Psoralen Protects Chondrocytes, Exhibits Anti-Inflammatory Effects on Synoviocytes, and Attenuates Monosodium Iodoacetate-Induced Osteoarthritis

Colon-targeted oral nanoliposomes loaded with psoralen alleviate DSS-induced ulcerative colitis

Oral administration, while convenient, but complex often faces challenges due to the complexity of the digestive environment. In this study, we developed a nanoliposome (NLP) encapsulating psoralen (P) and coated it with chitosan (CH) and pectin (PT) to formulate PT/CH-P-NLPs. PT/CH-P-NLPs exhibit good biocompatibility, superior to liposomes loaded with psoralen and free psoralen alone. After oral administration, PT/CH-P-NLPs remain stable in the stomach and small intestine, followed by a burst release of psoralen after reaching the slightly alkaline and gut microbiota-rich colon segment. In the DSS-induced ulcerative colitis of mice, PT/CH-P-NLPs showed significant effects on reducing inflammation, mitigating oxidative stress, protecting the integrity of the colon mucosal barrier, and modulating the gut microbiota. In conclusion, the designed nanoliposomes demonstrated the effective application of psoralen in treating ulcerative colitis.

Natural linear coumarin-heterocyclic conjugates: A review of their roles in phytotherapy

Heterocycle conjugates provide a fresh investigative scope to find novel molecules with enhanced phytotherapeutic characteristics. Coumarin-based products are widely used in the synthesis of several compounds with biological and medicinal properties since they are naturally occurring heterocycles with a broad dispersion. The investigation of coumarin-based phytochemicals with annulated heterocyclic rings is a promising approach to discovering novel conjugates with significant phytotherapeutic attributes. Due to the applicable coumarin extraction processes, a range of linear coumarin-heterocyclic conjugates were isolated from different natural resources and exhibited remarkable therapeutic efficacy. This review highlights the phytotherapeutic potential and origins of various natural linear coumarin-heterocyclic conjugates. We searched several databases, including Science Direct, Web of Science, Springer, Google Scholar, and PubMed. After sieving, we ultimately identified and included 118 pertinent studies published between 2000 and the middle of 2023. This will inspire medicinal chemists with extremely insightful ideas for designing and synthesizing therapeutically active lead compounds in the future that are built on the pharmacophores of coumarin-heterocyclic conjugates and have significant therapeutic attributes.

Effect of P. corylifolia on the pharmacokinetic profile of tofacitinib and the underlying mechanism

This work aimed to explore the mechanisms underlying the interaction of the active furanocoumarins in P. corylifolia on tofacitinib both in vivo and in vitro. The concentration of tofacitinib and its metabolite M8 was determined using UPLC-MS/MS. The peak area ratio of M8 to tofacitinib was calculated to compare the inhibitory ability of furanocoumarin contained in the traditional Chinese medicine P. corylifolia in rat liver microsomes (RLMs), human liver microsomes (HLMs) and recombinant human CYP3A4 (rCYP3A4). We found that bergapten and isopsoralen exhibited more significant inhibitory activity in RLMs than other furanocoumarins. Bergapten and isopsoralen were selected to investigate tofacitinib drug interactions in vitro and in vivo. Thirty rats were randomly allocated into 5 groups (n = 6): control (0.5% CMC-Na), low-dose bergapten (20 mg/kg), high-dose bergapten (50 mg/kg), low-dose isopsoralen (20 mg/kg) and ketoconazole. 10 mg/kg of tofacitinib was orally intervented to each rat and the concentration level of tofacitinib in the rats were determined by UPLC-MS/MS. More imporrantly, the results showed that bergapten and isopsoralen significantly inhibited the metabolism of tofacitinib metabolism. The AUC(0-t), AUC(0-∞), MRT(0-t), MRT(0-∞) and Cmax of tofacitinib increased in varying degrees compared with the control group (all p < 0.05), but CLz/F decreased in varying degrees (p < 0.05) in the different dose bergapten group and isopsoralen group. Bergapten, isopsoralen and tofacitinib exhibit similar binding capacities with CYP3A4 by AutoDock 4.2 software, confirming that they compete for tofacitinib metabolism. P. corylifolia may considerably impact the metabolism of tofacitinib, which can provide essential information for the accurate therapeutic application of tofacitinib.

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.

Exploring the mechanism and phytochemicals in Psoraleae Fructus-induced hepatotoxicity based on RNA-seq, in vitro screening and molecular docking

Psoraleae Fructus (PF) is a widely-used herb with diverse pharmacological activities, while its related hepatic injuries have aroused public concerns. In this work, a systematic approach based on RNA sequencing (RNA-seq), high-content screening (HCS) and molecular docking was developed to investigate the potential mechanism and identify major phytochemicals contributed to PF-induced hepatotoxicity. Animal experiments proved oral administration of PF water extracts disturbed lipid metabolism and promoted hepatic injuries by suppressing fatty acid and cholesterol catabolism. RNA-seq combined with KEGG enrichment analysis identified mitochondrial oxidative phosphorylation (OXPHOS) as the potential key pathway. Further experiments validated PF caused mitochondrial structure damage, mtDNA depletion and inhibited expressions of genes engaged in OXPHOS. By detecting mitochondrial membrane potential and mitochondrial superoxide, HCS identified bavachin, isobavachalcone, bakuchiol and psoralidin as most potent mitotoxic compounds in PF. Moreover, molecular docking confirmed the potential binding patterns and strong binding affinity of the critical compounds with mitochondrial respiratory complex. This study unveiled the underlying mechanism and phytochemicals in PF-induced liver injuries from the view of mitochondrial dysfunction.

Phytochemical and Pharmacological Aspects of Psoralen - A Bioactive Furanocoumarin from Psoralea corylifolia Linn

Since long ago, medicinal plants have played a vital role in drug discovery. Being blessed and rich in chemovars with diverse scaffolds, they have unique characteristics of evolving based on the need. The World Health Organization also mentions that medicinal plants remain at the center for meeting primary healthcare needs as the population relies on them. The plant-derived natural products have remained an attractive choice for drug development owing to their specific biological functions relevant to human health and also the high degree of potency and specificity they offer. In this context, one such esteemed phytoconstituent with inexplicable biological potential is psoralen, a furanocoumarin. Psoralen was the first constituent isolated from the plant Psoralea corylifolia, commonly known as Bauchi. Despite being a life-saver for psoriasis, vitiligo, and leukoderma, it also showed immense anticancer, anti-inflammatory, and anti-osteoporotic potential. This review brings attention to the possible application of psoralen as an attractive target for rational drug design and medicinal chemistry. It discusses the various methods for the total synthesis of psoralen, its extraction, the pharmacological spectrum of psoralen, and the derivatization done on psoralen.

