title: Th17 lymphocyte levels are higher in patients with ruptured than non-ruptured lumbar discs, and are correlated with pain intensity.
abstract: BACKGROUND
  Th17 lymphocytes have important roles in inflammation and autoimmune disease. Research on relationship between Th17 lymphocytes and pain associated with lumbar disc herniation (LDH) is limited. The purpose of this study was to examine the association of pain and Th17 lymphocyte and interleukin (IL)-17 levels in patients with herniated and non-herniated lumbar discs.
  
  
  METHODS
  Thirty-four patients with single lumbar intervertebral disc herniation (median age, 44 years), and 17 healthy adults (median age, 37 years) were enrolled. Patients were divided into 2 groups depending on their magnetic resonance imaging (MRI) results and visual observations during surgery (group P, non-ruptured disc, n=15; group E, ruptured disc, n=19). Patients received posterior or transforaminal lumbar interbody fusion. Preoperative pain intensity was recorded using a visual analogue scale (VAS) score. The percentage of Th17 lymphocytes and IL-17 and prostaglandin E2 (PGE2) levels in peripheral blood were determined. Disc tissue was examined by immunohistochemistry for Th17 and IL-17 expression.
  
  
  RESULTS
  Preoperative VAS pain scores were significantly higher in group E than group P (8.32±1.04 vs. 6.33±2.68, respectively, p=0.009). Similarly, PGE2 level was greater in group E than group P (3.75±1.41pg/ml vs. 2.63±0.89pg/ml, respectively, p=0.011). Compared to healthy controls (1.05±0.19%), the percentage of Th17 cells was significantly greater in group P (1.52±0.62%, p=0.031), and the percentage in group E (2.99±1.09%, p<0.001) was significantly greater than in group P. The IL-17 expressions were similar. VAS pain score was positively correlated with Th17 proportion (r=0.489, p=0.003), and IL-17 concentration (r=0.458, p=0.007). PGE2 was also positively correlated with Th17 proportion (r=0.539, p=0.001), and IL-17 concentration (r=0.500, p=0.003). The expression of IL-17 was higher in the cells of group E and group P compared with normal tissue (p<0.001).
  
  
  CONCLUSIONS
  Immune system activation is responsible, at least in part, for the pain experienced by patients with LDH, and increased levels of Th17 lymphocytes and IL-17 contribute to the pain.
authors.affiliation: Department of Orthopaedics, Qilu Hospital, Shandong University, 107 WenhuaXi Road, Jinan 250012, People's Republic of China. Electronic address: chengleiyx@126.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Cheng
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Fan
authors.forename: Ben
authors.initials: B
authors.lastname: Liu
authors.forename: Xuping
authors.initials: X
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Nie
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015232:Dinoprostone / Q000097:blood; D005260:Female; D006801:Humans; D020381:Interleukin-17 / Q000097:blood*; D007405:Intervertebral Disc Displacement / Q000097:blood / Q000276:immunology*; D017116:Low Back Pain / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D008159:Lumbar Vertebrae / Q000293:injuries*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D057234:Preoperative Period; D058504:Th17 Cells / Q000276:immunology* / Q000378:metabolism; D064232:Visual Analog Scale
chemical_list: D020381:Interleukin-17; D015232:Dinoprostone
keywords: IL; IL-17; IVD; Intervertebral disc; LDH; Lumbar disc herniation; PBMCs; PGE2; T helper 17; T helper lymphocytes; Th; VAS; interleukin; intervertebral disc; lumbar disc herniation; peripheral blood mononuclear cells; prostaglandin E2; visual analogue scale