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Markus M Lerch

Publications and source records attributed to Markus M Lerch.

36 records · Page 2Linked to original sources
PubMed2004

Early events in acute pancreatitis.

Considerable progress in the understanding of the pathogenesis of acute pancreatitis is based on the conclusive finding that the initiation of the disease occurs within the acinar cell. Two lines of evidence have contributed to the progress in understanding the disease process: (1) the identification of patients with a hereditary form of pancreatitis as carriers of germline-mutations in the genes for cationic trypsinogen and the pancreatic secretory trypsin inhibitor and (2) the use of various transgenic and knock-out mouse strains in experimental models of acute pancreatitis. On the other hand, these studies have delivered several unexpected results that appear to be incompatible with long-standing dogmas and paradigms of pancreatic research. Further progress in knowledge will result if the well-characterized enzymatic properties of human enzymes that are involved in the initial activation cascade can be investigated under in vivo conditions in transgenic animals or in permanent acinar cell lines. Such studies will permit the development of effective strategies for the prevention and treatment of this disease.

Acute Disease↗
PubMed2004

Medical treatment of acute pancreatitis.

Eighty percent of all cases of acute pancreatitis are linked etiologically to gallstone disease or caused by immoderate alcohol consumption. No specific causal treatment for acute pancreatitis exists. Early prognostic factors that indicate severe disease are three or more signs on organ failure scores according to Ranson, Imrie, or Acute Physiology and Chronic Health Evaluation (APACHE) 11, extrapancreatic complications of the disease, or the detection of pancreatic necrosis on CT scans. Elevated CRP levels above 130 mg/L can also predict a severe course of acute pancreatitis. The essential medical treatment for acute pancreatitis is the correction of hypovolemia. Moreover, relief of often severe visceral pain is a high priority. Prophylactic antibiotics should be restricted to patients with necrotizing pancreatitis, infected necrosis, or other infectious complications. Enteral nutrition has no adverse effect compared with parenteral nutrition during the course of acute pancreatitis, and is probably beneficial in regard to outcome.

Acute Disease↗
PubMed2004

Clinical and genetic characteristics of hereditary pancreatitis in Europe.

BACKGROUND & AIMS: Hereditary pancreatitis is an autosomal dominant disease that is mostly caused by cationic trypsinogen (PRSS1) gene mutations. The aim was to determine phenotype-genotype correlations of families in Europe. METHODS: Analysis of data obtained by the European Registry of Hereditary Pancreatitis and Pancreatic Cancer was undertaken using multilevel proportional hazards modelling. RESULTS: There were 112 families in 14 countries (418 affected individuals): 58 (52%) families carried the R122H, 24 (21%) the N29I, and 5 (4%) the A16V mutation, 2 had rare mutations, and 21 (19%) had no PRSS1 mutation. The median (95% confidence interval [CI]) time to first symptoms for R122H was 10 (8, 12) years of age, 14 (11, 18) years for N29I, and 14.5 (10, 21) years for mutation negative patients (P = 0.032). The cumulative risk (95% CI) at 50 years of age for exocrine failure was 37.2% (28.5%, 45.8%), 47.6% (37.1%, 58.1%) for endocrine failure, and 17.5% (12.2%, 22.7%) for pancreatic resection for pain. Time to resection was significantly reduced for females (P < 0.001) and those with the N29I mutation (P = 0.014). The cumulative risk (95% CI) of pancreatic cancer was 44.0% (8.0%, 80.0%) at 70 years from symptom onset with a standardized incidence ratio of 67% (50%, 82%). CONCLUSIONS: Symptoms in hereditary pancreatitis start in younger patients and endpoints take longer to be reached compared with other forms of chronic pancreatitis but the cumulative levels of exocrine and endocrine failure are much higher. There is an increasingly high risk of pancreatic cancer after the age of 50 years unrelated to the genotype.

Adult↗
PubMed2003

[Conservative treatment of acute pancreatitis].

