Interleukin 5 enhances interleukin 4-induced IgE production by normal human B cells. The role of soluble CD23 antigen

The Unified Airway Hypothesis: Evidence From Specific Intervention With Anti-IL-5 Biologic Therapy

The unified airway hypothesis proposes that upper and lower airway diseases reflect a single pathological process manifesting in different locations within the airway. Functional, epidemiological, and pathological evidence has supported this well-established hypothesis for some time. However, literature on the pathobiologic roles/therapeutic targeting of eosinophils and IL-5 in upper and lower airway diseases (including asthma, chronic rhinosinusitis with nasal polyps [CRSwNP], and nonsteroidal anti-inflammatory drug-exacerbated respiratory disease) has recently emerged. This narrative review revisits the unified airway hypothesis by searching the scientific literature for recent learnings and clinical trial/real-world data that provide a novel perspective on its relevance for clinicians. According to the available literature, eosinophils and IL-5 have important pathophysiological roles in both the upper and lower airways, although the impact of eosinophils and IL-5 may vary in asthma and CRSwNP. Some differential effects of anti-IL-5 and anti-IL-5-receptor therapies in CRSwNP have been observed, requiring further investigation. However, pharmaceutical targeting of eosinophils and IL-5 in patients with upper, lower, and comorbid upper and lower airway inflammation has led to clinical benefit, supporting the hypothesis that these are linked conditions manifesting in different locations. Consideration of this approach may improve patient care and aid clinical decision making.

Biomarkers in Different Asthma Phenotypes

Asthma is the most common respiratory disease. It has multiple phenotypes thatcan be partially differentiated by measuring the disease’s specific characteristics—biomarkers. The pathogenetic mechanisms are complex, and it is still a challenge to choose suitable biomarkers to adequately stratify patients, which became especially important with the introduction of biologicals in asthma treatment. Usage of biomarkers and an understanding of the underlying pathobiological mechanisms lead to the definition of endotypes. Asthma can be broadly divided into two endotypes, T2-high and T2-low. The right combination of various biomarkers in different phenotypes is under investigation, hoping to help researchers and clinicians in better disease evaluation since theindividual approach and personalized medicine are imperative. Multiple biomarkers are superior to a single biomarker.

Triterpenoid compound betulin attenuates allergic airway inflammation by modulating antioxidants, inflammatory cytokines and tissue transglutaminase in ovalbumin-induced asthma mice model

OBJECTIVES

This study hypothesized that to analyse the anti-inflammatory effect of triterpenoid compound betulin in ovalbumin (OVA)-induced asthmatic mice.

METHODS

In this study, betulin was intraperitoneally administered in OVA-challenged and sensitized mice. The effect of betulin on inflammatory cells, lung function, reactive oxygen species (ROS) production, antioxidants status, oxidative stress markers, serum IgE level and inflammatory cytokines status in BALF was examined by enzyme-linked immunosorbent assay. The expression of tTG, TGF-β1, MMP-9 and TIMP-1 in lung tissue was scrutinized by RT-qPCR analysis, and the expression of TREM-1, p-IκB-α and NF-κBp65 proteins in lung tissue was examined by western blot analysis.

KEY FINDINGS

We found that the betulin treatment has effectively attenuated the proliferation of inflammatory cells, reduced the ROS generation, elevated the antioxidant enzymes and attenuated the level of oxidative markers in asthma induced mice. Moreover, reduced the level of serum IgE and pro-inflammatory cytokines, and increased the anti-inflammatory cytokine IFN-γ. Betulin treatment down-regulated the expression of MMP-9, tTG and TGF-β1 genes; moreover, betulin treatment effectively down-regulated the TREM-1, p-IκB-α and NF-κBp65 proteins level in lung.

CONCLUSION

Betulin exhibited effective anti-asthmatic activity by attenuating the accumulation of inflammatory cells, expression of tTG, TGF-β1 and MMP-9 genes in lung tissue.

Berberine induces anti-atopic dermatitis effects through the downregulation of cutaneous EIF3F and MALT1 in NC/Nga mice with atopy-like dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with severe pruritus. Berberine, a naturally occurring isoquinoline alkaloid, has anti-inflammatory effects. This study investigated the effects and molecular mechanisms of berberine on AD-like symptoms in mice. In this study, NC/Nga mice with atopy-like dermatitis (dermatitis mice), fibroblast and mast cells were used. In dermatitis mice, intermittent oral administrations of berberine 3 times a week for 12 days inhibited skin symptom, itching, cutaneous infiltration of eosinophils and mast cells, and the expression of cutaneous eotaxin, macrophage migration inhibitory factor (MIF) and IL-4. Berberine also attenuated IL-4/MIF-induced eotaxin in fibroblasts and allergen-induced MIF and IL-4 in mast cells. In mast cells, the GeneChip® microarray showed that antigen increased the expression of EIF3F and MALT1, inhibited by berberine. The siRNAs for them inhibited the expression of MIF and IL-4 in antigen-stimulated mast cells. These results suggest that berberine improves AD-like symptoms through the inhibition of the eotaxin and pro-inflammatory cytokine expression and the related inflammatory cell recruitment. It is also suggested that the downregulation of EIF3F and MALT1 by berberine is involved in suppressing the cytokine expression. Taken together, berberine or berberine-containing crude drugs are expected to contribute to the improvement of AD symptoms.

Lactobacillus rhamnosus 2016SWU.05.0601 regulates immune balance in ovalbumin-sensitized mice by modulating expression of the immune-related transcription factors and gut microbiota

BACKGROUND

Probiotics regulate host immune balance, which may reduce immune-related diseases. The effects and mechanisms of Lactobacillus rhamnosus 2016SWU.05.0601 (Lr-0601) on the immune response in ovalbumin (OVA)-sensitized mice were explored.

RESULTS

Lr-0601 reduced serum immunoglobulin (Ig)E and OVA-IgE and attenuated the alteration in lung pathology in OVA-sensitized mice. Lr-0601 blocked OVA-induced up-regulation in serum T helper (Th) 2 and Th17 cytokines but increased the serum levels of Th1 and regulatory T (Treg) cytokines in OVA-sensitized mice. OVA also markedly reduced the protein levels of spleen T-box transcription factor and forkhead/winged helix transcription factor p3, leading to the reduced mRNA expression of interferon-γ and interleukin (IL)-10. By contrast, OVA markedly increased the protein expression of spleen GATA-binding protein 3 and retinoid-related orphan receptor γt, as well as the mRNA expression of spleen IL-4 and IL-17. These changes induced by OVA were reversed by Lr-0601. Moreover, Lr-0601 helped alleviate OVA-induced intestinal microbiota dysbiosis. A correlation was found between specific genera and immune-associated cytokines.

