Rhinosinusitis derived Staphylococcal enterotoxin B plays a possible role in pathogenesis of food allergy

The role of food allergy in otolaryngology disorders

PURPOSE OF REVIEW

Food allergy is often an unrecognized clinical entity that has been implicated as a cause in many types of chronic inflammatory conditions. This review serves to provide an update on how food allergy plays a role in otolaryngology disorders.

RECENT FINDINGS

The incidence of food allergy has been on the rise over the last decade. Currently, about 6% of children and 3-4% of adults are thought to be affected by food allergy. The middle and inner ear are immunologically responsive and this includes responsiveness to food hypersenstivities. Both chronic otitis media with effusion and Meniere's disease can improve with treatment of food allergies. Some evidence supports a link between rhinitis and nasal polyps and food allergies. Finally, there is increasing literature about eosinophilic esophagitis, which is a relatively newly recognized disease with many otolaryngologic associations. Many of these patients may have food allergy, and treatment of their food allergy may be effective in treating the disease.

SUMMARY

In chronic inflammatory disorders of the head and neck, especially those involving the upper aerodigestive tract, food allergy must be considered in the differential. Patients with food allergy often do not respond to conventional treatments, and it can often be a challenge to arrive at the proper diagnosis. Further research is warranted to improve our understanding of the role of food allergy in otolaryngology disorders, as well as our diagnostic and treatment methods.

Staphylococcal enterotoxin B-derived haptens promote sensitization

T helper 2 (Th2) polarization is a major pathological feature in allergic diseases; its etiology is not fully understood. This study aims to elucidate the adjuvant effect of the microbial product-derived small peptides in the initiation of antigen-specific Th2 polarization. In this study, a clinical survey of patients with chronic rhinosinusitis (CRS) and food allergy (FA) was carried out. The Staphylococcal enterotoxin B (SEB)-derived small peptides (Ssps) were examined in the human stool extracts. The formation of Ssp/antigen adducts was tested in a protein-protein combination assay. The bone marrow-derived dendritic cells (BMDCs) were employed to test the role of Ssp/ovalbumin (OVA) adducts in the dendritic cell (DC) maturation. A mouse model was developed to test the role of Ssp/OVA adducts in the initiation of Th2 polarization in the intestine. The results showed that 54 (18.2%) patients with FA were diagnosed among 296 patients with SEB(+) CRS; only eight (2.9%) FA patients were identified among 272 patients with SEB(-) CRS. Ssps were detected in the stool protein extracts from FA patients with SEB(+) CRS, but not in those with SEB(-) CRS. Ssp/OVA adducts induced DC maturation, speeded up DC migration, activated CD4(+) T cells in the regional lymph nodes and induced skewed Th2 polarization in the local tissue. We conclude that patients with SEB(+) CRS are prone to suffering from FA. SEB can be degraded to Ssps in the gastrointestinal tract. The Ssps can bind macromolecular antigens to form adducts to promote the antigenicity of the antigens and induction of the antigen-specific Th2 polarization and inflammation in the local tissue.

Staphylococcal-derived superantigen enhances peanut induced Th2 responses in the skin

BACKGROUND

The allergen-induced activation and expansion of IL-4 producing T helper type 2 (Th2) cells is a key event in the initiation and progression of allergic disease. Intriguingly, concomitant early childhood staphylococcal skin infections are being increasingly implicated in the allergen-induced switch of primary T cell responses towards the Th2 phenotype.

OBJECTIVE

We sought to identify whether or not staphylococcal-derived superantigen can influence the primary T cell response in the skin to food allergens with a view to determining whether such exposures create the immune pathology that predisposes to the development of food allergy.

METHODS

Using a novel Th2 reporter model, we determined the ability of the staphylococcal superantigen (SEB) to influence priming in the skin of IL-4 expressing Th2 cells by peanut extract (PE). Factors including the effect of SEB on the magnitude of the Th2 response in the skin draining lymph nodes, T cell receptor V region usage and the influence of endotoxin were evaluated.

RESULTS

Primary exposure to PE and SEB lead to significantly enhanced PE specific Th2 responses when the mice were subsequently exposed to PE alone. The enhancement of the Th2 response was dependent on the Vβ-binding properties of the SEB, but was not affected by endotoxin-mediated TLR-4 effects or strain differences in the mice.

