in the CD40 siRNA treated mice. Conclusions:, The present study demonstrates a novel therapeutic use for siRNA in allergy. CD40 siRNA attenuated allergy through inhibition of DC and B cell functions and generation of regulatory T (Treg) cells. [source] Tryptophan catabolites regulate mucosal sensitization to ovalbumin in respiratory airwaysALLERGY, Issue 3 2009S. O. Odemuyiwa Background:, Indoleamine 2,3 dioxygenase (IDO), the rate-limiting enzyme in tryptophan catabolism, is important in generating tolerance at the foetal,maternal interface. Studies using 1-methyl-tryptophan (1-MT), the specific inhibitor of IDO, showed that this enzyme is important in interferon-gamma (IFN-,)-dependent inhibition of allergic inflammation in the respiratory airway during immunotherapy. Aims of study:, We investigated the role of IDO in the development of allergic sensitization, leading to allergic inflammation and airway hyper-responsiveness (AHR). Methods:, We used a mouse model to generate mucosal tolerance to lipopolysaccharide-free ovalbumin (OVA) following repeated intranasal inoculation of OVA over a 3-day period. We tested the successful induction of tolerance by subsequent intraperitoneal (i.p.) sensitization followed by intranasal challenge with OVA. A slow-release pellet of 1-MT implanted into mice was used to block IDO activity prior to repeated intranasal inoculation of OVA. We measured T-cell proliferation in response to OVA, determined airway inflammation, and measured AHR to intranasal methacholine to investigate the role of IDO in sensitization to OVA. Results:, Repeated intranasal administration of OVA generated tolerance and prevented a subsequent sensitization to OVA via the i.p. route. This response was inhibited in mice receiving a slow-release pellet of 1-MT. However, we successfully reconstituted tolerance in mice receiving 1-MT following intra-peritoneal injection of a mixture of kynurenine and hydroxyanthranilic acid. Conclusion:, Our data suggest that, in addition to their role in IFN-,-mediated inhibition of allergic airway inflammation, products of tryptophan catabolism play an important role in the prevention of sensitization to potential allergens in the respiratory airway. [source] Influence of a cocoa-enriched diet on specific immune response in ovalbumin-sensitized ratsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 3 2009Teresa Pérez-Berezo Abstract Previous studies in young rats have reported the impact of 3 weeks of high cocoa intake on healthy immune status. The present article describes the effects of a longer-term cocoa-enriched diet (9 weeks) on the specific immune response to ovalbumin (OVA) in adult Wistar rats. At 4 weeks after immunization, control rats produced anti-OVA antibodies, which, according their amount and isotype, were arranged as follows: IgG1 > IgG2a > IgM > IgG2b > IgG2c. Both cocoa diets studied (4% and 10%) down-modulated OVA-specific antibody levels of IgG1 (main subclass associated with the Th2 immune response in rats), IgG2a, IgG2c and IgM isotypes. Conversely, cocoa-fed rats presented equal or higher levels of anti-OVA IgG2b antibodies (subclass linked to the Th1 response). Spleen and lymph node cells from OVA-immunized control and cocoa-fed animals proliferated similarly under OVA stimulation. However, spleen cells from cocoa-fed animals showed decreased interleukin-4 secretion (main Th2 cytokine), and lymph node cells from the same rats displayed higher interferon-, secretion (main Th1 cytokine). These changes were accompanied by a reduction in the number of anti-OVA IgG-secreting cells in spleen. In conclusion, cocoa diets induced attenuation of antibody synthesis that may be attributable to specific down-regulation of the Th2 immune response. [source] Mucosal mast cells mediate motor response induced by chronic oral exposure to ovalbumin in the rat gastrointestinal tractNEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2010E. Traver Abstract, We previously demonstrated that oral chronic exposure to ovalbumin (OVA) causes intestinal hypermotility in Sprague-Dawley rats. In this study, the objective was to determine the mechanism of action of OVA and the role of mucosal mast cells in the regulation of motor activity in this model. Rats were orally exposed to OVA during 6 weeks. Intestinal mucosal mast cells (IMMCs) were counted and rat mast