Ozone as Modulator of Resorption and Inflammatory Response in Extruded Nucleus Pulposus Herniation. Revising Concepts.

Ozone therapy has been used to treat disc herniation for more than four decades. There are several papers describing results and mechanism of action. However, it is very important to define the characteristics of extruded disc herniation. Although ozone therapy showed excellent results in the majority of spinal diseases, it is not yet fully accepted within the medical community. Perhaps it is partly due to the fact that, sometimes, indications are not appropriately made. The objective of our work is to explain the mechanisms of action of ozone therapy on the extruded disc herniation. Indeed, these mechanisms are quite different from those exerted by ozone on the protruded disc herniation and on the degenerative disc disease because the inflammatory response is very different between the various cases. Extruded disc herniation occurs when the nucleus squeezes through a weakness or tear in the annulus. Host immune system considers the nucleus material to be a foreign invader, which triggers an immune response and inflammation. We think ozone therapy modulates this immune response, activating macrophages, which produce phagocytosis of extruded nucleus pulposus. Ozone would also facilitate the passage from the M1 to M2 phase of macrophages, going from an inflammatory phase to a reparative phase. Further studies are needed to verify the switch of macrophages.

Modulation of the In Vivo Inflammatory Response by Pro- Versus Anti-Inflammatory Intervertebral Disc Treatments.

Inflammation is central in intervertebral disc (IVD) degeneration/regeneration mechanisms, and its balance is crucial to maintain tissue homeostasis. This work investigates the modulation of local and systemic inflammatory response associated with IVD degeneration/herniation by administration of PRO- versus ANTI-inflammatory treatments. Chitosan/poly-γ-glutamic acid nanocomplexes, known as pro-inflammatory (PRO), and soluble diclofenac, a non-steroidal anti-inflammatory drug (ANTI), were intradiscally administered in a rat IVD injury model, 24 h after lesion. Two weeks after administration, a reduction of disc height accompanied by hernia formation was observed. In the PRO-inflammatory treated group, IL-1ß, IL-6 and COX-2 IVD gene expression were upregulated, and loss of nucleus pulposus (NP) structure and composition was observed. Systemically, lower T-cell frequency was observed in the lymph nodes (LN) and spleen (SP) of the PRO group, together with an increase in CD4+ T cells subset in the blood (BL) and LN. In contrast, the ANTI-group had higher proteoglycans/collagen ratio and collagen type 2 content in the NP, while an increase in the frequency of myeloid cells, M1 macrophages and activated macrophages (MHCII+) was observed at the systemic level. Overall, this study illustrates the dynamics of local and systemic inflammatory and immune cell responses associated with intradiscal therapies, which will contribute to designing more successful immunomodulatory treatments for IVD degeneration.

Characterization of neuroinflammation and periphery-to-CNS inflammatory cross-talk in patients with disc herniation and degenerative disc disease.

The aim of the study was to identify inflammatory cytokines/chemokines associated with neuroinflammation and periphery-to-CNS inflammatory cross-talk in degenerative disc disease (DDD) and lumbar disc herniation (LDH), common causes of low back pain (LBP). A secondary aim was to investigate the associations between cytokines and symptom severity. METHODS: In total, 40 DDD and 40 LDH patients were recruited from a surgical waiting list, as well as 39 healthy controls (HC) and 40 cerebrospinal fluid (CSF) controls. The subjects completed questionnaires and pressure algometry was performed at the lumbar spine and forearm. The CSF, serum and disc tissues were collected during surgery. Inflammatory mediators TNF, INFg, IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13 and MCP1 were analysed by immunoassay (Meso Scale Discovery) and quantitative real-time polymerase chain reaction (qPCR) was used for analysis of IL-6, IL-8, MCP1 and TSPO expression in intervertebral discs (IVDs). RESULTS: In the LDH group, we found elevated IL-8 concentrations in CSF indicating neuroinflammation, while IL-8 and MCP1 concentrations in serum were lower compared to HC. The IVD expression of IL-6, IL-8 and TSPO was lower in LDH patients compared to DDD. LDH patients had a positive correlation between IL-8 concentrations in CSF and serum and IL-8 in CSF was associated with higher pain intensity and increased spinal pressure pain sensitivity. The MCP1 concentration in serum was associated with higher global pain ratings and increased spinal pressure pain sensitivity, while IL-6 serum concentration correlated with the intensity of the neuropathic pain component (leg pain) in LDH patients. IVD expression of TSPO in LDH patients was associated with increased intensity of back pain. No differences were found in cytokine CSF concentrations between DDD patients and CSF controls, but DDD patients had lower IL-8 and MCP1 serum concentrations than HC. In female DDD patients, IL-8 and MCP1 concentrations in serum were associated with increased intensity of back pain. CONCLUSION: Our results suggest that neuroinflammation mediated by elevated IL-8 concentrations in CSF and IL-8 mediated periphery-to-CNS inflammatory cross-talk contributes to pain in LDH patients and suggest a link between TSPO expression in discs and low back pain.

