D-mannose alleviates intervertebral disc degeneration through glutamine metabolism.

BACKGROUND: Intervertebral disc degeneration (IVDD) is a multifaceted condition characterized by heterogeneity, wherein the balance between catabolism and anabolism in the extracellular matrix of nucleus pulposus (NP) cells plays a central role. Presently, the available treatments primarily focus on relieving symptoms associated with IVDD without offering an effective cure targeting its underlying pathophysiological processes. D-mannose (referred to as mannose) has demonstrated anti-catabolic properties in various diseases. Nevertheless, its therapeutic potential in IVDD has yet to be explored. METHODS: The study began with optimizing the mannose concentration for restoring NP cells. Transcriptomic analyses were employed to identify the mediators influenced by mannose, with the thioredoxin-interacting protein (Txnip) gene showing the most significant differences. Subsequently, small interfering RNA (siRNA) technology was used to demonstrate that Txnip is the key gene through which mannose exerts its effects. Techniques such as colocalization analysis, molecular docking, and overexpression assays further confirmed the direct regulatory relationship between mannose and TXNIP. To elucidate the mechanism of action of mannose, metabolomics techniques were employed to pinpoint glutamine as a core metabolite affected by mannose. Next, various methods, including integrated omics data and the Gene Expression Omnibus (GEO) database, were used to validate the one-way pathway through which TXNIP regulates glutamine. Finally, the therapeutic effect of mannose on IVDD was validated, elucidating the mechanistic role of TXNIP in glutamine metabolism in both intradiscal and orally treated rats. RESULTS: In both in vivo and in vitro experiments, it was discovered that mannose has potent efficacy in alleviating IVDD by inhibiting catabolism. From a mechanistic standpoint, it was shown that mannose exerts its anti-catabolic effects by directly targeting the transcription factor max-like protein X-interacting protein (MondoA), resulting in the upregulation of TXNIP. This upregulation, in turn, inhibits glutamine metabolism, ultimately accomplishing its anti-catabolic effects by suppressing the mitogen-activated protein kinase (MAPK) pathway. More importantly, in vivo experiments have further demonstrated that compared with intradiscal injections, oral administration of mannose at safe concentrations can achieve effective therapeutic outcomes. CONCLUSIONS: In summary, through integrated multiomics analysis, including both in vivo and in vitro experiments, this study demonstrated that mannose primarily exerts its anti-catabolic effects on IVDD through the TXNIP-glutamine axis. These findings provide strong evidence supporting the potential of the use of mannose in clinical applications for alleviating IVDD. Compared to existing clinically invasive or pain-relieving therapies for IVDD, the oral administration of mannose has characteristics that are more advantageous for clinical IVDD treatment.

Effective delivery of miR-150-5p with nucleus pulposus cell-specific nanoparticles attenuates intervertebral disc degeneration.

BACKGROUND: The use of gene therapy to deliver microRNAs (miRNAs) has gradually translated to preclinical application for the treatment of intervertebral disc degeneration (IDD). However, the effects of miRNAs are hindered by the short half-life time and the poor cellular uptake, owing to the lack of efficient delivery systems. Here, we investigated nucleus pulposus cell (NPC) specific aptamer-decorated polymeric nanoparticles that can load miR-150-5p for IDD treatment. METHODS: The role of miR-150-5p during disc development and degeneration was examined by miR-150-5p knockout (KO) mice. Histological analysis was undertaken in disc specimens. The functional mechanism of miR-150-5p in IDD development was investigated by qRT-PCR assay, Western blot, coimmunoprecipitation and immunofluorescence. NPC specific aptamer-decorated nanoparticles was designed, and its penetration, stability and safety were evaluated. IDD progression was assessed by radiological analysis including X-ray and MRI, after the annulus fibrosus needle puncture surgery with miR-150-5p manipulation by intradiscal injection of nanoparticles. The investigations into the interaction between aptamer and receptor were conducted using mass spectrometry, molecular docking and molecular dynamics simulations. RESULTS: We investigated NPC-specific aptamer-decorated polymeric nanoparticles that can bind to miR-150-5p for IDD treatment. Furthermore, we detected that nanoparticle-loaded miR-150-5p inhibitors alleviated NPC senescence in vitro, and the effects of the nanoparticles were sustained for more than 3 months in vivo. The microenvironment of NPCs improves the endo/lysosomal escape of miRNAs, greatly inhibiting the secretion of senescence-associated factors and the subsequent degeneration of NPCs. Importantly, nanoparticles delivering miR-150-5p inhibitors attenuated needle puncture-induced IDD in mouse models by targeting FBXW11 and inhibiting TAK1 ubiquitination, resulting in the downregulation of NF-kB signaling pathway activity. CONCLUSIONS: NPC-targeting nanoparticles delivering miR-150-5p show favorable therapeutic efficacy and safety and may constitute a promising treatment for IDD.

