title: Lipid profile of human synovial fluid following intra-articular ankle fracture.
abstract: This study characterizes the metabolic profile of synovial fluid after intra-articular ankle fracture with an emphasis on changes in the lipid profile. Bilateral ankle synovial fluid from 19 patients with unilateral intra-articular ankle fracture was submitted for metabolic profiling. Contralateral ankle synovial fluid from each patient served as a matched control. Seven patients participated in a second bilateral synovial fluid collection after 6 months. Random forest classification, matched pairs t-tests (α < 0.01), repeated measures ANOVA with post-test contrasts (α < 0.01), correlation to cytokines and matrix metalloproteinases, and fracture and injury classification analyses yielded key lipid biomarkers in synovial fluid following intra-articular fracture. Free fatty acids, sphingomyelins, and lysolipids demonstrated significant elevation in fractured ankles at baseline. Fatty acids and sphingomyelins showed a significant decrease 6 months post-surgery. Random forest analysis showed predominantly fatty acids differentiating between groups. Significant correlations included fatty acids, sphingomyelins, and lysolipids with inflammatory cytokines and matrix metalloproteinases. Fracture classification showed increased fatty acids, lysolipids, and inositol metabolites as fracture severity increased. Fatty acid and sn-1 lysolipid elevation could be detrimental to the joint, as these strongly correlated with matrix metalloproteinases and TNF-α. This elevation also suggests involvement of phospholipase A2, a potential target for therapeutic intervention. Together with elevated 2-hydroxyl fatty acids, these findings suggest elevated sn-1 lysolipids, sphingomyelins, and subsequent lipid metabolites in synovial fluid as biomarkers of ankle injury. Reversal of this signature after 6 months suggests temporary involvement of these metabolites in disease progression, although they may activate signaling pathways which drive progression to osteoarthritis. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:657-666, 2017.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina.|Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri.|Albany Medical College, Albany, New York.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Leimer
authors.affiliation: Metabolon, Inc., Durham, North Carolina.
authors.forename: Kirk L
authors.initials: KL
authors.lastname: Pappan
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina.
authors.forename: Dana L
authors.initials: DL
authors.lastname: Nettles
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina.|University of Rochester Medical Center, Rochester, New York.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Bell
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Easley
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Olson
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina.|Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Lori A
authors.initials: LA
authors.lastname: Setton
authors.affiliation: Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Samuel B
authors.initials: SB
authors.lastname: Adams
mesh_terms: D000328:Adult; D064386:Ankle Fractures / Q000378:metabolism*; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013582:Synovial Fluid / Q000378:metabolism*; D055815:Young Adult
keywords: ankle fracture; lipidomics; metabolic profile; osteoarthritis; post-traumatic; synovial fluid