Expression levels of IL-17 and TNF-α in degenerated lumbar intervertebral discs and their correlation

The role of TNF-α in osteoporosis, bone repair and inflammatory bone diseases: A review

Tumour necrosis factor alpha (TNF-α) is a pleiotropic cytokine synthesised primarily by mononuclear cells; it has a potent pro-inflammatory effect, playing a crucial role in metabolic, immune, and inflammatory diseases. This cytokine has been studied in various biological systems. In bone tissue, TNF-α plays an integral role in skeletal disorders such as osteoporosis, fracture repair and rheumatoid arthritis through its involvement in regulating the balance between osteoblasts and osteoclasts, mediating inflammatory responses, promoting angiogenesis and exacerbating synovial proliferation. The biological effect TNF-α exerts in this context is determined by a combination of the signalling pathway it activates, the type of receptor it binds, and the concentration and duration of exposure. This review summarises the participation and pathophysiological role of TNF-α in osteoporosis, bone damage repair, chronic immunoinflammatory bone disease and spinal cord injury, and discusses its main mechanisms.

Research on the role and mechanism of IL-17 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is one of the primary causes of low back pain (LBP), which seriously affects patients' quality of life. In recent years, interleukin (IL)-17 has been shown to be highly expressed in the intervertebral disc (IVD) tissues and serum of patients with IDD, and IL-17A has been shown to promote IDD through multiple pathways. We first searched databases such as PubMed, Cochrane, Embase, and Web of Science using the search terms "IL-17 or interleukin 17″ and "intervertebral discs". The search period ranged from the inception of the databases to December 2023. A total of 24 articles were selected after full-text screening. The main conclusion of the clinical studies was that IL-17A levels are significantly increased in the IVD tissues and serum of IDD patients. The results from the in vitro studies indicated that IL-17A can activate signaling pathways such as the NF-κB and MAPK pathways; promote inflammatory responses, extracellular matrix degradation, and angiogenesis; and inhibit autophagy in nucleus pulposus cells. The main finding of the in vivo experiments was that puncture of animal IVDs resulted in elevated levels of IL-17A within the IVD, thereby inducing IDD. Clinical studies, in vitro experiments, and in vivo experiments confirmed that IL-17A is closely related to IDD. Therefore, drugs that target IL-17A may be novel treatments for IDD, providing a new theoretical basis for IDD therapy.

Network Pharmacology with Metabolomics Study to Reveal the Mechanisms of Bushen Huoxue Formula in Intervertebral Disc Degeneration Treatment

Background

Intervertebral disc degeneration (IVDD) is a pathophysiological process that leads to severe back pain or neurological deficits. The Bushen Huoxue Formula (BSHXF) is a traditional herbal remedy widely used to treat diseases related to IVDD. However, its pharmacological mechanism needs further exploration.

Objective

This study aimed to elucidate the mechanisms through which BSHXF treats IVDD-related diseases by integrating metabolomics with network pharmacology.

Methods

Network pharmacology was utilized to identify potential targets of BSHXF against IVDD. Additionally, an animal model of needle puncture-induced disc degeneration was established to assess the effect of BSHXF. Mice were randomly assigned to the sham group, model group, and BSHXF group. Various techniques, including PCR, CCK-8 assay, MRI, histological examinations, and immunohistochemical analyses, were employed to evaluate degenerative and oxidative stress conditions in mouse disc tissue and cultured nucleus pulposus (NP) cells. UHPLC-HRMS/MS was used to differential distinct metabolites in the disc tissue from different groups, and MetaboAnalyst 5.0 was employed to enrich the metabolic pathways.

Results

Through network pharmacology, 15 core proteins were identified through protein-protein interaction (PPI) network construction. Functional enrichment analysis highlighted the critical role of BSHXF in addressing IVDD by influencing the response to oxidative stress. Furthermore, experimental evidence demonstrated that BSHXF significantly improved the pathological progression of IVDD and increased oxidative stress markers SOD-1 and GPX1, both in the disc degeneration model and cultured NP cells. Metabolomics identified differential metabolites among the three groups, revealing 15 metabolic pathways between the sham and model groups, and 13 metabolic pathways enriched between the model and BSHXF groups.

