MicroRNA-9 regulates the development of knee osteoarthritis through the NF-kappaB1 pathway in chondrocytes

Nuclear factor κB overactivation in the intervertebral disc leads to macrophage recruitment and severe disc degeneration

Persistent inflammation has been associated with severe disc degeneration (DD). This study investigated the effect of prolonged nuclear factor κB (NF-κB) activation in DD. Using an inducible mouse model, we genetically targeted cells expressing aggrecan, a primary component of the disc extra cellular matrix, for activation of the canonical NF-κB pathway. Prolonged NF-κB activation led to severe structural degeneration accompanied by increases in gene expression of inflammatory molecules (Il1b, Cox2, Il6, and Nos2), chemokines (Mcp1 and Mif), and catabolic enzymes (Mmp3, Mmp9, and Adamts4). Increased recruitment of proinflammatory (F4/80+,CD38+) and inflammatory resolving (F4/80+,CD206+) macrophages was observed within caudal discs. We found that the secretome of inflamed caudal disc cells increased macrophage migration and inflammatory activation. Lumbar discs did not exhibit phenotypic changes, suggestive of regional spinal differences in response to inflammatory genetic overactivation. Results suggest prolonged NF-κB activation can induce severe DD through increases in inflammatory cytokines, chemotactic proteins, catabolic enzymes, and the recruitment and activation of macrophage cell populations.

The Potential Neuroprotective Effect of Thymoquinone on Scopolamine-Induced In Vivo Alzheimer's Disease-like Condition: Mechanistic Insights

BACKGROUND

Alzheimer's disease (AD) is a common neurodegenerative disorder without effective treatment. Thymoquinone (TQ) has demonstrated potential in exhibiting anti-inflammatory, anti-cancer, and antioxidant characteristics. Despite TQ's neuroprotection effect, there is a scarcity of information regarding its application in AD research, and its molecular trajectories remain ambiguous. Thus, the objective of the current investigation was to examine the potential beneficial effects and underlying mechanisms of TQ in scopolamine (SCOP)-induced neuronal injury to mimic AD in vivo model.

METHODS

Thirty mice were divided into normal, SCOP, and TQ groups. The Y-maze and pole climbing tests were performed to measure memory and motor performance. Afterwards, histopathological and immunohistochemical examinations were carried out. Furthermore, peroxisome proliferator-activated receptor gamma (PPAR-γ) signaling pathway-related proteins and genes were detected with an emphasis on the role of miR-9.

RESULTS

TQ has the potential to ameliorate cognitive deficits observed in SCOP-induced AD-like model, as evidenced by the improvement in behavioral outcomes, histopathological changes, modulation of the expression pattern of PPAR-γ downstream targets with a significant decrease in the deposition of amyloid beta (Aβ).

CONCLUSIONS

TQ provided meaningful multilevel neuroprotection through its anti-inflammatory and its PPAR-γ agonist activity. Consequently, TQ may possess a potential beneficial role against AD development.

Exploring the Feasibility of Circulating miRNAs as Diagnostic and Prognostic Biomarkers in Osteoarthritis: Challenges and Opportunities

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage degradation and joint inflammation. As the most common aging-related joint disease, OA is marked by inadequate extracellular matrix synthesis and the breakdown of articular cartilage. However, traditional diagnostic methods for OA, relying on clinical assessments and radiographic imaging, often need to catch up in detecting early-stage disease or i accurately predicting its progression. Consequently, there is a growing interest in identifying reliable biomarkers that can facilitate early diagnosis and prognosis of OA. MicroRNAs (miRNAs) have emerged as potential candidates due to their involvement in various cellular processes, including cartilage homeostasis and inflammation. This review explores the feasibility of circulating miRNAs as diagnostic and prognostic biomarkers in OA, focusing on knee OA while shedding light on the challenges and opportunities associated with their implementation in clinical practice.

Nuclear Factor Kappa B Over-Activation in the Intervertebral Disc Leads to Macrophage Recruitment and Severe Disc Degeneration

Objective

Low back pain (LBP) is the leading cause of global disability and is thought to be driven primarily by intervertebral disc (IVD) degeneration (DD). Persistent upregulation of catabolic enzymes and inflammatory mediators have been associated with severe cases of DD. Nuclear factor kappa B (NF-κB) is a master transcription regulator of immune responses and is over expressed during inflammatory-driven musculoskeletal diseases, including DD. However, its role in triggering DD is unknown. Therefore, this study investigated the effect of NF-κB pathway over-activation on IVD integrity and DD pathology.

Methods

Using skeletally mature mouse model, we genetically targeted IVD cells for canonical NF-κB pathway activation via expression of a constitutively active form of inhibitor of κB kinase B (IKKβ), and assessed changes in IVD cellularity, structural integrity including histology, disc height, and extracellular matrix (ECM) biochemistry, biomechanics, expression of inflammatory, catabolic, and neurotropic mediators, and changes in macrophage subsets, longitudinally up to 6-months post activation.

Results

Prolonged NF-κB activation led to severe structural degeneration, with a loss of glycosaminoglycan (GAG) content and complete loss of nucleus pulposus (NP) cellularity. Structural and compositional changes decreased IVD height and compressive mechanical properties with prolonged NF-κB activation. These alterations were accompanied by increases in gene expression of inflammatory molecules ( Il1b, Il6, Nos2 ), chemokines ( Mcp1 , Mif ), catabolic enzymes ( Mmp3, Mmp9, Adamts4 ), and neurotrophic factors ( Bdnf , Ngf ) within IVD tissue. Increased recruitment of activated F4/80 + macrophages exhibited a greater abundance of pro-inflammatory (CD38 + ) over inflammatory-resolving (CD206 + ) macrophage subsets in the IVD, with temporal changes in the relative abundance of macrophage subsets over time, providing evidence for temporal regulation of macrophage polarization in DD in vivo, where macrophages participate in resolving the inflammatory cascade but promote fibrotic transformation of the IVD matrix. We further show that NF-κB driven secretory factors from IVD cells increase macrophage migration and inflammatory activation, and that the secretome of inflammatory-resolving macrophages mitigates effects of NF-κB overactivation.

Conclusion

Overall the observed results suggest prolonged NF-κB activation can induce severe DD, acting through increases in inflammatory cytokines, chemotactic proteins, catabolic enzymes, and the recruitment and inflammatory activation of a macrophage cell populations, that can be mitigated with inflammatory-resolving macrophage secretome.

Study on the mechanism and pharmacokinetics of HB-NC4 based on C5b-9 target in the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease that mostly occurs in elderly individuals over 60 years old. The detailed pathogenesis of OA is unclear. Medicines available on the market are nonsteroidal anti-inflammatory drugs. Therefore, in this study, a fusion protein was introduced, and the detailed mechanism that could alleviate OA was discussed. As a targeted protein, HB-NC4 showed better binding ability to chondrocytes, and its half-life period was prolonged compared to NC4 alone. In addition, HB-NC4 can not only affect the levels of C3 and C5, but also inhibit the formation of the membrane-attack complex (MAC, C5b-9), thereby further affecting the expression of MAPK signalling pathway-related proteins to achieve the goal of treating OA. Thus, in this study, we demonstrate the pharmacokinetics of HB-NC4 and its mechanism to alleviate OA by regulating the complement system and MAPK signalling pathway. This study provides a new method for OA therapy based on fusion proteins.

