Establishment of trypsinogen-2 Amplification Luminescent Proximity Homogeneous Assay and its Application in Acute Pancreatitis

We aim to develop an amplified luminescence proximity homogeneous assay (AlphaLISA) for quantification of trypsinogen-2 levels in human serum for the diagnosis of acute pancreatitis. Based on new amplified luminescence proximity homogeneity assay (AlphaLISA) method, carboxyl-modified donor and acceptor beads were coupled to capture and detection antibodies. A double antibody sandwich immunoassay was used to detect the concentration of trypsinogen-2 in serum. The method had good linearity (> 0.998). The intra - analysis precision was between 1.54% and 2.20% (< 10%), the inter-analysis precision was between 3.17% and 6.94% (< 15%), and the recovery was between 96.23% and 103.45%. The cross-reactivity of carbohydrate antigen 242 (CA242) and T-cell immunoglobulin mucin-3 (Tim-3) were 0.09% and 0.93%, respectively. The detection time only needed 15 min. The results of trypsinogen-2-AlphaLISA and time-resolved fluorescence immunoassay were consistent (ρ = 0.9019). In addition, serum trypsinogen-2 concentration in patients with acute pancreatitis [239.23 (17.83-807.58) ng/mL] was significantly higher than that in healthy controls [20.54 (12.10-39.73) ng/mL]. When the cut-off value was 35.38ng/mL, the sensitivity and specificity were 91.8% and 96.67%, and the positive detection rate was 91.80%. We have successfully established a trypsinogen-2-AlphaLISA method, which can promote the timely diagnosis of acute pancreatitis.

Trypsin and Trypsinogen Activation Peptide in the Prediction of Severity of Acute Pancreatitis

OBJECTIVES

To assess the predictive value of serum trypsin and trypsinogen activation peptide (TAP) for the severity of AP through a single center cohort study as well as a systematic review of the current literature.

METHODS

A literature search was conducted using Medline (PubMed), EMBASE and the Cochrane Central Register. A total of 142 patients with acute pancreatitis (AP) were included in the cohort study and parameters of the revised Atlanta criteria of 2012 and the APACHE II were assessed.

RESULTS

The review showed promising results for the predictive value of serum trypsinogen-2 but conflicting results for serum TAP and trypsin. In the cohort study, patients were observed for 4 days after diagnosis of AP; 9 patients had severe AP, 35 patients had moderate AP and 81 patients had mild AP. The ratio of the geometric mean of severe vs. mild AP for trypsin was 0.72 (95% CI: 0.51-1.00), p = 0.053 and, for TAP, 0.74 (95% CI: 0.54-1.01), p = 0.055, respectively.

CONCLUSIONS

The cohort study showed an inverse correlation of serum levels of TAP and trypsin with severity of AP. Serum TAP and trypsin have an inferior predictive value of severity of AP compared to the clinical APACHE II score.

Methodologies for the Determination of Blood Alpha1 Antitrypsin Levels: A Systematic Review

Background: The study of hematic concentrations of alpha1 antitrypsin (AAT) is currently one step in the diagnosis of AAT deficiency. To try to clarify the relevance of the laboratory techniques, we carried out a systematic review of the literature. Methods: Studies evaluating the quantification of AAT in peripheral blood were searched in PubMed in July 2021. The selection criteria included (1) any type of study design that included a quantification of AAT in peripheral blood; (2) studies written in English or Spanish; (3) studies evaluating human beings; and (4) studies involving adults. Results: Out of 207 studies, the most frequently used techniques were nephelometry (43.9%), followed by ELISA (19.8%) and turbidimetry (13.5%). Altogether, 182 (87.9%) cases expressed their results in units of gram, while 16 (7.7%) articles expressed them in units of mole. Only 2.9% articles referred to the standard used, 43.5% articles indicated the commercial kit used, and 36.2% indicated the analyzer used. Conclusions: The technical aspects of these determinations are not always reported in the literature. Journals should be attentive to these technical requirements and ensure that they are included in the works in which AAT is determined in order to ensure a correct interpretation of the study findings.

Dramatic increase in serum trypsinogens, SPINK1 and hCGβ in aortic surgery patients after hypothermic circulatory arrest

The concentrations of several diagnostic markers have been found to increase dramatically in critically ill patients with a severe disturbance of normal physiological homeostasis, without indication of the diseases they are normally associated with. To prevent false diagnoses and inappropriate treatments of critically ill patients, it is important that the markers aiding the selection of second-line treatments are evaluated in such patients and not only in the healthy population and patients with diseases the markers are associated with. The levels of trypsinogen isoenzymes, the trypsin inhibitor serine peptidase inhibitor Kazal type 1 (SPINK1), hCG and hCGβ, which are used as pancreatitis and cancer markers, were analyzed by immunoassays from serum samples of 17 adult patients who have undergone surgery of the ascending aorta during hypothermic circulatory arrest (HCA) with optional selective cerebral perfusion. Highly elevated levels of trypsinogen-1, -2 and -3, SPINK1 and hCGβ were observed in patients after HCA. This was accompanied by increased concentrations of S100β and NSE. In conclusion, this study highlights the importance of critically evaluating the markers used for aiding selection of second line of treatments in critically ill patients.

