Interleukin-5 Antagonist Monoclonal Antibody Therapy Improves Symptoms and Reduces Steroid Dependence in Eosinophilic Myocarditis Patients

Eosinophilic myocarditis (EM) is a rare disease associated with significant morbidity and mortality. This case series follows the clinical courses of 3 patients with EM. The use of mepolizumab, an anti-interleukin-5 monoclonal antibody, as an adjunctive treatment was associated with stabilization of cardiac function and improved long-term outcomes.

Benralizumab in children with severe eosinophilic asthma: Pharmacokinetics and long-term safety (TATE study)

BACKGROUND

Benralizumab is an anti-interleukin-5 receptor α monoclonal antibody approved as an add-on maintenance treatment for patients with uncontrolled severe asthma. Prior Phase 3 studies have evaluated benralizumab in patients aged ≥12 years with severe uncontrolled asthma. The TATE study evaluated the pharmacokinetics (PK), pharmacodynamics (PD), and safety of benralizumab treatment in children.

METHODS

TATE was an open-label, Phase 3 study of benralizumab in children aged 6-11 years from the United States and Japan (plus participants aged 12-14 years from Japan) with severe eosinophilic asthma. Participants received benralizumab 10/30 mg according to weight (<35/≥35 kg). Primary endpoints included maximum serum concentration (Cmax ), clearance, half-life (t1/2 ), and blood eosinophil count. Clearance and t1/2 were derived from a population PK (popPK) analysis. Safety and tolerability were also assessed.

RESULTS

Twenty-eight children aged 6-11 years were included, with an additional two participants from Japan aged 12-14 years also included in the popPK analysis. Mean Cmax was 1901.2 and 3118.7 ng/mL in the 10 mg/<35 kg and 30 mg/≥35 kg groups, respectively. Clearance was 0.257, and mean t1/2 was 14.5 days. Near-complete depletion of blood eosinophils was shown across dose/weight groups. Exploratory efficacy analyses found numerical improvements in mean FEV1 , mean ACQ-IA, patient/clinician global impression of change, and exacerbation rates. Adverse events occurred in 22/28 (78.6%) of participants; none led to discontinuation/death.

CONCLUSION

PK, PD, and safety data support long-term benralizumab in children with severe eosinophilic asthma, and were similar to findings in adolescents and adults.

TRIAL REGISTRATION

ClinicalTrials.gov-ID: NCT04305405.

Eosinophilic Patterns in Patients with Seasonal Allergy Affected by Bronchial Asthma and Rhinitis/Rhinosinusitis: Efficacy of Benralizumab in Patients with the Persistent Pattern

BACKGROUND

Eosinophilia can be influenced by multiple factors. This study aims to set a protocol for monitoring blood absolute eosinophil count (AEC) in patients with seasonal allergy affected by bronchial asthma (BA), allergic rhinitis (AR), or chronic rhinosinusitis with or without nasal polyposis (CRSw/sNP).

METHODS

We planned a total of four annual blood samples to measure AEC in- and out-seasonal pollen exposure (i.e., one measurement every three months for one year).

RESULTS

We identified two distinct groups of patients (non-eosinophilic and eosinophilic). Patients in the eosinophilic group presented with four different patterns (episodic, transient, floating, and persistent). Most patients with episodic, transient, and floating patterns were affected by mild allergy and the increase in eosinophils was related to allergen exposure. In contrast, patients with the persistent pattern mostly presented with more severe allergy (i.e., severe BA and relapsing CRSwNP) and the eosinophilia was unrelated to allergen exposure. The subgroup of patients with severe BA, relapsing CRSwNP, and persistent eosinophilc pattern were treated with benralizumab, which induced a noteworthy improvement in both severe BA and CRSwNP.

CONCLUSIONS

Multiple AEC measurements in patients with seasonal allergy can better reflect patient's eosinophilic status and help define the relationship of AEC enhancement with allergen exposure.

Chicken Interleukin-5 is Expressed in Splenic Lymphocytes and Affects Antigen-Specific Antibody Production

Vaccination is important for reducing disease incidence in the poultry industry. To enhance immunity and vaccine efficacy, chicken cytokines associated with antibody production must be identified. In this study, we focused on interleukin-5 (IL-5), involved in antibody production in mice, measuring its expression and effects on antibody production. Concanavalin A-stimulated splenocytes were used for RT-PCR to clone IL5 cDNAs. Recombinant IL-5 was prepared from the clone and administered to chickens with antigen via the ocular-topical route twice every alternate week. IL-5 enhanced antigen-specific IgY and inhibited antigen-specific serum IgA production in serum. Our findings suggest that IL-5 plays an important role in chicken antibody production, with possible unique functions.

Real-world safety and effectiveness of mepolizumab for patients with eosinophilic granulomatosis with polyangiitis (EGPA) in Japan: 48-week interim analysis of the MARS study

OBJECTIVES

: Assess real-world, long-term safety/effectiveness of mepolizumab for eosinophilic granulomatosis with polyangiitis (EGPA) in Japan.

METHODS

: MARS (GSK ID:213684/NCT04551989) is an ongoing 96-week study of patients with EGPA who received 4-weekly mepolizumab 300 mg subcutaneously for ≥96 weeks before study entry (baseline) and continued treatment. This interim analysis included safety from baseline to Week 48 (observation period) and clinical outcomes before mepolizumab and during the observation period.

RESULTS

: Of 118 patients enrolled, 29% (34/118) experienced adverse events (AEs) of which 13% (15/118) experienced serious AEs; none were considered mepolizumab-related. Median oral corticosteroid (OCS) dose decreased from 6.9 (pre-mepolizumab) to 3.0 (baseline) and 2.0 mg/day (Weeks 45-48); the proportion of patients receiving no OCS increased from 8% to 32% and 38%, respectively. Patients experiencing clinical symptoms decreased from 94% (pre-mepolizumab) to 73% (baseline) and 67% (Week 48). During the observation period, 5% of patients experienced EGPA relapse; rates of EGPA-related hospitalisations, EGPA-related emergency room/unscheduled visits and asthma exacerbations were 0.05, 0.09 and 0.08 event/person-year, respectively.

CONCLUSIONS

: Results of mepolizumab treatment for ≥144 weeks (before baseline plus observation) were consistent with the known safety profile and allowed OCS dose reduction while improving disease control versus pre-treatment among patients with EGPA.

Distinct CRTH2+CD161+ (peTh2) memory CD4+ T-cell cytokine profiles in food allergy and eosinophilic gastrointestinal disorders

INTRODUCTION

Although IgE-mediated food allergy (FA) and eosinophilic gastrointestinal disorders (EGID) are clinically distinct and treated differently, pathogenic effector Th2 (peTh2) cells are implicated in the pathogenesis of both FA and EGID. The aim of this study was to better characterize peTh2 cells in the context of FA and EGID and the overlap between these two conditions.

METHODS

Peripheral blood peTh2 cells (CD3+CD4+CD27-CD49d+CRTH2+CD161+) were profiled by intracellular cytokine flow cytometry in the following patient cohorts: patients with FA alone (n = 8), FA and food-triggered EGID (EGID+FA+FT, n = 7), food-triggered EGID alone (EGID+FT, n = 7), EGID without FA or specific food triggers (ONLY_EGID, n = 9), and healthy volunteers (HV, n = 7). Overnight peripheral blood mononuclear cell (PBMC) culture supernatants were assessed for cytokine production by multiplex analysis.

RESULTS

CRTH2+CD161+ (peTh2) memory CD4+ T cells were significantly increased in both patients with FA and those with ALL_EGID (inclusive of EGID+FA+FT, EGID+FT and ONLY_EGID) when compared to HV. However, ALL_EGID patients, particularly those with EGID+FA+FT, had significantly elevated IL-5+IL-13+ peTh2 cells, whereas FA patients had significantly elevated IFN-γ or IL-17A-expressing peTh2 cells. This finding was supported by increased spontaneous IL-5 and IL-13 production in overnight cultures of PBMC from EGID+FA+FT patients compared to spontaneous IL-10 and IFN-γ production by PBMC from FA patients. FA patients had increased IL-9, IL-10, IL-17A, and IFN-γ production in overnight cultures of stimulated PBMC.

CONCLUSIONS

EGID and IgE-mediated FA share a common cell subtype defined by specific surface markers and termed CRTH2+CD161+ (peTh2) memory CD4+ T cells. However, the cytokine profiles of these CRTH2+CD161+ (peTh2) memory CD4+ T cells are markedly different between the two disorders.

An early Indian experience with benralizumab - A compendium on severe asthma cases: a case series

Background: Severe eosinophilic asthma (SEA), one of the phenotypes of asthma that is characterized by elevated blood eosinophil counts, is a common cause of uncontrolled asthma. Patients with SEA often experience severe persistent symptoms and have frequent exacerbations despite optimal inhaler therapy. They also have poor lung function and quality of life (QoL). Benralizumab (Fasenra), a monoclonal antibody, has been approved for managing cases of SEA. This series of six cases, the first of its kind from India, aims to add to the real-world evidence of benralizumab in India. Methods: Benralizumab 30 mg (once in four weeks for the first three doses followed by a dose every eight weeks for two years) was administered in six patients with symptoms of cough, breathlessness on exertion, and wheezing, diagnosed with SEA. The following were the endpoints assessed: (i) overlap between high immunoglobulin E (IgE) and eosinophilic asthma; (ii) reduction of exacerbations; (iii) withdrawal of oral corticosteroids; and (iv) improvement in lung function and QoL. Results: In all cases, management with benralizumab resulted in optimal clinical and functional improvement, a decline in systemic steroid use, and improved QoL. Conclusions: The cases presented here are the first of their kind in the Indian asthmatic population with all SEA patients demonstrating significant improvement in symptoms with the use of benralizumab.

