6,4'-Dihydroxy-7-methoxyflavanone inhibits osteoclast differentiation and function

Flavonoids from Dalbergia cochinchinensis: Impact on osteoclastogenesis

Background/purpose

Dalbergia cochinchinensi has been widely used in traditional medicine because of its flavonoids. This study examined which components in D. cochinchinensis were capable of reducing or even stimulating the formation of bone-resorbing osteoclasts.

Materials and methods

We have isolated subfamilies of chalcones (isoliquiritigenin, butein), flavones (7-hydroxy-6-methoxyflavone) and neoflavanoids (5-methoxylatifolin), and performed an in vitro bioassay on osteoclastogenesis. The flavonoids were tested for their potential to change the expression of tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK) in murine bone marrow cultures being exposed to RANKL, M-CSF and TGF-β1 using RT-PCR, histochemistry and immunoassay.

Results

We could confirm that isoliquiritigenin and butein significantly lower the expression of TRAP and CTSK in this setting. Moreover, histochemistry supported the decrease of TRAP by the chalcones. We further observed a trend towards an increase of osteoclastogenesis in the presence of 5-methoxylatifolin and 7-hydroxy-6-methoxyflavone, particular in bone marrow cultures being exposed to RANKL and M-CSF. Consistently, the anti-inflammatory activity was restricted to isoliquiritigenin and butein in murine RAW 264.7 inflammatory macrophages stimulated by lipopolysaccharide (LPS). With respect to osteoblastogenesis, neither of the flavonoids but butyrate, a short chain fatty acid, increased the osteogenic differentiation marker alkaline phosphatase activity in ST2 murine mesenchymal cells.

Conclusion

We have identified two flavonoids from D. cochinchinensis with a potential pro-osteoclastogenic activity and confirm the anti-osteoclastogenic activity of isoliquiritigenin and butein.

Glycolysis in Innate Immune Cells Contributes to Autoimmunity

Autoimmune diseases (AIDs) refer to connective tissue inflammation caused by aberrant autoantibodies resulting from dysfunctional immune surveillance. Most of the current treatments for AIDs use non-selective immunosuppressive agents. Although these therapies successfully control the disease process, patients experience significant side effects, particularly an increased risk of infection. There is a great need to study the pathogenesis of AIDs to facilitate the development of selective inhibitors for inflammatory signaling to overcome the limitations of traditional therapies. Immune cells alter their predominant metabolic profile from mitochondrial respiration to glycolysis in AIDs. This metabolic reprogramming, known to occur in adaptive immune cells, i.e., B and T lymphocytes, is critical to the pathogenesis of connective tissue inflammation. At the cellular level, this metabolic switch involves multiple signaling molecules, including serine–threonine protein kinase, mammalian target of rapamycin, and phosphoinositide 3-kinase. Although glycolysis is less efficient than mitochondrial respiration in terms of ATP production, immune cells can promote disease progression by enhancing glycolysis to satisfy cellular functions. Recent studies have shown that active glycolytic metabolism may also account for the cellular physiology of innate immune cells in AIDs. However, the mechanism by which glycolysis affects innate immunity and participates in the pathogenesis of AIDs remains to be elucidated. Therefore, we reviewed the molecular mechanisms, including key enzymes, signaling pathways, and inflammatory factors, that could explain the relationship between glycolysis and the pro-inflammatory phenotype of innate immune cells such as neutrophils, macrophages, and dendritic cells. Additionally, we summarize the impact of glycolysis on the pathophysiological processes of AIDs, including systemic lupus erythematosus, rheumatoid arthritis, vasculitis, and ankylosing spondylitis, and discuss potential therapeutic targets. The discovery that immune cell metabolism characterized by glycolysis may regulate inflammation broadens the avenues for treating AIDs by modulating immune cell metabolism.

