Role of Vascular Endothelial Growth Factor-D (VEGF-D) on IL-6 Expression in Cerulein-Stimulated Pancreatic Acinar Cells

Cerulein pancreatitis is similar to human edematous pancreatitis with dysregulation of the digestive enzyme production and cytoplasmic vacuolization, the death of acinar cells, edema formation, and an infiltration of inflammatory cells into the pancreas. Our preliminary proteomic analysis showed increased expression of vascular endothelial growth factor-D (VEGF-D) in cerulein (10(-8)M)-treated pancreatic acinar cells. We hypothesized that VEGF-D may have a role in cerulein-induced cytokine expression in pancreatic acinar cells. This article was designed to elucidate whether cerulein induces VEGF-D expression in pancreatic AR42J cells, and whether VEGF-D expression is related to interleukin-6 (IL-6) expression by transfecting antisense oligonucleotide (AS ODN) for VEGF-D into pancreatic acinar AR42J cells. Cerulein-induced AP-1 activation was monitored in the cells transfected with AS ODN or sense ODN (S ODN) for VEGF-D. mRNA expression of IL-6 was determined by RT-PCR analysis. AP-1 activation was assessed by electrophoretic mobility shift assay (EMSA). VEGF-D expression was assessed by Western blotting. Cerulein induced IL-6 expression and VEGF-D expression in AR42J cells. Cerulein-induced AP-1 activation and IL-6 expression was inhibited in the cells transfected with AS ODN for VEGF-D as compared to S ODN. Cerulein-induced VEGF-D expression may have a role in AP-1 activation and IL-6 expression in pancreatic acinar cells.

Biliary lipid composition in cholesterol microlithiasis

BACKGROUND

Little information is available on the pathogenesis of cholesterol microlithiasis, and it is not clear if biliary lipid composition in these patients is similar to changes seen in cholesterol gall stone patients.

AIMS

To measure biliary lipid composition in patients with cholesterol microlithiasis.

PATIENTS

Eleven patients with cholesterol microlithiasis, 20 cholesterol gall stone patients, and 17 healthy controls.

METHODS

Duodenal bile was collected in the fasting state during ceruletide infusion. Biliary cholesterol, phospholipids, and total bile acids were analysed by enzymatic assays, and conjugated bile acids by high pressure liquid chromatography.

RESULTS

Patients with microlithiasis had a cholesterol saturation index significantly higher than controls (mean value 1.30 (95% confidence interval 1.05-1.54) v 0.90 (0.72-1.08)) but similar to gall stone patients (1.51 (1.40-1.63)). This was due to a significant decrease in per cent phospholipid (10.0% (7.1-12.8)) compared with controls (21.4% (18.1-24.6)) and gall stone patients (24.9% (20.5-29.3)). Per cent cholesterol was similar in patients with microlithiasis and controls (5.3% (4.5-6.1) and 5.6 % (4.3-6.8), respectively) but was significantly increased in gall stone patients (10.9% (9.3-12.4)). Bile acid composition in patients with microlithiasis was similar to controls whereas in gall stone patients deoxycholic acid was significantly increased: 27.3% (24.8-29.7) v 19.0% (15.7-22.2) in controls and 20.6% (14.9-26.2) in patients with microlithiasis.

CONCLUSION

Patients with cholesterol microlithiasis have biliary cholesterol supersaturation, similarly to cholesterol gall stone patients. Whereas in the latter this is due to increased per cent cholesterol, in patients with microlithiasis this is caused by phospholipid deficiency, with normal per cent cholesterol and normal biliary bile acid composition.

Pancreatic function tests: when to choose, what to use

Although techniques for high-resolution imaging of the pancreas are constantly being improved, the evaluation of pancreatic function remains crucial for the workup of pancreatic diseases. More than 20 direct and indirect tests are available for the assessment of pancreatic function. Measurement of fecal elastase-1 is recommended as the most suitable test for the initial assessment of pancreatic function. Among other techniques, the pancreolauryl test, and alternatively the BT-PABA (N-benzoyl-L-tyrosyl-p-aminobenzoic acid) or the (13)C-mixed-triglyceride test, yield the best sensitivity and specificity. Nevertheless, all indirect tests are of limited value in patients with mild to moderate impairment of pancreatic function. In these patients, the secretin-caerulein test remains the gold standard.

