Berberine ameliorates cartilage degeneration in interleukin-1β-stimulated rat chondrocytes and in a rat model of osteoarthritis via Akt signalling

Polydatin inhibits the IL-1β-induced inflammatory response in human osteoarthritic chondrocytes by activating the Nrf2 signaling pathway and ameliorates murine osteoarthritis

Osteoarthritis (OA), which is characterized by progressive degradation of the articular cartilage, is the most prevalent form of human arthritis. Accumulating evidence has shown that polydatin (PD) exerts special biological functions in a variety of diseases. However, whether it protects against OA development has remained unknown. Here, we investigated the anti-inflammatory and chondroprotective effects of PD on interleukin (IL)-1β-induced human osteoarthritic chondrocytes and in the surgical destabilization of medial meniscus mouse (DMM) OA models. In vitro, PD treatment completely suppressed the over-production of pro-inflammatory mediators, including prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), nitric oxide (NO), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, PD exerted a suppressive effect on the expression of matrix-degrading proteases, including matrix metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS-5), which leads to the degradation of the extracellular matrix (ECM). Meanwhile, specific inhibition of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) level by short-interfering RNA (siRNA) strongly reversed the anti-inflammatory and chondroprotective effects of PD in human OA chondrocytes. The protective effects of PD were also observed in vivo. In conclusion, our studies demonstrate that PD holds novel therapeutic potential for the development of OA.

Suppression of Lipogenesis via Reactive Oxygen Species-AMPK Signaling for Treating Malignant and Proliferative Diseases

AIMS

Systemic diseases often have common characteristics. The aim of this study was to investigate the feasibility of targeting common pathological metabolism to inhibit the progression of malignant and proliferative diseases.

RESULTS

Gefitinib-resistant (G-R) nonsmall-cell lung cancer (NSCLC) and rheumatoid arthritis (RA) were studied as conditions representative of malignant and proliferative diseases, respectively. Strong lipogenic activity and high expression of sterol regulatory element-binding protein 1 (SREBP1) were found in both G-R NSCLC cells and synovial fibroblasts from RA patients (RASFs). Berberine (BBR), an effective suppressor of SREBP1 and lipogenesis regulated through reactive oxygen species (ROS)/AMPK pathway, selectively inhibited the growth of G-R NSCLC cells and RASFs but not that of normal cells. It effectively caused mitochondrial dysfunction, activated ROS/AMPK pathway, and finally suppressed cellular lipogenesis and cell proliferation. Addition of ROS blocker, AMPK inhibitor, and palmitic acid significantly reduced the effect of BBR. In an in vivo study, treatment of BBR led to significant inhibition of mouse tumor xenograft growth and remarkably slowed down the development of adjuvant-induced arthritis in rats. Innovation and Conclusion: Targeting ROS/AMPK/lipogenesis signaling pathway selectively inhibited the growth of G-R NSCLC cells and the progress of RASFs in vitro and in vivo, which provides a new avenue for treating malignancies and proliferative diseases. Antioxid. Redox Signal. 28, 339-357.

miR-26a promoted endometrial epithelium cells (EECs) proliferation and induced stromal cells (ESCs) apoptosis via the PTEN-PI3K/AKT pathway in dairy goats

Changes in endometrial cell morphology and function are absolutely necessary for successful embryo implantation. In this study, miR-26a was widely expressed in dairy goats, and was found to be regulated by β-estradiol (E2) and progesterone (P4) in endometrial epithelium cells (EECs) as well as stromal cells (ESCs). Furthermore, miR-26a played a role in the regulation of cells proliferation and apoptosis by directly regulating PTEN and indirectly regulating the PI3K/AKT pathway in EECs but not in ESCs of dairy goats in vitro. In addition, miR-26a regulated the expression of osteopontin (OPN), vascular endothelial growth factor (VEGF), Cyclooxygenase-2 (COX-2), and prolactin (PRL) in endometrial cells. Therefore, we could get a conclusion that miR-26a had very complex and diverse functions in the endometrial cells during the development of endometrial receptivity in dairy goats. This study provided an efficient platform for studying the regulatory effect of miR-26a on endometrial cells during the development of endometrial receptivity in dairy goats.

