Lipopolysaccharide alters aggrecan metabolism in the growth plate.
In this study, we examined the influence of lipopolysaccharide (LPS) on aggrecan metabolism and structure in the growth plate. Two experimental approaches were used: (i) in vivo administration of LPS to 10-day-old chicks; and (ii) in vitro addition of LPS to explant culture of normal chick growth plate. Twelve-day-old male broiler chicks were killed 48 hr after intravenous injection of LPS (3 mg/kg) or saline (control), and growth plate from the femur or tibia was cultured or frozen. Tissue for explant culture was (i) cultured for 5 days with daily medium change (glycosaminoglycan release into the medium estimates proteoglycan breakdown rates), or (b) incubated with 35SO4 to determine the rate of proteoglycan synthesis. Proteoglycan structure was determined by associative (0.5 M sodium acetate) and dissociative (4 M guanidine HCl) Sepharose CL2B chromatography. Explant culture of growth plate from LPS-injected chicks (in vivo) showed a decrease (P < 0.05) in the rate of proteoglycan synthesis. There were a greater proportion of small monomers and a reduced ability to aggregate in growth plate from LPS-injected chicks. In vitro addition of LPS (100 micrograms/ml) to explant culture medium reduced proteoglycan synthesis (P < 0.02), and the rate of release was increased (P < 0.001). In addition, the total and newly synthesized proteoglycans released into the medium from LPS-treated explant culture had a reduced aggregation and a majority of monomers that were smaller than control. These results demonstrate that LPS disrupts the normal metabolism and structure of growth plate aggrecan, and we hypothesize that this may adversely influence longitudinal growth.
Chong
L J
LJ
Department of Nutritional Sciences, Rutgers University, Cook College, New Brunswick, New Jersey 08903-0231, USA.
Shapses
S A
SA
D053674:Aggrecans; D000818:Animals; D002645:Chickens; D016326:Extracellular Matrix Proteins; D006132:Growth Plate / Q000187:drug effects* / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D037181:Lectins, C-Type; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D015394:Molecular Structure; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism*
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D011509:Proteoglycans