Chitosan oligosaccharides inhibit IL-1β-induced chondrocyte apoptosis via the P38 MAPK signaling pathway

Ultrasound-activated piezoelectric biomaterials for cartilage regeneration

Due to the low density of chondrocytes and limited ability to repair damaged extracellular matrix (ECM) in cartilage, many patients with congenital or acquired craniofacial trauma require filler graft materials to support facial structure, restore function, improve self-confidence, and regain socialization. Ultrasound has the capacity to stimulate piezoelectric materials, converting mechanical energy into electrical signals that can regulate the metabolism, proliferation, and differentiation of chondrocytes. This unique property has sparked growing interest in using piezoelectric biomaterials in regenerative medicine. In this review, we first explain the principle behind ultrasound-activated piezoelectric materials and how they generate piezopotential. We then review studies demonstrating how this bioelectricity promotes chondrocyte regeneration, stimulates the secretion of key extracellular components and supports cartilage regeneration by activating relevant signaling pathways. Next, we discuss the properties, synthesis, and modification strategies of various piezoelectric biomaterials. We further discuss recent progresses in the development of ultrasound-activated piezoelectric biomaterials specifically designed for cartilage regeneration. Lastly, we discuss future research challenges facing this technology, ultrasound-activated piezoelectric materials for cartilage regeneration engineering. While the technology holds great promise, certain obstacles remain, including issues related to material stability, precise control over ultrasound parameters, and the integration of these systems into clinical settings. The combination of ultrasound-activated piezoelectric technology with other emerging fields, such as Artificial Intelligence (AI) and cartilage organoid chips, may open new frontiers in regenerative medicine. We hope this review encourages further exploration of ultrasound-activated strategies for piezoelectric materials and their future applications in regenerative medicines.

Inhibition against p38/MEF2C pathway by Pamapimod protects osteoarthritis chondrocytes hypertrophy

BACKGROUND

The p38 mitogen-activated protein kinase pathway plays an important role in the pathogenesis of osteoarthritis (OA) involving in hypertrophy, calcification, and apoptosis of chondrocytes (CHs). In this study, we focused on a p38 inhibitor named Pamapimod (PAM) in the effect of CH hypertrophy degeneration.

METHODS

CHs were isolated from the cartilage collected from OA patients. Insulin-Transferrin-Selenium (ITS) medium was used as a hypertrophic inducer to establish CH hypertrophy model. Asiatic acid (AA) was used to activate p38 phosphorylation. We transfected CHs with myocyte enhancer factor 2C (MEF2C)-plasmid to upregulate MEF2C expression. Chondrogenic gene expression such as type II collagen and SOX-9, and hypertrophic genes such as type X collagen, MMP-13, and Runx-2 were analyzed by western blot, real-time polymerase chain reaction or immunofluorescence.

RESULTS

ITS and AA all contributed to the CHs hypertrophy with an upregulation of p-p38 and MEF2C protein expression. PAM treatments significantly inhibited p-p38 and MEF2C expression, down-regulated type X collagen, MMP-13, and Runx-2 expression and upregulated type II collagen and SOX-9 levels. PAM indirectly affected MEF2C expression and resulted in CHs hypertrophy suppression.

CONCLUSIONS

PAM protects CHs hypertrophy by the inhibition of the p38/MEF2C pathway.

Bibliometric analysis of chondrocyte apoptosis in knee osteoarthritis

BACKGROUND

Apoptosis, a form of programmed cell death, plays a significant role in osteoarthritis; however, bibliometric studies in this field remain scarce. Bibliometrics provides a visual representation of research outcomes and trends, guiding future investigations.

METHOD

Journal data from January 1, 2013, to December 31, 2023, in this field were obtained from the Web of Science (WOS) core database. Analysis was conducted using VOSviewer and CiteSpace.

RESULTS

Analysis revealed that over the past decade, 794 articles were published in 299 journals by 4447 authors from 49 countries and 877 institutions. The top contributors were China, the United States, and the United Kingdom. Zhuang Chao emerged as the most prolific author, and "osteoarthritis and cartilage" ranked as the most frequently cited journal. Keyword clustering focused on mechanisms, inflammation, and cartilage. The most-cited article was "chondrocyte apoptosis in the pathogenesis of osteoarthritis" in the "International Journal of Molecular Sciences." Burst word analysis highlighted extracellular matrix, circular RNA, micro RNA, indicating current research hotspots.

