The protective effect of phloretin in osteoarthritis: an in vitro and in vivo study

Natural compound phloretin restores periodontal immune homeostasis via HIF-1α-regulated PI3K/Akt and glycolysis in macrophages

Periodontitis is a chronic inflammatory disease that affects about 45 %-50 % of adults worldwide, but the efficacy of current clinical therapies is unsatisfactory due to the complicated periodontal immune microenvironment. Thus, developing drugs that can regulate innate immune cells (e.g., macrophages) is a potent strategy to treat periodontitis. Here, we report that phloretin, a food plant-derived natural compound, is sufficient to alleviate periodontitis through immune regulation. In vivo, phloretin treatment could significantly reduce alveolar bone resorption and periodontal inflammation in mouse periodontitis models. In vitro, phloretin could suppress proinflammatory (M1-like) polarization and cytokine release in macrophages induced by LPS. Mechanistically, the immune regulatory role of phloretin in macrophages may be due to its metabolic regulation effect. Phloretin might restore the balance of M1/M2 macrophage transition in periodontitis by inhibiting HIF-1α-mediated glycolysis and PI3k/Akt pathways, thereby reducing the proinflammatory effect and immune disorder caused by over-activated M1 macrophages. Together, this study highlights that natural compound, such as phloretin, can restore periodontal immune homeostasis by metabolic regulation of macrophages, which may provide novel insight into the treatment of periodontitis.

Glycosylation mode of phloretin affects the morphology and stress resistance of apple plant

Phloretin has different glycosylation modes in plants. Phlorizin (phloretin 2'-O-glucoside) is one of the glycosylation products of phloretin, and accumulates abundantly in apple plants. However, it is still unclear whether phlorizin is more beneficial for apple plants compared with other glycosylation products of phloretin. We created transgenic apple plants with different glycosylation modes of phloretin. In transgenic plants, the accumulation of phlorizin was partly replaced by that of trilobatin (phloretin 4'-O-glucoside) or phloretin 3',5'-di-C-glycoside. Compared with wild type, transgenic plants with less phlorizin showed dwarf phenotype, larger stomatal size, higher stomatal density and less tolerance to drought stress. Transcriptome and phytohormones assay indicate that phlorizin might regulate stomatal development and behaviour via controlling auxin and abscisic acid signalling pathways as well as carbonic anhydrase expressions. Transgenic apple plants with less phlorizin also showed less resistance to spider mites. Apple plants may hydrolyse phlorizin to produce phloretin, but cannot hydrolyse trilobatin or phloretin 3',5'-di-C-glycoside. Compared with its glycosylation products, phloretin is more toxic to spider mites. These results suggest that the glycosylation of phloretin to produce phlorizin is the optimal glycosylation mode in apple plants, and plays an important role in apple resistance to stresses.

Integrating network pharmacology and experimental verification to explore the pharmacological mechanisms of phlorizin against osteoarthritis

To study the pharmacological effects and mechanisms of phlorizin in the treatment of osteoarthritis (OA) through network pharmacological analysis, molecular docking, and experimental validation. First, we screened out the relevant targets related to phlorizin and OA from the public database. The key targets, biological processes, and signaling pathways of phlorizin against OA were identified by protein-protein interaction (PPI) network, Gene Ontology (GO), and Encyclopedia of Kyoto Genes and Genomes (KEGG) pathway enrichment analysis. Subsequently, molecular docking was performed to predict the binding activity between phlorizin and key targets. Finally, we evaluated the effects of phlorizin on hydrogen peroxide-induced OA in rats and validated its possible mechanism of action based on the findings of the network pharmacology analysis. Network pharmacology revealed a total of 235 cross-targets involved in the treatment of OA. Phlorizin's anti-OA effect was found to be primarily mediated through oxidoreductase activity, with JAK-STAT and NF-κB signaling pathways playing a regulating role, according to pathway enrichment analysis. Phlorizin demonstrated a strong affinity for NF-κB1 targets through molecular docking. Moreover, in vitro experiments demonstrated that phlorizin could enhance intracellular antioxidant enzyme activities with good ROS scavenging ability and significantly reduce the expression of NF-κB1 and inflammatory cytokines. Phlorizin can inhibit the progression of OA. The potential underlying mechanism involves inhibiting the NF-κB pathway to reduce inflammation and promote intracellular antioxidant action.

Revisiting prostaglandin E2: A promising therapeutic target for osteoarthritis

Osteoarthritis (OA) is a complex disease characterized by cartilage degeneration and persistent pain. Prostaglandin E2 (PGE2) plays a significant role in OA inflammation and pain. Recent studies have revealed the significant role of PGE2-mediated skeletal interoception in the progression of OA, providing new insights into the pathogenesis and treatment of OA. This aspect also deserves special attention in this review. Additionally, PGE2 is directly involved in pathologic processes including aberrant subchondral bone remodeling, cartilage degeneration, and synovial inflammation. Therefore, celecoxib, a commonly used drug to alleviate inflammatory pain through inhibiting PGE2, serves not only as an analgesic for OA but also as a potential disease-modifying drug. This review provides a comprehensive overview of the discovery history, synthesis and release pathways, and common physiological roles of PGE2. We discuss the roles of PGE2 and celecoxib in OA and pain from skeletal interoception and multiple perspectives. The purpose of this review is to highlight PGE2-mediated skeletal interoception and refresh our understanding of celecoxib in the pathogenesis and treatment of OA.

