Reduction of circulating IgE and allergens by a pH-sensitive antibody with enhanced FcγRIIb binding.

Allergen-crosslinked IgE triggers allergy by interacting with its receptor on basophils and mast cells. The anti-IgE monoclonal antibody omalizumab can alleviate allergy by competing with the receptor for IgE binding. However, along with neutralization, omalizumab also inhibits IgE degradation, which is clinically associated with high-dose and total IgE accumulation problems. In this study, we have developed an IgE-eliminating antibody on the basis of omalizumab, which has pH-dependent Fabs and an Fc with high affinity for FcγRIIb. In mice, the antibody rapidly eliminated total serum IgE to baseline levels and caused lower free IgE levels than omalizumab. At low dosages, the antibody also exhibited favorable IgE elimination effects. In addition, the antibody can degrade the corresponding allergen with the removal of IgE, addressing the allergy from its source. Introduction of the M252Y/S254T/T256E (YTE) mutation into this antibody prolongs its serum half-life without reducing potency. Thus, this engineered antibody holds a promising therapeutic option for allergy patients. Mechanistic insights are also included in this study.

IgE directly affects eosinophil migration in chronic rhinosinusitis with nasal polyps through CCR3 and predicts the efficacy of omalizumab.

BACKGROUND: Whether IgE affects eosinophil migration in chronic rhinosinusitis with nasal polyps (CRSwNP) remains largely unclear. Moreover, our understanding of local IgE, eosinophils, and omalizumab efficacy in CRSwNP remains limited. OBJECTIVE: We investigated whether IgE acts directly on eosinophils and determined its role in omalizumab therapy. METHODS: Eosinophils and their surface receptors were detected by hematoxylin and eosin staining and flow cytometry. IgE and its receptors, eosinophil peroxidase (EPX), eosinophilic cationic protein, and CCR3 were detected by immunohistochemistry and immunofluorescence. Functional analyses were performed on blood eosinophils and polyp tissues. Logistic regression was performed to screen for risk factors. Receiver operating characteristic curve was generated to evaluate the accuracy. RESULTS: Both FcεRI and CD23 were expressed on eosinophils. The expression of FcεRI and CD23 on eosinophil in nasal polyp tissue was higher than in peripheral blood (both P < .001). IgE and EPX colocalized in CRSwNP. IgE directly promoted eosinophil migration by upregulating CCR3 in CRSwNP but not in healthy controls. Omalizumab and lumiliximab were found to be effective in restraining this migration, indicating CD23 was involved in IgE-induced eosinophil migration. Both IgE+ and EPX+ cells were significantly reduced after omalizumab treatment in those who experienced response (IgE+ cells, P = .001; EPX+ cells, P = .016) but not in those with no response (IgE+ cells, P = .060; EPX+ cells, P = .151). Baseline IgE+ cell levels were higher in those with response compared to those without response (P = .024). The baseline local IgE+ cell count predicted omalizumab efficacy with an accuracy of 0.811. CONCLUSIONS: IgE directly promotes eosinophil migration, and baseline local IgE+ cell counts are predictive of omalizumab efficacy in CRSwNP.

A practical guide for implementing omalizumab therapy for food allergy.

The recent approval of omalizumab for the treatment of IgE-mediated food allergy is an important step forward for the millions of food allergy patients in the United States. Through the depletion of circulating IgE and the subsequent reduction of FcεR1 on key effector cells, patients increase their tolerance to food allergens. However, omalizumab does not permit patients to eat foods that they are allergic to with impunity. Rather, it protects them from most accidental exposures. In addition, omalizumab does not cure food allergy and has not demonstrated true immunomodulation. Thus, omalizumab might be a lifelong therapy for some patients. Furthermore, there are many important questions and issues surrounding the appropriate administration of omalizumab to treat food allergy, which we discuss. Managing treatment of patients with disease that falls outside the dosing range, assessing treatment response or nonresponse, addressing its appropriateness for patients older than 55, and determining whether immunotherapy plus omalizumab provides any advantage over omalizumab alone all need to be examined. Identifying appropriate patients for this therapy is critical given the cost of biologics. Indeed, not all food allergy patients are good candidates for this therapy. Also, when and how to stop omalizumab therapy in patients who may have outgrown their food allergy needs to be elucidated. Thus, although this therapy provides a good option for patients with food allergies, much information is needed to determine how best to use this therapy. Despite many unanswered questions and issues, we provide clinicians with some practical guidance on implementing this therapy in their patients.

