Potential Effects of Interleukins on the Pathogenesis of Systemic Onset Juvenile Idiopathic Arthritis

The role of Interleukin-21 in autoimmune Diseases: Mechanisms, therapeutic Implications, and future directions

IL-21 is a multifunctional cytokine that regulates the functional activity of various immune cells. Initial studies have shown that IL-21 can influence the differentiation, proliferation and function of T and B cells, as well as promote the maturation and increase the cytotoxicity of CD8 + T cells and NK cells. During humoral immune responses, IL-21 has significant effects on B cell activation, differentiation and apoptosis. In addition, IL-21 promotes the differentiation of both naive and memory B cells, ultimately leading to the activation of plasma cells. The function of IL-21 in the immune system is complex, as it has the ability to either stimulate or inhibit immune responses. in addition, IL-21 facilitates the differentiation of naive and memory B cells into plasma cells. The functionality of IL-21 in the immune system is diverse, as it has the ability to stimulate or inhibit immune responses. This cytokine has been implicated in several diseases including cancer, allergies and autoimmune diseases. Research has suggested that this cytokine is involved in the development of autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Several studies have suggested that inhibition of IL-21 has a therapeutic effect on autoimmune diseases. Therefore, targeting both the cytokine's receptor and IL-21 in autoimmune diseases may be an effective approach to reduce the severity of the disease or to treat it. This review will examine the biological effects of IL-21 on various immune cells and the role of the cytokine in autoimmune diseases.

New developments implicating IL-21 in autoimmune disease

Elevated interleukin (IL)-21 is a common finding in the tissues and/or sera of patients with autoimmune disease. CD4 T cells are the primary producers of IL-21; often the IL-21 producing CD4 T cells will express molecules associated with follicular helper cells (T_FH). Recent work has shown that the CD4 T cell-derived IL-21 is able to promote effector functions and memory differentiation of CD8 T cells in chronic infections and cancer. Autoimmunity has similarities to chronic infections and cancer. However, CD4 T cell-derived IL-21:IL21R signaling in CD8 T cells has not been fully appreciated in the context of autoimmunity. In this review, we assess the current knowledge regarding CD4 T cell-derived IL-21 and IL21R signaling within CD8 T cells and evaluate what implications it has within several autoimmune diseases including systemic lupus erythematous, rheumatoid arthritis, juvenile idiopathic arthritis, type 1 diabetes mellitus, psoriasis, Sjögren's syndrome, vitiligo, antiphospholipid syndrome, pemphigus, and giant cell arteritis.

Plasma interleukin-37 is increased and inhibits the production of inflammatory cytokines in peripheral blood mononuclear cells in systemic juvenile idiopathic arthritis patients

Background

Interleukin (IL)-37 has emerged as a novel anti-inflammatory cytokine that play an immunosuppressive role in regulating inflammatory response. This study aimed to measure IL-37 levels in the plasma and peripheral blood mononuclear cells (PBMCs) of patients with systemic juvenile idiopathic arthritis (sJIA), and to establish the correlation between IL-37 levels and disease activity, laboratory parameters and inflammatory cytokines.

Methods

The mRNA levels of IL-37 in PBMCs and plasma IL-37 concentrations in 46 sJIA patients and 30 age- and sex-matched healthy controls were measured by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The correlations between plasma IL-37 levels and disease activity, laboratory parameters and inflammatory cytokines in sJIA were analyzed by Spearman correlation test. PBMCs from the sJIA patients were stimulated with recombinant human IL-37 (rhIL-37) protein, expressions of IL-1β, IL-6, TNF-α and IL-17 were detected by RT-PCR and ELISA.

Results

Plasma levels of IL-37 and relative IL-37 mRNA expression were significantly elevated in sJIA patients, especially in active sJIA patients, when compared with the healthy controls (P < 0.001). Furthermore, patients with active disease showed higher IL-37 mRNAs and plasma protein levels than those with inactive disease as well as healthy controls. Plasma IL-37 levels were correlated with disease activity and inflammatory cytokines (IL-6, TNF-α, IL-17 and GM-CSF) in sJIA patients. The productions of inflammatory cytokines such as IL-6, TNF-α, IL-17 in PBMCs from sJIA patients were obviously decreased after recombinant IL-37 stimulation, whereas the production of IL-1β was not changed.