Circular RNA circNFKB1 promotes osteoarthritis progression through interacting with ENO1 and sustaining NF-κB signaling

Inflammatory cytokines-induced activation of the nuclear factor κB (NF-κB) pathway plays a critical role in the pathogenesis of osteoarthritis (OA). Circular RNA (circRNA) has been identified as important epigenetic factor in numerous diseases. However, the biological roles of inflammation-related circRNAs in regulating OA pathogenesis remain elusive. Here, we revealed circRNA expression profiles in human primary chondrocytes with interleukin-1β (IL-1β) stimulation by circRNA sequencing. We identified a highly upregulated circRNA, termed as circNFKB1 in inflamed chondrocytes and osteoarthritic cartilage. As a circRNA derived from exon 2-5 of NFKB1, circNFKB1 is located in both cytoplasm and nucleus of chondrocytes. Furthermore, knockdown of circNFKB1 inhibited extracellular matrix (ECM) catabolism and rescued IL-1β impaired ECM anabolism whereas ectopic expression of circNFKB1 significantly promoted chondrocytes degradation in vitro. Moreover, intraarticular injection of adenovirus-circNFKB1 in mouse joints triggered spontaneous cartilage loss and OA development. Mechanistically, circNFKB1 interacted with α-enolase (ENO1), regulated the expression of its parental gene NFKB1 and sustained the activation of NF-κB signaling pathway in chondrocytes. Therefore, this study highlights a novel ENO1-interacting circNFKB1 in OA pathogenesis, and provides valuable insights into understanding the regulatory mechanism of NF-κB signaling in chondrocytes and a promising therapeutic target for the treatment of OA.

The Involvement of Neutrophils in the Pathophysiology and Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic disability that significantly impairs quality of life. OA is one of the most prevalent joint pathologies in the world, characterized by joint pain and stiffness due to the degeneration of articular cartilage and the remodeling of subchondral bone. OA pathogenesis is unique in that it involves simultaneous reparative and degradative mechanisms. Low-grade inflammation as opposed to high-grade allows for this coexistence. Previously, macrophages and T cells have been identified as playing major roles in the inflammation and destruction of OA joints, but recent studies have demonstrated that neutrophils also contribute to the pathogenesis. Neutrophils are the first immune cells to enter the synovium after joint injury, and neutrophilic activity is indispensably a requisite for the progression of OA. Neutrophils act through multiple mechanisms including tissue degeneration via neutrophil elastase (NE), osteophyte development, and the release of inflammatory cytokines and chemokines. As the actions of neutrophils in OA are discovered, the potential for novel therapeutic targets as well as diagnostic methods are revealed. The use of chondrogenic progenitor cells (CPCs), microRNAs, and exosomes are among the newest therapeutic advances in OA treatment, and this review reveals how they can be used to mitigate destructive neutrophil activity.

DNA methylation and noncoding RNA in OA: Recent findings and methodological advances

Introduction:

Osteoarthritis (OA) is a chronic musculoskeletal disease characterized by progressive loss of joint function. Historically, it has been characterized as a disease caused by mechanical trauma, so-called ‘wear and tear’. Over the past two decades, it has come to be understood as a complex systemic disorder involving gene-environmental interactions. Epigenetic changes have been increasingly implicated. Recent improvements in microarray and next-generation sequencing (NGS) technologies have allowed for ever more complex evaluations of epigenetic aberrations associated with the development and progression of OA.

Methods:

A systematic review was conducted in the Pubmed database. We curated studies that presented the results of DNA methylation and noncoding RNA research in human OA and OA animal models since 1985.

Results:

Herein, we discuss recent findings and methodological advancements in OA epigenetics, including a discussion of DNA methylation, including microarray and NGS studies, and noncoding RNAs. Beyond cartilage, we also highlight studies in subchondral bone and peripheral blood mononuclear cells, which highlight widespread and potentially clinically important alterations in epigenetic patterns seen in OA patients. Finally, we discuss epigenetic editing approaches in the context of OA.

Conclusions:

Although a substantial body of literature has already been published in OA, much is still unknown. Future OA epigenetics studies will no doubt continue to broaden our understanding of underlying pathophysiology and perhaps offer novel diagnostics and/or treatments for human OA.

miR9 inhibits 6-mer HA-induced cytokine production and apoptosis in human chondrocytes by reducing NF-kB activation

The present study aimed to investigate the expression of miR9 and its correlation with cytokines, proteolytic enzymes and apoptosis in an experimental model of 6-mer HA induced inflammation in human chondrocytes. Human articular chondrocytes, transfected with a miR-9 mimic and miR-9 inhibitor, were stimulated with 6-mer HA in presence/absence of a specific NF-kB inhibitor. 6-mer HA induced a significant increase of TLR-4, CD44, IL-8, IL-18, MMP-9, ADAMTS-5, BAX and BCL-2 mRNAs expression and the related proteins, as well as NF-kB activation, associated with a significant up regulation of miR-9. In chondrocytes transfected with the miR-9 mimic before 6-mer HA treatment we found a decrease of such inflammatory cytokines, metalloproteases and pro-apoptotic molecules, while we found them increased in chondrocytes transfected with the miR9 inhibitor before 6-mer HA stimulation. The activities of TLR-4 and CD44, up regulated by 6-mer HA, were not modified by miR9 mimic/inhibitor, while the NF-kB activation was significantly affected. We suggested that the up regulation of miR9, induced by 6-mer HA, could be a cellular attempt to limit cell damage during inflammation.

An updated view on Temporomandibular Joint degeneration: insights from the cell subsets of mandibular condylar cartilage

The high prevalence of temporomandibular joint osteoarthritis (TMJOA), which causes joint dysfunction, indicates the need for more effective methods for treatment and repair. Mandibular condylar cartilage (MCC), a typical fibrocartilage that experiences degenerative changes during the development of TMJOA, has become a research focus and therapeutic target in recent years. MCC is composed of four zones of cells at various stages of differentiation. The cell subsets in MCC exhibit different physiological and pathological characteristics during development and in TMJOA. Most studies of TMJOA are mainly concerned with gene regulation of pathological changes. The corresponding treatment targets with specific cell subsets in MCC may provide more accurate and reliable results for cartilage repair and TMJOA treatment. In this review, we summarized the current research progress on the cell subsets of MCC from the perspective of MCC development and degeneration. We hope to provide a reference for further exploration of the pathological process of TMJOA and improvement of TMJOA treatment.

Disease-modifying therapeutic strategies in osteoarthritis: current status and future directions

Osteoarthritis (OA) is the most common form of arthritis. It is characterized by progressive destruction of articular cartilage and the development of chronic pain and constitutes a considerable socioeconomic burden. Currently, pharmacological treatments mostly aim to relieve the OA symptoms associated with inflammation and pain. However, with increasing understanding of OA pathology, several potential therapeutic targets have been identified, enabling the development of disease-modifying OA drugs (DMOADs). By targeting inflammatory cytokines, matrix-degrading enzymes, the Wnt pathway, and OA-associated pain, DMOADs successfully modulate the degenerative changes in osteoarthritic cartilage. Moreover, regenerative approaches aim to counterbalance the loss of cartilage matrix by stimulating chondrogenesis in endogenous stem cells and matrix anabolism in chondrocytes. Emerging strategies include the development of senolytic drugs or RNA therapeutics to eliminate the cellular or molecular sources of factors driving OA. This review describes the current developmental status of DMOADs and the corresponding results from preclinical and clinical trials and discusses the potential of emerging therapeutic approaches to treat OA.

Platelet-rich plasma treatment alleviates osteoarthritis-related pain, inflammation, and apoptosis by upregulating the expression levels of microRNA-375 and microRNA-337

OBJECTIVE

The present study was designed to determine the molecular mechanism by which platelet-rich plasma (PRP) acts on Osteoarthritis (OA) -related pain, inflammation, and apoptosis in vivo and in vitro.

