Clinical value of lipopolysaccharide-binding protein (LBP) determinations in acute pancreatitis

Toll-like receptor 4 in pancreatic damage and immune infiltration in acute pancreatitis

Acute pancreatitis is a complex inflammatory disease resulting in extreme pain and can result in significant morbidity and mortality. It can be caused by several factors ranging from genetics, alcohol use, gall stones, and ductal obstruction caused by calcification or neutrophil extracellular traps. Acute pancreatitis is also characterized by immune cell infiltration of neutrophils and M1 macrophages. Toll-like receptor 4 (TLR4) is a pattern recognition receptor that has been noted to respond to endogenous ligands such as high mobility group box 1 (HMGB1) protein and or exogenous ligands such as lipopolysaccharide both of which can be present during the progression of acute pancreatitis. This receptor can be found on a variety of cell types from endothelial cells to resident and infiltrating immune cells leading to production of pro-inflammatory cytokines as well as immune cell activation and maturation resulting in the furthering of pancreatic damage during acute pancreatitis. In this review we will address the various mechanisms mediated by TLR4 in the advancement of acute pancreatitis and how targeting this receptor could lead to improved outcomes for patients suffering from this condition.

Overview and prospect of serum markers for early prediction of severity of acute pancreatitis

Acute pancreatitis (AP) is one of the most common and potentially fatal emergencies of the digestive system. Aseptic inflammation of the pancreas caused by self-digestion of trypsin is considered to be the main pathogenesis of AP. The clinical course and prognosis of AP with different degrees of severity vary greatly, so early prediction of the severity of AP is of great significance to the diagnosis and treatment of this disease. In recent years, great progress has been made in the early risk assessment and severity stratification of AP patients with serum markers. This article gives an overview and discuss the prospects of serum markers for early prediction of the severity of AP.

Chasing a ghost?--Issues with the determination of circulating levels of endotoxin in human blood

Reliable quantification of bacterial products such as endotoxin is important for the diagnosis of Gram-negative infection and for the monitoring of its treatment. Further, it is important to identify patients with persistent subclinical level of bacterial products in their systemic circulation as data from animal studies also suggest this may be correlated with the onset of metabolic syndrome. In this review, we first aim to describe the principles of the Limulus amoebocyte lysate (LAL) test, an assay that is used to quantify endotoxin, and the various shortcomings that must be addressed before it can become a reliable means of quantifying endotoxin in samples derived from blood. We then review published data regarding endotoxin levels in healthy subjects and those with sepsis, inflammatory bowel disease, liver disorders and metabolic disorders such as obesity and diabetes. We also review the evidence regarding influence of macronutrients in augmenting the levels of systemic endotoxin. The results of this review show that reported mean levels of endotoxin in the systemic circulation of healthy humans and of those with various clinical disorders vary over a wide range. Further, this review shows that a significant proportion of this variation can be related to the method that was used to prepare plasma and serum samples prior to assay and its ability to reduce the effect of various blood borne factors that interfere with the LAL assay.

Laboratory markers predicting severity of acute pancreatitis

Acute pancreatitis (AP) is an inflammatory disease of highly variable severity, ranging from mild cases with low mortality to severe cases with high mortality. Numerous biomarkers have been studied as potential early predictors of the severity of this disease so that treatment can be optimally tailored to prevent complications. We aim to present and discuss the most relevant biomarkers for early severity assessment in AP that have been studied to date. We review the current literature on biomarkers that have been used to predict the severity in AP. C-reactive protein (CRP) is still considered to be the gold standard, with a cut-off value of 150 mg/ml 48 h after disease onset. Other markers, including procalcitonin (PCT) and interleukin 6 (IL-6) have been implemented in some hospitals, but are not used on a routine basis. Most other markers, including acute phase proteins (LBP, SAA, PTX3), cytokines (Il-8, TNF-a, MIF), activation peptides of pancreatic proteases (TAP, CAPAP, PLAP), antiproteases (AAT, a2M), adhesion molecules (ICAM-1, selectins, E-cadherin) and leukocyte-derived enzymes (PA2, PMN-E) have shown some promising results but have not been routinely implemented. Furthermore, new and interesting biomarkers (Copeptin, TRX-1, Ang-2, E-2) have shown good results, but more research is needed to determine if they could play a role in the future. Various reasons why new markers for disease severity have not been adopted in daily routine include low accuracy, cumbersome laboratory techniques and high cost. Despite these difficulties, research is still very active in finding new markers to predict the severity of AP.

Predictors of severe and critical acute pancreatitis: a systematic review

BACKGROUND

Persistent organ failure and infected pancreatic necrosis are major determinants of mortality in acute pancreatitis, but there is a gap in the literature assessing the best available predictors of these two determinants. The purpose of this review was to investigate the utility of predictors of persistent organ failure and infected pancreatic necrosis in patients with acute pancreatitis, both alone and in combination.

METHODS

We performed a systematic search of the literature in 3 databases for prospective studies evaluating predictors of persistent organ failure, infected pancreatic necrosis, or both, with strict eligibility criteria.