CONCLUSION

Utilizing bibliometrics and visual analysis, we explored the hotspots and trends in the field of chondrocyte apoptosis in osteoarthritis. Extracellular matrix, Circular RNA, Micro RNA, among others, are likely to become future research focal points and frontiers.

Low Deacetylation Degree Chitosan Oligosaccharide Protects against IL-1β Induced Inflammation and Enhances Autophagy Activity in Human Chondrocytes

Osteoarthritis (OA) is a degenerative joint disease, which can lead to joint pain, stiffness, deformity and dysfunction, that seriously affects the quality of life in patients. At present, the treatments of OA mainly include early pharmacological treatment and late joint replacement. However, current pharmacological treatment has limited efficacy and undesired side effects.Chitosan oligosaccharide (COS) is a kind of nontoxic and biodegradable oligo-saccharide, which is composed of 2-20 glucosamine or N-acetylglucosamine linked by β-1,4 glycosidic bond. Studies have shown that COS has significant biological properties like antimicrobial, anti-inflammatory, antioxidant, and anti-tumor, as well as immunoregulation ability. However, the effects of COS on OA have not been clarified. In this study, we explored the protective effects of COS with different degrees of deacetylation on chondrocytes stimulated by interleukin 1β (IL-1β) in vitro.The results showed that IL-1β inhibited cell proliferation and promoted cell apoptosis. Besides that, IL-1β increased the expression of the major chondro-degrading genes MMP13 and ADAMTS-5, while decreased the expression of COL2A and ACAN. COS with different degrees of deacetylation (HDACOS, MDACOS, LDACOS) had different effects on IL-1β induced inflammation. LDACOS had the most obvious anti-inflammatory effects to inhibit the expression of MMP13 and ADAMTS-5 while promoted the expression of COL2A and ACAN. In addition, we found that the expression of autophagy-related gene Beclin-1 was up-regulated, and the ratio of LC3-II/LC3-I was increased in the LDACOS group. Furthermore, transmission electron microscopy (TEM) analysis showed that the number of intracellular autophagosomes increased significantly with the treatment of LDACOS. Based on our research, we suggested that LDACOS could inhibit chondrocytes inflammation and promote cell autophagy, and might be a protective drug for the treatment of OA.

Anisotropic Chitosan Scaffolds Generated by Electrostatic Flocking Combined with Alginate Hydrogel Support Chondrogenic Differentiation

The replacement of damaged or degenerated articular cartilage tissue remains a challenge, as this non-vascularized tissue has a very limited self-healing capacity. Therefore, tissue engineering (TE) of cartilage is a promising treatment option. Although significant progress has been made in recent years, there is still a lack of scaffolds that ensure the formation of functional cartilage tissue while meeting the mechanical requirements for chondrogenic TE. In this article, we report the application of flock technology, a common process in the modern textile industry, to produce flock scaffolds made of chitosan (a biodegradable and biocompatible biopolymer) for chondrogenic TE. By combining an alginate hydrogel with a chitosan flock scaffold (CFS+ALG), a fiber-reinforced hydrogel with anisotropic properties was developed to support chondrogenic differentiation of embedded human chondrocytes. Pure alginate hydrogels (ALG) and pure chitosan flock scaffolds (CFS) were studied as controls. Morphology of primary human chondrocytes analyzed by cLSM and SEM showed a round, chondrogenic phenotype in CFS+ALG and ALG after 21 days of differentiation, whereas chondrocytes on CFS formed spheroids. The compressive strength of CFS+ALG was higher than the compressive strength of ALG and CFS alone. Chondrocytes embedded in CFS+ALG showed gene expression of chondrogenic markers (COL II, COMP, ACAN), the highest collagen II/I ratio, and production of the typical extracellular matrix such as sGAG and collagen II. The combination of alginate hydrogel with chitosan flock scaffolds resulted in a scaffold with anisotropic structure, good mechanical properties, elasticity, and porosity that supported chondrogenic differentiation of inserted human chondrocytes and expression of chondrogenic markers and typical extracellular matrix.