Conclusion

This study, integrating network pharmacology and metabolomics, suggests that BSHXF can alleviate IVDD progression by modulating oxidative stress. Key metabolic pathways associated with BSHXF-mediated reduction of oxidative stress include the citrate cycle, cysteine and methionine metabolism, alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, D-glutamine and D-glutamate metabolism, glutathione metabolism, and tryptophan metabolism. While this research demonstrates the therapeutic potential of BSHXF in reducing oxidative stress levels in IVDD, further research is needed to thoroughly understand its underlying mechanisms.

The mechanisms and functions of TNF-α in intervertebral disc degeneration

Low back pain (LBP) is one of the most common health problems in people's lives, which brings a massive burden to clinicians, and the leading cause of LBP is intervertebral disc degeneration (IDD). IDD is mainly caused by factors such as aging, mechanical stress, and lack of nutrition. The pathological mechanism of IDD is very complex, involving inflammatory response, cell metabolism disorder, and so on. Unfortunately, in the current treatment of IDD, only relieving symptoms as the primary means of relieving a patient's pain cannot effectively inhibit or reverse the progression of IDD. Tumor necrosis factor-α (TNF-α) is a multifunctional pro-inflammatory factor involved in many diseases' pathological processes. With the in-depth study of the pathological mechanism of IDD, more and more evidence has shown that TNF-α is an essential activator of IDD, which is related to the metabolic disorder, inflammatory responses, apoptosis, and other pathological processes of extracellular dissociation in the intervertebral disc. Therefore, anti-TNF-α therapy is an effective therapeutic target for alleviating IDD, especially in inhibiting extracellular matrix degradation and reducing inflammatory responses. This article reviews the pathological role of TNF-α in IDD and the latest research progress of TNF-α inhibitors in treating IDD.

The Role of IL-17-Mediated Inflammatory Processes in the Pathogenesis of Intervertebral Disc Degeneration and Herniation: A Comprehensive Review

It has been reported that degenerated and herniated lumbar intervertebral discs show high expression of IL-17, suggesting that local immune reactions occur in patients with low back pain. While clinical sample analyses from different laboratories confirm this, it is not deeply not known on how IL-17 is induced in the pathology and their interactions with other inflammatory responses. This conscience review organizes current laboratory findings on this topic and present trajectory for full understanding on the role of IL-17 in pathology of intervertebral disc disease.

Herbal Formula Modified Bu-Shen-Huo-Xue Decoction Attenuates Intervertebral Disc Degeneration via Regulating Inflammation and Oxidative Stress

Objective

This study aims to clarify the potential mechanism of modified Bu-Shen-Huo-Xue decoction (MBSHXD) in treating intervertebral disc degeneration (IDD) with methods of network pharmacology and molecular docking.

Methods

An MBSHXD and IDD-related common target gene set was established through TCMSP, UniProt, and two disease gene databases. GO and KEGG enrichment analysis and protein-protein interaction (PPI) networks were performed through the R platform and STRING to discover the potential mechanism. Molecular docking between the active ingredients and the core genes is used to calculate the binding energy.

Results

A total of 147 active ingredients and 79 common genes (including 10 core genes, TNF, VEGFA, IL6, MAPK3, AKT1, MAPK8, TP53, JUN, MMP9, and CXCL8) were identified. The results of GO and KEGG enrichment analysis showed that MBSHXD plays an essential role in regulating inflammation and oxidative stress. The meaningful pathways are the AGE-RAGE signaling pathway in diabetic complications, the IL-17 signaling pathway, the TNF signaling pathway, the PI3K-Akt signaling pathway, the MAPK signaling pathway, and apoptosis. In addition, the PPI network and molecular docking further demonstrated the roles that nine bioactive ingredients of MBSHXD play in IDD treatment through their interference with core target proteins.

Conclusion

This study reveals that MBSHXD has the characteristics of a “multi-component, multi-target, and multi-pathway” in the treatment of IDD by regulating inflammation and oxidative stress, and network pharmacology may provide a feasible method to verify the molecular mechanism of MBSHXD for IDD by combining with molecular docking.

Pharmacological Mechanism of Danggui-Sini Formula for Intervertebral Disc Degeneration: A Network Pharmacology Study

Background

Intervertebral disc degeneration (IVDD) is the most significant cause of low back pain, the sixth-largest disease burden globally, and the leading cause of disability. This study is aimed at investigating the molecular biological mechanism of Danggui-Sini formula (DSF) mediated IVDD treatment.