MATERIALS AND METHODS

An in vivo OA model was established in rats using anterior cruciate ligament transection, and an in vitro OA model was created by treating chondrocytes with IL-1β. Then, the induced rats and chondrocytes were treated with PRP. Real-time PCR were used to examine the expression of micorRNAs (miRs) and mRNAs of inflammatory cytokines. WB were performed to detect the expression of apoptotic factors and Wnt/β-catenin signals. Structural damage of the cartilage and pain in OA rats were analyzed and represented by Mankin Score, OARSIS score, Tender threshold, and Thermal pain threshold. CCK-8 assay and flow cytometry were used to determine cell viability and apoptosis.

RESULTS

The expression levels of miR-337 and miR-375 were downregulated in the in vivo and vitro OA models; however, PRP treatment elevated their levels. miR-337 and miR-375 inhibition reversed the effects of PRP of reducing tenderness and thermal pain thresholds in OA rats. Moreover, PRP decreased the mRNA expression levels of MMP-13, Bax, and inflammatory factors, such as IL-1β, IL-18, and TNF-α, as well as increased the expression levels of collagen II and antiapoptotic Bcl-2. The decrease in inflammation and apoptosis was reversed by miR-337 and miR-375 inhibition, respectively.

DISCUSSION AND CONCLUSIONS

In conclusion, miR-337 and miR-375 are involved in PRP-delayed OA progression by affecting inflammation and apoptosis.

Role of microRNA Shuttled in Small Extracellular Vesicles Derived From Mesenchymal Stem/Stromal Cells for Osteoarticular Disease Treatment

Osteoarticular diseases (OD), such as rheumatoid arthritis (RA) and osteoarthritis (OA) are chronic autoimmune/inflammatory and age-related diseases that affect the joints and other organs for which the current therapies are not effective. Cell therapy using mesenchymal stem/stromal cells (MSCs) is an alternative treatment due to their immunomodulatory and tissue differentiation capacity. Several experimental studies in numerous diseases have demonstrated the MSCs’ therapeutic effects. However, MSCs have shown heterogeneity, instability of stemness and differentiation capacities, limited homing ability, and various adverse responses such as abnormal differentiation and tumor formation. Recently, acellular therapy based on MSC secreted factors has raised the attention of several studies. It has been shown that molecules embedded in extracellular vesicles (EVs) derived from MSCs, particularly those from the small fraction enriched in exosomes (sEVs), effectively mimic their impact in target cells. The biological effects of sEVs critically depend on their cargo, where sEVs-embedded microRNAs (miRNAs) are particularly relevant due to their crucial role in gene expression regulation. Therefore, in this review, we will focus on the effect of sEVs derived from MSCs and their miRNA cargo on target cells associated with the pathology of RA and OA and their potential therapeutic impact.

Novel NFκB Inhibitor SC75741 Mitigates Chondrocyte Degradation and Prevents Activated Fibroblast Transformation by Modulating miR-21/GDF-5/SOX5 Signaling

Osteoarthritis (OA) is a common articular disease manifested by the destruction of cartilage and compromised chondrogenesis in the aging population, with chronic inflammation of synovium, which drives OA progression. Importantly, the activated synovial fibroblast (AF) within the synovium facilitates OA through modulating key molecules, including regulatory microRNAs (miR's). To understand OA associated pathways, in vitro co-culture system, and in vivo papain-induced OA model were applied for this study. The expression of key inflammatory markers both in tissue and blood plasma were examined by qRT-PCR, western blot, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays. Herein, our result demonstrated, AF-activated human chondrocytes (AC) exhibit elevated NFκB, TNF-α, IL-6, and miR-21 expression as compared to healthy chondrocytes (HC). Importantly, AC induced the apoptosis of HC and inhibited the expression of chondrogenesis inducers, SOX5, TGF-β1, and GDF-5. NFκB is a key inflammatory transcription factor elevated in OA. Therefore, SC75741 (an NFκB inhibitor) therapeutic effect was explored. SC75741 inhibits inflammatory profile, protects AC-educated HC from apoptosis, and inhibits miR-21 expression, which results in the induced expression of GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1. Moreover, ectopic miR-21 expression in fibroblast-like activated chondrocytes promoted osteoblast-mediated differentiation of osteoclasts in RW264.7 cells. Interestingly, in vivo study demonstrated SC75741 protective role, in controlling the destruction of the articular joint, through NFκB, TNF-α, IL-6, and miR-21 inhibition, and inducing GDF-5, SOX5, TGF-β1, BMPR2, and COL4A1 expression. Our study demonstrated the role of NFκB/miR-21 axis in OA progression, and SC75741's therapeutic potential as a small-molecule inhibitor of miR-21/NFκB-driven OA progression.

Small Noncoding RNAs in Knee Osteoarthritis: The Role of MicroRNAs and tRNA-Derived Fragments

Knee osteoarthritis (OA) is a degenerative knee joint disease that results from the breakdown of joint cartilage and underlying bone, affecting about 3.3% of the world's population. As OA is a multifactorial disease, the underlying pathological process is closely associated with genetic changes in articular cartilage and bone. Many studies have focused on the role of small noncoding RNAs in OA and identified numbers of microRNAs that play important roles in regulating bone and cartilage homeostasis. The connection between other types of small noncoding RNAs, especially tRNA-derived fragments and knee osteoarthritis is still elusive. The observation that there is limited information about small RNAs different than miRNAs in knee OA was very surprising to us, especially given the fact that tRNA fragments are known to participate in a plethora of human diseases and a portion of them are even more abundant than miRNAs. Inspired by these findings, in this review we have summarized the possible involvement of microRNAs and tRNA-derived fragments in the pathology of knee osteoarthritis.

miR-9 alleviated the inflammatory response and apoptosis in caerulein-induced acute pancreatitis by regulating FGF10 and the NF-κB signaling pathway

MicroRNAs (miRs) have been implicated in the development of acute pancreatitis (AP). However, the role and potential mechanism of miR-9 in AP progression remains unclear. Caerulein-treated AR42J cells were used as a cellular model of AP. Results revealed caerulein triggered an inflammatory response by promoting the secretion of inflammatory cytokines [tumor necrosis factor-α, interleukin (IL) 1β and IL-6], as evidenced by ELISA. Furthermore, caerulein-induced apoptosis was reported by flow cytometry and western blot assays. Additionally, miR-9 expression was downregulated by caerulein treatment, as demonstrated by reverse transcription quantitative PCR. However, miR-9 overexpression reduced the inflammatory response and apoptosis in caerulein-treated AR42J cells. miR-9 knockdown resulted in opposite effects. Furthermore, fibroblast growth factor (FGF) 10 was validated to be targeted via miR-9 by luciferase, RNA immunoprecipitation and RNA pull-down assays. Results demonstrated increased FGF10 expression in caerulein-treated AR42J cells and that FGF10 overexpression exacerbated the caerulein-induced inflammatory response and apoptosis, while its knockdown had the opposite effect. Additionally, FGF10 reversed the effect of miR-9 on caerulein-induced injury in AR42J cells. Results demonstrated that miR-9 inhibited the expression of the nuclear factor κB (NF-κB) pathway-related proteins by downregulating FGF10. As a result, miR-9 decreased inflammatory response and apoptosis in caerulein-treated AR42J cells by targeting FGF10 and blocking NF-κB signaling, suggesting that miR-9 may serve as a novel target for AP treatment.

