A rat model to study hypercalcemia-induced acute pancreatitis

Common calcium-sensing receptor (CASR) gene variants do not modify risk for chronic pancreatitis in a Hungarian cohort

The calcium-sensing receptor (CASR) is expressed in the pancreas where it might regulate calcium concentrations in pancreatic secretions. Two independent studies reported conflicting results claiming that commonly occurring missense variants of the CASR gene are risk factors for chronic pancreatitis (CP). Here, we attempted to replicate the association between CASR variants and CP. We analyzed 337 patients and 840 controls from the Hungarian National Pancreas Registry either by direct sequencing of exon 7 and the flanking noncoding regions or by TaqMan SNP genotyping assays. We identified two common missense variants, c.2956G>T (p.A986S), and c.2968A>G (p.R990G), three low-frequency variants, c.3031C>G (p.Q1011E), c.2610G>A (p.E870=) and c.∗60T>A, and 8 rare variants including the novel variant c.1895G>A (p.G632D). When allelic or genotype distributions were considered, none of the CASR variants associated with CP. Subgroup analysis of nonalcoholic versus alcoholic patients revealed no disease association either. Our results demonstrate that common CASR variants do not modify the risk for CP and should not be considered as genetic risk factors in the clinical setting.

Metabolic pancreatitis: Etiopathogenesis and management

Acute pancreatitis is a medical emergency. Alcohol and gallstones are the most common etiologies accounting for 60%-75% cases. Other important causes include postendoscopic retrograde cholangiopancreatography procedure, abdominal trauma, drug toxicity, various infections, autoimmune, ischemia, and hereditary causes. In about 15% of cases the cause remains unknown (idiopathic pancreatitis). Metabolic conditions giving rise to pancreatitis are less common, accounting for 5%-10% cases. The causes include hypertriglyceridemia, hypercalcemia, diabetes mellitus, porphyria, and Wilson's disease. The episodes of pancreatitis tend to be more severe. In cases of metabolic pancreatitis, over and above the standard routine management of pancreatitis, careful management of the underlying metabolic abnormalities is of paramount importance. If not treated properly, it leads to recurrent life-threatening bouts of acute pancreatitis. We hereby review the pathogenesis and management of various causes of metabolic pancreatitis.

The role of calcium in acute pancreatitis

Until recently, it was unclear whether calcium is more than a bystander in the development of acute pancreatitis. Now important evidence has been accumulated supporting a pivotal role of intracellular levels of calcium in the early pathogenesis of the disease. A sustained increase of cytosolic calcium concentrations, as observed in various models of acute pancreatitis, was identified as sabotaging crucial cellular defense mechanisms and initiating premature trypsinogen activation. These processes lead the acinar cell to necrosis, with spillage of activated proteases into the interstitial space, affecting surrounding acinar cells and initiating a vicious circle that ends in macroscopic acute pancreatitis and systemic inflammatory response syndrome. Comprehensive knowledge of the pathobiology of cytosolic calcium in the pancreatic acinar cell is leading to the understanding of coherent molecular pathways of early events in the pathogenesis of acute pancreatitis and is opening horizons for research into directly targeted therapeutic agents.

Molecular and functional identification of a Ca2+ (polyvalent cation)-sensing receptor in rat pancreas

The balance between the concentrations of free ionized Ca2+ and bicarbonate in pancreatic juice is of critical importance in preventing the formation of calcium carbonate stones. How the pancreas regulates the ionic composition and the level of Ca2+ saturation in an alkaline environment such as the pancreatic juice is not known. Because of the tight cause-effect relationship between Ca2+ concentration and lithogenicity, and because hypercalcemia is proposed as an etiologic factor for several pancreatic diseases, we have investigated whether pancreatic tissues express a Ca2+-sensing receptor (CaR) similar to that recently identified in parathyroid tissue. Using reverse transcriptase-polymerase chain reaction and immunofluorescence microscopy, we demonstrate the presence of a CaR-like molecule in rat pancreatic acinar cells, pancreatic ducts, and islets of Langerhans. Functional studies, in which intracellular free Ca2+ concentration was measured in isolated acinar cells and interlobular ducts, show that both cell types are responsive to the CaR agonist gadolinium (Gd3+) and to changes in extracellular Ca2+ concentration. We also assessed the effects of CaR stimulation on physiological HCO3- secretion from ducts by making measurements of intracellular pH. Luminal Gd3+ is a potent stimulus for HCO3- secretion, being equally as effective as raising intracellular cAMP with forskolin. These results suggest that the CaR in the exocrine pancreas monitors the Ca2+ concentration in the pancreatic juice, and might therefore be involved in regulating the level of Ca2+ in the lumen, both under basal conditions and during hormonal stimulation. The failure of this mechanism might lead to pancreatic stone formation and even to pancreatitis.

Pancreatitis and primary hyperparathyroidism: forty cases

BACKGROUND

Pancreatitis is associated with primary hyperparathyroidism (PHPT) in 1.5-7% of cases. The relationship of cause and effect between the two diseases has been debated.

METHODS

To evaluate this relationship, the clinical, biochemical and pathological data on 1435 patients operated on for hyperparathyroidism (HPT) over the past 30 years were retrospectively reviewed. A total of 1224 of these patients had biologically proven and cured PHPT and 211 patients had renal HPT (RHPT). The diagnosis of pancreatitis (PTS) was based on a high serum amylase level and/or abnormalities on ultrasound or computed tomography (CT) scan explorations. Only patients without biliary stones were included in the PTS group associated with HPT.

RESULTS

A total of 3.2% (n = 40) of patients with PHPT had PTS, which was acute in 18 cases, subacute in 8 cases and chronic in 14 cases. This rate of PTS is higher than in a random hospital population. Surgical cure of HPT was followed by the spontaneous healing of 17/18 acute PTS, whereas six of the 22 patients with subacute or chronic PTS developed complications due to the evolution of their disease (diabetes, pancreatic duct stenosis treated by surgery). A single diseased gland was found in 27 patients with PTS, which is in favour of primary parathyroid disease, being responsible for, and not a consequence of, PTS. Only the serum calcium (13.0 vs 12.1 g/dL) level was significantly increased in PHPT patients with PTS, when compared to those without PTS. The calcium level is probably of major importance in the development of PTS, which was never encountered in 211 patients with RHPT, who had low calcium and high PTH levels.

CONCLUSIONS

The data suggest that (i) the PTS-PHPT association is not incidental; (ii) PTS is the consequence and not the cause of PHPT; (iii) hypercalcaemia seems to be a major factor in the development of PTS in PHPT patients; and (iv) cure of PHPT leads to the healing of acute PTS, whereas it does not affect the evolution of subacute and chronic PTS.