Heartwood of Dalbergia cochinchinensis: 4,7,2'-Trihydroxy-4'-methoxyisoflavanol and 6,4'-Dihydroxy-7-methoxyflavane Reduce Cytokine and Chemokine Expression In Vitro

Dalbergia cochinchinensis has been widely used in traditional medicine because of its flavonoids; however, the impact of the flavonoids to modulate the inflammatory response to oral cells remains to be described. For this aim, we isolated 4,7,2'-trihydroxy-4'-methoxyisoflavanol (472T4MIF) and 6,4'-dihydroxy-7-methoxyflavane (64D7MF) from the heartwood of D. cochinchinensis and confirmed the chemical structure by nuclear magnetic resonance. We show here that both flavonoids are inhibitors of an inflammatory response of murine RAW 264.7 inflammatory macrophages stimulated by LPS. This is indicated by interleukin (IL)1, IL6, and chemokine CCL2 production besides the phosphorylation of p65. Consistently, in primary murine macrophages, both flavonoids decreased the inflammatory response by lowering LPS-induced IL1 and IL6 expression. To introduce oral cells, we have used human gingival fibroblasts and provoked the inflammatory response by exposing them to IL1β and TNFα. Under these conditions, 472T4MIF, but not 64D7MF, reduced the expression of chemokines CXCL1 and CXCL2. Taken together, we identified two flavonoids that can reduce the expression of cytokines and chemokines in macrophages and fibroblastic cells.

6,4'-dihydroxy-7-methoxyflavanone protects against H2O2-induced cellular senescence by inducing SIRT1 and inhibiting phosphatidylinositol 3-kinase/Akt pathway activation

6, 4'-Dihydroxy-7-methoxyflavanone (DMF) has been shown to possess anti-inflammatory, anti-oxidative, and neuroprotective activities. However, its effect on oxidative stress-induced aging remains undemonstrated. This study aimed at investigating the anti-senescence effect of DMF on hydrogen peroxide (H₂O₂)-induced premature senescence, and associated molecular mechanisms in human dermal fibroblasts (HDFs). The cells were DMF pretreated with small interfering RNA (siRNAs) of control or sirtuin 1 (SIRT1) before H₂O₂ exposure, and western blot analysis, senescence-associated β-galactosidase (SA-β-gal) activity, cell counting, gene silencing, and SIRT1 activity assay were performed. Pretreatment with DMF inhibited H₂O₂-induced senescence phenotypes, which showed decreased SA-β-gal activity and increased cell growth in comparison with H₂O₂-treated HDFs. Meanwhile, the decreases in ac-p53, p21^Cip1/WAF1, and p16^Ink4a and the increases in pRb and cyclin D1 were observed. DMF was also found to induce SIRT1 expression and activity level concentration- and time-dependently. Moreover, SIRT1 inhibition abrogated DMF senescence prevention. Additionally, Akt and ERK were activated with different kinetics after H₂O₂ exposure, and Akt activity inhibition attenuated SA-β-gal activity augmentation. We also found that DMF inhibited H₂O₂-induced Akt phosphorylation. This study indicates that DMF effectively protects against oxidative stress-induced premature senescence through SIRT1 expression up-regulation and Akt pathway inhibition in HDFs. These results suggest that DMF can be a potential therapeutic molecule for age-related diseases, or a protective agent against the aging process.

Inhibitory effect of Cudratricusxanthone A on osteoclast differentiation and function

BACKGROUND

Cudratricusxanthone A (CTXA) was isolated from Cudrania tricuspidata and its anti-inflammatory, hepatoprotective, and anti-proliferative activities have previously been studied in vitro. However, effects of CTXA on osteoclast differentiation have not been investigated.

PURPOSE

In this study, the effect of CTXA from C. tricuspidata on in vitro osteoclastogenesis was studied.

DESIGN/METHODS

CTXA was isolated from the roots of C. tricuspidata. The effects of CTXA on the RANKL-induced osteoclastogenesis, actin ring formation, and bone resorption were tested by using the RAW 264.7 cells and mouse bone marrow monocytes (BMMs).

RESULTS

The structure of CTXA was identified by comparison with spectral data in the literature. We also checked the effect of CTXA on in vitro osteoclastogenesis. CTXA significantly inhibited the JNK/MAPK signaling pathway without affecting ERK and p38 signaling in RANKL-stimulated RAW 264.7 cells and BMMs. Moreover, it inhibited RANKL-induced expression of c-Fos and NFATc1.

CONCLUSION

In conclusion, CTXA suppresses osteoclast differentiation by inhibiting RANKL-induced MAPK signaling and attenuates bone resorption by disrupting actin ring formation in mature osteoclasts. These results suggest that CTXA inhibits bone resorption through an inhibitory effect on osteoclast formation and function.

