Value of genetic testing in the management of pancreatitis

Alcohol-associated pancreatitis

Only a small proportion of heavy drinking individuals develop pancreatitis. The environmental and host cofactors shown to have an association with alcoholic pancreatitis are smoking and race. The known genetic variations and polymorphisms do not seem to play an important role in alcoholic pancreatitis. Newer developments in the understanding of complex disorders allow clinicians to understand better the role of cofactors and interactions between known and yet unknown environmental and genetic factors in causing alcoholic pancreatitis.

N34S mutation in the SPINK1 gene is not associated with alternative splicing

OBJECTIVES

Previous studies have shown an association between chronic pancreatitis (CP) and mutations, especially the N34S mutation, in the serine protease inhibitor Kazal type 1 (SPINK1) gene. But the underlying molecular mechanisms are unknown. The aberrant splicing caused by the cosegregating intronic mutations might play a role, but this hypothesis has not been tested. We here examined the messenger RNA sequences of the SPINK1 gene in patients carrying the mutations.

METHODS

RNA was isolated from the surgically resected pancreas of 2 CP patients carrying the homozygous N34S mutation and from the gastric biopsy specimen of a CP patient carrying the heterozygous [-215G>A; IVS3+2T>C] mutation. The entire coding region of the SPINK1 gene was amplified by reverse transcription-polymerase chain reaction, subcloned, and sequenced. The level of the wild-type SPINK1 transcript was assessed by real-time polymerase chain reaction.

RESULTS

Alternative splicing was not associated with the N34S mutation. On the other hand, the [-215G>A; IVS3+2T>C] mutation caused skipping of whole exon 3, where the trypsin binding site is located. This mutated protein was predicted to consist of 63 amino acids: deletion of amino acid sequence from residues 30 to 64 and shifting of reading frame at amino acid 65 with a novel stop codon. The expression of the wild-type SPINK1 transcript was decreased to 62% of the healthy control in the CP patient carrying the heterozygous [-215G>A; IVS3+2T>C] mutation.

CONCLUSIONS

Splicing mutation might represent a mechanism for SPINK1-associated CP, but the N34S mutation is not associated with alternative splicing.

Acute and recurrent pancreatitis in children: etiological factors

OBJECTIVES

To describe the clinical picture and outcome, and to assess the etiological factors of acute and recurrent pancreatitis in children.

METHODS

Thirty-six (65.5%) patients with acute and 19 (34.5%) with recurrent pancreatitis were studied. Mean age was 126 (41.3 SD) months; 27 (49.1%) were females.

SETTING

A pediatric referral hospital.

PERIOD

2000-2005.

DESIGN

Cross-sectional.

VARIABLES

Clinical and laboratory data and etiological factors.

STATISTICS

Chi2-test, Fisher test, OR, confidence interval, Student t-test and Mann-Whitney U-test.

RESULTS

The most frequent symptom in acute and recurrent pancreatitis was abdominal pain, followed by vomiting and ileus. The severity of pancreatitis and complications were similar in both groups. Biliary stones, family history of pancreatitis, drug ingestion and hypercalcemia occurred in both groups. Abdominal trauma and acute hepatitis A occurred in patients with acute pancreatitis; triglyceride>5.65 mmol/L, pancreas divisum and DeltaF508 mutation occurred in patients with recurrent pancreatitis. No difference was observed when frequency factors between study groups were compared.

CONCLUSIONS

The clinical picture and etiological factors were similar in both groups. Since one out of every three children with acute pancreatitis in this series presented recurrences, it was not considered to be a 'benign disease'. Fifteen different etiological factors were identified in two-thirds of the cases.

Human pancreatic digestive enzymes

A primary function of the pancreas is to produce digestive enzymes that are delivered to the small intestine for the hydrolysis of complex nutrients. Much of our understanding of digestive enzymes comes from studies in animals. New technologies and the availability of the sequence of the human genome allow for a critical review of older reports and assumptions based on animal studies. This report updates our understanding of human pancreatic digestive enzymes with a focus on new insights into the biology of human proteases, lipases and amylases.