Genkwanin alleviates intervertebral disc degeneration via regulating ITGA2/PI3K/AKT pathway and inhibiting apoptosis and senescence.

Intervertebral disc degeneration (IVDD) is a progressive degenerative disease influenced by various factors. Genkwanin, a known anti-inflammatory flavonoid, has not been explored for its potential in IVDD management. This study aims to investigate the effects and mechanisms of genkwanin on IVDD. In vitro, cell experiments revealed that genkwanin dose-dependently inhibited Interleukin-1ß-induced expression levels of inflammatory factors (Interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2) and degradation metabolic protein (matrix metalloproteinase-13). Concurrently, genkwanin upregulated the expression of synthetic metabolism genes (type II collagen, aggrecan). Moreover, genkwanin effectively reduced the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin, mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways. Transcriptome sequencing analysis identified integrin α2 (ITGA2) as a potential target of genkwanin, and silencing ITGA2 reversed the activation of PI3K/AKT pathway induced by Interleukin-1ß. Furthermore, genkwanin alleviated Interleukin-1ß-induced senescence and apoptosis in nucleus pulposus cells. In vivo animal experiments demonstrated that genkwanin mitigated the progression of IVDD in the rat model through imaging and histological examinations. In conclusion, This study suggest that genkwanin inhibits inflammation in nucleus pulposus cells, promotes extracellular matrix remodeling, suppresses cellular senescence and apoptosis, through the ITGA2/PI3K/AKT, NF-κB and MAPK signaling pathways. These findings indicate that genkwanin may be a promising therapeutic candidate for IVDD.

The Emerging Roles of Nanocarrier Drug Delivery System in Treatment of Intervertebral Disc Degeneration-Current Knowledge, Hot Spots, Challenges and Future Perspectives.

Low back pain (LBP) is a common condition that has substantial consequences on individuals and society, both socially and economically. The primary contributor to LBP is often identified as intervertebral disc degeneration (IVDD), which worsens and leads to significant spinal problems. The conventional treatment approach for IVDD involves physiotherapy, drug therapy for pain management, and, in severe cases, surgery. However, none of these treatments address the underlying cause of the condition, meaning that they cannot fundamentally reverse IVDD or restore the mechanical function of the spine. Nanotechnology and regenerative medicine have made significant advancements in the field of healthcare, particularly in the area of nanodrug delivery systems (NDDSs). These approaches have demonstrated significant potential in enhancing the efficacy of IVDD treatments by providing benefits such as high biocompatibility, biodegradability, precise drug delivery to targeted areas, prolonged drug release, and improved therapeutic results. The advancements in different NDDSs designed for delivering various genes, cells, proteins and therapeutic drugs have opened up new opportunities for effectively addressing IVDD. This comprehensive review provides a consolidated overview of the recent advancements in the use of NDDSs for the treatment of IVDD. It emphasizes the potential of these systems in overcoming the challenges associated with this condition. Meanwhile, the insights and ideas presented in this review aim to contribute to the advancement of precise IVDD treatment using NDDSs.

Glutamine suppresses senescence and promotes autophagy through glycolysis inhibition-mediated AMPKα lactylation in intervertebral disc degeneration.

Regulating metabolic disorders has become a promising focus in treating intervertebral disc degeneration (IDD). A few drugs regulating metabolism, such as atorvastatin, metformin, and melatonin, show positive effects in treating IDD. Glutamine participates in multiple metabolic processes, including glutaminolysis and glycolysis; however, its impact on IDD is unclear. The current study reveals that glutamine levels are decreased in severely degenerated human nucleus pulposus (NP) tissues and aging Sprague-Dawley (SD) rat nucleus pulposus tissues, while lactate accumulation and lactylation are increased. Supplementary glutamine suppresses glycolysis and reduces lactate production, which downregulates adenosine-5'-monophosphate-activated protein kinase α (AMPKα) lactylation and upregulates AMPKα phosphorylation. Moreover, glutamine treatment reduces NP cell senescence and enhances autophagy and matrix synthesis via inhibition of glycolysis and AMPK lactylation, and glycolysis inhibition suppresses lactylation. Our results indicate that glutamine could prevent IDD by glycolysis inhibition-decreased AMPKα lactylation, which promotes autophagy and suppresses NP cell senescence.

