title: Serum from children with polyarticular juvenile idiopathic arthritis (pJIA) inhibits differentiation, mineralization and may increase apoptosis of human osteoblasts "in vitro".
abstract: We examined the effects of polyarticular juvenile idiopathic arthritis (pJIA) serum on proliferation, differentiation, mineralization, and apoptosis of human osteoblast cells (hOb) in culture. The hOb were cultured with 10% serum from active pJIA and healthy controls (CT) and were tested for DNA synthesis, alkaline phosphatase (AP) activity, osteocalcin (OC) secretion, calcium levels, caspase 3 activity, and DNA fragmentation. None of the patients had used glucocorticoids for at least 1 month before the study, or any other drug that can affect bone mineral metabolism. Human inflammatory cytokine levels (IL-6, IL-8, IL-10, IL-1beta, TNF-alpha, and IL-12p70) were measured in pJIA and CT sera. Low levels of AP activity was observed in pJIA cultures compared with CT cultures (67.16 +/- 53.35 vs 100.11 +/- 50.64 mumol p-nitrophenol/h(-1) mg(-1) protein, P = 0.008). There was also a significant decrease in OC secretion (9.23 +/- 5.63 vs 12.82 +/- 7.02 ng/mg protein, P = 0.012) and calcium levels (0.475 +/- 0.197 vs 0.717 +/- 0.366 mmol/l, P = 0.05) in pJIA hOb cultures. No difference was observed in cell proliferation (323.56 +/- 108.23 vs 328.91 +/- 88.03 dpm/mg protein, P = 0.788). Osteoblasts cultured with JIA sera showed lower levels of DNA and increased fragmentation than osteoblasts cultured with CT sera. pJIA sera showed higher IL-6 values than CT (21.44 +/- 9.31 vs 3.58 +/- 2.38 pg/ml, P < 0.001), but no difference was observed related to IL-8, IL-10, IL-1beta, TNF-alpha, and IL-12p70 between pJIA and controls. This study suggests that serum from children with pJIA inhibits differentiation, mineralization and may increase apoptosis of hOb cultures, and inflammatory cytokines such as IL-6 might be a mechanism in this find. These results may represent an alternative therapeutic target for prevention and treatment of bone loss in JIA.
authors.affiliation: Rheumatology Division, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Valéria F
authors.initials: VF
authors.lastname: Caparbo
authors.forename: Flávia
authors.initials: F
authors.lastname: Prada
authors.forename: Clóvis A A
authors.initials: CA
authors.lastname: Silva
authors.forename: Paula L
authors.initials: PL
authors.lastname: Regio
authors.forename: Rosa M R
authors.initials: RM
authors.lastname: Pereira
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D017209:Apoptosis; D001171:Arthritis, Juvenile / Q000097:blood* / Q000503:physiopathology; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D002648:Child; D016207:Cytokines / Q000378:metabolism; D004247:DNA / Q000032:analysis; D053938:DNA Fragmentation; D005260:Female; D006801:Humans; D008297:Male; D010006:Osteoblasts / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000378:metabolism; D044967:Serum / Q000378:metabolism*
chemical_list: D016207:Cytokines; D015675:Osteocalcin; D004247:DNA; D000469:Alkaline Phosphatase; D002118:Calcium