Introduction: Circulating histones have been identified as mediators of damage in animal models of sepsis and in patients with trauma-associated lung injury. Despite existing controversies on actual histone concentrations, clinical implications and mechanism of action in various disease conditions, histone levels in human sepsis, association with disease progression and mediated effects on endothelial and immune cells remain unreported. This study aimed to determine histone levels and its clinical implication in septic patients and to elucidate histone-mediated effects ex-vivo. Methods: Histone levels, endogenous activated protein C (APC) levels and clinical data from two independent cohorts of septic patients were obtained. Histone levels were compared with various control groups including healthy individuals, intensive care unit (ICU) patients without sepsis, ICU patients with multiple organ failure and patients with minor or multiple trauma, all without infection. Endothelial and monocytic cells were stimulated with histones. Cellular integrity and sepsis prototypical cytokines were evaluated. The mechanism of action of histones via Toll-like receptor 4 (TLR4) was evaluated using a function blocking antibody. Histone degradation in plasma was studied by immunoblotting. Results: Histone H4 levels were significantly elevated in patients with sepsis (cohort I; n = 15 and cohort II; n = 19) versus ICU controls (n = 12), patients with multiple organ failure (n = 12) or minor trauma (n = 7), associated with need for renal replacement therapy and decrease in platelet count during disease progression, and remarkably were significantly associated with increased mortality rates in septic patients (ICU-, 28 day- and 90 day mortality rates). There was an inverse correlation between plasma histones and endogenous APC levels. Histone stimulation induced the release of sepsis prototypic cytokines and decreased cell integrity indicated by a significant increase of lactate dehydrogenase (LDH) and propidium iodide (PI) staining. Blocking of TLR4 decreased cellular cytotoxicity on endothelial cells. The calculated half-life of histones in spiked plasma was 4.6 minutes. Conclusions: Histone levels in septic patients are significantly increased and might mediate disease aggravation by cellular injury and inflammation via TLR4 signaling, which potentially results in multiple organ failure and fatal outcome.

Hepatic dysfunction and jaundice are traditionally viewed as late features of sepsis and portend poor outcomes. We hypothesized that changes in liver function occur early in the onset of sepsis, yet pass undetected by standard laboratory tests. In a long-term rat model of faecal peritonitis, biotransformation and hepatobiliary transport were impaired, depending on subsequent disease severity, as early as 6 h after peritoneal contamination. Phosphatidylinositol-3-kinase (PI3K) signalling was simultaneously induced at this time point. At 15 h there was hepatocellular accumulation of bilirubin, bile acids, and xenobiotics, with disturbed bile acid conjugation and drug metabolism. Cholestasis was preceded by disruption of the bile acid and organic anion transport machinery at the canalicular pole. Inhibitors of PI3K partially prevented cytokine-induced loss of villi in cultured HepG2 cells. Notably, mice lacking the PI3Kγ gene were protected against cholestasis and impaired bile acid conjugation. This was partially confirmed by an increase in plasma bile acids (e.g., chenodeoxycholic acid [CDCA] and taurodeoxycholic acid [TDCA]) observed in 48 patients on the day severe sepsis was diagnosed; unlike bilirubin (area under the receiver-operating curve: 0.59), these bile acids predicted 28-d mortality with high sensitivity and specificity (area under the receiver-operating curve: CDCA: 0.77; TDCA: 0.72; CDCA+TDCA: 0.87). Liver dysfunction is an early and commonplace event in the rat model of sepsis studied here; PI3K signalling seems to play a crucial role. All aspects of hepatic biotransformation are affected, with severity relating to subsequent prognosis. Detected changes significantly precede conventional markers and are reflected by early alterations in plasma bile acids. These observations carry important implications for the diagnosis of liver dysfunction and pharmacotherapy in the critically ill. Further clinical work is necessary to extend these concepts into clinical