Inhibition of PI3K/Akt/NF-κB signaling with leonurine for ameliorating the progression of osteoarthritis: In vitro and in vivo studies

Research progress on pharmacokinetics, anti-inflammatory and immunomodulatory effects of kaempferol

Chronic inflammation (an abnormal state) and autoimmune disease (AD) can both cause multiple organ damage. AD is a heterogeneous group of diseases due to immune dysfunction. Chronic inflammation is closely related to AD and is an important part of AD. With the increasing prevalence of AD, researchers are constantly exploring new drugs with small side effects, considerable curative effects, and lower costs. Kaempferol, a flavonoid, possesses a range of biological functions, including antioxidant, anti-inflammatory, anti-neoplastic, and immunomodulatory capabilities. This compound is prevalent in a variety of plant sources, such as vegetables, fruits, and medicinal herbs traditionally used in Chinese medicine. A plethora of empirical evidence from animal-based research supports the assertion that this particular substance exhibits both anti-inflammatory and immunomodulatory effects, with the curative effect being significant and application prospects. This article mainly summarizes and discusses the pharmacokinetics, drug delivery system, and the mechanism of kaempferol on immune cells, cytokines, signaling pathways, and other aspects. This paper summarizes the existing kaempferol drug delivery system, analyzes the possibility and limitations of kaempferol as a new anti-inflammatory and immunomodulatory drug, and discusses how to apply it in clinical practice. Therefore, kaempferol can more effectively exert its anti-inflammatory and immune-modulating effects, thereby demonstrating therapeutic potential in clinical settings, while reducing patient burden.

Notopterol mitigates osteoarthritis progression and relieves pain in mice by inhibiting PI3K/Akt/GPX4-mediated ferroptosis

Ferroptosis-induced lipid peroxidation in chondrocytes exacerbates intra-articular inflammation, oxidative stress, and articular cartilage degradation, accelerating osteoarthritis (OA) progression. Effective anti-inflammatory and antioxidant interventions can alleviate both joint pain and cartilage damage. This study aims to elucidate the therapeutic effects of Notopterol (NP), a bioactive compound extracted from the rhizome of Notopterygium incisum, a traditional Chinese medicine known for its potent anti-inflammatory and antioxidant properties, in treating OA. An in vivo mouse model of OA was established through medial meniscus destabilization (DMM). Intra-articular injections of NP over a 4-week treatment period significantly alleviated pain and gait abnormalities, reduced subchondral osteosclerosis, and attenuated cartilage degradation compared to the untreated DMM group. In vitro, chondrocytes treated with IL-1β to simulate OA conditions exhibited increased viability following NP pretreatment, with concurrent reductions in apoptosis, reactive oxygen species (ROS) accumulation, and chondrocyte catabolic dysfunction, along with enhanced extracellular matrix (ECM) synthesis. Mechanistically, NP exerts its anti-OA effects by inhibiting PI3K/Akt phosphorylation, suppressing ferroptosis, and improving antioxidant defense via upregulation of glutathione (GSH) and glutathione peroxidase 4 (GPX4), thereby preventing lipid peroxidation. In conclusion, NP modulates the PI3K/Akt/GPX4 axis to protect against lipid peroxidation, inhibit ferroptosis, and preserve cartilage integrity, thus delaying OA progression.

Yiqi Juanshen decoction alleviates renal interstitial fibrosis by targeting the LOXL2/PI3K/AKT pathway to suppress EMT and inflammation

Chronic kidney disease (CKD) is a major health concern, with renal interstitial fibrosis (RIF) as a key feature. Effective management of RIF is crucial for treating CKD. Yiqi Juanshen decoction (YQJSD), as traditional Chinese medicine, has shown promising results in CKD treatment. This study evaluates YQJSD's effectiveness in ameliorating RIF and explores the underlying molecular mechanisms using the unilateral ureteral obstruction (UUO) model. YQJSD has been shown to effectively reduce serum creatinine and blood urea nitrogen levels, decrease extracellular matrix deposition, and down-regulate the expression of α-SMA, COL4α1, Fibronectin (FN). Mechanistically, YQJSD exerts its effects by modulating multiple pathways: it inhibits the NF-κB signaling pathway, inhibiting the expression of pro-inflammatory cytokines like NF-κB1, IL-1β, TNF-α, and CCR1. Simultaneously, YQJSD suppresses the epithelial-mesenchymal transition (EMT) by downregulating the expression of Snail1, Vimentin, Twist1, and FSP1, while increasing E-cadherin expression. Moreover, YQJSD can regulate the PI3K/AKT signaling pathway by decreasing the expression of LOXL2 and PIK3R1, along with p-AKT1/2/3. This modulation of the LOXL2/PI3K/AKT pathway contributes to the inhibition of both EMT and inflammation, highlighting a critical role in the therapeutic intervention against RIF. These findings suggest that YQJSD may serve as a promising therapeutic management of RIF in CKD patients.

Osteoarthritis-like changes in rat temporomandibular joint induced by unilateral anterior large overjet treatment

Temporomandibular joint osteoarthritis (TMJOA) is a common degenerative disease that causes chronic pain and joint dysfunction. However, the current understanding of TMJOA pathogenesis is limited and necessitates further research. Animal models are crucial for investigating TMJOA due to the scarcity of clinical samples. Class II malocclusion is an occlusal type highly associated with TMJOA, but it currently lacks appropriate animal models for simulating this malocclusion in research. Therefore, this study develops a new malocclusion model using a unilateral anterior large overjet (UALO) dental device to cause Class II malocclusion characteristics and TMJOA-like pathological alterations in rats. By inducing a posteriorly positioned condyle, the UALO device effectively results in cartilage degradation, subchondral bone loss, condylar volume reduction, and mandibular retrusion. Furthermore, RNA sequencing of condylar cartilages revealed that the oxidative stress of chondrocytes was elevated under the UALO-triggered abnormal mechanical stress. Disruption of antioxidant systems and mitochondrial dysfunction are involved in cartilage degeneration. The current study provides a novel and reliable rat model suitable for TMJOA research and offers insights into the disease's potential mechanistic pathways and molecular targets, contributing to a deeper understanding of TMJOA.

An injectable hydrogel loaded with Icariin attenuates cartilage damage in rabbit knee osteoarthritis via Wnt/β-catenin signaling pathway

Knee osteoarthritis (KOA) is a chronic disease characterized by joint wear and cartilage degeneration. Current clinical treatments are based on symptomatic relief and are not effective in regenerating cartilage, and inflammation-induced cartilage damage accelerates the progression of osteoarthritis, making the protection of articular cartilage important for controlling the development of knee osteoarthritis. In this study, a biodegradable hydrogel (HA-Ca-Alg@Ica) loaded with Icariin (Ica) was prepared by in situ cross-linking of hyaluronic acid-calcium complex (HA-Ca) and sodium alginate (Alg-Na) for local sustained delivery of Ica. The hydrogel promoted chondrocyte proliferation and inhibited the degradation of cartilage matrix by regulating key factors (Wnt3a, β-catenin and GSK-3β) in the Wnt/β-catenin signaling pathway. In addition, the hydrogel reduced the expression of inflammatory factors, including IL-1β, IL-6, TNF-α, COX-2, and MMP13, leading to a reduction in inflammation and pain relief. In summary, this hydrogel containing Icariin has shown significant effects in reducing chondrocyte degradation and promoting chondrocyte proliferation, which can play a role in delaying osteoarthritis by protecting chondrocytes. These findings offer innovative prospects for the therapeutic management of knee osteoarthritis.

