Effect of cathelicidin-related antimicrobial peptide (CRAMP) on osteoclast formation induced by receptor activator of nuclear factor-κB ligand (RANKL). (a) Effects of CRAMP on osteoclast formation induced by 1α,25(OH)2D3 and prostaglandin E2 (PGE2) in co-cultures. Osteoblasts and bone marrow (BM) cells were co-cultured with or without 1α,25(OH)2D3 (10−8
m) and PGE2 (10−6
m). CRAMP (30 μg/ml) was added to some co-cultures. After 7 days, the number of tartrate-resistant acid phosphatase-positive [TRAP(+)] multinucleated cells was counted. (b) Effects of CRAMP on osteoclast formation induced by RANKL in BM macrophage (BMM) cultures. BMMs were cultured with macrophage colony-stimulating factor (M-CSF; 104 U/ml) or M-CSF plus RANKL (200 ng/ml). CRAMP (30 μg/ml) was added to some BMM cultures. After 6 days, cells were fixed and stained for TRAP (right). The number of TRAP(+) multinucleated cells was counted (left). Data are expressed as the mean ± SD (n = 4). Bar, 100 μm.