CONCLUSION

The combined results indicate that Lr-0601 modulated the balance of Th1/Th2 and Treg/Th17 in OVA-sensitized mice, which was associated with the regulation of immune-related transcription factors and gut microbiota. Lr-0601 can potentially be used as a probiotic for preventing immune-related diseases. © 2020 Society of Chemical Industry.

A novel sphingosylphosphorylcholine and sphingosine-1-phosphate receptor 1 antagonist, KRO-105714, for alleviating atopic dermatitis

Background

Atopic dermatitis (eczema) is a type of inflammation of the skin, which presents with itchy, red, swollen, and cracked skin. The high global incidence of atopic dermatitis makes it one of the major skin diseases threatening public health. Sphingosylphosphorylcholine (SPC) and sphingosine-1-phosphate (S1P) act as pro-inflammatory mediators, as an angiogenesis factor and a mitogen in skin fibroblasts, respectively, both of which are important biological responses to atopic dermatitis. The SPC level is known to be elevated in atopic dermatitis, resulting from abnormal expression of sphingomyelin (SM) deacylase, accompanied by a deficiency in ceramide. Also, S1P and its receptor, sphingosine-1-phosphate receptor 1 (S1P1) are important targets in treating atopic dermatitis.

Results

In this study, we found a novel antagonist of SPC and S1P1, KRO-105714, by screening 10,000 compounds. To screen the compounds, we used an SPC-induced cell proliferation assay based on a high-throughput screening (HTS) system and a human S1P1 protein-based [³⁵S]-GTPγS binding assay. In addition, we confirmed the inhibitory effects of KRO-105714 on atopic dermatitis through related cell-based assays, including a tube formation assay, a cell migration assay, and an ELISA assay on inflammatory cytokines. Finally, we confirmed that KRO-105714 alleviates atopic dermatitis symptoms in a series of mouse models.

Conclusions

Taken together, our data suggest that SPC and S1P1 antagonist KRO-105714 has the potential to alleviate atopic dermatitis.

IL-5Rα marks nasal polyp IgG4- and IgE-expressing cells in aspirin-exacerbated respiratory disease

BACKGROUND

The cause of severe nasal polyposis in aspirin-exacerbated respiratory disease (AERD) is unknown. Elevated antibody levels have been associated with disease severity in nasal polyps, but upstream drivers of local antibody production in nasal polyps are undetermined.

OBJECTIVE

We sought to identify upstream drivers and phenotypic properties of local antibody-expressing cells in nasal polyps from subjects with AERD.

METHODS

Sinus tissue was obtained from subjects with AERD, chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), CRS without nasal polyps, and controls without CRS. Tissue antibody levels were quantified via ELISA and immunohistochemistry and were correlated with disease severity. Antibody-expressing cells were profiled with single-cell RNA sequencing, flow cytometry, and immunofluorescence, with IL-5Rα function determined through IL-5 stimulation and subsequent RNA sequencing and quantitative PCR.

RESULTS

Tissue IgE and IgG4 levels were elevated in AERD compared with in controls (P < .01 for IgE and P < .001 for IgG4 vs CRSwNP). Subjects with AERD whose nasal polyps recurred rapidly had higher IgE levels than did subjects with AERD, with slower regrowth (P = .005). Single-cell RNA sequencing revealed increased IL5RA, IGHG4, and IGHE in antibody-expressing cells from patients with AERD compared with antibody-expressing cells from patients with CRSwNP. There were more IL-5Rα⁺ plasma cells in the polyp tissue from those with AERD than in polyp tissue from those with CRSwNP (P = .026). IL-5 stimulation of plasma cells in vitro induced changes in a distinct set of transcripts.

CONCLUSIONS

Our study identifies an increase in antibody-expressing cells in AERD defined by transcript enrichment of IL5RA and IGHG4 or IGHE, with confirmed surface expression of IL-5Rα and functional IL-5 signaling. Tissue IgE and IgG4 levels are elevated in AERD, and higher IgE levels are associated with faster nasal polyp regrowth. Our findings suggest a role for IL-5Rα⁺ antibody-expressing cells in facilitating local antibody production and severe nasal polyps in AERD.

Immunoglobulin E as a Biomarker in Asthma

Asthma is a chronic disease that affects children and adults with significant morbidity and mortality. It is multifactorial, with genetic and environmental factors affecting the overall course of the disease. Both specific and total immunoglobulin (Ig)E can be used in specific phenotypes such as allergic asthma. Using IgE as a biomarker for asthma provides a target for management and treatment. Biotherapeutics continue to emerge as important advances in asthma treatment, and their effect on IgE and its biomarker role continue to be studied.

RelB-Deficient Dendritic Cells Promote the Development of Spontaneous Allergic Airway Inflammation

RelB is a member of the NF-κB family, which is essential for dendritic cell (DC) function and maturation. However, the contribution of RelB to the development of allergic airway inflammation (AAI) is unknown. Here, we identify a pivotal role for RelB in the development of spontaneous AAI that is independent of exogenous allergen exposure. We assessed AAI in two strains of RelB-deficient (RelB^-/-) mice: one with a targeted deletion and one expressing a major histocompatibility complex transgene. To determine the importance of RelB in DCs, RelB-sufficient DCs (RelB^+/+ or RelB^-/-) were adoptively transferred into RelB^-/- mice. Both strains had increased pulmonary inflammation compared with their respective wild-type (RelB^+/+) and heterozygous (RelB^+/-) controls. RelB^-/- mice also had increased inflammatory cell influx into the airways, levels of chemokines (CCL2/3/4/5/11/17 and CXCL9/10/13) and T-helper cell type 2-associated cytokines (IL-4/5) in lung tissues, serum IgE, and airway remodeling (mucus-secreting cell numbers, collagen deposition, and epithelial thickening). Transfer of RelB^+/- CD11c⁺ DCs into RelB^-/- mice decreased pulmonary inflammation, with reductions in lung chemokines, T-helper cell type 2-associated cytokines (IL-4/5/13/25/33 and thymic stromal lymphopoietin), serum IgE, type 2 innate lymphoid cells, myeloid DCs, γδ T cells, lung Vβ13⁺ T cells, mucus-secreting cells, airway collagen deposition, and epithelial thickening. These data indicate that RelB deficiency may be a key pathway underlying AAI, and that DC-encoded RelB is sufficient to restore control of this inflammation.

