Morin attenuates osteoclast formation and function by suppressing the NF-κB, MAPK and calcium signalling pathways

Isonardosinone attenuates osteoclastogenesis and OVX-induced bone loss via the MAPK/NF-κB pathway

Osteoporosis is a globally prevalent metabolic bone disease that manifests itself as a decrease in bone mineral density and deterioration of bone structure, which reduces overall bone strength and increases fracture risk. However, the effect of anti-inflammatory isonardosinone (the active ingredient in Nardostachys chinensis) on osteoclastogenesis is unknown. We first predicted the main pathways and targets of ISO action in osteoporosis by network pharmacology. CCK-8 was used to test whether ISO affects cell proliferation of BMMs (osteoclast precursor cells) and to determine the safe action concentration. TRAcP and F-actin staining were used to characterise the inhibitory effect on osteoclast differentiation. RT-PCR and WB were used to examine changes in the relative expression of genes and proteins generated by osteoclasts under isopinacolone treatment, and we examined its effects on the RANKL-activated MAPK and NF-κB signaling pathways. An ovariectomy-induced osteoporosis model was constructed to assess the in vivo therapeutic effects of ISO. CCK-8 results showed that ISO had no cytotoxic or proliferative effects on BMMs at concentrations below 30 μM; TRAcP staining showed that ISO suppressed osteoclastogenesis in a concentration- and time-gradient-dependent manner; and F-actin staining showed that ISO suppressed osteoblast skeleton formation and expansion; RT-PCR and Western Blot assays showed that ISO suppressed the expression of CTSK, NFATC1, MMP9, C-Fos, and ACP5, inhibited the phosphorylation of JNK, P38, and ERK, and reversed the degradation of IκB-α, especially within 15 min. The in vivo results indicated that ISO has therapeutic effects on osteoporosis by improving bone microstructure to rescue bone loss. Taken together, these results lead to the conclusion that ISO is an attractive drug development strategy for the treatment of osteoporosis by effectively suppressing osteoclastogenesis through the MAPK/NF-κB signaling pathway, thereby reversing the bone loss associated with ovariectomy in vivo.

Astragaloside IV attenuates glucocorticoid-induced osteoclastogenesis and bone loss via the MAPK/NF-κB pathway

BACKGROUND

Astragaloside IV (AS-IV) is a bioactive saponin extracted from Radix Astragali, and it is reported to promote osteoblast differentiation while inhibiting osteoclastogenesis. However, the mechanism of AS-IV in glucocorticoid-induced osteoclastogenesis (GIO) remains undetermined. Herein, we examined the influence of AS-IV on GIO and bone loss.

METHODS

RAW264.7 cells were incubated with dexamethasone (Dex) alone or Dex and receptor activator of nuclear factor-B ligand (RANKL) (Dex and RANKL) for 2 days, and then treated with Dex or Dex and RANKL through AS-IV for the timeframes indicated. Following, mice were intraperitoneally administered with an intermediate-acting glucocorticoid, methylprednisolone (MP), or MP and AS-IV for 6 weeks.

RESULTS

AS-IV significantly decreased Dex-induced osteoclast nucleus and area, however, it did not impact the number of Dex-induced osteoclasts in RAW264.7 cells. AS-IV also significantly decreased the osteoclastic marker protein expressions in Dex-induced RAW264.7 cells with concentration of dose dependent fashion. Additionally, AS-IV promoted p38 phosphorylation (p-) and p-p65 translocation to the nucleus, while inhibiting phosphorylation of extracellular signal-regulated kinase (ERK) (p-ERK) and inhibitor of Nuclear factor κB (NF-κB) (p-IκB) levels. However, the AS-IV-mediated action on p-MAPK, p-NF-κB, and osteoclastic marker expressions were reversed by MAPK or IκB inhibitor in Dex-induced RAW264.7 cells. Furthermore, our in vivo evaluation revealed that AS-IV also attenuated the MP-mediated bone loss, and suppressed osteoclastogenesis.

CONCLUSIONS

This study demonstrates that AS-IV inhibits GIO and attenuates bone loss via the MAPK/NF-κB pathway. This also suggested that AS-IV could be a potential promising therapeutic agent for glucocorticoid-triggered bone loss.

