SAP15 is a cell penetrating peptide corresponding to the last 15 amino acids of the host defense peptide human beta-defensin 3, which is involved in adaptive immunity and pro- and anti-inflammatory responses. SAP15 is a histone deacetylase 5 (HDAC5) inhibitor with a dissociation constant of 86 nM in an SPR assay and inhibits lipopolysaccharide (LPS) induced phosphorylation of intracellular HDAC5 and NF- kappa B p65 in murine macrophages. In vivo, subcutaneous injection of SAP15-loaded sodium hyaluronic acid solution significantly decreases hind paw swelling, joint inflammation, and serum cytokine levels in a collagen induced arthritis (CIA) rat model.
