PI3Kδ inhibition prevents IL33, ILC2s and inflammatory eosinophils in persistent airway inflammation.

BACKGROUND: Phosphoinositide-3-kinase-delta (PI3Kδ) inhibition is a promising therapeutic approach for inflammatory conditions due to its role in leucocyte proliferation, migration and activation. However, the effect of PI3Kδ inhibition on group 2 innate lymphoid cells (ILC2s) and inflammatory eosinophils remains unknown. Using a murine model exhibiting persistent airway inflammation we sought to understand the effect of PI3Kδ inhibition, montelukast and anti-IL5 antibody treatment on IL33 expression, group-2-innate lymphoid cells, inflammatory eosinophils, and goblet cell metaplasia. RESULTS: Mice were sensitised to house dust mite and after allowing inflammation to resolve, were re-challenged with house dust mite to re-initiate airway inflammation. ILC2s were found to persist in the airways following house dust mite sensitisation and after re-challenge their numbers increased further along with accumulation of inflammatory eosinophils. In contrast to montelukast or anti-IL5 antibody treatment, PI3Kδ inhibition ablated IL33 expression and prevented group-2-innate lymphoid cell accumulation. Only PI3Kδ inhibition and IL5 neutralization reduced the infiltration of inflammatory eosinophils. Moreover, PI3Kδ inhibition reduced goblet cell metaplasia. CONCLUSIONS: Hence, we show that PI3Kδ inhibition dampens allergic inflammatory responses by ablating key cell types and cytokines involved in T-helper-2-driven inflammatory responses.

Porcine-Stimulated Human Tr1 Cells Showed Enhanced Suppression in Xenoantigen Stimulation Response.

Type 1 regulatory T (Tr1) cells play a fundamental role in maintaining and inducing immune tolerance. Our preliminary study demonstrated that an interleukin- (IL-) 10-mediated pathway is a possible regulatory mechanism underlying the xenoantigen-specific human Treg enhanced suppressive capacity. Here, we developed a feasible protocol for expanding IL-10-induced xenoantigen-specific human Tr1 cells in vitro which would be more efficient in transplantation immunotherapy efficiency. In this study, xenoantigen-specific Tr1 cells are generated from human naive CD4+ T cells expanded for two subsequent xenoantigen-stimulation cycles with recombinant human IL-10. The phenotype and suppressive capacity of xenoantigen-stimulated Tr1 cells are assessed, and the mechanism of their suppression is studied. Tr1 cells can be induced by porcine xenoantigen stimulation combined with IL-10, IL-2, and IL-15, displaying an increased expression of CD49b, CTLA-4, and LAG-3 without expressing Foxp3 which also showed an effector memory Treg phenotype and expressed high levels of CD39. After xenoantigen stimulation, the IL-10 and IL-5 gene expression in Tr1 cells increased, secreting more IL-10, and xenoantigen-stimulated Tr1 cells changed their T cell receptor (TCR) Vß repertoire, increasing the expression of TCR Vß2, TCR Vß9, and TCR Vß13. In a pig to human mixed lymphocyte reaction (MLR), xenoantigen-stimulated Tr1 cells displayed enhanced suppressive capacity via CD39 in a dose-dependent manner. Moreover, IL-5 could affect the proliferation of xenoantigen-specific Tr1 cells, but not their phenotypes' expression. This study provides a theory and feasible method for immune tolerance induction in clinical xenotransplantation.

Treatment of lymphocyte-variant hypereosinophilic syndrome (L-HES): what to consider after confirming the elusive diagnosis.

Lymphocyte-variant hypereosinophilic syndrome (L-HES) is a rare disease driven by immunophenotypically aberrant T cells producing eosinophilopoetic cytokines such as interleukin-5 (IL-5). Treatment is challenging because L-HES is relatively steroid resistant and not amenable to tyrosine kinase inhibitors. We searched the literature for clinical trials and observational studies, including case reports, of patients treated for L-HES. In all, 25 studies were selected; two were randomised controlled trials of IL-5 blockade, which included some patients with L-HES, and the rest were observational studies. Corticosteroids are often used as first-line therapy, but patients with L-HES have lower response rates than other types of HES. Treatments that reduce symptoms and steroid dependence in some patients include interferon-alpha (IFN-α), anti-IL-5 monoclonal antibodies, cyclosporine and mycophenolate. These drugs target T-cell activation and proliferation, or IL-5 directly. Although effective, IFN-α and cyclosporine were commonly reported to cause side-effects resulting in discontinuation. Alemtuzumab can induce remissions, but these are generally short lived. The anti-IL-5 monoclonal antibodies mepolizumab and benralizumab are effective and well tolerated, but with a high rate of relapse once withdrawn. Hydroxyurea, methotrexate, imatinib were unsuccessful in most patients studied. More prospective clinical trials are needed for patients with L-HES.