Kongensin A targeting PI3K attenuates inflammation-induced osteoarthritis by modulating macrophage polarization and alleviating inflammatory signaling

The inflammatory microenvironment, polarization of macrophages towards the M1 phenotype, and consequent matrix degradation and senescence of chondrocytes are primary contributors to the degeneration of knee joint cartilage, further exacerbating the progression of osteoarthritis (OA). Kongensin A (KA) is a recently identified natural plant extract exhibiting anti-necrotic apoptosis and anti-inflammatory properties, but the potential efficacy in alleviating OA remains uncertain. The current research lucubrated the effect of KA on the inflammatory microenvironment and macrophage polarization, as well as its regulatory function in extracellular matrix (ECM) metabolism and chondrocyte senescence. Our findings demonstrated that KA can suppress inflammatory signaling, maintain homeostasis between ECM anabolism and catabolism, and suppress chondrocytes senescence. Further investigation elucidated that the mechanism involves the suppression of the PI3K/AKT/NF-κB axis in chondrocytes under inflammatory conditions. Moreover, KA impeded M1 polarization of macrophages via inhibiting PI3K/AKT/NF-κB axis. Subsequently, we treated chondrocytes with macrophages-derived conditioned medium (CM) and revealed that KA can promote ECM anabolism and alleviate chondrocytes senescence by reprogramming macrophage polarization. Consistent with in vitro experiments, in vivo administration of KA demonstrated alleviated cartilage degeneration and delayed progression of OA. Collectively, through obstructing the PI3K/AKT/NF-κB axis, KA can reprogram macrophage polarization, promote matrix metabolism equilibrium, and alleviate chondrocytes senescence, thereby attenuating the pathology of OA. In conclusion, KA may emerge as a promising therapy for OA.

Esculin Alleviates Osteoarthritis Progression Through the Sirt1/NF-κB Pathway

Osteoarthritis (OA), a joint disease associated with inflammatory processes, contributes to joint destruction. Esculin (ESC) extracted from the stem bark of Fraxinus rhynchophylla Hance has been shown to possess anti-inflammatory properties. In this study, we investigated the effect of ESC on chondrocytes treated with IL-1β and its molecular mechanism. The importance and potential mechanism of ESC in the progression of OA were evaluated. The viability of chondrocytes after exposure to ESC was examined through the CCK-8 assays. The cells were then subjected to quantitative polymerase chain reaction (qPCR), western blot, and enzyme-linked immunosorbent assay (ELISA) techniques to analyze the degradation of the extracellular matrix (ECM) and occurrence of inflammation. The NF-κB mechanism was evaluated by western blot analysis, immunofluorescence (IF), and luciferase reporter assay. Molecular docking was performed to allow for predictions on proteins that interact with ESC. Moreover, the significance of Sirt1 was explored through a knockdown experiment based on siRNA. Micro-computed tomography (CT), H&E, Safranin O-Fast Green (S-O), and immunohistochemical analyses were carried out to assess the treatment efficacy of ESC on OA in destabilization of medial meniscus (DMM) models. ESC treatment effectively inhibited ECM degradation, modulated the levels of pro-inflammatory factors, and regulated the NF-κB signaling in chondrocytes exposed to IL-1β. Mechanistically, we found that ESCs bound to Sirt1 to inhibit the activity of the NF-κB mechanism. Furthermore, ESC treatment suppressed OA progression in the DMM models. Our findings reveal that ESC ameliorates OA progression via modulating the Sirt1/NF-κB axis. This demonstrates that ESC has the potential to be applied in the treatment of OA.

Inducers and Inhibitors of Pyroptotic Death of Granulosa Cells in Models of Premature Ovarian Insufficiency and Polycystic Ovary Syndrome

Granulosa cells (GCs), the largest cell population and primary source of steroid hormones in the ovary, are the important somatic ovarian components. They have critical roles in folliculogenesis by supporting oocyte, facilitating its growth, and providing a microenvironment suitable for follicular development and oocyte maturation, thus having essential functions in maintaining female fertility and in reproductive health in general. Pyroptotic death of GCs and associated inflammation have been implicated in the pathogenesis of several reproductive disorders in females including Premature Ovarian Insufficiency (POI) and Polycystic Ovary Syndrome (PCOS). Here, I reviewed factors, either intrinsic or extrinsic, that induce or inhibit pyroptosis in GCs in various models of these disorders, both in vitro and in vivo, and also covered associated molecular mechanisms. Most of these studied factors influence NLRP3 inflammasome- and GSDMD (Gasdermin D)-mediated pyroptosis in GCs, compared to other inflammasomes and gasdermins (GSDMs). I conclude that a more complete mechanistic understanding of these factors in terms of GC pyroptosis is required to be able to develop novel strategies targeting inflammatory cell death in the ovary.

The role of NF-κB-SOX9 signalling pathway in osteoarthritis

The nuclear factor-κB (NF-κB) signalling pathway exists in a variety of cells and is involved in the gene regulation of various physiological and pathological processes such as inflammation, immunity, cell proliferation and apoptosis. It has been shown that this signaling pathway is also involved in numerous events associated with osteoarthritis, including chondrocyte catabolism, chondrocyte survival, and synovial inflammation. SRY-related high mobility group-box 9(SOX9) is the "master regulator" of chondrocytes and one of the key transcription factors that maintain chondrocyte phenotype and cartilage homeostasis. NF-κB can positively regulate the expression of SOX9 by directly binding to its promoter region, and play a role in the formation and development of chondrocytes. This article reviews the regulatory effect of the NF-κB-SOX9 signaling axis on osteoarthritis.

Leonurine: a comprehensive review of pharmacokinetics, pharmacodynamics, and toxicology

Leonurine is an alkaloid unique to the Leonurus genus, which has many biological activities, such as uterine contraction, anti-inflammation, anti-oxidation, regulation of cell apoptosis, anti-tumor, angiogenesis, anti-platelet aggregation, and inhibition of vasoconstriction. This paper summarizes the extraction methods, synthetic pathways, biosynthetic mechanisms, pharmacokinetic properties, pharmacological effects in various diseases, toxicology, and clinical trials of leonurine. To facilitate a successful transition into clinical application, intensified efforts are required in several key areas: structural modifications of leonurine to optimize its properties, comprehensive pharmacokinetic assessments to understand its behavior within the body, thorough mechanistic studies to elucidate how it works at the molecular level, rigorous safety evaluations and toxicological investigations to ensure patient wellbeing, and meticulously conducted clinical trials to validate its efficacy and safety profile.

