Åke Lasson

The effect of intestinal ischemia and reperfusion injury on ICAM-1 expression, endothelial barrier function, neutrophil tissue influx, and protease inhibitor levels in rats.

Multiple organ dysfunction syndrome (MODS) is mediated by complex mechanisms in which interactions between activated leukocytes and endothelial cells play a central role. ICAM-1 (intercellular adhesion molecule-1) mediates firm adhesion and transendothelial migration of activated leukocytes from postcapillary venules into the tissue. The present study evaluated the ICAM-1 expression in various organs after 40 min of intestinal ischemia and 1, 3, 6, 12 h of reperfusion (I/R) in the rat, using a dual monoclonal antibody technique (n = 36). Endothelial barrier permeability, using the vascular leakage of radiolabeled human serum albumin was also assessed (n = 12). Neutrophil sequestration in the lungs was quantitated by myeloperoxidase activity and plasma protease inhibitor levels were measured with electroimmunoassay. Significant regional differences were found in ICAM-1 expression between organs, both constitutively and after I/R-injury. The highest constitutive levels were observed in the liver and lungs, followed by the kidneys. The constitutive ICAM-1 expression in the intestines and in the heart was about 1/20 compared with that found in the liver and lungs. The brain and muscle had levels of about 1/150 of that in the liver and lungs. After intestinal I/R, significant increases (17–45%) were found in the lungs, intestines, brain, heart, and muscle. Albumin leakage index (ALI) in all examined organs and myeloperoxidase activity in the lungs increased after I/R-injury. Serum levels of albumin and most protease inhibitors decreased significantly after I/R challenge. Intestinal I/R results in an increase of systemic ICAM-1 expression with marked organ variability. The upregulation of ICAM-1 could represent a crucial step in the adherence- and migration process of activated leukocytes and potentially in the development of tissue injury.

The influence of intestinal ischemia and reperfusion on bidirectional intestinal barrier permeability, cellular membrane integrity, proteinase inhibitors, and cell death in rats.

Intestinal ischemia and reperfusion injury (I/R) is probably involved in the pathogenesis of intestinal barrier dysfunction, associated with the concomitant translocation of enteric bacteria and toxins and the potential development of multiple organ failure. The intestinal endothelial and epithelial layers play a major role preventing the entry of toxic substances from the gut, but the influence of protease-antiprotease systemic balance on these barrier functions and the relationship between epithelial DNA synthesis, apoptosis, and endothelial and epithelial barrier macromolecule permeability are not fully investigated. Endothelial and epithelial barrier macromolecular permeability, epithelial DNA synthesis, the endothelial and epithelial plasma membrane system, apoptosis and oncosis, plasma levels of proteinase inhibitors, and proenzymes were measured in rats subjected to 20 and 40 min intestinal ischemia and 1, 3, 6, or 12 h reperfusion. Endothelial permeability increased after both 20 and 40 min intestinal ischemia. Epithelial permeability significantly increased during 1-6 h reperfusion after 20 min ischemia and during 1-12 h reperfusion after 40 min ischemia. Epithelial DNA synthesis increased in animals with 20 min ischemia followed by 12 h reperfusion. Plasma levels of prekallikrein, C1-esterase inhibitor, and alpha1-macroglobulin were significantly lower following both 20 and 40 min ischemia from 3 h reperfusion and on. Apoptotic epithelial cells significantly increased in animals subjected to 20 min ischemia followed by 12 h reperfusion. The severity of reperfusion injury in the intestinal endothelial and epithelial barrier seems to correlate with the period of ischemia and the pathway of cell damage and death, together with proteinase-antiproteinase imbalance.

Protease Inhibitors in Acute Human Pancreatitis: Correlation between Biochemical Changes and Clinical Course

A clinical and biochemical analysis of 27 attacks of acute pancreatitis was made throughout the course of the disease. In severe attacks alpha 2-macroglobulin (alpha 2-M) decreased during the first days, reaching values in blood below 40% of the normal value. In addition, this remaining alpha 2-M had a decreased trypsin-binding capacity, indicating circulating alpha 2-M protease complexes. The inter-alpha-trypsin inhibitor concentration was also decreased, whereas alpha 1-proteinase inhibitor, antichymotrypsin, and pancreatic secretory trypsin inhibitor increased. All changes were most pronounced in the peritoneal fluid and were also closely correlated to the severity of the disease, assessed by both Ransons and McMahons classification systems. All patients with clinical complications had profound biochemical changes. In accordance with earlier findings, activation of both the complement and kinin systems seems possible in both blood and peritoneal fluid at the low alpha 2-M concentrations found in severe attacks.