Chitosan oligosaccharide attenuates endoplasmic reticulum stress-associated intestinal apoptosis via the Akt/mTOR pathway

Endoplasmic reticulum stress (ERS) and apoptosis are widely considered as essential factors associated with intestinal disorders, whereas nutritional therapeutic approaches targeting ERS may control disease activity. Thus, we focus on the potential benefit of chitosan oligosaccharide (COS) on repressing ERS and ERS-induced apoptosis. In this study, we used the ERS model with tunicamycin (TM)-induced IPEC-J2 cells in vitro and nutrient deprivation-induced ERS in piglets to evaluate the protective mechanism of COS against ERS and ERS-induced apoptosis. The results showed that cells were characterized by activation of the unfolded protein response (UPR) and increased epithelial apoptosis upon exposure to TM. However, these changes were significantly attenuated by COS and the expressions of Akt and mTORC1 were inhibited. Furthermore, a specific inhibitor of mTOR confirmed the suppression of Akt and reduced the activation of the UPR and apoptosis. In vivo, COS protected against nutrient deprivation-induced ERS in the jejunum of piglets, in which the overexpression of the UPR and apoptosis was rescued. Consistently, COS attenuated nutrient deprivation-induced disruption of intestinal barrier integrity and functional capacity. Together, we provided the first evidence that COS could protect against intestinal apoptosis through alleviating severe ERS, which may be related to the inhibition of the Akt/mTOR signaling pathway.

Gonadotropin-inhibiting hormone promotes apoptosis of bovine ovary granulosa cells

Gonadotropin-inhibiting hormone (GnIH) inhibits the synthesis and release of gonadotropin by binding to its receptor. GnIH is involved in animal reproductive regulation, especially ovary function. It can regulate the proliferation, apoptosis and hormone secretion of follicular cells. However, the role and molecular mechanism of GnIH in bovine granulosa cell (bGC) apoptosis is unclear. Here, the effects of GnIH on proliferation, apoptosis, and mitochondrial function of bGCs were detected. A 10^-6 mol/mL concentration of GnIH inhibited bGC proliferation, promoted GC apoptosis, and damaged mitochondrial function. Additionally, GnIH significantly decreased the phosphorylation level of p38 (P < 0.01). To explore the role of the p38 signaling pathway in the process of GnIH-induced apoptosis in bGCs, an activator of p38 (U46619) was used to pretreat bGCs. U46619 pretreatment significantly alleviated GnIH damage to bGCs, including proliferation, apoptosis, and mitochondrial function. In conclusion, these results demonstrated that GnIH inhibited proliferation and promoted apoptosis of bGCs via the p38 signaling pathway.

Silencing UHRF1 enhances cell autophagy to prevent articular chondrocytes from apoptosis in osteoarthritis through PI3K/AKT/mTOR signaling pathway

Osteoarthritis (OA) is a common chronic degenerative joint disease, and chondrocyte apoptosis is one of most important pathological changes of OA pathogenesis. Growing studies have shown that Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is an important epigenetic regulatory factor that regulates cell proliferation and apoptosis of various tumors, but its role in OA remains ill-defined. In the present study, we found that UHRF1 expression was increased in human OA cartilage tissues, compared with normal cartilage tissues. Interleukin-1β (IL-1β), a major inflammatory cytokine that promotes cartilage degradation in OA, was used to stimulate primary human chondrocytes in vitro. The expression of UHRF1 was also enhanced in IL-1β-induced chondrocytes. Moreover, down-regulation of UHRF1 induced an increase on cell proliferation and autophagy, and a decrease on apoptosis of chondrocytes after IL-1β treatment. Further data indicated that silencing UHRF1 attenuated the up-regulation of IL-1β on phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway in chondrocytes. Then, an activator of PI3K weakened the effect of UHRF1 silencing on cell proliferation, autophagy, apoptosis of IL-1β-induced chondrocytes, and the cell autophagy special inhibitor 3-methyladenine (3-MA) also showed a same impact on UHRF1, hence suggesting that knockdown of UHRF1 enhances cell autophagy to protect chondrocytes from apoptosis in OA through PI3K/AKT/mTOR signaling pathway. In conclusion, our study suggests that UHRF1 may be a potential regulator of chondrocyte apoptosis in the pathogenesis of OA.

The emerging role of fibroblast-like synoviocytes-mediated synovitis in osteoarthritis: An update

Osteoarthritis (OA), the most ubiquitous degenerative disease affecting the entire joint, is characterized by cartilage degradation and synovial inflammation. Although the pathogenesis of OA remains poorly understood, synovial inflammation is known to play an important role in OA development. However, studies on OA pathophysiology have focused more on cartilage degeneration and osteophytes, rather than on the inflamed and thickened synovium. Fibroblast-like synoviocytes (FLS) produce a series of pro-inflammatory regulators, such as inflammatory cytokines, nitric oxide (NO) and prostaglandin E₂ (PGE₂ ). These regulators are positively associated with the clinical symptoms of OA, such as inflammatory pain, joint swelling and disease development. A better understanding of the inflammatory immune response in OA-FLS could provide a novel approach to comprehensive treatment strategies for OA. Here, we have summarized recently published literatures referring to epigenetic modifications, activated signalling pathways and inflammation-associated factors that are involved in OA-FLS-mediated inflammation. In addition, the current related clinical trials and future perspectives were also summarized.