Eosinophilic Granulomatosis with Polyangiitis: Latest Findings and Updated Treatment Recommendations

Eosinophilic granulomatosis with polyangiitis (EGPA) causes necrotizing vasculitis and eosinophil-rich granulomatous inflammation in small- to medium-sized vessels, resulting in multiple organ damage. EGPA is classified as an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, with myeloperoxidase-ANCA detected in approximately one-third of the patients. Conventional treatment of EGPA relies on systemic glucocorticoids (GCs) in combination with cyclophosphamide when poor prognostic factors are present; however, the dilemma between disease control and drug-related adverse effects has long been a challenge. Recent studies have revealed that the genetic background, pathophysiology, and clinical manifestations differ between ANCA-positive and ANCA-negative patients; however, mepolizumab, an interleukin (IL)-5 inhibitor, is effective in both groups, suggesting that the IL-5-eosinophil axis is deeply involved in the pathogenesis of both ANCA-positive and ANCA-negative EGPA. This review summarizes the latest knowledge on the pathophysiology of EGPA and focuses on the roles of eosinophils and ANCA. We then introduce the current treatment recommendations and accumulated evidence for mepolizumab on EGPA. Based on current unmet clinical needs, we discuss potential future therapeutic strategies for EGPA.

Interleukin 5 Receptor Subunit Alpha Expression as a Potential Biomarker in Patients with Nasal Polyposis

Chronic Rhinosinusitis with Nasal Polyposis (CRSwNP) affects the quality of life of patients suffering from it. The search for a suitable biomarker has been conducted over the last decades. Interleukin 5 receptor subunit alpha (IL-5Rα) involves the activation, maintenance, and survival of eosinophils, which are highly tied to chronic inflammatory processes of the airways, like asthma or CRSwNP. In this study, we evaluate the utility of IL5RA as a genetic biomarker in CRSwNP. IL5RA mRNA expression level was analyzed in different groups of patients by performing qPCR assays. A significant increase in IL5RA expression was observed in CRSwNP patients, especially those with asthma and atopy. We found differences in expression levels when comparing groups with or without polyposis or asthma, as well as some atypical cases related to eosinophil levels. That opens a path to future studies to further characterize groups of patients with common features in the context of pharmacogenetics and in an era towards developing a more precise personalized treatment with IL-5Rα as a therapeutic target for CRSwNP.

Current Understanding of the Role of Eosinophils in CRSwNP and Implications for Treatment with Mepolizumab and Benralizumab

BACKGROUND

International consensus statements now subdivide chronic rhinosinusitis (CRS) into several phenotypes and endotypes, including the presence of polyps (CRSwNP) and eosinophilia (eCRSwNP). Biological treatments aimed at blocking eosinophilic inflammation in CRSwNP via interleukin 5 (IL5) or the interleukin 5 receptor (IL5R) have demonstrated limited efficacy thus far.

OBJECTIVE

To review the pathophysiology of eCRSwNP, the evidence for mepolizumab (anti-IL5) and benralizumab (anti-IL5R) in CRSwNP, and to highlight areas for future research and therapeutic intervention.

METHODS

Primary and secondary literature search.

RESULTS

Clinical trials on mepolizumab and benralizumab in CRSwNP are limited and restricted by trial design which prevents direct comparison with other interventions, including surgery. Both agents would appear to provide some benefit in reducing nasal polyp size but limited clinical patient benefit. Molecular biological research highlights that eCRSwNP can occur in the absence of IL5 and that other cells/cytokines play an important part in the disease's pathophysiology.

CONCLUSION

Blockade of IL5/IL5R alone would appear to provide limited "real life" clinical benefit in patients with CRSwNP due to the complexities of the pathophysiology of the condition. Therapy aimed at several simultaneous cytokine targets has logic but well-designed trials are unlikely to be forthcoming in the short term due to the financial cost and commercial conflicts of interest.

IL-33 induces NF-κB activation in ILC2 that can be suppressed by in vivo and ex vivo 17β-estradiol

Asthmatic women tend to develop severe airway disease in their reproductive years, and 30%-40% of asthmatic women have peri-menstrual worsening of asthma symptoms. This indicates that fluctuations in ovarian hormones are involved in advancement of asthmatic disease and exacerbation of symptoms. Group 2 innate lymphoid cells, or ILC2, are readily detected in allergic conditions, such as rhinosinusitis, in individuals that develop nasal polyps do to allergen exposures, and in allergic asthma. ILC2 are airway localized immune cells activated by IL-33, an innate cytokine that perpetuates allergic inflammation by driving the production of IL-5 and IL-13. We have previously shown that ILC2 are highly activated in naïve and ovalbumin (OVA) challenged, female BALB/c mice in comparison to male mice following stimulation with IL-33. Here, we investigated the effect of steady-state ovarian hormones on ILC2 and the NF-κB signaling pathway following OVA sensitization and challenge. We found that estrogen-treated ovariectomized mice (OVX-E2) that had been challenged with OVA had reduced IL-5 and IL-13 production by lung ILC2 as compared to lung ILC2 isolated from intact male and female sham-operated controls that had been treated with OVA. ILC2 were isolated from untreated animals and co-cultured ex vivo with and without estrogen plus IL-33. Those estrogen-treated ILC2 similarly produced less IL-5 and IL-13 in comparison to untreated, and had reduced NF-κB activation. Single-cell RNA sequencing showed that 120 genes were differentially expressed in male and female ILC2, and Nfkb1 was found among top-ranked regulatory interactions. Together, these results provide new insight into the suppressive effect of estrogen on ILC2 which may be protective in female asthmatics. Understanding further how estrogen modulates ILC2 may provide therapeutic targets for the treatment of allergic diseases.

Eosinophils Decrease Pulmonary Metastatic Mammary Tumor Growth

Metastatic breast cancer is challenging to effectively treat, highlighting the need for an improved understanding of host factors that influence metastatic tumor cell colonization and growth in distant tissues. The lungs are a common site of breast cancer metastasis and are host to a population of tissue-resident eosinophils. Eosinophils are granulocytic innate immune cells known for their prominent roles in allergy and Th2 immunity. Though their presence in solid tumors and metastases have been reported for decades, the influence of eosinophils on metastatic tumor growth in the lungs is unclear. We used transgenic mouse models characterized by elevated pulmonary eosinophils (IL5Tg mice) and eosinophil-deficiency (ΔdblGATA mice), as well as antibody-mediated depletion of eosinophils, to study the role of eosinophils in EO771 mammary tumor growth in the lungs. We found that IL5Tg mice exhibit reduced pulmonary metastatic colonization and decreased metastatic tumor burden compared to wild-type (WT) mice or eosinophil-deficient mice. Eosinophils co-cultured with tumor cells ex vivo produced peroxidase activity and induced tumor cell death, indicating that eosinophils are capable of releasing eosinophil peroxidase (EPX) and killing EO771 tumor cells. We found that lung eosinophils expressed phenotypic markers of activation during EO771 tumor growth in the lungs, and that metastatic growth was accelerated in eosinophil-deficient mice and in WT mice after immunological depletion of eosinophils. Our results highlight an important role for eosinophils in restricting mammary tumor cell growth in the lungs and support further work to determine whether strategies to trigger local eosinophil degranulation may decrease pulmonary metastatic growth.

Rapamycin Dampens Inflammatory Properties of Bone Marrow ILC2s in IL-33-Induced Eosinophilic Airway Inflammation

The alarmin cytokine interleukin (IL)-33 plays an important proinflammatory role in type 2 immunity and can act on type 2 innate lymphoid cells (ILC2s) and type 2 T helper (T_H2) cells in eosinophilic inflammation and asthma. The mechanistic target of rapamycin (mTOR) signaling pathway drives immune responses in several inflammatory diseases, but its role in regulating bone marrow responses to IL-33 is unclear. The aim of this study was to determine the role of the mTORC1 signaling pathway in IL-33-induced bone marrow ILC2 responses and its impact on IL-33-induced eosinophilia. Wild-type mice were intranasally exposed to IL-33 only or in combination with the mTORC1 inhibitor, rapamycin, intraperitoneally. Four groups were included in the study: saline-treated (PBS)+PBS, rapamycin+PBS, PBS+IL-33 and rapamycin+IL-33. Bronchoalveolar lavage fluid (BALF), serum and bone marrow cells were collected and analyzed by differential cell count, enzyme-linked immunosorbent assay and flow cytometry. IL-33 induced phosphorylation of the mTORC1 protein rpS6 in bone marrow ILC2s both ex vivo and in vivo. The observed mTOR signal was reduced by rapamycin treatment, indicating the sensitivity of bone marrow ILC2s to mTORC1 inhibition. IL-5 production by ILC2s was reduced in cultures treated with rapamycin before stimulation with IL-33 compared to IL-33 only. Bone marrow and airway eosinophils were reduced in mice given rapamycin before IL-33-exposure compared to mice given IL-33 only. Bone marrow ILC2s responded to IL-33 in vivo with increased mTORC1 activity and rapamycin treatment successfully decreased IL-33-induced eosinophilic inflammation, possibly by inhibition of IL-5-producing bone marrow ILC2s. These findings highlight the importance of investigating specific cells and proinflammatory pathways as potential drivers of inflammatory diseases, including asthma.

