Correlation between gene expression and MRI STIR signals in patients with chronic low back pain and Modic changes indicates immune involvement.

Disability and distress caused by chronic low back pain (LBP) lacking clear pathoanatomical explanations cause huge problems both for patients and society. A subgroup of patients has Modic changes (MC), identifiable by MRI as vertebral bone marrow lesions. The cause of such changes and their relationship to pain are not yet understood. We explored the pathobiology of these lesions using profiling of gene expression in blood, coupled with an edema-sensitive MRI technique known as short tau inversion recovery (STIR) imaging. STIR images and total RNA from blood were collected from 96 patients with chronic LBP and MC type I, the most inflammatory MC state. We found the expression of 37 genes significantly associated with STIR signal volume, ten genes with edema abundancy (a constructed combination of STIR signal volume, height, and intensity), and one gene with expression levels significantly associated with maximum STIR signal intensity. Gene sets related to interferon signaling, mitochondrial metabolism and defense response to virus were identified as significantly enriched among the upregulated genes in all three analyses. Our results point to inflammation and immunological defense as important players in MC biology in patients with chronic LBP.

The effect of infliximab in patients with chronic low back pain and Modic changes (the BackToBasic study): study protocol of a randomized, double blind, placebo-controlled, multicenter trial.

BACKGROUND: Low back pain is common and a significant number of patients experience chronic low back pain. Current treatment options offer small to moderate effects. Patients with vertebral bone marrow lesions visualized as Modic changes on magnetic resonance imaging may represent a subgroup within the low back pain population. There is evidence for inflammatory mediators being involved in development of Modic changes; hence, suppression of inflammation could be a treatment strategy for these patients. This study examines the effect of anti-inflammatory treatment with the TNF-α inhibitor infliximab in patients with chronic low back pain and Modic changes. METHODS/DESIGN: The BackToBasic trial is a multicenter, double blind, randomized controlled trial conducted at six hospitals in Norway, comparing intravenous infusions with infliximab with placebo. One hundred twenty-six patients aged 18-65 with chronic low back pain and type 1 Modic changes will be recruited from secondary care outpatients' clinics. The primary outcome is back pain-specific disability at day 154 (5 months). The study is designed to detect a difference in change of 10 (SD 18) in the Oswestry Disability Index at day 154/ 5 months. The study also aims to refine MRI-assessment, investigate safety and cost-effectiveness and explore the underlying biological mechanisms of Modic changes. DISCUSSION: Finding treatments that target underlying mechanisms could pose new treatment options for patients with low back pain. Suppression of inflammation could be a treatment strategy for patients with low back pain and Modic changes. This paper presents the design of the BackToBasic study, where we will assess the effect of an anti-inflammatory treatment versus placebo in patients with chronic low back pain and type 1 Modic changes. The study is registered at ClinicalTrials.gov under the identifier NCT03704363 . The EudraCT Number: 2017-004861-29.

Clinical effect modifiers of antibiotic treatment in patients with chronic low back pain and Modic changes - secondary analyses of a randomised, placebo-controlled trial (the AIM study).

BACKGROUND: Randomised trials on antibiotic treatment for patients with chronic low back pain and vertebral endplate changes visible on MRI (Modic changes) have shown mixed results. A possible explanation might be a real treatment effect in subgroups of the study populations. The purpose of the present study was to explore potential clinical effect modifiers of 3-months oral amoxicillin treatment in patients with chronic low back pain and type I or II Modic changes at the level of a previous lumbar disc herniation. METHODS: We performed analyses of effect modifiers on data from AIM, a double-blind parallel-group multicentre trial. One hundred eighty patients with chronic low back pain, previous disc herniation, Modic change type I (n = 118) or type II (n = 62) were randomised to 3-months oral treatment with 750 mg amoxicillin (n = 89) or placebo (n = 91) three times daily. The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (possible values 0-24) at 1-year follow-up in the intention-to-treat population. The predefined minimal clinically important between-group mean difference was 4 RMDQ points (not reached in the primary analysis of AIM). Predefined baseline characteristics were analysed as potential effect modifiers, four primary (type I Modic changes, previous disc surgery, positive pain provocation test, high CRP) and five exploratory (disturbed sleep, constant low back pain, short duration of low back pain, younger age, and male) using ANCOVA with interaction terms. RESULTS: None of the four primary potential effect modifiers had strong evidence of modifying the treatment effect. In patients younger than 40 years the difference in mean RMDQ score between the treatment groups was - 4.0 (95%CI, - 6.9 to - 1.2), compared to - 0.5 (95%CI, - 2.3 to 1.3) in patients 40 years or older, both in favour of amoxicillin treatment (exploratory analysis). CONCLUSIONS: We did not find evidence for convincing clinical effect modifiers of antibiotic treatment in patients with chronic low back pain and Modic changes. Our results for younger age in these explorative analyses should not affect clinical treatment decisions without confirmation in future studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT02323412 , First registered 23 December 2014.