Morin Improves the Bone Histomorphology and Biochemical Markers in an Animal Model of Ovariectomy-Induced Osteoporosis by Suppressing Autophagy and Apoptosis

Osteoporosis (OP) is the most prevalent metabolic bone disease and an important postmenopausal consequence. This study aimed to investigate the effects of morin, a flavonoid with beneficial properties, on ovariectomy-induced OP. Animals were ovariectomized (OVX) and treated with different doses of morin (15, 30, and 45 mg/kg/day) or estradiol (10 μg/kg/day) for 10 weeks by gavage. Then bone histo-stereology, bone-related biochemical indicators, and gene and protein levels of autophagy and apoptosis-related markers were analyzed. In comparison to controls, OVX significantly decreased the number of osteoblasts (5.78 × 106 vs. 1.66 × 106) and osteocytes (32.55 × 106 vs. 11.92 × 106), whereas increasing the number of osteoclasts (83.38 × 103 vs. 392.1 × 103). Moreover, OVX caused a remarkable decrease in bone structures and Ca, P, and estradiol levels while increasing ALP and OC (p < 0.001). The administration of 45 mg/kg/day morin restored the effects of OP on bone histomorphology and biochemical markers (p < 0.05). Further studies revealed that morin caused a 7.1% and 36.6% decrease in the bone level of LC3 and BECN1 proteins, respectively, compared to the OVX group. Also, morin caused a significant decrease of 47.4% in the CASP3 level and a significant increase of 23.6% in the BCL-2 level compared to OVX animals (p < 0.001). The present findings showed that morin is potentially able to improve the bone-related histomorphological and biochemical changes caused by osteoporosis, which is probably attributed to the suppression of apoptosis- and autophagy-caused cell death.

Morin alleviates DSS-induced ulcerative colitis in mice via inhibition of inflammation and modulation of intestinal microbiota

Ulcerative colitis (UC) is a chronic inflammatory condition with recurrent and challenging symptoms. Effective treatments are lacking, making UC management a critical research area. Morin (MO), a flavonoid from the Moraceae family, shows potential as an anti-UC agent, but its mechanisms are not fully understood. Using a dextran sulfate sodium (DSS)-induced UC mouse model, we employed network pharmacology to predict MO's therapeutic effects. Assessments included changes in body weight, disease activity index (DAI), and colon length. Immunofluorescence, hematoxylin and eosin (H&E), and PAS staining evaluated colon damage. ELISA and western blot analyzed inflammatory factors, tight junction (TJ)-associated proteins (Claudin-3, Occludin, ZO-1), and Mitogen-Activated Protein Kinase (MAPK)/ Nuclear Factor kappa B (NF-κB) pathways. 16S rRNA sequencing assessed gut microbiota diversity, confirmed by MO's modulation via Fecal Microbial Transplantation (FMT). Early MO intervention reduced UC severity by improving weight, DAI scores, and colon length, increasing goblet cells, enhancing barrier function, and inhibiting MAPK/NF-κB pathways. MO enriched gut microbiota, favoring beneficial bacteria like Muribaculaceae and Erysipelotrichaceae while reducing harmful Erysipelotrichaceae and Muribaculaceae. This study highlights MO's potential in UC management through inflammation control, mucosal integrity maintenance, and gut flora modulation.

Macrophages in aseptic loosening: Characteristics, functions, and mechanisms

Aseptic loosening (AL) is the most common complication of total joint arthroplasty (TJA). Both local inflammatory response and subsequent osteolysis around the prosthesis are the fundamental causes of disease pathology. As the earliest change of cell behavior, polarizations of macrophages play an essential role in the pathogenesis of AL, including regulating inflammatory responses and related pathological bone remodeling. The direction of macrophage polarization is closely dependent on the microenvironment of the periprosthetic tissue. When the classically activated macrophages (M1) are characterized by the augmented ability to produce proinflammatory cytokines, the primary functions of alternatively activated macrophages (M2) are related to inflammatory relief and tissue repair. Yet, both M1 macrophages and M2 macrophages are involved in the occurrence and development of AL, and a comprehensive understanding of polarized behaviors and inducing factors would help in identifying specific therapies. In recent years, studies have witnessed novel discoveries regarding the role of macrophages in AL pathology, the shifts between polarized phenotype during disease progression, as well as local mediators and signaling pathways responsible for regulations in macrophages and subsequent osteoclasts (OCs). In this review, we summarize recent progress on macrophage polarization and related mechanisms during the development of AL and discuss new findings and concepts in the context of existing work.

Pharmacology-based molecular docking of 4-methylcatechol and its role in RANKL-mediated ROS/Keap1/Nrf2 signalling axis and osteoclastogenesis

4-Methylcatechol (4-MC) is an agonist of various neurotrophic factors, which can upregulate the expression of Heme oxygenase 1 (HO-1) protein by activating nuclear factor erythroid 2-related factor 2 (Nrf2), thereby inhibiting oxidative stress-induced neural stem cell death. During RANKL-stimulated osteoclast differentiation, intracellular reactive oxygen species (ROS) levels were increased. Nonetheless, the effect of 4-MC on osteoclast formation and bone resorption function has not been researched. In this study, we investigated the effect of HO-1 upregulation by 4-MC on RANKL-induced osteoclastogenesis and explored the molecular mechanism of HO-1 upregulation by 4-MC. We found that the small molecule compound 4-MC could bind to Keap1 amino acid residue of glycine GLY 367, isoleucine ILE 559 and valine VAL 606, with a predicted binding energy of -4.99 kcal/mol. 4-MC was found to inhibit osteoclast differentiation in vitro by activating Nrf2 to scavenge ROS, inhibiting NF-κB phosphorylation, and alleviating osteoporosis in ovariectomized (OVX) mice. Taken together, 4-MC reduces ROS by inhibiting Keap1, thereby preventing OVX-induced bone loss.