Psoralen synergizes with exosome-loaded SPC25 to alleviate senescence of nucleus pulposus cells in intervertebral disc degeneration

OBJECTIVE

To explore the mechanism of psoralen synergized with exosomes (exos)-loaded SPC25 on nucleus pulposus (NP) cell senescence in intervertebral disc degeneration (IVDD).

METHODS

IVDD cellular models were established on NP cells by tert-butyl hydroperoxide (TBHP) induction, followed by the treatment of psoralen or/and exos from adipose-derived stem cells (ADSCs) transfected with SPC25 overexpression vector (ADSCs-oe-SPC25-Exos). The viability, cell cycle, apoptosis, and senescence of NP cells were examined, accompanied by the expression measurement of aggrecan, COL2A1, Bcl-2, Bax, CDK2, p16, and p21.

RESULTS

After TBHP-induced NP cells were treated with psoralen or ADSCs-oe-SPC25-Exos, cell proliferation and the expression of aggrecan, COL2A1, Bcl-2, and CDK2 were promoted; however, the expression of Bax, p16, p21, and inflammatory factors was decreased, and cell senescence, cycle arrest, and apoptosis were inhibited. Of note, psoralen combined with ADSCs-oe-SPC25-Exos further decelerated NP cell senescence and cycle arrest compared to psoralen or ADSCs-oe-SPC25-Exos alone.

CONCLUSION

Combined treatment of psoralen and ADSCs-oe-SPC25-Exos exerted an alleviating effect on NP cell senescence, which may provide an insightful idea for IVDD treatment.

SNORC knockdown alleviates inflammation, autophagy defect and matrix degradation of chondrocytes in osteoarthritis development

Excessive inflammation and autophagy defect of chondrocytes play important roles in the pathological process of osteoarthritis (OA). The present study aimed to clarify the roles of small novel rich in cartilage (SNORC) in these pathological changes of chondrocytes in OA. Bioinformatics analysis of GEO dataset GSE207881 displayed that SNORC was a potential biomarker for OA. As confirmed by quantitative real-time PCR, immunohistochemical staining and western blotting, SNORC was significantly up-regulated in cartilage of OA rat model and interleukin (IL)-1β-stimulated primary rat articular chondrocytes in contrast to their corresponding normal control. Knocking down SNORC in IL-1β-induced chondrocytes obviously suppressed the production of nitric oxide (NO), IL-6, tumor necrosis factor (TNF)-α and prostaglandin E2 (PGE2) to alleviate inflammation, and reduced the protein levels of a disintegrin and metalloproteinase with thrombospondin 5 (ADAMTS5) and matrix metallopeptidase (MMP)13 and elevated collagen type 2 alpha 1 (COL2A1) level to improve matrix degradation. Down-regulation of SNORC increased Beclin1 expression and LC3II/LC3I ratio, but suppressed p62 expression to restore impaired autophagy in IL-1β-induced chondrocytes. Moreover, down-regulating SNORC mitigated mitochondrial dysfunction and apoptosis in IL-1β-stimulated chondrocytes. Mechanically, SNORC simultaneously activated the phosphatidylinositol-3-kinase/serine threonine kinase (PI3K/AKT) and c-Jun N-terminal kinase (JNK)/c-Jun signaling pathway in the IL-1β-induced chondrocyte, while re-activating the PI3K and JNK signals abolished the suppressive effect of down-regulating SNORC on IL-1β-induced chondrocyte damage. In a word, SNORC knockdown alleviates inflammation, matrix degradation, autophagy defect and excessive apoptosis of chondrocytes during OA development via suppressing the PI3K and JNK signaling pathway.

Psoralen Alleviates Renal Fibrosis by Attenuating Inflammasome-Dependent NLRP3 Activation and Epithelial-Mesenchymal Transition in a Mouse Unilateral Ureteral Obstruction Model

The role of psoralen (PS), a major active component extracted from Psoralea corylifolia L. seed, in renal fibrosis is still unclear. Thus, the objective of this study was to evaluate the effects of PS on the development and progression of renal fibrosis induced by unilateral ureteral obstruction (UUO) in a mouse model. Mice were divided into four groups: PS (20 mg/kg, i.g., n = 5), PS + sham (n = 5), UUO (n = 10), and PS + UUO (n = 10). PS was intragastrically administered 24 h before UUO and continued afterwards for 7 days. All mice were killed 7 days post UUO. Severe tubular atrophy, tubular injury, and tubulointerstitial fibrosis (TIF) were significantly developed in UUO mice. A higher expression of transforming growth factor-β1 (TGF-β1) was accompanied by elevated levels of α-smooth muscle actin (α-SMA) and phosphorylated Smad2/3 (pSmad2/3) at 7 days post UUO. However, PS treatment reduced tubular injury, interstitial fibrosis, and the expression levels of TGF-β1, α-SMA, and pSmad2/3. Furthermore, the levels of macrophages (represented by F4/80 positive cells) and the inflammasome, reflected by inflammasome markers such as nucleotide-binding and oligomerization domain-like receptors protein 3 (NLRP3) and cleaved caspase1 (cCASP-1), were significantly decreased by PS treatment. These results suggest that PS merits further exploration as a therapeutic agent in the management of chronic kidney disease (CKD).

