Interleukin 1 suppresses expression of cartilage-specific types II and IX collagens and increases types I and III collagens in human chondrocytes

Association of neurodegeneration, cognitive impairment, and short stature in Down syndrome; Could proinflammatory cytokines be the common factor?

Down syndrome (DS), caused by an extra copy of chromosome 21, is the most prevalent chromosomal disorder. It leads to various complications including, cardiac and endocrine dysfunctions, impairment of the immune system, growth retardation, and certain neurological conditions. Stunted growth in this population might be linked to an increased risk of a variety of co-occurring conditions, particularly neurological disorders. Studies indicate that the levels of neurodegeneration and neuroinflammation markers are higher in shorter children with DS. The disruption of insulin-like growth factor 1 (IGF1) signalling pathway due to the overexpression of proinflammatory cytokine genes could help establish a connection between short stature and neurodegeneration in DS. These cytokines disrupt the production of IGF1 in the liver, thereby inhibiting IGF1 from promoting bone and brain growth. Additionally, elevated cytokines levels impair the production of sex hormones by affecting the gonadal axis, further exacerbating the aforementioned conditions. The group of GnRH neurons responsible for cognitive functions is also impaired in DS, and treatment with GnRH agonists has demonstrated improvements in cognition. Although GnRH agonists can delay the fusion of growth plates by inhibiting pulsatile GnRH secretion, they may also lead to cognitive impairments. Hypothyroidism, the most prevalent endocrine complication of DS, can also contribute to both cognitive impairment and short stature. In conclusion, the increase of proinflammatory cytokines, through various mechanisms, can play a significant role in the development of both cognitive impairments and short stature in DS.

Irisin in the modulation of bone and cartilage homeostasis: a review on osteoarthritis relief potential

Osteoarthritis, a progressive and degenerative joint disease, disrupts the integrity of the entire joint structure, underscoring the urgency of identifying more effective therapeutic strategies and innovative targets. Among these, exercise therapy is considered a key component in the early management of osteoarthritis, functioning by stimulating the secretion of myokines from the skeletal muscle system. Irisin, a myokine predominantly secreted by skeletal muscle during exercise and encoded by the FNDC5 gene, has garnered attention for its regulatory effects on bone health. Emerging evidence suggests that irisin may play a protective role in osteoarthritis by promoting tissue homeostasis, enhancing subchondral bone density and microstructure, and inhibiting chondrocyte apoptosis. By improving chondrocyte viability, preserving extracellular matrix integrity, and maintaining homeostasis in osteoblasts, osteoclasts, and osteocytes, irisin emerges as a promising therapeutic target for osteoarthritis. This review delves into the role of irisin in osteoarthritis pathogenesis, highlighting its influence on cartilage and bone metabolism as well as its dynamic relationship with exercise. Additionally, this review suggests that further exploration on its specific molecular mechanisms, optimization of drug delivery systems, and strategic utilization of exercise-induced benefits will be pivotal in unlocking the full potential of irisin as a novel intervention for osteoarthritis.

Intra-articular injection of inorganic pyrophosphate improves IL-1β-induced cartilage damage in rat model of knee osteoarthritis in vivo

Objective

Osteoarthritis (OA) is the most common form of chronic joint disease, affecting mainly the elderly population. This disorder is caused by cartilage degeneration with complex changes in the chondrocyte phenotype. Inorganic pyrophosphate (PPi) was shown to counteract the detrimental effect of interleukin (IL)-1β challenging in an in vitro OA model based on rat articular chondrocytes. It also maintained the differentiated articular phenotype, mostly by down regulating wingless-related integration site (Wnt)-5a secretion. These observations suggest a PPi protective role for chondrocyte in vitro.

Methods

To address this hypothesis in vivo, we investigated the impact on knee joint of three intra-articular injection (IAI) of PPi in a rat model of cartilage damage induced by IAI of IL-1β, where cartilage degradation and synovial inflammation are similar to that observed in OA. Cartilage and synovial membrane were collected after 7 days of challenge by IL-1β.

Results

PPi was able to reduce the deleterious effect of IL-1β. This effect was observable on the expression of cartilage extracellular matrix metabolism markers and confirmed by histology with safranin O and hematoxylin-eosin-saffron (HES) staining. Inorganic pyrophosphate also repressed the Wnt5a expression induced by IL-1β. No effect was observed on the inflammatory response of the synovial membrane.

Conclusion

These results demonstrate that PPi improves IL-1β-induced cartilage damage in rat but not the associated inflammation of synovial membrane. Thus, PPi could become a molecule of interest to restrict the progression of this disorder.

A programmable arthritis-specific receptor for guided articular cartilage regenerative medicine

OBJECTIVE

Investigational cell therapies have been developed as disease-modifying agents for the treatment of osteoarthritis (OA), including those that inducibly respond to inflammatory factors driving OA progression. However, dysregulated inflammatory cascades do not specifically signify the presence of OA. Here, we deploy a synthetic receptor platform that regulates cell behaviors in an arthritis-specific fashion to confine transgene expression to sites of cartilage degeneration.

DESIGN

A single-chain variable fragment specific for type II collagen (CII) that is exposed in damaged cartilage was used to produce a synthetic Notch (synNotch) receptor that enables "CII-synNotch" mesenchymal stromal cells (MSCs) to recognize degraded cartilage. Artificial signaling induced by both CII-treated culture surfaces and primary tissues was measured via fluorescence and luminescence assays. Separate studies measured the ability of CII-synNotch to govern cartilage anabolic activity of MSCs. Finally, a co-culture with ATDC5 chondrocytes was used to determine whether CII-synNotch MSCs can protect chondrocytes against deleterious effects of pro-inflammatory interleukin-1 in a CII-dependent manner.

RESULTS

CII-synNotch MSCs are highly and selectively responsive to CII, but not type I collagen, as measured by luminescence assays, fluorescence microscopy, and concentrations of secreted transgene products in culture media. CII-synNotch cells exhibit the capacity to distinguish between healthy and damaged cartilage tissue and constrain transgene expression to regions of exposed CII fibers. Receptor-regulated production of cartilage anabolic and anti-inflammatory transgenes was effective to mediate cartilage regenerative functions.

CONCLUSION

This work demonstrates proof-of-concept that the synNotch platform guides MSCs for spatially regulated, disease-dependent delivery of OA-relevant biologic drugs.

Isoliensinine suppresses chondrocytes pyroptosis against osteoarthritis via the MAPK/NF-κB signaling pathway

BACKGROUND

Isoliensinine is an active compound derived from Nelumbo nucifera which has long been used for its anti-inflammatory properties. However, the mechanism of Isoliensinine in the treatment of osteoarthritis is poorly known.

PURPOSE

The present study aims to investigate whether Isoliensinine could alleviate osteoarthritis by regulating MAPK/NF-κB signaling pathway-mediated pyroptosis.

METHODS

Network pharmacology and KEGG enrichment analysis were used to identify the therapeutic targets of Isoliensinine for OA. Molecular docking was used to confirm the binding ability of Isoliensinine and related proteins. In vitro, chondrocytes were stimulated with IL-1β to construct an inflammatory model and treated with Isoliensinine. The viability of the cells was assessed using the CCK-8 kit. The apoptosis rate of cells was measured using Annexin V-FITC/PI assay. And assessed the levels of ROS, lipid-ROS, and mitochondrial membrane potential. Corresponding assay kits were utilized to measure the levels of MDA and SOD. Subsequently, the anabolic and catabolic markers in chondrocytes, alongside inflammatory targets were measured by RT-PCR and Western blot. The expression level of pyroptosis and MAPK/NF-κB signaling pathway-related targets was examined. Furthermore, we constructed a rat osteoarthritis model using ACLT surgery. We then assessed the progression of osteoarthritis by Micro-CT, H&E staining, S&F staining and immunohistochemistry.

RESULTS

Enrichment analysis showed that Isoliensinine treatment of osteoarthritis may be through the MAPK/NF-κB pathway, and molecular docking showed that Isoliensinine and MAPK/NF-κB pathway proteins had a good binding ability. Data showed that Isoliensinine could reduce ECM degradation and inflammation, and inhibit IL-1β-induced apoptosis. It also mitigated ROS and LPO activation, regulated mitochondrial dysfunction, and reduced intracellular oxidative stress levels. Furthermore, Western blot showed that Isoliensinine also inhibited the activation of the MAPK/NF-κB pathway, thereby inhibiting the pyroptosis of chondrocytes. In vivo, Micro-CT, H&E staining and S&F staining results showed that Isoliensinine could effectively improve joint damage caused by osteoarthritis. And IHC analyses indicated NLRP3, MMP3 protein expression were significantly diminished and Collagen II expression was increased in the Isoliensinine treatment groups.

CONCLUSION

In conclusion, our study suggested that Isoliensinine mitigates ECM degradation, oxidative stress, chondrocytes apoptosis, and pyroptosis through the inhibition of the MAPK and NF-κB pathways, thereby delaying the progression of osteoarthritis.