Ginsenoside Rg1 relieves rat intervertebral disc degeneration and inhibits IL-1ß-induced nucleus pulposus cell apoptosis and inflammation via NF-κB signaling pathway.

The study aimed to investigate the effect of ginsenoside Rg1 on intervertebral disc degeneration (IVDD) in rats and IL-1ß-induced nucleus pulposus (NP) cells, and explore its underlying mechanism. Forty IVDD rat models were divided into the IVDD group, low-dose (L-Rg1) group (intraperitoneal injection of 20 mg/kg/d ginsenoside Rg1), medium-dose (M-Rg1) group (intraperitoneal injection of 40 mg/kg/d ginsenoside Rg1), and high-dose (H-Rg1) group (intraperitoneal injection of 80 mg/kg/d ginsenoside Rg1). The pathological change was observed by HE and safranin O-fast green staining. The expression of IL-1ß, IL-6, TNF-α, MMP3, aggrecan, and collagen II was detected. The expression of NF-κB p65 in IVD tissues was detected. Rat NP cells were induced by IL-1ß to simulate IVDD environment and divided into the control group, IL-1ß group, and 20, 50, and 100 µmol/L Rg1 groups. The cell proliferation activity, the apoptosis, and the expression of IL-6, TNF-α, MMP3, aggrecan, collagen II, and NF-κB pathway-related protein were detected. In IVDD rats, ginsenoside Rg1 improved the pathology of IVD tissues; suppressed the expression of IL-1ß, IL-6, TNF-α, aggrecan, and collagen II; and inhibited the expression of p-p65/p65 and nuclear translocation of p65, to alleviate the IVDD progression. In the IL-1ß-induced NP cells, ginsenoside Rg1 also improved the cell proliferation and inhibited the apoptosis and the expression of IL-6, TNF-α, aggrecan, collagen II, p-p65/p65, and IκK in a dose-dependent manner. Ginsenoside Rg1 alleviated IVDD in rats and inhibited apoptosis, inflammatory response, and ECM degradation in IL-1ß-induced NP cells. And Rg1 may exert its effect via inhibiting the activation of NF-κB signaling pathway.

The Sanbi Decoction alleviates intervertebral disc degeneration in rats through intestinal flora and serum metabolic homeostasis modulation.

BACKGROUND: Intervertebral disc degeneration (IVDD) is an essential cause of low back pain (LBP), the incidence of which has risen in recent years and is progressively younger, but treatment options are limited, placing a serious economic burden on society. Sanbi decoction (SBD) is an important classical formula for the treatment of IVDD, which can significantly improve patients' symptoms and is a promising alternative therapy. PURPOSE: The aim of this study is to investigate the safety and efficacy of SBD in the treatment of IVDD and to explore the underlying mechanisms by using an integrated analytical approach of microbiomics and serum metabolomics, as well as by using molecular biology. METHODS: A rat IVDD puncture model was established and treated by gavage with different concentrations of SBD, and clean faeces, serum, liver, kidney, and intervertebral disc (IVD) were collected after 4 weeks. We assessed the safety by liver and kidney weighing, functional tests and tissue staining, the expression of tumor necrosis factor-alpha (TNF-ɑ), interleukin 1ß (IL-1ß) and interleukin 6 (IL-6) inflammatory factors in serum was detected by ELISA kits, and X-ray test, magnetic resonance imaging (MRI) examination, immunohistochemistry (IHC), western blotting (WB), hematoxylin-eosin (HE) staining and safranin O-fast green (SO/FG) staining were used to assess the efficacy. Finally, we performed 16S rRNA sequencing analysis on the faeces of different groups and untargeted metabolomics on serum and analyzed the association between them. RESULTS: SBD can effectively reduce the inflammatory response, regulate the metabolic balance of extracellular matrix (ECM), improve symptoms, and restore IVD function. In addition, SBD can significantly improve the diversity of intestinal flora and maintain the balance. At the phylum level, SBD greatly increased the relative abundance of Patescibacteria and Actinobacteriota and decreased the relative abundance of Bacteroidota. At the genus level, SBD significantly increased the relative abundance of Clostridia_UCG-014, Enterorhabdus, and Adlercreutzia, and decreased the relative abundance of Ruminococcaceae_UCG-005 (p < 0.05). Untargeted metabolomics indicated that SBD significantly improved serum metabolites and altered serum expression of 4alpha-phorbol 12,13-didecanoate (4alphaPDD), euscaphic acid (EA), alpha-muricholic acid (α-MCA), 5-hydroxyindoleacetic acid (5-HIAA), and kynurenine (Kyn) (p < 0.05), and the metabolic pathways were mainly lipid metabolism and amino acid metabolism. CONCLUSIONS: This study demonstrated that SBD can extensively regulate intestinal flora and serum metabolic homeostasis to reduce inflammatory response, inhibit the degradation of ECM, restore IVD height and water content to achieve apparent therapeutic effect for IVDD.