Antioxidant and Anti-Inflammatory Properties of Phytochemicals Found in the Yucca Genus

The Yucca genus encompasses about 50 species native to North America. Species within the Yucca genus have been used in traditional medicine to treat pathologies related to inflammation. Despite its historical use and the popular notion of its antioxidant and anti-inflammatory properties, there is a limited amount of research on this genus. To better understand these properties, this work aimed to analyze phytochemical composition through documentary research. This will provide a better understanding of the molecules and the mechanisms of action that confer such antioxidant and anti-inflammatory properties. About 92 phytochemicals present within the genus have reported antioxidant or anti-inflammatory effects. It has been suggested that the antioxidant and anti-inflammatory properties are mainly generated through its free radical scavenging activity, the inhibition of arachidonic acid metabolism, the decrease in TNF-α (Tumor necrosis factor-α), IL-6 (Interleukin-6), iNOS (Inducible nitric oxide synthase), and IL-1β (Interleukin 1β) concentration, the increase of GPx (Glutathione peroxidase), CAT (Catalase), and SOD (Superoxide dismutase) concentration, and the inhibition of the MAPK (Mitogen-Activated Protein Kinase), and NF-κB (Nuclear factor kappa B), and the activation of the Nrf2 (Nuclear factor erythroid 2–related factor) signaling pathway. These studies provide evidence of its use in traditional medicine against pathologies related to inflammation. However, more models and studies are needed to properly understand the activity of most plants within the genus, its potency, and the feasibility of its use to help manage or treat chronic inflammation.

Psoralen downregulates osteoarthritis chondrocyte inflammation via an estrogen-like effect and attenuates osteoarthritis

Estrogen and its receptor play a positive role in the development of osteoarthritis (OA). Psoralen is a plant-derived estrogen analog. This study aimed to verify whether psoralen inhibits OA through an estrogen-like effect. First, human primary chondrocytes in the late stage of OA were extracted to complete collagen type II immunofluorescence staining and cell proliferation experiments. Subsequently, estrogen, psoralen and estrogen receptor antagonists were co-cultured with OA chondrocytes, and RT-PCR was performed to detect the gene expression. A rabbit OA model was subsequently made by anterior cruciate ligament transection (ACLT). They were set as Sham group, OA group and Psoralen group, respectively. The articular cartilage samples were taken after 5 weeks of treatment, and the effect was observed by gross observation, histological staining, micro-CT scanning of subchondral bone. The results of cellular experiments displayed that the cultured cells were positive for collagen II fluorescence staining and 12 μg/mL psoralen was selected as the optimal concentration. In addition, psoralen had effects similar to estrogen, promoting the expression of estrogen tar-get genes CTSD, PGR and TFF1 and decreasing the expression of the inflammation-related gene TNF- α, IL-1β and IL-6. The effect of psoralen was blocked after the use of an estrogen receptor antagonist. Further animal experiments indicated that the psoralen group showed less destruction of cartilage tissue and decreased OASRI scores compared with the OA group. A subchondral bone CT scan demonstrated that psoralen significantly increased subchondral bone mineral density (BMD), trabecular thickness and trabecular number and decreased trabecular separation. In summary, psoralen inhibits the inflammatory production of chondrocytes, which is related to estrogen-like effect, and can be used to attenuate the progression of OA.

Methodology improvement for network pharmacology to correct the deviation of deduced medicinal constituents and mechanism: Xian-Ling-Gu-Bao as an example

ETHNOPHARMACOLOGICAL RELEVANCE

Network pharmacology is extremely adaptive for investigating traditional ethnic drugs, especially the herbal medicines. However, challenges still hang over many related studies due to the limitations in the methodology of conventional network pharmacology.

AIM OF THE STUDY

Our work was aimed to investigate the methodology limitations of conventional network pharmacology with Xian-Ling-Gu-Bao (XLGB) as a representative, meanwhile, propose the strategies for coping with these issues.

MATERIALS AND METHODS

Predicted phytochemical constituents formed virtual XLGB. The constituents in realistic XLGB samples was detected by liquid chromatography-mass spectrometry (LC-MS) to correct the constituent deviation resulted from virtual prediction. Multivariate statistical analysis of quantitative target data were used to reveal the relation of target profile between drug and disease. The key constituents and targets were screened and compared between virtual and realistic XLGB through network analysis. After enrichment analysis, reversing network pharmacology was performed to exclude weak targets and re-construct the interaction from key pathways to key targets. Finally, the core constituents and action mechanism of XLGB were deduced.

RESULTS

Significant deviation of phytochemical constituents was found between virtual and realistic XLGB. As expected, this deviation led to a cascade of deviation ranging from deduced key constituents to key targets and key pathways. Moreover, many key KEGG pathways were enriched and screened out, however, they were almost irrelevant to the studied disease. These results systemically illustrated the limitations in the methodology of conventional network pharmacology. Importantly, the strategies for coping with these limitations were proposed, such as high-throughput detection of the realistic samples, multivariate analysis of target profile and combined enrichment analysis. Finally, based on the improved network pharmacology, the medicinal constituents and mechanism of XLGB against osteoarthritis were effectively deduced.

CONCLUSIONS

Our work highlighted the necessity and proposed the strategies for improving the methodology of conventional network pharmacology. The corrected results from improved network pharmacology provided promising directions for future research on XLGB.

Psoralen Promotes Proliferation, Migration, and Invasion of Human Extravillous Trophoblast Derived HTR-8/Svneo Cells in vitro by NF-κB Pathway

Recurrent spontaneous abortion (RSA) is a kind of pathological pregnancy, and abnormal function of trophoblast cells may be related to a variety of pregnancy complications including RSA. Psoralen is an effective ingredient extracted from Cullen corylifolium (L.) Medik. with multiple bioactivities mainly including anti-osteoporotic, anti-tumor, anti-inflammatory, and estrogen-like effects. However, the exact role of psoralen on trophoblast invasiveness has not been investigated thus far. In the present study, the effects of psoralen on the proliferation, migration, and invasion abilities of HTR-8/SVneo cells were evaluated by the CCK-8 and Transwell assays. The expression patterns of nuclear factor κB (NF-κB)/p65 and metalloproteinases (MMP)-2 and MMP-9 were characterized by further experiments including real-time quantitative polymerase chain reaction and Western blot. Indirect immunofluorescence was applied to track the NF-κB p65 translocation. Herein, we found that cell viability and invasive ability were promoted by psoralen in a concentration-dependent manner. Psoralen concentration-dependently enhanced both MMP-2 and MMP-9 expression and their activity of HTR-8/SVneo cells. Additionally, we observed accelerated nuclear accumulation and enhanced nuclear translocation of p65 in the presence of psoralen. Furthermore, invasiveness enhancement of psoralen on HTR-8/SVneo cells was partly eliminated by a NF-κB pathway inhibitor. Thus, our findings suggest that psoralen may serve as a potential repurpose drug candidate that can be used to induce migration and invasion of trophoblast cells through strengthening the NF-κB pathway.

