Chondrocyte Proliferation Research Articles

When bones deceive: Beyond skeletal dysplasia

Congenital hypothyroidism results from a partial or complete loss of thyroid function. It is the most common treatable cause of mental retardation. Thyroid hormone facilitates the growth and development of the skeleton through its direct effects on chondrocyte proliferation and differentiation and its permissive effects on the growth hormone. Due to the congenital hypothyroidism screening programs, congenital hypothyroidism is rare, and hence, other differential diagnoses are often considered in children presenting later in life with short stature and coarse facies such as storage disorders, genetic disorders, and skeletal dysplasia. This article aims to assess and discuss the value of radiology, especially plain radiography and ultrasonography in the diagnosis of congenital hypothyroidism and prevent long-term mental retardation and neurological dysfunction.

General Control Non-derepressible 2 Alleviates Cartilage Degeneration and Inhibits NLRP3 Inflammasome Activation in Osteoarthritis.

This study aimed to evaluate the effects of general control non-derepressible 2 (GCN2) on osteoarthritis (OA) in vivo and in vitro. First, anterior cruciate ligament transection (ACLT)-induced rat model and interleukin (IL)-1β-induced ATDC5 chondrocyte were established. Hematoxylin and eosin staining and safranin O/fast green staining were employed for analyzing the histological changes in the rat cartilage. In addition, immunohistochemistry, quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, western blot, and immunofluorescence staining were employed for examining cartilage degeneration-, inflammation-, autophagy-, and NLR family pyrin domain containing 3 (NLRP3) inflammasome-associated genes expression. Moreover, 2,7-dichlorodihydrofluorescein acetoacetic acid probe was utilized for examining the intracellular reactive oxygen species. In addition, 5-ethynyl-2'-deoxyuridine assay and flow cytometry were applied for detecting chondrocyte proliferation and apoptosis IL-1β-treated ATDC5 chondrocytes. GCN2 overexpression ameliorated articular cartilage degeneration and inflammation but promoted chondrocyte autophagy in ACLT-induced OA rats. Similarly, we demonstrated that the upregulation of GCN2 could promote chondrocyte proliferation, suppress chondrocyte apoptosis, attenuate chondrocyte inflammation and extracellular matrix degradation, and promote chondrocyte autophagy. Moreover, GCN2 overexpression could inhibit the activation of NLRP3 inflammasome in IL-1β-induced ATDC5 chondrocyte. Furthermore, 3-methyladenine neutralized the protective and autophagy-promoting effects of GCN2 overexpression on ATDC5 chondrocytes. GCN2 could attenuate inflammation and cartilage degeneration, promote chondrocyte autophagy, and inhibit NLRP3 inflammasome activation in OA.

Biological functions and applications of LncRNAs in the regulation of the extracellular matrix in osteoarthritis.

Osteoarthritis (OA) is a major cause of disability, characterized by chronic pain, irreversible destruction, and loss of function of the articular cartilage. The integrity and arrangement of the composition and structure of the extracellular matrix (ECM) are essential for maintaining the elasticity, integrity, and mechanical support function of the cartilage tissue. Osteoarthritis causes substantial changes in the ECM, driving the progression of the disease. Recent studies have shown that the ECM plays a critical role in the development of cartilage tissue as well as the occurrence and development of osteoarthritis by directly or indirectly regulating chondrocyte proliferation, apoptosis, differentiation, and gene expression. Long non-coding RNAs (lncRNAs) are a class of non-coding RNAs derived from large transcripts. Mutations and disorders of lncRNAs are closely related to the development of osteoarthritis. Abnormal expression of lncRNAs in osteoarthritic cartilage regulates the synthesis and decomposition of the cartilaginous ECM. Therefore, the use of lncRNAs as nucleic acid drugs that regulate their targets may reduce ECM degradation, thereby delaying the pathological progression of osteoarthritis. In this review, the regulatory effects of lncRNAs on ECM in different cell behaviors related to OA are summarized. The roles of lncRNAs in the proliferation, apoptosis, differentiation, and ECM-related gene activity of chondrocytes, as well as the application of lncRNAs as potential gene therapy drugs for the repair and regeneration of osteoarthritic tissue, are also reviewed. A better understanding of the roles of lncRNAs in guiding chondrocyte behavior and ECM metabolism is critical for their future applications in osteoarthritis therapy and regenerative medicine.

