Lycopene alleviates food allergy by modulating the PI3K/AKT pathway in peanut-sensitized BALB/c mice.

Food allergies, which lead to life-threatening acute symptoms, are considered an important public health problem. Therefore, it is essential to develop efficient preventive and treatment measures. We developed a crude peanut protein extract (PPE)-induced allergy mouse model to investigate the effects of lycopene on peanut allergy. Mice were divided into four groups: 5 mg/kg lycopene, 20 mg/kg lycopene, no treatment, and control groups. Serum inflammatory factors were detected using enzyme-linked immunosorbent assay. In addition, pathology and immunohistochemistry analyses were used to examine the small intestine of mice. We found that lycopene decreased PPE-specific immunoglobulin E (IgE) and IL-13 levels in the serum, relieved small intestine inflammation, attenuated the production of histamine and mouse mast cell protease-1, and downregulated PI3K and AKT1 expression in the small intestine tissues of mice allergic to peanuts. Our results suggest that lycopene can ameliorate allergy by attenuating the PI3K/AKT pathway and the anaphylactic reactions mediated by PPE-specific IgE.

Development of a tool predicting severity of allergic reaction during peanut challenge.

BACKGROUND: Reliable prognostic markers for predicting severity of allergic reactions during oral food challenges (OFCs) have not been established. OBJECTIVE: To develop a predictive algorithm of a food challenge severity score (CSS) to identify those at higher risk for severe reactions to a standardized peanut OFC. METHODS: Medical history and allergy test results were obtained for 120 peanut allergic participants who underwent double-blind, placebo-controlled food challenges. Reactions were assigned a CSS between 1 and 6 based on cumulative tolerated dose and a severity clinical indicator. Demographic characteristics, clinical features, peanut component IgE values, and a basophil activation marker were considered in a multistep analysis to derive a flexible decision rule to understand risk during peanut of OFC. RESULTS: A total of 18.3% participants had a severe reaction (CSS >4). The decision rule identified the following 3 variables (in order of importance) as predictors of reaction severity: ratio of percentage of CD63hi stimulation with peanut to percentage of CD63hi anti-IgE (CD63 ratio), history of exercise-induced asthma, and ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) ratio. The CD63 ratio alone was a strong predictor of CSS (P < .001). CONCLUSION: The CSS is a novel tool that combines dose thresholds and allergic reactions to understand risks associated with peanut OFCs. Laboratory values (CD63 ratio), along with clinical variables (exercise-induced asthma and FEV1/FVC ratio) contribute to the predictive ability of the severity of reaction to peanut OFCs. Further testing of this decision rule is needed in a larger external data source before it can be considered outside research settings. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02103270.

Human CD22 Inhibits Murine B Cell Receptor Activation in a Human CD22 Transgenic Mouse Model.

CD22, a sialic acid-binding Ig-type lectin (Siglec) family member, is an inhibitory coreceptor of the BCR with established roles in health and disease. The restricted expression pattern of CD22 on B cells and most B cell lymphomas has made CD22 a therapeutic target for B cell-mediated diseases. Models to better understand how in vivo targeting of CD22 translates to human disease are needed. In this article, we report the development of a transgenic mouse expressing human CD22 (hCD22) in B cells and assess its ability to functionally substitute for murine CD22 (mCD22) for regulation of BCR signaling, Ab responses, homing, and tolerance. Expression of hCD22 on transgenic murine B cells is comparable to expression on human primary B cells, and it colocalizes with mCD22 on the cell surface. Murine B cells expressing only hCD22 have identical calcium (Ca2+) flux responses to anti-IgM as mCD22-expressing wild-type B cells. Furthermore, hCD22 transgenic mice on an mCD22-/- background have restored levels of marginal zone B cells and Ab responses compared with deficiencies observed in CD22-/- mice. Consistent with these observations, hCD22 transgenic mice develop normal humoral responses in a peanut allergy oral sensitization model. Homing of B cells to Peyer's patches was partially rescued by expression of hCD22 compared with CD22-/- B cells, although not to wild-type levels. Notably, Siglec-engaging antigenic liposomes formulated with an hCD22 ligand were shown to prevent B cell activation, increase cell death, and induce tolerance in vivo. This hCD22 transgenic mouse will be a valuable model for investigating the function of hCD22 and preclinical studies targeting hCD22.

CD4(+) T cells from food allergy model are resistant to TCR-dependent apoptotic induction.

BACKGROUND: CD4(+) T cell polarization plays a critical role in the pathogenesis of allergy. How to modulate the skewed CD4(+) T cell polarization is less clear. The specific immunotherapy (SIT) is the only specific remedy for the treatment of allergic diseases; the therapeutic effect is to be improved. OBJECTIVES: This study aims to investigate the role of interleukin (IL)-18 in enhancing the therapeutic effect of SIT. METHODS: A peanut allergy mouse model was developed and treated with SIT or/and IL-18. CD4(+) T cell apoptosis was assessed by flow cytometry. The expression of Fas ligand (FasL) was observed by quantitative real time RT-PCR and Western blotting. Interferon-γ in the culture medium was determined by enzyme-linked immunosorbent assay. The fasL gene promoter methylation in CD4(+) T cells was assessed by methylation specific PCR. RESULTS: The results showed that lower levels of IL-18 were detected in allergic mice; administration of IL-18 significantly enhanced the therapeutic effect of SIT on suppressing the allergic inflammation in the mouse intestine. In the cell culture studies, IL-18 increased the TCR-dependent CD4(+) T cell apoptosis, the expression of FasL in CD4(+) T cells, the production of Interferon-γ and the demethylation of the FasL promoter in CD4(+) T cells. CONCLUSIONS: Administration of IL-18 enhances the effect of SIT on suppressing allergic inflammation in the mouse intestine via enhancing the TCR-dependent CD4(+) T cell apoptosis.