Duality of Interactions Between TGF-β and TNF-α During Tumor Formation

The tumor microenvironment is essential for the formation and development of tumors. Cytokines in the microenvironment may affect the growth, metastasis and prognosis of tumors, and play different roles in different stages of tumors, of which transforming growth factor β (TGF-β) and tumor necrosis factor α (TNF-α) are critical. The two have synergistic and antagonistic effect on tumor regulation. The inhibition of TGF-β can promote the formation rate of tumor, while TGF-β can promote the malignancy of tumor. TNF-α was initially determined to be a natural immune serum mediator that can induce tumor hemorrhagic necrosis, it has a wide range of biological activities and can be used clinically as a target to immune diseases as well as tumors. However, there are few reports on the interaction between the two in the tumor microenvironment. This paper combs the biological effect of the two in different aspects of different tumors. We summarized the changes and clinical medication rules of the two in different tissue cells, hoping to provide a new idea for the clinical application of the two cytokines.

Identification of exosomal mRNA, lncRNA and circRNA signatures in an osteoarthritis synovial fluid-exosomal study

AIMS

Osteoarthritis (OA) is a common degenerative disease that is pathologically characterized by destruction of the joint matrix and reduction of articular chondrocytes, resulting in joint deformity and motor dysfunction. However, the molecular mechanisms governing this pathology have not been elucidated to date.

METHODS

In this study, we determined the expression levels of lncRNAs, circRNAs, and mRNAs extracted from synovial exosomes of OA and control patients. A network of circRNA/lncRNA-miRNA-mRNA interactions was established using MiRanda and TargetScan software to explore OA pathogenesis. The exosomal lncRNA, circRNA and mRNA expression profiles of the OA and control groups were analysed using LC human competing endogenous RNA (ceRNA) microarrays. The differentially expressed genes were analysed to determine their potential roles in the pathogenesis of OA by bioinformatic analysis.

RESULTS

There were 52 mRNAs, 196 lncRNAs and 98 circRNAs differentially expressed in synovial exosomes between osteoarthritis synovial and the control group. The final ceRNA network of lncRNAs and circRNAs exhibited a complex interaction between ncRNA and mRNA related to OA pathological mechanisms. An intersection analysis of the ceRNA network showed that 22 miRNAs, 45 lncRNAs, and 34 circRNAs enriched in the PI3K/Akt and autophagy pathways correlated with 7 mRNAs and may play important roles in OA pathological mechanisms.

CONCLUSION

Our work analysed mRNA/lncRNA/circRNA expression and displayed the ceRNA network of lncRNAs and circRNAs to profile the pathogenesis of OA in synovial exosomes. The results of this study may help to elucidate the pathogenesis of OA and may provide important references for further research attempting to identify more effective targets for the diagnosis and therapy of OA.

Research Progress on the Antiosteoarthritic Mechanism of Action of Natural Products

Background

Osteoarthritis (OA) is a clinical joint degenerative disease, the pathogenic factors of which include age, obesity, and mechanical injury. Its main pathological features include cartilage loss, narrowing of joint space, and osteophyte formation. At present, there are a variety of treatment methods for OA. Natural products, which are gradually being applied in the treatment of OA, are advantageous as they present with low toxicity and low costs and act on multiple targets.

Methods

The terms “natural products,” “osteoarthritis,” and “chondrocytes” were searched in PubMed to screen the related literature in the recent 10 years.

Results

We comprehensively introduced 62 published papers on 48 natural products involving 6, 3, 5, 12, 4, and 5 kinds of terpenoids, polysaccharides, polyphenols, flavonoids, alkaloids, and saponins, respectively (and others).

Conclusion

The mechanisms of their anti-OA action mainly involve reducing the production of inflammatory factors, reducing oxidative stress, regulating the metabolism of chondrocytes, promoting the proliferation of chondrocytes, or inhibiting chondrocyte apoptosis. This article summarizes the anti-OA activity of natural products in the last 10 years and provides candidate monomers for further study for use in OA treatment.

Hesperetin Exhibits Anti-Inflammatory Effects on Chondrocytes via the AMPK Pathway to Attenuate Anterior Cruciate Ligament Transection-Induced Osteoarthritis

This study aimed to determine whether hesperetin (HPT) has chondroprotective effects against the TNF-α-induced inflammatory response of chondrocytes and related mechanisms and clarify the impact of HPT on osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT). Under tumor necrosis factor-α (TNF-α) stimulation, rat chondrocytes were treated with or without HPT. The CCK-8 assay was used to detect viability and cytotoxicity. RT-qPCR and Western blot were used to examine the expression of aggrecan, collagen type II, and inflammatory and proliferative genes/proteins in chondrocytes. Flow cytometry was used to check the cell cycle to determine whether HPT protects chondrocytes against the inhibitory effect of TNF-α on chondrocyte proliferation. In addition, RNA sequencing was used to discover possible molecular targets and pathways and then validate these pathways with specific protein phosphorylation levels. Finally, immunofluorescence staining was used to examine the phosphorylation of the AMP-activated protein kinase (AMPK) pathway. The results showed that HPT restored the upregulation of interleukin 1β (IL-1β), PTGS2, and MMP-13 induced by TNF-α. In addition, HPT reversed the degradation of the extracellular matrix of chondrocytes induced by TNF-α. HPT also reversed the inhibitory effect of TNF-α on chondrocyte proliferation. RNA sequencing revealed 549 differentially expressed genes (DEGs), of which 105 were upregulated and 444 were downregulated, suggesting the potential importance of the AMPK pathway. Progressive analysis showed that HPT mediated the repair of TNF-α-induced chondrocyte damage through the AMPK signaling pathway. Thus, local treatment of HPT can improve OA induced by ACLT. These findings indicated that HPT has significant protective and anti-inflammatory effects on chondrocytes through the AMPK signaling pathway, effectively preventing cartilage degradation. Given the various beneficial effects of HPT, it can be used as a potential natural drug to treat OA.