Pinocembrin Reduces Arthritic Symptoms in Mouse Model via Targeting Sox4 Signaling Molecules

Rheumatoid arthritis (RA) is a chronic autoimmune, multifactorial, inflammatory disorder characterized by hyperplasia and infiltration of inflammatory cells at the synovial lining leading to destruction of cartilage and bone tissues. Pinocembrin (PCB) is a natural flavonoid extracted as a pure molecule from honey, propolis, and some plants. In this study, we evaluated the antiarthritic effect of PCB in adjuvant induced arthritis (AIA) mice. Treating the AIA mouse model with PCB reduced the arthritis symptoms/score, including edema size, extent of hind paw redness, abnormal movement, and holding inability. At the pathological level, PCB significantly decreased the joint erosion and percentages of infiltrated inflammatory cells. Biochemically, PCB interacts with the transcription factor, SRY-related HMG-box 4 (Sox4), and then modulates its dysregulated expression and the expression of Sox4/Stat3 signaling molecules in AIA mice. These molecules include tumor necrosis factor-α, nuclear transcription factor kappaB, and cyclooxygenase-2, besides the microRNAs; miR-132, miR-202-5p, and miR-7235, which are dysregulated in adjuvant-induced arthritis model relative to the control mice. The possible PCB interaction with Sox4 transcriptional protein was confirmed through molecular docking where three hydrogen bonds were formed at ARG and LYS residues at a stable binding energy of -4.72. Taken together, our data demonstrate that PCB could serve as a therapeutic drug in treatment of RA.

The Effect and Possible Mechanism of Intradiscal Injection of Simvastatin in the Treatment of Discogenic Pain in Rats

To study the effect of intradiscal injection of simvastatin on discogenic pain in rats and its possible mechanism, 30 adult female rats were used in this experiment. Twenty rats were randomly divided into sham operation group (Control group), intervertebral disk degeneration group (DDD group), intervertebral disk degeneration + hydrogel group (DDD + GEL group), and intervertebral disk degeneration + simvastatin group (DDD + SIM group). The mechanical pain threshold and cold sensation in rats were measured. The contents of NF-kappa B1, RelA, GAP43, SP, CGRP, TRPM 8, IL-1β, and TNF-α in the intervertebral disk (IVD), the corresponding contents of dorsal root ganglion (DRG) and plantar skin GAP43 and TRPM 8 were quantitatively detected by PCR. The corresponding IVDs were stained to detect their degeneration. There was no significant difference in the mechanical pain threshold between the groups at each time point. From the first day to the 8th week after surgery, the cold-sensing response of the DDD group was significantly higher than that of the Control group (P < 0.05). At 7 and 8 weeks postoperatively, the cold-sensing response of the DDD + SIM group was significantly lower than that of the DDD + GEL group (P < 0.05). The levels of NF-κB1, RelA, GAP43, SP, CGRP, TRPM8, IL-1β, and TNF-α in the IVD of DDD + SIM group were significantly lower than those in DDD group (P < 0.05). The content of GAP43 and TRPM8 in rat plantar skin decreased significantly and TRPM8 in DRG decreased significantly (P < 0.05).

Overview of MMP-13 as a Promising Target for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common degenerative disease characterized by the destruction of articular cartilage and chronic inflammation of surrounding tissues. Matrix metalloproteinase-13 (MMP-13) is the primary MMP involved in cartilage degradation through its particular ability to cleave type II collagen. Hence, it is an attractive target for the treatment of OA. However, the detailed molecular mechanisms of OA initiation and progression remain elusive, and, currently, there are no interventions available to restore degraded cartilage. This review fully illustrates the involvement of MMP-13 in the initiation and progression of OA through the regulation of MMP-13 activity at the molecular and epigenetic levels, as well as the strategies that have been employed against MMP-13. The aim of this review is to identify MMP-13 as an attractive target for inhibitor development in the treatment of OA.

Mangiferin attenuates IL1βinduced chondrocytes apoptosis

OBJECTIVES

Chondrocyte apoptosis is an important process in the pathogenesis of osteoarthritis. Mangiferin exerts multiple pharmacological effects such as anti-inflammatory and anti-apoptosis. However, the role of mangiferin in chondrocyte apoptosis is not clear. In this study, we aimed to explore the role of mangiferin in IL-1β-induced chondrocyte apoptosis.

METHODS

ATDC5 cells were randomly divided into a control group, a IL-1β group, a MFN-L group, a MFN-M group, a MFN-H group and a MFN+LY294002 group. Cells in the control group were treated with IL-1β (10 ng/mL) for 24 h; cells in the MFN-L group, the MFN-M group and the MFN-H group were pretreated with 5, 10 and 20 μmol/L mangiferin for 1 h respectively, and then they were treated with IL-1β (10 ng/mL) for 24 h; cells in the MFN+LY294002 group were treated with LY294002 (25 μmol/L) for 1 h, then mangiferin (20 μmol/L) and IL-1β (10 ng/mL) for 1 h and 24 h, respectively. Cell viability was detected by CCK-8 assay and cell apoptosis was measured by flow cytometry. Colorimetric assay was conducted to measure the caspase-3 activity. The protein levels of Bcl-2, Bax, and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway related proteins were detected by Western blotting.

RESULTS

Compared to the control group, cell viability was significantly decreased; cell apoptosis, caspase-3 activity and Bax protein expression were significantly increased; the protein levels of Bcl-2, p-PI3K, and p-Akt were significantly decreased in the IL-1β group (all P<0.05). Compared to the IL-1β group, cell viability was significantly increased; cell apoptosis, caspase-3 activity and Bax protein expression were significantly decreased; the protein levels of Bcl-2, p-PI3K, and p-Akt were significantly increased in the MFN-L, the MFN-M and the MFN-H groups (all P<0.05). Compared to the MFN-M group, cell apoptosis and the protein level of Bax in the MFN+LY294002 group were significantly increased; the Bcl-2 protein expression was significantly decreased (all P<0.05).

CONCLUSIONS

Mangiferin could attenuate IL-1β-induced apoptosis of the mice chondrocytes, which is mediated by the activation of PI3K/Akt signaling pathway.

miR-107 affects cartilage matrix degradation in the pathogenesis of knee osteoarthritis by regulating caspase-1

Background

Knee osteoarthritis (KOA) seriously affects the quality of life of KOA patients. This study aimed to investigate whether miR-107 could regulate KOA through pyroptosis to affect collagen protein secreted by chondrocytes through IL-1β.

Methods

The proliferation of chondrocytes was detected by CCK-8 assay. RT-qPCR analysis was used to identify miR-107 expression and transfection effects. The expression of Col II, IL-1β, IL-18, and MMP13 in supernatant of chondrocytes or chondrocytes was detected by ELISA assay and western blot analysis. The pyroptosis of chondrocytes was analyzed by TUNEL assay and the expression of pyroptosis-related proteins was analyzed by western blot. Luciferase reporter assay confirmed the relation of miR-107 to caspase-1.

Results

The proliferation of chondrocytes was decreased after LPS induction and further decreased by treatment of ATP. Single LPS treatment for chondrocytes downregulated the Col II expression while upregulated the expression of IL-1β, IL-18, and MMP-13, which was further changed by ATP treatment. miR-107 expression was decreased in chondrocytes induced by LPS and further decreased in chondrocytes induced by LPS and ATP. In addition, miR-107 overexpression increased the proliferation and decreased the pyroptosis of chondrocytes induced by LPS and ATP. miR-107 overexpression upregulated the Col II expression while down-regulated the expression of IL-1β, IL-18, and MMP-13 in supernatant of chondrocytes or chondrocytes induced by LPS and ATP. miR-107 overexpression down-regulated the expression of caspase-1, c-caspase-1, GSDMD-N, and TLR4 in chondrocytes induced by LPS and ATP. Furthermore, miR-107 directly targeted caspase-1.

Conclusions

miR-107 can protect against KOA by downregulating caspase-1 to decrease pyroptosis, thereby promoting collagen protein secreted by chondrocytes by down-regulating IL-1β.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Current Nanoparticle-Based Technologies for Osteoarthritis Therapy

Osteoarthritis (OA) is a common chronic joint disease that is characterized by joint pain and stiffness, and limitation of motion and the major cause of disability, which reduces life quality of patients and brings a large economic burden to the family and society. Current clinical treatment is mostly limited to symptomatic treatment aimed at pain alleviation and functional improvement, rather than suppressing the progression of OA. Nanotechnology is a promising strategy for the treatment of OA. In this review, we summarize the current experimental progress that focuses on technologies such as liposomes, micelles, dendrimers, polymeric nanoparticles (PNPs), exosomes, and inorganic nanoparticles (NPs) for their potential treatment of OA.