The incidence of acute pancreatitis per 100,000 population ranges from 10 to 46. The mortality of acute edematous interstitial pancreatitis is < 1%, while patients suffering from hemorrhagic necrotizing pancreatitis die from their disease in 10-24%. 80% of all cases of acute pancreatitis are etiologically correlated to diseases of the biliary tract or an excess alcohol consumption. As of today, no specific and causal treatment for acute pancreatitis has been established. Early prognostic factors for the evaluation of the clinical course of acute eipancreatitis are three or more indicators of organ failure in the Ranson or Imrie score, the development of extrapancreatic complications or the detection of pancreatic necrosis on contrast-enhanced CT scans. Elevated C-reactive protein (CRP) levels > 130 mg/l can predict a severe course of acute pancreatitis with a high sensitivity. The foundation of medical treatment in acute pancreatitis is the substitution of fluids to counteract hypovolemia. Furthermore, the relief of sometimes severe visceral pain has the highest priority. Infusion of procaine has been found to be ineffective for this purpose. The use of antibiotics should be restricted to patients with pancreatic necrosis. Enteral nutrition has no adverse effect compared to parenteral nutrition and is likely to be beneficial to the course of pancreatitis.

APACHE↗
PubMed2003

p8 improves pancreatic response to acute pancreatitis by enhancing the expression of the anti-inflammatory protein pancreatitis-associated protein I.

p8 is a transcription cofactor whose expression is strongly and rapidly activated in pancreatic acinar cells during the acute phase of pancreatitis. A p8-deficient mouse strain was generated as a tool to investigate its function. Upon induction of acute pancreatitis, myeloperoxidase activity in pancreas and serum concentrations of amylase and lipase were much higher and pancreatic lesions more severe in p8-deficient mice than in wild-type, indicating that p8 expression decreased pancreatic sensitivity to pancreatitis induction. The protective mechanism might involve the pancreatitis-associated protein (PAP I), whose strong induction during pancreatitis is p8-dependent, because administration of anti-PAP I antibodies to rats increased pancreatic inflammation during pancreatitis. In addition, 100 ng/ml PAP I in the culture medium of macrophages prevented their activation by tumor necrosis factor alpha, strongly suggesting that PAP I was an anti-inflammatory factor. Finally, PAP I was able to inhibit NFkappaB activation by tumor necrosis factor alpha, in macrophages and in the AR42J pancreatic acinar cell line. In conclusion, p8 improves pancreatic resistance to inducers of acute pancreatitis by a mechanism implicating the expression of the anti-inflammatory protein PAP I.

Alleles↗
PubMed2003

Claudin-4 expression decreases invasiveness and metastatic potential of pancreatic cancer.

Claudin-4 has been identified as an integral constituent of tight junctions and has been found to be highly expressed in pancreatic cancer. The aim of the present study was to elucidate the effect of claudin-4 on growth and metastatic potential in pancreatic cancer cells, as well as the regulation of claudin-4 by oncogenic pathways. Claudin-4 was stably overexpressed in SUIT-2 pancreatic cancer cells, and its effect on invasion and growth in vitro was examined by using two-chamber invasion assays, soft agar assays, and fluorescence-activated cell sorter analysis. Claudin-4 localization was characterized by light and electron microscopy, and pulmonary colonization was analyzed in vivo after injection of claudin-4 overexpressing cells into the tail vein of nude mice. Overexpression of claudin-4 was associated with significantly reduced invasive potential in vitro and inhibited colony formation in soft agar assays. In vivo, tail vein-injected claudin-4 overexpressing cells formed significantly less pulmonary metastases in comparison with mock-transfected cells. These effects were not caused by changes in proliferation, cell cycle progression, or matrix metalloproteinase gelatinolytic activity, but were paralleled by increased cell contact formation. Moreover, proinvasive transforming growth factor beta was able to down-regulate claudin-4 in PANC-1 cells. Inhibition of Ras signaling by using dominant-negative Ras and specific inhibitors of both downstream effectors mitogen-activated protein/extracellular signal-regulated kinase kinase and phosphatidylinositol 3'-kinase also decreased claudin-4 expression. Our findings identify claudin-4 as a potent inhibitor of the invasiveness and metastatic phenotype of pancreatic cancer cells, and as a target of the transforming growth factor beta and Ras/Raf/extracellular signal-regulated kinase pathways.