Influence of gastrointestinal hormones on tumor microcirculation of experimental pancreatic cancer in the rat

BACKGROUND/AIMS

Gastrointestinal hormones influence the microcirculation in the normal pancreas. In the present study, we studied the effect of cerulein and somatostatin on pancreatic cancer microcirculation after orthotopic and nonorthotopic tumor implantation.

METHODS

In 36 male Lewis rats (150-180 g) induction of a ductlike pancreatic cancer was achieved by intrapancreatic or intraperitoneal tumor fragment interposition between two inert transparent polymethyl methacrylate plates. After 4 weeks, intravital microscopy of the tumor microcirculation was performed in a temperature-controlled immersion chamber. The animals received 5 microg/kg cerulein or 3 mg/kg somatostatin for 1 h intravenously. The erythrocyte velocity in normal pancreatic capillaries or in tumor vessels was measured.

RESULTS

The erythrocyte velocity in the capillaries of the normal pancreas was 1.01 +/- 0.11 mm/s at baseline and increased to 1.64 +/- 0.09 mm/s after cerulein stimulation (p = 0.007). Pancreatic cancer vessels demonstrated no increase in erythrocyte velocity after orthotopic (baseline 0.95 +/- 0.14 mm/s, after 1 h 0.86 +/- 0.13 mm/s; n.s.) and nonorthotopic tumor implantation (baseline 0.91 +/- 0.12 mm/s, after 1 h 0.95 +/- 0.14 mm/s; n.s.) after cerulein stimulation. Somatostatin decreased the erythrocyte velocity both in normal pancreas (baseline 0.87 +/- 0.02 mm/s, after 1 h 0.60 +/- 0.07 mm/s; p = 0.01) and in pancreatic cancer (baseline 0.85 +/- 0.20 mm/s, after 1 h 0.63 +/- 0.18 mm/s; p = 0.02) after orthotopic tumor implantation. There was no effect of somatostatin after nonorthotopic tumor implantation (baseline 0.90 +/- 0.10 mm/s, after 1 h 0.88 +/- 0.14 mm/s; n.s.).

CONCLUSION

These data suggest that pancreatic cancer microcirculation lacks physiological blood flow control by stimulatory hormones, in contrast to the normal pancreas.

The role of calcium in pancreatitis

BACKGROUND/AIMS

A large, sustained increase in acinar [Ca2+]i may play a key role in the pathogenesis of acute pancreatitis. Many mechanisms which lead to cell damage in vitro and pancreatitis in vivo, such as free radicals or supraphysiological cerulein concentrations, cause a rapid increase in [Ca2+]i in pancreatic acinar cells. Little is known about why [Ca2+]i increases in some instances stimulate secretion and in other instances initiate cell death. So far, [Ca2+]i increases were thought to represent physiological signals when they occurred as oscillations at the single cell level.

METHODOLOGY

This paper reviews recent literature and our own original research about the role of calcium in the function of pancreatic acinar cells and the development of pancreatitis.

RESULTS

Recent studies showed that exposure of acinar cells to free radicals not only caused a bulk increase in [Ca2+]i but also resulted in calcium oscillations which had a lower frequency than, but similar amplitude to oscillations occurring after physiological stimuli. The absolute increase in [Ca2+]i did not definitely determine the cellular response. Instead, the duration of [Ca2+]i increase may have been more important. In contrast to previous belief of a direct relationship between [Ca2+]i oscillations and exocytosis, recent results show that radicals can induce [Ca2+]i oscillations which do not exert exocytosis but inhibit the secretory response to physiological stimuli. Further experiments showed that the [Ca2+]i release caused by radicals originates from thapsigargin-insensitive, ryanodine-sensitive stores.

CONCLUSIONS

The origin and duration of [Ca2+]i increases rather than their extent or oscillatory nature, determine whether the cell will secrete or die. An abnormal [Ca2+]i increase can trigger trypsin activation, acinar cell damage and acute pancreatitis. This hypothesis is supported by studies which show that calcium chelators inhibit radical-induced trypsin activation as well as cell necrosis and apoptosis. Thus, an inhibition of pathological [Ca2+]i release may have a therapeutic potential.

