ASP2-1, a polysaccharide from Acorus tatarinowii Schott, inhibits osteoclastogenesis via modulation of NFATc1 and attenuates LPS-induced bone loss in mice

Fecal microbiota transplantation alleviates lipopolysaccharide-induced osteoporosis by modulating gut microbiota and long non-coding RNA TUG1 expression

Purpose

To study whether fecal microbiota transplantation (FMT) can alleviate lipopolysaccharide (LPS)-induced osteoporosis (OP) by regulating the composition and abundance of gut microbiota and the expression level of long non-coding RNA (lncRNA) TUG1.

Methods

Twenty C57BL/6 mice were selected. Two mice were randomly designated as fecal donors, while the remaining mice were randomly divided into control group, LPS group, and LPS + FMT group. Each group consisted of 6 mice. The mice in the LPS and LPS + FMT groups were intraperitoneally injected with LPS to establish the OP model, and the mice in the LPS + FMT group were treated with donor feces by gavage. Micro-CT was used to scan the femur specimens of mice, and the bone structural parameters of the control and LPS groups were compared to verify the effectiveness of the OP model. HE staining was used to compare the microstructure of femurs in the 3 groups. 16S rRNA gene sequencing was used to analyze the composition and abundance of gut microbiota in mice. Immunofluorescence staining was used to compare the expression levels of Runt-related transcription factor 2 (RUNX2) in the femur of the 3 groups. Real-time quantitative reverse transcription PCR (qRT-PCR) was used to compare the expression levels of lncRNA TUG1 in the intestines and serum of mice in the 3 groups.

Results

Micro-CT showed that compared with the control group, the mice in the LPS group had more bone loss. The bone mineral density, trabecular number, and trabecular thickness of the control group was higher, and the trabecular separation was smaller. The models were validated effectively. HE staining showed that compared with the control group, the bone trabeculae in the LPS group were thinner and sparse, while that in the LPS + FMT group were dense and clear. The 16s rRNA sequencing showed that the abundance of Bacteroides and Lactobacillus in LPS+FMT group was significantly higher than that in LPS group. Immunofluorescence staining showed that the RUNX2 level in the control group and LPS + FMT group was similar, and both were higher than that in the LPS group. The qRT-PCR results showed that the TUG1 mRNA level in the control group and LPS + FMT group was similar and significantly higher than that in the LPS group.

Conclusion

FMT can enhance osteoblast levels and improve bone structure by modulating the abundance of gut microbiota in OP mice (such as increasing Bacteroides and Lactobacillus populations) and promoting the expression of lncRNA TUG1, thereby alleviating LPS-induced OP.

Effective mechanism of polysaccharides from Erxian herbal pair in promoting bone repair in traumatic osteomyelitis by activating osteoblast GPR41 and inhibiting the MEK/ERK/MAPK signalling axis

Polysaccharides are the key components of natural products; however, their effects on bone repair haven't been fully evaluated. This study aimed to assess the efficacy and mechanism of polysaccharides in promoting bone repair. The Erxian herb pair polysaccharide (EHP) was isolated and purified using water extraction (1:20 (w/v); 100 ± 2 °C; 5 h) and alcohol precipitation (80 ± 2 %). A traumatic osteomyelitis (TO) rat model was established using lipopolysaccharide (LPS). The gut microbiota was analysed through intestinal flora and metagenomic sequencing. The results revealed that the yields of crude polysaccharide and purified polysaccharide EHP were 3.73 ± 0.34 % and 0.48 ± 0.06 %, respectively. The total sugar content of EHP was 83.53 ± 0.16 %. The EHP, with a molecular weight of 31.964 kDa, was primarily composed of mannose, rhamnose, glucose, galactose, and arabinose. In vivo experiments demonstrated that EHP intervention (300 mg/kg/day) significantly augmented bone density and enhanced the activity of alkaline phosphatase (ALP) (P < 0.01). EHP upregulated the abundance of probiotics and increased the production of butyric acid (P < 0.05). In vitro experiments revealed that butyric acid (500-1000 μM) enhanced osteoblast activity and inhibited the expression of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) (P < 0.01). These findings indicate that polysaccharides may represent a promising therapeutic agent for bone-healing.