Control of articular degeneration by extracellular vesicles from stem/stromal cells as a potential strategy for the treatment of osteoarthritis

Osteoarthritis (OA) is a degenerative joint condition that contributes to years lived with disability. Current therapeutic approaches are limited as there are no disease-modifying interventions able to delay or inhibit the progression of disease. In recent years there has been an increasing interest in the immunomodulatory and regenerative properties of mesenchymal stem/stromal cells (MSCs) to develop new OA therapies. Extracellular vesicles (EVs) mediate many of the biological effects of these cells and may represent an alternative avoiding the limitations of cell-based therapy. There is also a growing interest in EV modifications to enhance their efficacy and applications. Recent preclinical studies have provided strong evidence supporting the potential of MSC EVs for the development of OA treatments. Thus, MSC EVs may regulate chondrocyte functions to avoid cartilage destruction, inhibit abnormal subchondral bone metabolism and synovial tissue alterations, and control pain behavior. EV actions may be mediated by the transfer of their cargo to target cells, with an important role for proteins and non-coding RNAs modulating signaling pathways relevant for OA progression. Nevertheless, additional investigations are needed concerning EV optimization, and standardization of preparation procedures. More research is also required for a better knowledge of possible effects on different OA phenotypes, pharmacokinetics, mechanism of action, long-term effects and safety profile. Furthermore, MSC EVs have a high potential as vehicles for drug delivery or as adjuvant therapy to potentiate or complement the effects of other approaches.

Effect of Passaging on Bovine Chondrocyte Gene Expression and Engineered Cartilage Production

Tissue engineering strategies show great potential for repairing osteochondral defects in osteoarthritic joints; however, these approaches often rely on passaging cells multiple times to obtain enough cells to produce functional tissue. Unfortunately, monolayer expansion culture causes chondrocyte dedifferentiation, which is accompanied by a phenotypical and morphological shift in chondrocyte properties that leads to a reduction in the quality of de novo cartilage produced. Thus, the objective of this study was to evaluate transcriptional variations during in vitro expansion culture and determine how differences in cell phenotype from monolayer expansion alter development of functional engineered cartilage. We used an unbiased approach to explore genome-wide transcriptional differences in chondrocyte phenotype at passage 1 (P1), P3, and P5, and then seeded cells into hydrogel scaffolds at P3 and P5 to assess cells' abilities to produce cartilaginous extracellular matrix in three dimensional (3D). We identified distinct phenotypic differences, specifically for genes related to extracellular organization and cartilage development. Both P3 and P5 chondrocytes were able to produce chondrogenic tissue in 3D, with P3 cells producing matrix with greater compressive properties and P5 cells secreting matrix with higher glycosaminoglycan/DNA and collagen/DNA ratios. Furthermore, we identified 24 genes that were differentially expressed with passaging and enriched in human osteoarthritis (OA) genome-wide association studies, thereby prioritizing them as functionally relevant targets to improve protocols that recapitulate functional healthy cartilage with cells from adult donors. Specifically, we identified novel genes, such as TMEM190 and RAB11FIP4, which were enriched with human hip OA and may play a role in chondrocyte dedifferentiation. This work lays the foundation for several pathways and genes that could be modulated to enhance the efficacy for chondrocyte culture for tissue regeneration, which could have transformative impacts for cell-based cartilage repair strategies.

Biomarkers for hypertrophic chondrocyte differentiation are associated with spatial cellular organisation and suggest endochondral ossification-like processes in osteoarthritic cartilage: An exploratory study

Background

In healthy articular cartilage, chondrocytes are found along arcades of collagen fibers as Single Strings. With onset of cartilage degeneration this pattern changes to Double Strings. In the course of osteoarthritis Small Clusters, and finally Big Clusters form. In highly degenerated articular cartilage, another poorly understood pattern is found where chondrocyte morphology differs considerably, and the distribution of cells is diffuse. Progression of osteoarthritis is accompanied by key processes such as chondrocyte proliferation, apoptosis, hypertrophic differentiation, inflammation, and angiogenesis. The aim of this exploratory study was to identify biomarkers for these processes in the context of spatial cellular organizational changes in articular cartilage.

Methods

Cartilage explants (n = 166 patients) were sorted according to their predominant cellular pattern. Quantitative or semi-quantitative analysis of 39 biomarkers were performed by multiplex assay (31) or ELISA (8), and qualitative analysis on 12 immunohistochemical markers.

Results

Hypertrophic differentiation (e.g. type-X collagen, osteopontin, osteocalcin and interleukin-6) and angiogenesis were associated with changes in chondrocyte organisation. First changes take place already at the transition from Single Strings to Double Strings. Drastic changes in the appearance of numerous biomarkers are found at the transition from Big Clusters to Diffuse.

Conclusion

Key processes in osteoarthritis and their biomarkers seem to depend on the spatial distribution of chondrocytes in articular cartilage. Abrupt changes in biomarker occurrence were observed between Big Clusters and Diffuse insinuating that the Diffuse pattern is composed of a different cell population or at least a different form of chondrocyte morphology.

The Translational Potential of this Article

In situ identification of the different spatial chondrocyte patterns by fluorescence microscopy has already been established in the recent past. Analysing human in-situ cartilage explants rather than isolated OA chondrocytes closes the gap between in vitro and in vivo studies and as such, stretches a big step towards translation of the observed findings. The direct association between tissue biomarker profile and cellular arrangements representing different states of OA sheds new light on the molecular and cellular physiopathology, especially in the context of larger processes such as angiogenesis, cellular proliferation, differentiation, and apoptosis. This also opens an interesting perspective for future investigation of such biomarkers and processes in clinical studies.

Basement membrane extract potentiates the endochondral ossification phenotype of bone marrow-derived mesenchymal stem cell-based cartilage organoids

Endochondral ossification is a developmental process in the skeletal system and bone marrow of vertebrates. During endochondral ossification, primitive cartilaginous anlages derived from mesenchymal stem cells (MSCs) undergo vascular invasion and ossification. In vitro regeneration of endochondral ossification is beneficial for research on the skeletal system and bone marrow development as well as their clinical aspects. However, to achieve the regeneration of endochondral ossification, a stem cell-based artificial cartilage (cartilage organoid, Cart-Org) that possesses an endochondral ossification phenotype is required. Here, we modified a conventional 3D culture method to create stem cell-based Cart-Org by mixing it with a basement membrane extract (BME) and further characterized its chondrogenic and ossification properties. BME enlarged and matured the bone marrow MSC-based Cart-Orgs without any shape abnormalities. Histological analysis using Alcian blue staining showed that the production of cartilaginous extracellular matrices was enhanced in Cart-Org treated with BME. Transcriptome analysis using RNA sequencing revealed that BME altered the gene expression pattern of Cart-Org to a dominant chondrogenic state. BME triggered the activation of the SMAD pathway and inhibition of the NK-κB pathway, which resulted in the upregulation of SOX9, COL2A1, and ACAN in Cart-Org. BME also facilitated the upregulation of genes associated with hypertrophic chondrocytes (IHH, PTH1R, and COL10A1) and ossification (SP7, ALPL, and MMP13). Our findings indicate that BME promotes cartilaginous maturation and further ossification of bone marrow MSC-based Cart-Org, suggesting that Cart-Org treated with BME possesses the phenotype of endochondral ossification.

A programmable arthritis-specific receptor for guided articular cartilage regenerative medicine

Objective

Investigational cell therapies have been developed as disease-modifying agents for the treatment of osteoarthritis (OA), including those that inducibly respond to inflammatory factors driving OA progression. However, dysregulated inflammatory cascades do not specifically signify the presence of OA. Here, we deploy a synthetic receptor platform that regulates cell behaviors in an arthritis-specific fashion to confine transgene expression to sites characterized by cartilage degeneration.

Methods

An scFv specific for type II collagen (CII) was used to produce a synthetic Notch (synNotch) receptor that enables "CII-synNotch" mesenchymal stromal cells (MSCs) to recognize CII fibers exposed in damaged cartilage. Engineered cell activation by both CII-treated culture surfaces and on primary tissue samples was measured via inducible reporter transgene expression. TGFβ3-expressing cells were assessed for cartilage anabolic gene expression via qRT-PCR. In a co-culture with CII-synNotch MSCs engineered to express IL-1Ra, ATDC5 chondrocytes were stimulated with IL-1α, and inflammatory responses of ATDC5s were profiled via qRT-PCR and an NF-κB reporter assay.

Results

CII-synNotch MSCs are highly responsive to CII, displaying activation ranges over 40-fold in response to physiologic CII inputs. CII-synNotch cells exhibit the capacity to distinguish between healthy and damaged cartilage tissue and constrain transgene expression to regions of exposed CII fibers. Receptor-regulated TGFβ3 expression resulted in upregulation of Acan and Col2a1 in MSCs, and inducible IL-1Ra expression by engineered CII-synNotch MSCs reduced pro-inflammatory gene expression in chondrocytes.

