• Toru Igarashi, Takeshi Suzuki, Katsuya Mori, Kei Inoue, Hiroyuki Seki, Takashige Yamada, Shizuko Kosugi, Shizuka Minamishima, Nobuyuki Katori, Fumiya Sano, Takayuki Abe, and Hiroshi Morisaki.
• From the Department of Anesthesiology, Keio University School of Medicine, Tokyo, Japan; Center for Clinical Research, Keio University School of Medicine, Tokyo, Japan; and Department of Preventive Medicine and Public Health, Center for Clinical Research, Keio University School of Medicine, Tokyo, Japan.
• Anesth. Analg. 2015 Jul 1; 121 (1): 81-89.

BackgroundNeutrophil-derived lipocalin-2 exerts bacteriostatic effects through retardation of iron uptake by the Gram-negative organisms like Escherichia coli. We tested the hypothesis that the expression of lipocalin-2, a bacteriostatic protein, was upregulated by induction of surgical site infection (SSI) with E coli in healthy and diseased rats and that epidural anesthesia modulated its expression.MethodsMale Wistar rats were randomized into a healthy or disease group, the latter of which was administered lipopolysaccharide. Both groups were further divided into 3 subgroups, the control, saline, and lidocaine groups: group healthy control (n = 10), healthy saline (n = 10), and healthy lidocaine (n = 10) versus group disease control (n = 15), disease saline (n = 18), and disease lidocaine (n = 19), respectively. While saline was epidurally administered to the control and saline groups, lidocaine was administered to the lidocaine groups. Except for the control groups, E coli was injected to the pseudosurgical site to mimic SSI after abdominal surgery. Plasma concentrations of inflammatory cytokine and lipocalin-2 were measured. At 72 hours, the surgical site tissues were obtained to evaluate mRNA expression of lipocalin-2 and E coli DNA expression.ResultsAll disease subgroups showed markedly increased plasma inflammatory cytokines versus the healthy subgroups. Among the disease subgroups, plasma concentrations of lipocalin-2 and tissue mRNA expression of lipocalin-2 were significantly increased in group disease lidocaine versus the others. Concurrently, E coli DNA expression in the tissue specimens was also significantly lower in group disease lidocaine as compared with group disease saline.ConclusionsEpidural anesthesia was associated with an increase in the expression lipocalin-2 and a decrease in the expression of E coli DNA at pseudosurgical sites in sick but not healthy rats. These observations suggest a potential mechanism by which epidural anesthesia could reduce the risk of SSI.

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