Methods

A potential gene set for DSF treatment of IVDD was identified through TCMSP, UniProt, and five disease gene databases. A protein interaction network of common targets between DSF and IVDD was established by using the STRING database. GO and KEGG enrichment analyses were performed using the R platform to discover the potential mechanism. Moreover, AutoDock Vina was used to verify molecular docking and calculate the binding energy.

Results

A total of 119 active ingredients and 136 common genes were identified, including 10 core genes (AKT1, IL6, ALB, TNF, VEGFA, TP53, MAPK3, CASP3, JUN, and EGF). Enrichment analysis results showed that the therapeutic targets of DSF for diseases mainly focused on the AGE-RAGE signaling pathway involved in diabetic complications, IL-17 signaling pathway, TNF signaling pathway, Toll-like receptor signaling pathway, apoptosis, cellular senescence, PI3K-Akt signaling pathway, and FoxO signaling pathway. These biological processes are induced mainly in response to oxidative stress and reactive oxygen species and the regulation of apoptotic signaling pathways. Molecular docking showed that there was a stable affinity between the core genes and the key components.

Conclusions

The combination of network pharmacology and molecular docking provides a practical way to analyze the molecular biological mechanism of DSF-mediated IVDD treatment, which confirms the “multicomponent, multitarget and multipathway” characteristics of DSF and provides an essential theoretical basis for clinical practice.

An in vivo study of the effect of c-Jun on intervertebral disc degeneration in rats

Intervertebral disc degeneration (IDD) has been well-recognized as one of the causes of vast lower back pain. The objective of the current study intends to elucidate the influence and regulatory molecular mechanisms of c-Jun on IDD. This study established an IDD model of Sprague-Dawley (SD) rats by needle puncture. An LV5-c-Jun lentiviral vector was constructed and injected into rats’ intervertebral disc (IVD) tissue to increase the c-Jun expression following the establishment of modeling. The pathological changes of IVD tissue structure and collagen fibers were visualized following the processes of hematoxylin-eosin (HE) staining method and transmission electron microscopy. Real-time PCR, western blot, immunohistochemistry, and ELISA assays were performed to detect the expression levels of TGF-β, TIMP-3, COL2A1, and inflammatory cytokines. The collagen fibers were arranged in parallel and the surface was smooth after c-Jun overexpression, whereas the collagen fibers in the control group were disorderly arranged with a rough surface. The findings indicated that c-Jun was responsible for upregulating expression levels of TGF-β, TIMP-3, and COL2A1 in the mRNA and proteins, but simultaneously downregulating expression levels of inflammatory factors IL-1β, IL-17, IL-6, and TNF-α. c-Jun overexpression produced a positive effect on IDD, inhibited inflammatory response in vivo, and might delay the degeneration of IVD. Thus, c-Jun may act as a novel potential agent in treating IDD.

Low back pain scores correlate with the cytokine mRNA level in lumbar disc biopsies: a study of inflammatory markers in patients undergoing lumbar spinal fusion

PURPOSE

The molecular mechanism behind pain in degenerative disc disease (DDD) and chronic low back pain (LBP) patients is largely unknown. This present study examines the association of LBP and disability to mediators of the inflammatory cascade, as indexed by mRNA gene expression of pro-inflammatory cytokine markers in the intervertebral disc (IVD).

METHODS

Biopsies of the annulus fibrosus (AF) and the nucleus pulposes (NP) from patients with DDD undergoing 1-2 level fusion surgery at L4/L5 or L5/S1 were obtained from total of 34 patients [9 M, 25 F] with average age of 53 [32-63]. The mRNA expression of TNF-α, IL-1β, and IL-6 in the AF and NP was analyzed using quantitative real-time polymerase chain reaction (RT-qPCR), and the expression level of these markers was correlated to the visual analogue scale (VAS) and Oswestry Disability Index (ODI) scores (0-100) for pain and disability.

RESULTS

We report a statistically significant positive correlation between pain intensity (VAS score) and the expression of TNF-α in both the AF (r = 0.54, p = 0.001) and NP (r = 0.40, p = 0.02), similarly with IL-1β in AF (r = 0.37, p = 0.02) and IL-6 in NP (r = 0.40, p = 0.02). In addition, we found significant positive correlation observed between disability score (ODI) and expression of IL-6 in both AF (r = 0.36, p = 0.03) and NP (r = 0.41, p = 0.01).

