Selective Clearance of Senescent Chondrocytes in Osteoarthritis by Targeting Excitatory Amino Acid Transporter Protein 1 to Induce Ferroptosis

Chronic Kidney Disease and Osteoarthritis: Current Understanding and Future Research Directions

Chronic kidney disease (CKD) is a significant public health concern. Osteoarthritis (OA), a common form of arthritis, has been shown to have a dramatically increased prevalence, particularly among individuals aged 40-50 and older, in the presence of CKD. Furthermore, CKD may exacerbate the progression and impact of OA. A survey study revealed that 53.9% of CKD patients undergoing long-term hemodialysis were diagnosed with OA. These findings underscore the potential association between CKD and OA. Uremic toxins, such as indoxyl sulfate, p-cresyl sulfate, transforming growth factor-β, and advanced glycation end-products, are regarded as potential risk factors in various CKD-related conditions, affecting bone and joint metabolism. However, whether these factors serve as a bridging mechanism between CKD and OA comorbidities, as well as their detailed roles in this context, remains unclear. Addressing the progression of OA in CKD patients and identifying effective treatment and prevention strategies is an urgent challenge that warrants immediate attention. This review focuses on describing and discussing the molecular pathological mechanisms underlying CKD-associated OA and the possible therapeutic strategies.

Clinical and omics biomarkers in osteoarthritis diagnosis and treatment

Osteoarthritis (OA) is a prevalent degenerative joint disease that significantly impacts the quality of life for hundreds of millions, and is a major cause of disability. Despite this, diagnostic and therapeutic options for OA are still limited. With advances in molecular biology, an increasing number of OA biomarkers have been identified, which not only enhances our understanding of OA pathogenesis, but also offers new approaches for OA diagnosis and treatment. This review discussed the research progress on traditional OA biomarkers, and analyzed the application of various omics, including genomics, transcriptomics, proteomics, and metabolomics, in the diagnosis and treatment of OA. Furthermore, we explored how integrating multi-omics methods can reveal interactions among different biomolecules and their roles in the development of OA. This emerging interdisciplinary approach not only provides a more comprehensive understanding of the fundamental biological characteristics of OA, but also aids in identifying new integrated biomarkers, thereby allowing for more accurate predictions of disease progression and treatment responses. The identification and development of biomarkers offer new perspectives in understanding OA, enhancing the specificity and sensitivity of biological diagnostic markers, providing a basis for the design of targeted drugs, and ultimately advancing the development of precision diagnosis and treatment strategies in clinical OA. This study provides an overview of both commonly used and emerging biomarkers of OA which is beneficial for a more accurate, timely, effective clinical diagnosis and treatment for OA.

LncRNA HOXA11-AS intercepts the POU2F2-mediated downregulation of SLC3A2 in osteoarthritis to suppress ferroptosis

BACKGROUND

Osteoarthritis (OA) is a prevalent ailment characterized by the gradual degradation of joints, resulting in discomfort and restricted movement. The recently proposed mechanism of ferroptosis is intricately associated with the initiation and progression of OA. Our study found that the long non-coding RNA HOXA11-AS reduces ferroptosis by increasing the expression of SLC3A2 through the transcription factor POU2F2.

MATERIALS AND METHODS

HOXA11-AS was identified through lncRNA microarray analysis, and its impact on chondrocytes and extracellular matrix was assessed using real-time quantitative PCR, western blotting, and CCK8 assays. Subsequently, overexpression of HOXA11-AS in the knee joints of mice confirmed its protective efficacy on chondrocyte phenotype in the OA model. The involvement of HOXA11-AS in regulating ferroptosis via SLC3A2 was further validated through RNA sequencing analysis of mouse cartilage and the assessment of malondialdehyde levels and glutathione peroxidase activity. Finally, a combination of RNA sequencing, pull-down assays, mass spectrometry (MS), and chromatin immunoprecipitation (ChIP) techniques was employed to identify POU2F2 as the crucial transcription factor responsible for repressing the expression of SLC3A2, which can be effectively inhibited by HOXA11-AS.

RESULTS

Our study demonstrated that HOXA11-AS effectively enhanced the metabolic homeostasis of chondrocytes, and alleviated the progression of OA in vitro and in vivo experiments. Furthermore, HOXA11-AS was found to enhance SLC3A2 expression, a key regulator of ferroptosis, by interacting with the transcriptional repressor POU2F2.

CONCLUSIONS

HOXA11-AS promotes SLC3A2 expression and inhibits chondrocyte ferroptosis, by binding to the transcriptional repressor POU2F2, offering a promising and innovative therapeutic approach for OA.

