PO25 - Plasma Nuclear Cell-Free Nuclear DNA as a Biomarker in Sarcoidosis: A Multicenter Pilot Study
Sarbjot Grewal (United States)1; Mary Richert (United States)2; Samantha Shaffer (United States)3; Hyesik Kong (United States)4; Temesgen Andargie (United States)4; Moon J Jang (United States)5; Ed Chen (United States)6; Michelle Sharp (United States)6; Steven Holland (United States)3; Shambu Aryal (United States)7; Nabeel Hamzeh (United States)8; Sean Agbor-Enoh (United States)4;
1 - Critical Care Medicine, National Institutes of Health, Bethesda, MD; 2 - National Jewish Health; 3 - National Institute of Allergy and Infectious Diseases; 4 - National Heart, Lung, and Blood Institute, Bethesda, MD; 5 - National Heart, Lung, and Blood Institute, Bethesda, MD, USA; 6 - Johns Hopkins Hospital; 7 - Inova Fairfax Hospital; 8 - University of Iowa;
Keywords: Sarcoidosis; cell free DNA; biomarker;
Select the theme: Challenges in Sarcoidosis Diagnosis and Staging
Type: Original Papers
Presentation: Poster Presentation

Introduction: Sarcoidosis shows variable organ involvement, with pulmonary sarcoidosis being the most common form. Identification of organ involvement and risk stratification for disease progression remain important clinical challenges. We hypothesized that plasma cell-free nuclear DNA (ncfDNA) will reliably distinguish individuals with sarcoidosis compared to healthy controls and higher ncfDNA levels correlates with severity of lung disease in sarcoidosis.

Objectives: To evaluate whether ncfDNA and tissue-specific ncfDNA profiles can distinguish sarcoidosis from healthy controls, and assess utility as non-invasive biomarkers.

Materials and Methods: The multicenter study recruited individuals with sarcoidosis from four academic centers in addition to healthy controls. FVC was used to measure pulmonary disease burden. Plasma samples collected at enrollment were used to isolate and quantify ncfDNA by digital droplet PCR. Whole-genome bisulfite sequencing was used to perform methylation analyses to isolate tissue specific cfDNA. ncfDNA distributions were compared using the Wilcoxon rank-sum test and reported as median (interquartile range [IQR]).

Results: 166 individuals with sarcoidosis and 156 healthy controls were analyzed. Individuals with sarcoidosis demonstrated two-fold higher ncfDNA levels than healthy controls [median 5,113 (IQR 3,480–8,346) vs 2,172 (IQR 1,375–2,972) copies/mL; p < 0.001]. ncfDNA negatively correlated with FVC% predicted (r = −0.36, p < 0.001), with higher levels observed in patients with lower FVC% predicted. Methylation analysis revealed distinct ncfDNA tissue sources. Individuals with sarcoidosis showed increased ncfDNA derived from innate immune inflammatory cells such as granulocyte, monocyte, macrophage and megakaryocyte, as well as increased ncfDNA from the following diseased organ compartments, the lung, hepatocyte, and kidney.

Conclusions: Individuals with sarcoidosis showed higher ncfDNA compared to healthy controls and individuals with lower lung function, suggesting greater disease burden were found to have higher ncfDNA levels. The ncfDNA methylation analysis reveal tissue-specific cfDNA profiles. Our findings suggest that ncfDNA may be a useful biomarker of tissue injury in sarcoidosis.