IL-1β/HMGB1 signalling promotes the inflammatory cytokines release via TLR signalling in human intervertebral disc cells

High mobility group box protein 1 sensitizes mononuclear cells to further contact with lipopolysaccharide

Fever is an adaptive host-defense response to infection and nowadays is rightly considered to be an expression of a healthy body and a well-functioning immune system. The condition is that it must be tightly regulated. Therefore, in individual cases, fever may be detrimental and should be treated. Specific excessive febrile reaction to pathogens which occurs after aseptic injuries is one among such cases. We previously found that among necrotic products, high mobility group box protein 1 (HMGB1) released from the site of aseptic injury affects immune effectors (cells) to mediate higher fever in response to further contact with bacterial lipopolysaccharide (LPS). Here we observed that intraperitoneal (i.p.) pre-injection of recombinant HMGB1 (5 µg/rat i.p.) provoked an increase in plasma levels of prostaglandin E2 (PGE2) in rats and augmented release of interleukin (IL)-1β and IL-6 after LPS administration at a dose of 50 µg/kg i.p. compared to rats pre-injected with saline or heat-denatured HMGB1. Furthermore, peripheral blood mononuclear cells (PBMCs) isolated from rats injected with HMGB1 were more sensitized to produce enhanced levels of IL-1β and PGE2 when stimulated with LPS in vitro (1 µg/ml/106 cells for 4 h) compared to control animals injected with saline or heat-denatured HMGB1. We also noted a significant increase in activation of nuclear factor κB (NF-κB) in cells isolated from rats injected with HMGB1. Altogether, the obtained results suggest that HMGB1 participates in priming of immune cells to further contact with pathogens.

Protective effects of Shensuitongzhi formula on intervertebral disc degeneration via downregulation of NF-κB signaling pathway and inflammatory response

Low back pain (LBP) is a common orthopedic disease over the world. Lumbar intervertebral disc degeneration (IDD) is regarded as an important cause of LBP. Shensuitongzhi formula (SSTZF) is a drug used in clinical treatment for orthopedic diseases. It has been found that SSTZF can have a good treatment for IDD. But the exact mechanism has not been clarified. The results showed that SSTZF protects against LSI-induced degeneration of cartilage endplates and intervertebral discs. Meanwhile, SSTZF treatment dramatically reduces the expression of inflammatory factor as well as the expression of catabolism protein and upregulates the expression of anabolism protein in LSI-induced mice. In addition, SSTZF delayed the progression of LSI-induced IDD via downregulation the level of NF-κB signaling key gene RELA and phosphorylation of key protein P65 in endplate chondrocytes. Our study has illustrated the treatment as well as the latent mechanism of SSTZF in IDD.

Decoding Macrophage Subtypes to Engineer Modulating Hydrogels for the Alleviation of Intervertebral Disk Degeneration

A major pathological basis for low back pain is intervertebral disk degeneration, which is primarily caused by the degeneration of nucleus pulposus cells due to imbalances in extracellular matrix (ECM) anabolism and catabolism. The phenotype of macrophages in the local immune microenvironment greatly influences the balance of ECM metabolism. Therefore, the control over the macrophage phenotype of the ECM is promising to repair intervertebral disk degeneration. Herein, the preparation of an injectable nanocomposite hydrogel is reported by embedding epigallocatechin-3-gallate-coated hydroxyapatite nanorods in O-carboxymethyl chitosan cross-linked with aldehyde hyaluronic acid that is capable of modulating the phenotype of macrophages. The bioactive components play a primary role in repairing the nucleus pulposus, where the hydroxyapatite nanorods can promote anabolism in the ECM through the nucleopulpogenic differentiation of mesenchymal stem cells. In addition, epigallocatechin-3-gallate can decrease catabolism in the ECM in nucleus pulposus by inducing M2 macrophage polarization, which exists in normal intervertebral disks and can alleviate degeneration. The nanocomposite hydrogel system shows promise for the minimally invasive and effective treatment of intervertebral disk degeneration by controlling anabolism and catabolism in the ECM and inhibiting the IL17 signaling pathway (M1-related pathway) in vitro and in vivo.

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.

Sex differences in the biomechanical and biochemical responses of caudal rat intervertebral discs to injury

Background

Intervertebral disc degeneration (IDD) is a major cause of low back pain (LBP) worldwide. Sexual dimorphism, or sex-based differences, appear to exist in the severity of LBP. However, it is unknown if there are sex-based differences in the inflammatory, biomechanical, biochemical, and histological responses of intervertebral discs (IVDs).

Methods

Caudal (Coccygeal/Co) bone-disc-bone motion segments were isolated from multiple spinal levels (Co8 to Co14) of male and female Sprague-Dawley rats. Changes in motion segment biomechanics and extracellular matrix (ECM) biochemistry (glycosaminoglycan [GAG], collagen [COL], water, and DNA content) were evaluated at baseline and in response to chemical insult (lipopolysaccharide [LPS]) or puncture injury ex vivo. We also investigated the contributions of Toll-like receptor (TLR4) signaling on responses to LPS or puncture injury ex vivo, using a small molecule TLR4 inhibitor, TAK-242.

Results

Findings indicate that IVD motion segments from female donors had greater nitric oxide (NO) release in LPS groups compared to male donors. HMGB1 release was increased in punctured discs, but not LPS injured discs, with no sex effect. Although both male and female discs exhibited reductions in dynamic moduli in response to LPS and puncture injuries, dynamic moduli from female donors were higher than male donors across all groups. In uninjured (baseline) samples, a significant sex effect was observed in nucleus pulposus (NP) DNA and water content. Female annulus fibrosus (AF) also had higher DNA, GAG, and COL content (normalized by dry weight), but lower water content than male AF. Additional injury- and sex-dependent effects were observed in AF GAG/DNA and COL/DNA content. Finally, TAK-242 improved the dynamic modulus of female but not male punctured discs.

Conclusions

Our findings demonstrate that there are differences in rat IVD motion segments based on sex, and that the response to injury in inflammatory, biomechanical, biochemical, and histological outcomes also exhibit sex differences. TLR4 inhibition protected against loss of mechanical integrity of puncture-injured IVD motion segments, with differences responses based on donor sex.

Pathogenesis and therapeutic implications of matrix metalloproteinases in intervertebral disc degeneration: A comprehensive review

Intervertebral disc (IVD) degeneration (IDD) is a common disorder that affects the spine and is a major cause of lower back pain (LBP). The extracellular matrix (ECM) is the structural foundation of the biomechanical properties of IVD, and its degradation is the main pathological characteristic of IDD. Matrix metalloproteinases (MMPs) are a group of endopeptidases that play an important role in the degradation and remodeling of the ECM. Several recent studies have shown that the expression and activity of many MMP subgroups are significantly upregulated in degenerated IVD tissue. This upregulation of MMPs results in an imbalance of ECM anabolism and catabolism, leading to the degradation of the ECM and the development of IDD. Therefore, the regulation of MMP expression is a potential therapeutic target for the treatment of IDD. Recent research has focused on identifying the mechanisms by which MMPs cause ECM degradation and promote IDD, as well as on developing therapies that target MMPs. In summary, MMP dysregulation is a crucial factor in the development of IDD, and a deeper understanding of the mechanisms involved is needed to develop effective biological therapies that target MMPs to treat IDD.

Signaling Mechanisms of Stem Cell Therapy for Intervertebral Disc Degeneration

Low back pain is the leading cause of disability worldwide. Intervertebral disc degeneration (IDD) is the primary clinical risk factor for low back pain and the pathological cause of disc herniation, spinal stenosis, and spinal deformity. A possible approach to improve the clinical practice of IDD-related diseases is to incorporate biomarkers in diagnosis, therapeutic intervention, and prognosis prediction. IDD pathology is still unclear. Regarding molecular mechanisms, cellular signaling pathways constitute a complex network of signaling pathways that coordinate cell survival, proliferation, differentiation, and metabolism. Recently, stem cells have shown great potential in clinical applications for IDD. In this review, the roles of multiple signaling pathways and related stem cell treatment in IDD are summarized and described. This review seeks to investigate the mechanisms and potential therapeutic effects of stem cells in IDD and identify new therapeutic treatments for IDD-related disorders.