CONCLUSION

We conclude that the intensity of LBP and disability is associated with the level of inflammation in the disc.

The role of structure and function changes of sensory nervous system in intervertebral disc-related low back pain

Low back pain (LBP) is a common musculoskeletal symptom, which can be developed in multiple clinical diseases. It is widely recognized that intervertebral disc (IVD) degeneration (IVDD) is one of the leading causes of LBP. However, the pathogenesis of IVD-related LBP is still controversial, and the treatment means are also insufficient to date. In recent decades, the role of structure and function changes of sensory nervous system in the induction and the maintenance of LBP is drawing more and more attention. With the progress of IVDD, IVD cell exhaustion and extracellular matrix degradation result in IVD structural damage, while neovascularization, innervation and inflammatory activation further deteriorate the microenvironment of IVD. New nerve ingrowth into degenerated IVD amplifies the impacts of IVD-derived nociceptive molecules on sensory endings. Moreover, IVDD is usually accompanied with disc herniation, which could injure and inflame affected nerves. Under mechanical and pro-inflammatory stimulation, the pain-transmitting pathway exhibits a sensitized function state and ultimately leads to LBP. Hence, relevant pathogenic factors, such as neurotrophins, ion channels, inflammatory factors, etc., are supposed to serve as promising therapeutic targets for LBP. The purpose of this review is to comprehensively summarize the current evidence on 1) the pathological changes of sensory nervous system during IVDD and their association with LBP, and 2) potential therapeutic strategies for LBP targeting relevant pathogenic factors.

The c-Jun signaling pathway has a protective effect on nucleus pulposus cells in patients with intervertebral disc degeneration

Among a range of diverse clinical symptoms, intervertebral disc degeneration (IDD) contributes mostly to the onset of lower back pain. The present study aimed to investigate the effects of c-Jun on nucleus pulposus (NP) cells of IDD and its regulation on molecular mechanisms. Intervertebral disc (IVD) tissues were collected from patients suffering from IDD disease, and NP cells were subsequently isolated and cultured. By overexpressing c-Jun in NP cells, expression levels of mRNAs and proteins of IDD-related genes and inflammatory cytokines were subjected to reverse transcription-quantitative PCR, western blot and ELISA assays. Additional transforming growth factor-β (TGF-β) antibodies were administrated to suppress the function of TGF-β. Cell proliferation and apoptosis were determined via Cell Counting Kit-8 and TUNEL assays, respectively. The results demonstrated that the overexpression of c-Jun robustly upregulated both mRNA and protein expression of TGF-β, TIMP metallopeptidase inhibitor 3, aggrecan and collagen type II alpha 1 chain and simultaneously downregulated the expression of the inflammatory cytokines TNF-α, interleukin (IL)-1β, IL-6 and IL-17. Furthermore, following c-Jun overexpression, survival rates of NP cells were increased while apoptosis rates were decreased. However, the addition of a TGF-β antibody significantly promoted apoptosis and restricted cell survival, which differed from the results of the c-Jun overexpression group. The present study hypothesized therefore that c-Jun may positively regulate TGF-β expression within NP cells of IDD, which could promote the proliferation of IDD-NP cells and accelerate cell viability via reducing apoptosis and the inflammatory response.

The role of IL-1β and TNF-α in intervertebral disc degeneration

Low back pain (LBP), a prevalent and costly disease around the world, is predominantly caused by intervertebral disc (IVD) degeneration (IDD). LBP also presents a substantial burden to public health and the economy. IDD is mainly caused by aging, trauma, genetic susceptibility, and other factors. It is closely associated with changes in tissue structure and function, including progressive destruction of the extracellular matrix (ECM), enhanced senescence, disc cell death, and impairment of tissue biomechanical function. The inflammatory process, exacerbated by cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), are considered to be the key mediators of IDD and LBP. IL-1β and TNF-α are the most important proinflammatory cytokines, as they have powerful proinflammatory activities and can promote the secretion of a variety of proinflammatory mediators. They are also upregulated in the degenerative IVDs, and they are closely related to various pathological IDD processes, including inflammatory response, matrix destruction, cellular senescence, autophagy, apoptosis, pyroptosis, and proliferation. Therefore, anti-IL-1β and anti-TNF-α therapies may have the potential to alleviate disc degeneration and LBP. In this paper, we reviewed the expression pattern and signal transduction pathways of IL-1β and TNF-α, and we primarily focused on their similar and different roles in IDD. Because IL-1β and TNF-α inhibition have the potential to alleviate IDD, an in-depth understanding of the role of IL-1β and TNF-α in IDD will benefit the development of new treatment methods for disc degeneration with IL-1β and TNF-α at the core.

