Evaluation of 5-methylcytosine and 5-hydroxymethylcytosine levels in juvenile idiopathic arthritis and its types

Abstract

Objective: Juvenile idiopathic arthritis is the most common chronic rheumatic disease of autoimmune origin in childhood. While altered DNA methylation has been associated with adult autoimmune rheumatic diseases, studies on juvenile idiopathic arthritis remain limited. This study evaluated levels of 5-methylcytosine and 5-hydroxymethylcytosine, important epigenetic biomarkers, in juvenile idiopathic arthritis and its subtypes.

Methods: This single-center cross-sectional study included patients diagnosed with juvenile idiopathic arthritis aged 1 month to 18 years. Children with systemic or autoimmune diseases and comorbidities were excluded. The study comprised 58 juvenile idiopathic arthritis patients and 35 age-gender-matched healthy controls presenting with non-rheumatological complaints. Demographic and clinical characteristics, including juvenile idiopathic arthritis subtypes, were recorded. The 5-methylcytosine and 5-hydroxymethylcytosine levels were assessed quantitatively using an enzyme-linked immunosorbent assay kit. The relationships between 5-methylcytosine and 5-hydroxymethylcytosine and juvenile idiopathic arthritis and its subtypes were evaluated statistically.

Results: The 5-hydroxymethylcytosine level was significantly higher, whereas the 5-methylcytosine and 5-methylcytosine/5-hydroxymethylcytosine ratios were significantly lower in the patient group than in the control group. No significant differences between different juvenile idiopathic arthritis subtypes and disease activity status were found in 5-hydroxymethylcytosine and 5-methylcytosine levels or 5-methylcytosine/5-hydroxymethylcytosine ratios (p>0.05). The 5-methylcytosine/5-hydroxymethylcytosine ratio, with an optimal cut-off value of ≤28.05, demonstrated a sensitivity of 70.69% and a specificity of 77.14% in distinguishing juvenile idiopathic arthritis patients from controls (p<0.001).

Conclusion: 5-Hydroxymethylcytosine and 5-methylcytosine can be potential biomarkers for juvenile idiopathic arthritis and its subtypes, indicating their roles in juvenile idiopathic arthritis development regarding molecular mechanisms and novel therapeutic approaches.

Figure 1

Comparison of DNA methylation and hydroxymethylation levels between juvenile idiopathic arthritis patients and healthy controls. Box plots showing (A) 5-hydroxymethylcytosine levels, (B) 5-methylcytosine levels, and (C) 5-methylcytosine/5-hydroxymethylcytosine ratios in juvenile idiopathic arthritis patients (n=58) versus healthy controls (n=35). Juvenile idiopathic arthritis patients demonstrated significantly higher 5-hydroxymethylcytosine levels (p<0.001), significantly lower 5-methylcytosine levels (p=0.038), and significantly lower 5-methylcytosine/5-hydroxymethylcytosine ratios (p<0.001) compared to controls. Box plots display median values with interquartile ranges; individual data points represent outliers. Statistical significance was determined using independent samples median test.