The inhibition of PLCγ1 protects chondrocytes against osteoarthritis, implicating its binding to Akt

Previous studies have addressed the involvement of phosphoinositide-specifc phospholipase γ1 (PLCγ1) and protein kinase B (PKB/Akt) in osteoarthritis (OA) pathogenesis, but it is not ascertained the possibility of them to be potential targets for OA therapy. Here, through local intra-articular injection of PLCγ or Akt inhibitor in a rat OA model induced by anterior cruciate ligament transaction plus medial meniscus resection, the architecture of chondrocyte and matrix organization of articular cartilage were observed using histopathological assays and Aggrecan, Col2, PLCγ1, and Akt levels were detected using immunohistochemistry assays. By treatment of Akt or PLCγ inhibitor and transfection of different PLCγ1- or Akt-expressing vectors in rat OA model chondrocytes, Aggrecan, Col2, PLCγ1, p-PLCγ1, Akt, and p-Akt levels were detected using western blotting analysis. The binding between PLCγ1 and Akt was assessed with co-immunoprecipitation assays in human OA chondrocytes. These results showed that PLCγ inhibition protected chondrocytes against OA, but Akt inhibition did not dramatically aggravate OA progression. There were mutual antagonism and binding between PLCγ1 and Akt that could be regulated by their phosphorylation levels. Consequently, the data reveal that the inhibition of PLCγ1 may provide an attractive therapeutic target for OA therapy, implicating its binding to Akt.

Different roles of Akt and mechanistic target of rapamycin in serum‑dependent chondroprotection of human osteoarthritic chondrocytes

Despite various animal serums being used widely to culture chondrocytes, the regulatory mechanism of serum on chondrocyte activities has not been elucidated. In the present study, human osteoarthritis (OA) chondrocytes were used to perform in vitro investigations on the effect of different concentrations of bovine fetal serum on extracellular matrix synthesis, cell proliferation and autophagy using the Cell Counting Kit‑8 analysis, a laser‑scanning confocal microscope, and western blot analysis. The results demonstrated that 5% serum exerted a chondroprotective effect more than the other concentrations of serum, as it simultaneously promoted cell proliferation, autophagy, and ECM synthesis in human OA chondrocytes. Furthermore, the decreased mechanistic target of rapamycin (mTOR) and increased Akt were observed in 5% serum‑treated OA chondrocytes. Either mTOR or Akt inhibitor influenced the effect of 5% serum on cell proliferation and autophagy in human OA chondrocytes, which was associated with LC‑3B or B‑cell lymphoma-2 (Bcl‑2) signal molecules. Consistent with previous studies, the present study proposes that 5% serum promotes cell proliferation via the Akt/Bcl‑2 axis and induces autophagy via the mTOR/LC‑3B axis in human OA chondrocytes. Furthermore, the different roles of Akt and mTOR in the cell processes of human OA chondrocytes require consideration for preclinical and clinical therapy of OA.

Kaempferol Alleviates the Interleukin-1β-Induced Inflammation in Rat Osteoarthritis Chondrocytes via Suppression of NF-κB

Background

This study was designed to examine the anti-inflammatory and anti-osteoarthritis (OA) effects of kaempferol in rat articular chondrocytes stimulated with interleukin-1β.

Material/Methods

Rat articular chondrocytes cultures were treated with interleukin-1β alone or with kaempferol (25, 50, 100, and 200 μM) and interleukin-1β. The effect of kaempferol on chondrocyte cells viability was measured by MTT assay. The effect on prostaglandin E2 (PGE2) and nitric oxide (NO) level were also assessed using the ELISA and Griess reagent, respectively, for kaempferol activity. Moreover, the expression of iNOS, Cox-2 and activation of NF-κB under influence of kaempferol was also assessed by Western blot.