Harpagide inhibits the TNF-α-induced inflammatory response in rat articular chondrocytes by the glycolytic pathways for alleviating osteoarthritis

Osteoarthritis (OA) causes severe and functional dysfunction due to abnormal inflammation. The objective of this study was to evaluate the effect of Harpagide (HPG) on TNF-α-induced inflammation in vitro and in vivo. The effect of HPG on the proliferation of rat chondrocytes was studied. The anti-inflammatory effect of HPG and its molecular mechanisms were elucidated by qPCR, Western blotting, flow cytometry, metabolome analysis in vitro. In addition, the OA rat model was established, and the effect of HPG on OA was verified in vivo. We revealed 10 μM HPG demonstrated biocompatibility. The results demonstrated that HPG restored the upregulation of MMP-13, COX2, IL-1β and IL-6 induced by TNF-α. Moreover, HPG reversed TNF-α induced degradation of the extracellular matrix of chondrocytes. TNF-α treatment induced down-regulation of the mRNA/protein levels of proliferative markers Bcl2, CDK1 and Cyclin D1 were also recovered. HPG can inhibit TNF-α-induced inflammatory response through glycolytic metabolic pathways. HPG can restore TNF-α-induced upregulation of GRP78/IRE1α, and downregulation of AMPK proteins. In vivo experiments demonstrated that after HPG treatment, the appearance and physiological structure of articular cartilage were more integrated with highly organized chondrocytes and rich cartilage matrix compared with OA group. Finally, the molecular docking of HPG and selected key factors in glycolysis results showed that HPG had good binding potential with PFKM, PFKP, PFKFB3, PKM, HK2, and PFKL. In conclusion, the results shown HPG protects and activates chondrocytes, inhibits TNF-α-induced inflammatory response by glycolysis pathway in rat articular chondrocytes, and plays a role in the treatment of OA.

The Protective Effect of Selenium Nanoparticles in Osteoarthritis: In vitro and in vivo Studies

Introduction

Osteoarthritis (OA) is a common chronic joint disease characterized by articular cartilage degeneration. OA usually manifests as joint pain, limited mobility, and joint effusion. Currently, the primary OA treatment is non-steroidal anti-inflammatory drugs (NSAIDs). Although they can alleviate the disease's clinical symptoms and signs, the drugs have some side effects. Selenium nanoparticles (SeNPs) may be an alternative to relieve OA symptoms.

Materials and Results

We confirmed the anti-inflammatory effect of selenium nanoparticles (SeNPs) in vitro and in vivo experiments for OA disease in this study. In vitro experiments, we found that SeNPs could significantly reduce the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the major inflammatory factors, and had significant anti-inflammatory and anti-arthritic effects. SeNPs can inhibit reactive oxygen species (ROS) production and increased glutathione peroxidase (GPx) activity in interleukin-1beta (IL-1β)-stimulated cells. Additionally, SeNPs down-regulated matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) expressions, while up-regulated type II collagen (COL-2) and aggrecan (ACAN) expressions stimulated by IL-1β. The findings also indicated that SeNPs may exert their effects through suppressing the NF-κB p65 and p38/MAPK pathways. In vivo experiments, the prevention of OA development brought on by SeNPs was demonstrated using a DMM model.

Discussion

Our results suggest that SeNPs may be a potential anti-inflammatory agent for treating OA.

The Molecular Pharmacology of Phloretin: Anti-Inflammatory Mechanisms of Action

The isolation of phlorizin from the bark of an apple tree in 1835 led to a flurry of research on its inhibitory effect on glucose transporters in the intestine and kidney. Using phlorizin as a prototype drug, antidiabetic agents with more selective inhibitory activity towards glucose transport at the kidney have subsequently been developed. In contrast, its hydrolysis product in the body, phloretin, which is also found in the apple plant, has weak antidiabetic properties. Phloretin, however, displays a range of pharmacological effects including antibacterial, anticancer, and cellular and organ protective properties both in vitro and in vivo. In this communication, the molecular basis of its anti-inflammatory mechanisms that attribute to its pharmacological effects is scrutinised. These include inhibiting the signalling pathways of inflammatory mediators' expression that support its suppressive effect in immune cells overactivation, obesity-induced inflammation, arthritis, endothelial, myocardial, hepatic, renal and lung injury, and inflammation in the gut, skin, and nervous system, among others.

