title: Substance P stimulates production of inflammatory cytokines in human disc cells.
abstract: METHODS
  Laboratory study.
  
  
  OBJECTIVE
  The aims of this study were as follows: (1) to confirm that Substance P (SP) is expressed by nucleus pulposus (NP) and annulus fibrosus (AF) cells; (2) to determine the effect of SP on expression of inflammatory mediators in human disc cells and the effect of inflammatory mediators on the expression of SP; and (3) to characterize the relative expression of SP receptor isoforms in disc tissue and describe whether exposure to SP changes receptor expression.
  
  
  BACKGROUND
  SP, classically described as a neurotransmitter, acts as an inflammatory regulator in other tissue types, but its role within the intervertebral disc has not been characterized.
  
  
  METHODS
  Human AF and NP cells from 7 individuals were expanded in monolayer and maintained in alginate bead culture. Cells were treated with SP or interleukin (IL)-1β/tumor necrosis factor-α (TNF-α). After treatment, the cells were recovered and then RNA was isolated and transcribed into cDNA. Quantitative reverse-transcriptase polymerase chain reaction was performed to evaluate expression of inflammatory mediators and SP and its receptors.
  
  
  RESULTS
  Disc cells treated with SP demonstrated significant upregulation of IL-1β, IL-6, and IL-8 in NP and AF cells whereas significant upregulation of RANTES and TNF occurred only in the AF cells. AF and NP cells expressed SP at low levels; expression did not change significantly with SP treatment but was significantly upregulated after treatment with IL-1β/TNF-α. Both SP receptor isoforms were expressed by NP and AF cells.
  
  
  CONCLUSIONS
  SP upregulates inflammatory mediators in disc cells. SP and its receptors were expressed in both NP and AF cells, and expression did not change after treatment with SP but increased after treatment with IL-1β/TNF-α. SP likely acts in an autocrine or paracrine manner in intervertebral disc cells and may be involved in "crosstalk" between disc cells and neurons, providing a potential mechanism for transmission of painful discogenic stimuli.
authors.affiliation: From the Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Kepler
authors.forename: Dessislava Z
authors.initials: DZ
authors.lastname: Markova
authors.forename: Alan S
authors.initials: AS
authors.lastname: Hilibrand
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Vaccaro
authors.forename: Makarand V
authors.initials: MV
authors.lastname: Risbud
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Albert
authors.forename: D Greg
authors.initials: DG
authors.lastname: Anderson
mesh_terms: D000328:Adult; D018946:Chemokine CCL5 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D007403:Intervertebral Disc / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D018040:Receptors, Neurokinin-1 / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013373:Substance P / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018946:Chemokine CCL5; D016207:Cytokines; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D018040:Receptors, Neurokinin-1; D014409:Tumor Necrosis Factor-alpha; D013373:Substance P