Cytokine, catabolic enzyme and structural matrix gene expression in synovial fluid following intra‐articular administration of triamcinolone acetonide in exercised horses

Abstract

This study supports the use of synovial fluid as a biological matrix for studying the effects of corticosteroids on gene expression. For the majority of genes studied the effects on expression relative to baseline for both inflammatory and matrix genes were prolonged relative to plasma and synovial fluid TA concentrations. Downregulation of collagen gene expression warrants the careful use of TA in horses.

Expression of inflammatory and structural matrix genes in synovial fluid following intra‐articular administration of isoflupredone acetate to exercised horses

“…However, as the proposed mechanism of action for inhibition of PLA2 by annexin is substrate depletion, this finding is not unexpected [25,26]. Also in agreement with the previous report describing the effects of intra-articular TCA in horses [10], the expression of PTGS2 (COX-2) was not significantly altered following IPA administration. Also in agreement with the previous report describing the effects of intra-articular TCA in horses [10], the expression of PTGS2 (COX-2) was not significantly altered following IPA administration.…”

“…The effects of corticosteroids on the expression levels of these genes in horses appear to differ depending on the specific corticosteroid and dose administered [32]. This is in contrast to a previous report describing the effects of TCA administration on the expression levels of genes encoding collagen, whereby significant downregulation was noted following intra-articular administration [10]. This is in contrast to a previous report describing the effects of TCA administration on the expression levels of genes encoding collagen, whereby significant downregulation was noted following intra-articular administration [10].…”

“…It should be noted that in the current study, as a first step in the assessment of the effects of IPA on samples to 7 days samples following intra-articular isoflupredone acetate administration to eight horses. Similar findings have been reported in synovial fluid collected from horses receiving TCA [10] and in the joints of mice following administration of dexamethasone [23]. Genes with mean transformed fold change ratios less than À2 and larger than +2 were considered significantly regulated.…”

“…In the presently reported study, while down-regulation of collagen genes (COL1A1 and COL1A2) was noted following saline administration, with the exception of the 96-h time point (COL1A1), IPA did not appear to have a significant effect on collagen expression. In that study, the investigators theorised that the alteration in collagen gene expression was not likely related to the drug itself but more likely a result of the arthrocentesis procedure, as similar changes in expression levels were noted in the control group [10]. In that study, the investigators theorised that the alteration in collagen gene expression was not likely related to the drug itself but more likely a result of the arthrocentesis procedure, as similar changes in expression levels were noted in the control group [10].…”

“…Our laboratory has previously described a method by which to assess the effectiveness and duration of effect of intra-articular TCA in horses by measuring expression levels of genes involved in the inflammatory process in synovial fluid, both prior to and for several weeks post drug administration [10]. Our laboratory has previously described a method by which to assess the effectiveness and duration of effect of intra-articular TCA in horses by measuring expression levels of genes involved in the inflammatory process in synovial fluid, both prior to and for several weeks post drug administration [10].…”