Carcinoma, Pancreatic Ductal↗
PubMed2003

Early changes in pancreatic acinar cell calcium signaling after pancreatic duct obstruction.

Intracellular Ca(2+)-changes not only participate in important signaling pathways but have also been implicated in a number of disease states including acute pancreatitis. To investigate the underlying mechanisms in an experimental model mimicking human gallstone-induced pancreatitis, we ligated the pancreatic duct of Sprague-Dawley rats and NMRI mice for up to 6 h and studied intrapancreatic changes including the dynamics of [Ca(2+)](i) in isolated acini. In contrast to bile duct ligation, pancreatic duct obstruction induced intra-pancreatic trypsinogen activation, leukocytosis, hyperamylasemia, and pancreatic edema and increased lung myeloperoxidase activity. Although resting [Ca(2+)](i) in isolated acini rose by 45% to 205 +/- 7 nmol, the acetylcholine- and cholecystokinin (CCK)-stimulated calcium peaks as well as the amylase secretion declined, but neither the [Ca(2+)](i)-signaling pattern nor the amylase output in response to the Ca(2+)-ATPase inhibitor thapsigargin nor the secretin-stimulated amylase release were impaired by pancreatic duct ligation. On the single cell level pancreatic duct ligation reduced the percentage of cells in which submaximal secretagogue stimulation was followed by a physiological response (i.e. Ca(2+) oscillations) and increased the percentage of cells with a pathological response (i.e. peak plateau or absent Ca(2+) signal). Moreover, it reduced the frequency and amplitude of Ca(2+) oscillation as well as the capacitative Ca(2+) influx in response to secretagogue stimulation. Serum pancreatic enzyme elevation as well as trypsinogen activation was significantly reduced by pretreatment of animals with the calcium chelator BAPTA-AM. These experiments suggest that pancreatic duct obstruction rapidly changes the physiological response of the exocrine pancreas to a Ca(2+)-signaling pattern that has been associated with premature digestive enzyme activation and the onset of pancreatitis, both of which can be prevented by administration of an intracellular calcium chelator.

Adenosine Triphosphatases↗
PubMed2003

Gallstone pancreatitis: when is endoscopic retrograde cholangiopancreatography truly necessary?

Acute pancreatitis is an inflammation of the pancreas that can, in a minority of patients, lead to local complications, multiorgan failure, and death. Gallstones are the most common cause of acute pancreatitis in Western countries. The majority of patients with acute gallstone pancreatitis have mild disease and recover within 3 to 5 days with bed rest and intravenous fluid replacement. In up to 20% of patients, severe pancreatitis develops and can involve pancreatic tissue necrosis and multiorgan failure. Recent advances in the care of patients with gallstone-induced pancreatitis include better severity stratification on hospital admission, more aggressive fluid resuscitation in the early disease course, early use of antibiotics in patients with pancreatic necrosis, a shift from parenteral to enteral feeding regimens, a better defined and less aggressive approach to pancreatic surgery, and the possibility to remove impacted gallstones endoscopically. Urgent endoscopic retrograde cholangiopancreatography and sphincterotomy are recommended in patients with signs of cholangitis or jaundice, ultrasound evidence of dilated common bile duct, or evidence of severe disease.

APACHE↗
PubMed2003

Up-regulation, nuclear import, and tumor growth stimulation of the adhesion protein p120 in pancreatic cancer.

