Microarray analysis reveals an inflammatory transcriptomic signature in peripheral blood for sciatica.

BACKGROUND: Although the pathology of sciatica has been studied extensively, the transcriptional changes in the peripheral blood caused by sciatica have not been characterized. This study aimed to characterize the peripheral blood transcriptomic signature for sciatica. METHODS: We used a microarray to identify differentially expressed genes in the peripheral blood of patients with sciatica compared with that of healthy controls, performed a functional analysis to reveal the peripheral blood transcriptomic signature for sciatica, and conducted a network analysis to identify key genes that contribute to the observed transcriptional changes. The expression levels of these key genes were assessed by qRT-PCR. RESULTS: We found that 153 genes were differentially expressed in the peripheral blood of patients with sciatica compared with that of healthy controls, and 131 and 22 of these were upregulated and downregulated, respectively. A functional analysis revealed that these differentially expressed genes (DEGs) were strongly enriched for the inflammatory response or immunity. The network analysis revealed that a group of genes, most of which are related to the inflammatory response, played a key role in the dysregulation of these DEGs. These key genes are Toll-like receptor 4, matrix metallopeptidase 9, myeloperoxidase, cathelicidin antimicrobial peptide, resistin and Toll-like receptor 5, and a qRT-PCR analysis validated the higher transcript levels of these key genes in the peripheral blood of patients with sciatica than in that of healthy controls. CONCLUSION: We revealed inflammatory characteristics that serve as a peripheral blood transcriptomic signature for sciatica and identified genes that are essential for mRNA dysregulation in the peripheral blood of patients with sciatica.

Gut Microbiota Influences Neuropathic Pain Through Modulating Proinflammatory and Anti-inflammatory T Cells.

BACKGROUND: Gut microbiota, a consortium of diverse microorganisms residing in the gastrointestinal tract, has emerged as a key player in neuroinflammatory responses, supporting the functional relevance of the "gut-brain axis." Chronic-constriction injury of the sciatic nerve (CCI) is a commonly used animal model of neuropathic pain with a major input from T cell-mediated immune responses. In this article, we sought to examine whether gut microbiota influences CCI neuropathic pain, and, if so, whether T-cell immune responses are implicated. METHODS: We used a mixture of wide-spectrum oral antibiotics to perturbate gut microbiota in mice and then performed CCI in these animals. Nociceptive behaviors, including mechanical allodynia and thermal hyperalgesia, were examined before and after CCI. Additionally, we characterized the spinal cord infiltrating T cells by examining interferon (IFN)-γ, interleukin (IL)-17, and Foxp3. Using a Foxp3-GFP-DTR "knock-in" mouse model that allows punctual depletion of regulatory T cells, we interrogated the role of these cells in mediating the effects of gut microbiota in the context of CCI neuropathic pain. RESULTS: We found that oral antibiotics induced gut microbiota changes and attenuated the development of CCI neuropathic pain, as demonstrated by dampened mechanical allodynia and thermal hyperalgesia. Percentages of IFN-γ-producing Th1 cells and Foxp3+ regulatory T cells were significantly different between animals that received oral antibiotics (Th1 mean = 1.0, 95% confidence interval [CI], 0.9-1.2; Foxp3 mean = 8.1, 95% CI, 6.8-9.3) and those that received regular water (Th1 mean = 8.4, 95% CI, 7.8-9.0, P < .01 oral antibiotics versus water, Cohen's d = 18.8; Foxp 3 mean = 2.8, 95% CI, 2.2-3.3, P < .01 oral antibiotics versus water, Cohen's d = 6.2). These T cells characterized a skewing from a proinflammatory to an anti-inflammatory immune profile induced by gut microbiota changes. Moreover, we depleted Foxp3+ regulatory T cells and found that their depletion reversed the protection of neuropathic pain mediated by gut microbiota changes, along with a dramatic increase of IFN-γ-producing Th1 cell infiltration in the spinal cord (before depletion mean = 2.8%, 95% CI, 2.2-3.5; after depletion mean = 9.1%, 95% CI, 7.2-11.0, p < .01 before versus after, Cohen's d = 5.0). CONCLUSIONS: Gut microbiota plays a critical role in CCI neuropathic pain. This role is mediated, in part, through modulating proinflammatory and anti-inflammatory T cells.

