Orcinol glucoside targeted p38 as an agonist to promote osteogenesis and protect glucocorticoid-induced osteoporosis

Kaempferol combats the osteogenic differentiation damage of periodontal ligament stem cells in periodontitis via regulating EphrinB2-mediated PI3K/Akt and P38 pathways

BACKGROUND

The osteogenic differentiation of periodontal ligament stem cells (PDLSCs) plays a fundamental role in endogenous bone regeneration during periodontitis treatment, yet achieving consistent differentiation under inflammatory conditions remains clinically challenging. Kaempferol, a phytochemical flavonol, has demonstrated osteoprotective efficacy in osteoporosis and bone repair models. However, whether kaempferol exerts pro-osteogenic effects on PDLSCs within the pathologically complex microenvironment of periodontitis, and through what molecular mechanisms, remains unexplored.

PURPOSE

This study aimed to systematically characterize the therapeutic efficacy of kaempferol in restoring osteogenic differentiation of human PDLSCs under inflammatory stress, and promoting bone regeneration in a mice periodontitis model, and elucidate novel molecular targets and downstream mechanisms mediating these regenerative actions.

METHODS

An in vitro inflammatory microenvironment was established using lipopolysaccharide (LPS)-stimulated human PDLSCs to mimic periodontitis-induced osteogenic impairment. Osteogenic recovery was assessed through alkaline phosphatase (ALP), alizarin red S staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analysis of osteogenesis-related markers (ALP, RUNX2, OSX, OPN). The bioinformatics, network pharmacology and siRNA transfection were performed to identify EphrinB2 as kaempferol's putative cellular target. Downstream PI3K/Akt and p38 MAPK pathway activation was evaluated through phosphoprotein analysis. In vivo validation employed micro-CT quantification of alveolar bone loss and immunohistochemical profiling of pathways key proteins in a mice periodontitis model.

RESULTS

Kaempferol dose-dependently rescued LPS-impaired osteogenic differentiation in human PDLSCs, especially at 10 μM, where kaempferol significantly reversed suppressed ALP activity, mineralized nodule formation, and transcriptional and protein expression of osteogenic markers (ALP, RUNX2, OSX, OPN). Mechanistically, kaempferol upregulated the key target EphrinB2 under inflammatory stress, thereby reactivating the downstream PI3K/Akt and p38 pathways. In periodontitis mice, kaempferol administration (10 mg/kg) significantly promoted the periodontal expression of OPN and EphrinB2, restored the phosphorylation of PI3K, AKT, and P38, attenuating alveolar bone loss by 63.8 % (BV/TV: 72.4 % ± 2.07 vs. 44.2 % ± 3.19 in CON).

CONCLUSION

Kaempferol could rescue PDLSCs' osteogenic differentiation and mitigates bone loss in periodontitis microenvironments by targeting EphrinB2 to activate PI3K/Akt and P38 pathways. This work underscores kaempferol's potential as a natural therapeutic for reversing pathological bone resorption and promoting periodontal regeneration.

Targeting p38 MAPK: A potential bridge between ER stress and age-related bone loss

The endoplasmic reticulum (ER) is crucial in the development of numerous age-related bone disorders. Notably, ER stress can precipitate bone loss by orchestrating inflammatory responses, apoptosis, and autophagy through the activation of the p38 MAPK pathway. Age-related bone loss diseases pose a significant burden on society and healthcare as the global population ages. This review provides a comprehensive analysis of recent research advancements, delving into the critical role of ER stress-activated p38 MAPK in inflammation, apoptosis, and autophagy, as well as its impact on bone formation and bone resorption. This review elucidates the molecular mechanisms underlying the involvement of ER stress-activated p38 MAPK in osteoporosis, rheumatoid arthritis, periodontitis, and osteoarthritis and discusses the therapeutic potential of targeting p38 MAPK. Furthermore, this review provides a scientific foundation for new therapeutic strategies by highlighting prospective research directions.