Conclusion

This work demonstrates proof-of-concept that the synNotch platform guides MSCs for spatially regulated, disease-dependent delivery of OA-relevant biologic drugs.

Fundamentals of osteoarthritis: Inflammatory mediators in osteoarthritis

OBJECTIVES

As more has become known of the pathophysiology of osteoarthritis (OA), evidence that inflammation plays a critical role in its development and progression has accumulated. Here, we aim to review current knowledge of the complex inflammatory network in the OA joint.

DESIGN

This narrative review is presented in three main sections: local inflammation, systemic inflammation, and therapeutic implications. We focused on inflammatory mediators and their link to OA structural changes in the joint.

RESULTS

OA is characterized by chronic and low-grade inflammation mediated mostly by the innate immune system, which results in cartilage degradation, bone remodeling and synovial changes. Synovitis is regarded as an OA characteristic and associated with increased severity of symptoms and joint dysfunction. However, the articular cartilage and the subchondral bone also produce several pro-inflammatory mediators thus establishing a complex interplay between the different tissues of the joint. In addition, systemic low-grade inflammation induced by aging, obesity and metabolic syndrome can contribute to OA development and progression. The main inflammatory mediators associated with OA include cytokines, chemokines, growth factors, adipokines, and neuropeptides.

CONCLUSIONS

Future research is needed to deeper understand the molecular pathways mediating the inflammation in OA to provide new therapeutics that target these pathways, or to repurpose existing drugs.

Betulinic Acid Attenuates Osteoarthritis via Limiting NLRP3 Inflammasome Activation to Decrease Interleukin-1β Maturation and Secretion

Introduction

Osteoarthritis (OA) is the most common degenerative joint disorder. Prior studies revealed that activation of NLRP3 inflammasome could promote the activation and secretion of interleukin-1β (IL-1β), which has an adverse effect on the progression of OA. Betulinic acid (BA) is a compound extract of birch, whether it can protect against OA and the mechanisms involved are still unknown.

Materials and Methods

In vivo experiments, using gait analysis, ELISA, micro-CT, and scanning electron microscopy (SEM), histological staining, immunohistological (IHC) and immunofluorescence (IF) staining, and atomic force microscopy (AFM) to assess OA progression after intraperitoneal injection of 5 and 15 mg/kg BA in an OA mouse model. In vitro experiments, caspase-1, IL-1β, and the N-terminal fragment of gasdermin D (GSDMD-NT) were measured in bone marrow-derived macrophages (BMDMs) by using ELISA, western blot, and immunofluorescence staining.

Results

We demonstrated that OA progression can be postponed with intraperitoneal injection of 5 and 15 mg/kg BA in an OA mouse model. Specifically, BA postponed DMM-induced cartilage deterioration, alleviated subchondral bone sclerosis, and relieved synovial inflammation. In vitro studies, the activated NLRP3 inflammasome produces mature IL-1β by facilitating the cleavage of pro-IL-1β, and BA could inhibit the activation of NLRP3 inflammasome in BMDMs.

Conclusions

Taken together, our analyses revealed that BA attenuates OA via limiting NLRP3 inflammasome activation to decrease the IL-1β maturation and secretion.

Stevioside targets the NF-κB and MAPK pathways for inhibiting inflammation and apoptosis of chondrocytes and ameliorates osteoarthritis in vivo

Osteoarthritis (OA) is a joint disease that is characterized by articular cartilage degeneration and destruction. Stevioside (SVS) is a diterpenoid glycoside extracted from Stevia rebaudiana Bertoni with some specific effects against inflammatory and apoptotic, whereas it is still unclear what function SVS has in osteoarthritis. This study focuses on the anti-inflammatory and anti-apoptosis functions of SVS on chondrocytes induced by interleukin (IL)-1beta, and the role of SVS in an osteoarthritis model for mice. We can detect the production of inflammatory factors such as nitric oxide (NO) and prostaglandin E2 (PGE2) using real-time quantitative polymerase chain reaction (RT-qPCR), the Griess reaction, and enzyme linked immunosorbent assay (ELISA). On the basis of Western blot, we have observed the protein expressions of cartilage matrix metabolism, inflammatory factors, and apoptosis of chondrocytes. Simultaneously, the pharmacological effects of SVS in mice were evaluated by hematoxylin and eosin (HE), toluidine blue, Safranin O, and immunohistochemical staining. The results show that SVS slows extracellular matrix degradation and chondrocyte apoptosis. In addition, SVS mediates its cellular effect by inhibiting the activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. Meanwhile, molecular docking studies revealed that SVS has excellent binding capabilities to p65, extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). The study suggests that SVS can be developed as a potential osteoarthritis treatment.

Silencing miR-146a-5p Protects against Injury-Induced Osteoarthritis in Mice

Osteoarthritis (OA), the most prevalent joint disease and the leading cause of disability, remains an incurable disease largely because the etiology and pathogenesis underlying this degenerative process are poorly understood. Low-grade inflammation within joints is a well-established factor that disturbs joint homeostasis and leads to an imbalance between anabolic and catabolic processes in articular cartilage; however, the complexity of the network between inflammatory factors that often involves positive and negative feedback loops makes current anti-cytokine therapy ineffective. MicroRNAs (miRNAs) have emerged as key regulators to control inflammation, and aberrant miRNAs expression has recently been linked to OA pathophysiology. In the present study, we characterized transcriptomic profiles of miRNAs in primary murine articular chondrocytes in response to a proinflammatory cytokine, IL-1β, and identified miR-146a-5p as the most responsive miRNA to IL-1β. miR-146a-5p was also found to be upregulated in human OA cartilage. We further demonstrated that knockdown of miR-146a-5p antagonized IL-1β-mediated inflammatory responses and IL-1β-induced catabolism in vitro, and silencing of miR-146a in chondrocytes ameliorated articular cartilage destruction and reduced OA-evoked pain in an injury-induced murine OA model. Moreover, parallel RNA sequencing revealed that differentially expressed genes in response to IL-1β were enriched in pathways related to inflammatory processes, cartilage matrix homeostasis, and cell metabolism. Bioinformatic analyses of putative miR-146a-5p gene targets and following prediction of protein-protein interactions suggest a functional role of miR-146a-5p in mediating inflammatory processes and regulation of cartilage homeostasis. Our genetic and transcriptomic data define a crucial role of miR-146a-5p in OA pathogenesis and implicate modulation of miR-146a-5p in articular chondrocytes as a potential therapeutic strategy to alleviate OA.

Recent advances in the pharmacotherapy of osteoarthritis

Introduction: Osteoarthritis (OA) is a common debilitating disease affecting the geriatric population. Management of osteoarthritis is a challenge for orthopedicians because till date there has been no such drug that can completely cure the disease or at least retard/arrest the disease progression. In addition to the currently available treatment options for OA like NSAIDs, opioids, nutraceuticals (glucosamine sulphate and chondroitin sulphate), many new drugs are being discovered or repurposed for use in osteoarthritis. Most of these recent drugs aim at retarding the disease progression rather than providing just a symptomatic relief.

Materials and methods: All relevant articles regarding approved new drugs and pipeline drugs for osteoarthritis published between 2012–2021 were analysed. Those included animal studies as well as clinical trials. Some older articles were also referred to, provided they highlighted any significant data. The obtained data were analysed and compiled.

Results and discussion: Broadly the recent drugs for OA can be classified based upon their site of action as (i) drugs targeting articular cartilage, (ii) drugs targeting inflammation, (iii) drugs targeting the subchondral bone, and (iv) drugs for relieving pain. Ranging from in vitro studies to clinical trials, these drugs are in various phases of drug discovery. Early diagnosis of OA and its management with a drug that retards disease progression rather than prescribing just a symptom reliever is very much necessary in the current situation.

Conclusion: Need for new drugs for OA is increasing day by day. More number of clinical trials with larger sample sizes alone can satisfy the need of disease modifying drugs for OA. This review provides a deep insight into all the recent advances in the pharmacotherapy of osteoarthritis.