Sex differences in neuro(auto)immunity and chronic sciatic nerve pain.

Chronic pain occurs with greater frequency in women, with a parallel sexually dimorphic trend reported in sufferers of many autoimmune diseases. There is a need to continue examining neuro-immune-endocrine crosstalk in the context of sexual dimorphisms in chronic pain. Several phenomena in particular need to be further explored. In patients, autoantibodies to neural antigens have been associated with sensory pathway hyper-excitability, and the role of self-antigens released by damaged nerves remains to be defined. In addition, specific immune cells release pro-nociceptive cytokines that directly influence neural firing, while T lymphocytes activated by specific antigens secrete factors that either support nerve repair or exacerbate the damage. Modulating specific immune cell populations could therefore be a means to promote nerve recovery, with sex-specific outcomes. Understanding biological sex differences that maintain, or fail to maintain, neuroimmune homeostasis may inform the selection of sex-specific treatment regimens, improving chronic pain management by rebalancing neuroimmune feedback. Given the significance of interactions between nerves and immune cells in the generation and maintenance of neuropathic pain, this review focuses on sex differences and possible links with persistent autoimmune activity using sciatica as an example.

[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.

Lessons learnt from a discontinued randomised controlled trial: adalimumab injection compared with placebo for patients receiving physiotherapy treatment for sciatica (Subcutaneous Injection of Adalimumab Trial compared with Control: SCIATiC).

BACKGROUND: Adalimumab, a biological treatment targeting tumour necrosis factor α, might be useful in sciatica. This paper describes the challenges faced when developing a new treatment pathway for a randomised controlled trial of adalimumab for people with sciatica, as well as the reasons why the trial discussed was stopped early. METHODS: A pragmatic, parallel group, randomised controlled trial with blinded (masked) participants, clinicians, outcome assessment and statistical analysis was conducted in six UK sites. Participants were identified and recruited from general practices, musculoskeletal services and outpatient physiotherapy clinics. They were adults with persistent symptoms of sciatica of 1 to 6 months' duration with moderate to high level of disability. Eligibility was assessed by research physiotherapists according to clinical criteria, and participants were randomised to receive two doses of adalimumab (80 mg then 40 mg 2 weeks later) or saline placebo subcutaneous injections in the posterior lateral thigh. Both groups were referred for a course of physiotherapy. Outcomes were measured at baseline, 6-week, 6-month and 12-month follow-up. The main outcome measure was disability measured using the Oswestry Disability Index. The planned sample size was 332, with the first 50 in an internal pilot phase. RESULTS: The internal pilot phase was discontinued after 10 months from opening owing to low recruitment (two of the six sites active, eight participants recruited). There were several challenges: contractual delays; one site did not complete contract negotiations, and two sites signed contracts shortly before trial closure; site withdrawal owing to patient safety concerns; difficulties obtaining excess treatment costs; and in the two sites that did recruit, recruitment was slower than planned because of operational issues and low uptake by potential participants. CONCLUSIONS: Improved patient care requires robust clinical research within contexts in which treatments can realistically be provided. Step changes in treatment, such as the introduction of biologic treatments for severe sciatica, raise complex issues that can delay trial initiation and retard recruitment. Additional preparatory work might be required before testing novel treatments. A randomised controlled trial of tumour necrosis factor-α blockade is still needed to determine its cost-effectiveness in severe sciatica. TRIAL REGISTRATION: Current Controlled Trials, ISRCTN14569274 . Registered on 15 December 2014.

In vivo and systems biology studies implicate IL-18 as a central mediator in chronic pain.

