Case Report: Eosinophilic Bronchiolitis With Eosinophil ETosis in Mucus Plugs Successfully Treated With Benralizumab

Eosinophilic bronchiolitis is a rare allergic disorder caused by eosinophilic inflammation in the bronchioles of the lungs. An effective treatment strategy is needed in cases resistant to steroids. However, its pathophysiology remains unclear owing to the limited number of cases. We herein present the case of a 31-year-old man who experienced eosinophilic bronchiolitis with eosinophil ETosis (EETosis) in the mucus plugs. The patient was diagnosed with asthma. His respiratory symptoms worsened with eosinophilia when treated with the standard asthma regimen, including inhaled corticosteroids, long-acting β2-agonist, long-acting muscarinic antagonist, and leukotriene receptor antagonist. Chest computed tomography revealed bronchial wall thickening and centrilobular nodules in the lower lobes of both lungs. Bronchoscopy showed obstruction of the subsegmental bronchus with mucus plugs. Histological analysis demonstrated abundant eosinophils in the mucus plugs. Cytolytic eosinophils together with Charcot–Leyden crystal formations and deposition of major basic proteins were also observed, indicating the occurrence of EETosis. Introduction of benralizumab, an anti-interleukin-5 receptor α antibody, successfully controlled the patient’s condition and reduced the amount of systemic corticosteroids administered. Our findings confirm that this antibody strongly decreases airway eosinophils in patients with severe asthma. Thus, benralizumab might be an optimal therapeutic agent for the treatment of mucus plug-forming and/or EETosis-occurring eosinophilic lung diseases, including eosinophilic bronchiolitis.

Heterogeneous Response of Airway Eosinophilia to Anti-IL-5 Biologics in Severe Asthma Patients

Many questions concerning responders (R) and nonresponders (NR) in severe eosinophilic asthma (SEA) after blocking the IL-5 (interleukin 5) pathway are still not clear, especially regarding the early parameters of response to biologics in personalized treatment strategies. We evaluated 17 SEA patients treated with anti-IL-5 biologics (16 patients mepolizumab, one patient benralizumab) before the introduction of biologics, and at a week 16 follow-up. Clinical, cellular and immunological parameters in peripheral blood were measured in R and NR. Sputum induction with the measurement of cellular and immunological parameters was performed at 16 weeks only. There were 12 R and 5 NR to biologics. After 16 weeks, there was a significant improvement in percentages of FEV1 (p = 0.001), and asthma control test (ACT) (p = 0.001) in the R group, but not in NR. After 16 weeks, the eosinophils in induced sputum were 27.0% in NR and 4.5% in R (p = 0.05), with no difference in IL-5 concentrations (p = 0.743). Peripheral eosinophilia decreased significantly in NR (p = 0.032) and R (p = 0.002). In patients with SEA on anti-IL-5 therapy, there was a marked difference in airway eosinophilic inflammation between R and NR already at 16 weeks, after anti-IL-5 introduction.

Specific Immunotherapy in a Murine Model of Grass Pollen (Phl p5b)-Induced Airway Inflammation

Background: The use of ovalbumin as a model allergen in murine models of allergic asthma is controversially discussed since it is not an aeroallergen and sensitization can only be achieved by using strong Th2-inducing adjuvants. Therefore, in this study, a murine model of asthma has been established in which sensitization against the major grass pollen allergen Phl p5b was performed without using aluminum hydroxide (alum). We used this model for specific immunotherapy.Methods: Female, 5–6-week-old mice were sensitized by six subcutaneous (s.c.) injections of 20 μg Phl p5b followed by four provocations to induce allergic airway inflammation. For desensitization, 1 mg of Phl p5b was injected subcutaneously during allergen challenge for one to a maximum of four times. Three days after the last challenge, the allergic immune response was analyzed.Results: Sensitized and challenged animals showed a significant infiltration of eosinophils into the airways, and the production of interleukin-5 (IL-5) by in vitro re-stimulated splenocytes could be detected. Furthermore, hyper-responsiveness of the airways was verified by invasive measurement of airway resistance in methacholine-challenged animals. Desensitized animals showed a significant reduction of all parameters.Conclusion: In this study, a murine model of asthma has successfully been established by sensitization against the clinically relevant allergen Phl p5b without using alum. S.c. injection of allergen dose dependently led to desensitization of sensitized mice. We suggest that this model is useful to study adjuvant effects of immune modulatory substances on immunotherapy without the interference of alum.