Graphical abstract:

Interleukin 1β and lipopolysaccharides induction dictate chondrocyte morphological properties and reduce cellular roughness and adhesion energy comparatively

Osteoarthritis (OA) is a whole joint disease marked by the degradation of the articular cartilage (AC) tissue, chronic inflammation, and bone remodeling. Upon AC's injury, proinflammatory mediators including interleukin 1β (IL1β) and lipopolysaccharides (LPS) play major roles in the onset and progression of OA. The objective of this study was to mechanistically detect and compare the effects of IL1β and LPS, separately, on the morphological and nanomechanical properties of bovine chondrocytes. Cells were seeded overnight in a full serum medium and the next day divided into three main groups: A negative control (NC) of a reduced serum medium and 10 ng/ml IL1ß or 10 ng/ml LPS-modified media. Cells were induced for 24 h. Nanomechanical properties (elastic modulus and adhesion energy) and roughness were quantified using atomic force microscopy. Nitric oxide, prostaglandin 2 (PGE2), and matrix metalloproteinases 3 (MMP3) contents; viability of cells; and extracellular matrix components were quantified. Our data revealed that viability of the cells was not affected by inflammatory induction and IL1ß induction increased PGE2. Elastic moduli of cells were similar among IL1β and NC while LPS significantly decreased the elasticity compared to NC. IL1ß induction resulted in least cellular roughness while LPS induction resulted in least adhesion energy compared to NC. Our images suggest that IL1ß and LPS inflammation affect cellular morphology with cytoskeleton rearrangements and the presence of stress fibers. Finally, our results suggest that the two investigated inflammatory mediators modulated chondrocytes' immediate responses to inflammation in variable ways.

Association Between Gut Microbiota and Osteoarthritis: A Review of Evidence for Potential Mechanisms and Therapeutics

Osteoarthritis (OA) is a multifactorial joint disease characterized by degeneration of articular cartilage, which leads to joints pain, disability and reduced quality of life in patients with OA. Interpreting the potential mechanisms underlying OA pathogenesis is crucial to the development of new disease modifying treatments. Although multiple factors contribute to the initiation and progression of OA, gut microbiota has gradually been regarded as an important pathogenic factor in the development of OA. Gut microbiota can be regarded as a multifunctional “organ”, closely related to a series of immune, metabolic and neurological functions. This review summarized research evidences supporting the correlation between gut microbiota and OA, and interpreted the potential mechanisms underlying the correlation from four aspects: immune system, metabolism, gut-brain axis and gut microbiota modulation. Future research should focus on whether there are specific gut microbiota composition or even specific pathogens and the corresponding signaling pathways that contribute to the initiation and progression of OA, and validate the potential of targeting gut microbiota for the treatment of patients with OA.

Disease-Modifying Adjunctive Therapy (DMAT) in Osteoarthritis-The Biological Effects of a Multi-Mineral Complex, LithoLexal® Joint-A Review

Modern advances in molecular medicine have led to the reframing of osteoarthritis as a metabolically active, inflammatory disorder with local and systemic contributing factors. According to the ‘inflammatory theory’ of osteoarthritis, immune response to an initial damage is the key trigger that leads to progressive joint destruction. Several intertwined pathways are known to induce and govern articular inflammation, cartilage matrix degradation, and subchondral bone changes. Effective treatments capable of halting or delaying the progression of osteoarthritis remain elusive. As a result, supplements such as glucosamine and chondroitin sulphate are commonly used despite the lack of scientific consensus. A novel option for adjunctive therapy of osteoarthritis is LithoLexal^® Joint, a marine-derived, mineral-rich extract, that exhibited significant efficacy in clinical trials. LithoLexal^® has a lattice microstructure containing a combination of bioactive rare minerals. Mechanistic research suggests that this novel treatment possesses various potential disease-modifying properties, such as suppression of nuclear factor kappa-B, interleukin 1β, tumor necrosis factor α, and cyclooxygenase-2. Accordingly, LithoLexal^® Joint can be considered a disease-modifying adjunctive therapy (DMAT). LithoLexal^® Joint monotherapy in patients with knee osteoarthritis has significantly improved symptoms and walking ability with higher efficacy than glucosamine. Preliminary evidence also suggests that LithoLexal^® Joint may allow clinicians to reduce the dose of nonsteroidal anti-inflammatory drugs in osteoarthritic patients by up to 50%. In conclusion, the multi-mineral complex, LithoLexal^® Joint, appears to be a promising candidate for DMAT of osteoarthritis, which may narrow the existing gap in clinical practice.

Sulforaphane-loaded hyaluronic acid-poloxamer hybrid hydrogel enhances cartilage protection in osteoarthritis models

Sulforaphane (SFN) is an isothiocyanate with anti-arthritic and immuno-regulatory activities, supported by the downregulation of NF-κB pathway, reduction on metalloproteinases expression and prevention of cytokine-induced cartilage degeneration implicated in OA progression. SFN promising pharmacological effects associated to its possible use, by intra-articular route and directly in contact to the site of action, highlight SFN as promising candidate for the development of drug-delivery systems. The association of poloxamers (PL) and hyaluronic acid (HA) supports the development of osteotrophic and chondroprotective pharmaceutical formulations. This study aims to develop PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release and evaluate their biocompatibility and efficacy for osteoarthritis treatment. All formulations showed viscoelastic behavior and cubic phase organization. SFN incorporation and drug loading showed a concentration-dependent behavior following HA addition. Drug release profiles were influenced by both diffusion and relaxation of polymeric chains mechanisms. The PL407-PL338-HA-SFN hydrogel did not evoke pronounced cytotoxic effects on either osteoblast or chondrosarcoma cell lines. In vitro/ex vivo pharmacological evaluation interfered with an elevated activation of NF-κB and COX-2, increased the type II collagen expression, and inhibited proteoglycan depletion. These results highlight the biocompatibility and the pharmacological efficacy of PL-HA hybrid hydrogels as delivery systems for SFN intra-articular release for OA treatment.

Both microRNA-455-5p and -3p repress hypoxia-inducible factor-2α expression and coordinately regulate cartilage homeostasis

Osteoarthritis (OA), the most common aging-related joint disease, is caused by an imbalance between extracellular matrix synthesis and degradation. Here, we discover that both strands of microRNA-455 (miR-455), -5p and -3p, are up-regulated by Sox9, an essential transcription factor for cartilage differentiation and function. Both miR-455-5p and -3p are highly expressed in human chondrocytes from normal articular cartilage and in mouse primary chondrocytes. We generate miR-455 knockout mice, and find that cartilage degeneration mimicking OA and elevated expression of cartilage degeneration-related genes are observed at 6-months-old. Using a cell-based miRNA target screening system, we identify hypoxia-inducible factor-2α (HIF-2α), a catabolic factor for cartilage homeostasis, as a direct target of both miR-455-5p and -3p. In addition, overexpression of both miR-455-5p and -3p protect cartilage degeneration in a mouse OA model, demonstrating their potential therapeutic value. Furthermore, knockdown of HIF-2α in 6-month-old miR-455 knockout cartilage rescues the elevated expression of cartilage degeneration-related genes. These data demonstrate that both strands of a miRNA target the same gene to regulate articular cartilage homeostasis.

Clusterin secretion is attenuated by the proinflammatory cytokines interleukin-1β and tumor necrosis factor-α in models of cartilage degradation

The protein clusterin has been implicated in the molecular alterations that occur in articular cartilage during osteoarthritis (OA). Clusterin exists in two isoforms with opposing functions, and their roles in cartilage have not been explored. The secreted form of clusterin (sCLU) is a cytoprotective extracellular chaperone that prevents protein aggregation, enhances cell proliferation and promotes viability, whereas nuclear clusterin acts as a pro-death signal. Therefore, these two clusterin isoforms may be putative molecular markers of repair and catabolic responses in cartilage and the ratio between them may be important. In this study, we focused on sCLU and used established, pathophysiologically relevant, in vitro models to understand its role in cytokine-stimulated cartilage degradation. The secretome of equine cartilage explants, osteochondral biopsies and isolated unpassaged chondrocytes was analyzed by western blotting for released sCLU, cartilage oligomeric protein (COMP) and matrix metalloproteinases (MMP) 3 and 13, following treatment with the proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α. Release of sulfated glycosaminoglycans (sGAG) was determined using the dimethylmethylene blue assay. Clusterin messenger RNA (mRNA) expression was quantified by quantitative real-time polymerase chain reaction. MMP-3, MMP-13, COMP, and sGAG release from explants and osteochondral biopsies was elevated with cytokine treatment, confirming cartilage degradation in these models. sCLU release was attenuated with cytokine treatment in all models, potentially limiting its cytoprotective function. Clusterin mRNA expression was down-regulated 7-days post cytokine stimulation. These observations implicate sCLU in catabolic responses of chondrocytes, but further studies are required to evaluate its role in OA and its potential as an investigative biomarker.

An insight into osteoarthritis susceptibility: Integration of immunological and genetic background

Osteoarthritis (OA) is a progressive degenerative disease that affects all synovial joints, causing the disability of the main locomotor diarthrodial joints. OA pathogenesis is caused by a complex interplay between a number of genetic and environmental risk factors, involved in the early onset and progression of this chronic inflammatory joint disease. Uncovering the underlying immunological and genetic mechanisms will enable an insight into OA pathophysiology and lead to novel and integrative approaches in the treatment of OA patients, together with a reduction of the disease risk, or a delay of its onset in susceptible patients.