In chronic spontaneous urticaria, increased Galectin-9 expression on basophils and eosinophils is linked to high disease activity, endotype-specific markers, and response to omalizumab treatment.

BACKGROUND: Galectin-9 (Gal-9) has been implicated in allergic and autoimmune diseases, but its role and relevance in chronic spontaneous urticaria (CSU) are unclear. OBJECTIVES: To characterize the role and relevance of Gal-9 in the pathogenesis of CSU. METHODS: We assessed 60 CSU patients for their expression of Gal-9 on circulating eosinophils and basophils as well as T cell expression of the Gal-9 receptor TIM-3, compared them with 26 healthy controls (HCs), and explored possible links with disease features including disease activity (urticaria activity score, UAS), total IgE, basophil activation test (BAT), and response to omalizumab treatment. We also investigated potential drivers of Gal-9 expression by eosinophils and basophils. RESULTS: Our CSU patients had markedly increased rates of circulating Gal-9+ eosinophils and basophils and high numbers of lesional Gal-9+ cells. High rates of blood Gal-9+ eosinophils/basophils were linked to high disease activity, IgE levels, and BAT negativity. Serum levels of TNF-α were positively correlated with circulating Gal-9+ eosinophils/basophils, and TNF-α markedly upregulated Gal-9 on eosinophils. CSU patients who responded to omalizumab treatment had more Gal-9+ eosinophils/basophils than non-responders, and omalizumab reduced blood levels of Gal-9+ eosinophils/basophils in responders. Gal-9+ eosinophils/basophils were negatively correlated with TIM-3+TH17 cells. CONCLUSION: Our findings demonstrate a previously unrecognized involvement of the Gal-9/TIM-3 pathway in the pathogenesis CSU and call for studies that explore its relevance.

Ligelizumab impairs IgE-binding to plasmacytoid dendritic cells more potently than omalizumab and restores IFN-α production and FOXP3+ Treg generation.

BACKGROUND: Ligelizumab is an anti-IgE monoclonal antibody binding IgE with higher affinity than omalizumab that is under clinical investigation for several IgE-mediated diseases. We previously showed that omalizumab removes IgE bound to FcεRI on plasmacytoid dendritic cells (pDCs) and restores their ability to produce IFN-α and regulatory T cells (Tregs). The aim of this work is to investigate the capacity of ligelizumab to regulate functional properties of pDCs in comparison with omalizumab. METHODS: pDCs were isolated from atopic donors and IgE was detached from FcεRI on pDCs with designed ankyrin repeat protein (DARPin) bi53-79. pDCs were resensitized with IgE alone or in the presence of ligelizumab or omalizumab prior to IgE-FcεRI crosslinking and Toll-like receptor 9 (TLR9) stimulation. Flow cytometry, ELISA, coculture experiments and intranuclear staining were performed to determine cytokine production and Treg generation. An antigen-specific model of resensitization and IgE-crosslinking was also performed. RESULTS: The levels of serum total free IgE show a non-linear positive correlation with the frequency of IgE+ pDCs displaying IgE bound to FcεRI within the 43 individual donors included in the study. Ligelizumab displays stronger capacity than omalizumab to block the binding of free IgE to FcεRI on human pDCs, resulting in a greater restoration of TLR9-L-induced IFN-α production. Ligelizumab also restores the ability of pDCs to generate FOXP3+ Tregs as previously reported for omalizumab. CONCLUSIONS: The uncovered novel molecular mechanisms of ligelizumab to regulate functional properties of pDCs from atopic donors might have important clinical implications for anti-IgE treatments in different IgE-mediated diseases.

