title: Inflammatory cytokines and cellular metabolites as synovial fluid biomarkers of posttraumatic ankle arthritis.
abstract: BACKGROUND
  There is a paucity of research on posttraumatic ankle arthritis (PTAA). We aimed to identify synovial fluid PTAA biomarkers using cytokine analysis and metabolic profiling.
  
  
  METHODS
  Ankle joint synovial fluid was obtained from 20 patients with PTAA and 20 patients with no ankle pain and no radiographic evidence of ankle arthritis (control group). Synovial fluid samples were analyzed for IFN-γ, TNF-α, MIP-1β, MCP-1, IL-1β, IL-1Ra, IL-4, IL-6, IL-8, IL-10, IL-13, and IL-15 using ELISA and for more than 3000 metabolites using liquid and gas chromatography with mass spectroscopy. To compare presence of cytokines and metabolites between groups, t tests were used. Random forest analysis was performed on metabolites to determine whether control and PTAA samples could be differentiated based on metabolic profile.
  
  
  RESULTS
  IL-1Ra, IL-6, IL-8, IL-10, IL-15, and MCP-1 were significantly elevated in the PTAA group. In addition, 107 metabolites in the PTAA group were significantly altered, including derangement in amino acid, carbohydrate, lipid, and energy metabolism, extracellular matrix turnover, and collagen degradation. Random forest analysis yielded a predictive accuracy of 90% when using the metabolic profiles to distinguish between control and PTAA samples.
  
  
  CONCLUSIONS
  This study identified inflammatory cytokines and metabolites present in the synovial fluid of PTAA.
  
  
  CONCLUSIONS
  Several of these entities have previously been implicated in rheumatoid arthritis and osteoarthritis of the knee, but many could potentially be used as novel biomarkers of PTAA. Most importantly, the findings suggest that metabolites could be used to distinguish synovial fluid from patients with PTAA.
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Samuel B
authors.initials: SB
authors.lastname: Adams
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, NC, USA.
authors.forename: Dana L
authors.initials: DL
authors.lastname: Nettles
authors.affiliation: Department of Orthopaedic Surgery, Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors.forename: Lynne C
authors.initials: LC
authors.lastname: Jones
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Miller
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Guyton
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA Lyn.camire@medstar.net.
authors.forename: Lew C
authors.initials: LC
authors.lastname: Schon
mesh_terms: D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000378:metabolism* / Q000503:physiopathology; D001168:Arthritis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D016022:Case-Control Studies; D016207:Cytokines / Q000378:metabolism*; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D055442:Metabolome / Q000502:physiology*; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000378:metabolism; D011859:Radiography; D012016:Reference Values; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000378:metabolism*; D014947:Wounds and Injuries / Q000150:complications* / Q000175:diagnosis
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators
keywords: ankle; arthritis; biomarkers; cytokines; metabolic profiling; posttraumatic; synovial fluid