BJ-1103, 6-aminopyridin-3-ol skeletal compound, modulates neuroprotective and anti-neuroinflammatory effects in murine hippocampal and microglial cells via Nrf2-mediated heme oxygenase-1 expression

BJ-1103, as a 6-aminopyridin-3-ol skeletal compound, was originally developed as an antioxidant against free radicals and oxidative stress was prepared from pyridoxine·HCl by the reported procedure. In the present study, we examined the effect of BJ-1103 on neuroprotection and neuroinflammation. Our data showed that BJ-1103 can protect HT22 cells against glutamate-induced cell cytotoxicity. And, BJ-1103 also inhibited LPS-induced inflammatory action. In addition, BJ-1103-induced heme oxygenase-1 (HO-1) expression and elevated HO-1 activities in the two cell lines studied. Additionally, BJ-1103 treatment induced nuclear transcription factor erythroid-2 related factor 2 (Nrf2) and increased the promoter activity of antioxidant response elements (AREs). We have demonstrated using the Nrf2 siRNA, HO inhibitor or HO-1 siRNA that BJ-1103 suppressed neurotoxicity and neuroinflammation through the Nrf2-mediated HO-1 expression. These results demonstrated that BJ-1103 may have good therapeutic agent against neurodegenerative diseases that are induced by oxidative stress and neuroinflammation.

Recent progress on the traditional Chinese medicines that regulate the blood

In traditional Chinese medicine, the herbs that regulate blood play a vital role. Here, nine herbs including Typhae Pollen, Notoginseng Root, Common Bletilla Tuber, India Madder Root and Rhizome, Chinese Arborvitae Twig, Lignum Dalbergiae Oderiferae, Chuanxiong Rhizoma, Corydalis Tuber, and Motherwort Herb were selected and reviewed for their recent studies on anti-tumor, anti-inflammatory and cardiovascular effects. Besides, the analytical methods developed to qualify or quantify the active compounds of the herbs are also summarized.

2,4,5-Trimethoxyldalbergiquinol promotes osteoblastic differentiation and mineralization via the BMP and Wnt/β-catenin pathway

Dalbergia odorifera has been traditionally used as a medicine to treat many diseases. However, the role of 2,4,5-trimethoxyldalbergiquinol (TMDQ) isolated and extracted from D. odorifera in osteoblast function and the underlying molecular mechanisms remain poorly understood. The aim of this study was to investigate the effects and possible underlying mechanisms of TMDQ on osteoblastic differentiation of primary cultures of mouse osteoblasts as an in vitro assay system. TMDQ stimulated osteoblastic differentiation, as assessed by the alkaline phosphatase (ALP) activity, ALP staining, mineralized nodule formation, and the levels of mRNAs encoding the bone differentiation markers, including ALP, bone sialoprotein (BSP), osteopontin, and osteocalcin. TMDQ upregulated the expression of Bmp2 and Bmp4 genes, and increased the protein level of phospho-Smad1/5/8. Furthermore, TMDQ treatment showed the increased mRNA expression of Wnt ligands, phosphorylation of GSK3, and the expression of β-catenin protein. The TMDQ-induced osteogenic effects were abolished by Wnt inhibitor, Dickkopf-1 (DKK1), and bone morphogenetic protein (BMP) antagonist, noggin. TMDQ-induced runt-related transcription factor 2 (Runx2) expression was attenuatted by noggin and DKK1. These data suggest that TMDQ acts through the activation of BMP, Wnt/β-catenin, and Runx2 signaling to promote osteoblast differentiation, and we demonstrate that TMDQ could be a potential agent for the treatment of bone loss-associated diseases such as osteoporosis.

Spatholobus suberectus inhibits osteoclastogenesis and stimulates chondrogenesis

This study was carried out to investigate the effect of Spatholobus suberectus Dunn (SS) on the protection of chondral defect and inhibition of osteoclastogenesis. To examine these effects, we measured the matrix metalloproteinase (MMP) levels in SW1353 chondrosarcoma cells and performed tartrate-resistant acid phosphatase (TRAP) staining in bone marrow macrophage (BMM)-derived osteoclasts. To investigate the anti-osteoarthritis (OA) effects, we assessed TNF-α-induced MMP-1, -3, -9 and tissue inhibitors of matrix metalloproteinase (TIMP) expression levels in SW1353 cells. We observed that SS extract significantly inhibited MMP and TIMP expression in SW1353 cells. Also, SS extract inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation. These results suggest that SS extract may have a potential in the treatment of bone loss and chondral defect by suppressing osteoclast differentiation and decreasing the expression of OA factors. Therefore, clarification of the mechanism of the action of SS extract and its active components is needed.