Nrf2 activation by pyrroloquinoline quinone inhibits natural aging-related intervertebral disk degeneration in mice

Age-related intervertebral disk degeneration (IVDD) involves increased oxidative damage, cellular senescence, and matrix degradation. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound with strong anti-oxidant capacity. The goal of this study was to determine whether PQQ can prevent aging-related IVDD, and the underlying mechanism. Here, we found that dietary PQQ supplementation for 12 months alleviated IVDD phenotypes in aged mice, including increased disk height index and reduced histological scores and cell loss, without toxicity. Mechanistically, PQQ inhibited oxidative stress, cellular senescence, and senescence-associated secretory phenotype (SASP) in the nucleus pulposus and annulus fibrosus of aged mice. Similarly, PQQ protected against interleukin-1β-induced matrix degradation, reactive oxygen species accumulation, and senescence in human nucleus pulposus cells (NPCs) in vitro. Molecular docking predicted and biochemical assays validated that PQQ interacts with specific residues to dissociate the Keap1-Nrf2 complex, thereby increasing nuclear Nrf2 translocation and activation of Nrf2-ARE signaling. RNA sequencing and luciferase assays revealed Nrf2 can transcriptionally upregulate Wnt5a by binding to its promoter, while Wnt5a knockdown prevented PQQ inhibition of matrix metalloproteinase-13 in NPCs. Notably, PQQ supplementation failed to alleviate aging-associated IVDD phenotypes and oxidative stress in aged Nrf2 knockout mice, indicating Nrf2 is indispensable for PQQ bioactivities. Collectively, this study demonstrates Nrf2 activation by PQQ inhibits aging-induced IVDD by attenuating cellular senescence and matrix degradation. This study clarifies Keap1-Nrf2-Wnt5a axis as the novel signaling underlying the protective effects of PQQ against aging-related IVDD, and provides evidence for PQQ as a potential agent for clinical prevention and treatment of natural aging-induced IVDD.

Identification of key eRNAs for intervertebral disc degeneration by integrated multinomial bioinformatics analysis

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common degenerative condition leading to abnormal stress distribution under load, causing intervertebral stenosis, facet joint degeneration, and foraminal stenosis. Very little is known about the molecular mechanism of eRNAs in IVDD.

METHODS

Gene expression profiles of 38 annulus disc samples composed of 27 less degenerated discs (LDs) and 11 more degenerated discs (MDs) were retrieved from the GEO database. Then, differentially expressed enhancer RNAs (DEeRNAs), differentially expressed target genes (DETGs), and differentially expressed transcription factors (DETFs), hallmark of cancer signalling pathways according to GSVA; the types and quantity of immune cells according to CIBERSORT; and immune gene sets according to ssGSEA were analysed to construct an IVDD-related eRNA network. Then, multidimensional validation was performed to explore the interactions among DEeRNAs, DETFs and DEGs in space.

RESULTS

A total of 53 components, 14 DETGs, 15 DEeRNAs, 3 DETFs, 5 immune cells, 9 hallmarks, and 7 immune gene sets, were selected to construct the regulatory network. After validation by online multidimensional databases, 21 interactive DEeRNA-DEG-DETF axes related to IVDD exacerbation were identified, among which the C1S-CTNNB1-CHD4 axis was the most significant.

CONCLUSION

Based upon the results of our study, we theorize that the C1S-CTNNB1-CHD4 axis plays a vital role in IVDD exacerbation. Specifically, C1S recruits CTNNB1 and upregulates the expression of CHD4 in IVDD, and subsequently, CHD4 suppresses glycolysis and activates oxidative phosphorylation, thus generating insoluble collagen fibre deposits and leading to the progression of IVDD. Overall, these DEeRNAs could comprise promising therapeutic targets for IVDD due to their high tissue specificity.

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-β-gal-positive cells and hindered the manifestation of p16INK4α and the inflammatory factor IL-1β 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.

Experimental validation and comprehensive analysis of m6A methylation regulators in intervertebral disc degeneration subpopulation classification

Intervertebral disc degeneration (IVDD) is one of the most prevalent causes of chronic low back pain. The role of m6A methylation modification in disc degeneration (IVDD) remains unclear. We investigated immune-related m6A methylation regulators as IVDD biomarkers through comprehensive analysis and experimental validation of m6A methylation regulators in disc degeneration. The training dataset was downloaded from the GEO database and analysed for differentially expressed m6A methylation regulators and immunological features, the differentially regulators were subsequently validated by a rat IVDD model and RT-qPCR. Further screening of key m6A methylation regulators based on machine learning and LASSO regression analysis. Thereafter, a predictive model based on key m6A methylation regulators was constructed for training sets, which was validated by validation set. IVDD patients were then clustered based on the expression of key m6A regulators, and the expression of key m6A regulators and immune infiltrates between clusters was investigated to determine immune markers in IVDD. Finally, we investigated the potential role of the immune marker in IVDD through enrichment analysis, protein-to-protein network analysis, and molecular prediction. By analysising of the training set, we revealed significant differences in gene expression of five methylation regulators including RBM15, YTHDC1, YTHDF3, HNRNPA2B1 and ALKBH5, while finding characteristic immune infiltration of differentially expressed genes, the result was validated by PCR. We then screen the differential m6A regulators in the training set and identified RBM15 and YTHDC1 as key m6A regulators. We then used RBM15 and YTHDC1 to construct a predictive model for IVDD and successfully validated it in the training set. Next, we clustered IVDD patients based on the expression of RBM15 and YTHDC1 and explored the immune infiltration characteristics between clusters as well as the expression of RBM15 and YTHDC1 in the clusters. YTHDC1 was finally identified as an immune biomarker for IVDD. We finally found that YTHDC1 may influence the immune microenvironment of IVDD through ABL1 and TXK. In summary, our results suggest that YTHDC1 is a potential biomarker for the development of IVDD and may provide new insights for the precise prevention and treatment of IVDD.

Mast Cells and Their Related Gene HK-1 are Closely Associated with Discogenic Low Back Pain: A Bioinformatics and Clinical Sample Study

Background

Low back pain (LBP) is primarily caused by intervertebral disc degeneration (IVDD). Immune cells penetrating nucleus pulposus (NP) tissues may play an important role in generating IVDD and LBP.

Methods

The clinical data from 100 cases of IVDD patients was initially analyzed retrospectively. Subsequently, peripheral blood and NP tissues from 41 IVDD patients were gathered for a validated investigation. Among them, ribosome-removed-RNA sequencing (RNA-seq) was performed on 10 cases of NP tissues of specific classifications (VAS 3 and Pfirrmann 3 were used as the controls, while patients with VAS 6 and Pfirrmann 5 were used as the experimental group). Differentially expressed genes (DEGs) were identified for the subsequent bioinformatics analysis. Further methods to confirm the underlying cause of discogenic LBP included mast cell immunohistochemistry (IHC), 12 cytokine detection, Western blot (WB), and real-time polymerase chain reaction (RT-PCR).

Results

Discogenic LBP and IVDD severity are strongly associated, and immunological cell infiltration has been demonstrated to be a significant factor in LBP by bioanalytical research. Tryptase-positive mast cells were found to be significantly more abundant in the VAS 6 NP tissues of IVDD patients than in the VAS 3 NP tissues. It was initially demonstrated that IVDD and LBP were significantly impacted by hemokinin-1 (HK-1), the mast cell-related gene. Furthermore, blood levels of interleukin 12 p70 (IL-12P70) are noticeably elevated and strongly correlated with HK-1, indicating that HK-1 may be involved in the regulation of mast cell activity and IL-12P70 production.

Conclusion

The severity of LBP was observed to be positively correlated with the IVDD Pfirrmann grading. Further research indicates that patients with IVDD may experience persistent low back pain due to HK-1 activation of mast cells and the release of the cytokine IL12P70. This work will offer new insights into the diagnosis and treatment of discogenic LBP.

