Interleukins in Churg-Strauss syndrome

Eosinophilic Granulomatosis with Polyangiitis: Clinical Pathology Conference and Review

Eosinophilic granulomatosis with polyangiitis (EGPA) (formerly Churg-Strauss syndrome) is a small vessel vasculitis associated with asthma and eosinophilia. Despite its rarity, continuous gains are being made in understanding the disease with knowledge advancements regarding its epidemiology, heterogeneous clinical manifestations, management, and outcomes. Large knowledge gaps remain, however, particularly surrounding pathophysiologic and diagnostic uncertainties. There is still an incomplete understanding of the interplay between the eosinophilic and vasculitic processes that are features of disease pathogenesis. EGPA is also a conceptually difficult disorder given its dual categorization with hypereosinophilic syndromes and systemic vasculitides and the absence of a biomarker that can reliably distinguish between the two. In addition, recent evidence points to distinct, but partly overlapping, disease phenotypes, yet there is insufficient understanding to inform phenotype-tailored therapies. EGPA also remains a diagnostic challenge in part because asthma may be the primary or predominant manifestation for years, and the chronic corticosteroid requirement may mask other disease features. Efforts are ongoing to better elucidate pathophysiologic mechanisms, resolve classification issues, better characterize disease manifestations, and further clarify disease subcategorization, all of which will translate into better diagnosis and treatment with the possibility of specifically adapted therapies.

Interferon-α for Induction and Maintenance of Remission in Eosinophilic Granulomatosis with Polyangiitis: A Single-center Retrospective Observational Cohort Study

Objective.

Eosinophilic granulomatosis with polyangiitis (EGPA) is characterized by frequent relapses following induction therapy. Interferon-α (IFN-α) can reverse the underlying Th2-driven immune response and has successfully induced remission in previous reports. We undertook this study to investigate its efficacy and safety in patients with EGPA.

Methods.

We conducted a retrospective monocentric cohort study including 30 patients (16 women) with active EGPA under IFN-α treatment. Primary endpoints were remission induction, occurrence of relapses, prednisolone (PSL) dosage at time of remission, and adverse events. Remission was defined by a Birmingham Vasculitis Activity Score (BVAS) of 0. Pulmonary function tests were recorded at baseline and at time of remission. Health-related quality of life was analyzed by questionnaire at baseline and following 12 months of treatment.

Results.

At baseline, the median BVAS was 6 (interquartile range 4–13.5) and remission or partial response was achieved in 25/30 patients. After initiation of IFN-α treatment, the median PSL dosages could be reduced from 17.5 mg/day at baseline to 5.5 mg/day at time of remission. Following remission, 17 relapses (5 major) in 16 patients were observed. Pulmonary function tests improved and the time of hospitalization decreased. Adverse events at initiation of treatment were common, but mostly transient. Severe adverse events occurred during treatment in 4 patients (autoimmune hepatitis, n = 1; drug-induced neuropathy, n = 3).

Conclusion.

IFN-α treatment results in high rate of remission and maintenance in EGPA with significant reduction in oral corticosteroids, although reversible adverse events may occur. IFN-α represents an alternative therapeutic option in cases of refractory to standard treatment.

Eosinophilia in Rheumatologic/Vascular Disorders

Peripheral and tissue eosinophilia can be a prominent feature of several unique rheumatologic and vascular diseases. These diseases span a wide range of clinical features, histologic findings, therapeutic approaches, and outcomes. Despite the rare nature of these entities--which makes large-scale studies challenging--knowledge has continued to grow regarding their epidemiology, pathophysiology, and management. This review compares and contrasts 5 rheumatologic and vascular conditions in which eosinophilia can be seen: eosinophilic granulomatosis with polyangiitis (Churg-Strauss), immunoglobulin G4-related disease, diffuse fasciitis with eosinophilia, eosinophilia-myalgia syndrome, and eosinophilic myositis.

Cutting edge issues in the Churg-Strauss syndrome

Churg-Strauss syndrome (CSS) is a rare systemic small-vessel vasculitis that develops in the background of bronchial asthma, which is characterized by eosinophilia and eosinophilic infiltration of various tissues. It belongs to the group of antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides. The triggering factors and pathogenesis of CSS are still unknown. The possible role of eotaxin-3 and CCR4-related chemokines in selective recruitment of eosinophils to the target tissues in CSS has been recently suggested, but the role of eosinophilic inflammation in the development of vasculitic lesions is not completely understood. From the clinical view, two distinct phenotypes of the disease are slowly emerging depending on the ANCA-positivity status. Glucocorticoids are still the mainstay of treatment; however, data are accumulating regarding the beneficial role of novel immunosuppressants and biologic compounds, especially in patients with poorer prognosis.