Interleukin-5 (IL-5) Therapy Prevents Allograft Rejection by Promoting CD4+CD25+ Ts2 Regulatory Cells That Are Antigen-Specific and Express IL-5 Receptor

CD4+CD25+Foxp3+T cell population is heterogenous and contains three major sub-groups. First, thymus derived T regulatory cells (tTreg) that are naïve/resting. Second, activated/memory Treg that are produced by activation of tTreg by antigen and cytokines. Third, effector lineage CD4+CD25+T cells generated from CD4+CD25- T cells’ activation by antigen to transiently express CD25 and Foxp3. We have shown that freshly isolated CD4+CD25+T cells are activated by specific alloantigen and IL-4, not IL-2, to Ts2 cells that express the IL-5 receptor alpha. Ts2 cells are more potent than naïve/resting tTreg in suppressing specific alloimmunity. Here, we showed rIL-5 promoted further activation of Ts2 cells to Th2-like Treg, that expressed foxp3, irf4, gata3 and il5. In vivo, we studied the effects of rIL-5 treatment on Lewis heart allograft survival in F344 rats. Host CD4+CD25+T cells were assessed by FACS, in mixed lymphocyte culture and by RT-PCR to examine mRNA of Ts2 or Th2-like Treg markers. rIL-5 treatment given 7 days after transplantation reduced the severity of rejection and all grafts survived ≥60d whereas sham treated rats fully rejected by day 31 (p<0.01). Treatment with anti-CD25 or anti-IL-4 monoclonal antibody abolished the benefits of treatment with rIL-5 and accelerated rejection. After 10d treatment with rIL-5, hosts’ CD4+CD25+ cells expressed more Il5ra and responded to specific donor Lewis but not self. Enriched CD4+CD25+ cells from rIL-5 treated rats with allografts surviving >60 days proliferated to specific donor only when rIL-5 was present and did not proliferate to self or third party. These cells had more mRNA for molecules expressed by Th2-like Treg including Irf4, gata3 and Il5. These findings were consistent with IL-5 treatment preventing rejection by activation of Ts2 cells and Th2-like Treg.

Successful induction treatment of bullous pemphigoid using reslizumab: a case report

Background Bullous pemphigoid (BP) is a potentially life-threatening autoimmune blistering disease which is characterized by autoantibodies against hemidesmosomal proteins of the skin and mucous membranes. In recent years, the role of eosinophil and immunoglobulin E autoantibodies have been further elucidated in BP, and have been considered potential therapeutic targets. Case presentations A 67-year-old male presented with erythematous bullous eruption. The skin eruption was located on whole body, and suggested BP. Peripheral blood eosinophil count and total immunoglobulin E markedly elevated in initial laboratory findings. Topical and systemic steroid (methylprednisolone 2 mg/kg/day) treatment was started, and his skin symptoms worsened repeatedly, whenever systemic steroid were reduced. On admission day 29, reslizumab (anti-interleukin-5) 3.5 mg/kg was administered intravenously to the patients. The bullous skin lesion began to improve rapidly, and methylprednisolone (8 mg/day) was reduced without any worsening of symptoms during two doses of reslizumab. Conclusions We report a case of successful treatment response to reslizumab administration in a patient with BP. Further studies are needed to confirm the role of anti-interleukin-5 as a treatment for BP in the future.