Search Results (51)

Specific venom immunotherapy (VIT) in patients with hymenoptera venom allergy (HVA) represents a well-studied approach to reduce the severity of a possible anaphylactic reaction. Currently, data on mechanisms of tolerance induction at the cellular level within the first hours of therapy are lacking. To address this, total and unoccupied high-affinity IgE receptor (FcεRI) numbers per basophil, soluble FcεRI (sFcεRI) and serum tryptase levels were measured before and after the first day of VIT induction in HVA patients. Additionally, basophil activation tests (BATs) were performed at those time points. In the early phase of VIT induction, no significant change in total FcεRI receptor density on basophils was observed, but a significant increase in unoccupied FcεRI was noticeable, predominantly in patients with high total IgE and low baseline unoccupied FcεRI density. No meaningful difference in serum tryptase levels or sFcεRI levels was observed after VIT induction. BATs showed heterogeneous results, often unchanged before and after VIT (in 47% of the cases), sometimes increased (in 40%) and only rarely decreased EC₅₀ sensitivity (in 13%). Changes in the BAT EC₅₀ correlated with FcεRI receptor density changes in basophils. In summary, VIT induction led to an increased ratio of unoccupied-to-total FcεRI without notable tryptase or sFcεRI serum elevation, pointing towards subthreshold cell activation with receptor internalization and recycling. However, the mostly unchanged or even increased basophil sensitivity in EC₅₀ calls for further research to clarify the clinical relevance of these rapid receptor modulations. Full article

High-affinity IgE receptors (FcεRI) are expressed on human blood eosinophils and may be upregulated on eosinophils at sites of allergic inflammation including atopic dermatitis and allergic asthma. FcεRI engagement, however, fails to elicit “effector” responses from eosinophils. Thus, a functional role for FcεRI on eosinophils has been uncertain. We evaluated the role of FcεRI in enhancing eosinophil antigen presentation in vivo by using humanized FcεRI α chain (hFcεRIα) transgenic mice. Eosinophils from hFcεRIα transgenic mice expressed humanized FcεRIα, with higher levels of eosinophils from the bronchoalveolar lavage of experimental asthma than those from polymyxin-elicited peritoneal lavage. The hFcεRIα-bearing eosinophils instilled intratracheally (i.t.) into recipient wild-type mice migrated from airways into paratracheal lymph nodes (pLNs) and spleens. Eosinophils, pretreated in vitro with nitrophenyl-ovalbumin ((NP)-OVA) and anti-NP human IgE complexes and instilled i.t., presented NP antigen via hFcεRIα to T cells more effectively than those pretreated with NP-OVA only, as assessed by pLN cell proliferation. IgE/FcεRIα-facilitated eosinophil antigen presentation resulted in increased IL-4 but not INF-γ production by pLN cells, with a bias towards Th2 cytokine production. Furthermore, cross-linking hFcεRIα on eosinophils increased eosinophil expressions of T cell costimulatory proteins CD40, CD80, and CD86. Humanized FcεRIα on murine eosinophils functions to enhance eosinophil antigen presentation capacities by mediating IgE-facilitated antigen presentation and upregulating expression of requisite T cell costimulatory proteins. Thus, a functional, non-“effector” role for FcεRI on eosinophils is revealed through identifying a means by which IgE may act on eosinophils to mediate their immunomodulatory, enhanced antigen presentation capabilities. Full article