Inflammation is associated with peripheral neuropathy, however the interplay among cytokines, chemokines, and neurons is still unclear. We hypothesized that this neuroinflammatory interaction can be defined by computational modeling based on the dynamics of protein expression in the sciatic nerve of rats subjected to chronic constriction injury. Using Dynamic Bayesian Network inference, we identified interleukin (IL)-18 as a central node associated with neuropathic pain in this animal model. Immunofluorescence supported a role for inflammasome activation and induction of IL-18 at the site of injury. Combined in vivo and in silico approaches may thus highlight novel targets in peripheral neuropathy.

Autoimmunity in intervertebral disc herniation: from bench to bedside.

INTRODUCTION: The cause of low back pain and the pathophysiology of lumbar pain and sciatica have recently been reconsidered basing on current knowledge on cellular and molecular mediators of inflammation. Several cytokines have been considered as potential therapeutic targets to contrast sciatica in patients with disc herniation, and supportive studies suggest a leading role of TNF-α in this contest: therefore, clinical trials have tested TNF-α inhibitors in the clinical setting of the patient with radicular pain secondary to an herniated disc. AREAS COVERED: The current review deals with the autoimmune theory of disc herniation and its role in determining radiculopathy and neuropathic pain. It also reports the recent evidences that led to the introduction of anti-TNF-α drugs into the clinical setting as a biological therapy for radiculopathy and disc herniation. EXPERT OPINION: Targeting the TNF-α pathway has demonstrated controversial effects in the tested study population and available results only report a short-term follow-up. More confirmatory studies in terms of long-term clinical results, complications, more effective route of administration and cost-effective analysis are required to establish the real role of this biological therapy in the treatment of patients with disc herniation and neuropathy.

Influence of cytokine inhibitors on concentration and activity of MMP-1 and MMP-3 in disc herniation.

INTRODUCTION: Spontaneous resorption of disc herniation (DH) after sciatica is well documented. The matrix metalloproteinases (MMP)-1 and MMP-3 are enzymes potentially involved in this process. Glucocorticoid injections are commonly used for treatment, and other anti-inflammatory molecules like tumor necrosis factor (TNF) inhibitors are under clinical investigation. However, little is known about the effect of these molecules on DH resorption. METHODS: DH tissue was harvested from patients undergoing surgery for sciatica. Samples were thoroughly washed. Diced explants were cultured ex-vivo in 1) 0.5 ml Dulbecco's modified Eagle's medium (DMEM) 10% fetal calf serum (FCS), (controls), 2) recombinant interleukin 1 receptor antagonist (IL-1Ra), (100 ng/ml), 3) dexamethasone (10E-5 M), or 4) TNF inhibitor monoclonal antibody (10 microg/ml). Supernatants were harvested at 48 hours and frozen. Immunocapture activity assays determined total MMP activity, active MMP levels and pro-MMP levels. RESULTS: Fourteen DH tissue samples were analysed. Levels of all forms of MMP-3 were higher than the respective levels of MMP-1(P < 0.01). In particular, the median (interquartile range [IQR]) total MMP-3 level was 0.97 (0.47 - 2.19) ng/mg of tissue compared to 0.024 (0.01 - 0.07) ng/mg of total MMP-1 level (P < 0.01). Incubation with IL-1Ra, dexamethasone, or TNF inhibitors significantly decreased levels of all forms of MMP-3 (P < 0.05). Dexamethasone significantly decreased the ratio of active MMP-3 to total MMP-3 activity. A significant inhibitory effect of dexamethasone was observed only on active MMP-1, while IL-1 and TNF inhibitor had no significant effect on any form. CONCLUSIONS: MMP-3 appears to play a greater role than MMP-1 in DH resorption. Dexamethasone, IL-1-Ra and TNF inhibitor decreased active MMP-3, indicating that the clinical use of these drugs may affect the resorption of DH under certain conditions.

