Toll-like receptor 4/nuclear factor-kappa B pathway is involved in radicular pain by encouraging spinal microglia activation and inflammatory response in a rat model of lumbar disc herniation

Animal Models of Intervertebral Disc Diseases: Advantages, Limitations, and Future Directions

Animal models are valuable tools for studying the underlying mechanisms of and potential treatments for intervertebral disc diseases. In this review, we discuss the advantages and limitations of animal models of disc diseases, focusing on lumbar spinal stenosis, disc herniation, and degeneration, as well as future research directions. The advantages of animal models are that they enable controlled experiments, long-term monitoring to study the natural history of the disease, and the testing of potential treatments. However, they also have limitations, including species differences, ethical concerns, a lack of standardized protocols, and short lifespans. Therefore, ongoing research focuses on improving animal model standardization and incorporating advanced imaging and noninvasive techniques, genetic models, and biomechanical analyses to overcome these limitations. These future directions hold potential for improving our understanding of the underlying mechanisms of disc diseases and for developing new treatments. Overall, although animal models can provide valuable insights into pathophysiology and potential treatments for disc diseases, their limitations should be carefully considered when interpreting findings from animal studies.

TLR-4: a promising target for chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) affects a significant majority of cancer patients, with up to 80% experiencing this severe and dose-limiting side effect while undergoing anti-cancer treatment. CIPN can be induced by a variety of drugs commonly employed in the management of both solid tumors and hematologic cancers. The inadequacies in comprehending the pharmacological interventions associated with CIPN and the subsequent signaling pathways have significantly contributed to the disappointing outcomes of several drugs in clinical trials. Recent investigations in pain research have demonstrated a growing inclination toward addressing neuro-inflammation as a strategy for managing chronic pain conditions. Notably, toll-like receptor-4 (TLR-4) has emerged as a key player in immune system activation and is undergoing extensive research. In this review, we emphasize the potential role of TLR-4 in neuropathic pain, highlighting its promise as a target for CIPN treatment. Furthermore, we explore and analyse the intricate interplay between TLR-4, diverse immune cells, downstream pathways, and receptors within the context of CIPN. A comprehensive exploration of these interactions provides valuable insights into the central role of TLR-4 in CIPN development, paving the way for potential ground-breaking therapeutic approaches to alleviate this debilitating condition.

Comparative effect of atorvastatin and risperidone on modulation of TLR4/NF-κB/NOX-2 in a rat model of valproic acid-induced autism

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is significantly increasing, resulting in severe distress. The approved treatment for ASD only partially improves the sympoms, but it does not entirely reverse the symptoms. Developing novel disease-modifying drugs is essential for the continuous improvement of ASD. Because of its pleiotropic effect, atorvastatin has been garnered attention for treating neuronal degeneration. The present study aimed to investigate the therapeutic effects of atorvastatin in autism and compare it with an approved autism drug (risperidone) through the impact of these drugs on TLR4/NF-κB/NOX-2 and the apoptotic pathway in a valproic acid (VPA) induced rat model of autism.

METHODS

On gestational day 12.5, pregnant rats received a single IP injection of VPA (500 mg/kg), for VPA induced autism, risperidone and atorvastatin groups, or saline for control normal group. At postnatal day 21, male offsprings were randomly divided into four groups (n = 6): control, VPA induced autism, risperidone, and atorvastatin. Risperidone and atorvastatin were administered from postnatal day 21 to day 51. The study evaluated autism-like behaviors using the three-chamber test, the dark light test, and the open field test at the end of the study. Biochemical analysis of TLR4, NF-κB, NOX-2, and ROS using ELISA, RT-PCR, WB, histological examination with hematoxylin and eosin and immunohistochemical study of CAS-3 were performed.

RESULTS

Male offspring of prenatal VPA-exposed female rats exhibited significant autism-like behaviors and elevated TLR4, NF-κB, NOX-2, ROS, and caspase-3 expression. Histological analysis revealed structural alterations. Both risperidone and atorvastatin effectively mitigated the behavioral, biochemical, and structural changes associated with VPA-induced rat model of autism. Notably, atorvastatin group showed a more significant improvement than risperidone group.

