Structure-Dependent Effects of Bisphosphonates on Inflammatory Responses in Cultured Neonatal Mouse Calvaria

Keiko Suzuki; Sadaaki Takeyama; Shinobu Murakami; Masahiro Nagaoka; Mirei Chiba; Kaoru Igarashi; Hisashi Shinoda

doi:10.3390/antiox9060503

Structure-Dependent Effects of Bisphosphonates on Inflammatory Responses in Cultured Neonatal Mouse Calvaria

Antioxidants (Basel). 2020 Jun 9;9(6):503. doi: 10.3390/antiox9060503.

Authors

Keiko Suzuki¹, Sadaaki Takeyama², Shinobu Murakami³, Masahiro Nagaoka⁴, Mirei Chiba⁵, Kaoru Igarashi⁶, Hisashi Shinoda³

Affiliations

¹ Department of Dental Pharmacology, School of Dentistry, Showa University, Tokyo 142-8555, Japan.
² Department of Molecular Cell Pharmacology, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan.
³ Center for Environmental Dentistry, Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan.
⁴ Department of Dental Pharmacology, School of Dentistry, Ohu University, Fukushima 963-8611, Japan.
⁵ Division of Oral Physiology, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
⁶ Division of Craniofacial Anomalies, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.

Abstract

Bisphosphonates (BPs) are classified into two groups, according to their side chain structures, as nitrogen-containing BPs (NBPs) and non-nitrogen-containing BPs (non-NBPs). In this study, we examined the effects of NBPs and non-NBPs on inflammatory responses, by quantifying the inflammatory mediators, prostaglandin E₂ (PGE₂) and nitric oxide (NO), in cultured neonatal mouse calvaria. All examined NBPs (pamidronate, alendronate, incadronate, risedronate, zoledronate) stimulated lipopolysaccharide (LPS)-induced PGE₂ and NO production by upregulating COX-2 and iNOS mRNA expression, whereas non-NBPs (etidronate, clodronate, tiludronate) suppressed PGE₂ and NO production, by downregulating gene expression. Additionally, [4-(methylthio) phenylthio] methane bisphosphonate (MPMBP), a novel non-NBP with an antioxidant methylthio phenylthio group in its side chain, exhibited the most potent anti-inflammatory activity among non-NBPs. Furthermore, results of immunohistochemistry showed that the nuclear translocation of NF-κB/p65 and tyrosine nitration of cytoplasmic protein were stimulated by zoledronate, while MPMBP inhibited these phenomena, by acting as a superoxide anion (O₂^-) scavenger. These findings indicate that MPMBP can act as an efficacious agent that causes fewer adverse effects in patients with inflammatory bone diseases, including periodontitis and rheumatoid arthritis.

Keywords: NF-κB; NO; PGE2; anti-inflammatory; antioxidant; bisphosphonate; bisphosphonate-related osteonecrosis of the jaw (BRONJ); nitrotyrosine; periodontitis; peroxynitrite.