Construction of a novel mRNA-miRNA-lncRNA/circRNA triple subnetwork associated with immunity and aging in intervertebral disc degeneration

OBJECTIVE

Intervertebral disk degeneration (IVDD) is one of the most common causes of low back pain. However, in the etiology of IVDD, the specific method by which nucleus pulposus (NP) cell senescence and the immune response induce disease is uncertain.

METHODS

Gene Expression Omnibus database was used to find differentially expressed genes (DEGs), differentially expressed miRNAs (DE miRNAs), differentially expressed lncRNAs (DE lncRNAs), and differentially expressed circRNAs (DE circRNAs). Functional enrichment analysis was performed through Enrichr database. Potential regulatory miRNAs, lncRNAs and circRNAs of mRNAs were predicted by ENCORI and circBank, respectively.

RESULTS

We identified 198 upregulated and 131 downregulated genes, 39 upregulated and 22 downregulated miRNAs, 2152 upregulated and 564 downregulated lncRNAs, and 352 upregulated and 279 downregulated circRNAs as DEGs, DE miRNAs, DE lncRNAs, DE circRNAs, respectively. Functional enrichment analysis revealed that they were significantly enriched in Toll-like receptor signaling route and the NF-kappa B signaling pathway. An mRNA-miRNA-lncRNA/circRNA network linked to the pathogenesis of NP cells in IVDD was constructed based on node degree and differential expression level. Eight immune-related DEGs (6 upregulated and 2 downregulated genes) and five aging-related DEGs (3 upregulated and 2 downregulated genes) were identified in the critical network.

CONCLUSION

We established a novel immune-related and aging-related triple regulatory network of mRNA-miRNA-lncRNA/circRNA ceRNA, among which all RNAs may be utilized as the pathogenesis biomarker of NP cells in IVDD.

Comparative Analysis of Autophagy and Apoptosis in Disc Degeneration: Understanding the Dynamics of Temporary-Compression-Induced Early Autophagy and Sustained-Compression-Triggered Apoptosis

The purpose of this study was to investigate the initiation of autophagy activation and apoptosis in nucleus pulposus cells under temporary compression (TC) and sustained compression (SC) to identify ideal research approaches in intervertebral disc degeneration. Various techniques were used: radiography (X-ray), magnetic resonance imaging (MRI), transmission electron microscope (TEM), H&E staining, Masson's trichrome staining, immunohistochemistry (IHC) (LC3, beclin-1, and cleaved caspase-3), and real-time polymerase chain reaction (RT-qPCR) for autophagy-related (beclin-1, LC3, and P62) and apoptosis-related (caspase-3 and PARP) gene expression analysis. X-ray and MRI revealed varying degrees of disc degeneration, ranging from moderate to severe in both groups. The severity was directly linked to compression duration, with SC resulting in notably severe central NP cell degeneration. Surprisingly, TC also caused similar, though less severe, degeneration. Elevated expression of LC3 and beclin-1 was identified after 6 weeks, but it notably declined after 12 weeks. Central NP cells in both groups exhibited increased expression of cleaved caspase-3 that was positively correlated with the duration of SC. TC showed fewer apoptotic markers compared to SC. LC3, beclin-1, and P62 mRNA expression peaked after 6 weeks and declined after 12 weeks in both groups. Cleaved caspase-3 and PARP expression peaked in SC, positively correlating with longer compression duration, while TC showed lower levels of apoptosis gene expression. Furthermore, TEM results revealed different events of the autophagic degradation process after 2 weeks of compression. TCmay be ideal for studying early triggered autophagy-mediated degeneration, while SC may be ideal for studying late or slower-triggered apoptosis-mediated degeneration.

FSTL1 Accelerates Nucleus Pulposus Cell Senescence and Intervertebral Disc Degeneration Through TLR4/NF-κB Pathway

Intervertebral disc degeneration (IVDD) is a major contributor to low back pain (LBP), and inflammatory factors play crucial roles in its pathogenesis. Follistatin-like 1 (FSTL1) has been reported to induce an inflammatory response in chondrocytes, microglia and preadipocytes, but its role in the pathogenesis of nucleus pulposus cell (NPC) degeneration remains unclear. In this study, we mainly utilized an acidosis-induced NPC degeneration model and a rabbit puncture IVDD model to investigate the role of FSTL1 in IVDD both in vitro and in vivo. We confirmed that FSTL1 expression significantly increased in nucleus pulposus (NP) tissues from IVDD patients and rabbit puncture IVDD models. The expression levels of FSTL1 were significantly increased in all three models of NPC degeneration under harsh microenvironments. In addition, recombinant human FSTL1 (rh-FSTL1) was found to upregulate the expression of p16 and p21, increase the number of senescence-associated β-galactosidase (SA-β-gal)-positive cells, induce senescence-related secretory phenotypes (SASP), and downregulate extracellular matrix (ECM) protein expressions, leading to an imbalance in ECM metabolism destructions. Conversely, silencing of FSTL1 by small interfering RNA (siRNA) ameliorated senescence of NPCs associated with inflammation in IVDD. Furthermore, Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway plays a crucial role in regulating NPC senescence through FSTL1 regulation. Inhibition of TLR4 expression partly reversed the effects of rh-FSTL1 on NPC senescence-associated inflammation. Finally, rabbit IVDD model experiments demonstrated that the specific FSTL1 siRNA markedly repressed the development of IVDD. These findings may offer a therapeutic approach for mitigating inflammation-induced senescence associated with IVDD.

Fisetin suppresses ferroptosis through Nrf2 and attenuates intervertebral disc degeneration in rats

Low back pain, primarily caused by intervertebral disc degeneration (IVDD), lacks effective pharmacological treatments. Oxidative stress has been identified as a significant contributor to IVDD. This study aims to establish an in vitro model of IVDD induced by oxidative stress and identify potential therapeutic agents and their underlying mechanisms. By screening the natural product library, fisetin emerged as the most promising compound in suppressing cell death induced by oxidative stress in nucleus pulposus cells (NPCs). Furthermore, our investigation revealed that the cell death induced by oxidative stress was predominantly associated with ferroptosis, and fisetin demonstrated the ability to inhibit ferroptosis in NPCs. Mechanistic exploration suggested that the impact of fisetin on ferroptosis may be mediated through the Nrf2/HO-1 (Nuclear factor erythroid 2-related factor 2/heme oxygenase-1) axis. Notably, the in vivo study demonstrated that fisetin could alleviate IVDD in rats. These findings highlight fisetin as a potential therapeutic option for IVDD and implicate the involvement of the Nrf2/HO-1 pathway in its mechanism of action.

Role of Necroptosis in Intervertebral Disc Degeneration

Apoptosis has historically been considered the primary form of programmed cell death (PCD) and is responsible for regulating cellular processes during development, homeostasis, and disease. Conversely, necrosis was considered uncontrolled and unregulated. However, recent evidence has unveiled the significance of necroptosis, a regulated form of necrosis, as an important mechanism of PCD alongside apoptosis. The activation of necroptosis leads to cellular membrane disruption, inflammation, and vascularization. This process is crucial in various pathological conditions, including intervertebral disc degeneration (IVDD), neurodegeneration, inflammatory diseases, multiple cancers, and kidney injury. In recent years, extensive research efforts have shed light on the molecular regulation of the necroptotic pathway. Various stimuli trigger necroptosis, and its regulation involves the activation of specific proteins such as receptor-interacting protein kinase 1 (RIPK1), RIPK3, and the mixed lineage kinase domain-like (MLKL) pseudokinase. Understanding the intricate mechanisms governing necroptosis holds great promise for developing novel therapeutic interventions targeting necroptosis-associated IVDD. The objective of this review is to contribute to the growing body of scientific knowledge in this area by providing a comprehensive overview of necroptosis and its association with IVDD. Ultimately, these understandings will allow the development of innovative drugs that can modulate the necroptotic pathway, offering new therapeutic avenues for individuals suffering from necroptosis.