CONCLUSIONS

The research results unequivocally demonstrated that atorvastatin can modulate VPA-induced autism by suppressing inflammation, oxidative stress, and apoptosis through TLR4/NF-κB/NOX-2 signaling pathway. Atorvastatin could be a potential treatment for ASD.

Oral application of magnesium-L-threonate alleviates radicular pain by inhibiting neuro-inflammation dependent central sensitization of rats

BACKGROUND

We have reported neuro-inflammation is involved in radicular pain by enhancing the efficiency of pain synaptic transmission in spinal level. Recently, peers' studies have confirmed that magnesium deficiency leads to neuro-inflammation, thus contributes to memory and emotional deficits and pain hypersensitivity in antineoplastic agents treated rats. In this study, we explore the effect of oral application of magnesium-L-threonate (L-TAMS) in radicular pain induced by lumbar disc herniation (LDH) of rats and the possible mechanisms.

METHODS

Rat model of LDH was induced by autologous nucleus pulposus (NP) implantation. Mechanical and thermal pain thresholds were assessed by von Frey filaments and hotplate test respectively. L-TAMS was applied from drinking water at dosage of 604 mg/kg/day from 2 day before NP implantation and until the end of the experiment. Free Mg2+ content in serum and cerebrospinal fluid (CSF) was measured by calmagite chromometry. Synaptic transmission efficiency was determined by C-fiber evoked field potentials recorded by electrophysiologic recording in vivo. The activation of microglia in spinal dorsal horn was displayed by immunofluorescence staining and western blotting. The expressions of pro-inflammatory cytokines and glutamic N-methyl-D-aspartate receptor (NMDAR) subunits (NR2A, NR2B) were assessed by western blotting and enzyme-linked immunosorbent assay (ELISA) respectively.

RESULTS

NP implantation induced mechanical allodynia and thermal hyperalgesia, accompanied by decreased Mg2+ concentration in serum and CSF which were both obscured by oral application of L-TAMS. L-TAMS inhibited spinal microglia activation and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) expression of rats with NP. L-TAMS decreased C-fiber evoked potentials and NR2B protein level in rats with NP, which were rescued by extra intrathecal delivery of TNF-α or IL-6 or IL-1β.

CONCLUSIONS

Oral application of L-TAMS alleviates radicular pain by inhibiting neuro-inflammation dependent central sensitization of rats.

Exosomes derived from human urine-derived stem cells ameliorate IL-1β-induced intervertebral disk degeneration

BACKGROUND

Human intervertebral disk degeneration (IVDD) is a sophisticated degenerative pathological process. A key cause of IVDD progression is nucleus pulposus cell (NPC) degeneration, which contributes to excessive endoplasmic reticulum stress in the intervertebral disk. However, the mechanisms underlying IVDD and NPC degeneration remain unclear.

METHODS

We used interleukin (IL)-1β stimulation to establish an NPC-degenerated IVDD model and investigated whether human urine-derived stem cell (USC) exosomes could prevent IL-1β-induced NPC degeneration using western blotting, quantitative real-time polymerase chain reaction, flow cytometry, and transcriptome sequencing techniques.

RESULTS

We successfully extracted and identified USCs and exosomes from human urine. IL-1β substantially downregulated NPC viability and induced NPC degeneration while modulating the expression of SOX-9, collagen II, and aggrecan. Exosomes from USCs could rescue IL-1β-induced NPC degeneration and restore the expression levels of SOX-9, collagen II, and aggrecan.

CONCLUSIONS

USC-derived exosomes can prevent NPCs from degeneration following IL-1β stimulation. This finding can aid the development of a potential treatment strategy for IVDD.