Overview of Anti-Inflammatory and Anti-Nociceptive Effects of Polyphenols to Halt Osteoarthritis: From Preclinical Studies to New Clinical Insights

Knee osteoarthritis (OA) is one of the most multifactorial joint disorders in adults. It is characterized by degenerative and inflammatory processes that are responsible for joint destruction, pain and stiffness. Despite therapeutic advances, the search for alternative strategies to target inflammation and pain is still very challenging. In this regard, there is a growing body of evidence for the role of several bioactive dietary molecules (BDMs) in targeting inflammation and pain, with promising clinical results. BDMs may be valuable non-pharmaceutical solutions to treat and prevent the evolution of early OA to more severe phenotypes, overcoming the side effects of anti-inflammatory drugs. Among BDMs, polyphenols (PPs) are widely studied due to their abundance in several plants, together with their benefits in halting inflammation and pain. Despite their biological relevance, there are still many questionable aspects (biosafety, bioavailability, etc.) that hinder their clinical application. This review highlights the mechanisms of action and biological targets modulated by PPs, summarizes the data on their anti-inflammatory and anti-nociceptive effects in different preclinical in vitro and in vivo models of OA and underlines the gaps in the knowledge. Furthermore, this work reports the preliminary promising results of clinical studies on OA patients treated with PPs and discusses new perspectives to accelerate the translation of PPs treatment into the clinics.

Loganin attenuates interleukin-1-induced chondrocyte inflammation, cartilage degeneration, and rat synovial inflammation by regulating TLR4/MyD88/NF-κB

Objective

Inflammation plays a crucial part in osteoarthritis (OA) development. This work aimed to explore loganin’s role and molecular mechanism in inflammation and clarify its anti-inflammatory effects in OA treatment.

Methods

Chondrocytes were stimulated using interleukin (IL)-1β and loganin at two concentrations (1 μM and 10 μM). Nitric oxide (NO) and prostaglandin E2 (PGE2) expression was assessed. Real-time polymerase chain reaction was used to evaluate inducible NO synthase (iNOS), cyclooxygenase (COX)-2, IL-6, and tumor necrosis factor (TNF)-α mRNA levels. Western blot was used to investigate TLR4, MyD88, p-p65, and IκB-α expression. p65 nuclear translocation, synovial inflammatory response, and cartilage degeneration were also assessed.

Results

Loganin significantly reduced IL-1β-mediated PGE2, NO, iNOS, and COX-2 expression compared with that of the IL-1β stimulation group. The TLR4/MyD88/NF-κB pathway was suppressed by loganin, which decreased inflammatory cytokine (TNF-α and IL-6) levels compared with those of the IL-1β stimulation group. Loganin inhibited IL-1β-mediated NF-κB p65 nuclear translocation compared with that of the IL-1β stimulation group. Loganin partially suppressed cartilage degeneration and the synovial inflammatory response in vivo.

Conclusion

This work demonstrated that loganin inhibited IL-1β-mediated inflammation in rat chondrocytes through TLR4/MyD88/NF-κB pathway regulation, thereby reducing rat cartilage degeneration and the synovial inflammatory response.

Protective effects of apple polyphenols on bone loss in mice with high fat diet-induced obesity

Obesity-induced inflammation can lead to an imbalance in bone formation and resorption. Our previous studies have demonstrated that apple polyphenols (AP) can reduce body weight and inflammation. But its effect...

Sex-Specific Reduction in Inflammation of Osteoarthritic Human Chondrocytes and Nutraceutical-Dependent Extracellular Matrix Formation

Introduction

The aim of this study was to investigate the ability of osteoarthritic human chondrocytes to produce articular cartilage (AC) tissues with a reduced inflammatory environment in response to 4 anti-inflammatory nutraceuticals: alpha-tocopherol (Alpha), gallic acid (G), ascorbic acid (AA), and catechin hydrate (C).

Methods

Chondrocytes isolated from patients who underwent total knee arthroplasty surgeries were divided into groups (9 male; mean age, 66.2 ± 3.5 years and 11 female; mean age, 64.2 ± 3.1 years). Cells were cultured based on sex and supplemented with either a negative control (NC) medium or NC plus one of the nutraceuticals at a concentration of 50 μM. At day 21, cultures were characterized histologically, biochemically, and for gene expression of vital markers.

Results

At day 21, 62.3% and 66.2% reduction in nitric oxide (NO) content was evident for female and male cells, respectively. G-treatment of female cells resulted in the lowest expression of nitric oxide synthase-2 (NOS2), matrix metalloproteinase-13 (MMP13), and collagen type-10 (COL10). Alpha-treatment of male cells resulted in the lowest expression of NOS2, bone morphogenic protein-2, MMP13, COL10 and tumor necrosis factor alpha induced protein-6 (TNFAIP6) relative to NC. AA and Alpha treatment resulted in the highest glycosaminoglycan (GAG) content for female and male cultures, respectively.

Conclusion

A sex-dependent response of osteoarthritic chondrocytes to nutraceutical treatment was evident. Our results suggest the use of G for female cells and Alpha for male cells in OA applications seems to be favorable in reducing inflammation and enhancing chondrocytes' ability to form AC tissues.