The Biochemical and Pharmacological Properties of Ozone: The Smell of Protection in Acute and Chronic Diseases.

Ozone therapy has been widely used in everyday clinical practice over the last few years, leading to significant clinical results in the treatment of herniated discs and pain management. Nevertheless, further studies have demonstrated its potential efficacy and safety under other clinical and experimental conditions. However, some of these studies showed controversial results regarding the safety and efficacy of ozone therapy, thus mining its potential use in an everyday clinical practice. To this regard, it should be considered that extensive literature review reported the use of ozone in a significant different dose range and with different delivery systems. The aim of the present review is to describe the various pharmacological effects of ozone in different organs and clinical conditions and to provide possible biochemical and molecular insights for ozone biological properties, thus providing a possible explanation for various controversial clinical outcomes described in the scientific literature.

Local up-regulation of interferon-γ (IFN-γ) following disc herniation is involved in the inflammatory response underlying acute lumbar radicular pain.

Lumbar radicular pain after disc herniation may be associated with release of pro-inflammatory cytokines from nucleus pulposus (NP) tissue. In the present study we examined the role of interferon-γ (IFN-γ) and cluster of differentiation 68 (CD68) in the acute phase of this process. First, in an animal model mimicking the clinical situation after disc herniation, the role of IFN-γ close to the dorsal nerve roots was studied. Next, in patients with lumbar radicular pain due to disc herniation, we examined how two single nucleotide polymorphisms (SNPs; rs2069705 and rs2069718) are important for the IFN-γ expression influenced the pain behavior. The animal data demonstrated a significant increase in the nociceptive activity at the spinal level after local application of NP and IFN-γ onto the dorsal nerve roots. A positive correlation between IFN-γ and CD68 in the NP tissue was also demonstrated. In the patients, a significant increase in Oswestry Disability Index (ODI) score was observed in carriers of the IFN-γ SNPs; rs2069705 A and rs2069718 G alleles. The present data suggest that IFN-γ close to the dorsal nerve roots may contribute to the pathogenesis, the nociceptive activity and the pain behavior following lumbar disc herniation.

Plasmacytoid dendritic cells and memory T cells infiltrate true sequestrations stronger than subligamentous sequestrations: evidence from flow cytometric analysis of disc infiltrates.

PURPOSE: Herniated nucleus pulposus has been considered to induce an adaptive immune response. Antigen recognition by antigen-presenting-cells (APCs) represents an important step within manifestation of an adaptive immune response. Macrophages have been assumed to function as APC, while importance of plasmacytoid dendritic cells for initiation of an immune response directed towards herniated nucleus pulposus has never been examined. The aim of the present study was to assess importance of plasmacytoid dendritic cells for initiation of immune response directed towards herniated discs. METHODS: Fifteen patients with true sequestrations and three patients with subligamentous sequestrations underwent surgery after their neurological examinations. Disc material was harvested, weighted and digested for 90 min. Separated single cells were counted, stained for plasmacytoid dendritic cells (CD123(+)CD4(+)), macrophages (CD14(+)CD11c(+)) and memory T cells (CD4(+)CD45RO(+)) and analysed by flow cytometry. Both patient groups were compared in cell proportions. Furthermore, patients with true sequestrations (TRUE patients) were subdivided into subgroups based on severity of muscle weakness and results in straight leg raising (SLR) test. Subgroups were compared in cell proportions. RESULTS: Plasmacytoid dendritic cells and memory T cells infiltrated true sequestrations stronger than the subligamentous sequestration and plasmacytoid dendritic cells predominated over macrophages in true sequestrations. Highest proportions of plasmacytoid dendritic cells were detected in infiltrates of patients having true sequestrations, severe muscle weakness and negative result in SLR test. CONCLUSIONS: The findings of the present study indicate that plasmacytoid dendritic cells are involved in initiation of an immune response directed towards herniated nucleus pulposus, while macrophages may reinforce the manifested immune response and mediate disc resorption.

