IGF-I and IGF-binding proteins in articular exudates of children with post-traumatic knee damage and juvenile idiopathic arthritis.
OBJECTIVE
IGF-I stimulates multiple functions of connective tissue cells and its activity is modulated by IGF-binding proteins (BPs). Some metalloproteinases are expected to modify IGF-I activity by digestion of IGF-BPs. It was decided to evaluate the concentration of IGF-I, IGF-BPs and the activity of gelatinases A and B in knee exudates of children with post-traumatic damage (PTD) and children with juvenile idiopathic arthritis (JIA) in comparison with those in the sera of the same patients.


METHODS
ELISA (for IGF-I assay), polyacrylamine gel electrophoresis following Western immunoblotting (for IGF-I and IGF-BPs expression), and zymography (for gelatinase detection) were used.


RESULTS
The knee exudates, especially those taken from patients with JIA, contained large amounts of IGF-I. The exudates of PTD and JIA patients contained some forms of IGF-BP-1 of molecular weight lower than those occurring in serum. Low expression BP-3 and high activity of gelatinase B were detected in the JIA exudates.


CONCLUSIONS
The high gelatinase activities in exudates imply joint tissue damage. The cellular response to damage of this kind is an increase in IGF-I production, which stimulates repair processes. High proteolytic activities of gelatinase B in JIA patients may lower the amount of BP-3, possibly causing a relative decrease of IGF-I concentration and impairing the reparation processes stimulated by IGF-I.
Guszczyn
Tomasz
T
Department of Paediatric Orthopaedics and Traumatology, Medical University of Białystok, Białystok, Poland. tombial@mp.pl
Rzeczycka
Justyna
J
Popko
Janusz
J
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005122:Exudates and Transudates / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D007718:Knee Injuries / Q000378:metabolism* / Q000473:pathology; D007719:Knee Joint / Q000378:metabolism* / Q000473:pathology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000032:analysis / Q000378:metabolism
D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9