Autologous nucleus pulposus primes T cells to develop into interleukin-4-producing effector cells: an experimental study on the autoimmune properties of nucleus pulposus.

An autoimmune response to herniated nucleus pulposus has been proposed to constitute a pathophysiologic mechanism for inducing sciatica based on the fact that nucleus pulposus under normal conditions is excluded from the development of immunological tolerance. The manifestation of an autoimmune response comprises different steps starting with antigen capture, continuing with activation of T helper (T(H)) cells and ending with production of autoantibodies. Activated T(H) cells differentiate into either T(H)1 cells, predominately producing proinflammatory cytokines such as interferon gamma (IFNgamma) or a T(H)2 subset mainly producing anti-inflammatory cytokines such as interleukin-4 (IL-4). The aim of the present study was to examine if exposure of autologous nucleus pulposus (NP) to the immune system for 3 weeks is potent enough to prime T(H) cells to differentiate into T(H)2 cells. The study was performed in a pig model allowing the exposure of NP to the immune system. To assess the polarization of T(H) cells the intracellular production of IFNgamma and IL-4 was measured in T cells by using flow cytometry. The revealed predominant production of IL-4 together with low production of IFNgamma in T cells after NP exposure to the immune system indicates that nucleus pulposus may prime T(H) cells to develop into IL-4-producing T(H)2 cells after being exposed to the immune system, for example, in association with disc herniation.

Systemic glucocorticoid therapy reduces pain and the number of endoneurial tumor necrosis factor-alpha (TNFalpha)-positive mast cells in rats with a painful peripheral neuropathy.

Clinical and experimental evidence suggests that glucocorticoids may be effective in the treatment of neuropathic pain, but their mechanism of action is unknown. We gave triamcinolone (3 mg/kg) to rats with an experimental post-traumatic painful peripheral neuropathy, chronic constriction injury (CCI), five days after nerve injury, when the abnormal pain syndrome is known to be present; and pain sensitivity was measured on postoperative days 7 - 14, a period during which symptoms are known to be at approximately peak severity. Additional CCI rats were treated similarly; and then they were sacrificed five days after the injection for an immunocytochemical analysis of endoneurial tumor necrosis factor-alpha (TNFalpha), macrophages, and mast cells in the sciatic nerve proximal to the site of injury. Vehicle-injected CCI rats demonstrated the expected neuropathic pain symptoms. Triamcinolone-treated CCI rats had a statistically significant reduction in the magnitude of heat-hyperalgesia and mechano-allodynia, but there was no effect on cold-allodynia or mechano-hyperalgesia. On the nerve-injured side of vehicle-injected rats, TNFalpha was present in Schwann cells and mast cells. On the nerve-injured side of triamcinolone-treated rats, there was a significant (71.5%) reduction in the number of TNFalpha-positive mast cells. Our results suggest that glucocorticoid therapy for neuropathic pain may work via the reduced expression of TNFalpha in endoneurial mast cells.

Is the interleukin-6 haplotype a prognostic factor for sciatica?

AIMS: We have shown in a cross-sectional setting that an IL6 haplotype (GGGA) is associated with intervertebral disc disease (IDD) characterized by sciatica. The aim of this study was to evaluate the prognostic role of the GGGA haplotype in IDD. METHODS: DNA from 153 sciatica patients who participated in a randomized controlled trial of periradicular infiltration was analysed for IL6 variations rs1800797 (-596A>G), rs1800796 (-572G>C), rs1800795 (-174G>C), and rs13306435 (+15T>A). The patients recorded back and leg pain intensity and duration, disability by Oswestry Index and back-related sickness absence over a three-year follow-up. Repeated measures and univariate analysis of variance with adjustment for age, gender and physical work load were used in statistical analyses for the last two-years of the follow-up. RESULTS: The prevalence of the GGGA haplotype was 9% (14/153). Subjects with the GGGA haplotype did not differ from those without the haplotype with respect to pain intensity, or disability score, but days with back and leg pain and days on sick leave were significantly higher among subjects with the IL6 haplotype after adjustment for occupation (p=0.006, 0.001 and 0.002, respectively). An interaction between the IL6 haplotype and physical work load was significant for the duration of back and leg pain and sick leave (p=0.038, 0.011 and 0.006, respectively). CONCLUSIONS: This is the first observation of any prognostic genotype among sciatica patients. The IL6 haplotype GGGA predicted the number of days with back or leg pain and also sickness absence. Subjects with the IL6 haplotype may be more vulnerable when doing physically demanding jobs.

