Natural Compounds for the Treatment of Psoriatic Arthritis: A Proposal Based on Multi-Targeted Osteoclastic Regulation and on a Preclinical Study

12-Deoxyphorbol 13-acetate inhibits RANKL-induced osteoclastogenesis via the attenuation of MAPK signaling and NFATc1 activation

Osteoporosis, characterized by bone loss and microstructure damage, occurs when osteoclast activity outstrips osteoblast activity. Natural compounds with inhibitory effect on osteoclast differentiation and function have been evidenced to protect from osteoporosis. After multiple compounds screening, 12-deoxyphorbol 13-acetate (DPA) was found to decline RANKL-induced osteoclastogenesis dose-dependently by attenuating activities of NFATc1 and c-Fos, followed by decreasing the level of osteoclast function-associated genes and proteins including Acp5, V-ATPase-d2 and CTSK. Mechanistically, we found that DPA suppressing RANKL-induced downstream signaling pathways, including MAPK signaling pathway and calcium oscillations. Furthermore, the in vivo efficacy of DPA was further confirmed in an OVX-induced osteoporosis mice model. Collectively, the results in our presentation reveal that DPA might be a promising compound to manage osteoporosis.

Patchouli Alcohol Modulates the Pregnancy X Receptor/Toll-like Receptor 4/Nuclear Factor Kappa B Axis to Suppress Osteoclastogenesis

The incidence of osteoporosis, which is primarily characterized by plethoric osteoclast (OC) formation and severe bone loss, has increased in recent years. Millions of people worldwide, especially postmenopausal women, suffer from osteoporosis. The drugs commonly used to treat osteoporosis still exist many disadvantages, but natural extracts provide options for the treatment of osteoporosis. Therefore, the identification of cost-effective natural compounds is important. Patchouli alcohol (PA), a natural compound extracted from Pogostemon cablin that exerts anti-inflammatory effects, is used as a treatment for gastroenteritis. However, no research on the use of Patchouli alcohol in osteoporosis has been reported. We found that PA dose-dependently inhibited the receptor activator of nuclear factor kappa-B ligand (RANKL)-induced formation and function of OCs without cytotoxicity. Furthermore, these inhibitory effects were reflected in the significant effect of PA on the NF-κB signaling pathway, as PA suppressed the transcription factors NFATc1 and c-Fos. We also determined that PA activated expression of the nuclear receptor pregnane X receptor (PXR) and promoted the PXR/Toll-like receptor 4 (TLR4) axis to inhibit the nuclear import of NF-κB (p50 and p65). Additionally, PA exerted therapeutic effects against osteoporosis in ovariectomized (OVX) mice, supporting the use of PA as a treatment for osteoporosis in the future.

Natural Compound Mixture, Containing Emodin, Genipin, Chlorogenic Acid, Cimigenoside, and Ginsenoside Rb1, Ameliorates Psoriasis-Like Skin Lesions by Suppressing Inflammation and Proliferation in Keratinocytes

Herbal combinations of Rhei Radix et Rhizoma, Gardeniae Fructus, Cimicifugae Rhizoma, and Ginseng Radix have been used in traditional formulas to treat the symptoms of heat and dryness. This study investigated the therapeutic effects of a natural compound mixture (PSM) of these herbal combinations, containing emodin, genipin, chlorogenic acid, cimigenoside, and ginsenoside Rb1, for the treatment of psoriasis and its underlying molecular mechanisms. PSM was applied topically to the dorsal skin lesions of imiquimod- (IMQ-) induced C57BL/6 mice, and the expression of the proinflammatory mediators was investigated. The topical application of 1% PSM reduced psoriasis-like symptoms in IMQ-induced C57BL/6 mice significantly. PSM also attenuated the production of IFN-γ, IL-1β, and IL-6 in skin lesions. Histological analysis showed that PSM had antipsoriatic effects by reducing the lesional epidermal thickness. Either M5 (IL-1α, IL-17A, IL-22, oncostatin M, and TNF-α, 10 ng/ml each) or IL-22- (100 ng/ml) stimulated HaCaT cells were used to examine the efficacy and underlying mechanism of PSM. In M5-stimulated HaCaT cells, PSM inhibited the production of C-X-C motif chemokine ligand (CXCL) 10 and C-C motif chemokine ligand (CCL) 20 effectively. Moreover, compared to the use of a single compound, it had synergistic inhibitory effects in CXCL8 production. PSM suppressed the phosphorylation of ERK1/2, p38, and STAT3 signaling pathways in M5-stimulated HaCaT cells. Furthermore, PSM reduced the proliferation rate and K16 and K17 expressions in IL-22-stimulated HaCaT cells by inhibiting the Akt/mTOR signaling pathway. These results suggest that PSM may have a therapeutic potential in the treatment of psoriasis lesions.