T helper cell IL-4 drives intestinal Th2 priming to oral peanut antigen, under the control of OX40L and independent of innate-like lymphocytes.

Intestinal T helper type 2 (Th2) immunity in food allergy results in IgG1 and IgE production, and antigen re-exposure elicits responses such as anaphylaxis and eosinophilic inflammation. Although interleukin-4 (IL-4) is critically required for allergic sensitization, the source and control of IL-4 during the initiation of Th2 immunity in vivo remains unclear. Non-intestinal and non-food allergy systems have suggested that natural killer-like T (NKT) or γδ T-cell innate lymphocytes can supply the IL-4 required to induce Th2 polarization. Group 2 innate lymphoid cells (ILCs) are a novel IL-4-competent population, but their contribution to initiating adaptive Th2 immunity is unclear. There are also reports of IL-4-independent Th2 responses. Here, we show that IL-4-dependent peanut allergic Th2 responses are completely intact in NKT-deficient, γδ T-deficient or ILC-deficient mice, including antigen-specific IgG1/IgE production, anaphylaxis, and cytokine production. Instead, IL-4 solely from CD4(+) Th cells induces full Th2 immunity. Further, CD4(+) Th cell production of IL-4 in vivo is dependent on OX40L, a costimulatory molecule on dendritic cells (DCs) required for intestinal allergic priming. However, both Th2 cells and ILCs orchestrated IL-13-dependent eosinophilic inflammation. Thus, intestinal Th2 priming is initiated by an autocrine/paracrine acting CD4(+) Th cell-intrinsic IL-4 program that is controlled by DC OX40L, and not by NKT, γδ T, or ILC cells.

Peanut-induced intestinal allergy is mediated through a mast cell-IgE-FcepsilonRI-IL-13 pathway.

BACKGROUND: Although implicated in the disease, the specific contributions of FcepsilonRI and IL-13 to the pathogenesis of peanut-induced intestinal allergy are not well defined. OBJECTIVES: We sought to determine the contributions of FcepsilonRI, IL-13, and mast cells to the development of intestinal mucosal responses in a murine model of peanut-induced intestinal allergy. METHODS: Sensitized wild-type (WT), FcepsilonRI-deficient (FcepsilonRI(-/-)), and mast cell-deficient (Kit(W-sh/W-sh)) mice received peanut orally every day for 1 week. Bone marrow-derived mast cells (BMMCs) from WT, FcepsilonRI(-/-), IL-4(-/-), IL-13(-/-), and IL-4/IL-13(-/-) mice were differentiated and transferred into WT, FcepsilonRI(-/-), and Kit(W-sh/W-sh) recipients. BMMCs from WT and UBI-GFP/BL6 mice were differentiated and transferred into WT and Kit(W-sh/W-sh) mice. Blockade of IL-13 was achieved by using IL-13 receptor alpha2 (IL-13Ralpha2)-IgG fusion protein. RESULTS: FcepsilonRI(-/-) mice showed decreased intestinal inflammation (mast cell and eosinophil numbers) and goblet cell metaplasia and reduced levels of IL4, IL6, IL13, and IL17A mRNA expression in the jejunum. Transfer of WT BMMCs to FcepsilonRI(-/-) recipients restored their ability to develop intestinal allergic responses unlike transfer of FcepsilonRI(-/-), IL-13(-/-), or IL-4/IL-13(-/-) BMMCs. FcepsilonRI(-/-) mice exhibited lower IL-13 levels and treatment of WT mice with IL-13 receptor alpha2 prevented peanut-induced intestinal allergy and inflammation. CONCLUSIONS: These data indicate that the development of peanut-induced intestinal allergy is mediated through a mast cell-dependent IgE-FcepsilonRI-IL-13 pathway. Targeting IL-13 might be a potential treatment for IgE-mediated peanut-induced allergic responses in the intestine.

Peanut- and cow's milk-specific IgE, Th2 cells and local anaphylactic reaction are induced in Balb/c mice orally sensitized with cholera toxin.

BACKGROUND: The development of animal models developing specific immunoglobulin (Ig)E presenting the same specificity as human IgE and similar clinical symptoms as those observed in allergic patients are of great interest for the understanding of mechanisms involved in the induction and regulation of food allergy. METHODS: Balb/c female mice were sensitized with whole peanut protein extract (WPPE) by means of intraperitoneal (i.p.) injections with alum or gavages with cholera toxin (CT). The WPPE specific IgE, IgG1 and IgG2a were monitored. Th2 cells activation was analysed assaying interleukin (IL)-4 and IL-5 vs IFNgamma on reactivated splenocytes. Local anaphylactic reaction was evaluated by assaying histamine in faecal samples. The oral sensitization protocol was further extended to cow's milk proteins (CMP). RESULTS: Balb/c mice developed high peanut-specific IgE and IgG1 responses either after i.p. or oral sensitizations. In both cases, antibodies were specific to polymer of glycinin fragments, containing polypeptides from Ara h3/4, and to a lesser extent to Ara h1 and Ara h2. Interleukin-4 and IL-5 production were evidenced. Balb/c mice could also be sensitized to CMP, as demonstrated by CMP-specific IL-4 and IL-5 secretions and induction of IgE specific for whole caseins, beta-lactoglobulin, serum bovine albumin and lactoferrin. Of interest was the occurrence of a local anaphylactic reaction in the peanut and CM models. CONCLUSIONS: In contrast with previous authors, Balb/c mice were sensitized and evidenced an allergic reaction after oral administrations of peanut or CMP plus CT, providing an interesting model for further studies on immunopathogenic mechanisms.