TSP-1 increases autophagy level in cartilage by upregulating HSP27 which delays progression of osteoarthritis

This study aimed to determine whether Thrombospondin-1 (TSP-1) can be used as a biomarker to diagnose early osteoarthritis (OA) and whether it has a chondroprotective effect against OA. We examined TSP-1 expression in cartilage, synovial fluid, and serum at different time points after anterior cruciate ligament transection (ACLT) surgery in rats. Subsequently, TSP-1 was overexpressed or silenced to detect its effects on extracellular matrix (ECM) homeostasis, autophagy level, proliferation and apoptosis in chondrocytes. Adenovirus encoding TSP-1 was injected into the knee joints of ACLT rats to test its effect against OA. Combined with proteomic analysis, the molecular mechanism of TSP-1 in cartilage degeneration was explored. Intra-articular injection of an adenovirus carrying the TSP-1 sequence showed chondroprotective effects against OA. Moreover, TSP-1 expression decreases with OA progression and can effectively promote cartilage proliferation, inhibit apoptosis, and helps to sustain the balance between ECM anabolism and catabolism. Overexpression of TSP-1 also can increase autophagy by upregulating Heat Shock Protein 27 (HSP27, hspb1), thereby enhancing its effect as a stimulator of autophagy. TSP-1 is a hopeful strategy for OA treatment.

PiRNA hsa_piR_019949 promotes chondrocyte anabolic metabolism by inhibiting the expression of lncRNA NEAT1

BackgroundOsteoarthritis is a prevalent degenerative joint condition typically found in individuals who are aged 50 years or older. In this study, the focus is on PIWI-interacting RNA (piRNA), which belongs to a category of small non-coding RNAs. These piRNAs play a role in the regulation of gene expression and the preservation of genomic stability. The main objective of this research is to examine the expression of a specific piRNA called hsa_piR_019949 in individuals with osteoarthritis, to understand its impact on chondrocyte metabolism within this condition.MethodsWe analyzed piRNA expression in osteoarthritis cartilage using the GEO database. To understand the impact of inflammatory factors on piRNA expression in chondrocytes, we conducted RT-qPCR experiments. We also investigated the effect of piRNA hsa_piR_019949 on chondrocyte proliferation using CCK-8 and clone formation assays. Furthermore, we assessed the influence of piRNA hsa_piR_019949 on chondrocyte apoptosis by conducting flow cytometry analysis. Additionally, we examined the differences in cartilage matrix composition through safranine O staining and explored the downstream regulatory mechanisms of piRNA using transcriptome sequencing. Lentiviral transfection of NEAT1 and NLRP3 was performed to regulate the metabolism of chondrocytes.ResultsUsing RNA sequencing technology, we compared the gene expression profiles of 5 patients with osteoarthritis to 3 normal controls. We found a gene called hsa_piR_019949 that showed differential expression between the two groups. Specifically, hsa_piR_019949 was downregulated in chondrocytes when stimulated by IL-1β, an inflammatory molecule. In further investigations, we discovered that overexpression of hsa_piR_019949 in vitro led to increased proliferation and synthesis of the extracellular matrix in chondrocytes, which are cells responsible for cartilage formation. Conversely, suppressing hsa_piR_019949 expression resulted in increased apoptosis (cell death) and degradation of the extracellular matrix in chondrocytes. Additionally, we found that the NOD-like receptor signaling pathway is linked to the low expression of hsa_piR_019949 in a specific chondrocyte cell line called C28/I2. Furthermore, we observed that hsa_piR_019949 can inhibit the expression of a long non-coding RNA called NEAT1 in chondrocytes. We hypothesize that NEAT1 may serve as a downstream target gene regulated by hsa_piR_019949, potentially influencing chondrocyte metabolism and function in the context of osteoarthritis.ConclusionsPiRNA hsa_piR_019949 has shown potential in promoting the proliferation of chondrocytes and facilitating the synthesis of extracellular matrix in individuals with osteoarthritis. This is achieved by inhibiting the expression of a long non-coding RNA called NEAT1. The implication is that by using hsa_piR_019949 mimics, which are synthetic versions of the piRNA, as a therapeutic approach, it may be possible to effectively treat osteoarthritis.

