Maslinic acid prevents IL-1β-induced inflammatory response in osteoarthritis via PI3K/AKT/NF-κB pathways

Maslinic acid alleviates intervertebral disc degeneration by inhibiting the PI3K/AKT and NF-κB signaling pathways

Intervertebral disc degeneration (IDD) is the cause of low back pain (LBP), and recent research has suggested that inflammatory cytokines play a significant role in this process. Maslinic acid (MA), a natural compound found in olive plants ( Olea europaea), has anti-inflammatory properties, but its potential for treating IDD is unclear. The current study aims to investigate the effects of MA on TNFα-induced IDD in vitro and in other in vivo models. Our findings suggest that MA ameliorates the imbalance of the extracellular matrix (ECM) and mitigates senescence by upregulating aggrecan and collagen II levels as well as downregulating MMP and ADAMTS levels in nucleus pulposus cells (NPCs). It can also impede the progression of IDD in rats. We further find that MA significantly affects the PI3K/AKT and NF-κB pathways in TNFα-induced NPCs determined by RNA-seq and experimental verification, while the AKT agonist Sc-79 eliminates these signaling cascades. Furthermore, molecular docking simulation shows that MA directly binds to PI3K. Dysfunction of the PI3K/AKT pathway and ECM metabolism has also been confirmed in clinical specimens of degenerated nucleus pulposus. This study demonstrates that MA may hold promise as a therapeutic agent for alleviating ECM metabolism disorders and senescence to treat IDD.

Emerging technology has a brilliant future: the CRISPR-Cas system for senescence, inflammation, and cartilage repair in osteoarthritis

Osteoarthritis (OA), known as one of the most common types of aseptic inflammation of the musculoskeletal system, is characterized by chronic pain and whole-joint lesions. With cellular and molecular changes including senescence, inflammatory alterations, and subsequent cartilage defects, OA eventually leads to a series of adverse outcomes such as pain and disability. CRISPR-Cas-related technology has been proposed and explored as a gene therapy, offering potential gene-editing tools that are in the spotlight. Considering the genetic and multigene regulatory mechanisms of OA, we systematically review current studies on CRISPR-Cas technology for improving OA in terms of senescence, inflammation, and cartilage damage and summarize various strategies for delivering CRISPR products, hoping to provide a new perspective for the treatment of OA by taking advantage of CRISPR technology.

Protective effects of ectoine on articular chondrocytes and cartilage in rats for treating osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease that primarily includes articular cartilage destruction and inflammatory reactions, and effective treatments for this disease are still lacking. The present study aimed to explore the protective effects of ectoine, a compatible solute found in nature, on chondrocytes in rats and its possible application in OA treatment. In the in vitro studies, the morphology of the chondrocytes after trypsin digestion for 2 min and the viability of the chondrocytes at 50°C were observed after ectoine treatment. The reactive oxygen species (ROS) levels in chondrocytes pretreated with ectoine and post-stimulated with H2O2 were detected using an ROS assay. Chondrocytes were pretreated with ectoine before IL-1β stimulation. RT‒qPCR was used to measure the mRNA levels of cyclooxygenase-2 (COX-2), metallomatrix proteinase-3, -9 (MMP-3, -9), and collagen type II alpha 1 (Col2A1). In addition, immunofluorescence was used to assess the expression of type II collagen. The in vivo effect of ectoine was evaluated in a rat OA model induced by the modified Hulth method. The findings revealed that ectoine significantly increased the trypsin tolerance of chondrocytes, maintained the viability of the chondrocytes at 50°C, and improved their resistance to oxidation. Compared with IL-1β treatment alone, ectoine pretreatment significantly reduced COX-2, MMP-3, and MMP-9 expression and maintained type II collagen synthesis in chondrocytes. In vivo, the cartilage of ectoine-treated rats exhibited less degeneration and lower Osteoarthritis Research Society International (OARSI) scores. The results of this study suggest that ectoine exerts protective effects on chondrocytes and cartilage and can, therefore, be used as a potential therapeutic agent in the treatment of OA.

Ubiquitin-specific peptidase 25 exacerbated osteoarthritis progression through facilitating TXNIP ubiquitination and NLRP3 inflammasome activation

Several members of the ubiquitin-specific proteases (USPs) family have been revealed to regulate the progression of osteoarthritis (OA). The current study aimed to investigate the role and the underlying mechanism of USP25 in IL-1β-induced chondrocytes and OA rat model. It was discovered that IL-1β stimulation upregulated USP25, increased ROS level, and suppressed cell viability in rat chondrocytes. Besides, USP25 knockdown alleviated IL-1β-induced injury by decreasing ROS level, attenuating pyroptosis, and downregulating the expression of IL-18, NLRP3, GSDMD-N, active caspase-1, MMP-3, and MMP-13. Furthermore, we discovered that USP25 affected the IL-1β-induced injury in chondrocytes in a ROS-dependent manner. Moreover, USP25 was revealed to interact with TXNIP, and USP25 knockdown increased the ubiquitination of TXNIP. The pro-OA effect of USP25 abundance could be overturned by TXNIP suppression in IL-1β-induced chondrocytes. Finally, in vivo experiment results showed that USP25 inhibition alleviated cartilage destruction in OA rats. In conclusion, we demonstrated that USP25 stimulated the overproduction of ROS to activate the NLRP3 inflammasome via regulating TXNIP, resulting in increased pyroptosis and inflammation in OA.

Extracellular matrix in synovium development, homeostasis and arthritis disease

Extracellular matrix (ECM) is a three-dimensional network entity composed of extracellular macromolecules. ECM in synovium not only supports the structural integrity of synovium, but also plays a crucial role in regulating homeostasis and damage repair response in synovium. Obvious disorders in the composition, behavior and function of synovial ECM will lead to the occurrence and development of arthritis diseases such as rheumatoid arthritis (RA), osteoarthritis (OA) and psoriatic arthritis (PsA). Based on the importance of synovial ECM, targeted regulation of the composition and structure of ECM is considered to be an effective measure for the treatment of arthritis disease. This paper reviews the current research status of synovial ECM biology, discusses the role and mechanism of synovial ECM in physiological status and arthritis disease, and summarizes the current strategies for targeting synovial ECM to provide information for the pathogenesis, diagnosis and treatment of arthritis disease.