(i) Background: The increasing prevalence of allergic diseases highlights the need for effective treatments. Lonicera caerulea fruit has been recognized for its anti-inflammatory, anti-cancer, and neuroprotective effects, but the mechanisms underlying its anti-allergic properties remain unclear. (ii) Objective: This study aims to evaluate the total phenolic, total flavonoid, and cyanidin-3-glucoside (C3G) contents of Lonicera caerulea extract (HR2302-30E) and to investigate its antioxidant and anti-allergic activities. (iii) Methods: Using an IgE-stimulated RBL-2H3 cell model, we assessed the effects of HR2302-30E and C3G on mast cell degranulation, β-hexosaminidase and histamine release. Western blot analysis was performed to evaluate the expression of high-affinity IgE receptor (FcεRI)β/γ and the phosphorylation of Src family kinases (Syk, Fyn). We also examined the phosphorylation of downstream factors phospholipase Cγ, protein kinase Cδ, and mitogen-activated protein kinase. (iv) Results: Total phenolic, flavonoid, and C3G contents of HR2302-30E were 18.73 mg GAE/g, 11.83 mg QE/g, and 7.02 mg/g, respectively. In IgE-activated mast cells, HR2302-30E and C3G inhibited β-hexosaminidase and histamine release. Western blot analysis revealed reduced expression of FcεRIβ/γ and decreased phosphorylation of key downstream signaling molecules. Conclusions: These findings suggest that HR2302-30E and C3G modulate FcεRI signaling, indicating their potential as natural anti-allergic agents. Full article

The specific detection of serum IgE antibodies specific to allergens (sIgE Abs) that can crosslink the plural high-affinity IgE receptor (FcεRIα) molecules on the surface of mast cells or basophils with a multivalent allergen can reduce the false-positive diagnoses observed in chemiluminescent and fluorescence enzyme immunoassays for type-I allergic patients. In this study, we detected sIgE Abs to the egg-allergen ovalbumin (OVA) and the wheat-allergen gluten in the sera of rats sensitized with each allergen using an amplified luminescence proximity homogeneous assay by crosslinking (AlphaCL). OVA and gluten were reacted with each sIgE Ab in the sera. Then, acceptor and donor beads labeled with the human FcεRIα were added to the reacted solution. The luminescence intensity for anti-OVA IgE Abs in the sera with the removal of IgG Abs was observed in five of seven (71.4%) of the sensitized rats, whereas no signals were observed in any of the unsensitized rats. The AlphaCL could also detect anti-gluten sIgE Abs in the sera of sensitized rats, but not of unsensitized rats. In conclusion, we successfully detected sIgE Abs in the sera of rats sensitized to two allergens using the AlphaCL. This detection method has the potential to be used as a new diagnostic tool for type-I allergic patients. Full article

The high-affinity IgE receptor, FcεRI, is typically associated with type 2 effectors such as mast cells (MC). The relatively unique expression profile of FcεRI and accumulating evidence from pre-clinical and clinical settings, such as MC interactions with tumors, have led us to study MCs as a potential therapeutic target in breast cancer. Our work identified MCs interacting with tumor cells at primary sites using the 4T1 (BALB/c) adenocarcinoma model in vivo. However, this analysis was complicated by a surprising finding that the tumor cells intrinsically and strongly expressed FcεRI. We further studied the expression and function of FcεRI in breast cancer cells in vitro. The 4T1 cells expressed FcεRI to a level similar to mouse bone marrow-derived MC (BMMC). Additionally, two established breast cancer cultures derived from human T-47D cells, one estrogen-dependent (E3) and the other estrogen-withdrawn (EWD8), also expressed FcεRI with EWD8 cells showing the greatest abundance. Functional analyses indicated that IgE-mediated antigen stimulation did not elicit classic Ca²⁺ flux in breast cancer cells as seen in the respective species’ MCs; however, FcεRI crosslinking could stimulate IL-6 production from the T-47D derivatives. Preliminary analysis of primary breast cancer biopsy datasets using R2: Genomics Analysis and Visualization Platform was discordant with our in vivo model and in vitro observations. Indeed, FcεRI mRNA abundance declined in metastatic breast cancers compared to non-cancerous breast tissue. Altogether, we report a previously unidentified and immunologically substantive difference between breast cancer models and human primary tumors. Investigators pursuing FcεRI-relevant therapeutics in this context should be aware of this translational barrier. Full article