Impact of body mass index on omalizumab response in adults with moderate-to-severe allergic asthma.

BACKGROUND: Effectiveness of asthma treatment, including biologics, may be different in patients with higher body mass index (BMI). OBJECTIVE: To evaluate response to omalizumab (dosed by serum immunoglobulin E level and weight) by BMI category. METHODS: Pooled data from 2 randomized, double-blind, placebo-controlled studies of adults with moderate-to-severe allergic asthma were analyzed by BMI category (<25 kg/m2 [normal or underweight], n = 397; 25 to <30 kg/m2 [overweight], n = 330; ≥ 30 kg/m2 [obese], n = 268). Placebo-adjusted exacerbation rate reductions were evaluated by Poisson regression modeling. Changes from baseline in forced expiratory volume in 1 second, beclomethasone dipropionate (BDP) dose, Total Asthma Symptom Score, and Asthma Quality of Life Questionnaire were evaluated by analysis of covariance. RESULTS: Greater placebo-adjusted exacerbation rate reductions (95% confidence interval) were observed with increasing BMI (normal or underweight, -37.4% [-69.0% to 26.8%]; overweight, -52.7% [-78.4% to 3.7%]; obese, -71.9% [-86.9% to -39.5%]). There were no differences in forced expiratory volume in 1 second improvement between BMI categories at week 16 (normal or underweight, 76.2 [5.3-147.1] mL; overweight, 98.1 [13.9-182.4] mL; obese, 69.1 [-18.9 to 157.2] mL). No differences in BDP dose reduction (µg) were noted between BMI categories (normal or underweight, 23.0 [15.7-30.3]; overweight, 22.5 [13.5-31.5]; obese, 16.6 [5.8-27.3]). Fewer patients in the higher BMI categories eliminated BDP use. There were trends for smaller improvements with higher BMI in Total Asthma Symptom Score (normal/underweight, -0.52 [-0.82 to -0.22]; overweight, -0.50 [-0.80 to -0.20]; obese, -0.39 [-0.77 to 0.00]) and Asthma Quality of Life Questionnaire (normal or underweight, 0.34 [0.16-0.52]; overweight, 0.34 [0.13-0.55]; obese, 0.15 [-0.08 to 0.39]). CONCLUSION: Omalizumab provides benefit to patients with moderate-to-severe allergic asthma, regardless of BMI. TRIAL REGISTRATION: Studies 008/009 were conducted before clinical trial registration was required, and therefore clinical trial registration numbers are not available.

[Analysis of predictors of response to anti-IgE therapy in patients with severe atopic bronchial asthma in real clinical practice].