Tumor progression locus 2 (TPL2) in tumor-promoting Inflammation, Tumorigenesis and Tumor Immunity

Over the years, tumor progression locus 2 (TPL2) has been identified as an essential modulator of immune responses that conveys inflammatory signals to downstream effectors, subsequently modulating the generation and function of inflammatory cells. TPL2 is also differentially expressed and activated in several cancers, where it is associated with increased inflammation, malignant transformation, angiogenesis, metastasis, poor prognosis and therapy resistance. However, the relationship between TPL2-driven inflammation, tumorigenesis and tumor immunity has not been addressed. Here, we reconcile the function of TPL2-driven inflammation to oncogenic functions such as inflammation, proliferation, apoptosis resistance, angiogenesis, metastasis, immunosuppression and immune evasion. We also address the controversies reported on TPL2 function in tumor-promoting inflammation and tumorigenesis, and highlight the potential role of the TPL2 adaptor function in regulating the mechanisms leading to pro-tumorigenic inflammation and tumor progression. We discuss the therapeutic implications and limitations of targeting TPL2 for cancer treatment. The ideas presented here provide some new insight into cancer pathophysiology that might contribute to the development of more integrative and specific anti-inflammatory and anti-cancer therapeutics.

Adult mouse hippocampal transcriptome changes associated with long-term behavioral and metabolic effects of gestational air pollution toxicity

Gestational exposure to air pollution increases the risk of autism spectrum disorder and cognitive impairments with unresolved molecular mechanisms. This study exposed C57BL/6J mice throughout gestation to urban-derived nanosized particulate matter (nPM). Young adult male and female offspring were studied for behavioral and metabolic changes using forced swim test, fat gain, glucose tolerance, and hippocampal transcriptome. Gestational nPM exposure caused increased depressive behaviors, decreased neurogenesis in the dentate gyrus, and increased glucose tolerance in adult male offspring. Both sexes gained fat and body weight. Gestational nPM exposure induced 29 differentially expressed genes (DEGs) in adult hippocampus related to cytokine production, IL17a signaling, and dopamine degradation in both sexes. Stratification by sex showed twofold more DEGs in males than females (69 vs 37), as well as male-specific enrichment of DEGs mediating serotonin signaling, endocytosis, Gαi, and cAMP signaling. Gene co-expression analysis (WCGNA) identified a module of 43 genes with divergent responses to nPM between the sexes. Chronic changes in 14 DEGs (e.g., microRNA9-1) were associated with depressive behaviors, adiposity and glucose intolerance. These genes enriched neuroimmune pathways such as HMGB1 and TLR4. Based on cerebral cortex transcriptome data of neonates, we traced the initial nPM responses of HMGB1 pathway. In vitro, mixed glia responded to 24 h nPM with lower HMGB1 protein and increased proinflammatory cytokines. This response was ameliorated by TLR4 knockdown. In sum, we identified transcriptional changes that could be associated with air pollution-mediated behavioral and phenotypic changes. These identified genes merit further mechanistic studies for therapeutic intervention development.

Therapeutic effect of Resveratrol in the treatment of osteoarthritis via the MALAT1/miR-9/NF-κB signaling pathway

The aim of the current study was to explore the role of Resveratrol (Res) in osteoarthritis (OA) and its underlying mechanism. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to determine the relative expression levels of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), microRNA-9 (miR-9), nuclear factor kappa B subunit 1 (NF-κB1), interleukin (IL)-6, matrix metallopeptidase 13 (MMP-13) and caspase-3 in vitro and in the in vivo model of OA, as well as examining the effect of Res on MALAT1, miR-9 and NF-κB1, IL-6, MMP-13 and caspase-3 expression levels. Immunohistochemical analysis was performed to examine NF-κB1 and MMP-13 protein levels in the in vivo model of OA. Dual-luciferase reporter assays were used to confirm the regulatory relationship between miR-9 and MALAT1 and NF-κB1, as well as examining the effect of Res on the transcriptional activation of MALAT1 promoter. Furthermore, the effect of Res on cell proliferation in vitro was examined by MTT assay. The relative mRNA expression levels of MALAT1 and NF-κB1 were significantly increased, while miR-9 expression was significantly decreased in the OA group compared with the sham group. Treatment with Res partially reversed the effects of OA on MALAT1, NF-κB1 and miR-9 expression. Similarly, the relative protein expression levels of NF-κB1, IL-6, MMP-13 and caspase-3 were significantly increased in the OA group compared with the sham group; however, treatment with Res partially reversed the effects of OA on the protein expression levels of NF-κB1, IL-6, MMP-13 and caspase-3. MALAT1 and NF-κB1 were identified as potential target genes of miR-9, and dual-luciferase assays were used to examine the effect of miR-9 on the luciferase activity of 3'UTR MALAT1 and NF-κB1. Treatment with Res suppressed the transcriptional activation of the MALAT1 promoter, thereby inhibiting MALAT1 expression. Additionally, the relative expression level of miR-9 significantly increased following treatment with Res in a dose-dependent manner, while the relative protein expression levels of NF-κB1, IL-6, MMP-13 and caspase-3 significantly decreased following treatment with Res compared with the control. Furthermore, treatment with Res significantly increased the growth rate of chondrocytes in a dose-dependent manner compared with the control. Taken together, these results suggest that direct targeting of the MALAT1/miR-9/NF-κB1/IL-6, MMP-13/caspase-3 axis may be a novel therapeutic strategy for the treatment of OA.

MicroRNA-9 ameliorates destructive arthritis through down-regulation of NF-κB1-RANKL pathway in fibroblast-like synoviocytes

We investigated the effect of miR-9 on fibroblast-like synoviocytes (FLS) from RA patients and animal arthritis model. The binding of miR-9 to NF-κB1 3'UTR was analyzed by luciferase reporter assay and immunoprecipitation. ChIP assay and luciferase promoter assay were performed to identify the binding of NF-κB1 to RANKL promoter and its activity. FLS were treated with miR-9/anti-miR-9 to evaluate cell proliferation and the expression of RANKL. Therapeutic effect of intra-articular miR-9 was evaluated in type-II collagen-induced arthritis in rats. miR-9 bound to the 3'-UTR of NF-κB1 and downregulated NF-κB1. NF-κB1 bound to RANKL promoter and increased the promoter activity of RANKL. RANKL was downregulated by miR-9. Proliferation of FLS was increased by miR-9 inhibitor. miR-9 dampened experimental arthritis by lowering inflammatory state, reducing RANKL and osteoclasts formation. Our findings revealed miR-9-NF-κB1-RANKL pathway in RA-FLS, further, miR-9 ameliorated inflammatory arthritis in vivo which propose therapeutic implications of miR- 9 in RA.

STAT3 speeds up progression of osteoarthritis through NF-κB signaling pathway

Osteoarthritis (OA) is the most common motor system disease in the elderly, with a high incidence and a huge social and economic burden. Therefore, it is urgent to study its potential pathogenesis to improve the therapeutic effect of the disease. In this study, we constructed a number of regulator-mediated OA dysfunction modules, and carried out in-depth analysis in order to examine the disease development process. Differential expression analysis, co-expression analysis and enrichment analysis were combined to screen genes related to disease progression. Subsequently, key regulatory factors in the process of OA were identified based on the pivotal regulators that may manipulate important parts of the module subnetwork. A total of 16 OA dysfunction modules were obtained, involving the aggregation of 3,239 module genes. Then, enrichment analysis showed that module genes were significantly involved in apoptosis, inflammation-related functions and signaling pathways. Finally, we revealed a series of regulators, including 842 ncRNA (miR-132-3p, miR-130a-3p and miR-590-3p), 59 transcription factors (NFKB1, RELA and STAT3). We consider that STAT3 is the core transcription factor and promotes the development of OA through the signal of NF-κB. Overall, our results provide biologists and pharmacists with a new way of thinking to reveal the disease process of OA, and provide a wider range of candidate targets for follow-up research.