Effects of cholecystokinin, caerulein and pentagastrin on arterial blood pressure and plasma renin activity in rats

Effects of cholecystokinin (CCK-33), caerulein (CER) and pentagastrin (PG) on arterial blood pressure and plasma renin activity (PRA) were studied in rats. The results showed that CCK-33 (106.25, 212.5 and 425.0 pmoles/kg i.v.) increased systolic and diastolic blood pressure and decreased PRA. CER used at doses: 0.37, 1.85 and 3.7 nmoles/kg (i.v.) did not change systolic blood pressure. CER administered at the higher doses slightly decreased diastolic blood pressure, evoked bradycardia and increased PRA. PG used at doses of 0.13, 1.3 and 13.0 nmoles/kg (i.v.) and the peptide given at the highest dose (13.0 nmoles/kg, i.v.) slightly increased arterial blood pressure. PG administered at all doses did not change PRA. This research shows that in spite of similarity in biochemical structure of CCK-33, CER, PG there are differences in effects of the studied peptides on arterial blood pressure and PRA. The correlation between an influence of CCK-33, CER and PG on arterial blood pressure and PRA was also observed.

[Effect of pancreatic innervation on exocrine secretory performance of the pancreas]

In the present study we examined the influence of extrinsic pancreatic innervation on exocrine pancreatic response to secretin, caerulein, tryptophan and fat, and furthermore the amino acid- and fat-stimulated release of neurotensin and CCK in dogs. Denervation of the pancreas did not alter secretory response to secretin and caerulein, whereas transsection of the extrinsic nerves significantly diminished the protein response to tryptophan and fat. Release of CCK was not altered by pancreatic denervation. However, fat-evoked neurotensin plasma levels were significantly increased after denervation of the pancreas.

Pancreatic lysosomal enzyme secretion via gut-hormone-regulated pathway in rats

To explore the secretory profiles of lysosomal enzyme in pancreatic juice, we stimulated the secretion of lysosomal enzyme by intravenous pancreatic secretagogues and intraduodenal instillation of liquid meals in rats. Lysosomal hydrolases, such as cathepsin B, are secreted from the apices of pancreatic acinar cells via a hormone-regulated pathway, as in the secretion of pancreatic digestive enzymes. The intravenous infusion of the cholecystokinin analogue caerulein, or the intraduodenal administration of nutrients results in a closely related secretion of both amylase and cathepsin B from the apices of acinar cells, suggesting that they are discharged from the same presecretory compartment (zymogen granules). Lysosomal enzymes appear to enter into the secretory compartment as a result of malsorting, but the cause of this anomaly is not known. We found small amounts of lysosomal enzymes colocalized with digestive enzymes within zymogen granules in normal acinar cells and in normal pancreatic juice, suggesting some physiological roles of lysosomal enzymes in pancreatic ducts. Furthermore, lysosomal enzymes appear to play important roles in the pathogenesis of pancreatic disease, such as pancreatitis, from both inside and outside the pancreas, since cathepsin B can probably activate trypsinogen.

[Tensiometric study of muscular strips of guinea pig gallbladder]

The tensiometric properties of smooth muscle strips from 10 male guinea pig gallbladders were evaluated following acetylcholine (ACH), cholecystokinin octapeptide (CCK-OP), cerulein (CRL) and histamine (HIS) administration. All agonists induced dose-dependent tonic contractions with the maximum effect caused by the octapeptide. CRL showed a 9-folds higher relative potency when compared to CCK-OP. ED50s of agonists were: ACH 1.36 +/- 0.28 SEM microM (n = 14; range 0.20-3.60); HIST, 5.7 +/- 1.9 microM (n = 12; range 1-23); CRL 0.72 +/- 0.15 nM (n = 8; range 0.35-1.07); CCK-OP, 6.77 +/- 1.80 nM (n = 12; range 0.44-20.32); For the same strips, max tension (g), was: 1.97 (SEM 0.12) for ACH; 1.5 (0.18) for HIST; 1.81 (0.18) for CRL; 2.44 (0.14) for CCK-OP. Pretreatment of the strips with atropine (1 microM) completely abolished ACh-induced contractions, without affecting either CCK-OP or CRL responses. The model represents a valid "in vitro" study of different molecules whose action might stimulate, enhance or inhibit the physiological hormonal and non-hormonal effect of the agonists at the level of animal and human gallbladder smooth muscle.

