Picroside II suppresses chondrocyte pyroptosis through MAPK/NF-κB/NLRP3 signaling pathway alleviates osteoarthritis

BACKGROUND

Picroside II (P-II) is the main bioactive constituent of Picrorhiza Kurroa, a traditional Chinese herb of interest for its proven anti-inflammatory properties. Its beneficial effects have been noted across several physiological systems, including the nervous, circulatory, and digestive, capable of treating a wide range of diseases. Nevertheless, the potential of Picroside II to treat osteoarthritis (OA) and the mechanisms behind its efficacy remain largely unexplored.

AIM

This study aims to evaluate the efficacy of Picroside II in the treatment of osteoarthritis and its potential molecular mechanisms.

METHODS

In vitro, we induced cellular inflammation in chondrocytes with lipopolysaccharide (LPS) and subsequently treated with Picroside II to assess protective effect on chondrocyte. We employed the Cell Counting Kit-8 (CCK-8) assay to assess the impact of Picroside II on cell viability and select the optimal Picroside II concentration for subsequent experiments. We explored the effect of Picroside II on chondrocyte pyroptosis and its underlying molecular mechanisms by qRT-PCR, Western blot (WB) and immunofluorescence. In vivo, we established the destabilization of the medial meniscus surgery to create an OA mouse model. The therapeutic effects of Picroside II were then assessed through Micro-CT scanning, Hematoxylin-eosin (H&E) staining, Safranin O-Fast Green (S&F) staining, immunohistochemistry and immunofluorescence.

RESULTS

In in vitro studies, toluidine blue and CCK-8 results showed that a certain concentration of Picroside II had a restorative effect on the viability of chondrocytes inhibited by LPS. Picroside II notably suppressed the expression levels of caspase-1, IL-18, and IL-1β, which consequently led to the reduction of pyroptosis. Moreover, Picroside II was shown to decrease NLRP3 inflammasome activation, via the MAPK/NF-κB signaling pathway. In vivo studies have shown that Picroside II can effectively reduce subchondral bone destruction and osteophyte formation in the knee joint of mice after DMM surgery.

CONCLUSIONS

Our research suggests that Picroside II can inhibit chondrocyte pyroptosis and ameliorate osteoarthritis progression by modulating the MAPK/NF-κB signaling pathway.

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).

The beneficial pharmacological effects and potential mechanisms of picroside II: Evidence of its benefits from in vitro and in vivo

Picrorhiza kurroa, the dried rhizome of Picrorhiza kurroa Royle ex Benth, is a famous Chinese herb that has been traditionally used in China. Picroside II (PII), a glycoside derivative, is the main bioactive constituent of Picrorhiza kurroa. In the past several decades, bioactive components from Picrorhiza kurroa have attracted the attention of researchers due to their promising therapeutic effects. A large number of studies have demonstrated the therapeutic potential of PII for the prevention and treatment of some diseases, such as organic ischemia/reperfusion (I/R) injury, liver damage, inflammation, cancer metastasis and angiogenesis. In the present paper, we aimed to provide an overview of the pharmacology of PII, focusing on its anti-oxidant, anti-inflammatory and anti-apoptotic activities. Meanwhile, the plant tissue distribution and pharmacokinetic properties were also described. Due to its beneficial pharmacological effects in I/R injury, PII may serve as a promising therapeutic agent for organic I/R injury prevention.

Integrin-associated molecules and signalling cross talking in osteoclast cytoskeleton regulation

In the ageing skeleton, the balance of bone reconstruction could commonly be broken by the increasing of bone resorption and decreasing of bone formation. Consequently, the bone resorption gradually occupies a dominant status. During this imbalance process, osteoclast is unique cell linage act the bone resorptive biological activity, which is a highly differentiated ultimate cell derived from monocyte/macrophage. The erosive function of osteoclasts is that they have to adhere the bone matrix and migrate along it, in which adhesive cytoskeleton recombination of osteoclast is essential. In that, the podosome is a membrane binding microdomain organelle, based on dynamic actin, which forms a cytoskeleton superstructure connected with the plasma membrane. Otherwise, as the main adhesive protein, integrin regulates the formation of podosome and cytoskeleton, which collaborates with the various molecules including: c-Cbl, p130^Cas , c-Src and Pyk2, through several signalling cascades cross talking, including: M-CSF and RANKL. In our current study, we discuss the role of integrin and associated molecules in osteoclastogenesis cytoskeletal, especially podosomes, regulation and relevant signalling cascades cross talking.