Okadaic acid enhances NfKB, TLR-4, caspase 3, ERK ½, c-FOS, and 8-OHdG signaling pathways activation in brain tissues of zebrafish larvae

This study was designed to investigate the potential neuronal damage mechanism of the okadaic acid (OA) in the brain tissues of zebrafish embryos by evaluating in terms of immunofluorescence of Nf KB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG signaling pathways. We also evaluated body malformations. For this purpose, zebrafish embryos were exposed to 0.5 μg/ml, 1 μg/ml and 2.5 μg/ml of OA for 5 days. After application, FITC/GFP labeled protein-specific antibodies were used in immunofluorescence assay for NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG respectively. The results indicated that OA caused immunofluorescence positivity of NfKB, TLR-4, caspase 3, ERK ½, c-FOS and 8-OHdG in a dose-dependent manner in the brain tissues of zebrafish embryos. Pericardial edema (PE), nutrient sac edema (YSE) and body malformations, tail malformation, short tail and head malformation (BM) were detected in zebrafish embryos. These results suggest that OA induces neuronal damage by affecting the modulation of DNA damage, apoptotic, and inflammatory activities in the brain tissues of zebrafish embryos. The increase in signaling pathways shows that OA can cause damage in the structure and function of brain nerve cells. Our results provide a new basis for the comprehensive assessment of the neural damage of OA and will offer enable us to better understand molecular the mechanisms underlying the pathophysiology of OA toxicity.

Pulsed radiofrequency of lumbar dorsal root ganglion for lumbar radicular pain: A systematic review and meta-analysis

BACKGROUND

Pulsed radiofrequency (PRF) of the lumbar dorsal root ganglion (DRG) has been widely used as a method to relieve lumbar radicular pain (LRP). However, the value of PRF application in LRP patients remains uncertain. This systematic review aimed to compare the effects of PRF of lumbar DRG and LEI in patients with LRP.

METHODS

A literature search was performed using well-known databases for articles published up to May 2023. We included randomized controlled trials (RCTs) that evaluated the effects of PRF compared to LEI with or without steroids. We screened articles, extracted data, and assessed risk of bias in duplicate. The pain scores and Oswestry Disability Index (ODI) scores at 1, 3, and 6 months after procedures were obtained. A random-effects meta-analysis model was applied for outcomes. We evaluated evidence certainty for each outcome using the GRADE scoring system. This review was registered in the PROSPERO (ID: CRD42021253628).

RESULTS

A total of 10 RCTs were included and data of 613 patients were retrieved. We assessed the overall quality of the evidence as very low to moderate. PRF showed no difference in pain scores at 1 (mean difference [MD] -0.80, 95% confidence interval [CI] -1.59 to 0.00, low certainty) and 6 months (MD -2.37, 95% CI -4.79 to 0.05, very low certainty), and significantly improved pain scores at 3 months (MD -1.31, 95% CI -2.29 to -0.33, low certainty). There was no significant difference in ODI score at any interval (very low to low certainty). In the subgroup who underwent a diagnostic block, did not use steroids, and PRF duration greater than 360 s, PRF significantly reduced pain scores at 3 months after procedures.

CONCLUSIONS

We found low quality of the evidence supporting adjuvant PRF to the lumbar DRG has a greater analgesic effect at 3 months after procedures in patients with LRP than LEI. We identified no convincing evidence to show that this treatment improves function. High-quality evidence is lacking, and data were largely derived from short-term effects. Given these limitations, high-quality trials with data on long-term effects are needed.

Biphasic release of betamethasone from an injectable HA hydrogel implant for alleviating lumbar disc herniation induced sciatica