Tubeimoside I suppresses diabetes-induced bone loss in rats, osteoclast formation, and RANKL-induced nuclear factor-κB pathway

Type 2 diabetes mellitus is often companied with osteoporosis, a process which involves osteoclast activation. In this study, we found tubeimoside I, a natural compound isolated from the Chinese medicinal herb Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), significantly ameliorated the decrease of bone mass in type 2 diabetes-induced osteoporosis in rats. It appears that tubeimoside I exerts this protecting effect through inhibiting osteoclast formation and function. Futhermore, our study showed that tubeimoside I inhibits NF-κB transcriptional activation and degradation of IκBα. Collectively, our results reveal that tubeimoside I attenuates osteoclastogenesis through down-regulating NF-κB signaling pathway, and is a potential candidate for the treatment of bone-destructive diseases like type 2 diabetic osteoporosis.

Astilbin prevents bone loss in ovariectomized mice through the inhibition of RANKL-induced osteoclastogenesis

Osteoporosis is the most common osteolytic disease characterized by excessive osteoclast formation and resultant bone loss, which afflicts millions of patients around the world. Astilbin, a traditional herb, is known to have anti-inflammatory, antioxidant and antihepatic properties, but its role in osteoporosis treatment has not yet been confirmed. In our study, astilbin was found to have an inhibitory effect on the RANKL-induced formation and function of OCs in a dose-dependent manner without cytotoxicity. These effects were attributed to its ability to suppress the activity of two transcription factors (NFATc1 and c-Fos) indispensable for osteoclast formation, followed by inhibition of the expression of bone resorption-related genes and proteins (Acp5/TRAcP, CTSK, V-ATPase-d2 and integrin β3). Furthermore, we examined the underlying mechanisms and found that astilbin repressed osteoclastogenesis by blocking Ca2+ oscillations and the NF-κB and MAPK pathways. In addition, the therapeutic effect of MA on preventing bone loss in vivo was further confirmed in an ovariectomized mouse model. Therefore, considering its ability to inhibit RANKL-mediated osteoclastogenesis and the underlying mechanisms, astilbin might be a potential candidate for treating osteolytic bone diseases.

Cumambrin A prevents OVX-induced osteoporosis via the inhibition of osteoclastogenesis, bone resorption, and RANKL signaling pathways

Being the principal cells responsible for bone resorption and pathologic bone loss, osteoclasts have become the main target for antiresorptive treatment. Cumambrin A is a natural compound isolated from Chrysanthemum indicum L. and belongs to a member of the sesquiterpene lactone family. To date, the therapeutic effect of cumambrin A on osteoporosis and its mechanisms of action are not known. In this study, we found that cumambrin A can significantly inhibit osteoclast formation and bone resorption through the suppression of receptor activator of NF-κB ligand (RANKL)-induced NF-κB and nuclear factor of activated T-cell activity and ERK phosphorylation. Furthermore, cumambrin A inhibits the expression of osteoclast marker genes including cathepsin K, calcitonin receptor, and V-ATPase d2. Using an in vivo ovariectomized mouse model, we showed that cumambrin A protects against estrogen withdrawal-induced bone loss. Collectively, our results reveal that cumambrin A can suppress osteoclast formation, bone resorption, and RANKL-induced signaling pathways, suggesting that cumambrin A is a potential therapeutic agent for the treatment of osteoporosis.-Zhou, L., Liu, Q., Hong, G., Song, F., Zhao, J., Yuan, J., Xu, J., Tan, R. X., Tickner, J., Gu, Q., Xu, J. Cumambrin A prevents OVX-induced osteoporosis via the inhibition of osteoclastogenesis, bone resorption, and RANKL signaling pathways.