Co-exposure of peptidoglycan and heat-inactivated Asian sand dust exacerbates ovalbumin-induced allergic airway inflammation in mice

AIMS

Asian sand dust (ASD) comprises soil particles, microorganisms, and various chemical components. We examined whether peptidoglycan (PGN), a structural cell wall component of Gram-positive bacteria, exacerbates ASD-induced allergic airway inflammation in mice.

METHODS

The ASD (median diameter ∼4 µm) used was a certified reference material from the National Institute for Environmental Studies in Japan, derived from Gobi Desert surface soil collected in 2011. BALB/c mice were intratracheally exposed to PGN, heat-inactivated ASD (H-ASD), and ovalbumin (OVA), individually and in combination. Twenty-four hours after the final intratracheal administration, bronchoalveolar lavage fluid (BALF) and serum samples were collected. Inflammatory cell count, cytokine levels in the BALF, OVA-specific immunoglobulin levels in the serum, and pathological changes in the lungs were analyzed.

RESULTS AND DISCUSSION

After OVA + PGN + H-ASD treatment, the number of eosinophils, neutrophils, and macrophages in the BALF and of eosinophils in the lung tissue was significantly higher than that after OVA + PGN or OVA + H-ASD treatment. Moreover, levels of chemokines and cytokines associated with eosinophil recruitment and activation were significantly higher in the BALF of this group than in that of the OVA + PGN group, and tended to be higher than those in the OVA + H-ASD group. Pathological changes in the lungs were most severe in mice treated with OVA + PGN + H-ASD.

CONCLUSIONS

Our results indicate that PGN is involved in the exacerbation of ASD-induced allergic airway inflammation in mice. Thus, inhalation of ASD containing Gram-positive bacteria may trigger allergic bronchial asthma.

Switching Treatment from Mepolizumab to Benralizumab for Elderly Patients with Severe Eosinophilic Asthma: A Retrospective Observational Study

Objective Switching from mepolizumab to benralizumab has been reported to significantly improve both asthma control and the lung function. However, the data on its efficacy in elderly patients with severe eosinophilic asthma are limited. This study aimed to assess whether elderly patients with severe eosinophilic asthma could experience an improved asthma control and lung function when switching directly from mepolizumab to benralizumab. Methods In this single-center, retrospective study conducted between February 2017 and September 2018, we assessed the effect of switching the treatment directly from mepolizumab to benralizumab on eosinophil levels, exacerbation rates, and lung function. We compared the treatment responses between the two groups using either Fisher's exact test or Mann-Whitney U-test, as appropriate. Patients We enrolled 12 elderly patients (age ≥65 years) with severe eosinophilic asthma treated with mepolizumab at Hiroshima Prefectural Hospital (Hiroshima, Japan) during the study period. Six patients were switched from mepolizumab to benralizumab, and six continued with the mepolizumab treatment. Results The switch from mepolizumab to benralizumab caused a near-complete reduction in the eosinophil count (p=0.008). The annual rate of clinically relevant exacerbations and hospitalizations diminished as well, albeit with no statistical significance. We found no improvement in the lung function after switching treatment and no difference in the treatment response between the groups. Conclusion Although this study is based on a small sample of participants, the results indicate that both mepolizumab treatment and switching from mepolizumab to benralizumab treatment without a washout period have clinically relevant asthma control benefits for elderly patients with severe eosinophilic asthma.

Localization and RNA Interference-Driven Inhibition of a Brugia malayi-Encoded Interleukin-5 Receptor Binding Protein

A molecule we termed Brugia malayi IL-5 receptor (IL-5R) binding protein (BmIL5Rbp; also known as Bm8757) was identified from B. malayi filarial worms and found to inhibit human interleukin-5 (IL-5) binding to its human receptor competitively. After the expression and purification of a recombinant BmIL5Rbp and generation of BmIL5Rbp-specific rabbit antibody, we localized the molecule on B. malayi worms through immunohistochemistry and immunoelectron microscopy. RNA interference (RNAi) was used to inhibit BmIL5Rbp mRNA and protein production. BmIL5Rbp was shown to localize to the cuticle of Brugia malayi and to be released in its excretory/secretory products. RNAi inhibited BmIL5Rbp mRNA production by 33%, reduced the surface protein expression by ~50%, and suppressed the release of BmIL5Rbp in the excretory/secretory products. RNAi has been used successfully to knock down the mRNA and protein expression of BmIL5Rbp in the early larval stages of B. malayi and provided a proof of principle for the local inhibition of the human IL-5R. These findings provide evidence that a parasite-encoded IL-5R antagonist may locally inhibit a vital host innate immune activation of IL-5 on eosinophils.

From DREAM to REALITI-A and beyond: Mepolizumab for the treatment of eosinophil-driven diseases

Effective treatment of inflammatory diseases is often challenging owing to their heterogeneous pathophysiology. Understanding of the underlying disease mechanisms is improving and it is now clear that eosinophils play a complex pathophysiological role in a broad range of type 2 inflammatory diseases. Standard of care for these conditions often still includes oral corticosteroids (OCS) and/or cytotoxic immune therapies, which are associated with debilitating side effects. Selective, biological eosinophil‐reducing agents provide treatment options that improve clinical symptoms associated with eosinophilic inflammation and reduce OCS use. Mepolizumab is a humanized monoclonal antibody that binds to and neutralizes interleukin‐5, the major cytokine involved in eosinophil proliferation, activation, and survival. Mepolizumab is approved for the treatment of severe eosinophilic asthma, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome. Additionally, the efficacy of add‐on mepolizumab has been observed in patients with severe chronic rhinosinusitis with nasal polyposis and chronic obstructive pulmonary disease with an eosinophilic phenotype. Here, we review the development, approval, and real‐world effectiveness of mepolizumab for the treatment of patients with severe eosinophilic asthma, from the DREAM to REALITI‐A studies, and describe how knowledge from this journey extended to the use of mepolizumab and other biologics across a broad spectrum of eosinophilic diseases.

Eosinophilic fasciitis induced by a game of drumming probably via type 2 innate immunity

We report a case of eosinophilic fasciitis triggered by strenuous physical activity, which did not relapse during the follow-up period. We ascertained that interleukin-33 (IL-33) was released from the vascular endothelial cells after intense exercise, inducing type 2 innate lymphocytes (ILC2) and causing fasciitis. A healthy woman experienced itching on both limbs a few hours after a game of drumming. Her hand, knee joints, and legs gradually swelled up with groove signs along the superficial veins. White blood cell and eosinophil counts were significantly elevated. Magnetic resonance imaging revealed a high signal at the fascia on both lower limbs. Histopathological findings of the left lower limb tissue specimen showed edematous fascia with eosinophils. No relapse of eosinophilic fasciitis was observed after finishing treatment with prednisolone. Immunological staining for IL-4, IL-5, IL-33, tumor necrosis factor-α, and interferon-γ was performed on the fascial tissue. Both IL-4 and IL-5 were stained on the lymphocytes at the muscle and fascia levels; however, CD3 and CD4 were unstained in these cells, suggesting that those cells were ILC2. Tumor necrosis factor-α and interferon-γ were unstained. Vascular endothelial cells in the fascia strongly expressed IL-33. Eosinophilic fasciitis may be associated with type 2 immunity triggered by IL-33 in the current case.

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.

Association between the type of allergen and T-helper 2 mediated inflammation in allergic reactions: a systematic review and a meta-analysis

OBJECTIVES

To determine whether the levels of T-helper (T_H) 2 cytokines (interleukin (IL)-4 and IL-5) in allergic reactions are allergen dependent and evaluate the impact of various treatment strategies on the levels of these cytokines.

METHODS

The PubMed search engine was used from inception until January 2021. The random-effects residual maximum likelihood model was performed, and effect sizes were estimated using the Hedge's g statistic. All data analysis was performed using STATA 16.0 (StataCorp LP, TX, USA).

RESULTS

Fourteen studies reporting on 794 participants were included in this study. House dust mite was associated with eliciting a stronger immune response mediated by both IL-4 and IL-5 when compared to pollen. Whereas a mixture of house dust mite and pollen was associated with IL-4-weighted inflammation. Comparisons of IL-4 and IL-5 levels amongst the allergens showed significant differences. The treatment with anti-corticosteroids or allergen-specific immunotherapy was effective in normalising the T_H2 responses and alleviating allergy symptoms.