Chitosan oligosaccharide inhibits skull resorption induced by lipopolysaccharides in mice

Background

Low-molecular-weight chitosan oligosaccharide (LMCOS), a chitosan degradation product, is water-soluble and easily absorbable, rendering it a popular biomaterial to study. However, its effect on bone remodelling remains unknown. Therefore, we evaluated the effect of LMCOS on lipopolysaccharide (LPS)-induced bone resorption in mice.

Methods

Six-week-old male C57BL/6 mice (n = five per group) were randomly divided into five groups: PBS, LPS, LPS + 0.005% LMCOS, LPS + 0.05% LMCOS, and LPS + 0.5% LMCOS. Then, the corresponding reagents (300 μL) were injected into the skull of the mice. To induce bone resorption, LPS was administered at 10 mg/kg per injection. The mice were injected three times a week with PBS alone or LPS without or with LMCOS and sacrificed 2 weeks later. The skull was removed for micro-computed tomography, haematoxylin-eosin staining, and tartrate-resistant acid phosphatase staining. The area of bone damage and osteoclast formation were evaluated and recorded.

Results

LMCOS treatment during LPS-induced skull resorption led to a notable reduction in the area of bone destruction; we observed a dose-dependent decrease in the area of bone destruction and number of osteoclasts with increasing LMCOS concentration.

Conclusions

Our findings showed that LMCOS could inhibit skull bone damage induced by LPS in mice, further research to investigate its therapeutic potential for treating osteolytic diseases is required.

Gene Expression Profiles of Peripheral Blood Monocytes in Osteoarthritis and Analysis of Differentially Expressed Genes

Background

There is little understanding of the molecular processes involved in the pathogenesis of osteoarthritis, limiting early diagnosis and effective treatment of OA. Use of genechips can provide insights into the molecular pathogenesis of diseases. In this study, determination of gene expression profiles of osteoarthritis peripheral blood mononuclear cells will allow exploration of the molecular pathogenesis of OA and find out more candidate biomarkers and potential drug targets of OA.

Result

A total of 1231 DEGs were screened out including 791 upregulated DEGs and 440 downregulated DEGs. The most significant upregulated DEG was RPL38, which may inhibit chondrocyte differentiation and synthesis of the extracellular matrix. PIK3CA, PIK3CB, PIK3CD, PIK3R1, MAPK14, IL1A, JUND, FOSL2, and PPP3CA were the gene symbols of the osteoclast differentiation pathway which was the most significant pathway enriched by DEGs. However, the MAPK signaling pathway occupied the core position of all the pathways which can regulate apoptosis, cell cycle, wnt signaling pathway, p53 signaling pathway, and phosphatidylinositol signaling system. Furthermore, PI3Ks may regulate IL1A, JUND, FOSL2 and PPP3CA through the MAPK signaling pathway.

Conclusion

These identified DEGs and pathways may be novel biomarkers to monitor the changes of OA and can be a potential drug target for the treatment of OA.

Recent Updates in Pharmacological Properties of Chitooligosaccharides

Chemical structures derived from marine foods are highly diverse and pharmacologically promising. In particular, chitooligosaccharides (COS) present a safe pharmacokinetic profile and a great source of new bioactive polymers. This review describes the antioxidant, anti-inflammatory, and antidiabetic properties of COS from recent publications. Thus, COS constitute an effective agent against oxidative stress, cellular damage, and inflammatory pathogenesis. The mechanisms of action and targeted therapeutic pathways of COS are summarized and discussed. COS may act as antioxidants via their radical scavenging activity and by decreasing oxidative stress markers. The mechanism of COS antidiabetic effect is characterized by an acceleration of pancreatic islets proliferation, an increase in insulin secretion and sensitivity, a reduction of postprandial glucose, and an improvement of glucose uptake. COS upregulate the GLUT2 and inhibit digestive enzyme and glucose transporters. Furthermore, they resulted in reduction of gluconeogenesis and promotion of glucose conversion. On the other hand, the COS decrease inflammatory mediators, suppress the activation of NF-κB, increase the phosphorylation of kinase, and stimulate the proliferation of lymphocytes. Overall, this review brings evidence from experimental data about protective effect of COS.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

Modulation of cartilage's response to injury: Can chondrocyte apoptosis be reversed?