BACKGROUND & AIMS: Cell adhesion proteins have been implicated as tumor suppressors because they prevent malignant cells from dissociating their cell contacts. We have studied the role of p120(ctn), a recently discovered member of the cadherin/catenin family, in human pancreatic cancer. METHODS: In 32 resection specimens of pancreatic adenocarcinoma and 10 control samples the expression of p120(ctn) was studied by Northern blot, immunocytochemistry, and immunogold electron microscopy. Patient survival data, tumor grading, and staging were correlated to the experimental results. In PaTu 8889 T pancreatic cancer cells, p120(ctn) expression was suppressed with 21-nucleotide small interfering RNA (siRNA) duplexes and proliferation was determined by bromodeoxyuridine (BrdU) incorporation. RESULTS: In pancreatic cancer p120(ctn) messenger RNA (mRNA) was increased 3- to 4-fold. Although p120(ctn) was localized exclusively at cell contacts in controls it was found in the cytosol and nucleus of pancreatic cancer cells. This redistribution correlated to the degree of tumor dedifferentiation but was independent of tumor stage. The mean survival of patients with predominant membrane localization of p120(ctn) was 24 +/- 7 (SEM) months vs. 9 +/- 2 months for patients with predominant cytoplasmic p120(ctn) expression (P < 0.05). Silencing of p120(ctn) with siRNA duplexes reduced pancreatic cancer cell growth by 40%. CONCLUSIONS: Up-regulation, cytoplasmic redistribution, and nuclear import of p120(ctn) are associated with a more malignant phenotype of pancreatic cancer. This study further represents conclusive evidence for a direct involvement of p120(ctn) in malignant tumor cell proliferation. Both p120(ctn)-defective tumor cell contacts and p120(ctn)-mediated growth signals appear to contribute to the aggressive spread of pancreatic cancer.

Active Transport, Cell Nucleus↗
PubMed2003

Pathophysiology of alcohol-induced pancreatitis.

Excessive ethanol consumption is a common risk factor for acute and chronic pancreatitis. Ethanol could lead to the onset of pancreatitis in a number of ways; the most recently discovered is its effect on intrapancreatic digestive enzyme activation, by either sensitizing acinar cells to pathologic stimuli or stimulating the release of a secretagogue (cholecystokinin) from duodenal I cells. Recent advances in cell biologic and molecular techniques have permitted us to address the intracellular events involved in digestive enzyme activation in a manner that was previously considered impossible. Investigations that used these novel techniques found that (a) trypsin is, in contrast to its role in the small intestine, not necessarily involved in the premature intracellular activation of other digestive proteases such as proelastase; (b) trypsinogen does not autoactivate intracellularly but is instead largely activated by the lysosomal hydrolase cathepsin B; and (c) the role of trypsin in the intrapancreatic protease cascade is most likely one that involves the degradation, rather than the activation, of active digestive proteases including trypsin itself. These studies, as well as investigations that have addressed the role of mutant trypsin in the disease onset of hereditary pancreatitis, suggest that trypsin may not be critical for triggering pancreatitis but might have a protective role against the action of some of the other digestive proteases. While the specific role of different digestive enzymes in initiating pancreatitis is still a matter of debate and the topic of ongoing investigations, experimental evidence suggests that ethanol can directly interfere with the processes involved in digestive zymogen activation.

Acetaldehyde↗
PubMed2002

Presence of cathepsin B in the human pancreatic secretory pathway and its role in trypsinogen activation during hereditary pancreatitis.

The lysosomal cysteine protease cathepsin B is thought to play a central role in intrapancreatic trypsinogen activation and the onset of experimental pancreatitis. Recent in vitro studies have suggested that this mechanism might be of pathophysiological relevance in hereditary pancreatitis, a human inborn disorder associated with mutations in the cationic trypsinogen gene. In the present study evidence is presented that cathepsin B is abundantly present in the secretory compartment of the human exocrine pancreas, as judged by immunogold electron microscopy. Moreover, pro-cathepsin B and mature cathepsin B are both secreted together with trypsinogen and active trypsin into the pancreatic juice of patients with sporadic pancreatitis or hereditary pancreatitis. Finally, cathepsin B- catalyzed activation of recombinant human cationic trypsinogen with hereditary pancreatitis-associated mutations N29I, N29T, or R122H were characterized. In contrast to a previous report, cathepsin B-mediated activation of wild type and all three mutant trypsinogen forms was essentially identical under a wide range of experimental conditions. These observations confirm the presence of active cathepsin B in the human pancreatic secretory pathway and are consistent with the notion that cathepsin B-mediated trypsinogen activation might play a pathogenic role in human pancreatitis. On the other hand, the results clearly demonstrate that hereditary pancreatitis-associated mutations do not lead to increased or decreased trypsinogen activation by cathepsin B. Therefore, mutation-dependent alterations in cathepsin B-induced trypsinogen activation are not the cause of hereditary pancreatitis.

