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

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.