Etiopathogenesis of adolescent idiopathic scoliosis: Review of the literature and new epigenetic hypothesis on altered neural crest cells migration in early embryogenesis as the key event

Adolescent idiopathic scoliosis (AIS) affects 2-3% of children. Numerous hypotheses on etiologic/causal factors of AIS were investigated, but all failed to identify therapeutic targets and hence failed to offer a cure. Therefore, currently there are only two options to minimize morbidity of the patients suffering AIS: bracing and spinal surgery. From the beginning of 1960th, spinal surgery, both fusion and rod placement, became the standard of management for progressive adolescent idiopathic spine deformity. However, spinal surgery is often associated with complications. These circumstances motivate AIS scientific community to continue the search for new etiologic and causal factors of AIS. While the role of the genetic factors in AIS pathogenesis was investigated intensively and universally recognized, these studies failed to nominate mutation of a particular gene or genes combination responsible for AIS development. More recently epigenetic factors were suggested to play causal role in AIS pathogenesis. Sharing this new approach, we investigated scoliotic vertebral growth plates removed during vertebral fusion (anterior surgery) for AIS correction. In recent publications we showed that cells from the convex side of human scoliotic deformities undergo normal chondrogenic/osteogenic differentiation, while cells from the concave side acquire a neuronal phenotype. Based on these facts we hypothesized that altered neural crest cell migration in early embryogenesis can be the etiological factor of AIS. In particular, we suggested that neural crest cells failed to migrate through the anterior half of somites and became deposited in sclerotome, which in turn produced chondrogenic/osteogenic-insufficient vertebral growth plates. To test this hypothesis we conducted experiments on chicken embryos with arrest neural crest cell migration by inhibiting expression of Paired-box 3 (Pax3) gene, a known enhancer and promoter of neural crest cells migration and differentiation. The results showed that chicken embryos treated with Pax3 siRNA (microinjection into the neural tube, 44 h post-fertilization) progressively developed scoliotic deformity during maturation. Therefore, this analysis suggests that although adolescent idiopathic scoliosis manifests in children around puberty, the real onset of the disease is of epigenetic nature and takes place in early embryogenesis and involves altered neural crest cells migration. If these results confirmed and further elaborated, the hypothesis may shed new light on the etiology and pathogenesis of AIS.

Therapeutic Applications of Type 2 Diabetes Mellitus Drug Metformin in Patients with Osteoarthritis

Type 2 diabetes mellitus (T2DM) and osteoarthritis (OA) are common chronic diseases that frequently co-exist. The link between OA and T2DM is attributed to common risk factors, including age and obesity. Several reports suggest that hyperglycemia and accumulated advanced glycosylation end-products might regulate cartilage homeostasis and contribute to the development and progression of OA. Metformin is used widely as the first-line treatment for T2DM. The drug acts by regulating glucose levels and improving insulin sensitivity. The anti-diabetic effects of metformin are mediated mainly via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), which is an energy sensing enzyme activated directly by an increase in the AMP/ATP ratio under conditions of metabolic stress. Dysregulation of AMPK is strongly associated with development of T2DM and metabolic syndrome. In this review, we discuss common risk factors, the association between OA and T2DM, and the role of AMPK. We also address the adaptive use of metformin, a known AMPK activator, as a new drug for treatment of patients with OA and T2DM.

The role of viral and bacterial infections in the pathogenesis of IPF: a systematic review and meta-analysis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease. Several risk factors such as smoking, air pollution, inhaled toxins, high body mass index and infectious agents are involved in the pathogenesis of IPF. In the present study, this meta-analysis study investigates the prevalence of viral and bacterial infections in the IPF patients and any possible association between these infections with pathogenesis of IPF.

Methods

The authors carried out this systematic literature review from different reliable databases such as PubMed, ISI Web of Science, Scopus and Google Scholar to December 2020.Keywords used were the following “Idiopathic pulmonary fibrosis”, “Infection”, “Bacterial Infection” and “Viral Infection”, alone or combined together with the Boolean operators "OR”, “AND” and “NOT” in the Title/Abstract/Keywords field. Pooled proportion and its 95% CI were used to assess the prevalence of viral and bacterial infections in the IPF patients.

Results

In this systematic review and meta-analyses, 32 studies were selected based on the exclusion/inclusion criteria. Geographical distribution of included studies was: eight studies in American people, 8; in European people, 15 in Asians, and one in Africans. The pooled prevalence for viral and bacterial infections w ere 53.72% (95% CI 38.1–69.1%) and 31.21% (95% CI 19.9–43.7%), respectively. The highest and lowest prevalence of viral infections was HSV (77.7% 95% CI 38.48–99.32%), EBV (72.02%, 95% CI 44.65–90.79%) and Influenza A (7.3%, 95% CI 2.66–42.45%), respectively. Whereas the highest and lowest prevalence in bacterial infections were related to Streptococcus sp. (99.49%, 95% CI 96.44–99.9%) and Raoultella (1.2%, 95% CI 0.2–3.08%), respectively.

Conclusions

The results of this review were confirmed that the presence of viral and bacterial infections are the risk factors in the pathogenesis of IPF. In further analyses, which have never been shown in the previous studies, we revealed the geographic variations in the association strengths and emphasized other methodological parameters (e.g., detection method). Also, our study supports the hypothesis that respiratory infection could play a key role in the pathogenesis of IP.

Is Lutikizumab, an Anti-Interleukin-1α/β Dual Variable Domain Immunoglobulin, efficacious for Osteoarthritis? Results from a bayesian network meta-analysis

Objective

Most guidelines recommend the use of nonsteroidal anti-inflammatory drugs (NSAIDs), duloxetine, and tramadol for the nonoperative treatment of osteoarthritis (OA), but the use of them is limited by the tolerability and safety concerns. Lutikizumab is a novel anti–IL-1α/β dual variable domain immunoglobulin that can simultaneously bind and inhibit IL-1α and IL-1β to relieve the pain and dysfunction symptoms. We conducted this network meta-analysis to comprehensively compare the clinical efficacy and safety of lutikizumab with other drugs recommended by guidelines.

Methods

We conducted a Bayesian network and conventional meta-analyses to compare the efficacy and safety of lutikizumab with other traditional drugs. All eligible randomized clinical trials, in PubMed, CNKI, EMBASE, and Web of Science databases, from January 2000 to January 2020, were included. The Cochrane risk of the bias assessment tool was used for quality assessment. Pain relief, function improvement, and risk of adverse effects (AEs) were compared in this study.

Results

24 articles with 11858 patients were included. Duloxetine (DUL) had the largest effect for pain relief (4.76, 95% CI [2.35 to 7.17]), and selective cox-2 inhibitors (SCI) were the most efficacious treatment for physical function improvement (SMD 3.94, 95% CI [2.48 to 5.40]). Lutikizumab showed no benefit compared with placebo for both pain relief (SMD 1.11, 95% CI [-2.29 to 4.52]) and function improvement (SMD 0.992, 95% CI [-0.433 to 4.25]). Lutikizumab and all other drugs are of favorable tolerance for patients in the treatment of OA compared with placebo.

Conclusions

Lutikizumab, the new anti–Interleukin-1α/β dual variable domain immunoglobulin, showed no improvement in pain or function when compared with placebo. Selective cox-2 inhibitors and duloxetine remain the most effective and safest treatment for OA. More high-quality trials are still needed to reconfirm the findings of this study.

Apigenin Mitigates Intervertebral Disc Degeneration through the Amelioration of Tumor Necrosis Factor α (TNF-α) Signaling Pathway

Background

Intervertebral disc degeneration (IDD) is a common spinal disease affected by environmental and lifestyle factors that has a significant pathological cascade toward inflammation and partial disability. There is currently no therapy that can completely restore the cellular derangement in IDD. Hence, in this study, the therapeutic effects of apigenin on IDD were evaluated using a rat model.

Material/Methods

Animals were separated into 4 groups: Grp 1, sham-operated control; Grp 2, IDD-induced; Grp 3, IDD-induced+apigenin treatment; Grp 4, apigenin control. The animals were assessed for inflammatory cytokines, chemokines, and prostaglandin signaling.

Results

There were significant increases in the inflammatory cytokines IL-1β, IL-2, IL-6, IL-8 and IL-17 in the IDD-induced group compared to that of control. Moreover, with increased levels of MMP-3, MMP-9, ADAMTS-4, and syndecan-4, the levels of TNF-α, IFN-γ, prostaglandin E2, and cyclooxygenase 2 were directly increased in the IDD-induced group. In contrast, apigenin protectively restored levels of prostaglandin signaling and reduced cytokine levels. In addition, nucleus pulposus cells cultured separately with either TNF-α inhibitor or apigenin significantly attenuated the levels of extracellular matrix proteins.

Conclusions

The reduction of cytokine levels under apigenin treatment suggests it may be a promising target drug therapy for the treatment of deleterious IDD conditions.