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Inflammation plays an important role in the development of acute lung injury (ALI). Severe pulmonary inflammation can cause acute respiratory distress syndrome (ARDS) or even death. Expression of proinflammatory interleukin-‍1β (IL-‍1β) and inducible nitric oxide synthase (iNOS) in the process of pulmonary inflammation will further exacerbate the severity of ALI. The purpose of this study was to explore the effect of Palrnatine (Pa) on lipopolysaccharide (LPS)-induced mouse ALI and its underlying mechanism. Pa, a natural product, has a wide range of pharmacological activities with the potential to protect against lung injury. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) assays were performed to detect the expression and translation of inflammatory genes and proteins in vitro and in vivo. Immunoprecipitation was used to detect the degree of P65 translocation into the nucleus. We also used molecular modeling to further clarify the mechanism of action. The results showed that Pa pretreatment could significantly inhibit the expression and secretion of the inflammatory cytokine IL-1β, and significantly reduce the protein level of the proinflammatory protease iNOS, in both in vivo and in vitro models induced by LPS. Further mechanism studies showed that Pa could significantly inhibit the activation of the protein kinase B (Akt)/nuclear factor-κB (NF-κB) signaling pathway in the LPS-induced ALI mode and in LPS-induced RAW264.7 cells. Through molecular dynamics simulation, we observed that Pa was bound to the catalytic pocket of Akt and effectively inhibited the biological activity of Akt. These results indicated that Pa significantly relieves LPS-induced ALI by activating the Akt/NF-κB signaling pathway.

In vitro and in vivo evaluation of organic anion-transporting polypeptide 2B1-mediated pharmacokinetic interactions by apple polyphenols

Organic anion-transporting polypeptide (OATP) 2B1 plays a critical role in the intestinal absorption of substrate drugs. Apple juice reportedly interacts with OATP2B1 substrate drugs. The purpose of this study was to investigate the effect of two apple polyphenols, phloretin and phloridzin, on OATP2B1-mediated substrate transport in vitro and to evaluate the effect of phloretin on rosuvastatin pharmacokinetics in rats.In vitro studies revealed that both polyphenols inhibited OATP2B1-mediated uptake of estrone-3-sulfate. Despite preincubation with phloretin and subsequent washing, the inhibitory effect was retained. Phloretin markedly decreased OATP2B1-mediated rosuvastatin uptake, with an IC₅₀ value of 3.6 μM.On coadministering rosuvastatin and phloretin in rats, the plasma concentration of rosuvastatin 10 min after oral administration was significantly lower than that in the vehicle group. The area under the plasma concentration-time curve of rosuvastatin was not significant, showing a tendency to decrease in the phloretin group when compared with the vehicle group. The in-situ rat intestinal loop study revealed the inhibitory effect of phloretin on rosuvastatin absorption.Phloretin has potent and long-lasting inhibitory effects on OATP2B1 in vitro. Phloretin may inhibit OATP2B1-mediated intestinal absorption of rosuvastatin; however, it failed to significantly impact the systemic exposure of rosuvastatin in rats.

Phloretin suppresses neuroinflammation by autophagy-mediated Nrf2 activation in macrophages

Background

Macrophages play a dual role in neuroinflammatory disorders such as multiple sclerosis (MS). They are involved in lesion onset and progression but can also promote the resolution of inflammation and repair of damaged tissue. In this study, we investigate if and how phloretin, a flavonoid abundantly present in apples and strawberries, lowers the inflammatory phenotype of macrophages and suppresses neuroinflammation.

Methods

Transcriptional changes in mouse bone marrow-derived macrophages upon phloretin exposure were assessed by bulk RNA sequencing. Underlying pathways related to inflammation, oxidative stress response and autophagy were validated by quantitative PCR, fluorescent and absorbance assays, nuclear factor erythroid 2–related factor 2 (Nrf2) knockout mice, western blot, and immunofluorescence. The experimental autoimmune encephalomyelitis (EAE) model was used to study the impact of phloretin on neuroinflammation in vivo and confirm underlying mechanisms.

Results

We show that phloretin reduces the inflammatory phenotype of macrophages and markedly suppresses neuroinflammation in EAE. Phloretin mediates its effect by activating the Nrf2 signaling pathway. Nrf2 activation was attributed to 5′ AMP-activated protein kinase (AMPK)-dependent activation of autophagy and subsequent kelch-like ECH-associated protein 1 (Keap1) degradation.

Conclusions

This study opens future perspectives for phloretin as a therapeutic strategy for neuroinflammatory disorders such as MS.

Trial registration

Not applicable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02194-z.

Phytochemical inhibitors of the NLRP3 inflammasome for the treatment of inflammatory diseases

The NLRP3 inflammasome holds a crucial role in innate immune responses. Pathogen- and danger-associated molecular patterns may initiate inflammasome activation and following inflammatory cytokine release. The inflammasome formation and its-associated activity are involved in various pathological conditions such as cardiovascular, central nervous system, metabolic, renal, inflammatory and autoimmune diseases. Although the mechanism behind NLRP3-mediated disorders have not been entirely illuminated, many phytochemicals and medicinal plants have been described to prevent inflammatory disorders. In the present review, we mainly introduced phytochemicals inhibiting NLRP3 inflammasome in addition to NLRP3-mediated diseases. For this purpose, we performed a systematic literature search by screening PubMed, Scopus, and Google Scholar databases. By compiling the data of phytochemical inhibitors targeting NLRP3 inflammasome activation, a complex balance between inflammasome activation or inhibition with NLRP3 as central player was pointed out in NLRP3-driven pathological conditions. Phytochemicals represent potential therapeutic leads, enabling the generation of chemical derivatives with improved pharmacological features to treat NLRP3-mediated inflammatory diseases.