Strontium Ranelate Ameliorates Intervertebral Disc Degeneration via Regulating TGF-β1/NF-κB Axis

Intervertebral disc degeneration (IVDD) is a prevalent and debilitating condition characterized by chronic back pain and reduced quality of life. Strontium ranelate (SRR) is a compound traditionally used for treating osteoporosis via activating TGF-β1 signaling pathway. Recent studies have proved the anti-inflammatory effect of SRR on chondrocytes. Although the exact mechanism of IVDD remains unclear, accumulating evidences have emphasized the involvement of multifactorial pathogenesis including inflammation, oxidative stress damage, and etc. However, the biological effect of SRR on IVDD and its molecular mechanism has not been investigated. Firstly, this study proved the decreased expression of Transforming Growth Factor-beta 1(TGF-β1) in degenerated human intervertebral disc tissues. Subsequently, we confirmed for the first time that SRR could promote cell proliferation, mitigate inflammation and oxidative stress in human nucleus pulposus cells in vitro via increasing the expression of TGF-β1 and suppressing the Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-κB) pathway. The molecular docking result proved the interaction between SRR and TGF-β1 protein. To further verify this interaction, gain- and loss- of function experiments were conducted. We discovered that both TGF-β1 knockdown and overexpression influenced the activation of the NF-κB pathway. Taken together, SRR could mitigate IL-1β induced-cell dysfunction in human nucleus pulposus cells by regulating TGF-β1/NF-κB axis in vitro. Finally, the in vivo therapeutic effect of SRR on IVDD was confirmed. Our findings may contribute to the understanding of the complex interplay between inflammation and degenerative processes in the intervertebral disc and provide valuable insights into the development of targeted treatment-based therapeutics for IVDD.

Evaluation of intervertebral disc degeneration in young adult asymptomatic Dachshunds with magnetic resonance imaging and radiography

BACKGROUND

Dachshunds have a high prevalence of intervertebral disc disease (IVDD) to which they are predisposed due to early intervertebral disc (IVD) degeneration and calcification. Moreover, the recently found 12-FGF4 retrogene (RG) is associated with calcified discs visible on radiographs (CDVR) and IVDD. Earlier studies suggest that all IVDs of one-year-old Dachshunds show signs of degeneration. This prospective, analytical, blinded study aimed to investigate the extent and distribution of IVD degeneration in young adult (24-31 months) asymptomatic Dachshunds (n = 21) hypothesizing that not all IVDs of two-year-old Dachshunds are degenerated. Another aim was to explore the correlations between IVD degeneration evaluated with magnetic resonance imaging (MRI), the number of CDVR, and the dog's 12-FGF4RG status. The study protocol included grading the CDVR on spinal radiographs, grading the IVD degeneration on T2-weighted sagittal and transverse high-field MR images of all IVDs (n = 546), and 12-FGF4RG variant genotyping.

RESULTS

Of all IVDs evaluated, 2% (n = 11) were normal based on MRI grading. Despite the study population having moderately degenerated IVDs (median MRI grade 3), there was also variation in the degree of IVD degeneration between individuals and in the distribution of IVD degeneration between different vertebral regions. The number of CDVR correlated significantly with the magnitude of IVD degeneration based on MRI evaluation and with the 12-FGF4RG genotype. The odds for being 12-FGF4RG homozygous were higher for Dachshunds with CDVR. However, the 12-FGF4RG variant did not alone explain the phenotypic variation in IVD degeneration.

CONCLUSIONS

The number of CDVR is a valid indicator of overall IVD degeneration, as it correlates with MRI-based IVD grading. Also, as the extent and distribution of IVD degeneration varies between individual Dachshunds, selective breeding against IVDD using radiographic screening and 12-FGF4RG variant genotyping is possible.

The deubiquitinase USP11 ameliorates intervertebral disc degeneration by regulating oxidative stress-induced ferroptosis via deubiquitinating and stabilizing Sirt3

Increasing studies have reported that intervertebral disc degeneration (IVDD) is the main contributor and independent risk factor for low back pain (LBP), it would be, therefore, enlightening that investigating the exact pathogenesis of IVDD and developing target-specific molecular drugs in the future. Ferroptosis is a new form of programmed cell death characterized by glutathione (GSH) depletion, and inactivation of the regulatory core of the antioxidant system (glutathione system) GPX4. The close relationship of oxidative stress and ferroptosis has been studied in various of diseases, but the crosstalk between of oxidative stress and ferroptosis has not been explored in IVDD. At the beginning of the current study, we proved that Sirt3 decreases and ferroptosis occurs after IVDD. Next, we found that knockout of Sirt3 (Sirt3^-/-) promoted IVDD and poor pain-related behavioral scores via increasing oxidative stress-induced ferroptosis. The (immunoprecipitation coupled with mass spectrometry) IP/MS and co-IP demonstrated that USP11 was identified to stabilize Sirt3 via directly binding to Sirt3 and deubiquitinating Sirt3. Overexpression of USP11 significantly ameliorate oxidative stress-induced ferroptosis, thus relieving IVDD by increasing Sirt3. Moreover, knockout of USP11 in vivo (USP11^-/-) resulted in exacerbated IVDD and poor pain-related behavioral scores, which could be reversed by overexpression of Sirt3 in intervertebral disc. In conclusion, the current study emphasized the importance of the interaction of USP11 and Sirt3 in the pathological process of IVDD via regulating oxidative stress-induced ferroptosis, and USP11-mediated oxidative stress-induced ferroptosis is identified as a promising target for treating IVDD.

Trigonochinene E promotes lysosomal biogenesis and enhances autophagy via TFEB/TFE3 in human degenerative NP cells against oxidative stress

BACKGROUND

Macroautophagy (henceforth autophagy) is the major form of autophagy, which delivers intracellular cargo to lysosomes for degradation. Considerable research has revealed that the impairment of lysosomal biogenesis and autophagic flux exacerbates the development of autophagy-related diseases. Therefore, reparative medicines restoring lysosomal biogenesis and autophagic flux in cells may have therapeutic potential against the increasing prevalence of these diseases.

PURPOSE

The aim of the present study was thus to explore the effect of trigonochinene E (TE), an aromatic tetranorditerpene isolated from Trigonostemon flavidus, on lysosomal biogenesis and autophagy and to elucidate the potential underlying mechanism.

METHODS

Four human cell lines, HepG2, nucleus pulposus (NP), HeLa and HEK293 cells were applied in this study. The cytotoxicity of TE was evaluated by MTT assay. Lysosomal biogenesis and autophagic flux induced by 40 μM TE were analyzed using gene transfer techniques, western blotting, real-time PCR and confocal microscopy. Immunofluorescence, immunoblotting and pharmacological inhibitors/activators were applied to determine the changes in the protein expression levels in mTOR, PKC, PERK, and IRE1α signaling pathways.

RESULTS

Our results showed that TE promotes lysosomal biogenesis and autophagic flux by activating the transcription factors of lysosomes, transcription factor EB (TFEB) and transcription factor E3 (TFE3). Mechanistically, TE induces TFEB and TFE3 nuclear translocation through an mTOR/PKC/ROS-independent and endoplasmic reticulum (ER) stress-mediated pathway. The PERK and IRE1α branches of ER stress are crucial for TE-induced autophagy and lysosomal biogenesis. Whereas TE activated PERK, which mediated calcineurin dephosphorylation of TFEB/TFE3, IRE1α was activated and led to inactivation of STAT3, which further enhanced autophagy and lysosomal biogenesis. Functionally, knockdown of TFEB or TFE3 impairs TE-induced lysosomal biogenesis and autophagic flux. Furthermore, TE-induced autophagy protects NP cells from oxidative stress to ameliorate intervertebral disc degeneration (IVDD).

CONCLUSIONS

Here, our study showed that TE can induce TFEB/TFE3-dependent lysosomal biogenesis and autophagy via the PERK-calcineurin axis and IRE1α-STAT3 axis. Unlike other agents regulating lysosomal biogenesis and autophagy, TE showed limited cytotoxicity, thereby providing a new direction for therapeutic opportunities to use TE to treat diseases with impaired autophagy-lysosomal pathways, including IVDD.