INTRODUCTION: Guidelines on Biological Therapy for Bronchial Asthma of the European Academy of Allergy and Clinical Immunology (EAACI) identified a number of controversial issues for additional outcome analysis using randomized clinical trials and data from routine clinical practice. In particular, there is unmet need to clarify algorithms for prescribing biologicals using predictors of response and its timing, taking into account risk factors and multimorbidity. Omalizumab is a recombinant humanized monoclonal anti-IgE antibody of IgG1 class used for the treatment of severe refractory atopic bronchial asthma (BA) and a variety of IgE-mediated diseases. Among biological agents, this "pioneer molecule" has the greatest experience in the "allergology and immunology" profile. Detailed description of the "nonresponders" portraits will allow to perform the therapy response assessment on time and facilitate rational planning of individual therapy, which is a prerequisite for biologicals era. Using only routine methods, it is possible to perform initial and dynamic screening to phenotype a heterogeneous cohort of patients with severe asthma and chose the optimal strategy. AIM: To identify predictors of nonresponse to omalizumab anti-IgE therapy in patients with severe atopic BA and to establish optimal timing of efficacy assessment using retrospective analysis of data from the Biologic Therapy Registry of Allergology and Immunology in routine clinical practice. MATERIALS AND METHODS: A retrospective single-center registry study was conducted at the Allergy and Immunology Reference Center from June 2017 to August 2021. 135 patients with severe BA, with confirmed perennial sensitization, who received omalizumab according to the recommendations of the current version of GINA, were selected from the clinical and dynamic observational system (registry). Dosing regimen and administration frequency of omalizumab were determined in accordance with the instructions for the drug. Assessment of therapy efficacy was performed at the time point 4, 6 and 12 months. Patients were subgrouped into "responders" and "non-responders" according to the following criteria: ACT score less than 19 and/or difference between initial ACT score in dynamics less than 3 points; forced expiratory volume in the first second less than 80%; combination of these two criteria. Nonparametric methods of descriptive statistics were used in data processing: median, interquartile range. Differences were considered significant at p0.05. MannWhitney U-test, KruskalWallis one-way analysis of variance, and Fisher's 2 test were used to compare quantitative characteristics. RESULTS: Heterogeneous subgroups of patients differing in reaching the criteria of "non-responders" to treatment were identified; the informativity of modifiable and unmodifiable factors differed at time-points of dynamic observation. In the differential analysis, two profiles of "nonresponders" were defined in combination with the most significant predictors of "nonrsponse" to omalizumab. According to the data obtained, one of the clinical phenotypes, namely the combination of severe asthma with the Samters triad, corresponded to the characteristics of the patient "nonresponders": age of onset is about 30 years, females, severe exacerbations of BA while taking non-steroidal anti-inflammatory drugs, accompanied with high levels of eosinophilia. CONCLUSION: The data obtained illustrates the hypothesis of pathogenetic heterogeneity of severe BA with the phenomenon of overlapping phenotypes and can serve as an additional orienteer for creating the individual plan of anti-IgE therapy in real clinical practice.

Effects of omalizumab on basophils: Potential biomarkers in asthma and chronic spontaneous urticaria.

Omalizumab is an anti-IgE humanized monoclonal antibody approved for the treatment of severe asthma and chronic spontaneous urticaria. Omalizumab binds free serum IgE and antagonizes its interaction with FcεRI, which is considered the main pharmacodynamic mechanism responsible for the clinical response to the treatment. The reduction of IgE serum concentration down-regulates the cellular expression of FcεRI on basophils. However, the biological events occurring on basophils during the therapy with omalizumab are multiple and complex. Here we review the current evidence regarding the specific biological effects of omalizumab on basophils in patients with asthma and chronic spontaneous urticaria. In addition to the modulation of IgE receptors, omalizumab may affect basophils homeostasis, intra-cellular signaling, cellular responsiveness/activation and cytokine release. These effects may be partially responsible for the clinical success of omalizumab and potentially provide useful biological markers for future assessment of the clinical response to the treatment. However, further investigation is required to better elucidate the role of basophils during the treatment with omalizumab.

Effect of omalizumab on lung function and eosinophil levels in adolescents with moderate-to-severe allergic asthma.

BACKGROUND: Omalizumab improves clinical outcomes in patients with asthma. Several studies have shown lung function improvements with omalizumab; however, this has not been examined exclusively in adolescents. OBJECTIVE: To assess the effect of omalizumab on lung function and eosinophil counts in adolescents with uncontrolled moderate-to-severe allergic asthma. METHODS: In this post hoc analysis, data from adolescents aged 12 to 17 years from 8 randomized trials of omalizumab were pooled (studies 008, 009, and 011, and SOLAR, INNOVATE, ALTO, ETOPA, and EXTRA). Changes from baseline to end of study in forced expiratory volume in 1 second (FEV1), percent predicted FEV1 (ppFEV1), forced vital capacity (FVC), and blood eosinophil counts were assessed by fitting an analysis of covariance model and calculating least squares mean (LSM) difference for omalizumab vs placebo. RESULTS: A total of 340 adolescents were identified (omalizumab, n = 203 [59.7%]; placebo, n = 137 [40.3%]). Omalizumab increased all baseline lung function variables more than placebo by end of study: LSM treatment differences (95% confidence interval) were 3.0% (0.2%-5.7%; P = .035), 120.9 mL (30.6-211.2 mL; P = .009), and 101.5 mL (8.3-194.6 mL; P = .033) for ppFEV1, absolute FEV1, and FVC, respectively. The LSM difference demonstrated a greater reduction in eosinophil counts for omalizumab vs placebo: -85.9 cells/µL (-137.1 to -34.6 cells/µL; P = .001). CONCLUSION: Omalizumab was associated with lung function improvements and circulating eosinophil counts reductions in adolescents with moderate-to-severe uncontrolled asthma. Findings emphasize the effect of omalizumab in young patients and the need to optimize treatment early in the disease course. https://clinicaltrials.gov/: NCT00314574, NCT00046748, NCT00401596.

