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The aim – to present the experience of diagnosis, management, and therapy with IL-1 inhibitors in patients with Schnitzler’s syndrome (SchS) according to a multicenter Russian cohort.Materials and methods. In an observational retrospective study for a 10-year period (2012–2022), 17 patients with SchS who were admitted to the hospital or were observed on an outpatient basis, among them 8 women, 9 men, were included in the study. The diagnosis of all corresponded to the Strasbourg diagnostic criteria.Results. The age of patients ranged from 25 to 81 years (Me 53 [46; 56] years). The age at the time of the onset of the disease ranged from 20 to 72 years (Me 46 [39; 54] years), the duration of the disease before diagnosis ranged from 1 to 35 years (Me 6.5 [3; 6] years), in 3 it exceeded 10 years, in the rest it ranged from 1 to 8 years. Infectious and lymphoproliferative diseases, monogenic AIDS (CAPS, TRAPS, HIDS) were excluded from all patients at the prehospital stage. The guiding diagnosis for all was Still’s disease in adults. Clinical manifestations of the disease included: fatigue, lethargy, fatigue, rash and fever in all, skin elements were urticular in all, accompanied by itching in 6 (37.5%). Bone pain had 12 (70.6%), arthralgia – 16 (94.1%), arthritis – 9 (52.9%), myalgia – 7 (41.2%), weight loss in 4 (23.5%). Lymphadenopathy (6), enlarged liver (6), pericarditis (4), angioedema (6), redness and dryness in the eyes (3), sore throat (2), abdominal pain (1), distal polyneuropathy (2), paraesthesia (1), chondritis of the auricles were less common (1). Monoclonal gammopathy was detected in all with a secretion level of 2.9–15.1 g/l: IgMk (n=10 (64.7%)), less often IgMλ (n=2), IgGk (n=2), IgGλ (n=1), IgAλ (n=1). Ben-Jones protein was not detected in any of them. All patients had an increase in the level of ESR, CRP. 16 patients before inclusion in the study received GC (94.1%) with a temporary effect and its escape with dose reduction or cancellation, DMARD – 7, among them methotrexate (5), hydroxychloroquine (2), cyclophosphamide (1), also NSAIDs and antihistamines in all, biological drugs: anti-B-cell the drug rituximab (1), monoclonal AT to IgE – omalizumab in 2 (1 – without effect, 1 – partial effect). 11 patients were prescribed IL-1: canakinumab – 9 (52.9%) subcutaneously once every 8 weeks, anakinra – 4 (23.5%) subcutaneously daily. The duration of taking anakinra, which was prescribed in the test mode, ranged from 1 week to 2.5 months with a further switch to canakinumab in 3. The duration of taking canakinumab at the time of analysis ranged from 7 months to 8 years. Against the background of treatment with IL-1, 10 out of 11 (90.9%) received a complete response from the clinical manifestations of the disease and a decrease in the level of ESR and CRP within a few days. In 1 patient, a partial response was received to the administration of anakinra, and when switching to canakinumab, the effect of treatment was finally lost. 1 patient received IL-6 for 8 months with incomplete effect and transition to IL-1 with positive dynamics. In 1 patient, due to the persistent absence of relapses, the interval between canakinumab injections was increased to 5 months without signs of reactivation, but subsequently, against the background of stress and relapses of the disease, the intervals were reduced to 4 months. A healthy child was born in the same patient on the background of treatment. The tolerability of therapy was satisfactory in all patients, no SAE was noted.Conclusion. SchS is a rare multifactorial/non–monogenic AID that needs to be differentiated from a number of rheumatic diseases and other AIDS. The onset in adulthood, the presence of recurrent urticarial rashes in combination with fever and other manifestations of a systemic inflammatory response are indications for examination for monoclonal secretion. The use of short- or long-acting IL-1 is a highly effective and safe option in the treatment of such patients.

Adam Al-Hakim,1 Anoop Mistry,1 Sinisa Savic1,2 1Department of Clinical Immunology and Allergy, St James’s University Hospital, Leeds, UK; 2Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UKCorrespondence: Sinisa Savic, Leeds Institute of Rheumatic and Musculoskeletal Medicine, Clinical Science Building, St James’s University Hospital, Leeds, LS9 7TF, UK, Tel +441132065567, Email s.savic@leeds.ac.ukAbstract: Systemic autoinflammatory diseases (SAID) are conditions caused by dysregulation or disturbance of the innate immune system, with neutrophils and macrophages the main effector cells. Although there are now more than 40 distinct, genetically defined SAIDs, the genetic/molecular diagnosis remains unknown for a significant proportion of patients with the disease onset in adulthood. This review focuses on new developments related to acquired/late onset SAID, including phenocopies of monogenic disorders, Schnitzler’s syndrome, Adult onset Still’s disease, VEXAS syndrome, and autoinflammatory complications associated with myelodysplastic syndrome.Keywords: autoinflammation, adult onset Still’s disease, inflammasome, VEXAS, Schnitzler’s syndrome