Experimental Disc Herniation in the Rat Causes Downregulation of Serotonin Receptor 2c in a TNF-dependent Manner.

BACKGROUND: During recent decades, the knowledge of the pathophysiology of disc herniation and sciatica has drastically improved. What previously was considered a strict biomechanical process is now considered a more complex interaction between leaked nucleus pulposus and the tissue in the spinal canal. An inflammatory reaction, with tumor necrosis factor (TNF) playing an essential role, has been demonstrated. However, the exact mechanisms of the pathophysiology of disc herniation remain unknown. QUESTIONS/PURPOSES: In this study we use an animal model to investigate (1) if and/or how experimental disc herniation affects gene expression in the early phase (24 hours postsurgery) in the dorsal root ganglion; and (2) if TNF inhibition can reduce any observed changes. METHODS: A rat model of disc herniation was used. Twenty rats were evenly divided into four groups: naïve, sham, disc herniation, and disc herniation with TNF inhibition. The dorsal root ganglion of the affected nerve root was harvested 24 hours after surgery and analyzed with a TaqMan Low Density Array(®) quantitative polymerase chain reaction assay. Gene expression levels in sham were compared with disc herniation to assess question 1 and disc herniation to disc herniation with TNF inhibition to assess question 2. RESULTS: Experimental disc herniation caused a decrease in the expression of the serotonin receptor 2c gene (p = 0.022). TNF inhibition was found to reduce the observed decrease in expression of serotonin receptor 2c (p = 0.037). CONCLUSIONS: Our results suggest that a decrease in the expression of the serotonin receptor 2c gene may contribute to the pathophysiology of disc herniation. Further research on its involvement is warranted. CLINICAL RELEVANCE: This pilot study gives a brief insight into cellular changes that may contribute to the pathophysiology of disc herniation. This knowledge may contribute to the development of more and better treatment options for patients with disc herniation and sciatica.

Herniated intervertebral disk induces hypertrophy and ossification of ligamentum flavum.

STUDY DESIGN: In vitro experiment using degenerated human ligamentum flavum (LF) and herniated intervertebral disk (IVD). OBJECTIVES: To investigate the role and effect of degenerated and herniated IVDs on LF hypertrophy and ossification. SUMMARY OF BACKGROUND DATA: Spinal stenosis is caused, in part, by hypertrophy and ossification of the LF, which are induced by aging and degenerative process. It is well known that degenerated IVDs spontaneously produce inflammatory cytokines. Therefore, we hypothesized that degenerated IVD may affect adjacent LF through secreted inflammatory cytokines. METHODS: LF and herniated lumbar IVD tissues were obtained during surgical spinal procedures. LF fibroblasts were isolated by enzymatic digestion of LF tissue. LF cell cultures were treated with disk supernatant from herniated IVDs. Secreted cytokines from IVD tissue culture were detected by enzyme-linked immunosorbent assay. After analysis of cytotoxicity, DNA synthesis was measured. Reverse transcription-polymerase chain reaction for mRNA expressions of types I, II, III, V, and XI collagen and osteocalcin, and histochemical stains were performed. RESULTS: Supernatant from tissue culture of herniated IVD showed increased production of interleukin-1α, interleukin-6, tumor necrosis factor-α, prostaglandin E2, and nitric oxide compared with disk tissue culture from traumatic condition. There was no cytotoxicity in LF cells treated with disk supernatant from herniated IVDs. There was significant increase in DNA synthesis, upregulation in mRNA expression of types III, XI collagen and osteocalcin, whereas variable expression pattern of type I and V, and strong positive stains for Von Kossa and alkaline phosphatase in LF cultures with disk supernatant. CONCLUSIONS: Degenerated and herniated IVDs provide an important pathomechanism in hypertrophy and ossification of the LF through inflammatory cytokines.