Maslinic acid attenuates UVB-induced oxidative damage in HFF-1 cells

BACKGROUND

Oxidative damage is one of the major mechanisms of ultraviolet B (UVB)-induced damage to the skin. Maslinic acid (MA) is a natural compound of pentacyclic triterpene acids. It has been proved to have anti-inflammatory and antioxidant properties.

OBJECTIVE

This study aimed to explore the effects of MA on oxidative damage in human foreskin fibroblast cells (HFF-1) and the potential molecular mechanisms.

METHODS

A specific dose of UVB radiation was used to induce oxidative damage in HFF-1. Based on this, we performed measurements of cell proliferation, reactive oxygen species (ROS) levels, antioxidant enzyme activity, inflammation-related mediators, and NF-κB nuclear localization with or without the addition of MA.

RESULTS

MA significantly promoted cell proliferation viability at 10 and 20 μM. The addition of MA 24 h before UVB irradiation was more effective at enhancing cell proliferation and also produced lower ROS levels compared to co-cultured fibroblasts and MA for 24 h after irradiation. However, there was no statistically significant difference between groups at concentrations of 10 and 20 μM. The pretreatment group with MA had elevated superoxide dismutase and catalase activities, decreased IL-6 generation, and lowered mRNA levels of IL-6, TNF-α and MMP3 in comparison with the UVB-irradiated group without additional MA. Meanwhile, the nuclear translocation of NF-κB and the degradation of IκB were inhibited by MA pretreatment.

CONCLUSION

Taken together, these findings suggest that MA may alleviate UVB-induced oxidative damage in HFF-1 by inhibiting the nuclear translocation of NF-κB.

Maslinic Acid Supplementation during the In Vitro Culture Period Ameliorates Early Embryonic Development of Porcine Embryos by Regulating Oxidative Stress

As a pentacyclic triterpene, MA exhibits effective free radical scavenging capabilities. The purpose of this study was to explore the effects of MA on porcine early-stage embryonic development, oxidation resistance and mitochondrial function. Our results showed that 1 μM was the optimal concentration of MA, which resulted in dramatically increased blastocyst formation rates and improvement of blastocyst quality of in vitro-derived embryos from parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). Further analysis indicated that MA supplementation not only significantly decreased the abundance of intracellular reactive oxygen species (ROS) and dramatically increased the abundance of intracellular reductive glutathione (GSH) in porcine early-stage embryos, but also clearly attenuated mitochondrial dysfunction and inhibited apoptosis. Moreover, Western blotting showed that MA supplementation upregulated OCT4 (p < 0.01), SOD1 (p < 0.0001) and CAT (p < 0.05) protein expression in porcine early-stage embryos. Collectively, our data reveal that MA supplementation exerts helpful effects on porcine early embryo development competence via regulation of oxidative stress (OS) and amelioration of mitochondrial function and that MA may be useful for increasing the in vitro production (IVP) efficiency of porcine early-stage embryos.

Urolithin A (UA) attenuates ferroptosis in LPS-induced acute lung injury in mice by upregulating Keap1-Nrf2/HO-1 signaling pathway

Acute lung injury (ALI) is a life-threatening disease with high incidence and mortality rates. Urolithin A (UA) is a pomegranate intestinal flora metabolite with anti-inflammatory, antioxidant, and anti-aging properties. Ferroptosis is a critical factor in lipopolysaccharide (LPS)-induced acute lung injury (ALI). However, the link between UA and ferroptosis is unknown. The purpose of this research was to look into the role of UA in regulating LPS-induced ferroptosis in ALI. The current study used LPS to injure two models, one BEAS-2B cell injury model and one ALI mouse model. UA effectively alleviated LPS-induced ALI compared to the LPS group by lowering in vivo lung wet/dry weight ratio, reactive oxygen species, and malondialdehyde production, as well as superoxide dismutase, catalase, and glutathione depletion. Furthermore, by increasing GPX4 and SLC7A11 expression and decreasing Fe2+ levels, lung histopathological damage, inflammatory cytokine secretion, and ferroptosis levels can be significantly reduced. The Keap1-Nrf2/HO-1 pathway was upregulated by UA, which inhibited LPS-induced ALI and ferroptosis. ML385 inhibited UA’s protective effect against LPS-induced ALI. These findings suggested that UA could be a novel potential therapeutic target for ALI.

Exercise induced meteorin-like protects chondrocytes against inflammation and pyroptosis in osteoarthritis by inhibiting PI3K/Akt/NF-κB and NLRP3/caspase-1/GSDMD signaling

The production of metrnl, a novel adipomyokine, is induced upon exercise in adipose tissue and skeletal muscle. In this study, we investigated the anti-inflammatory and antipyroptotic effects of exercise-induced metrnl producted in rats in vitro and in vivo. Forty Sprague-Dawley rats were divided randomly into five groups: control (CG), osteoarthritis (OA) with sedentary lifestyle (OAG), OA with low intensity exercise (OAL), OA with moderate intensity exercise (OAM), and OA with high intensity exercise (OAH). The correlation between the level of metrnl and OA degree was detected using ELISA, X-ray imaging, histology, and immunohistochemistry in vivo. Primary chondrocytes were preincubated with recombinant metrnl before interleukin-1β administration to verify the anti-inflammatory and antipyroptotic effects of metrnl. Western blotting and quantitative reverse transcription (qRT)-PCR were used to evaluate the differences in protein and mRNA expression between groups, respectively. Reactive oxygen species (ROS) assay, immunofluorescence, transmission electron microscopy (TEM), and flow cytometry were used to evaluate morphological changes and pyroptosis in chondrocytes. In the moderate-intensity treadmill exercise group, the severity of OA showed maximum relief and the metrnl levels had the most significant increase. Metrnl exerted its anti-inflammatory effect through the suppression of the PI3K/Akt/NF-κB pathway in IL-1β-induced OA chondrocytes, which was accompanied with the recovery of collagen II expression and the attenuation of MMP13 and ADAMTS5. Moreover, metrnl ameliorated chondrocyte pyroptosis by inhibiting the activation of the nod-like receptor protein-3/caspase-1/gasdermin D cascade. In conclusion, moderate-intensity exercise improves inflammation and pyroptosis by increasing metrnl release, which inhibits the PI3K/Akt/NF-κB and further NLRP3/caspase-1/GSDMD signaling pathways.