TAK-715 alleviated IL-1β-induced apoptosis and ECM degradation in nucleus pulposus cells and attenuated intervertebral disc degeneration ex vivo and in vivo

BACKGROUND

Intervertebral disc degeneration (IDD) is one of the most common disorders related to the spine. Inflammation, apoptosis and extracellular matrix (ECM) degradation contribute to disc degeneration in nucleus pulposus cells (NPCs). This study focused on the role and mechanism of the p38 inhibitor TAK-715 in intervertebral disc degeneration.

METHODS

NPCs were treated with IL-1β to mimic apoptosis, followed by the addition of TAK-715. It was determined that apoptosis, inflammatory mediators (COX-2), inflammatory cytokines (HMGB1), and ECM components (collagen II, MMP9, ADAMTS5, and MMP3) existed in NPCs. In addition, the p38MAPK signaling pathways were examined. The role of TAK-715 in vivo was determined by acupuncture-induced intervertebral disc degeneration. Following an intradiscal injection of TAK-715, MRI and a histopathological analysis were conducted to assess the degree of degeneration.

RESULTS

IL-1β-induced apoptosis was alleviated by TAK-715 in vitro, and antiapoptotic proteins were upregulated. Furthermore, TAK-715 blocked IL-1β-induced inflammatory mediator production (COX-2) and inflammatory cytokine production (HMGB1) and degraded the ECM (collagen II, MMP9, ADAMTS5, and MMP3). By inhibiting the phosphorylation of p38, TAK-715 exerted its effects. In a rat tail model, TAK-715 ameliorates puncture-induced disc degeneration based on MRI and histopathology evaluations.

CONCLUSION

TAK-715 attenuated intervertebral disc degeneration in vitro and in vivo, suggesting that it might be an effective treatment for IDD.

Blocking toll-like receptor 4 mitigates static loading induced pro-inflammatory expression in intervertebral disc motion segments

While the anabolic effects of mechanical loading on the intervertebral disc (IVD) have been extensively studied, inflammatory responses to loading have not been as well characterized. Recent studies have highlighted a significant role of innate immune activation, particularly that of toll-like receptors (TLRs), in IVD degeneration. Biological responses of intervertebral disc cells to loading depend on many factors that include magnitude and frequency. The goals of this study were to characterize the inflammatory signaling changes in response to static and dynamic loading of IVD and investigate the contributions of TLR4 signaling in response to mechanical loading. Rat bone-disc-bone motion segments were loaded for 3 hr under a static load (20 % strain, 0 Hz) with or without an additional low-dynamic (4 % dynamic strain, 0.5 Hz) or high-dynamic (8 % dynamic strain, 3 Hz) strain, and results were compared to unloaded controls. Some samples were also loaded with or without TAK-242, an inhibitor of TLR4 signaling. The magnitude of NO release into the loading media (LM) was correlated with the applied frequency and strain magnitudes across different loading groups. Injurious loading profiles, such as static and high-dynamic, significantly increased Tlr4 and Hmgb1 expression while this result was not observed in the more physiologically relevant low-dynamic loading group. TAK-242 co-treatment decreased pro-inflammatory expression in static but not dynamic loaded groups, suggesting that TLR4 plays a direct role in mediating inflammatory responses of IVD to static compression. Overall, the microenvironment induced by dynamic loading diminished the protective effects of the TAK-242, suggesting that TLR4 plays a direct role in mediating inflammatory responses of IVD to static loading injury.

Current Perspectives on Periodontitis in Systemic Sclerosis: Associative Relationships, Pathogenic Links, and Best Practices

Systemic sclerosis is a chronic, autoimmune, multisystemic disease characterized by aberrant extracellular matrix protein deposition and extreme progressive microvasculopathy. These processes lead to damage within the skin, lungs, or gastrointestinal tract, but also to facial changes with physiognomic and functional alterations, and dental and periodontal lesions. Orofacial manifestations are common in SSc but are frequently overshadowed by systemic complications. In clinical practice, oral manifestations of SSc are suboptimally addressed, while their management is not included in the general treatment recommendations. Periodontitis is associated with autoimmune-mediated systemic diseases, including systemic sclerosis. In periodontitis, the microbial subgingival biofilm induces host-mediated inflammation with subsequent tissue damage, periodontal attachment, and bone loss. When these diseases coexist, patients experience additive damage, increasing malnutrition, and morbidity. The present review discusses the links between SSc and periodontitis, and provides a clinical guide for preventive and therapeutical approaches in the management of these patients.

HMGB1 promotes Ox-LDL-induced endothelial cell damage by inhibiting PI3K/Akt signaling pathway

BACKGROUND

Atherosclerosis is the pathological basis of cardio-cerebrovascular diseases. Oxidized low-density lipoprotein (ox-LDL) is an important risk factor for atherosclerosis. Ox-LDL leads to endothelial cell (EC) damage and dysfunction through various processes and promotes the occurrence and deterioration of atherosclerosis. High mobility group box-1 (HMGB1) is a protein associated with cellular damage. In the present study, the effect of HMGB1 on ox-LDL-induced EC damage was determined and the underlying mechanism explored.

MATERIALS AND METHODS

Human umbilical vein ECs (HUVECs) were exposed to ox-LDL to induce endothelial damage and changes in HMGB1 expression level were detected using western blotting analysis and reverse transcription-quantitative PCR. To observe the effect of HMGB1 on ox-LDL-induced damage, the HMGB1 expression was downregulated with siRNA, and cell viability, cytotoxicity, and apoptosis rate were assessed. HUVECs were pretreated with LY294002, an inhibitor of the PI3K/Akt pathway, to determine whether the effect of HMGB1 on damage is via the PI3K-Akt pathway.

RESULTS

The results showed that ox-LDL can upregulate HMGB1 expression in HUVECs and downregulation of HMGB1 expression can prevent ox-LDL-induced damage in HUVECs. Furthermore, the effect of HMGB1 on ox-LDL-induced damage could be promoted by inhibiting the PI3K/Akt signaling pathway.

CONCLUSION

The results indicate HMGB1 may be a promising research target to alleviate ox-LDL-induced EC damage.

Is intervertebral disc degeneration associated with reduction in serum ferritin?

OBJECTIVE

Ferritin autophagy is characterized by intracellular ferroptosis and selective ferritin degradation. However, the role of ferritin in the development of intervertebral disc degeneration (IDD) has not been elucidated. The study aimed to investigate the role of serum iron metabolism markers, especially serum ferritin (SF), in IDD.

METHODS

217 patients who came to the spine surgery department of our hospital for low back pain were recruited, and blood samples were collected for routine examination after admission. The cumulative grade was also calculated by summing up the Pfirrmann grade of all lumbar discs.

RESULTS

Correlation analysis showed that cumulative grade was correlated with SF (r = - 0.185, p = 0.006), not with serum iron (SI), transferrin saturation (TS), unsaturated iron-binding capacity (UIBC) and total iron-binding capacity (TIBC) (all p > 0.05). In addition, SF levels in the low severity IDD were significantly higher than high severity IDD in cumulative grade (p = 0.003) and single disc grade. No statistically significant difference was found in the other four indicators. A statistically significant difference was observed between the high (cumulative grade > 17) and low score (cumulative grade ≤ 17) groups in terms of age. According to the ROC curve, the cut-off value of SF levels was 170.5. Patients with SF < 170.5 ng/mL had severe disc degeneration. The sensitivity and specificity were 0.635 and 0.602, respectively.

CONCLUSION

This study preliminarily showed that SF was negatively correlated with the degree of IDD and can be used to predict IDD severity.

