Intramucosal pH and endotoxin and cytokine release in severe acute pancreatitis

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis

Introduction

Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities.

Methods

A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention.

Results

205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease.

Conclusions

AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

Updates in the Management of Perioperative Vasoplegic Syndrome

Vasoplegic syndrome occurs relatively frequently in cardiac surgery, liver transplant, major noncardiac surgery, in post-return of spontaneous circulation situations, and in pateints with sepsis. It is paramount for the anesthesiologist to understand both the pathophysiology of vasoplegia and the different treatment strategies available for rescuing a patient from life-threatening hypotension.

Tryptophan catabolites in mesenteric lymph may contribute to pancreatitis-associated organ failure

Background

Multiple organ failure (MOF) is the key determinant of mortality in acute pancreatitis (AP). Mesenteric lymph cytotoxicity contributes to organ failure in experimental models of systemic inflammation. The aim of this study was to evaluate the mesenteric lymph pathway and the lymph injury proteome in experimental AP-associated MOF, and to test the hypothesis that immunoregulatory tryptophan catabolites contribute to mesenteric lymph cytotoxicity.

Methods

Using an experimental model of AP in rats, the humoral component of mesenteric lymph in AP was compared with that from sham-operated control animals, using in vitro and in vivo cytotoxicity assays, high-throughput proteomics and high-performance liquid chromatography. The experimental findings were corroborated in a cohort of 34 patients with AP.

Results

Compared with biologically inactive lymph from sham-operated rats, mesenteric lymph in AP became cytotoxic 3 h after induction. Hierarchical clustering of lymph proteomic mass spectra predicted the biological behaviour of lymph. Levels of the immunoregulatory tryptophan catabolite, 3-hydroxykynurenine, were increased in cytotoxic lymph and re-created cytotoxicity in vitro. In humans with AP, plasma kynurenine concentrations correlated in real time with MOF scores and preceded a requirement for mechanical ventilation and haemodialysis.

Conclusion

These results support the concept that mesenteric lymph-borne kynurenines may contribute to pancreatitis-associated MOF.

Early gut mucosal dysfunction in patients with acute pancreatitis

OBJECTIVES

A clinical study was made to test the hypothesis that gut mucosal damage happens and correlates with endotoxemia, systemic inflammation, severity of disease, septic complication, and outcome in acute pancreatitis (AP) patients.

METHODS

Patients were divided into 3 groups according to severity: grade 1 (n = 26, mild), grade 2 (n = 18, severe AP [SAP] without organ dysfunction), and grade 3 (n = 18, SAP with organ dysfunction). Twenty healthy volunteers were enrolled as control group. The intestinal lactulose and mannitol absorption ratio, d-xylose absorption, endotoxin, and tumor necrosis factor alpha were detected in parallel to clinical data collection.

RESULTS

Lactulose and mannitol absorption ratio increased in patients with AP, and the increase was more pronounced in SAP (grade 1: 0.044 +/- 0.017, grade 2: 0.39 +/- 0.16, grade 3: 0.48 +/- 0.22, control: 0.024 +/- 0.009; P < 0.01 between control and AP, P < 0.01 between mild and severe group). d-Xylose absorption decreased in pancreatitis groups (P < 0.01) especially in severe groups (P < 0.01 between mild and SAP). We also observed a significant positive correlation of mucosal permeability with endotoxin (r = 0.902, P < 0.001) and tumor necrosis factor alpha changes (r = 0.862, P < 0.001). The severity and septic complication in AP patients were different accompanied with severity of gut mucosal damage.

CONCLUSIONS

Intestinal mucosal function is injured in early phase of AP especially in patients with organ dysfunction, which may be a stimulus for development of multiple organ dysfunction and correlate with bad outcome in AP patients.

Diagnostic criteria and severity assessment of acute cholecystitis: Tokyo Guidelines

This article addresses the criteria for severity assessment and the severity scoring system of the Ministry of Health and Welfare of Japan; now the Japanese Ministry of Health, Labour, and Welfare (the JPN score). It also presents data comparing the JPN score with the Acute Physiology and Chronic Health Evaluation (APACHE) II score and the Ranson score, which are the major measuring scales used in the United States and Europe. The goal of investigating these scoring systems is the achievement of earlier diagnosis and more appropriate and successful treatment of severe or moderate acute pancreatitis, which has a high mortality rate. This article makes the following recommendations in terms of assessing the severity of acute pancreatitis:

(1) Severity assessment is indispensable to the selection of proper initial treatment in the management of acute pancreatitis (Recommendation A).