Changes of type II collagenase biomarkers on IL-1β-induced rat articular chondrocytes

Osteoarthritis (OA) is characterized by progressive degeneration of cartilage, formation of cartilage at the cartilage edge, and remodeling of the subchondral bone. Pro-inflammatory cytokines [e.g., interleukin (IL)-1β] that induce inflammation and promote chondrocyte damage induce OA. Currently, the diagnosis of OA is commonly based on imaging examinations (e.g., X-ray) and evaluations of clinical symptoms; however, biomarkers that can effectively diagnose OA are currently not available. By studying the mechanism underlying OA cartilage injury and changes in the concentrations of the biomarkers procollagen type II carboxy-terminal propeptide (PIICP), collagen type-II C-telopeptide fragments (CTX-II), and type II collagen cleavage neoepitope (C2C) during pathogenesis, the present study established a theoretical basis for the evaluation and early diagnosis of OA. In an experiment, 10 ng/ml IL-1β was used to the treat chondrocyte-induced OA models in vitro for 0, 12, 24 and 48 h. Western blotting was used to detect the expression levels of matrix metalloproteinase (MMP)-3, MMP-13, and inducible nitric oxide synthase (iNOS) protein at each time-point. The concentrations of CTX-II, C2C, and PIICP in the cell culture supernatant were detected by ELISA kit. A biochemical kit was used to detect changes of nitric oxide (NO) in the cell culture supernatant. In addition, chondrocytes were treated with 10 ng/ml IL-1β for 0, 30, 60 and 90 min and the translocation and phosphorylation of the NF-κB pathway were investigated by western blotting. Following IL-1β stimulation, the NF-κB pathway was activated to increase the expression levels of MMPs and iNOS synthesis downstream of the pathway, resulting in an increased degradation of type II collagen (Col II). To sum up, pro-inflammatory IL-1β induced an OA chondrocyte model. During the development of OA, the expression of MMPs and NO increased and Col II was degraded.

Inhibition effect of Caragana sinica root extracts on Osteoarthritis through MAPKs, NF-κB signaling pathway

Osteoarthritis (OA) is a common joint disease characterized by degradation and inflammation of cartilage extracellular matrix. We aimed to evaluate the protective effect of Caragana sinica root (CSR) on interleukin (IL)-1β-stimulated rat chondrocytes and a monosodium iodoacetate (MIA)-induced model of OA. In vitro, cell viability of CSR-treated chondrocytes was measured by MTT assay. The mRNA expression of Matrix metallopeptidases (MMPs), a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) and extracellular matrix (ECM) were analyzed by quantitative real-time PCR (qRT-PCR). Moreover, the protein expression of MAPK (phosphorylation of EKR, JNK, p38), inhibitory kappa B (IκBα) and nuclear factor-kappa B (NF-κB p65) was detected by western blot analysis. In vivo, the production of nitric oxide (NO) was detected by Griess reagent, while those of inflammatory mediators, MMPs and ECM were detected by ELISA. The degree of OA was evaluated by histopathological analyses, Osteoarthritis Research Society International (OARSI) score and micro-CT analysis. CSR significantly inhibited the expression of MMPs, ADAMTSs and the degradation of ECM in IL-1β-stimulated chondrocytes. Furthermore, CSR significantly suppressed IL-1β-stimulated of MAPKs, NF-κB signaling pathway. In vivo, CSR and Indomethacin inhibited the production of inflammatory mediators, MMPs and degradation of ECM in MIA-induced model of OA. In addition, CSR improved the severity of OA. Taken together, these results suggest CSR is a potential therapeutic active agent in the treatment of OA.

In vitro anti-inflammatory potential of phloretin microemulsion as a new formulation for prospective treatment of vaginitis

Phloretin is a promising polyphenolic compound known for its anti-inflammatory properties, but its poor solubility and low bioavailability hinder its clinical applicability. Till current date, its potential in the treatment of vaginitis has not been explored, and only very few papers reported its formulation as nanoparticles to overcome its pharmaceutical challenges. Therefore, in the current study, phloretin was formulated in microemulsion of 11 nm size, and its in vitro anti-inflammatory properties were explored using histamine and IL-6 release inhibition assays, protease inhibition assay, and membrane stabilization potential. The anti-inflammatory properties of phloretin microemulsion were compared to the drug phloretin, and the reference standard non-steroidal anti-inflammatory drugs (NSAIDs). Results proved that both phloretin and phloretin microemulsion significantly inhibited the release of the inflammatory mediators histamine and IL-6, inhibited protease action, and exhibited membrane stabilization potential. Phloretin microemulsion exhibited comparable anti-inflammatory properties to the NSAIDs diclofenac and indomethacin, and, hence, it can be delineated as a promising therapeutic tool in topical treatment of vaginal inflammation.

