FMO5 and systemic lupus erythematosus: In addition, LPS stimulates and increases the expression of toll-like receptor (TLR)4 in the vasculature, which resulted in increased NADPH oxidase activity.52 In correlation with plasma LPS levels, mRNA levels of TLR4 were higher in SLE compared to CTR group, which were significantly reduced by RS treatment (Figure 5d).