Maslinic Acid: A New Compound for the Treatment of Multiple Organ Diseases

Maslinic acid (MA) is a pentacyclic triterpene acid, which exists in many plants, including olive, and is highly safe for human beings. In recent years, it has been reported that MA has anti-inflammatory, antioxidant, anti-tumor, hypoglycemic, neuroprotective and other biological activities. More and more experimental data has shown that MA has a good therapeutic effect on multiple organ diseases, indicating that it has great clinical application potential. In this paper, the extraction, purification, identification and analysis, biological activity, pharmacokinetics in vivo and molecular mechanism of MA in treating various organ diseases are reviewed. It is hoped to provide a new idea for MA to treat various organ diseases.

Maslinic Acid Suppresses High Glucose-induced Inflammation by Epigenetically Inhibiting TXNIP Expression

OBJECTIVE

Hyperglycemia-induced inflammation and subsequent endothelial injuries ultimately lead to the pathogenesis of cardiovascular diseases associated with high mortality, such as atherosclerosis. Maslinic acid (MA) is a phytochemical with anti-inflammatory activity. However, it remains unknown whether it can inhibit diabetes-associated cardiovascular inflammation. The present study aimed to determine the effect of MA on high glucose-induced endothelial inflammation and apoptosis in human umbilical vein endothelial cells (HUVECs) and to explore the underlying mechanism.

METHODS

HUVECs were treated with high glucose to induce inflammation and apoptosis. Apoptosis was determined by flow cytometry. CCK-8 assay was used to examine cell viability. Production levels of cytokines were detected by quantitative realtime PCR (qPCR) and ELISA. Protein expression levels and signaling pathways activation were detected by Western blotting. RNA immunoprecipitation and qPCR were used to determine the N⁶-methyladenosine (m6A) levels of target mRNAs.

RESULTS

MA promoted the recruitment of RNA demethylase ALKBH5 to TXNIP mRNA, and subsequently enhanced its m6A demethylation. By this means, MA decreased the stability of TXNIP mRNA and downregulated its expression level. Subsequently, reactive oxygen species (ROS) and production of pro-inflammatory cytokines, including TNF-α, IL-6 and IL-1β, were inhibited. And high glucose-induced apoptosis in HUVECs was inhibited by MA.

CONCLUSION

MA ameliorates high glucose-induced endothelial inflammation and injury, serving as a new potential therapeutic application for protecting against diabetes-associated atherosclerosis and other inflammatory diseases.

Medicinal plants and their secondary metabolites in alleviating knee osteoarthritis: A systematic review

BACKGROUND

With the increasing ages of the general population, the incidence of knee osteoarthritis (KOA) is also rising, and KOA has become a major health problem worldwide. Recently, medicinal plants and their secondary metabolites have gained interest due to their activity in treating KOA. In this paper, a comprehensive systematic review of the literature was performed concerning the effects of medicinal plant extracts and natural compounds against KOA in recent years. The related molecular pathways of natural compounds against KOA were summarized, and the possible crosstalk among components in chondrocytes was discussed to propose possible solutions for the current situation of treating KOA.

PURPOSE

This review focused on the molecular mechanisms by which medicinal plants and their secondary metabolites act against KOA.

METHODS

Literature searches were performed in the PUBMED, Embase, Science Direct, and Web of Science databases for a 10-year period from 2011 to 2022 with the search terms "medicinal plants," "bioactive compounds," "natural products," "phytochemical," "knee osteoarthritis," "knee joint osteoarthritis," "knee osteoarthritis," "osteoarthritis of the knee," and "osteoarthritis of knee joint."

RESULTS

According to the results, substantial plant extracts and secondary metabolites show a positive effect in fighting KOA. Plant extracts and their secondary metabolites can affect the diagnostic and prognostic biomarkers of KOA. Natural products inhibit the expression of MMP1, MMP3, MMP19, syndecan IV, ADAMTS-4, ADAMTS-5, iNOS, COX-2, collagenases, IL-6, IL-1β, and TNF-α in vitro and in vivo and . Cytokines also upregulate the expression of collagen II and aggrecan. The main signaling pathways affected by the extracts and isolated compounds include AMPK, SIRT, NLRP3, MAPKs, PI3K/AKT, mTOR, NF-κB, WNT/β-catenin, JAK/STAT3, and NRF2, as well as the cell death modes apoptosis, autophagy, pyroptosis, and ferroptosis.

CONCLUSION

The role of secondary metabolites in different signaling pathways supplies a better understanding of their potential to develop further curative options for KOA.

Analysis of the Mechanism of Maslinic Acid on Papillary Thyroid Carcinoma Based on RNA-Seq Technology

Objective

This study analyzed gene sequence changes in the thyroid papillary carcinoma (PTC) cell line TPC-1 treated with the natural compound maslinic acid (MA) through RNA-sequencing (RNA-seq) and identified the necessary genes to provide a basis for the study of the molecular mechanism of action of MA in PTC treatment.

Methods

RNA-seq technology was used to detect genetic differences between the normal cell group (Nthy-ori 3-1) and the TPC-1 cell group (N vs T). Then, gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Venn diagram analysis of shared genes, and protein–protein interaction (PPI) network analysis were used to analyze the therapeutic effect of the MA on TPC-1 cells. Real-time quantitative PCR (qRT-PCR) was used to verify six key genes.