Consumptive coagulopathy, fibrinolysis and protease-antiprotease interactions during acute human pancreatitis

Twenty-seven attacks of acute human pancreatitis of different severity were analysed concerning clinical outcome and activation of the coagulation and fibrinolytic systems. Consumptive coagulopathy was suggested by decreased platelet counts, decreased prothrombin values and consumption of fibrinogen during the first days in severe attacks. Factor X was slightly decreased the first 5 days in all attacks. Increased fibrinolysis was suggested by decreased plasminogen values in severe attacks. Fibrinogen degradation products were seen in 40% of the patients in blood and in 100% of the patients in the peritoneal fluid. The four main protease inhibitors of the two systems all showed protease-antiprotease complexation and lower functional than quantitative values. Plasma levels of antithrombin III and alpha 2-macroglobulin were low, while the levels of C1-inhibitor and alpha 2-antiplasmin were high. Functional levels of all the four protease inhibitors were almost zero in the peritoneal fluid in severe attacks. It is concluded that severe acute pancreatitis results in both consumptive coagulopathy and in increased fibrinolysis. A local antiprotease deficiency is seen in the peritoneal cavity and high levels of protease-antiprotease complexes are also seen in plasma. All these changes are closely correlated to the severity of the disease and may probably determine the clinical outcome of the acute attack.

Effects of inhibition of PAF, ICAM-1, and PECAM-1 on gut barrier failure caused by intestinal ischemia and reperfusion.

Background: The role of cell adhesion molecules and transmigration of PMNs through the endothelial barrier is probably essential in intestinal ischemia and reperfusion (I/R)-induced gut barrier dysfunction. Although cytokines are released in I/R, it is unclear whether cytokines directly increase permeability or if this phenomenon requires both expression of cell adhesion molecules and PMN adhesion-activation. Endothelial barrier dysfunction plays an important role in the pathogenesis of multiple organ dysfunction syndrome, inducing gut barrier failure, but the mechanisms are not fully understood. The purpose of this study was to evaluate the potential therapeutic value of inhibition of platelet activating factor (PAF), intercellular adhesion molecule-1 (ICAM-1), and platelet endothelial cell adhesion molecule-1 (PECAM1) in gut barrier dysfunction induced by intestinal I/R. Methods:BACKGROUND The role of cell adhesion molecules and transmigration of PMNs through the endothelial barrier is probably essential in intestinal ischemia and reperfusion (I/R)-induced gut barrier dysfunction. Although cytokines are released in I/R, it is unclear whether cytokines directly increase permeability or if this phenomenon requires both expression of cell adhesion molecules and PMN adhesion-activation. Endothelial barrier dysfunction plays an important role in the pathogenesis of multiple organ dysfunction syndrome, inducing gut barrier failure, but the mechanisms are not fully understood. The purpose of this study was to evaluate the potential therapeutic value of inhibition of platelet activating factor (PAF), intercellular adhesion molecule-1 (ICAM-1), and platelet endothelial cell adhesion molecule-1 (PECAM-1) in gut barrier dysfunction induced by intestinal I/R. METHODS A PAF antagonist (lexipafant, BB-882) and monoclonal antibodies against rat ICAM-1 (anti-ICAM-1-MAb) and PECAM-1 (anti-PECAM-1-MAb) were used in a model of gut barrier dysfunction caused by intestinal ischemia for 40 min and concomitant reperfusion for 12 h in the rat, and endothelial permeability, myeloperoxidase activity, interleukin-1beta and protease inhibitor levels were evaluated. RESULTS The endothelial permeability and tissue leukocyte recruitment in the distal small intestine significantly increased in rats with I/R treated with saline. Proteolytic activity in plasma was evident by low levels of the three measured plasma protease inhibitors. These changes were, to different degrees, reduced by treatment with lexipafant, anti-ICAM-1-MAb, or anti-PECAM-1-MAb. Alterations in systemic levels of interleukin-1beta paralleled the changes found in gut barrier permeability and leukocyte trapping. CONCLUSIONS Our results suggest that treatment with the PAF inhibitor lexipafant and monoclonal antibodies against ICAM-1 or, seemingly most efficient, PECAM-1 reduces the severity of I/R-associated intestinal dysfunction, associated with a decrease in systemic concentrations of IL-1beta local leukocyte recruitment, and partly restoring plasma protease inhibitor levels.

Gallstone ileus demonstrated by CT

Objective The appearance and evolution of gallstone ileus as seen by CT are reported. Materials and Methods CT examination was performed on three patients with unspecific abdominal pain. In one patient sequential investigations were performed over 7 months. Results In all cases the gallbladder was greatly distorted, contained air, and was in direct continuity with a thickened duodenal wall. The gallstone was detected in the small bowel in all cases. In one patient sequential CT examinations over several months demonstrated the evolution from uncomplicated gallstone disease to cholecystitis and finally to perforation of the gallstone into the duodenal bulb. Conclusion Awareness of the CT findings in gallstone ileus may result in more rapid diagnosis and treatment, which may lead to a decrease in the rather high morbidity and mortality seen in this disease.

