Phospholipase A2 activity and concentration in several body fluids in patients with acute pancreatitis

Usefulness of early-phase peritoneal lavage for treating severe acute pancreatitis

OBJECTIVE

To improve the prognosis of severe acute pancreatitis, preventing infectious complications, particularly infected pancreatic necrosis, is important. The present study evaluated the efficacy of peritoneal lavage for improving the prognosis of patients with severe acute pancreatitis.

PATIENTS

We retrospectively reviewed the cases of 23 consecutive patients with severe acute pancreatitis who were treated with peritoneal lavage.

RESULTS

Peritoneal lavage was started within 72 hours after the initial onset of symptoms in 20 patients (87%). The duration of peritoneal lavage, which was significantly correlated with the number of prognostic factors according to the revised Japanese criteria, Ranson score and serum C-reactive protein level at the start of peritoneal lavage, was a median of seven (3-22) days. There were no adverse events associated with the peritoneal lavage. Eight patients (35%) concurrently underwent continuous regional arterial infusion. Five days after starting peritoneal lavage, the patients' clinical conditions significantly improved. Overall, the survival rate was 96%. One patient (4%) died due to rupture of a pseudoaneurysm of the splenic artery. Complications occurred in seven patients (30%). Infectious complications were observed in three patients (13%) (one patient developed infected pancreatic necrosis and bacteremia, and two patients developed bacteremia). Pseudocysts and pancreatic fistulas developed in five and one patient, respectively. The incidence of complications was lower in the patients receiving peritoneal lavage within 72 hours from the initial onset of symptoms than in the remaining patients (20% vs. 100%; p=0.005).

CONCLUSION

We speculate that peritoneal lavage reduces the mortality and incidence of complications in patients with severe acute pancreatitis.

Route and type of nutrition and surgical stress influence secretory phospholipase A2 secretion of the murine small intestine

BACKGROUND

The function of secretory phospholipase A2 (sPLA2) is site dependent. In tissue, sPLA2 regulates eicosanoid production; in circulation, sPLA2 primes neutrophils; and in the intestinal lumen, sPLA2 provides innate bactericidal immunity as a defensin-related protein. Since parenteral nutrition (PN) primes leukocytes while suppressing intraluminal mucosal immunity, the authors hypothesized that (1) PN would diminish luminal sPLA2 activity but increase activity in intestinal tissue and serum and (2) stress would accentuate these changes.

METHODS

Mice received chow, a complex enteral diet (CED), intragastric PN (IG-PN), or PN in experiment 1 and chow, chow+stress, PN, or PN+stress in experiment 2.

RESULTS

In experiment 1, luminal sPLA2 activity was greatest in chow and decreased in CED, IG-PN, and PN, with PN lower than CED and IG-PN. Compared to that after chow, serum sPLA2 activity dropped after CED, IG-PN, and PN. Serum sPLA2 was higher in portal than systemic serum. In experiment 2, PN lowered luminal sPLA2 activity vs chow. Stress lowered luminal sPLA2 activity in chow, without change in PN. Following stress, luminal immunoglobulin A increased in chow but not PN. Serum sPLA2 activity increased in PN.

CONCLUSIONS

PN attenuates sPLA2 activity in intestinal fluid, consistent with suppressed innate mucosal defense. Stress suppresses luminal fluid sPLA2 activity in chow but not the immunoglobulin A response; PN impairs both. Stress significantly elevates serum sPLA2 in PN-fed mice, consistent with known increased neutrophil priming with PN. PN reduces innate bactericidal immunity of the gut but upregulates serum proinflammatory products poststress.

Role of secretory phospholipase a(2) in CNS inflammation: implications in traumatic spinal cord injury

Secretory phospholipases A(2) (sPLA(2)s) are a subfamily of lipolytic enzymes which hydrolyze the acyl bond at the sn-2 position of glycerophospholipids to produce free fatty acids and lysophospholipids. These products are precursors of bioactive eicosanoids and platelet-activating factor (PAF). The hydrolysis of membrane phospholipids by PLA(2) is a rate-limiting step for generation of eicosanoids and PAF. To date, more than 10 isozymes of sPLA(2) have been found in the mammalian central nervous system (CNS). Under physiological conditions, sPLA(2)s are involved in diverse cellular responses, including host defense, phospholipid digestion and metabolism. However, under pathological situations, increased sPLA(2) activity and excessive production of free fatty acids and their metabolites may lead to inflammation, loss of membrane integrity, oxidative stress, and subsequent tissue injury. Emerging evidence suggests that sPLA(2) plays a role in the secondary injury process after traumatic or ischemic injuries in the brain and spinal cord. Importantly, sPLA(2) may act as a convergence molecule that mediates multiple key mechanisms involved in the secondary injury since it can be induced by multiple toxic factors such as inflammatory cytokines, free radicals, and excitatory amino acids, and its activation and metabolites can exacerbate the secondary injury. Blocking sPLA(2) action may represent a novel and efficient strategy to block multiple injury pathways associated with the CNS secondary injury. This review outlines the current knowledge of sPLA(2) in the CNS with emphasis placed on the possible roles of sPLA(2) in mediating CNS injuries, particularly the traumatic and ischemic injuries in the brain and spinal cord.