Results

Kaempferol treatment (up to 100 μM) in a concentration-dependent way caused reduction in the interleukin-1β-stimulated formations of PGE2 and NO. Kaempferol also upregulated the expression of iNOS and Cox-2 in interleukin-1β-stimulated rat OA chondrocytes. Additionally, kaempferol was found to inhibit the IκBα degradation and NF-κB activation in rat chondrocytes stimulated with interleukin-1β.

Conclusions

Kaempferol significantly caused reduction in interleukin-1β-stimulated pro-inflammatory mediators in rat OA chondrocytes by inhibiting the NF-κB pathway. These results suggest that kaempferol had significant anti-inflammatory and anti-arthritis effects. Thus, kaempferol, as a novel therapeutic active agent, may prevent, stop, or retard the progression of OA.

Berberine promotes ischemia-induced angiogenesis in mice heart via upregulation of microRNA-29b

BACKGROUND

Berberine has several preventive effects on cardiovascular diseases. Increased expression of miR-29b has been reported to attenuate cardiac remodeling after myocardial infarction (MI). We hypothesized that berberine via an miR-29b-dependent mechanism promotes angiogenesis and improves heart functions in mice after MI.

METHODS

The MI model was established in mice by ligation of left anterior descending coronary artery. The expression of miR-29b was examined by RT-qPCR. Angiogenesis was assessed by immunohistochemistry.

RESULTS

Berberine increased miR-29b expression and promoted cell proliferations and migrations in cultured endothelial cells, which were abolished by miR-29b antagomir or AMP-activated protein kinase inhibitor compound C. In mice following MI, administration of berberine significantly increased miR-29b expressional level, promoted angiogenesis, reduced infarct size, and improved heart functions after 14 postoperative days. Importantly, these in vivo effects of berberine were ablated by antagonism of miR-29b.

CONCLUSION

Berberine via upregulation of miR-29b promotes ischemia-induced angiogenesis and improves heart functions.

miR-182 aids in receptive endometrium development in dairy goats by down-regulating PTN expression

Increasing evidence has shown that miRNAs play important roles in endometrium development during the menstrual cycle in humans and many other animals. Our previous data indicated that miR-182 levels increase 15.55-fold and pleiotrophin (PTN) levels decrease 20.97-fold in the receptive endometrium (RE, D15) compared with the pre-receptive endometrium (PE, D5) in dairy goats. The present study shows that miR-182 is widely expressed in different tissues of dairy goats and that its expression levels are regulated by E2 and P4 in endometrial epithelium cells (EECs). We confirmed that PTN is a target of miR-182 and that miR-182 regulates the protein levels of AKT, Bcl-2, FAS, MAPK, Caspase-3 and SP1 in EECs. Furthermore, miR-182 up-regulates or maintains the expression levels of osteopontin (OPN), cyclooxygenase-2 (COX-2) and prolactin receptor (PRLR) in EECs, suggesting that miR-182 is an important regulatory factor in the construction of endometrial receptivity in dairy goats. In conclusion, miR-182 participates in the development of endometrial receptivity by down-regulating PTN and affecting the expression of select apoptosis-related genes and increasing or maintaining the expression levels of OPN, COX-2 and PRLR in the EECs of dairy goats.

Tert-butylhydroquinone promotes angiogenesis and improves heart functions in rats after myocardial infarction

BACKGROUND

Hypertension is an increased risk of heart failure and acute myocardial infarction (MI). Tert-butylhydroquinone (tBHQ), as an antioxidant, shows multiple cardioprotective actions including the reduction in blood pressure. The aim of this study was to investigate whether and how tBHQ improves heart functions in rats.

METHODS

The MI model was established in WKY and spontaneously hypertensive rats (SHRs) by ligation of left anterior descending coronary artery. Akt phosphorylation was examined by western blot in human umbilical vein endothelial cells (HUVECs) or in rats. Angiogenesis was assessed by immunohistochemistry and immunofluorescence. Heart function was determined by echocardiography.