Elucidating the Focal Immunomodulatory Clues Influencing Mesenchymal Stem Cells in the Milieu of Intervertebral Disc Degeneration

The intervertebral discs (IVDs) are a relatively mobile joint that interconnects vertebrae of the spine. Intervertebral disc degeneration (IVDD) is one of the leading causes of low back pain, which is most often related to patient morbidity as well as high medical costs. Patients with chronic IVDD often need surgery that may sometimes lead to biomechanical complications as well as augmented degeneration of the adjacent segments. Moreover, treatment modalities like rigid intervertebral fusion, dynamic instrumentation, as well as other surgical interventions are still controversial. Mesenchymal stem cells (MSCs) have exhibited to have immunomodulatory functions and the ability to differentiate into cartilage, making these cells possibly an epitome for IVD regeneration. Transplanted MSCs were able to repair IVDD back to the normal disc milieu via the activation of the generation of extracellular matrix (ECM) proteins such as aggrecan, proteoglycans and collagen types I and II. IVD milieu clues like, periostin, cluster of differentiation, tumor necrosis factor alpha, interleukins, chemokines, transforming growth factor beta, reactive oxygen species, toll-like receptors, tyrosine protein kinase receptor and disialoganglioside, exosomes are capable of influencing the MSCs during treatment of IVDD. ECM microenvironment clues above have potentials as biomarkers as well as accurate molecular targets for therapeutic intervention in IVDD.

Oxygen metabolism-balanced engineered hydrogel microspheres promote the regeneration of the nucleus pulposus by inhibiting acid-sensitive complexes

Intervertebral disc degeneration (IVDD) is commonly caused by imbalanced oxygen metabolism-triggered inflammation. Overcoming the shortcomings of antioxidants in IVDD treatment, including instability and the lack of targeting, remains challenging. Microfluidic and surface modification technologies were combined to graft chitosan nanoparticles encapsulated with strong reductive black phosphorus quantum dots (BPQDs) onto GelMA microspheres via amide bonds to construct oxygen metabolism-balanced engineered hydrogel microspheres (GM@CS-BP), which attenuate extracellular acidosis in nucleus pulposus (NP), block the inflammatory cascade, reduce matrix metalloproteinase expression (MMP), and remodel the extracellular matrix (ECM) in intervertebral discs (IVDs). The GM@CS-BP microspheres reduce H₂O₂ intensity by 229%. Chemical grafting and electrostatic attraction increase the encapsulation rate of BPQDs by 167% and maintain stable release for 21 days, demonstrating the antioxidant properties and sustained modulation of the BPQDs. After the GM@CS-BP treatment, western blotting revealed decreased acid-sensitive ion channel-3 and inflammatory factors. Histological staining in an 8-week IVDD model confirmed the regeneration of NP. GM@CS-BP microspheres therefore maintain a balance between ECM synthesis and degradation by regulating the positive feedback between imbalanced oxygen metabolism in IVDs and inflammation. This study provides an in-depth interpretation of the mechanisms underlying the antioxidation of BPQDs and a new approach for IVDD treatment.

Interleukin-18 Inhibition Protects Against Intervertebral Disc Degeneration via the Inactivation of Caspase-3/9 Dependent Apoptotic Pathways

BACKGROUND

The present study was designed to identify and understand the potential effectiveness of therapeutic target in intervertebral disc degeneration (IVDD) and its regulation mechanism.

METHODS

The role and mechanism of interleukin-18 (IL-18) in the disease were investigated. The IVDD degenerative nucleus pulposus (NP) tissues from the human and mouse models were used.A total of three groups of Male BALB/c mice were randomly made i.e control, IVDD, and IVDD+Ad-shIL-18 groups. After Ad-shIL-18 transfection, the expression of ECM synthesis related protein Aggrecan (ACAN) and Collagen II, apoptotic effector Caspases (Caspase-3, 8, 9, 12 and Cleaved-Caspase 3, 8, 9, 12), pro-apoptotic gene Bax and anti-apoptotic factors Bcl-2 in NP cells of the human were evaluated.

RESULTS

The results of our study revealed that the mRNA and protein expression levels of IL-18 were notably increased in the NP tissues of IVDD patients and mice models. In the IVDD mice model, Ad-sh-IL-18 treatment reversed the IVDD progression. The levels of Aggrecan and Collagen II, contributing to ECM degradation in NP cells, were also significantly increased. Additionally, Ad-sh-IL-18 could inhibit the NP cell's apoptosis via regulating the caspase-3/9 pathway.

CONCLUSION

The IL-18 knockdown via the caspase-3/9 pathway, might reduce the NP cell's death as well as the imbalance between catabolism and anabolism of ECM in IVDD.

Pretreatment of nucleus pulposus mesenchymal stem cells with appropriate concentration of H2O2 enhances their ability to treat intervertebral disc degeneration

Background

Nucleus pulposus mesenchymal stem cells (NPMSCs) transplantation is a promising treatment for intervertebral disc degeneration (IVDD). However, the transplanted NPMSCs exhibited weak cell proliferation, high cell apoptosis, and a low ability to resist the harsh microenvironment of the degenerated intervertebral disc. There is an urgent need to explore feasible methods to enhance the therapeutic efficacy of NPMSCs transplantation.

Objective

To identify the optimal concentration for NPMSCs pretreatment with hydrogen peroxide (H₂O₂) and explore the therapeutic efficacy of NPMSCs transplantation using H₂O₂ pretreatment in IVDD.

Methods

Rat NPMSCs were pretreated with different concentrations (range from 25 to 300 μM) of H₂O₂. The proliferation, reactive oxygen species (ROS) level, and apoptosis of NPMSCs were detected by cell counting kit-8 (CCK-8) assay, 5-ethynyl-2′-deoxyuridine (EdU) staining, and flow cytometry in vitro. The underlying signalling pathways were explored utilizing Western blotting. A rat needle puncture-stimulated IVDD model was established. X-ray, histological staining, and a multimode small animal live imaging system were used to evaluate the therapeutic effect of H₂O₂-pretreated NPMSCs in vivo.

Results

NPMSCs pretreated with 75 μM H₂O₂ demonstrated the strongest elevated cell proliferation by inhibiting the Hippo pathway (P < 0.01). Meanwhile, 75 μM H₂O₂-pretreated NPMSCs exhibited significantly enhanced antioxidative stress ability (P < 0.01), which is related to downregulated Brd4 and Keap1 and upregulated Nrf2. NPMSCs pretreated with 75 μM H₂O₂ also exhibited distinctly decreased apoptosis (P < 0.01). In vivo experiments verified that 75 μM H₂O₂-pretreated NPMSCs-transplanted rats exhibited an enhanced disc height index (DHI% = 90.00 ± 4.55, P < 0.01) and better histological morphology (histological score = 13.5 ± 0.5, P < 0.01), which means 75 μM H₂O₂-pretreated NPMSCs can better adapt to the environment of degenerative intervertebral discs and promote the repair of IVDD.

Conclusions

Pretreatment with 75 μM H₂O₂ was the optimal concentration to improve the proliferation, antioxidative stress, and antiapoptotic ability of transplanted NPMSCs, which is expected to provide a new feasible method to improve the stem cell therapy efficacy of IVDD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03031-7.