Inhibition of MAGL attenuates Intervertebral Disc Degeneration by Delaying nucleus pulposus senescence through STING.

Intervertebral disc degeneration (IVDD) stands as the primary cause of low back pain (LBP). A significant contributor to IVDD is nucleus pulposus cell (NPC) senescence. However, the precise mechanisms underlying NPC senescence remain unclear. Monoacylglycerol lipase (MAGL) serves as the primary enzyme responsible for the hydrolysis of 2-arachidonoylglycerol (2-AG), breaking down monoglycerides into glycerol and fatty acids. It plays a crucial role in various pathological processes, including pain, inflammation, and oxidative stress. In this study, we utilized a lipopolysaccharide (LPS)-induced NPC senescence model and a rat acupuncture-induced IVDD model to investigate the role of MAGL in IVDD both in vitro and in vivo. Initially, our results showed that MAGL expression was increased 2.41-fold and 1.52-fold within NP tissues from IVDD patients and rats induced with acupuncture, respectively. This increase in MAGL expression was accompanied by elevated expression of p16INK4α. Following this, it was noted that the suppression of MAGL resulted in a notable decrease in the quantity of SA-ß-gal-positive cells and hindered the manifestation of p16INK4α and the inflammatory factor IL-1ß in NPCs. MAGL inhibition promotes type II collagen (Col-2) expression and inhibits matrix metalloproteinase 13 (MMP13), thereby restoring the balance of extracellular matrix (ECM) metabolism both in vitro and in vivo. A significant role for STING has also been demonstrated in the regulation of NPC senescence by MAGL. The expression of the STING protein was reduced by 57% upon the inhibition of MAGL. STING activation can replicate the effects of MAGL and substantially increase LPS-induced inflammation while accelerating the senescence of NPCs. These results strongly indicate that the inhibition of MAGL can significantly suppress nucleus pulposus senescence via its interaction with STING, consequently restoring the balance of ECM metabolism. This insight provides new perspectives for potential treatments for IVDD.

Laquinimod attenuates oxidative stress-induced mitochondrial injury and alleviates intervertebral disc degeneration by inhibiting the NF-κB signaling pathway.

BACKGROUND: Low back pain (LBP) caused by intervertebral disc degeneration (IVDD) is a significant global health concern. It is necessary to investigate the underlying pathological mechanisms leading to IVDD and develop precise treatment strategies for this condition. Considering the well-established anti-inflammatory properties and ability to reduce oxidative stress in various diseases, for the first time we aim to explore the potential of Laquinimod in alleviating IVDD. METHODS: We used hydrogen peroxide (H2O2) to simulate the oxidative stress microenvironment in IVDD, and Laquinimod for intervention purposes. Western blot analysis, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence assay were used to measure the expression levels of inflammatory cytokines, catabolic enzymes, and markers of extracellular matrix (ECM) synthesis in nucleus pulposus (NP) cells. In addition, dichlorofluorescin-diacetate (DCFH-DA) and JC-1 fluorescent probes, flow cytometry analysis, and qRT-PCR were used to measure mitochondrial function and apoptosis in NP cells under conditions of oxidative stress. An acupuncture-induced rat model of IVDD was established to further evaluate the efficacy of Laquinimod in alleviating IVDD in vivo. RESULTS: Our findings showed that Laquinimod significantly reduced the oxidative stress-induced inflammatory response in NP cells, downregulated the expression of catabolic enzymes, and markedly enhanced ECM degradation by inhibiting the NF-κB signaling pathway. The administration of Laquinimod concurrently improved the mitochondrial functional state and reduced apoptosis in NP cells. Additionally, in vivo experiments in rats showed that Laquinimod significantly alleviated acupuncture-induced IVDD. CONCLUSIONS: Collectively, the findings of this study provide new insights into the therapeutic potential of Laquinimod as a treatment for oxidative stress-induced IVDD.