Circular RNA CircACAP2 regulates temporomandibular joint osteoarthritis via miR-21-5p/PLAG1 axis.

The pathogenesis of temporomandibular joint osteoarthritis (TMJOA) remains not fully understood. Our previous studies demonstrated that miR-21-5p may participate in the TMJOA development and the interaction between circRNA-ACAP2 (CircACAP2) and miR-21-5p. Our present study aimed to explore the biological functions and regulatory mechanisms of CircACAP2 in TMJOA. The differential expression pattern of CircACAP2 in OA and normal tissues or cells was detected. CircACAP2 biological functions experiments were performed in chondrocytes by overexpression and interference techniques. The interaction of CircACAP2 with miR-21-5p and downstream target mRNA, polymorphic adenoma gene 1 (PLAG1), was predicted by bioinformatic databases and then demonstrated by dual-luciferase reporter assay. The biological role of CircACAP2 in TMJOA was investigated and validated in a mouse model. The expression level of CircACAP2 was markedly reduced in OA cartilage and directly related to chondrocyte proliferation and apoptosis as well as ECM metabolism in the cartilage. CircACAP2 functioned in chondrocytes via targeting miR-21-5p and PLAG1. Overexpressing of CircACAP2 alleviated TMJOA in mouse models. The present study unveiled that CircACAP2/miR-21-5p/PLAG1 axis may play an important regulatory role in TMJOA progression, which may highlight a potentially effective intervention and therapeutic strategy for the treatment of TMJOA.

MICROENVIRONMENTAL DEPENDENCE OF PROPER CHONDROCYTIC MATURATION

Articular cartilage is a relatively hypoxic tissue with a unique extracellular matrix that is enriched with cations, resulting in an elevated interstitial fluid osmolarity. Several biomechanical and physicochemical stimuli are reported to influence chondrocyte metabolism. For regenerative in vitro applications, increasing the extracellular osmolarity above plasma level to more physiological valuesinduces chondrogenic marker expression and the differentiation of chondroprogenitor cells. Calcineurin inhibitor FK506 modulates the differentiation of primary chondrocytes under such conditions and its effect on cell proliferation, extracellular matrix quality, and BMP- and TGF-β signaling will be described. Supraphysiological osmolarity compromises chondrocyte proliferation, while physosmolarity or FK506 did not. Rather, the combination of the latter increased proteoglycan and collagen expression in chondrocytesin vitro and in situ, affecting expression of TGF-β-inducible protein TGFBI and chondrogenic (SOX9, Col2) as well as terminal differentiation markers (e.g., Col10). Surprisingly, expression of particularly minor collagens (e.g., Col9, Col11) was improved. Physiological osmolarity seems to promote terminal chondrogenic differentiation of progenitor cells through sensitization of TGF-β superfamily signaling at the type I receptor. While hyperosmolarity alone facilitates TGF-β superfamily signaling, FK506 seems to enhance signaling by releasing the FKBP12 break from the type I receptor to improve collagenous marker expression. Our data help explaining seemingly contradictory earlier findings and potentially benefit future cell-based cartilage repair strategies.

Strong, tough, and elastic poly(vinyl alcohol)/polyacrylamide DN hydrogels based on the Hofmeister effect for articular cartilage replacement.

