Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Gene Expression Profiling Of Spinal Cord Injured Patients With Intractable Neuropathic Pain

ABSTRACT: Objective: Chronic pain is a major problem in patients with spinal cord injury (SCI). According to different studies, approximately 70% of patients with SCI experience persistent pain. Although previous gene expression profiling studies have been conducted in animal models, gene expression profiling study in human whole blood has not been reported yet. The objective of this study was to define the gene expression profile of neuropathic pain in spinal cord injured patients. Materials and Methods: We performed gene expression analysis including 20.000 genes using Affymetrix GeneChip® Primeview™ Human Gene Expression Arrays. For confirmation of expression levels of selected genes, we performed real time polymerase chain reaction. We gathered samples from periferic blood mononuclear cells. Data of twelve patients with intractable neuropathic pain was compared with thirteen patients who don’t have pain. All patients have complete injuries with a level of injury above T5. Results: A total of 16 differentially expressed genes including 9 up-regulated and 7 down-regulated were obtained with a cut-off degree at 4 fold change. EIF1AY, RPS4Y1, DDX3Y, RPL31, ETS1, KLF3, JUN, CYorf15B, and ERAP2 were in up-regulated and HLA-C, XIST, C4BPA, FAM118A, ZNF506, OVOS2, and C1D were in down-regulated group. KEGG pathway database showed that 14.6% of genes were enriched in the nodes of immune system. Real time polymerase chain reaction analyses did not increase to statistically significant levels for confirmation of gene expression analyze results. Conclusions: Considering these data, findings of this first gene expression study in humans with SCI might provide valuable information for future targets for understanding neuropathic pain pathogenesis. The results of gene expression analyses were not confirmed by real time polymerase chain reaction. Studies with larger sample size are needed for confirmation. This is a cross-sectional study with a control group. Patients were divided into two groups according to intractable neuropathic pain existence.There were 12 patients in group A (Patients with pain) and 13 patients in control group.

ORGANISM(S): Homo sapiens

SUBMITTER: Emre Adıgüzel

PROVIDER: E-GEOD-69901 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Peripheral nerve injury alters the expression of hundreds of proteins in dorsal root ganglia (DRG). Targeting some of these proteins has led to successful treatments for acute pain, but not for sustained postoperative neuropathic pain. The latter may require targeting multiple proteins. Since a single microRNA (miR) can affect the expression of multiple proteins, here, we describe an approach to identify chronic neuropathic pain-relevant miRs. We used two variants of the spared nerve injury (SNI): Sural-SNI and Tibial-SNI and found distinct pain phenotypes between the two. Both models induced strong mechanical allodynia, but only Sural-SNI rats maintained strong mechanical and cold allodynia, as previously reported. In contrast, we found that Tibial-SNI rats recovered from mechanical allodynia and never developed cold allodynia. Since both models involve nerve injury, we increased the probability of identifying differentially regulated miRs that correlated with the quality and magnitude of neuropathic pain and decreased the probability of detecting miRs that are solely involved in neuronal regeneration. We found seven such miRs in L3-L5 DRG. The expression of these miRs increased in Tibial-SNI. These miRs displayed a lower level of expression in Sural-SNI, with four having levels lower than those in sham animals. Bioinformatics analysis of how these miRs could affect the expression of some ion channels supports the view that, following a peripheral nerve injury, the increase of the 7 miRs may contribute to the recovery from neuropathic pain while the decrease of four of them may contribute to the development of chronic neuropathic pain. The approach used resulted in the identification of a small number of potentially neuropathic pain relevant miRs. Additional studies are required to investigate whether manipulating the expression of the identified miRs in primary sensory neurons can prevent or ameliorate chronic neuropathic pain following peripheral nerve injuries. To identify the miRs that were differentially dysregulated between Tibial-SNI and Sural-SNI, we first performed 12 microarrays in a limited number of samples (in four individual DRGs per group: Sham, Tibial-SNI and Sural-SNI; two L3-DRG and two L4-DRG). Then, miRs identified as having differential expression were corroborated with real time qRT-PCR in RNA isolated from individual DRGs (L3, L4 and L5) derived from 4 rats per group (not presented here, but in the manuscript).

Project description:Not all patients with nerve injury develop neuropathic pain. The extent of nerve damage and age at the time of injury are two of the few risk factors identified to date. In addition, preclinical studies show that neuropathic pain variance is heritable. To define such factors further, we performed a large-scale gene profiling experiment which plotted global expression changes in the rat dorsal root ganglion in three peripheral neuropathic pain models. This resulted in the discovery that the potassium channel alpha subunit KCNS1, involved in neuronal excitability, is constitutively expressed in sensory neurons and markedly downregulated following nerve injury. KCNS1 was then characterized by an unbiased network analysis as a putative pain gene, a result confirmed by single nucleotide polymorphism association studies in humans. A common amino acid changing allele, the 'valine risk allele', was significantly associated with higher pain scores in five of six independent patient cohorts assayed (total of 1359 subjects). Risk allele prevalence is high, with 18-22% of the population homozygous, and an additional 50% heterozygous. At lower levels of nerve damage (lumbar back pain with disc herniation) association with greater pain outcome in homozygote patients is P = 0.003, increasing to P = 0.0001 for higher levels of nerve injury (limb amputation). The combined P-value for pain association in all six cohorts tested is 1.14 E-08. The risk profile of this marker is additive: two copies confer the most, one intermediate and none the least risk. Relative degrees of enhanced risk vary between cohorts, but for patients with lumbar back pain, they range between 2- and 3-fold. Although work still remains to define the potential role of this protein in the pathogenic process, here we present the KCNS1 allele rs734784 as one of the first prognostic indicators of chronic pain risk. Screening for this allele could help define those individuals prone to a transition to persistent pain, and thus requiring therapeutic strategies or lifestyle changes that minimize nerve injury. Microarrays were run on mRNA extracted from adult rat L4 and L5 DRGs cells after 3,7,21,40 hours after three different sciatic nerve lesions [Spared Nerve Injury (SNI); Chronic Constriction Injury (CCI); Spinal Nerve Ligation (Ch) with Sham controls (SH)].

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Gene Expression Profiling Of Spinal Cord Injured Patients With Intractable Neuropathic Pain

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