Genetic issues in pediatric pancreatitis

The number of hospitalizations in children with acute and chronic pancreatitis is increasing and accounts for significant morbidity. Acute pancreatitis is a reversible event involving diffuse inflammation of the pancreas with variable involvement of other regional tissues, remote organs, or both, whereas chronic pancreatitis is a process that produces irreversible changes in the pancreatic structure and function. Mutations in the gene encoding cationic trypsinogen have recently been identified to be associated with hereditary pancreatitis. Genetic mutations in the pancreatic secretory trypsin inhibitor and the cystic fibrosis transmembrane conductance regulator have been described to play a role in the development of pancreatitis as well. Mutations in the cytokine target genes relating to regulation of inflammation are likely to be important in determining the severity of pancreatitis. These findings, along with the advances in cell biology, have contributed to a better understanding of the pathophysiology of pancreatic diseases.

Chronic pancreatitis

Chronic pancreatitis (CP) is characterised by pancreatic inflammation and fibrosis leading eventually to destruction of pancreatic parenchyma and loss of exocrine and endocrine function. A model of interactions between environmental triggers of pancreatic inflammation and disease susceptibility or modifying genes (including PRSS1, SPINK1 and CFTR) provides a framework within which to understand disease pathogenesis. Early in the disease, when fibrosis is mild and pancreatic damage limited, it is difficult to distinguish CP from recurrent acute pancreatitis (RAP) although it is likely these represent opposite ends of a spectrum of disease with a common aetiology in which CP represents either a later disease stage or disease in individuals predisposed to generate a chronic fibrogenic inflammatory response. Pain is a dominant feature resulting in part from neuroimmune interactions within the pancreas. Diagnosis at an early stage of disease is challenging, though in later stages is dependent upon the demonstration of pancreatic fibrosis and duct ectasia using one or more imaging modalities including transabdominal and endoscopic ultrasound, CT and MRCP or ERCP. Current treatments are largely supportive and reactive. The challenge for pediatricians is to achieve diagnosis at an early stage of the disease and to develop treatments that can alter its natural history.

Gene-environment factors that contribute to alcoholic pancreatitis in humans

Alcohol-associated acute and chronic pancreatitis occur in a minority of alcohol users, suggesting that most drinkers are protected from pancreatic diseases while a subset is susceptible. Ongoing studies suggest that the pathophysiology is complex and can involve multiple genetic and environmental pathways and stochastic events. Both rat models and human genetic epidemiology studies have been used to understand susceptibility and modifying factors in humans. Rat studies suggest that different types of altered pancreatic physiology occur depending on dose, they occur rapidly and that alcohol changes the immune response to recurrent pancreatic injury. Human studies suggest that PRSS1 and SPINK1 mutation increase the pancreas' susceptibility to alcohol-associated pancreatitis, and that tobacco smoking, and some factors, affect disease progression.

Polygenetic traits in pancreatic disorders

Rapid advances in information and technology provide opportunities to discover the risks or causes for various disorders within individual patients. The availability of new data and new technology has outstripped the conceptual framework of simple disorders,however, and challenges current statistical approaches. The author addresses the issues surrounding study design and sample size for complex genetic traits with special attention to meta-analysis and systems biology. The author concludes that meta-analysis should play a limited role in evaluating studies of complex genetic diseases. Instead, systems biology-based approaches should be developed to integrate multiple, focused, and mechanistic association studies, with the goal of assisting in the risk assessment of patients on a person-by-person basis.

Role of endoscopic evaluation in idiopathic pancreatitis: a systematic review

In approximately 20% of patients with acute pancreatitis, a cause is not established by history, physical examination, routine laboratory testing, and abdominal imaging. For those with a single unexplained attack, the role of invasive evaluation with endoscopic retrograde cholangiopancreatography is unsettled but has been generally limited to those patients with suspected bile duct stones or malignancy. Recent studies suggest that microlithiasis is causative in up to 75% of patients with an unexplained attack and gallbladder in situ, whereas sphincter of Oddi dysfunction is most prevalent in those with recurrent attacks who have previously undergone cholecystectomy. EUS has been shown to be highly accurate for the identification of gallbladder sludge, common bile duct stones, and pancreatic diseases. Given this apparent diagnostic utility, an EUS-based strategy may be a reasonable approach to evaluate patients with a single idiopathic attack. ERCP and sphincter of Oddi manometry should generally be reserved for patients with multiple unexplained attacks and negative EUS results, especially for those patients who have previously undergone cholecystectomy.