practice. Please see later in the article for the Editors' Summary Sepsis (blood poisoning)—a life-threatening condition caused by an inappropriate immune response to an infection—is a major global cause of death. Normally, when bacteria or other microbes enter the human body, the immune system efficiently destroys the invaders. In sepsis the immune system goes into overdrive, and the chemicals it releases into the blood to combat the infection trigger widespread inflammation (swelling). This leads to the formation of small blood clots and leaky blood vessels that block the flow of blood to vital organs such as the kidneys and liver. In the most severe cases, multiple organs fail and the patient dies. Anyone can get sepsis, but people with weakened immune systems, the very young, and the elderly are most vulnerable. Symptoms of sepsis include fever, chills, rapid breathing, a fast heart rate, and confusion. In its early stages, sepsis can be treated with antibiotics alone, but people with severe sepsis need to be admitted to an intensive care unit where the vital organs can be supported while the infection is treated. Thirty to fifty percent of people who develop severe sepsis die. If sepsis could be diagnosed in its early stages, it might be possible to save more people. Unfortunately, the symptoms of sepsis mimic those of other conditions, and, because sepsis tends to develop very quickly, it is often not diagnosed until it is too late to save the patient's life. The development of liver (hepatic) dysfunction and jaundice are both regarded as late features of sepsis (jaundice is yellowing of the skin and eyes caused by a build-up of bilirubin in the blood). However, the researchers hypothesized that changes in liver function occur early in sepsis and could, therefore, be used to improve the diagnosis and management of sepsis. The researchers induced sepsis in rats by injecting bacteria into the peritoneal cavity (the gap between the abdominal wall and the abdominal organs), separated the infected animals into predicted survivors and non-survivors based on their heart stroke volume measured using cardiac ultrasound, and then examined their liver function. The expression of genes encoding proteins involved in “biotransformation” and “hepatobiliary transport” (the processes that convert waste products and toxic chemicals into substances that can be conjugated to increase solubility and then excreted) was down-regulated within six hours of sepsis induction in the predicted non-survivors compared to the predicted survivors. Functional changes such as bilirubin and bile acid accumulation in the liver (cholestasis), poor excretion of xenobiotics (molecules not usually found in the body such as antibiotics), and disturbed bile acid conjugation were also seen in predicted non-survivors but not in survivors. Moreover, phosphatidylinositol-3-kinase (PI3K) signaling (which is involved in several immune processes) increased soon after sepsis induction in non-survivor but not in survivor animals. Notably, mice lacking the PI3Kγ gene did not develop cholestasis or show impaired bile acid conjugation after induction of sepsis. Finally, in human patients, plasma bile acids were increased in 48 patients on the day that severe sepsis was diagnosed, and these increases accurately predicted death in these patients. These findings show that liver dysfunction is an early event in animal models of sepsis and that PI3K signalling plays a crucial role in the development of liver dysfunction. They show that all aspects of liver biotransformation are affected during sepsis and suggest that outcomes are related to the severity of these changes. The limited clinical data included in this study also support the hypothesis that changes in liver function occur early in sepsis, although these data need confirming and extending. Taken together, these findings suggest that liver function tests might aid early diagnosis of sepsis and might also provide information about likely outcomes. They also have important implications for the use of drugs in patients who are critically ill with sepsis, in that some of the drugs routinely administered to such patients may not be adequately detoxified and may, therefore, contribute to organ injury. Finally, these findings suggest that inhibition of PI3Kγ may alleviate sepsis-associated cholestasis. Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001338.