Serum Serine Peptidase Inhibitor Kazal-Type 1, Trypsinogens 1 to 3, and Complex of Trypsin 2 and α1-Antitrypsin in the Diagnosis of Severe Acute Pancreatitis

OBJECTIVES

We explored prediction of severe acute pancreatitis (AP) and development of organ dysfunction (OD).

METHODS

Serum concentrations of serine peptidase inhibitor Kazal type 1 (SPINK1), trypsinogen 1, trypsinogen 2, and trypsinogen 3, complex between trypsin 2 and α1-antitrypsin, serum C-reactive protein, creatinine, and pancreatic amylase were measured in 239 AP patients with disease onset within 72 hours.

RESULTS

SPINK1 distinguished most accurately patients who later developed severe AP. The area under the receiver operating characteristic curve for SPINK1 was 0.742, followed by trypsinogen 2 (0.726), complex between trypsin 2 and α1-antitrypsin (0.657), creatinine (0.656), trypsinogen 1 (0.652), trypsinogen 3 (0.557), and C-reactive protein (0.499). With a cutoff of 166 μg/L, SPINK1 had a specificity of 93%, a sensitivity of 48%, and diagnostic odds ratio of 11.52. In multivariate logistic regression analysis, only SPINK1 was an independent predictor of severe AP among patients presenting without OD on admission (P < 0.001).

CONCLUSIONS

Plasma levels of the biomarkers and creatinine correlated with the severity of AP and development of OD. In patients presenting without OD at admission, SPINK1 was an independent marker for later development of severe AP.

Serum amylase and lipase and urinary trypsinogen and amylase for diagnosis of acute pancreatitis

BACKGROUND

The treatment of people with acute abdominal pain differs if they have acute pancreatitis. It is important to know the diagnostic accuracy of serum amylase, serum lipase, urinary trypsinogen-2, and urinary amylase for the diagnosis of acute pancreatitis, so that an informed decision can be made as to whether the person with abdominal pain has acute pancreatitis. There is currently no Cochrane review of the diagnostic test accuracy of serum amylase, serum lipase, urinary trypsinogen-2, and urinary amylase for the diagnosis of acute pancreatitis.

OBJECTIVES

To compare the diagnostic accuracy of serum amylase, serum lipase, urinary trypsinogen-2, and urinary amylase, either alone or in combination, in the diagnosis of acute pancreatitis in people with acute onset of a persistent, severe epigastric pain or diffuse abdominal pain.

SEARCH METHODS

We searched MEDLINE, Embase, Science Citation Index Expanded, National Institute for Health Research (NIHR HTA and DARE), and other databases until March 2017. We searched the references of the included studies to identify additional studies. We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively. We also performed a 'related search' and 'citing reference' search in MEDLINE and Embase.

SELECTION CRITERIA

We included all studies that evaluated the diagnostic test accuracy of serum amylase, serum lipase, urinary trypsinogen-2, and urinary amylase for the diagnosis of acute pancreatitis. We excluded case-control studies because these studies are prone to bias. We accepted any of the following reference standards: biopsy, consensus conference definition, radiological features of acute pancreatitis, diagnosis of acute pancreatitis during laparotomy or autopsy, and organ failure. At least two review authors independently searched and screened the references located by the search to identify relevant studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from the included studies. The thresholds used for the diagnosis of acute pancreatitis varied in the trials, resulting in sparse data for each index test. Because of sparse data, we used -2 log likelihood values to determine which model to use for meta-analysis. We calculated and reported the sensitivity, specificity, post-test probability of a positive and negative index test along with 95% confidence interval (CI) for each cutoff, but have reported only the results of the recommended cutoff of three times normal for serum amylase and serum lipase, and the manufacturer-recommended cutoff of 50 mg/mL for urinary trypsinogen-2 in the abstract.

MAIN RESULTS

Ten studies including 5056 participants met the inclusion criteria for this review and assessed the diagnostic accuracy of the index tests in people presenting to the emergency department with acute abdominal pain. The risk of bias was unclear or high for all of the included studies. The study that contributed approximately two-thirds of the participants included in this review was excluded from the results of the analysis presented below due to major concerns about the participants included in the study. We have presented only the results where at least two studies were included in the analysis.Serum amylase, serum lipase, and urinary trypsinogen-2 at the standard threshold levels of more than three times normal for serum amylase and serum lipase, and a threshold of 50 ng/mL for urinary trypsinogen-2 appear to have similar sensitivities (0.72 (95% CI 0.59 to 0.82); 0.79 (95% CI 0.54 to 0.92); and 0.72 (95% CI 0.56 to 0.84), respectively) and specificities (0.93 (95% CI 0.66 to 0.99); 0.89 (95% CI 0.46 to 0.99); and 0.90 (95% CI 0.85 to 0.93), respectively). At the median prevalence of 22.6% of acute pancreatitis in the studies, out of 100 people with positive test, serum amylase (more than three times normal), serum lipase (more than three times normal), and urinary trypsinogen (more than 50 ng/mL), 74 (95% CI 33 to 94); 68 (95% CI 21 to 94); and 67 (95% CI 57 to 76) people have acute pancreatitis, respectively; out of 100 people with negative test, serum amylase (more than three times normal), serum lipase (more than three times normal), and urinary trypsinogen (more than 50 ng/mL), 8 (95% CI 5 to 12); 7 (95% CI 3 to 15); and 8 (95% CI 5 to 13) people have acute pancreatitis, respectively. We were not able to compare these tests formally because of sparse data.