Tenascin-C regulates migration of SOX10 tendon stem cells via integrin-α9 for promoting patellar tendon remodeling

Insufficient attention has been focused on the directional migration of SOX10+ tendon stem cells (STSCs) during tendon remodeling. Here, we investigate whether tenascin-C (TNC) promotes STSC motility and migration. Based on the hypothesis that TNCs induce STSC migration, RNA-sequencing (RNA-seq) was conducted, identifying 2107 differentially expressed genes (DEGs), of which 1272 were up-regulated and 835 down-regulated following treatment with TNC versus the control. The DEGs were principally involved in cell adhesion and cell membrane signal transduction. Highly enriched-related signaling included the PI3K-Akt, focal adhesion, and ECM-receptor interaction pathways. Protein interaction analysis established that TNC was positively correlated with ITGA9 (integrin-α9). Furthermore, TNC activated the phosphorylation levels of FAK and Akt, and knockdown of ITGA9 with siRNA revealed that TNC contributes to STSC migration via the targeting of ITGA9. In addition, in vivo administration of TNC promoted tissue regeneration of injured tendons. In conclusion, TNC regulated the migration of STSCs via ITGA9, thereby promoting the regeneration of tendon injuries.

Psoralen inhibits the inflammatory response and mucus production in allergic rhinitis by inhibiting the activator protein 1 pathway and the downstream expression of cystatin‑SN

Psoralen (PSO) exerts anti-inflammatory pharmacological effects and plays an important role in a variety of inflammatory diseases. However, the effects of PSO with allergic rhinitis (AR) are yet to be reported. In the present study, an in vitro AR model was generated by inducing JME/CF15 human nasal epithelial cells with IL-13, after which MTT was used to assess the cytotoxicity of PSO. The expression levels of inflammatory cytokines (granulocyte-macrophage colony-stimulating factor and Eotaxin) were determined by ELISA. Furthermore, the expression of inflammatory IL-6 and −8, as well as mucin 5AC, was assessed by reverse transcription-quantitative PCR and western blotting, and cellular reactive oxygen species were detected using a 2′,7′-dichlorodihydrofluorescein diacetate fluorescent probe. Western blotting was also used to detect the expression and phosphorylation of c-Fos and c-Jun in the activator protein 1 (AP-1) pathway, as well as the expression of cystatin-SN (CST1). PSO inhibited the inflammatory response and mucus production in IL-13-induced JME/CF15 cells. Furthermore, the levels of c-Fos and c-Jun phosphorylation in the AP-1 pathway were decreased in IL-13-induced JME/CF15 cells following PSO treatment. The expression of pathway proteins was activated by the addition of PMA, an AP-1 pathway activator, which concurrently reversed the inhibitory effects of PSO on the inflammatory response and mucus formation. The addition of an AP-1 inhibitor (SP600125) further inhibited pathway activity, and IL-13-induced inflammation and mucus formation was restored. In conclusion, PSO regulates the expression of CST1 by inhibiting the AP-1 pathway, thus suppressing the IL-13-induced inflammatory response and mucus production in nasal mucosal epithelial cells.

Alpinetin Protects Chondrocytes and Exhibits Anti-Inflammatory Effects via the NF-κB/ERK Pathway for Alleviating Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease which is greatly affected by the inflammatory response triggered by the NF-κB signaling pathway. Alpinetin (APT) is a natural flavonoid compound, which has been reported to have many important biological activities such as antibacterial, antitumor, and anti-inflammatory. However, the action of its effect on chondrocytes in OA has yet to be elucidated. In this study, we investigated APT's anti-inflammatory action. The effects of APT on cell viability and cytotoxicity of rat chondrocytes was investigated by CCK8. Western blotting, qRT-PCR, and immunofluorescent staining were used to elucidate the molecular mechanisms and signaling pathways of APT mediating anti-inflammatory effects on chondrocytes. An OA model was induced by destabilization of the medial meniscus (DMM) in rats, then APT was injected into the knee articular cavity to examine its anti-inflammatory effects in vivo. These results showed that APT could reduce the TNF-α-induced increase of MMP-13 and ADAMTS-5 and decrease of COL2A1 levels. APT antagonized TNF-α-induced down-regulation of BCL-2 and CDK1. Further studies have shown that APT simultaneously repressed cell nucleus translocation of p65 and the phosphorylation of IκB and activated the phosphorylation of ERK. In vivo, APT suppressed cartilage matrix degradation. In conclusion, APT appears to favorably modulate anti-inflammatory effects in chondrocytes making it a promising compound for OA treatment. Graphical Abstract Inhibitory effects of Alpinetin on TNF-α-induced NF-κB activation resulted in destruction of cartilage in rat OA chondrocytes in vitro. The TNF-α receptor were stimulated by TNF-α, activating the cytoplasmic IκBα kinases(IKKS), then IKKs will be phosphorylated, and subsequently degraded by the ubiquitin-proteasome system. NF-κB transfer to the nucleus and bind various NF-κB regulates the NF-κB recognition site in the promoter region. Which triggers the gene expression of pro-inflammatory and pro-apoptotic. However, Alpinetin could inhibits the NF-κB signaling pathway in different ways: APT inhibits IκBα phosphorylation, preventing phosphorylated ubiquitination of IκBα further. Moreover, APT blocks translocation of the activated NF-κB to the nucleus, to protect the cartilage tissue from damage.

Magnolin exhibits anti-inflammatory effects on chondrocytes via the NF-κB pathway for attenuating anterior cruciate ligament transection-induced osteoarthritis

Purpose: This study aimed to investigate whether magnolin (MGL) possesses the capability of suppressing inflammatory responses that can in turn alleviate osteoarthritis (OA).Methods: We investigated the effects of MGL on the viability of rat chondrocytes at concentrations of 5 to 100 µM, and selected 10 µM for further study. We elucidated the molecular mechanisms and signaling pathways mediating these effects via RNA sequencing, qRT-PCR, immunofluorescent staining, and Western blotting techniques. Following this, we established an anterior cruciate ligament (ACL) transection-induced OA rat model, and injected MGL into the knee articular cavities to verify the in vivo anti-inflammatory effects of MGL.Results: We found that MGL could recover the TNF-α-induced upregulation of IL-1β, COX2, ADAMTS-5, and MMP-1/3/13 at the gene/protein level, as well as the downregulation of cartilaginous ECM synthesis. Gene expression profiles of different groups identified 49 common differentially expressed genes (DEGs), which were mainly enriched in the structural constituents of the ribosome, the extracellular space, and inflammatory response. The NF-κB pathway was highly enriched, and the expression levels of DEGs associated with it (Nfkbia, Ptgs2, Rela, Tnfrsf1a, Tradd, Traf2) under TNF-α stimulation were reversed by MGL. Further studies proved that MGL simultaneously suppressed the cell nucleus translocation of p65 and the phosphorylation of IκBα. Moreover, in vivo, MGL suppressed cartilage matrix degradation, inhibited MMP-13 expression, and promoted cartilage matrix construction by upregulating SOX9 synthesis.Conclusion: MGL demonstrated significant anti-inflammatory bioactivity on chondrocytes by suppressing the activation of NF-κB pathway, which in turn exhibited a significant alleviation of OA.