Unraveling the neuroimmune interface in chronic pain-the association between cytokines in the cerebrospinal fluid and pain in patients with lumbar disk herniation or degenerative disk disease.

ABSTRACT: Recent evidence highlights the importance of the neuroimmune interface, including periphery-to-central nervous system (CNS) neuroimmune crosstalk, in chronic pain. Although neuroinflammatory processes have been implicated in central sensitization for a long time, their potential neuroprotective and analgesic effects remain relatively elusive. We have explored the relationships between cytokine expression and symptom severity, and candidates for periphery-to-CNS crosstalk. Patients with degenerative disk disease (DDD) (nociceptive pain) or patients with lumbar disk herniation (LDH) with radiculopathy (predominantly neuropathic pain) completed questionnaires regarding pain and functional disability, underwent quantitative sensory testing, and provided blood and cerebrospinal fluid (CSF) samples. Proximity extension assay (PEA) was used to measure the levels of 92 inflammatory proteins in the CSF and serum from a total of 160 patients and controls, and CSF/serum albumin quotients was calculated for patients with DDD and patients with LDH. We found signs of neuroimmune activation, in the absence of systemic inflammation. Regarding periphery-to-CNS neuroimmune crosstalk, there were significant associations between several cytokines and albumin quotient, despite the latter being primarily at subclinical levels. The cytokines CCL11, CD5, IL8, and MMP-10 were elevated in the CSF, had positive correlations between CSF and serum levels, and associated in a nonlinear manner with back, but not leg, pain intensity in the LDH, but not the DDD, group. In conclusion, we found evidence for neuroimmune activation in the CNS of both patient groups in the absence of systemic inflammation and signs of a communication between CSF and serum. Complex and disease-specific associations were found between cytokines in CSF and back pain intensity.

Effect of scraping therapy on interleukin-1 in serum of rats with lumbar disc herniation.

OBJECTIVE: To explore the effect of scraping therapy on the Interleukin-1 (IL-1) levels of rats with lumbar disc herniation (LDH). METHODS: Fifty male rats were devided into a blank group (A), a sham operation group (B), a model group (C), a scraping group (D), and a drug group (E). The rats in the group B were treated with sham operation, and groups C, D and E were made into the LDH model by operation. After operation, group C were treated with no interventions, D were given scraping and E were fed with azathioprine. Then the IL-1 levels of different groups were detected by enzyme-linked immuno sorbent assay method. And the transplanted coccygeal vertebra discs were observed by pathological section. RESULTS: The IL-1 levels in the groups C, D, and E were significantly higher than those in the groups A and B (all P < 0.01), which proved the operation was successful. The IL-1 levels in the groups D and E at different periods had statistical significance (F = 414.158, P < 0.01). The treatment periods and interventions have interation (F = 46.613, P < 0.01). Multiple comparison results showed that the IL-1 levels in the groups D and E was significantly lower than that in the group C (P < 0.01), while the IL-1 levels between the groups D and E had no statistical significance (P > 0.05). Moreover, pathological section indicated that immuno-inflammatory response was hardly found in coccygeal vertebra discs in the groups A and B, while local immuno-inflammatory responses of the groups D and E were much lighter than that of the group C. CONCLUSION: Scraping therapy could inhibit the immuno-inflammatory responses in the rats with LDH caused by transplantation of autologous nucleus pulposus.

Proinflammatory cytokine expression profile in degenerated and herniated human intervertebral disc tissues.