The pathogenic mechanism of severe acute pancreatitis complicated with renal injury: a review of current knowledge

The onset of severe acute pancreatitis (SAP) is clinically harmful as it may rapidly progress from a local pancreatic inflammation into proemial systemic inflammatory reactions. Patients with SAP have a high mortality, with most cases of death resulting from complications involving the failure of organs other than the pancreas. The distinctive feature of SAP is that once it starts, it may aggrevate the clinical condition of the patient continuously, so that the levels of injury to the other organs surpass the severity of the pancreatic lesion, even causing multiple organ failure and, ultimately, death. In clinical practice, the main complications in terms of organ dysfunctions are shock, acute respiratory failure, acute renal failure, among others. The acute renal injury caused by SAP is not only able to aggravate the state of pancreatitis, but it also develops into renal failure and elevates patients' mortality. Studies have found that the injury due to massive inflammatory mediators, microcirculation changes and apoptosis, among others, may play important roles in the pathogenic mechanism of acute renal injury.

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Secreted phospholipases A2 induce the expression of chemokines in microvascular endothelium

Acute respiratory distress syndrome (ARDS) is characterized by alterations in microvascular permeability. In ARDS secreted phospholipase A(2) (sPLA(2)) IB and IIA are found to be highly upregulated. In this study, we therefore investigated the influence of exogenously added sPLA(2)-IB and sPLA(2)-IIA on the production of chemokines and adhesion molecules in lung microvascular endothelial cells (LMVEC). Treatment of LMVEC with sPLA(2)s resulted in a significant increase in the production of chemokines and adhesion molecules due to an increased expression of their mRNA and in an enhanced release of oleic acid. The upregulation of chemokines and adhesion molecules by LPS was stronger in the presence of sPLA(2). Activation of NF-kappaB occurred upon stimulation with sPLA(2). Moreover the MAPkinase pERK seems to be involved since a specific pERK inhibitor, e.g., U0126, but not a p38Kinase inhibitor, e.g., SB203580 prevented sPLA(2)-induced chemokine upregulation. Our data therefore suggest that LMVEC are a highly sensitive target for the direct action of extracellular sPLA(2)s.

Roles of secretory phospholipases A(2) in inflammatory diseases and trauma

Six distinct secretory small molecular weight phospholipases A(2) (PLA(2)) have been cloned and characterized from human tissues. Two of them, pancreatic group IB PLA(2) (PLA(2)-IB) and synovial-type group IIA PLA(2) (PLA(2)-IIA) have been studied as to their association to various inflammatory diseases. PLA(2)-IB is a digestive enzyme synthesized by pancreatic acinar cells. In acute pancreatitis, which is characterized by destruction of pancreatic tissue, PLA(2)-IB is released into the circulation, but its role in pancreatic and other tissue damage is still hypothetical. The concentration of PLA(2)-IIA increases in blood plasma in generalized inflammatory response resulting from infections, chronic inflammatory diseases, acute pancreatitis, trauma and surgical operations. PLA(2)-IIA is synthesized in a number of gland cells and is present in cellular secretions on mucosal surfaces including Paneth cells of intestinal mucosa, prostatic gland cells and seminal plasma, and lacrimal glands and tears. PLA(2)-IIA is expressed in hepatoma-derived cells in vitro and hepatocytes in vivo. PLA(2)-IIA is regarded as an acute phase protein and seems to function as an antibacterial agent especially effective against Gram-positive bacteria. Other putative functions in the inflammatory reaction include hydrolysis of cell membrane phospholipids and release of arachidonic acid for prostanoid synthesis.

Isolation of human intestinal defensins from ileal neobladder urine

We describe the isolation of naturally occurring human intestinal defensins HD-5 and HD-6 from ileal neobladder urine and ileal mucosa. Using an antibody-based detection assay, we found multiple N-terminally processed forms of HD-5. The predominant HD-5 forms in tissue were longer than those in neobladder urine (amino acid (aa) 23-94 and 29-94 versus aa 36-94, 56-94 and 63-94) suggesting that Paneth cells store prodefensin that is processed to mature defensin during or after degranulation. Search for mature HD-6 yielded aa 69-100 as the predominant form in both sources. The ileal neobladder is a promising model to study human Paneth cell secretion.

What is the best biochemical test to diagnose acute pancreatitis? A prospective clinical study

OBJECTIVE

To determine which biochemical test is best to distinguish acute pancreatitis from other pancreatic and nonpancreatic diseases associated with hyperamylasemia.