Scutellarein alleviates osteoarthritis progression through the PI3K/Akt/NF-kappaB signaling pathway: In vitro and in vivo studies

Osteoarthritis (OA), a joint disease that is associated with inflammatory processes is involved in joint destruction. Scutellarein (Scu), a component of the medicinal herbs Scutellaria barbata D. Don and Erigeron breviscapus (vant) Hand Mass, has anti-inflammatory effects. We explored the role of Scu in the development of OA and the underlying mechanisms. CCK-8 assays, Calcein-AM/PI and EdU staining were used to determine chondrocyte viability after Scu exposure. Western blot, qPCR, as well as ELISA were utilized to measure extracellular matrix (ECM) degradation and inflammation. Immunofluorescence (IF), western blot and luciferase assays were used to examine the NF-kappaB (NF-κB) pathway. Scu interacting proteins were predicted using network pharmacology analysis and molecular docking. X-ray, H&E, Safranin O-Fast Green(S-O), toluidine blue, and immunohistochemistry analysis were used to examine the therapeutic effects of Scu in OA using destabilization of medial meniscus (DMM) models. Scu demonstrated inhibitory effects on ECM degradation and pro-inflammatory factor levels in chondrocytes treated with IL-1β. Mechanistically, Scu inhibited the IL-1β-induced activation of the PI3K/Akt/ NF-κB signaling pathway cascades. Furthermore, Scu has been shown to have significant binding capacities to PI3K. Additionally, Scu ameliorated the OA progression in DMM models. Our findings suggest that Scu may contribute to the amelioration of OA progression by targeting the PI3K/Akt/NF-κB signaling pathway, implying Scu possesses promising therapeutic potential for the treatment of OA.

Effects of endoplasmic reticulum stress on chondrocyte apoptosis via the PI3K/AKT signaling pathway

Chondrocytes undergo endoplasmic reticulum stress (ERS)-induced apoptosis under abnormal stimulation. However, the underlying molecular mechanism remains unclear. We investigated the regulatory effect of the PI3K/AKT signaling pathway on ERS and its effect on chondrocyte apoptosis. In addition, we established a unilateral anterior crossbite (UAC) model in rats to induce temporomandibular joint osteoarthritis (TMJOA). Chondrocytes were isolated from the temporomandibular joints and treated with lipopolysaccharide (LPS) in vitro. Protein expression of ERS and apoptosis markers (GRP78 and CASP12) was analyzed by immunohistochemistry and western blotting. The expression of GRP78, CASP12, p-PI3K, and p-AKT significantly increased in the UAC group. LY294002, a PI3K/AKT signaling pathway inhibitor, reduced the protein expression of GRP78, ATF4, CHOP, and CASP12, whereas 740 Y-P, an activation agent, elevated the expression of proteins GRP78, ATF4, CHOP, and CASP12. In the present study, UAC and LPS stimulation induced apoptosis of chondrocytes in the ERS pathway. Inhibition of the PI3K/AKT signaling pathway reduced ERS-induced chondrocyte apoptosis.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Cucurbitacin E reduces IL-1β-induced inflammation and cartilage degeneration by inhibiting the PI3K/Akt pathway in osteoarthritic chondrocytes

BACKGROUND

Osteoarthritis is a degenerative joint disease. Cartilage degeneration is the earliest and most important pathological change in osteoarthritis, and persistent inflammation is one of the driving factors of cartilage degeneration. Cucurbitacin E, an isolated compound in the Cucurbitacin family, has been shown to have anti-inflammatory effects, but its role and mechanism in osteoarthritic chondrocytes are unclear.

METHODS

For in vitro experiments, human chondrocytes were stimulated with IL-1β, and the expression of inflammatory genes was measured by Western blotting and qPCR. The expression of extracellular matrix proteins was evaluated by immunofluorescence staining, Western blotting and saffron staining. Differences in gene expression between cartilage from osteoarthritis patients and normal cartilage were analysed by bioinformatics methods, and the relationship between Cucurbitacin E and its target was analysed by a cellular thermal shift assay, molecular docking analysis and molecular dynamics simulation. For in vivo experiments, knee osteoarthritis was induced by DMM in C57BL/6 mouse knee joints, and the effect of Cucurbitacin E on knee joint degeneration was evaluated.

RESULTS

The in vitro experiments confirmed that Cucurbitacin E effectively inhibited the production of the inflammatory cytokine interleukin-1β(IL-1β) and cyclooxygenase-2 (COX-2) by IL-1β-stimulated chondrocytes and alleviates extracellular matrix degradation. The in vivo experiments demonstrated that Cucurbitacin E had a protective effect on the knee cartilage of C57BL/6 mice with medial meniscal instability in the osteoarthritis model. Mechanistically, bioinformatic analysis of the GSE114007 and GSE117999 datasets showed that the PI3K/AKT pathway was highly activated in osteoarthritis. Immunohistochemical analysis of PI3K/Akt signalling pathway proteins in pathological slices of human cartilage showed that the level of p-PI3K in patients with osteoarthritis was higher than that in the normal group. PI3K/Akt were upregulated in IL-1β-stimulated chondrocytes, and Cucurbitacin E intervention reversed this phenomenon. The cellular thermal shift assay, molecular docking analysis and molecular dynamics experiment showed that Cucurbitacin E had a strong binding affinity for the inhibitory target PI3K. SC79 activated Akt phosphorylation and reversed the effect of Cucurbitacin E on IL-1β-induced chondrocyte degeneration, demonstrating that Cucurbitacin E inhibits IL-1β-induced chondrocyte inflammation and degeneration by inhibiting the PI3K/AKT pathway.

CONCLUSION

Cucurbitacin E inhibits the activation of the PI3K/AKT pathway, thereby alleviating the progression of OA. In summary, we believe that Cucurbitacin E is a potential drug for the treatment of OA.

A literature review: mechanisms of antitumor pharmacological action of leonurine alkaloid

Leonurine refers to the desiccated aerial portion of a plant in the Labiatae family. The primary bioactive constituent of Leonurine is an alkaloid, Leonurine alkaloid (Leo), renowned for its substantial therapeutic efficacy in the treatment of gynecological disorders, in addition to its broad-spectrum antineoplastic capabilities. Over recent years, the pharmacodynamic mechanisms of Leo have garnered escalating scholarly interest. Leo exhibits its anticancer potential by means of an array of mechanisms, encompassing the inhibition of neoplastic cell proliferation, induction of both apoptosis and autophagy, and the containment of oncogenic cell invasion and migration. The key signal transduction pathways implicated in these processes include the Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL), the Phosphoinositide3-Kinase/Serine/Threonine Protein Kinase (PI3K/AKT), the Signal Transducer and Activator of Transcription 3 (STAT3), and the Mitogen-Activated Protein/Extracellular Signal-Regulated Kinase (MAP/ERK). This paper commences with an exploration of the principal oncogenic cellular behaviors influenced by Leo and the associated signal transduction pathways, thereby scrutinizing the mechanisms of Leo in the antineoplastic sequence of events. The intention is to offer theoretical reinforcement for the elucidation of more profound mechanisms underpinning Leo's anticancer potential and correlating pharmaceutical development.