Epidural steroid injection (ESI) is a common therapeutic approach for managing sciatica caused by lumbar disc herniation (LDH). However, the short duration of therapeutic efficacy and the need for repeated injections pose challenges in LDH treatment. The development of a controlled delivery system capable of prolonging the effectiveness of ESI and reducing the frequency of injections, is highly significant in LDH clinical practice. In this study, we utilized a thiol-ene click chemistry to create a series of injectable hyaluronic acid (HA) based release systems loaded with diphasic betamethasone, including betamethasone dipropionate (BD) and betamethasone 21-phosphate disodium (BP) (BD/BP@HA). BD/BP@HA hydrogel implants demonstrated biocompatibility and biodegradability to matched neuronal tissues, avoiding artificial compression following injection. The sustained release of betamethasone from BD/BP@HA hydrogels effectively inhibited both acute and chronic neuroinflammation by suppressing the nuclear factor kappa-B (NF-κB) pathway. In a mouse model of LDH, the epidural administration of BD/BP@HA efficiently alleviated LDH-induced sciatica for at least 10 days by inhibiting the activation of macrophages and microglia in dorsal root ganglion and spinal dorsal horn, respectively. The newly developed HA hydrogels represent a valuable platform for achieving sustained drug release. Additionally, we provide a simple paradigm for fabricating BD/BP@HA for epidural injection, demonstrating greater and sustained efficiency in alleviating LDH-induced sciatica compared to traditional ESI and displaying potentials for clinical translation. This system has the potential to revolutionize drug delivery for co-delivery of both soluble and insoluble drugs, thereby making a significant impact in the pharmaceutical industry. STATEMENT OF SIGNIFICANCE: Lumbar disc herniation (LDH) is a common degenerative disorder leading to sciatica and spine surgery. Although epidural steroid injection (ESI) is routinely used to alleviate sciatica, the efficacy is short and repeated injections are required. There remains challenging to prolong the efficacy of ESI. Herein, an injectable hyaluronic acid (HA) hydrogel implant by crosslinking acrylated-modified HA (HA-A) with thiol-modified HA (HA-SH) was designed to achieve a biphasic release of betamethasone. The hydrogel showed biocompatibility and biodegradability to match neuronal tissues. Notably, compared to traditional ESI, the hydrogel better alleviated sciatica in vivo by synergistically inhibiting the neuroinflammation in central and peripheral nervous systems. We anticipate the injectable HA hydrogel implant has the potential for clinical translation in treating LDH-induced sciatica.

Intradiscal inflammatory stimulation induces spinal pain behavior and intervertebral disc degeneration in vivo

Degeneration of the intervertebral disc (IVD) results in a range of symptomatic (i.e., painful) and asymptomatic experiences. Components of the degenerative environment, including structural disruption and inflammatory cytokine production, often correlate with pain severity. However, the role of inflammation in the activation of pain and degenerative changes has been complex to delineate. The most common IVD injury model is puncture; however, it initiates structural damage that is not representative of the natural degenerative cascade. In this study, we utilized in vivo injection of lipopolysaccharide (LPS), a pro-inflammatory stimulus, into rat caudal IVDs using 33G needles to induce inflammatory activation without the physical tissue disruption caused by puncture using larger needles. LPS injection increased gene expression of pro-inflammatory cytokines (Tnfa, Il1b) and macrophage markers (Inos, Arg1), supported by immunostaining of macrophages (CD68, CCR7, Arg1) and systemic changes in blood cytokine and chemokine levels. Disruption of the IVD structural integrity after LPS injection was also evident through changes in histological grading, disc height, and ECM biochemistry. Ultimately, intradiscal inflammatory stimulation led to local mechanical hyperalgesia, demonstrating that pain can be initiated by inflammatory stimulation of the IVD. Gene expression of nociceptive markers (Ngf, Bdnf, Cgrp) and immunostaining for neuron ingrowth (PGP9.5) and sensitization (CGRP) in the IVD were also shown, suggesting a mechanism for the pain exhibited. To our knowledge, this rat IVD injury model is the first to demonstrate local pain behavior resulting from inflammatory stimulation of caudal IVDs. Future studies will examine the mechanistic contributions of inflammation in mediating pain.

J147 ameliorates sepsis-induced depressive-like behaviors in mice by attenuating neuroinflammation through regulating the TLR4/NF-κB signaling pathway

Neuroinflammation is associated with the pathophysiology of depression. The molecular mechanism of depressive-like behavior caused by sepsis-associated encephalopathy (SAE) is incompletely understood. J147 (an analog of curcumin) has been reported to improve memory and has neuroprotective activity, but its biological function in the depressive-like behavior observed in SAE is not known. We investigated the effects of J147 on lipopolysaccharide (LPS)-induced neuroinflammatory, depressive-like behaviors, and the toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signal pathway in the mouse hippocampus and microglia (BV2 cells). The forced-swimming test (FST) and tail-suspension test (TST) were undertaken for assessment of depressive-like behaviors. Expression of the proinflammatory genes interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α were measured using RT-qPCR and ELISA. Microglia activation was detected using immunofluorescence staining. The TLR4/NF-κB signaling pathway was studied using western blotting and immunofluorescence staining. J147 pretreatment markedly downregulated expression of IL-6, IL-1β, and TNF-α, and the mean fluorescence intensity of ionized calcium-binding adapter protein-1 in microglia. J147 restrained LPS-induced nuclear translocation of nuclear factor-kappa B (NF-κB), inhibitor of nuclear factor kappa B (IκB) degradation, and TLR4 activation in microglia. J147 administration inhibited bodyweight loss, mortality, microglia activation, and depressive-like behaviors in LPS-treated mice. In conclusion, J147 ameliorated the sepsis-induced depressive-like behaviors induced by neuroinflammation through attenuating the TLR4/NF-κB signaling pathway in microglia.

