Thomas Arendt

Intestinal crypt cell apoptosis in murine acute graft versus host disease is mediated by tumour necrosis factor α and not by the FasL-Fas interaction: effect of pentoxifylline on the development of mucosal atrophy

BACKGROUND Murine T cell mediated acute semiallogeneic graft versus host disease (GVHD) is characterised by lymphocytic infiltrates, crypt hyperplasia, and villous atrophy. It has been shown that programmed cell death (apoptosis) of the crypt epithelium takes place during the intestinal manifestation of acute GVHD. AIMS To investigate which of the two most investigated inductors of apoptosis (Fas ligand (FasL) and tumour necrosis factor α (TNF-α)) is responsible for the induction of apoptosis in this animal model. METHODS Animals undergoing acute semiallogeneic GvH reaction were treated with neutralising anti-TNF-α, two different anti-FasL antibodies, or pentoxifylline. RESULTS Anti-TNF-α application inhibited the appearance of apoptotic cells in the intestinal mucosa, whereas anti-FasL antibodies had no influence on mucosal apoptosis. In addition, the transfer of FasL deficient (gld) donor lymphocytes still induced crypt cell apoptosis, villous atrophy, and crypt hyperplasia. Furthermore, when the animals were treated with pentoxifylline, a known inhibitor of TNF-α secretion in vitro and in vivo, there was significant normalisation of the intestinal morphology accompanied by inhibition of epithelial apoptosis. CONCLUSIONS The FasL-Fas interaction is not involved in the induction of apoptosis during acute GVHD. However, neutralisation of TNF-α by an antibody or by pentoxifylline inhibits the occurrence of apoptosis and of mucosal atrophy in this animal model. These results have implications for the treatment of immunologically mediated human atrophic gut diseases—for example, diet refractory cases of coeliac disease.

Activation of the hypothalamo-pituitary-adrenal axis in response to septic or non-septic diseases – implications for the euthyroid sick syndrome

Objective: To determine whether cytokine release or activation of the hypothalamo-pituitary-adrenal (HPA) axis is predominantly involved in the development of the euthyroid sick syndrome (ESS). Design: Prospective observational study. Setting: Intensive care unit at a tertiary care medical center in Germany. Patients: Nine patients with sepsis of different causes and eight patients with acute myocardial infarction. Interventions: None. Measurements and results: Immediately on admission and on day 7 the following parameters were determined: total thyroxine (T4), free thyroxine (FT4), total triiodothyronine (T3), thyrotropin (TSH), interleukin-1β (IL-1β), interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), serum cortisol and plasma adrenocorticotropin (ACTH). On admission, concentrations of all thyroid hormones and TSH were significantly lower in septic patients compared to non-septic patients, whereas all cytokines except IL-2 were significantly elevated in the sepsis group. By contrast, there was no difference in serum cortisol and plasma ACTH levels between the two groups. On day 7, T4 and T3 were still lower in the septic group, whereas IL-1β, sIL-2R and IL-6 were still elevated. Again, no differences were found with regard to cortisol and ACTH levels. Conclusions: Euthyroid sick syndrome occurs very early during the course of septic diseases. Significantly decreased levels of total T4, FT4, T3 and TSH in septic patients suggest central suppression of TSH as well as inhibition of thyroid hormone release in ESS. The HPA axis is activated in septic patients and in non-septic patients and does not contribute to the development of ESS.

Biliary pancreatic reflux-induced acute pancreatitis--myth or possibility?