Low-dose phloretin alleviates diabetic atherosclerosis through endothelial KLF2 restoration

We investigated whether low-dose phloretin served as daily dietary supplements could ameliorate diabetic atherosclerosis and the role of kruppel-like factor 2 (KLF2). HUVECs cultured in high glucose medium were treated with different concentrations of phloretin and KLF2 mRNA, and protein level was detected. Diabetes was induced using streptozotocin in Apoe−/- mice after which they were fed a high-cholesterol diet for 8 weeks. Diabetic mice injected with KLF2 shRNA-lentivirus or control virus were treated with 20 mg/kg phloretin. Glucose, lipid profile, aortic atheroma, and endothelial nitric oxide synthase (eNOS) expression were detected. Phloretin retained endothelial function by KLF2-eNOS activation under hyperglycemia. Low-dose phloretin helped with lipid metabolism, and blocked the acceleration of atherosclerosis in STZ-induced diabetic mice since the early stage, which was diminished by KLF2 knockdown. Low-dose phloretin exhibited athero-protective effect in diabetic Apoe−/- mice dependent on KLF2 activation. This finding makes phloretin for diabetic atherosclerosis.

Therapeutic Potential Low-Intensity Pulsed Ultrasound for Osteoarthritis: Pre-clinical and Clinical Perspectives

Osteoarthritis (OA), degeneration of cartilage associated with aging, lifestyle, and trauma, is one of the most common diseases that leads to lower quality of life and socioeconomic burden in the United States. Clinically, OA is initially managed by non-steroidal anti-inflammatory drugs, but eventually requires surgical intervention to reduce pain and increase function. Cartilage is a mechanotransductive tissue and requires a mechanical stimulus to sustain its mechanical and physiologic properties. Low-intensity pulsed ultrasound (LIPUS) is a cyclic acoustic wave that can provide essential mechanical stimuli to activate molecular and cellular pathways leading to chondrocyte proliferation, differentiation and activity, as well as to inhibit inflammatory pathways associated with OA. The activation of chondrocyte proliferation and inhibition of anti-inflammatory cytokines make LIPUS a potential therapy for mild to moderate OA. Although a few review articles have described the effects of ultrasound on chondrocytes and cartilage, there remains a need for a comprehensive analysis of our current understanding of the basic science and clinical status of the effects of low-intensity ultrasound on chondrocytes and cartilage and the implications of these studies on LIPUS as a therapeutic option for OA. This review analyzes recent literature describing the results of LIPUS using in vitro and in vivo pre-clinical models and clinical studies, as well as future directions for research.

Nifedipine inhibits oxidative stress and ameliorates osteoarthritis by activating the nuclear factor erythroid-2-related factor 2 pathway

Nifedipine is a voltage-gated calcium channel inhibitor widely used in the treatment of hypertension. Nifedipine has been reported to have antioxidant and anti-apoptotic effects and promotes cell proliferation. However, the effects of nifedipine on oxidative stress and apoptosis in osteoarthritic (OA) chondrocytes are still unclear. In this study, we sought to investigate whether nifedipine alleviates oxidative stress and apoptosis in OA through nuclear factor erythroid-2-related factor 2 (Nrf2) activation. The cytotoxicity of nifedipine against human chondrocytes was detected using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) kit, whereas mRNA and protein expression levels were measured using reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The oxidative stress level was analyzed by measuring reactive oxygen species (ROS), glutathione peroxidase (GSH-px), catalase (CAT) and superoxide dismutase (SOD) activities. The role of Nrf2 in the effect of nifedipine on OA was analyzed using an Nrf2 inhibitor brusatol (BR). The result showed that nifedipine inhibited the expression of matrix metalloprotein(MMP)-13, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, cyclooxygenase (COX)-2, inducible nitric oxide (NO) synthase (iNOS), and prostaglandin E2 (PGE2), as well as reduced ROS production in human OA chondrocytes, which was partially reversed by BR. Nifedipine prevented cartilage degeneration and contributed to the expression of Nrf-2 in chondrocytes. These results indicate that nifedipine inhibited inflammation and oxidative stress in chondrocytes via activation of Nrf-2/HO-1 signaling.

Dihydrochalcones: Methods of Acquisition and Pharmacological Properties-A First Systematic Review

Dihydrochalcones are a class of secondary metabolites, for which demand in biological and pharmacological applications is still growing. They posses several health-endorsing properties and, therefore, are promising candidates for further research and development. However, low content of dihydrochalcones in plants along with their low solubility and bioavailability restrict the development of these compounds as clinical therapeutics. Therefore, chemomicrobial and enzymatic modifications are required to expand their application. This review aims at analyzing and summarizing the methods of obtaining dihydrochalcones and of presenting their pharmacological actions that have been described in the literature to support potential future development of this group of compounds as novel therapeutic drugs. We have also performed an evaluation of the available literature on beneficial effects of dihydrochalcones with potent antioxidant activity and multifactorial pharmacological effects, including antidiabetic, antitumor, lipometabolism regulating, antioxidant, anti-inflammatory, antibacterial, antiviral, and immunomodulatory ones. In addition, we provide useful information on their properties, sources, and usefulness in medicinal chemistry.