AUTHORS' CONCLUSIONS

As about a quarter of people with acute pancreatitis fail to be diagnosed as having acute pancreatitis with the evaluated tests, one should have a low threshold to admit the patient and treat them for acute pancreatitis if the symptoms are suggestive of acute pancreatitis, even if these tests are normal. About 1 in 10 patients without acute pancreatitis may be wrongly diagnosed as having acute pancreatitis with these tests, therefore it is important to consider other conditions that require urgent surgical intervention, such as perforated viscus, even if these tests are abnormal.The diagnostic performance of these tests decreases even further with the progression of time, and one should have an even lower threshold to perform additional investigations if the symptoms are suggestive of acute pancreatitis.

Clinical Value of Severity Markers in Acute Pancreatitis

Acute pancreatitis is a common digestive disease of which the severity may vary from mild, edematous to severe, necrotizing disease. An improved outcome in the severe form of the disease is based on early identification of disease severity and subsequent focused management of these high-risk patients. However, the ability of clinicians to predict, upon presentation, which patient will have mild or severe acute pancreatitis is not accurate. Prospective systems using clinical criteria have been used to determine severity in patients with acute pancreatitis, such as the Ranson's prognostic signs, Glasgow score, and the acute physiology and chronic health evaluation II score (APACHE II). Their application in clinical practise has been limited by the time delay of at least 48 h to judge all parameters in the former two and by being cumbersome and time-consuming in the latter. Contrast-enhanced computed tomography is presently the most accurate non-invasive single method to evaluate the severity of acute pancreatitis. It cannot, however, be performed to all patients with acute pancreatitis. Therefore, considerable interest has grown in the development of reliable biochemical markers that reflect the severity of acute pancreatitis. In this article we critically appraise current and new severity markers of acute pancreatitis in their ability to distinguish between mild and severe disease and their clinical utility.

Biomarker development, from bench to bedside

This review describes studies performed by our group and other laboratories in the field aimed at development of biomarkers not only for cancer but also for other diseases. The markers covered include tumor-associated trypsin inhibitor (TATI), tumor-associated trypsin (TAT), human chorionic gonadotropin (hCG), prostate-specific antigen (PSA) and their various molecular forms, their biology and diagnostic use. The discovery of TATI was the result of a hypothesis-driven project aimed at finding new biomarkers for ovarian cancer among urinary peptides. TATI has since proved to be a useful prognostic marker for several cancers. Recently, it has been named Serine Peptidase Inhibitor Kazal Type 1 (SPINK1) after being rediscovered by several groups as a tumor-associated peptide by gene expression profiling and proteomic techniques and shown to promote tumor development by stimulating the EGF receptor. To explain why a trypsin inhibitor is strongly expressed in some cancers, research focused on the protease that it inhibited led to the finding of tumor-associated trypsin (TAT). Elevated serum concentrations of TAT-2 were found in some cancer types, but fairly high background levels of pancreatic trypsinogen-2 limited the use of TAT-2 for cancer diagnostics. However, trypsinogen-2 and its complex with α1-protease inhibitor proved to be very sensitive and specific markers for pancreatitis. Studies on hCG were initiated by the need to develop more rapid and sensitive pregnancy tests. These studies showed that serum from men and non-pregnant women contains measurable concentrations of hCG derived from the pituitary. Subsequent development of assays for the subunits of hCG showed that the β subunit of hCG (hCGβ) is expressed at low concentrations by most cancers and that it is a strong prognostic marker. These studies led to the formation of a working group for standardization of hCG determinations and the development of new reference reagents for several molecular forms of hCG. The preparation of intact hCG has been adopted as the fifth international standard by WHO. Availability of several well-defined forms of hCG made it possible to characterize the epitopes of nearly 100 monoclonal antibodies. This will facilitate design of immunoassays with pre-defined specificity. Finally, the discovery of different forms of immunoreactive PSA in serum from a prostate cancer patient led to identification of the complex between PSA and α1-antichymotrypsin, and the use of assays for free and total PSA in serum for improved diagnosis of prostate cancer. Epitope mapping of PSA antibodies and establishment of PSA standards has facilitated establishment well-standardized assays for the various forms of PSA.

Specific Immunoassay Reveals Increased Serum Trypsinogen 3 in Acute Pancreatitis

BACKGROUND

Trypsinogen 3 is a minor trypsinogen isoform in the pancreas. In contrast with trypsin 1 and 2, trypsin 3 degrades pancreatic secretory trypsin inhibitor, which may lead to an excess of active trypsin and acute pancreatitis (AP). We developed an immunoassay for trypsinogen 3 and studied whether an assay of serum trypsinogen 3 is of clinical utility in the diagnosis of AP.