OBJECTIVE: Prior reports document macrophage and lymphocyte infiltration with proinflammatory cytokine expression in pathologic intervertebral disc (IVD) tissues. Nevertheless, the role of the Th17 lymphocyte lineage in mediating disc disease remains uninvestigated. We undertook this study to evaluate the immunophenotype of pathologic IVD specimens, including interleukin-17 (IL-17) expression, from surgically obtained IVD tissue and from nondegenerated autopsy control tissue. METHODS: Surgical IVD tissues were procured from patients with degenerative disc disease (n = 25) or herniated IVDs (n = 12); nondegenerated autopsy control tissue was also obtained (n = 8) from the anulus fibrosus and nucleus pulposus regions. Immunohistochemistry was performed for cell surface antigens (CD68 for macrophages, CD4 for lymphocytes) and various cytokines, with differences in cellularity and target immunoreactivity scores analyzed between surgical tissue groups and between autopsy control tissue regions. RESULTS: Immunoreactivity for IL-4, IL-6, IL-12, and interferon-gamma (IFNgamma) was modest in surgical IVD tissue, although expression was higher in herniated IVD samples and virtually nonexistent in control samples. The Th17 lymphocyte product IL-17 was present in >70% of surgical tissue fields, and among control samples was detected rarely in anulus fibrosus regions and modestly in nucleus pulposus regions. Macrophages were prevalent in surgical tissues, particularly herniated IVD samples, and lymphocytes were expectedly scarce. Control tissue revealed lesser infiltration by macrophages and a near absence of lymphocytes. CONCLUSION: Greater IFNgamma positivity, macrophage presence, and cellularity in herniated IVDs suggests a pattern of Th1 lymphocyte activation in this pathology. Remarkable pathologic IVD tissue expression of IL-17 is a novel finding that contrasts markedly with low levels of IL-17 in autopsy control tissue. These findings suggest involvement of Th17 lymphocytes in the pathomechanism of disc degeneration.

Revealing the Immune Infiltration Landscape and Identifying Diagnostic Biomarkers for Lumbar Disc Herniation.

Intervertebral disc (IVD) degeneration and its inflammatory microenvironment ultimately led to discogenic pain, which is thought to originate in the nucleus pulposus (NP). In this study, key genes involved in NP tissue immune infiltration in lumbar disc herniation (LDH) were identified by bioinformatic analysis. Gene expression profiles were downloaded from the Gene Expression Omnibus (GEO) database. The CIBERSORT algorithm was used to analyze the immune infiltration into NP tissue between the LDH and control groups. Hub genes were identified by the WGCNA R package in Bioconductor and single-cell sequencing data was analyzed using R packages. Gene expression levels were evaluated by quantitative real-time polymerase chain reaction. The immune infiltration profiles varied significantly between the LDH and control groups. Compared with control tissue, LDH tissue contained a higher proportion of regulatory T cells and macrophages, which are associated with the macrophage polarization process. The most significant module contained three hub genes and four subclusters of NP cells. Functional analysis of these genes was performed, the hub gene expression pattern was confirmed by PCR, and clinical features of the patients were investigated. Finally, we identified TGF-ß and MAPK signaling pathways as crucial in this process and these pathways may provide diagnostic markers for LDH. We hypothesize that the hub genes expressed in the specific NP subclusters, along with the infiltrating macrophages play important roles in the pathogenesis of IVD degeneration and ultimately, disc herniation.

Primary immune system responders to nucleus pulposus cells: evidence for immune response in disc herniation.

Although intervertebral disc herniation and associated sciatica is a common disease, its molecular pathogenesis is not well understood. Immune responses are thought to be involved. This study provides direct evidence that even non-degenerated nucleus pulposus (NP) cells elicit immune responses. An in vitro colony forming inhibition assay demonstrated the suppressive effects of autologous spleen cells on NP cells and an in vitro cytotoxicity assay showed the positive cytotoxic effects of natural killer (NK) cells and macrophages on NP cells. Non-degenerated rat NP tissues transplanted into wild type rats and immune-deficient mice demonstrated a significantly higher NP cell survival rate in immune-deficient mice. Immunohistochemical staining showed the presence of macrophages and NK cells in the transplanted NP tissues. These results suggest that even non-degenerated autologous NP cells are recognized by macrophages and NK cells, which may have an immunological function in the early phase of disc herniation. These findings contribute to understanding resorption and the inflammatory reaction to disc herniation.

Investigation of resident and recruited macrophages following disc injury in mice.

