Modulation of osteoclastogenesis in porcine bone marrow cultures by quercetin and rutin

Abstract

Flavonols, in contrast to soybean isoflavones, are the most abundant phytoestrogens in western diets, being present in onions, beans, fruits, red wine, and tea. They may protect against atherosclerosis, inhibit certain cancer cell types, and reduce bone resorption. The most widely distributed flavonol is quercetin, which occurs mainly as its glycoside, rutin, but data are very scarce regarding the precise mechanism of action of these compounds on bone-resorbing cells at concentrations similar to those detected in human plasma. We have therefore investigated the effects of nanomolar concentrations of quercetin and rutin on the development and activity of osteoclasts in vitro compared with the effects of 17beta-estradiol. Nonadherent porcine bone marrow cells were cultured on dentine slices in the presence of 10 nM 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), with or without 10 nM quercetin, 10 nM rutin or 10 nM 17beta-estradiol for 11 days. Multinuclear TRAP+ cells that resorbed dentine (osteoclasts) developed in the presence of 1,25(OH)2D3, but their number was significantly reduced by quercetin, rutin, and 17beta-estradiol (P < 0.05). Like 17beta-estradiol, both flavonols also significantly reduced resorption (P<0.05) as assessed by the size of pits resorbed on dentine slices. Osteoclasts and osteoclast progenitors contained estrogen receptor alpha (ERalpha), ERbeta, and RANK proteins. Both flavonols increased nuclear ERbeta protein and decreased ERalpha protein of osteoclast progenitors. Moreover, rutin reduced RANK protein, whereas 17beta-oestradiol and quercetin promoted apoptosis by cleavage of caspase-8 and caspase-3. All the effects of flavonols were reversed by 1 microM ICI 182,780, an estrogen antagonist. Thus, the anti-resorbing properties of flavonols are mainly mediated by ER proteins through the inhibition of RANK protein or the activation of caspases.

Rutin inhibits osteoclast formation by decreasing reactive oxygen species and TNF-α by inhibiting activation of NF-κB

“…Rutin did not show cytotoxicity to either bone marrow cells or BMM under these conditions (Data not shown). Rassi et al (2005) showed that nanomolar concentration of rutin reduced 1,25-dihydroxyvitamin D3-induced bone resorption in porcine bone marrow cells. Rutin could be more sensitive in inhibiting bone resorption activity than in inhibiting osteoclast formation, although we did not measure the effect of rutin on functional activity of osteoclast.…”

Moderate alcohol consumption and increased bone mineral density: potential ethanol and non-ethanol mechanisms

“…7 macrophages treated with receptor activator of NF-kB (RANK) ligand, as well as human peripheral blood mononuclear cells differentiated with macrophage colony-stimulating factor and RANK ligand Woo et al 2004). Moreover, Rassi et al (2005) have recently demonstrated in a porcine bone-marrow model that even low nanomolar concentrations of quercetin or rutin significantly inhibit osteoclast formation and activity similar to 17b oestradiol. Kaempferol (1-6 mM), another flavonol found in alcoholic beverages, also induces apoptosis and inhibits bone resorption activity in primary rabbit osteoclasts even at concentrates of less than 1 mm (Wattel et al 2003).…”

“…These in vivo effects suggest that either rutin, or its active metabolites quercetin and isorhamnetin, may exert modulatory effects on bone cells. Indeed, results from in vitro studies (Wattel et al 2003Woo et al 2004; Rassi et al 2005) suggest that both rutin and quercetin may directly affect bone cells, particularly osteoclasts. Quercetin has been reported to induce apoptosis in primary rabbit or porcine osteoclasts (Wattel et al 2003;Rassi et al 2005).…”

“…Indeed, results from in vitro studies (Wattel et al 2003Woo et al 2004; Rassi et al 2005) suggest that both rutin and quercetin may directly affect bone cells, particularly osteoclasts. Quercetin has been reported to induce apoptosis in primary rabbit or porcine osteoclasts (Wattel et al 2003;Rassi et al 2005). In addition, quercetin (1-10 mM) decreases both osteoclast formation and activity in murine primary macrophage colony-stimulating factor-dependent osteoclast progenitors and in RAW 264 .…”

Bone mineral density, polyphenols and caffeine: a reassessment

“…3) have also been shown to modulate the activity of bone cells in vitro and in vivo. During an 11 d incubation, both rutin and quercetin (10 nM) significantly inhibited the formation of osteoclasts in porcine bone marrow cells treated with 1,25-dihydroxyvitamin D 3 (10 nM) 33 . In the same study, a 48 h treatment of 11 d old osteoclast cells with rutin or quercetin (10 nM) was also shown to significantly reduce bone resorption.…”