PTGS2 and osteonecrosis: Furthermore, another study also indicated that oral administration of Ok-PDRN inhibited the expression of IL-1β, matrix metalloproteinase (MMP)-3, and MMP-7, as well as production of inflammatory mediators including COX-2, prostaglandin E2 (PGE2), and TNF-α in an MIA-induced osteonecrosis model [21].