Molecular Pathways in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis

Pulmonary arterial hypertension in adults with Still's disease: another pulmonary manifestation associated with HLA-DRB1*15

OBJECTIVES

Inflammatory lung disease in Still's disease (SD) has recently been described. Among its manifestations, pulmonary arterial hypertension (PAH) is a rare and life-threatening event, with only a few case reports published. The objective was to report the largest adult cohort of PAH occurring in the context of SD.

METHODS

We identified 16 adult SD patients with PAH (PAH+) by a call for observations from the CRI-IMIDIATE (Club Rhumatismes & Inflammation - Immune-Mediated Inflammatory Disease Alliance for Translational and Clinical Research) network (https://cri-net.com/recherche/reseau-CRI-Imidiate/) and a search of the French pulmonary hypertension network registry. Patient characteristics and disease evolution were retrospectively compared with those of 111 SD controls without PAH (PAH-) followed in a reference centre.

RESULTS

The profile of patients in the PAH+ and PAH- groups differed: 100% versus 69.4% female (P = .006), 75% versus 17.1% Black (P < .0001), more active SD both at diagnosis and throughout the disease course, and more likely to present macrophage activation syndrome (62.5% vs 14.4%, P < .0001) and exhibit eosinophilia during the disease course (68.7% vs 7.2%, P < .0001). For the 84 out of 127 patients with genetic typing, the HLA-DRB1*15 allele was more prevalent in PAH+ than PAH- patients (8/11 [72.7%] vs 22/73 [30.1%], P = .014). PAH+ patients more frequently received canakinumab and immunosuppressants than did PAH- patients and had higher frequency of drug reactions to interleukin 1 (IL-1) and/or IL-6 inhibitors (37.5% vs 7.2%, P = .002). Mortality was higher in PAH+ than PAH- patients (37.5% vs 0.9%, P < .0001), and all deaths were related to SD flare.

CONCLUSIONS

These results reinforce the association between the HLA-DRB1*15 allele and severe forms of SD and raise the question of therapeutic optimisation in such patients.

Pathogenesis of juvenile idiopathic arthritis

PURPOSE OF REVIEW

To provide an overview of the most recent updates in the pathogenesis of juvenile idiopathic arthritis (JIA).

RECENT FINDINGS

Recent genetic studies on the pathogenesis of JIA have revolved around using in silico multiomic analyses to identify genetic variants that may play a role in the pathogenesis of JIA. Genome wide association studies (GWAS) have provided bulk-RNA and single cell-RNA sequencing datasets to identify groups of enhanced genes, signaling pathways, and other genetic variants. These data have led to the exploration of processes that regulate T-cell receptor signaling and T-cell differentiation, as well as genes linked to interferon-gamma signaling. Immune dysregulation is a major driver of JIA pathogenesis and neutrophil extracellular traps (NETs) are emerging as contributors to disease progression. The contribution of immune cells to the microenvironment in the inflamed joints of patients with JIA may hold the key to how inflammation is regulated and how the immune response from these cells contributes to disease progression.

SUMMARY

This review will focus on emerging insights from large scale multiomic studies, which reveal pathways involved in JIA pathogenesis. In addition, recent studies have identified immune dysregulation, especially in the microenvironment of the inflamed joint.

Unmet needs and research gaps in Still's disease across ages: proceedings from a pediatric and adult joint expert panel

BACKGROUND

Still's disease (SD), including systemic juvenile idiopathic arthritis (sJIA) and adult-onset SD (AOSD), is an inflammatory condition typically characterized by daily fever, arthritis, and skin rash together with neutrophilic leukocytosis, thrombocytosis, and increased acute phase reactants. The reported differences between sJIA and AOSD appear to reflect variations along an inflammatory spectrum influenced by age, rather than differences in the underlying pathology.

METHODS

In February 2023, an expert meeting, including pediatric and adult rheumatologists, was held in Rome, Italy, with the aim of defining more precise and timely strategies for disease management. The following four topics were discussed: (1) early recognition and diagnosis of SD; (2) pathogenetic pathways and possible biomarkers for diagnosis and response; (3) refractory disease and risk factors, and (4) treatment of SD and its complications.

RESULTS

The development of improved diagnostic criteria and validation of biomarkers are important steps towards achieving early diagnosis, although several biomarkers remain to be universally validated and available for clinical practice. Additionally, awareness of important complications of SD, including macrophage activation syndrome and lung disease, is crucial for improving patient outcomes, alongside an improved understanding of risk factors for the development of refractory disease. While interleukin (IL)-1 and IL-6 inhibitors have improved the treatment landscape of SD, harmonizing the therapeutic approach across centers and countries, together with developing treatment strategies for refractory patients, still represents a challenge.

CONCLUSIONS

Here, we summarize the results of discussions among experts, supplemented by relevant literature, and highlight unmet needs in the diagnosis and management of SD.

Clinical and laboratory features of juvenile idiopathic arthritis with wrist involvement: Results of a retrospective cohort study

BACKGROUND

Previous studies in the pre-biological era showed an association of wrist inflammation in juvenile idiopathic arthritis (JIA) with progressive disease course, polyarticular involvement and failure of methotrexate treatment.

AIM

To describe features of JIA, associated with wrist arthritis.

METHODS

Data from about 753 JIA patients were included in this retrospective cohort study. The clinical and laboratory features of patients with and without wrist involvement were analyzed.