Stephanine Protects Against Osteoporosis by Suppressing Osteoclastogenesis via Inhibition of the RANKL-RANK Interaction

The interaction between the receptor activator of nuclear factor-κB ligand (RANKL) and its receptor RANK is known to regulate osteoclastogenesis in bone remodelling and has become an important therapeutic target for the treatment of osteoporosis. Stephanine (SA), an isoquinoline aporphine-type alkaloid isolated from Stephania plants, possesses excellent anti-inflammatory effects and can be used for rheumatoid arthritis treatment. However, its specific role in osteoclastogenesis and osteoporosis remains unknown. In this study, we investigated the influence of SA on osteoclastogenesis in RANKL-stimulated RAW 264.7 cells and osteoporosis in an ovariectomised (OVX) mouse model and elucidated the underlying molecular mechanism. In vitro, SA can bind to RANK and RANKL with the KD values of 3.7 and 76.47 μM, respectively, and disrupt the RANKL-RANK interaction, which inhibits RANKL-stimulated RANK-tumour necrosis factor receptor associated factor 6 (TRAF6) binding and RANK signalling pathways activation, downregulates the expression of key osteoclastogenesis-related regulatory factors in osteoclast precursors, ultimately suppresses osteoclast differentiation and activation. In vivo, SA significantly ameliorated bone loss through inhibiting osteoclastogenesis in OVX mice because of the decreased number of osteoclasts and the increased trabecular bone area. SA markedly inhibited the serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b), c-telopeptide of type I collagen (CTX-I), and RANKL, whereas it increased that of osteoprotegerin (OPG) in OVX mice. Additionally, SA strikingly downregulated the OVX-induced expression of osteoclast-specific genes and proteins. Taken together, this study elucidated that SA can effectively protect against osteoporosis by suppressing osteoclastogenesis via inhibition of the RANKL-RANK interaction, which supports the potential application of SA as a natural therapeutic agent for osteoporosis.

Integrated Thermal Proteome Profiling and Affinity Ultrafiltration Mass Spectrometry (iTPAUMS): A Novel Paradigm for Elucidating the Mechanism of Action of Natural Products

Natural products (NPs) are foundational to drug discovery, offering a rich repertoire of molecular diversity with multifaceted modes of action against a broad array of targets. Despite their potential, deconvoluting the intricate mechanism of action (MoA) of NPs, characterized by their multicomponent, multitarget, and multilevel interactions, remains a formidable challenge. Here, we introduce an innovative pipeline called integrated thermal proteome profiling and affinity ultrafiltration mass spectrometry (iTPAUMS). This approach combines the high-throughput capacity of thermal proteome profiling (TPP) with the specificity of affinity ultrafiltration mass spectrometry (AUMS), creating a powerful toolkit for elucidating complex MoAs of NPs. Significantly, our investigation represents a pioneering application of TPP to delineate the target group of NPs mixtures and overcome the long-standing obstacle of mapping specific component-target interactions through AUMS. Our findings demonstrate the utility of iTPAUMS in constructing a comprehensive component-target atlas, providing a robust analytical foundation for unraveling the intricate pharmacological landscapes of NPs and advancing drug discovery.

Dendrobine Ameliorates Glucocorticoid-Induced Osteoporosis by Promoting Osteogenesis through JNK/p38 MAPK Pathway Activation and GR Nuclear Translocation Inhibition

Glucocorticoid-induced osteoporosis (GIOP) is the common reason for secondary osteoporosis. Dendrobine (DEN) is the major biologically active component of Dendrobium officinale with anti-inflammatory and antiaging properties. Whether DEN could alleviate osteogenic inhibition in GIOP rats is still unknown. The influence on osteogenic function caused by DEN on dexamethasone-treated bone marrow mesenchymal stem cells and rats was observed. The in vitro results showed that DEN reversed the inhibition of osteogenic differentiation by dexamethasone. Moreover, DEN supplementation attenuated dexamethasone-induced bone loss in vivo. DEN activated JNK and p38 MAPK pathways and restrained GR nuclear translocation, which could be prevented by the JNK (SP600125) or p38 (SB203580) pathway inhibitor. This study verified that DEN alleviated dexamethasone-induced nuclear translocation of GR, and inhibition of osteogenesis via JNK and p38 pathways, laying the foundation for DEN as a therapeutic agent for GIOP.

Withanolides from the active extract of Physalis angulate and their anti-hepatic fibrosis effects

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis angulata L., a traditional Chinese medicine called "Kuzhi" in China, was used traditionally to treat liver diseases (eg. icterus, hepatitis) as well as malaria, asthma, and rheumatism.

AIM OF THE STUDY

Our study aimed to investigate the withanolides with anti-hepatic fibrosis effect from P. angulate.