The role of nerve fibers and their neurotransmitters in regulating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) has been the major contributor to chronic lower back pain (LBP). Abnormal apoptosis, senescence, and pyroptosis of IVD cells, extracellular matrix (ECM) degradation, and infiltration of immune cells are the major molecular alternations during IVDD. Changes at tissue level frequently occur at advanced IVD tissue. Ectopic ingrowth of nerves within inner annulus fibrosus (AF) and nucleus pulposus (NP) tissue has been considered as the primary cause for LBP. Innervation at IVD tissue mainly included sensory and sympathetic nerves, and many markers for these two types of nerves have been detected since 1940. In fact, in osteoarthritis (OA), beyond pain transmission, the direct regulation of neuropeptides on functions of chondrocytes have attracted researchers' great attention recently. Many physical and pathological similarities between joint and IVD have shed us the light on the neurogenic mechanism involved in IVDD. Here, an overview of the advances in the nervous system within IVD tissue will be performed, with a discussion on in the role of nerve fibers and their neurotransmitters in regulating IVDD. We hope this review can attract more research interest to address neuromodulation and IVDD itself, which will enhance our understanding of the contribution of neuromodulation to the structural changes within IVD tissue and inflammatory responses and will help identify novel therapeutic targets and enable the effective treatment of IVDD disease.

Innovative immune mechanisms and antioxidative therapies of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is the basic pathological process of many degenerative diseases of the spine, characterized by series of symptoms, among which low back pain (LBP) is the most common symptom that patients suffer a lot, which not only makes patients and individual families bear a huge pain and psychological burden, but also consumes a lot of medical resources. IDD is usually thought to be relevant with various factors such as genetic predisposition, trauma and aging, and IDD progression is tightly relevant with structural and functional alterations. IDD processes are caused by series of pathological processes, including oxidative stress, matrix decomposition, inflammatory reaction, apoptosis, abnormal proliferation, cell senescence, autophagy as well as sepsis process, among which the oxidative stress and inflammatory response are considered as key link in IDD. The production and clearance of ROS are tightly connected with oxidative stress, which would further simulate various signaling pathways. The phenotype of disc cells could change from matrix anabolism-to matrix catabolism- and proinflammatory-phenotype during IDD. Recent decades, with the relevant reports about oxidative stress and inflammatory response in IDD increasing gradually, the mechanisms researches have attracted much more attention. Consequently, this study focused on the indispensable roles of the oxidative stress and inflammatory response (especially macrophages and cytokines) to illustrate the origin, development, and deterioration of IDD, aiming to provide novel insights in the molecular mechanisms as well as significant clinical values for IDD.

Expression of adipokines and adipocytokines by epidural adipose tissue in cauda equina syndrome in dogs

Background

Compression of epidural adipose tissue (EAT) within the scope of cauda equina syndrome (CES) could lead to an enhanced expression of inflammatory mediators, possibly contributing to pain amplification in dogs.

Objectives

To analyze expression of inflammatory adipo(‐cyto)kines within the EAT of dogs with CES.

Animals

Client‐owned dogs: 15 dogs with CES and 9 dogs euthanized for unrelated medical reasons (controls).

Methods

Prospective, experimental study. Epidural adipose tissue and subcutaneous adipose tissue were collected during dorsal laminectomy and used for real‐time quantitative polymerase chain reaction. Tissue explants were cultured for measurements of inflammation‐induced release of cytokines.

Results

Results show a CES‐associated upregulation of the cytokines tumor necrosis factor alpha (TNFα: mean ± SD: 18.88 ± 11.87, 95% CI: 10.90‐26.86 vs 9.66 ± 5.22, 95% CI: 5.29‐14.02, *: P = .04) and interleukin‐ (IL‐) 10 (20.1 ± 9.15, 95% CI: 14.82‐25.39 vs 11.52 ± 6.82, 95% CI: 5.82‐17.22, *: P = .03), whereas the expression of the adipokine leptin was attenuated in EAT of dogs with CES (3.07 ± 2.29, 95% CI: 1.80‐3.34 vs 9.83 ± 8.42, 95% CI: 3.36‐16.30, **: P = .007). Inflammatory stimulation of EAT explant cultures resulted in an enhanced release of IL‐6 (LPS: 5491.55 ± 4438, 95% CI: 833.7‐10 149; HMGB1: 1001.78 ± 522.2, 95% CI: 518.8‐1485; PBS: 310.9 ± 98.57, 95% CI: 228.5‐393.3, ***: P < .001).

Conclusion and Clinical Importance

Expression profile of inflammatory adipo(‐cyto)kines by EAT is influenced from compressive forces acting in dogs with CES and might contribute to amplification of pain.

Mesenchymal stromal/stem cells and their exosomes application in the treatment of intervertebral disc disease: A promising frontier

Today, the application of mesenchymal stromal/stem cells (MSCs) and their exosomes to treat degenerative diseases has received attention. Due to the characteristics of these cells, such as self-renewability, differentiative and immunomodulatory effects, their use in laboratory and clinical studies shows promising results. However, the allogeneic transplantation problems of MSCs limit the use of these cells in the clinic. Scientists propose the application of exosomes to use from the therapeutic effect of MSCs and overcome their defects. These vesicles change the target cell behaviour and transcription profile by transferring various cargo such as proteins, mi-RNAs, and lipids. One of the degenerative tissue diseases in which MSCs and their exosomes are used in their treatment is intervertebral disc disease (IDD). Different factors such as genetics, nutrition, ageing, and environmental factors play a significant role in the onset and progression of this disease. These factors affect the cellular and molecular properties of the disc, leading to tissue destruction. Nucleus pulposus cells (NPCs) are among the most important cells involved in the pathogenesis of disc degeneration. MSCs exert their therapeutic effects by differentiating, reducing apoptosis, increasing proliferation, and decreasing senescence in NPCs. In addition, the use of MSCs and their exosomes also affects the annulus fibrosus and cartilaginous endplate cells in disc tissue and prevents disc degeneration progression.

Circulating HMGB1 is increased in myelodysplastic syndrome but not in other bone marrow failure syndromes: proof-of-concept cross-sectional study

Background

Myelodysplastic syndrome (MDS) is associated with persistent immune activation. High mobility group box-1 (HMGB1) is a ubiquitous, functionally diverse, non-histone intranuclear protein. During acute and chronic inflammatory states, HMGB1 is actively released by inflammatory cells, further amplifying the inflammatory response. A role in MDS and other hypoplastic bone marrow (BM) disorders is incompletely understood.

Objectives

The objective of the study is to evaluate whether circulating HMGB1 is elevated in patients with MDS and other BM failure syndromes [namely, aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH)].

Design

This is a observational, cross-sectional, single-center, exploratory study.

Methods

We evaluated circulating concentrations of HMGB1, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in patients with MDS and age-matched hematologically healthy controls as well as patients with AA and PNH.

Results

We included 66 patients with MDS and 65 age-matched controls as well as 44 patients with other BM failures (AA = 27, PNH = 17). Circulating levels of HMGB1 were higher in patients with MDS [median, 4.9 ng/ml; interquartile range (IQR): 2.3-8.1] than in AA (median, 2.6 ng/ml; IQR: 1.7-3.7), PNH (median, 1.7 ng/ml; IQR: 0.9-2.5), and age-matched healthy individuals (median, 1.9 ng/ml; IQR: 0.9-2.5) (p = 0.0001). We observed higher concentrations of HMGB1 in the very low/low-risk MDS patients than in the intermediate/high/very high-risk ones (p = 0.046). Finally, in comparison with patients with AA, those with hypocellular MDS (h-MDS) had significantly higher levels of circulating HMGB1 (n = 14; median concentration, 5.6 ng/ml, IQR: 2.8-7.3; p = 0.006). We determined a circulating HMGB1 value of 4.095 ng/ml as a diagnostic cutoff differentiator between h-MDS and AA.

Conclusion

These observations indicate that circulating HMGB1 is increased in patients with MDS. HMGB1 (but not IL-1β or TNF-α) differentiated between MDS and other BM failures, suggesting that HMGB1 may be mechanistically involved in MDS and a druggable target to decrease inflammation in MDS.