Chemical components, pharmacological actions, and clinical applications of Rhizoma Picrorhizae

Rhizoma Picrorhizae (RP) is a traditional Chinese medicine, which has always been used to treat many diseases like infantile epilepsy and malnutrition. In modern applications, it has been used to treat hepatitis B and various liver injuries with remarkable curative effects. So far, more than 90 chemical components have been reported in RP, mainly including iridoid glycosides, cucurbitacins, phenylethanoid glycosides, and phenolic glycosides. Among these, iridoid glycosides are the most important active ingredients, and about 30 such compounds have been isolated at present. In pharmacology, RP is beneficial to the choleresis, liver protection, anti-inflammation, asthma relief, immune regulation, and protection of heart, brain, kidney, and other organs. There have been many investigations on this medicinal herb in recent years, and it has attracted much attention in the medicine domain. In this paper, through systematically consulting the relevant books and electronic databases, we analyzed, arranged, and summarized the available information on this herb to provide reference for its further research.

Classic and Novel Signaling Pathways Involved in Cancer: Targeting the NF-κB and Syk Signaling Pathways

The nuclear factor kappa B (NF-κB) consists of a family of transcription factors involved in the regulation of a wide variety of biological responses. Growing evidence support that NF-κB plays a major role in oncogenesis as well as its well-known function in the regulation of immune responses and inflammation. Therefore, we made a review of the diverse molecular mechanisms by which the NF-κB pathway is constitutively activated in different types of human cancers and the potential role of various oncogenic genes regulated by this transcription factor in cancer development and progression. We also discussed various pharmacological approaches employed to target the deregulated NF-κB signaling pathway and their possible therapeutic potential in cancer therapy. Moreover, Syk (Spleen tyrosine kinase), non-receptor tyrosine kinase which mediates signal transduction downstream of a variety of transmembrane receptors including classical immune-receptors like the B-cell receptor (BCR), which can also activate the inflammasome and NF-κB-mediated transcription of chemokines and cytokines in the presence of pathogens would be discussed as well. The highlight of this review article is to summarize the classic and novel signaling pathways involved in NF-κB and Syk signaling and then raise some possibilities for cancer therapy.

Puerarin for OVX-Induced Postmenopausal Osteoporosis in Murine Model: Systematic Review and Meta-Analysis

AIMS/BACKGROUND

Ovariectomy (OVX)-induced murine model is widely used for postmenopausal osteoporosis study. Our current study was conducted to systematically review and essentially quantified the bone mass enhancing effect of puerarin on treating OVX-induced postmenopausal osteoporosis in murine model.

METHODS

Literatures from PUBMED, EMBASE, and CNKI were involved in our searching strategy by limited the inception date to January 9th, 2019. Moreover, the enhancing effect of puerarin on bone mass compared to OVX-induced rats is evaluated by four independent reviewers. Finally, all the data were extracted, quantified and analyzed via RevMan, besides that in our current review study, we assessed the methodological quality for each involved study.

RESULTS

Based on the searching strategy, eight randomization studies were finally included in current meta-analysis and systematic review. According to the data analysis by RevMan, puerarin could improve bone mineral density (BMD); (eight studies, n=203; weighted mean difference, 0.05; 95% CI, 0.03-0.07; P<0.0001) using a random-effects model. There is no significant difference between puerarin and estrogen (seven studies, n=184; weighted mean difference, 0.00; 95% CI, -0.01 to 0.00; P=0.30).

CONCLUSION

Puerarin showed upregulating effects on bone mass in OVX-induced postmenopausal osteoporosis in murine model. More studies of the effect of puerarin on bone density in OVX animals are needed.