Pathogenic mechanisms of IgE-mediated inflammation in self-destructive autoimmune responses

Autoantibodies of the IgG subclass are pathogenic in a number of autoimmune disorders such as systemic lupus erythomatosus. The presence of circulating IgE autoantibodies in autoimmune patients has also been known for almost 40 years. Despite their role in allergies, IgE autoantibodies are not associated with a higher rate of atopy in these patients. However, recently they have been recognized as active drivers of autoimmunity through mechanisms involving the secretion of Type I interferons by plasmacytoid dendritic cells (pDC), the recruitment of basophils to lymph nodes, and the activation of adaptive immune responses through B and T cells. Here, we will review the formation, prevalence, affinity, and roles of the IgE autoantibodies that have been described in autoimmunity. We also present novel evidence supporting that triggering of IgE receptors in pDC induces LC3-associated phagocytosis, a cellular process also known as LAP that is associated with interferon responses. The activation of pDC with immune complexes formed by DNA-specific IgE antibodies also induce potent B-cell differentiation and plasma cell formation, which further define IgE's role in autoimmune humoral responses.

Effect of the topical application of an ethanol extract of quince seeds on the development of atopic dermatitis-like symptoms in NC/Nga mice

Background

Quince (Cydonia oblonga Miller) is a deciduous shrub belonging to the Rosaceae family. Quince seed extract has long been used as a cosmetic ingredient for its moisturizing effect. However, little is known about whether quince seed extract has therapeutic effects on keratinocyte-associated skin inflammation.

Methods

In the present study, we investigated the effect of the topical application of ethanol extract of quince seeds (QSEtE) on atopic dermatitis (AD) symptoms in NC/Nga mice. The direct effect of QSEtE on keratinocytes was evaluated using the human keratinocyte cell line HaCaT.

Results

The preliminary application of QSEtE markedly reduced house dust mite allergen-induced skin lesions. The expression of thymus- and activation-regulated chemokine (TARC) in dorsal skin was downregulated. QSEtE directly suppressed the expression and production of TARC in HaCaT cells.

Conclusions

The results suggest that the topical application of QSEtE is effective in preventing the onset of and ameliorating the atopic symptoms of keratinocyte-associated skin inflammation by suppressing TARC production in keratinocytes.

Control of Circulating IgE by the Vitamin D Receptor In Vivo Involves B Cell Intrinsic and Extrinsic Mechanisms

Vitamin D deficiency is associated with the development of asthma and allergy. The active form of vitamin D [1,25(OH)₂D] regulates B cells in vitro and mice without the vitamin D receptor (VDR knockout [KO]) have high serum IgE. Whole-body VDR KO, T cell-specific VDR (T-VDR) KO, B cell-specific VDR (B-VDR) KO, and vitamin D deficient mice were used to determine the targets of vitamin D in the regulation of IgE in vivo. Vitamin D deficient, VDR KO, and B-VDR KO mice developed hyper-IgE, whereas T-VDR KO mice did not. The data show that IL-10 secretion by B cells and CD1d expression on IL-10 secreting B cells was lower in VDR KO mice. Mesenteric lymph node cultures from VDR KO and B-VDR KO mice secreted higher IgE ex vivo than wild-type (WT) cultures, and the addition of IL-10 eliminated the difference in IgE production between VDR KO and WT cultures. The increase in IgE in VDR KO mice was 2-fold greater than in the B-VDR KO mice, suggesting that VDR deficiency in non-B cells contributes to hyper-IgE in vivo. Antibiotic depletion of the microbiota raised serum IgE 4-fold in both WT and VDR KO mice. The VDR directly and indirectly regulates IgE production in B cells. Through the VDR, vitamin D is an environmental factor that helps to maintain low serum IgE responses.

Strategies targeting the IL-4/IL-13 axes in disease

IL-4 and IL-13 are pleiotropic Th2 cytokines produced by a wide variety of different cell types and responsible for a broad range of biology and functions. Physiologically, Th2 cytokines are known to mediate host defense against parasites but they can also trigger disease if their activities are dysregulated. In this review we discuss the rationale for targeting the IL-4/IL-13 axes in asthma, atopic dermatitis, allergic rhinitis, COPD, cancer, inflammatory bowel disease, autoimmune disease and fibrotic disease as well as evaluating the associated clinical data derived from blocking IL-4, IL-13 or IL-4 and IL-13 together.

Suppression of dust mite allergy by mucosal delivery of a hypoallergenic derivative in a mouse model

Allergic asthma caused by house dust mite (HDM) is becoming a public health problem. Specific immunotherapy is considered to be the only curative treatment, but it is always associated with IgE-mediated side effects in the therapy process. A few studies showed that the disruption of allergen IgE epitopes could reduce IgE reactivity and thus reduce allergenic activity. In this study, a hypoallergenic derivative of the major HDM allergen Der p2 was constructed by genetic engineering. This derivative was confirmed to have a considerably reduced IgE reactivity compared with Der p2. For its application in vivo, recombinant Lactococcus lactis (LL-DM) was engineered to deliver the Der p2 derivative to the intestinal mucosal surface. Oral administration of LL-DM significantly alleviated Der p2-induced airway inflammation, as shown by reduced inflammatory infiltration and a reduction in Th2 cytokines in bronchoalveolar lavage. This protective effect was associated with an up-regulation of specific IgG2a and a decrease in IL-4 level in the spleen which may affect specific IgE response. Moreover, the levels of regulatory T cells in the mesenteric lymph nodes and spleen were markedly increased in mice fed with LL-DM, suggesting that LL-DM can inhibit allergic responses via the induction of regulatory T cell. Our results indicate that the Der p2 derivative is a promising therapeutic molecule for specific immunotherapy and recombinant lactic acid bacteria could be developed as a promising treatment or prevention strategy for allergic diseases.

Siegesbeckia glabrescens attenuates allergic airway inflammation in LPS-stimulated RAW 264.7 cells and OVA induced asthma murine model

Siegesbeckia glabrescens (SG) is a plant growing in Korea that is used as a traditional medicine for various inflammatory diseases. In this study, we investigated the protective effects of SG extract on allergic asthma in an ovalbumin (OVA)-induced asthma murine model and lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Female BALB/c mice were sensitized by intraperitoneal injection of OVA on days 0 and 14 and then challenged with OVA from days 21 to 23. SG (30mg/kg) was administered by oral gavage 1h before the OVA challenge. LPS-stimulated RAW264.7 cells were evaluated to determine their levels of nitric oxide (NO). The SG significantly reduced the number of inflammatory cells in bronchoalveolar lavage (BAL) fluid and also reduced IL-4, IL-5, IL-13, eotaxin and immunoglobulin E in OVA-sensitized/challenged mice. SG also effectively reduced airway inflammation and mucus overproduction in lung tissue in addition to decreasing the expression of iNOS and COX-2. In LPS-stimulated RAW264.7 cells, SG treatment significantly reduced the levels of NO. These findings indicate that SG effectively suppressed inflammatory responses, and its effects appear to be related to reduction in iNOS and COX-2 expression. Therefore, we suggest that SG may have potential use as a therapeutic agent for inflammatory diseases such as allergic asthma.