METHODS

Monoclonal antibodies were generated using recombinant human trypsinogen 3 as the antigen and used to establish a sandwich-type immunoassay. We analyzed serum trypsinogen 3 concentrations in 82 patients with AP and 63 patients with upper abdominal pain (controls). The reference interval was determined using serum samples from 172 apparently healthy individuals.

RESULTS

The measuring range of the trypsinogen 3 assay was 1.0–250 μg/L. Intra- and interassay CVs were &lt;11%, and cross-reactivity with other trypsinogen isoenzymes was &lt;0.1%. The median trypsinogen 3 concentration in serum from healthy individuals was &lt;1.0 μg/L, and the upper reference limit was 4.4 μg/L. We observed increased trypsinogen 3 concentrations in patients with mild (median 9.5 μg/L) and severe (15.0 μg/L) AP; in both groups, the concentrations were significantly higher than in controls (median &lt;1.0 μg/L) (P &lt; 0.0001). In ROC analysis, the area under the curve of trypsinogen 3 for separation between AP and controls was 0.90 (P &lt; 0.0001).

CONCLUSIONS

We established for the first time a specific immunoassay for trypsinogen 3 using monoclonal antibodies. Patients with AP were found to have increased serum concentrations of trypsinogen 3. The availability of this assay will be useful for studies of the clinical utility of trypsinogen 3.

Assessment of trypsinogen-2 levels as an early diagnostic for post-endoscopic retrograde cholangiopancreatography pancreatitis

OBJECTIVES

The objective of the present study was to assess the use of serum trypsinogen-2 (TRY-2) measurements in early diagnosis of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP).

METHODS

In this prospective study, investigation 1 involved collection of blood serum both before and at 2, 4, and 18 hours after ERCP, whereas investigation 2 involved collection before and 1, 2, 3, 4, 6, and 18 hours after ERCP. Total amylase, pancreatic amylase, and TRY-2 levels were measured from serum samples, and values from patients with pancreatitis after ERCP were compared to those from healthy control patients after ERCP.

RESULTS

In investigation 1, 8 of the 68 cases examined were diagnosed as post-ERCP pancreatitis. In the healthy group, total- and pancreatic-amylase levels peaked 4 hours after ERCP, and TRY-2 levels peaked at 2 hours after ERCP. In contrast, cases of post-ERCP pancreatitis demonstrated prolonged periods of high total-amylase, pancreatic-amylase, and TRY-2 levels. In investigation 2, none of the 23 cases was diagnosed as post-ERCP pancreatitis: Pancreatic amylase levels peaked 4 to 6 hours after ERCP and TRY-2 levels peaked 1 hour after ERCP.

CONCLUSION

These results suggest that TRY-2 is a more sensitive marker than amylase, and it can be useful in early diagnosis of post-ERCP pancreatitis.

Urinary matrix metalloproteinase -8, -9, -14 and their regulators (TRY-1, TRY-2, TATI) in patients with diabetic nephropathy

Matrix metalloproteinase-9 (MMP-9) has been shown to be involved in the development of diabetic nephropathy (DNP). We studied the levels, molecular forms, and degree of activation of urinary MMP-8, -9, -14, trypsin-1 and -2, as well as tumor-associated trypsin inhibitor (TATI) of DNP patients and healthy controls. Urinary samples were analyzed for MMPs by Western blotting and gelatin zymography and for trypsin-1, -2, and TATI by time-resolved immunofluorometric assays. Total MMP-8 immunoreactivity, the proportion of active MMP-9, and gelatinolytic activity in urine were significantly higher in DNP patients than in controls. In urine of DNP patients the proportion of active polymorphonuclear neutrophil (PMN)-type (but not fibroblast-type) MMP-8 was increased. MMP-8 and MMP-9 were found to form high molecular weight complexes in DNP urine. Total immunoreactivity of soluble urinary MMP-14 and the levels of trypsin (TRY)-1 and TRY-2, but not of TATI, were also significantly increased in DNP. Zymography, Western blotting, and immunofluorometric analysis of DNP urine showed a significant association especially between activation of MMP-9 as well as PMN-type MMP-8 and TRY-2. Our findings suggest that a trypsin-MMP cascade is involved in the pathogenesis of DNP, which may offer new possibilities for diagnosis and treatment of DNP with MMP inhibitors.

Enhanced detection of cholangiocarcinoma with serum trypsinogen-2 in patients with severe bile duct strictures

BACKGROUND/AIMS

Primary sclerosing cholangitis (PSC) is associated with a high risk of cholangiocarcinoma. Our aim was to evaluate the diagnostic value of trypsinogen-1, trypsinogen-2, tumour-associated trypsin inhibitor, human chorionic gonadotropin beta and trypsin-2-alpha(1)-antitrypsin for cholangiocarcinoma and to compare them with CA19-9 and CEA.

METHODS

The study consisted of 84 patients with either PSC or cholangiocarcinoma or both referred for liver transplantation or other liver surgery. The serum concentrations were determined by time-resolved immunofluorometric assays.