Traditional hydrogels are usually weak and brittle, which limit their application in articular cartilage replacement because cartilage is generally strong, tough, and elastic in nature. Therefore, it is highly desirable to construct hydrogels to mimic the mechanical properties of the native articular cartilage. Herein, in this work, poly(vinyl alcohol)/polyacrylamide (PVA/PAM) DN hydrogels were prepared by in situ polymerization, which were then treated with Hofmeister series ions (Cit3-, SO42-, and Cl-) to achieve H-PVA/PAM DN hydrogels. Among the three Hofmeister ions, the DN hydrogel treated with Cit3- (named PVA/PAM-Cit) showed the densest microstructure and the highest crystallinity degree. In this context, PVA/PAM-Cit exhibited a tensile strength of 18.9 ± 1.6 MPa, a compressive strength of 102.3 ± 7.9 MPa, a tensile modulus of 10.6 ± 2.1 MPa, a compressive modulus of 8.9 ± 0.8 MPa, and a roughness of 66.2 ± 4.2 MJ m-3, respectively, which were the highest strength and modulus, and the second highest toughness when compared with those of the reported PVA and PVA based DN hydrogels so far. It also showed an extreme high elasticity, which could maintain a stress of 99.2% after 500 cycles of fatigue testing. Additionally, PVA/PAM-Cit can promote the adhesion, spreading and proliferation of chondrocytes. These results verify that such a strong, tough, and elastic hydrogel could be a novel candidate material for articular cartilage replacement.

TREM2 promotes macrophage polarization from M1 to M2 and suppresses osteoarthritis through the NF-κB/CXCL3 axis.

Objective: Osteoarthritis (OA) is the most prominent chronic arthritic disease, affecting over 3 billion people globally. Synovial macrophages, as immune cells, play an essential role in cartilage damage in OA. Therefore, regulating macrophages is crucial for controlling the pathological changes in OA. Triggering receptor expressed on myeloid cells 2 (TREM2), as expressed on immune cell surfaces, such as macrophages and dendritic cells, has suppressed inflammation and regulated M2 macrophage polarization but demonstrated an unknown role in synovial macrophage polarization in OA. This study aimed to investigate TREM2 expression downregulation in OA mice macrophages. Furthermore, the expression trend of TREM2 was associated with polarization-related molecule expression in macrophages of OA mice. Results: We used TREM2 knockout (TREM2-KO) mice to observe that TREM2 deficiency significantly exacerbated the joint inflammation response in OA mice, thereby accelerating disease progression. Separating macrophages and chondrocytes from TREM2-KO mice and co-cultivating them significantly increased chondrocyte apoptosis and inhibited chondrocyte proliferation. Further, TREM2 deficiency also significantly enhanced phosphatidylinositol 3-kinase(PI3K)/AKT signaling pathway activation, increasing nuclear factor kappa light chain enhancer of activated B cells (NF-κB) signaling and C-X-C Motif Chemokine Ligand 3 (CXCL3) expression. Furthermore, NF-κB signaling pathway inhibition significantly suppressed arthritis inflammation in OA mice, thereby effectively alleviating TREM2 deficiency-related adverse effects on chondrocytes. Notably, knocking down CXCL3 of TREM2-KO mice macrophages significantly inhibits inflammatory response and promotes chondrocyte proliferation. Intravenous recombinant TREM2 protein (soluble TREM2, sTREM2) injection markedly promotes macrophage polarization from M1 to M2 and improves the joint tissue pathology and inflammatory response of OA. Conclusion: Our study reveals that TREM2 promotes macrophage polarization from M1 to M2 during OA by NF-κB/CXCL3 axis regulation, thereby improving the pathological state of OA.

Ddx5 participates in regulation of Col10a1 expression and chondrocyte hypertrophic differentiation in vitro.