Role of the cysteine protease cathepsin S in neuropathic hyperalgesia.

Using a gene expression analysis approach we found that the mRNA encoding the lysosomal cysteine protease cathepsin S (CatS) was up-regulated in rat dorsal root ganglia (DRG) following peripheral nerve injury. CatS protein was expressed in infiltrating macrophages in DRG and near the site of injury. At both sites CatS expression progressively increased from day 3 to day 14 after injury. In naïve rats, intraplantar injection of activated rat recombinant (rr) CatS (0.3, 1 microg/rat) induced a mechanical hyperalgesia that developed within half-an-hour, diminished by 3h and was absent after 24h. Activated rrCathepsin B (CatB) and non-activated rrCatS injected intraplantarly at the same or higher doses than activated rrCatS had no effect on rat nociceptive thresholds. In nerve-injured rats, mechanical hyperalgesia, but not allodynia, was significantly reversed for up to 3h by systemic administration of a non-brain penetrant, irreversible CatS inhibitor (LHVS, 3-30 mg/kg s.c.). Depletion of peripheral macrophages by intravenous injection of liposome encapsulate clodronate (1ml, 5 mg/ml) partially reduced established mechanical hyperalgesia but not allodynia, and abolished the anti-hyperalgesic effect of LHVS. Our results demonstrate a pro-nociceptive effect of CatS and indicate that endogenous CatS released by peripheral macrophages contributes to the maintenance of neuropathic hyperalgesia following nerve injury.

Prostanoid receptor EP1 and Cox-2 in injured human nerves and a rat model of nerve injury: a time-course study.

BACKGROUND: Recent studies show that inflammatory processes may contribute to neuropathic pain. Cyclooxygenase-2 (Cox-2) is an inducible enzyme responsible for production of prostanoids, which may sensitise sensory neurones via the EP1 receptor. We have recently reported that while macrophages infiltrate injured nerves within days of injury, they express increased Cox-2-immunoreactivity (Cox-2-IR) from 2 to 3 weeks after injury. We have now investigated the time course of EP1 and Cox-2 changes in injured human nerves and dorsal root ganglia (DRG), and the chronic constriction nerve injury (CCI) model in the rat. METHODS: Tissue sections were immunostained with specific antibodies to EP1, Cox-2, CD68 (human macrophage marker) or OX42 (rat microglial marker), and neurofilaments (NF), prior to image analysis, from the following: human brachial plexus nerves (21 to 196 days post-injury), painful neuromas (9 days to 12 years post-injury), avulsion injured DRG, control nerves and DRG, and rat CCI model tissues. EP1 and NF-immunoreactive nerve fibres were quantified by image analysis. RESULTS: EP1:NF ratio was significantly increased in human brachial plexus nerve fibres, both proximal and distal to injury, in comparison with uninjured nerves. Sensory neurones in injured human DRG showed a significant acute increase of EP1-IR intensity. While there was a rapid increase in EP1-fibres and CD-68 positive macrophages, Cox-2 increase was apparent later, but was persistent in human painful neuromas for years. A similar time-course of changes was found in the rat CCI model with the above markers, both in the injured nerves and ipsilateral dorsal spinal cord. CONCLUSION: Different stages of infiltration and activation of macrophages may be observed in the peripheral and central nervous system following peripheral nerve injury. EP1 receptor level increase in sensory neurones, and macrophage infiltration, appears to precede increased Cox-2 expression by macrophages. However, other methods for detecting Cox-2 levels and activity are required. EP1 antagonists may show therapeutic effects in acute and chronic neuropathic pain, in addition to inflammatory pain.