RESULTS

Wrist involvement was found in oligoarthritis (5.8%), RF(-)/RF(+) polyarthritis (44.9%/15.0%), enthesitis-related arthritis (17.7%), and systemic (58.6%) JIA categories. Unilateral wrist involvement was typical for oligoarthritis patients, bilateral involvement was either equal to that of unilateral involvement or was more frequent in other categories. Wrist arthritis was found to be associated with female sex, a low incidence of uveitis, and more indications of systemic inflammation, including elevated levels of C-reactive protein, erythrocyte sedimentation rate, and platelets, as well as involvement of the cervical spine, temporomandibular, shoulder, elbow, metacarpophalangeal, proximal interphalangeal, distal interphalangeal, hip, ankle, and tarsus arthritis. The number of patients with hip osteoarthritis and hip replacement was also higher. Wrist arthritis was associated with a lower probability of achieving remission [hazard ratio (HR) = 1.3 (95%CI: 1.0-1.7), P = 0.055], and a higher probability of being treated with biologics [HR = 1.7 (95%CI: 1.3-2.10, P = 0.00009)].

CONCLUSION

Wrist arthritis in JIA patients is a marker of a severe disease course, characterized by more intensive inflammation, unfavorable outcomes, and. requiring more intensive treatment with early administration of biologics. Close monitoring of wrist inflammation with ultrasound and MR assessment with early biological treatment might improve the outcomes.

New discoveries in the genetics and genomics of systemic juvenile idiopathic arthritis

INTRODUCTION

Systemic juvenile idiopathic arthritis (sJIA) is a severe inflammatory condition with onset in childhood. It is sporadic, but elements of its stereotypical innate immune responses are likely genetically encoded by both common variants with small effect sizes and rare variants with larger effects.

AREAS COVERED

Genomic investigations have defined the unique genetic architecture of sJIA. Identification of the class II HLA locus as the strongest sJIA risk factor for the first time brought attention to T lymphocytes and adaptive immune mechanisms in sJIA. The importance of the human leukocyte antigen (HLA) locus was reinforced by recognition that HLA-DRB1*15 alleles are strongly associated with development of drug reactions and sJIA-associated lung disease (sJIA-LD). At the IL1RN locus, genetic variation relates to both risk of sJIA and may also predict non-response to anakinra. Finally, rare genetic variants may have critical roles in disease complications, such as homozygous LACC1 mutations in families with an sJIA-like illness, and hemophagocytic lymphohistiocytosis (HLH) gene variants in some children with macrophage activation syndrome (MAS).

EXPERT OPINION

Genetic and genomic analysis of sJIA holds great promise for both basic discovery of the course and complications of sJIA, and may help guide personalized medicine and therapeutic decision-making.

Comparative efficacy and safety of different drugs in patients with systemic juvenile idiopathic arthritis: A systematic review and network meta-analysis

BACKGROUND

The goal of this study was to estimate the relative efficacy and safety of different biological agents (infliximab, canakinumab, baricitinib, anakinra, adalimumab, tofacitinib, tocilizumab, and rilonacept) compared with placebo for systemic juvenile idiopathic arthritis (JIA) patients, through a network meta-analysis.

METHODS

Pubmed, Embase, and Cochrane Library were searched from database inception to July 2023 for randomized controlled trials comparing different biological agents (infliximab, canakinumab, baricitinib, anakinra, adalimumab, tofacitinib, tocilizumab, and rilonacept) or placebo directly or indirectly in JIA. Bayesian network meta-analyses were conducted. Data was extracted and analyzed by R with gemtc package. The treatment options were ranked using the surface under the cumulative ranking curve (SUCRA) value.

RESULTS

We identified 10 randomized controlled trials and analyzed 898 participants. Canakinumab (odds ratio 55.0, 95% credible intervals 2.4-67.0) was more effective than the placebo, and the difference was statistically significant. However, there was no statistical significance between other drugs versus placebo in terms of the modified ACRpedi30 (P > .05). The SUCRA shows that canakinumab ranked first (SUCRA, 86.9%), anakinra ranked second (SUCRA, 77.7%), adalimumab ranked third (SUCRA, 61.9%), and placebo ranked the last (SUCRA, 6.3%). Nevertheless, there were no notable discrepancies in the occurrence of adverse events, hepatic-related adverse events, infectious adverse event, serious adverse events, and serious infection following treatment with canakinumab, anakinra, tocilizumab, rilonacept, or the placebo. Based on the clustergram of modified ACRpedi30 and adverse events, canakinumab is suggested for JIA according to the surface under SUCRAs considering the symptom and adverse events simultaneously.

CONCLUSIONS

Among patients with JIA, canakinumab exhibited the highest likelihood of being the optimal treatment for achieving the modified ACRpedi30 response rate, and neither of the tested biological agents carried a significant risk of serious adverse events.

Treatment of systemic juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis (sJIA) is an inflammatory disease with hallmarks of severe systemic inflammation, which can be accompanied by arthritis. Contemporary scientific insights set this paediatric disorder on a continuum with its counterpart, adult-onset Still disease (AOSD). Patients with sJIA are prone to complications, including life-threatening hyperinflammation (macrophage activation syndrome (sJIA-MAS)) and sJIA-associated lung disease (sJIA-LD). Meanwhile, the treatment arsenal in sJIA has expanded markedly. State-of-the-art therapeutic approaches include biologic agents that target the IL-1 and IL-6 pathways. Beyond these, a range of novel agents are on the horizon, some of them already being used on a compassionate use basis, including JAK inhibitors and biologic agents that target IL-18, IFNγ, or IL-1β and IL-18 simultaneously. However, sJIA, sJIA-MAS and sJIA-LD still pose challenging conundrums to rheumatologists treating paediatric and adult patients worldwide. Although national and international consensus treatment plans exist for the treatment of 'classic' sJIA, the treatment approaches for early sJIA without arthritis, and for refractory or complicated sJIA, are not well defined. Therefore, in this Review we outline current approaches for the treatment of sJIA and provide an outlook on knowledge gaps.