Abstract
IntroductionHigh mobility group box 1 (HMGB1) is a key mediator of inflammation that is actively secreted by macrophages and/or passively released from damaged cells. The proinflammatory role of HMGB1 has been demonstrated in both animal models and humans, since the severity of inflammatory response is strictly related to serum HMGB1 levels in patients suffering from traumatic insult, including operative trauma. This study was undertaken to investigate HMGB1 production kinetics in patients undergoing major elective surgery and to address how circulating mononuclear cells are implicated in this setting. Moreover, we explored the possible relationship between HMGB1 and the proinflammatory cytokine interleukin-6 (IL-6).MethodsForty-seven subjects, American Society of Anesthesiologists physical status I and II, scheduled for major abdominal procedures, were enrolled. After intravenous medication with midazolam (0.025 mg/Kg), all patients received a standard general anesthesia protocol, by thiopentone sodium (5 mg/Kg) and fentanyl (1.4 μg/Kg), plus injected Vecuronium (0.08 mg/Kg). Venous peripheral blood was drawn from patients at three different times, t0: before surgery, t1: immediately after surgical procedure; t2: at 24 hours following intervention. Monocytes were purified by incubation with anti-CD14-coated microbeads, followed by sorting with a magnetic device. Cellular localization of HMGB1 was investigated by flow cytometry assay; HMGB1 release in the serum by Western blot. Serum samples were tested for IL-6 levels by ELISA. A one-way repeated-measures analysis ANOVA was performed to assess differences in HMGB1 concentration over time, in monocytes and serum.ResultsWe show that: a) cellular expression of HMGB1 in monocytes at t1 was significantly higher as compared to t0; b) at t2, a significant increase of HMGB1 levels was found in the sera of patients. Such an increase was concomitant to a significant down-regulation of cellular HMGB1, suggesting that the release of HMGB1 might partially derive from mononuclear cells; c) treatment of monocytes with HMGB1 induced in vitro the release of IL-6; d) at t2, high amounts of circulating IL-6 were detected as compared to t0.ConclusionsThis study demonstrates for the first time that surgical/anesthesia trauma is able to induce an early intracellular upregulation of HMGB1 in monocytes of surgical patients, suggesting that HMGB1 derives, at least partially, from monocytes.
Highlights
High mobility group box 1 (HMGB1) is a key mediator of inflammation that is actively secreted by macrophages and/or passively released from damaged cells
We show that: a) cellular expression of HMGB1 in monocytes at t1 was significantly higher as compared to t0; b) at t2, a significant increase of HMGB1 levels was found in the sera of patients
Such an increase was concomitant to a significant down-regulation of cellular HMGB1, suggesting that the release of HMGB1 might partially derive from mononuclear cells; c) treatment of monocytes with HMGB1 induced in vitro the release of IL-6; d) at t2, high amounts of circulating IL-6 were detected as compared to t0
Summary
High mobility group box 1 (HMGB1) is a key mediator of inflammation that is actively secreted by macrophages and/or passively released from damaged cells. Surgical/anesthesia trauma-induced stress response is mediated by a massive neuro-endocrine-hormonal flux, resulting in activation of intracellular signaling pathways and production of several molecules among which cytokines play a crucial role in regulating the function of activated cells and in preserving body homeostasis [1,2]. The intensity of such an inflammatory response is dependent on many factors, including the magnitude of tissue damage, the patient’s pre-existing diseases, the type of surgery and surgeon’s experience, as well as the anesthesia regimen [3,4]. Drugs employed for inducing and maintaining general anesthesia, such as opioids and muscle relaxants, as well as sevoflurane, exhibited a pro-apoptotic effect on lymphocyte cells by decreasing mitochondrial transmembrane potential or activating extrinsic cell death pathways [5,6]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call