Effect of Usnic Acid on Osteoclastogenic Activity

Lipopolysaccharide-Induced Bone Loss in Rodent Models: A Systematic Review and Meta-Analysis

Osteoporosis has traditionally been characterized by underlying endocrine mechanisms, though evidence indicates a role of inflammation in its pathophysiology. Lipopolysaccharide (LPS), a component of gram-negative bacteria that reside in the intestines, can be released into circulation and stimulate the immune system, upregulating bone resorption. Exogenous LPS is used in rodent models to study the effect of systemic inflammation on bone, and to date a variety of different doses, routes, and durations of LPS administration have been used. The study objective was to determine whether systemic administration of LPS induced inflammatory bone loss in rodent models. A systematic search of Medline and four other databases resulted in a total of 110 studies that met the inclusion criteria. Pooled standardized mean differences (SMDs) and corresponding 95% confidence intervals (CI) with a random-effects meta-analyses were used for bone volume fraction (BV/TV) and volumetric bone mineral density (vBMD). Heterogeneity was quantified using the I² statistic. Shorter-term (<2 weeks) and longer-term (>2 weeks) LPS interventions were analyzed separately because of intractable study design differences. BV/TV was significantly reduced in both shorter-term (SMD = -3.79%, 95% CI [-4.20, -3.38], I² 62%; p < 0.01) and longer-term (SMD = -1.50%, 95% CI [-2.00, -1.00], I² 78%; p < 0.01) studies. vBMD was also reduced in both shorter-term (SMD = -3.11%, 95% CI [-3.78, -2.44]; I² 72%; p < 0.01) and longer-term (SMD = -3.49%, 95% CI [-4.94, -2.04], I² 82%; p < 0.01) studies. In both groups, regardless of duration, LPS negatively impacted trabecular bone structure but not cortical bone structure, and an upregulation in bone resorption demonstrated by bone cell staining and serum biomarkers was reported. This suggests systemically delivered exogenous LPS in rodents is a viable model for studying inflammatory bone loss, particularly in trabecular bone. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Lichens in Pharmacological Action: What Happened in the Last Decade?

Lichens are a unique group of organisms, which can produce compounds that are named secondary metabolites and rarely or are not produced in other organisms. Lichens possess pharmacological actions related to their secondary metabolites. Our knowledge of lichens and their pharmacological actions rapidly increases as new technologies and devices, which facilitate the investigation of the chemical profile and biological activities of lichens, are introduced and become more readily available. In addition, new methods and perspectives, as well as suggestions for pharmacological mechanisms, accumulate daily. Furthermore, lichen substances stand as a relatively untapped source of natural products. Accordingly, researchers investigate the pharmacological actions of lichen-derived material more frequently than it was in the past. This review focused on the pharmacological activities of lichens published in the last 11 years (2012-2022). Literature data obtained from WebOfScience and PubMed databases using related search keywords revealed that anti-genotoxicity, anticancer, and anti-microbial activity studies have constantly been conducted. More recently, immunomodulatory and inflammation-related studies took to the stage. Enzyme inhibition actions were popular as well. Our selection was based on the novelty and mechanistic insight that papers presented.

Dendrobine attenuates osteoclast differentiation through modulating ROS/NFATc1/ MMP9 pathway and prevents inflammatory bone destruction

BACKGROUND

Osteolytic diseases share symptoms such as bone loss, fracture and pain, which are caused by over-activated osteoclasts. Targeting osteoclast differentiation has emerged as a therapeutic strategy clinically. Dendrobine is an alkaloid isolated from Chinese herb Dendrobium nobile, with knowing effects of analgesia and anti-inflammation. The roles of dendrobine on osteoclasts and osteolysis remain unclear.

PURPOSE

Herein, the possible roles of dendrobine in osteoclastogenesis, inflammatory osteolysis and the underlying mechanism were explored.

METHODS

Bone marrow-derived macrophages (BMMs) and RAW264.7 cells were employed to evaluate the roles of dendrobine on osteoclastogenesis, bone absorption and the underlying mechanism in vitro. LPS injection was used to cause inflammatory osteolysis in vivo.