Effective intravenous immunoglobulin therapy for Churg-Strauss syndrome (allergic granulomatous angiitis) complicated by neuropathy of the eighth cranial nerve: a case report

INTRODUCTION

We report the case of a patient with Churg-Strauss syndrome with eighth cranial nerve palsy. Vestibulocochlear nerve palsy is extremely rare in Churg-Strauss syndrome. To the best of our knowledge, only one case of complicated neuropathy of the eighth cranial nerve has been described in a previous report presenting an aggregate calculation, but no differentiation between polyarteritis nodosa and Churg-Strauss syndrome was made. High-dose immunoglobulin was administered to our patient, and her neuropathy of the eighth cranial nerve showed improvement.

CASE PRESENTATION

At the age of 46, a Japanese woman developed Churg-Strauss syndrome that later became stable with low-dose prednisolone treatment. At the age of 52, she developed sudden difficulty of hearing in her left ear, persistent severe rotary vertigo, and mononeuritis multiplex. At admission, bilateral perceptive deafness of about 80dB and eosinophilia of 4123/μL in peripheral blood were found. A diagnosis of cranial neuropathy of the eighth cranial nerve associated with exacerbated Churg-Strauss syndrome was made. Although high doses of steroid therapy alleviated the inflammatory symptoms and markers, the vertigo and bilateral hearing loss remained. Addition of a high-dose immunoglobulin finally resulted in marked alleviation of the symptoms associated with neuropathy of the eighth cranial nerve.

CONCLUSIONS

A high dose of immunoglobulin therapy shows favorable effects in neuropathy of the eighth cranial nerve, but no reports regarding its efficacy in cranial neuropathy have been published.

Increased production of IL-5 and dominant Th2-type response in airways of Churg-Strauss syndrome patients

OBJECTIVE

Churg-Strauss syndrome (CSS) is a rare systemic vasculitis associated with eosinophilia and asthma. We assessed the local immune response in airways of CSS patients with different activity of the disease.

METHODS

Concentration of IL-5, CCL17, CCL22 and CCL26 (ELISA) together with cell expression of T-helper-related genes (real-time PCR array) were measured in bronchoalveolar lavage fluid (BALF) sampled from 11 patients with active CSS, 11 patients with CSS in remission and 9 control subjects with bronchial asthma.

RESULTS

In active CSS, both BALF and blood eosinophil counts were increased (P<0.01). BALF cells in active disease were characterized by an increased expression of Th2 and regulatory-type transcripts: STAT6, STAT3, GATA3, IL4, IL5 and IL10 as compared with asthmatics, and STAT5A, CCR4, FOXP3, IL4, IL5 and IL10 when compared with inactive CSS. There was significant increase in BALF concentration of IL-5 and CCL26 in exacerbation of CSS. CCR4-active chemokines were detected more frequently in active disease. We found a strong positive correlation between clinical parameters of disease activity (BVAS, eosinophilia) and expression of IL4, IL5, IL10 and STAT5A.

CONCLUSION

These results indicate that as compared with asthma, active-CSS patients have much stronger local Th2 response in the airways. Airway cells may contribute to lung eosinophilia in CSS by producing IL-5 and eosinophil active chemokines.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

Intrinsic pathway of apoptosis in peripheral blood eosinophils of Churg-Strauss syndrome

OBJECTIVES

Churg-Strauss syndrome (CSS) is a rare necrotizing vasculitis associated with asthma, blood and tissue eosinophilia and granuloma formation. We wondered whether eosinophil accumulation in CSS results from the defect of intrinsic apoptosis pathway in blood eosinophils, leading to their prolonged survival.

METHODS

We analysed immunophenotype (flow cytometry), expression of apoptosis-related genes (real-time PCR) and spontaneous apoptosis in blood eosinophils isolated from nine patients in exacerbation (active CSS), seven patients in remission (inactive CSS) and 14 matched healthy subjects. Serum IL-5 levels were also measured.

RESULTS

In active CSS, blood eosinophils were characterized by small (<2-fold) decrease in expression of a few genes, primarily proapoptotic (e.g. BCL2L13, CASP2, CARD4) or involved in regulation of NF-kappaB (IKBKB, REL), but they did not differ in the rate of spontaneous apoptosis, when compared with other groups. Only selected genes were positively (BNIPL, PYCARD, CASP8, CRADD, BCAP31), or negatively (IKBKE) correlated with disease activity. In active CSS, eosinophils expressed activation markers (CD69, CD25), especially in subjects with most severe disease and elevated serum IL-5.