Osteoarthritis is characterized by a chronic, progressive and irreversible degradation of the articular cartilage associated with joint inflammation and a reparative bone response. More than 100 million people are affected by this condition worldwide with significant health and welfare costs. Our available treatment options in osteoarthritis are extremely limited. Chondral or osteochondral grafts have shown some promising results but joint replacement surgery is by far the most common therapeutic approach. The difficulty lies on the limited regeneration capacity of the articular cartilage, poor blood supply and the paucity of resident progenitor stem cells. In addition, our poor understanding of the molecular signalling pathways involved in the senescence and apoptosis of chondrocytes is a major factor restricting further progress in the area. This review focuses on molecules and approaches that can be implemented to delay or even rescue chondrocyte apoptosis. Ways of modulating the physiologic response to trauma preventing chondrocyte death are proposed. The use of several cytokines, growth factors and advances made in altering several of the degenerative genetic pathways involved in chondrocyte apoptosis and degradation are also presented. The suggested approaches can help clinicians to improve cartilage tissue regeneration.

Warm sparse-dense wave inhibits cartilage degradation in papain-induced osteoarthritis through the mitogen-activated protein kinase signaling pathway

Cartilage degradation is an important in the pathogenesis of osteoarthritis (OA). Abnormal activation of the mitogen-activated protein kinase (MAPK) signaling pathway in chondrocytes promotes an inflammatory response, resulting in the release of chondral matrix-degrading enzymes that accelerate the degradation of cartilage. As a non-pharmaceutical and non-invasive physical therapy regimen, warm sparse-dense wave (WSDW) has been successfully used for the treatment of OA. However, it remains unclear whether WSDW inhibits cartilage degradation in OA through the MAPK signaling pathway. The present study investigated the effects of WSDW on papain-induced OA in rat knee joints. Papain-induced OA was established in rats, which were subsequently divided into a model group and three experimental groups that received a WSDW with the following ratios: WSDW=1:1, WSDW=1:2 and WSDW=2:1. After 12 weeks of treatment, cartilage degradation was evaluated by Mankin scoring of paraffin-embedded sections stained with hematoxylin and eosin. The changes in cartilage structure were observed by transmission electron microscopy, and the expressions of RAS, extracellular signal-regulated kinase (ERK), p38 and p53 were measured by reverse transcription-quantitative polymerase chain reaction and western blot analysis. WSDW was demonstrated to improve the arrangement of collagen fibers, inhibit the tidemark replication and delay cartilage degradation in papain-induced OA. The expressions of RAS, ERK, p38 and p53 in the WSDW (1:2) and (2:1) groups were significantly decreased when compared with the model group (P<0.01). Furthermore, amongst the WSDW groups, the inhibitory effects of the WSDW (1:2) group were typically greater than those of the WSDW (1:1) and (2:1) groups. The results indicate that WSDW may inhibit cartilage degradation in papain-induced OA in rat knee joints by regulating the MAPK signaling pathway.

Knockdown of TREM-1 suppresses IL-1β-induced chondrocyte injury via inhibiting the NF-κB pathway

Triggering receptor expressed on myeloid cells 1 (TREM-1) is a recently discovered molecule that modulates inflammatory responses. This study aimed to investigate the specific function of TREM-1 in chondrocytes and its association with the pathophysiology of osteoarthritis (OA). We observed upregulation of TREM-1 in OA cartilage compared to normal tissues. Knockdown of TREM-1 suppressed interleukin 1 beta (IL-1β)-induced extracellular matrix (ECM) metabolic imbalance, pro-inflammatory cytokine production, decrease in cell viability and apoptosis. Mechanistic analyses further revealed that IL-1β-induced activation of the NF-κB pathway is suppressed upon TREM-1 knockdown, similar to the effect of pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. TREM-1 expression was consistently increased in a mouse OA model in vivo, and its silencing led to inhibition of matrix metallopeptidase-13 (MMP-13) production, increased collagen type II synthesis and decreased NF-κB signaling. Our data collectively suggest that TREM-1 plays a critical in OA development through regulation of NF-κB signaling. Pharmacological inhibition of TREM-1 may therefore present an effective novel therapeutic approach for OA.