Magnoflorine Alleviates "M1" Polarized Macrophage-Induced Intervertebral Disc Degeneration Through Repressing the HMGB1/Myd88/NF-κB Pathway and NLRP3 Inflammasome

Intervertebral disc degeneration (IDD) is related to the deterioration of nucleus pulposus (NP) cells due to hypertrophic differentiation and calcification. The imbalance of pro-inflammatory (M1 type) and anti-inflammatory (M2 type) macrophages contributes to maintaining tissue integrity. Here, we aimed to probe the effect of Magnoflorine (MAG) on NP cell apoptosis mediated by “M1” polarized macrophages. THP-1 cells were treated with lipopolysaccharide (LPS) to induce “M1” polarized macrophages. Under the treatment with increasing concentrations of MAG, the expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-18), high mobility group box protein 1 (HMGB1), as well as myeloid differentiation factor 88 (MyD88), nuclear factor kappa B (NF-κB) and NOD-like receptor 3 (NLRP3) inflammasomes in THP-1 cells were determined. What’s more, human NP cells were treated with the conditioned medium (CM) from THP-1 cells. The NP cell viability and apoptosis were evaluated. Western blot (WB) was adopted to monitor the expression of apoptosis-related proteins (Bax, Caspase3, and Caspase9), catabolic enzymes (MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5), and extracellular matrix (ECM) compositions (collagen II and aggrecan) in NP cells. As a result, LPS evidently promoted the expression of pro-inflammatory cytokines and HMGB1, the MyD88-NF-κB activation, and the NLRP3 inflammasome profile in THP-1 cells, while MAG obviously inhibited the "M1″ polarization of THP-1 cells. After treatment with “M1” polarized THP-1 cell CM, NP cell viability was decreased, while cell apoptosis, the pro-inflammatory cytokines, apoptosis-related proteins, and catabolic enzymes were distinctly up-regulated, and ECM compositions were reduced. After treatment with MAG, NP cell damages were dramatically eased. Furthermore, MAG dampened the HMGB1 expression and inactivated the MyD88/NF-κB pathway and NLRP3 inflammasome in NP cells. In conclusion, this study confirmed that MAG alleviates “M1” polarized macrophage-mediated NP cell damage by inactivating the HMGB1-MyD88-NF-κB pathway and NLRP3 inflammasome, which provides a new reference for IDD treatment.

NF-κB signalling pathways in nucleus pulposus cell function and intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common clinical degenerative disease of the spine. A series of factors, such as inflammation, oxidative stress and mechanical stress, promote degradation of the extracellular matrix (ECM) of the intervertebral discs (IVD), leading to dysfunction and structural destruction of the IVD. Nuclear factor-κB (NF-κB) transcription factor has long been regarded as a pathogenic factor of IDD. Therefore, NF-κB may be an ideal therapeutic target for IDD. As NF-κB is a multifunctional functional transcription factor with roles in a variety of biological processes, a comprehensive understanding of the function and regulatory mechanism of NF-κB in IDD pathology will be useful for the development of targeted therapeutic strategies for IDD, which can prevent the progression of IDD and reduce potential risks. This review discusses the role of the NF-κB signalling pathway in the nucleus pulposus (NP) in the process of IDD to understand pathological NP degeneration further and provide potential therapeutic targets that may interfere with NF-κB signalling for IDD therapy.

Inhibition of toll-like receptor 4 protects against inflammation-induced mechanobiological alterations to intervertebral disc cells

Intervertebral disc (IVD) degeneration is associated with elevated levels of inflammatory cytokines implicated in disease aetiology and matrix degradation. Toll-like receptor-4 (TLR4) has been shown to participate in the inflammatory responses of the nucleus pulposus (NP) and its levels are upregulated in disc degeneration. Activation of TLR4 in NP cells leads to significant, persistent changes in cell biophysical properties, including hydraulic permeability and osmotically active water content, as well as alterations to the actin cytoskeleton. The study hypothesis was that inflammation-induced changes to cellular biomechanical properties and actin cytoskeleton of NP cells could be prevented by inhibiting TLR4 signalling. Isolated NP cells from bovine discs were treated with lipopolysaccharide (LPS), the best studied TLR4 agonist, with or without treatment with the TLR4 inhibitor TAK-242. Cellular volume regulation responses to step osmotic loading were measured and the transient volume-response was captured by time-lapse microscopy. Volume-responses were analysed using mixture theory framework to investigate hydraulic permeability and osmotically active intracellular water content. Hydraulic permeability and cell radius were significantly increased with LPS treatment and these changes were blocked in cells treated with TAK-242. LPS-induced remodelling of cortical actin and IL-6 upregulation were also mitigated by TAK-242 treatment. These findings indicated that TLR4 signalling participated in NP cell biophysical regulation and may be an important target for mitigating altered cell responses observed in IVD inflammation and degeneration.

The role of high mobility group protein B3 (HMGB3) in tumor proliferation and drug resistance

The high mobility group protein B (HMGB) family (including HMGB1, HMGB2, HMGB3, and HMGB4) can regulate the mechanisms of DNA replication, transcription, recombination, and repair, and act as cytokines to mediate responses to infection, injury, and inflammation. HMGB1/2/3 has a high similarity in sequence and structure, while HMGB4 has no acidic C-terminal tail. Among them, HMGB3 can regulate the self-renewal and differentiation of normal hematopoietic stem cell population, but the decrease of its expression is easy to induce leukemia. Up-regulation of its expression promotes tumor development and chemotherapy resistance through a variety of mechanisms, and non-coding RNA can regulate to promote tumor cell proliferation, invasion, and migration and inhibit cancer cell apoptosis.

Anti‑inflammatory mechanism of berberine on lipopolysaccharide‑induced IEC‑18 models based on comparative transcriptomics

Intestinal surface epithelial cells (IECs) have long been considered as an effective barrier for maintaining water and electrolyte balance, and are involved in the mechanism of nutrient absorption. When intestinal inflammation occurs, it is often accompanied by IEC malfunction. Berberine (BBR) is an isoquinoline alkaloid found in numerous types of medicinal plants, which has been clinically used in China to treat symptoms of gastrointestinal pathogenic bacterial infection, especially bacteria‑induced diarrhea and inflammation. In the present study, IEC‑18 rat intestinal epithelial cells were treated with lipopolysaccharide (LPS) to establish an in vitro model of epithelial cell inflammation, and the cells were subsequently treated with BBR in order to elucidate the anti‑inflammatory mechanism. Transcriptome data were then searched to find the differentially expressed genes (DEGs) compared between two of the treatment groups (namely, the LPS and LPS+BBR groups), and DEGs were analyzed using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Weighted Gene Correlation Network Analysis and Interactive Pathways Explorer to identify the functions and pathways enriched with DEGs. Finally, reverse transcription‑quantitative PCR was used to verify the transcriptome data. These experiments revealed that, comparing between the LPS and LPS+BBR groups, the functions and pathways enriched in DEGs were 'DNA replication', 'cell cycle', 'apoptosis', 'leukocyte migration' and the 'NF‑κB and AP‑1 pathways'. The results revealed that BBR is able to restrict DNA replication, inhibit the cell cycle and promote apoptosis. It can also inhibit the classic inflammatory pathways, such as those mediated by NF‑κB and AP‑1, and the expression of various chemokines to prevent the migration of leukocytes. According to transcriptomic data, BBR can exert its anti‑inflammatory effects by regulating a variety of cellular physiological activities, including cell cycle, apoptosis, inflammatory pathways and leukocyte migration.