Results

GO and KEGG analyses showed that four crucial signaling pathways are related to TPC development: cytoplasmic molecule (cell adhesion molecules), neuroactive ligand–receptor interaction, tumor transcriptional disorder, and cytokine–cytokine interaction. The Venn diagram revealed 434 genes were shared between the MA vs T-group and 387 genes were shared between the MATH vs T and N vs T groups. PPI and ClueGO showed that NLRP3, SERPINE1, CD74, EDN1, HMOX1, and CXCL1 genes were significantly associated with PTC, while CXCL1, HMOX1, and other factors were mainly involved in the cytokine–cytokine interaction. The qRT-PCR results showed that the expression of NLRP3, EDN1, HMOX1, and CXCL1 genes was significantly upregulated in the TPC-1 group but significantly downregulated after MA treatment (p < 0.01). SERPINE1 and CD74 genes were not expressed in TPC-1 cells, whereas they were significantly upregulated after MA treatment (p < 0.01).

Conclusions

This present study proves for the first time that MA can treat PTC, and the preliminary identification of key genes and rich signal transduction pathways provides potential biomarkers. It also provides potential biomarkers for the treatment of PTC with the natural compound MA and preliminarily discusses the therapeutic mechanism of action of MA against PTC, which is helpful for the further diagnosis and treatment of PTC patients.

Self-Assembled Maslinic Acid Attenuates Doxorobucin Induced Cytotoxicity via Nrf2 Signaling Pathway: An In Vitro and In Silico Study in Human Healthy Cells

The clinical applications of some well-known chemotherapeutic drugs for cancer treatment have been restricted nowadays owing to their adverse effects on many physiological systems. In this experimental study, maslinic acid (MA) isolated from Olea europaea (Olive) fruit extract was used to mitigate the cytotoxicity induced by Doxorubicin (DOX) in human healthy peripheral blood mononuclear cells (hPBMCs). Self-assembled maslinic acid (SA-MA) was obtained in ethanol-water mixture (35.5 mM: 4:1 v/v). The morphology of SA-MA was analyzed by various physicochemical characterization techniques, which revealed its micro-metric vesicular architecture as well as nano-vesicular appearances. In this study, treatment of hPBMCs with DOX has been found to generate severe intracellular oxidative stress, which was significantly mitigated after pre-treatment with SA-MA. Alteration of hPBMC morphologies after DOX treatment was also restored notably by pre-treatment with SA-MA. Furthermore, pentoxifylline (TNF-α inhibitor) and indomethacin (COX-2 inhibitor) were used to investigate the responsible pathway by which SA-MA protected hPBMCs from DOX-induced cellular stress. Restoration of hPBMC viability above 92% in both cases confirmed that SA-MA protected the cells by inhibiting inflammatory pathways generated by DOX treatment. Subsequently, in molecular docking study, it was also evaluated that MA could successfully bind with the pocket region of Keap1, while Nrf2 was capable of upregulating cytoprotecting genes.

"Two-birds-one-stone" colon-targeted nanomedicine treats ulcerative colitis via remodeling immune microenvironment and anti-fibrosis

Dysregulated mucosal immune responses and colonic fibrosis impose two formidable challenges for ulcerative colitis treatment. It indicates that monotherapy could not sufficiently deal with this complicated disease and combination therapy may provide a potential solution. A chitosan-modified poly(lactic-co-glycolic acid) nanoparticle (CS-PLGA NP) system was developed for co-delivering patchouli alcohol and simvastatin to the inflamed colonic epithelium to alleviate the symptoms of ulcerative colitis via remodeling immune microenvironment and anti-fibrosis, a so-called “two-birds-one-stone” nanotherapeutic strategy. The bioadhesive nanomedicine enhanced the intestinal epithelial cell uptake efficiency and improved the drug stability in the gastrointestinal tract. The nanomedicine effectively regulated the Akt/MAPK/NF-κB pathway and reshaped the immune microenvironment through repolarizing M2Φ, promoting regulatory T cells and G-MDSC, suppressing neutrophil and inflammatory monocyte infiltration, as well as inhibiting dendritic cell maturation. Additionally, the nanomedicine alleviated colonic fibrosis. Our work elucidates that the colon-targeted codelivery for combination therapy is promising for ulcerative colitis treatment and to address the unmet medical need.

Network Pharmacology-Based Analysis on the Effects and Mechanism of the Wang-Bi Capsule for Rheumatoid Arthritis and Osteoarthritis

Wang-Bi capsule (WB) is a traditional Chinese medicine (TCM)-based herbal formula, and it has been used in the treatment of rheumatoid arthritis (RA) in China for many years. Additionally, WB is also used as a supplement to the treatment of osteoarthritis (OA) in clinical practice. Our research aimed to reveal the therapeutic effects and underling mechanism of WB on RA and OA through computational system pharmacology analysis and experimental study. Based on network pharmacology analysis, a total of 173 bioactive compounds interacted with 417 common gene targets related to WB, RA, and OA, which mainly involved the PI3K-Akt signaling pathway. In addition, the serine-threonine protein kinase 1 (AKT1) might be a core gene protein for the action of WB, which was further emphasized by molecular docking. Moreover, the anti-inflammatory activity of WB in vitro was confirmed by reducing NO production in lipopolysaccharide (LPS)-induced RAW264.7 cells. The anti-RA and OA effects of WB in vivo were confirmed by ameliorating the disease symptoms of collagen II-induced RA (CIA) and monosodium iodoacetate-induced OA (MIA) in rats, respectively. Furthermore, the role of the PI3K-Akt pathway in the action of WB was preliminarily verified by western blot analysis. In conclusion, our study elucidated that WB is a potentially effective strategy for the treatment of RA and OA, which might be achieved by regulating the PI3K-Akt pathway. It provides us with systematic insights into the effects and mechanism of WB on RA and OA.