Human umbilical cord mesenchymal stem cells-derived exosomes exert anti-inflammatory effects on osteoarthritis chondrocytes

Inflammation of chondrocytes plays a critical role in the occurrence and development of osteoarthritis (OA). Recent evidence indicated exosomes derived from mesenchymal stem cells (MSCs-Exos) exhibit excellent anti-inflammatory ability in many troublesome inflammatory diseases including OA. In the present study, we aimed to explore the role of human umbilical cord-derived MSCs-Exos (hUC-MSCs-Exos) in treating the inflammation of chondrocytes and its related mechanisms. Ultracentrifugation was applied to isolate hUC-MSCs-Exos from the culture supernatant of hUC-MSCs. Two OA-like in vitro inflammation models of human articular chondrocytes induced with interleukin 1β (IL-1β) and co-incubation with macrophage utilizing transwell cell culture inserts were both used to evaluate the anti-inflammatory effects of hUC-MSCs-Exos. The mRNA sequencing of chondrocytes after treatment and microRNA (miRNA) sequencing of hUC-MSCs-Exos were detected and analyzed for possible mechanism analysis. The results of the study confirmed that hUC-MSCs-Exos had a reversed effect of IL-1β on chondrocytes in the expression of collagen type II alpha 1 (COL2A1) and matrix metalloproteinase 13 (MMP13). The addition of hUC-MSCs-Exos to M1 macrophages in the upper chamber showed down-regulation of IL-1β and tumor necrosis factor α (TNF-α), up-regulation of IL-10 and arginase1 (ARG1), and reversed the gene and protein expression of COL2A1 and MMP13 of the chondrocytes seeded in the lower chamber. The results of this study confirmed the anti-inflammatory effects of hUC-MSCs-Exos in the human articular chondrocytes inflammation model. hUC-MSCs-Exos may be used as a potential cell-free treatment strategy for chondrocyte inflammation in OA.

Global research trends and hotspots of PI3K/Akt signaling pathway in the field of osteoarthritis: A bibliometric study

The phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway has gradually become a new target for the treatment of osteoarthritis (OA). Numerous studies of PI3K/Akt signaling in OA have been published in the past few years. By analyzing these research characteristics and qualities, we aimed to reveal the current research focus and emerging trends in PI3K/Akt signaling in OA. We searched the Web of Science database for relevant articles concerning the PI3K/Akt signaling pathway in OA published from inception to October 31, 2022. The following data were extracted: author name, article title, keywords, topic, publication country/region, institution, publication journal, journal impact factor, number of times cited, and H-index. VOSviewer and Excel 2019 were used to conduct the bibliometric study and visualize the analysis. A total of 374 publications were included in this study. In all selected articles, "orthopedics" was the dominant topic (252 of 374, 67.38%). The most productive year was 2021. Frontiers in Pharmacology published the most articles. The People's Republic of China has published the most articles worldwide. The top 5 keywords were "OA," "expression," "apoptosis," "chondrocytes," and "inflammation." The keywords "autophagy," "mitochondrial dysfunction," "inflammatory response," "cartilage degeneration," and "network pharmacology" have increased in recent years. Our study showed a growing trend in published articles related to the PI3K/Akt signaling pathway in OA. Inflammatory response, cartilage degeneration, and apoptosis remain central topics in the field. Research on autophagy, mitochondrial dysfunction, and network pharmacology is on the rise, and the focus on PI3K/Akt will continue to increase.

The p53/miR-29a-3p axis mediates the antifibrotic effect of leonurine on angiotensin II-stimulated rat cardiac fibroblasts

Overactivation of cardiac fibroblasts (CFs) is one of the main causes of myocardial fibrosis (MF), and inhibition of CF activation is a crucial strategy for MF therapy. A previous study by our group demonstrated that leonurine (LE) effectively inhibits collagen synthesis and myofibroblast generation originated from CFs, and eventually mitigates the progression of MF (where miR-29a-3p is likely to be a vital mediator). However, the underlying mechanisms involved in this process remain unknown. Thus, the present study aimed to investigate the precise role of miR-29a-3p in LE-treated CFs, and to elucidate the pharmacological effects of LE on MF. Neonatal rat CFs were isolated and stimulated by angiotensin II (Ang II) to mimic the pathological process of MF in vitro. The results show that LE distinctly inhibits collagen synthesis, as well as the proliferation, differentiation and migration of CFs, all of which could be induced by Ang II. In addition, LE promotes apoptosis in CFs under Ang II stimulation. During this process, the down-regulated expressions of miR-29a-3p and p53 are partly restored by LE. Either knockdown of miR-29a-3p or inhibition of p53 by PFT-α (a p53 inhibitor) blocks the antifibrotic effect of LE. Notably, PFT-α suppresses miR-29a-3p levels in CFs under both normal and Ang II-treated conditions. Furthermore, ChIP analysis confirmed that p53 is bound to the promoter region of miR-29a-3p, and directly regulates its expression. Overall, our study demonstrates that LE upregulates p53 and miR-29a-3p expression, and subsequently inhibits CF overactivation, suggesting that the p53/miR-29a-3p axis may play a crucial role in mediating the antifibrotic effect of LE against MF.

Protective effects of leonurine hydrochloride on pyroptosis in premature ovarian insufficiency via regulating NLRP3/GSDMD pathway

BACKGROUND

Premature ovarian insufficiency is common in clinically infertile patients. The NOD-like receptor family pyrin domain-containing 3 (NLRP3)/Gasdermin D (GSDMD) signaling pathway plays a key role in premature ovarian insufficiency. Leonurine (Leo) is one of the important active ingredients extracted from Leonurus japonicus Houttuyn, which can inhibit NLRP3 activation. However, whether leonurine hydrochloride plays a protective role in premature ovarian insufficiency through actions on NLRP3/GSDMD signaling is not yet known.

METHODS

After cyclophosphamide-induced premature ovarian insufficiency was established in female mice, Leo was injected intraperitoneally over four weeks to evaluate the ovarian function and anti-pyroptosis effects using the metrics of fertility, serum hormone level, ovary weight, follicle number, expression of NLRP3/GSDMD pathway-related proteins, and serum IL-18 and IL-1β levels.

RESULTS

Intraperitoneal administration of leonurine hydrochloride was found to significantly protect fertility and maintain both serum hormone levels and follicle number in mice with premature ovarian insufficiency. Mice treated with leonurine hydrochloride consistently resisted cyclophosphamide-induced ovarian damage by inhibiting the activation of NLRP3 inflammasome, Caspase-1 and GSDMD in both ovarian tissue and granulosa cells, which led to lower levels of IL-18 and IL-1β in the serum (p < 0.05, p < 0.01, p < 0.001).

CONCLUSION

Intraperitoneal administration of leonurine hydrochloride prevents cyclophosphamide-induced premature ovarian insufficiency in mice by inhibiting NLRP3/GSDMD-mediated pyroptosis.

Corynoline Alleviates Osteoarthritis Development via the Nrf2/NF-κB Pathway

Purpose

OA is a multifactorial joint disease in which inflammation plays a substantial role in the destruction of joints. Corynoline (COR), a component of Corydalis bungeana Turcz., has anti-inflammatory effects.

Materials and Methods

We evaluated the significance and potential mechanisms of COR in OA development. The viabilities of chondrocytic cells upon COR exposure were assessed by CCK-8 assays. Western blot, qPCR, and ELISA were used to assess extracellular matrix (ECM) degeneration and inflammation. The NF-κB pathway was evaluated by western blot and immunofluorescence (IF). Prediction of the interacting proteins of COR was done by molecular docking, while Nrf2 knockdown by siRNAs was performed to ascertain its significance. Micro-CT, H&E, Safranin O-Fast Green (S-O), toluidine blue staining, and immunohistochemical examination were conducted to assess the therapeutic effects of COR on OA in destabilization of medial meniscus (DMM) models.

Results

COR inhibited ECM degeneration and proinflammatory factor levels and modulated the NF-κB pathway in IL-1β-treated chondrocytes. Mechanistically, COR bound Nrf2 to downregulate the NF-κB pathway. Moreover, COR ameliorated the OA process in DMM models.

Conclusion

We suggest that COR ameliorates OA progress through the Nrf2/NF-κB axis, indicating COR may have a therapeutic potential for OA.