Madecassoside inhibits estrogen deficiency-induced osteoporosis by suppressing RANKL-induced osteoclastogenesis

Osteoporosis is the most common osteolytic disease characterized by excessive osteoclast formation and resultant bone loss, which afflicts millions of patients around the world. Madecassoside (MA), isolated from Centella asiatica, was reported to have anti-inflammatory and antioxidant activities, but its role in osteoporosis treatment has not yet been confirmed. In our study, MA was found to have an inhibitory effect on the RANKL-induced formation and function of OCs in a dose-dependent manner without cytotoxicity. These effects were attributed to its ability to suppress the activity of two transcription factors (NFATc1 and c-Fos) indispensable for osteoclast formation, followed by inhibition of the expression of bone resorption-related genes and proteins (Acp5/TRAcP, CTSK, ATP6V0D2/V-ATPase-d2, and integrin β3). Furthermore, we examined the underlying mechanisms and found that MA represses osteoclastogenesis by blocking Ca2+ oscillations and the NF-κB and MAPK pathways. In addition, the therapeutic effect of MA on preventing bone loss in vivo was further confirmed in an ovariectomized mouse model. Therefore, considering its ability to inhibit RANKL-mediated osteoclastogenesis and the underlying mechanisms, MA might be a potential candidate for treating osteolytic bone diseases.

Poria cocos polysaccharide attenuates RANKL-induced osteoclastogenesis by suppressing NFATc1 activity and phosphorylation of ERK and STAT3

Pathological fractures caused by osteolytic lesions seriously threaten the health of patients. Osteoclasts play important roles in bone resorption whose hyperfunction are closely related to osteolytic lesions. Studies on osteoclast differentiation and function assist in the prevention of excessive bone loss associated diseases. We screened a variety of natural compounds with anti-inflammatory effect and found that poria cocos polysaccharide (PCP) inhibited RANKL-induced osteoclast formation and bone resorption via TRAcP staining, immunofluorescence, RT-PCR and western blot. PCP down-regulated phosphorylation of STAT3, P38, ERK and JNK, and thus repressed the expression of NFAcT1 and c-Fos during RANKL-induced osteoclastogenesis. Besides, the expression of bone resorption related genes such as TRAcP and CTSK was suppressed by PCP. The results suggest that PCP can be invoked as a candidate for the treatment of osteolytic diseases by inhibiting osteoclastogenesis.

Achyranthes bidentata polysaccharide suppresses osteoclastogenesis and bone resorption via inhibiting RANKL signaling

Osteoclasts are highly differentiated multinucleated giant cells that play fundamental roles in bone resorption and in the pathogenesis of osteolytic conditions, such as osteoporosis and cancer-induced bone loss. Achyranthes bidentata polysaccharide (ABP) is a hydrophilic compound with anti-oxidation and anti-aging characteristics. The impact of ABP on RANKL-induced osteoclast formation and bone resorption has not been assessed, hence, in this study we investigated the effect of ABP on osteoclast formation and resorption in murine bone marrow derived osteoclasts. We found that ABP was able to suppress RANKL-induced osteoclast differentiation and bone resorption activity at concentrations above 6.5 µM, while demonstrating no cytotoxicity at concentrations up to 10 µM. The actions of ABP were mediated through inhibition of RANKL-induced c-Fos and NFATc1 gene and protein expression. Furthermore, we found that ABP suppressed NFATc1 transcriptional activity, and the phosphorylation of MAPK pathways induced by RANKL. Collectively, ABP attenuates RANKL-mediated osteoclast activity and signaling, and might serve as a potential therapeutic candidate for preventing bone loss related diseases.