The KKS [comprised of kallikreins (Klks), bradykinins (BKs)] and angiotensin-converting enzyme inhibitors (ACEi), which bridge the KKS–renin–angiotensin (RAS) pathway, suppressed the Type I IFN responses in murine dendritic cells (DCs) from normal and lupus-prone mice and in human peripheral blood mononuclear cells [12]. Here, KLK4 is linked to systemic lupus erythematosus.