Effects of Hyeonggaeyeongyo-tang in ovalbumin-induced allergic rhinitis model

Allergic rhinitis (AR) is an allergic inflammation of the nasal airways. The prevalence of AR is increasing worldwide. We investigated whether Hyeonggaeyeongyo-tang (HYT) is effective to suppress the progression of AR induced by ovalbumin (OVA). Male BALB/c mice were used for this study. Allergic rhinitis was induced by OVA. Treatment with HYT was assessed to study the effect of HYT on allergic rhinitis in mice. Histological analysis, immunohistochemistry, multiplex cytokine assay, blood analysis, and cell viability assay were performed to verify inhibitory effect of HYT on allergic rhinitis. HYT did not show any toxicity maintaining body weight. Food intake was steady without variation in mice. HYT reduced infiltration of inflammatory cells and mast cells into nasal cavity. HYT reduced the levels of cytokines and leukocytes in the blood. HYT decreased the splenocyte cell viability. Antihistamines and steroids are the most common medications used to treat allergic rhinitis. However, long-term use of drug generates resistance or side effects requiring the development of new drug. Our present study clearly demonstrates that HYT suppresses the progression of allergic rhinitis induced by OVA. This suggests that HYT might be a useful drug for the treatment of allergic rhinitis.

Comparisons on enhancing the immunity of fresh and dry Cordyceps militaris in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

The immunomodulatory capacities of fresh Cordyceps militaris (FCM) and dry Cordyceps militaris (DCM) were compared.

MATERIALS AND METHODS

In vivo immunomodulatory assay, different doses of FCM and DCM were orally administrated over a period of 15 days in a cyclophosphamide (CY) induced immunosuppression mice; in vitro testing, the spleen cells were extracted from healthy mice and treaded with CY, then cultured with different dose of FCM or DCM; the contents of Cordyceps militaris polysaccharide (CMP), cordycepin, adenosine, total polyphenol (TP) and total flavonoids (TF) in FCM and DCM were measured.

RESULTS

Our studys indicated that, FCM was significantly stronger than DCM on increasing the spleen and thymus indexes, spleen lymphocyte activity, macrophage function, and promoting the levels of IL-2, IFN-γ in vivo and in vitro. The contents of immunomodulatory CMP and TF in FCM were markedly higher than in DCM.

CONCLUSION

All these results suggested that FCM was superior to DCM on enhancing immunity.

Serum interleukin--4 and tumor necrosis factor alpha concentrations in children with primary acid gastroesophageal reflux and acid gastroesophageal reflux secondary to cow's milk allergy

AIM

The possible role of serum interleukin 4 (IL-4) and tumor necrosis factor alpha (TNF- α) in pathogenesis of the reflux symptoms in children with primary acid gastroesophageal reflux (GER) and acid GER secondary to cow's milk allergy (CMA).

MATERIAL AND METHODS

Out of 264 children, 76 (28.8%) patients with primary GER and 62 (23.5%) patients with GER secondary to CMA (pH - monitoring) serum IL-4 and TNF- α concentrations were assessed before treatment, 1 and 2 years after the initiation of the periodically administered pharmacotherapy.

RESULTS

Children with primary GER had mean IL-4 concentrations 0.17 ± 0.06 pg/ml before treatment, 0.08 ± 0.07 pg/ ml after 1-year and 0.07 ± 0.06 pg/ml after 2-years of treatment. The mean IL-4 concentrations were 1.07 ± 0.24, 0.5 ± 0.22 and 0.44 ± 0.19 pg/ml respectively in children with GER secondary to CMA. The mean serum TNF- α concentrations was 3.62 ± 1.30 pg/ml before treatment , 2.16 ± 1,35 pg/ ml after 1 year and 1.65 ± 1.16 pg/ml after 2 years of treatment in children with primary GER. In group with GER secondary to CMA mean serum TNF- α concentrations were 4.95 ± 1.88, 2.53 ± 0.80 and 2.02 ± 0.78 pg/ml respectively. Statistical analysis of the concentration of both cytokines showed their differentiation between them and in the study groups.

CONCLUSIONS

The highest mean serum IL-4 and TNF-α concentrations were observed in children with GER secondary to CMA and in children in control group (with cow's milk allergy and/or other food allergy diagnosed - CMA/FA) before the treatment administration.

Glycyrrhiza uralensis flavonoids present in anti-asthma formula, ASHMI™, inhibit memory Th2 responses in vitro and in vivo

Allergic asthma is associated with Th2-mediated inflammation. Several flavonoids were isolated from Glycyrrhiza uralensis, one of the herbs in the anti-asthma herbal medicine intervention. The aim of this investigation was to determine whether Glycyrrhiza uralensis flavonoids have inhibitory effects on memory Th2 responses in vitro and antigen-induced Th2 inflammation in vivo. The effects of three Glycyrrhiza uralensis flavonoids on effector memory Th2 cells, D10.G4.1 (D10 cells), were determined by measuring Th2 cytokine production. Isoliquiritigenin, 7, 4'-dihydroxyflavone (7, 4'-DHF) and liquiritigenin significantly suppressed IL-4 and IL-5 production in a dose-dependent manner, 7, 4'-DHF being most potent. It was also evaluated for effects on D10 cell proliferation, GATA-3 expression and IL-4 mRNA expression, which were suppressed, with no loss of cell viability. Chronic treatment with 7, 4'-DHF in a murine model of allergic asthma not only significantly reduced eosinophilic pulmonary inflammation, serum IgE levels, IL-4 and IL-13 levels, but also increased IFN-γ production in lung cell cultures in response to antigen stimulation.

Dietary β-glucan regulates the levels of inflammatory factors, inflammatory cytokines, and immunoglobulins in interleukin-10 knockout mice

β-Glucan is known to have anti-inflammatory properties, and several studies have demonstrated the beneficial effects of dietary β-glucan on inflammatory bowel disease (IBD). However, it is unknown how β-glucan mediates its protective effects on IBD. Therefore, we used a well-established mouse model for IBD, interleukin (IL)-10(-/-) mice, to explore the protective effects of β-glucan on IBD-like symptoms caused by IL-10 deficiency. The mice were divided into two groups: IL-10(-/-) and IL-10(-/-) + β-glucan treatment groups. IL-10(-/-) mice treated with dietary β-glucan exhibited less inflammation within the colon. The levels of immunoglobulins A and E were lower in the serum, spleen, mesenteric lymph nodes, and Peyer's patches in the IL-10(-/-) mice compared with the IL-10(-/-) + β-glucan mice. Also, the expression of pro-inflammatory cytokines was lower in the IL-10(-/-) + β-glucan mice compared with the IL-10(-/-) mice. Histological analysis also revealed that administration of dietary β-glucan in IL-10(-/-) mice reduced colonic tissue damage. Finally, the expression of the pro-inflammatory cytokine tissue necrosis factor-α was significantly lower with dietary β-glucan treatment in IL-10(-/-) mice. In conclusion, dietary β-glucan reduces the inflammation associated with IBD caused by IL-10 deficiency.