Identifying effector molecules, cells, and cytokines of innate immunity in OA

Inflammatory changes are observed in affected joints of osteoarthritis (OA) patients and are thought to be involved in the pathology that develops along OA progression. This narrative review provides an overview of the various cell types that are present in the joint during OA and which alarmins, cytokines, chemokines, growth factors, and other mediators they produce. Moreover, the involvement of more systemic processes like inflammaging and its associated cellular senescence in the context of OA are discussed.

Nasal Chondrocyte-Derived Soluble Factors Affect Chondrogenesis of Cocultured Mesenchymal Stem Cells

To investigate the effect of soluble factors released from human nasal chondrocytes (NCs) on cocultured human bone marrow mesenchymal stem cells (MSCs) and NC tissue-engineered constructs. Cartilage engineered from pure NCs on a three-dimensional (3D) porous collagen scaffold was cultured indirectly in a Transwell system with cartilage engineered from a direct coculture of human bone marrow-derived MSCs and NCs on a 3D porous collagen scaffold. The soluble factors were measured in the conditioned media from the different chambers of the Transwell system. Engineered cartilage from cocultures exposed to the pure NC construct exhibited reduced chondrogenic potential relative to control constructs, shown by reduced extracellular matrix deposition and increased expression of hypertrophic markers. Analysis of the soluble factors within the conditioned media showed an increase in inflammatory cytokines in the coculture chamber exposed to the pure NC construct. Principal component analysis revealed that the majority of the data variance could be explained by proinflammatory factors and hypertrophic chondrogenesis. In conclusion, our data suggest that inflammatory cytokines derived from NCs reduce the chondrogenic potential of coculture engineered cartilage through the induction of hypertrophic chondrogenesis. Impact statement The use of engineered cartilage from cocultured nasal chondrocytes (NCs) and mesenchymal stem cells for nasal cartilage reconstruction may be problematic. Our data suggest that the soluble factors from surrounding native NCs in the cartilage to be fixed can compromise the quality of the engineered cartilage if used in reconstructive surgery.

Cocktail of Hyaluronic Acid and Human Amniotic Mesenchymal Cells Effectively Repairs Cartilage Injuries in Sodium Iodoacetate-Induced Osteoarthritis Rats

Osteoarthritis (OA) is one of the most common refractory degenerative articular cartilage diseases. Human amniotic mesenchymal cells (hAMSCs) have emerged as a promising stem cell source for cartilage repair, and hyaluronic acid (HA) has proven to be a versatile regulator for stem cell transplantation. Herein, an effective and straightforward intra-articular injection therapy using a cocktail of hAMSCs and HA was developed to treat knee OA in a rat model. The injured cartilage was remarkably regenerated, yielding results comparable to normal cartilage levels after 56 days of treatment. Both hAMSCs and HA were indispensable organic components in this therapy, in which HA could synergistically enhance the effects of hAMSCs on cartilage repair. The regenerative mechanism was attributed to the fact that the addition of HA comprehensively enhances the activities of hAMSCs, including chondrogenic differentiation, proliferation, colonization, and regenerative modulation. This cocktail paves a new avenue for injection therapy to treat OA, holding the potential to realize rapid clinical translation.

Enoxolone suppresses apoptosis in chondrocytes and progression of osteoarthritis via modulating the ERK1/2 signaling pathway

Introduction

Osteoarthritis (OA) is an inflammatory disorder of synovial joints which is mainly treated with therapeutic agents showing side effects associated with the gastrointestinal (GI) and metabolic system. Consequently, there is urgent need for a potent, safe and novel agent for treating OA and related disorders. Enoxolone is a pentacyclic triterpenoid obtained from the herb liquorice. Based on earlier findings, we postulated that enoxolone may produce chondroprotective activity by exerting anti-inflammatory, anti-catabolic and oxidative stress-decreasing effects.

Material and methods

The chondrocytes were extracted from the femoral head articular cartilage of healthy rats. Immunofluorescence staining was done for identification of chondrocytes. Cell viability and proliferation studies were done using Cell Counting Kit-8. Apoptotic cells were identified by TUNEL assay and flow cytometry analysis. Autophagy was assessed by monodansylcadaverine assay. Western blot analysis was done for expression of proteins.

Results

In the present study we investigated the protective effect of enoxolone on interleukin 1β (IL-1β) treated Iry chondrocytes in vitro. Treatment with IL-1β resulted in a significant reduction in cell viability of cells in increasing dose and time. Treatment with enoxolone along with IL-1β caused a significant decrease in growth inhibition. Also, enoxolone inhibited the IL-1β mediated apoptosis and activation of caspase-3 in cells. We also observed that enoxolone elevated the levels of p-ERK1/2, light chain 3 (LC3)-II and Beclin-1 (autophagy markers) in chondrocytes. The expression of (LC3)-II and Beclin-1 was decreased when the cells were treated with U0126 (ERK1/2 inhibitor).

Conclusions

Our findings demonstrate that enoxolone could suppress inflammatory signaling and apoptosis via the ERK1/2 pathway in chondrocytes.

UFL1 attenuates IL-1β-induced inflammatory response in human osteoarthritis chondrocytes

Osteoarthritis (OA) is a chronic inflammatory joint disease characterized by degradation of articular cartilage. Ubiquitin-fold modifier 1 (UFM1)-specific ligase 1 (UFL1) is an UFM1 E3 ligase that has been identified as a regulator of inflammatory response. However, the role of UFL1 in OA remains unknown. The aim of the present study was to explore the function of UFL1 in an in vitro OA system in chondrocytes. Our results showed that UFL1 was lowly expressed in both OA articular tissues and chondrocytes with IL-1β induction. Ectopic expression of UFL1 improved cell viability of IL-1β-induced chondrocytes. UFL1 suppressed the production of NO and PGE2, as well the expression levels of iNOS and COX-2 in IL-1β-induced chondrocytes. The IL-1β-induced increases in TNF-α and IL-6 levels were attenuated by UFL1. Ectopic expression of UFL1 inhibited the production of extracellular matrix (ECM) degrading enzymes including matrix metalloproteinase 3 (MMP-3), MMP-13, ADAMTS-4 and ADAMTS-5 in chondrocytes with IL-1β induction. Additionally, UFL1 suppressed IL-1β-induced activation of NF-κB signaling pathway in chondrocytes. In conclusion, these findings indicated that UFL1 exerted protective effect on IL-1β-induced chondrocytes. Thus, UFL1 might be a potential target for the treatment of OA.

lnc-SAMD14-4 can regulate expression of the COL1A1 and COL1A2 in human chondrocytes

Osteoarthritis (OA) is the most common motor system disease in aging people, characterized by matrix degradation, chondrocyte death, and osteophyte formation. OA etiology is unclear, but long noncoding RNAs (lncRNAs) that participate in numerous pathological and physiological processes may be key regulators in the onset and development of OA. Because profiling of lncRNAs and their biological function in OA is not understood, we measured lncRNA and mRNA expression profiles using high-throughput microarray to study human knee OA. We identified 2,042 lncRNAs and 2,011 mRNAs that were significantly differentially expressed in OA compared to non-OA tissue (>2.0- or < - 2.0-fold change; p < 0.5), including 1,137 lncRNAs that were upregulated and 905 lncRNAs that were downregulated. Also, 1,386 mRNA were upregulated and 625 mRNAs were downregulated. QPCR was used to validate chip results. Gene Ontology analysis and the Kyoto Encyclopedia of Genes and Genomes was used to study the biological function enrichment of differentially expressed mRNA. Additionally, coding-non-coding gene co-expression (CNC) network construction was performed to explore the relevance of dysregulated lncRNAs and mRNAs. Finally, the gain/loss of function experiments of lnc-SAMD14-4 was implemented in IL-1β-treated human chondrocytes. In general, this study provides a preliminary database for further exploring lncRNA-related mechnisms in OA.

Inhibiting the PI3K/AKT/NF-κB signal pathway with nobiletin for attenuating the development of osteoarthritis: in vitro and in vivo studies

Osteoarthritis (OA), an age-related degenerative disease, is characterized by progressive degradation of the articular cartilage. There is increasing evidence that nobiletin (NOB) exerts special biological functions in a variety of diseases. However, whether it protects against OA remains unknown. In this study, we investigated the anti-inflammatory and chondroprotective effects of NOB on IL-1β-induced human OA chondrocytes and in the surgical DMM mice OA models. In vitro, NOB treatment completely suppressed the overproduction of pro-inflammatory mediators, including PGE2, NO, COX-2, iNOS, TNF-α and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, NOB exerted a potent inhibitory effect on the expression of MMP-13 and ADAMTS-5 as well as the degradation of aggrecan and collagen-II, which leads to the degradation of the extracellular matrix. Furthermore, NOB dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with NOB not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. In conclusion, our study suggests that NOB holds novel therapeutic potential for the treatment of OA.