Interaction of neurotensin with caerulein or secretin on digestive tract growth in rats

Because neurotensin may potentiate exocrine pancreatic secretory responses to cholecystokinin and secretin, we examined interactions of neurotensin with caerulein or secretin on growth of pancreas, stomach, small intestine, and colon. Rats were injected with saline, neurotensin (100 micrograms/kg), caerulein (0.67 micrograms/kg), secretin (100 micrograms/kg), or neurotensin plus caerulein or secretin every 8 h for 5 days. Pancreas, stomach, small intestine, and colon were weighed and assayed for DNA, protein, and digestive enzymes. Although neurotensin increased pancreatic weight (P less than 0.01), DNA (P less than 0.01), and protein content (P less than 0.05) by 20-30%, it had less than additive effects on responses to caerulein and secretin. Neurotensin had no effects on pancreatic enzymes or on responses to caerulein or secretin. Neurotensin alone had no effects on growth of the oxyntic gland area or antrum but inhibited increases in antral weight, DNA, and protein caused by secretin. Neurotensin increased small intestine weight (9%, P less than 0.05) and protein content (23%, P less than 0.01). Secretin also increased weight (22%), DNA (29%), and protein content (48%) of the small intestine (all P less than 0.01), but neurotensin and secretin together had less than additive effects. Our results suggest that neurotensin inhibits rather than potentiates certain growth effects of caerulein or secretin on the pancreas and other organs.

Multiple-level caerulein control of the gene expression of secretory proteins in the rat pancreas

Continuous intravenous infusion of caerulein (0.25 micrograms X kg-1 X h-1) has recently been reported [Schick, J., Kern, H. & Scheele, G. (1984) J. Cell Biol. 99, 1569-1574] to enhance significantly the synthesis of both trypsinogen and chymotrypsinogen and to decrease that of amylase in the rat pancreas. With a view to achieving a better understanding of the mechanisms underlying caerulein modulation of pancreatic gene expression, the relative levels of active mRNA corresponding to these proteins were determined in caerulein-stimulated animals and compared to those of controls infused with a 0.9% NaCl solution. For this purpose, the translation products synthesized in vitro in a rabbit reticulocyte lysate translation system were measured. Prolonged caerulein infusion had less pronounced effects on mRNA levels as determined by the relative synthesis of translation products than on individual secretory proteins. No changes in mRNA levels were observed during 6 h of hormonal stimulation, whereas a 7-fold increase in the ratio of trypsinogen to amylase synthesis was obtained previously. After 24 h of caerulein infusion, only a slight change in active mRNA coding for amylase (1.7-fold) and serine protease zymogens (1.4-fold) occurred as compared to 14-fold and 2-fold variations in the synthesis rates of the corresponding proteins. These findings indicate that caerulein exerts a predominantly translational control on the biosynthesis of pancreatic amylase, trypsinogen and chymotrypsinogen even after 24 h of hormonal stimulation. However, additional control at a transcriptional or post-transcriptional level (i.e. via messenger RNA stability) may well take place.

Ceruletide intravenous dose-response study by a simplified scintigraphic technique

The intravenous dose response of a ceruletide diethylamine (ceruletide) was established by a simplified scintigraphic technique where multiple graded doses were given sequentially on a single occasion. The gallbladder volume was represented nongeometrically by 99mTc-IDA counts. The mean latent period, ejection period, and ejection rate were similar for all four groups of subjects given 1-20 ng/kg of ceruletide. The mean (+/- SD) ejection fractions after 1, 5, 10, and 15 ng/kg of ceruletide as the single dose were 19.4 +/- 11.9%, 59.6 +/- 26.0%, 55.2 +/- 23.3%, and 67.8 +/- 8.7%, respectively. These ejection fractions were similar to the values when the identical dose of ceruletide was administered sequentially either before or after another dose. A dose of 5 ng/kg produced the most physiologic type of emptying. Intravenous doses of 10 ng/kg and larger caused adverse reactions in 42% of the total doses in the form of abdominal pain, nausea, systolic and diastolic hypotension, or bradycardia. It is concluded that the dose response of a cholecystokininlike agent (ceruletide) can be established reliably by a scintigraphic technique where multiple graded doses are given on a single occasion.