Hepatitis C virus infection in psoriatic arthritis.

OBJECTIVE: To evaluate the prevalence of hepatitis C virus (HCV) infection in patients with psoriatic arthritis (PsA), compared with patients affected by non HCV-related rheumatic degenerative disorders. METHODS: One-hundred consecutive subjects with PsA, and a statistically comparable group of 100 consecutive patients with peripheral osteoarthritis (OA) or sciatica due to L4-L5 or L5-S1 herniated disc were tested for HCV infection with a third-generation microparticle enzyme immunoassay (MEIA). Positive cases were submitted to a third-generation recombinant immunoblot assay (RIBA) confirmatory test. Comparison between the HCV prevalence obtained in the 2 enrolled groups was performed using Fisher's exact test. RESULTS: Anti-HCV antibodies were found with the MEIA method, in 1 patient with PsA, and in 4 patients with OA or sciatica. The RIBA method confirmed MEIA results in all positive patients. The difference in HCV prevalence detected in the PsA group and in the control group was not statistically significant (P = 0.68). Furthermore, HCV prevalence in PsA patients was lower than the ones reported in different geographic areas of Italy. CONCLUSION: Our present report does not confirm previous data that indicated an increased prevalence of HCV in PsA patients, and as a consequence, does not sustain a possible trigger role of HCV in cases of PsA. The absence of clinical or instrumental resources that consent a definite differential diagnosis between PsA and HCV-related arthritis was outlined and analyzed.

Neural-immune interactions: implications for pain management in patients with low-back pain and sciatica.

Bidirectional communication between the immune system and the brain and the implications of this communication are emerging concepts in pain research. Although representing a small portion of the disc degeneration syndromes, lumbar herniated discs can cause significant symptoms that may persist even after surgical interventions. Evolving evidence demonstrates that proinflammatory cytokines are a key mediator in the process of disc degeneration as well as in the pain experienced by those afflicted with lumbar herniated discs. Activated immune cells release proinflammatory cytokines, which signal the brain through humoral and neural routes. The brain responds by altering neural activity and promoting further production of proinflammatory cytokines within the brain and spinal cord. Increased local cytokine production by disc tissue irritates spinal nerve roots, resulting in pain and functional changes in neural activity. This review of the current literature explores the importance of cytokine production within the context of lumbar disc degeneration and lumbar spine pain. Furthermore, the significance of the neural-immune interaction will be examined as it relates to pain management and to patient treatment.

Snake venom phospholipase A2s (Asp49 and Lys49) induce mechanical allodynia upon peri-sciatic administration: involvement of spinal cord glia, proinflammatory cytokines and nitric oxide.

Snakebites constitute a serious public health problem in Central and South America, where species of the lancehead pit vipers (genus Bothrops) cause the majority of accidents. Bothrops envenomations are very painful, and this effect is not neutralized by antivenom treatment. Two variants of secretory phospholipases A2 (sPLA2), corresponding to Asp49 and Lys49 PLA2s, have been isolated from Bothrops asper venom. These sPLA2s induce hyperalgesia in rats following subcutaneous injection. However, venom in natural Bothrops bites is frequently delivered intramuscularly, thereby potentially reaching peripheral nerve bundles. Thus, the present series of experiments tested whether these sPLA2s could exert pain-enhancing effects following administration around healthy sciatic nerve. Both were found to produce mechanical allodynia ipsilateral to the injection site; no thermal hyperalgesia was observed. As no prior study has examined potential spinal mechanisms underlying sPLA2 actions, a series of anatomical and pharmacological studies were performed. These demonstrated that both sPLA2s produce activation of dorsal horn astrocytes and microglia that is more prominent ipsilateral to the site of injection. As proinflammatory cytokines and nitric oxide have each been previously implicated in spinally mediated pain facilitation, the effect of pharmacological blockade of these substances was tested. The results demonstrate that mechanical allodynia induced by both sPLA2s is blocked by interleukin-1 receptor antagonist, anti-rat interleukin-6 neutralizing antibody, the anti-inflammatory cytokine interleukin-10, and a nitric oxide synthesis inhibitor (L-NAME). As a variety of immune cells also produce and release sPLA2s during inflammatory states, the data may have general implications for the understanding of inflammatory pain.