Bardoxolone methyl ameliorates osteoarthritis by inhibiting osteoclastogenesis and protecting the extracellular matrix against degradation

Inflammation and oxidative damage are closely related to the development of osteoarthritis. Bardoxolone methyl (CDDO-Me), a semisynthetic oleanane triterpenoid, plays a strong anti-inflammatory and antioxidant role. The purpose of our research was to explore fundamental mechanisms of CDDO-Me in orthopaedics development. The results showed that CDDO-Me inhibited nuclear factor-κB ligand (RANKL)-induced osteoclast formation and extracellular matrix (ECM) degradation by activating the Nrf2/HO-1 signaling pathways and inhibiting NF-κB pathway activation and excess ROS production. In vivo, CDDO-Me significantly attenuated articular cartilage proteoglycan loss and the number of TRAP-positive osteoclasts in a destabilized medial meniscus (DMM) mouse model of OA. Taken together, these data demonstrate that CDDO-Me inhibits osteoclastogenesis and ECM degradation, underscoring its potential therapeutic value in treating OA.

Casticin promotes osteogenic differentiation of bone marrow stromal cells and improves osteoporosis in rats by regulating nuclear factor-κB/mitogen-activated protein kinase

BACKGROUND

Osteoporosis has influenced millions of people, especially postmenopausal women, which has become a big burden to the whole world. Although the diverse roles of casticin (CAS) on different diseases were identified, whether it was implicated with osteoporosis was unknown.

METHODS

A rat model of osteoporosis was established through dexamethasone (DEX) treatment and a cell model reflecting the osteogenic and osteoclast induction was constructed in bone marrow stromal cells (BMSCs). The calcification at the late stage of induction was measured via Alizarin Red S staining. Western blot was applied to evaluate the levels of proteins.

RESULTS

Hematoxylin and eosin staining revealed that the number of bone trabecular in DEX-induced osteoporosis rats was decreased, while increased doses of CAS treatment elevated the number of bone trabecular. CAS treatment alleviated DEX-induced osteoporosis in rats. Moreover, we found that CAS inhibited the nuclear factor-κB/mitogen-activated protein kinase (NF-κB/MAPK) pathway. In addition, CAS promoted osteogenic differentiation of BMSCs and reduced osteoclastogenesis of bone marrow monocytes. Finally, CAS was observed to retard the receptor activator of NFκ-B ligand-induced NF-κB/MAPK pathway.

CONCLUSION

CAS promoted osteogenic differentiation of BMSCs and improved osteoporosis in rats by regulating the NF-κB/MAPK pathway. This might shed a light into using CAS as a drug treating osteoporosis in the future.

Morin Disrupts Cytoskeleton Reorganization in Osteoclasts through an ROS/SHP1/c-Src Axis and Grants Protection from LPS-Induced Bone Loss

Morin is a naturally occurring flavonoid with anti-inflammatory and antioxidative properties. Therefore, we hypothesized that morin may prevent inflammatory bone loss by reducing oxidative stress. To investigate the effect of morin on inflammatory bone loss, mice were injected with lipopolysaccharide (LPS). Osteoclasts (OCs) were analyzed by tartrate-resistant acid phosphatase (TRAP) staining and actin ring formation. Micro-computerized tomography analysis indicated that morin prevented LPS-induced bone loss in mice. In vivo TRAP staining indicated that morin decreased the number and surface of the OCs that were increased in LPS-treated mice. Furthermore, in vitro experiments indicated that morin decreased the number and activity of OCs upon LPS stimulation. Morin decreased actin ring-containing OCs with decreased activation of c-Src (Y416)/vav guanine nucleotide exchange factor 3/Ras-related C3 botulinum toxin substrate 1 compared with LPS alone. Morin decreased cytosolic reactive oxygen species (ROS), thus preventing the oxidation of Src homology region 2 domain-containing phosphatase 1 (SHP-1), followed by the inactivation of c-Src via direct interaction with SHP1. Conversely, SHP1 knockdown abolished the inhibitory effect of morin on OCs. Therefore, our findings suggest that morin disrupted cytoskeletal reorganization via an ROS/SHP1/c-Src axis in OCs, thereby granting protection from LPS-induced bone loss, which demonstrates its therapeutic potential against inflammatory bone loss.