The MCP-1 -2518 A/G polymorphism is not a susceptibility factor for chronic pancreatitis

BACKGROUND AND AIMS

Chronic pancreatitis (CP) is an inflammatory process initiated by recurrent acute pancreatitis and characterized by progressive parenchyma destruction and fibrosis. Genetic factors influence susceptibility and modify progression. The monocyte chemotactic protein-1 (MCP-1) -2518 G allele, which modifies the severity of acute pancreatitis, was investigated as a susceptibility factor for CP.

METHODS

A genetic association study was performed on 177 CP patients and 116 healthy controls from the NAPS2 Study. The MCP-1 A/G genotype was determined by RFLP and confirmed by DNA sequencing.

RESULTS

Compared to the control group the MCP-1 -2518 genotypes were similar: A/A (57% vs. 50%), A/G (34.5% vs. 40%) and G/G (8.5% vs. 10%). These allele frequencies were not statistically different (p = 0.267).

CONCLUSIONS

Although the pro-inflammatory chemokine MCP-1 -2518 G allele is a severity factor for AP, it does not significantly alter susceptibility to CP.

Biochemical markers of acute pancreatitis

Serum amylase remains the most commonly used biochemical marker for the diagnosis of acute pancreatitis, but its sensitivity can be reduced by late presentation, hypertriglyceridaemia, and chronic alcoholism. Urinary trypsinogen-2 is convenient, of comparable diagnostic accuracy, and provides greater (99%) negative predictive value. Early prediction of the severity of acute pancreatitis can be made by well validated scoring systems at 48 hours, but the novel serum markers procalcitonin and interleukin 6 allow earlier prediction (12 to 24 hours after admission). Serum alanine transaminase >150 IU/l and jaundice suggest a gallstone aetiology, requiring endoscopic retrograde cholangiopancreatography. For obscure aetiologies, serum calcium and triglycerides should be measured. Genetic polymorphisms may play an important role in "idiopathic" acute recurrent pancreatitis.

Evaluating disorders with a complex genetics basis. the future roles of meta-analysis and systems biology

Growing evidence suggests that complex gene and environment interactions underlie a number of diseases including chronic inflammatory diseases of the digestive system. The rapid advances in information and technology provide opportunities to discover the risks or etiology for a variety of disorders within individual patients. However, the availability of new data and new technology has outstripped the conceptual framework of simple disorders and challenges current statistical approaches. Here we address the issues surrounding study design and sample size for complex genetic traits, with special attention to meta-analysis and systems biology. We conclude that meta-analysis should play a limited role in evaluating studies of complex genetic diseases. Instead, systems biology-based approaches should be developed to integrate multiple, focused, and mechanistic association studies with the goal of assisting in the risk assessment of patients on a person-by-person basis.

Mechanisms of disease: Advances in understanding the mechanisms leading to chronic pancreatitis

Chronic pancreatitis remains a challenging and frustrating clinical problem. In the past few years, however, advances in genetic and immunologic research have spawned new insights and approaches to chronic pancreatitis. Genetic and environmental risk assessment may help identify individuals who are likely to develop severe chronic pancreatitis early in the disease course, and allow targeted attention to reduce confounding risks and slow or prevent this problem in the future.

Chronic pancreatitis

PURPOSE OF REVIEW

As in our previous reviews, we endeavor to review important new observations in chronic pancreatitis made in the past year. We included articles, including review articles, only if they contained new observations or readdressed old questions and provided new insights into old and new concepts.

RECENT FINDINGS

Important observations include the following: (1) Strong association between cystic fibrosis transmembrane regulator dysfunction/mutations and 'recurrent acute pancreatitis', particularly in patients with pancreas divisum (2) Pancreas divisum may be incidental finding in recurrent acute pancreatitis (3) Smoking increases risk of chronic pancreatitis (4) Coxsackie B virus may increase severity of alcoholic chronic pancreatitis (5) CD4+ T cells and an immune reaction against amylase may play a role in pathogenesis of autoimmune pancreatitis (6) 2-(18F)-Fluro-2-deoxy-D-glucose positron emission tomography might be useful to detect pancreatic cancer in chronic pancreatitis patients at risk for developing pancreatic cancer, but contrast-enhanced Doppler ultrasound or endosonography may be as sensitive and better than contrast enhanced computed tomography (7) Superiority of surgery vs endotherapy for long term pain relief and weight gain in painful chronic pancreatitis (8) Early treatment of pain and malabsorption may improve life quality (9) Antifibrogenesis and fibrolytic agents as potential therapies.