Neurohormonal Peptides in Endocrine Tumors of the Pancreas, Stomach, and Upper Small Intestine: I. An Immunohistochemical Study of 27 Cases

Preliminary observations have indicated the existence of characteristic spectra of gastroenteropancreatic (GEP) neurohormonal peptides in endocrine tumors arising in foregut, midgut, and hindgut derivatives. In order to further explore this feature of GEP endocrine neoplasms, islet cell tumors from 14 patients were studied, as were endocrine tumors of the stomach, duodenum, and upper jejunum from 6, 5, and 2 patients, respectively. All tumors were examined immunohistochemically with antisera raised against islet hormones [insulin, somatostatin, glucagon, pancreatic polypeptide (PP)], peptides of the gastrin family [gastrin, cholecystokinin (CCK)], peptides of the secretin family [secretin, vasoactive intestinal peptide (VIP)], and substance P, neurotensin, leu-enkephalin, beta-endorphin, motilin, calcitonin, and ACTH. In addition, an ultrastructural investigation was made. Whenever possible, the immunohistochemical observations were correlated with the clinical manifestations and with the results of radioimmunochemical determination of GEP neurohormones in the blood. The pattern of immunoreactive neurohormonal peptides and the clinical picture were those to be expected in endocrine tumors arising in foregut derivatives. Some principles are proposed for the classification of GEP endocrine tumors on the basis of their histopathologic growth pattern, their spectrum of neurohormonal peptides, and their clinical manifestations.

Elevated Pancreatic Secretory Trypsin Inhibitor Levels during Severe Inflammatory Disease, Renal Insufficiency, and after Various Surgical Procedures

Elevated levels of immunoreactive pancreatic secretory trypsin inhibitor (PSTI) were found in serum from patients with perforated duodenal ulcer, bacterial peritonitis, urosepticemia, pneumonia, acute renal failure, and also after different surgical procedures. The extent of the trauma seemed to determine the maximal level of PSTI. The increase found paralleled the changes seen in the acute-phase protein antichymotrypsin. There was, however, almost no increase in trypsinogen, thought to be produced together with PSTI in the acinar cells of the pancreas. In conclusion, there is evidence that PSTI is probably also produced somewhere outside the pancreas, in agreement with recent immunohistochemical data. This production may be part of a general acute-phase reaction. Thus, PSTI may have a more general inhibitory function against trypsin-like protease release in tissue injury, instead of being a purely local trypsin inhibitor in the pancreatic gland.

Correlation Among Complement Activation, Protease Inhibitors, and Clinical Course in Acute Pancreatitis in Man

Changes in complement levels and protease inhibitors were measured in plasma/serum and peritoneal fluid during 15 attacks of acute pancreatitis. The abnormalities found in the complement system and the protease inhibitors were most pronounced in severe attacks, especially in the peritoneal fluid. Depressed levels of C1q, C3, properdin, and factor I were found in blood on admission in severe attacks. A decrease during the first days of illness was found for C1q, C3, C4, properdin, factor I, and factor H levels in blood. There was a discrepancy between the low C1q and the high C1r and C1s levels in blood. Complexes of C1r-C1s-C1 inactivator and factor B conversion products were found, especially in the peritoneal fluid, denoting an activation of the complement system. High levels of trypsin in complex with alpha 1-protease inhibitor were found, both in blood and in peritoneal fluid, denoting the liberation of active trypsin in acute pancreatitis. The levels of the functional alpha 2-macroglobulin were low, especially in the peritoneal fluid. It is concluded that both classical and alternative complement activation take place in acute pancreatitis, starting in the peritoneal cavity. The magnitude of activation depends on the severity of the disease. Trypsin-induced activation of complement components may explain some of these changes.

Changes in the kallikrein kinin system during acute pancreatitis in man

Changes in the kallikrein-kinin system were analysed in 19 attacks of acute pancreatitis in man and correlated to the severity and clinical course of the disease. Prekallikrein, kininogen and kallikrein inhibition were significantly lower in blood in severe attacks than in moderate or mild attacks. These changes were even more pronounced in peritoneal fluid, where kallikrein activity was above normal, while kininogen and kallikrein inhibition were nil in severe attacks. Both high and low molecular weight kininogen were decreased, denoting an activation also by kininogenases other than plasma kallikrein. These changes indicate an activation of the kallikreinkinin system in acute severe pancreatitis in man, especially in the abdominal cavity. Although there is a great deal of evidence for activation of the kinin system in experimental shock states in animals (1-4), there are to date rather few studies showing that such an activation takes place in human acute pancreatitis. This lack of clinical studies is mainly explained by the difficulty in measuring activated components of the system, especially since these components are rapidly inactivated in different ways in vivo (5).