Ion channel Piezo1 induces ferroptosis of trabecular meshwork cells: a novel observation in the pathogenesis in primary open angle glaucoma

This study aims to elucidate the role of Piezo1, a mechanosensitive molecule, in trabecular meshwork cells (TMCs) in the context of primary open angle glaucoma (POAG), a leading cause of irreversible visual impairment. Dysfunction of the trabecular meshwork (TM) is a key factor in the elevated intraocular pressure (IOP) observed in POAG, yet the specific mechanisms leading to TM dysfunction are not fully understood. We performed cell stretching on human trabecular meshwork cells (HTMCs) and pharmacologically activated HTMCs with Yoda1 to study the role of Piezo1 in HTMCs. We focused on assessing cell viability, mitochondrial changes, lipid peroxidation, and the expression of ferroptosis-related targets such as acyl-CoA synthetase long-chain family member 4 (ACSL4) and glutathione peroxidase 4 (GPX4). Cell stretching induces ferroptosis in HTMCs, and this phenomenon is reversed by Piezo1 knockdown. In addition, pharmacological activation of Piezo1 also leads to ferroptosis in HTMCs. Furthermore, inhibiting the JNK/p38 signaling pathway was found to mitigate the ferroptotic response induced by Yoda1, thereby confirming that Piezo1 induces ferroptosis in TMCs through this pathway. Notably, our experiments suggest that Yoda1 may trigger ferroptosis in the TM of mouse eyes. Our findings demonstrate that the Piezo1 pathway is a crucial mediator of ferroptosis in TMCs, providing new insights into the pathogenic mechanisms of glaucoma, particularly POAG. This study highlights the potential of targeting the Piezo1 pathway as a therapeutic approach for mitigating TM dysfunction and managing POAG.NEW & NOTEWORTHY This study is the first to show that cell stretching induces ferroptosis in trabecular meshwork cells (TMCs), dependent on Piezo1 activation. Targeting the Piezo1 pathway offers new therapeutic potential for mitigating trabecular meshwork dysfunction and managing primary open angle glaucoma (POAG). The study also reveals Piezo1 induces ferroptosis via the JNK/p38 signaling pathway.

Ferroptosis in Osteoarthritis: Current Understanding

Osteoarthritis (OA) is a prevalent degenerative disease in elderly people that is characterized by cartilage loss and abrasion, leading to joint pain and dysfunction. The aetiology of OA is complicated and includes abnormal mechanical stress, a mild inflammatory environment, chondrocyte senescence and apoptosis, and changes in chondrocyte metabolism. Ferroptosis is a regulated cell death modality characterized by the excessive accumulation of lipid peroxidation and mitochondrial dysfunction. The role of ferroptosis in OA pathogenesis has aroused researchers' attention in the past two years, and there is mounting evidence indicating that ferroptosis is destructive. However, the impact of ferroptosis on OA and how the regulators of ferroptosis affect OA development are unclear. Here, we reviewed the current understanding of ferroptosis in OA pathogenesis and summarized several drugs and compounds targeting ferroptosis in OA treatment. The accumulation of intracellular iron, the trigger of Fenton reaction, the excessive production of ROS, the peroxidation of PUFA-PLs, and mitochondrial and membrane damage are involved in chondrocyte ferroptosis. System Xc - and GPX4 are the most important regulators that control ferroptosis. Several compounds, such as DFO and Fer-1, have been proven effective in preventing ferroptosis and slowing OA progression on animal models. Collectively, targeting ferroptosis shows great potential in treating OA.

Iron homeostasis and ferroptosis in human diseases: mechanisms and therapeutic prospects

Iron, an essential mineral in the body, is involved in numerous physiological processes, making the maintenance of iron homeostasis crucial for overall health. Both iron overload and deficiency can cause various disorders and human diseases. Ferroptosis, a form of cell death dependent on iron, is characterized by the extensive peroxidation of lipids. Unlike other kinds of classical unprogrammed cell death, ferroptosis is primarily linked to disruptions in iron metabolism, lipid peroxidation, and antioxidant system imbalance. Ferroptosis is regulated through transcription, translation, and post-translational modifications, which affect cellular sensitivity to ferroptosis. Over the past decade or so, numerous diseases have been linked to ferroptosis as part of their etiology, including cancers, metabolic disorders, autoimmune diseases, central nervous system diseases, cardiovascular diseases, and musculoskeletal diseases. Ferroptosis-related proteins have become attractive targets for many major human diseases that are currently incurable, and some ferroptosis regulators have shown therapeutic effects in clinical trials although further validation of their clinical potential is needed. Therefore, in-depth analysis of ferroptosis and its potential molecular mechanisms in human diseases may offer additional strategies for clinical prevention and treatment. In this review, we discuss the physiological significance of iron homeostasis in the body, the potential contribution of ferroptosis to the etiology and development of human diseases, along with the evidence supporting targeting ferroptosis as a therapeutic approach. Importantly, we evaluate recent potential therapeutic targets and promising interventions, providing guidance for future targeted treatment therapies against human diseases.