CONCLUSION

T_H2-mediated inflammation in allergic reactions is allergen-dependent. Therefore, the type of allergen should be considered when using cytokine-targeting biologics in allergic reactions.

Anti-interleukin-5 in the Management of Eosinophilic Asthma: A Review of Effectiveness, Safety, and Budgetary Impact From the Perspective of the Brazilian Health System

OBJECTIVES

To evaluate the efficacy and safety of anti-interleukin-5 class therapy agents in the treatment of eosinophilic asthma and the financial impact of these drugs on the Brazilian and Mato Grosso public health systems.

METHODS

The literature review in important databases was guided by a structured research question including patient or population, intervention, comparator, outcome and type of study. The retrieved studies went through a screening, selection, data extraction, and methodological quality assessment process. A model with two scenarios, one with mepolizumab and the other with benralizumab, was created for budget impact analysis.

RESULTS

Evidence indicated that anti-interleukins-5 have an acceptable safety profile and can reduce exacerbation rates by up to 50% in the population with eosinophilic asthma; however, they showed no significant difference in quality of life. The adoption of these drugs in the Brazilian health system can impact the budget from R$ 40,379,731.50 to R$ 140,301,211.34 depending on the drug incorporated, considering a time horizon of 5 years. From the perspective of the state of Mato Grosso, the budget impact may reach, in the fifth year, an amount of R$ 1,301,210.58 and R$ 2,050.687.62 for the scenarios with mepolizumab and benralizumab, respectively.

CONCLUSION

Anti-interleukins-5 are promising treatments for eosinophilic asthma because they minimise exacerbations and are well tolerated and safe. The financial impact is large, implying that technology costs may be a barrier to accessing this treatment class.

Reverse butterfly pattern image with eosinophilia: Effective treatment with benralizumab-A case report

A 16-year-old adolescent presented with dry cough, fever, weight loss, night sweats, exercise intolerance, and eosinophilia. Computed tomography showed consolidations with "reverse butterfly" pattern. He responded well to corticosteroids but had frequent relapses. He became steroid dependent and developed steroid related morbidity. Benralizumab was prescribed with complete resolution of eosinophilia and lung infiltrates with no adverse effect.

Molecular Targets for Biological Therapies of Severe Asthma: Focus on Benralizumab and Tezepelumab

Asthma is a heterogeneous respiratory disease characterized by usually reversible bronchial obstruction, which is clinically expressed by different phenotypes driven by complex pathobiological mechanisms (endotypes). In recent years several molecular effectors and signaling pathways have emerged as suitable targets for biological therapies of severe asthma, refractory to standard treatments. Indeed, various therapeutic mono-clonal antibodies currently allow one to intercept at different levels the chain of pathogenic events leading to type 2 (T2) airway inflammation. Pro-allergic immunoglobulin E (IgE) is the first molecule against which an anti-asthma monoclonal antibody (omalizumab) was developed; today other targets are successfully being exploited by biological treatments for severe asthma. In particular, pro-eosinophilic interleukin 5 (IL-5) can be targeted by mepolizumab or reslizumab, whereas benralizumab is a selective blocker of IL-5 receptor, and IL-4 and IL-13 can be targeted by dupilumab. Besides these drugs, which are already available in medical practice, other biologics are under clinical development such as those targeting innate cytokines, including the alarmin thymic stromal lymphopoietin (TSLP), which plays a key role in the pathogenesis of type 2 asthma. Therefore, ongoing and future biological therapies are significantly changing severe asthma management on a global level. These new therapeutic options make it possible to implement phenotype/endotype-specific treatments, which are delineating personalized approaches precisely addressing the individual traits of asthma pathobiology. The aim of the study is to review the immunopathology and treatment efficacy for severe asthma and focused on new biological agents with benralizumab (anti-IL-5) and tezepelumab (anti-TSLP).

Interleukin-5-induced eosinophil population improves cardiac function after myocardial infarction

AIMS

Interleukin (IL)-5 mediates the development of eosinophils (EOS) that are essential for tissue post-injury repair. It remains unknown whether IL-5 plays a role in heart repair after myocardial infarction (MI). This study aims to test whether IL-5-induced EOS population promotes the healing and repair process post-MI and to reveal the underlying mechanisms.

METHOD AND RESULTS

MI was induced by permanent ligation of the left anterior descending coronary artery in wild-type C57BL/6 mice. Western blot and real-time polymerase chain reaction revealed elevated expression of IL-5 in the heart at 5 days post-MI. Immunohistostaining indicated that IL-5 was secreted mainly from macrophages and type 2 innate lymphoid cells in the setting of experimental MI. External supply of recombinant mouse IL-5 (20 min, 1 day, and 2 days after MI surgery) reduced the infarct size and increased ejection fraction and angiogenesis in the border zone. A significant expansion of EOS was detected in both the peripheral blood and infarcted myocardium after IL-5 administration. Pharmacological depletion of EOS by TRFK5 pretreatment muted the beneficial effects of IL-5 in MI mice. Mechanistic studies demonstrated that IL-5 increased the accumulation of CD206+ macrophages in infarcted myocardium at 7 days post-MI. In vitro co-culture experiments showed that EOS shifted bone marrow-derived macrophage polarization towards the CD206+ phenotypes. This activity of EOS was abolished by IL-4 neutralizing antibody, but not IL-10 or IL-13 neutralization. Western blot analyses demonstrated that EOS promoted the macrophage downstream signal transducer and activator of transcription 6 (STAT6) phosphorylation.

CONCLUSION

IL-5 facilitates the recovery of cardiac dysfunction post-MI by promoting EOS accumulation and subsequent CD206+ macrophage polarization via the IL-4/STAT6 axis.

TRANSLATIONAL PERSPECTIVE

Accumulating evidence suggests that modulation of innate and adaptive immune responses is a promising therapeutic strategy for myocardial infarction. In this study, we demonstrate that IL-5 exerts cardioprotective effects on infarcted myocardium by promoting eosinophil accumulation and subsequent CD206+ macrophage polarization via the IL-4/STAT6 axis. Hence, regulation of cardiac IL-5 level or eosinophil count may become a therapeutic approach for post-myocardial infarction cardiac repair in humans.

Real-World Multicenter Experience with Mepolizumab and Benralizumab in the Treatment of Uncontrolled Severe Eosinophilic Asthma Over 12 Months

Purpose

Treatment of severe eosinophilic asthma (SEA) has been revolutionized by the development of monoclonal antibodies targeting underlying immunological pathways of eosinophilic asthma. Two of the most frequently used antibodies in clinical practice are mepolizumab, targeting interleukin (IL) 5 and benralizumab, targeting the IL5 receptor alpha. The comparative treatment efficacy of these antibodies remains unclear, particularly regarding long-term outcomes.

Patients and Methods

In this multicenter, retrospective study, we included 123 patients treated with mepolizumab and 64 patients treated with benralizumab for 12 months at one of three study sites in Germany. Data were collected at baseline and after 6 and 12 months of therapy. Endpoints were changes in pulmonary function (PF), exacerbation rate, oral corticosteroid (OCS) use and dose, asthma control test (ACT) score and fractional exhaled nitric oxide (FeNO) levels.

Results

Both mepolizumab and benralizumab led to significant improvements in PF with an increase in median forced expiratory volume (FEV1) after 12 months from 59% to 74% for mepolizumab and 63% to 72% for benralizumab. Treatment also led to significant improvements in ACT scores after 12 months (mepolizumab: 13 [interquartile range (IQR) 9-17] to 19 [IQR 15-23]; benralizumab: 12 [IQR 9-16] to 22 [IQR 16-25]) as well as a reduction of mean OCS dose (mepolizumab 8 mg [IQR 5-12.5 mg] median prednisolone equivalent at baseline to 5 mg [IQR 3-7.5 mg]; benralizumab 7.5 mg [IQR 5-15 mg] to 5 mg [IQR 2-10 mg]). The exacerbation rates were reduced significantly, irrespective of the treatment. Overall, changes were similar after 6 and 12 months of therapy.

Conclusion

Both mepolizumab and benralizumab are highly effective in the long-term treatment of SEA, with no clinically relevant differences in outcomes after 12 months of therapy. In both groups, improvements were similar after 6 and 12 months of therapy, underlining the feasibility of early treatment evaluation.

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.

[Impact of reslizumab on the course of chronic rhinosinusitis in patients with eosinophilic asthma]

Chronic rhinosinusitis (CRS) with polyps is associated with eosinophilic inflammation, in which the key mediator is interleukin - 5 (IL-5) and is often combined with asthma.

RESEARCH OBJECTIVES

To evaluate the therapeutic potential of reslizumab-humanized anti-IL-5 monoclonal antibody for the treatment of CRS with polyps in patients with severe asthma.