Introduction: Systemic inflammatory response syndrome is common after surgery, and it can be difficult to discriminate between infection and inflammation. We performed a review of the literature with the aims of describing the evolution of serum procalcitonin (PCT) levels after uncomplicated cardiac surgery, characterising the role of PCT as a tool in discriminating infection, identifying the relation between PCT, organ failure, and severity of sepsis syndromes, and assessing the possible role of PCT in detection of postoperative complications and mortality. Methods: We performed a search on MEDLINE using the keyword 'procalcitonin' crossed with 'cardiac surgery,' 'heart,' 'postoperative,' and 'transplantation.' Our search was limited to human studies published between January 1990 and June 2006. Results: Uncomplicated cardiac surgery induces a postoperative increase in serum PCT levels. Peak PCT levels are reached within 24 hours postoperatively and return to normal levels within the first week. This increase seems to be dependent on the surgical procedure and on intraoperative events. Although PCT values reported in infected patients are generally higher than in non-infected patients after cardiac surgery, the cutoff point for discriminating infection ranges from 1 to 5 ng/ml, and the dynamics of PCT levels over time may be more important than absolute values. PCT is superior to C-reactive protein in discriminating infections in this setting. PCT levels are higher with increased severity of sepsis and the presence of organ dysfunction/failure and in patients with a poor outcome or in those who develop postoperative complications. PCT levels typically remain unchanged after acute rejection but increase markedly after bacterial and fungal infections. Systemic infections are associated with greater PCT elevation than is local infection. Viral infections are difficult to identify based on PCT measurements. Conclusion: The dynamics of PCT levels, rather than absolute values, could be important in identifying patients with infectious complications after cardiac surgery. PCT is useful in differentiating acute graft rejection after heart and/or lung transplantation from bacterial and fungal infections. Further studies are needed to define cutoff points and to incorporate PCT levels in useful prediction models.

Background: The aim of extracorporeal albumin dialysis (ECAD) is to reduce endogenous toxins accumulating in liver failure. To date, ECAD is conducted mainly with the Molecular Adsorbents Recirculating System (MARS). However, single-pass albumin dialysis (SPAD) has been proposed as an alternative. The aim of this study was to compare the two devices with a prospective, single-centre, non-inferiority crossover study design with particular focus on reduction of bilirubin levels (primary endpoint) and influence on paraclinical and clinical parameters (secondary endpoints) associated with liver failure.Methods: Patients presenting with liver failure were screened for eligibility and after inclusion were randomly assigned to be started on either conventional MARS or SPAD (with 4 % albumin and a dialysis flow rate of 700 ml/h). Statistical analyses were based on a linear mixed-effects model.Results: Sixty-nine crossover cycles of ECAD in 32 patients were completed. Both systems significantly reduced plasma bilirubin levels to a similar extent (MARS: median −68 μmol/L, interquartile range [IQR] −107.5 to −33.5,p = 0.001; SPAD: −59 μmol/L, −84.5 to +36.5,p = 0.001). However, bile acids (MARS: −39 μmol/L, −105.6 to −8.3,p < 0.001; SPAD: −9 μmol/L, −36.9 to +11.4,p = 0.131), creatinine (MARS: −24 μmol/L, −46.5 to −8.0,p < 0.001; SPAD: −2 μmol/L, −9.0 to +7.0/L,p = 0.314) and urea (MARS: −0.9 mmol/L, −1.93 to −0.10,p = 0.024; SPAD: −0.1 mmol/L, −1.0 to +0.68,p = 0.523) were reduced and albumin-binding capacity was increased (MARS: +10 %, −0.8 to +20.9 %,p < 0.001; SPAD: +7 %, −7.5 to +15.5 %,p = 0.137) only by MARS. Cytokine levels of interleukin (IL)-6 and IL-8 and hepatic encephalopathy were altered by neither MARS nor SPAD.Conclusions: Both procedures were safe for temporary extracorporeal liver support. While in clinical practice routinely assessed plasma bilirubin levels were reduced by both systems, only MARS affected other paraclinical parameters (i.e., serum bile acids, albumin-binding capacity, and creatinine and urea levels). Caution should be taken with regard to metabolic derangements and electrolyte disturbances, particularly in SPAD using regional citrate anti-coagulation.Trial registration: German Clinical Trials Register (www.drks.de)DRKS00000371. Registered 8 April 2010.