Structural identification and anti-neuroinflammatory effect of a heteropolysaccharide ATP50-3 from Acorus tatarinowii rhizome

Acorus tatarinowii, a famous traditional Chinese medicine, is used for the clinical treatment of memory impairment and dementia. In this research, AT50, the crude polysaccharide extracted from A. tatarinowii rhizome, significantly improved the memory and learning ability of mice with Alzheimer's disease (AD) and exerted excellent anti-neuroinflammatory effects. More importantly, AT50 returned the levels of NO, TNF-α, IL-1β, PGE-2, and IL-6 in AD mouse brains to normal levels. To identify the active ingredients in AT50, a heteropolysaccharide ATP50-3 was obtained from AT50. Structural analysis indicated ATP50-3 consisted of α-L-Araf-(1→, →2)-α-L-Araf-(1→, →3)-α-L-Araf-(1→, →5)-α-L-Araf-(1→, α-D-Xylp-(1→, →3,4)-β-D-Xylp-(1→, →3)-α-D-Galp-(1→, →3,6)-α-D-Galp-(1→, →6)-4-OAc-α-D-Galp-(1→, →3,4,6)-α-D-Galp-(1→, →4)-α-D-Glcp-(1→, →2,3,6)-β-D-Glcp-(1→, →4,6)-α-D-Manp-(1→, →3,4)-α-L-Rhap-(1→, →4)-α-D-GalpA-(1→, and →4)-α-D-GlcpA-(1 → residues and terminated with Xyl and Ara. Additionally, ATP50-3 significantly inhibited the release of proinflammatory factors in lipopolysaccharide-stimulated BV2 cells. ATP50-3 may be an active constituent of AT50, responsible for its anti-neuroinflammatory effects, with great potential to treat AD.

DNA hypomethylation ameliorates erosive inflammatory arthritis by modulating interferon regulatory factor-8

Epigenetic regulation plays a crucial role in the pathogenesis of autoimmune diseases such as inflammatory arthritis. DNA hypomethylating agents, such as decitabine (DAC), have been shown to dampen inflammation and restore immune homeostasis. In the present study, we demonstrate that DAC elicits potent anti-inflammatory effects and attenuates disease symptoms in several animal models of arthritis. Transcriptomic and epigenomic profiling show that DAC-mediated hypomethylation regulates a wide range of cell types in arthritis, altering the differentiation trajectories of anti-inflammatory macrophage populations, regulatory T cells, and tissue-protective synovial fibroblasts (SFs). Mechanistically, DAC-mediated demethylation of intragenic 5'-Cytosine phosphate Guanine-3' (CpG) islands of the transcription factor Irf8 (interferon regulatory factor 8) induced its re-expression and promoted its repressor activity. As a result, DAC restored joint homeostasis by resetting the transcriptomic signature of negative regulators of inflammation in synovial macrophages (MerTK, Trem2, and Cx3cr1), TREGs (Foxp3), and SFs (Pdpn and Fapα). In conclusion, we found that Irf8 is necessary for the inhibitory effect of DAC in murine arthritis and that direct expression of Irf8 is sufficient to significantly mitigate arthritis.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics

A. calamus var. angustatus Besser is an important traditional medicinal herb commonly used in China and other Asian countries. This study is the first systematic review of the literature to thoroughly analyze the ethnopharmacological application, phytochemistry, pharmacology, toxicology and pharmacokinetic properties of A. calamus var. angustatus Besser and provides a rationale for future research and prospects for application in clinical treatment. Information on relevant studies investigating A. calamus var. angustatus Besser was collected from SciFinder, the Web of Science, PubMed, CNKI, Elsevier, ResearchGate, ACS, Flora of China, and Baidu Scholar, etc. up to December 2022. In addition, information was also obtained from Pharmacopeias, books on Chinese herbal classics, local books, as well as PhD and MS dissertations. A. calamus var. angustatus Besser has played an important role in the herbal treatment of coma, convulsion, amnesia, and dementia for thousands of years. Studies investigating the chemical constituents of A. calamus var. angustatus Besser have isolated and identified 234 small-molecule compounds and a few polysaccharides. Among them, simple phenylpropanoids represented by asarone analogues and lignans are the two main active ingredients, which can be considered characteristic chemotaxonomic markers of this herb. In vitro and in vivo pharmacological studies indicated that crude extracts and active compounds from A. calamus var. angustatus Besser display a wide range of pharmacological activities, especially as treatment for Alzheimer's disease (AD), and anticonvulsant, antidepressant-like, anxiolytic-like, anti-fatigue, anti-Parkinson, neuroprotection, and brain protection properties, providing more evidence to explain the traditional medicinal uses and ethnopharmacology. The clinical therapeutic dose of A. calamus var. angustatus Besser does not present any toxic effects, but its main active ingredients α-asarone and β-asarone at excessive dose may lead to toxicity, and in particular, their respective epoxide metabolites may exert potential toxicity to the liver. This review provides a reference and further information for the future development and clinical application of A. calamus var. angustatus Besser.

FTY720 Attenuates LPS-Induced Inflammatory Bone Loss by Inhibiting Osteoclastogenesis via the NF-κB and HDAC4/ATF Pathways

Osteoclast (OC) abnormalities lead to many osteolytic diseases, such as osteoporosis, inflammatory bone erosion, and tumor-induced osteolysis. Exploring effective strategies to remediate OCs dysregulation is essential. FTY720, also known as fingolimod, has been approved for the treatment of multiple sclerosis and has anti-inflammatory and immunosuppressive effects. Here, we found that FTY720 inhibited osteoclastogenesis and OC function by inhibiting nuclear factor kappa-B (NF-κB) signaling. Interestingly, we also found that FTY720 inhibited osteoclastogenesis by upregulating histone deacetylase 4 (HDAC4) expression levels and downregulating activating transcription factor 4 (ATF4) expression levels. In vivo, FTY720 treatment prevented lipopolysaccharide- (LPS-) induced calvarial osteolysis and significantly reduced the number of tartrate-resistant acid phosphatase- (TRAP-) positive OCs. Taken together, these results demonstrate that FTY720 can inhibit osteoclastogenesis and ameliorate inflammation-induced bone loss. Which may provide evidence of a new therapeutic target for skeletal diseases caused by OC abnormalities.

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).

Monotropein Protects against Inflammatory Bone Loss and Suppresses Osteoclast Formation and Bone Resorption by Inhibiting NFATc1 via NF-κB and Akt/GSK-3β Pathway

