Kinetics of interleukin-11 release after cardiopulmonary bypass

Analysis of systemic interleukin-11 after major trauma

Recent data have shown that anti-inflammatory responses to major injury occur immediately after trauma. Interleukin 11 (IL-11), a member of the IL-6 family, is a pleiotropic cytokine with hematopoietic, osteotrophic, and mucosa protective properties, as well as anti-inflammatory functions. IL-11 inhibits synthesis of proinflammatory cytokines, promotes a Th2-type immune response, and improves outcome after shock and sepsis in different animal models. To further investigate the role of IL-11 in the human posttraumatic immune response, we measured plasma levels of IL-11 in 216 multiple-injured patients (mean age of 40 +/- 16 [range 11-81] years; Injury Severity Score [ISS] of 31 +/- 11 [range 16-66] points; 52 women and 164 men) after injury and correlated this with demographics, clinical course, and other laboratory parameters. IL-11 was significantly elevated in polytraumatized patients compared with healthy donors (P <0.0001). The time course of IL-11 in surviving patients was an initial increase after trauma with a decrease during the first 4 weeks, whereas nonsurvivors (n=34) had a significant increase later after injury (4 weeks). IL-11 was significantly higher after abdominal trauma and in men. No correlation between systemic IL-11 and ISS or age was detected. IL-11 correlated significantly with other pro- and anti-inflammatory cytokines such as IL-18. Our data demonstrate elevated levels of systemic IL-11 after multiple injuries; however, the role of a posttraumatic increase of IL-11 has to be further analyzed. In contrast to IL-6, IL-11 in plasma does not correlate with trauma severity and seems to have no clinical relevance to outcome prediction after trauma.

Role of TNF in mediating renal insufficiency following cardiac surgery: evidence of a postbypass cardiorenal syndrome

Recent evidence has implicated proinflammatory mediators such as TNF-alpha in the pathophysiology of ischemia-reperfusion (I/R) injury. Clinically, serum levels of TNF-alpha are increased after myocardial infarction and after cardiopulmonary bypass. Both cardiopulmonary bypass and renal ischemia-reperfusion injury induce a cascade of events leading to cellular damage and organ dysfunction. Tumor necrosis factor (TNF), a potent proinflammatory cytokine, is released from both the heart and the kidney in response to ischemia and reperfusion. TNF released during cardiopulmonary bypass induces glomerular fibrin deposition, cellular infiltration, and vasoconstriction, leading to a reduction in glomerular filtration rate (GFR). The signaling cascade through which renal ischemia-reperfusion induces TNF production is beginning to be elucidated. Oxidants released following reperfusion activate p38 mitogen-activated protein kinase (p38 MAP kinase) and the TNF transcription factor, NFkappaB, leading to subsequent TNF synthesis. In a positive feedback, proinflammatory fashion, binding of TNF to specific TNF membrane receptors can reactivate NFkappaB. This provides a mechanism by which TNF can upregulate its own expression as well as facilitate the expression of other genes pivotal to the inflammatory response. Following its production and release, TNF results in both renal and myocardial apoptosis and dysfunction. An understanding of these mechanisms may allow the adjuvant use of anti-TNF therapeutic strategies in the treatment of renal injury. The purposes of this review are: (1) to evaluate the evidence which indicates that TNF is produced by the heart following cardiopulmonary bypass; (2) to examine the effect of TNF on myocardial performance; (3) to outline the mechanisms by which the kidney produces significant TNF in response to ischemia and reperfusion; (5) to investigate the role of TNF in renal ischemia-reperfusion injury, (6) to describe the mechanisms of TNF-induced renal cell apoptosis, and (7) to suggest potential anti-TNF strategies designed to reduce renal insufficiency following cardiac surgery.