Microbial transformation of pentacyclic triterpenes for anti-inflammatory agents on the HMGB1 stimulated RAW 264.7 cells by Streptomyces olivaceus CICC 23628

High mobility group box-1 protein (HMGB1) is a typical Damage-Associated Molecular Patterns (DAMPs) released in response to cellular inflammation. The pentacyclic triterpenes (PTs) are considered to be the natural inhibitors against HMGB1-related inflammation. To explore new lead compounds of PTs as anti-inflammatory agents, biotransformation of four PTs by Streptomyces olivaceus CICC 23628 was investigated in this study. As a result, thirteen unique 3,4-seco-triterpenes metabolites were isolated and twelve of them were first identified and reported. Structures of metabolites were determined based on HR-ESI-MS, 1D/2D NMR, and single-crystal X-ray diffraction. Furthermore, all compounds were subjected to the bioassay on the model of HMGB1-stimulated RAW 264.7 cells to evaluate their anti-inflammatory activity through nitric oxide (NO) inhibition activity. Compounds 3b (3,4-seco-olean-12-en-4,21α,22β,24-tetrahydroxy-ol-3-oic acid) and 2b (3,4-seco-olean-12-en-4,21β,22β,24,29-pentahydroxy-ol-3-oic acid) exhibited NO inhibitory activity with IC₅₀ values of 15.94 μM and 36.00 μM, respectively. Thus, indicating their potential as HMGB1 inhibitors and in developing potent anti-inflammatory agents. This work provides an operationally simple, efficient method for the rapid diversification of the PTs scaffold for a variety of distinctive 3,4-seco-triterpenes to facilitate the discovery of potential anti-inflammatory compounds.

Maslinic Acid Attenuates Ischemia/Reperfusion Injury-Induced Myocardial Inflammation and Apoptosis by Regulating HMGB1-TLR4 Axis

Aims: The inflammatory response and apoptosis are the major pathological features of myocardial ischemia/reperfusion injury (MI/RI). Maslinic acid (MA), a natural pentacyclic triterpene with various bioactivities, plays critical roles in the multiple cellular biological processes, but its protective effects on the pathophysiological processes of MI/RI have not been extensively investigated. Our study aimed to determine whether MA treatment alleviate ischemia/reperfusion (I/R)-induced myocardial inflammation and apoptosis both in vitro and in vivo, and further reveal the underlying mechanisms. Methods and results: An MI/RI rat model was successfully established by ligating the left anterior descending coronary artery and H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to mimic I/R injury. In addition, prior to H/R stimulation or myocardial I/R operation, the H9c2 cells or rats were treated with varying concentrations of MA or vehicle for 24 h and two consecutive days, respectively. In this study, our results showed that MA could obviously increase the cell viability and decrease the cardiac enzymes release after H/R in vitro. MA could significantly improve the H/R-induced cardiomyocyte injury and I/R-induced myocardial injury in a dose-dependent manner. Moreover, MA suppressed the expression of inflammatory cytokines (tumor necrosis factor alpha [TNF-α, interleukin-1β [IL-1β and interleukin-6 [IL-6]) and the expressions of apoptosis-related proteins (cleaved caspase-3 and Bax) as well as increased the levels of anti-apoptotic protein Bcl-2 expression both in vitro and in vivo. Mechanistically, MA significantly inhibited nuclear translocation of nuclear factor-κB (NF-κB) p65 after H/R via regulating high mobility group box 1 (HMGB1)/toll-like receptor 4 (TLR4) axis. Conclusion: Taken together, MA treatment may alleviate MI/RI by suppressing both the inflammation and apoptosis in a dose-dependent manner, and the cardioprotective effect of MA may be partly attributable to the inactivation of HMGB1/TLR4/NF-κB pathway, which offers a new therapeutic strategy for MI/RI.

Circ_SPG11 plays contributing effects on IL-1β-induced chondrocyte apoptosis and ECM degradation via miR-665 inhibition-mediated GREM1 upregulation

The dysregulation of circular RNA (circRNA) has been monitored in osteoarthritis (OA) cartilage, hinting that circRNA deregulation modulates OA progression. We thus aimed to unveil the role of circRNA spastic paraplegia 11 (circ_SPG11) in OA conditions. The upregulation of circ_SPG11 was observed in OA cartilage and IL-1β-treated chondrocytes. Knockdown of circ_SPG11 restored IL-1β-depleted cell proliferation and alleviated IL-1β-induced cell apoptosis and ECM degradation. Circ_SPG11 bound to miR-665 and negatively regulated miR-665 expression. Inhibition of miR-665 reversed the inhibitory effect on IL-1β-induced chondrocyte injury caused by circ_SPG11 knockdown. GREM1 was a target of miR-665, and circ_SPG11 knockdown depleted GREM1 expression by enriching miR-665. Overexpression of GREM1 also reversed the inhibitory effect on IL-1β-induced chondrocyte injury caused by miR-665 enrichment. Circ_SPG11 might promote IL-1β-induced chondrocyte apoptosis and ECM degradation via increasing GREM1 expression by decoying miR-665.

