Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801
Performing Department
Veterinary Research & Extension
Non Technical Summary
Intra-articular corticosteroid (CS) administration is a major therapeutic strategy to control clinical signs resulting from arthritis in performance horses. The significant therapeutic effects of CS administration on the clinical signs of arthritis are not without cost. CSs are immuno-suppressive and also suppress biosynthetic activities of many cell types, including articular chondrocytes. This suppressive activity on chondrocyte matrix synthetic activity is believed to contribute to the phenomenon of steroid arthropathy, in concert with the direct damage generated through inappropriate use of compromised joints. The proposed research will investigate the role of bone morphogenetic proteins and transforming growth factor-bs on the means by which CS administration compromises cartilage matrix synthesis. Both BMPs and TGF-bs are known to be vital for the maintenance of healthy articular cartilage. The hypothesis addressed by this research project is that corticosteroid-induced suppression of articular chondrocyte matrix synthesis is a consequence of reduced BMP ligand expression and activity. This hypothesis will be addressed through three experimental Aims. Experiments in Aim 1 will assess the effects of CS administration on expression of known chondro-anabolic TGF-b and BMP ligands, their cognate receptors and inhibitors, using QPCR and Elisa assays. The overall goal of this Aim is to generate a comprehensive map of the impact CSs exert on TGF-b and BMP signaling factors in articular chondrocytes. We expect that CSs will suppress expression of BMP-2 and TGF-b1, at least, and might also have negative influences on the receptors for these ligands. The experiments in Aim 2 will determine whether intra-articular corticosteroid administration in vivo influences BMP concentrations in synovial fluid, using ELISa assays and resonses of BMP and TGF-b reporter cell lines. The experiments in this Aim will clarify the clinical significance of suppressed BMP/TGF-b secretion in horses following intra-articular corticosteroid administration. We expect that CS injections will redice synovial BMP and TGF-b levels. Experiments in Aim 3 will determine whether exogenous BMP ligand administration antagonizes the negative effects of corticosteroids on articular chondrocyte activities. These experiments will clarify whether BMP supplementation can prevent the negative bio-synthetic effects of CS administration on articular chondrocytes.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Intra-articular corticosteroid (CS) administration is a major therapeutic strategy to control clinical signs resulting from arthritis. CSs classically exert their anti-inflammatory effects by blocking phospholipase A activity, reducing the conversion of cell wall phospholipids to active inflammatory mediators. It is well recognized, however, that CSs influence cell activities through a number of signaling mechanisms, notably the MAPK, NFkB and STAT signaling pathways. The significant therapeutic effects of CS administration on joint inflammation are not without cost. CSs are immuno-suppressive and also suppress biosynthetic activities of many cell types, including articular chondrocytes. This suppressive activity on chondrocyte matrix synthetic activity is believed to contribute to the phenomenon of steroid arthropathy, in concert with the direct damage generated through inappropriate use of compromised joints. The proposed research is focused on determining the mechanism by which CS administration suppresses cartilage matrix synthesis, and focuses on the BMP signaling pathways. Both these pathways are known to be vital for the maintenance of healthy articular cartilage. This focus is derived from preliminary data demonstrating that CS profoundly down-regulates expression of both BMP-2 and TGF-b1 by articular chondrocytes, along with matrix gene suppression. The hypothesis addressed by this research project is that corticosteroid-induced suppression of articular chondrocyte matrix synthesis is a consequence of reduced BMP ligand expression and activity. This hypothesis will be addressed through three experimental Aims. Experiments in Aim 1 will assess the effects of CS administration on expression of known chondro-anabolic TGF-b and BMP ligands, their cognate receptors and inhibitors. The overall goal of this Aim is to generate a comprehensive map of the impact CSs exert on TGF-b and BMP signaling factors in articular chondrocytes. The experiments in Aim 2 will determine whether intra-articular corticosteroid administration in vivo influences BMP concentrations in synovial fluid. The experiments in this Aim will clarify the clinical significance of suppressed BMP ligand secretion in horses following intra-articular corticosteroid administration. Experiments in Aim 3 will determine whether exogenous BMP ligand administration antagonizes the suppressive effects of corticosteroids on articular chondrocyte matrix synthesis in vitro. The experiments in this Aim will clarify whether corticosteroid-mediated suppression of articular chondrocyte biosynthetic activities can be prevented or mitigated by BMP ligand supplementation.
Project Methods
The experiments in Aim 1 will be carried out with an in vitro aggregate culture model, using equine articular chondrocytes. The effects of corticosteroid administration on the expression of BMP and TGFb ligands, receptors and inhibitors will be assessed by quantitative PCR and by BMP-2 and TGF-b1 ELISA assays of culture medium. The experiments in Aim 2 will measure synovial fluid BMP-2 and TGF-b1 concentrations after intra-articular corticosteroid injections by ELISA assays and by the use of BMP- and TGF-b- reporter cel lines. The experiments in Aim 3 will use the same in vitro model outlined in Aim 1, annd will use exogenous recombinant BMP-2 and TGF-b1 protein in the presence and absence of homeostatically significant corticosteroid concentrations.