Involved in redox regulation of the cell. Acts as an antioxidant. Inhibits TNFSF11-induced NFKB1 and JUN activation and osteoclast differentiation. May affect bone resorption and help to maintain bone mass. Acts as a negative regulator of macrophage-mediated inflammation by inhibiting macrophage production of inflammatory cytokines, probably through suppression of the MAPK signaling pathway. Secreted from mature adipocytes but not from preadipocytes. The active site cysteines correspond to the redox-active cysteines of peroxiredoxins. Belongs to the peroxiredoxin-like PRXL2 family. PRXL2A subfamily.