Tumor necrosis factor-alpha monoclonal antibody, infliximab, used to manage severe sciatica.

STUDY DESIGN: An open-label study was conducted. OBJECTIVE: To evaluate the efficacy and safety of infliximab, a monoclonal chimeric antibody, against tumor necrosis factor-alpha (TNFalpha) for the treatment of severe sciatica. SUMMARY OF BACKGROUND DATA: Evidence from animal studies indicates that TNFalpha plays a role in the pathophysiology of sciatica. Anti-TNFalpha therapy has not been previously evaluated in sciatic patients. METHODS: In this study, 10 patients with disc herniation-induced severe sciatica received infliximab (Remicade 3 mg/kg) intravenously over 2 hours. The outcome was assessed at 1 hour, 1 week, 2 weeks, 1 month, and 3 months after the infusion and compared to historical control subjects consisting of 62 patients who received saline in a trial of periradicular infiltration for sciatica. Leg pain was the primary outcome, with more than a 75% decrease from the baseline score constituting a painless state. Fisher's exact test and repeated measures analysis of variance were used for statistical analysis. RESULTS: At 1 hour after the infusion, leg pain had decreased by 50%. At 2 weeks, 60% of the patients in the infliximab group were painless, as compared with 16% of the control patients (P = 0.006). The difference was sustained at 3 months (90% vs 46%; P = 0.014). Infliximab was superior over the whole follow-up period in terms of leg pain (P = 0.003) and back-related disability (P = 0.004). At 1 month, every patient in the infliximab group had returned to work, whereas 38% of the control subjects still were on sick leave (P = 0.02). None of the patients treated with infliximab underwent surgery during the follow-up period. No immediate or delayed adverse drug reactions and no adverse effects related to medication were observed. CONCLUSIONS: Anti-TNFalpha therapy is a promising treatment option for sciatica. There is an urgent need for a randomized controlled trial to evaluate whether thesepromising early results can be confirmed.

Endoneurial remodeling by TNFalph- and TNFalpha-releasing proteases. A spatial and temporal co-localization study in painful neuropathy.

Peripheral nerve injury causing Wallerian degeneration results in endoneurial remodeling initiated by an increase in tumor necrosis factor-alpha (TNF), which is activated from its precursor by extracellular proteases of the matrix metalloproteinase (MMP) family. We used immunohistochemistry to analyze the distribution of TNF, TNF-releasing MMPs, including gelatinases (MMP-2 and MMP-9), and TNF-alpha converting enzyme (TACE) in painful neuropathy caused by chronic constriction injury of rat sciatic nerve. Tissue was analyzed at the injury site and in the corresponding L4 and L5 dorsal root ganglia (DRG) throughout the time-course of the neuropathy. Using confocal laser scanning microscopy, we co-localized TNF with each MMP, and observed spatial and temporal distinction in their distribution. TNF co-localized in vessel endothelium with MMP-2 and in macrophages with MMP-9 and TACE at the period of active immune cell migration. TNF co-localized with myelin degrading MMP-9 within Schwann cells during demyelination, and intraaxonally during remyelination. These studies were performed to explore the role of basal-lamina degrading gelatinases and other TNF-releasing MMPs in TNF-mediated Wallerian degeneration. The data provided in this study may be useful in designing selective therapy for painful neuropathy using synthetic hydroxamate MMP inhibitors.