TGFB1 and systemic lupus erythematosus: hCDR1 is a tolerogenic peptide derived from the sequence of the first complementarity-determining region (CDR1) of anti-DNA immunoglobulin (Ig) G, and it can downregulate pathogenic cytokines, such as tumor necrosis factor (TNF)-α, IL-1β, and IFN-γ, and upregulate the immunosuppressive cytokine TGF-β in lupus-prone mice (25).