Monotropein (Mon) is a kind of iridoid glycoside plant secondary metabolite primarily present in some edible and medicinal plants. The aim of this study was to investigate the effect of Mon on lipopolysaccharide (LPS)-induced inflammatory bone loss in mice and osteoclasts (OCs) derived from bone marrow-derived macrophages (BMMs), and explore the mechanisms underlying the effect of Mon on LPS-induced osteoclastogenesis. It was found that Mon markedly attenuated deterioration of the bone micro-architecture, enhanced tissue mineral content (TMC) and bone volume/total volume (BV/TV), reduced structure model index (SMI) and trabecular separation/spacing (Tb.Sp) in the bone tissue and decreased the activities of tartrate resistant acid phosphatase-5b (TRACP-5b), receptor activator NF-κB (RANK), and receptor activator NF-κB ligand (RANKL) as well as the serum levels of interleukin 6 (IL-6) and interleukin 1β (IL-1β) in LPS-treated mice. In addition, Mon treatment reduced the number of TRAP positive OCs in the bone tissue of LPS-treated mice and also exerted a stronger inhibitory effect on formation, differentiation, and F-actin ring construction of OCs derived from BMMs. Mon significantly inhibited the expression of the nuclear factor of activated T-cells c1 (NFATc1) and the immediate early gene (C-Fos) and nuclear translocation of NFATc1 in LPS-treated OCs, thereby inhibiting the expression of matrix metalloproteinase-9 (MMP-9), cathepsin K (CtsK), and TRAP. Mon significantly inhibited the expression of TRAF6, phosphorylation of P65, and degradation of IKBα, thus inhibiting the activation of NF-κB pathway in LPS-induced inflammatory mice and OCs derived from BMMs, and also inhibited LPS-induced phosphorylation of protein kinase B (Akt) and Glycogen synthase kinase 3β (GSK-3β) in OCs derived from BMMs. In conclusion, these results suggested that Mon could effectively inhibit osteoclastogenesis both in vitro and in vivo and therefore may prove to be potential option for prevention and treatment of osteoclastic bone resorption-related diseases.

Ginseng oligosaccharides protect neurons from glutamate-induced oxidative damage through the Nrf2/HO-1 signaling pathway

The effects of ginseng oligosaccharides (GSOs) on neuronal oxidative injury induced by glutamate (GLU) and the molecular mechanisms involved were investigated. Cell damage was assessed using MTT assays, and the lactate dehydrogenase (LDH) release rate and flow cytometry were used to detect the accumulation of reactive oxygen species (ROS) and mitochondrial membrane potential respectively. The levels of catalase (CAT) and glutathione (GSH) were measured in PC12 cells and Drosophila brain tissue. The climbing ability of Drosophila was observed. Levels of proteins, including Cyt C, Bcl-2/BAX, and Nrf2/HO-1-associated proteins, were determined by western blotting and immunofluorescence. It was found that GSOs reversed GLU-induced reductions in cell viability and the LDH release rate, and rescued ROS accumulation. GSOs also mitigated the deleterious effects of GLU on the mitochondrial membrane potential and Cyt C release, thus alleviating mitochondrial dysfunction, and increased GSH levels and CAT activity in both cells and Drosophila brain tissue. The climbing index in GSO-treated Drosophila was significantly higher than that in the tert-butyl-hydroperoxide-treated flies. Furthermore, GSOs protected cells against GLU-induced apoptosis by reducing the expression of the mitochondrial apoptosis-associated Bcl-2 family effector proteins and protected cells from GLU-induced oxidative damage by increasing the nuclear translocation of Nrf2 and HO-1 expression. These findings indicate that GSOs protect against GLU-induced neuronal oxidative damage through Nrf2/HO-1 activation.

Polysaccharides Extracted From Panax Ginseng C.A. Mey Enhance Complement Component 4 Biosynthesis in Human Hepatocytes

Panax ginseng C.A. Mey (ginseng) is a classic medicinal plant which is well known for enhancing immune capacity. Polysaccharides are one of the main active components of ginseng. We isolated water-soluble ginseng polysaccharides (WGP) and analyzed the physicochemical properties of WGP including molecular weight, monosaccharide composition, and structural characteristics. WGP had minimal effect on the growth of hepatocytes. Interestingly, WGP significantly increased the mRNA and protein levels of complement component 4 (C4), one of the core components of the complement system. Promoter reporter gene assays revealed that WGP significantly enhanced activity of the C4 gene promoter. Deletion analyses determined that the E-box1 and Sp1 regions play key roles in WGP-induced C4 transcription. Taken together, our results suggest that WGP promotes C4 biosynthesis through upregulation of transcription. These results provide new explanation for the intrinsic mechanism by which ginseng boosts human immune capacity.