Hyperbaric Oxygen Therapy Alleviates Paclitaxel-Induced Peripheral Neuropathy Involving Suppressing TLR4-MyD88-NF-κB Signaling Pathway

Paclitaxel (PAC) results in long-term chemotherapy-induced peripheral neuropathy (CIPN). The coexpression of transient receptor potential vanilloid 1 (TRPV1) and Toll-like receptor 4 (TLR4) in the nervous system plays an essential role in mediating CIPN. In this study, we used a TLR4 agonist (lipopolysaccharide, LPS) and a TLR4 antagonist (TAK-242) in the CIPN rat model to investigate the role of TLR4-MyD88 signaling in the antinociceptive effects of hyper-baric oxygen therapy (HBOT). All rats, except a control group, received PAC to induce CIPN. Aside from the PAC group, four residual groups were treated with either LPS or TAK-242, and two of them received an additional one-week HBOT (PAC/LPS/HBOT and PAC/TAK-242/HBOT group). Mechanical allodynia and thermal hyperalgesia were then assessed. The expressions of TRPV1, TLR4 and its downstream signaling molecule, MyD88, were investigated. The mechanical and thermal tests revealed that HBOT and TAK-242 alleviated behavioral signs of CIPN. Immunofluorescence in the spinal cord dorsal horn and dorsal root ganglion revealed that TLR4 overexpression in PAC- and PAC/LPS-treated rats was significantly downregulated after HBOT and TAK-242. Additionally, Western blots showed a significant reduction in TLR4, TRPV1, MyD88 and NF-κB. Therefore, we suggest that HBOT may alleviate CIPN by modulating the TLR4-MyD88-NF-κB pathway.

Storax Protected Primary Cortical Neurons from Oxygen-Glucose Deprivation/Reoxygenation Injury via Inhibiting the TLR4/TRAF6/NF-κB Signaling Pathway

Storax is a traditional Chinese herb that is widely applied in stroke treatment. However, its neuroprotective effects and mechanisms are yet to be fully elucidated. This study aimed to elucidate the neuroprotective effects and underlying mechanisms of storax on oxygen-glucose deprivation/reoxygenation (OGD/R) in injured cortical neurons. The cortical neurons of Wistar rats were primarily cultured in vitro. TheTUNELmethod and CM-H2DCFDA probe were used to detect cell apoptosis and reactive oxygen species (ROS) expression. Enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blot were used to detect the expression of inflammatory cytokines and proteins of the TLR4/TRAF6/NF-κB signaling pathway. Immunofluorescence was used to measure NF-κB nuclear translocation. Transfection of TLR4 siRNA was used to detect the potential anti-inflammatory mechanisms of storax. The present results have shown that storax protected primary cortical neurons from OGD/R-induced injury by suppressing ROS generation and cell apoptosis; alleviating HMGB-1, TNF-α, IL-1β, and ICAM-1 expression; and promoting IL-10 expression. In addition, storax inhibited the activation of TLR4, TRAF6, IκBα, IKKβ, and NF-κBp65 caused by OGD/R. It is suggested that storax prevents OGD/R-induced primary cortical neuron injury by inhibiting the TLR4/TRAF6/NF-κB signaling pathway.

IL-10 alleviates radicular pain by inhibiting TNF-α/p65 dependent Nav1.7 up-regulation in DRG neurons of rats

BACKGROUND

Lumbar disc herniation (LDH) may induce radicular pain, the upregulation of voltage-gated sodium channels (VGSCs) in dorsal root ganglion (DRG) contributes to radicular pain by generating ectopic discharge of neurons, but the mechanism is unclear. Previously, we reported pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) up-regulated VGSCs in diabetic neuropathy. In this study, we explored the effect of anti-inflammatory cytokine interleukin-10 (IL-10) on radicular pain and the possible mechanisms.