(2) Assessment by a severity scoring system (JPN score, APACHE II score) is important for determining treatment policy and identifying the need for transfer to a specialist unit (Recommendation A).

(3) C-reactive protein (CRP) is a useful indicator for assessing severity (Recommendation A).

(4) Contrast-enhanced computed tomography (CT) scanning and contrast-enhanced magnetic resonance imaging (MRI) play an important role in severity assessment (Recommendation A).

(5) A JPN score of 2 or more (severe acute pancreatitis) has been established as the criterion for hospital transfer (Recommendation A).

(6) It is preferable to transfer patients with severe acute pancreatitis to a specialist medical institution where they can receive continuous monitoring and systemic management.

Prolonged intestinal mucosal acidosis is associated with multiple organ failure in human acute pancreatitis: Gastric tonometry revisited

AIM: To evaluate whether multiple determinations of intramucosal pH (pHi) in acute pancreatitis (AP) patients could provide additional information of the disease severity during early hospitalization.

METHODS: Twenty-one patients suffering from acute pancreatitis were monitored by gastric tonometry in the first 72 h after hospital admission.

RESULTS: In the survivor group (n = 15) the initially low pHi values returned to normal level (pHi ≥ 7.32) within 48 h (median pHi: d 1: 7.21; d 2: 7.32; d 3: 7.33). In contrast, pHi values in the non-survivor group n = 6) were persistently either below or in the low normal range (median pHi 7.12; 7.12; 7.07 respectively), but pHi differences between the two groups reached significance only after 24 h (P < 0.01). Mucosal acidosis detected at any time during the monitored period was associated with the emergence of single or multiple organ dysfunction (P < 0.01).

CONCLUSION: Prolonged gastric mucosal acidosis was associated with remote organ dysfunction and failure in Acute Pancreatitis, however, correlation with the fatal outcome became significant only 24 h after admission. Due to its non-invasive nature gastric tonometry may supplement the pro-inflammatory markers to achieve a multi-faceted monitoring of the disease.

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Vasodilatory shock in severe acute pancreatitis without sepsis: is there any place for hydrocortisone treatment?

BACKGROUND

Hydrocortisone (HC) has been reported to rapidly improve hemodynamics and reduce the time to vasopressor cessation in septic shock, but none has focused on this effect in acute pancreatitis. We therefore performed a study to assess the effects of hydrocortisone on catecholamine-dependent shock among patients with severe acute pancreatitis.

METHODS

A retrospective, case-controlled study among 10 patients with severe acute pancreatitis and HC treatment for catecholamine-dependent shock was performed. The control group comprised 11 conventionally treated patients with the same severity of pancreatitis and circulatory shock according to the norepinephrine support required. In focus were the first 48 h from the start of HC administration in the HC group and from the reference point in the control group, respectively. The reference point for the control group was the time point at which doses of norepinephrine exceeded 0.3 microg kg(-1) min(-1).

RESULTS

Patients in the HC group were weaned off norepinephrine in a significantly shorter time (61 h in HC group vs. 141 h, P = 0.016). The HC group received significantly less norepinephrine (area under curve of norepinephrine dose, P = 0.041). The reduction in norepinephrine dose was comparable at 24 h, being -0.051 (-0.208-0.022) microg kg(-1) min(-1) in the HC group vs. -0.026 (-0.150-0.030) microg kg(-1) min(-1) in the controls (P = 0.307), and at 48 h with respective figures of -0.206 (-0.317 to -0.102) microg kg(-1) min(-1) and -0.103 (-0.178-0.029) microg kg(-1) min(-1) (P = 0.072), from the start of HC administration.

CONCLUSION

According to our data it seems reasonable to formulate a hypothesis that low doses of HC shorten the time to vasopressor cessation and rapidly reduce the need for norepinephrine support in patients with shock associated with severe acute pancreatitis without sepsis.

Alterations of systemic endotoxemia over the course of acute edematous pancreatitis. correlation to the advent of an infection?

BACKGROUND/AIMS

To define whether bacterial translocation occurs over the course of acute edematous pancreatitis and to correlate its presence to the advent of an infection since data in humans are lacking.

METHODS

Thirty-three patients hospitalized over the period January 2000-January 2001 were subjected to venipuncture at regular time intervals for the collection of blood samples for blood culture and for determination of endotoxins and of C-reactive protein. Endotoxins were measured by the Limulus assay and C-reactive protein by nephelometry.