PATIENTS AND METHODS

We investigated the cases of 9 patients with severe asthma treated with intravenous reslizumab at a dose of 3 mg per 1 kg of weight with regularity once in 4 weeks. The presence of CRS with polyps was revealed in 7 of 9 patients, SCT scanning of the paranasal sinuses indicated changes in all the patients, 2 patients had symptoms of chronic non-allergic rhinitis (NARES).The treatment effectiveness control was carried out after 6 months from the beginning of the treatment by the dynamics of nasal symptoms (SNOT-22), endoscopic image of the nose, total polyp score (TPS), changes in the SCT of the paranasal sinuses on the Lund-Mackay scale, rhinocytogram, the content of eosinophilic cationic protein in the blood, the level of systemic eosinophilia. The effectiveness of asthma control was assessed by the reduction of the frequency of asthma exacerbations, the need for systemic corticosteroids, spirometry data and Asthma Control Test (ACT) results. Along with a marked improvement in asthma control, 8 out of 9 patients displayed clinical, endoscopic, radiological signs of weakening of nasal symptoms. More significant improvement in asthma control was achieved in patients having CRS with polyps. In the group of patients having CRS with polyps, it was possible to detect anamnestic presence of NARES symptoms in the early stages of the disease. This indicates that NARES can be a precursor to the development of eosinophilic, non-IgE-induced asthma and nasal polyps.

CONCLUSION

Treatment with reslizumab in patients with eosinophilic asthma and concomitant CRS with polyps and chronic non-allergic rhinitis (NARES) leads not only to improved control of asthma symptoms, but also to a significant regression of nasal symptoms.

A Phase II, Multicenter, Randomized, Placebo-Controlled Study of Benralizumab, a Humanized Anti-IL-5R Alpha Monoclonal Antibody, in Patients With Eosinophilic Chronic Rhinosinusitis

BACKGROUND

Strong eosinophil infiltration in chronic rhinosinusitis with nasal polyp (CRSwNP) is highly associated with recalcitrance and higher nasal polyp recurrence rate after surgery. The prevalence of eosinophilic CRSwNP (ECRS) is increasing in Asian countries including Japan. Benralizumab is a humanized anti-IL-5R alpha monoclonal antibody that depletes eosinophils by antibody-dependent cell-mediated cytotoxicity.

OBJECTIVE

To assess the efficacy and safety of benralizumab in patients with ECRS.

METHODS

This phase II, randomized, double-blind, placebo-controlled study was conducted in Japan. Patients were randomized 1:2:2 to placebo, a single administration of benralizumab 30 mg, or benralizumab 30 mg every 4 weeks (q4w) for a total of three doses. The primary endpoint was the change in nasal polyp score from baseline at Week 12.

RESULTS

Overall, 56 patients were enrolled (placebo, n = 11; benralizumab single dose, n = 22; benralizumab q4w, n = 23). Although the mean total nasal polyp score began to decrease after the initiation of benralizumab treatment, there were no statistically significant differences in change in nasal polyp score from baseline at Week 12 between benralizumab and placebo (placebo, -0.5 ± 0.8; benralizumab single, -0.3 ± 0.8; benralizumab q4w, -0.5 ± 1.5). Post-hoc analysis showed that the administration of benralizumab decreased nasal polyp scores ≥2 points in 42.2% of ECRS patients and that patients with high blood eosinophil levels had a greater tendency to respond to benralizumab treatment. The safety profile was similar to that in previous studies and no unexpected adverse events were noted.

CONCLUSION

Although benralizumab did not meet the primary efficacy endpoint, reductions of nasal polyp scores were seen in the benralizumab group compared with the placebo group over the whole study period, especially in patients with high levels of blood eosinophils.

Episodic Angioedema with Hypereosinophilia (Gleich's Syndrome): A Case Report and Extensive Review of the Literature

Episodic angioedema with eosinophilia (EAE) (Gleich's syndrome) is a rare disease characterized by hypereosinophilia (up to 95 × 10⁹ cells/L), recurrent episodes of angioedema, urticaria, weight gain, and fever, that occur at periodical intervals (usually every 3-4 weeks). The exact etiology of EAE is still unclear, but both eosinophils and abnormalities of cytokines homeostasis seem to play a pivotal role in the pathogenesis of the disease. In particular, the cyclic elevation of serum interleukin-5 before the increase in eosinophil count has been reported. Herein, we performed a broad literature review and report the case of a thirty-two-year-old woman with a two-year history of cyclic angioedema attacks, urticaria, periodic weight gain, and severe hypereosinophilia, diagnosed with EAE and treated with oral corticosteroids. Describing the most relevant clinical features of EAE reported so far in the literature, we aim to provide physicians with some useful tools to help them deal with this disease. In addition, we aim to raise awareness about this rare condition in which approved diagnostic classification criteria are currently missing.

A stromal progenitor and ILC2 niche promotes muscle eosinophilia and fibrosis-associated gene expression

Despite the well-accepted view that chronic inflammation contributes to the pathogenesis of Duchenne muscular dystrophy (DMD), the function and regulation of eosinophils remain an unclear facet of type II innate immunity in dystrophic muscle. We report the observation that group 2 innate lymphoid cells (ILC2s) are present in skeletal muscle and are the principal regulators of muscle eosinophils during muscular dystrophy. Eosinophils were elevated in DMD patients and dystrophic mice along with interleukin (IL)-5, a major eosinophil survival factor that was predominantly expressed by muscle ILC2s. We also find that IL-33 was upregulated in dystrophic muscle and was predominantly produced by fibrogenic/adipogenic progenitors (FAPs). Exogenous IL-33 and IL-2 complex (IL-2c) expanded muscle ILC2s and eosinophils, decreased the cross-sectional area (CSA) of regenerating myofibers, and increased the expression of genes associated with muscle fibrosis. The deletion of ILC2s in dystrophic mice mitigated muscle eosinophilia and impaired the induction of IL-5 and fibrosis-associated genes. Our findings highlight a FAP/ILC2/eosinophil axis that promotes type II innate immunity, which influences the balance between regenerative and fibrotic responses during muscular dystrophy.

Immune cells that comprise type II innate immunity coalesce to regulate tissue repair and fibrosis. Kastenschmidt et al. report that ILC2s reside in skeletal muscle, are activated in muscular dystrophy, and promote muscle eosinophilia. Stromal progenitors expressed IL-33, which expanded ILC2s and promoted a transcriptional program associated with muscle fibrosis.

Anti-IL5 Drugs in COVID-19 Patients: Role of Eosinophils in SARS-CoV-2-Induced Immunopathology

SARS-CoV-2 infection stimulates a complex activation of the immune system. Eosinophils belong to the host’s defense equipment against respiratory viruses. In the first phase of the infection, eosinophils contribution is probably appropriate and beneficial, as they facilitate the suppression of the viral replication. However, in severe COVID-19 patients, during the second and third phases of the disease, eosinophils may participate in a maladaptive immune response and directly contribute to immunopathology. In fact, in severe patients, the immune response is prevalently T helper 1 type, but T helper 2 is also present. Eosinophils’ expansion and activation are stimulated by Type 2 cytokines, especially IL-5. Moreover, bronchial asthma, in which eosinophils play a central role, seems not to be a major risk factor for severe COVID-19. Among possible explanations, asthmatic patients are often treated with corticosteroids, which have been demonstrated to reduce the progression to critical COVID-19 in hospitalized patients. In addition to steroids, severe asthmatic patients are currently treated with biological drugs that target Type 2 immune response. Because IL-5 is necessary for the growth, survival, and activation of eosinophils, IL-5 inhibitors, such as mepolizumab, decrease the peripheral blood count of eosinophils, but do not influence eosinophils activation in the airway. In severe COVID-19 patients, the blockade of eosinophils’ activation might contrast harmful immunity.

CCR4-positive peripheral T-cell lymphoma presenting as eosinophilic pneumonia and developing from prolonged pustular psoriasis

A 29-year-old woman with chronic, prolonged pustular psoriasis was admitted to our hospital because of high-grade fever and a systemic skin rash. General examination revealed a whole-body skin rash and superficial lymphadenopathy. Peripheral blood examination showed unclassified cells positive for CD3, CD4, and T-cell receptor αβ, and negative for CD20 and CD56. Soon after administration, she developed acute respiratory failure and required artificial ventilation. Bronchoalveolar lavage fluid showed increased numbers of eosinophils and abnormal lymphocytes of the same phenotype in peripheral blood and skin. She was diagnosed with eosinophilic pneumonia, and her respiratory failure was improved by corticosteroid therapy. Based on the histological findings of skin, lymph node, and bone marrow biopsies, a diagnosis of peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), with positivity for CC chemokine receptor 4 was made. She received chemotherapy followed by allogeneic stem cell transplantation, which resulted in complete remission of her PTCL-NOS. She remained alive and disease-free 6 years later. This is the first reported case of PTCL-NOS developing during the clinical course of pustular psoriasis. The clinical manifestations of PTCL-NOS are complex, but an accurate diagnosis and appropriate therapy may produce a good clinical outcome in patients with PTCL-NOS.

