Inhibitory effects of astaxanthin on cml‐hsa‐induced inflammatory and rankl‐induced osteoclastogenic gene expression in raw 264.7 cells

Abstract

Objective: Elevated levels of serum Nε‐carboxymethyllysine (CML), a well‐known advanced glycation end‐product (AGE), were observed in patients with inflammation or osteoporo-sis. Astaxanthin was reported to possess anti‐inflammatory and antioxidant effects. In the present study, we investigated the effects of commercially available dietary supplement AstaReal ACTR (ASR) capsule content as astaxanthin on CML‐HSA‐induced inflammatory and receptor activator of nuclear factor‐kappa‐Β ligand (RANKL)‐induced osteoclastogenic gene expression. Methods: RAW 264.7 murine macrophage cells were stimulated with CML‐HSA to trigger inflammatory gene expression and treated with either a vehicle control or varied concentrations of astaxanthin. Inflammatory gene expression was measured using an enzyme‐linked immunosorbent assay (ELISA) or qPCR. We triggered osteoclastogenesis using RANKL, and osteoclastogenic gene expression was measured through tartrate‐resistant acid phosphatase (TRAP) activity, staining, immunofluorescence, and qPCR analyses. Results: CML‐HSA showed a stimulatory effect on inflammatory gene expression, and astaxanthin reduced the expression by at least two‐fold. The levels of autoinflammatory gene expression were reduced by astaxanthin. The RANKL‐induced osteoclastogenesis was significantly inhibited by astaxanthin, with reductions in the activation of nuclear factor‐κB (NF‐κB), the expression of NFATc1 (nuclear factor of activated T cells 1), multi-nucleated cell formation, and the expression of mature osteoclast marker genes. Conclusion: Astaxanthin has potential as a remedy for CML‐HSA‐induced inflammation and RANKL‐induced excessive bone loss.