Blotting, Western↗
PubMed2002

Usual ductal hyperplasia of the breast is a committed stem (progenitor) cell lesion distinct from atypical ductal hyperplasia and ductal carcinoma in situ.

Current classification systems in proliferative mammary gland pathology are based on a two-cell system, recognizing only glandular and myoepithelial lines of differentiation. A third cell type has recently been characterized in normal breast tissue by double-immunofluorescence analysis to express cytokeratin 5 (Ck5) only. These cells were shown to represent progenitor or adult stem cells that give rise to the glandular and myoepithelial cell lineage. The double-labelling technique has been applied to characterize a spectrum of intraductal epithelial proliferations, namely benign usual ductal hyperplasia, atypical ductal hyperplasia, and ductal carcinoma in situ, all of which are thought to represent the gradual steps of a sequence in the development of breast cancer. Immunofluorescence studies with specific antibodies against Ck5, Ck8/18/19, and smooth muscle actin were complemented by western blotting analysis of Ck5 and Ck8/18/19 expression in normal breast tissue and in proliferative lesions. Usual ductal hyperplasia appears to be a Ck5-positive committed stem (progenitor) cell lesion with the same differentiation potential as seen in the normal breast. This is in sharp contrast to atypical ductal hyperplasia/ductal carcinoma in situ, which display the differentiated glandular immunophenotype (Ck8/18/19-positive, but Ck5-negative). These data require the abandonment of the idea of an obligate biological continuum of intraductal proliferations from benign to malignant. This study provides evidence that cells undergoing malignant transformation tend to be fairly advanced in the glandular lineage of differentiation. The committed stem (progenitor) cell model may contribute to a better understanding of both benign proliferative breast disease and breast cancer development.

Blotting, Western↗
PubMed2002

Vascular smooth muscle and nitric oxide synthase.

The concept of endothelium-derived relaxing factor (EDRF) put forward in 1980 by Furchgott and Zawadzki implies that nitric oxide (NO) produced by NO synthase (NOS) in the endothelium diffuses to the underlying vascular smooth muscle, where it modulates vascular tone as well as vascular smooth muscle cell (VSMC) proliferation by increasing cGMP formation with subsequent activation of cGMP-dependent protein kinase. According to this concept, VSMC do not express NOS by themselves. This attractive, simple scheme is now under considerable debate. To address this issue, we designed this study with the use of a novel supersensitive immunocytochemical technique of signal amplification with tyramide and electron microscopic immunogold labeling complemented with Western blotting, as in our recent studies demonstrating NOS in the myocardial and skeletal muscles. We provide the first evidence that, in contrast to the currently accepted view, VSMC in various blood vessels express all three NOS isoforms depending on the blood vessel type. These findings suggest an alternative mechanism by which local NOS expression may modulate vascular functions in an endothelium-independent manner.

Animals↗
PubMed2002

Common adult stem cells in the human breast give rise to glandular and myoepithelial cell lineages: a new cell biological concept.