MiR-27a promotes the autophagy and apoptosis of IL-1β treated-articular chondrocytes in osteoarthritis through PI3K/AKT/mTOR signaling

Osteoarthritis (OA) is a common degenerative joint disorder, which involves articular cartilage degeneration as well as joint inflammatory reactions. The recent studies have identified microRNA (miRNA) as one of the epigenetic mechanisms for the regulation of gene expression. Here we aim to reveal the role of miRNA in the regulation of gene expression in articular chondrocytes and its significance in the OA pathogenesis. In the present study, miRNA profiling was performed using OA cartilage and normal healthy cartilage tissues. As compared to their levels in normal cells and tissues, miR-27a expression was found to be upregulated in OA cartilage and IL-1β-treated articular chondrocytes. TUNEL staining, as well as flow cytometry with Annexin V-FITC/PI double labeling indicated that miR-27a inhibition reduced the apoptosis of IL-1β-treated articular chondrocytes. Bioinformatics prediction and the dual-luciferase reporter assay indicated that miR-27a targeted the 3'-UTR of the PI3K gene to silence it. The PI3K mRNA level in OA cartilage and IL-1β-treated articular chondrocytes was also downregulated, comparing with normal cells and tissues. Transfection of chondrocytes transfected with the miR-27a inhibitor upregulated the PI3K expression. This study demonstrated miR-27a is a regulator of the PI3K-Akt-mTOR axis in human chondrocytes and could participate in OA pathogenesis.

The protective role of microRNA-140-5p in synovial injury of rats with knee osteoarthritis via inactivating the TLR4/Myd88/NF-κB signaling pathway

Objective: Recently, many studies have revealed the effect of microRNAs (miRNAs) in knee osteoarthritis (KOA). This study aims to explore the role of miR-140-5p in protective effects and mechanisms of synovial injury of rats with KOA via regulating the TLR4/Myd88/NF-κB signaling pathway.

Methods: The models of KOA Wistar rats were established by operation of anterior cruciate ligament transection. Rats were injected with agomir NC or miR-140-5p agomir. MiR-140-5p expression in KOA synovial tissues and synoviocytes was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The synoviocytes were transfected with mimics NC sequence and miR-140-5p mimics sequence. The expression of TLR4/Myd88/NF-κB signaling pathway-related proteins was measured by RT-qPCR and western blot analysis. The proliferation and apoptosis of synoviocytes in rats with KOA were evaluated by a string of experiments. The expression levels of inflammatory factors in KOA synovial tissues and synoviocytes were detected.

Results: MiR-140-5p was down-regulated in KOA synovial tissues and synoviocytes. Upregulation of miR-140-5p could inhibit the inflammation reaction and the apoptosis of synoviocytes as well as promote proliferation of synoviocytes of rats with KOA. Furthermore, upregulated miR-140-5p could inactivate the TLR4/Myd88/NF-κB signaling pathway in rats with KOA.

Conclusion: This study suggests that upregulated miR-140-5p could protect synovial injury by restraining inflammation reaction and apoptosis of synoviocytes in KOA rats via TLR4/Myd88/NF-κB signaling pathway inactivation.

NF-κB Signaling Pathways in Osteoarthritic Cartilage Destruction

Osteoarthritis (OA) is a type of joint disease associated with wear and tear, inflammation, and aging. Mechanical stress along with synovial inflammation promotes the degradation of the extracellular matrix in the cartilage, leading to the breakdown of joint cartilage. The nuclear factor-kappaB (NF-κB) transcription factor has long been recognized as a disease-contributing factor and, thus, has become a therapeutic target for OA. Because NF-κB is a versatile and multi-functional transcription factor involved in various biological processes, a comprehensive understanding of the functions or regulation of NF-κB in the OA pathology will aid in the development of targeted therapeutic strategies to protect the cartilage from OA damage and reduce the risk of potential side-effects. In this review, we discuss the roles of NF-κB in OA chondrocytes and related signaling pathways, including recent findings, to better understand pathological cartilage remodeling and provide potential therapeutic targets that can interfere with NF-κB signaling for OA treatment.

Hyaluronic Acid: Molecular Mechanisms and Therapeutic Trajectory

Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) content varies widely in different joints and species. HA is a non-sulfated, naturally occurring non-protein glycosaminoglycan (GAG), with distinct physico-chemical properties, produced by synoviocytes, fibroblasts, and chondrocytes. HA has an important role in the biomechanics of normal SF, where it is partially responsible for lubrication and viscoelasticity of the SF. The concentration of HA and its molecular weight (MW) decline as osteoarthritis (OA) progresses with aging. For that reason, HA has been used for more than four decades in the treatment of OA in dogs, horses and humans. HA produces anti-arthritic effects via multiple mechanisms involving receptors, enzymes and other metabolic pathways. HA is also used in the treatment of ophthalmic, dermal, burns, wound repair, and other health conditions. The MW of HA appears to play a critical role in the formulation of the products used in the treatment of diseases. This review provides a mechanism-based rationale for the use of HA in some disease conditions with special reference to OA.

Upregulation of microRNA-9-5p inhibits apoptosis of chondrocytes through downregulating Tnc in mice with osteoarthritis following tibial plateau fracture

Osteoarthritis (OA) is a common degenerative joint disease which is typically progressed with age, affecting smaller joints of hands, lower limbs, and the vertebral column. It has been reported that microRNAs could regulate the biological processes of OA. Therefore, the purpose of this study was to elucidate miR-9-5p's role in regulating cartilage remodeling of OA mice following tibial plateau fracture (TPF) through regulation of tenascin C (Tnc). Initially, we determined the expression of miR-9-5p and Tnc in mice with OA and then testified their relationship. The results displayed a high expression of Tnc, but a poor expression of miR-9-5p with high methylation in OA. Tnc was confirmed to be a target gene of miR-9-5p. Moreover, based on gain- and loss-function experiments, an increase of miR-9-5p and loss of Tnc had the potential to inhibit cell apoptosis, while facilitating cell proliferation, migration, invasion, and cartilage remodeling of mice with OA following TPF. This was further demonstrated by a higher expression of type II collagen, lower type X collagen, and protogenin expression. Subsequently, downregulation of miR-9-5p aggravated the pathological changes of mice, illustrated by an increase in the Mankin score. In conclusion, the present study proved that overexpression of miR-9-5p suppressed chondrocytes apoptosis and promoted cartilage remodeling through downregulating of Tnc in mice with OA.

Green tea polyphenols attenuate LPS-induced inflammation through upregulating microRNA-9 in murine chondrogenic ATDC5 cells

BACKGROUND

Osteoarthritis (OA), a universal chronic musculoskeletal disorder, is closely related to inflammation. More effective drugs for improving OA outcome are definitely needed. Herein, we attempted to verify the protective role of green tea polyphenols (GTP) after treatment with murine in ATDC5 cells to reveal the regulatory mechanism.