METHODS

Rat model of LDH was induced by implanting autologous nucleus pulposus (NP). Mechanical and thermal pain thresholds were assessed by von Frey filaments and hotplate test respectively. IL-10 and TNF-α level in DRG and cerebrospinal fluid (CSF) were assessed by Enzyme-linked immunosorbent assay (ELISA). IL-10 was intrathecally delivered for 12 days. The expression of IL-10R1 and sodium channel Nav1.7 was displayed by immunofluorescence staining. The protein level of TNF-α and p-p65 was measured by western blotting.

RESULTS

NP implantation increased Nav1.7 expression in DRG neurons, decreased IL-10 level and increased TNF-α level in DRG and CSF. IL-10 significantly alleviated pain behaviors of rats with NP. IL-10R1 was co-localized with neurons but not with satellite cells in DRG. IL-10 decreased Nav1.7 and TNF-α/p-p65 expression in DRG of rats with NP. Co-administration of TNF-α with IL-10 counteracted the effect of IL-10 on pain behaviors, Nav1.7 and TNF-α/p-p65 expression of rats with NP.

CONCLUSIONS

The study revealed that IL-10 alleviated radicular pain by inhibiting TNF-α/p-p65 dependent Nav1.7 up-regulation in DRG neurons.

The role of percutaneous neurolysis in lumbar disc herniation: systematic review and meta-analysis

BACKGROUND

Recalcitrant disc herniation may result in chronic lumbar radiculopathy or sciatica. Fluoroscopically directed epidural injections and other conservative modalities may provide inadequate improvement in some patients. In these cases, percutaneous neurolysis with targeted delivery of medications is often the next step in pain management.

METHODS

An evidence-based system of methodologic assessment, namely, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used. Multiple databases were searched from 1966 to January 2021. Principles of the best evidence synthesis were incorporated into qualitative evidence synthesis. The primary outcome measure was the proportion of patients with significant pain relief and functional improvement (≥ 50%). Duration of relief was categorized as short-term (< 6 months) and long-term (≥ 6 months).

RESULTS

This assessment identified one high-quality randomized controlled trial (RCT) and 5 moderate-quality non-randomized studies with an application of percutaneous neurolysis in disc herniation. Overall, the results were positive, with level II evidence.

CONCLUSIONS

Based on the present systematic review, with one RCT and 5 nonrandomized studies, the evidence level is II for percutaneous neurolysis in managing lumbar disc herniation.

Vitamin D inhibits TNF-α induced apoptosis of human nucleus pulposus cells through regulation of NF-kB signaling pathway

BACKGROUND

To observe the effects of vitamin D on the apoptotic human nucleus pulposus cells under tumor necrosis factor-α (TNF-α) treatment.

METHODS

The gene expression data was downloaded from the NCBI Gene Expression Omnibus (GEO) database ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE34095 ). Differentially expressed genes between degenerative disc and non-degenerative disc were performed by R software. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analyses were performed using The Database for Annotation, Visualization and Integrated Discovery (DAVID). Then, the human nucleus pulposus tissue was harvested from 12 patients according to the modified Pfirrmann classification and human nucleus pulposus cells were obtained from digestion of herniated nucleus pulposus tissue. The collected nucleus pulposus cells were treated with different concentration of TNF-α, and cellular apoptosis was measured by flow cytometry. Then, human nucleus pulposus cells were divided into following groups: normal culture medium, TNF-α treated, TNF-α, and vitamin D-treated groups. Cellular apoptosis rate was quantified by flow cytometry. Protein expression of p-p65, p65, and IkBa was detected with western blot analysis.

RESULTS

A total of 536 differentially expressed genes were identified through bioinformatic analysis. KEGG pathway revealed that NF-kB signaling pathway was involved in the process of disc degeneration. In the NP cell cultures, vitamin D significantly increased cell proliferation potency. Furthermore, vitamin D inhibited TNF-α induced apoptosis of human nucleus pulposus cells. Vitamin D reduced the phospho-NF-κB/p65 expression in the TNF-α-treated NP cells.

CONCLUSION

Vitamin D can attenuate TNF-α-induced NP cells apoptosis through interfering with the NF-κB pathway.