CB2R Attenuates Intervertebral Disc Degeneration by Delaying Nucleus Pulposus Cell Senescence through AMPK/GSK3β Pathway

Nucleus pulposus (NP) cell (NPC) senescence is one of the main causes of intervertebral disc degeneration (IVDD). However, the underlying mechanism of NPC senescence is still unclear. The cannabinoid type 2 receptor (CB2R) is a member of the cannabinoid system and plays an important role in antioxidative stress, anti-inflammatory and antisenescence activities. In this study, we used a hydrogen peroxide (H₂O₂)-induced NPC senescence model and a rat acupuncture IVDD model to explore the role of CB2R in IVDD in vitro and in vivo. First, we confirmed that the expression of p16INK4a in the NP tissues of IVDD patients and rat acupuncture IVDD models obviously increased accompanied by a decrease in CB2R expression. Subsequently, we found that activation of CB2R significantly reduced the number of SA-β-gal positive cells and suppressed the expression of p16INK4a and senescence-related secretory phenotypes [SASP, including matrix metalloproteinase 9 and 13 (MMP9, MMP13) and high mobility group protein b1 (HMGB1)]. In addition, activation of CB2R promoted the expression of collagen type II (Col-2) and SRY-Box transcription factor 9 (SOX9), inhibit the expression of collagen type X (Col-X), and restore the balance of extracellular matrix (ECM) metabolism. In addition, the AMPK/GSK3β pathway was shown to play an important role in CB2R regulation of NPC senescence. Inhibition of AMPK expression reversed the effect of JWH015 (a CB2R agonist). Finally, we further demonstrated that in the rat IVDD model, the AMPK/GSK3β pathway was involved in the regulation of CB2R on NPC senescence. In conclusion, our experimental results prove that CB2R plays an important role in NPC senescence. Activation of CB2R can delay NPC senescence, restore the balance of ECM metabolism, and attenuate IVDD.

SIRT1 alleviates IL-1β induced nucleus pulposus cells pyroptosis via mitophagy in intervertebral disc degeneration

Inflammatory stress of nucleus pulposus cells (NPCs) plays an important role in the pathogenesis of intervertebral disc degeneration (IVDD). Pyroptosis and NLRP3 inflammasome activation have been reported aggravating IVDD. SIRT1 is essential for mammalian cell survival and longevity by participating in various cellular processes. However, few studies analyzed the potential mechanism of SIRT1 in NLRP3- activated pyroptosis in NPCs. In this study, we confirmed that IL-1β could induce pyroptosis and NLRP3 inflammation activation, meanwhile, resulted in mitochondrial oxidative stress injury and dysfunction in NPCs. When the mitochondrial ROS was inhibited by Mito-Tempo, the pyroptosis and NLRP3 inflammation activation was also inhibited. SIRT1 overexpression could ameliorate IL-1β induced mitochondrial dysfunction and ROS accumulation, inhibit NLRP3 inflammasome activation by promoting PINK1/Parkin mediated mitophagy, however, these protective phenomena reversed by autophagy inhibitor 3-MA pretreatment. In vivo, SIRT1 agonist (SRT1720) treatment decreased the expression of NLRP3, p20, and IL-1β, increased the expression of PINK1 and LC3, delayed IVDD process in the rat model. Taken together, our results indicate that SIRT1 alleviates IL-1β induced NLRP3 inflammasome activation via mitophagy in NPCs, SIRT1 may be a potential therapeutic target to alleviate NLRP3- activated pyroptosis in the inflammatory stress related IVDD.

Circular RNA hsa_circ_0083756 promotes intervertebral disc degeneration by sponging miR-558 and regulating TREM1 expression

Objectives

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain. Circular RNAs (circRNAs) have been demonstrated to exert vital functions in IVDD. However, the role and mechanism of hsa_circ_0083756 in the development of IVDD remain unclear.

Materials and methods

RT‐qPCR was performed to detect expressions of hsa_circ_0083756, miR‐558 and TREM1 in nucleus pulposus (NP) tissues and cells. CCK8 assay, flow cytometry, TUNEL assay, RT‐qPCR and WB were used to clarify the roles of hsa_circ_0083756 in NP cells proliferation and extracellular matrix (ECM) formation. Bioinformatics analyses, dual‐luciferase reporter gene experiment, RNA immunoprecipitation (RIP) assay and FISH assay were performed to predict and verify the targeting relationship between hsa_circ_0083756 and miR‐558, as well as that between miR‐558 and TREM1. Ultimately, the effect of hsa_circ_0083756 on IVDD was tested through anterior disc‐puncture IVDD animal model in rats.

Results

hsa_circ_0083756 was upregulated in degenerative NP tissues and cells. In vitro loss‐of‐function and gain‐of‐function studies suggested that hsa_circ_0083756 knockdown promoted, whereas hsa_circ_0083756 overexpression inhibited NP cells proliferation and ECM formation. Mechanistically, hsa_circ_0083756 acted as a sponge of miR‐558 and subsequently promoted the expression of TREM1. Furthermore, in vivo study indicated that silencing of hsa_circ_0083756 could alleviate IVDD in rats.

Conclusions

hsa_circ_0083756 promoted IVDD via targeting the miR‐558/TREM1 axis, and hsa_circ_0083756 may serve as a potential therapeutic target for the treatment of IVDD.

Rac1 regulates nucleus pulposus cells degeneration and promotes the progression of intervertebral disc degeneration

Nucleus Pulposus Cells (NPCs) dysfunction is considered as an important event related to intervertebral disc degeneration (IVDD). In the present study, tandem mass spectrometry (TMT) was used to detect total protein expression of NP in patients with IVDD and healthy controls. Bioinformatic analysis was performed to identify differentially expressed proteins that may be involved in the degeneration of NP. The results show that Rac1 may be a key protein involved in the degeneration of NP via Wnt/β-catenin pathway activation. We investigated the influence of Rac1 on IVDD degeneration and associated mechanisms. This study has the potential to advance understanding of the mechanism of occurrence of degenerative NP tissues and provide novel strategies for slowing IVDD progression.

Comparison of Dorsal-to-Ventral Ratios of the Cervical Paraspinal Musculature in French Bulldogs With and Without Cervical Intervertebral Disk Disease and Two Other Breeds Based on CT Scan Measurements

Objective: To objectively assess the cervical paraspinal musculature of French bulldogs (FBs) using computed tomography (CT) scan-based measurements, outline differences in other breeds published in the literature, and investigate the potential influence of its cervical paraspinal musculature on predisposed sites for intervertebral disk disease.

Animals: Thirty FBs that underwent CT scans of the cervical spine from the skull to C7/T1 were enrolled. Fifteen dogs were patients suffering from intervertebral disk herniation (IVDH group), and 15 dogs underwent CT scans due to brachycephalic obstructive airway syndrome (BOAS group).

Methods: At the level of each cervical intervertebral disk from C2/C3 to C7/T1, measurements were performed and statistically analyzed. On the sagittal CT scan reconstruction, the height ratio of the dorsal to ventral paraspinal musculature and the angle of the disk axis to vertebral body length were assessed. On the transverse plane, the area ratio of the dorsal and ventral paraspinal musculature and the ratio of force moments were determined at each intervertebral disk level. Finally, ratios were compared to the values of Labrador retrievers and dachshunds published by Hartmann et al. (1).

Results: Comparing the two FB groups, one significant difference was detected in the mean height ratio of the dorsal to ventral paraspinal musculature at the level of C5/C6 (P = 0.0092) and C6/C7 (P = 0.0076), with IVDH FBs having the more prominent dorsal paraspinal musculature. At the level of C3/C4, a significantly less prominent dorsal paraspinal musculature in FBs than in dachshunds (P = 0.0058) and a significantly steeper disk to vertebral body angulation were observed (P = 0.0005).

Conclusion: Although some incidental differences were found, most parameters did not significantly differ between the BOAS and IVDH FBs. Significant conformational differences in the cervical paraspinal musculature and disk to vertebral body length angulation were found between FBs and two other breeds (chondrodystrophic and non-chondrodystrophic). This study's findings suggest that the paraspinal musculature is an additional biomechanical influencing factor on the preferential sites of IVDH in the cervical spine and that other major factors exist in IVDH development, especially in FBs.