Association of upper and lower airway eosinophilic inflammation with response to omalizumab in patients with severe asthma.

Background: The anti-immunoglobulin E monoclonal antibody, omalizumab, is used to treat severe asthma and has the potential to ameliorate airway inflammation. However, the effect of omalizumab in ameliorating upper airway inflammation has not been fully elucidated. Objective: We investigated the association of upper and lower airway inflammation with the response to omalizumab treatment. Methods: We used the Global Evaluation of Treatment Effectiveness to assess the efficacy of omalizumab in treating 16 patients with severe asthma. We also investigated the symptom score, short-acting ß-agonist inhaler use, pulmonary function, biomarkers, computed tomography scans, and nasal mucosa pathology at omalizumab initiation and after four months of treatment. Results: When the fraction of exhaled nitric oxide (FeNO) and the percentage of sputum eosinophil were used as indicators of lower airway inflammation, positive correlations were found between CD20 B-cell, mast cell, and eosinophil counts in the nasal mucosa. Improved asthma symptoms were observed in 12 of the 16 severe asthma cases. The FeNO and eosinophil levels in the nasal tissue, prior to the administration of omalizumab were predictors of the response to asthma treatment. Conclusions: These findings suggest heterogeneity among people with severe asthma. In addition, the phenotype associated with response to omalizumab, leading to improvement in asthma symptoms, comprises upper airway eosinophilia and high FeNO levels.

What the physicians should know about mast cells, dendritic cells, urticaria, and omalizumab during COVID-19 or asymptomatic infections due to SARS-CoV-2?

Coronavirus disease (COVID-19) pandemic presents several dermatological manifestations described in the present indexed literature, with around 700 cases reported until May 2020, some described as urticaria or urticarial rashes. Urticaria is constituted by evanescent erythematous-edematous lesions (wheals and flare), which does not persist in the same site for more than 24 to 48 hours and appears in other topographic localization, resolving without residual hyper pigmentation. During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, some cytokines are synthesized, including Interferon (IFN) type I, TNF-α, and chemokines which may induce mast cells (MCs) and basophils degranulation by mechanisms similar to the autoinflammatory monogenic or polygenic diseases. In this article, we discuss the spectrum of the urticaria and urticarial-like lesions in the COVID-19's era, besides other aspects related to innate and adaptative immune response to viral infections, interactions between dermal dendritic cells and MCs, and degranulation of MCs by different stimuli. Plasmacytoid dendritic cells share, in allergic patients, expression of the high-affinity IgE receptors on cell membranes and demonstrated a low pattern of type I IFN secretion in viral infections. We discuss the previous descriptions of the effects of omalizumab, a monoclonal antibody directed to IgE and high-affinity IgE receptors, to improve the IFN responses and enhance their antiviral effects.

Effect of omalizumab use on glucose homeostasis in non-diabetic patients with chronic urticaria.