Treating severe asthma: Targeting the IL-5 pathway.

Severe asthma is a heterogeneous disease with different phenotypes based on clinical, functional or inflammatory parameters. In particular, the eosinophilic phenotype is associated with type 2 inflammation and increased levels of interleukin (IL)-4, IL-5 and IL-13). Monoclonal antibodies that target the eosinophilic inflammatory pathways (IL-5R and IL-5), namely mepolizumab, reslizumab, and benralizumab, are effective and safe for severe eosinophilic asthma. Eosinophils threshold represents the most indicative biomarker for response to treatment with all three monoclonal antibodies. Improvement in asthma symptoms scores, lung function, the number of exacerbations, history of late-onset asthma, chronic rhinosinusitis with nasal polyposis, low oral corticosteroids use and low body mass index represent predictive clinical markers of response. Novel Omics studies are emerging with proteomics data and exhaled breath analyses. These may prove useful as biomarkers of response and non-response biologics. Moreover, future biomarker studies need to be undertaken in paediatric patients affected by severe asthma. The choice of appropriate biologic therapy for severe asthma remains challenging. The importance of finding biomarkers that can predict response continuous an open issue that needs to be further explored. This review describes the clinical effects of targeting the IL-5 pathway in severe asthma in adult and paediatric patients, focusing on predictors of response and non-response.

Efficacy and safety of reslizumab in the treatment of eosinophilic granulomatosis with polyangiitis.

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA), a rare vasculitis with substantial morbidity, is characterized by asthma, eosinophilia, sinusitis, pulmonary infiltrates, neuropathy, positivity for antineutrophil cytoplasmic antibody, and multiorgan vasculitis. Although treatment options previously included corticosteroids and immunosuppressants, anti-interleukin 5 therapies have gained interest in EGPA treatment. Mepolizumab was approved for and recently benralizumab was found to have safety and efficacy in EGPA. OBJECTIVE: To determine the safety and efficacy of reslizumab in EGPA. METHODS: In this open-label, pilot study, we evaluated the safety and efficacy of intravenous reslizumab (3 mg/kg) in EGPA in 10 subjects. Oral corticosteroid dose, adverse events, exacerbations, symptom control, disease activity, blood markers, and lung function were evaluated before, during, and after 7 monthly reslizumab treatments. RESULTS: Reslizumab was tolerated and resulted in a significant reduction in daily oral corticosteroid (P < .05). Of the 10 subjects, 3 experienced an EGPA exacerbation during the treatment. One had a severe adverse event, requiring removal from the study. CONCLUSION: Yielding similar results to other anti-interleukin 5 biologic medications, reslizumab is generally a safe and effective treatment for EGPA that warrants further study. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02947945.

Biologics for the Treatment of Allergic Rhinitis, Chronic Rhinosinusitis, and Nasal Polyposis.

Allergic rhinitis (AR), most presentations of nasal polyposis (NP), and many presentations of chronic rhinosinusitis are type 2high disorders characterized by expression of interleukin (IL)-4, IL-5, and IL-13. Neutralization of IgE with anti-IgE (omalizumab) has proven efficacy in AR. Similarly, in addition to anti-IgE, blockade of IL-5/IL-5 (mepolizumab, reslizumab, benralizumab) and dual blockade of IL-4 and IL-13 with anti-IL-4R (dupilumab) have demonstrated efficacy in NP. However, these agents are expensive and future studies are essential to evaluate cost effectiveness in comparison with current medical and surgical therapies. This article reviews biologics as potential interventions in AR, chronic rhinosinusitis, and NP.

Biologics for the Treatment of Allergic Conditions: Eosinophil Disorders.

Eosinophil-associated diseases are characterized by a common pathogenetic background, represented by eosinophil-led inflammation and overexpression of interleukin (IL)-5. IL-5 and its receptor are excellent therapeutic targets for eosinophil-associated diseases. Three monoclonal antibodies targeting IL-5 currently are available: mepolizumab and reslizumab block circulating IL-5 preventing the binding to its receptor, whereas benralizumab binds to IL-5 receptor α. They have a steroid-sparing effect in eosinophil disorders, such as eosinophilic granulomatosis with polyangiitis, hypereosinophilic syndrome, allergic bronchopulmonary aspergillosis, eosinophilic esophagitis, and chronic eosinophilic pneumonia. The biotechnological drugs targeting IL-5 are promising therapies; however, further studies are needed.