N6-Methyladenosine Induced miR-34a-5p Promotes TNF-α-Induced Nucleus Pulposus Cell Senescence by Targeting SIRT1

Low back pain is tightly associated with intervertebral disc degeneration (IVDD) and aberrant nucleus pulposus (NP) is a critical cause. miRNAs N6-methyladenosine (m6A) modification accounts for the TNF-α-induced senescence of NP cells. The aim of this study was to investigate whether m6A modification regulates TNF-α-mediated cell viability, cell cycle arrest, and cell senescence and how it works. The results showed that METTL14 expression positively correlated with m6A and TNF-α expression in HNPCs. The knockdown of METTL14 led to the inhibition of the TNF-α-induced cell senescence. METTL14 overexpression promoted cell senescence. METTL14 regulated the m6A modification of miR-34a-5p and interacted with DGCR8 to process miR-34a-5p. The miR-34a-5p inhibitor inhibited the cell cycle senescence of HNPCs. miR-34a-5p was predicted to interact with the SIRT1 mRNA. SIRT1 overexpression counteracted the miR-34a-5p-promoted cell senescence. METTL14 participates in the TNF-α-induced m6A modification of miR-34a-5p to promote cell senescence in HNPCs and NP cells of IVDD patients. Downregulation of either METTL14 expression or miR-34a-5p leads to the inhibition of cell cycle arrest and senescence. SIRT1 mRNA is an effective binding target of miR-34a-5p, and SIRT1 overexpression mitigates the cell cycle arrest and senescence caused by miR-34a-5p.

Evaluation of the analgesic effect of fentanyl-ketamine and fentanyl-lidocaine constant rate infusions in isoflurane-anesthetized dogs undergoing thoracolumbar hemilaminectomy

OBJECTIVE

To evaluate anesthetic conditions and postoperative analgesia with the use of intraoperative constant rate infusions (CRIs) of fentanyl-lidocaine or fentanyl-ketamine in dogs undergoing thoracolumbar hemilaminectomy.

STUDY DESIGN

Prospective, randomized, blinded, clinical study.

ANIMALS

A total of 32 client-owned dogs.

METHODS

Dogs were premedicated with fentanyl (5 μg kg^-1) administered intravenously (IV), anesthesia was induced with IV alfaxalone and maintained with isoflurane. Fentanyl (0.083 μg kg^-1 minute^-1) was infused IV with either ketamine (0.5 mg kg^-1; then 40 μg kg^-1 minute^-1; group KF) or lidocaine (2 mg kg^-1; then 200 μg kg^-1 minute^-1; group LF) assigned randomly. Heart rate, noninvasive arterial pressures, respiratory rate, esophageal temperature, end-tidal partial pressure of carbon dioxide and isoflurane concentration were recorded throughout anesthesia. Maintenance of anesthesia, recovery and postoperative pain (Glasgow Composite Pain Scale) were scored. Cardiopulmonary data were analyzed using a two-way anova with repeated measures, demographics of the two groups with a t test, and scores with Mann-Whitney U test, with p < 0.05.

RESULTS

All dogs recovered from anesthesia without complications. No significant difference was found between groups for cardiopulmonary variables, total anesthesia time, sedation score and requirement for postoperative sedation or for rescue analgesia. Anesthetic maintenance score was of lower quality in KF than in LF [median (interquartile range): 0 (0-0.5) versus 0 (0-0); p = 0.032)], but still considered ideal. Recovery score was higher and indicative of less sedation in LF than in KF [1 (1-1.5) versus 0.5 (0-1); p < 0.0001]. Pain score was higher in KF than in LF [2 (1-3) versus 1 (1-2); p = 0.0009].

CONCLUSIONS AND CLINICAL RELEVANCE

Both CRIs of KF and LF provided adequate anesthetic conditions in dogs undergoing thoracolumbar hemilaminectomy. Based on requirement for rescue analgesia, postoperative analgesia was adequate in both groups.

Breeding schemes for intervertebral disc disease in dachshunds: Is disc calcification score preferable to genotyping of the FGF4 retrogene insertion on CFA12?

Background

Approximately every fifth Dachshund is affected by disc herniation - a painful, hereditary condition which is typically preceded by disc calcification. Therefore, the selection of dogs suitable for breeding can be based on radiographic examination of calcification status.

Recently, an insertion of an FGF4 retrogene on CFA12 has been identified and associated with the risk of developing disc herniation in chondrodystrophic breeds and a DNA test is now offered.

In this study we investigate the incidence of disc herniation in the smooth-haired, long-haired and wire- haired Dachshund populations. We also evaluate and compare the accuracy of the two breeding schemes predicting the risk of disc herniation: the DNA test and the radiography based scheme.

Results

The overall incidence of disc herniation in Danish Dachshunds was 18% and no significant difference was found between the long-haired (17%), smooth-haired (22%) and wire-haired (16%) populations (p > 0.05). We found a significant association (p <  0.0001) between calcification status and the risk of disc herniation with a relative risk of 14.78. Using calcification status (≥ 5 or <  5 calcifications) as a risk indicator has a sensitivity of 0.79 and a specificity of 0.91.

A significant association between the FGF4 retrogene insertion and the disc calcification status was found in the wire-haired population (p <  0.0001) where the DNA test has a sensitivity of 1.0 and a specificity of 0.14. In the long- and smooth-haired populations no association was found (p > 0.05) and here the insertion allele was almost fixed.

Conclusion

Our results show that the FGF4 retrogene insertion on CFA12 is not a valid risk indicator on its own. Relying on the DNA test will have an irreversible effect on the Dachshund breed excluding almost all dogs from breeding. Thus, using calcification status remains the most reliable breeding scheme for disc herniation in Dachshunds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40575-020-00096-6.

Fibronectin Fragments and Inflammation During Canine Intervertebral Disc Disease

Background: Canine intervertebral disc disease (IVDD) represents a significant clinical problem in veterinary medicine, with similarities to the human pathology. Host-derived damage-associated molecular patterns like fibronectin fragments (FnF) that develop during tissue dysfunction may be of specific relevance to IVD pathologies by inducing an inflammatory response in resident cells. Aim: This project aimed to determine the presence and pathobiological role of FnF during IVD herniation in dogs, with a focus on inflammation. Methods: Herniated nucleus pulposus (NP) material from five dogs as well as non-herniated adjacent NP material from three dogs was collected during spinal surgery required due to acute IVD herniation. The presence of different types of FnF were determined by Western blot analysis. NP cells isolated from six herniated canine IVDs were then exposed to 30 kDa FnF. NP cell inflammation and catabolism was examined by investigating the expression of IL-1β, IL-6, IL-8, and COX-2, as well as MMP-1 and MMP-3 by qPCR (all targets) and ELISA (IL-6, PGE₂). Results: Amongst multiple sized FnF (30, 35, 45, and >170kDa), N-terminal fragments at a size of ~30 kDa were most consistently expressed in all five herniated IVDs. Importantly, these fragments were exclusively present in herniated, but not in non-herniated IVDs. Exposure of canine NP cells to 500 nM 30 kDa FnF caused a significant upregulation of IL-6 (62.5 ± 79.9, p = 0.032) and IL-8 (53.0 ± 75.7, p = 0.031) on the gene level, whereas IL-6 protein analysis was inconclusive. Donor-donor variation was observed in response to FnF treatment, whereby this phenomenon was most evident for COX-2, with three donors demonstrating a significant downregulation (0.67 ± 0.03, p = 0.003) and three donors showing upregulation (6.9 ± 5.5, p = 0.21). Co-treatment with Sparstolonin B, a TRL-2/TRL-4 antagonist, showed no statistical difference to FnF treatment alone in all tested target genes. Conclusion: Given the presence of the 30 kDa FnF in canine herniated IVDs and the proinflammatory effect of 30 kDa FnF on NP cells, we concluded that the accumulation of FnF may be involved in the pathogenesis of canine IVDD. These results correspond to the findings in humans with IVDD.

