Mixed Connective Tissue Disease as Different Entity: Global Methylation Aspect

Area of Science:

• Epigenetics
• Immunology
• Rare Diseases

Background:

• Mixed Connective Tissue Disease (MCTD) is a rare autoimmune disorder with unclear pathogenesis.
• DNA methylation is a key epigenetic regulator of gene expression, increasingly implicated in autoimmune connective tissue diseases (ACTDs).
• Previous research suggests a potential role for DNA methylation alterations in the development of ACTDs like Systemic Sclerosis (SSc) and Systemic Lupus Erythematosus (SLE).

Purpose of the Study:

• To investigate global DNA methylation differences between patients with MCTD and other ACTDs (SSc, SLE) in whole blood samples.
• To explore the potential of global DNA methylation as a distinguishing biomarker for MCTD.

Main Methods:

• Study included 54 MCTD patients, 43 SSc patients, 45 SLE patients, and 43 healthy controls (HC).
• Global DNA methylation levels were quantified using Enzyme-Linked Immunosorbent Assay (ELISA).
• Statistical analyses were performed to compare methylation levels between groups and within SSc subtypes.

Main Results:

• Global DNA methylation was not significantly different between MCTD patients and healthy controls (p=0.09).
• Hypomethylation was observed in MCTD patients compared to SSc (p≤0.001) and SLE (p<0.001) patients.
• Significant differences in global methylation were found between SLE and MCTD (p<0.001), SLE and HC (p=0.008), SSc and MCTD (p≤0.001), and SSc and HC (p<0.001).
• Patients with limited SSc exhibited higher global methylation levels than those with diffuse SSc (p=0.01).

Conclusions:

• Global DNA hypomethylation can distinguish MCTD from SSc and SLE.
• Global DNA methylation levels may not serve as a definitive diagnostic marker for differentiating MCTD from other ACTDs.
• Further research is warranted to elucidate the specific role of DNA methylation in MCTD pathogenesis and its potential as a distinguishing factor.