Association of Modic change types and their short tau inversion recovery signals with clinical characteristics- a cross sectional study of chronic low back pain patients in the AIM-study.

BACKGROUND: Modic Changes (MCs, magnetic resonance imaging (MRI) signal changes in the vertebral bone marrow extending from the vertebral endplate) may represent a subgroup of nonspecific chronic low back pain that could benefit from a specific management. The primary aim was to compare clinical characteristics between patients with type 1 versus type 2 MCs. The secondary aim was to explore associations between clinical characteristics and MC related short tau inversion recovery (STIR) signals. METHODS: This cross-sectional study used baseline data prospectively collected between 2015 and 2017 on the 180 patients included in the AIM-study (Antibiotics In Modic changes), a randomized controlled trial in a Norwegian hospital out-patient setting of patients with chronic low back pain, a lumbar disc herniation within the last 2 years, low back pain intensity score ≥ 5 (on a 0-10 scale) and current type 1 or type 2 MCs at the previously herniated lumbar disc level. We used prespecified clinical characteristics including self-report measures, physiologic measures and functional measures from clinical history and examination. The diagnostic accuracy of various clinical characteristics to discriminate between patients with type 1 MCs (with or without additional type 2 MCs) and patents with type 2 MCs only (not type 1) were assessed by calculating the area under the receiver-operating curve. We assessed the correlations of clinical characteristics with details of MC related STIR signal increase. RESULTS: No clinical characteristic differed between patients with type 1 (n = 118) versus type 2 (but not type 1) (n = 62) MCs. The clinical characteristics showed no/minor differences or no/weak correlations with MC related STIR signal increase. Patients with a positive Springing test (at any lumbar level) had slightly less volume of STIR signal increase than those with a negative test (mean difference 1.3 on a 0-48 scale, 95% CI 0.3 to 2.3). CONCLUSION: Clinical characteristics were similar for patients with type 1 MCs and patients with type 2 MCs, and showed no clinically relevant correlations with MC related STIR signal increase. TRIAL REGISTRATION: ClinicalTrials.gov NCT02323412, First registered 23 December 2014.

Efficacy of antibiotic treatment in patients with chronic low back pain and Modic changes (the AIM study): double blind, randomised, placebo controlled, multicentre trial.

OBJECTIVE: To assess the efficacy of three months of antibiotic treatment compared with placebo in patients with chronic low back pain, previous disc herniation, and vertebral endplate changes (Modic changes). DESIGN: Double blind, parallel group, placebo controlled, multicentre trial. SETTING: Hospital outpatient clinics at six hospitals in Norway. PARTICIPANTS: 180 patients with chronic low back pain, previous disc herniation, and type 1 (n=118) or type 2 (n=62) Modic changes enrolled from June 2015 to September 2017. INTERVENTIONS: Patients were randomised to three months of oral treatment with either 750 mg amoxicillin or placebo three times daily. The allocation sequence was concealed by using a computer generated number on the prescription. MAIN OUTCOME MEASURES: The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (range 0-24) at one year follow-up in the intention to treat population. The minimal clinically important between group difference in mean RMDQ score was predefined as 4. RESULTS: In the primary analysis of the total cohort at one year, the difference in the mean RMDQ score between the amoxicillin group and the placebo group was -1.6 (95% confidence interval -3.1 to 0.0, P=0.04). In the secondary analysis, the difference in the mean RMDQ score between the groups was -2.3 (-4.2 to-0.4, P=0.02) for patients with type 1 Modic changes and -0.1 (-2.7 to 2.6, P=0.95) for patients with type 2 Modic changes. Fifty patients (56%) in the amoxicillin group experienced at least one drug related adverse event compared with 31 (34%) in the placebo group. CONCLUSIONS: In this study on patients with chronic low back pain and Modic changes at the level of a previous disc herniation, three months of treatment with amoxicillin did not provide a clinically important benefit compared with placebo. Secondary analyses and sensitivity analyses supported this finding. Therefore, our results do not support the use of antibiotic treatment for chronic low back pain and Modic changes. TRIAL REGISTRATION: ClinicalTrials.gov NCT02323412.