The type X collagen gene (Col10a1), is a specific molecular marker of hypertrophic chondrocytes during endochondral ossification. Col10a1 expression is known to be influenced by many regulators. In this study, we aim to investigate how DEAD-box helicase 5 (DDX5), a potential binding factor for Col10a1 enhancer, may play a role in Col10a1 expression and chondrocyte hypertrophic differentiation in vitro. The potential binding factors of the 150-bp Col10a1 cis-enhancer were identified with the hTFtarget database. The expression of DDX5 and COL10A1 was detected by quantitative real-time PCR (qRT-PCR) and Western blot in chondrogenic ATDC5 and MCT cell models with or without Ddx5 knockdown or overexpression. Dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) were performed to determine the interaction between DDX5 and the Col10a1 enhancer. The effect and mechanism of DDX5 on chondrocyte differentiation and maturation was evaluated by alcian blue, alkaline phosphatase (ALP), and alizarin red staining in ATDC5 cell lines with stable knockdown of Ddx5. DDX5 was identified as a potential binding factor for the Col10a1 enhancer. The expression of DDX5 in hypertrophic chondrocytes was higher than that in proliferative chondrocytes. Knockdown of Ddx5 decreased, while overexpression of Ddx5 slightly increased COL10A1 expression. DDX5 promotes the enhancer activity of Col10a1 as demonstrated by dual-luciferase reporter assay, and the ChIP experiment suggests a direct interaction between DDX5 and the Col10a1 enhancer. Compared to the control (NC) group, we observed weaker alcian blue and ALP staining intensity in the Ddx5 knockdown group of ATDC5 cells cultured both for 7 and 14 days. Whereas weaker alizarin red staining intensity was only found in the Ddx5 knockdown group of cells cultured for 7 days. Meanwhile, knockdown of Ddx5 significantly reduced the level of runt-related transcription factor 2 (RUNX2) in related ATDC5 cells examined. Our results suggest that DDX5 acts as a positive regulator for Col10a1 expression and may cooperate with RUNX2 together to control Col10a1 expression and promote the proliferation and maturation of chondrocytes.

Promising horizons in achondroplasia along with the development of new drugs.

Achondroplasia (ACH) is a representative skeletal disorder characterized by rhizomelic shortened limbs and short stature. ACH is classified as belonging to the fibroblast growth factor receptor 3 (FGFR3) group. The downstream signal transduction of FGFR3 consists of STAT1 and RAS/RAF/MEK/ERK pathways. The mutant FGFR3 found in ACH is continuously phosphorylated and activates downstream signals, resulting in abnormal proliferation and differentiation of chondrocytes in the growth plate and cranial base synchondrosis. A patient registry has been developed and has contributed to revealing the natural history of ACH patients. Concerning the short stature, the adult height of ACH patients ranges between 126.7-135.2 cm for men and 119.9-125.5 cm for women in many countries. Along with severe short stature, foramen magnum stenosis and spinal canal stenosis are major complications: the former leads to sleep apnea, breathing disorders, myelopathy, hydrocephalus, and sudden death, and the latter causes pain in the extremities, numbness, muscle weakness, movement disorders, intermittent claudication, and bladder-rectal disorders. Growth hormone treatment is available for ACH only in Japan. However, the effect of the treatment on adult height is not satisfactory. Recently, the neutral endopeptidase-resistant CNP analogue vosoritide has been approved as a new drug for ACH. Additionally in development are a tyrosine kinase inhibitor, a soluble FGFR3, an antibody against FGFR3, meclizine, and the FGF2-aptamer. New drugs will bring a brighter future for patients with ACH.

Impact of Different Culture Media on Proliferation and Dedifferentiation of Fatal Chondrocytes

Impact of Different Culture Media on Proliferation and Dedifferentiation of Fatal Chondrocytes

ROR2-Related Skeletal Dysplasia Reveals Disrupted Chondrocyte Polarity through Modulation of BMP/TGF-β Signaling.