RESULTS

The best predictors of persistent organ failure were the Japanese Severity Score and Bedside Index of Severity in Acute Pancreatitis when the evaluation was performed within 48h of admission, and blood urea nitrogen and Japanese Severity Score after 48h of admission. Systemic Inflammation Response Syndrome was a poor predictor of persistent organ failure. The best predictor of infected pancreatic necrosis was procalcitonin.

CONCLUSIONS

Based on the best available data, it is justifiable to use blood urea nitrogen for prediction of persistent organ failure after 48h of admission and procalcitonin for prediction of infected pancreatic necrosis in patients with confirmed pancreatic necrosis. There is no predictor of persistent organ failure that can be justifiably used in clinical practice within 48h of admission.

Early angiopoietin-2 levels after onset predict the advent of severe pancreatitis, multiple organ failure, and infectious complications in patients with acute pancreatitis

BACKGROUND

Acute pancreatitis is a severe condition that requires early identification of patients at risk of developing potentially lethal complications. Current clinical scoring systems and biochemical parameters are insufficient. In this study, we aimed to assess whether early plasma Angiopoietin-2 (Ang-2) is associated with adverse outcomes in patients with predicted severe acute pancreatitis (SAP).

STUDY DESIGN

This analysis is a substudy of the PROPATRIA trial (probiotics vs placebo in patients with predicted SAP). The Ang-2 levels were measured prospectively in plasma in the first 5 days after admission in 115 patients.

RESULTS

Early Ang-2 levels were higher in patients who developed SAP: 6.4 vs 3.1 μg/L (p < 0.001) and also were higher in patients who developed multiorgan failure in the first week (p = 0.001) and after the first week (p = 0.049). Furthermore, high Ang-2 levels were associated with infectious complications in the first week (p < 0.001) and after the first week (p < 0.001). Finally, plasma Ang-2 was significantly higher in patients who died (p < 0.001) and in patients who developed bowel ischemia (p < 0.001). As a predictor of adverse outcomes, plasma Ang-2 was superior to a number of current scores, such as the APACHE II score, the Imrie score, C-reactive protein, lipopolysaccharide binding protein, and procalcitonin.

CONCLUSIONS

In the setting of this randomized controlled trial, early plasma Ang-2 was found to be an accurate predictor of SAP, multiorgan failure, and infectious complications. As a biomarker, it did outperform all of the investigated conventional predictors that are currently used in clinical practice.

Lipopolysaccharide binding protein is down-regulated during acute liver failure

BACKGROUND AND AIMS

Lipopolysaccharide binding protein (LBP) is involved in the modulation of acute liver injury and failure caused by acetaminophen (APAP). Although the biological activity of LBP is concentration dependent, little is known about its levels in acute liver failure.

METHODS

Serum and hepatic LBP were measured in acute APAP-induced liver injury in mice. Serum LBP was measured in patients with acute liver failure from APAP and non-APAP causes.

RESULTS

Interestingly, contrary to other diseases, serum and hepatic LBP levels decreased significantly in mice within 24 h after being subjected to APAP-induced injury compared to the control (1.6 ± 0.1 vs. 3.5 ± 1.6 μg/ml, respectively; P < 0.05). Similar decreases were noted in another mouse model of acute liver injury due to carbon tetrachloride. Among patients with acute liver failure due to APAP (n = 5) and non-APAP (n = 5) causes, admission LBP levels were decreased compared to those of healthy controls (5.4 ± 1.4 vs. 3.2 ± 0.2 μg/ml, normal vs. acute liver failure; P = 0.07). However, the levels were not associated with the etiology of acute liver failure or 3-week outcome.

CONCLUSIONS

Serum and hepatic LBP levels are significantly reduced early after the induction of severe acute liver injury/failure due to acetaminophen and other liver injuries. This reduction in LBP production is specific to acute liver failure and may be important in developing future diagnostic and therapeutic approaches for patients with acute liver failure.

Advance in laboratory markers of acute severe pancreatitis

Acute pancreatitis (AP) was one of common acute abdominal diseases in digestive system, and it was divided into mild type and severe type. Many methods were used to judge the severity of AP, including all kinds of scoring system, biochemical indexes, and imaging methods. Recent researches found that some serum indexes such as acute reactive proteins, cytokines, enzymes, active peptides and procalcitonin could classify the severity of AP and judge the risks of complications. This article reviews the progress in the laboratory markers of severe AP.

Lipopolysaccharide binding protein in a surgical intensive care unit: a marker of sepsis?

OBJECTIVES

We investigated the time course of lipopolysaccharide binding protein (LBP) plasma concentrations in patients in the surgical intensive care unit (ICU), their value in discriminating sepsis from systemic inflammatory response syndrome, and their association with severity of sepsis and outcome in these patients compared with interleukin (IL)-6, C-reactive protein, and procalcitonin.

DESIGN

Prospective, observational, cohort study.

SETTING

Academic ICU.

PATIENTS

All 327 consecutively admitted patients.

