Hydroxychloroquine in children with proliferative lupus nephritis: a randomized clinical trial

Molecular characterisation of lupus low disease activity state (LLDAS) and DORIS remission by whole-blood transcriptome-based pathways in a pan-European systemic lupus erythematosus cohort

OBJECTIVES

To unveil biological milieus underlying low disease activity (LDA) and remission versus active systemic lupus erythematosus (SLE).

METHODS

We determined differentially expressed pathways (DEPs) in SLE patients from the PRECISESADS project (NTC02890121) stratified into patients fulfilling and not fulfilling the criteria of (1) Lupus LDA State (LLDAS), (2) Definitions of Remission in SLE remission, and (3) LLDAS exclusive of remission.

RESULTS

We analysed data from 321 patients; 40.8% were in LLDAS, and 17.4% in DORIS remission. After exclusion of patients in remission, 28.3% were in LLDAS. Overall, 604 pathways differed significantly in LLDAS versus non-LLDAS patients with an false-discovery rate-corrected p (q)<0.05 and a robust effect size (dr)≥0.36. Accordingly, 288 pathways differed significantly between DORIS remitters and non-remitters (q<0.05 and dr≥0.36). DEPs yielded distinct molecular clusters characterised by differential serological, musculoskeletal, and renal activity. Analysis of partially overlapping samples showed no DEPs between LLDAS and DORIS remission. Drug repurposing potentiality for treating SLE was unveiled, as were important pathways underlying active SLE whose modulation could aid attainment of LLDAS/remission, including toll-like receptor (TLR) cascades, Bruton tyrosine kinase (BTK) activity, the cytotoxic T lymphocyte antigen 4 (CTLA-4)-related inhibitory signalling, and the nucleotide-binding oligomerization domain leucine-rich repeat-containing protein 3 (NLRP3) inflammasome pathway.

CONCLUSIONS

We demonstrated for the first time molecular signalling pathways distinguishing LLDAS/remission from active SLE. LLDAS/remission was associated with reversal of biological processes related to SLE pathogenesis and specific clinical manifestations. DEP clustering by remission better grouped patients compared with LLDAS, substantiating remission as the ultimate treatment goal in SLE; however, the lack of substantial pathway differentiation between the two states justifies LLDAS as an acceptable goal from a biological perspective.

Advancements on the impact of hydroxychloroquine in systemic lupus erythematosus

Hydroxychloroquine (HCQ) has gained significant attention as a therapeutic option for systemic lupus erythematosus (SLE) because of its multifaceted mechanism of action. It is a lipophilic, lysosomotropic drug, that easily traverses cell membranes and accumulates in lysosomes. Once accumulated, HCQ alkalizes lysosomes within the cytoplasm, thereby disrupting their function and interfering with processes like antigen presentation. Additionally, HCQ has shown potential in modulating T-cell responses, inhibiting cytokine production, and influencing Toll-like receptor signaling. Its immunomodulatory effects have generated interest in its application for autoimmune disorders. Despite its established efficacy, uncertainties persist regarding the optimal therapeutic concentrations and their correlation with adverse effects such as retinal toxicity. Therefore, standardized dosing and monitoring guidelines are crucial. In this study, we provide a comprehensive review of the mechanisms, efficacy, dosing variations, and retinal toxicity profiles of HCQ, which are essential to optimize SLE treatment protocols and ensure patient safety.

Managing Lupus Nephritis in Children and Adolescents

Lupus nephritis is an important manifestation of systemic lupus erythematosus, which leads to chronic kidney disease, kidney failure, and can result in mortality. About 35%-60% of children with systemic lupus erythematosus develop kidney involvement. Over the past few decades, the outcome of patients with lupus nephritis has improved significantly with advances in immunosuppressive therapies and clinical management. Nonetheless, there is a paucity of high-level evidence to guide the management of childhood-onset lupus nephritis, because of the relatively small number of patients at each centre and also because children and adolescents are often excluded from clinical trials. Children and adults differ in more ways than just size, and there are remarkable differences between childhood- and adult-onset lupus nephritis in terms of disease severity, treatment efficacy, tolerance to medications and most importantly, psychosocial perspective. In this article, we review the 'art and science' of managing childhood-onset lupus nephritis, which has evolved in recent years, and highlight special considerations in this specific patient population.

Hydroxychloroquine in nephrology: current status and future directions

Hydroxychloroquine is one of the oldest disease-modifying anti-rheumatic drugs in clinical use. The drug interferes with lysosomal activity and antigen presentation, inhibits autophagy, and decreases transcription of pro-inflammatory cytokines. Owing to its immunomodulatory, anti-inflammatory, anti-thrombotic effect, hydroxychloroquine has been an integral part of therapy for systemic lupus erythematosus and lupus nephritis for several decades. The therapeutic versatility of hydroxychloroquine has led to repurposing it for other clinical conditions, with recent studies showing reduction in proteinuria in IgA nephropathy. Research is also underway to investigate the efficacy of hydroxychloroquine in primary membranous nephropathy, Alport's syndrome, systemic vasculitis, anti-GBM disease, acute kidney injury and for cardiovascular risk reduction in chronic kidney disease. Hydroxychloroquine is well-tolerated, inexpensive, and widely available and therefore, should its indications expand in the future, it would certainly be welcomed. However, clinicians should be aware of the risk of irreversible and progressive retinal toxicity and rarely, cardiomyopathy. Monitoring hydroxychloroquine levels in blood appears to be a promising tool to evaluate compliance, individualize the dose and reduce the risk of retinal toxicity, although this is not yet standard clinical practice. In this review, we discuss the existing knowledge regarding the mechanism of action of hydroxychloroquine, its utility in lupus nephritis and other kidney diseases, the main adverse effects and the evidence gaps that need to be addressed in future research. Created with Biorender.com. HCQ, hydroxychloroquine; GBM, glomerular basement membrane; mDC, myeloid dendritic cell; MHC, major histocompatibility complex; TLR, toll-like receptor.

Lupus Nephritis in Children: Novel Perspectives

Childhood-onset systemic lupus erythematosus is an inflammatory and autoimmune condition characterized by heterogeneous multisystem involvement and a chronic course with unpredictable flares. Kidney involvement, commonly called lupus nephritis, mainly presents with immune complex-mediated glomerulonephritis and is more frequent and severe in adults. Despite a considerable improvement in long-term renal prognosis, children and adolescents with lupus nephritis still experience significant morbidity and mortality. Moreover, current literature often lacks pediatric-specific data, leading clinicians to rely exclusively on adult therapeutic approaches. This review aims to describe pediatric lupus nephritis and provide an overview of the novel perspectives on the pathogenetic mechanisms, histopathological classification, therapeutic approach, novel biomarkers, and follow-up targets in children and adolescents with lupus nephritis.