Expression patterns of neurotrophins and neurotrophin receptors in articular chondrocytes and inflammatory infiltrates in knee joint arthritis.
BACKGROUND
It is likely that neurotrophins (NTs) are of great importance for the articular cartilage and the inflammation process in arthritis.


METHODS
The immunohistochemical expression of the NTs nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) and the associated receptors p75, TrkA and TrkB was examined in the knee joint of arthritic and healthy mice.


RESULTS
Immunoreactions for NGF and BDNF were detected in cells and nerve fiber varicosities in the inflammatory infiltrates of the synovial tissue of arthritic joints but not in synovial tissue of controls. p75-immunoreactive nerve fiber-like strands were detected in inflammatory infiltrates. Immunostaining for NGF, BDNF, p75, TrkA and TrkB was noted in articular chondrocytes. There was a statistically significant decrease in reactions for NGF (p < 0.001), TrkA (p = 0.001) and p75 (p < 0.001) in articular chondrocytes in joints exhibiting severe arthritis.


CONCLUSIONS
The findings show that an NT system develops in inflammatory infiltrates of the synovial tissue. Furthermore, most interestingly, autocrine/paracrine effects appear to exist concerning NTs for the articular chondrocytes. The downregulated expression of NGF and NT receptors in articular chondrocytes in arthritis is a new aspect concerning the involvement of NTs in cartilage.
Grimsholm
Ola
O
Department of Integrative Medical Biology, Section for Anatomy, Umeå University, Umeå, Sweden. ola.grimsholm@anatomy.umu.se
Guo
Yongzhi
Y
Ny
Tor
T
Forsgren
Sture
S
D000818:Animals; D001169:Arthritis, Experimental / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology; D019902:Chondrocytes / Q000378:metabolism*; D007150:Immunohistochemistry; D007249:Inflammation / Q000378:metabolism; D007719:Knee Joint / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D009414:Nerve Growth Factors / Q000096:biosynthesis*; D017475:Receptors, Nerve Growth Factor / Q000096:biosynthesis*
D009414:Nerve Growth Factors; D017475:Receptors, Nerve Growth Factor