Leonurine Protects Bone Mesenchymal Stem Cells from Oxidative Stress by Activating Mitophagy through PI3K/Akt/mTOR Pathway

Osteoporosis bears an imbalance between bone formation and resorption, which is strongly related to oxidative stress. The function of leonurine on bone marrow-derived mesenchymal stem cells (BMSCs) under oxidative stress is still unclear. Therefore, this study was aimed at identifying the protective effect of leonurine on H₂O₂ stimulated rat BMSCs. We found that leonurine can alleviate cell apoptosis and promote the differentiation ability of rat BMSCs induced by oxidative stress at an appropriate concentration at 10 μM. Meanwhile, the intracellular ROS level and the level of the COX2 and NOX4 mRNA decreased after leonurine treatment in vitro. The ATP level and mitochondrial membrane potential were upregulated after leonurine treatment. The protein level of PINK1 and Parkin showed the same trend. The mitophage in rat BMSCs blocked by 3-MA was partially rescued by leonurine. Bioinformatics analysis and leonurine-protein coupling provides a strong direct combination between leonurine and the PI3K protein at the position of Asp841, Glu880, Val882. In conclusion, leonurine protects the proliferation and differentiation of BMSCs from oxidative stress by activating mitophagy, which depends on the PI3K/Akt/mTOR pathway. The results showed that leonurine may have potential usage in osteoporosis and bone defect repair in osteoporosis patients.

Fuzi decoction ameliorates pain and cartilage degeneration of osteoarthritic rats through PI3K-Akt signaling pathway and its clinical retrospective evidence

BACKGROUND

Osteoarthritis (OA) is a difficult disease but the clinic lacks effective therapy. As a classic formula of traditional Chinese medicine (TCM), Fuzi decoction (FZD) has been clinically applied for treating OA-related syndromes, but its anti-OA efficacy and mechanism remain unclear.

PURPOSE

To experimentally and clinically determine the anti-OA efficacy of FZD and clarify the underlying mechanism.

METHODS

UPLC/MS/MS was applied to identify the main components of FZD. A monoiodoacetate (MIA)-induced OA rat model was employed to evaluate the in vivo efficacy of FZD against OA, by using pain behavior assessment, histopathological observation, and immunohistochemical analysis. Primary rat chondrocytes were isolated to determine the in vitro effects of FZD by using cell viability assay, wound healing assay, and real-time PCR (qPCR) analysis on anabolic/catabolic mRNA expressions. RNA sequencing (RNA-seq) and network pharmacology analysis were conducted and the overlapping data were used to predict the mechanism of FZD, followed by verification with qPCR and Western blot assays. Finally, a retrospective analysis was performed to confirm FZD's efficacy and safety in OA patients.

RESULTS

The UPLC/MS/MS result showed that FZD contained atractylenolide I, benzoylhypaconitine, benzoylmesaconitine, benzoylaconitine, hypaconitine, mesaconitine, aconitine, lobetyolin, paeoniflorin, and pachymic acid. The in vivo data showed that FZD restored the cartilage degeneration in MIA-induced OA rats by ameliorating pain behavior parameters, recovering histopathological alterations, benefitting cartilage anabolism (up-regulating Col2 expression), and suppressing catabolism (down-regulating MMP13 and Col10 expressions). The in vitro data showed that FZD increased cell viability and wound healing capacity of chondrocytes, and restored the altered expressions of anabolic and catabolic genes of chondrocytes. The overlapping results of RNA-seq and network pharmacology analysis suggested that PI3K/Akt signaling mediated the anti-OA mechanism of FZD, which was verified by qPCR and Western blot experiments. Clinically, the anti-OA efficacy and safety of FZD were confirmed by the retrospective analysis on OA patients.

CONCLUSION

The scientific innovation of this study was the determination of anti-OA efficacy of FZD by experimental and clinical evidence and the discovery of its mechanism by integrated RNA-seq, network pharmacology, and molecular experiments, which suggests FZD as a promising TCM agency for OA treatment.

Mechanical Stimulation Protects Against Chondrocyte Pyroptosis Through Irisin-Induced Suppression of PI3K/Akt/NF-κB Signal Pathway in Osteoarthritis

Irisin, a myokine secreted by muscle during physical exercise, is known to have biological activities in different cell types. Chondrocyte inflammation and pyroptosis have been shown to play important roles in osteoarthritis (OA). In this study, we investigated the effects of exercise-induced irisin during different intensities of treadmill exercise in a rat OA model and the anti-inflammatory and antipyroptosis mechanism of irisin in OA chondrocytes. Forty-eight SD rats (n = 8) were randomly assigned to control (CG), OA (OAG), OA groups under different intensities of treadmill exercise (OAL, OAM, and OAH), OAM + irisin neutralizing antibodies group (OAM + irisin (NA)). The levels of irisin and the severity of OA between groups were detected using ELISA, histology, immunohistochemistry, X-ray and computed tomography and magnetic resonance imaging. The anti-inflammatory and antipyroptosis mechanisms of irisin were investigated in vitro in OA chondrocytes preincubated with recombinant irisin (0, 5, or 10 ng/ml) for 1 h before treatment with interleukin-1β (IL-1β) for 24 h mRNA and protein expression levels were determined using quantitative reverse transcription polymerase chain reaction, and western blot analyses. Morphological changes and cell death associated with pyroptosis were examined using transmission electron microscopy, flow cytometry and immunofluorescence. Moderate-intensity treadmill exercise increased the levels of irisin, exhibiting the best therapeutic effects on OA which could be suppressed by irisin neutralizing antibodies. Irisin not only recovered the expression of collagen II and attenuated that of MMP-13 and ADAMTS-5 in IL-1β-induced OA chondrocytes by inhibiting the PI3K/Akt/NF-κB signaling pathway, but also inhibited the activity of nod-like receptor protein-3 (NLRP3)/caspase-1, thus ameliorating pyroptosis in chondrocytes. In conclusion, moderate mechanical stimulation protects against chondrocyte pyroptosis through irisin-induced suppression of PI3K/Akt/NF-κB signal pathway in osteoarthritis.

Cartilage degeneration is associated with activation of the PI3K/AKT signaling pathway in a growing rat experimental model of developmental trochlear dysplasia

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Established a new experimental rat model of the developmental trochlear dysplasia;

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Using the macroscopic morphological and micro-CT to assess trochlear dysplasia;

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Using Histological staining to investigate the cartilage degradation of the model;

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Investigated the relationship of the PI3K/AKT signaling pathway with trochlear dysplasia cartilage degeneration;

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Using immunohistochemistry and qPCR to investigate the PI3K/AKT and the marker of the cartilage degeneration.

Introduction

Trochlear dysplasia is a commonly encountered lower extremity deformity in humans. However, the molecular mechanism of cartilage degeneration in trochlear dysplasia is unclear thus far.

Objectives

The PI3K/AKT signaling pathway is known to be important for regulating the pathophysiology of cartilage degeneration. The aim of this study was to investigate the relationship of the PI3K/AKT signaling pathway with trochlear dysplasia cartilage degeneration.

Methods

In total, 120 female Sprague-Dawley rats (4 weeks of age) were randomly separated into control and experimental groups. Distal femurs were isolated from the experimental group at 4, 8, and 12 weeks after surgery; they were isolated from the control group at the same time points. Micro-computed tomography and histological examination were performed to investigate trochlear anatomy and changes in trochlear cartilage. Subsequently, expression patterns of PI3K/AKT, TGFβ1, and ADAMTS-4 in cartilage were investigated by immunohistochemistry and quantitative polymerase chain reaction.