Downregulating Akt/NF-κB signaling and its antioxidant activity with Loureirin A for alleviating the progression of osteoarthritis: In vitro and vivo studies

Osteoarthritis(OA) is one of the most common diseases in orthopedics. It is characterized by degeneration of articular cartilage and chronic inflammation. In this study, we aim to elucidate the mechanism of Loureirin A's therapeutic effect in OA progression. In vitro, Loureirin A pretreatment can significantly inhibit production of NO, PGE2, COX-2, TNF-α, iNOS andIL-6 induced by IL-1β in mouse articular chondrocytes. Moreover, Loureirin A suppressed the expression of matrix metalloproteinase-9(MMP-9), which leads to degradation of the extracellular matrix. The degradation of aggrecan and type II collagen protein in the extracellular matrix (ECM) stimulated by IL-1β was reversed. For signal pathway research, Loureirin A dramatically inhibited the phosphorylation of AKT and subsequent NF-κB entering into the nucleus caused by IL-1β in chondrocytes. Besides, a number of related indicators suggested that Loureirin A has a strong antioxidant activity in the treatment of osteoarthritis via increasing content of SOD2 and suppressing MDA and ROS. In addition, in vivo study demonstrated that Loureirin A could ameliorated the progression of OA in mice DMM model In conclusion, all results showed that Loureirin A may be a potential therapeutic candidate for the OA.

Inhibiting the PI3K/AKT/NF-κB signal pathway with nobiletin for attenuating the development of osteoarthritis: in vitro and in vivo studies

Osteoarthritis (OA), an age-related degenerative disease, is characterized by progressive degradation of the articular cartilage. There is increasing evidence that nobiletin (NOB) exerts special biological functions in a variety of diseases. However, whether it protects against OA remains unknown. In this study, we investigated the anti-inflammatory and chondroprotective effects of NOB on IL-1β-induced human OA chondrocytes and in the surgical DMM mice OA models. In vitro, NOB treatment completely suppressed the overproduction of pro-inflammatory mediators, including PGE2, NO, COX-2, iNOS, TNF-α and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, NOB exerted a potent inhibitory effect on the expression of MMP-13 and ADAMTS-5 as well as the degradation of aggrecan and collagen-II, which leads to the degradation of the extracellular matrix. Furthermore, NOB dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with NOB not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. In conclusion, our study suggests that NOB holds novel therapeutic potential for the treatment of OA.

Protective Effects of Sweroside on IL-1β-Induced Inflammation in Rat Articular Chondrocytes Through Suppression of NF-κB and mTORC1 Signaling Pathway

Sweroside (SW), as a bioactive herbal ingredient, has anti-inflammatory effects. Protective effects of SW on IL-1β-stimulated articular chondrocytes, however, has not been fully understood. This study was to explore the anti-inflammatory effects and further to investigate the possible mechanism underlying SW effect on IL-1β-stimulated rat articular chondrocytes. Rat articular chondrocytes were cultured with or without SW for 1 h, and then stimulated with IL-1β for 24 h. ELISA analysis was used to measure the production of NO and PGE2. Western blot was to detect the expression of iNOS and COX-2. Furthermore, the mRNA expression of MMP-1, MMP3, MMP13, and ADAMTS-5 were measured by q-PCR. These results demonstrated that SW significantly inhibited IL-1β-induced NO and PGE2 production, as well as MMP-1, MMP3, MMP13, and ADAMTS-5 mRNA expression. Moreover, SW also suppressed IL-1β-induced NF-κB activation and iκ-B degradation, S6K1 and S6 phosphorylation. In conclusion, these results strongly demonstrated that the anti-inflammatory activity of SW is in part mediated by suppressing NF-κB and mTORC1 signaling, which was expected to be a promising drug target of osteoarthritis therapy.

A Review of the Science of Colorful, Plant-Based Food and Practical Strategies for "Eating the Rainbow"

Over the past decades, thousands of published studies have amassed supporting recommendations to consume fruits and vegetables for physiological and psychological health. Newer research has emerged to suggest that these plant-based foods contain a plethora of not only vitamins and minerals, but perhaps, most importantly, phytonutrients. These phytonutrients have known pleiotropic effects on cellular structure and function, ultimately resulting in the modulation of protein kinases and subsequent epigenetic modification in a manner that leads to improved outcomes. Even though eating fruits and vegetables is a well-known feature of a healthy dietary pattern, population intakes continue to be below federal recommendations. To encourage consumers to include fruits and vegetables into their diet, an “eat by color” approach is proposed in this review. Although each individual food may have numerous effects based on its constituents, the goal of this simplified approach was to identify general patterns of benefits based on the preponderance of scientific data and known mechanisms of food-based constituents. It is suggested that such a consumer-oriented categorization of these plant-based foods may lead to greater recognition of their importance in the daily diet throughout the lifespan. Other adjunctive strategies to heighten awareness of fruits and vegetables are discussed.