Macrophages, particularly M1 macrophages, produce proinflammatory cytokines and contribute to the degenerative process in injured intervertebral discs (IVDs). We previously showed that macrophages in both intact and injured IVDs increased following IVD injury. Resident macrophages and macrophages recruited from the peripheral blood have distinct roles in tissue. However, it remains to be determined whether increased macrophages derive from resident or recruited macrophages. We investigated the origin of M1 macrophages in injured IVDs using green fluorescent protein (GFP) transgenic bone marrow chimeric mice. The M1 macrophage marker, CD86, increased in both disc-derived resident macrophages and bone marrow-derived macrophages (BMMs) after lipopolysaccharide/interferon γ stimulation in vitro. Following IVD injury, the proportion of cells positive for the CD86 ligand, the F4/80 antigen, and the surface glycoprotein CD11b (CD86+ CD11b+ F4/80+) significantly increased in GFP+ populations at days 3, 7, and 14. In contrast, CD86+ CD11b+ F4/80+ cells in GFP- populations significantly increased on day 3, and thereafter decreased on days 7 and 14. The proportion of CD86+ CD11b+ F4/80+ cells in the GFP+ populations was significantly higher than that in the GFP- populations at days 1, 3, 7, and 14. Monocyte chemoattractant protein-1 expression in disc-derived macrophages, but not in BMMs, increased following interleukin-1ß stimulation. Our results suggest M1 macrophages following IVD injury originate from recruited macrophages. Resident macrophages may behave differently in IVD injury. The role of resident macrophages needs to be clarified. Further investigation is needed.

[Serum biomarkers in acute low back pain and sciatica]. / Szérumbiomarkerek akut lumbalis-lumbosacralis fájdalomban.

Inflammation contributes to the pathogenesis of low back pain and sciatica. Growing evidence suggests that elevated levels of some inflammatory biomarkers are associated with these conditions. Much of the research evaluating the association between pro- and anti-inflammatory cytokines, chemokines, other regulatory molecules, and low back pain and sciatica, focused on patients with chronic low back pain, while fewer studies addressed the issue of detectable biomarkers in the acute phase. Previous studies suggest that pro-inflammatory cytokines such as TNF-α, IL-6, and IL-8 and anti-inflammatory IL-4 and IL-10 play an important role in the inflammatory response following intervertebral disc herniation. According to the approach of personalized medicine it is important to identify subsets of patients within the acute patient group regarding etiology, prognosis and treatment. In addition, if we can identify subgroups based on levels of pro-inflammatory biomarkers, where inflammation may be the leading cause of pain, we assume that this subgroup would likely be effectively treated with anti-inflammatory medication. The efficacy of TNF-α inhibitors and IL-6 inhibitors in treating low back pain and sciatica has already been tested in clinical trials, but further studies are required. Overall, identification of circulating biomarkers of acute low back pain and sciatica may assist in refining personalized diagnosis and treatment. Further research is needed to evaluate the role of inflammation in acute low back pain and sciatica, to identify what methods are appropriate for evaluation in clinical practice, and whether there are biomarkers of prognostic value in these patients. Orv Hetil. 2020; 161(13): 483-490.

Effect of Preoperative Uric Acid Level and Neutrophil / Lymphocyte Ratio on Preoperative and Postoperative Visual Analogue Pain Scores in Patients with Lumbar Disc Herniation: A Cross-Sectional Study.

AIM: To determine the relationship between the serum urate (SU) level, neutrophil / lymphocyte ratio (NLR), and pain severity using preoperative and postoperative visual analogue scale (VAS) scores in patients with lumbar disc herniation (LDH). MATERIAL AND METHODS: This single-center, cross-sectional study included 20 consecutive patients who were operated for LDH by the same surgeon. The patients'pre- and postoperative UA levels, NLRs, and intensity severity VAS scores were investigated. Preoperative magnetic resonance imaging (MRI) findings, serum UA levels, and neutrophil and lymphocyte counts were recorded. Pain severity was recorded preoperatively and at 6 months postoperatively. Effects of the preoperative SU levels and NLRs on the pre- and postoperative VAS scores were statistically assessed. RESULTS: Statistically significant positive correlation coefficients were determined between NLR and the preoperative and postoperative VAS scores. Negative correlation coefficients were found between the SU levels and preoperative VAS scores; in contrast, positive correlation coefficients were found between the SU levels and the postoperative VAS scores. CONCLUSION: Our results demonstrate the importance of not ignoring the serum UA level and NLR in pre- and postoperative pain in patients with LDH. Nevertheless, further extensive studies are warranted.