Association of IL-5 cytokine production and in vivo IgE levels in infants and parents

BACKGROUND

Total IgE in human subjects tracks strongly from birth onward through unknown mechanisms. Regulation of IgE might occur in relation to adaptive immune cytokine production. In vitro studies have assessed the role of individual cytokines in regulating IgE production in human subjects.

OBJECTIVE

We sought to investigate the association between IgE levels in vivo and the capacity of the individuals to produce adaptive immune cytokines.

METHODS

Blood samples from participants in the Tucson Infant Immune Study (children at birth and at 3 and 12 months of age, fathers, and mothers before and after delivery) were assessed for percentage of eosinophils and plasma total IgE levels. IFN-gamma, IL-4, IL-5, IL-13, and IL-10 levels were measured in supernatants of mitogen-stimulated PBMCs and examined cross-sectionally for relation to cytokine production by using simple regression, multiple regression with cytokines only and with other known predictors of IgE levels, and longitudinally by means of random effects modeling.

RESULTS

After adjusting for eosinophils and other predictors, IL-5 production (but not that of other cytokines) was associated directly with total IgE levels in children at 3 months (P = .009) and 12 months (P = .011) of age but not at birth. The IL-5/IgE association was present also in fathers (P = .040) and in mothers, both during pregnancy (P < .001) and after delivery (P = .030).

CONCLUSIONS

This study indicates that mitogen-stimulated IL-5 production is associated with in vivo total IgE levels, independent of the production of other cytokines and circulating eosinophils.

CLINICAL IMPLICATIONS

Understanding the regulation of IgE in vivo might help elucidate the development of allergic responses in individuals.

T Helper Type 2-Biased Natural Killer Cell Phenotype in Patients with Pemphigus Vulgaris

Pemphigus vulgaris (PV) is an autoantibody-mediated bullous disease, but the role of natural killer (NK) cells in its pathogenic process has never been examined in detail. Circulating CD56+ CD3- NK cells as well as CD69+-activated NK cells were increased in PV patients compared with healthy controls and patients with other autoantibody-mediated autoimmune diseases, including immune thrombocytopenic purpura and myasthenia gravis. Gene expression analysis of highly purified NK cells demonstrated an increased expression of IL-10 and decreased expression of IL-12Rbeta2, perforin, and granzyme B ex vivo in PV patients versus healthy controls. The NK cells from PV patients also showed impaired signal transducer and activator of transduction4 phosphorylation upon in vitro IL-12 stimulation. Moreover, NK cells from PV patients exhibited reduced IL-10 production in response to in vitro stimulation with IL-2/IL-12. Finally, IL-5 expression in NK cells was exclusively detected ex vivo in PV patients with active disease, and was lost in subsequent analyses performed during disease remission. Together these findings suggest that NK cells contribute to a T helper type 2-biased immune response in PV patients through impaired IL-12 signaling and an upregulation of IL-10 and IL-5.

Serine proteases, their inhibitors and allergy

This paper reviews four serine protease inhibitors and three protease gene defects that are associated with allergic conditions, suggesting an important role for these genes and their products in the development of allergy. Serine protease inhibitors may have a therapeutic potential in the treatment of allergy.

ADAM10 is a principal 'sheddase' of the low-affinity immunoglobulin E receptor CD23

CD23, the low-affinity immunoglobulin E receptor, is an important modulator of the allergic response and of diseases such as rheumatoid arthritis. The proteolytic release of CD23 from cells is considered a key event in the allergic response. Here we used loss-of-function and gain-of-function experiments with cells lacking or overexpressing candidate CD23-releasing enzymes (ADAM8, ADAM9, ADAM10, ADAM12, ADAM15, ADAM17, ADAM19 and ADAM33), ADAM-knockout mice and a selective inhibitor to identify ADAM10 as the main CD23-releasing enzyme in vivo. Our findings provide a likely target for the treatment of allergic reactions and set the stage for further studies of the involvement of ADAM10 in CD23-dependent pathologies.

The level of IgE produced by a B cell is regulated by norepinephrine in a p38 MAPK- and CD23-dependent manner

Although the causes of asthma vary, the severity of the disease correlates with the level of IgE produced. In this study we show that mice produced less IgE when they were depleted of the neurotransmitter norepinephrine (NE) before the administration of Ag. The suppression was prevented when a beta2-adrenergic receptor (beta2AR)-selective agonist was administered, suggesting that NE stimulated the beta2AR to regulate the level of an IgE response in vivo. Although the cell targeted by NE to produce this effect in vivo is unknown, we show in vitro that the level of IgE increased on a per cell basis without an effect on class switch recombination when NE stimulated the beta2AR on a B cell directly. The beta2AR-induced increase in IgE depended on p38 MAPK but not protein kinase A activation, was due to an increased rate of mature IgE mRNA transcription, and was lost when beta2AR-deficient B cells were used. Also, CD23 transcription was increased in a p38 MAPK-dependent manner and resulted in an increased level of soluble CD23 (sCD23). The beta2AR-induced increase in sCD23 was associated with IgE up-regulation and possibly interacted with CD21/CD19. Using B cells from respective knockout mice, data showed that the beta2AR-induced increase in IgE depended on B cell expression of CD23, CD21, and CD19. These findings suggest that at least one mechanism by which endogenous B cell activity in vivo is regulated by NE involves stimulation of the beta2AR on the B cell alone to increase the level of IgE produced in a p38 MAPK- and sCD23-dependent manner.

Anti-CD23

CD23, the low-affinity immunoglobulin (Ig)E receptor (FcepsilonRII), is widely distributed on the surface of various human cells. CD23 mediates numerous IgE-related immune responses (including allergen focusing) by enhancing IgE antigen complex presentation, regulating IgE synthesis, influencing cell differentiation and growth of both B- and T-cells, and stimulating production of pro-inflammatory mediators from monocytes/macrophages, eosinophils, and even airway smooth muscle cells. Both membrane and soluble CD23 play an important role in allergic reactions. Cellular contacts and cytokines modulate its expression in a concerted manner as needed for allergic reactions. Expression of CD23 and soluble CD23 has been associated with allergic diseases. Targeting CD23 with monoclonal antibody (MAb) is a promising candidate therapy in allergic diseases. A newly developed agent known as Lumiliximab, which is an anti-CD23 MAb (Lumiliximab), was demonstrated to be a well-tolerated agent in a phase I clinical trial (a placebo-controlled study with allergic asthma). Adverse events were mild, and no relationship was apparent between the dose of Lumilixilab and the frequency, severity, or type of event. Sustained and dose-dependent decreases in mean serum total IgE concentrations were noted. The serum half-life of Lumilixilab increased from 2 to 10 d with increasing doses. Blocking antigen presentation, preventing costimulation signals, and reducing production of pro-inflammatory mediators are some of the potential mechanisms involved for anti-CD23 activity. Although the safety and clinical efficacy of Lumilixilab in allergic asthma and rhinitis require confirmation, the observed data imply that anti-CD23 is a promising candidate therapy option for future treatment of allergic diseases.

