Hypertrophic differentiation of mesenchymal stem cells is suppressed by xanthotoxin via the p38‑MAPK/HDAC4 pathway

Xanthotoxin (8-methoxypsoralen): A review of its chemistry, pharmacology, pharmacokinetics, and toxicity

Xanthotoxin (XAT) is a natural furanocoumarins, a bioactive psoralen isolated from the fruit of the Rutaceae plant Pepper, which has received increasing attention in recent years due to its wide source and low cost. By collecting and compiling literature on XAT, the results show that XAT exhibits significant activity in the treatment of various diseases, including neuroprotection, skin repair, osteoprotection, organ protection, anticancer, antiinflammatory, antioxidative stress and antibacterial. In this paper, we review the pharmacological activity and potential molecular mechanisms of XAT for the treatment of related diseases. The data suggest that XAT can mechanistically induce ROS production and promote apoptosis through mitochondrial or endoplasmic reticulum pathways, regulate NF-κB, MAPK, JAK/STAT, Nrf2/HO-1, MAPK, AKT/mTOR, and ERK1/2 signaling pathways to exert pharmacological effects. In addition, the pharmacokinetics properties and toxicity of XAT are discussed in this paper, further elucidating the relationship between structure and efficacy. It is worth noting that data from clinical studies of XAT are still scarce, limiting the use of XAT in the clinic, and in the future, more in-depth studies are needed to determine the clinical efficacy of XAT.

Next-Generation Sequencing of Circular RNAs Reveals the Molecular Mechanisms of Chondrogenic Differentiation in Human Adipose-derived Stem Cells

Adipose-derived stem cells are one of the potential sources of cells for the treatment of cartilage defects. This study aimed to investigate the molecular mechanisms that account for the chondrogenic differentiation of human adipose-derived stem cells (hADSCs). We employed integrin β1 (ITGB1) overexpression to induce chondrogenic differentiation of hADSCs. Next-generation sequencing was used to determine the mRNAs and circular RNAs (circRNAs) expression profiles in ITGB1-overexpresing and negative control cells. The potential functions of differentially expressed mRNAs were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses. Moreover, differentially expressed circRNAs with the greatest fold change were validated by polymerase chain reaction (PCR), Sanger sequencing, and quantitative real-time PCR (qRT-PCR). These three circRNAs and their downstream microRNAs and mRNAs were used to construct a circRNA-microRNA-mRNA interaction network. The results showed that we identified 713 differentially expressed circRNAs (150 upregulated and 563 downregulated in ITGB1-overexpressing hADSCs versus negative control cells, respectively). Meanwhile, 2383 mRNAs were differentially expressed between two groups (1672 upregulated and 711 downregulated in ITGB1-overexpressing cells compared with the negative control cells). The GO and KEGG analysis results showed that the differentially expressed mRNAs were enriched in biological processes, cellular components, and molecular functions, especially in the phosphatidylinositol 3-kinase (PI3K)-AKT and mitogen-activated protein kinase signaling pathways. Three differentially expressed circRNAs, including hsa_circ_0071127, hsa_circ_0008637, and hsa_circ_0020028, were validated by qRT-PCR. Moreover, the circRNA-microRNA-mRNA network predicted that fibroblast growth factor 2 (FGF2) was a common node regulated by these three circRNAs through several microRNAs, including miR-195-3p, miR-205-3p, and miR-152-3p. We further found that the knockdown of hsa_circ_0020028, but not the two other circRNAs, significantly reduced FGF2 mRNA expression in hADSCs. Furthermore, the knockdown of hsa_circ_0020028 significantly inhibited the protein expression of FGF2, chondrogenic differentiation markers (COL II, aggrecan, and SOX9), and PI3K/AKT signaling in ITGB1-overexpressing hADSCs. This study uncovered the differentially expressed mRNA and circRNA profiles in the chondrogenic differentiation of hADSCs induced by ITGB1 overexpression. Our findings demonstrate that hsa_circ_0020028 regulates the ITGB1 overexpression-mediated chondrogenic differentiation of hADSCs through regulation of FGF2-related signaling pathways.

SPRY4 acts as an indicator of osteoarthritis severity and regulates chondrocyte hypertrophy and ECM protease expression

Osteoarthritis (OA) causes serious changes in the metabolic and signaling pathways of chondrocytes, including the mitogen-activated protein kinase (MAPK) pathway. However, the role of sprouty RTK signaling antagonist 4 (SPRY4), an inhibitor of MAPK, in the human cartilage tissues and chondrocytes remains to be understood. Here, using SPRY4 gene delivery into healthy and degenerated chondrocytes, we elucidated the role of SPRY4 in preventing chondrocyte hypertrophy. In addition to using the human cartilage tissues with the destabilization of the medial meniscus (DMM) model in Sprague-Dawley (SD) rats, the role of SPRY4 in cartilage tissues and chondrocytes was explored through their molecular and histological analyses. In order to determine the effects of SPRY4 on healthy human chondrocyte hypertrophy, small interfering RNA (siRNA) was used to knock down SPRY4. Lentiviral transduction of SPRY4 into degenerated human chondrocytes allowed us to investigate its ability to prevent hypertrophy. SPRY4 expression levels were higher in healthy human cartilage tissue and chondrocytes than in degenerated human cartilage tissues and hypertrophy-induced chondrocytes. The knockdown of SPRY4 in healthy chondrocytes caused an increase in hypertrophy, senescence, reactive oxygen species (ROS) production, and extracellular matrix (ECM) protease expression. However, all these factors decreased upon overexpression of SPRY4 in degenerated chondrocytes via regulation of the MAPK signaling pathway. We conclude that SPRY4 is a crucial indicator of osteoarthritis (OA) severity and could play an important role in preventing OA in the cartilage by inhibiting chondrocyte hypertrophy.