Up-regulation of circulating microRNA-17 is associated with lumbar radicular pain following disc herniation.

BACKGROUND: Previous studies suggest that regulatory microRNAs (miRs) may modulate neuro-inflammatory processes. The purpose of the present study was to examine the role of miR-17 following intervertebral disc herniation. METHODS: In a cohort of 97 patients with leg pain and disc herniation verified on MRI, we investigated the association between circulating miR-17 and leg pain intensity. A rat model was used to examine possible changes in miR-17 expression in nucleus pulposus (NP) associated with leak of NP tissue out of the herniated disc. The functional role of miR-17 was addressed by transfection of miR-17 into THP-1 cells (human monocyte cell line). RESULTS: An association between the level of miR-17 in serum and the intensity of lumbar radicular pain was shown. Up-regulation of miR-17 in the rat NP tissue when applied onto spinal nerve roots and increased release of TNF following transfection of miR-17 into THP-1 cells were also observed. Hence, our data suggest that miR-17 may be involved in the pathophysiology underlying lumbar radicular pain after disc herniation. CONCLUSIONS: We conclude that miR-17 may be associated with the intensity of lumbar radicular pain after disc herniation, possibly through a TNF-driven pro-inflammatory mechanism.

Five-year development of lumbar disc degeneration-a prospective study.

OBJECTIVE: To examine the impact of demographic, clinical, and genetic factors as well as herniated discs on 5-year development of disc degeneration in the lumbar spine, and to investigate associations between changes in lumbar degenerative findings and pain. MATERIALS AND METHODS: In 144 patients with lumbar radicular pain or low back pain, we scored disc degeneration, herniated discs, and high-intensity zones in the posterior annulus fibrosus on lumbar magnetic resonance imaging (MRI) at baseline and 5-year follow-up. Genotyping (TaqMan assay) was performed for genes encoding vitamin D receptor (VDR), collagen XIα (COL11A), matrix metalloproteinase 1/9 (MMP1/MMP9), and interleukin 1α/1RN (IL-1α/IL-1RN). Associations were analyzed using multivariate linear regression adjusted for age, sex, smoking, body mass index, and baseline scores for degenerated discs and herniated discs (when analyzing impact of baseline factors) or for pain (when analyzing associations with pain). RESULTS: Progression of disc degeneration over 5 years was significantly (p < 0.001) related to higher age and less disc degeneration at baseline, but not to sex, smoking, body mass index, herniated discs, or variants in the studied genes. No associations were identified between changes in disc degeneration or high-intensity zones and pain at 5-year follow-up. However, increased number of herniated discs over 5 years was associated with pain at rest (p = 0.019). CONCLUSIONS: Age and disc degeneration at baseline, rather than genetic factors, influenced the 5-year development of disc degeneration in patients with lumbar radicular pain or low back pain. Development of herniated discs was related to pain at rest.

C-reactive protein and cold-pressor tolerance in the general population: the Tromsø Study.

The aim of this study was to examine whether increases in severity of subclinical inflammation, measured by high-sensitivity C-reactive protein (hs-CRP), increased experimental pain sensitivity, measured by cold-pressor tolerance, and to test whether this relationship is independent of chronic pain. A large population-based study from 2007 to 2008, the sixth Tromsø Study, provided data from 12,981 participants. For the present analysis, complete data for 10,274 participants (age: median 58 years) were available. The main outcome measure was cold-pressor tolerance, tested by placing the dominant hand in circulating cold water (3°C) for a maximum of 106 seconds. Cox proportional hazard models, treating hand withdrawal during the cold-pressor test as the event and enduring the full test time as censored data, were used to investigate the relationship between hs-CRP levels (≤3 or >3 mg/L) and cold-pressure tolerance. The fully adjusted model was controlled for age, sex, education, body mass index, smoking status, alcohol consumption, emotional distress, statin usage, and self-reported presence of chronic pain. Additional analysis was performed in participants without chronic pain. Higher levels of hs-CRP were negatively related to cold-pressor tolerance (hazard ratio [HR] = 1.24, 95% confidence interval [CI], 1.12-1.37, P < 0.001), adjusted for age and sex. This relationship remained essentially unaltered after controlling for potential confounders (HR = 1.22, 95% CI, 1.09-1.36, P < 0.001), as well as for the presence of chronic pain (HR = 1.22, 95% CI, 1.09-1.36, P < 0.001). The present data show that subclinical inflammation is related to increased pain sensitivity, suggesting a potential role of inflammation in experimental pain which may be of importance for the development of clinical pain.