RESULTS

Forty-six patients were transplanted due to PSC; in 3 of the explanted livers cholangiocarcinoma was found incidentally. All transplanted patients had severe biliary strictures together with cirrhosis or pre-cirrhosis. Twenty-nine of 38 patients with cholangiocarcinoma were candidates for intervention. In all, 8 patients had both PSC and cholangiocarcinoma. Receiver-operating characteristics curve analysis showed that serum trypsinogen-2 had the highest accuracy in differentiating between cholangiocarcinoma and PSC. The area under the curve (AUC) value was 0.804 for trypsinogen-2 and 0.613 for CA19-9. Serum trypsinogen-2 also showed the highest accuracy for differentiation between PSC and PSC with simultaneous cholangiocarcinoma with an AUC value of 0.759.

CONCLUSIONS

Our results suggest that serum trypsinogen-2 is a most useful marker for diagnosing patients with cholangiocarcinoma, and it is superior to serum CA19-9 and CEA.

Biochemistry and clinical role of trypsinogens and pancreatic secretory trypsin inhibitor

Trypsinogens and PSTI/TATI/SPINK1 are expressed, usually together, at high levels by the pancreas but also by many other normal and malignant tissues. The present review describes studies on the expression and putative functions of trypsinogens and PSTI/TATI/SPINK1 in the human body. The clinical aspects are discussed, including the correlations between expression of trypsinogens and PSTI/TATI/SPINK1 in tissues, serum, and urine of patients with pancreatitis or cancer and clinicopathological characteristics, i.e., the roles of trypsinogens and PSTI/TATI/SPINK1 in spontaneous and hereditary pancreatitis, tumor progression, and prognosis.

Trypsin-2 degrades human type II collagen and is expressed and activated in mesenchymally transformed rheumatoid arthritis synovitis tissue

It has traditionally been believed that only the human collagenases (matrix metalloproteinase-1, -8, and -13) are capable of initiating the degradation of collagens. Here, we show that human trypsin-2 is also capable of cleaving the triple helix of human cartilage collagen type II. We purified human trypsin-2 and tumor-associated trypsin inhibitor by affinity chromatography whereas collagen type II was purified from cartilage extracts using pepsin digestion and salt precipitation. Degradation of type II collagen and gelatin by trypsin-2 was demonstrated with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, zymography, and mass spectrometry, and tumor-associated trypsin inhibitor specifically inhibited this degradation. Although human trypsin-2 efficiently digested type II collagen, bovine trypsin did not. Furthermore, immunohistochemical staining detected trypsin-2 in the fibroblast-like synovial lining and in stromal cells of human rheumatoid arthritis synovial membrane. These findings were confirmed by reverse transcriptase-polymerase chain reaction and nucleotide sequencing. Trypsin-2 alone and complexed with alpha(1)-proteinase inhibitor were also detected in the synovial fluid of affected joints by time-resolved immunofluorometric assay, suggesting that trypsin-2 is activated locally. These results are the first to assess the ability of human trypsin to cleave human type II collagen. Thus, trypsin-2 and its regulators should be further studied for use as markers of prognosis and disease activity in rheumatoid arthritis.

Early sequential changes in serum markers of acute pancreatitis induced by endoscopic retrograde cholangiopancreatography

BACKGROUND/AIMS

Trypsinogen activation is thought to play a crucial role in the pathogenesis of acute pancreatitis (AP). Our aim was to characterize the very early sequential changes of trypsinogen-1, trypsinogen-2, the trypsin-2-alpha1-antitrypsin complex (T2-AAT), and pancreatic secretory trypsin inhibitor (PSTI) in serum from patients with pancreatitis induced by endoscopic retrograde cholangiopancreatography (ERCP), a model for studying the early phase of the disease in humans.

PATIENTS AND METHODS

The study population consisted of 659 consecutive patients with 897 ERCP procedures. Blood samples were obtained before and at different time points after the procedure. The serum concentrations of trypsinogen-1 and trypsinogen-2, PSTI and T2-AAT were determined by time-resolved immunofluorometric assays.

RESULTS

ERCP-induced pancreatitis developed after 50 of the 897 ERCP procedures (5.6%). Sixty-one randomly selected ERCP patients without post-ERCP pancreatitis served as controls. Trypsinogen-1 and trypsinogen-2 showed an equally steep increase during the two first hours after ERCP in patients developing AP, but trypsinogen-1 decreased more rapidly than trypsinogen-2, which remained elevated during the 5-day study period. Serum PSTI also increased rapidly whereas T2-AAT increased more slowly peaking at 24 h. In patients developing post-ERCP pancreatitis the median concentration of trypsinogen-1 was markedly higher than in the controls already before the ERCP procedure. In the control group the concentrations of trypsinogen-1, trypsinogen-2, PSTI and T2-AAT did not change significantly.

CONCLUSIONS

The rapid increase of trypsinogen-1 and trypsinogen-2 and PSTI in the early phase of AP suggests that release of pancreatic enzymes is the initial event while the delayed increase of T2-AAT may reflect that the capacity of the intrapancreatic PSTI-based inhibitory mechanism has been exhausted.

Expression of trypsinogen-1, trypsinogen-2, and tumor-associated trypsin inhibitor in ovarian cancer: prognostic study on tissue and serum

PURPOSE

The purpose is to study the prognostic significance of tissue expression of trypsinogen-1, trypsinogen-2, and tumor-associated trypsin inhibitor (TATI) and serum concentration of trypsinogen-2, trypsin-2-API (complex of trypsin-2 with alpha-1-proteinase inhibitor), and TATI in epithelial ovarian cancer.