PURPOSE: In some diabetic patients receiving omalizumab therapy, blood glucose regulation is impaired. However, the effect of omalizumab on glucose homeostasis in non-diabetic patients remains unknown. METHODS: The patients were given subcutaneous omalizumab at a dose of 300 mg every four weeks for the treatment of chronic urticaria in this study. Fasting blood glucose, fasting plasma insulin, total cholesterol, triglyceride, and high-density (HDL) and low-density lipoprotein (LDL) were studied before and at the 12th week of treatment. The homeostatic model assessment for insulin resistance (HOMA-IR) was used to determine insulin resistance. RESULTS: Forty of the 45 patients included in the study completed 12 weeks of treatment. While fasting blood glucoses (p = 0.011) and HOMA-IR values (p = 0.027) were significantly increased in the 12th week, the increase in fasting insulin level was not significant (p = 0.07). After treatment, 10 patients developed impaired fasting glucose and 13 developed insulin resistance. CONCLUSION: The increase in blood glucose levels may be associated with the paradoxically increase of histamine levels in the blood by omalizumab. If this increase cannot be balanced with insulin, patients may develop impaired glucose tolerance and insulin resistance. Therefore, we suggest that patients using omalizumab should be followed up for glucose homeostasis and insulin resistance.

Omalizumab does not lead to a distinct alteration in hematological parameters and complete blood count-derived inflammation biomarkers except for basophil count.

PURPOSE: Omalizumab is a monoclonal anti-IgE antibody used to treat patients with chronic spontaneous urticaria by decreasing free IgE levels. Omalizumab may have an anti-inflammatory effect by inhibiting T-cell activation and inducing eosinophil apoptosis. In this study, we evaluated the effect of omalizumab on hematological parameters and inflammation biomarkers in patients with chronic spontaneous urticaria. METHODS: Between July 2018 and November 2019, medical records of 60 patients (44 female, 16 male) with chronic spontaneous urticaria who were treated with omalizumab were reviewed retrospectively. Hematological parameters and inflammation biomarkers including the neutrophil/lymphocyte, monocyte/lymphocyte, platelet/lymphocyte and mean platelet volume/platelet count ratios were compared before and after 12 weeks of omalizumab treatment. RESULTS: The absolute count of basophils and percentage of basophils increased significantly after omalizumab treatment (p = 0.04, p = 0.004). The absolute count of eosinophils, percentage of eosinophils, neutrophil/lymphocyte, monocyte/lymphocyte, and mean platelet volume/platelet ratios decreased, while platelet/lymphocyte ratio increased after omalizumab treatment. Nevertheless, these changes were not statistically significant. CONCLUSIONS: Increased basophil counts suggest that omalizumab has a crucial effect through basophils in chronic spontaneous urticaria. Further studies focussing on basophils may contribute to the literature both to elucidate the etiopathogenesis of urticaria and to improve novel treatment agents for the disease. On the other hand, our study revealed that omalizumab did not have a distinct effect on complete blood count-derived inflammation biomarkers and thus inflammation.

Omalizumab normalizes the gene expression signature of lesional skin in patients with chronic spontaneous urticaria: A randomized, double-blind, placebo-controlled study.

BACKGROUND: Omalizumab, a humanized recombinant monoclonal anti-IgE antibody, proved to be effective in patients with chronic spontaneous urticaria (CSU), including severe and treatment-refractory CSU. Here, we report omalizumab's effect on gene expression in skin biopsies from CSU patients enrolled in a double-blind, placebo-controlled study. METHODS: Chronic spontaneous urticaria patients (18-75 years) were randomized to either 300 mg omalizumab (n = 20) or placebo (n = 10) administered s.c. every 4 weeks for 12 weeks (NCT01599637). Lesional and nonlesional skin biopsies were collected from the same area of consenting patients and assessed at baseline and on Day 85 compared with skin biopsies from the same area of 10 untreated healthy volunteers (HVs). Gene expression data were generated using Affymetrix HG-U133Plus2.0 microarrays. Statistical analyses were performed using R packages. RESULTS: At baseline, 63 transcripts were differentially expressed between lesional and nonlesional skin. Two-thirds of these lesional signatures were also differentially expressed between lesional and HV skin. Upon treatment with omalizumab, >75% of lesional signatures changed to reflect nonlesional skin expression levels (different vs placebo, P < 0.01). Transcripts upregulated in lesional skin (vs nonlesional and/or HV skin) suggested increased mast cell/leukocyte infiltration (FCER1G, C3AR1, CD93, S100A8, and S100A9), increased oxidative stress, vascularization (CYR61), and skin repair events (KRT6A, KRT16). Lesional signatures were not modulated by treatment in nonresponders (defined based on UAS7 longitudinal changes ≥16). CONCLUSION: Omalizumab, in treatment responders, reverted transcriptional signatures associated with CSU lesion phenotype to reflect nonlesional/HV expression levels; this is consistent with observed omalizumab-mediated clinical improvement observed in patients with CSU.