DESIGN

We conducted a prospective clinical study of 836 consecutive patients who had a total serum amylase test requested by a physician during a 7-month period.

MATERIAL AND METHODS

Radioimmunoassay and enzymatic activity methods were used to measure pancreas-specific proteins of varied size, charge, and stability. In addition, scoring systems were used for the diagnosis of pancreatitis, and statistical analyses were done to determine sensitivity and specificity.

RESULTS

We found minor differences in sensitivity and specificity for diagnosis of acute pancreatitis among pancreatic isoamylase, phospholipase A2, colipase, lipase, and carboxylester lipase. Of these tests, the combination of isoamylase and phospholipase A2 had a small but statistically significant increased sensitivity (90%; 95% confidence interval [CI] = 74 to 98%) and specificity (93%; 95% CI = 91 to 95%) over isoamylase (90% and 92%, respectively; 95% CI = 90 to 94%) and phospholipase A2 (90% and 75%, respectively; 95% CI = 72 to 78%) alone for the diagnosis of acute pancreatitis.

CONCLUSION

Pancreas-specific proteins are satisfactory for diagnosing acute pancreatitis if the test is validated by the laboratory. Clinically, the slight advantage of using both isoamylase and phospholipase A2 does not outweigh the expense of performing two assays; we recommend using isoamylase to diagnose acute pancreatitis.

In vitro evaluation of polymerized liposomes as an oral drug delivery system

The physical characteristics of polymerized liposomes for potential use as an oral drug delivery system were examined in vitro. The trap efficiency in monomeric liposomes composed of 1,2-di (2,4-octadecadienoyl) phosphatidylcholine was increased from 3% for original multilamellar vesicles to 35% for freeze-thaw treated liposomes. Polymerized liposomes with azobis (isobutyronitrile) and azobis (2-amidinopropane) hydrochloride as radical initiators showed complete stability against solubilization by Triton X-100, a detergent chosen to mimic bile salts. Release rates of 14C-BSA and 14C-sucrose in media simulating the gastro-intestinal fluids was 50% less than from regular liposomes composed of hydrogenated egg phosphatidylcholine mixed with cholesterol (molar ratio 1:1), which can be regarded as one of the most stable types of regular liposomes. It was estimated that, when administered orally, polymerized liposomes can reach the intestine while maintaining their vesicle structure and keeping at least 75% of their original content.

Elevated PLA2 activity in schizophrenics and other psychiatric patients

We measured serum phospholipase A2 (PLA2) activity in 39 schizophrenics, 26 psychiatric controls, and 26 normal controls using a radioenzymatic assay with phosphatidylcholine as precursor. Serum PLA2 activity was significantly higher in schizophrenics (p = 0.002) and other psychiatric (including substance abusing) patients (p = 0.032) than in normal controls. Enzyme activity did not differ between the schizophrenic patients and psychiatric controls. Fifty-one percent of the schizophrenics and 46% of psychiatric controls had PLA2 values above the highest value for normal controls. In the psychiatric control group higher than normal PLA2 activities were observed in all diagnostic categories, including major depression, bipolar disorder, posttraumatic stress disorder (PTSD), and substance abuse. In the context of others' findings of increased circulating PLA2 in infectious and inflammatory conditions, these increases must be viewed as disease nonspecific. The significance of these changes and their relationship to other acute-phase protein changes needs to be clarified in future research.

[Severe acute pancreatitis: diagnostic approaches and therapeutic implications]

Diagnosis of acute pancreatitis (AP) can be obtained with a high level of accuracy by clinical assessment and determination of common laboratory parameters such as serum amylase and lipase concentrations. However, the key of an optimal management of patients with AP is based on an early discrimination between interstitial oedematous and necrotizing forms. The former resolves spontaneously whereas parenchymal necrosis acting as a focus for bacteria has a very high severity. In this respect, multifactor prognostic scoring systems and new biological assessments like C reactive protein are valuable methods for forecasting the prognosis of AP. However, these indicators of severity require a full 48 hour period of observation. In order to overcome these drawbacks, other prognostic criteria have been explored based mainly, on laboratory data. The most interesting ones are trypsinogen activation peptides and leucocyte elastase. Finally, the more useful tool is computed tomography (CT). Combined with high dose intravenous contrast agent, it allows an early identification of necrosis. Other goals of computed tomography are an accurate diagnosis of infection by guided needle aspirations and a preoperative recognition of devitalized and infected tissues, which require a careful surgical necrosectomy. A prolonged drainage is always recommended but relative merits of a conventional closed drainage and an open one are controversial. Another therapeutic challenge is gallstone associated to severe pancreatitis. An early stone removal is advocated by some authors but others prefer delayed surgery because of high mortality rates in case of emergency surgery. Delayed surgery until biological parameters of pancreatitis are normalized seems preferable. An early endoscopic sphincterotomy in an attractive alternative method.