Neurotransmitter excitatory amino acids in synovial fluids demonstrate distinct temporal fluctuations in active arthritis

Terry A McNearney, Niti Goel, Jeffrey R Lisse, Karin N Westlund
2018 Rheumatology and Orthopedic Medicine  
Objective: This case study presents concentrations of synovial fluid (SF) neurotransmitter excitatory amino acids (EAA) glutamate (Glu) and aspartate (Asp) and tumor necrosis factor-alpha (TNFα) in patients with acute onset and chronic arthropathies over time. Methods: SF samples were sequentially obtained daily from both knees of a patient with acute clinically distinct flares of pseudogout. Two SF samples (same knee) were also obtained from 3 rheumatoid arthritis (RA) patients during active
more » ... nts during active flares. SF EAA and other amino acids (AA) were measured by HPLC, TNFα levels by immunoassay, and SF WBC counts by hemocytometer. SF EAA, other AA and TNFα levels are presented as ratios derived from matched cadaveric SF samples with no antemortem history of active arthritis. Results: Sequential SF Glu and Asp levels from 3 of 4 patients demonstrated impressive fluctuations over time spans from days to years. SF Glu, Asp and serine (Ser) levels were several-fold to higher than other SF AA levels from the patient with pseudogout flares and demonstrated fluctuations over days. Increases in SF WBC counts and Glu levels preceded increases in SF TNFα levels and WBC counts also showed temporal fluctuations. Conclusion: SF neurotransmitter Glu and Asp level fluctuations were independent of other AA levels or other joint compartments. SF EAA Glu and Asp may reflect and/or further impact ongoing inflammatory intra-articular processes. Further studies will elucidate their utility in arthritis as biomarkers or as novel antiinflammatory targets. An understanding of their fluctuations in acute arthritis could inform the management of joints in the immediate post-trauma setting. McNearney TA (2018) Neurotransmitter excitatory amino acids in synovial fluids demonstrate distinct temporal fluctuations in active arthritis Volume 3(4): 2-5
doi:10.15761/rom.1000161 fatcat:wzvayxnr5jhn5ehwwfmprmgcja