Omalizumab in Chronic Urticaria: An Italian Survey.

Omalizumab is approved for use in chronic spontaneous urticaria (CSU); however, it is not approved for chronic inducible urticaria (CIndU). The aim of the present study was to assess the effectiveness of omalizumab in treating CSU and CIndU in Italy. This is a multicentre prospective observational real-life study involving patients with severe urticaria capable of undergoing omalizumab therapy. We enrolled 127 patients (59.1% females), ranging in age from 15 to 83 years, 69.3% had CSU alone, 26.8% had CSU and CIndU, and 3.9% had only CIndU (30.8% delayed pressure, 35.9% dermographic, 15.3% cholinergic, 12.8% cold, 5.1% aquagenic). After the first cycle of omalizumab (300 mg every 4 weeks for 24 weeks), 16 CSU patients and 10 patients (20.5%) with CIndU with or without CSU did not require a second cycle of omalizumab (300 mg every 4 weeks for 20 weeks). The patient with aquagenic urticaria achieved remission after the first cycle. None showed a lack of response to the second cycle of omalizumab. Omalizumab is a promising drug for both spontaneous and inducible chronic urticaria. Current evidence indicates that omalizumab may be approved also for CIndU.

Activation of Human Basophils by A549 Lung Epithelial Cells Reveals a Novel IgE-Dependent Response Independent of Allergen.

Evidence for epithelial cell (EC)-derived cytokines (e.g., thymic stromal lymphopoietin [TSLP]) activating human basophils remains controversial. We therefore hypothesize that ECs can directly activate basophils via cell-to-cell interaction. Basophils in medium alone or with IL-3 ± anti-IgE were coincubated with TSLP, IL-33, or IL-25. Analogous experiments cocultured basophils (1-72 h) directly with EC lines. Supernatants were tested for mediators and cytokines. Abs targeting receptors were tested for neutralizing effects. Lactic acid (pH 3.9) treatment combined with passive sensitization tested the role of IgE. Overall, IL-33 augmented IL-13 secretion from basophils cotreated with IL-3, with minimal effects on histamine and IL-4. Conversely, basophils (but not mast cells) released histamine and marked levels of IL-4/IL-13 (10-fold) when cocultured with A549 EC and IL-3, without exogenous allergen or IgE cross-linking stimuli. The inability to detect IL-33 or TSLP, or to neutralize their activity, suggested a unique mode of basophil activation by A549 EC. Half-maximal rates for histamine (4 h) and IL-4 (5 h) secretion were slower than observed with standard IgE-dependent activation. Ig stripping combined with passive sensitization ± omalizumab showed a dependency for basophil-bound IgE, substantiated by a requirement for cell-to-cell contact, aggregation, and FcεRI-dependent signaling. A yet unidentified IgE-binding lectin associated with A549 EC is implicated after discovering that LacNAc suppressed basophil activation in cocultures. These findings point to a lectin-dependent activation of basophil requiring IgE but independent of allergen or secreted cytokine. Pending further investigation, we predict this unique mode of activation is linked to inflammatory conditions whereby IgE-dependent activation of basophils occurs despite the absence of any known allergen.

Omalizumab as an alternative therapeutic tool in the treatment of bullous pemphigoid: A case report.