Concentrations of gastric mucosal cytokines in children with food allergy and Helicobacter pylori infection

AIM: To measure the concentrations of chosen cytokines in the antrum mucosa depending on the kind of harmful pathogenic factors and to compare the concentrations with the values of controls without allergy and coexisting Helicobacter pylori (H pylori) infection.

METHODS: The patients (97 children) were divided into three groups according to the data obtained from the case history, to the main cause of the disease and to the dominant clinical symptoms. Group I: children with food allergy (Fa); group II: children infected with H pylori; group III (control group): children with functional disorders of the alimentary tract (without Fa and Hp infection). H pylori infection was determined by the presence of anti-Hp antibodies in serum (ELISA method) and urease test performed during endoscopic examination. Cytokine concentration in homogenates of gastric mucosa was detected by ELISA method.

RESULTS: The IL-2 concentration in gastric mucosa bioptates was the highest in children with Hp infection (116.5±179.5 pg/mg of the protein) and Fa and Hp infection (98.1±101.0 pg/mg), while decreased in children with Fa (44.8±50.3 pg/mg) and controls (45.7±23.5 pg/mg). The lowest mean concentration of IFN-γ was observed in children with Hp infection (18.9±16.4 pg/mg), with Fa and Hp infection (25.5±27.7 pg/mg), with Fa (40.6±39.7 pg/mg) and controls (49.9±33.4 pg/mg). The highest IL-4 concentrations were observed in children with Hp infection (35.3±52.8 pg/mg) and in children with Fa and Hp infection (37.2±51.7 pg/mg), while lower IL-4 concentration (23.6±35.8 pg/mg) was found in children with Fa compared to the controls (22.7±13.8 pg/mg). The analysis of IL-4 concentrations in children with Hp infection regarding the intensity of gastritis showed the highest value (62.2±61.2 pg/mg) in mild and moderate gastritis. The concentrations of IL-5 in the gastric mucosa of children with or without Fa did not differ significantly and were comparable to the control group. The highest mean IL-8 value was observed in Hp-infected children with or without Fa. The highest concentration of mucosal IL-10 was detected in children with Hp infection (79.3±41.2 pg/mg) and decreased in children with Fa and Hp infection (50.1±18.8 pg/mg) and in children with Fa (39.9±35.5 pg/mg). The intensity and activity of the inflammation did not affect IL-10 concentrations in the gastric mucosa. In children with Hp infection, TNF-α concentration was the highest (45.9±49.3 pg/mg) and in children with Fa and Hp infection was low (45.3±32.6 pg/mg), whereas decreased in children with Fa (21.7±34.2 pg/mg) and in controls (31.6±14.5 pg/mg).

CONCLUSION: The morphological changes of the gastric mucosa in children with Hp infection are comparable to those in children with Fa and coexisting Hp infection. Cytokine concentration in children with Fa and Hp infection is significantly different in IFN-γ, IL-2, IL-8, and TNF-α.

IgM production of lymphocytes from C57BL/6N mice was stimulated by estrogen treated splenic adherent cells

Estrogens have diverse effects on cell growth, differentiation and homeostatic functions, and have been shown to play an important role in regulating immune system. In this study, we examined the effect of 17beta-estradiol (E2) on antibody production by splenocytes isolated from C57BL/6N mice. Our results suggest that the activation of immunoglobulin (Ig) M production by E2 requires direct cell-cell interaction between adherent and non-adherent cells in mouse splenocyte population, and the primary target of E2 is adherent cell population. In addition, we indicated that ER antagonist ICI 182780 suppressed this enhancing effect of E2. Both ERalpha agonist and ERalpha agonist enhanced IgM production of mouse splenocytes. ERs are expressed on plasma membrane as well as in nucleus. However, a plasma membrane-associated ER specific ligand has no stimulation effect on IgM production. In conclusion, our results indicate that adherent cells stimulated by E2 up-regulate IgM production of lymphocytes through the direct cell-cell interactions, and the enhancing effect of E2 is arouse through ERalpha and ERbeta on these cells.

Elevated expression of CD23 on peripheral blood B lymphocytes from patients with bullous pemphigoid: correlation with increased serum IgE

BACKGROUND

Increased serum IgE levels are occasionally found in patients with severe bullous pemphigoid (BP). CD23, a low affinity Fc receptor for IgE, is mainly expressed on mature B lymphocytes. Studies have suggested that serum levels of soluble CD23 (sCD23) correlate with serum IgE levels and disease severity in BP.

OBJECTIVE

The purpose of our study is to examine whether the expression of CD23 is elevated in BP and whether this expression correlates with serum IgE levels and disease severity.

METHODS

We measured CD23 expression on B cells from patients with active BP, pemphigus vulgaris, pemphigus foliaceus, and atopic dermatitis (AD), as well as healthy control subjects, using a flow cytometer. Serum levels of IgE and sCD23 were also measured.

RESULTS

The expression of CD23 was significantly higher in BP patients compared with healthy control subjects (P < 0.05), whereas the levels were normal in the other bullous diseases. CD23 expression tended to be higher in severe BP compared with moderate BP, and the levels in severe BP were comparable to the levels in AD. Furthermore, CD23 expression correlated positively with serum IgE levels (P < 0.002), and the IgE levels were significantly higher in severe BP than in moderate BP (P < 0.01 ). CD23 expression in BP did not correlate with sCD23 levels.

CONCLUSIONS

These results suggest that the up-regulated surface CD23 on B cells may be involved in IgE synthesis and inflammatory events in BP.

Increased sensitivity to IL-4 in cystic fibrosis patients with allergic bronchopulmonary aspergillosis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is characterized by a heightened Th2 CD4+ T-cell response to Aspergillus fumigatus allergens and a hyper-immunoglobulin (Ig)E state compared with cystic fibrosis patients without ABPA. We hypothesize that one reason for this response is increased sensitivity to interleukin (IL)-4 in ABPA resulting in increased expression of CD23 and CD86 and leading to a positive amplification mechanism that increases Th2 CD4+ T cell responses.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from seven ABPA CF and 19 non-ABPA CF patients and 16 nonatopic controls and stimulated with rIL-4 (range 0.1-10 ng/ml) and rIL-13 (range 1-10 ng/ml) for 48 h. The number of CD23 molecules and percentages of CD23+ B cells were quantified by flow cytometry. Both phorbol 12-myristate 13-acetate (PMA)/ionomycin (IO) and antigen stimulated, toxoid and Asp f2/f3/f4, PBMC were examined for cytoplasmic cytokine synthesis enumerated by cytokine staining using flow cytometry to measure Th2 and Th1 CD3+ T cells.

