Detection of Human Pancreatic Pro-Phospholipase A<sub>2</sub> Activation Using an Immunoassay for the Free Activation Peptide DSGISPR

Gudgeon, A. M.; Patel, Geeta; Hermon‐Taylor, John; Hurley, Paul R.; Bowyer, R. C.; Jehanli, Ahmed

doi:10.1177/000456329102800513

Cited by 15 publications

(11 citation statements)

References 26 publications

(2 reference statements)

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“…Most of the zymogen Pro-PROP released into the systemic circulation in necrotizing pancreatitis therefore seems to remain unactivated and does not play a role in the development of systemic complications. Therefore we could not substantiate the hope that plasma PROP is an early indicator of systemic complications and an important early event in the systemic response to acute pancreatitis as suggested by previous studies on urinary PROP [3, 14, 28]. There remain some questions on PROP that need to be addressed in further studies: to what extend is PROP derived from activated pancreatic PLA 2 -I or released from activated granulocytes locally as well as in the systemic circulation.…”

Section: Discussionmentioning

confidence: 71%

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Local and Systemic Zymogen Activation in Human Acute Pancreatitis

Mayer

Rau²,

Siech³

et al. 2000

Digestion

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Background: Activation of trypsinogen and phospholipase A₂ is an early event in pancreatic inflammation, but little is known about zymogen activation and the severity of human pancreatitis. Methods: Using a new fluoroimmunoassay we measured trypsinogen activation peptide (TAP) and phospholipase A₂ activation peptide (PROP) in plasma and ascites in 25 patients with acute pancreatitis. TAP, PROP, Pro-PROP and pancreatic PLA₂-I were measured in plasma for 14 days and in pancreatic necroses, ascitic fluid and pleural effusions. Results: All 16 patients with severe acute pancreatitis (SAP) had pancreatic necrosis, 10 developed systemic complications like sepsis, pulmonary or renal failure, 6 had infected necrosis, and 4 died. All 9 patients with mild pancreatitis (MAP) survived. Plasma TAP on admission was higher in patients with SAP than in those with MAP and increased in infected necroses. It did not correlate with systemic complications. Systemic PROP was not increased in complicated courses but was significantly higher in patients with MAP than in those with SAP on admission. Pro-PROP was higher in patients with SAP than in those with MAP but was not correlated with systemic complications. Plasma pancreatic PLA₂-I was increased but not different in patients with SAP and those with MAP. In patients with pancreatic necrosis, TAP and PROP were highest, while in those with post-acute pancreatic abscess, only PROP and Pro-PROP were high. In patients with pleural effusion, TAP was low and PROP/ Pro-PROP were high. Conclusion: Trypsinogen and PLA₂-I activation are early events in acute pancreatitis and the activation peptides can be detected in plasma. In the pancreas, trypsinogen activation is accompanied by PLA₂-I activation in patients with pancreatic necrosis. However, in our study, organ complications in SAP patients was not associated with increased plasma PROP.

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Section: Discussionmentioning

confidence: 71%

“…Active trypsin is difficult to measure because is it quickly complexed or denatured. Therefore, the measurement of specific peptides that are released on activation has evolved as a helpful tool in assessing zymogen activation [3, 10, 11, 14, 28]. …”

Section: Discussionmentioning

confidence: 99%

Local and Systemic Zymogen Activation in Human Acute Pancreatitis

Mayer

Rau²,

Siech³

et al. 2000

Digestion

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“…PROP can be used in assays to characterize the severity of acute pancreatitis (11). The C-terminal pentapeptide of PROP (GISPR) is essential for the inhibition of enzyme activity (12). Besides trypsin, pro-hG1B can also be activated by thrombin (13) and 29-kDa trypsin-like endogenous type 1-proPLA2 activator (11).…”

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confidence: 99%

Structural Insight into the Activation Mechanism of Human Pancreatic Prophospholipase A2

Xü

Long

Feng

et al. 2009

Journal of Biological Chemistry

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Pancreatic phospholipase A2 (phospholipase A2 group 1B, G1B) belongs to the superfamily of secreted phospholipase A2 (PLA2) enzymes. G1B has been proposed to be a potential target for diseases such as hypertension, obesity, and diabetes. Human pancreatic prophospholipase A2 (pro-hG1B) is activated by cleavage of the first seven-residue propeptide (phospholipase A2 propeptide, PROP). However, questions still remain on the mode of action for pro-hG1B. In this work, we expressed prohG1B in Pichia pastoris and determined the crystal structure at 1.55-Å resolution. The x-ray structure demonstrates that prohG1B forms a trimer. In addition, PROP occupies the catalytic cavity and can be self-cleaved at 37°C. A new membrane-bound surface and activation mechanism are proposed based on the trimeric model of pro-hG1B. We also propose a new autoproteolytic mechanism for pro-hG1B by the reaction triad Asp49-Arg0-Ser(-2) that is similar to the serine protease catalytic triad.Phospholipase A2 (PLA2, 5 EC 3.1.1.4) hydrolyzes glycerophospholipids at the sn-2 acyl bond to produce free fatty acids. The PLA2 family currently comprises five categories: the secreted PLA2s, the cytosolic PLA2s, the Ca 2ϩ -independent PLA2s, the platelet-activating factor acetyl hydrolases, and the lysosomal PLA2s. To date, based on the catalytic mechanism as well as functional and structural information, 15 different groups of PLA2 have been reported and named (1).G1B is a member of the secreted PLA2 enzymes. This lipolytic enzyme releases glycerophospholipids and arachidonic acid that serve as the precursors of signal molecules that mediate a multitude of biological functions, such as inflammation. The G1B gene has been reported to be linked to hypertension in three sample populations (2). The concentration of G1B protein in serum is a potential marker for pancreatic acinar cell carcinoma (3). Knock-out mice experiments showed that G1B knockdown can prevent diet-induced obesity and obesity-related insulin resistance (4). After being fed with glucose-rich meals, knock-out mice showed lower postprandial glycemia than wild-type mice (5). A recent report also pointed to the linkage between hG1B and ophthalmic diseases (6). Therefore, hG1B is considered to be a potential target for treatment of obesity, diabetes (4, 5), or ophthalmic diseases (6).Pro-hG1B is a digestive zymogen secreted from pancreatic acinar cells in its inactive form (7). It is activated by trypsin in the duodenum. The activation of pro-hG1B by cleavage of the PROP, a heptapeptide of the sequence DSGISPR, is linked to diseases like pancreatitis (8) and acute lung injury (9). Circulating hG1B, mostly in the form of pro-hG1B, indicates pancreatic injury in acute pancreatitis (10). PROP can be used in assays to characterize the severity of acute pancreatitis (11). The C-terminal pentapeptide of PROP (GISPR) is essential for the inhibition of enzyme activity (12). Besides trypsin, pro-hG1B can also be activated by thrombin (13) and 29-kDa trypsin-like endogenous type 1-proPLA2 activator (11)...

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“…Phospholipase A 2 (PLA 2 ) has been investigated as a marker of MODS, 14 but a recent study showed that there was no correlation between serum PLA 2 activity and the severity of the disease, so serum pro-PLA 2 was recently proposed as an alternative. 15,16 There have been some reports dealing with the correlation between blood IL-6 or urinary trypsinogen activation peptide (TAP) and severity level. The blood concentration of IL-6 increases within 24 h after the onset of symptoms, reaching a peak value in 24-36 h; thus, discrimination of severity is possible with a sensitivity of 100% and a specificity of 71% by 24 h after hospitalization.…”

Section: Discussionmentioning

confidence: 99%