Renoprotective Effects of Maslinic Acid on Experimental Renal Fibrosis in Unilateral Ureteral Obstruction Model via Targeting MyD88

Maslinic acid (MA), also named crategolic acid, is a pentacyclic triterpene extracted from fruits and vegetables. Although various beneficial pharmacological effects of MA have been revealed, its effect on renal fibrosis remains unclear. This study was designed to clarify whether MA could attenuate renal fibrosis and determine the putative underlying molecular mechanisms. We demonstrated that MA-treated mice with unilateral ureteral obstruction (UUO) developed a histological injury of low severity and exhibited downregulated expression of fibrotic markers, including α-smooth muscle actin (α-SMA), vimentin, and fibronectin by 38, 44 and 40%, and upregulated expression of E-cadherin by 70% as compared with untreated UUO mice. Moreover, MA treatment restored the expression levels of α-SMA, connective tissue growth factor, and vimentin to 10, 7.8 and 38% of those induced by transforming growth factor (TGF)-β in NRK49F cells. MA decreased expression of Smad2/3 phosphorylation and Smad4 in UUO kidneys and TGF-β treated NRK49F cells (p < 0.05, respectively). Notably, MA specifically interferes with MyD88, an adaptor protein, thereby mitigating Smad4 nuclear expression (p < 0.01 compared to TGF-β treated group) and ameliorating renal fibrotic changes (p < 0.01 for each fibrotic markers compared to TGF-β induced cells). In addition, in the UUO model and lipopolysaccharide-induced NRK49F cells, MA treatment decreased the expression of IL-1β, TGF-α and MCP-1, ICAM-1, associated with the suppression of NF-κB signaling. These findings suggest that MA is a potential agent that can reduce renal interstitial fibrosis, to some extent, via targeting TGF-β/Smad and MyD88 signaling.

The Anticancer Potential of Maslinic Acid and Its Derivatives: A Review

Cancer is still an insurmountable problem for humans and critically attacking human health. In recent years, natural products have gained increasing attention in the field of anti-tumor due to their extensive sources and minimal side effects. Maslinic acid (MA), a pentacyclic triterpene acid mainly derived from the olive tree (Olea europaea L.) has been confirmed to possess great anti-cancer effects. This paper reviewed the inhibitory effect of MA and its derivatives on lung cancer, colon cancer, ovarian cancer, gastric cancer, lymphatic, leukemia, breast cancer, pancreatic cancer, melanoma, prostate cancer, renal cell carcinoma, gallbladder cancer, and bladder cancer, among others. MA inhibited the proliferation of various tumor cells and showed lower IC50 values in melanoma 518A2 cells and gastric cancer MKN28 cells compared with other cell lines. A series of semi-synthetic derivatives obtained by modifying MA chemical structure have been shown to have high cytotoxicity to human tumor cell lines, but low cytotoxicity to non-malignant cells, which is conducive to developing its potential as a chemotherapeutic agent. These studies suggest that MA derivatives have broad prospects in the development of antitumor therapeutics in the future and warrant further study.

Anti-Inflammatory Action of Dietary Wild Olive (Acebuche) Oil in the Retina of Hypertensive Mice

Inflammation plays a crucial role in the course of eye diseases, including many vascular retinopathies. Although olive oil is known to have beneficial effects against inflammatory processes, there is no information available on the anti-inflammatory potential of the wild olive tree (namely, acebuche (ACE) for the primitive Spanish lineages). Here we investigate the anti-inflammatory effects of ACE oil in the retina of a mouse model of arterial hypertension, which was experimentally induced by administration of L-NAME (NG-nitro-L-arginine-methyl-ester). The animals were fed supplements of ACE oil or extra virgin olive oil (EVOO, for comparative purposes). Retinal function was assessed by electroretinography (ERG), and different inflammation-related parameters were measured in the retina and choroid. Besides significant prevention of retinal dysfunction shown in ERG recordings, ACE oil-enriched diet upregulated the expression of the anti-inflammatory markers PPARγ, PPARα and IL-10, while reducing that of major proinflammatory biomarkers, IL-1β, IL-6, TNF-α and COX-2. This is the first report to highlight the anti-inflammatory properties of an ACE oil-enriched diet against hypertension-related retinal damage. Noteworthy, dietary supplementation with ACE oil yielded better results compared to a reference EVOO.

Aldehyde dehydrogenase 2 alleviates monosodium iodoacetate-induced oxidative stress, inflammation and apoptosis in chondrocytes via inhibiting aquaporin 4 expression

BACKGROUND

Knee osteoarthritis (KOA) is a common cause of disability among the elderly. We aimed to explore the effects of aldehyde dehydrogenase (ALDH) 2 on the progression of KOA and identifying the potential mechanisms.

METHODS

First, ALDH2 expression in knee joint effusion of patients with KOA and the levels of oxidative stress-related markers were determined. After ALDH2 overexpression in monosodium iodoacetate (MIA)-treated SW1353 cells, cell viability was tested with CCK-8 assay. Subsequently, oxidative stress and inflammation-associated factors were measured. Meanwhile, cell apoptosis was assessed with TUNEL staining and expression of apoptosis-related proteins was detected by western blotting. To analyze the mechanism of ALDH2 in KOA, aquaporin 4 (AQP4) expression was determined using western blotting following ALDH2-upregulation. Subsequently, AQP4 was overexpressed to evaluate the changing of oxidative stress, inflammation and apoptosis in SW1353 cells exposed to MIA with ALDH2 overexpression.

RESULTS

Results indicated that knee joint effusion with higher ALDH2 expression displayed lower oxidative stress. In addition, significantly upregulated ALDH2 expression was observed in MIA-treated SW1353 cells. ALDH2 overexpression oxidative stress, inflammation and apoptosis in SW1353 cells exposed to MIA. Moreover, MIA-triggered elevated expression of AQP4, which was reduced by ALDH2 overexpression. By contrast, AQP4-upregulation abrogated the inhibitory effects of ALDH2 on oxidative stress, inflammation and apoptosis in MIA-induced SW1353 cells.

CONCLUSIONS

ALDH2 inactivates the expression of AQP4, by which mechanism the MIA-induced oxidative stress, inflammation and apoptosis injuries were alleviated, which provides a novel insight for understanding the mechanism of KOA and a promising target for the treatment of this disease.

Role of the miR-133a-5p/FBXO6 axis in the regulation of intervertebral disc degeneration

OBJECTIVE

Low back pain is a leading cause of disabilities worldwide, and intervertebral disc degeneration (IVDD)-related disorders have been recognised as one of the main contributors. Nevertheless, the underlying mechanism has not yet been fully understood. The aim of this study was to investigate the role of the miR-133a-5p/FBXO6 axis in the regulation of IVDD.