Results

In the experimental group, the trochlear dysplasia model was successfully established at 8 weeks after surgery. Moreover, cartilage degeneration was observed beginning at 8 weeks after surgery, with higher protein and mRNA expression levels of PI3K/AKT, TGFβ1, and ADAMTS-4, relative to the control group.

Conclusion

Patellar instability might lead to trochlear dysplasia in growing rats. Moreover, trochlear dysplasia may cause patellofemoral osteoarthritis; cartilage degeneration in trochlear dysplasia might be associated with activation of the PI3K/AKT signaling pathway. These results provide insights regarding the high incidence of osteoarthritis in patients with trochlear dysplasia. However, more research is needed to clarify the underlying mechanisms.

Biological and Cytoprotective Effect of Piper kadsura Ohwi against Hydrogen-Peroxide-Induced Oxidative Stress in Human SW1353 Cells

Oxidative stress plays a role in regulating a variety of physiological functions in living organisms and in the pathogenesis of articular cartilage diseases. Piper kadsura Ohwi is a traditional Chinese medicine that is used as a treatment for rheumatic pain, and the extracts have anti-inflammatory and antioxidant effects. However, there is still no study related to cell protection by P. kadsura. The P. kadsura extracts (PKE) were obtained by microwave-assisted extraction, liquid-liquid extraction, and column chromatography separation. The extracts could effectively scavenge free radicals in the antioxidant test, the EC₅₀ of extracts is approximately the same as vitamin C. PKE decreased the apoptosis of SW1353 cells treated with H₂O₂ and could upregulate the gene expression of antioxidant enzymes (SOD-2, GPx, and CAT) and the Bcl-2/Bax ratio, as well as regulate PARP, thus conferring resistance to H₂O₂ attack. PKE protects cells against apoptosis caused by free radicals through the three pathways of JNK, MEK/ERK, and p38 by treatment with MAPK inhibitor. The identified components of PKE were bicyclo [2.2.1] heptan-2-ol-1,7,7-trimethyl-,(1S-endo)-, alpha-humulene, and hydroxychavicol by gas chromatography–mass spectrometry.

Leonurine protects against ulcerative colitis by alleviating inflammation and modulating intestinal microflora in mouse models

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the colon. The aim of the present study was to explore the effects of leonurine (YMJ) on inflammation and intestinal microflora in colonic tissues of a dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mouse model. Mice were randomly divided into control (n=5), DSS (n=5, treated with DSS) and DSS+YMJ (n=5, treated with DSS and YMJ) groups. Body weight was recorded, disease activity index (DAI) was calculated, and colon histopathology was evaluated using hematoxylin and eosin staining. Serum interleukin (IL)-6, tumor necrosis factor-α (TNF-α) and IL-1β levels were examined using ELISA. Expression levels of nuclear factor-κB (p65) and phosphorylated (p)-p65 were evaluated via western blotting. 16S ribosomal RNA was extracted from mouse feces. Composition or abundance changes of intestinal microflora were analyzed. The results indicated that YMJ treatment (DSS+YMJ group) significantly increased body weight, reduced DAI scores and increased colon length in UC mouse models compared with those in the DSS group (P<0.05). YMJ significantly reduced inflammatory infiltration, significantly decreased serum TNF-α, IL-6 and IL-1β levels (P<0.05) and significantly downregulated the p-p65/p65 ratio compared with the DSS group (P<0.05). YMJ increased the quantity of the intestinal flora and improved intestinal microflora diversity in the mice of the DSS group. Specifically, YMJ partly regulated intestinal microflora in feces, including a reduction of Bifidobacterium, and an increase in Parasutterella and Ackermania. In conclusion, YMJ improved disease outcomes of the UC mice, reduced the levels of serum inflammatory factors and increased the ratio of beneficial bacteria in the intestinal tract.

Mitochondrial Targeting of Herbal Medicine in Chronic Kidney Disease

Chronic kidney disease (CKD) is a common progressive disease that is typically characterized by the permanent loss of nephrons and an eventual decline in glomerular filtration rate. CKD increases mortality and has a significant impact on the quality of life and the economy, which is becoming a major public health issue worldwide. Since current conventional-medicine treatment options for CKD are not satisfactory, many patients seek complementary and alternative medicine treatments including Traditional Chinese Medicine. Herbal medicine is often used to relieve symptoms of renal diseases in the clinic. The kidney is abundant in the number of mitochondria, which provide enough energy for renal function and metabolism. In recent years, a vital role for mitochondrial dysfunction has been suggested in CKD. Mitochondria have become a new target for the treatment of diseases. A growing number of studies have demonstrated herbal medicine could restore mitochondrial function and alleviate renal injury both in vivo and in vitro. In this review, we sum up the therapeutic effect of herbal medicine in CKD via targeting mitochondrial function. This implies future strategies in preventing CKD.

Activation of autophagy contributes to the protective effects of lycopene against oxidative stress-induced apoptosis in rat chondrocytes

Oxidative stress is commonly associated with osteoarthritis (OA). Lycopene (LYC), a natural carotenoid compound, is an effective antioxidant with potential cartilage-protecting actions. However, how it affects hydrogen peroxide (H₂ O₂ )-induced damage to the cartilage is unclear. In this study, an in vitro oxidative stress model was developed via treating primary chondrocytes with H₂ O₂ . Western blot, immunohistochemistry, and quantitative RT-PCR (qRT-PCR) were used to assess the levels of related factors. Reactive oxygen species (ROS) and apoptosis levels were analyzed by the use of appropriate probes and flow cytometry. The expression and activity of stress-specific enzymes (malondialdehyde, superoxide dismutase, and catalase) were also assessed. The role of autophagy was explored by using the inhibitor, 3-methyladenine (3-MA), as well as monodansylcadaverine staining, western blotting, and red fluorescent protein-green fluorescent protein-light chain 3 lentivirus infection. The result showed LYC exerted significant chondrocyte-protective effects, including reduced inflammation and chondrocyte degradation, increased chondrocyte proliferation, apoptosis inhibition, and reduced ROS production. LYC could effectively induce autophagy in the H₂ O₂ treatment group, and this effect could be attenuated by 3-MA. In terms of mechanism, LYC played a role in inhibiting MAPK and PI3K/Akt/NF-κB axis, which down-regulates levels of mTOR and had a potential therapeutic significance for cartilage degeneration.

Isovitexin Depresses Osteoarthritis Progression via the Nrf2/NF-κB Pathway: An in vitro Study

Purpose

Osteoarthritis (OA) is a multifactorial joint disease and inflammatory processes contribute to joint destruction. Isovitexin (IVX) is a flavone component found in passion flower, Cannabis and, and the palm that is known for its anti-inflammatory properties.

Materials and Methods

This study investigated in vitro the role and underlying mechanism used by IVX in its regulation of OA development. Effects of IVX on the viability of chondrocytes were measured by CCK-8 assays. The phenotypes of extracellular matrix (ECM) degeneration and inflammation were measured by qPCR, Western blot, and ELISA; and NF-κB pathway was detected by immunofluorescence and Western blot. Molecular docking was applied to predict the interacting protein of IVX, while Nrf2 was knocked down by siRNAs to confirm its role.