Mechanisms of chondrocyte cell death in osteoarthritis: implications for disease progression and treatment

Osteoarthritis (OA) is a chronic joint disease characterized by the degeneration, destruction, and excessive ossification of articular cartilage. The prevalence of OA is rising annually, concomitant with the aging global population and increasing rates of obesity. This condition imposes a substantial and escalating burden on individual health, healthcare systems, and broader social and economic frameworks. The etiology of OA is multifaceted and not fully understood. Current research suggests that the death of chondrocytes, encompassing mechanisms such as cellular apoptosis, pyroptosis, autophagy, ferroptosis and cuproptosis, contributes to both the initiation and progression of the disease. These cell death pathways not only diminish the population of chondrocytes but also exacerbate joint damage through the induction of inflammation and other deleterious processes. This paper delineates the morphological characteristics associated with various modes of cell death and summarizes current research results on the molecular mechanisms of different cell death patterns in OA. The objective is to review the advancements in understanding chondrocyte cell death in OA, thereby offering novel insights for potential clinical interventions.

Iron metabolism and arthritis: Exploring connections and therapeutic avenues

ABSTRACT

Iron is indispensable for the viablility of nearly all living organisms, and it is imperative for cells, tissues, and organisms to acquire this essential metal sufficiently and maintain its metabolic stability for survival. Disruption of iron homeostasis can lead to the development of various diseases. There is a robust connection between iron metabolism and infection, immunity, inflammation, and aging, suggesting that disorders in iron metabolism may contribute to the pathogenesis of arthritis. Numerous studies have focused on the significant role of iron metabolism in the development of arthritis and its potential for targeted drug therapy. Targeting iron metabolism offers a promising approach for individualized treatment of arthritis. Therefore, this review aimed to investigate the mechanisms by which the body maintains iron metabolism and the impacts of iron and iron metabolism disorders on arthritis. Furthermore, this review aimed to identify potential therapeutic targets and active substances related to iron metabolism, which could provide promising research directions in this field.

siRNA therapy in osteoarthritis: targeting cellular pathways for advanced treatment approaches

Osteoarthritis (OA) is a common joint disorder characterized by the degeneration of cartilage and inflammation, affecting millions worldwide. The disease's complex pathogenesis involves various cell types, such as chondrocytes, synovial cells, osteoblasts, and immune cells, contributing to the intricate interplay of factors leading to tissue degradation and pain. RNA interference (RNAi) therapy, particularly through the use of small interfering RNA (siRNA), emerges as a promising avenue for OA treatment due to its capacity for specific gene silencing. siRNA molecules can modulate post-transcriptional gene expression, targeting key pathways involved in cellular proliferation, apoptosis, senescence, autophagy, biomolecule secretion, inflammation, and bone remodeling. This review delves into the mechanisms by which siRNA targets various cell populations within the OA milieu, offering a comprehensive overview of the potential therapeutic benefits and challenges in clinical application. By summarizing the current advancements in siRNA delivery systems and therapeutic targets, we provide a solid theoretical foundation for the future development of novel siRNA-based strategies for OA diagnosis and treatment, paving the way for innovative and more effective approaches to managing this debilitating disease.

Advancing skeletal health and disease research with single-cell RNA sequencing

Orthopedic conditions have emerged as global health concerns, impacting approximately 1.7 billion individuals worldwide. However, the limited understanding of the underlying pathological processes at the cellular and molecular level has hindered the development of comprehensive treatment options for these disorders. The advent of single-cell RNA sequencing (scRNA-seq) technology has revolutionized biomedical research by enabling detailed examination of cellular and molecular diversity. Nevertheless, investigating mechanisms at the single-cell level in highly mineralized skeletal tissue poses technical challenges. In this comprehensive review, we present a streamlined approach to obtaining high-quality single cells from skeletal tissue and provide an overview of existing scRNA-seq technologies employed in skeletal studies along with practical bioinformatic analysis pipelines. By utilizing these methodologies, crucial insights into the developmental dynamics, maintenance of homeostasis, and pathological processes involved in spine, joint, bone, muscle, and tendon disorders have been uncovered. Specifically focusing on the joint diseases of degenerative disc disease, osteoarthritis, and rheumatoid arthritis using scRNA-seq has provided novel insights and a more nuanced comprehension. These findings have paved the way for discovering novel therapeutic targets that offer potential benefits to patients suffering from diverse skeletal disorders.