Advanced glycation end products cause RAGE-dependent annulus fibrosus collagen disruption and loss identified using in situ second harmonic generation imaging in mice intervertebral disk in vivo and in organ culture models

Aging and diabetes are associated with increased low-back pain and intervertebral disk (IVD) degeneration yet causal mechanisms remain uncertain. Advanced glycation end products (AGEs), which accumulate in IVDs from aging and are implicated in diabetes-related disorders, alter collagen and induce proinflammatory conditions. A need exists for methods that assess IVD collagen quality and degradation in order to better characterize specific structural changes in IVDs due to AGE accumulation and to identify roles for the receptor for AGEs (RAGE). We used multiphoton microscopy with second harmonic generation (SHG), collagen-hybridizing peptide (CHP), and image analysis methods to characterize effects of AGEs and RAGE on collagen quality and quantity in IVD annulus fibrosus (AF). First, we used SHG imaging on thin sections with an in vivo dietary mouse model and determined that high-AGE (H-AGE) diets increased AF fibril disruption and collagen degradation resulting in decreased total collagen content, suggesting an early degenerative cascade. Next, we used in situ SHG imaging with an ex vivo IVD organ culture model of AGE challenge on wild type and RAGE-knockout (RAGE-KO) mice and determined that early degenerative changes to collagen quality and degradation were RAGE dependent. We conclude that AGE accumulation leads to RAGE-dependent collagen disruption in the AF and can initiate molecular and tissue level collagen disruption. Furthermore, SHG and CHP analyzes were sensitive to collagenous alterations at multiple hierarchical levels due to AGE and may be useful in identifying additional contributors to collagen damage in IVD degeneration processes.

High-mobility group box 1 is a driver of inflammation throughout pregnancy

A proinflammatory response driven by high-mobility group box 1 (HMGB1) is important for the success of both the early stages of pregnancy and parturition initiation. However, the tight regulation of HMGB1 within these two stages is critical, as increased HMGB1 can manifest into pregnancy-related pathologies. Although during the early stages of pregnancy HMGB1 is critical for the development and implantation of the embryo, and uterine decidualization, high levels within the uterine cavity have been linked to pregnancy failure. In addition, chronic inflammation, resultant from increased HMGB1 within the maternal circulation and gestational tissues, also increases the risk for preterm labor, preterm birth, or infant mortality. Due to the link between HMGB1 and several pregnancy pathologies, the possibility of leveraging HMGB1 as a biomarker has been assessed. However, data are limited that demonstrate how known HMGB1 inhibitors could reduce inflammation within pregnancy. Thus, further research is warranted to improve our understanding of the potential of HMGB1 as a therapeutic target to reduce inflammation within pregnancy. This review aims to describe what is understood about the role of HMGB1 that drives inflammation throughout pregnancy and highlight its potential as a biomarker and therapeutic target within this context.

LncRNA TUG1 promotes the intervertebral disc degeneration and nucleus pulposus cell apoptosis though modulating miR-26a/HMGB1 axis and regulating NF-κB activation

AIMS

This study was to investigate the effect of TUG1 on apoptosis and ECM degradation of human degenerative intervertebral disc nucleus pulposus cells (NPCs) and its mechanism.

METHODS

Human degenerative intervertebral disc NP tissues were obtained from 10 patients with lumbar disc herniation (LDH) who underwent lumbar spine surgery (IDD group), normal intervertebral disc NP tissues were obtained from 10 patients with lumbar vertebrae fractures (LVF group).

RESULTS

The expression of TUG1 and HMGB1 protein in human degenerative disc NP tissues and NPCs was significantly increased, while the level of miR-26a was significantly decreased. Overexpression of TUG1 inhibited the proliferation while promoted apoptosis and ECM degradation of human degenerative intervertebral disc NPCs. Simultaneously, the effect of TUG1 knockdown on NPCs was opposite. Interestingly, TUG1 acted as an endogenous sponge to down-regulate the expression of miR-26a in NPCs by direct binding to miR-26a. Overexpression of miR-26a reversed the effects of TUG1 overexpression on apoptosis and ECM degradation. Additionally, HMGB1 was a target gene of miR-26a. The increased expression of HMGB1 induced by TUG1 overexpression could be reversed by the introduction of miR-26a mimic. Overexpression of TUG1 significantly upregulated the expression of p65 in the nucleus, while overexpression of TUG1 partially abolished the inhibition of NF-κB by QNZ pretreatment.

CONCLUSION

TUG1 could promote the apoptosis and ECM degradation of degenerated intervertebral disc NPCs by regulating the miR-26a/HMGB1, which may be involved in the activation of NF-κB pathway.

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.

Astrocyte regional diversity in ALS includes distinct aberrant phenotypes with common and causal pathological processes

Astrocytes are major contributors of motor neuron (MN) degeneration in amyotrophic lateral sclerosis (ALS). We investigated whether regional and cell maturation differences influence ALS astrocyte malfunction. Spinal and cortical astrocytes from SOD1G93A (mSOD1) 7-day-old mice were cultured for 5 and 13 days in vitro (DIV). Astrocyte aberrancies predominated in 13DIV cells with region specificity. 13DIV cortical mSOD1 astrocytes showed early morphological changes and a predominant reactive and inflammatory phenotype, while repressed proteins and genes were found in spinal cells. Inflammatory-associated miRNAs, e.g. miR-155/miR-21/miR-146a, were downregulated in the first and upregulated in the later ones. Interestingly, depleted miR-155/miR-21/miR-146a in small extracellular vesicles (sEVs/exosomes) was a common pathological feature. Cortical mSOD1 astrocytes induced late apoptosis and kinesin-1 downregulation in mSOD1 NSC-34 MNs, whereas spinal cells upregulated dynein, while decreased nNOS and synaptic-related genes. Both regional-distinct mSOD1 astrocytes enhanced iNOS gene expression in mSOD1 MNs. We provide information on the potential contribution of astrocytes to ALS bulbar-vs. spinal-onset pathology, local influence on neuronal dysfunction and their shared miRNA-depleted exosome trafficking. These causal and common features may have potential therapeutic implications in ALS. Future studies should clarify if astrocyte-derived sEVs are active players in ALS-related neuroinflammation and glial activation.

Avidin grafted dextran nanostructure enables a month-long intra-discal retention

Low back pain is often the direct result of degeneration of the intervertebral disc. A wide range of therapeutics including anti-catabolic, pro-anabolic factors and chemo-attractants that can stimulate resident cells and recruit endogenous progenitors are under consideration. The avascular nature and the dense matrix of this tissue make it challenging for systemically administered drugs to reach their target cells inside the nucleus pulposus (NP), the central gelatinous region of the intervertebral disc (IVD). Therefore, local intra-discal injection of therapeutic drugs directly into the NP is a clinically relevant delivery approach, however, suffers from rapid and wide diffusion outside the injection site resulting in short lived benefits while causing systemic toxicity. NP has a high negative fixed charge density due to the presence of negatively charged aggrecan glycosaminoglycans that provide swelling pressures, compressive stiffness and hydration to the tissue. This negative fixed charge density can also be used for enhancing intra-NP residence time of therapeutic drugs. Here we design positively charged Avidin grafted branched Dextran nanostructures that utilize long-range binding effects of electrostatic interactions to bind with the intra-NP negatively charged groups. The binding is strong enough to enable a month-long retention of cationic nanostructures within the NP following intra-discal administration, yet weak and reversible to allow movement to reach cells dispersed throughout the tissue. The branched carrier has multiple sites for drug conjugation and can reduce the need for multiple injections of high drug doses and minimize associated side-effects, paving the way for effective clinical translation of potential therapeutics for treatment of low back pain and disc degeneration.