Mitochondrial-Targeted Metal-Phenolic Nanoparticles to Attenuate Intervertebral Disc Degeneration: Alleviating Oxidative Stress and Mitochondrial Dysfunction.

As intervertebral disc degeneration (IVDD) proceeds, the dysfunctional mitochondria disrupt the viability of nucleus pulposus cells, initiating the degradation of the extracellular matrix. To date, there is a lack of effective therapies targeting the mitochondria of nucleus pulposus cells. Here, we synthesized polygallic acid-manganese (PGA-Mn) nanoparticles via self-assembly polymerization of gallic acid in an aqueous medium and introduced a mitochondrial targeting peptide (TP04) onto the nanoparticles using a Schiff base linkage, resulting in PGA-Mn-TP04 nanoparticles. With a size smaller than 50 nm, PGA-Mn-TP04 possesses pH-buffering capacity, avoiding lysosomal confinement and selectively accumulating within mitochondria through electrostatic interactions. The rapid electron exchange between manganese ions and gallic acid enhances the redox capability of PGA-Mn-TP04, effectively reducing mitochondrial damage caused by mitochondrial reactive oxygen species. Moreover, PGA-Mn-TP04 restores mitochondrial function by facilitating the fusion of mitochondria and minimizing their fission, thereby sustaining the vitality of nucleus pulposus cells. In the rat IVDD model, PGA-Mn-TP04 maintained intervertebral disc height and nucleus pulposus tissue hydration. It offers a nonoperative treatment approach for IVDD and other skeletal muscle diseases resulting from mitochondrial dysfunction, presenting an alternative to traditional surgical interventions.

Kongensin a attenuates intervertebral disc degeneration by inhibiting TAK1-mediated PANoptosis of nucleus pulposus cells.

Low back pain (LBP) is most commonly caused by intervertebral disc degeneration (IVDD). Pyroptosis, apoptosis, and necroptosis are crucial in IVDD pathogenesis; however, possible simultaneous occurrence in IVDD and co-regulation between the pathways and the regulatory mechanisms have not been investigated. PANoptosis is a regulated cell death (RCD) pathway with the key characteristics of pyroptosis, apoptosis, and necroptosis. This study revealed that tert-butyl hydroperoxide (TBHP) altered the expression of key proteins involved in PANoptosis in nucleus pulposus cells (NPCs). Furthermore, the natural product Kongensin A (KA), which has potential anti-necrotic and anti-inflammatory properties, inhibited PANoptosis. TAK1, often referred to as mitogen-activated protein kinase kinase kinase 7 (Map3k7), is a key regulator of innate immunity, cell death, inflammation, and cellular homeostasis; however, the physiological roles and regulatory mechanisms underlying IVDD remain unclear. In this study, we discovered that KA can upregulate TAK1 expression in NPCs, -which inhibits PANoptosis by suppressing oxidative stress. In conclusion, our results suggest that KA inhibits PANoptosis and delays IVDD progression in NPCs by upregulating TAK1 expression to maintain mitochondrial redox balance. Consequently, targeting TAK1 may be a promising therapeutic approach for IVDD therapy.

Downregulation of VEGFA accelerates AGEs-mediated nucleus pulposus degeneration through inhibiting protective mitophagy in high glucose environments.

Intervertebral disc degeneration (IVDD) contributes largely to low back pain. Recent studies have highlighted the exacerbating role of diabetes mellitus (DM) in IVDD, mainly due to the influence of hyperglycemia (HG) or the accumulation of advanced glycation end products (AGEs). Vascular endothelial growth factor A (VEGFA) newly assumed a distinct impact in nonvascular tissues through mitophagy regulation. However, the combined actions of HG and AGEs on IVDD and the involved role of VEGFA remain unclear. We confirmed the potential relation between VEGFA and DM through bioinformatics and biological specimen detection. Then we observed that AGEs induced nucleus pulposus (NP) cell degeneration by upregulating cellular reactive oxygen species (ROS), and HG further aggravated ROS level through breaking AGEs-induced protective mitophagy. Furthermore, this adverse effect could be strengthened by VEGFA knockdown. Importantly, we identified that the regulation of VEGFA and mitophagy were vital mechanisms in AGEs-HG-induced NP cell degeneration through Parkin/Akt/mTOR and AMPK/mTOR pathway. Additionally, VEGFA overexpression through local injection with lentivirus carrying VEGFA plasmids significantly alleviated NP degeneration and IVDD in STZ-induced diabetes and puncture rat models. In conclusion, the findings first confirmed that VEGFA protects against AGEs-HG-induced IVDD, which may represent a therapeutic strategy for DM-related IVDD.