Conclusions

Our results demonstrate that levels of IL-37 were higher in sJIA patients, which were correlated with disease activity and sJIA related inflammatory cytokines. In addition, rhIL-37 down-regulates the expressions of inflammatory cytokines form PBMCs in sJIA patients, suggesting that IL-37 may have the potential role as a natural inhibitor for the pathogenesis and therapy of sJIA.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1655-8) contains supplementary material, which is available to authorized users.

Interleukin-6 as a "metabolic hormone"

Interleukin 6 (IL-6) is a cytokine that is involved in divers immune responses and implicated in a number of diseases. However, this cytokine has other non-immune functions. Within this review, we highlight selected effects on metabolic pathways, which are mediated, controlled or modified by the IL-6. Importantly, putting spotlight on such concepts could allow us to classify IL-6 among the metabolic hormones and further study it to both deepen our knowledge on disorders involving metabolic or energy imbalances such as obesity and develop novel therapeutic strategies. Furthermore, potential explanations related to IL-6 roles in both physiology and pathology as well as relevant implications and applications on both research and therapeutic fields are also pointed as consequences of the involvement of IL-6 in the energy and metabolic homeostasis via its "endocrine" roles.

Cytokine Biomarkers of Disease Activity and Therapeutic Response after Initiating Methotrexate Therapy in Patients with Juvenile Idiopathic Arthritis

STUDY OBJECTIVE

To evaluate the relationship between plasma cytokine levels with disease activity and therapeutic response in patients with juvenile idiopathic arthritis (JIA) after initiating methotrexate (MTX) therapy.

DESIGN

Single-center observational prospective cohort study.

SETTING

Outpatient pediatric rheumatology clinic at a tertiary care academic pediatric hospital.

PATIENTS

The study included 61 patients diagnosed with JIA who started therapy with standard-dose MTX 15 mg/m² /week. At 3 months, treating physicians were given the option of maintaining the MTX dose, increasing the MTX dose, or adding etanercept (ETN), based on their clinical judgment.

MEASUREMENTS AND MAIN RESULTS

Patients were evaluated at baseline, 3 months (51 patients), and 6 months (35 patients). Plasma samples from each visit were analyzed for interleukin (IL)-1α, IL-1β, IL-1Ra, IL-6, and tumor necrosis factor-α (TNF-α). Cytokine concentrations were evaluated for relationships with disease activity using the 71-joint count Juvenile Arthritis Disease Activity Score (JADAS). Therapeutic response was assessed by changes in JADAS. Failure to respond to standard-dose MTX was defined as the need for the addition of ETN or a MTX dose increase at or before the 3-month visit. Increased disease severity at baseline was associated with increased IL-6 (p=0.01) and TNF-α (p=0.008) levels. Initiation of MTX was associated with reductions in IL-1α (p=0.009), IL-1β (p=0.01), IL-1Ra (p=0.007), and IL-6 (p=0.03) levels; however, reductions in JADAS were only associated with reductions in IL-6 (p=0.009) and TNF-α levels (p=0.02). Compared with responders, patients failing to respond to standard-dose MTX had increased TNF-α levels at baseline (p=0.02) and at 3 months (p=0.005). Reductions in JADAS by 6 months were observed following either the addition of ETN (p=0.009) or an increase in MTX dose (p=0.007), but the addition of ETN was associated with a median 7-fold increase in TNF-α levels (p=0.003) that corresponded with clinical response.

CONCLUSION

Plasma cytokine levels were responsive to MTX therapy in patients with JIA, but only TNF-α and IL-6 levels were consistently associated with disease activity and therapeutic response. Increased TNF-α levels at baseline were associated with failure to respond to standard-dose MTX and the need for more aggressive drug therapy. Initiation of ETN resulted in increased TNF-α levels that corresponded with therapeutic response, suggesting a potential clinical benefit of monitoring TNF-α levels as a pharmacodynamic marker of etanercept activity.