Genetic studies have shown that Robinow syndrome (RS), a rare skeletal dysplasia, is caused by ROR2 mutation. However, the cell origin and molecular mechanisms underlying this disease remain elusive. We established a conditional knockout system by crossing Prx1cre and Osxcre with Ror2 flox/flox mice. and conducted histological and immunofluorescence analyses to investigate the phenotypes during skeletal development. In the Prx1cre line, we observed RS-like skeletal abnormities, including short stature and an arched skull. Additionally, we found inhibition of chondrocyte differentiation and proliferation. In the Osxcre line, loss of ROR2 in osteoblast lineage cells led to reduced osteoblast differentiation during both embryonic and postnatal stages. Furthermore, ROR2 mutant mice exhibited increased adipogenesis in the bone marrow compared to their littermate controls. To further explore the underlying mechanisms, bulk RNA-seq analysis of Prx1cre; Ror2 flox/flox embryos was performed, results revealed decreased BMP/TGF-β signaling. Immunofluorescence analysis further confirmed the decreased expression of p-smad1/5/8, accompanied by disrupted cell polarity in the developing growth plate. Pharmacological treatment using FK506 partially rescued the skeletal dysplasia and resulted in increased mineralization and osteoblast differentiation. By modeling the phenotype of RS in mice, our findings provide evidence for the involvement of mesenchymal progenitors as the cell origin and highlight the molecular mechanism of BMP/TGF-β signaling in skeletal dysplasia.

Identification and functional coordination analysis of gene co-expression networks in different tissues of XBP1 cartilage-specific deficient mice.

Abnormal differentiation and proliferation of chondrocytes leads to various diseases related to growth and development. The process of chondrocyte differentiation involves a series of complex cellular and molecular interactions. X-box binding protein 1 (XBP1), an essential molecule of the unfolded protein response (UPR) in Endoplasmic Reticulum (ER) stress, participated in cartilage development and causes other related diseases. We previously reported that XBP1 deficiency in cartilage impacts the function and associated diseases of many different tissues including cartilage. However, how differential expression of genes modulates the roles of cartilage and other tissues when XBP1 is lack of in chondrocytes remains unclear. We aimed to screen for differentially expressed (DE) genes in cartilage, brain, heart, and muscle by high-throughput sequencing in XBP1 cartilage-specific knockout (CKO) mice. Further, gene co-expression networks were constructed by weighted gene co-expression network analysis (WGCNA) algorithm and pivot genes were identified in the above four tissues. Protein detection, Hematoxylin-eosin (HE) staining and immunohistochemistry (IHC) experiments have proved that these differentially co-expressed genes participate in the downstream regulatory pathway of different tissues and affect tissue function.Significantly differentially expressed mRNAs [differentially expressed genes (DEGs)] were identified between XBP1 CKO mice and controls in cartilage, brain, heart, and muscle tissues, including 610, 126, 199 and 219 DEGs, respectively. 39 differentially co-expressed genes were identified in the above four tissues, and they were important pivot genes. Comprehensive analysis discovered that XBP1 deficiency in cartilage influences the difference of co-expressed genes between cartilage and other different tissues. These differentially co-expressed genes participate in downstream regulatory pathways of different tissues and affect tissue functions. Collectively, our conclusions may contribute potential biomarkers and molecular mechanisms for the mutual modulation between cartilage and different tissues and the diagnosis and treatment of diseases caused by abnormalities in different tissues. The analysis also provides meaningful insights for future genetic discoveries.

Development and evaluation of 3D composite scaffolds with piezoelectricity and biofactor synergy for enhanced articular cartilage regeneration.