Wwp2 maintains cartilage homeostasis through regulation of Adamts5

The WW domain-containing protein 2 (Wwp2) gene, the host gene of miR-140, codes for the Wwp2 protein, which is an HECT-type E3 ubiquitin ligases abundantly expressed in articular cartilage. However, its function remains unclear. Here, we show that mice lacking Wwp2 and mice in which the Wwp2 E3 enzyme is inactivated (Wwp2-C838A) exhibit aggravated spontaneous and surgically induced osteoarthritis (OA). Consistent with this phenotype, WWP2 expression level is downregulated in human OA cartilage. We also identify Runx2 as a Wwp2 substrate and Adamts5 as a target gene, as similar as miR-140. Analysis of Wwp2-C838A mice shows that loss of Wwp2 E3 ligase activity results in upregulation of Runx2-Adamts5 signaling in articular cartilage. Furthermore, in vitro transcribed Wwp2 mRNA injection into mouse joints reduces the severity of experimental OA. We propose that Wwp2 has a role in protecting cartilage from OA by suppressing Runx2-induced Adamts5 via Runx2 poly-ubiquitination and degradation.

miR-21-5p protects IL-1β-induced human chondrocytes from degradation

OBJECTIVE

Osteoarthritis (OA) is a prevalent degenerative disease caused by various factors. MicroRNAs are important regulators in OA. MiR-21-5p expression is decreased in OA cartilage, but the effects of modulating miR-21-5p on cartilage regeneration are unknown. Therefore, our aim was to investigate the effects of miR-21-5p on cartilage metabolism of OA chondrocytes.

DESIGN

We used IL-1β (10 ng/ml) to mimic OA chondrocytes. OA chondrocytes were transfected with miR-21-5p, the gene expression of COL2A1, MMP13, and ADAMTS5 was detected by qPCR. At the same time, COL2A1, MMP13, and ADAMTS5 were analyzed at the protein level by Western blot. CCK8 measured the cell's viability and SA-β-gal detected the cell's senescence.

RESULTS

Upregulation of miR-21-5p had increased COL2A1 expression and decreased MM P13 and ADAMTS5 expression, which were in accord with Western blot data. SA-β-gal activity significantly increased, the viability was decreased in OA chondrocytes, and upregulation of miR-21-5p can decrease the SA-β-gal activity and increase cell viability.

CONCLUSION

MiR-21-5p might be a potential disease-modifying compound in OA, as it promotes hyaline cartilage production. These results provided that novel insights into the important function in OA pathological development.

Analysis of differentially expressed genes in rheumatoid arthritis and osteoarthritis by integrated microarray analysis

BACKGROUND

Rheumatoid arthritis (RA) and osteoarthritis (OA) were two major types of joint diseases. This study aimed to explore the mechanism underlying OA and RA and analyze their difference by integrated analysis of multiple gene expression data sets.

METHODS

Gene expression data sets of RA and OA were downloaded from The Gene Expression Omnibus. Shared and specific differentially expressed genes (DEGs) in RA and OA were identified by integrated analysis of multiple gene expression data sets. Functional annotation and protein-protein interaction (PPI) network construction of OA- and RA-specific DEGs were performed to further explore the molecular mechanisms underlying RA and OA and analyze the mechanism differences between them.

RESULTS

Compared with normal controls, 3757 and 2598 DEGs were identified in RA and OA, respectively. Among them, 2176 DEGs were RA-specific DEGs and 1017 DEGs were OA-specific DEGs. Moreover, the expression of 17 DEGs played opposite pattern in RA and OA compared with normal controls. Chemokine signaling pathway and oxidative phosphorylation were significantly enriched pathways for RA- and OA-specific DEGs, respectively. BIRC2 and CSNK1E were respective hub genes of RA- and OA-specific PPI network.

CONCLUSION

Our findings provided clues for the specific mechanism and developing specific biomarkers for RA and OA.

Expression of inflammatory cytokines in mesenchymal stromal cells is sensitive to culture conditions and simple cell manipulations

BACKGROUND

Mesenchymal stromal cells (MSCs) can be used in several clinical applications. While MSCs are frequently cultured in fetal bovine serum for in vitro experimentation, human serum supplements are required for cells to be used in patients. Here we show how different human serum supplements and in vitro manipulations used during the cell culture impact on MSC proliferation rate and expression of inflammatory molecules.

METHODS

MSCs were cultured in medium supplemented with human plasma or serum combined with human platelet lysate (PL) and/or basic fibroblast growth factor (FGF2). Real time RT-PCR and western blot were used to assess expression of inflammatory cytokines.

RESULTS

Serum with addition of FGF2 gave the fastest proliferation rate. However, serum with FGF2 also increased expression of genes encoding inflammatory cytokines. The most favorable expansion condition for chondrogenic differentiation and inhibition of cartilage matrix degrading enzymes was plasma supplemented with PL and FGF2. Detachment of cells using trypsin gave considerable upregulation of inflammatory cytokine mRNAs which lasted for up to 24 h, with concomitant increase in protein levels. Even the gentle act of changing medium led to upregulation of cytokine mRNA, caused by addition of fresh serum.

DISCUSSION

Different culture conditions and simple cell manipulation influence proliferation rate and expression of inflammatory genes. Supplementing culture medium with allogeneic AB serum and FGF2 during monolayer expansion supported cell expansion better than other supplements, but also induced the highest levels of inflammatory cytokines and gave inferior results for chondrogenic differentiation. The importance of the composition of the culture medium and even gentle in vitro manipulation of the cells should be taken into account in the planning of procedures using in vitro expanded MSCs.

Investigational drugs for the treatment of osteoarthritis, an update on recent developments

INTRODUCTION

Osteoarthritis (OA) is the leading cause of pain, loss of function, and disability among elderly, with the knee the most affected joint. It is a heterogeneous condition characterized by complex and multifactorial etiologies which contribute to the broad variation in symptoms presentation and treatment responses that OA patients present. This poses a challenge for the development of effective treatment on OA.

AREAS COVERED

This review will discuss recent development of agents for the treatment of OA, updating our previous narrative review published in 2015. They include drugs for controlling local and systemic inflammation, regulating articular cartilage, targeting subchondral bone, and relieving pain.

EXPERT OPINION

Although new OA drugs such as monoclonal antibodies have shown marked effects and favorable tolerance, current treatment options for OA remain limited. The authors believe there is no miracle drug that can be used for all OA patients'; treatment and disease stage is crucial for the effectiveness of drugs. Therefore, early diagnosis, phenotyping OA patients and precise therapy would expedite the development of investigational drugs targeting at symptoms and disease progression of OA.

Select Biomarkers on the Day of Anterior Cruciate Ligament Reconstruction Predict Poor Patient-Reported Outcomes at 2-Year Follow-Up: A Pilot Study

Background

The majority of patients develop posttraumatic osteoarthritis within 15 years of anterior cruciate ligament (ACL) injury. Inflammatory and chondrodegenerative biomarkers have been associated with both pain and the progression of osteoarthritis; however, it remains unclear if preoperative biomarkers differ for patients with inferior postoperative outcomes.

Hypothesis/Purpose

The purpose of this pilot study was to compare biomarkers collected on the day of ACL reconstruction between patients with “good” or “poor” 2-year postoperative outcomes. We hypothesized that inflammatory cytokines and chondrodegenerative biomarker concentrations would be significantly greater in patients with poorer outcomes.

Study Design

Prospective cohort design.

Methods

22 patients (9 females, 13 males; age = 19.5 ± 4.1 years; BMI = 24.1 ± 3.6 kg/m²) previously enrolled in a randomized trial evaluating early anti-inflammatory treatment after ACL injury. Biomarkers of chondrodegeneration and inflammation were assessed from synovial fluid (sf) samples collected on the day of ACL reconstruction. Participants completed Knee Injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) questionnaires two years following surgery. Patients were then categorized based on whether their KOOS Quality of Life (QOL) score surpassed the Patient Acceptable Symptom State (PASS) threshold of 62.5 points or the IKDC PASS threshold of 75.9 points.

Results

Patients that failed to reach the QOL PASS threshold after surgery (n = 6, 27%) had significantly greater sf interleukin-1 alpha (IL-1α; p = 0.004), IL-1 receptor antagonist (IL-1ra; p = 0.03), and matrix metalloproteinase-9 (MMP-9; p = 0.01) concentrations on the day of surgery. Patients that failed to reach the IKDC PASS threshold (n = 9, 41%) had significantly greater sf IL-1α (p = 0.02).

Conclusion

These pilot data suggest that initial biochemical changes after injury may be an indicator of poor outcomes that are not mitigated by surgical stabilization alone. Biological adjuvant treatment in addition to ACL reconstruction may be beneficial; however, these data should be used for hypothesis generation and more definitive randomized clinical trials are necessary.