RESULTS

A wide range of concentrations of endotoxins was observed over the first 3 days of the disease. Mean (+/-SE) of endotoxins was 4.01 +/- 1.36 and 2.42 +/- 0.95 EU/ml 3 and 6 h, respectively, after admission of afebrile patients. Respective values 3 and 6 h after admission of febrile patients were 3.03 +/- 1.14 and 5.84 +/- 2.28 EU/ml (normal <0.1 EU/ml); these values gradually decreased after the second day. No correlation was found between endotoxins and C-reactive protein. Endotoxins were increased as a result of the occurrence of an infection on the third day.

CONCLUSIONS

A significant level of endotoxemia is observed over the course of acute edematous pancreatitis, which might be correlated to the advent of the systemic inflammatory response.

The Severity of Infection Induces a Shift in the Type 1/Type 2 T-Helper Cell Balance in Patients with or without Peritonitis

BACKGROUND

A type-1 to type-2 T-helper cell (Th1/Th2) shift is hypothesized to occur among patients with severe trauma and pancreatitis. It was hypothesized that the Th2 situation caused an immune-suppressed period that led to a critical imbalance in the patients' conditions, with an increased risk of multiple organ failure and mortality.

METHODS

In eight patients with localized intra-abdominal infection (diverticulitis) and six patients with peritonitis due to perforation of a hollow viscus, we examined the cytokine response of CD3(+) T cells in the greater omentum and in the peripheral blood by in vitro stimulation, intracellular cytokine staining, and flow cytometry for TNF-alpha, IFN-gamma, IL-2, and IL-4. Follow-up cytokine assays were carried out on peripheral blood on days 3 and 7. Different levels of cytokine expression in each group were examined to determine the origin of the lymphocytes, both from omentum or peripheral blood. Cytokine production in the diverticulitis group was compared with that of the peritonitis patients.

RESULTS

In localized infections (diverticulitis), there was higher expression of TNF-alpha (51%/35% positive cells in omentum/blood), IFN-gamma (47%/32%), and IL-2 (33%/20%) in the omentum than in the peripheral blood mononuclear cells (PMBCs), but this was not true for IL-4 expression (0.8%/1.3%). In patients with peritonitis, there were no differences in cytokine expression between lymphocytes from the greater omentum and from PMBCs for TNF-alpha (18%/21% omentum/blood), IFN-gamma (20%/22%), IL-2 (16%/12%), or IL-4 (10.9%/7.6%). Compared to the diverticulitis group, patients with peritonitis showed reduced expression for TNF-alpha, IFN-gamma, and IL-2, but there was a significantly higher response for IL-4 for both compartments.

CONCLUSIONS

There was a shift from Th1 to Th2 in patients with severe clinical symptoms of peritonitis. Immune suppression is evident because of the T cell response in the greater omentum, but immunosuppression seems to not reach its maximum level before day 7 post operation. This differs from findings in multiple trauma and pancreatitis; however, it is parallel to the clinical situation in patients with peritonitis.

Gastric mucosal acidosis and cytokine release in patients with septic shock

OBJECTIVE

It has been postulated that in critically ill patients, splanchnic hypoperfusion may lead to cytokine release into the systemic circulation. The presence of cytokines could trigger an inflammatory response and cause multiple organ dysfunction syndrome. Although experimental studies support this hypothesis, humans studies remain controversial. The aim of the study was to determine the relationship between splanchnic hypoperfusion and cytokine release during septic shock.

DESIGN

Human prospective study.

SETTING

Medical intensive care unit at a university hospital.

PATIENTS

A total of 30 patients with mean arterial pressure of <60 mm Hg after volume loading with either oliguria or hyperlactatemia.

MEASUREMENTS

Gastric intramucosal measurements as an indicator of splanchnic hypoperfusion and blood samples were obtained at admission to the medical intensive care unit and repeated during 48 hrs. Cytokine (tumor necrosis factor-alpha and interleukin-6) values were evaluated by enzyme-linked immunoassays at the following periods: at the time of admission and 2, 4, 8, 12, 24, 36, and 48 hrs later.