RESULTS

The numbers of CD23 molecules on B-cells were significantly elevated at time 0 in ABPA CF patients compared with both non-ABPA CF patients and nonatopic controls. Following IL-4 stimulation in vitro, the numbers and percentages of CD23 expression on B cells were significantly up-regulated in ABPA CF patients compared with non-ABPA CF patients and controls. The IL-13 stimulation up-regulated CD23 expression; however, there was no significant difference in ABPA CF patients compared with non-ABPA CF patients and controls. The percentages of interferon (IFN)-gamma+ CD3+T cells following PMA/IO stimulation were significantly decreased in both ABPA and non-ABPA CF patients compared with controls. There were no significant differences of IL-4+ and IL-13+ CD3+ T cells between ABPA and non-ABPA CF patients. When tetanus toxoid stimulated T cells were examined, both ABPA and non-ABPA CF patients had significantly decreased IFN-gamma+ CD3+ T cells compared with controls. In Asp f2/f3/f4 stimulated T cells, ABPA CF patients had significantly increased IL-4+ CD3+ T cells compared with non-ABPA CF patients and controls.

CONCLUSIONS

ABPA CF patients have increased sensitivity to IL-4 but not to IL-13 up-regulation of CD23 molecules compared with non-ABPA CF patients. There were decreased percentages of IFN-gamma+ and IL-2+ Th1 T cells in CF patients compared with nonatopic controls but similar percentages of IL-4+ Th2 T cells in all three groups. However, ABPA CF patients had increased frequency of Aspergillus-stimulated Th2 T cells. This indicated that there is skewing of Th2 T cells in ABPA CF patients. Thus, in CF ABPA patients there is increased Th2 T cells and increased sensitivity to IL-4.

The biology of IGE and the basis of allergic disease

Allergic individuals exposed to minute quantities of allergen experience an immediate response. Immediate hypersensitivity reflects the permanent sensitization of mucosal mast cells by allergen-specific IgE antibodies bound to their high-affinity receptors (FcepsilonRI). A combination of factors contributes to such long-lasting sensitization of the mast cells. They include the homing of mast cells to mucosal tissues, the local synthesis of IgE, the induction of FcepsilonRI expression on mast cells by IgE, the consequent downregulation of FcgammaR (through an insufficiency of the common gamma-chains), and the exceptionally slow dissociation of IgE from FcepsilonRI. To understand the mechanism of the immediate hypersensitivity phenomenon, we need explanations of why IgE antibodies are synthesized in preference to IgG in mucosal tissues and why the IgE is so tenaciously retained on mast cell-surface receptors. There is now compelling evidence that the microenvironment of mucosal tissues of allergic disease favors class switching to IgE; and the exceptionally high affinity of IgE for FcepsilonRI can now be interpreted in terms of the recently determined crystal structures of IgE-FcepsilonRI and IgG-FcgammaR complexes. The rate of local IgE synthesis can easily compensate for the rate of the antibody dissociation from its receptors on mucosal mast cells. Effective mechanisms ensure that allergic reactions are confined to mucosal tissues, thereby minimizing the risk of systemic anaphylaxis.

Wheat gliadin promotes the interleukin-4-induced IgE production by normal human peripheral mononuclear cells through a redox-dependent mechanism

Increased levels of serum IgE have been described in gliadin-intolerant patients; however, biological mechanisms implicated in this immunoglobulin production remained unknown. In this study, we demonstrated that in vitro crude gliadins and gliadin lysates (Glilys) promoted the IL-4-induced IgE production by human peripheral blood mononuclear cells (PBMC), indicating that the biological process related to gliadin intolerance and/or allergy may lead to IgE production in vivo. It was found that crude gliadin and Glilys potentiated, after 13 days of culture in a dose-dependent manner, IL-4-induced IgE production and, to a lesser extent, the IgG production, while they did not affect IgA or IgM productions. This promoting effect of gliadin and Glilys on the IL-4-induced activation of normal human PBMC was also observed on the early release (2 days) of the soluble fraction of CD23, suggesting its possible involvement in IgE potentiation. The promoting effect of crude gliadin and Glilys appeared to be indirect because they did not modify purified B-lymphocytes IgE production after IL-4 and anti-CD40 monoclonal antibody stimulation. In addition, as revealed by luminol-dependent chemiluminescence, we demonstrated that crude gliadin and Glilys promoted a substantial production of free radicals by normal human PBMC, treated or not with IL-4. This redox imbalance associated with an increased IgE production led us to evaluate the effect of pharmacological antioxidants (N-acetyl-cysteine (NAC) and Cu/Zn-superoxide dismutase (SOD1)) on IgE production by human PBMC. The NAC and the intracellularly delivered SOD1 were found to suppress the IL-4+/-crude gliadin or Glilys-induced IgE production by normal human PBMC. Taken together, these data indicated that gliadin specifically enhanced IL-4-induced IgE production by normal human PBMC, probably by the regulation of redox pathways, and that this 'pro-allergenic' effect could be counteracted by natural antioxidants: thiols and/or vectorized SOD1.

Effects of wogonin, wogonoside, and 3,5,7,2',6'-pentahydroxyflavone on chemical mediator production in peritoneal exduate cells and immunoglobulin E of rat mesenteric lymph node lymphocytes

Wogonin (WG), wogonoside (WGS), and 3,5,7,2',6'-pentahydroxyl flavanone (PHF) were isolated from Scutellaria baicalensis, and their effects on histamine, leukotriene B(4) (LTB(4)), and immunoglobulin E (IgE) were examined in rats, observing for a manifestation of a type I allergic reaction. WG and WGS in the amounts of 10 and 100 microM were shown to markedly inhibit histamine release in cells stimulated with calcium ionophore A23187 or compound 48/80. PHF exerted inhibitory activity only at 100 microM. In the case of LTB(4), WG, WGS and PHF markedly inhibited LTB(4) production at the concentration of 100 microM. We also find that the increase in the IgE content induced by concanavalin A (ConA) was alleviated in the presence WG and WGS, while the inhibitory effect of PHF was much weaker. However, the magnitude of inhibitory effect observed on the content of lipid peroxidation induced by ConA was in order of PHF > WG > WGS, with PHF being the strongest. Interestingly, WG and WGS with the methoxyl group strongly inhibited histamine and IgE production, whereas PHF with the hydroxyl group in the B ring was much stronger than WG and WGS against lipid peroxidation. Based on data, it was concluded that the flavonoid components, WG, WGS, and PHF, may block a common pathway for the release of histamine and LTB(4), and that the IgE level is responsible for the lipid peroxidation induced by ConA.