Mesenchymal stem cells-derived exosomes ameliorate intervertebral disc degeneration through inhibiting pyroptosis

Mesenchymal stem cell (MSCs)‐based therapies have shown a promised result for intervertebral disc degeneration (IVDD) treatment. However, its molecular mechanisms remain unclear. Exosomes involve cell‐cell communication via transference of its contents among different cells, and the present potential effect on cell death regulation. This study aimed to investigate the role of MSCs‐derived exosomes on IVDD formation. Here, we first found the NLRP3‐mediated nucleus pulposus cell (NP cell) pyroptosis was activated in the IVDD mice model and lipopolysaccharide (LPS)‐induced model. However, MSCs treatment could inhibit NP cell pyroptosis in vitro. We then isolated MSCs‐derived exosomes by differential centrifugation and identified the characteristics. Secondly, we investigated the function of MSCs‐derived exosomes on LPS‐induced NP cell pyroptosis. Finally, we presented evidence that MSCs‐derived exosomal miR‐410 was a crucial regulator of pyroptosis. Results showed that MSCs‐derived exosomes play an anti‐pyroptosis role by suppressing the NLRP3 pathway. Moreover, it suggested that this effect was attributed to miR‐410, which was derived from MSCs‐exosomes and could directly bind to NLRP3mRNA. In conclusion, for the first time, we demonstrated that MSCs‐exosome treatment may inhibit pyroptosis and could be a promising therapeutic strategy for IVDD.

The therapeutic effect of TBK1 in intervertebral disc degeneration via coordinating selective autophagy and autophagic functions

Introduction

While its innate immune function has been known, recent works of literature have focused on the role of Tank binding kinase 1 (TBK1) in regulating autophagy and it is unknown whether TBK1 protects against intervertebral disc degeneration (IVDD) through affecting autophagy.

Objectives

Here, we aim to explore whether TBK1 is implicated in the pathogenesis of IVDD, and investigated the potential mechanism.

Methods

Western blotting and immunohistochemistry were used to detect the TBK1 expression in human and rat NP tissue. After TBK1 overexpression in NP cells with lentivirus transfection, autophagic flux, apoptosis and senescence percentage were assessed. Si-RNA , a utophagy inhibitors and protein phosphatase inhibitors were applied to study the mechanism of autophagy regulation. In vivo study, we further evaluated the therapeutic action of lentivirus-TBK1(Lv-TBK1)injection in a rodent IVDD model.

Results

The TBK1 level was reduced in rat and human NP tissue. TBK1 overexpression protected against apoptosis and premature senescence. These functions of TBK1 were abolished by chloroquine-medicated autophagy inhibition.P-TBK1, an activation form of TBK, is involved in selective autophagy through directly phosphorylating P62 at Ser 403, and the activation of TBK1 is also dependent on Parkin manner. TBK1 also activated NPCs autophagy to relieve puncture injury in vivo.

Conclusion

We demonstrated that TBK1 overexpression attenuated senescence and apoptosis and promoted NPCs survival via upregulating autophagy. TBK1 represents a promising avenue for IVDD treatment.

Mfn2 is involved in intervertebral disc degeneration through autophagy modulation

OBJECTIVE

To explore whether Mitofusin 2 (Mfn2) is implicated in the pathogenesis of intervertebral disc degeneration (IVDD).

METHODS

We detected the protein content of Mfn2 in degenerated human nucleus pulposus (NP) tissues and investigated the effects of Mfn2 knockdown and Mfn2 overexpression on rat nucleus pulposus cells (NPCs) under oxidative stress by using a range of biological techniques. Afterwards, we confirmed the effects of Mfn2 overexpression on NPCs in vivo and further evaluated the therapeutic action of adenovirus (AV)-Mfn2 injection in a rodent IVDD model.

RESULTS

Mfn2 expression was decreased in human NP tissues during IVDD. Mfn2 knockdown aggravated the impairment of autophagic flux, mitochondrial dysfunction and cellular apoptosis in rat NPCs after Tert-Butyl hydroperoxide (TBHP) treatment, while Mfn2 overexpression significantly reversed these alterations. Besides, Mfn2 overexpression promoted an ROS (reactive oxygen species)-dependent mitophagy via PINK1 (PTEN-induced putative kinase 1)/Parkin pathway in TBHP-treated NPCs. Inhibition of autophagy with chloroquine (CQ) disordered the protective effects of Mfn2 overexpression on NPCs. Furthermore, Mfn2 overexpression in discs by AV-Mfn2 injection ameliorated the development of IVDD in rats.

CONCLUSION

Mfn2 repression is deeply involved in the pathogenesis of IVDD with its impairment on autophagy, leading to the aggravation of mitochondrial dysfunction and apoptotic cell death, which ought to be a promising therapeutic target for IVDD.

BRD4 inhibition regulates MAPK, NF-κB signals, and autophagy to suppress MMP-13 expression in diabetic intervertebral disc degeneration

Diabetes mellitus may lead to intervertebral disc degeneration (IVDD). Matrix metalloproteinase-13 (MMP-13) is one of the major catabolic factors in extracellular matrix (ECM) metabolism of nucleus pulposus cells (NPCs) and contributes to diabetic IVDD. Bromodomain-containing protein 4 (BRD4) is a member of the bromodomain and extraterminal protein family and is implicated in chronic inflammation. Here, we report that the expression of BRD4 and MMP-13 was elevated in diabetic nucleus pulposus tissues as well as in advanced glycation end products (AGEs)-treated NPCs; also, the regulatory effect of BRD4 on MMP-13 was studied. We found that MMP-13 was regulated by MAPK and NF-κB signaling as well as autophagy in AGEs-treated NPCs. Next, we explored the role of BRD4 in regulation of MAPK, NF-κB signaling, and autophagy. The results showed that BRD4 is the upstream regulator of all of these 3 factors, and inhibition of BRD4 may suppress MAPK and NF-κB signaling while activating autophagy in AGEs-treated NPCs. Finally, we demonstrated that BRD4 inhibition may suppress MMP-13 expression in diabetic NPCs in vitro as well as in vivo; meanwhile, it may preserve ECM in diabetic rats. Our study demonstrates that inhibition of BRD4 may suppress MAPK and NF-κB signaling and activate autophagy to suppress MMP-13 expression in diabetic IVDD, and diabetic IVDD may be compromised by BRD4 inhibitors.-Wang, J., Hu, J., Chen, X., Huang, C., Lin, J., Shao, Z., Gu, M., Wu, Y., Tian, N., Gao, W., Zhou, Y., Wang, X., Zhang, X. BRD4 inhibition regulates MAPK, NF-κB signals, and autophagy to suppress MMP-13 expression in diabetic intervertebral disc degeneration.

Laser Therapy for Incision Healing in 9 Dogs

Laser therapy is becoming common place in veterinary medicine with little evidence proving efficacy or dosages. This study evaluated surgical wound healing in canines. Twelve Dachshunds underwent thoraco-lumbar hemilaminectomies for intervertebral disc disease (IVDD). Digital photographs were taken of their incisions within 24 h of surgery and 1, 3, 5, 7, and 21 days postoperatively. The first three dogs were used to create a standardized scar scale to score the other dogs' incision healing. The remaining 9 dogs were randomly assigned to either receive 8 J/cm2 laser therapy once a day for 7 days or the non-laser treated control group. Incision healing was scored based on the scar scale from 0 to 5, with zero being a fresh incision and five being completely healed with scar contraction and hair growth. All scar scores significantly improved with increasing time from surgery (<0.001). Good agreement was achieved for inter-rater reliability (p = 0.9). Laser therapy increased the scar scale score, showed improved cosmetic healing, by day seven and continued to be significantly increased on day 21 compared to control dogs (p < 0.001). Daily application of laser therapy at 8J/cm2 hastened wound healing in Dachshunds that received thoracolumbar hemilaminectomies for IVDD. It also improved the cosmetic appearance.

Neuter status as a risk factor for canine intervertebral disc herniation (IVDH) in dachshunds: a retrospective cohort study

BACKGROUND

Intervertebral disc herniation (IVDH) involves displacement of the intervertebral disc secondary to disc degeneration and is extremely common in dachshunds. Clinical signs include pain with or without paresis or paralysis. Mortality rate is high and some cases are left with permanent disability even after treatment. Aims of this study were twofold: Firstly, to investigate whether neutering, i.e. gonadectomy, is associated with increased risk of IVDH in dachshunds, and secondly to investigate whether age of neutering alters risk of IVDH in this breed.Information was obtained for 1964 dachshunds from the owner survey, "Dachslife 2015". For dachshunds that were ≥ 3 years and < 10 years old at the time of the survey (1073 individuals) incidence of IVDH was compared between early-neutered (< 12 months), late-neutered (> 12 months) and entire animals of each gender.