MAIN RESULTS

High levels of interleukin-6 and tumor necrosis factor-alpha were observed at admission in survivors and nonsurvivors, without significant difference. At 48 hrs, cytokine levels were significantly higher in patients who died compared with the survivors (tumor necrosis factor: 163 +/- 16 for nonsurvivors vs. 34 +/- 9 ng/mL for survivors; interleukin-6: 2814 +/- 485 for nonsurvivors vs. 469 +/- 107 ng/mL for survivors). At 48 hrs, the PCO2 gap was significantly higher in the nonsurvivors compared with survivors (25.87 +/- 2.73 vs. 11.35 +/- 2.25 mm Hg), despite systemic hemodynamic variables in the normal range. A positive relationship was demonstrated between plasma levels of tumor necrosis factor-alpha and interleukin-6 and the PCO2 gap throughout the study. The PCO2 gap was not correlated with hemodynamic variables.

CONCLUSIONS

Our data suggest a relationship between gastric mucosal acidosis, as assessed by PCO2 gap, and cytokine levels in critically ill patients with septic shock. Gut injury may be a contributor of the inflammatory response in patients with septic shock.

Intensive care unit management of intra-abdominal infection

OBJECTIVE

To review the biologic characteristics of, and management approaches to, intra-abdominal infection in the critically ill patient.

DESIGN

Narrative review.

SETTING

Medline review focussed on intra-abdominal infection in the critically ill patient.

PATIENTS AND SUBJECTS

Restricted to studies involving human subjects.

INTERVENTIONS

None.

RESULTS

Intra-abdominal infections are an important cause of morbidity and mortality in the intensive care unit (ICU). Peritonitis can be classified as primary, secondary, or tertiary, the unique pathologic features reflecting the complex nature of the endogenous gut flora and the gut-associated immune system, and the alterations of these that occur in critical illness. Outcome is dependent on timely and accurate diagnosis, vigorous resuscitation and antibiotic support, and decisive implementation of optimal source control measures, specifically the drainage of abscesses and collections of infected fluid, the debridement of necrotic infected tissue, and the use of definitive measures to prevent further contamination and to restore anatomy and function.

CONCLUSIONS

Optimal management of intra-abdominal infection in the critically ill patient is based on the synthesis of evidence, an understanding of biologic principles, and clinical experience. An algorithm outlining a clinical approach to the ICU patient with complex intra-abdominal infection is presented.

In vivo measurement of nitric oxide production in porcine gut, liver and muscle during hyperdynamic endotoxaemia

1. During prolonged endotoxaemia, an increase in arginine catabolism may result in limiting substrate availability for nitric oxide (NO) production. These effects were quantitated in a chronically instrumented porcine endotoxaemia model. 2. Ten days prior to the beginning of the experiments, pigs were catheterized. On day 0, pigs received a continuous infusion of endotoxin (3 microg kg(-1) h(-1)) over 24 h and were saline resuscitated. Blood was drawn from the catheters at 0 and 24 h during primed-infusion of (15)N(2)-arginine and P-aminohippurate to assess (15)N(2)-arginine to (15)N-citrulline conversion and plasma flow rates, respectively, across the portal-drained viscera, liver and hindquarter. 3. During endotoxin infusion a hyperdynamic circulation with elevated heart rate, cardiac index and decreased mean arterial pressure was achieved, characteristic of the human septic condition. 4. Endotoxin induced NO production by the portal-drained viscera and the liver. The increased NO production was quantitatively matched by an increase in arginine disposal. Nitrite/nitrate levels remained unchanged during endotoxaemia. 5. Despite an increased arginine production from the hindquarter and an increased whole-body arginine appearance rate during endotoxin infusion, the plasma arginine concentration was lower in endotoxin-treated animals than in controls. 6 On a whole-body level, the muscle was found to serve as a major arginine supplier and, considering the lowered arginine plasma levels, seems critical in providing arginine as precursor for NO synthesis in the splanchnic region.

L-arginine supplementation in pigs decreases liver protein turnover and increases hindquarter protein turnover both during and after endotoxemia

BACKGROUND

Accumulating evidence suggests that L-arginine, under conditions of septicemia, not only enhances immune function but also improves protein metabolism.

OBJECTIVE

Because the effect of L-arginine administration on the protein metabolism of different organs is unknown, the aim of the study was to elucidate the effects of exogenous supplementation of L-arginine during endotoxemia on the in vivo protein metabolism of individual organs and at the whole-body level.

DESIGN

Female pigs were cannulated with catheters in the aorta and the splenic, caval, portal, hepatic, and renal veins, enabling measurements across the hindquarter, portal-drained viscera, liver, and kidneys. Endotoxemia was induced by a 24-h continuous intravenous infusion of endotoxin (3 microg x kg body wt(-1) x h(-1)). At 8 h, an intravenous infusion of L-arginine was started (n = 8). Control pigs (n = 6) received L-alanine. At 24 h, blood was sampled. After cessation of the endotoxin infusion, L-arginine and L-alanine infusions were continued as a supplement in the enterally infused diet. At 48 h, blood samples were obtained during the postendotoxemic and nutritionally supported conditions. Stable isotopes were used to assess protein metabolism and phenylalanine hydroxylation.

