Project description:We performed genome-wide DNA methylation analysis of 850,000 CpG sites in women and men with chronic Low Back Pain (LBP) and pain free-controls. T cells were isolated (Discovery Cohort, n=32) and used to identify differentially methylated CpG sites, and gene ontologies and molecular pathways were identified.T cells were isolated (Discovery Cohort, n=32) and used to identify differentially methylated CpG sites, and gene ontologies and molecular pathways were identified. A polygenic DNA methylation score for LBP was generated in both women and men. Validation was performed in an independent cohort (Validation Cohort, n=63) of chronic LBP and healthy controls. Analysis with the Discovery Cohort revealed a total of 2,496 and 419 differentially methylated CpGs in women and men, respectively. The majority of these sites were hypo-methylated in women and enriched in genes with functions in the extracellular matrix, the immune system (i.e. cytokines) or in epigenetic processes. In men, we identified a unique chronic LBP DNA methylation signature characterized by significant enrichment for genes from the major histocompatibility complex. A sex-specific polygenic DNA methylation score was generated to evaluate the pain status of each individual and confirmed in The Validation Cohort using pyrosequencing.
Project description:Background. Inter- and intra-individual fluctuations in pain intensity pose a major challenge to treatment efficacy, with a majority perceiving their pain relief as inadequate. Recent preclinical studies have identified circadian rhythmicity as a potential contributor to these fluctuations and therapeutic target. Methods. We therefore sought to determine the impact of these rhythms in people with chronic low back pain (CLBP) through a detailed characterization, including questionnaires to evaluate biopsychosocial characteristics, ecological momentary assessment (7-day e-diaries at 8:00/14:00/20:00) to assess pain fluctuations, and intra-day blood transcriptomics (8:00/20:00) to identify genes/pathways of interest. Results. While most individuals displayed constant or variable/mixed pain phenotypes, a distinct subset had daily fluctuations of increasing pain scores (>30% change in intensity over 12-hours in ≥4/7 days). This population had no opioid users, better biopsychosocial profiles, and differentially expressed transcripts relative to other pain phenotypes. The circadian-governed neutrophil degranulation pathway was particularly enriched among arhythmic individuals; the link between neutrophil degranulation and opioid use was further confirmed in a separate CLBP cohort. Conclusion. Our findings identify pain rhythmicity and the circadian expression of neutrophil degranulation pathways as indicators of CLBP outcomes, which may help provide a personalized approach to phenotyping biopsychosocial characteristics and medication use. This highlights the need to better understand the impact of circadian rhythmicity across chronic pain conditions.
Project description:There are currently no therapies for the staggering disability and public health costs of chronic low back pain (LBP). Innervation of the degenerating intervertebral disc (IVD) is suspected to cause discogenic LBP, but the mechanisms that orchestrate the IVD’s neo-innervation and subsequent symptoms of LBP remain unknown. We hypothesize that Vascular Growth Endothelial Factor-A (VEGFA) critically mediates the neurite invasion in the IVD and contributes to prolonged LBP. Initiating IVD degeneration through a mechanical injury, we evaluated the progression of neurovascular features into the IVD, as well as resultant LBP symptoms and locomotive performance at acute (3-weeks) and prolonged (12-weeks) time points following IVD injury. To determine the role of VEGFA, we used a mouse model with ubiquitous inducible recombination of the floxed VEGFA allele (UBC-CreERT2; VEGFAfl/fl). The ablation of VEGFA attenuated the neurite and vessel infiltration into the degenerating IVD, and the VEGFA-null animals exhibited alleviated mechanical allodynia and improved locomotive performance. To determine the effects of IVD-derived VEGFA on endothelial cells and neurons, we cultured HMEC-1 endothelial cells and SH-SY5Y neurons using conditioned media from VEGFA-silenced (siRNA) human primary IVD cells stimulated by IL1b. The endothelial cells and neurons exposed to the secretome of the VEGFA-silenced IVD cells exhibited reduced growth, suggesting that the inhibition of IVD-derived VEGFA may be sufficient to attenuate intradiscal neurovascular features. Together, we show that VEGFA orchestrates the growth of intradiscal vessels and neurites that cause low back pain and impaired function, and the inhibition of VEGFA can prevent prolonged low back pain.
Project description:Chronic low back pain (cLBP) lacks clear physiological explanations, and the treatment options are of limited effect. Here, we elucidate the underlying biology of cLBP in a subgroup of patients with Modic changes type I (suggestive of inflammatory vertebral bone marrow lesions) by correlating gene expression in blood with patient-reported outcomes on disability and pain intensity and explore sex-differences. Patients were included from the placebo group of a clinical study on patients with cLBP and Modic changes. Blood was collected at the time of inclusion, after three months, and after one year, and gene expression was measured at all time points by high-throughput RNA sequencing. The patients reported disability using the Roland Morris Disability Questionnaire, and pain intensity was assessed as a mean of three scores on a 0-10 numeric rating scale: current LBP, worst LBP within the last two weeks, and mean LBP within the last two weeks. The gene expression profiles were then correlated to the reported outcomes. Changes in gene expression over time correlated significantly with changes in both disability and pain. The findings showed distinct patterns in men and women, with negligible overlap in correlated genes between the sexes. The genes involved were enriched in immunological pathways, particularly T cell receptor complex and immune responses related to neutrophils. Several of the genes harbour polymorphisms that previously have been found to be associated with chronic pain. Men and women had distinct sets of correlating genes, suggesting gender differences in the underlying biology of disability and pain in these patients.
Project description:This study presents the first application of comprehensive single-nuclei RNA sequencing (snRNA-seq) of dorsal root ganglion (DRG) neurons in a rat model using Parse technology. Our dataset includes two experimental models: (1) control rats representing both sexes and (2) rats with disc-associated chronic lower back pain, alongside sham-treated animals. By leveraging high-resolution transcriptomic profiling, this study provides novel insights into the molecular landscape of DRG neurons, offering a valuable resource for understanding the cellular mechanisms underlying chronic pain.
Project description:We used transcriptome-wide data to investigate the molecular pathophysiological mechanisms in peripheral blood immune cells at the transcriptome-wide level that underlie the transition of acute to chronic low back pain.
Project description:Gene expression correlates with disability and pain intensity in patients with chronic low back pain and Modic changes in a sex-specific manner
Project description:Ablation of VEGFA following a lumbar intervertebral disc injury attenuates intradiscal neurovascular features and prevents chronic low back pain symptoms
Project description:The cellular and molecular dynamics at human acupuncture points remain largely unexplored. To address this, we developed a novel acupuncture-needle technique capable of collecting sufficient numbers of cells from acupuncture points during treatment. Using this approach in combination with single-nucleus RNA sequencing (snRNA-seq), we identified heterogeneous cell populations at the acupoint BL23. This study enabled characterization of the cellular and transcriptional changes occurring before and after acupuncture treatment in patients with lower back pain (lumbar sprain), offering new insights into the mechanisms underlying acupuncture-induced pain relief.