CONCLUSIONS AND CLINICAL RELEVANCE

These results identify that in the skin environment, the presence of SEB can significantly increase the numbers of allergen-induced Th2 cells which develop in response to subsequent allergen exposure. These data highlight the process by which individuals may become pathologically sensitized to food allergens in early life.

TIM4 modulates antigen-specific Th2 cell differentiation in mice with food allergy

AIM: To evaluate the modulatory effect of microbial products on the expression of T cell immunoglobulin and mucin domain 4 (TIM4) in dendritic cells (DCs) and to determine the role of TIM4 in modulating CD4+ T cell activation in allergic response induced by exposure to microbial products.

METHODS: Bone marrow-derived DCs were isolated from Balb/c mice and cultured in vitro. Cultured DCs were divided into control group and Staphylococcal enterotoxin B (SEB)-stimulated group. The expression of TIM4 mRNA in different groups of DCs was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of CD11c, MHC-II and CD86 on DCs were measured by flow cytometry. DCs co-cultured with CD4+ T cells in vitro were divided into five groups: control group, SEB group, OVA group, SEB plus ovalbumin (OVA) group, and anti-TIM4 antibody plus SEB and OVA group. Different sets of DCs were co-cultured for 48 h with CD4+ T cells that were obtained from the spleen of allergic mice. Levels of interleukin-4 (IL-4) and interferon-γ (IFN-γ) in culture medium were evaluated by enzyme-linked immunosorbent assay (ELISA).

RESULTS: Compared with the control group, the expression of TIM4 mRNA in DCs was increased significantly in the SEB-stimulated group (0.941 ± 0.018 vs 0.422 ± 0.083, P < 0.05), and SEB up-regulated the expression of TIM-4 in a dose-dependent manner. SEB stimulation also significantly increased the expression of MHC-II and the costimulatory molecule CD86 on DCs compared with control cells (MHC-II: 76.684% ± 3.1803% vs 52.984% ± 3.6026%, P = 0.000; CD86: 89.746% ± 2.113% vs 67.558% ± 0.4341%, P = 0.000). Compared with control DCs co-cultured with CD4+ T cells, the level of IL-4 in culture medium increased significantly (295.834 ± 20.408 vs 78.335 ± 13.109, P < 0.05) and that of IFN-γ decreased significantly (362.109 ± 92.271 vs 761.897 ± 102.967, P < 0.05) in the SEB plus OVA group. The levels of IL-4 and IFN-γ in the SEB group and OVA group showed no significant differences with those in the control group. In contrast, the expression level of IL-4 was significantly lower and that of IFN-γ was significantly higher in the anti-TIM4 antibody group than in the SEB plus OVA group (P < 0.05). The levels of IL-4 and IFN-γ in the anti-TIM4 antibody group showed no significant differences with those in the control group, SEB group and OVA group (90.511 ± 15.500 vs 295.834 ± 20.408; 807.734 ± 95.436 vs 362.109 ± 92.271, both P < 0.05).

CONCLUSION: TIM4 is involved in the pathogenesis of food allergy induced by concurrent exposure to microbial products and food antigen. Inhibition of TIM4 expression can significantly inhibit Th2 cell polarization, effectively correct Th1/Th2 imbalance and thereby prevent the development of allergic reaction.

TIM4 and TIM1 modulate the function of CD4+CD25+ T regulatory cells in mice with food allergy

AIM: To evaluate the function of T regulatory (Treg) cells and determine the role of T cell immunoglobulin and mucin domain-containing protein 4 (TIM4) and TIM1 in modulating the function of Treg cells in mice with food allergy.

METHODS: Thirty-two BALB/c mice fed an ovalbumin (OVA)-free diet were randomly and equally divided into four groups: normal saline (NS) group, staphylococcal enterotoxin B (SEB) plus OVA group, anti-TIM1 antibody plus SEB and OVA group, and anti-TIM4 antibody plus SEB and OVA group. Mice in the four groups were sensitized by intraperitoneal injections of NS, SEB/OVA, anti-TIM1/SEB/OVA, and anti-TIM4/SEB/OVA on days 0, 3 and 9, respectively. All mice (except the NS group) were challenged by intraperitoneal injections of SEB/OVA on days 7 and 14, respectively. The expression of forkhead box P3 (FOXP3) mRNA in the jejunum and spleen and TIM4 mRNA in the jejunum was measured by reverse transcription-polymerase chain reaction (RT-PCR). The levels of transforming growth factor β1 (TGF-β1) and interleukin-10 (IL-10) in the serum were analyzed by enzyme-linked immunosorbent assay (ELISA). The expression of TGF-β1 and IL-10 proteins in the jejunum was detected by immunohistochemistry.

