CGAS and rheumatoid arthritis: Tumor necrosis factor (TNF) is a core inflammatory factor in RA, which inhibits phosphatase and tensin homologue-induced kinase 1 (PINK1)-mediated mitophagy and elicits mitochondrial damage, which increases cytoplasmic mtDNA levels and activates cGAS-STING, boosting inflammation in RA (105) (Figure 2).