RESULTS

Both during and after the endotoxin challenge, L-arginine administration enhanced protein synthesis and degradation across the hindquarter and simultaneously reduced protein synthesis and degradation in the liver at equal rates. Protein turnover across the kidneys and portal-drained viscera remained unaffected. After endotoxemia, L-arginine infusion decreased whole-body protein turnover without affecting the net protein balance.

CONCLUSION

L-Arginine administration affects protein turnover of the muscle area and the liver oppositely.

Early trauma polymorphonuclear neutrophil responses to chemokines are associated with development of sepsis, pneumonia, and organ failure

OBJECTIVES

The modulation of polymorphonuclear neutrophil (PMN) function by injury is unpredictable, and can predispose either to hyperimmune states (adult respiratory distress syndrome [ARDS], multiple organ failure) or to immune dysfunction, infection, and sepsis. Such outcomes have been related to excess production of the CXC chemokine interleukin (IL)-8, but PMN responses to IL-8 are mediated by both the relatively stable and IL-8 specific CXC receptor 1 (CXCR1) and the labile, promiscuous CXCR2. We hypothesized that progression to septic and multiple organ failure outcomes could be related to early differences in PMN CXC receptor status.

METHODS

PMNs were isolated 12 +/- 3 hours after injury from 15 major trauma patients (Injury Severity Score of 34 +/- 2, 11 men and 4 women, age 36 +/- 4 years) who survived at least 7 days. Volunteer normal PMNs (n = 6 donors) were studied for comparison. Cells were stimulated either with the CXCR2 specific agent growth-related oncogene-alpha, or with IL-8, which stimulates CXCR1 and CXRR2. Receptor response was assessed as the mobilization of cell calcium. The development of ARDS, sepsis, and pneumonia was assessed according to standardized criteria. Day 1 receptor activity in the clinical groups was then compared by analysis of variance with Tukey's or t tests as appropriate.

RESULTS

In patients that were otherwise comparable, CXCR2 responses were markedly diminished in the PMNs of patients who went on to sepsis and pneumonia, but were elevated in PMNs from the patients who went on to ARDS. CXCR1 responses were modestly lower in trauma patients than volunteers, but showed no significant variations among the various clinical outcome groups.

CONCLUSION

The activity of PMN CXCR2 receptors soon after injury may be reflected in the later clinical sequelae of PMN activity. High CXCR2 activity may correlate with PMN hyperfunction and outcomes such as ARDS, whereas the loss of CXCR2 function in inflammatory environments may impair PMN functions in a manner that predisposes to pneumonia or sepsis. Early responses of PMN CXC receptors to injury may influence the clinical course of trauma patients.

The significance of interleukin 8 in urine

AIMS

To assess the implications of detection of interleukin 8 (IL-8) in urine.

METHODS

IL-8 was measured by immunoassay in all 305 urine samples from children aged 0-18.4 years received by our microbiology laboratory during four weeks, with a retrospective structured case note audit for all those in whom IL-8, white cells, or bacteria were detected. Patients were divided into three groups: urinary tract infection (UTI), at least one sample with >/=5 leucocytes x 10(9)/l and >/=10(5) cultured bacteria/ml; possible UTI, at least one sample with >/=5 leucocytes x 10(9)/l or >/=10(5) cultured bacteria/ml but not both; UTI unlikely, sample(s) with <5 leucocytes x 10(9)/l and <10(5) cultured bacteria/ml. Medical records were sought for all in groups 1 (14/14 found) and 2 (18/21 found) and those in group 3 (41/59 found) in whose urine any leucocytes, cultured bacteria, or IL-8 were detected.

RESULTS

IL-8 was detected in 58/305 samples from 48/264 patients. IL-8 was detected in at least one urine sample from 13/14 patients with confirmed UTI (group 1); in 11/21 patients with possible UTI (group 2), of whom two were treated as UTI; and in 23/228 patients without UTI. Using a cut off of 200 pg/ml, urine IL-8 had a sensitivity of 93% and a specificity of 90% for diagnosing UTI.

CONCLUSIONS

Urine IL-8 is a sensitive test for UTI, but is poorly specific as it is also present in a variety of other infectious and inflammatory disorders.