RESULTS: Compared with the NS group, the expression levels of FOXP3 mRNA in the jejunum and spleen significantly decreased (0.401 ± 0.145 vs 0.732 ± 0.162 and 0.407 ± 0.082 vs 0.691 ± 0.145, respectively; both P < 0.05), the expression level of TIM4 mRNA increased significantly (P < 0.05), and the levels of TGF-β1 in the serum and jejunum decreased significantly (7859.853 ± 126.704 ng/L vs 8342.814 ± 488.461 ng/L and 108.834 ± 9.634 ng/L vs 156.298 ± 12.002 ng/L, respectively; both P < 0.05) in the SEB/OVA group. In contrast, the expression levels of FOXP3 mRNA in the jejunum and spleen and TGF-β1 in the serum and jejunum were significantly higher in the anti-TIM1/SEB/OVA and anti-TIM4/SEB/OVA groups than in the SEB/OVA group (all P < 0.05).

CONCLUSION: Treg cells in SEB/OVA-sensitized mice are dysfunctional. Pretreatment with anti-TIM1 or anti-TIM4 can restore the function of Treg cells, suggesting that the TIM4-TIM1 pathway may play a key role in the development of food allergy.

Concurrent exposure to microbial products and food antigens triggers initiation of food allergy

It is estimated that as much as 6-8% population suffers from food allergy or food antigen-related disorders. The prevalence keeps rising. So far we do not have identified remedy to treat food allergy. Avoidance of the offending food is the only effective method currently. Skewed T helper 2 polarization is one of the major feature in the pathogenesis of food allergy. However, the causative mechanism in the initiation of food allergy remains to be further understood. Research in food allergy has got giant advance in recent years. Several animal models have been established and used in food allergy study. One of the common features of these food allergy animal models is that most of them require using microbial products as adjuvant to sensitize animals. This review documents the recent advance in the mechanistic study on concurrent use of microbial products and food antigens to study food allergy.

Impact of innate immunity in a subset of children with autism spectrum disorders: a case control study

Background

Among patients with autism spectrum disorders (ASD) evaluated in our clinic, there appears to be a subset that can be clinically distinguished from other ASD children because of frequent infections (usually viral) accompanied by worsening behavioural symptoms and/or loss/decrease in acquired skills. This study assessed whether these clinical features of this ASD subset are associated with atopy, asthma, food allergy (FA), primary immunodeficiency (PID), or innate immune responses important in viral infections.

Methods

This study included the ASD children described above (ASD test, N = 26) and the following controls: ASD controls (N = 107), non-ASD controls with FA (N = 24), non-ASD controls with chronic rhinosinusitis/recurrent otitis media (CRS/ROM; N = 38), and normal controls (N = 43). We assessed prevalence of atopy, asthma, FA, CRS/ROM, and PID. Innate immune responses were assessed by measuring production of proinflammatory and counter-regulatory cytokines by peripheral blood mononuclear cells (PBMCs) in response to agonists of Toll-like receptors (TLRs), with or without pre-treatment of lipopolysaccharide (LPS), a TLR4 agonist.

Results

Non-IgE mediated FA was equally prevalent in both ASD test and ASD control groups, occurring at higher frequency than in the non-ASD controls. Allergic rhinitis, atopic/non-atopic asthma, and atopic dermatitis were equally prevalent among the study groups except for the CRS/ROM group in which non-atopic asthma was more prevalent (52.6%). CRS/ROM and specific polysaccharide antibody deficiency (SPAD) were more prevalent in the ASD test group than in the ASD control, FA, and normal control groups: 23.1% vs. < 5% for CRS/ROS and 19.2% vs. < 1% for SPAD. However, CRS/ROM patients had the highest prevalence of SPAD (34.2%). When compared to ASD and normal case controls, PBMCs from 19 non-SPAD, ASD test group children produced: 1) less IL-1β with a TLR7/8 agonist, less IL-10 with a TLR2/6 agonist, and more IL-23 with a TLR4 agonist without LPS pre-treatment, and 2) less IL-1β with TLR4/7/8 agonists with LPS pre-treatment. These are cytokines associated with the neuro-immune network.