The inflammatory response in the regression of lumbar disc herniation.

Lumbar disc herniation (LDH) is highly associated with inflammation in the context of low back pain. Currently, inflammation is associated with adverse symptoms related to the stimulation of nerve fibers that may lead to pain. However, inflammation has also been indicated as the main factor responsible for LDH regression. This apparent controversy places inflammation as a good prognostic indicator of spontaneous regression of LDH. This review addresses the molecular and cellular mechanisms involved in LDH regression, including matrix remodeling and neovascularization, in the scope of the clinical decision on conservative versus surgical intervention. Based on the evidence, a special focus on the inflammatory response in the LDH context is given, particularly in the monocyte/macrophage role. The phenomenon of spontaneous regression of LDH, extensively reported in the literature, is therefore analyzed here under the perspective of the modulatory role of inflammation.

Chemical and mechanical nerve root insults induce differential behavioral sensitivity and glial activation that are enhanced in combination.

Both chemical irritation and mechanical compression affect radicular pain from disc herniation. However, relative effects of these insults on pain symptoms are unclear. This study investigated chemical and mechanical contributions for painful cervical nerve root injury. Accordingly, the C7 nerve root separately underwent chromic gut exposure, 10gf compression, or their combination. Mechanical allodynia was assessed, and glial reactivity in the C7 spinal cord tissue was assayed at days 1 and 7 by immunohistochemistry using GFAP and OX-42 as markers of astrocytes and microglia, respectively. Both chromic gut irritation and 10gf compression produced ipsilateral increases in allodynia over sham (p<0.048); combining the two insults significantly (p<0.027) increased ipsilateral allodynia compared to either insult alone. Behavioral hypersensitivity was also produced in the contralateral forepaw for all injuries, but only the combined insult was significantly increased over sham (p<0.031). Astrocytic activation was significantly increased over normal (p<0.001) in the ipsilateral dorsal horn at 1 day after either compression or the combined injury. By day 7, GFAP-reactivity was further increased for the combined injury compared to day 1 (p<0.001). In contrast, spinal OX-42 staining was generally variable, with only mild activation at day 1. By day 7 after the combined injury, there were significant (p<0.003) bilateral increases in OX-42 staining over normal. Spinal astrocytic and microglial reactivity follow different patterns after chemical root irritation, compression, and a combined insult. The combination of transient compression and chemical irritation produces sustained bilateral hypersensitivity, sustained ipsilateral spinal astrocytic activation and late onset bilateral spinal microglial activation.

The association of the activation-inducible tumor necrosis factor receptor and ligand with lumbar disc herniation.

PURPOSE: Herniated nucleus pulposus fragments are recognized by the immune system as a foreign-body, which results in an autoimmune reaction. Human activation-inducible tumor necrosis factor receptor (AITR) and its ligand, AITRL, are important costimulatory molecules in the pathogenesis of autoimmune diseases. Despite the importance of these costimulatory molecules in autoimmune disease, their role in the autoimmune reaction to herniated disc fragments has yet to be explored. The purpose of the present study is to investigate whether the overexpression of AITR and AITRL might be associated with lumbar disc herniation. MATERIALS AND METHODS: The study population consisted of 20 symptomatic lumbar disc herniation patients. Ten macroscopically normal control discs were obtained from patients with spinal fractures managed with anterior procedures that involved a discectomy. Peripheral blood samples from both the study patients and controls were collected. The expression levels of AITR and AITRL were investigated by flow cytometric analysis, confocal laser scanning microscopy, immunohistochemistry and by reverse transcriptase-polymerase chain reaction (RT-PCR). The soluble AITR and AITRL serum levels were measured by an enzyme-linked immunosorbent assay. RESULTS: Flow cytometric analysis revealed significantly higher levels of both AITR and AITRL in the lumbar disc herniation patients than in the controls. The AITRL expression levels were also increased in patients with lumbar disc herniation, shown by using confocal laser scanning microscopy, immunohisto-chemistry, and RT-PCR. Finally, soluble AITR and AITRL were elevated in the patients with lumbar disc herniations. CONCLUSION: The AITR and AITRL are increased in both the herniated disc tissue and the peripheral blood of patients with lumbar disc herniation.