The Role of Interleukin 18/Interleukin 18-Binding Protein in Adult-Onset Still’s Disease and Systemic Juvenile Idiopathic Arthritis

Interleukin 18 (IL-18) is a pro-inflammatory cytokine of the IL-1 family, whose activity is tightly controlled at the level of production, as well as signalization. Notably, it is buffered by its natural inhibitor, IL-18 binding protein (IL-18BP), which is massively present in circulation in normal and in most pathological conditions, thus preventing harmful pro-inflammatory systemic effects of IL-18. IL-18 has long been considered to be involved in the pathophysiology of various inflammatory diseases. However, a first clinical trial using recombinant IL-18BP for the treatment of rheumatoid arthritis and psoriasis gave disappointing results. Direct measurements of unbound, bioactive, free form of circulating IL-18 demonstrated that IL-18 was more specifically involved in adult-onset Still’s disease (AOSD) and systemic juvenile idiopathic arthritis (sJIA) but also in their most severe complication, macrophage activation syndrome (MAS). More importantly, administration of recombinant IL-18BP to patients with AOSD, and sJIA with MAS, showed promising results. This review summarizes available data regarding IL-18 and IL-18BP in AOSD and sJIA in mouse models and humans and shows the importance of IL-18/IL-18BP imbalance in these conditions, leading to the conclusion that IL-18, particularly free IL-18, may be a useful biomarker in these diseases and an interesting therapeutic target.

Detection and Prediction of Macrophage Activation Syndrome in Still’s Disease

Distinguishing between macrophage activation syndrome (MAS) and a simple flare of Still’s disease (SD) may be challenging. We sought to clarify the clinical features and outcome of MAS in SD and to explore predictive factors of MAS development. Demographic and clinical data, treatments, and outcomes were recorded in a cohort of 206 SD patients. SD patients with and without MAS were compared. To explore predictive factors for the development of MAS, patients were compared at the time of SD diagnosis. Twenty (9.7%) patients experienced MAS, which was inaugural in 12 cases. Patients with MAS were more likely to have hepatomegaly (OR, 3.71; 95% CI, 1.14–11.2; p = 0.03) and neurological symptoms (OR, 4.43; 95% CI, 1.08–15.3; p = 0.04) than patients without MAS. Cytopenias, abnormal liver tests, and coagulation disorders were significantly more frequent in patients with MAS; lactate dehydrogenase and serum ferritin levels were significantly higher. An optimized threshold of 3500 μg/L for serum ferritin yielded a sensitivity (Se) of 85% and a negative predictive value (NPV) of 97% for identifying patients with/without MAS. Survival analysis showed that a high ferritin level at the time of SD diagnosis was predictive of MAS development (p < 0.001). Specific factors, including neurological symptoms, cytopenias, elevated LDH, and coagulopathy, may contribute to the early detection of MAS. Extreme hyperferritinemia at the onset of SD is a prognostic factor for the development of MAS.

Adult Still's disease: New horizons

Still's disease in children (systemic juvenile idiopathic arthritis - JIA) and adult Still's disease (ASD) are considered as systemic autoinflammatory diseases of unknown etiology, which are based on similar immunopathogenetic mechanisms associated with genetically determined disorders of the mechanisms of innate immunity. ASD was first described 50 years ago by the English rheumatologist Eric George Lapthorne Bywaters. The molecular basis of ASD immunopathogenesis is the activation of innate immunity associated with NLRP3 inflammasome-dependent mechanisms of inflammation, characterized by the overproduction of “pro-inflammatory” cytokines - interleukin (IL) 1 and IL-18, inducing the synthesis of other proinflammatory inflammatory mediators. A review of new data concerning the mechanisms of immunopathology, clinical polymorphism, laboratory biomarkers and the possibilities of ASD pharmacotherapy is presented.Particular attention is paid to the prospects for the use of monoclonal antibodies to IL-1β - canakinumab. The problems associated with the generality of clinical and laboratory disorders, pathogenetic mechanisms and pharmacotherapy of ASD and coronavirus disease 2019 (COVID-19) are considered.

A Rare Case of Adult-onset Still's Disease Revealed by Acute Myopericarditis

Background: Still's disease in adults is a systemic inflammatory pathology of unknown aetiology, characterized by clinical manifestations associating feverish peaks, arthritis or arthtralgia, transient rashes and hyperferritinemia. Currently, this disease remains a multisystemic disease with generally poor outcome, poorly described in the literature with very few studies unlike other rheumatic diseases, probably underdiagnosed due to its clinical polymorphism. Cardiac forms are quite rare and among the manifestations described, pericarditis remains the most reported entity, myocardial involvement is exceptional. The aim of our observation is to report an exceptional case of discovery of stille disease following a myo-pericarditis mimicking a coronary Sd initially.

An Adult-Onset Still’s Disease During Pregnancy that Delivered a Neonate with Hemophagocytic Lymphohistiocytosis and Severe Liver Failure Requiring Liver Transplantation: A Case Report and Literature Review

Adult-onset Still’s disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology that is categorized as a non-hereditary disease. Neonatal hemophagocytic lymphohistiocytosis (HLH) is also a rare, but potentially fatal condition. Neonatal HLH is one of the causes of neonatal acute liver failure that often requires urgent liver transplantation. The relationship between AOSD during pregnancy and neonatal HLH currently remains unclear. We encountered a case of AOSD that developed during pregnancy, and an offspring was born with neonatal HLH resulting in severe liver failure. The mother with AOSD only presented with liver dysfunction during pregnancy; however, disease activity was exacerbated after delivery. The maternal clinical course was quite severe and refractory that she required biological therapy in addition to high-dose corticosteroids and immunosuppressants. Additionally, the severe condition of the neonate with HLH and acute liver failure required intensive care with the administration of steroids and intravenous immunoglobulin treatments, and ultimately liver transplantation. This is the first case that severe maternal AOSD associated with a neonatal HLH resulted in severe clinical courses. Physicians need to be aware of the risk of a mother with AOSD delivering an offspring with neonatal HLH with potentially acute liver failure.

Adult-Onset Still’s Disease: Novel Biomarkers of Specific Subsets, Disease Activity, and Relapsing Forms

Adult-onset Still’s disease (AOSD) is a systemic inflammatory disease of unknown etiology. Recent studies have demonstrated that the hallmark of AOSD is a cytokine storm, which is characterized by the excessive production of interleukin (IL)-1, IL-6, IL-18, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), suggesting how pro-inflammatory cytokines play an important role in the pathogenesis of this disease. Actually, a certain proportion of patients (around 17–32%) with severe clinical symptoms achieves only partial remission or is resistant to both first-line corticosteroids and second-line DMARDs. These patients are defined as refractory AOSD patients, requiring higher dosage glucocorticoids, longer treatment duration, or the simultaneous introduction of immunosuppressive drugs, further leading to AOSD relapses. In this narrative review, we will analyze the latest literature data to unravel potential pathogenetic factors associated with specific patterns of AOSD disease or relapses in order to identify biomarkers that may guide clinical decisions, eventually leading to new therapeutic options.