Magnolol prevents ovariectomy‑induced bone loss by suppressing osteoclastogenesis via inhibition of the nuclear factor‑κB and mitogen‑activated protein kinase pathways

Magnolol is the active component of the traditional Chinese medicine Magnolia officinalis, and has antioxidant, anti-inflammatory and anticancer activities, as well as an effect on bone metabolism in vitro. In the present study, it is reported that magnolol suppresses osteoclastogenesis in vivo and in vitro. Magnolol prevented ovariectomy-induced bone loss and osteoclastogenesis in vivo, and decreased the serum levels of C-terminal telopeptide of type 1 collagen, interleukin-6, tumor necrosis factor (TNF)-α and tartrate-resistant acid phosphatase 5B. In vitro, magnolol inhibited the osteoclastogenesis induced by the receptor activator for nuclear factor-κB ligand, and impaired the osteoclast function in bone marrow monocytes and RAW264.7 cells in a dose-dependent manner. Furthermore, magnolol suppressed the expression levels of the osteoclastogenesis markers cathepsin K, calcitonin receptor, matrix metalloproteinase 9, TNF receptor-associated factor 6 and tartrate-resistant acid phosphatase by inhibiting the nuclear factor-κB and mitogen-activated protein kinase pathways. Therefore, magnolol is a promising agent for the treatment of osteoporosis and associated disorders.

Regulation effects of melatonin on bone marrow mesenchymal stem cell differentiation

Melatonin's therapeutic potential has been highly underestimated because its biological functional roles are diverse and relevant mechanisms are complicated. Among the numerous biological activities of melatonin, its regulatory effects on pluripotent mesenchymal stem cells (MSCs), which are found in bone marrow stem cells (BMSCs) and adipose tissue (AD-MSC), have been recently proposed, which has received increasingly more attention in recent studies. Moreover, receptor-dependent and receptor-independent responses to melatonin are identified to occur in these cells by regulating signaling pathways, which drive the commitment and differentiation of MSCs into osteogenic, chondrogenic, or adipogenic lineages. Therefore, the aim of our current review is to summarize the evidence related to the utility of melatonin as a regulatory agent by focusing on its relationship with the differentiation of MSCs. In particular, we aimed to review its roles in promoting osteogenic and chondrogenic differentiation and the relevant signaling cascades involved. Also, the roles that melatonin and, particularly, its receptors play in these processes are highlighted.

Inhibition effects of a natural inhibitor on RANKL downstream cellular signalling cascades cross-talking

Myricitrin is a natural occurring flavonoid glycoside that possesses effects on inhibiting nitric oxide (NO) transmission and preventing inflammatory reaction. Although previous study showed the myricitrin possesses antibone loss effects via reducing the expression of IL-6 and partially suppressing reactive oxygen species (ROS) production. However, the effects of myricitrin on nuclear factor-kappaB ligand (RANKL)-stimulated osteoclastogenesis have not yet been further investigated. The current study was aimed to demonstrating the inhibitory effects of myricitrin on RANKL-stimulated osteoclastogenesis and relevant mechanisms. We found myricitrin significantly suppressed osteoclastogenesis suggesting that it may acts on RANKL/RANK induced downstream signal cross cascading in osteoclast precursors. In that, our Western blotting results showed myricitrin significantly attenuated RNAKL/MAPKs (phosphorylation of p38, ERK, JNK) and AKT signal cascading. Complementing previous study, our results suggesting as a natural inhibitor, myricitrin possesses the potential therapeutic effects on inflammatory osteolysis.

Vaccaria hypaphorine impairs RANKL-induced osteoclastogenesis by inhibition of ERK, p38, JNK and NF-κB pathway and prevents inflammatory bone loss in mice

Osteoclasts are sole bone-resorbing cells which exert a profound effect on skeletal metabolism. The search for medicines that affect the differentiation and function of osteoclasts is crucial in developing therapies for osteoclast-based diseases. Vaccaria hypaphorine, the main active compound of the traditionally used Chinese herb Vaccaria segetalis, has anti-inflammatory activity. The present study demonstrated for the first time that vaccaria hypaphorine could significantly inhibit the receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastic differentiation in vitro and alleviate lipopolysaccharide (LPS)-induced bone loss in vivo. Further study showed that vaccaria hypaphorine decreased osteoclastogenesis in a dose-dependent manner. Furthermore, vaccaria hypaphorine was confirmed to inhibit osteoclasts differentiation at early stage but not at later stage. Pit formation assay and F-actin ring staining showed that vaccaria hypaphorine inhibited the bone-resorbing activity of osteoclasts. Mechanistically, vaccaria hypaphorine impaired RANKL-induced osteoclastogenesis through reduction of extracellular signal-regulated kinases (ERK), p38, c-Jun N-terminal kinase (JNK) and NF-κB p65 phosphorylation. Taken together, our results provided evidences that vaccaria hypaphorine might be considered as potential therapeutic agent for treating osteoclast-based bone loss.