Immunoglobulin E (IgE) plays a critical role for the immune system, fighting against parasites, toxins, and cancer. However, when it reacts to allergens without proper regulation, it can cause allergic reactions, including anaphylaxis, through a process initiated by effector cells such as basophils and mast cells. These cells display IgE on their surface, bound to the high-affinity IgE receptor FcεRI. A cross-linking antigen then triggers degranulation and the release of inflammatory mediators from the cells. Therapeutic monoclonal anti-IgE antibodies such as omalizumab, disrupt this process and are used to manage IgE-related conditions such as severe allergic asthma and chronic spontaneous urticaria. Interestingly, naturally occurring anti-IgE autoantibodies circulate at surprisingly high levels in healthy humans and mice and may thus be instrumental in regulating IgE activity. Although many open questions remain, recent studies have shed new light on their role as IgE regulators and their mechanism of action. Here, we summarize the latest insights on natural anti-IgE autoantibodies, and we compare their functional features to therapeutic monoclonal anti-IgE autoantibodies. Full article

Anti-interleukin (IL) 5 is an effective treatment modality for inhibiting eosinophilic inflammation in patients with T2-high severe asthma. The aim of this study was to determine the clinical efficacy and serum levels of type 2 inflammatory mediators during 24 weeks of mepolizumab treatment in patients with T2-high severe asthma. Eighteen patients with T2-high severe asthma were enrolled in this study. All patients received 100 mg of mepolizumab subcutaneously every 4 weeks and were retested at 4, 12, and 24 weeks. A clinical examination, asthma control test (ACT), and spirometry were performed; fractional exhaled nitric oxide (Fe_NO) levels were evaluated; and blood samples were drawn at every visit. Type 2 inflammation mediator levels were measured using enzyme-linked immunosorbent assay (ELISA). The blood eosinophil level significantly decreased, the ACT score and FEV₁ increased after 4 weeks of mepolizumab treatment with the same tendency after 12 and 24 weeks (p < 0.05), and the Fe_NO level did not change (p > 0.05). A total of 27.8% of patients reached clinical remission criteria after 24 weeks of mepolizumab treatment. IL-33 and eotaxin significantly increased (p < 0.05) while IL-5, IL-13, thymic stromal lymphopoietin (TSLP), soluble IL-5 receptor subunit alpha (sIL-5Rα), and soluble high-affinity immunoglobulin E receptor (sFcεRI) decreased, with the same tendency after 12 and 24 weeks (p < 0.05). The serum levels of immunoglobulin (Ig) E and IL-4 and IL-25 levels did not change during mepolizumab treatment compared to baseline (p > 0.05). In conclusion, treatment with mepolizumab over 24 weeks improved lung function and asthma control in T2-high severe asthma patients, with nearly one-third achieving clinical remission criteria, and affected the balance of type 2 inflammatory mediators. Full article

The significant role of mast cells in the development of allergic and inflammatory diseases is well-established. Among the various mechanisms of mast cell activation, the interaction of antigens/allergens with IgE and the subsequent binding of this complex to the high-affinity IgE receptor FcεRI stand out as the most studied and fundamental pathways. This activation process leads to the rapid exocytosis of granules containing preformed mediators, followed by the production of newly synthesized mediators, including a diverse array of cytokines, chemokines, arachidonic acid metabolites, and more. While conventional approaches to allergy control primarily focus on allergen avoidance and the use of antihistamines (despite their associated side effects), there is increasing interest in exploring novel methods to modulate mast cell activity in modern medicine. Recent evidence suggests a role for autophagy in mast cell activation, offering potential avenues for utilizing low-molecular-weight autophagy regulators in the treatment of allergic diseases. More specifically, mitochondria, which play an important role in the regulation of autophagy as well as mast cell activation, emerge as promising targets for drug development. This review examines the existing literature regarding the involvement of the molecular machinery associated with autophagy in FcεRI-dependent mast cell activation. Full article