Alleviation of Synovial Inflammation of Juanbi-Tang on Collagen-Induced Arthritis and TNF-Tg Mice Model

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is primarily characterized by synovial inflammation. In this study, we found that a traditional Chinese decoction, Juanbi-Tang (JBT), JBT attenuated the symptoms of collagen-induced arthritis (CIA) mice and in tumor necrosis factor transgenic (TNF-Tg) mice by attenuating the arthritis index and hind paw thickness. According to histopathological staining of ankle sections, JBT significantly decreased the area of inflammation and reduced bone destruction of ankle joints in both these two types of mice. Moreover, decreased tartaric acid phosphatase-positive osteoclasts were observed in the JBT group compared with those found in the control group. We also revealed that JBT suppressed monocytes and T cells as well as the production of CCL2, CCR6, and CXCR3 ligands. We next used high-performance liquid chromatography to investigate the components and pharmacological properties of this classical herbal medicine in traditional Chinese medicine. Based on network pharmacology, we performed computational prediction simulation of the potential targets of JBT, which indicated the NF-kappa B pathway as its target, which was confirmed in vitro. JBT suppressed the production of pro-inflammatory cytokines including interleukin-6 (IL-6) and IL-8, and inhibited the expression of matrix metalloproteinase 1 in fibroblast-like synoviocytes derived from RA patients (MH7A cells). Furthermore, JBT also suppressed the phosphorylation of p38, JNK, and p65 in TNF-α-treated MH7A cells. In summary, this study proved that JBT could inhibit synovial inflammation and bone destruction, possibly by blocking the phosphorylation of NF-kappa B pathway-mediated production of proinflammatory effectors.

Enterococcus faecium L-15 Cell-Free Extract Improves the Chondrogenic Differentiation of Human Dental Pulp Stem Cells

Hyaline cartilage is a tissue of very low regenerative capacity because of its histology and limited nutrient supply. Cell-based therapies have been spotlighted in the regeneration of damaged cartilage. Dental pulp stem cells (DPSCs) are multipotent and are easily accessible for therapeutic purposes. In human gastrointestinal tracts, Enterococcus faecium is a naturally occurring commensal species of lactic acid bacteria. In this work, the human DPSCs were differentiated into chondrocytes using a chondrogenic differentiation medium with or without L-15 extract. We observed that chondrogenic differentiation improved in an E. faecium L-15 extract (L-15)-treated DPSC group via evaluation of chondrogenic-marker mRNA expression levels. In particular, we found that L-15 treatment promoted early-stage DPSC differentiation. Cells treated with L-15 were inhibited at later stages and were less likely to transform into hypertrophic chondrocytes. In L-15-treated groups, the total amount of cartilage extracellular matrix increased during the differentiation process. These results suggest that L-15 promotes chondrogenic differentiation, and that L-15 may be used for cartilage repair or cartilage health supplements. To our knowledge, this is the first report demonstrating the beneficial effect of L-15 treatment on chondrogenic differentiation.

Protective Effects of Peucedanum japonicum Extract against Osteoarthritis in an Animal Model Using a Combined Systems Approach for Compound-Target Prediction

Peucedanum japonicum Thunberg is an herbal medicine used to treat neuralgia, rheumatoid arthritis, and inflammatory-related diseases. However, its effects on osteoarthritis (OA) and its regulatory mechanisms have not been investigated by network analysis. Here, we investigated the pharmacological effects of Peucedanum japonicum extract (PJE) on OA, by combining in vivo effective verification and network pharmacology prediction. Rats in which OA was induced by monosodium iodoacetate (MIA) were treated with PJE (200 mg/kg), and histopathological parameters, weight bearing distribution and inflammatory factors in serum and joint tissue were measured after 28 days of treatment. Additionally, in silico network analysis was used to predict holistic OA regulatory mechanisms of PJE. The results showed that PJE exerted potential protective effects by recovering hind paw weight bearing distribution, alleviating histopathological features of cartilage and inhibiting inflammatory mediator levels in the OA rat model. Furthermore, network analysis identified caspase-3 (CASP3), caspase-7 (CASP7), and cytochrome P450 2D6 (CYP2D6) as potential target genes; in addition, the TNF (Tumor necrosis factor) signaling pathway was linked to OA therapeutic action. Our combined animal OA model and network analysis confirmed the therapeutic effects of PJE against OA and identified intracellular signaling pathways, active compounds and target genes linked to its therapeutic action.