CONCLUSIONS

High susceptibility of peripheral blood eosinophils to spontaneous apoptosis in vitro, and minor changes in expression of apoptotic-related genes in transcriptome analysis, do not support the hypothesis on intrinsic defect in apoptosis, as the cause of eosinophil accumulation in CSS.

Update on the use of biologics in primary systemic vasculitides

The introduction of biologic therapies, which selectively target components of the immune system, has revolutionized the treatment of rheumatoid arthritis. Anti-TNF-alpha therapy (infliximab, etanercept and adalimumab) and B-cell-depleting agents, such as rituximab, are the most widely used agents. Increased experience of the use of biologic drugs in other immune-mediated inflammatory diseases has led to the application of biologic therapies in the treatment of primary systemic vasculitis. Conversely, the success of biological agents has improved understanding of the immunopathogenesis of vascular inflammation. The need for biologic agents arises from the failure of the current standard of care to maintain remission while limiting drug toxicity. Evidence for the efficacy of biologic agents does not match that of conventional immunosuppressants yet, but it is building rapidly. This paper reviews the current evidence for the standard of care of patients with vasculitis and the role of biologic therapy in primary systemic vasculitis. In this review, we examine the rationale for using biologics based on the pathophysiology of primary systemic vasculitis. The risks and benefits of the use of biologics are discussed, together with future directions and predictions of these emerging therapies.

Churg-Strauss syndrome

PURPOSE OF REVIEW

Churg-Strauss syndrome is a small-vessel necrotizing vasculitis typically characterized by asthma, lung infiltrates, extravascular necrotizing granulomas and hypereosinophilia. The most recent clinical studies on its pathogenesis and therapeutic management are reviewed here.

RECENT FINDINGS

French and Italian clinical studies found that the clinical characteristics of patients with Churg-Strauss syndrome differed according to their antineutrophil cytoplasmic autoantibody status: cardiomyopathy predominated in antineutrophil cytoplasmic autoantibody-negative patients while necrotizing glomerulonephritis was more often observed in antineutrophil cytoplasmic autoantibody-positive patients. These histologically documented findings suggest the existence of different Churg-Strauss syndrome subtypes, characterized by the predominance of distinct pathogenetic mechanisms. To date, following the therapeutic recommendations for Churg-Strauss syndrome (i.e. corticosteroids and, when required, immunosuppressants), patient outcomes are good, with 5-year survival exceeding 90%, but often with the need to continue low-dose corticosteroids to control residual asthma.

SUMMARY

The precise pathogenetic mechanisms of Churg-Strauss syndrome are only partly elucidated. Recent results suggest that antineutrophil cytoplasmic autoantibodies are probably more involved in the vasculitic manifestations of Churg-Strauss syndrome (e.g. glomerulonephritis) whereas eosinophil tissue infiltration and associated cytotoxicity would be responsible for cardiomyopathy. If confirmed, these results could support individual therapeutic stratification according to the clinical pattern. Furthermore, some patients may benefit from new biologic therapies under development, for example antiinterleukin-5 or antiimmunoglobulin E monoclonal antibodies.

Churg-Strauss syndrome: update on recent developments

Churg-Strauss syndrome (CSS) is a form of primary vasculitis characterized by allergy and angiitis. In the organ systems involved (lung, heart, peripheral nervous system, and so forth), eosinophilic infiltration can be found. Eosinophilia and normochromic normocytic anemia are leading laboratory findings together with elevated IgE. New seromarkers for the activation of endothelial cells, lymphocytes, and eosinophils (soluble thrombomodulin, soluble interleukin-2 receptor, eosinophil cationic protein) may be able to predict a relapse. Antineutrophil cytoplasmic antibodies are found in only approximately 50% of all patients with CSS, and their diagnostic value is questionable. Etiologically, hyperresponsiveness to an antigenic stimulus seems to underlie the syndrome. In asthmatics, cysteinyl leukotriene receptor type 1 antagonists are reported to trigger the disease. Cytokine profile findings on the cells involved in CSS remain contradictory. Some think CSS may be a Th2-mediated disease; its pathophysiology is not known fully. Interleukin-5 and tumor necrosis factor-alpha are elevated in serum and fluid of bronchoalveolar lavage, suggesting target cytokines for future treatment protocols. Treatment consists of glucocorticoid monotherapy. Data on outcome and effectiveness is lacking for other immunosuppressive regimens, such as cyclophosphamide or glucocorticoid plus cyclophosphamide. Treatment with interferon-alpha has been effective in patients refractory to glucocorticoid plus cyclophosphamide.