RESULTS

Dendrobine repressed osteoclastogenesis, bone resorption induced by receptor activator of nuclear factor kappa B ligand (RANKL) in vitro. Mechanistically, dendrobine inhibited RANKL-upregulated intracellular (ROS), p-p38, c-Fos expression and nuclear factor of activated T cells (NFATc1) nuclear translocation. Osteoclastic genes were reduced, and among them matrix metalloproteinase 9 (MMP9) mRNA was dramatically blocked by dendrobine. Moreover, it substantially suppressed MMP9 protein expression during osteoclastogenesis in vitro. Accordingly, oral 20 mg/kg/day dendrobine was capable of preventing LPS-induced osteolysis with decreased osteoclasts in vivo.

CONCLUSION

Taken together, dendrobine suppresses osteoclastogenesis through restraining ROS, p38-c-Fos and NFATc1-MMP9 in vitro, thus attenuates inflammatory osteolysis in vivo. This finding supports the discover of dendrobine as a novel osteoclast inhibitor for impeding bone erosion in the future.

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

Morin is a natural compound isolated from moraceae family members and has been reported to possess a range of pharmacological activities. However, the effects of morin on bone-associated disorders and the potential mechanism remain unknown. In this study, we investigated the anti-osteoclastogenic effect of morin in vitro and the potential therapeutic effects on ovariectomy (OVX)-induced osteoporosis in vivo. In vitro, by using a bone marrow macrophage-derived osteoclast culture system, we determined that morin attenuated receptor activator of nuclear factor (NF)-κB ligand (RANKL)-induced osteoclast formation via the inhibition of the mitogen-activated protein kinase (MAPK), NF-κB and calcium pathways. In addition, the subsequent expression of nuclear factor of activated T cells c1 (NFATc1) and c-fos was significantly suppressed by morin. In addition, NFATc1 downregulation led to the reduced expression of osteoclastogenesis-related marker genes, such as V-ATPase-d2 and Integrin β3. In vivo, results provided that morin could effectively attenuate OVX-induced bone loss in C57BL/6 mice. In conclusion, our results demonstrated that morin suppressed RANKL-induced osteoclastogenesis via the NF-κB, MAPK and calcium pathways, in addition, its function of preventing OVX-induced bone loss in vivo, which suggested that morin may be a potential therapeutic agent for postmenopausal osteoporosis treatment.

Usnic acid suppresses cervical cancer cell proliferation by inhibiting PD-L1 expression and enhancing T-lymphocyte tumor-killing activity

The programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway is abnormally expressed in cervical cancer cells. Moreover, PD-1/PD-L1 blockade reduces the apoptosis and exhaustion of T cells and inhibits the development of malignant tumors. Usnic acid is a dibenzofuran compound originating from Usnea diffracta Vain and has anti-inflammatory, antifungal, and anticancer activities. However, the molecular mechanism of its antitumor effects has not been fully elucidated. In this work, we first observed that usnic acid decreased the expression of PD-L1 in HeLa cells and enhanced the cytotoxicity of co-cultured T cells toward tumor cells. Usnic acid inhibited PD-L1 protein synthesis by reducing STAT3 and RAS pathways cooperatively. It was subsequently shown that usnic acid induced MiT/TFE nuclear translocation through the suppression of mTOR signaling pathways, and promoted the biogenesis of lysosomes and the translocation of PD-L1 to the lysosomes for proteolysis. Furthermore, usnic acid inhibited cell proliferation, angiogenesis, migration, and invasion, respectively, by downregulating PD-L1, thereby inhibiting tumor growth. Taken together, our results show that usnic acid is an effective inhibitor of PD-L1 and our study provide novel insights into the mechanism of its anticancer targeted therapy.

Biomolecule from Trigonella stellata from Saudi Flora to Suppress Osteoporosis via Osteostromal Regulations

Trigonella stellata has used in folk medicine as palatable and nutraceutical herb. It also regulates hypocholesterolemia, hypoglycemia, and has showed anti-inflammatory activities as well as antioxidants efficacy. Osteoporosis is a one of bone metabolic disorders and is continuously increasing worldwide. In the present study, caffeic acid was isolated from Trigonella stellata and identified using 1 D- and 2 D-NMR spectroscopic data. Caffeic acid was investigated on osteoblast and osteoclast in vitro using mice bone marrow-derived mesenchymal cells. Caffeic acid played reciprocal proliferation between osteoblast and osteoclast cells and accelerated the bone mineralization. It was confirmed by cytotoxicity, alkaline phosphatase (ALP), alizarin red S (ARS), and Tartrate resistant acid phosphatase (TRAP) assay. Caffeic acid regulated the osteogenic marker and upregulated the osteopontin, osteocalcin, and bone morphogenic proteins (BMP). Quantitative real time PCR and Western blot were used to quantify the mRNA and protein markers. It also regulated the matrix metalloprotease-2 (MMP-2) and cathepsin-K proteolytic markers in osteoclast cells. In addition, caffeic acid inhibited bone resorption in osteoclast cells. On the other hand, it upregulate osteoblast differentiation through stimulation of extracellular calcium concentrations osteoblast differentiation, respectively. The results also were confirmed through in silico docking of caffeic acid against cathepsin-B and cathepsin-K markers. These findings revealed that caffeic acid has a potential role in bone-metabolic disorder through its multifaceted effects on osteoblast and osteoclast regulations and controls osteoporosis.