Overexpression of miR-150 Inhibits the NF-κB Signal Pathway in Intervertebral Disc Degeneration through Targeting P2X7

Objective: To elaborate the mechanism of miR-150 in the regulation of the NF-κB signal pathway in intervertebral disc degeneration (IDD) by targeting P2X7. Methods: The degenerative and normal intervertebral disc tissues were collected to detect the expressions of miR-150 and P2X7. Nucleus pulposus cells were transfected and divided into different groups. Cell apoptosis was determined by flow cytometry and TUNEL staining. The expressions of IL-6, TNF-α, MMP-3, MMP-13, Cox-2, iNOS, collagen II and aggrecan, as well as NF-κB-associated proteins were measured by qRT-PCR and Western blotting. Furthermore, IDD rat models were established to validate the role of miR-150 in vivo.Results: miR-150 was down-regulated but P2X7 was up-regulated in the degenerative intravertebral disc tissues. The apoptosis of nucleus pulposus cells in the IL-1β-induced group with the transfection of miR-150 mimic and siP2X7 was significantly decreased, with reduced levels of IL-6, TNF-α, MMP-3, MMP-13, Cox-2 and iNOS, increased levels of collagen II and aggrecan, as well as decreased P2X7, p-p65/p65 and cleaved caspase-3. However, the above factors showed an opposite tendency after treatment with miR-150 inhibitor. Furthermore, the P2X7 siRNA transfection could reverse the effects caused by miR-150 inhibitor. Simultaneously, pcDNA P2X7 transfection also inhibited the function of miR-150 mimic in IL-1β-induced nucleus pulposus cells. In vivoexperiments further verified the protective role of miR-150 in IDD rats. Conclusion: miR-150 may alleviate the degeneration of the intervertebral disc partially since it could restrict the NF-κB pathway by targeting P2X7, and thereby inhibiting IL-1β-induced matrix catabolism, inflammatory responses and apoptosis of the nucleus pulposus cells.

HMGB1 participates in LPS‑induced acute lung injury by activating the AIM2 inflammasome in macrophages and inducing polarization of M1 macrophages via TLR2, TLR4, and RAGE/NF‑κB signaling pathways

High mobility group box 1 (HMGB1), a crucial proinflammatory cytokine, was reported to activate the absent in melanoma 2 (AIM2) inflammasome, which are both essential in acute lung injury (ALI). However, their interaction mechanism has remained elusive. Macrophages are known to express the AIM2 inflammasome and the main receptors [receptor for advanced glycation end products (RAGE), Toll‑like receptor 2/4 (TLR‑2/TLR‑4)] of HMGB1 to transmit intracellular signals. The present study aimed to indicate whether HMGB1 participates in the process of lipopolysaccharides (LPS)‑induced ALI through activating the AIM2 inflammasome in macrophages, as well as inducing polarization of M1 macrophages via TLR2, TLR4 and RAGE/ nuclear factor‑κB (NF‑κB) signaling pathways. In an in vivo mouse model of LPS‑induced ALI, anti‑HMGB1, recombinant (r)HMGB1, LPS from Rhodobacter sphaeroides (LPS‑RS, TLR2/4 antagonist) or FPS‑ZM1 (RAGE antagonist) were administrated. In in vitro studies, bone marrow‑derived macrophages from mice primed with LPS were stimulated with or without anti‑HMGB1, rHMGB1, LPS‑RS, or FPS‑ZM1. The findings revealed that anti‑HMGB1, LPS‑RS and FPS‑ZM1 significantly decreased infiltration of inflammatory cells, wet‑to‑dry ratio, myeloperoxidase activity in the lung, the levels of cytokines, as well as macrophages and neutrophil infiltration in the bronchoalveolar lavage fluid. However, rHMGB1 aggravated the inflammatory response in ALI. Mechanistically, anti‑HMGB1, LPS‑RS and FPS‑ZM1 attenuated activation of TLR2, TLR4, and RAGE/NF‑κB signaling pathways and expression of the AIM2 inflammasome in macrophages. However, rHMGB1 enhanced their expression levels and induced polarization of M1 macrophages. These results indicated that HMGB1 could participate in the pathogenesis of ALI by activating the AIM2 inflammasome in macrophages, as well as inducing polarization of M1 macrophages through TLR2, TLR4 and RAGE/NF‑κB signaling pathways.

1,4-Dihydropyridine (DHP) suppresses against oxidative stress in nucleus pulposus via activating sirtuin-1

Intervertebral disc degeneration (IVDD) is a major cause of many spinal diseases characterized mainly by nucleus pulposus degradation. 1,4-dihydropyridine (DHP), a new activator of sirtuin-1 (sirt1), has been reported to have anti-oxidative effects. The aim of this study is to investigate the effect of DHP on nucleus pulposus (NP) cells in vitro. NP cells were pretreated with IL-1β to establish a degenerated model, and then treated with DHP alone or DHP combined with selisistat (an inhibitor of sirt1). ROS level was analyzed by flow cytometry. Production of IL-6 and TNF-α were evaluated by the enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expression were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot respectively. Immunofluorescence was used to assess the expression of collagen-II and sirt1. We found that DHP inhibited IL-1β-induced upregulation of ROS, TNF-α, IL-6, MMP-3, ADAMTS-5. Besides, DHP remarkably increased the sirt1 and anti-oxidative protein SOD-1 level. Furthermore, DHP significantly protected the IL-1β-induced degradation of collagen-II and aggrecan. However, the inhibitory effect of DHP was obvious abolished by selisistat, suggesting that DHP exerts these effects in NP cells through activating sirt1. Taken together, we found that DHP inhibited the ROS, inflammatory response and ECM degradation through activating Sirt1 in human NP cells.

Glycyrrhizin suppresses inflammation and cell apoptosis by inhibition of HMGB1 via p38/p-JUK signaling pathway in attenuating intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is associated with the nucleus pulposus (NP) cells inflammation and apoptosis. Previous studies have shown that glycyrrhizin (GL) is a valid inhibitor of the high-mobility group box-1 gene (HMGB1) which expressed much higher in an inflammatory condition. However, it is not known whether GL protects against IDD by the inhibition of HMGB1. To study the effect and mechanism of glycyrrhizin on intervertebral disc degeneration. We analyzed the expression of HMGB1 in different degree of degenerate disc tissues. Interleukin 1 beta (IL-1β) was used in stimulating the NP cells to degeneration. We used recombined human HMGB1 to resist the function of GL to explore whether GL acted via the target of HMGB1. Our study showed that the expression of HMGB1 markedly increased in severely degenerated disc tissues. IL-1β promoted the progress of IDD, and the stimulation of GL could reverse the effects of IL-1β. Moreover, p38 and p-JNK were significantly suppressed by GL stimuli. These results suggested that GL prevented NP degradation via restraining inflammation and cell apoptosis by inhibition of HMGB1 via p38/p-JNK signaling pathway. GL may become a novel cytokine for the therapy of IDD in the future.

Elevated resistin levels may regulate high mobility group box 1 expression in Guillain-Barré syndrome

Interactions among cytokines have important roles in the inflammatory processes underlying Guillain-Barré syndrome (GBS). Resistin and high mobility group box 1 (HMGB1) are involved in many inflammatory processes. This study examined 51 GBS patients, and found that serum resistin levels were elevated in 51 patients with GBS and correlated with HMGB1 levels. In vitro, resistin induced the release of HMGB1, interleukin (IL)-1β, and IL-6 in THP-1 macrophages. This process was dependent on activation of p38 mitogen-activated protein kinase and NF-κB signaling pathways. These results suggest that signaling between resistin and HMGB1 might be a potential therapeutic target in GBS.

Ligustilide alleviated IL-1β induced apoptosis and extracellular matrix degradation of nucleus pulposus cells and attenuates intervertebral disc degeneration in vivo

Intervertebral disc degeneration is a multifactorial and complicated degenerative disease that imposes a huge economic burden on society. However, there is no effective treatment that can delay and reverse the progression of disc degeneration. The inflammatory response causes the death of nucleus pulposus cells and the degradation of extracellular matrix are main factors of intervertebral disc degeneration. Ligustilide is a bioactive phthalide that is said to have an anti-inflammatory effect and anti-apoptosis effect on various disorders. Therefore, we further explored the protective effect of ligustilide on intervertebral disc degeneration and its potential mechanism. In this study, we found that ligustilide inhibited apoptosis, suppressed the expression of related inflammatory mediators (iNOS and COX-2) and decreased the expression of inflammatory cytokines (TNF-a and IL-6) in nucleus pulposus cells under IL-1β stimulation. At the same time, the degradation of extracellular matrix of nucleus pulposus cells induced by IL-1β was inhibited. In addition, we also found that ligustilide inhibits the inflammation response by inhibiting the NF-κB signaling pathway. Moreover, TUNEL assay and histological analysis showed that ligustilide could inhibit the apoptosis of nucleus pulposus cells and ameliorate the progression of intervertebral disc degeneration in punctured Rat IDD model. In summary, ligustilide may become a new potential treatment for intervertebral disc degeneration.