RESULTS

tBHQ increased Akt phosphorylation, promoted cell proliferations and migrations in HUVECs, which were abolished by Akt inhibitor wortmannin. In SHRs following MI, administration of tBHQ significantly increased Akt phosphorylation, promoted angiogenesis, reduced infarct size, and improved heart functions after 14 postoperative days. Importantly, these in vivo effects of tBHQ were ablated by wortmannin in SHRs.

CONCLUSION

tBHQ via Akt activation promotes ischemia-induced angiogenesis and improves heart functions in hypertensive rats. In perspectives, the application of tBHQ should be considered in patients with ischemic diseases such as MI and stroke.

Berberine confers neuroprotection in coping with focal cerebral ischemia by targeting inflammatory cytokines

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Berberine reduces brain edema and infarct volume through regulation of inflammatory responses in focal cerebral ischemia.

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Berberine increases the expression of anti-inflammatory cytokines after ischemic stroke.

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Berberine contributes to recovery of motor function after focal cerebral ischemia.

Scope

Existing research indicates that anti-inflammatory and antioxidant properties of berberine play major roles in coping with oxidative stress in neurodegenerative diseases, but it is not known if this isoquinoline alkaloid affects inflammatory cytokines such as interleukin 10 in focal cerebral ischemia.

Methods and results

Male Wistar rats (10 weeks old) were treated with 40 mg/kg concentration of berberine 1 h after focal cerebral ischemia and the anti-inflammatory properties of berberine were evaluated by immunohistochemical analysis, water content measure and behavioral tests. Evaluation of infarct volume was performed by TTC staining. Immunohistochemistry and behavioral assessment indicated recovery in treatment group compared to only ischemia group. The infarct volume decreased in treatment group compared to ischemia group. Berberine administration significantly decreased brain edema and contributed to the restoration of motor function. Moreover, berberine potently contributed to neuroprotection in motor area through downregulation of pro-inflammatory cytokines and upregulation of anti-inflammatory cytokines.

Conclusions

These findings confirm the validity of berberine as a potent anti-inflammatory agent in treatment of ischemic stroke.

AMPK deficiency in chondrocytes accelerated the progression of instability-induced and ageing-associated osteoarthritis in adult mice

Osteoarthritis (OA) is a progressive degenerative disease of the joints that is associated with both joint injury and ageing. Here, we investigated the role of the energy sensor AMP-activated protein kinase (AMPK) in maintaining a healthy state of articular cartilage and in OA development. Using cartilage-specific, tamoxifen-inducible AMPKα1 conditional knockout (AMPKα1 cKO), AMPKα2 conditional knockout (AMPKα2 cKO) and AMPKα1α2 conditional double knockout (AMPKα cDKO) mice, we found that compared with wild-type (WT) littermates, mutant mice displayed accelerated severity of surgically induced OA, especially AMPKα cDKO mice. Furthermore, male but not female AMPKα cDKO mice exhibited severely spontaneous ageing-associated OA lesions at 12 months of age. The chondrocytes isolated from AMPKα cDKO mice resulted in an enhanced interleukin-1β (IL-1β)-stimulated catabolic response. In addition, upregulated expression of matrix metalloproteinase-3 (MMP-3), MMP-13 and phospho-nuclear factor-κB (phospho-NF-κB) p65 and increased levels of apoptotic markers were detected in the cartilage of AMPKα cDKO mice compared with their WT littermates in vivo. Thus, our findings suggest that AMPK activity in chondrocytes is important in maintaining joint homeostasis and OA development.

