title: Plasma pro-inflammatory markers in chronic neuropathic pain: A multivariate, comparative, cross-sectional pilot study.
abstract: Caused by a lesion or disease of the somatosensory system, neuropathic pain is notoriously difficult to treat with conventional analgesics. It has been suggested that inflammatory cytokines play a role in the development and maintenance of neuropathic pain. But human studies of these substances are relatively few and partly contradictory.
  
  
  
  To simultaneously investigate the plasma levels of chemokine interleukin 8 (IL-8) and the cytokines IL-6, IL-1β, and Granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with peripheral neuropathic pain (most of whom due to failed back surgery syndrome) (n=14) compared to controls (n=17).
  
  
  
  IL-6 was significantly higher in patients than in controls (0.92±0.12pg/ml vs. 0.57±0.08pg/ml, p=0.012). IL-1β, IL-8, and GM-CSF levels did not differ between the two groups. A multivariate analysis showed a tendency for patients also to have higher GM-CSF plasma levels than controls.
  
  
  
  This study found an increased level of IL-6 in plasma in patients with neuropathic pain, but not for the other pro-inflammatory substances investigated. There are several possible confounders not registered or controlled for in this and other studies of neuropathic pain.
  
  
  
  Larger studies that take several possible confounders into consideration are needed to further investigate the levels of plasma cytokines in different pain conditions.
authors.affiliation: Division of Community Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University,LinköpingSweden.|Pain and Rehabilitation Centre, Anaesthetics, Operations and Specialty Surgery Centre, Region Östergötland, Sweden.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Bäckryd
authors.affiliation: Division of Community Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University,LinköpingSweden.|Pain and Rehabilitation Centre, Anaesthetics, Operations and Specialty Surgery Centre, Region Östergötland, Sweden.
authors.forename: Bijar
authors.initials: B
authors.lastname: Ghafouri
authors.affiliation: Division of Community Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University,LinköpingSweden.|Pain and Rehabilitation Centre, Anaesthetics, Operations and Specialty Surgery Centre, Region Östergötland, Sweden.
authors.forename: Britt
authors.initials: B
authors.lastname: Larsson
authors.affiliation: Division of Community Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University,LinköpingSweden.|Pain and Rehabilitation Centre, Anaesthetics, Operations and Specialty Surgery Centre, Region Östergötland, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Gerdle
mesh_terms: D015415:Biomarkers; D018925:Chemokines; D059350:Chronic Pain / Q000378:metabolism*; D003430:Cross-Sectional Studies; D016207:Cytokines / Q000378:metabolism*; D016179:Granulocyte Colony-Stimulating Factor; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6; D009437:Neuralgia / Q000378:metabolism*; D010865:Pilot Projects
chemical_list: D015415:Biomarkers; D018925:Chemokines; D016207:Cytokines; D015850:Interleukin-6; D016179:Granulocyte Colony-Stimulating Factor
keywords: Chemokine; Cytokine; Human; Interleukin; Neuropathic; Pain; Plasma