B cell subsets in adult-onset Still's disease: potential candidates for disease pathogenesis and immunophenotyping

Advancing personalised precision treatment for Still's disease based on molecular characteristics and disease progression

Still's disease, a systemic autoinflammatory disorder with a classic multigenetic background, is characterised by polyarthritis, high-spiking fever, salmon-like evanescent skin rash, and hyperferritinaemia. Although the exact cause of Still's disease remains unclear, it is believed to be influenced by genetic factors, infections, and immune dysregulation. Current studies indicate that neutrophils and macrophages play crucial roles in the pathogenesis of Still's disease, along with involvement of natural killer cells, T cells, and B cells. Advances in biologic agents have expanded treatment strategies beyond conventional approaches, with cytokine-targeted agents showing promise in the management of Still's disease. Some cytokine-targeting biologic agents can be developed based on clinical manifestations, complications, immune cells, and molecular networks. Emphasis of immunophenotyping for precise clinical subtyping and targeted molecular therapies based on these findings is crucial for optimising treatment outcomes. In this Review, we discuss the latest advancements in the understanding of Still's disease pathogenesis and corresponding therapeutic approaches.

Indices and ferritin level that predict organ involvement in adult-onset Still's disease

Aim: The aim of the study is to evaluate whether C-reactive protein to albumin ratio (CAR), lactate dehydrogenase to albumin ratio (LAR), ferritin to erythrocyte sedimentation rate ratio (FER), systemic immune-inflammation index (SII), prognostic nutritional index (PNI) indices and ferritin level can predict organ involvement in adult-onset Still's disease (AOSD) patients.Methods: This study was planned as a cross-sectional study. Univariate and multivariate logistic regression analyses were performed to evaluate the usefulness of ferritin level and inflammatory indices in defining organ involvement.Results: Sixty-one patients diagnosed with AOSD were included in this study. Multivariate logistic regression analyzes showed that LAR (OR 1.028, 95% CI: 1.011-1.044) (p = 0.001) index predicted lymphadenopathy involvement, CAR (OR 1.249, 95% CI: 1.087-1.435) (p = 0.002) index predicted hepatomegaly involvement, ferritin level (OR 1.004, 95% CI: 1.001-1.008) (p = 0.007) predicted splenomegaly involvement, FER (OR 1.085, 95% CI: 1.012-1.164) (p = 0.021) and PNI (OR 0.271, 95% CI: 1.132-0.553) (p < 0.001) index predicted the occurrence of serositis.Conclusion: This study showed that ferritin level, CAR, FER, PNI and LAR markers may predict organ involvement at diagnosis in AOSD patients.

Recent advances and evolving concepts in Still's disease

Still's disease is a rare inflammatory syndrome that encompasses systemic juvenile idiopathic arthritis and adult-onset Still's disease, both of which can exhibit life-threatening complications, including macrophage activation syndrome (MAS), a secondary form of haemophagocytic lymphohistiocytosis. Genetic insights into Still's disease involve both HLA and non-HLA susceptibility genes, suggesting the involvement of adaptive immune cell-mediated immunity. At the same time, phenotypic evidence indicates the involvement of autoinflammatory processes. Evidence also implicates the type I interferon signature, mechanistic target of rapamycin complex 1 signalling and ferritin in the pathogenesis of Still's disease and MAS. Pathological entities associated with Still's disease include lung disease that could be associated with biologic DMARDs and with the occurrence of MAS. Historically, monophasic, recurrent and persistent Still's disease courses were recognized. Newer proposals of alternative Still's disease clusters could enable better dissection of clinical heterogeneity on the basis of immune cell profiles that could represent diverse endotypes or phases of disease activity. Therapeutically, data on IL-1 and IL-6 antagonism and Janus kinase inhibition suggest the importance of early administration in Still's disease. Furthermore, there is evidence that patients who develop MAS can be treated with IFNγ antagonism. Despite these developments, unmet needs remain that can form the basis for the design of future studies leading to improvement of disease management.

Deep Immunophenotyping of Circulating T and B Cells in Relapsing Adult-Onset Still's Disease

Adult-onset Still's disease (AOSD) is a complex systemic inflammatory disorder, categorized as an 'IL-1 driven' inflammasomapathy. Despite this, the interaction between T and B cells remains poorly understood. We conducted a study, enrolling 7 patients with relapsing AOSD and 15 healthy control subjects, utilizing deep flow cytometry analysis to examine peripheral blood T- and B-cell subsets. T-cell and B-cell subsets were significantly altered in patients with AOSD. Within CD4+ T cells, Th2 cells were decreased. Additionally, Th17 cell and follicular Th cell subsets were altered within CD45RA-CD62L+ and CD45RA-CD62L- Th cells in patients with AOSD compared to healthy controls. We identified changes in CD8+ T cell maturation and 'polarization' in AOSD patients, with an elevated presence of the TEMRA CD8+ T cell subset. Furthermore, the percentage of Tc1 cells was decreased, while the frequency of CCR6-CXCR3- Tc2 cells was elevated. Finally, we determined that the frequency of CD5+CD27- B cells was dramatically decreased in patients with AOSD compared to healthy controls. Further investigations on a large group of patients with AOSD are required to evaluate these adaptive immunity cells in the disease pathogenesis.