Bullous pemphigoid (BP) is an acquired autoimmune bullous disease characterized by autoantibodies against the hemidesmosomal proteins found in the basal keratinocytes of the basement membrane zone (BMZ): a 180 kDa protein (type XVII collagen) mainly and the 230 kDa antigen. There is such evidence that the antibodies against the BMZ components are not only of IgG type, but also this bullous disease may have IgE antibodies directed to the BMZ that contribute to the pathogenesis of the disorder. IgE is not only thought to contribute to the pathogenesis of BP, it has also been suggested that eosinophils play a role in the development of the first signs associated with BP. A humanized monoclonal antibody directed to IgE, omalizumab, is approved for the treatment of severe asthma and chronic spontaneous urticaria, and it may be useful in the treatment of BP in the first stages of the disease.

The efficacy of omalizumab in Cutaneous Mastocytosis: A case series.

BACKGROUND: Mastocytosis describes a heterogeneous group of disorders arising from a clonal proliferation of mast cells. Given the lack of curative treatments for the cutaneous form, there is a significant need for superior therapies. Omalizumab is a recombinant DNA-derived humanized IgG monoclonal antibody that selectively binds to human immunoglobulin E (IgE). It represents a potential treatment for the management of cutaneous mastocytosis, which currently has no standard treatment. METHODS: Two patients were treated with subcutaneous omalizumab 300 mg every 4 weeks. DISCUSSION: Patient 1 experienced 50% reduction in cutaneous infiltration and moderate improvement in pruritus. Patient 2 underwent 90% complete clearance of cutaneous lesions and reported full resolution of pruritus. The median duration of treatment was 24 weeks and time to response was 8 weeks. No significant changes in tryptase levels were observed. Both patients experienced injection site reactions. CONCLUSION: We provide evidence from two cases supporting the efficacy of IgE-mediated therapy in the treatment of cutaneous mastocytosis. Even at a higher-than-standard dose (300 mg vs. 150 mg), the drug was well-tolerated. As we await the results of pivotal clinical trials, omalizumab appears to be a promising treatment option in patients with cutaneous mastocytosis unresponsive to traditional therapies.

Effect of omalizumab on outcomes in patients with aspirin-exacerbated respiratory disease.

Background: The current treatment for patients with aspirin-exacerbated respiratory disease (AERD) who have uncontrolled asthma or chronic rhinosinusitis is aspirin desensitization. For patients who are unable to undergo or do not benefit from aspirin desensitization, treatment with biologics is an option, although efficacy data for AERD is scarce. Objective: We reported a series of patients with AERD who were started on omalizumab and measured the outcomes to assess improvement. Methods: Adult patients with AERD who were initiated on omalizumab from January 2007 to January 2018 were included. We compared outcomes 6-12 months before initiating biologic therapy and during the last 6-12 months while they were on biologic therapy. Our study investigated the number of oral steroid courses, short-acting beta-agonists (SABA), antibiotics for sinusitis or pneumonia, emergency department visits, hospitalizations, pulmonary function tests, and changes in controller medications. Results: Twenty-nine patients were placed on omalizumab. Sixty-two percent demonstrated a reduction in the number of steroid courses (p = 0.0014) and number of SABA canisters used (p = 0.0005) during their last 12 months while on omalizumab. Eighty-six percent of the patients with AERD and on omalizumab demonstrated either a decrease in the number of steroid courses or number of SABA canisters used in the last year of the study. The patients with AERD and with concomitant immunoglobulin E (IgE) mediated respiratory disease showed a statistically significant reduction in the number of steroid courses and number of SABA canisters used while on omalizumab for 1 year (p = 0.002 and p = 0.005, respectively), whereas those without concomitant IgE-mediated respiratory disease did not have a substantial reduction in steroids or SABA canisters used. Conclusion: Our case series reported that omalizumab could effectively be used as an adjunct treatment for AERD, but additional larger and longitudinal studies are needed to corroborate these findings.