MEASUREMENTS AND MAIN RESULTS

Serum LBP concentrations were higher in patients who had severe sepsis/septic shock on ICU admission than in patients who never had sepsis (20.5 [8.1-38.8] vs. 14.2 [7.7-22.2] microg/mL, p < .05) but were similar in patients with sepsis without organ failure and those who never had sepsis. After 3 days, LBP levels were similar in all groups. In a receiver operating characteristic curve analysis, LBP concentrations moderately discriminated sepsis from systemic inflammatory response syndrome (area under curve [AUC] = .66) and severe sepsis from sepsis without organ failure (AUC = .71). IL-6 had the highest AUC in discriminating sepsis from other conditions (AUC = .76) and procalcitonin had the highest AUC for discrimination of severe sepsis from sepsis (AUC = .86). LBP concentrations on admission and during the first week were similar in patients with gram-positive and those with gram-negative infections (15.9 [11-26.7] and 37.2 [25.1-62.4] vs. 16.3 [5.3-31.6] and 31.6 [13.4], microg/mL, p > .2). LBP concentrations on admission were similar in nonsurvivors and survivors and did not discriminate ICU mortality. However, the maximum LBP concentration during the first 3 days in the ICU discriminated moderately between survivors and nonsurvivors.

CONCLUSIONS

In the surgical ICU, LBP moderately discriminated patients without infection from patients with severe sepsis but not from patients with sepsis without organ dysfunction. LBP concentrations did not distinguish between gram-positive and gram-negative infections. The correlation of LBP concentrations with disease severity and outcome is weak compared with other markers and its use as a biomarker is not warranted in this patient population.

Interleukin-6 and lipopolysaccharide-binding protein in acute appendicitis in children

The aim of the study was to evaluate the diagnostic accuracy of interleukin-6 (IL-6) and lipopolysaccharide-binding protein (LBP) in children with acute appendicitis (AA) and to compare this with the diagnostic accuracy of routinely used C-reactive protein (CRP) and white blood cell (WBC) count. Eighty-two consecutive children admitted to our Department because of suspected AA were enrolled in this prospective study and classified into two groups: group 1 (49 children who underwent surgery for AA) and group 2 (33 children with no surgery with diagnosis of non-specific abdominal pain or sonographic mesenteric lymphadenitis). There were no negative appendectomies during the time of the study. The patients were further classified into three subgroups: subgroup 1A (43 patients with advanced AA), subgroup 2A (11 patients with mesenteric lymphadenitis) and subgroup 2B (10 patients with non-specific abdominal pain). The perforation rate was 32.7 %. WBC count and serum CRP, IL-6 and LBP were measured on admission. Area under receiver operating characteristic (ROC) curve (AUC), sensitivity, specificity and predictive values were evaluated. Serum IL-6 and LBP were significantly higher in group 1 than in group 2. The highest AUC for AA was that for IL-6 (0.776), followed by WBC count (0.684), CRP (0.637) and LBP (0.635). In conclusion, only IL-6, determined on admission, showed medium diagnostic accuracy, while other laboratory markers showed low diagnostic accuracy for AA in children. The new laboratory markers therefore do not significantly improve the diagnosis of AA.

Pancreatic response to endotoxin after chronic alcohol exposure: switch from apoptosis to necrosis?

Chronic alcohol consumption is known to increase the susceptibility to acute and chronic pancreatitis, and it is likely that a cofactor is required to initiate the progression to alcoholic pancreatitis. The severity and complications of alcoholic and nonalcoholic acute pancreatitis may be influenced by a number of cofactors, including endotoxemia. To explore the effect of a possible cofactor, we used endotoxin [lipopolysaccharide (LPS)] as a tool to induce cellular injury in the alcoholic pancreas. Single, increasing doses of endotoxin were injected in rats fed an alcohol or control diet and killed 24 h after the injection. We examined the mechanism by which LPS exacerbates pancreatic injury in alcohol-fed rats and whether the injury is associated with apoptosis or necrosis. We showed that chronic alcohol exposure alone inhibits apoptosis through the intrinsic pathway and the downstream apoptosis executor caspase-3 compared with the controls. Pancreatic necrosis and inflammation increased after LPS injection in control and alcohol-fed rats in a dose-dependent fashion but with a significantly greater response in the alcohol-fed animals. Caspase activities and TdT-mediated dUTP nick-end labeling positivity were lower in the alcoholic pancreas injected with LPS, whereas the histopathology and inflammation were more severe compared with the control-fed animals. Assessment of a putative indicator of necrosis, the ratio of ADP to ATP, indicated that alcohol exposure accelerates pancreatic necrosis in response to endotoxin. These findings suggest that the pancreas exposed to alcohol is more sensitive to LPS-induced damage because of increased sensitivity to necrotic cell death rather than apoptotic cell death. Similar to the liver, the pancreas is capable of responding to LPS with a more severe response in alcohol-fed animals, favoring pancreatic necrosis rather than apoptosis. We speculate that this mechanism may occur in acute alcoholic pancreatitis patients.