Phyllomedusa skin: a huge factory and store-house of a variety of active peptides

The skin of the neotropical hylid frogs belonging to the subfamily. Phyllomedusinae is a formidable factory and store-house of a variety of active peptides belonging to seven distinct families: the caeruleins (represented by phyllocaerulein), the bradykinins (phyllokinin), the tachykinins (phyllomedusin), the bombesins (phyllolitorin, [Leu8]phyllolitorin, rohdei-litorin), sauvagine, the dermorphins (dermorphin, [Hyp6]dermorphin) and finally the tryptophyllins (a set of 8-11 members). Another linear peptide and three diketopiperazines should be added to the list. The biochemical and pharmacological positions of the Phyllomedusa peptides within their families is briefly discussed, dwelling upon some recent and controversial data.

Is caerulein amphibian CCK?

The amphibian skin decapeptide caerulein is structurally related to the mammalian peptides gastrin and CCK, suggesting that the peptides might share a common evolutionary history. It has been suggested that caerulein is the amphibian counterpart of gastrin and CCK, and that the Amphibia do not possess authentic gastric and CCK. High Performance Liquid Chromatography (HPLC) in conjunction with radioimmunoassay using a caerulein-specific antiserum and C-terminal CCK antisera, was used to characterize CCK-and caerulein-like peptides in amphibian brain and gut. In the brain of Xenopus laevis, two CCK-like peptides were present, one of which was indistinguishable by HPLC from mammalian CCK8. No decapeptide caerulein was detected in the brain of Xenopus laevis or Rana temporaria. In the stomach of Xenopus and in the intestine of both species studied, CCK-like and caerulein-like peptides were present. The results indicate therefore that the Amphibia possess CCK8-like rather than caerulein-like peptides in brain. In contrast, stomach and intestine contain both CCK-like and caerulein-like peptides, but the latter are however distinguishable from the decapeptide found in skin.

Pathophysiology of gastrointestinal hormones. Implications for paediatrics

Gastrointestinal hormones (GI hormones) have received growing interest in endocrinology, gastroenterology and neuroendocrinology. Because of new methodological techniques, they can be measured in plasma and therefore be related to different pathophysiological conditions. In childhood, our present knowledge is as yet limited to the physiological rôle of gastrin at different ages and in some diseases (gastrinoma; Verner-Morrison syndrome) caused by humoral dysfunction. The present review relates the clinical important GI hormones to chemically classified families. The diagnostic value of determining endogenous hormone concentration in plasma and the validity of function tests carried out by administration of exogenous hormones are pointed out. Particular emphasis is given to the trophic action of GI hormones in the development and function of the gastrointestinal tract during childhood. More speculatively, GI hormones are involved in the complex function of the central nervous system, thus making food intake a trophotropic action in a broader sense.

Somatostatin 28: effects on exocrine pancreatic secretion in conscious dogs

The effect of somatostatin 28, a noval intestinal peptide containing somatostatin in its C-terminal portion, was tested on basal exocrine pancreatic secretion on conscious dogs and after stimulation by secretin (1 CU x kg-1 x hr-1), caerulein (37.5 ng x kg-1 x hr-1) or secretin (2 CU x kg-1 x hr-1) caerulein (37.5 ng x kg-1 x hr-1). We found differences in the inhibitory effect of somatostatin 28 on these three forms of stimulation. Bicarbonate secretion stimulated by secretin was inhibited only slightly by large doses of somatostatin 28, whereas small doses markedly inhibited stimulation by caerulein. Protein concentrations were inhibited only when secretin was the stimulant. Protein outputs to all forms of stimulation were inhibited. When compared with synthetic somatostatin 14, lower doses of somatostatin 28 were required to produce the same inhibitory effect on protein outputs stimulated by secretin alone and on volumes stimulated by caerulein alone.