Messenger RNA expression of multiple immune mediators in leukocytes from elective orthopaedic surgical patients

The aim of this longitudinal observational study was to investigate and describe the spectrum of messenger ribonucleic acid (mRNA) expression of multiple inflammatory markers in circulating leukocytes after major orthopaedic surgery. We studied ten elective arthroplasty patients perioperatively on the orthopaedic ward, and eight healthy volunteers for a comparison group. Venous blood specimens were collected preoperatively, and 6, and 24 hours postoperatively, together with 6- and 24-hour postoperative wound drain specimens. The mRNA of 21 different inflammatory mediators was measured by real-time reverse transcriptase Polymerase Chain Reaction. Comparisons were made with the venous blood of eight healthy comparison subjects. There were significant differences (P<0.01) between preoperative specimens and normal comparisons (i.e. higher MPO, PDGF, TREM and IRAKM; lower mtHSP) reflecting the effects of chronic inflammation associated with osteoarthritis. There were significant increases (P<0.01) in expression of IL-8, MPO, IL-1beta, TREM, MMP9, and C5aR in circulating blood at 24 hours postoperatively, but not at six hours. There was no significant decrease in expression of any inflammatory mediator. There was no statistical difference in inflammatory mediator expression between drain specimens and venous specimens taken at the same time. We conclude that, in uncomplicated orthopaedic surgical patients, there was up-regulation of some cytokine mRNAs at both the local and systemic levels during the first day after surgery. We observed no evidence of immune compartmentalization, and found no evidence for innate immune paresis within the first day after surgery.