Eosinophil Lineage-Committed Progenitors as a Therapeutic Target for Asthma

Eosinophilic asthma is the most prevalent phenotype of asthma. Although most asthmatics are adequately controlled by corticosteroid therapy, a subset (5-10%) remain uncontrolled with significant therapy-related side effects. This indicates the need for a consideration of alternative treatment strategies that target airway eosinophilia with corticosteroid-sparing benefits. A growing body of evidence shows that a balance between systemic differentiation and local tissue eosinophilopoietic processes driven by traffic and lung homing of bone marrow-derived hemopoietic progenitor cells (HPCs) are important components for the development of airway eosinophilia in asthma. Interleukin (IL)-5 is considered a critical and selective driver of terminal differentiation of eosinophils. Studies targeting IL-5 or IL-5R show that although mature and immature eosinophils are decreased within the airways, there is incomplete ablation, particularly within the bronchial tissue. Eotaxin is a chemoattractant for mature eosinophils and eosinophil-lineage committed progenitor cells (EoP), yet anti-CCR3 studies did not yield meaningful clinical outcomes. Recent studies highlight the role of epithelial cell-derived alarmin cytokines, IL-33 and TSLP, (Thymic stromal lymphopoietin) in progenitor cell traffic and local differentiative processes. This review provides an overview of the role of EoP in asthma and discusses findings from clinical trials with various therapeutic targets. We will show that targeting single mediators downstream of the inflammatory cascade may not fully attenuate tissue eosinophilia due to the multiplicity of factors that can promote tissue eosinophilia. Blocking lung homing and local eosinophilopoiesis through mediators upstream of this cascade may yield greater improvement in clinical outcomes.

Deletion of Arno Reduces Eosinophilic Inflammation and Interleukin-5 Expression in a Murine Model of Rhinitis

BACKGROUND

ARF nucleotide-binding site opener (ARNO) is a guanine nucleotide-exchange factor for ADP-ribosylation factor proteins. ARF nucleotide-binding site opener also binds MyD88, and small-molecule inhibition of ARNO reduces inflammation in animal models of inflammatory arthritis and acute inflammation. However, whether genetic deletion of Arno in mice reduces pathologic inflammation has not yet been reported. Furthermore, its role in the nasal cavity has yet to be investigated.

OBJECTIVE

To generate Arno knockout mice and to determine whether genetic loss of ARNO reduces eosinophilic inflammation in the ovalbumin (OVA) murine model of rhinitis.

METHODS

Arno knockout mice were generated and wild type and knockout littermates were subjected to the OVA-induced mouse model of rhinosinutitis. Eosinophilic inflammation was assessed through immunofluorescent quantification of EMBP⁺ eosinophils in the septal mucosa and cytokine expression was assessed by quantitative polymerase chain reaction.

RESULTS

Arno knockout mice are viable and fertile without any noted deficits. Arno wild type and knockout mice subjected to the OVA-induced model of rhinitis demonstrated an average of 314.5 and 153.8 EMBP⁺ cells per mm² septal tissue, respectively (P < .05). Goblet cells per mm of basal lamina were assessed via Alcian blue and there was no statistically significant difference between Arno wild type and knockout mice. Ovalbumin-induced expression of interleukin-5 (IL-5) was significantly reduced in Arno knockout mice (P < .05). There was no statistically significant reduction in IL-4, IL-13, or eotaxin-1 expression.

CONCLUSIONS

These data demonstrate that deletion of Arno reduces eosinophilic inflammation and IL-5 expression in an OVA-induced model of rhinitis.

Changes in Type 2 Biomarkers After Anti-IL5 Treatment in Patients With Severe Eosinophilic Asthma

Patients with severe eosinophilic asthma (SEA) suffer from frequent asthma exacerbations, where eosinophils are major effector cells in airway inflammation, and anti-interleukin (IL)-5 becomes an effective treatment modality to control eosinophilic inflammation of SEA. Fifteen patients with SEA who had been treated with anti-IL5 (reslizumab, 100 mg monthly intravenously) for 6 months at Ajou University Hospital (Suwon, Korea) were enrolled in this study. Clinical parameters, including total blood eosinophil count (TEC), FEV1%, fractional exhaled nitric oxide (FeNO) levels, and serum biomarkers such as eosinophil-derived neurotoxin (EDN), periostin (PON), and transforming growth factor-β1 (TGF-β1), were analyzed. EDN levels and TEC decreased significantly after 1 month of treatment (P < 0.05 for both), while no changes were noted in FeNO/PON/TGF-β1 levels. FEV1% increased after 2 months of treatment (P < 0.05). A positive correlation was observed between TEC and EDN levels (r = 0.60, P = 0.02). Significant negative correlations were noted between age and TEC/EDN levels (r = -0.57, P = 0.02 and r = -0.56, P = 0.03, respectively). Baseline TEC was higher in the EDN-responder group (≥75% decrease) than in the non-responder group (P = 0.06) with a positive correlation between %reduction in EDN and TEC (r = 0.67, P = 0.01). The onset age was younger and asthma duration was longer in the FEV1%-non-responder group (<12% increase) than in the FEV1%-responder group (P = 0.07 and P = 0.007, respectively). In conclusion, changes in the serum EDN level may be a potential biomarker for monitoring eosinophilic inflammation after anti-IL5 treatment in SEA, which is affected by onset age and asthma duration.

Interleukin-5 deletion promotes sepsis-induced M1 macrophage differentiation, deteriorates cardiac dysfunction, and exacerbates cardiac injury via the NF-κB p65 pathway in mice

Inflammation plays a crucial role in sepsis-induced cardiac injury. The purpose of this study was to determine whether interleukin-5 (IL-5) affected lipopolysaccharide (LPS)-induced cardiac injury by regulating the inflammatory response. First, the expression level and source of cardiac IL-5 were examined, and the results showed that LPS treatment and cecal ligation decreased cardiac IL-5 expression in macrophages. In addition, LPS was used to establish a mouse sepsis model, and the effects of IL-5 deletion on cardiac injury, M1 macrophage differentiation and myocardial cell apoptosis were analyzed. The results showed that IL-5 deficiency significantly increased cardiac injury marker expression, worsened cardiac dysfunction, promoted M1 macrophage differentiation and exacerbated myocardial cell apoptosis in LPS-induced septic mice. The nuclear factor-kappa B (NF-κB) p65 pathway was inhibited by JSH-23, and the results showed that treatment with JSH-23 inhibited M1 macrophage differentiation and alleviated cardiac injury in LPS-treated IL-5-knockout mice. Furthermore, the effects of IL-5 deficiency on M1 macrophage differentiation and myocardial cell apoptosis were measured in vitro. The IL-5-mediated promotion of M1 macrophage differentiation was also reversed by S31-201, and the pro-apoptotic effect of IL-5 knockout on macrophage-mediated myocardial cell apoptosis was also reversed by JSH-23. In conclusion, we found that IL-5 knockout may exacerbate sepsis-induced cardiac injury by promoting M1 macrophage differentiation in mice. IL-5 may be a potential target for the clinical prevention of sepsis-related cardiac injury.

A randomized, placebo-controlled, double-blind pilot study of single-dose humanized anti-IL5 antibody (reslizumab) for the reduction of eosinophilia following diethylcarbamazine treatment of Loa loa infection

BACKGROUND

Diethylcarbamazine citrate (DEC) treatment of loiasis is complicated by adverse reactions that are correlated with the number of circulating microfilariae (mf). The cause of these reactions is unknown, but they are accompanied by a dramatic interleukin-5 (IL-5)-dependent increase in eosinophilia and evidence of eosinophil activation.

METHODS

To explore the role of IL-5 driven eosinophilia in post-DEC reactions, 8 adults with confirmed loiasis and &5000 mf/mL blood were enrolled in a randomized, double-blind, placebo-controlled trial of the humanized anti-IL-5 antibody, reslizumab, (1.0 mg/kg IV) administered 3 to 7 days prior to initiation of DEC treatment (9 mg/kg/day for 21 days). The primary endpoint was the reduction in absolute eosinophil count (AEC) during the first week of DEC treatment.

RESULTS

Baseline characteristics were comparable between the two groups. Single dose reslizumab lowered the AEC by 77% prior to initiation of DEC therapy (vs. 12% in the placebo group, p&0.05). More importantly, AEC remained below baseline in the first week of DEC treatment in all subjects who received reslizumab and in none of the placebo subjects. Mf clearance occurred within 2 days of initiation of DEC in all 7 mf-positive subjects. Mild to moderate adverse events were seen in all 8 subjects and were not significantly different between the groups.

CONCLUSIONS

In summary, although reslizumab was able to blunt peripheral eosinophilia post-DEC treatment in subjects with loiasis and had no effect on microfilarial clearance, the reduction in AEC appeared to have been insufficient to prevent post-treatment AEs.

