Inhibition of early response genes prevents changes in global joint metabolomic profiles in mouse post-traumatic osteoarthritis.

OBJECTIVE: Although joint injury itself damages joint tissues, a substantial amount of secondary damage is mediated by the cellular responses to the injury. Cellular responses include the production and activation of proteases (MMPs, ADAMTSs, Cathepsins), and the production of inflammatory cytokines. The trajectory of cellular responses is driven by the transcriptional activation of early response genes, which requires Cdk9-dependent RNA Polymerase II phosphorylation. Our objective was to determine whether inhibition of cdk9-dependent early response gene activation affects changes in the joint metabolome. DESIGN: To model post-traumatic osteoarthritis, we subjected mice to non-invasive Anterior Cruciate Ligament (ACL)-rupture joint injury. Following injury, mice were treated with flavopiridol - a potent and selective inhibitor of Cdk9 kinase activity - to inhibit Cdk9-dependent transcriptional activation, or vehicle control. Global joint metabolomics were analyzed 1 h after injury. RESULTS: We found that injury induced metabolomic changes, including increases in Vitamin D3 metabolism, anandamide, and others. Inhibition of primary response gene activation immediately after injury largely prevented the global changes in the metabolomics profiles. Cluster analysis of joint metabolomes identified groups of injury-induced and drug-responsive metabolites. CONCLUSIONS: Metabolomic profiling provides an instantaneous snapshot of biochemical activity representing cellular responses. We identified two sets of metabolites that change acutely after joint injury: those that require transcription of primary response genes, and those that do not. These data demonstrate the potential for inhibition of early response genes to alter the trajectory of cell-mediated degenerative changes following joint injury, which may offer novel targets for cell-mediated secondary joint damage.

Characterization of synovial fluid metabolomic phenotypes of cartilage morphological changes associated with osteoarthritis.

OBJECTIVE: Osteoarthritis (OA) is a multifactorial disease with etiological heterogeneity. The objective of this study was to classify OA subgroups by generating metabolomic phenotypes from human synovial fluid. DESIGN: Post mortem synovial fluids (n = 75) were analyzed by high performance-liquid chromatography mass spectrometry (LC-MS) to measure changes in the global metabolome. Comparisons of healthy (grade 0), early OA (grades I-II), and late OA (grades III-IV) donor populations were considered to reveal phenotypes throughout disease progression. RESULTS: Global metabolomic profiles in synovial fluid were distinct between healthy, early OA, and late OA donors. Pathways differentially activated among these groups included structural deterioration, glycerophospholipid metabolism, inflammation, central energy metabolism, oxidative stress, and vitamin metabolism. Within disease states (early and late OA), subgroups of donors revealed distinct phenotypes. Synovial fluid metabolomic phenotypes exhibited increased inflammation (early and late OA), oxidative stress (late OA), or structural deterioration (early and late OA) in the synovial fluid. CONCLUSION: These results revealed distinct metabolic phenotypes in human synovial fluid, provide insight into pathogenesis, represent novel biomarkers, and can move toward developing personalized interventions for subgroups of OA patients.

Chemistry to conservation: using otoliths to advance recreational and commercial fisheries management.

Otolith chemistry is an effective technique for evaluating fish environmental history, but its utility in fisheries management has not been comprehensively examined. Thus, a review of otolith chemistry with emphasis on management applicability is presented. More than 1500 otolith chemistry manuscripts published from 1967 to 2015 are reviewed and descriptive case studies are used to illustrate the utility of otolith chemistry as a fisheries management tool. Otolith chemistry publications span a wide variety of topics (e.g. natal origins, habitat use, movement, stock discrimination and statistical theory) and species in freshwater and marine systems. Despite the broad distribution of manuscripts in a variety of fisheries, environmental and ecological journals, the majority of publications (83%, n = 1264) do not describe implications or applications of otolith chemistry for fisheries management. This information gap is addressed through case studies that illustrate management applications of otolith chemistry. Case studies cover numerous topics (e.g. natal origins, population connectivity, stock enhancement, transgenerational marking, pollution exposure history and invasive species management) in freshwater and marine systems using sport fishes, invasive fishes, endangered fishes and species of commercial and aquaculture importance. Otolith chemistry has diverse implications and applications for fisheries management worldwide. Collaboration among fisheries professionals from academia, government agencies and non-governmental organizations will help bridge the research-management divide and establish otolith chemistry as a fisheries management tool.