29-kDa FN-f inhibited autophagy through modulating localization of HMGB1 in human articular chondrocytes

Fibronectin fragments found in the synovial fluid of patients with osteoarthritis (OA) induce the catabolic responses in cartilage. Nuclear high-mobility group protein Box 1 (HMGB1), a damage-associated molecular pattern, is responsible for the regulation of signaling pathways related to cell death and survival in response to various stimuli. In this study, we investigated whether changes induced by 29-kDa aminoterminal fibronectin fragment (29-kDa FN-f) in HMGB1 expression influences the pathogenesis of OA via an HMGB1- modulated autophagy signaling pathway. Human articular chondrocytes were enzymatically isolated from articular cartilage. The level of mRNA was measured by quantitative real-time PCR. The expression of proteins was examined by western blot analysis, immnunofluorescence assay, and enzyme-linked immunosorbent assay. Interaction of proteins was evaluated by immunoprecipitation. The HMGB1 level was significantly lower in human OA cartilage than in normal cartilage. Although 29-kDa FN-f significantly reduced the HMGB1 expression at the mRNA and protein levels 6 h after treatment, the cytoplasmic level of HMGB1 was increased in chondrocytes treated with 29-kDa FN-f, which significantly inhibited the interaction of HMGB1 with Beclin-1, increased the interaction of Bcl-2 with Beclin-1, and decreased the levels of Beclin-1 and phosphorylated Bcl-2. In addition, the level of microtubule-associated protein 1 light chain 3-II, an autophagy marker, was down-regulated in chondrocytes treated with 29-kDa FN-f, whereas the effect was antagonized by mTOR knockdown. Furthermore, prolonged treatment with 29-kDa FN-f significantly increased the release of HMGB1 into the culture medium. These results demonstrated that 29-kDa FN-f inhibits chondrocyte autophagy by modulating the HMGB1 signaling pathway. [BMB Reports 2018; 51(10): 509-514].

Upregulation of miR-107 expression following hyperbaric oxygen treatment suppresses HMGB1/RAGE signaling in degenerated human nucleus pulposus cells

Background

The expression of both high-mobility group box 1 (HMGB1) and receptor for advanced glycation end-products (RAGE) is upregulated in degenerated discs. HMGB1 is known to function as a coupling factor between hypoxia and inflammation in arthritis, and this inflammatory response is modulated by microRNAs (miRNAs), with miR-107 expression downregulated during hypoxia. In this study, we investigated the regulation of the miR-107/HMGB1/RAGE pathway in degenerated nucleus pulposus cells (NPCs) after hyperbaric oxygen (HBO) treatment.

Methods

NPCs were separated from human degenerated intervertebral disc tissues. The control cells were maintained in 5% CO₂/95% air, and the hyperoxic cells were exposed to 100% O₂ at 2.5 atmospheres absolute. MiRNA expression profiling was performed via microarray and confirmed by real-time PCR, and miRNA target genes were identified using bioinformatics and luciferase reporter assays. The cellular protein and mRNA levels of HMGB1, RAGE, and inducible nitric oxide synthase (iNOS) were assessed, and the phosphorylation of MAPK (p38MAPK, ERK, and JNK) was evaluated. Additionally, cytosolic and nuclear fractions of the IκBα and NF-κB p65 proteins were analyzed, and secreted HMGB1 and metalloprotease (MMP) levels in the conditioned media were quantified.

Results

Using microarray analyses, 96 miRNAs were identified as upregulated and 66 downregulated following HBO treatment. Based on these results, miR-107 was selected for further investigation. Bioinformatics analyses indicated that the 3′ untranslated region of the HMGB1 mRNA contained the “seed-matched-sequence” for hsa-miR-107, which was validated via dual-luciferase reporter assays. MiR-107 was markedly induced by HBO, and simultaneous suppression of HMGB1 was observed in NPCs. Knockdown of miR-107 resulted in upregulation of HMGB1 expression in HBO-treated cells, and HBO treatment downregulated the mRNA and protein levels of HMGB1, RAGE, and iNOS and the secretion of HMGB1. In addition, HBO treatment upregulated the protein levels of cytosolic IκBα and decreased the nuclear translocation of NF-κB in NPCs. Moreover, HBO treatment downregulated the phosphorylation of p38MAPK, ERK, and JNK and significantly decreased the secretion of MMP-3, MMP-9, and MMP-13.

Conclusions

HBO inhibits pathways related to HMGB1/RAGE signaling via upregulation of miR-107 expression in degenerated human NPCs.

miR-125 regulates PI3K/Akt/mTOR signaling pathway in rheumatoid arthritis rats via PARP2

The present study aimed to explore miR-125 effects on rheumatoid arthritis (RA) development to provide a potential target for RA. Briefly, rat RA model was established (Model group) by injection of Freund’s Complete Adjuvant into the left hind toe. Normal rats injected with saline in the same location were set as Normal group. All rats’ secondary foot swelling degree, polyarthritis index score, spleen and thymus index were measured. Synovial tissues were subjected to Hematoxylin–Eosin (HE) staining and immunohistochemistry. Synovial cells of each group were isolated and named as Normal-C group and Model-C group, respectively. Synovial cells of Model-C group further underwent cotransfection with miR-125 mimics and PARP2-siRNA (mimics+siPARP2 group) or with miR-125 negative control (NC) and PARP2-siRNA NC (NC group). Quantitative reverse transcriptase PCR (qRT-PCR), Western blot, luciferase reporter assay, ELISA, and MTT assay were performed. As a result, compared with Normal group, rats of Model group showed significantly higher secondary foot swelling degree, polyarthritis index score, spleen and thymus index (P<0.01). Down-regulated miR-125 and up-regulated PARP2 was found in synovial tissues of Model group when compared with Normal group (P<0.01). Synovial tissues of Model-C group exhibited severe hyperplasia and inflammatory cell infiltration. Luciferase reporter assay indicated that PARP2 was directly inhibited by miR-125. Compared with NC group, cells of mimics+siPARP2 group had significantly lower IL-1β, MMP-1 and TIMP-1 levels, absorbance value, and p-PI3K, p-Akt and p-mTOR relative expression (P<0.01 or P<0.05). Thus, miR-125 might attenuate RA development by regulating PI3K/Akt/mTOR signaling pathway via directly inhibiting PARP2 expression.

High mobility group box-1 induces pro-inflammatory signaling in human nucleus pulposus cells via toll-like receptor 4-dependent pathway

Intervertebral disc (IVD) degeneration (DD) is associated with low back pain, the leading cause of disability worldwide. Damage-associated molecular patterns (DAMPs) that contribute to inflammation and trigger DD have not been well characterized. Extracellular high mobility group box-1 (HMGB1) protein has been implicated as a potent DAMP and pro-inflammatory stimulus in the immune system. In this study, we show that HMGB1 and IL-6 levels increase in patients with advanced DD in comparison to early DD. This study further tested the hypothesis that HMGB1 promotes inflammatory signaling driving DD in human nucleus pulposus (NP) cells and tissue. Immunofluorescence and western blot analysis confirmed the expression of HMGB1 and its extracellular release by NP cells under cell stress. Gene expression and protein quantification indicate that HMGB1 stimulates the expression IL-6 and MMP-1 in a dose-dependent manner. The contributions of toll-like receptor (TLR) -2, -4 and receptor for advanced glycation end products (RAGE) as receptors mediating HMGB1 signaling was examined using small molecule inhibitors. Inhibition of TLR-4 signaling, with TAK-242, completely abrogated HMGB1 induced IL-6 and MMP-1 expression, whereas inhibition of TLR-2, with O-vanillin, or RAGE, with FPS-ZM1, had mild inhibitory effects. HMGB1 stimulation activated NF-ĸB signaling while TAK-242 co-treatment abrogated it. Lastly, effects of HMGB1 on matrix deposition was evaluated in a 3D culture system of human NP cells. These results implicate HMGB1 as a potent DAMP that promotes inflammation in NP cells and degradation of NP tissues. TLR4-HMGB1 axis is a potential major pathway to alleviate disc inflammation and mitigate DD. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