Conclusion

Clinical features of the ASD test group were not associated with atopy, asthma, FA, or PID in our study but may be associated with altered TLR responses mediating neuro-immune interactions.

Impairing oral tolerance promotes allergy and anaphylaxis: a new murine food allergy model

BACKGROUND

Food allergy is a disorder in which antigenic food proteins elicit immune responses. Animal models of food allergy have several limitations that influence their utility, including failure to recapitulate several key immunologic hallmarks. Consequently, little is known regarding the pathogenesis and mechanisms leading to food allergy. Staphylococcus aureus-derived enterotoxins, a common cause of food contamination, are associated with antigen responses in atopic dermatitis.

OBJECTIVE

We hypothesized that S aureus-derived enterotoxins might influence the development of food allergy. We examined the influence of administration of staphylococcal enterotoxin B (SEB) with food allergens on immunologic responses and compared these responses with those elicited by a cholera toxin-driven food allergy model.

METHODS

Oral administration of ovalbumin or whole peanut extract with or without SEB was performed once weekly. After 8 weeks, mice were challenged with oral antigen alone, and the physiologic and immunologic responses to antigen were studied.

RESULTS

SEB administered with antigen resulted in immune responses to the antigen. Responses were highly T(H)2 polarized, and oral challenge with antigen triggered anaphylaxis and local and systemic mast cell degranulation. SEB-driven sensitization induced eosinophilia in the blood and intestinal tissues not observed with cholera toxin sensitization. SEB impaired tolerance specifically by impairing expression of TGF-beta and regulatory T cells, and tolerance was restored with high-dose antigen.

CONCLUSIONS

We demonstrate a new model of food allergy to oral antigen in common laboratory strains of mice that recapitulates many features of clinical food allergy that are not seen in other models. We demonstrate that SEB impairs oral tolerance and permits allergic responses.

Influence of food allergy on gut barrier function and CD4+CD25+ regulatory T cells in food allergic mice

AIM: To investigate the gut barrier functional changes of ovalbumin-induced allergic mice and to determine whether there is bacteria translocation; and to observe changes of CD4⁺CD25⁺ regulatory T cells in FA mice spleen in order to shed light on relationship between CD4⁺CD25⁺ regulatory T cells and food allergy.

METHODS: Twenty BALB/c mice on ovalbulmin (OVA)-free diet were randomly divided into experimental group and control group. The mice in experimental group were sensitized with OVA while mice in control group were given normal saline (NS). The intestinal microbial flora was detected by culturing the feces. The secretory immunoglobulin A (sIgA) in intestinal mucus and the diamine oxidase (DAO) in blood serum were analyzed using ELISA. The mesenteric lymph nodes (MLN), homogenated tissues of livers, lungs, kidneys, and NS used for peritoneal lavage were cultured to determine bacterial translocation. The number of CD4⁺CD25⁺ regulatory T cells (CD4⁺CD25⁺ Treg cells) in spleens was estimated using flow cytometry.

RESULTS: The number of probiotics in experimental group was significantly lower than that of the control group (Lactobacillus: P = 0.006; Bifidobacterium: P = 0.016). In contrast, the number of conditional pathogenic bacteria was significantly higher than that of control group (Escherichia coli: P = 0.001; Bacteroides: P = 0.001). Compared with the control group, sIgA (0.107 ± 0.012 vs 0.086 ± 0.008, P = 0.001) in intestinal mucus, DAO (0.357 ± 0.025 vs 0.179 ± 0.035, P = 0.001) in blood serum and frequency of bacteria translocation (47.8% vs 15.6%, P = 0.001) were significantly higher in experimental group. The number of CD4⁺CD25⁺ Treg cells was significantly lower in experimental group (4.350% ± 0.619% vs 6.488% ± 2.313%, P = 0.001).

CONCLUSION: Intestinal flora imbalance and high intestinal permeability in ovalbumin-induced allergic mice suggest gut barrier dysfunction. The phenomenon of bacteria translocation is verified in FA mice. Down-regulation of CD4⁺CD25⁺ Treg cells may play an important role in food allergy.