Pretreatment with mechano growth factor E peptide attenuates osteoarthritis through improving cell proliferation and extracellular matrix synthesis in chondrocytes under severe hypoxia

Osteoarthritis (OA) is characterized by pain and declining gait function associated with degeneration of cartilage. A severe hypoxic environment occurs due to tissue injury in the joint cavity and may aggravate the development of OA. In this study, the effects of severe hypoxia and treatment with mechano growth factor (MGF) E peptide on metabolism of the extracellular matrix (ECM) during the progression of OA were determined. The results showed that cell viability, cell proliferation, and type II collagen expression in chondrocytes were significantly inhibited by cobalt chloride (CoCl₂)-simulated severe hypoxia, whereas cell apoptosis and expression levels of hypoxia inducible factor 1 alpha, type I collagen, and matrix metalloproteinases 1/13 were clearly induced. Pretreatment with MGF E peptide reduced the abovementioned adverse effects induced by CoCl₂-simulated severe hypoxia in chondrocytes. Pretreatment also upregulated the proliferation of chondrocytes under severe hypoxia through the PI3K-Akt and MEK-ERK1/2 signaling pathways. In a rat model of monosodium iodoacetate (MIA)-induced OA. MIA treatment induced tissue necrosis and cartilage degeneration, and histological score was significantly decreased. The levels of type II collagen and aggrecan were reduced after MIA treatment for 4 or 6 weeks, and abnormal distribution of ECM occurred in the inner epicondyle after 6 weeks. MGF E peptide also reduced the progression of MIA-induced OA by retarding cartilage degeneration, upregulating type II collagen synthesis, and improving ECM distribution after 4 or 6 weeks. Our findings suggest that MGF attenuates the progression of OA, and thus may be applied for the treatment of OA in the clinic.

Anti-inflammatory activity of psoralen in human periodontal ligament cells via estrogen receptor signaling pathway

Psoralen is one of the most effective ingredients extracted from the Chinese herb, Psoralea corylifolia L. Studies have found that psoralen has anti-inflammatory and estrogen-like effects; however, little research has been conducted to elucidate the mechanisms underlying these effects. Through the molecule docking assay, psoralen was found to have a better combination with ERα than ERβ. In human periodontal ligament cells, psoralen was found to upregulate the estrogen target genes (e.g., CTSD, PGR, TFF1) and down-regulate the expression of inflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-8) stimulated by P. gingivalis LPS, as well as TLR4-IRAK4-NF-κb signaling pathway proteins. These effects were reversed by the ER antagonist ICI 182780. These results indicated that psoralen may exert anti-inflammatory effects as an agonist to ER, which could provide a theoretical basis for the use of psoralen for adjuvant therapy and prevention of periodontitis.

Molecular mechanisms of mechanical load-induced osteoarthritis

INTRODUCTION

Mechanical loading enhances the progression of osteoarthritis. However, its molecular mechanisms have not been established.

OBJECTIVE

The aim of this review was to summarize the probable mechanisms of mechanical load-induced osteoarthritis.

METHODS

A comprehensive search strategy was used to search PubMed and EMBASE databases (from the 15th of January 2015 to the 20th of October 2020). Search terms included "osteoarthritis", "mechanical load", and "mechanism".

RESULTS

Abnormal mechanical loading activates the interleukin-1β, tumour necrosis factor-α, nuclear factor kappa-B, Wnt, transforming growth factor-β, microRNAs pathways, and the oxidative stress pathway. These pathways induce the pathological progression of osteoarthritis. Mechanical stress signal receptors such as integrin, ion channel receptors, hydrogen peroxide-inducible clone-5, Gremlin-1, and transient receptor potential channel 4 are present in the articular cartilages.

CONCLUSION

This review highlights the molecular mechanisms of mechanical loading in inducing chondrocyte apoptosis and extracellular matrix degradation. These mechanisms provide potential targets for osteoarthritis prevention and treatment.

Current Nanoparticle-Based Technologies for Osteoarthritis Therapy

Osteoarthritis (OA) is a common chronic joint disease that is characterized by joint pain and stiffness, and limitation of motion and the major cause of disability, which reduces life quality of patients and brings a large economic burden to the family and society. Current clinical treatment is mostly limited to symptomatic treatment aimed at pain alleviation and functional improvement, rather than suppressing the progression of OA. Nanotechnology is a promising strategy for the treatment of OA. In this review, we summarize the current experimental progress that focuses on technologies such as liposomes, micelles, dendrimers, polymeric nanoparticles (PNPs), exosomes, and inorganic nanoparticles (NPs) for their potential treatment of OA.

Safflower yellow alleviates osteoarthritis and prevents inflammation by inhibiting PGE2 release and regulating NF-κB/SIRT1/AMPK signaling pathways

BACKGROUND

Safflower yellow (SY) is the main active ingredient of safflower, with various pharmacological effects such as anticoagulating, antioxidant, and anti-arthritis effects.

PURPOSE

To investigate the anti-inflammatory and chondrocyte protecting role of SY, which subsequently leads to the inhibition of cartilage degradation.

METHODS

Rat chondrocytes were stimulated with tumor necrosis factor α (TNF-α) with or without SY treatment. Following this, CCK-8 assay was performed to detect cytotoxicity. RT-qPCR, Western blotting, and immunofluorescence staining were used to detect the gene/protein expression of typical cartilage matrix genes and related inflammatory markers. Subsequently, EdU assay was used to evaluate cell proliferation. RNA sequencing, online target prediction, and molecular docking were performed to determine the possible molecular targets and pathways.