Biologics and Allergy Immunotherapy in the Treatment of Allergic Diseases.

Allergic diseases represent some of the most chronic and costly chronic conditions. Medical management may require long-term pharmacotherapy, which is often associated with poor adherence. Although medications provide symptomatic control, they do not modify the allergic disease. Patients may prefer disease-modifying treatments that provide lasting benefits after discontinuation. To date, allergy immunotherapy is the only proved disease modification therapy associated with lasting benefits after discontinuation. However, allergy immunotherapy safety and efficacy has only been established in allergic rhinitis, mild to moderate asthma, and some patients with atopic dermatitis.

Targeted Therapy for Chronic Spontaneous Urticaria: Rationale and Recent Progress.

Chronic spontaneous urticaria (CSU) is characterized by the presence of wheals, angioedema, or both for at least 6 weeks. It may persist for a long time-up to 50% of the patients have been reported to be symptomatic 5 years after the onset. Some patients can suffer more than one episode of CSU during their lifetime. Considering the recurrences, disabling symptoms, and significant impact on quality of life, proper and effective treatment of CSU is critical. The use of antihistamines (AHs) is still the mainstay of treatment. However, given the low rates of response to AHs (38.6% and 63.2% to standard doses and higher doses, respectively), the complete control of symptoms seems difficult to attain. The use of omalizumab for CSU has been a major breakthrough in the care of patients with CSU. However, the partial response and lack of response to omalizumab in a subgroup of patients, as high as 70% in some studies, make the development of alternative treatments desirable. Ever-increasing knowledge on the pathogenesis is making new target molecules available and enabling drug development for CSU. In addition to drug repurposing as in anti-IL-4/13, IL-5, and IL-17 antibodies, novel targeted therapy options such as ligelizumab and Bruton's tyrosine kinase inhibitors are currently undergoing clinical trials and will be available in the near future. This article reviews the current challenges in the treatment of CSU, the pathogenesis and potential target molecules, and the rationale for novel treatments and their rapidly developing status.

Cellular Source of Cysteinyl Leukotrienes Following Chlorine Exposure.

Exposure of mice to high concentrations of chlorine leads to the synthesis of cysteinyl leukotrienes (cysLTs). CysLTs contribute to chlorine-induced airway hyperresponsiveness. The aim of the current study was to determine the cellular source of the cysLTs. To achieve this aim, we exposed mice to 100 ppm of chlorine for 5 minutes. Intranasal instillation of clodronate in liposomes and of diphtheria toxin in CD11c-DTR mice was used to deplete macrophages. CCR2-/- mice were used to assess the contribution of recruited macrophages. Eosinophils and neutrophils were depleted with specific antibodies. Platelet-neutrophil aggregation was prevented with an antibody against P-selectin. The potential roles of phagocytosis of neutrophils by macrophages and of transcellular metabolism between epithelial cells and neutrophils were explored in coculture systems. We found that depletion of neutrophils was the only intervention that inhibited the synthesis of cysLTs at 24 hours after chlorine exposure. Although macrophages did synthesize cysLTs in response to phagocytosis of neutrophils, depletion of macrophages did not reduce the increment in cysLTs triggered by chlorine exposure. However, coculture of airway epithelial cells with neutrophils resulted in a significant increase in the synthesis of cysLTs, dependent on the expression of 5-lipoxygenase by neutrophils. We conclude that cysLT synthesis following chlorine exposure may be dependent on transcellular metabolism by neutrophil-epithelial interactions.

Targeted Anti-IL-5 Therapies and Future Therapeutics for Hypereosinophilic Syndrome and Rare Eosinophilic Conditions.

Eosinophilic inflammation is a component of many atopic diseases such as asthma, and biologics targeting eosinophils have been shown to be effective in subsets of these patients. However, there also are conditions in which eosinophils are the key inflammatory cells responsible for driving tissue damage. In these eosinophilic diseases such as hyper-eosinophilic syndrome, eosinophilic esophagitis, and eosinophilic granulomatosis with polyangiitis (EGPA), the development of biologics inhibiting eosinophilic inflammation have offered targeted therapeutic strategies for patients that have not responded well to typical first line drugs, which often have significant adverse side effects with poor disease modification or recurrent relapse with significant morbidity. IL-5 has long been recognized as the key inflammatory cytokine involved in the priming and survival of eosinophils and their proliferation and maturation in eosinophilic disease. There are a number of trials and case series demonstrating the immunomodulatory benefits of anti-IL-5 therapies in these diseases with good clinical responses. Yet, due to the heterogeneity and rarity of these conditions, anti-IL-5 therapies have not resulted in disease remission for all patients. Clearly, further research into the use of anti-IL-5 therapies in various eosinophilic diseases is needed and ongoing investigation into other immune mechanisms underlying chronic eosinophilic diseases may provide alternative therapies for these challenging conditions.