EXPERIMENTAL DESIGN

Expression of trypsinogen-1, trypsinogen-2, and TATI was determined by immunohistochemistry with monoclonal antibodies in tissue sections of tumors from 119 patients with untreated primary epithelial ovarian cancer. Preoperative serum concentrations of trypsinogen-2, trypsin-2-API and TATI were analyzed using specific immunoassays.

RESULTS

Fifty-four percent of the tumors expressed trypsinogen-1, 45% expressed trypsinogen-2, and 30% expressed TATI. In patients with stage III and IV disease, TATI tissue expression (P = 0.002) and elevated TATI concentration in serum (P = 0.048) were associated with adverse cancer-specific and progression-free survival in univariate analysis. In multivariate analysis, TATI tissue expression (P = 0.005), tumor grade (P = 0.0001), histological type (P = 0.02), and stage (P = 0.0005) were independent prognostic factors for adverse cancer-specific survival and TATI tissue expression (P = 0.006) and grade (P = 0.0003) for progression-free survival. In multivariate analysis of all patients and those with advanced disease, serum trypsin-2-API concentration was an adverse prognostic factor for cancer-specific and progression-free survival, and it was independent of stage and histological type of the tumor (P <or= 0.01).

CONCLUSIONS

Tissue expression of TATI and an elevated preoperative serum concentration of trypsin-2-API are strong independent prognostic factors in advanced epithelial ovarian cancer. These results suggest that trypsin expression plays a role in the progression of ovarian cancer. TATI and trypsin-2-API are of potential use as an aid for stratification of randomized studies and for selecting treatment strategies.

Trypsinogen-2 and trypsinogen activation peptide (TAP) in urine of patients with acute pancreatitis

BACKGROUND AND AIMS

There is an obvious clinical need for a simple test that can identify patients at risk of developing severe acute pancreatitis. In this work we compared urinary trypsinogen-2 with urinary trypsinogen activation peptide (TAP) and serum C-reactive protein (CRP) for early differentiation between mild and severe acute pancreatitis.

PATIENTS AND METHODS

The study population consisted of 127 consecutive patients with acute pancreatitis of whom 29 had severe disease. Urinary trypsinogen-2 was measured by a quantitative immunofluorometric assay and TAP by a competitive immunoassay. Serum CRP was determined by immunoturbidimetry.

RESULTS

The sensitivity and specificity to identify severe acute pancreatitis on admission was 72% and 81% for urinary trypsinogen-2, 64% and 82% for urinary TAP, and 29% and 93% for serum CRP, respectively. At 24 h after admission, the values were 82% and 78% for urinary trypsinogen-2, 52% and 92% for urinary TAP, and 84% and 72% for serum CRP, respectively. Receiver-operating characteristics curve analysis showed that the area under the curve was larger for urinary trypsinogen-2 than for urinary TAP and serum CRP on admission and 24 h after admission. On admission the positive likelihood ration for urinary trypsiongen-2 was 3.7, for urinary TAP 3.6, and 4.3 for serum CRP, respectively. The corresponding negative likelihood ratios were 0.34, 0.43, and 0.76, respectively.

CONCLUSION

Urinary trypsinogen-2 was superior to serum CRP and as god as or even better than urinary TAP and in the early prediction of disease severity in acute pancreatitis. These results suggest that it could be a valuable adjunct in the early assessment of the severity of acute pancreatitis.

The usefulness of laboratory tests in the early assessment of severity of acute pancreatitis

Acute pancreatitis is a disorder that affects approximately 200,000 individuals in the U.S. annually. While most cases are mild, up to 30% of patients will have a complicated course with prolonged hospitalization and significant morbidity and mortality. Early institution of several therapeutic interventions, such as enteral nutrition, prophylactic antibiotics, endoscopic retrograde cholangiopancreatography (ERCP) and intensive care monitoring, have been shown to decrease the morbidity associated with severe acute pancreatitis. However, the ability of clinicians to predict, upon presentation, which patient will have mild or severe pancreatitis has remained poor over the years, thus leading to a delay in the institution of such treatments. Researchers have focused on markers that might improve upon clinical prediction alone. While data have shown the predictive value of tools such as Ranson's and Glasgow's criteria, C-reactive protein (CRP) and the APACHE score, their application in clinical practice has been limited by a time delay of at least 48 h in the former two and by being cumbersome in the latter. Thus, our focus is to critically appraise the evidence available for various biochemical markers in their ability to distinguish mild and severe acute pancreatitis early and more accurately than currently available tools.

New laboratory tests in acute pancreatitis

Acute pancreatitis (AP) is a common disease with wide variation of severity. The diagnosis of AP is usually based on high serum amylase or lipase values but the accuracy of these methods is considered unsatisfactory. One in five of the patients develops a severe disease and carries a considerable risk of development of organ failure and high mortality. Early detection of patients with severe AP and especially those with increased risk of organ failure is importance since such patients seem to benefit from treatment in an intensive care unit started as soon as possible after presentation. In addition to enzymological methods, increasing interest has been focused on laboratory markers reflecting the level of inflammatory response in AP. At present, in routine clinical work the most commonly used severity marker is serum C-reactive protein, the concentration of which rises too slowly to be used for early prediction of severity. New therapies aiming at modifying the course of systemic inflammation in AP are being developed and therefore monitoring the patient's immune inflammatory status is needed. In this review article we present the current knowledge of laboratory tests, which has been evaluated for diagnostic and prognostic purposes in AP.