RESULTS

Neutered females were at significantly higher risk of IVDH than entire females (risk ratio 1.81, 95% CI 1.28-2.54). For males, incidence of IVDH in neutered as compared with entire dachshunds was increased but this difference was not quite statistically significant (risk ratio 1.38, 95% CI 0.96-1.99).For both genders, this study demonstrated significantly increased risk of IVDH in early-neutered dachshunds (before 12 months old) as compared with those neutered late (after 12 months old). For early neutered males, risk ratio was 1.54 (95% CI 1.07-2.22). For early-neutered females, risk ratio was 2.12 (95% CI 1.44-3.11).

CONCLUSION

Results from this retrospective study suggest that gonadectomy, especially if performed before 12 months old, increases risk of IVDH in this breed. Decisions regarding neutering should be made on an individual basis, taking a range of pros and cons into account. Considering the high prevalence, morbidity and mortality of IVDH in dachshunds, increased IVDH risk associated with neutering is a key factor to consider in deciding whether and when to neuter.

Association Between Natural Killer Cell Activity and Colorectal Cancer in High-Risk Subjects Undergoing Colonoscopy

BACKGROUND & AIMS

Low activity of natural killer (NK) cells has been associated with increased risk of cancer and has been reported in patients with colorectal cancer (CRC). Activity of NK cells can be measured in a small volume of whole blood by a commercially available test. We investigated whether this test could be used to identify patients with CRC, using findings from colonoscopy as a reference standard.

METHODS

We performed an open-label, prospective, cross-sectional study of 872 high-risk subjects (more than 40 years old) screened for CRC by colonoscopy at a university hospital in Montreal, Canada from October 2014 through January 2016. Blood samples were collected on the day of colonoscopy, prior to the procedure. The test involves stimulation of whole blood with cytokine that induces NK cells to secrete interferon gamma (IFNG), which is quantified by an ELISA. Tissue samples were taken from lesions during the colonoscopy and analyzed histologically; subjects were classified as having no evidence of disease, adenomatous polyps of less than 10 mm, of 10 mm or more, or CRC. We used the non-parametric Mann-Whitney test to compare NK cell activity between subjects with no evidence of CRC and subjects found to have CRC. Receiver operating characteristic curve analysis was used to assess the ability of the test to identify individuals with CRC. The primary objective was to determine the difference in NK cell activity between subjects with vs without CRC. The secondary objective was the test performance, based on receiver operating characteristic analysis, and cut-off value that most accurately identified individuals with CRC.

RESULTS

We found a significant difference in NK cell activity between the 23 subjects with CRC (based on pathology analysis) and the 849 subjects without CRC: subjects found to have CRC by colonoscopy had a median level of 86.0 pg IFNG/mL (inter-quartile range, 43.3-151.0 pg IFNG/mL), whereas subjects without CRC had a median level of 298.1 pg IFNG/mL (inter-quartile range, 100.4-920.2 pg IFNG/mL) (P = .0002). The cut-off value that most accurately identified subjects with CRC was 181 pg/mL. The NK cell activity test identified subjects with CRC with 87.0% sensitivity, 60.8% specificity, a positive predictive value of 5.7%, and a negative predictive value of 99.4%. The odds ratio for detection of CRC in subjects with low NK cell activity vs subjects with higher NK cell activity was 10.3 (95% CI, 3.03-34.9).

CONCLUSIONS

Using colonoscopy as the reference standard, a test for NK cell activity in whole blood samples identified patients with CRC with 87.0% sensitivity and a negative predictive value of 99.4%. Subjects with low NK cell activity had a 10-fold higher risk of CRC compared with subjects with high NK cell activity. This test might be used in clinical practice to assess patients for risk of CRC. Clinicaltrials.gov number: NCT02291198.

DachsLife 2015: an investigation of lifestyle associations with the risk of intervertebral disc disease in Dachshunds

BACKGROUND

Intervertebral disc disease (IVDD) represents a major problem in the Dachshund, with at a relative risk of IVDD 10-12 times higher than other breeds, and an estimated 19-24 % of Dachshunds showing clinical signs related to IVDD during their lifetime. A variety of genetic, physical and lifestyle-related risk factors for IVDD have previously been identified, with some conflicting findings. As such, advising owners and breeders regarding best-practice for IVDD prevention is challenging at present. This study aimed to (i) estimate prevalence of IVDD in six Dachshund varieties, and (ii) identify risk factors associated with IVDD diagnosis from a wide variety of demographic, conformational, dietary, activity and exercise-related variables.

RESULTS

A web-based survey "Dachs-Life 2015" was carried out from January-April 2015, with responses received for 2031 individual Dachshunds. Three-hundred and ten dogs were classed as Cases based on veterinary-diagnosis of IVDD, and 56 dogs were excluded from further analyses due to a lack of veterinary-diagnosis of their clinical signs. The remaining1665 dogs with no previous signs of IVDD were classified as Non-Cases. The overall prevalence of IVDD was 15.7 % (95 % CI: 14.1-17.3). Breed variety was significantly associated with IVDD risk, with the highest prevalence seen in the Standard Smooth-Haired (24.4 %, 95 % CI: 22.5-26.3) and lowest in the Standard Wire-Haired (7.1 %, 95 % CI: 6.0-8.2). Older dogs and neutered dogs were at increased odds of IVDD. Of the lifestyle risk factors, univariable analysis identified dogs that exercised for <30 min per day, were not allowed to jump on and off furniture, or were supplemented with glucosamine or chondroitin were at increased odds of IVDD, whereas dogs that exercised for more than 1 h per day, that were considered highly or moderately active by their owners, and those that showed at Open or Championship shows were at decreased odds of IVDD.

CONCLUSIONS

In line with previous reports, IVDD is commonly diagnosed in the Dachshund, with significant differences in prevalence between Dachshund varieties. Lifestyle risk factors were identified which are hypothesis-generating for future prospective studies, and can inform an evidence-based approach to mitigating IVDD risk for Dachshund owners and breeders.

Severity of spinal cord dysfunction and pain associated with hydrated nucleus pulposus extrusion in dogs

OBJECTIVE

To identify the severity of neurological deficits, presence of signs of cervical pain, and the site of intervertebral disc space extrusion in 21 dogs diagnosed via magnetic resonance imaging (MRI) with a hydrated nucleus pulposus extrusion (HNPE) and compare those findings to dogs with other compressive cervical myelopathies.

METHODS

Medical records and MRI findings were reviewed in dogs that were presented to two veterinary hospitals between 2006 and 2012 and subsequently diagnosed by MRI to have a HNPE (n = 21) or other compressive cervical myelopathies originating from the intervertebral disc (n = 174). Information obtained included signalment, severity of neurological deficits, presence of signs of neck pain, and site of HNPE. The severity of clinical neurological spinal cord dysfunction was determined for each dog in both groups using the Frankel scoring system (0-4). The MRI were reviewed for confirmation of diagnosis and site of HNPE. An ANOVA was used to compare age between groups and a Mann-Whitney test for pairwise comparisons of the Frankel score between groups. Values of p <0.05 were considered statistically significant.

RESULTS

Significantly more severe Frankel scores and less severe signs of cervical pain detected on palpation were observed in dogs with a HNPE as compared to dogs with other compressive myelopathies. The sites of HNPE were C3-C4 (8/21), C4-C5 (12/21), and C5-C6 (1/21).

CLINICAL SIGNIFICANCE

Dogs affected with HNPE have more severe clinical neurological deficits and less severe signs of cervical pain as compared to dogs with other compressive cervical myelopathies.