Eosinophilia Associated With CD3-CD4+ T Cells: Characterization and Outcome of a Single-Center Cohort of 26 Patients

Background: Lymphocytic variant hypereosinophilic syndrome is characterized by marked over-production of eosinophilopoietic factor(s) by dysregulated T cells leading to eosinophil expansion. In most cases, these T cells are clonal and express a CD3^-CD4⁺ phenotype. As this is a rare disorder, presenting manifestations, disease course, treatment responses, and outcome are not well-characterized. Materials and Methods: In this retrospective single-center observational study, we reviewed medical files of all patients with persistent hypereosinophilia seen between 1994 and 2019 in whom CD3^-CD4⁺ T cells were detected. Data collection included clinical and biological findings at presentation, treatment responses, disease course, and serial CD3^-CD4⁺ T cell counts. Results: Our cohort comprises 26 patients, including 2 with hypereosinophilia of undetermined significance. All 24 symptomatic patients had cutaneous lesions and/or angioedema, and fasciitis was present in several cases. The aberrant T cell subset represented 2% or less total lymphocytes in 11 subjects. TCR gene rearrangement patterns on whole blood were polyclonal in these cases, while they all had serum CCL17/TARC levels above 1,500 pg/ml. Disease manifestations were mild and did not require maintenance therapy in roughly one third of the cohort, while two thirds required long-term oral corticosteroids and/or second-line agents. Among these, interferon-alpha was the most effective treatment option with a response observed in 8/8 patients, one of whom was cured of disease. Treatment had to be interrupted in most cases however due to poor tolerance and/or development of secondary resistance. Anti-interleukin-5 antibodies reduced blood eosinophilia in 5/5 patients, but clinical responses were disappointing. A sub-group of 5 patients had severe treatment-refractory disease, and experienced significant disease- and treatment-related morbidity and mortality, including progression to T cell lymphoma in three. Conclusions: This retrospective longitudinal analysis of the largest monocentric cohort of CD3^-CD4⁺ T cell associated lymphocytic variant hypereosinophilic syndrome published so far provides clinicians confronted with this rare disorder with relevant new data on patient presentation and outcome that should help tailor therapy and follow-up to different levels of disease severity. It highlights the need for novel therapeutic options, especially for the subset of patients with severe treatment-refractory disease. Future research efforts should be made toward understanding CD3^-CD4⁺ T cell biology in order to develop new treatments that target primary pathogenic mechanisms.

Interplay Between the IL-33/ST2 Axis and Bone Marrow ILC2s in Protease Allergen-Induced IL-5-Dependent Eosinophilia

Background: Eosinophils develop from CD34⁺ progenitor cells in the bone marrow under the influence of interleukin (IL)-5. Several cell types produce IL-5, including type 2 innate lymphoid cells (ILC2s). The alarmin cytokine IL-33 is known to activate ILC2s in mucosal tissues, but little is known about IL-33-responsive ILC2s in the bone marrow in allergen-induced airway inflammation.

Methods: Wild type (WT) and Rag1 deficient (Rag1^−/−) mice, which lack mature T and B cells, received intranasal doses of papain to induce acute allergic inflammation. In some experiments, mice were pre-treated with anti-IL-5 prior to the papain challenge. Furthermore, recombinant IL-33 was administered to WT mice, Rag1^−/− mice, lymphocyte deficient mice (Rag2^−/−Il2rg^−/−) and to ex vivo whole bone marrow cultures. Bone marrow eosinophils and ILC2s were analyzed by flow cytometry. Eosinophil count was assessed by differential cell count and secreted IL-5 from bone marrow cells by ELISA.

Results: Intranasal administration of papain or IL-33 increased the number of mature eosinophils in the bone marrow despite the absence of adaptive immune cells in Rag1^−/− mice. In parallel, an increased number of eosinophils was observed in the airways together with elevated levels of Eotaxin-2/CCL24. Bone marrow ILC2s were increased after papain or IL-33 administration, whereas ILC2s was found to be increased at baseline in Rag1^−/− mice compared to WT mice. An upregulation of the IL-33 receptor (ST2) expression on bone marrow ILC2s was observed after papain challenge in both Rag1^−/− and WT mice which correlated to increased number of bone marrow eosinophilia. Furthermore, an increased number of ST2⁺ mature eosinophils in the bone marrow was observed after papain challenge, which was further dependent on IL-5. In addition, bone marrow-derived ILC2s from both mouse strains produced large amounts of IL-5 ex vivo after IL-33 stimulation of whole bone marrow cultures. In contrast, IL-33-induced bone marrow and airway eosinophilia were abolished in the absence of ILC2s in Rag2^−/−Il2rg^−/− mice and no production of IL-5 was detected in IL-33-stimulated bone marrow cultures.

Conclusion: These findings establish bone marrow ILC2s and the IL-33/ST2 axis as promising targets for modulation of uncontrolled IL-5-dependent eosinophilic diseases including asthma.

Increased susceptibility to Haemonchus contortus infection by interleukin-5 modulation of eosinophil responses in sheep

Eosinophils are prominent effector cells in immune responses against gastrointestinal nematode infections in ruminants, but their in vivo role has been hard to establish in large animals. Interleukin-5 is a key cytokine in the induction and stimulation of anti-parasitic eosinophil responses. This study attempted to modulate the eosinophil response in sheep through vaccination with recombinant interleukin-5 (rIL-5) and determine the effect on subsequent Haemonchus contortus infection. Nematode-resistant Canaria Hair Breed (CHB) sheep vaccinated with rIL-5 in Quil-A adjuvant, had lower blood eosinophil counts and higher mean worm burdens than control sheep vaccinated with Quil-A adjuvant alone. In addition, adult worms in IL-5-vaccinated sheep were significantly longer with higher eggs in utero in female worms, supporting an active role of eosinophils against adult parasites in CHB sheep. These results confirm that eosinophils can play a direct role in effective control of H contortus infection in sheep and offer a new approach to study immune responses in ruminants.

Matching-adjusted comparison of oral corticosteroid reduction in asthma: Systematic review of biologics

BACKGROUND

Oral corticosteroid (OCS) treatment for severe asthma is associated with substantial disease burden. Thus, OCS dosage reduction is desirable. Relative efficacy of biologics in reducing OCS treatment for severe, uncontrolled asthma is not fully characterized.

OBJECTIVE

We performed a matching-adjusted indirect comparison (MAIC) to assess the relative effects on OCS treatment reduction of three biologic asthma treatments.

METHODS

In MAIC of benralizumab vs. mepolizumab and vs. dupilumab, patient-level data from the Phase III benralizumab OCS-sparing trial, ZONDA, were weighted to match treatment effect-modifying patient characteristics in comparator trials.

RESULTS

After matching adjustment, mean difference between benralizumab and mepolizumab for OCS reduction was 6.08% (95% CI -22.22-34.38; P = .67) by week 24, and odds ratio of OCS elimination was 2.32 (95% CI 0.48-11.15; P = .29). A trend in annual asthma exacerbation rate reduction favouring benralizumab over mepolizumab was observed, although it was not statistically significant (rate ratio [RR] = 0.56 [95% CI 0.28-1.13; P = .11]). Mean difference between benralizumab and dupilumab for OCS reduction was -0.71% (95% CI -20.56-19.15; P = .94), and odds ratio of OCS elimination was 2.26 (95% CI 0.52-9.84; P = .28). A non-significant trend in annual asthma exacerbation rate reduction favouring benralizumab over dupilumab was observed (RR = 0.50 [95% CI 0.20-1.28; P = .15]). Effective sample size was 49% (72 vs. 148) and 25% (36 vs. 142) of original sample size for MAIC of benralizumab vs. mepolizumab and benralizumab vs. dupilumab, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Following patient baseline characteristics matching across clinical trials, benralizumab demonstrated efficacy comparable to mepolizumab and dupilumab for OCS dosage reduction, OCS elimination, and annual exacerbation rate reduction. Comparatively low effective sample sizes indicated substantial differences for patient populations between ZONDA and mepolizumab and dupilumab trials.

IL-5Rα marks nasal polyp IgG4- and IgE-expressing cells in aspirin-exacerbated respiratory disease

BACKGROUND

The cause of severe nasal polyposis in aspirin-exacerbated respiratory disease (AERD) is unknown. Elevated antibody levels have been associated with disease severity in nasal polyps, but upstream drivers of local antibody production in nasal polyps are undetermined.

OBJECTIVE

We sought to identify upstream drivers and phenotypic properties of local antibody-expressing cells in nasal polyps from subjects with AERD.

METHODS

Sinus tissue was obtained from subjects with AERD, chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), CRS without nasal polyps, and controls without CRS. Tissue antibody levels were quantified via ELISA and immunohistochemistry and were correlated with disease severity. Antibody-expressing cells were profiled with single-cell RNA sequencing, flow cytometry, and immunofluorescence, with IL-5Rα function determined through IL-5 stimulation and subsequent RNA sequencing and quantitative PCR.

RESULTS

Tissue IgE and IgG4 levels were elevated in AERD compared with in controls (P < .01 for IgE and P < .001 for IgG4 vs CRSwNP). Subjects with AERD whose nasal polyps recurred rapidly had higher IgE levels than did subjects with AERD, with slower regrowth (P = .005). Single-cell RNA sequencing revealed increased IL5RA, IGHG4, and IGHE in antibody-expressing cells from patients with AERD compared with antibody-expressing cells from patients with CRSwNP. There were more IL-5Rα⁺ plasma cells in the polyp tissue from those with AERD than in polyp tissue from those with CRSwNP (P = .026). IL-5 stimulation of plasma cells in vitro induced changes in a distinct set of transcripts.

CONCLUSIONS

Our study identifies an increase in antibody-expressing cells in AERD defined by transcript enrichment of IL5RA and IGHG4 or IGHE, with confirmed surface expression of IL-5Rα and functional IL-5 signaling. Tissue IgE and IgG4 levels are elevated in AERD, and higher IgE levels are associated with faster nasal polyp regrowth. Our findings suggest a role for IL-5Rα⁺ antibody-expressing cells in facilitating local antibody production and severe nasal polyps in AERD.