The protective effect of phloretin in osteoarthritis: an in vitro and in vivo study

Osteoarthritis (OA) is a degenerative joint disease characterized by the degradation and inflammation of cartilage. Phloretin, a type of dihydrochalcone mainly found in apples and apple-derived products, has been reported to possess various potent biological effects such as antioxidant, anticancer, anti-inflammatory, and immunomodulatory. However, the anti-inflammatory effects of phloretin on OA have not been reported. This study was aimed at assessing the effects of phloretin on human OA chondrocytes. Human OA chondrocytes were pretreated with phloretin (10, 30, and 100 μM) for 2 h and subsequently stimulated with IL-1β for 24 h. The production of NO, PGE2, TNF-α, and IL-6 was determined using the Griess reagent and ELISAs. The mRNA expression of COX-2, iNOS, MMP-3, MMP-13, and ADAMTS-5 was measured by real-time PCR. Changes in the protein expression of COX-2, iNOS, MMPs, ADAMTS, aggrecan, collagen-II, NF-κB, and the PI3K/Akt signaling pathway were detected by western blotting. In this study, we found that phloretin significantly inhibited the IL-1β-induced production of NO, PGE2, TNF-α, and IL-6, the expression of COX-2, iNOS, MMP-3, MMP-13, and ADAMTS-5, and the degradation of aggrecan and collagen-II in human OA chondrocytes. Furthermore, phloretin dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with phloretin not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in a mouse model of OA. Moreover, immunohistochemical results showed that phloretin significantly decreased the expression of MMP-13 and increased the expression of collagen-II in OA in mice. In conclusion, these results suggest that phloretin may be a potential agent for the treatment of OA.

Testing the potency of anti-TNF-α and anti-IL-1β drugs using spheroid cultures of human osteoarthritic chondrocytes and donor-matched chondrogenically differentiated mesenchymal stem cells

Inflammation plays a major role in progression of rheumatoid arthritis, a disease treated with antagonists of tumor necrosis factor-alpha (TNF-α) and interleukin 1β (IL-1β). New in vitro testing systems are needed to evaluate efficacies of new anti-inflammatory biological drugs, ideally in a patient-specific manner. To address this need, we studied microspheroids containing 10,000 human osteoarthritic primary chondrocytes (OACs) or chondrogenically differentiated mesenchymal stem cells (MSCs), obtained from three donors. Hypothesizing that this system can recapitulate clinically observed effects of anti-inflammatory drugs, spheroids were exposed to TNF-α, IL-1β, or to supernatant containing secretome from activated macrophages (MCM). The anti-inflammatory efficacies of anti-TNF-α biologicals adalimumab, infliximab, and etanercept, and the anti-IL-1β agent anakinra were assessed in short-term microspheroid and long-term macrospheroid cultures (100,000 OACs). While gene and protein expressions were evaluated in microspheroids, diameters, amounts of DNA, glycosaminoglycans, and hydroxiproline were measured in macrospheroids. The tested drugs significantly decreased the inflammation induced by TNF-α or IL-1β. The differences in potency of anti-TNF-α biologicals at 24 h and 3 weeks after their addition to inflamed spheroids were comparable, showing high predictability of short-term cultures. Moreover, the data obtained with microspheroids grown from OACs and chondrogenically differentiated MSCs were comparable, suggesting that MSCs could be used for this type of in vitro testing. We propose that in vitro gene expression measured after the first 24 h in cultures of chondrogenically differentiated MSCs can be used to determine the functionality of anti-TNF-α drugs in personalized and preclinical studies. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1045-1058, 2018.

In Vitro Anti-Inflammation and Chondrogenic Differentiation Effects of Inclusion Nanocomplexes of Hyaluronic Acid-Beta Cyclodextrin and Simvastatin

The aim of this study was to prepare inclusion nanocomplexes of hyaluronic acid-β-cyclodextrin and simvastatin (HA-β-CD/SIM) and evaluate in vitro anti-inflammation effects on lipopolysaccharide (LPS)-activated synoviocytes and chondrogenic differentiation effects on rat adipose-derived stem cells (rADSCs). The β-CD moieties in HA-β-CD could incorporate SIM to form HA-β-CD/SIM nanocomplexes with diameters of 297-350 nm. HA-β-CD/SIM resulted in long-term release of SIM from the nanocomplexes for up to 63 days in a sustained manner. In vitro studies revealed that HA-β-CD/SIM nanocomplexes were able to effectively and dose-dependently suppress the mRNA expression levels of pro-inflammatory markers such as matrix metallopeptidase-3 (MMP-3), MMP-13, cyclooxygenase-2 (COX-2), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), interleukin-6 (IL-6), and tumor necrosis factor (TNF-α) in LPS-stimulated synoviocytes. HA-β-CD/SIM-treated rADSCs significantly and dose-dependently enhanced mRNA expressions of aggrecan, collagen type II (COL2A1), and collagen type X (COL10A1), implying that HA-β-CD/SIM greatly induced the chondrogenic differentiation of rADSCs. Conclusively, HA-β-CD/SIM nanocomplexes will be a promising therapeutic material to alleviate inflammation as well as promote chondrogenesis.

The role of leptin in osteoarthritis

BACKGROUND

The pathogenesis of osteoarthritis (OA) is not clear; leptin may be related to its pathogenesis.

METHODS

We reviewed articles on leptin in OA, chondrocytes, and in vitro experiments. It is concluded that leptin may lead to OA via some signaling pathways. At the same time, the concentration of leptin in vitro experiments and OA/rheumatoid arthritis (RA) patients was summarized.

RESULTS

Leptin levels in serum and synovial fluid of OA/RA patients were higher than normal person. In the condition of infection and immunity, serum leptin levels in the peripheral blood significantly increase. Because of the close relationship between obesity, leptin, and OA, it is crucial to study the effects of weight loss and exercise intervention on serum leptin levels to improve the symptoms of OA patients.

CONCLUSION

Treatment for leptin-increased obesity may be a treatment for OA. The role of leptin in OA cannot be ignored and needs to be further studied.

Depletion of aquaporin 1 decreased ADAMTS‑4 expression in human chondrocytes

Inflammation serves an important role in the progression of osteoarthritis (OA), and IL-1β may act as a catabolic factor on cartilage, reducing the synthesis of primary cartilage components type II collagen and aggrecan. Aquaporin 1 (AQP1) is a 28-kDa water channel formed of six transmembrane domains on the cell membrane. AQP1 is highly expressed in the anus, gallbladder and liver, and is moderately expressed in the hippocampus, ependymal cells of the central nervous system and articular cartilage. It was hypothesized that AQP1 may be highly expressed in OA cartilage and that it may increase the expression of catabolic factors during inflammatory OA progression. Therefore, the present study evaluated AQP1 functions in human OA articular chondrocytes. Primary chondrocytes were isolated from human hip and knee cartilage tissues, cultured and transfected with AQP1-specific small interfering RNA with or without subsequent IL-1β treatment. In vitro explant culture from hip cartilages were also prepared. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to assess the expression of AQP genes in human articular cartilage, AQP1 immunohistochemistry of the cartilages and explant culture, as well as RT-quantitative PCR, western blotting and immunocytochemistry/immunofluorescence of OA chondrocytes to evaluate the expression of AQP1, and catabolic and anabolic factors. RT-PCR results demonstrated that AQP0, 1, 3, 7, 9, and 11 were expressed in OA chondrocytes. Immunohistochemistry revealed that AQP1 was highly expressed in the superficial to middle zones of OA articular cartilages. Additionally, AQP1 mRNA was significantly higher in OA cartilage and IL-1β treatment significantly increased AQP1 expression in hip explant cartilage. Furthermore, AQP1 downregulation decreased a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS)-4 expression in OA chondrocytes, though it did not affect other associated genes. Immunofluorescence showed that AQP1 and ADAMTS-4 were co-localized. These findings indicated that AQP1 depletion may decrease ADAMTS-4 expression in human OA chondrocytes. Therefore, regulating AQP1 expression may be a strategy to suppress catabolic factors during OA progression.

Icariin Regulates Cellular Functions and Gene Expression of Osteoarthritis Patient-Derived Human Fibroblast-Like Synoviocytes

Synovial inflammation plays an important role in the pathogenesis and progress of osteoarthritis (OA). There is an urgent need to find safe and effective drugs that can reduce the inflammation and regulate the pathogenesis of cytokines of the OA disease. Here, we investigated the effect of icariin, the major pharmacological active component of herb Epimedium on human osteoarthritis fibroblast-like synoviocytes (OA–FLSs). The OA–FLSs were isolated from patients with osteoarthritis and cultured in vitro with different concentrations of icariin. Then, cell viability, proliferation, and migration were investigated; MMP14, GRP78, and IL-1β gene expression levels were detected via qRT-PCR. Icariin showed low cytotoxicity to OA–FLSs at a concentration of under 10 μM and decreased the proliferation of the cells at concentrations of 1 and 10 μM. Icariin inhibited cell migration with concentrations ranging from 0.1 to 1 μM. Also, the expression of three cytokines for the pathogenesis of OA which include IL-1β, MMP14 and GRP78 was decreased by the various concentrations of icariin. These preliminary results imply that icariin might be an effective compound for the treatment of OA disease.