In Situ Remodeling of Efferocytosis via Lesion-Localized Microspheres to Reverse Cartilage Senescence

Efferocytosis, an intrinsic regulatory mechanism to eliminate apoptotic cells, will be suppressed due to the delayed apoptosis process in aging-related diseases, such as osteoarthritis (OA). In this study, cartilage lesion-localized hydrogel microspheres are developed to remodel the in situ efferocytosis to reverse cartilage senescence and recruit endogenous stem cells to accelerate cartilage repair. Specifically, aldehyde- and methacrylic anhydride (MA)-modified hyaluronic acid hydrogel microspheres (AHM), loaded with pro-apoptotic liposomes (liposomes encapsulating ABT263, A-Lipo) and PDGF-BB, namely A-Lipo/PAHM, are prepared by microfluidic and photo-cross-linking techniques. By a degraded porcine cartilage explant OA model, the in situ cartilage lesion location experiment illustrated that aldehyde-functionalized microspheres promote affinity for degraded cartilage. In vitro data showed that A-Lipo induced apoptosis of senescent chondrocytes (Sn-chondrocytes), which can then be phagocytosed by the efferocytosis of macrophages, and remodeling efferocytosis facilitated the protection of normal chondrocytes and maintained the chondrogenic differentiation capacity of MSCs. In vivo experiments confirmed that hydrogel microspheres localized to cartilage lesion reversed cartilage senescence and promoted cartilage repair in OA. It is believed this in situ efferocytosis remodeling strategy can be of great significance for tissue regeneration in aging-related diseases.

Ferroptosis resistance in cancer: recent advances and future perspectives

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death and has been implicated in the occurrence and development of various diseases, including heart disease, nervous system diseases and cancer. Ferroptosis induction recently emerged as an attractive strategy for cancer therapy. Ferroptosis has become a potential target for intervention in these diseases or injuries in relevant preclinical models. This review summarizes recent progress on the mechanisms of ferroptosis resistance in cancer, highlights redox status and metabolism's role in it. Combination therapy for ferroptosis has great potential in cancer treatment, especially malignant tumors that are resistant to conventional therapies. This review will lead us to have a comprehensive understanding of the future exploration of ferroptosis and cancer therapy. A deeper understanding of the relationship between ferroptosis resistance and metabolism reprogramming may provide new strategies for tumor treatment and drug development based on ferroptosis.

Targeting regulated chondrocyte death in osteoarthritis therapy

In vivo articular cartilage degeneration is an essential hallmark of osteoarthritis (OA), involving chondrocyte senescence, extracellular matrix degradation, chondrocyte death, cartilage loss, and bone erosion. Among them, chondrocyte death is one of the major factors leading to cartilage degeneration. Many studies have reported that various cell death modes, including apoptosis, ferroptosis, and autophagy, play a key role in OA chondrocyte death. Currently, there is insufficient understanding of OA pathogenesis, and there remains a lack of treatment methods to prevent OA and inhibit its progression. Studies suggest that OA prevention and treatment are mainly directed to arrest premature or excessive chondrocyte death. In this review, we a) discuss the forms of death of chondrocytes and the associations between them, b) summarize the critical factors in chondrocyte death, c) discuss the vital role of chondrocyte death in OA, d) and, explore new approaches for targeting the regulation of chondrocyte death in OA treatment.

Crosstalk between ferroptosis and chondrocytes in osteoarthritis: a systematic review of in vivo and in vitro studies

Purpose

Recent scientific reports have revealed a close association between ferroptosis and the occurrence and development of osteoarthritis (OA). Nevertheless, the precise mechanisms by which ferroptosis influences OA and how to hobble OA progression by inhibiting chondrocyte ferroptosis have not yet been fully elucidated. This study aims to conduct a comprehensive systematic review (SR) to address these gaps.

Methods

Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020, we conducted a comprehensive search of the Embase, Ovid, ProQuest, PubMed, Scopus, the Cochrane Library, and Web of Science databases to identify relevant studies that investigate the association between ferroptosis and chondrocytes in OA. Our search included studies published from the inception of these databases until January 31st, 2023. Only studies that met the predetermined quality criteria were included in this SR.

Results

In this comprehensive SR, a total of 21 studies that met the specified criteria were considered suitable and included in the current updated synthesis. The mechanisms underlying chondrocyte ferroptosis and its association with OA progression involve various biological phenomena, including mitochondrial dysfunction, dysregulated iron metabolism, oxidative stress, and crucial signaling pathways.

Conclusion

Ferroptosis in chondrocytes has opened an entirely new chapter for the investigation of OA, and targeted regulation of it is springing up as an attractive and promising therapeutic tactic for OA.

Systematic review registration

https://inplasy.com/inplasy-2023-3-0044/, identifier INPLASY202330044.