The inability of articular cartilage to self-repair following injuries frequently precipitates osteoarthritis, profoundly affecting patients' quality of life. Given the limitations inherent in current clinical interventions, an urgent need exists for more effective cartilage regeneration methodologies. Previous studies have underscored the potential of electrical stimulation in cartilage repair, thus motivating the investigation of innovative strategies. The present study introduces a three-dimensional scaffold fabricated through a composite technique that leverages the synergy between piezoelectricity and biofactors to enhance cartilage repair. This scaffold is composed of polylactic acid (PLLA) and barium titanate (BT) for piezoelectric stimulation and at the bottom with a collagen-coated layer infused with fibroblast growth factor-18 (FGF-18) for biofactor delivery. Designed to emulate the properties of natural cartilage, the scaffold enables controlled generation of piezoelectric charges and the sustained release of biofactors. In vitro tests confirm that the scaffold promotes chondrocyte proliferation, matrix hyperplasia, cellular migration, and the expression of genes associated with cartilage formation. Moreover, in vivo studies on rabbits have illustrated its efficacy in catalyzing the in situ regeneration of articular cartilage defects and remodeling the extracellular matrix. This innovative approach offers significant potential for enhancing cartilage repair and holds profound implications for regenerative medicine.

Gubi Zhitong formula alleviates osteoarthritis in vitro and in vivo via regulating BNIP3L-mediated mitophagy

BackgroundOsteoarthritis (OA) is characterized by degeneration of articular cartilage, leading to joint pain and dysfunction. Gubi Zhitong formula (GBZTF), a traditional Chinese medicine formula, has been used in the clinical treatment of OA for decades, demonstrating definite efficacy. However, its mechanism of action remains unclear, hindering its further application. MethodsThe ingredients of GBZTF were analyzed and performed with liquid chromatography-mass spectrometry (LC-MS). 6 weeks old SD rats were underwent running exercise (25 m/min, 80 min, 0°) to construct OA model with cartilage wear and tear. It was estimated by Micro-CT, Gait Analysis, Histological Stain. RNA-seq technology was performed with OA Rats' cartilage, and primary chondrocytes induced by IL-1β (mimics OA chondrocytes) were utilized to evaluated and investigated the mechanism of how GBZTF protected OA cartilage from being damaged with some functional experiments. ResultsA total of 1006 compounds were identified under positive and negative ion modes by LC-MS. Then, we assessed the function of GBZTF through in vitro and vivo. It was found GBZTF could significantly up-regulate OA rats’ limb coordination and weight-bearing capacity, and reduce the surface and sub-chondral bone erosions of OA joints, and protect cartilage from being destroyed by inflammatory factors (iNOS, IL-6, IL-1β, TNF- α, MMP13, ADAMTS5), and promote OA chondrocytes proliferation and increase the S phage of cell cycle. In terms of mechanism, RNA-seq analysis of cartilage tissues revealed 1,778 and 3,824 differentially expressed genes (DEGs) in model vs control group and GBZTF vs model group, respectively. The mitophagy pathway was most significantly enriched in these DEGs. Further results of subunits of OA chondrocytes confirmed that GBZTF could alleviate OA-associated inflammation and cartilage damage through modulation BCL2 interacting protein 3-like (BNIP3L)-mediated mitophagy. ConclusionThe therapeutic effectiveness of GBZTF on OA were first time verified in vivo and vitro through functional experiments and RNA-seq, which provides convincing evidence to support the molecular mechanisms of GBZTF as a promising therapeutic decoction for OA.

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

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

Small RNA signatures of the anterior cruciate ligament from patients with knee joint osteoarthritis.

Introduction: The anterior cruciate ligament (ACL) is susceptible to degeneration, resulting in joint pain, reduced mobility, and osteoarthritis development. There is currently a paucity of knowledge on how anterior cruciate ligament degeneration and disease leads to osteoarthritis. Small non-coding RNAs (sncRNAs), such as microRNAs and small nucleolar RNA (snoRNA), have diverse roles, including regulation of gene expression. Methods: We profiled the sncRNAs of diseased osteoarthritic ACLs to provide novel insights into osteoarthritis development. Small RNA sequencing from the ACLs of non- or end-stage human osteoarthritic knee joints was performed. Significantly differentially expressed sncRNAs were defined, and bioinformatics analysis was undertaken. Results and Discussion: A total of 184 sncRNAs were differentially expressed: 68 small nucleolar RNAs, 26 small nuclear RNAs (snRNAs), and 90 microRNAs. We identified both novel and recognized (miR-206, -365, and -29b and -29c) osteoarthritis-related microRNAs and other sncRNAs (including SNORD72, SNORD113, and SNORD114). Significant pathway enrichment of differentially expressed miRNAs includes differentiation of the muscle, inflammation, proliferation of chondrocytes, and fibrosis. Putative mRNAs of the microRNA target genes were associated with the canonical pathways "hepatic fibrosis signaling" and "osteoarthritis." The establishing sncRNA signatures of ACL disease during osteoarthritis could serve as novel biomarkers and potential therapeutic targets in ACL degeneration and osteoarthritis development.