OBJECTIVEnThe mechanism whereby gallstone passage through the choledochoduodenal junction initiates acute pancreatitis is not known. We mimicked different patterns of stone impaction at the choledochoduodenal junction in a rabbit model and studied whether these result in biliary pancreatic reflux and the initiation of pancreatic inflammation.nnnMETHODSnIn rabbits, catheters were introduced into the common bile duct (CBD) and the pancreatic duct. In five experiments, obstruction of these catheters at various time intervals mimicked different patterns of stone obstruction of both ducts prior to a stone impaction at the papilla of Vater: experiment I--no obstruction of the pancreatic duct and the CBD; experiment II--separate obstruction of the CBD and the pancreatic duct; experiment III--selective obstruction of the CBD; experiment IV--separate obstruction of the CBD and the pancreatic duct and subsequent decompression of the pancreatic duct; experiment V--obstruction pattern as in experiment IV associated with a bacterial infection of bile (10(8) E. coli/ml). Ductal pressures were recorded for 24 h. In order to study the effects of a subsequent impaction of the stone at the papilla of Vater, the catheters in the CBD and in the pancreatic duct were connected and mimicked a common channel behind a papillary stone. The flow direction of bile and pancreatic juice was directly observed. Pancreatic histology was analysed 24 h later.nnnRESULTSnIn experiments I-III, neither biliary pancreatic reflux nor acute pancreatitis was observed. In experiments IV and V, obstruction of the CBD caused an increase in the biliary pressure to 17 +/- 3 cm H2O, whereas the pancreatic duct pressure dropped to subnormal levels following obstruction and selective decompression (2 +/- 0.5 cm H2O). After the creation of a common channel, biliary pancreatic reflux was observed for 118 +/- 21 min. Flow of sterile bile into the pancreas was not harmful to the gland. Infected biliary pancreatic reflux initiated acute pancreatitis.nnnCONCLUSIONSn1. Bile flow into the pancreas may occur. 2. Biliary pancreatic reflux may initiate acute pancreatitis. 3. Bile reflux-induced acute pancreatitis requires previous biliary hypertension, temporary pancreatic duct obstruction, and the bacterial infection of choledochal secretions.

Hypoxic Renal Tissue Damage by Endothelin-Mediated Arterial Vasoconstriction during Radioangiography in Man

In vivo, a high rate of renal blood flow provides a more than sufficient rate of oxygen supply to the kidney. Limitations in tissue oxygenation may occur under systemic circulatory alterations (i.e. cardiovascular failure, arterioscelorosis), respiratory insuffiency (i.e. lung diseases, hypoxia, extreme anemia, acclimation to high altitude), or during perfusion of isolated organs with blood substitutes (Klause, N., and Gronow, G., 1990; Klause, N., et al., 1990). Hypoxic limitation of renal function at a maintained systemic respiration and circulation is less well understood. One example is tissue hypoxia in the kidney due to a vasoconstrictory side effect of radiocontrast media (RCM). Recent animal experiments support evidence that in the pathophysiology of RCM-induced renal vasoconstriction the balance between production of endothelium derived nitric oxide (NO) and endothelin (ET) is disturbed, whereby NO does not seem to play an important role (Bagnis et al., 1997, Morcos et al., 1997).

Santorini's duct : risk factor for acute pancreatitis or protective morphologic variant? Experiments in rabbits

Background and aims: Gallstone pancreatitis is assumed to result from stone passage through the choledochoduodenal junction. Stone impactions may either result in the obstruction of the pancreatic duct or occur below the confluence of the biliary tract and the pancreatic duct and, thus, may favour bile reflux into the pancreatic duct. We studied effects of a patent Santorinis duct upon secretory flow and pancreas morphology under both conditions. Methods: A catheter in the distal rabbit pancreatic duct created a second outlet for pancreatic juice and, thus, mimicked a patent Santorinis duct. A second catheter was introduced into the proximal pancreatic duct and into the common bile duct. This catheter mimicked a common channel behind a papillary obstruction. Clamping of this catheter mimicked a stone obstruction of the pancreatic duct. A catheter in the cystic duct allowed for the infection of bile with 107 Escherichia coli bacteria/ml. The flow direction of bile and pancreatic juice was directly observed. Pancreatic histology was analysed after 24 h. Results: Pancreatic duct obstruction produced an oedema of the gland. Creation of a patent Santorinis duct prevented development of the histological changes caused by pancreatic duct obstruction. In rabbits in which a common channel obstruction was mimicked, Santorinis duct produced flow of bile along the pancreatic duct system. Flow of sterile bile along the duct did not cause pancreatic inflammatory lesions. Bile that was infected with E. coli bacteria produced an acute interstitial‐oedematous pancreatitis. Conclusions: (1) A patent Santorinis duct protects the gland from the effects of main pancreatic duct obstruction; (2) Santorinis duct promotes biliary pancreatic reflux during obstruction of the common channel and subsequent development of pancreatitis caused by infected choledochal secretions; (3) Santorinis duct may thus be both a protective morphological variant and a risk factor for pancreatitis dependent upon the site of stone impaction within the choledochoduodenal junction.