RESULTS

The results showed that SY restored the TNF-α-induced up-regulation of IL-1β, PTGS2, and MMP-13 and down-regulation of COL2A1 and ACAN. Furthermore, it recovered cell proliferation by suppressing TNF-α. Gene expression profiles identified 717 differentially expressed genes (DEGs) in the cells cultured with or without SY under TNF-α stimulation. After pathway enrichment, PI3K-Akt, TNF, Cytokine-cytokine receptor interaction, NF-κB, NOD-like receptor, and Chemokine signaling pathways were notably selected to highlight NFKBIA, CCL5, CCL2, IL6, and TNF as potential targets in osteoarthritis (OA). SY inhibited TNF-α-induced activation of NF-κB and endoplasmic reticulum (ER) stress by promoting AMPK phosphorylation along with SIRT1 expression. Further, SY reduced MMP-13 expression and targeted COX-2 for decreasing PGE2 release. In addition, anterior cruciate ligament transection-induced OA was ameliorated by local administration of SY.

CONCLUSION

These results demonstrate that SY protects chondrocytes and inhibits inflammation by regulating the NF-κB/SIRT1/AMPK pathways and ER stress, thus preventing cartilage degeneration in OA.

Ursolic acid protects chondrocytes, exhibits anti-inflammatory properties via regulation of the NF-κB/NLRP3 inflammasome pathway and ameliorates osteoarthritis

Inflammation and poor viability of chondrocytes result in the degradation of cartilage as osteoarthritis (OA) progresses. The purpose of the present study was to investigate whether ursolic acid (UA) can protect chondrocytes and alleviate OA. Following stimulation with tumor necrosis factor-α (TNF-α), 5 μM UA displayed no cytotoxicity and reversed the up-regulation of the inflammatory factors MMP13, IL-1β, IL-6 and PTGS2, and down-regulation of the cartilaginous genes/proteins type II collagen and Aggrecan. RNA sequencing identified 533 common deferentially expressed genes (DEGs) of which TNF, PI3K-AKT, NOD-like receptor, cytokine receptor interaction and NF-κB pathways were of potential importance. Further notable DEGs in the most-highly expressed 10 pathways contributed to maintenance of cartilaginous ECM homeostasis and were involved in an inflammatory response. The expression of these most-enriched DEGs was reversed by UA following stimulation with TNF-α. Additional investigation demonstrated that treatment with UA inhibited TNF-α-induced nuclear translocation of p65 and phosphorylation of IκBα and AKT, and reversed TNF-α-induced up-regulation of P20, ACS and NLRP3. Furthermore, rat anterior cruciate ligament transection (ACLT) induced-OA was ameliorated by treatment with UA. In conclusion, these results suggest that UA activates chondrocytes through the NF-κB/NLRP3 inflammasome pathway, thus preventing cartilage degeneration in osteoarthritis.

A Review of the Pharmacological Properties of Psoralen

Psoralen is the principal bioactive component in the dried fruits of Cullen corylifolium (L.) Medik (syn. Psoralea corylifolia L), termed "Buguzhi" in traditional Chinese medicine (TCM). Recent studies have demonstrated that psoralen displays multiple bioactive properties, beneficial for the treatment of osteoporosis, tumors, viruses, bacteria, and inflammation. The present review focuses on the research evidence relating to the properties of psoralen gathered over recent years. Firstly, multiple studies have demonstrated that psoralen exerts strong anti-osteoporotic effects via regulation of osteoblast/osteoclast/chondrocyte differentiation or activation due to the participation in multiple molecular mechanisms of the wnt/β-catenin, bone morphogenetic protein (BMP), inositol-requiring enzyme 1 (IRE1)/apoptosis signaling kinase 1 (ASK1)/c-jun N-terminal kinase (JNK) and the Protein Kinase B(AKT)/activator protein-1 (AP-1) axis, and the expression of miR-488, peroxisome proliferators-activated receptor-gamma (PPARγ), and matrix metalloproteinases (MMPs). In addition, the antitumor properties of psoralen are associated with the induction of ER stress-related cell death via enhancement of PERK: Pancreatic Endoplasmic Reticulum Kinase (PERK)/activating transcription factor (ATF), 78kD glucose-regulated protein (GRP78)/C/EBP homologous protein (CHOP), and 94kD glucose-regulated protein (GRP94)/CHOP signaling, and inhibition of P-glycoprotein (P-gp) or ATPase that overcomes multidrug resistance. Furthermore, multiple articles have shown that the antibacterial, anti-inflammatory and neuroprotective effects of psoralen are a result of its interaction with viral polymerase (Pol), destroying the formation of biofilm, and regulating the activation of tumor necrosis factor alpha (TNF-α), transforming growth factor beta (TGF-β), interleukin 4/5/6/8/12/13 (IL-4/5/6/8/12/13), GATA-3, acetylcholinesterase (AChE), and the hypothalamic-pituitary-adrenal (HPA) axis. Finally, the toxic effects and mechanisms of action of psoralen have also been reviewed.

Small Molecule Regulation of Stem Cells that Generate Bone, Chondrocyte, and Cardiac Cells

Embryonic stem cells (ESCs) are stem cells (SCs) that can self-renew and differentiate into a myriad of cell types. The process of developing stemness is determined by signaling molecules that drive stem cells to a specific lineage. For example, ESCs can differentiate into mature cells (e.g., cardiomyocytes) and mature cardiomyocytes can be characterized for cell beating, action potential, and ion channel function. A goal of this Perspective is to show how small molecules can be used to differentiate ESCs into cardiomyocytes and how this can reveal novel aspects of SC biology. This approach can also lead to the discovery of new molecules of use in cardiovascular disease. Human induced pluripotent stem cells (hiPSCs) afford the ability to produce unlimited numbers of normal human cells. The creation of patient-specific hiPSCs provides an opportunity to study cell models of human disease. The second goal is to show that small molecules can stimulate hiPSC commitment to cardiomyocytes. How iPSCs can be used in an approach to discover new molecules of use in cardiovascular disease will also be shown in this study. Adult SCs, including mesenchymal stem cells (MSCs), can likewise participate in self-renewal and multilineage differentiation. MSCs are capable of differentiating into osteoblasts, adipocytes or chondrocytes. A third goal of this Perspective is to describe differentiation of MSCs into chondrogenic and osteogenic lineages. Small molecules can stimulate MSCs to specific cell fate both in vitro and in vivo. In this Perspective, some recent examples of applying small molecules for osteogenic and chondrogenic cell fate determination are summarized. Underlying molecular mechanisms and signaling pathways involved are described. Small molecule-based modulation of stem cells shows insight into cell regulation and potential approaches to therapeutic strategies for MSC-related diseases.