TSG-6 secreted by bone marrow mesenchymal stem cells attenuates intervertebral disc degeneration by inhibiting the TLR2/NF-κB signaling pathway

Inflammation has been correlated with intervertebral disc degeneration (IDD). Recent evidence suggests that TNF-α-stimulated gene 6 protein (TSG-6) secreted by bone marrow mesenchymal stem cells (BMSCs) displays a remarkable ability to inhibit inflammatory processes in a variety of diseases. However, it is unknown whether BMSCs exert their therapeutic effect against IDD by secreting TSG-6. Here we investigated the effects of BMSCs and TSG-6 on IDD and explored the possible underlying mechanisms in vitro and in vivo. We found that BMSCs and TSG-6 reduced the expression of MMP-3 and MMP-13, and increased the expression of collagen II and aggrecan in the IL-1β-treated nucleus pulposus cells (NPCs), but the protective effects of BMSCs and TSG-6 were attenuated when TSG-6 expression was silenced. We also found that the activation of the TLR2/NF-κB pathway was inhibited by BMSCs and TSG-6. The levels of IL-6 and TNF-α in the degenerated NPCs were reduced and the proliferation of IL-1β-treated NPCs was increased in the presence of BMSCs and TSG-6. Furthermore, in vivo experiments showed that BMSCs and TSG-6 restored the MRI T2-weighted signal intensity and increased collagen II and aggrecan expression in the degenerated nucleus pulposus (NP) tissues. Finally, our results showed that BMSCs and TSG-6 downregulated the TLR2/NF-κB signaling and reduced the expression of MMPs and inflammatory cytokines in the degenerated NP tissues. The present study is the first to demonstrate the involvement of TLR2/NF-κB pathway in the potential anti-IDD therapeutic effect of TSG-6, and the results provide new insight into the beneficial effect of BMSCs in the treatment of IDD.

HMGB3 modulates ROS production via activating TLR cascade in Apostichopus japonicus

High mobility group box protein 3 (HMGB3) regulates proliferation and inflammatory response in vertebrates. However, its functional roles in invertebrates are largely unknown. In this study, a HMGB3 homologue molecule was identified from Apostichopus japonicus (designated as AjHMGB3) by RACE approach. The full-length cDNA of AjHMGB3 was of 2298 bp with an open reading frame of 1320 bp encoding a 439-amino-acid (aa) residue protein. Structural analysis then conducted and the results revealed that AjHMGB3 processed two conserved HMGBs (133-204 and 210-279 aa) and an acidic tail. The results of subsequent multiple sequence alignment and phylogenetic analysis both indicated that AjHMGB3 belongs to a new member of HMGB3 protein subfamily. Furthermore, AjHMGB3 was expressed in all examined tissues except in tentacles and particularly highly expressed in the intestine, as indicated by spatial expression analysis results. The Vibrio splendidus challenge in vivo and lipolysaccharide (LPS) stimulation in vitro can significantly upregulate the mRNA expression of AjHMGB3 in coelomocytes. This finding is consistent with the expression profiles of TLR cascade members. We further investigated the expression profiles of AjMyD88 and Ajp105 after the gain- or loss-of-function of AjHMGB3 in coelomocytes. The results showed that AjMyD88 and Ajp105 were upregulated 2.19- and 2.83-fold in AjHMGB3 overexpressed treatment and downregulated 0.38- and 0.43-fold in the AjHMGB3 silencing group. The p50 subunit displayed expression profiles that are identical to those of AjMyD88 and Ajp105 according to the Western blot results. In the same condition, the respiratory burst was increased by 37.5% in the AjHMGB3 overexpressed group and depressed by 28.2% in the AjHMGB3 knock-down group. Our present findings collectively suggested that AjHMGB3 acted as an NF-κB activator and produced ROS production in sea cucumbers.

The influence of surface EMG-triggered multichannel electrical stimulation on sensomotoric recovery in patients with lumbar disc herniation: study protocol for a randomized controlled trial (RECO)

Background

Intervertebral disc degeneration is one of the most common reasons for chronic low back pain and sensomotoric deficits, often treated by lumbar sequestrectomy. Nevertheless, the prognostic factors relevant for time and quality of recovery, of the surgical procedure, relative to conservative treatment, remain controversial and require further investigation. Surface electrical stimulation (SES) may be an influential intervention, already showing positive impact on motor and sensory recovery in different patient groups. Since mechanisms of SES still remain unclear, further inquiry is needed.

Methods/Design

This is a prospective, monocentric, randomized, controlled clinical trial. A total of 80 adult patients suffering from a lumbar disc herniation (LDH; 40 treated surgically, 40 conservatively) are allocated in a ratio of 1:1. Patients in the treatment group will receive surface electromyography (EMG)-triggered electrical stimulation for eight weeks, whereas patients in the control group will not obtain any additional treatment. The primary outcome parameter is defined as the cold detection threshold (CDT), determined by quantitative sensory testing (QST), 24 months after intervention. Secondary outcome parameters include the inquiry of sensory nerve function by two-point discrimination and QST, the assessment of motor nerve function by manual muscle testing, and validated scales and scores. These include: the Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) assessing the domains pain, back-specific function, work disability, and patient satisfaction; the EQ-5D investigating the patient’s generic health status; the painDETECT questionnaire (PD-Q) to identify neuropathic pain components; and the Beck Depression Inventory (BDI) to assess severity of depression. Moreover, neurological status, pain medication usage, and blood samples (CRP, TNFα, IL-1β, IL-6) will be evaluated. Study data generation (study site) and data storage, processing, and statistical analysis are clearly separated.

Discussion

The results of the RECO study will detect the effect of EMG-triggered multichannel SES on the improvement of mechanical and thermal sensitivity and the effect on motor recovery and pain, associated with clinical and laboratory parameters. Furthermore, data comparing surgical and conservative treatment can be collected. This will hopefully allow treatment recommendations for patients with LDH accompanied by a sensomotoric deficit.

Trial registration

ISRCTN, ISRCTN12741173. Registered on 15 January 2017.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2310-z) contains supplementary material, which is available to authorized users.

The role of lncRNA MALAT1 in intervertebral degenerative disc disease

Intervertebral degenerative disc disease (IDDD) is a common disease in clinic that causes pain and heavy financial burden on patients with poor prognosis. However, the pathogenesis of IDDD is not clear. Long non-coding RNA (LncRNA) is involved in regulating various body growth and pathological processes by affecting cell proliferation, differentiation, and apoptosis. However, the role of lncRNAs in IDDD is rarely reported. This study aims to investigate the role and mechanism of lncRNA MALAT1 in the development of IDDD. The nucleus pulposus of the intervertebral disc were collected and the primary nucleus pulposus cells were isolated and cultured. The cells were divided into three groups, including IDDD group, empty plasmid group transfected by pcDNA3.1, or MALAT1 group transfected by pcDNA3.1-MALAT1. MALAT1 expression was detected by real-time PCR. Cell proliferation was assessed by MTT assay. Caspase 3 activity was tested by the activity detection kit. IL-1 and IL-6 levels were analyzed by ELISA. The expression of MALAT1 in IDDD nucleus pulposus cells was significantly lower than that in control group (P < 0.05). The expression of MALAT1 was significantly increased after transfection with pcDNA3.1-MALAT1 plasmid in IDDD nucleus pulposus cells, which obviously inhibited cell proliferation, enhanced Caspase 3 activity, and promoted the secretion of IL-1 and IL-6 compared with IDDD group (P < 0.05). MALAT1 level decreased in IDDD nucleus pulposus cells. Upregulation of MALAT1 expression restrained IDDD through suppressing inflammation; inhibiting nucleus pulposus cell apoptosis, and promoting cell proliferation.

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.