Results

We demonstrated that IVX suppressed ECM degeneration and suppressed pro-inflammatory factors in IL-1β-treated chondrocytes. Additionally, IVX impact on NF-κB signaling in IL-1β-exposed chondrocytic cells; Mechanistically, it was also demonstrated in molecular docking and knock down studies that IVX might bind to Nrf2 to suppress NF-κB pathway.

Conclusion

Our data suggest that IVX halts OA disease advancement through the Nrf2/NF-κB axis, suggesting a possibility of IVX as a target for OA therapy.

Leonurine Promotes the Osteoblast Differentiation of Rat BMSCs by Activation of Autophagy via the PI3K/Akt/mTOR Pathway

Background

Leonurine, a major bioactive component from Herba leonuri, has been shown to exhibit anti-inflammatory and antioxidant effects. The aim of this study was to investigate the effect of leonurine on bone marrow-derived mesenchymal stem cells (BMSCs) as a therapeutic approach for treating osteoporosis.

Materials and Methods

Rat bone marrow-derived mesenchymal stem cells (rBMSCs) were isolated from 4-weeks-old Sprague–Dawley rats. The cytocompatibility of leonurine on rBMSCs was tested via CCK-8 assays and flow cytometric analyses. The effects of leonurine on rBMSC osteogenic differentiation were analyzed via ALP staining, Alizarin red staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot. Additionally, autophagy-related markers were examined via qRT-PCR and Western blot analyses of rBMSCs during osteogenic differentiation with leonurine and with or without 3-methyladenine (3-MA) as an autophagic inhibitor. Finally, the PI3K/Akt/mTOR signaling pathway was evaluated during rBMSC osteogenesis.

Results

Leonurine at 2–100 μM promoted the proliferation of rBMSCs. ALP and Alizarin red staining results showed that 10 μM leonurine promoted rBMSC osteoblastic differentiation, which was consistent with the qRT-PCR and Western blot results. Compared with those of the control group, the mRNA and protein levels of Atg5, Atg7, and LC3 were upregulated in the rBMSCs upon leonurine treatment. Furthermore, leonurine rescued rBMSC autophagy after inhibition by 3-MA. Additionally, the PI3K/AKT/mTOR pathway was activated in rBMSCs upon leonurine treatment.

Conclusion

Leonurine promotes the osteoblast differentiation of rBMSCs by activating autophagy, which depends on the PI3K/Akt/mTOR pathway. Our results suggest that leonurine may be a potential treatment for osteoporosis.

Maltol prevents the progression of osteoarthritis by targeting PI3K/Akt/NF-κB pathway: In vitro and in vivo studies

Osteoarthritis (OA), a prevalent degenerative arthritis disease, principle characterized by the destruction of cartilage and associated with the inflammatory response. Maltol, a product formed during the processing of red ginseng (Panax ginseng, CA Meyer), has been reported to have the potential effect of anti-inflammatory. However, its specific mechanisms are not demonstrated. We investigated the protective effect of maltol in the progression of OA both in vitro and in vivo experiments. Human chondrocytes were pre-treated with maltol (0, 20, 40, 60 μM, 24 hours) and incubated with IL-1β (10 ng/mL, 24 hours) in vitro. Expression of PGE2, TNF-α and NO was measured by the ELISA and Griess reaction. The expression of iNOs, COX-2, aggrecan, ADAMTS-5, MMP-13, IκB-α, p65, P-AKT, AKT, PI3K and P-PI3K was analysed by Western blotting. The expression of collagen II and p65-active protein was detected by immunofluorescence. Moreover, the serious level of OA was evaluated by histological analysis in vivo. We identified that maltol could suppress the IL-1β-stimulated generation of PGE2 and NO. Besides, maltol not only suppressed the production of COX-2, iNOs, TNF-α, IL-6, ADAMTS-5, MMP-13, but also attenuated the degradation of collagen II and aggrecan. Furthermore, maltol remarkably suppressed the phosphorylation of PI3K/AKT and NF-κB induced by IL-1β in human OA chondrocytes. Moreover, maltol could block the cartilage destroy in OA mice in vivo. To date, all data indicate maltol is a potential therapeutic agent by inhibiting inflammatory response via the regulation of NF-κB signalling for OA.

Inhibition of PI3K/Akt/NF-κB signaling by Aloin for ameliorating the progression of osteoarthritis: In vitro and in vivo studies

Osteoarthritis (OA) is a progressive and degenerative joint disease. Aloin is a bitter and yellow-brown-coloured compound from the Aloe plant and is allowed for use in foods as a "natural flavour". In our study, we examined the protective effects of Aloin on the inhibition of OA development as well as its underlying mechanism in both in vitro and vivo experiments. In in-vitro experiments, the protective effect of aloin on the anabolism and catabolism of the extracellular matrix (ECM) induced by IL-1 β in chondrocytes by inhibiting the expression of pro-inflammatory factors, including TNF-α (p = 0.016), IL-6 (p = 0.006), iNOS (p = 0.001) and COX-2 (p = 0.006). Mechanistically, Aloin suppressed the IL-1β-induced activation of the PI3K/Akt/NF-κB signalling pathway cascades. Moreover, molecular docking studies demonstrated that Aloin bound strongly to PI3K. In vivo, Aloin ameliorated the OA process in the destabilization of the medial meniscus (DMM) model. In summary, our findings demonstrate that Aloin ameliorates the progression of OA via the PI3K/Akt/NF-κB signalling pathways, which supports Aloin as a promising therapeutic agent for the treatment of OA.

Huoxuezhitong capsule ameliorates MIA-induced osteoarthritis of rats through suppressing PI3K/ Akt/ NF-κB pathway

Huoxuezhitong capsule (HXZT, activating blood circulation and relieving pain capsule), has been applied for osteoarthritis since 1974. It consists of Angelica sinensis (Oliv.) Diels, Panax notoginseng (Burkill) F. H. Chen ex C. H., Boswellia sacra, Borneol, Eupolyphaga sinensis Walker, Pyritum. However, the direct effects of HXZT on osteoarthritis and the underlying mechanisms were poorly understood. In this study, we aimed to explore the analgesia effect of HXZT on MIA-induced osteoarthritis rat and the underlying mechanisms. The analgesia and anti-inflammatory effect of HXZT on osteoarthritis in vivo were tested by the arthritis model rats induced by monosodium iodoacetate (MIA).. Mechanistic studies confirmed that HXZT could inhibit the activation of NF-κB and down-regulate the mRNA expression of related inflammatory factors in LPS-induced RAW264.7 and ATDC5 cells. Furtherly, in LPS-induced RAW264.7 cells, HXZT could suppress NF-κB via inhibiting PI3K/Akt pathway. Taken together, HXZT capsule could ameliorate MIA-induced osteoarthritis of rats through suppressing PI3K/ Akt/ NF-κB pathway.