MicroRNA-targeting nanomedicines for the treatment of intervertebral disc degeneration.

Low back pain stands as a pervasive global health concern, afflicting almost 80% of adults at some point in their lives with nearly 40% attributable to intervertebral disc degeneration (IVDD). As only symptomatic relief can be offered to patients there is a dire need for innovative treatments.Given the accumulating evidence that multiple microRNAs (miRs) are dysregulated during IVDD, they could have a huge potential against this debilitating condition. The way miRs can profoundly modulate signaling pathways and influence several cellular processes at once is particularly exciting to tackle this multifaceted disorder. However, miR delivery encounters extracellular and intracellular biological barriers. A promising technology to address this challenge is the vectorization of miRs within nanoparticles, providing both protection and enhancing their uptake within the scarce target cells of the degenerated IVD. This comprehensive review presents the diverse spectrum of miRs' connection with IVDD and demonstrates their therapeutic potential when vectorized in nanomedicines.

Ginsenoside Rg3 exhibits anti-catabolic and anti-apoptotic effects in IL-1ß treated human disc nucleus pulposus cells and in a rat model of disc degeneration by inactivating the MAPK pathway.

Intervertebral disc degeneration (IDD) is the major cause of degeneration of joint diseases. IDD is characterized by a large number of apoptosis of nucleus pulposus cells (NPCs) and extracellular matrix (ECM) degradation. Ginsenoside Rg3 is the active component extracted from ginseng and has a vital function in modulating diseases. This study aimed to investigate the regulatory functions of ginsenoside Rg3 in IDD. We established the IDD cell model via inducing NPCs with IL-1ß. The rat model of IDD was established by fibrous ring puncture method. Cell apoptotic capability was assessed through TUNEL assay. The levels of catabolic proteases MMPs and ADAMTSs were tested by western blot and RT-qPCR. IL-1ß induction notably promoted the apoptosis of NPCs, while ginsenoside Rg3 treatment reversed the promoting function of IL-1ß. Furthermore, we found that MMP2, MMP3, Adamts4, and Adamts5 levels were increased in IL-1ß-induced NPCs, while ginsenoside Rg3 treatment markedly reduced their levels. Additionally, ginsenoside Rg3 was found to suppress the IL-1ß-stimulated p38 MAPK pathway in NPCs. In the IDD rat model, we found that ginsenoside Rg3 treatment can alleviate NPC degeneration, recover the arrangement of annulus fibrous, and preserve more proteoglycan matrix. Moreover, ginsenoside Rg3 reduced apoptosis and catabolism and inactivated the p38 MAPK pathway in IDD rats. Ginsenoside Rg3 exhibits anti-catabolic and anti-apoptotic effects in IL-1ß-stimulated NPCs and IDD rats by inactivating MAPK pathway.

Ozone therapy (O2-O3) alleviates the progression of early intervertebral disc degeneration via the inhibition of oxidative stress and the interception of the PI3K/Akt/NF-κB signaling pathway.

Intervertebral disc degeneration (IDD) stands for the most frequent cause of low back pain. Finding a cure for this disease is an important challenge as current conservative treatments and surgical interventions fail to bring a solution to this disease. Ozone therapy (O2-O3) has yielded outstanding outcomes in intervertebral disc pathology. The ozone's efficacy in the treatment of IDD remains unconfirmed. This study aimed to assess the effectiveness of intradiscal ozone injection on IDD induced in a rat. Effects of ozone therapy on the viability of nucleus pulposus cells were evaluated by CCK-8 assays. Macrophage immunoreactivity was detected by immunohistochemical, the expression of collagen type II was evaluated by western blot, and measurement of oxidative stress parameters was realized. Molecular docking studies were carried out in order to predict the interaction formed between O3 and the target enzymes, on the one hand, O3 with PI3K and, on the other hand, O3 with COX-2. IRM, X-ray, hematoxylin-eosin, and bleu alcian staining were realized to assess the therapeutic impacts of ozone in the puncture-induced rat model of IDD. In vivo, O3 ameliorated the IDD in the early stage of this disease. It was also displayed in molecular docking that O3 might bind to PI3K to suppress the PI3K/Akt/NF-κB signaling pathway. This study's results show that the O3 should be administered at the low grade of IDD and at an early stage because it cannot restore the advanced inflammatory alteration of the IVD. Our results corroborated also that O3 inhibits the progression of IDD via the PI3K/Akt/NF-κB signaling pathway, which supports O3 as an effective therapeutic option for treating IDD.