Insights into the Action Mechanisms of Traditional Chinese Medicine in Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by articular cartilage destruction, synovial inflammation, and osteophyte formation. No effective treatments are available. The current pharmacological medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesics, accompanied by possible adverse effects, might ameliorate OA symptoms. But they do not arrest the progression of OA. Traditional Chinese medicine (TCM) provides medical value by modification of disease and symptoms in OA. Valuable work on exploring TCM merits for OA patients has been investigated using modern technologies, although the complicated interacting network among the numerous components indicates the uncertainty of target specification. This review will provide an overview of the action mechanism of TCM in the last 5 years, discussing the TCM activities of anti-inflammation, antiapoptosis, antioxidation, anticatabolism, and proliferation in OA. TCM is a proposed medical option for OA treatment.

WITHDRAWN: Resveratrol increases microRNA-130a expression to promote angiogenesis and improve heart functions in mice after myocardial infarction

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Berberis Vulgaris and Berberine: An Update Review

Berberine is an isoquinoline alkaloid present in several plants, including Coptis sp. and Berberis sp. Berberine is a customary component in Chinese medicine, and is characterized by a diversity of pharmacological effects. An extensive search in electronic databases (PubMed, Scopus, Ovid, Wiley, ProQuest, ISI, and Science Direct) were used to identify the pharmacological and clinical studies on Berberis vulgaris and berberine, during 2008 to 2015, using 'berberine' and 'Berberis vulgaris' as search words. We found more than 1200 new article studying the properties and clinical uses of berberine and B. vulgaris, for treating tumor, diabetes, cardiovascular disease, hyperlipidemia, inflammation, bacterial and viral infections, cerebral ischemia trauma, mental disease, Alzheimer disease, osteoporosis, and so on. In this article, we have updated the pharmacological effects of B. vulgaris and its active constituent, berberine. Copyright © 2016 John Wiley & Sons, Ltd.

Berberine promotes proliferation of sodium nitroprusside-stimulated rat chondrocytes and osteoarthritic rat cartilage via Wnt/β-catenin pathway

Berberine chloride (BBR) is an isoquinoline derivative alkaloid isolated from medicinal herbs, including Coptis chinensis and Berberis aristate. This compound plays significant roles in the treatment of osteoarthritis (OA). The purpose of this study was to investigate the effects of BBR on the proliferation of sodium nitroprusside (SNP)-stimulated chondrocytes in vitro, the articular cartilage in a rat OA model, as well as to discuss the molecular mechanisms underlying these effects. In vitro, we demonstrated that BBR led to cell proliferation, increased the cell population in S-phase and decreased that in G0/G1-phase; moreover, the F-actin remodeling in SNP-stimulated chondrocytes were prevented. In addition, BBR markedly up-regulated β-catenin, c-Myc, and cyclin D1 expression of genes and proteins, and down-regulated glycogen synthase kinase-3β (GSK-3β) and matrix metalloproteinase-7 (MMP-7) expression. Notably, inhibition of the Wnt/β-catenin pathway by XAV939 partially blocked these effects. The in vivo results suggested that BBR promoted β-catenin protein level and enhanced proliferating cell nuclear antigen (PCNA) expression in osteoarthritic rat cartilage. In conclusion, these findings indicate that BBR promotes SNP-stimulated chondrocyte proliferation by promoting G1/S phase transition and synthesis of PCNA in cartilage through activation of Wnt/β-catenin signaling pathway.

A Network Pharmacology Approach to Uncover the Pharmacological Mechanism of XuanHuSuo Powder on Osteoarthritis

As the most familiar type of arthritis and a chronic illness of the joints, Osteoarthritis (OA) affects a great number of people on the global scale. XuanHuSuo powder (XHSP), a conventional herbal formula from China, has been extensively applied in OA treatment. Nonetheless, its pharmacological mechanism has not been completely expounded. In this research, a network pharmacology approach has been chosen to study the pharmacological mechanism of XHSP on OA, and the pharmacology networks were established based on the relationship between four herbs found in XHSP, compound targets, and OA targets. The pathway enrichment analysis revealed that the significant bioprocess networks of XHSP on OA were regulation of inflammation, interleukin-1β (IL-1β) production and nitric oxide (NO) biosynthetic process, response to cytokine or estrogen stimuli, and antiapoptosis. These effects have not been reported previously. The comprehensive network pharmacology approach developed by our research has revealed, for the first time, a connection between four herbs found in XHSP, corresponding compound targets, and OA pathway systems that are conducive to expanding the clinical application of XHSP. The proposed network pharmacology approach could be a promising complementary method by which researchers might better evaluate multitarget or multicomponent drugs on a systematic level.