Breast biology and pathology are currently shaped by the two-cell concept that recognizes only glandular and myoepithelial cells. In the present study, we have visualized a previously unidentified cell population within the epithelial compartment of the breast, which displays the phenotypic characteristics of a committed stem cell. Immunofluorescence double labeling with digital image processing and Western blotting were applied to normal breast tissue as well as to noninvasive and invasive breast cancers using antibodies to basal cytokeratin 5 (Ck5), glandular cytokeratins 8/18 (Ck8/18/19), and smooth muscle alpha-actin (SMA) as markers for myoepithelial cells (SMA). A distinct population of cells was identified that expressed Ck5 in the absence of Ck8/18/19 or SMA. These cells differentiate toward glandular epithelial or myoepithelial Ck5-negative end cells passing through either Ck5/Ck8/18/19 or Ck5/SMA-positive intermediates. Our experiments clearly demonstrate a precursor or committed stem cell function of the Ck5-positive cell that is responsible for regeneration of the human adult breast epithelium. However, the observation that the vast majority of breast cancers display the glandular epithelial immunophenotype strongly suggests that the neoplastic cells derive from a late stage of the glandular epithelial differentiation pathway. The significance of this new cell biological model is that it might serve as a tool to unravel the regulatory mechanisms that govern regeneration and abnormal proliferation of breast epithelium at the cellular level.

Actins↗
PubMed2002

Trypsin activity is not involved in premature, intrapancreatic trypsinogen activation.

A premature and intracellular activation of digestive zymogens is thought to be responsible for the onset of pancreatitis. Because trypsin has a critical role in initiating the activation cascade of digestive enzymes in the gut, it has been assumed that trypsin also initiates intracellular zymogen activation in the pancreas. We have tested this hypothesis in isolated acini and lobules from rat pancreas. Intracellular trypsinogen activation was induced by supramaximal secretagogue stimulation and measured using either specific trypsin substrates or immunoreactivity of the trypsinogen activation peptide (TAP). To prevent a trypsin-induced trypsinogen activation, we used the cell-permeant, highly specific, and reversible inhibitor Nalpha-(2-naphthylsulfonyl)-3-amidinophenylalanine-carboxymethylpiperazide (S124), and to prevent cathepsin-induced trypsinogen activation, we used the cysteine protease inhibitor E-64d. Incubation of acini or lobules in the presence of S124 completely prevented the generation of trypsin activity in response to supramaximal caerulein but had no effect whatsoever on the generation of TAP. Conversely, when trypsin activity was recovered at the end of the experiment by either washout of S124 from acini or extensive dilution of lobule homogenates, it was up to 400% higher than after caerulein alone and corresponded, in molar terms, to the generation of TAP. Both trypsin activity and TAP release were inhibited in parallel by E-64d. We conclude that caerulein-induced trypsinogen activation in the pancreas is caused by an E-64d-inhibitable mechanism such as cathepsin-induced trypsinogen activation, and neither involves nor requires intracellular trypsin activity. Specific trypsin inhibition, on the other hand, prevents 80% of trypsin inactivation or autodegradation in the pancreas.

Acute Disease↗
PubMed2001

Hereditary pancreatitis caused by a novel PRSS1 mutation (Arg-122 --> Cys) that alters autoactivation and autodegradation of cationic trypsinogen.

Hereditary pancreatitis has been found to be associated with germline mutations in the cationic trypsinogen (PRSS1) gene. Here we report a family with hereditary pancreatitis that carries a novel PRSS1 mutation (R122C). This mutation cannot be diagnosed with the conventional screening method using AflIII restriction enzyme digest. We therefore propose a new assay based on restriction enzyme digest with BstUI, a technique that permits detection of the novel R122C mutation in addition to the most common R122H mutation, and even in the presence of a recently reported neutral polymorphism that prevents its detection by the AflIII method. Recombinantly expressed R122C mutant human trypsinogen was found to undergo greatly reduced autoactivation and cathepsin B-induced activation, which is most likely caused by misfolding or disulfide mismatches of the mutant zymogen. The K(m) of R122C trypsin was found to be unchanged, but its k(cat) was reduced to 37% of the wild type. After correction for enterokinase activatable activity, and specifically in the absence of calcium, the R122C mutant was more resistant to autolysis than the wild type and autoactivated more rapidly at pH 8. Molecular modeling of the R122C mutant trypsin predicted an unimpaired active site but an altered stability of the calcium binding loop. This previously unknown trypsinogen mutation is associated with hereditary pancreatitis, requires a novel diagnostic screening method, and, for the first time, raises the question whether a gain or a loss of trypsin function participates in the onset of pancreatitis.

Amino Acid Sequence↗