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Researchers Identify Specific Cytokines and Lysosomal Enzymes to Differentiate Among Forms of Pancreatitis: Presented at UEGW

By Chris Berrie

PRAGUE, CZECH REPUBLIC -- September 30, 2004 -- Differences in interleukin-6 (IL-6) concentrations and the relative activities of lysosomal enzymes and their isoforms in serum samples demonstrate a discriminatory test for the various forms of pancreatitis, according to data from study presented here September 29th at the 12th United European Gastroenterology Week.

Presenter Halina Milnerowicz, PhD, professor of toxicology, Department of Toxicology, Wroclaw University of Medicine, Wroclaw, Poland, said that experimental and clinical studies have indicated that cytokines, IL-6 in particular, play an important and essential role as mediators of the inflammatory process associated with pancreatitis. Similarly, the lysosomal enzymes N-acetyl-beta-D-glycosaminidase (NAG; EC 3.2.1.30) and beta-D-glucuronidase (betaDG; EC 3.2.1.31) have been postulated as being important in the pathogenesis of chronic pancreatitis.

"We have thus looked at interleukin-6 as a diagnostic marker, estimated at diagnosis, and NAG-B, [as] an isoform of NAG that is also important in pancreatitis," said Dr. Milnerowicz.

For their study, the researchers used serum samples from 20 patients with chronically exacerbated pancreatitis (CEP), 15 with acute pancreatitis (AP), and 35 with chronic pancreatitis (CP). Then they compared their data with serum samples from 22 healthy controls. Serum samples were taken during the first 48 hours of hospitalization [in the patients with chronic pancreatitis.

They used a sandwich-type, enzyme-linked immunosorbent assay to determine IL-6 concentrations in the serum samples. The enzyme activities were measured with p-nitrophenyl-N-acetyl-D-glucosaminide (10 mM) for NAG and its isoenzymes, and with p-nitrophenyl-D-glucuronide (4.68 mM) for betaDG.

The mean control serum level of IL-6 was 1.3 pg/mL. Patients with CEP and, more so, those with AP had significantly higher mean levels (17.7 pg/mL, P <.01; 85.0 pg/mL, P <.001, respectively). In CP patients, the mean IL-6 level was not significantly different from those of controls (2.0 pg/mL).

For NAG, the mean control activity was 8.1 U/L, significantly higher mean NAG activity that was seen in the patients with CEP (18.4 U/L; P <.001), and those with AP (34.3 U/L; P <.001). The CP group, however, did not have significantly increased activity (10.4 U/L).

The betaDG activity also showed increases, although these were significant across all of the pancreatitis forms. With a mean control activity of 0.8 U/L, the mean increased activities seen were 1.6 U/L (P <.001), 2.4 U/L (P <.001), and 1.2 U/L (P <.01), respectively.

When the activities of the A and B isoforms of NAG were determined, the control NAG activity was seen to be totally due to the NAG-A isoform (mean, 8.1 U/L). In the pancreatitis patient sera, the increased mean NAG-A activities versus control largely paralleled those of the total NAG activity seen initially (17.5 U/L, P <.01; 37.2 U/L, P <.001; 9.3 U/L, NS, respectively). With no activity seen for NAG-B in the control group, there were small but uniform mean activities found for NAG-B in the pancreatitis patients (0.9 U/L; 0.9 U/L; 1.1 U/L, respectively).

However, due to this difference in the NAG-A and NAG-B activities, when they are expressed as percentages of the total activity in each pancreatitis condition, this demonstrates the following values for the NAG-B isoforms: control, 0; CEP, 4.9; AP, 2.4; CP, 10.6.

Dr. Milnerowicz concluded that the combination of the differences in IL-6 concentrations and these calculated relative increases across the activities of the NAG-A and NAG-B isoforms are thus specific to each form of pancreatitis, and hence this serum-based sampling should prove useful in the differentiation between these various types of pancreatitis.


[Presentation title: "The Activity of Lysosomal Enzymes: N-acetyl-beta-D-glycosaminidase and beta-D-glucuronidase and the Role of Interleukin-6 in Serum of Patients with Pancreatitis. Abstract MON-G-374." Abstract 574]

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