MATERIALS AND METHODS

Withanolides were obtained from the EtOH extract of P. angulate by bioassay-molecular networking analysis-guided isolation using column chromatography and normal/reversed-phase semipreparative HPLC. The structures of new withanolides were elucidated by combinations of spectroscopic techniques with NMR and ECD calculations. MTT cell viability assay, AO/EB staining method, cell wound healing assay, ELISA and Western blot experiments were employed to evaluate the anti-hepatic fibrosis activity and to uncover related mechanism. Molecular docking analysis and cellular thermal shift assay were used to evaluate and verify the interaction between the active withanolides and their potential targets.

RESULTS

Eight unreported withanolides, withagulides A-H (1-8), along with twenty-eight known ones were obtained from P. angulate. Withanolides 6, 9, 10, 24, 27, and 29-32 showed marked anti-hepatic fibrosis effect with COL1A1 expression inhibition above 50 %. Physalin F (9), the main component in the active fraction, significantly decreased the TGF β1-stimulated expressions of collagen I and α-SMA in LX-2 cells. Mechanism study revealed that physalin F exerted its anti-hepatic fibrosis effect via the PI3K/AKT/mTOR signaling pathway.

CONCLUSION

This study suggested that withanolides were an important class of natural products with marked anti-hepatic fibrosis effect. The main withanolide physalin F might be a promising candidate for hepatic fibrosis treatment. The work provided experimental foundation for the use of P. angulate to treat hepatic fibrosis.

Glaucatotones A-I: Guaiane-type sesquiterpenoids from the roots of Lindera glauca with anti-inflammatory activity

Glaucatotones A - I, nine new guaiane-type sesquiterpenoids, along with two reported compounds, namely (1β,5β)-1-hydroxyguaia-4(15),11(13)-dieno-12,5-lactone (10) and pseudoguaianelactone C (11), were isolated from the roots of Lindera glauca. The structures and absolute configurations of these compounds were elucidated by extensive spectroscopic analyses, single-crystal X-ray diffraction, and comparison of experimental and calculated electronic circular dichroism (ECD) data. Structurally, glaucatotone A (1) is characterized as a dihomosesquiterpenoid with an unprecedented 5/5/7/6 ring system. A pair of enantiomers, (±)-glaucatotone B (2a/2b), represent the first rearranged norsesquiterpenoid with a (cyclopentylmethyl)cyclohexane skeleton. 3 is defined as a dinorsesquiterpenoid possessing a 5/7/5 ring system. 4-6 are three guaiane-type norsesquiterpenoids. In vitro bioactivity, 2a selectively inhibited Bcap-37 with IC50 value of 5.60 μM, and 9 selectively inhibited Du-145 with IC50 value of 5.52 μM. The anti-inflammatory activity of 1-9 were tested, and of these compounds, 1, 2a, 2b and 7 exhibited potent inhibitory effects.

Comparison of the Glucocorticoid Receptor Binding and Agonist Activities of Typical Glucocorticoids: Insights into Their Endocrine Disrupting Effects

Over the past decades, the synthetic glucocorticoids (GCs) have been widely used in clinical practice and animal husbandry. Given the health hazard of these toxic residues in food, it is necessary to explore the detailed interaction mechanisms of typical GCs and their main target glucocorticoid receptor (GR). Hence, this work compared the GR binding and agonist activities of typical GCs. Fluorescence polarization assay showed that these GCs were potent ligands of GR. Their GR binding affinities were in the order of methylprednisolone>betamethasone≈prednisolone>dexamethasone, with IC50 values of 1.67, 2.94, 2.95, and 5.58 nM. Additionally, the limits of detection of dexamethasone, betamethasone, prednisolone, and methylprednisolone were 0.32, 0.14, 0.19, and 0.09 μg/kg in fluorescence polarization assay. Reporter gene assay showed that these GCs induced GR transactivation in a dose-dependent manner, confirming their GR agonist activities. Among which, dexamethasone at the concentration of 100 nM produced a maximal induction of more than 11-fold over the blank control. Molecular docking and molecular dynamics simulations suggested that hydrogen-bonding and hydrophobic interactions played an important role in stabilizing the GC-GR-LBD complexes. In summary, this work might help to understand the GR-mediated endocrine disrupting effects of typical GCs.