Food allergies are common worldwide and have become a major public health concern; more than 220 million people are estimated to suffer from food allergies worldwide. On the other hand, polyphenols, phenolic substances found in plants, have attracted attention for their health-promoting functions, including their anti-allergic effects. In this study, we examined the potential inhibitory effects of 80% ethanol extracts from 22 different vegetables on the degranulation process in RBL-2H3 cells. Our aim was to identify vegetables that could prevent and treat type I allergic diseases. We found strong inhibition of degranulation by extracts of perilla and chives. Furthermore, we verified the respective efficacy via animal experiments, which revealed that the anaphylactic symptoms caused by ovalbumin (OVA) load were alleviated in OVA allergy model mice that ingested vegetable extracts of perilla and chives. These phenomena were suggested to be caused by induction of suppression in the expression of subunits that constitute the high-affinity IgE receptor, particularly the α-chain of FcεR I. Notably, the anti-allergic effects of vegetables that can be consumed daily are expected to result in the discovery of new anti-immediate allergenic drugs based on the components of these vegetables. Full article

Multiple myeloma (MM) is an incurable malignancy of plasma cells and the second most common hematologic malignancy in the United States. Although antibodies in clinical cancer therapy are generally of the IgG class, antibodies of the IgE class have attractive properties as cancer therapeutics, such as their high affinity for Fc receptors (FcεRs), the low serum levels of endogenous IgE allowing for less competition for FcR occupancy, and the lack of inhibitory FcRs. Importantly, the FcεRs are expressed on immune cells that elicit antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), and/or antigen presentation such as mast cells, eosinophils, macrophages, and dendritic cells. We now report the development of a fully human IgE targeting human CD38 as a potential MM therapy. We targeted CD38 given its high and uniform expression on MM cells. The novel anti-CD38 IgE, expressed in mammalian cells, is properly assembled and secreted, exhibits the correct molecular weight, binds antigen and the high affinity FcεRI, and induces degranulation of FcεRI expressing cells in vitro and also in vivo in transgenic BALB/c mice expressing human FcεRIα. Moreover, the anti-CD38 IgE induces ADCC and ADCP mediated by monocytes/macrophages against human MM cells (MM.1S). Importantly, the anti-CD38 IgE also prolongs survival in a preclinical disseminated xenograft mouse model using SCID-Beige mice and human MM.1S cells when administered with human peripheral blood mononuclear cells (PBMCs) as a source of monocyte effector cells. Our results suggest that anti-CD38 IgE may be effective in humans bearing MM and other malignancies expressing CD38. Full article

Proteomics in respiratory allergic diseases has such a battery of techniques and programs that one would almost think there is nothing impossible to find, invent or mold. All the resources that we document here are involved in solving problems in allergic diseases, both diagnostic and prognostic treatment, and immunotherapy development. The main perspectives, according to this version, are in three strands and/or a lockout immunological system: (1) Blocking the diapedesis of the cells involved, (2) Modifications and blocking of paratopes and epitopes being understood by modifications to antibodies, antagonisms, or blocking them, and (3) Blocking FcεRI high-affinity receptors to prevent specific IgEs from sticking to mast cells and basophils. These tools and targets in the allergic landscape are, in our view, the prospects in the field. However, there are still many allergens to identify, including some homologies between allergens and cross-reactions, through the identification of structures and epitopes. The current vision of using proteomics for this purpose remains a constant; this is also true for the basis of diagnostic and controlled systems for immunotherapy. Ours is an open proposal to use this vision for treatment. Full article

Signal transduction by the high-affinity IgE receptor (FcεRI) depends on membrane lipid and protein compartmentalization. Recently published data show that cells treated with 1-heptanol, a cell membrane fluidizer, exhibit changes in membrane properties. However, the functional consequences of 1-heptanol-induced changes on mast cell signaling are unknown. This study shows that short-term exposure to 1-heptanol reduces membrane thermal stability and dysregulates mast cell signaling at multiple levels. Cells treated with 1-heptanol exhibited increased lateral mobility and decreased internalization of the FcεRI. However, this did not affect the initial phosphorylation of the FcεRI-β chain and components of the SYK/LAT1/PLCγ1 signaling pathway after antigen activation. In contrast, 1-heptanol inhibited SAPK/JNK phosphorylation and effector functions such as calcium response, degranulation, and cytokine production. Membrane hyperfluidization induced a heat shock-like response via increased expression of the heat shock protein 70, increased lateral diffusion of ORAI1-mCherry, and unsatisfactory performance of STIM1-ORAI1 coupling, as determined by flow-FRET. Furthermore, 1-heptanol inhibited the antigen-induced production of reactive oxygen species and potentiated stress-induced plasma membrane permeability by interfering with heat shock protein 70 activity. The combined data suggest that 1-heptanol-mediated membrane fluidization does not interfere with the earliest biochemical steps of FcεRI signaling, such as phosphorylation of the FcεRI-β chain and components of the SYK/LAT/PLCγ1 signaling pathway, instead inhibiting the FcεRI internalization and mast cell effector functions, including degranulation and cytokine production. Full article