SUMMARY

Ongoing basic and clinical research this past year has further characterized genetic, molecular and clinical aspects of chronic pancreatitis. The advent of predictable and lasting treatments of chronic pancreatitis is most likely to appear on the wings of carefully conducted studies targeting genetic and molecular mechanisms of chronic pancreatitis, particularly pancreatic fibrogenesis.

Inflammatory Markers of Disease Severity in Acute Pancreatitis

To date, CRP remains the single standard biochemical marker for predicting the severity of AP. Because the combination of clinico-physiological scores and CRP provides good information at 48 hours, research has focused on the predictive ability of various markers when applied in the initial 24 hours after admission to the hospital. After detailed review of the literature, the authors conclude that there is no single tool that serves as the optimal predictor of severity. There are, however, data supporting the use of certain tests to improve upon the clinician's early predictive ability on the subsequent course of AP. These include an APACHE II score greater than seven, IL-6 at the time of admission, and urine TAP, urine trypsinogen-2,and serum PMN-elastase at 24 hours (Box 1). These markers will only be able to help the clinician's predictive ability if they can be performed locally and if the results can be available in a timely manner. Future research should focus on markers such as procalcitonin, IL-8, IL-I ra, sTNFR,CAPAP, PLA-2, novel markers, and the combined use of more than one marker. The conventional research approach in predicting severity used in the last15 years has limitations and appears to have reached its maximal potential. Novel conceptions and approaches, such as identification of genetic polymorphisms that predispose to severe course and complications of AP, are needed for a quantum step forward.

Predictors of severity and necrosis in acute pancreatitis

C-reactive protein remains the single standard biochemical marker for predicting the severity of AP. Because the combination of clinical-physiological scores and CRP provide good information at 48 hours, research has focused on the predictive ability of various markers when applied in the initial 24 hours after admission to the hospital. After detailed review of the literature, the authors conclude that there is no single tool that serves as the optimal predictor of severity. There are, however, data that support the use of certain tests to improve upon the clinician's early predictive ability on the subsequent course of AP. These include an APACHE II score greater than 7 and IL-6 at the time of admission, and urine TAP, urine trypsinogen-2, and serum PMN elastase at 24 hours (Table 4). These markers only will be able to help the clinician's predictive ability if they can be performed locally and if the results can be available ina timely manner. Future research should focus on promising markers such as procalcitonin, IL-8, IL-I ra, sTNFR, CAPAP, PLA-2, novel markers, and the combined use of more than one marker. The conventional research approach in predicting severity used in the last 15 years has limitations and appears to have reached its maximal potential. Novel conceptions and approaches, such as identification of genetic polymorphisms that predispose to severe course and complications of AP or other approaches are needed for a quantum step forward.

Alcoholic pancreatitis

Without doubt, alcohol consumption is one of the most important considerations in adults with acute or chronic pancreatitis. Understanding chronic pancreatitis as a complex disorder in which complimentary factors are required for recurrent acute and late chronic pancreatitis to develop in subsets of patients is critical for the early diagnosis and management of these individuals. Recent pathophysiological and genetic findings represent the beginning of major diagnostic and treatment breakthroughs that are likely to continue for the foreseeable future. The information provided in this article should provide the physician with a fresh perspective and remind the clinician of the importance of an accurate and complete history, and the need to document the actual alcohol consumption, pattern of drinking, and raise appropriate concerns if signs of alcoholism are detected. If alcohol-associated pancreatitis is detected, then limitation of pancreatic damage, limitation of progression, or preventative intervention should become the major concern.

Pancreatitis in childhood

Inflammatory disease of the pancreas falls into two major classifications: acute and chronic. Acute pancreatitis is a reversible process, whereas chronic pancreatitis produces irreversible changes in the architecture and function of the pancreas. The recent finding that mutations in the gene encoding cationic trypsinogen are associated with hereditary pancreatitis, the identification of genes that increase the risk for developing chronic pancreatitis, and advances in cell biology have contributed greatly to our understanding of the molecular mechanisms leading to pancreatitis. Although pancreatitis is less common in children than in adults, it still occurs with regularity and should be considered in any child with acute or chronic abdominal pain. The major difference between pancreatitis in children and adults lies in the etiologies and outcome of acute pancreatitis and in the etiology of chronic pancreatitis. The treatment of acute and chronic pancreatitis is similar at all ages.