Overexpression of microRNA-634 suppresses survival and matrix synthesis of human osteoarthritis chondrocytes by targeting PIK3R1

Osteoarthritis (OA) is a degenerative disease characterized by deterioration of articular cartilage. Recent studies have demonstrated the importance of some microRNAs in cartilage damage. The aim of this study was to identify and characterize the expression of microRNA-634 (miR-634) in normal and OA chondrocytes, and to determine its role in OA pathogenesis. Human normal and OA chondrocytes obtained from patients were cultured in vitro. Transfection with miR-634 mimic or inhibitor was employed to investigate the effect of miR-634 on chondrocyte survival and matrix synthesis, and to identify miR-634 target. The results indicated that miR-634 was expressed at lower level in high grade OA chondrocyte compared with normal chondrocytes. Overexpression of miR-634 could inhibit cell survival and matrix synthesis in high grade OA chondrocytes. Furthermore, miR-634 targeted PIK3R1 gene that encodes the regulatory subunit 1 of class I PI3K (p85α) and exerted its inhibitory effect on the phosphorylation of Akt, mTOR, and S6 signal molecules in high grade OA chondrocytes. Therefore, the data suggested that miR-634 could suppress survival and matrix synthesis of high grade OA chondrocytes through targeting PIK3R1 gene to modulate the PI3K/Akt/S6 and PI3K/Akt/mTOR/S6 axes, with important implication for validating miR-634 as a potential target for OA therapy.

MicroRNA-30a promotes extracellular matrix degradation in articular cartilage via downregulation of Sox9

OBJECTIVES

Sox9 has recently been reported to be a key mediator during cartilage degradation in osteoarthritis (OA). Our aim was to clarify the role of microRNA-30a (miR-30a) and its target gene Sox9 in regulation of extracellular matrix (ECM) degradation in OA.

MATERIALS AND METHODS

Expression of miR-30a in cartilage tissues and in primary chondrocytes from healthy and OA donors, was determined by real-time PCR, and levels of Sox9 mRNA and protein were analyzed by real-time PCR and western blotting, respectively. Subsequently, the target of miR-30a was predicted by bioinformatics and confirmed using a luciferase assay. Expression of ECM-related genes was determined by tissue-specific staining, immunofluorescence, real-time PCR, and western blotting. The role of miR-30a in OA was examined in vivo using a collagenase-induced OA rat model.

RESULTS

miR-30a was significantly upregulated and Sox9 was downregulated in primary chondrocytes from cartilage taken from OA donors compared to healthy controls. We showed that miR-30a specifically bound to the 3' UTR of Sox9, and overexpression of miR-30a downregulated expression levels of Sox9, proteoglycan aggrecan, and Col II compared to those induced by small interfering RNA transfection to knockdown Sox9. miR-30a inhibition reversed the effects of ECM degradation in vitro and in vivo.

CONCLUSIONS

miR-30a acts as a virulence MRA in OA, promoting ECM degradation by targeting Sox9 and by modulating activity of its downstream effectors Col II and proteoglycan aggrecan.

