TLR9 and systemic lupus erythematosus: In SLE and RA patients, HCQ affects TLR7 and TLR9 activation and decreases the percentage of DCs as well as their production of IFN-α (Sacre et al., 2012; Alves et al., 2017; Hjorton et al., 2018; Zeidi et al., 2019; Meng et al., 2022), IL-6 (Piconi et al., 2011; Hjorton et al., 2018; Meng et al., 2022) and TNF-α (Sacre et al., 2012; Hjorton et al., 2018; Han et al., 2020).