A comparison of serum trypsinogen-2 and trypsin-2-alpha1-antitrypsin complex with lipase and amylase in the diagnosis and assessment of severity in the early phase of acute pancreatitis

OBJECTIVE

The aim of the study was to compare the recently introduced laboratory markers trypsinogen-2 and trypsin-2-alpha1 antitrypsin complex (trypsin-2-AAT) in serum with lipase and amylase in the diagnostic and prognostic evaluation of patients with acute pancreatitis (AP).

METHODS

The analytes were measured on admission in 64 consecutive patients with AP and in 30 controls with acute abdominal disease of extrapancreatic origin. Twenty-one patients had severe and 43 mild AP. As reference methods we used serum amylase and C-reactive protein.

RESULTS

In subjects with AP, elevated trypsinogen-2 values (> or = 90 microg/L) were observed in 63 patients (98%), trypsin-2-AAT values (> or = 12 microg/L) in 64 patients (100%), lipase values (> or = 200 U/L) in 64 patients (100%), and amylase values (> or = 300 IU/L) in 62 patients (97%). The diagnostic accuracy of the markers was evaluated by receiver operating characteristic (ROC) analysis. On admission, trypsinogen-2, trypsin-2-AAT, lipase, and amylase differentiated patients with AP from controls with high accuracy and ROC analyses showed similar areas under the ROC curves (AUC) for trypsinogen-2 (AUC 0.960), trypsin-2-AAT (0.948), lipase (AUC 0.947), and amylase (AUC 0.930). For differentiation between severe and mild AP, trypsin-2-AAT (AUC 0.805) was slightly better than trypsinogen-2 (AUC 0.792), and they were both clearly better than lipase (AUC 0.583), C-reactive protein (AUC 0.519), or amylase (AUC 0.632) (p < 0.05).

CONCLUSIONS

All the markers studied showed high accuracy for differentiating between AP and extrapancreatic diseases. However, trypsinogen-2 and trypsin-2-AAT displayed the best accuracy for predicting a severe AP already at admission, which makes these markers superior for clinical purposes.

The Ratio of Trypsin-2-α1-Antitrypsin to Trypsinogen-1 Discriminates Biliary and Alcohol-induced Acute Pancreatitis

Background: Rapid determination of the etiology of acute pancreatitis (AP) enables institution of appropriate treatment. We evaluated the ability of trypsinogen-1, trypsinogen-2, trypsin-1-α1-antitrypsin (AAT), and trypsin-2-AAT in serum to identify the etiology of AP.

Methods: The study consisted of 67 consecutive patients with AP admitted to Helsinki University Central Hospital. Forty-two had alcohol-induced AP, 16 had biliary AP, and 9 had unexplained etiology. Serum samples were drawn within 12 h after admission. Trypsinogen-1, trypsinogen-2, trypsin-1-AAT, and trypsin-2-AAT were determined by time-resolved immunofluorometric assays. Logistic regression was used to estimate the ability of the serum analytes to discriminate between alcohol-induced and biliary AP. The validity of the tests was evaluated by ROC curve analysis.

Results: Patients with alcohol-induced AP had higher median values of trypsin-1-AAT (P = 0.065), trypsinogen-2 (P = 0.034), and trypsin-2-AAT (P &lt;0.001) than those with biliary AP, who had higher values of amylase (P = 0.002), lipase (P = 0.012), and alanine aminotransferase (P = 0.036). The ratios of trypsin-2-AAT to trypsinogen-1, lipase, or amylase efficiently discriminated between biliary and alcohol-induced AP (areas under ROC curves, 0.92–0.96).

Conclusions: Trypsinogen-2 and trypsin-2-AAT are markedly increased in AP of all etiologies, whereas trypsinogen-1 is increased preferentially in biliary AP. The trypsin-2-AAT/trypsinogen-1 ratio is a promising new marker for discrimination between biliary and alcohol-induced AP.

Time-resolved Immunofluorometric Assay of Trypsin-1 Complexed with α1-Antitrypsin in Serum: Increased Immunoreactivity in Patients with Biliary Tract Cancer

Background: Increased serum concentrations of trypsin immunoreactivity occur in patients with biliary tract cancer. To characterize this trypsin, we developed a sensitive time-resolved immunofluorometric assay for trypsin-1 complexed with α1-antitrypsin (AAT) and studied the concentrations of this complex in sera from healthy individuals (n = 130) and patients with benign biliary disease (n = 32), biliary tract cancer (n = 17), pancreatic cancer (n = 27), and hepatocellular cancer (n = 12).

Methods: We used a trypsin-1-specific monoclonal antibody on the solid phase and a europium-labeled polyclonal antibody to AAT as tracer. The detection limit was 0.42 μg/L. The validity of the trypsin-1-AAT test for detection of biliary tract cancer was compared with trypsin-2-AAT and CA19-9.