In vivo anti-apoptosis activity of novel berberine-loaded chitosan nanoparticles effectively ameliorates osteoarthritis

Berberine chloride (BBR) is an isoquinoline alkaloid that possesses promising protective efficacies against osteoarthritis (OA). Nevertheless, the therapeutic agent of this substance in OA is limited by its poor aqueous solubility, low bioavailability and short biological half-life. In this study, chitosan (CS)-based nanoparticles were prepared for the sustained release of BBR. Novel BBR-loaded chitosan nanoparticles (CNs) were successfully synthesized by the ionic cross-linking method. BBR-loaded CNs were spherical and homogeneous in shape. Moreover, they exhibited good stability and had ideal releasing profile in vitro. After intra-articular injection of BBR-loaded CNs, the level of BBR in rat plasma decreased and the retention time in synovial fluid increased compared with free BBR solution. In vivo evaluation of BBR-loaded CNs further showed higher anti-apoptosis activity in the treatment of OA compared with BBR solution at equivalent concentration. This result was evidenced by the changes of gross morphology and histological analyses in rat articular cartilage, TUNEL assay, quantitative real-time polymerase chain reaction, Western blot, and immunohistochemical analyses of caspase-3, Bcl-2 and Bax expressions. Given these results, BBR-loaded CNs are potential therapeutic agents for OA.

Deletion of the PH-domain and Leucine-rich Repeat Protein Phosphatase 1 (Phlpp1) Increases Fibroblast Growth Factor (Fgf) 18 Expression and Promotes Chondrocyte Proliferation

Endochondral ossification orchestrates formation of the vertebrate skeleton and is often induced during disease and repair processes of the musculoskeletal system. Here we show that the protein phosphatase Phlpp1 regulates endochondral ossification. Phlpp1 null mice exhibit decreased bone mass and notable changes in the growth plate, including increased BrdU incorporation and matrix production. Phosphorylation of known Phlpp1 substrates, Akt2, PKC, and p70 S6 kinase, were enhanced in ex vivo cultured Phlpp1(-/-) chondrocytes. Furthermore, Phlpp1 deficiency diminished FoxO1 levels leading to increased expression of Fgf18, Mek/Erk activity, and chondrocyte metabolic activity. Phlpp inhibitors also increased matrix content, Fgf18 production and Erk1/2 phosphorylation. Chemical inhibition of Fgfr-signaling abrogated elevated Erk1/2 phosphorylation and metabolic activity in Phlpp1-null cultures. These results demonstrate that Phlpp1 controls chondrogenesis via multiple mechanisms and that Phlpp1 inhibition could be a strategy to promote cartilage regeneration and repair.

Taraxasterol inhibits IL-1β-induced inflammatory response in human osteoarthritic chondrocytes

Osteoarthritis (OA), a chronic degenerative joint disease, is a leading cause of disability among elderly patients. Taraxasterol, a pentacyclic-triterpene isolated from Taraxacum officinale, has been shown to have anti-inflammatory effects. However, the protective effect of taraxasterol on OA remains unclear. In order to provide a scientific basis for the applicability of taraxasterol in OA, the anti-inflammatory effects of taraxasterol on IL-1β-stimulated osteoarthritic chondrocytes were investigated. Chondrocytes were pretreated with taraxasterol 1h before IL-1β treatment. The productions of MMP-1, MMP3, MMP13, PGE2 and NO were measured by ELISA and Griess reaction. The expression of COX-2, iNOS, and NF-κB was detected by western blot analysis. Our results demonstrated that taraxasterol dose-dependently suppressed MMP-1, MMP3, MMP13, PGE2 and NO production induced by IL-1β. The expression of COX-2 and iNOS was also inhibited by taraxasterol. Western blot analysis showed that taraxasterol suppressed IL-1β-induced NF-κB activation in a dose-dependent manner. Taken together, we found that taraxasterol protected human chondrocytes by inhibiting MMPs, NO and PGE2 production. Taraxasterol may be a useful agent for prevention and treatment of OA.