Iodine absorption in patients undergoing ERCP compared with coronary angiography

BACKGROUNDnSystemic absorption of iodinated contrast material occurs during endoscopic retrograde cholangiopancreatography (ERCP), the clinical significance of which has not yet been determined.nnnMETHODSnUrinary iodine excretion was measured before and after coronary angiography (n = 20) and ERCP (n = 12). Thyroid hormone levels were determined before iodine load and after 6 and 24 weeks.nnnRESULTSnBefore coronary angiography, iodine excretion was 101 +/- 38.3 micromol/mol creatinine and increased to 865. 10(5) +/- 721. 10(5) micromol/mol on the next day (p </= 0.001). After 6 weeks, it was still elevated (167 +/- 88.8 micromol/mol, p < 0.01). Before ERCP, iodine excretion was 115 +/- 60.3 micromol/mol and reached a peak of 5.3. 10(5) +/- 4.9. 10(5) micromol/mol (p < 0.001). Six weeks later, it had returned to baseline. Two patients in the coronary angiography group but none in the ERCP group had suppressed thyrotropin after 6 weeks.nnnCONCLUSIONSnThe systemic iodine load during ERCP is approximately 0.6% of the iodine load during coronary angiography. Therefore routine measurement of thyroid hormones before ERCP is not recommended.

Infected bile-induced acute pancreatitis in rabbits. The role of bacteria.

SummaryConclusionsBacteria species commonly found in bile of patients with choledocholithiasis render human bile toxic to the pancreas. The severity of infected bile-induced acute pancreatitis depends on the bacterial species. Infected bile-induced acute pancreatitis turns into a sterile inflammation within 10 d.BackgroundFlow of bile into the pancreatic duct was proposed to cause some forms of gallstone pancreatitis. The development of bile-induced acute pancreatitis at physiologic ductal pressure is known to depend on the bacterial infection of bile. In this study, we investigated the effect of a variety of bacteria species commonly found in bile of patients with choledocholithiasis upon the pancreatic toxicity of human bile. The time-course of pancreatic infection in infected bile-induced acute pancreatitis was also analyzed.MethodsIn rabbits, the pancreatic duct was kept obstructed throughout the experiment. After 24 h, 50 μL of pancreatic juice was obtained from the congested pancreatic duct and replaced with the same quantity of infected human bile. Bile contained bacteria (107 microorganisms/μL) of species frequently found in choledochal secretions of patients with gallstone disease. Effects on pancreatic morphology were studied after 48 h. In another experiment, the number ofEscherichia coli/mg of pancreatic tissue was determined in a time sequence study following exposure of the rabbit pancreatic duct to 50 μLE. coli-infected bile (107 microorganisms/mL) and temporary (12 h) or permanent duct obstruction.ResultsSterile bile was not harmful to the pancreas. Infected bile caused an interstitial-edematous pancreatitis with occasional acinar necrosis. The severity of acute pancreatitis depended on the bacterial species. Following pancreatic duct exposure toE. coli-infected bile, there was complete clearance of the bacteria from the gland with a concomitant interstitial leukocyte infiltration within a period of 2–10 d.