The PI3K/AKT/mTOR signaling pathway in osteoarthritis: a narrative review

Osteoarthritis (OA) is a complicated degenerative disease that affects whole joint tissue. Currently, apart from surgical approaches to treat late stage OA, effective treatments to reverse OA are not available. Thus, the mechanisms leading to OA, and more effective approaches to treat OA should be investigated. According to available evidence, the PI3K/AKT/mTOR signaling pathway is essential for normal metabolism of joint tissues, but is also involved in development of OA. To provide a wide viewpoint to roles of PI3K/AKT/mTOR signaling pathway in osteoarthritis, a comprehensive literature search was performed using PubMed terms 'PI3K OR AKT OR mTOR' and 'osteoarthritis'. This review highlights the role of PI3K/AKT/mTOR signaling in cartilage degradation, subchondral bone dysfunction, and synovial inflammation, and discusses how this signaling pathway affects development of the disease. We also summarize recent evidences of therapeutic approaches to treat OA by targeting the PI3K/AKT/mTOR pathway, and discuss potential challenges in developing these strategies for clinical treatment of OA.

Arctigenin prevents the progression of osteoarthritis by targeting PI3K/Akt/NF-κB axis: In vitro and in vivo studies

Osteoarthritis (OA), which is principally featured by progressive joint metabolic imbalance and subsequent degeneration of articular cartilage, is a common chronic joint disease. Arctigenin (ATG), a dietary phyto-oestrogen, has been described to have potent anti-inflammatory effects. Nevertheless, its protective effects on OA have not been clearly established. The target of our following study is to evaluate the protective effects of ATG on IL-1β-induced human OA chondrocytes and mouse OA model. Our results revealed that the ATG pre-treatment effectively decreases the level of pro-inflammatory mediators, such as prostaglandin E2 (PGE2), nitrous oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6 and tumour necrosis factor alpha (TNF-α) in IL-1β-induced human chondrocytes. In addition, ATG protects against the degradation of extracellular matrix (ECM) under the stimulation of IL-1β and the possible mechanism might be connected with the inactivation of phosphatidylinositol-3-kinase (PI3K)/Akt/nuclear factor-kappa B (NF-κB) axis. Furthermore, a powerful binding capacity between ATG and PI3K was also uncovered in our molecular docking research. Meanwhile, ATG may act as a protector on the mouse OA model. Collectively, all these findings suggest that ATG could be utilized as a promising therapeutic agent for the treatment of OA.

Putative functional variants of PI3K/AKT/mTOR pathway are associated with knee osteoarthritis susceptibility

BACKGROUND

Osteoarthritis (OA) is a degenerative musculoskeletal disease which causes joint deformity and pain and finally leads to limb dysfunction. Knee osteoarthritis (KOA) has the highest incidence among all kinds of OA. Strong evidence leads to the understanding that P13K/AKT/mTOR signaling is very important in cartilage degeneration.

METHODS

This research sought to understand the association between genetic variation of PI3K/AKT/mTOR genes and KOA susceptibility among Chinese population. All the genetic variants of PI3K/AKT/mTOR pathway were graded and selected using RegulomeDB database, and then, an association study including 278 osteoarthritis patients and 289 controls was conducted.

RESULTS

Finally, eight SNPs' genotypes' distributions and susceptibility to KOA were presented. AKT1 rs2498789 was associated with KOA susceptibility in dominate genetic model (AA + GA vs GG) after adjusted for BMI, age, and gender: OR = 1.46, 95% CI: 1.03-2.05, P = .03. PIK3CA rs7646409 was also associated with KOA susceptibility (TC vs TT) after adjusted for BMI, age, and gender: OR = 0.58, 95% CI: 0.36-0.93, P = .02. PIK3CA rs7646409 (TC vs TT) with KOA risk was more significant in age < 60 group (P for heterogeneity was .03). Risk score showed significant association with KOA susceptibility after cumulative analysis (OR = 2.45, 95% CI: 1.35-4.45, P = .003).

CONCLUSIONS

This study shows that genetic variation of PI3K/AKT/mTOR is associated with KOA susceptibility in Chinese Han population, indicating that PI3K/AKT/mTOR is very important in KOA pathogenesis.

Quercetin alleviates rat osteoarthritis by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages

Osteoarthritis (OA) is a progressive joint disorder that is primarily characterized by the degeneration and destruction of the articular cartilage. Cartilage matrix degradation, production of proinflammatory mediators, chondrocyte apoptosis and activation of macrophages in the synovial are involved in OA pathogenesis. Current non-surgical therapies for OA mainly aim at relieving pain but can barely alleviate the progression of OA. Quercetin, a naturally occurring flavonoid has shown potent anti-inflammatory effects, however, its effects and underlying mechanisms on OA have seldom been systematically illuminated. In this study, we explored the protective effects of quercetin on repairing OA-induced cartilage injuries and its possible mechanisms. In vitro, quercetin remarkably suppressed the expression of matrix degrading proteases and inflammatory mediators, meantime promoted the production of cartilage anabolic factors in interleukin-1β-induced (IL-1β) rat chondrocytes. In addition, quercetin exhibited anti-apoptotic effects by decreasing intracellular reactive oxygen species (ROS), restoring mitochondrial membrane potential (MMP) and inhibiting the Caspase-3 pathway in apoptotic rat chondrocytes. Moreover, quercetin induced M2 polarization of macrophages and upregulated the expression of transforming growth factor β (TGF-β) and insulin-like growth factor (IGF), which in turn created a pro-chondrogenic microenvironment for chondrocytes and promoted the synthesis of glycosaminoglycan (GAG) in chondrocytes. In vivo, intra-articular injection of quercetin alleviated the degradation of the cartilage and the apoptosis of chondrocytes in a rat OA model. Moreover, the expression of TGF-β1 and TGF-β2 in the synovial fluid and the ratio of M2 macrophages in the synovial membrane were elevated. In summary, our study proves that quercetin exerts chondroprotective effects by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages and creating a pro-chondrogenic environment for chondrocytes to enhance cartilage repair under OA environment. It is suggested that quercetin may serve as a potential drug for OA treatment.

Chondroprotective and antiarthritic effects of Daphnetin used in vitro and in vivo osteoarthritis models

AIMS

Daphnetin (DAP) is a traditional Chinese drug usually used to treat cardiovascular diseases. Studies have confirmed the anti-inflammatory, antioxidant, anti-bacterial and insecticidal, anti-tumor and neuro-protective effects of DAP. However, its anti-arthritic potential remains unexplored. The aim of this study is to investigate the in vitro and in vivo chondroprotective effects of DAP.

MAIN METHODS

The effect of DAP on primary rabbit chondrocytes was examined using recombinant human IL-1β for 24 h. For the in vivo studies, rabbits were randomly divided into groups: a normal control group and osteoarthritis (OA) groups. The OA groups received three different doses of DAP for 4 or 8 weeks. The anti-arthritic effect of DAP was assessed using histopathological examinations, qRT-PCR, western blotting and immunohistochemical analysis.

KEY FINDINGS

Both in vitro and in vivo results indicate that DAP exerts a protective effect against IL-1β in chondrocytes. In vitro, DAP inhibits the expression of IL-6, IL-12, MMP-3, MMP-9 and MMP-13, induced by IL-1β in rabbit chondrocytes, and stimulates the production of IL-10. The inhibitory effect of DAP on the MMPs is partially regulated by the inhibition of the PI3K/AKT, MAPK and NF-κB signaling pathways. The effect of DAP on OA may be attributed to the suppression of inflammatory factor secretion, chondrocyte apoptosis observed by the decrease in pro-apoptotic Caspase-3 and BAX, and the activation of anti-apoptotic BCL-2.

SIGNIFICANCE

DAP has a broad range of prospects in the treatment of OA, which provides a novel therapeutic strategy for OA.