Protein kinase B and extracellular signal-regulated kinase contribute to the chondroprotective effect of morroniside on osteoarthritis chondrocytes

Despite extensive studies on the multifaceted roles of morroniside, the main active constituent of iridoid glycoside from Corni Fructus, the effect of morroniside on osteoarthritis (OA) chondrocytes remains poorly understood. Here, we investigated the influence of morroniside on cultured human OA chondrocytes and a rat experimental model of OA. The results showed that morroniside enhanced the cell viability and the levels of proliferating cell nuclear antigen expression (PCNA), type II collagen and aggrecan in human OA chondrocytes, indicating that morroniside promoted chondrocyte survival and matrix synthesis. Furthermore, different doses of morroniside activated protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) in human OA chondrocytes, and in turn, triggered AKT/S6 and ERK/P70S6K/S6 pathway, respectively. The PI3K/AKT inhibitor LY294002 or the MEK/ERK inhibitor U0126 attenuated the effect of morroniside on human OA chondrocytes, indicating that the activation of AKT and ERK contributed to the regulation of morroniside in human OA chondrocytes. In addition, the intra-articular injection of morroniside elevated the level of proteoglycans in cartilage matrix and the thickness of articular cartilage in a rat experimental model of OA, with the increase of AKT and ERK activation. As a consequence, morroniside has chondroprotective effect on OA chondrocytes, and may have the therapeutic potential for OA treatment.

Rosiglitazone via PPARγ-dependent suppression of oxidative stress attenuates endothelial dysfunction in rats fed homocysteine thiolactone

To explore whether rosiglitazone (RSG), a selective peroxisome proliferator-activated receptor γ (PPARγ) agonist, exerts beneficial effects on endothelial dysfunction induced by homocysteine thiolactone (HTL) and to investigate the potential mechanisms. Incubation of cultured human umbilical vein endothelial cells with HTL (1 mM) for 24 hrs significantly reduced cell viabilities assayed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, as well as enhanced productions of reactive oxygen species, activation of nuclear factor kappa B, and increased intercellular cell adhesion molecule-1 secretion. Pre-treatment of cells with RSG (0.001–0.1 mM), pyrollidine dithiocarbamate (PDTC, 0.1 mM) or apocynin (0.1 mM) for 1 hr reversed these effects induced by HTL. Furthermore, co-incubation with GW9662 (0.01 mM) abolished the protective effects of RSG on HTL-treated cells. In ex vivo experiments, exposure of isolated aortic rings from. rats to HTL (1 mM) for 1 hr dramatically impaired acetylcholine-induced endothelium-dependent relaxation, reduced release of nitric oxide and activity of superoxide dismutase, and increased malondialdehyde content in aortic tissues. Preincubation of aortic rings with RSG (0.1, 0.3, 1 mM), PDTC or apocynin normalized the disorders induced by HTL. In vivo analysis indicated that administration of RSG (20 mg/kg/d) remarkably suppressed oxidative stress and prevented endothelial dysfunction in rats fed HTL (50 mg/kg/d) for 8 weeks. RSG improves endothelial functions in rats fed HTL, which is related to PPARγ-dependent suppression of oxidative stress.

Astragalin inhibits IL-1β-induced inflammatory mediators production in human osteoarthritis chondrocyte by inhibiting NF-κB and MAPK activation

Astragalin, a bioactive component isolated from Rosa agrestis, has been described to exhibit anti-inflammatory activity. The aim of this study was to investigate the anti-inflammatory effects and the underlying mechanisms of astragalin on IL-1β-stimulated human osteoarthritis chondrocyte. The production of NO and PGE2 was detected by Griess reaction and ELISA. The expression of iNOS and COX-2 was detected by western blotting. The expression of NF-κB and MAPKs was detected by western blot analysis. We found that astragalin dose-dependently inhibited IL-1β-induced NO and PGE2 production, as well as iNOS and COX-2 expression. Meanwhile, western blot analysis showed that astragalin inhibited IL-1β-induced NF-κB and MAPK activation in human osteoarthritis chondrocyte. In addition, astragalin was found to activate PPAR-γ. The inhibition of astragalin on IL-1β-induced NO and PGE2 production can be reversed by PPAR-γ antagonist GW9662. Astragalin suppressed IL-1β-induced inflammatory mediators via activating PPAR-γ, which subsequently inhibited IL-1β-induced NF-κB and MAPK activation. Astragalin may be a potential agent in the treatment of osteoarthritis.