Protective effects of ten oligostilbenes from Paeonia suffruticosa seeds on interleukin-1β-induced rabbit osteoarthritis chondrocytes

Background

Paeonia suffruticosa is an important traditional Chinese herb used to treat osteoarthritis (OA) and oligostilbenes are the main active ingredient of the seeds of P. suffruticosa. The monomer trans-resveratrol of this species was demonstrated to have chondroprotective effects as a lead compound for the treatment of osteoarthritis, but it has not been applied due to its low efficacy.

Methods

Oligostilbenes were isolated by chromatography and were identified by NMR and HPLC. A rabbit osteoarthritis chondrocyte model was induced by interleukin-1β and was treated with individual drugs to systematically evaluate their effects. Cell Counting Kit 8 was used to test their effects on cell viability, calculate EC₅₀ and plot a dose-response curve.Their effects on apoptosis were analyzed by Annexin V and PI staining, and the expression of chondrocyte-specific genes COL2A1, MMP13 and SOX9 was evaluated by real-time PCR.

Results

Paeonia suffruticosa seed extract could promote the cell viability of rabbit OA chondrocytes at low concentration and then ten oligostilbenes were isolated from it. Trans-oligostilbenes were better than their cis-forms, trimers and dimers were better than monomers for promoting the cell viability of rabbit osteoarthritis chondrocytes. None of the oligostilbenes was more effective than seed extract at the appropriate concentration; 1 μM oligostilbenes all showed various anti-apoptotic effects. Trans-gnetin H showed the best effect on proliferation and inhibition of MMP13 expression on OA chondrocytes, while trans-viniferin was most effective in promoting the expression of COL2A1 and SOX9.

Conclusions

Ten oligostilbenes from P. suffruticosa seed all have certain protective effects on OA chondrocytes at low concentration. The trans-viniferin and some trimers have the potential to be further developed for the treatment of osteoarthritis because they were more effective than resveratrol and diacerein. The synergistic effect that may exist between oligostilbenes also warrants further research.

Application of Metabolomics to Osteoarthritis: from Basic Science to the Clinical Approach

PURPOSE OF THE REVIEW

Osteoarthritis (OA) is a multifactorial and progressive disease affecting whole synovial joint. The extract pathogenic mechanisms and diagnostic biomarkers of OA remain unclear. In this article, we review the studies related to metabolomics of OA, discuss the biomarkers as a tool for early OA diagnosis. Furthermore, we examine the major studies on the application of metabolomics methodology in the complex context of OA and create a bridge from findings in basic science to their clinical utility.

RECENT FINDINGS

Recently, the tissue metabolomics signature permits a view into transitional phases between the healthy and OA joint. Both nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry-based metabolomics approaches have been used to interrogate the metabolic alterations that may indicate the complex progression of OA. Specifically, studies on alterations pertaining to lipids, glucose, and amino acid metabolism have aided in the understanding of the complex pathogenesis of OA. The discovery of identified metabolites could be important for diagnosis and staging of OA, as well as for the assessment of efficacy of new drugs.

Anti-inflammatory Mechanism Involved in 4-Ethylguaiacol-Mediated Inhibition of LPS-Induced Inflammation in THP-1 Cells

4-Ethylguaiacol, a common aroma compound of baijiu (a traditional Chinese alcoholic beverage), was assessed for its potential anti-inflammatory effects in an LPS-induced THP-1 cell model. To characterize the effect of 4-ethylguaiacol on the LPS-induced inflammatory response, the mRNA and protein expression of the TLR4-MAPKs-NF-κB-IκBα-AP-1, Nrf2-HO-1, and AMPK-SIRT1 pathways were monitored by ELISA, real-time PCR, and Western blotting. On the basis of the result, 4-ethylguaiacol exerted anti-inflammatory effects at doses of 10, 100, and 500 μM (the concentration of 4-ethylguaiacol in gujinggong baijiu is in the range of 1044 ± 44 to 1661 ± 63 μg/L) and significantly mitigated LPS-induced inflammation via activation of the Nrf2-HO-1 and AMPK-SIRT1 pathways and inhibition of NF-κB and AP-1 activation, thereby markedly inhibiting the activation of inflammasomes and down-regulating the production of inflammatory cytokines. These results indicated that 4-ethylguaiacol could reverse LPS-induced inflammatory responses and is a natural, potent anti-inflammatory component in baijiu.

Initial effects of inflammation-related cytokines and signaling pathways on the pathogenesis of post-traumatic osteoarthritis

The main pathological change in post-traumatic osteoarthritis (PTOA) is cartilage degeneration, which is closely related to inflammation and oxidative stress. Inflammation can cause degeneration of articular cartilage. Cartilage degeneration can also stimulate the progression of inflammation. It has been found that inflammatory cytokines can participate in the pathological process of cartilage degeneration through multiple signaling pathways, mainly mitogen-activated protein kinase, nuclear transcription factor kappa B, and Wnt–β-catenin signal transduction pathways. This review aimed at exploring the relationship between PTOA and inflammation-related cytokines by introducing the role of proinflammatory cytokines in chondrocyte destruction and extracellular matrix degradation.