Isotype switching by human B cells is division-associated and regulated by cytokines

Isotype switching by murine B cells follows a pattern whereby the proportion of cells undergoing switching increases with division number and is regulated by cytokines. Here we explored whether human B cells behaved in a similar manner. The effect of IL-4, IL-10, and IL-13, alone or in combination, on Ig isotype switching by highly purified naive human CD40 ligand (CD40L)-activated B cells was measured against division number over various harvest times. Switching to IgG was induced by IL-4 and, to a lesser extent, IL-13 and IL-10. The combination of IL-10 with IL-4, but not IL-13, induced a higher percentage of cells to undergo switching. Isotype switching to IgG by human CD40L-activated naive B cells was found to be linked to the division history of the cells: IgG(+) cells appeared in cultures of B cells stimulated with CD40L and IL-4 after approximately the third cell division, with the majority expressing IgG1, thus revealing a predictable pattern of IgG isotype switching. These results reveal a useful quantitative framework for monitoring the effects of cytokines on proliferation and isotype switching that should prove valuable for screening Ig immunodeficiencies and polymorphisms in the population for a better understanding of the regulation of human humoral immune responses.

IL-10 enhances B-cell IgE synthesis by promoting differentiation into plasma cells, a process that is inhibited by CD27/CD70 interaction

Interleukin-10 (IL-10) is a major regulatory cytokine of inflammatory responses that is considered to play an important role in specific immunotherapy. However, whether IL-10 enhances or inhibits B-cell IgE production has remained a matter of contention. To clarify the effect of IL-10 on IgE synthesis in the presence of IL-4 and CD40 signalling, we examined B-cell proliferation, germline epsilon transcripts and plasma cell differentiation. In addition, the effect of CD27 signalling on IgE synthesis in the presence of IL-10, IL-4 and CD40 signalling was investigated. IL-10 facilitated the production of IgE in mononuclear cells and highly purified B-cells, enhanced B-cell proliferation and, most importantly, promoted the generation of plasma cells. However, IL-10 did not enhance expression of germline epsilon transcripts. The addition of CD27 signalling through the use of CD32-CD27 ligand (CD70) double transfectants significantly diminished the B-cell proliferation, IgE synthesis and plasma cell differentiation enhanced by IL-10. IL-10 enhances B-cell IgE production by promoting differentiation into plasma cells. CD27/CD70 interactions under IL-10 and sufficient CD40 cosignalling exert the opposite effect on IgE synthesis. The results of this study indicate that precautions are critical when planning immunotherapy using IL-10 in IgE-related allergic diseases.

Recombinant Dirofilaria immitis polyprotein that stimulates murine B cells to produce nonspecific polyclonal immunoglobulin E antibody

Nonspecific immunoglobulin E (IgE) production is an event characteristically observed in parasitic helminth infections, but its mechanisms are still unclear. To define these mechanisms, we prepared a recombinant Dirofilaria immitis protein (rDiAg) and assessed its effect on nonspecific IgE production. rDiAg preferentially induced nonspecific IgE production, without eliciting specific IgE production, as well as a Th2-type cytokine profile (high interleukin-4 [IL-4] and IL-10 production but low gamma interferon production) in BALB/c mice. rDiAg significantly elicited the proliferative response of naive B cells. This response was not abolished by polymyxin B, an inhibitor of lipopolysaccharide (LPS), and rDiAg normally expanded splenic B cells from LPS nonresponder C3H/HeJ mice. Thus, the mitogenic effect of rDiAg was not due to LPS contamination. rDiAg also enhanced levels of CD23 expression on splenic B cells. Splenic B cells produced marked levels of IgE when cultured with the combination of rDiAg and IL-4 (rDiAg-IL-4), whereas peritoneal B cells produced negligible levels of IgE. rDiAg-IL-4-induced IgE production by splenic B cells was synergistically increased by coculture with peritoneal B cells. rDiAg-driven IL-10 secretion was higher in peritoneal B cells than in splenic B cells. IgE production by splenic B cells cocultured with peritoneal B cells was decreased to a level comparable to that by splenic B cells in the presence of a neutralizing anti-IL-10 monoclonal antibody. Collectively, these results suggest that rDiAg-induced polyclonal expansion and IgE class switching of splenic B cells contribute to nonspecific IgE production and that these responses are enhanced by peritoneal B-cell-derived IL-10.

Effect of ganhuangenin obtained from Scutellaria radix on the chemical mediator production of peritoneal exudate cells and immunoglobulin E level of mesenteric lymph node lymphocytes in Sprague-Dawley rats

We previously showed that ganhuangenin (GHG) has beneficial antioxidative properties against lipid peroxidation in tissues of Sprague-Dawley (SD) rats. In this study, the effect of GHG on immunoglobulin E (IgE), histamine and leukotriene B(4) (LTB(4)) levels of cells isolated from SD rats was examined with regard to the manifestation of the type I allergic reaction. We showed that GHG inhibited the IgE production of mesenteric lymph node (MLN) lymphocytes. In the presence or absence of concanavalin A (ConA), the concentration used did not exert a toxic effect against MLN lymphocytes. Interestingly, the increase in the IgE content and lipid peroxidation induced by ConA was alleviated in the presence of GHG. Moreover, GHG also inhibited histamine release from the peritoneal exudate cells stimulated with a calcium ionophore, A23187, or with the histamine releaser, compound 48/80. In the case of LTB(4), GHG markedly inhibited its release at a concentration of 100 microM. Thus, it is concluded that GHG may block the common pathway for the release of histamine and LTB(4), and that the IgE level is responsible for the lipid peroxidation induced by ConA.

CD23 shedding: requirements for substrate recognition and inhibition by dipeptide hydroxamic acids

CD23 (low affinity IgE receptor, FcepsilonRII) is expressed as a Type II extracellular protein on a variety of cells such as B cells, monocytes and macrophages and is cleaved from the cell surface to generate several distinct fragments. The expression of CD23 on the cell surface as well as the generation of soluble fragments of CD23 has been shown to be involved in regulation of IgE synthesis. CD23 is released from the cell surface by a metalloprotease, analogous to the cleavage of other cell surface molecules such as TNF-alpha. This activity has been extensively studied with respect to biochemical characterization and ability to cleave specific mutants of CD23. Both local sequence and distal domains have been shown to affect cleavage of CD23. Selective dipeptide hydroxamic acid inhibitors of CD23 processing have been identified and demonstrated to very potently and selectively inhibit CD23 processing.