Histological Evaluation of Arthritis in Mice

Arthritis is one the almost commonly prevalent painful diseases which cause limit the movement of joints. This study conducts to investigate histological alterations resulted in rheumatoid arthritis (RA)-induced in mice and estimating the levels of some serum biomarkers including serum IL-6, CRP and RF. Totally, 30 were purchased, acclimated, and divided into two groups; control that injected distilled water, and arthritis that injected adjuvant (CFA). Post the 25th day of experiment, all study mice of both groups were subjected for collection of blood and right ankle joints. Serologically, the findings of IL-6, CRP and RF of arthritis group were elevated significantly when compare to control mice. Histologically, the findings observed in mice of control group were included the proliferation of chondrocytes of articular cartilage with moderate cellular and subchondral marrow space, infiltration few inflammatory cells in dermis, proliferation of chondrocytes in articular cartilage with absence of inflammatory reaction in synovial cavity, moderate infiltration of inflammatory cells in subcutaneous tissue, nearly normal articular cartilage with regular tidemark and absence of sclerosis in marrow spaces, regenerative articular cartilage and regular tidemark line with presence of very narrow distance between articular cartilage and marrow bone, and existence of normal bone trabeculae. In arthritis mice, there were an infiltration of inflammatory cells in subcutaneous tissues and dermis, marked increases in numbers of osteoclasts, sclerosis, regular tidemark and proliferation of chondrocytes, low amonunt of abscesses in subcutaneous tissue, thickness of bone trabeculae, fragments of bone, subchondral sclerosis, moderate distance between bone and articular cartilage. In conclussion, RA causes severe impacts on tissues of affected joints. Studying the mechanism of inhibition during different inflammatory process appear needed.

The circular RNA expression profile of human auricle cartilage and the role of circCOL1A2 in isolated microtia

Microtia is one of the most common craniofacial birth defects worldwide, and its primary clinical manifestation is auricle deformity. Epigenetic factors are known to contribute to the etiology of microtia, yet the involvement of circular RNAs (circRNAs) in human auricle development and their association with microtia remains poorly understood. In this study, we aimed to analyze differentially expressed circRNAs and explore their functional implications in isolated microtia. By employing circRNA microarray analysis and bioinformatics approaches, we identified 340 differentially expressed circRNAs in auricle cartilage of patients with isolated microtia, comprising 152 upregulated and 188 downregulated circRNAs. A circRNA-mRNA co-expression network was constructed, followed by gene ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Subsequently, we selected four significantly upregulated circRNAs from the co-expression network based on their association with cartilage development and validated their expressions in 30 isolated microtia and 30 control clinical auricle cartilage samples. Among these circRNAs, circCOL1A2, the most significantly upregulated circRNA, was selected as a representative circRNA for investigating its role in isolated microtia. Overexpression of circCOL1A2 significantly inhibited chondrocyte proliferation and chondrogenic differentiation of human mesenchymal stem cells. Additionally, circCOL1A2 upregulated Dermatan Sulfate Epimerase Like (DSEL) expression by sponging miR-637 through the competing endogenous RNA (ceRNA) mechanism. Notably, the downregulation of DSEL attenuated the inhibitory effect of circCOL1A2 overexpression on cell proliferation and chondrogenic differentiation. Collectively, these findings highlight the involvement of circCOL1A2 in the pathogenesis of isolated microtia and emphasize the potential significance of dysregulated circRNAs in disease development.