Role of IL1A rs1800587, IL1B rs1143627 and IL1RN rs2234677 genotype regarding development of chronic lumbar radicular pain; a prospective one-year study.

Previous studies indicate that lumbar radicular pain following disc herniation may be associated with release of several pro-inflammatory mediators, including interleukin-1 (IL1). In the present study, we examined how genetic variability in IL1A (rs1800587 C>T), IL1B (rs1143627 T>C) and IL1RN (rs2234677 G>A) influenced the clinical outcome the first year after disc herniation. Patients (n = 258) with lumbar radicular pain due to disc herniation were recruited from two hospitals in Norway. Pain and disability were measured by visual analogue scale (VAS) and Oswestry Disability Index (ODI) over a 12 month period. The result showed that patients with the IL1A T allele, in combination with the IL1RN A allele had more pain and a slower recovery than other patients (VAS p = 0.049, ODI p = 0.059 rmANOVA; VAS p = 0.003, ODI p = 0.050 one-way ANOVA at 12 months). However, regarding the IL1B/IL1RN genotype, no clear effect on recovery was observed (VAS p = 0.175, ODI p = 0.055 rmANOVA; VAS p = 0.105, ODI p = 0.214 one-way ANOVA at 12 months). The data suggest that the IL1A T/IL1RN A genotype, but not the IL1B T/IL1RN A genotype, may increase the risk of a chronic outcome in patients following disc herniation.

The association between Modic changes and pain during 1-year follow-up in patients with lumbar radicular pain.

OBJECTIVE: To examine whether Modic changes influence pain during a 1-year follow-up in patients with lumbar radicular pain. MATERIALS AND METHODS: A total of 243 patients with lumbar radicular pain due to disc herniation were recruited from two hospitals in Norway and followed up at 6 weeks, 6 months, and 12 months. On baseline lumbar magnetic resonance images, two observers independently evaluated Modic changes (types I-III; craniocaudal size 0-3). Outcomes were sensory pain (McGill Pain Questionnaire), back and leg pain (visual analogue scale, VAS). Association between Modic type and outcomes was explored with a mixed model and then by two-way analysis of variance (ANOVA) at each time point with Modic and treatment groups (surgical, n = 126; nonsurgical, n = 117) as fixed factors, adjusted for disc degeneration, age, sex, smoking, and duration of radicular pain. Modic size was also analyzed using ANOVA. RESULTS: Pain scores had decreased significantly at 1-year follow-up. Modic type was significantly related to McGill sensory scores (mixed model: p = 0.014-0.026; ANOVA: p = 0.007 at 6 weeks), but not to VAS back pain or VAS leg pain scores. At 6 weeks, the mean McGill sensory score was higher in Modic I than in Modic II-III patients (p = 0.003) and in patients without Modic changes (p = 0.018). Modic size L1-S1 was not associated with pain outcomes. CONCLUSION: Patients with lumbar radicular pain have a substantial pain reduction during 1-year follow-up, but Modic type I changes may imply a slower initial decrease in sensory pain.

Pain intensity the first year after lumbar disc herniation is associated with the A118G polymorphism in the opioid receptor mu 1 gene: evidence of a sex and genotype interaction.

Earlier studies have shown that the single nucleotide polymorphism (SNP) A118G (rs1799971) in the opioid receptor mu 1 (OPRM1) gene may affect pain sensitivity. In the present study we investigated whether the A118G SNP could predict clinical outcome regarding progression of pain intensity and disability in patients with low back pain and sciatica after lumbar disc herniation. Patients (n = 258) with lumbar disc herniation and sciatic pain, all European-Caucasian, were recruited from two hospitals in Norway. Pain and disability were rated on a visual analog scale (VAS), by McGill Sensory Questionnaire and by Oswestry Disability Index (ODI) over a 12 months period. The data revealed a significant interaction between sex and A118G genotype regarding the pain intensity during the 12 months (VAS, p = 0.002; McGill, p = 0.021; ODI, p = 0.205, repeated-measures ANOVA). We found that */G women had a slower recovery rate than the */G men. Actually, the */G women had 2.3 times as much pain as the */G men 12 months after the disc herniation (VAS, p = 0.043, one-way ANOVA; p = 0.035, Tukey HSD). In contrast, the A/A women and A/A men seemed to have almost exactly the same recovery rate. The present data suggest that OPRM1 G allele increases the pain intensity in women, but has a protective effect in men the first year after disc herniation.