Onset of Effect, Changes in Airflow Obstruction and Lung Volume, and Health-Related Quality of Life Improvements with Benralizumab for Patients with Severe Eosinophilic Asthma: Phase IIIb Randomized, Controlled Trial (SOLANA)

Objective

In the SOLANA trial, we sought to physiologically characterize benralizumab’s onset of effect and maintenance of that effect for patients with severe eosinophilic asthma.

Methods

SOLANA (NCT02869438) was a multicenter, randomized, double-blind, parallel-group, placebo-controlled, Phase IIIb study conducted at 49 centers in six countries (Chile, Germany, Hungary, the Philippines, South Korea, and the United States). Eligible patients with baseline blood eosinophil counts ≥300 cells/µL were randomized to subcutaneous benralizumab (30 mg) or placebo administered at Days 0, 28, and 56. The primary endpoint was the average change from baseline in prebronchodilator forced expiratory volume in 1 s (pre-BD FEV₁) during the Day 28‒Day 84 period for benralizumab vs placebo. Secondary endpoints included patient-reported outcomes (PROs). A subset of patients participated in a whole-body plethysmography substudy. Safety was also assessed.

Results

In total, 233 patients were randomized to benralizumab (n=118) or placebo (n=115). Improvement from baseline in pre-BD FEV₁ with benralizumab 30 mg was not statistically significant compared with placebo (least-squares mean change difference [95% confidence interval] 57 mL [−22 to 135]; p=0.16). Compared with placebo, benralizumab demonstrated early (Day 7) nonstatistically significant improvements in whole-body plethysmography assessments of hyperinflation and clinically meaningful improvements in PRO measures (Asthma Control Questionnaire 6 at Day 14 and St. George’s Respiratory Questionnaire at Day 28), which were maintained over the treatment period. Benralizumab’s safety profile was commensurate with previously reported studies.

Conclusion

The observed early changes in lung volume despite relatively small improvements in airflow obstruction suggest that the anti-inflammatory effect of benralizumab may be manifested as deflation over time for patients with hyperinflation, who potentially have a greater degree of airway remodeling. This early effect could partially explain the rapid PRO improvements observed for certain patients.

Mepolizumab add-on therapy in a real world cohort of patients with severe eosinophilic asthma: response rate, effectiveness, and safety

Introduction: Severe eosinophilic asthma is an incapacitating disease. Mepolizumab, a humanized anti-interleukin-5 monoclonal antibody, proved to be effective as an add-on therapy in patients with severe eosinophilic asthma. However, only data from randomized controlled trials are available and real world data are lacking.Methods: A retrospective observational longitudinal study was conducted in a real world cohort of patients with severe eosinophilic asthma treated with mepolizumab. The primary objective was to determine response rate, based on a global evaluation of treatment effectiveness by the treating pulmonologist. Secondary objectives were to assess exacerbation frequency, systemic maintenance glucocorticoid usage, Asthma Control Questionnaire (ACQ), lung function, and adverse events.Results: Seventy-eight patients were included. Treatment with mepolizumab was considered beneficial and was therefore continued in 75.6% of patients 12 months from the initiation of mepolizumab. The most common reason for drop-out was insufficient response. Secondary objectives: 12 months from the initiation of mepolizumab there was a decrease of 3.2 (CI 2.5-4.1; p < 0.001) severe asthma exacerbations per year, a decrease of ACQ of 0.80 points (CI 0.49-1.12; p < 0.001), and an increase of 3.7 (CI 0.3-7.2; p = 0.034) percent of predicted FEV1 compared to baseline. At baseline 51.3% of patients were treated with systemic glucocorticoid maintenance therapy, compared to 15.4% (p < 0.001) of patients 12 months from the initiation of mepolizumab. No serious adverse events considered to be related to mepolizumab were reported.Conclusion: This study confirms that mepolizumab add-on therapy is effective and safe in a real world cohort of patients with severe eosinophilic asthma.

[Clinical and economic analysis of Reslizumab use in the treatment of patients with severe allergic eosinophilic asthma]

Asthma is a heterogeneous chronic disease of airways. One of its endotypes is eosinophilic asthma, accompanied by both peripheral blood and airway eosinophilia, where severe eosinophilia is usually associated with more severe asthma. Anti - interleukin-5 (IL-5) monoclonal antibodies (MAb) can reduce eosinophil counts in peripheral blood and tissues in asthma patients. The first drug of this class registered in Russia was reslizumab.

AIM

Comparative clinical and economic analysis of reslizumab use in patients with allergic asthma and eosinophilia.

MATERIALS AND METHODS

Omalizumab was chosen as a reference drug, because until now it was the only MAb for the treatment of severe asthma in Russia. The study population included patients with allergic asthma with both high levels of IgE and high eosinophil counts in peripheral blood, i.e. individuals eligible for both omalizumab and reslizumab treatment. A decrease in the number of exacerbations requiring prescription of systemic corticosteroids and an increase in QALY index was used as efficacy criteria. An indirect comparative study was used, because no direct comparison has been conducted to date. As a result, reslizumab demonstrated a statistically significant reduction in the frequency of clinically significant asthma exacerbations compared with omalizumab. The utility of the both asthma treatment strategies was compared using Markov models, taking into account the frequency of exacerbations, their severity, as well as decrease in QALYs due to exacerbations. The time horizon was 12 months.

RESULTS

Reslizumab treatment was 37.2% less expensive compared with omalizumab for the patients who are equally eligible for the both drugs. The calculated cost - effectiveness and cost - utility ratios were in favor of reslizumab. Budget impact analysis showed a significant effect of reslizumab on reducing budget costs. If reslizumab is used in 4250 patients (an estimated number of patients with severe allergic asthma and eosinophilia in Russia), this would reduce the costs for their treatment by up to 4896 million rubles per year.

CONCLUSIONS

For patients with severe allergic eosinophilic asthma who are equally eligible for the both drugs, reslizumab can be considered a more reasonable medical technology in terms of pharmacoeconomics when compared with omalizumab.

Frontline Science: Cytokine-mediated developmental phenotype of mouse eosinophils: IL-5-associated expression of the Ly6G/Gr1 surface Ag

Eosinophils have broad and extensive immunomodulatory capacity; recent studies have focused on the roles of distinct eosinophil subsets in specific tissue microenvironments. Ly6G is a GPI-linked leukocyte surface Ag understood primarily as a marker of mouse neutrophils, although its full function is not known. Here, we show that Ly6G/Gr1, detected by mAbs 1A8 (anti-Ly6G) and RB6-8C5 (anti-Gr1), is detected prominently on a significant fraction of eosinophils from mouse bone marrow and bone marrow-derived culture, with fractions expressing this Ag increasing in IL-5-enriched microenvironments. Among our findings, we identified SiglecF⁺ Gr1⁺ eosinophils in bone marrow from naïve, allergen-challenged and IL-5 transgenic mice; SiglecF⁺ Gr1⁺ eosinophils were also prominent ex vivo in bone marrow-derived eosinophils (bmEos) in IL-5-enriched culture. Reducing the IL-5 concentration 20-fold had no impact on the rate of generation of SiglecF⁺ bmEos but did result in a marked increase in the Gr1^- fraction (from 17.4 ± 2% to 30 ± 2.3%, ***P < 0.005). Reducing the IL-5 concentration also enhanced chemotaxis; SiglecF⁺ Gr1^- bmEos were considerably more responsive to eotaxin-1 than were their SiglecF⁺ Gr1⁺ counterparts. These results suggest that (i) IL-5 regulates the expression of Ly6G/Gr1, either directly or indirectly, in cells of the eosinophil lineage, (ii) eosinophils generated in response to high concentrations of IL-5 can be distinguished from those generated under homeostatic conditions by expression of the Ly6G/Gr1 cell surface Ag, and (iii) expression of Ly6G/Gr1 may have an impact on function, directly or indirectly, including the potential to undergo chemotaxis in response to eotaxin-1.

Inflammatory endotypes in COPD

Chronic obstructive pulmonary disease (COPD) is a major global health problem that is poorly treated by current therapies as it has proved difficult to treat the underlying inflammation, which is largely corticosteroid-resistant in most patients. Although rare genetic endotypes of COPD have been recognized, despite the clinical heterogeneity of COPD, it has proved difficult to identify distinct inflammatory endotypes. Most patients have increased neutrophils and macrophages in sputum, reflecting the increased secretion of neutrophil and monocyte chemotactic mediators in the lungs. However, some patients also have increased eosinophils in sputum and this may be reflected by increased blood eosinophils. Increased blood and sputum eosinophils are associated with more frequent exacerbations and predict a good response to corticosteroids in reducing and treating acute exacerbations. Eosinophilic COPD may represent an overlap with asthma but the mechanism of eosinophilia is uncertain as, although an increase in sputum IL-5 has been detected, anti-IL-5 therapies are not effective in preventing exacerbations. More research is needed to link inflammatory endotypes to clinical manifestations and outcomes in COPD and in particular to predict response to precision medicines.