Results: Increased concentrations of trypsin-1-AAT (&gt;33 μg/L) were found in 76% of patients with biliary tract cancer, and the concentrations were significantly higher than in those with benign biliary disease (P &lt;0.0001). The median concentration of trypsin-1-AAT in serum from patients with biliary tract cancer was 3.7-fold higher than in healthy controls, 2.6-fold higher than in patients with benign biliary tract disease, 1.7-fold higher than in patients with pancreatic cancer, and 2.0-fold higher than in patients with hepatocellular cancer.

Conclusions: Of the markers studied, trypsin-1-AAT had the largest area (0.83) under the receiver operating curve in differentiating biliary tract cancer from benign biliary tract disease. Our results suggest that trypsin-1-AAT is a new potential marker for biliary tract cancer.

Support of the diagnosis of pancreatitis by enzyme tests--old problems, new techniques

Computerized tomography and ultrasound are helpful in the diagnosis of acute pancreatitis. The procedures, however, are not always available and so laboratory tests continue to play an important role. Serum amylase measurement is the most widely used test, despite its lack of sensitivity (75-92%) and specificity (20-60%). A cut-off point of 3-6 times the upper reference limit increases the specificity greatly, but at the expense of sensitivity. A method using chloronitrophenyl-maltotrioside as substrate has recently been rejected by the IFCC. A method using ethylidene-protected 4-nitrophenyl-maltoheptaoside and a new alpha-glucosidase has emerged as the method of choice. Amylase isoenzyme determinations have higher specificity than total amylase measurements. Serum lipase methods are more sensitive and specific, but methodological problems persist. Cationic trypsin-1 measurements yield high sensitivity but low specificity. Elastase-1 is claimed to correlate best with the clinical symptoms. Reasons for the widely differing reports on sensitivity and specificity of tests for pancreatitis are discussed.

Serum trypsinogen-2 in the prediction of outcome in acute necrotizing pancreatitis

BACKGROUND

The accuracy of serum trypsinogen-2 in predicting the severity of acute necrotizing pancreatitis (ANP) was prospectively evaluated in 52 consecutive patients.

METHODS

A new sensitive immunofluorometric assay was used for serum trypsinogen-2,

RESULTS

Mean values during the first 24 h were 42.1 micrograms/l in control patients, 1435 micrograms/l in uncomplicated cases, and 4090 micrograms/l in complicated or fatal cases. There was a significant difference in serum trypsinogen-2 values between patients with uncomplicated and complicated disease (p = 0.002) already on admission. When a cutoff level of 1000 micrograms/l was used, patients with uncomplicated ANP were differentiated from patients with complicated ANP with a sensitivity of 91% and with a specificity of 71%.

CONCLUSIONS

The immunofluorometric assay of serum trypsinogen-2 is a sensitive and specific method for prediction of the severity of the disease in necrotizing pancreatitis.

Serum trypsinogen-2 and trypsin-2-alpha(1)-antitrypsin complex in malignant and benign digestive-tract diseases. Preferential elevation in patients with cholangiocarcinomas

Serum concentrations of trypsinogen-2 and trypsin-2-alpha(1)-antitrypsin (trypsin-2-AAT) were determined in 145 patients with malignant and 61 with benign digestive-tract diseases. The validity of these tests for detection of cancer was compared with that of CA 19-9 and CEA. Elevated levels of trypsinogen-2 (>90 micrograms/l) and trypsin-2-AAT (>25 micrograms/l) were found in 46% and 42%, respectively, of patients with malignant disease and the levels of trypsinogen-2 were significantly higher than in those with benign disease (p<0.005). High trypsinogen-2 and trypsin-2-AAT concentrations were found most often in patients with biliary and pancreatic cancer, but also in benign obstructive biliary disease. Our results suggest that trypsinogen-2 and trypsin-2-AAT are new potential markers for cholangiocarcinomas.

Urinary trypsinogen-2 test strip for acute pancreatitis

BACKGROUND

A simple, rapid test is specific and sensitive enough to distinguish, in patients with clinically suspected acute pancreatitis, those whose abdominal pain is indeed of pancreatic origin has proved elusive.

METHODS

In two consecutive series of surgical patients in a teaching hospital, whose acute abdominal pain turned out to be due to acute pancreatitis (n-57) or extrapancreatic in origin (n=40), we studied urinary trypsinogen-2 in two ways. A test strip, incorporating monoclonal antibodies to two epitopes on trypsinogen-2, recorded a blue line when concentrations exceeded 50 microgram/L; we also measured trypsinogen-2 concentrations in the laboratory.

FINDINGS

In the patients with acute pancreatitis the test strip was positive in 52 and negative in five, whereas in the 40 extrapancreatic controls there were four false positives. In a further set of 57 orthopaedic controls, one urine was strip-test positive. Concentrations of urinary trypsinogen-2 and the test-strip results were in good agreement and in only three of the 154 patients were the two approaches discrepant, at the 50 microgram/L cut-off.

INTERPRETATION

These findings, in patients whose acute abdominal pain was known to be pancreatic in origin or not, are encouraging but need to be confirmed in a consecutive series of patients in whom the diagnosis of pancreatitis is in doubt.