A review on osteoclast diseases and osteoclastogenesis inhibitors recently developed from natural resources

Natural products have been investigated as potential candidates of novel therapeutics and play a crucial role in advanced medicinal drugs. Natural resources, including local medicinal plants (especially folk medicinal plants), animals, bacteria, and fungi have been used for more than a century, and are precious gifts from nature, providing potential medicines with high safety. Osteoclast-related diseases, such as osteoporosis, rheumatoid arthritis, Paget's disease, osteoclastoma, and periprosthetic osteolysis, are currently the most common reasons for bone inflammation, pain and fractures, resulting in low quality of life. However, the curative effects of current therapeutic drugs for these osteoclast-related diseases are limited, and long-term treatment is needed. Further, in severe cases, surgical treatments are necessary, which may cause unaffordable expenses and subsequent influences such as neuralgia, mental stress, and even development of cancer. Thus, safer inhibitors and potential drugs with enhanced curative effects and quick relief are needed to treat patients with osteoclast diseases. This review aims to introduce the main osteoclast-related diseases and some of the recently developed naturally sourced inhibitors against osteoclastogenesis, also it is desired to attract people's attention on using widely available natural resources for the evolution of new types of osteoclast inhibitors with minimal or no side-effects upon long-term treatments.

Mycousfurans A and B, Antibacterial Usnic Acid Congeners from the Fungus Mycosphaerella sp., Isolated from a Marine Sediment

Mycousfurans (1 and 2), two new usnic acid congeners, along with (−)-mycousnine (3), (−)-placodiolic acid (4), and (+)-usnic acid (5), were isolated using high-performance liquid chromatography-ultraviolet (HPLC-UV)-guided fractionation of extracts of Mycosphaerella sp. isolated from a marine sediment. The planar structures of 1 and 2 were elucidated using 1D and 2D NMR spectra. The relative configurations of the stereogenic carbons of 1 and 2 were established via analysis of their nuclear Overhauser spectroscopy (NOESY) spectra, and their absolute configurations were determined using a comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1 and 2 were found to have antibacterial activity, showing moderate activity against Kocuria rhizophila and Staphylococcus aureus.

Extracts of Flavoparmelia sp. Inhibit Receptor Activator of Nuclear Factor-κB Ligand-Mediated Osteoclast Differentiation

Background

Osteoporosis is a geriatric disease with diminished bone density. The increase in the number of patients and medical expenses due to a global aging society are recognized as problems. Bone loss is the most common symptom of bone disease, not only osteoporosis but Paget's disease, rheumatoid arthritis, multiple myeloma, and other diseases. The main cause of this symptoms is excessive increase in the number and activity of osteoclasts. Osteoclasts are multinucleated giant cells that can resorb bone. They are differentiated and activation from monocytes/macrophages in the presence of macrophage colony-stimulating factor and receptor activator of nuclear factor-κB ligand (RANKL).

Methods

The effect of extract of Flavoparmelia sp. (EFV), a genus of lichenized fungi within the Parmeliaceae, on the differentiation of bone marrow-derived macrophages (BMMs) into osteoclasts was examined by phenotype assay and the cell cytotoxicity was evaluated by cell counting kit-8. The osteoclast differentiation-related genes and proteins were investigated by real-time polymerase chain reaction and immunoblotting. The functional activity of osteoclast in response to EFV treatment was evaluated by an Osteo Assay plate.

Results

In this study, we found that EFV, a genus of lichenized fungi within the Parmeliaceae, inhibited osteoclast formation. And we investigated its inhibitory mechanism. EFV reduced RANKL-mediated osteoclast formation and activation by inhibiting expression of nuclear factor of activated T cells 1, a key factor of osteoclastogenesis.

Conclusions

Taken together, our results show that EFV is a promising candidate for health functional foods or therapeutic agents that can help treat bone diseases such as osteoporosis.