BHLHE40 Promotes TH2 Cell-Mediated Antihelminth Immunity and Reveals Cooperative CSF2RB Family Cytokines.

The transcription factor BHLHE40 is an emerging regulator of the immune system. Recent studies suggest that BHLHE40 regulates type 2 immunity, but this has not been demonstrated in vivo. We found that BHLHE40 is required in T cells for a protective TH2 cell response in mice infected with the helminth Heligmosomoides polygyrus bakeri H. polygyrus elicited changes in gene and cytokine expression by lamina propria CD4+ T cells, many of which were BHLHE40 dependent, including production of the common ß (CSF2RB) chain family cytokines GM-CSF and IL-5. In contrast to deficiency in GM-CSF or IL-5 alone, loss of both GM-CSF and IL-5 signaling impaired protection against H. polygyrus Overall, we show that BHLHE40 regulates the TH2 cell transcriptional program during helminth infection to support normal expression of Csf2, Il5, and other genes required for protection and reveal unexpected redundancy of common ß chain-dependent cytokines previously thought to possess substantially divergent functions.

Anti-interleukin (IL)-5 as a steroid-sparing agent in chronic eosinophilic pneumonia.

Introduction: Anti-interleukin (IL)-5 therapy is a novel drug class clinically effective in patients with diverse eosinophil-related disorders such as allergic eosinophilic asthma, eosinophilic granulomatosis with polyangiitis (EGPA), nasal polyposis, eosinophilic COPD, and other non-pulmonary disorders such as eosinophilic esophagitis. Chronic eosinophilic pneumonia (CEP) is a steroid responsive disorder, however, relapses are common following corticosteroid tapering. Case Study: We present the case of a 42-year-old woman with steroid-dependent relapsing CEP successfully treated with anti-IL-5 antibody. Results: Treatment with anti-IL-5 antibody resulted in remission with the ability to taper off the steroids, and no recurrence of the disease for 6 months. Conclusion: Our case report supports the potential use of anti-IL-5 therapy for remission of patients with CEP with recurrent relapses. Whether, it would also be an effective initial therapy might also be an area that deserves future investigation.

A Pediatric Case of Relapsing Eosinophilic Granulomatosis with Polyangiitis Successfully Treated with Mepolizumab.

We herein report the first pediatric case (a 13-year-old girl) of relapsing eosinophilic granulomatosis with polyangiitis (EGPA) successfully treated with mepolizumab (anti-interleukin-5). She was classified as having EGPA based on the presence of asthma, eosinophilia, pulmonary infiltrates, and extravascular eosinophil infiltration confirmed by a biopsy. She achieved remission after initial oral prednisolone (PSL) therapy, but EGPA relapsed during PSL tapering. Subsequent combined therapy with PSL and tacrolimus did not improve the recurrent disease. Intravenous methylprednisolone pulse therapy was started, followed by oral PSL. During PSL tapering, mepolizumab was added to the treatment, which resulted in sustained remission and successful PSL tapering.

The spectrum of therapeutic activity of mepolizumab.

Introduction: The basis of the development of the anti-interleukin-5 monoclonal antibody mepolizumab was the acknowledgment of the crucial importance of this cytokine in promoting eosinophils production, activation, and survival, which is associated with the eosinophilic asthma phenotype, as well as with other disorders characterized by high levels of eosinophils. Areas covered: All the available literature on the outcomes treatment with mepolizumab in eosinophilic disorders are reviewed, including asthma, chronic rhinosinusitis, esophagitis, granulomatosis with polyangiitis, eosinophilic chronic obstructive pulmonary disease, hypereosinophilic syndrome, and allergic bronchopulmonary aspergillosis. Expert opinion: The efficacy of mepolizumab in eosinophilic asthma is clearly demonstrated by a number of controlled trials and by meta-analyses. Among other eosinophilic disorders, controlled trials are available for chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, hypereosinophilic syndrome, eosinophilic granulomatosis with polyangiitis, and eosinophilic chronic obstructive pulmonary disease. Allergic bronchopulmonary aspergillosis, as well as other minor eosinophilic disorders, are backed only by case reports and are waiting controlled trials to verify the therapeutic role of mepolizumab.