METHODS

RT-qPCR, WB and IHC were performed to assess the expression of FBXO6 in human IVD tissues. Nucleus pulposus (NP) cells were treated with IL-1β to induce IVDD cellular model. Silence of FBXO6 was achieved using specific siRNAs. CCK-8 assay, flow cytometry, TUNEL assay, RT-qPCR and WB were used to evaluate the role and mechanism of FBXO6 in the process of IVDD. Online tools, GSE datasets and RT-qPCR were used to search the candidate miRNAs targeting FBXO6. The direct binding sites between FBXO6 and miR-133a-5p were further verified by a dual luciferase assay. RT-qPCR, WB and rescue experiments were conducted to identify the regulatory function of miR-133a-5p on the expression of aggrecan, collagen Ⅱ, MMP3, ADAMTS5, IL-6 and COX2. In addition, the role of the NF-κB pathway in regulating miR-133a-5p was studied using lentiviral shRNA, WB and RT-qPCR.

RESULTS

Results showed that FBXO6 mainly expressed in the NP tissue of IVD and the expression of FBXO6 decreased with the process of IVDD as well as under IL-1β stimulation. The silence of FBXO6 led to the decreased expression of aggrecan and collagen Ⅱ and the increased expression of MMP3, ADAMTS5, IL-6 and COX2, which further induced the degeneration of NP cells. The bioinformatic analysis showed that miR-133a-5p was the candidate miRNA targeting FBXO6. miR-133a-5p was upregulated in IVDD tissues and significantly inhibited the expression of FBXO6. The inhibition of miR-133a-5p ameliorated the acceleration of IVDD induced by the silence of FBXO6 in vitro. Moreover, it was demonstrated that IL-1β regulated the expression of the miR-133a-5p/FBXO6 axis via the NF-κB pathway in NP cells.

CONCLUSION

miR-133a-5p was upregulated by IL-1β to aggravate intervertebral disc degeneration via sponging FBXO6. Inhibiting miR-133a-5p expression or rescuing FBXO6 expression may be promising strategies for the treatment of IVDD.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study suggests that the miR-133a-5p/FBXO6 axis could regulate NP cells proliferation, apoptosis, synthesis and degradation of extracellular matrix, which provides a promising therapeutic target and strategy for the treatment of IVDD.

Kaempferol attenuates the effects of XIST/miR-130a/STAT3 on inflammation and extracellular matrix degradation in osteoarthritis

Aim: To investigate whether kaempferol exhibited protective effects on osteoarthritis chondrocytes by modulating the XIST/miR-130a/STAT3 axis. Methods: qRT-PCR and western blot assays were used for gene and protein determination. Dual luciferase reporter and RNA immunoprecipitation assays were employed to study the interaction between miRNA and lncRNA or genes. Results: Kaempferol decreased proinflammatory cytokine production and extracellular matrix degradation in C28/I2 cells. Additionally, kaempferol ameliorated XIST expression and enhanced miR-130a expression. XIST interacted with miR-130a, and STAT3 was identified as a target of miR-130a. Knockdown of XIST expression suppressed proinflammatory cytokine production and extracellular matrix degradation in C28/I2 cells. Overexpression of STAT3 rescued the effects of XIST knockdown. Conclusion: Kaempferol inhibited inflammation and extracellular matrix degradation by modulating the XIST/miR-130a/STAT3 axis in chondrocytes.

Expression of VEGF-A Signaling Pathway in Cartilage of ACLT-induced Osteoarthritis Mouse Model

BACKGROUND

Anterior cruciate ligament transection surgery (ACLT)-induced OA model was often used to investigate the molecular mechanism of knee osteoarthritis (KOA). Researches have shown that vascular endothelial growth factor (VEGF) played an important role in OA. The present study aimed to investigate the pathological changes after ACLT surgery and reveal the expression characteristics of the VEGF-A/VEGFR2 signaling pathway in this model.

METHODS

Moderate KOA model was established by ACLT, and 1, 2, 4, 8, and 12 weeks after surgery, hematoxylin-eosin (HE) and Safranin-O(S-O) staining were used to detect the pathological changes in mouse knee cartilage, and the matrix biomarkers A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5(ADAMTS5), Collagen II (COL-II) were detected using immunohistochemistry (IHC), CD31 was detected by immunofluorescence (IF) to show the vascular invasion in cartilage, and proteins expression of VEGF-A pathway were detected by Western blot (WB). Meanwhile, the inflammatory biomarkers cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in cartilage were detected by WB.

RESULTS

ACLT surgery can lead to degeneration of cartilage in mice, and the characteristics of the lesion were time-dependent. The ADAMTS5-positive cells increased while COL-II decreased in OA cartilage with time, and new blood vessels labeled by CD31 can be seen from 1 week in OA cartilage, and increased in 8 and 12 weeks. The expression of VEGF-A, VEGFR2, COX-2, and iNOS were higher than control groups, which were basically consistent with the degree of osteoarthritis.

CONCLUSIONS

The degenerative degree of articular cartilage was time-dependent; angiogenesis and inflammation were important pathological changes of cartilage in KOA. The expression of the VEGF-A/VEGFR2 signaling pathway was basically correlated with the degree of KOA.