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by daily or almost daily recurring skin edema and flare with itch and pruritus anywhere on the body for more than 6 weeks. Although basophil- and mast cell-released inflammatory mediators, such as histamine, play important roles in the pathogenesis of CSU, the detailed underlying mechanism is not clear. Since several auto-antibodies, IgGs which recognize IgE or the high-affinity IgE receptor (FcεRI) and IgEs against other self-antigens, are detected in CSU patients, they are considered to activate both mast cells in the skin and basophils circulating in the blood. In addition, we and other groups demonstrated that the coagulation and complement system also contribute to the development of urticaria. Here, we summarized the behaviors, markers and targets of basophils in relation to the coagulation–complement system, and for the treatment of CSU. Full article

Chronic spontaneous urticaria (CSU) is defined as the almost daily occurrence of widespread wheals, angioedema, or both, for more than 6 weeks. It affects 1–2% of the general population, with a higher prevalence in female patients, and is more frequent patients over 20 years of age. More than half of all cases of chronic idiopathic urticaria are thought to occur due to an autoimmune mechanism, specifically the production of autoantibodies against the high-affinity immunoglobulin E (IgE) receptor (FcεRI). The quality of life in these patients is often greatly compromised, also due to the onset of comorbidities represented by other autoimmune diseases, such as thyroid disease, rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s syndrome, celiac disease, and type 1 diabetes, among others. This review aimed to analyze the close correlation between CSU and some autoimmune and autoinflammatory diseases, in order to encourage a multidisciplinary and multimorbid approach to the patient affected by CSU, which allows not only control of the natural course of the disease, but also any associated comorbidities. Full article

Background: Chronic spontaneous urticaria (CSU) is defined as the recurrence of unprovoked transient wheals and itch for more than 6 weeks. Currently, there is an unmet need concerning response prediction in CSU. The present study investigated biomarkers of type I and type IIb autoimmunity as potential predictors of response to omalizumab in CSU. Materials and methods: Differences in levels of IgG and IgE autoantibodies targeting the high- and low-affinity IgE receptors (FcεRI and FcεRII, respectively), as well as spontaneous and specifically triggered leukotriene C (LTC)4 release by basophils from the investigated subjects, were evaluated in 18 consecutive, prospectively enrolled CSU patients and 18 age- and sex-matched, healthy non-atopic controls. Results: The patients with CSU had higher levels of anti-FcεRI IgE (542 (386.25–776.5) vs. 375 (355–418), optical density (OD), p = 0.008), and IgG (297 (214.5–431.25) vs. 193.5 (118–275) OD, p = 0.004) autoantibodies relative to the controls. Simultaneous anti-FcεRI IgG and IgE positivity (i.e., both autoantibody levels above the respective cut-offs) was recorded only in late- and non-responders (3/8 and 1/2, respectively). Discussion: Significantly higher anti-FcεRI IgE autoantibody levels were found in the CSU patients as compared to the controls, supporting FcεRI as an autoallergic target of IgE (autoallergen) in the complex pathophysiological scenario of CSU. The co-occurrence of anti-FcεRI IgG and IgE autoantibodies was documented only in late- and non-responders, but not in early ones, crediting the co-existence of autoimmune and autoallergic mechanisms as a driver of late/poor response to omalizumab. Full article