Immunomodulation of mesenchymal stem cells in discogenic pain

BACKGROUND CONTEXT

Back pain is a highly prevalent health problem in the world today and has a great economic impact on health-care budgets. Intervertebral disc (IVD) degeneration has been identified as a main cause of back pain. Inflammatory cytokines produced by macrophages or disc cells in an inflammatory environment play an important role in painful progressive degeneration of IVD. Mesenchymal stem cells (MSCs) have shown to have immunosuppressive and anti-inflammatory properties. Mesenchymal stem cells express a variety of chemokines and cytokines receptors having tropism to inflammation sites.

PURPOSE

This study aimed to develop an in vitro controlled and standardized model of inflammation and degeneration of IVD with rat cells and to evaluate the protective and immunomodulatory effect of conditioned medium (CM) from the culture of MSCs to improve the conditions presented in herniated disc and discogenic pain processes.

STUDY DESIGN

This is an experimental study.

METHODS

In this study, an in vitro model of inflammation and degeneration of IVD has been developed, as well as the effectiveness of CM from the culture of MSCs.

RESULTS

Conditioned medium from MSCs downregulated the expression of various proinflammatory cytokines produced in the pathogenesis of discogenic pain such as interleukin (IL)-1β, IL-6, IL-17, and tumor necrosis factor (TNF).

CONCLUSION

Mesenchymal stem cells represent a promising alternative strategy in the treatment of IVD degeneration inasmuch as there is currently no treatment which leads to a complete remission of long-term pain in the absence of drugs.

Carthamin yellow inhibits matrix degradation and inflammation induced by LPS in the intervertebral disc via suppression of MAPK pathway activation

Carthamin yellow (CY), which is a flavonoid compound isolated from safflower, has various pharmacological effects including promoting blood circulation to remove blood stasis and alleviating pain. CY is a herb used in Chinese traditional medicines. Intervertebral disc degeneration (IDD) is a common spinal disorder and degeneration of nucleus pulposus (NP) cells and inflammation are significant parts of the pathological cascade. The curative effect of CY on NP cells in association with degeneration and inflammation remains to be elucidated. In the present study, rat NP cells were isolated, cultured and used to detect the suppressive effects of CY on lipopolysaccharide (LPS)-induced genetic expression variation and the expression of matrix degradation enzymes, including matrix metallopeptidase-3, ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS)-4 and ADAMTS-5. A protective effect of CY on NP cells was observed against LPS-induced matrix degradation and inflammation. Western blotting results demonstrated that pretreatment with CY significantly suppressed the LPS-induced activation of the mitogen activated protein kinase (MAPK) pathway. The results of the present study suggested that CY exerted anti-degenerative and anti-inflammatory effects on NP cells via inhibition of MAPK pathway activation. Therefore, CY may be a potential therapeutic drug for the treatment of IDD in the future.

Tumor necrosis factor-α: a key contributor to intervertebral disc degeneration

Intervertebral disc (IVD) degeneration (IDD) is the most common cause leading to low back pain (LBP), which is a highly prevalent, costly, and crippling condition worldwide. Current treatments for IDD are limited to treat the symptoms and do not target the pathophysiology. Tumor necrosis factor-α (TNF-α) is one of the most potent pro-inflammatory cytokines and signals through its receptors TNFR1 and TNFR2. TNF-α is highly expressed in degenerative IVD tissues, and it is deeply involved in multiple pathological processes of disc degeneration, including matrix destruction, inflammatory responses, apoptosis, autophagy, and cell proliferation. Importantly, anti-TNF-α therapy has shown promise for mitigating disc degeneration and relieving LBP. In this review, following a brief description of TNF-α signal transduction, we mainly focus on the expression pattern and roles of TNF-α in IDD, and summarize the emerging progress regarding its inhibition as a promising biological therapeutic approach to disc degeneration and associated LBP. A better understanding will help to develop novel TNF-α-centered therapeutic interventions for degenerative disc disease.