Catalytic Nanodots-Driven Pyroptosis Suppression in Nucleus Pulposus for Antioxidant Intervention of Intervertebral Disc Degeneration.

Low back pain resulting from intervertebral disc degeneration (IVDD) is a prevalent global concern; however, its underlying mechanism remains elusive. Single-cell sequencing analyses revealed the critical involvement of pyroptosis in IVDD. Considering the involvement of reactive oxygen species (ROS) as the primary instigator of pyroptosis and the lack of an efficient intervention approach, this study developed carbonized Mn-containing nanodots (MCDs) as ROS-scavenging catalytic biomaterials to suppress pyroptosis of nucleus pulposus (NP) cells to efficiently alleviate IVDD. Catalytic MCDs have superior efficacy in scavenging intracellular ROS and rescuing homeostasis in the NP microenvironment compared with N-acetylcysteine, a classical antioxidant. The data validates that pyroptosis plays a vital role in mediating the protective effects of catalytic MCDs against oxidative stress. Systematic in vivo assessments substantiate the effectiveness of MCDs in rescuing a puncture-induced IVDD rat model, further demonstrating their ability to suppress pyroptosis. This study highlights the potential of antioxidant catalytic nanomedicine as a pyroptosis inhibitor and mechanistically unveils an efficient strategy for the treatment of IVDD.

From drugs to biomaterials: a review of emerging therapeutic strategies for intervertebral disc inflammation.

Chronic low back pain (LBP) is an increasingly prevalent issue, especially among aging populations. A major underlying cause of LBP is intervertebral disc degeneration (IDD), often triggered by intervertebral disc (IVD) inflammation. Inflammation of the IVD is divided into Septic and Aseptic inflammation. Conservative therapy and surgical treatment often fail to address the root cause of IDD. Recent advances in the treatment of IVD infection and inflammation range from antibiotics and small-molecule drugs to cellular therapies, biological agents, and innovative biomaterials. This review sheds light on the complex mechanisms of IVD inflammation and physiological and biochemical processes of IDD. Furthermore, it provides an overview of recent research developments in this area, intending to identify novel therapeutic targets and guide future clinical strategies for effectively treating IVD-related conditions.

Mechanically tough, adhesive, self-healing hydrogel promotes annulus fibrosus repair via autologous cell recruitment and microenvironment regulation.

Annulus fibrosus (AF) defect is an important cause of disc re-herniation after discectomy. The self-regeneration ability of the AF is limited, and AF repair is always hindered by the inflammatory microenvironment after injury. Hydrogels represent one of the most promising materials for AF tissue engineering strategies. However, currently available commercial hydrogels cannot withstand the harsh mechanical load within intervertebral disc. In the present study, an innovative triple cross-linked oxidized hyaluronic acid (OHA)-dopamine (DA)- polyacrylamide (PAM) composite hydrogel, modified with collagen mimetic peptide (CMP) and supplied with transforming growth factor beta 1 (TGF-ß1) (OHA-DA-PAM/CMP/TGF-ß1 hydrogel) was developed for AF regeneration. The hydrogel exhibited robust mechanical strength, strong bioadhesion, and significant self-healing capabilities. Modified with collagen mimetic peptide, the hydrogel exhibited extracellular-matrix-mimicking properties and sustained the AF cell phenotype. The sustained release of TGF-ß1 from the hydrogel was pivotal in recruiting AF cells and promoting extracellular matrix production. Furthermore, the composite hydrogel attenuated LPS-induced inflammatory response and promote ECM synthesis in AF cells via suppressing NFκB/NLRP3 pathway. In vivo, the composite hydrogel successfully sealed AF defects and alleviated intervertebral disk degeneration in a rat tail AF defect model. Histological evaluation showed that the hydrogel integrated well with host tissue and facilitated AF repair. The strategy of recruiting endogenous cells and providing an extracellular-matrix-mimicking and anti-inflammatory microenvironment using the mechanically tough composite OHA-DA-PAM/CMP/TGF-ß1 hydrogel may be applicable for AF defect repair in the clinic. STATEMENT OF SIGNIFICANCE: Annulus fibrosus (AF) repair is challenging due to its limited self-regenerative capacity and post-injury inflammation. In this study, a mechanically tough and highly bioadhesive triple cross-linked composite hydrogel, modified with collagen mimetic peptide (CMP) and supplemented with transforming growth factor beta 1 (TGF-ß1), was developed to facilitate AF regeneration. The sustained release of TGF-ß1 enhanced AF cell recruitment, while both TGF-ß1 and CMP could modulate the microenvironment to promote AF cell proliferation and ECM synthesis. In vivo, this composite hydrogel effectively promoted the AF repair and mitigated the intervertebral disc degeneration. This research indicates the clinical potential of the OHA-DA-PAM/CMP/TGF-ß1 composite hydrogel for repairing AF defects.

