Cell Free DNA in SLE Patients: A Possible Marker of Disease Activity and Organ Damage

Abstract Background Systemic lupus erythematous (SLE) is a prototypic autoimmune disease with a complex pathogenesis involving multiple genetic and environmental factors. Cell death has been regarded as an important event in lupus pathogenesis as it leads to release of antigens as nucleic acids for immune complex formation. DNA-antibody complex in the circulation are one of the hallmarks of SLE that leads to detrimental effects causing manifestations of SLE. Fluctuation in circulating DNA level might be one of the driving factors behind flare-ups of SLE. Objectives This study aims to measure the circulating cell free DNA (cf-DNA) in patients with SLE as a potential marker for disease activity and organ damage. Methods This case control study included 100 participants categorized into 75 SLE patients as patient group (Group I), further divided to 39 SLE patients without therapy (group Ia), 36 SLE patients with therapy (Group Ib) and 25 age and sex matched healthy subjects as a control group (Group II). All participants were subjected to full history taking, thorough rheumatological examination and lab assessment of complete blood count (CBC), ESR, CRP, C3, C4 levels, ANA titer, anti-ds-DNA concentration by ELIZA and measurement of plasma cf-DNA levels by real time PCR. Cf- DNA concentration is expressed as concentration (ng/ml). Results SLE patients (Group Ia and Ib) showed significant increase in (plasma cf-DNA,CRP, ESR, ANA, anti-ds-DNA), significant decrease in (C3 and C4, hemoglobin, total leucocytic count and platelet count). Plasma cf-DNA (ng/ml) was significantly lower in group Ib compared to group Ia. There was significant positive correlation between plasma cf-DNA (ng/ml) and levels of ANA and anti-ds-DNA in all SLE patients and with SLEDAI-2k score in all patients. Conclusion Plasma level of cf-DNA is significantly increased in SLE patients especially before starting therapy these data may suggest it to be a possible marker of treatment follow up. Further studies on a larger patient population are still needed to confirm these results.