Bioactive Plasma Mitochondrial DNA Is Associated With Disease Progression in Scleroderma-Associated Interstitial Lung Disease.

Objective: Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is characterized by variable clinical outcomes, activation of innate immune pattern-recognition receptors (PRRs), and accumulation of α-smooth muscle actin (α-SMA)-expressing myofibroblasts. The aim of this study was to identify an association between these entities and mitochondrial DNA (mtDNA), an endogenous ligand for the intracellular DNA-sensing PRRs Toll-like receptor 9 (TLR-9) and cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING), which has yet to be determined.

Methods: Human lung fibroblasts (HLFs) from normal donors and SSc-ILD explants were treated with synthetic CpG DNA and assayed for α-SMA expression and extracellular mtDNA using quantitative polymerase chain reaction for the human MT-ATP6 gene.