title: Brain-derived neurotrophic factor is increased in serum and skin levels of patients with chronic spontaneous urticaria.
abstract: BACKGROUND
  Chronic spontaneous urticaria is triggered by many direct and indirect aggravating factors including autoreactive/autoimmune mechanisms, infections, non-allergic and pseudoallergic intolerance reactions. However, the role of neuroimmune mechanisms in chronic spontaneous urticaria so far is unclear.
  
  
  OBJECTIVE
  Thus, we wanted to address the regulation of the neurotrophin brain-derived neurotrophic factor (BDNF) in serum and inflammatory skin of patients with chronic spontaneous urticaria in comparison to subjects with healthy skin.
  
  
  METHODS
  Fifty adult patients with chronic spontaneous urticaria and 23 skin-healthy subjects were studied. Chronic spontaneous urticaria was defined as recurrent weals for more than 6 weeks. Autologous serum skin test was performed in all patients with chronic spontaneous urticaria and BDNF serum levels were analysed by enzyme immunoassay in all subjects. Furthermore, skin biopsies were taken from weals of eight patients with chronic spontaneous urticaria as well as from healthy skin of eight controls to evaluate the expression of BDNF and its receptors including tyrosine kinase (trk) B and pan-neurotrophin receptor p75(NTR) by immunohistochemistry.
  
  
  RESULTS
  BDNF serum levels were detectable in all subjects studied. However, BDNF levels were significantly higher in patients with chronic spontaneous urticaria compared to non-atopic skin-healthy controls (P<0.001). Furthermore, epidermal and dermal expression of BDNF and epidermal expression of p75(NTR) was significantly higher in patients with chronic spontaneous urticaria compared with controls (P<0.05-0.001). There was no difference with regard to the expression of trkB between chronic spontaneous urticaria and controls and no difference in BDNF serum levels between autologous serum skin test-positive (n=23) and -negative (n=27) patients with chronic spontaneous urticaria.
  
  
  CONCLUSIONS
  This study shows that BDNF is increased in serum and diseased skin of patients with chronic spontaneous urticaria, suggesting a role for neurotrophins in the pathophysiology of this chronic inflammatory skin disease. Further studies are needed to address the functional role of BDNF on key target effector cells in chronic spontaneous urticaria to establish new therapeutic implications.
authors.affiliation: Department of Dermatology and Allergy, Hannover Medical School, Hannover, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Rössing
authors.forename: N
authors.initials: N
authors.lastname: Novak
authors.forename: S
authors.initials: S
authors.lastname: Mommert
authors.forename: F
authors.initials: F
authors.lastname: Pfab
authors.forename: M
authors.initials: M
authors.lastname: Gehring
authors.forename: B
authors.initials: B
authors.lastname: Wedi
authors.forename: A
authors.initials: A
authors.lastname: Kapp
authors.forename: U
authors.initials: U
authors.lastname: Raap
mesh_terms: D000328:Adult; D000368:Aged; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood* / Q000378:metabolism*; D002908:Chronic Disease; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D008875:Middle Aged; D012867:Skin / Q000378:metabolism*; D015854:Up-Regulation; D014581:Urticaria / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D019208:Brain-Derived Neurotrophic Factor