Recent advance in treatment of osteoarthritis by bioactive components from herbal medicine

Osteoarthritis (OA) is a common chronic articular degenerative disease, and characterized by articular cartilage degradation, synovial inflammation/immunity, and subchondral bone lesion, etc. The disease affects 2-6% of the population around the world, and its prevalence rises with age and exceeds 40% in people over 70. Recently, increasing interest has been devoted to the treatment or prevention of OA by herbal medicines. In this paper, the herbal compounds with anti-OA activities were reviewed, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 43 herbal compounds were analyzed, which mainly target the damaged joints (e.g. cartilage, subchondral bone, and synovium, etc.) and circulatory system to improve the pathogenesis of OA. Through cheminformatics analysis, over half of these compounds have good drug-likeness properties, and the pharmacokinetic behavior of these components still needs to be further optimized, which is conducive to the enhancement in their drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-OA drug discovery, which may be worthy of further investigation and development.

Psoralen alleviates high glucose-induced HK-2 cell injury by inhibition of Smad 2 signaling via upregulation of microRNA 874

Background

Diabetic nephropathy (DN) causes the vast proportion of excess mortality for patients with diabetes. Novel therapeutic approaches slowing down its incidence is still lacking. Psoralen is the major active ingredient of Psoralea corylifolia Linn. (PCL), which was used to treat a number of diseases. In this study, we aimed to investigate whether psoralen could alleviate DN using in vitro model.

Methods

Cell viability assay and immunofluorescence were used to evaluate the effect of psoralen on high glucose (HG)-stimulated human kidney HK-2 cells (48 h). RT-qPCR was used to detect the expressions of miRNA in cells. Cell transfection, apoptosis assay, inflammatory cytokines detection and Western blot were further performed to explore the underlying molecular mechanisms.

Results

HG-induced toxicity of HK-2 cells was alleviated by psoralen. Meanwhile, the secretion of inflammatory cytokines and extracellular matrix (ECM) accumulation induced by HG in HK-2 cells were also decreased by psoralen. In addition, the expression of miR-874 in HK-2 cells was significantly upregulated by psoralen. Western blot assays indicated that psoralen could reverse HG-induced increase of TLR-4/NF-κB and Smad2 via upregulation of miR-874.

Conclusion

This study demonstrated that psoralen could significantly alleviate HG-induced HK-2 cell injury via upregulation of miR-874. In addition, HG-induced increase of TLR-4/NF-κB and Smad2 was revered by psoralen. Therefore, psoralen might serve as an agent for the treatment of DN.

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

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

Topical application of Chinese herbal medicine DAEP relieves the osteoarthritic knee pain in rats

Background

The potential adverse effects of conventional oral pharmacotherapy of osteoarthritis (OA) restrict their long-term use. Topical application of a Chinese herbal paste for relieving OA knee pain can be effective and safe. However, evidence-based scientific research is insufficient to support its application worldwide. The aim of this study was to investigate the in vivo efficacy of a topical Chinese herbal paste on relieving OA knee pain and its underlying mechanism.

Methods

An OA rat model was developed by anterior cruciate ligament transection (ACLT) followed by treadmill running. A herbal paste including Dipsaci Radix, Achyranthis Bidentatae Radix, Eucommiae Cortex and Psoraleae Fructus, named as DAEP, was applied topically on the knee joint of the rats (DAEP). The rats without DAEP treatment served as Control. Rats with surgery but without ACLT, treadmill running and DAEP treatment acted as Sham. The morphologic change of the knee joint was observed radiographically. Nociception from the knee of the rats was assessed using Incapacitent test and CatWalk gait system. The therapeutic mechanism was investigated by analyzing the gene and protein expression of inflammatory markers via qPCR and Western blot, respectively.

Results

Radiographic images showed less destruction at the posterior tibial plateau of the DAEP group compared with the Control after 2 weeks of treatment. The static weight ratio and the gait parameters of the Control were reduced significantly via Incapacitance test and CatWalk gait analysis, respectively. DAEP treatment increased the Print Area and Maximum Intensity significantly compared with the Control. DAEP significantly suppressed the upregulation of gene expression of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS).

Conclusions

DAEP exhibited its effect via the nuclear factor (NF)-κB pathway by suppressing the phosphorylation of IκB kinase αβ (p-IKKαβ) and cyclooxygenase-2 (COX-2) protein expression. This study provides scientific evidence to support the clinical application of the Chinese herbal paste on reliving OA pain.

Effects of Bakuchiol on chondrocyte proliferation via the PI3K-Akt and ERK1/2 pathways mediated by the estrogen receptor for promotion of the regeneration of knee articular cartilage defects

Objectives

Cartilaginous tissue degradation occurs because of the lack of survival of chondrocytes. Here, we ascertained whether bakuchiol (BAK) has the capability of activating chondrocyte proliferation.

Materials and methods

The effect of BAK on the proliferation of rat chondrocytes at a concentration of 10 and 20 µmol/L was investigated. The molecular mechanisms involving target binding and signalling pathways were elucidated by RNA‐sequencing, qPCR, molecular docking and Western blotting. Matrigel mixed with bakuchiol was implanted locally into rat knee articular cartilage defects to verify the activation of chondrocytes due to bakuchiol in vivo.

Results

Bakuchiol implantation resulted in the activation of rat chondrocyte proliferation in a dose‐dependent manner. RNA‐sequencing revealed 107 differentially expressed genes (DEGs) with 75 that were up‐regulated and 32 that were down‐regulated, indicating increased activation of the PI3K‐Akt and cell cycle pathways. Activation of the phosphorylation of Akt, ERK1/2 and their inhibitors blocked the proliferative effect of bakuchiol treatment, confirming its direct involvement in these signal transduction pathways. Molecular docking and siRNA silencing revealed that estrogen receptor‐α (ERα) was the target of bakuchiol in terms of its cell proliferative effect via PI3K activation. Two weeks after implantation of bakuchiol, the appearance and physiological structure of the articular cartilage was more integrated with abundant chondrocytes and cartilage matrix compared to that of the control.

Conclusions

Bakuchiol demonstrated significant bioactivity towards chondrocyte proliferation via the PI3K‐Akt and ERK1/2 pathways mediated by estrogen receptor activation and exhibited enhanced promotion of the remodelling of injured cartilage.