Clinical Relevance of Autoantibodies against Interleukin-2 in Patients with Systemic Lupus Erythematosus

Efficacy, Safety and the Lymphocyte Subset Changes of Low-Dose IL-2 in Patients with Autoimmune Rheumatic Diseases: A Systematic Review and Meta-Analysis

INTRODUCTION

Current therapies for autoimmune rheumatic diseases (ARDs) have limited efficacy in certain patients, highlighting the need for the development of novel treatment approaches. This meta-analysis aims to assess the efficacy and safety of low-dose interleukin-2 (LD-IL-2) and evaluate the alterations in lymphocyte subsets in various rheumatic diseases following administration of different dosages of LD-IL-2.

METHODS

A comprehensive search was conducted in PubMed, Web of Science, the Cochrane Library, Embase databases and CNKI to identify relevant studies. A total of 31 trials were included in this meta-analysis. The review protocols were registered on PROSPERO (CRD42022318916), and the study followed the PRISMA guidelines.

RESULTS

Following LD-IL-2 treatment, patients with ARDs exhibited a significant increase in the number of Th17 cells and Tregs compared to their pre-treatment levels [standardized mean difference (SMD) = 0.50, 95% confidence interval (CI) (0.33, 0.67), P < 0.001; SMD = 1.13, 95% CI (0.97, 1.29), P < 0.001]. Moreover, the Th17/Tregs ratio showed a significant decrease [SMD = - 0.54, 95% CI (- 0.64, - 0.45), P < 0.001]. In patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), LD-IL-2 injection led to a significant increase in Treg numbers, and the Th17/Tregs ratio and disease activity scores, including Disease Activity Score-28 joints (DAS28), Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), were all significantly reduced. No serious adverse events were reported in any of the included studies. Additionally, 54.8% of patients with lupus nephritis achieved distinct clinical remission following LD-IL-2 treatment. Injection site reactions and fever were the most common side effects of LD-IL-2, occurring in 33.1% and 14.4% of patients, respectively.

CONCLUSION

LD-IL-2 treatment showed promise and was well tolerated in the management of ARDs, as it effectively promoted the proliferation and functional recovery of Tregs.

TRIAL REGISTRATION

Retrospectively registered (CRD42022318916, 21/04/2022).

Cytokines as Biomarkers in Systemic Lupus Erythematosus: Value for Diagnosis and Drug Therapy

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease. The disease is characterized by activation and dysregulation of both the innate and the adaptive immune systems. The autoimmune response targets self-molecules including cell nuclei, double stranded DNA and other intra and extracellular structures. Multiple susceptibility genes within the immune system have been identified, as well as disturbances in different immune pathways. SLE may affect different organs and organ systems, and organ involvement is diverse among individuals. A universal understanding of pathophysiological mechanism of the disease, as well as directed therapies, are still missing. Cytokines are immunomodulating molecules produced by cells of the immune system. Interferons (IFNs) are a broad group of cytokines, primarily produced by the innate immune system. The IFN system has been observed to be dysregulated in SLE, and therefore IFNs have been extensively studied with a hope to understand the disease mechanisms and identify novel targeted therapies. In several autoimmune diseases identification and subsequent blockade of specific cytokines has led to successful therapies, for example tumor necrosis factor-alpha (TNF-α) inhibition in rheumatoid arthritis. Authors of this review have sought corresponding developments in SLE. In the current review, we cover the actual knowledge on IFNs and other studied cytokines as biomarkers and treatment targets in SLE.

Anti-Cytokine Autoantibodies in Systemic Lupus Erythematosus

Cytokine dysregulation is characteristic of systemic lupus erythematosus (SLE), a systemic autoimmune disease of considerable heterogeneity. Insights gained about the cytokine dysregulation in SLE have the potential for identifying patient subsets before the onset of clinical disease and during established disease. Clustering patients by cytokine and disease activity subsets is more informative than isolated cytokine studies, as both pro inflammatory and immunoregulatory cytokines contribute to the cytokine dysregulated state in SLE. Endogenous anti-cytokine autoantibodies (ACAAs) may be involved in the regulation of cytokine biology by reducing excessive production or by prolonging their half-life in the circulation through the formation of cytokine-antibody immune complexes. Although endogenous ACAAs may have deleterious effects such as contributing to immunodeficiency states, their role in the pathophysiology of autoimmune conditions such as SLE has yet to be clearly elucidated. The aim of the present article is to provide a focused review of the current knowledge of ACAAs in SLE.