Chylous cardiac tamponade in acute pancreatitis

SummaryA 47-year-old woman with acute necrotizing pancreatitis developed sudden cardiorespiratory arrest and needed resuscitation. A pericardial effusion was found, and 350 ml of a white nontransparent milky fluid was aspirated that contained 1020 mg triglycerides/100 ml. The diagnosis of chylous cardiac tamponade was made. Absence of amylase in the chylous effusion militates against the popular hypothesis that lymphatic transport of exocrine digestive enzymes from the inflamed pancreas produces the frequent intrathoracic serosal effusions in acute pancreatitis. The data of our patient rather suggest that these effusions result from the leakage of pancreatic inflammatory exudates through the diaphragm which, apparently, may even result in the loss of pericardial and adjacent thoracic lymph vessel integrity. Although pericardial tamponade is a rare complication, it should be considered if otherwise unexplained circulatory deterioration occurs in a patient with acute pancreatitis.

Does bile of patients with acute gallstone pancreatitis cause pancreatic inflammatory lesions? A study of the pancreatic toxicity of choledochal secretions collected at ERCP

BACKGROUNDnBile flow into the pancreatic duct has been proposed as the cause of acute biliary pancreatitis. However, the pancreatic toxicity of choledochal bile from patients with acute gallstone pancreatitis has not been studied.nnnMETHODSnBile was collected endoscopically from the common bile ducts of 21 patients with acute gallstone pancreatitis within 72 hours after the onset of disease. The bile samples were instilled into the pancreatic duct of rabbits, and light microscopic examination of the pancreas morphology was performed to assess the toxicity of human bile. Microbiologic quantitative analysis of the aerobic and anaerobic bacterial bile flora was performed.nnnRESULTSnBile of six patients with acute gallstone pancreatitis (29%) induced interstitial inflammation in the rabbit pancreas. Choledochal bile of these patients harbored more than 10(4) CFU/mL bacteria (Proteus vulgaris, n = 1; Klebsiella pneumoniae, n = 1; Escherichia coli, n = 2; enterococci, n = 2). After sterilization, the bile samples did not induce acute pancreatitis. In 15 patients (71%), bile did not cause acute pancreatitis in the rabbit pancreas. These choledochal secretions were sterile or contained less than 10(4) CFU/mL.nnnCONCLUSIONSnReflux of infected bile may be a potential cause of acute pancreatitis in the minority of patients with bacterobilia. In most patients with gallstone pancreatitis, bile is neither infected nor harmful to the pancreas, and its flow into the gland is unlikely to be the cause of inflammation.

Interferon-γ is not involved in the intestinal manifestations of the acute murine semiallogenic graft-versus-host disease

Background: The acute murine semiallogenic graft-versus-host disease (GvHD) is known to be associated with Th1 cytokines secreting lymphocytes in the spleen and lymph nodes. However, whether this cytokine secretion pattern is also involved in the intestinal manifestations of acute GvHD (crypt hyperplasia and villous atrophy) is not known, so far. Methods: We first investigated the secretion of interleukin (IL) 4 (indicative of Th2-type differentiation) and interferon (IFN) γ (Th1-type differentiation) by splenic and by small bowel lamina propria lymphocytes. In addition, animals were treated with neutralizing antibodies to IL-4 or IL-12. The effect of this treatment on the intestinal morphology was examined. Second, we also investigated the effect of donor-derived IFN-γ by using donor lymphocytes from IFN-γ knock-out animals. Third, animals were treated with the fusion protein OX40-Ig which interferes with the OX40-OX40L interaction and thereby inhibits the intestinal manifestations of acute GvHD. Results: We found that, whereas splenic lymphocytes secrete an excess of IFN-γ, lymphocytes of the intestinal lamina propria secrete less IFN-γ and IL-4 than control animals. When OX40-Ig is administered to animals with acute GvHD, the intestinal histology normalizes as well as the secretion of IFN-γ and IL-4, indicating that the intestinal morphology is not affected by the secretion of IFN-γ by lamina propria lymphocytes. The treatment of animals suffering from acute GvHD with anti-IL-4 and anti-IL-12, which blocks the differentiation of IFN-γ secreting T-lymphocytes, did not significantly affect the development of crypt hyperplasia or villous atrophy. Furthermore, donor lymphocytes of IFN-γ knock-out animals also induced the intestinal manifestations of acute GvHD. Conclusions: These findings indicate that IFN-γ is not crucial for the development of crypt hyperplasia and villous atrophy in the murine semiallogenic GvHD.