METHODS

ATDC5 cells were stimulated with lipopolysaccharide (LPS) to mimic an inflammatory response during OA. Cell activity, apoptosis, levels of relative proteins, and prophlogistic factors were tested via a Cell Counting Kit-8 experiment, a flow cytometry experiment, western blot, and RT-qPCR (ELISA and Western blot), separately. miR-9 level was detected by RT-qPCR and altered via miR-9 mimic and inhibitor transfection. We finally studied MAPK and NF-κB pathways in GTP-related modulations using western blot.

RESULTS

LPS caused inflammatory cell damage in ATDC5 cells, showing decreased cell activity, enhanced apoptosis, and increased levels of pro-inflammatory cytokines. GTP pretreatments could significantly attenuate LPS-induced alterations. In addition, LPS-induced miR-9 upregulation was further positively regulated in ATDC5 cells. The effects of GTP pretreatments in LPS-caused ATDC5 cells were enhanced via miR-9 upregulation, whereas they were reduced via miR-9 suppression. Finally, we found that GTP pretreatments could suppress the MAPK and NF-κB pathways through miR-9 regulation.

CONCLUSION

GTP pretreatments attenuated LPS-induced inflammatory response accompanied by the suppression of the MAPK and NF-κB pathways via positively regulating miR-9 in ATDC5 cells.

Inhibition of SIRT1 by microRNA-9, the key point in process of LPS-induced severe inflammation

Severe inflammation may lead to multiple organs dysfunction syndrome, which has a high mortality. MicroRNA is found participated in this process. In this study we developed a lipopolysaccharide-induced inflammation cell model on macrophages and a lipopolysaccharide-induced inflammation mouse model. It was found that during inflammation, microRNA-9 was increased, accompanied with the up-regulation of pro-inflammatory cytokines and anti-inflammatory cytokines. Down-regulation of microRNA-9 inhibited the up-regulation of inflammatory cytokines, promoted the up-regulation of anti-inflammatory cytokines and induced the remission of organ damage, showing a protective effect in inflammation. Bioinformatics analysis combined with luciferase reporter assay showed that SIRT1 was the target gene of microRNA-9. Transfection of microRNA-9 inhibitor could increase the level of SIRT1 and decrease the activation of NF-κB pathway in macrophages. Myeloid specific sirt1 knockout mice were included and we found that lack of SIRT1 in mice macrophages led to aggravated inflammation, cell apoptosis and organ injury, and eliminated the protective property of microRNA-9 inhibitor. In conclusion, we demonstrated that inhibition of microRNA-9 could alleviate inflammation through the up-regulation of SIRT1 and then suppressed the activation of NF-κB pathway. This is a meaningful explore about the specific mechanism of microRNA-9 in inflammation.

Aging, Melatonin, and the Pro- and Anti-Inflammatory Networks

Aging and various age-related diseases are associated with reductions in melatonin secretion, proinflammatory changes in the immune system, a deteriorating circadian system, and reductions in sirtuin-1 (SIRT1) activity. In non-tumor cells, several effects of melatonin are abolished by inhibiting SIRT1, indicating mediation by SIRT1. Melatonin is, in addition to its circadian and antioxidant roles, an immune stimulatory agent. However, it can act as either a pro- or anti-inflammatory regulator in a context-dependent way. Melatonin can stimulate the release of proinflammatory cytokines and other mediators, but also, under different conditions, it can suppress inflammation-promoting processes such as NO release, activation of cyclooxygenase-2, inflammasome NLRP3, gasdermin D, toll-like receptor-4 and mTOR signaling, and cytokine release by SASP (senescence-associated secretory phenotype), and amyloid-β toxicity. It also activates processes in an anti-inflammatory network, in which SIRT1 activation, upregulation of Nrf2 and downregulation of NF-κB, and release of the anti-inflammatory cytokines IL-4 and IL-10 are involved. A perhaps crucial action may be the promotion of macrophage or microglia polarization in favor of the anti-inflammatory phenotype M2. In addition, many factors of the pro- and anti-inflammatory networks are subject to regulation by microRNAs that either target mRNAs of the respective factors or upregulate them by targeting mRNAs of their inhibitor proteins.

Redox and NF-κB signaling in osteoarthritis

Human cells have to deal with the constant production of reactive oxygen species (ROS). Although ROS overproduction might be harmful to cell biology, there are plenty of data showing that moderate levels of ROS control gene expression by maintaining redox signaling. Osteoarthritis (OA) is the most common joint disorder with a multi-factorial etiology including overproduction of ROS. ROS overproduction in OA modifies intracellular signaling, chondrocyte life cycle, metabolism of cartilage matrix and contributes to synovial inflammation and dysfunction of the subchondral bone. In arthritic tissues, the NF-κB signaling pathway can be activated by pro-inflammatory cytokines, mechanical stress, and extracellular matrix degradation products. This activation results in regulation of expression of many cytokines, inflammatory mediators, transcription factors, and several matrix-degrading enzymes. Overall, NF-κB signaling affects cartilage matrix remodeling, chondrocyte apoptosis, synovial inflammation, and has indirect stimulatory effects on downstream regulators of terminal chondrocyte differentiation. Interaction between redox signaling and NF-κB transcription factors seems to play a distinctive role in OA pathogenesis.

NF-κB-Associated Pain-Related Neuropeptide Expression in Patients with Degenerative Disc Disease

The role of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) has been highlighted in mechanisms underlying inflammatory and neuropathic pain processes. The present study was designed to investigate whether NF-κB signaling is associated with pain-related neuropeptide expression in patients with chronic back pain related to degenerative disc disease (DDD). Intervertebral disc (IVD) tissues were collected from forty DDD patients undergoing disc replacement or fusion surgery, and from eighteen postmortem (PM) control subjects. RELA, NFKB1, CGRP, TAC1, TRPV1, and MMP-3 gene expression were analyzed by RT-qPCR, while NF-κB subunit RelA and NF-κB1⁻DNA binding in nuclear extracts and calcitonin gene related peptide (CGRP), substance P (SP), and transient receptor potential, subfamily V, member 1 (TRPV1) protein levels in cytosolic extracts of tissues were assessed by enzyme-linked immunosorbent assay (ELISA). An upregulated NF-κB1⁻DNA binding, and higher CGRP and TRPV1 protein levels were observed in DDD patients compared to PM controls. In DDD patients, NF-κB1⁻DNA binding was positively correlated with nuclear RelA levels. Moreover, NF-κB1⁻DNA binding was positively associated with TRPV1 and MMP-3 gene and SP and TRPV1 protein expression in DDD patients. Our results indicate that the expression of SP and TRPV1 in IVD tissues was associated with NF-κB activation. Moreover, NF-κB may be involved in the generation or maintenance of peripheral pain mechanisms by the regulation of pain-related neuropeptide expression in DDD patients.

Expression of miR-9 in the serum of patients with acute ischemic stroke and its effect on neuronal damage

BACKGROUND

This research was aimed to measure the expression of miR-9 in serum of acute ischemic stroke (AIS) patients and explore the role of miR-9 on OGD-induced neuronal damage.

METHODS

In the present study, we measured the expression of miR-9 in serum of 65 AIS patients by real-time quantitative PCR (RT-qPCR) and the effect of miR-9 on oxygen-glucose deprivation (OGD)-induced neuronal injury was detected by CCK-8 in vitro. Western blot was used to measure the expression of protein.

RESULTS

We found that the serum level of miR-9 in 65 AIS patients was significantly higher than that in control group (no-AIS), and was positively correlated with NIHSS score (r=0.627, P<0.001), infarct volume ((r=0.576, P<0.001), serum IL-8 (r=0.376, P=0.002), TNF-α (r=0.418, P<0.001), IL-6 (r=0.545, P<0.001), and IL-1β (r=0.592, P<0.001). miR-9 expression levels were upregulated in cultured neurons with OGD treatment. The downregulation of miR-9 significantly alleviated OGD-induced neuronal injury. Dual-luciferase reporter assay demonstrated that SIRT1 was a target gene of miR-9, and miR-9 negatively regulated SIRT 1 expression and positively regulated p65 expression.