Therapeutic effect and mechanism of Yougui Wan in rats with intervertebral disk degeneration.

OBJECTIVE: To explore the potential mechanism of Yougui Wan on deformed lumbar intervertebral disk structure in rats. METHODS: Thirty male Sprague-Dawley rats were randomly divided into 3 groups, with 10 rats in each group. The animals in the blank control group were healthy rats without specific treatment, and those in the model group and traditional Chinese medicine (TCM) group were used to establish the intervertebral disk degeneration (IDD) model by puncturing the annulus. Four weeks after modeling, rats in the TCM group were administered Yougui Wan by gavage for 2 consecutive weeks. Serum interleukin-6 (IL-10), macrophage migration inhibitory factor (MIF) and tumor necrosis factor alpha (TNF-α) levels were measured by ELISA, and the protein expression levels of collagen II and Notch1 in intervertebral disk tissues were examined by Western blotting. Apoptosis was detected by the TUNEL method. RESULTS: Compared with those in the blank group, IL-10, MIF and TNF-α levels in the model group and TCM group were increased (P < 0.05), the protein expression levels of collagen II were decreased, and the protein expression levels of Notch1 were increased. Compared with those in the model group, the levels of IL-10 in the TCM group were increased (P < 0.05), the levels of MIF and TNF-α were decreased (P < 0.05), the protein expression levels of collagen II were increased, and the protein expression levels of Notch1 were decreased. CONCLUSION: Yougui Wan can inhibit the inflammatory response in IDD rats, reduce the degradation of extracellular matrix, reduce apoptosis in nucleus pulposus cells, and alleviate intervertebral disk degeneration. The mechanism may be related to the regulation of the Notch signaling pathway.

An Engineered Bionic Nanoparticle Sponge as a Cytokine Trap and Reactive Oxygen Species Scavenger to Relieve Disc Degeneration and Discogenic Pain.

The progressive worsening of disc degeneration and related nonspecific back pain are prominent clinical issues that cause a tremendous economic burden. Activation of reactive oxygen species (ROS) related inflammation is a primary pathophysiologic change in degenerative disc lesions. This pathological state is associated with M1 macrophages, apoptosis of nucleus pulposus cells (NPC), and the ingrowth of pain-related sensory nerves. To address the pathological issues of disc degeneration and discogenic pain, we developed MnO2@TMNP, a nanomaterial that encapsulated MnO2 nanoparticles with a TrkA-overexpressed macrophage cell membrane (TMNP). Consequently, this engineered nanomaterial showed high efficiency in binding various inflammatory factors and nerve growth factors, which inhibited inflammation-induced NPC apoptosis, matrix degradation, and nerve ingrowth. Furthermore, the macrophage cell membrane provided specific targeting to macrophages for the delivery of MnO2 nanoparticles. MnO2 nanoparticles in macrophages effectively scavenged intracellular ROS and prevented M1 polarization. Supportively, we found that MnO2@TMNP prevented disc inflammation and promoted matrix regeneration, leading to downregulated disc degenerative grades in the rat injured disc model. Both mechanical and thermal hyperalgesia were alleviated by MnO2@TMNP, which was attributed to the reduced calcitonin gene-related peptide (CGRP) and substance P expression in the dorsal root ganglion and the downregulated Glial Fibrillary Acidic Protein (GFAP) and Fos Proto-Oncogene (c-FOS) signaling in the spinal cord. We confirmed that the MnO2@TMNP nanomaterial alleviated the inflammatory immune microenvironment of intervertebral discs and the progression of disc degeneration, resulting in relieved discogenic pain.