cell protease II (RMCPII) measured in duodenum, jejunum, ileum and colon. Anti-OVA IgE, IgG, and IL-4 were measured in serum. Eosinophils and IgE+ cells were counted in jejunum. In an additional study rats were treated with the mast cell stabilizer ketotifen and mast cell number, RMCPII concentration and motor activity in vitro were evaluated. OVA exposed rats showed an increase in mucosal mast cell number and in RMCPII content in small intestine and colon. However, variables of a Th2 type response were not affected by exposure to OVA: (i) neither OVA specific IgE nor IgG were found; (ii) IL-4 did not increase and, (iii) the number of eosinophils and IgE+ cells was identical in the exposed and unexposed groups. These results brought us to hypothesize a possible non-Ig-mediated action of OVA on mast cells. Ketotifen significantly diminished the response to OVA: Ketotifen reduced the number of mast cells and the RMCPII content and blocked increased intestinal contractility. In addition ketotifen modified motor response in both OVA exposed and unexposed animals giving evidence of the importance of mast cells in intestine motor activity driving. [source] Pharmacology and immunological actions of a herbal medicine ASHMITM on allergic asthmaPHYTOTHERAPY RESEARCH, Issue 7 2010Tengfei Zhang Abstract Allergic asthma is a chronic and progressive inflammatory disease for which there is no satisfactory treatment. Studies reported tolerability and efficacy of an anti-asthma herbal medicine intervention (ASHMI) for asthma patients, developed from traditional Chinese medicine. To investigate the pharmacological actions of ASHMI on early- and late-phase airway responses (EAR and LAR), Ovalbumin (OVA)-sensitized mice received 6 weeks of ASHMI treatment beginning 24,h following the first intratracheal OVA challenge. EAR were determined 30,min following the fourth challenge and LAR 48,h following the last challenge. ASHMI effects on cytokine secretion, murine tracheal ring contraction and human bronchial smooth muscle cell prostaglandin (PG) production were also determined. ASHMI abolished EAR, which was associated with significantly reduced histamine, leukotriene C4, and OVA-specific IgE levels, as well as LAR, which was associated with significantly reduced bronchoalveolar lavage fluid (BALF) eosinophils, decreased airway remodeling, and lower Th2 cytokine levels in BALF and splenocyte cultures. Furthermore, ASHMI inhibited contraction of murine tracheal rings and increased production of the potent smooth muscle relaxer PGI2. ASHMI abrogation of allergic airway responses is associated with broad effects on asthma pathological mechanisms. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effects of Th2 pulmonary inflammation in mice with bleomycin-induced pulmonary fibrosisRESPIROLOGY, Issue 6 2008Hirokuni HIRATA Background and objective: Leucocytes, especially lymphocytes and neutrophils, as well as alveolar macrophages, that infiltrate into the lung are involved in the development of pulmonary fibrosis. However, the role of T helper (Th)2-type inflammation, mediated by Th2 cells and eosinophils, in fibrosis remains unknown. Transgenic mice deficient in the transcriptional repressor, Bcl6, display an attenuation of Th2 cytokine production. We studied the effects of Th2-type pulmonary inflammation on bleomycin-induced pulmonary fibrosis using Bcl6 transgenic mice. Methods: Bleomycin was administered to ovalbumin (OVA)-sensitized Bcl6 transgenic and wild-type mice by intratracheal instillation during sequential OVA antigen challenge. Concentrations of transforming growth factor-,1 in the BAL fluid were measured 2 weeks after bleomycin administration. At the same time lung tissue was examined histopathologically, and homogenized to assess collagen levels and Th1/Th2 cytokine mRNA expression. Results: Although OVA-sensitized, bleomycin-treated Bcl6 transgenic mice had markedly lower numbers of eosinophils in both BAL and lung tissue compared with OVA-sensitized, bleomycin-treated wild-type mice, the development of pulmonary fibrosis in response to bleomycin was similar in Bcl6 transgenic mice and wild-type mice. Conclusion: These results suggest that Th2-dominant inflammation in the lung is not essential for the development of bleomycin-induced pulmonary fibrosis. [source] | ||||||||||||||||||||||||||||||||||||||||||||||