CONCLUSIONS

All in all, our data showed that downregulation of miR-9 protected neurons against OGD/R-induced injury by the SIRT1-mediated NF-kB pathway.

The complex landscape of microRNAs in articular cartilage: biology, pathology, and therapeutic targets

The disabling degenerative disease osteoarthritis (OA) is prevalent among the global population. Articular cartilage degeneration is a central feature of OA; therefore, a better understanding of the mechanisms that maintain cartilage homeostasis is vital for developing effective therapeutic interventions. MicroRNAs (miRs) modulate cell signaling pathways and various processes in articular cartilage via posttranscriptional repression of target genes. As dysregulated miRs frequently alter the homeostasis of articular cartilage, modulating select miRs presents a potential therapeutic opportunity for OA. Here, we review key miRs that have been shown to modulate cartilage-protective or -destructive mechanisms and signaling pathways. Additionally, we use an integrative computational biology approach to provide insight into predicted miR gene targets that may contribute to OA pathogenesis, and highlight the complexity of miR signaling in OA by generating both unique and overlapping gene targets of miRs that mediate protective or destructive effects. Early OA detection would enable effective prevention; thus, miRs are being explored as diagnostic biomarkers. We discuss these ongoing efforts and the applicability of miR mimics and antisense inhibitors as potential OA therapeutics.

Activation of NF-κB in Synovium versus Cartilage from Patients with Advanced Knee Osteoarthritis: A Potential Contributor to Inflammatory Aspects of Disease Progression

The aim was to assess the activation and association of the NF-κB system across synovial membrane (SM) and articular cartilage (AC) in patients with knee osteoarthritis (OA) and ascertain its potential effects on catabolic mediator expression in advanced OA. SM and AC were obtained from 40 OA patients undergoing total knee arthroplasty and from 19 postmortem control subjects. NF-κB subunit RelA in nuclear and cytosolic fractions and NF-κB1-DNA binding in nuclear extracts was assessed by ELISA, whereas NFKB1, RELA, IL-8, IL-6, and MMP3 gene expression were analyzed by reverse transcriptase-quantitative PCR in tissues. We observed higher SM nuclear RelA protein levels and upregulated NF-κB1-DNA binding in OA patients compared with postmortem controls. However, in AC, lower nuclear RelA levels were observed compared with cytosolic extracts in patients. Nuclear RelA levels correlated positively with NF-κB1-DNA binding in SM and AC in patients. SM RELA and MMP3 mRNA levels were upregulated, whereas IL-8 and IL-6 as well as AC RELA were downregulated in patients compared with controls. In SM, nuclear RelA levels correlated positively with MMP3 gene expression in patients. A negative correlation was observed between SM nuclear RelA levels and AC NF-κB1-DNA binding, and SM nuclear NF-κB1-DNA binding correlated negatively with AC MMP3 and NFKB1 mRNA levels in patients. These findings highlight NF-κB-triggered cross-talk and feedback mechanisms between SM and AC in OA. Further, our findings strongly support a role for an activated NF-κB system in the transcriptional mechanism of inflammatory processes, especially in SM of patients with advanced OA.

Plasma miR-136 can be used to screen patients with knee osteoarthritis from healthy controls by targeting IL-17

The current study mainly evaluated the plasma level of microRNA (miR)-136 in knee osteoarthritis (KOA) patients and determined if miR-136 could be used as a potential biomarker to screen KOA patients from healthy controls. It was demonstrated that plasma miR-136 was significantly decreased in the plasma of KOA patients. Moreover, the reduction in plasma miR-136 negatively correlated with the severity of KOA. Additionally, the increase in the serum interleukin (IL)-17 level positively correlated with the severity of KOA. More importantly, dual luciferase assays and western blot assays indicated that IL-17 was a target gene of miR-136. Further analysis showed that plasma miR-136 could be used as a biomarker to screen KOA patients from healthy controls. In summary, for the first time, the present study revealed that through targeting IL-17, decreased plasma miR-136 levels could be used as a potential biomarker to screen KOA patients from healthy controls.

Differential miRNAomics of the synovial membrane in knee osteoarthritis induced by bilateral anterior cruciate ligament transection in rats

The differential microRNA (miRNA) omics of the synovial membrane were investigated using a rat model of knee osteoarthritis (KOA) induced by bilateral anterior cruciate ligament transection, which produced pathological biomarkers in KOA. Sprague‑Dawley rats were randomly divided into two groups; Sham‑operated and KOA‑operated group. The KOA rats were subjected to bilateral anterior cruciate ligament transection. After 6 weeks, total RNA was extracted from the knee joint synovial membrane of the rats and a microRNA (miR) microarray was performed to identify differentially expressed miRs. Subsequently, the obtained differentially expressed miRs were validated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis. A total of 24 miRs were identified with alterations ≥1.5‑fold in the synovial membrane in the KOA‑operated group compared with the sham‑operated group, of which 4 miRs (miR‑532‑5p, ‑200b‑5p, ‑377‑3p and ‑759‑5p) were decreased and 20 miRs (miR‑382‑3p, ‑223‑3p, ‑100‑5p, ‑30d‑5p, ‑183‑5p, ‑130, ‑92b‑3p, ‑125b‑3p, ‑151‑3p, ‑155‑3p, 27a‑3p, ‑146b‑3p, ‑885‑5p, ‑352, ‑184, ‑345‑5p, ‑30a‑5p and ‑9a‑5p) were increased. Subsequently, RT‑qPCR was used to validate the expressions of miR‑223, ‑100, ‑345, ‑130, ‑382, ‑377, ‑352, ‑200b, ‑9a and ‑183, which were upregulated by a fold change of ≥1.5 in synovial membranes of KOA rats compared with shams. Furthermore, in vitro miR‑223 mimic could suppress the luciferase activity of NACHT, LRR and PYD domains‑containing protein 3 (NLRP3) 3' untranslated region by detecting of dual luciferase reporter vector. Additionally, the expression of NLRP3, interleukin (IL)‑1β and IL‑18 significantly increased in the synovial membrane of KOA rats. A total of 24 different miRs were determined by comparing the miRNAomics in the synovial membrane of the KOA model rats. Furthermore, the miR‑233‑regulated NLRP3 inflammasome was implicated in synovial membrane injury, which may be an important mechanism of KOA pathogenesis.

Onset and Progression of Human Osteoarthritis-Can Growth Factors, Inflammatory Cytokines, or Differential miRNA Expression Concomitantly Induce Proliferation, ECM Degradation, and Inflammation in Articular Cartilage?

Osteoarthritis (OA) is a degenerative whole joint disease, for which no preventative or therapeutic biological interventions are available. This is likely due to the fact that OA pathogenesis includes several signaling pathways, whose interactions remain unclear, especially at disease onset. Early OA is characterized by three key events: a rarely considered early phase of proliferation of cartilage-resident cells, in contrast to well-established increased synthesis, and degradation of extracellular matrix components and inflammation, associated with OA progression. We focused on the question, which of these key events are regulated by growth factors, inflammatory cytokines, and/or miRNA abundance. Collectively, we elucidated a specific sequence of the OA key events that are described best as a very early phase of proliferation of human articular cartilage (AC) cells and concomitant anabolic/catabolic effects that are accompanied by incipient pro-inflammatory effects. Many of the reviewed factors appeared able to induce one or two key events. Only one factor, fibroblast growth factor 2 (FGF2), is capable of concomitantly inducing all key events. Moreover, AC cell proliferation cannot be induced and, in fact, is suppressed by inflammatory signaling, suggesting that inflammatory signaling cannot be the sole inductor of all early OA key events, especially at disease onset.