Angelicin Alleviates Post-Trauma Osteoarthritis Progression by Regulating Macrophage Polarization via STAT3 Signaling Pathway

Post-trauma osteoarthritis (PTOA) is the most common articular disease characterized by degeneration and destruction of articular cartilage (Bultink and Lems, Curr. Rheumatol Rep., 2013, 15, 328). Inflammatory response of local joint tissue induced by trauma is the most critical factor accelerating osteoarthritis (OA) progression (Sharma et al., 2019; Osteoarthritis. Cartilage, 28, 658–668). M1/M2 macrophages polarization and repolarization participates in local inflammation, which plays a major role in the progression of OA (Zhang et al., 2018; Ann. Rheum. Dis., 77, 1524–1534). The regulating effect of macrophage polarization has been reported as a potential therapy to alleviate OA progression. Synovitis induced by polarized macrophages could profoundly affect the chondrocyte and cartilage matrix (Zhang et al., 2018; Ann. Rheum. Dis., 77, 1524–1534). Generally, anti-inflammatory medications widely used in clinical practice have serious side effects. Therefore, we focus on exploring a new therapeutic strategy with fewer side effects to alleviate the synovitis. Angelicin (ANG) is traditional medicine used in various folk medicine. Previous studies have revealed that angelicin has an inhibitory effect on inflammation (Wei et al., 2016; Inflammation, 39, 1876–1882), tumor growth (Li et al., 2016; Oncology reports, 36, 3,504–3,512; Wang et al., 2017; Molecular Medicine Reports, 16, 5441–5449), DNA damage (Li et al., 2019; Exp. Ther. Med., 18, 1899–1906), and virus proliferation (Li et al., 2018; Front. Cell. Infect. Microbiol., 8, 178). But its specific effects on influencing the process of OA were rarely reported. In this study, the molecular mechanism of angelicin in vivo and in vitro was clearly investigated. Results showed that angelicin could regulate the M1/M2 ratio and function and alleviate the development of PTOA in the meanwhile. Bone marrow monocytes were isolated and induced by macrophage colony-stimulating factor (M-CSF), lipopolysaccharide (LPS) and interferon (IFN)-γ for M1 polarization and interleukin (IL)-4/IL-13 for M2 polarization. Subsequently, repolarization intervention was performed. The results indicate that angelicin can repolarize M1 toward M2 macrophages by upregulating the expression of CD9. Besides, angelicin can also protect and maintain M2 polarization in the presence of LPS/IFN-γ, and subsequently downregulate the expression of inflammatory mediators such as IL-1β and TNF-α. Mechanistically, angelicin can activate the p-STAT3/STAT3 pathway by conducting CD9/gp130 to repolarize toward M2 macrophages. These results suggest angelicin can alleviate the progression of OA by regulating M1/M2 polarization via the STAT3/p-STAT3 pathway. Therefore, angelicin may have a promising application and potential therapeutic value in OA clinical treatment.

Role of Physical Exercise and Nutraceuticals in Modulating Molecular Pathways of Osteoarthritis

Osteoarthritis (OA) is a painful and disabling disease that affects millions of patients. Its etiology is largely unknown, but it is most likely multifactorial. OA pathogenesis involves the catabolism of the cartilage extracellular matrix and is supported by inflammatory and oxidative signaling pathways and marked epigenetic changes. To delay OA progression, a wide range of exercise programs and naturally derived compounds have been suggested. This literature review aims to analyze the main signaling pathways and the evidence about the synergistic effects of these two interventions to counter OA. The converging nutrigenomic and physiogenomic intervention could slow down and reduce the complex pathological features of OA. This review provides a comprehensive picture of a possible signaling approach for targeting OA molecular pathways, initiation, and progression.

Multifunctional l-arginine-based magnetic nanoparticles for multiple-synergistic tumor therapy

Tumor therapy is facing the big challenge of insufficient treatment. Here, we report high-intensity focused ultrasound (HIFU)-responsive magnetic nanoparticles based on superparamagnetic iron oxide (SPIO, Fe₃O₄ NPs) as the shell and l-arginine (LA) as the core entrapped by poly-lactide-co-glycolide (PLGA) nanoparticles (Fe₃O₄@PLGA/LA NPs) for synergistic breast cancer therapy. These NPs can significantly enhance therapeutic performance due to their enhanced accumulation and prolonged retention at the tumor site under magnetic guidance. The Fe₃O₄@PLGA/LA NPs exhibited synergistic therapeutic effects by the rational combination of HIFU-based tumor ablation and nitric oxide (NO) assisted antitumor gas therapy. Both Fe₃O₄ NPs and LA could be released rapidly under HIFU irradiation, where Fe₃O₄ NPs can promote HIFU-based tumor ablation by changing the acoustic properties of the tumor tissues and LA can spontaneously react with hydrogen peroxide (H₂O₂) in the tumor microenvironment to generate NO for gas therapy. Moreover, Fe₃O₄ NPs can react with H₂O₂ to produce highly reactive oxygen-containing species (ROS) to accelerate the oxidation of LA and the release of NO. This novel strategy showed synergistic tumor growth suppression as compared with individual HIFU therapy or gas therapy. This can be attributed to the rational design of multifunctional NPs with magnetic targeting and multi-modality imaging properties.

CTRP9 protects against MIA-induced inflammation and knee cartilage damage by deactivating the MAPK/NF-κB pathway in rats with osteoarthritis

C1q/TNF-related protein 9 (CTRP9), the closest paralog of adiponectin, has been reported to protect against inflammation-related diseases. However, its role in regulating osteoarthritis (OA) has not been fully elucidated. First, a rat model of OA was generated. Furthermore, rats with OA were injected with different doses of recombinant CTRP9 protein (rCTRP9), and the knee cartilage damage was evaluated. Finally, the phosphorylation of p38 and the secretion of matrix metalloproteinases (MMPs) were detected by Western blotting and enzyme-linked immunosorbent assay. Results revealed that CTRP9 was highly expressed in adipose tissue, followed by skeletal muscle and cartilage tissue, and less expressed in liver, kidney and lung. Moreover, the expression of CTRP9 significantly decreased in the monosodium iodoacetate (MIA) group in the knee cartilage and knee synovial fluid, and the contents of interleukin-1β (IL-1β) and IL-6 significantly increased in knee synovial fluid. In addition, rCTRP9 alleviated MIA-induced inflammation, oxidative stress and knee cartilage damage in a dose-dependent way. In addition, rCTRP9 could attenuate the expression of p38MAPK and p-p38 and suppress the expression of nuclear factor-kappa B (NF-κB), p65 and MMPs. Collectively, the results of the present study suggested that CTRP9 alleviates the inflammation of MIA-induced OA through deactivating p38MAPK and NF-κB signaling pathways in rats.