Schnitzler syndrome is a rare autoinflammatory disorder characterized by urticarial rash, joint pain, recurrent fever, leucocytosis, elevated C-reactive protein (CRP) and serum amyloid A (SAA), and monoclonal IgM or IgG gammopathy. According to the Strasbourg criteria, both urticarial rash and gammopathy are mandatorily required for the diagnosis of Schnitzler’s syndrome. However, incomplete variants lacking either skin symptoms or monoclonal gammopathy have also been described. Here, we report a case in which the diagnosis of Schnitzler-like syndrome was made despite the absence of gammopathy, based on neutrophilic dermal inflammation, episodic and excessive increase in inflammatory parameters, and prompt response to anakinra, a soluble IL1 receptor antagonist (sIL-1RA). In addition, we detected neutrophil epitheliotropism, which is highly suggestive of autoinflammatory disease. Using whole-exome sequencing, we were unable to find a causative pathogenic mutation but did find several mutations possibly related to the inflammatory processes in this patient. This and other cases highlight that the existing Strasbourg criteria are too strict to capture Schnitzler-like syndromes that may respond well and rapidly to IL1 inhibition. Recurrent episodes of disease with normalization of inflammatory symptoms in the interval, rapid response to anakinra, and neutrophilic epitheliotropism in a lesional skin biopsy may help confirm the diagnosis of Schnitzler-like syndrome.

Abstract Background Schnitzler’s syndrome (SchS) is a rare autoinflammatory syndrome with diagnostic challenge and be characterized by chronic urticaria, a monoclonal gammopath, periodic fever and bone pain. In addition to the monoclonal gammopathy, bone abnormalities are often found at the site of bone pain in patients with SchS. The remarkable efficacy of interleukin-1 (IL-1) inhibition was also demonstrated in this syndrome. Case presentation We describe a case of refractory chronic urticaria presenting with clinical manifestations consistent with SchS without monoclonal gammopathy. A 43-year-old female patient suffering from recurring of urticaria with periodic fever as well as bone pain for the past 4 years. The patient had leukocytosis and elevated levels of C-reactive protein (CRP) and serum amyloid A (SAA). PET/CT (positron emission tomography/computed tomography) and MRI (magnetic resonance imaging) examination revealed hyper-metabolism areas in both femoral bone marrow. Although bone marrow histology revealed no abnormality, urticarial skin lesions shows neutrophilic infiltrations without evidence of vasculitis. We could not exclude the possibility of SchS. The patient had been treated with antihistamines, steroids, omarizumab, colchicine and cyclosporine A, no therapeutic effect was observed. She was started on canakinumab 150 mg subcutaneous injection with 4 weeks interval. Within 48 h after the first injection, the urticarial rash disappeared, and febrile attack and bone pain had not recurred. Elevated levels of serum CRP and SAA were normalized within a week after the first injection of canakinumab. Conclusions The current case suggests an important role for IL-1 as a mediator in the pathophysiology of SchS-like refractory urticaria with bine pain. It had been presumed that monoclonal gammopathy may not always present in SchS. It is important to avoid delay in diagnosis and initiation of proper treatment in SchS or autoinflammatory conditions resembling SchS.

Abstract Schnitzler’s syndrome is an auto-inflammatory disorder which is characterized by two mandatory features: an urticarial rash and a monoclonal gammopathy. Although the pathophysiology of this syndrome is not yet fully understood, a role for interleukin-1 seems apparent. While this presumed link between interleukin-1 and the monoclonal gammopathy is not yet elucidated, a mutual factor in pathophysiology however seems likely. Here we present a novel hypothesis of a shared pathophysiologic mechanism between Schitzler’s syndrome and monoclonal gammopathy.

Schnitzler's syndrome is a rare autoinflammatory disorder characterized by interleukin-1ß-mediated and neutrophil-dominated inflammation. Neutrophil extracellular traps (NETs) are web-like structures of decondensed chromatin, histones, and antimicrobial peptides released by neutrophils. NETs were initially described in the context of pathogen defense but are also involved in autoimmune-mediated skin diseases. Here, we assessed the role of neutrophil extracellular trap formation (NETosis) in Schnitzler's syndrome. Immunofluorescence co-staining of myeloperoxidase and subnucleosomal complex was performed on lesional skin samples from patients with Schnitzler's syndrome, other neutrophilic dermatoses (cryopyrin-associated periodic syndrome, Sweet syndrome, and pyoderma gangrenosum), urticarial vasculitis and chronic spontaneous urticaria as well as healthy control skin. Blood neutrophils from patients with Schnitzler's syndrome and controls were isolated, and NETosis was induced by phorbol 12-myristate 13-acetate (PMA). Also, NETosis of control neutrophils induced by symptomatic Schnitzler's syndrome sera, cytokines and sub-threshold PMA doses was studied. Immunofluorescence co-staining revealed widespread and substantial NET formation in lesional skin of Schnitzler's syndrome patients but absence of NETs in chronic spontaneous urticaria and control skin. Neutrophils undergoing NETosis were observed in the skin of other neutrophilic diseases too. Correspondingly, blood neutrophils from Schnitzler's syndrome patients showed significantly elevated NETosis rates compared to control neutrophils following stimulation with PMA. Increased NETosis correlated well with high levels of C-reactive protein (CRP). SchS patients with the lowest NETosis rates had persistent joint and bone pain despite IL-1 blockade. Stimulation of control neutrophils and sub-threshold PMA with sera of symptomatic Schnitzler's syndrome patients disclosed enhanced NETosis as compared to control sera. Our results suggest that the induction of NET formation by neutrophils contributes to skin and systemic inflammation and may support the resolution of local inflammation in Schnitzler's syndrome.