Levels of leukocyte proteases in plasma and peritoneal exudate in severe, acute pancreatitis

Increased circulating levels of proteinase 3 in patients with anti-neutrophilic cytoplasmic autoantibodies-associated systemic vasculitis in remission

In systemic small vessel vasculitides, patients form autoantibodies against neutrophil granular proteins, anti-neutrophilic cytoplasmic autoantibodies (ANCA). Some correlation is seen between ANCA titre and disease activity, but whether this is cause or effect is still unknown. It has been reported that levels of proteinase 3 (PR3), one of the main ANCA antigens, are increased in patients with active disease. An increased level of circulating antigen could mean a predisposition to autoimmunity. In order to explore this we measured PR3 levels in patients with stable disease. In addition we measured neutrophil gelatinase-associated lipocalin (NGAL) as a specific marker of neutrophil degranulation, cystatin C as a marker of renal function as well as C-reactive protein (CRP), IL-6 and sTNFr1 as markers of inflammation. PR3, NGAL, IL-6 and sTNFr1 were measured in plasma by the ELISA technique. In the PR3 ELISA, we used anti-PR3 monoclonal antibodies as capture-antibodies and affinity-purified rabbit-anti-PR3 antibodies for detection. PR3-ANCA, myeloperoxidase (MPO)-ANCA, CRP and cystatin C were measured by routine methods. PR3 was significantly raised (P < 0.0001) in vasculitis patients (median 560 micro g/l, range 110-3,940, n = 59) compared with healthy blood donors (350 micro g/l, 110-580, n = 30) as well as disease controls (360, 110-580, n = 46). No correlation was seen with disease activity, inflammation or renal function. The raised NGAL levels correlated strongly with decreased renal function (r = 0.8, P < 0.001). After correcting for this, slightly increased levels (110, 42-340, n = 59) were observed compared with healthy blood donors (81, 38-130, n = 25), but not compared with the disease controls (120, 57-260, n = 48). In the disease controls, there was a significant correlation between NGAL and proteinase 3 (r = 0.3, p < 0.05), but this was not the case in the vasculitis patients. Whether patients had PR3-ANCA or MPO-ANCA was of no significance. In our measurements, we found significantly raised levels of PR3 in plasma from patients with small vessel vasculitis, regardless of ANCA specificity. This was not due to decreased renal function, ongoing inflammation or neutrophil activation. Plausible mechanisms for this include defects in the reticuloendothelial system, genetic factors and selective neutrophil degranulation or leakage.

Pancreatic enzyme-induced pancreatitis and systemic complications in rats

Effects of retrograde injection into the pancreatic duct and intravenous infusion of pancreatic enzymes and bile salt on the pancreas and other vital organs such as the liver and the lung were investigated in rats. Intraductal injection (1 ml/kg) of alpha-chymotrypsin (50-100 mg/ml), trypsin (10-100 mg/ml), pancreatic elastase (10 mg/ml), lipase (100-300 mg/ml), pancreatic kallikrein (25 mg/ml) and sodium taurocholate (50 mg/ml) solutions significantly increased pancreatic water content. Alpha-chymotrypsin, pancreatic elastase, taurocholate and trypsin elicited gross pancreatic hemorrhage. In contrast, lipase and kallikrein elicited gross pancreatic edema, but not hemorrhage. Intravenous infusion of trypsin (1 mg/kg/hr) and pancreatic elastase (10 mg/kg/hr) significantly increased pulmonary vascular permeability in rats, whereas infusion of neutrophil elastase (0.3 mg/kg/hr) did not elicit these effects. Only trypsin slightly reduced arterial oxygen pressure. These results show pancreatic enzymes and bile salts induce pancreatic inflammation after retrograde injection into the pancreatic duct in rats. Furthermore, trypsin and pancreatic elastase extravasation into the vascular system can lead to pulmonary dysfunction in rats.

Neopterin in acute pancreatitis

BACKGROUND

Activation of the cellular immune system may play a role in the pathogenesis of acute pancreatitis (AP); it has recently been proposed that excessive leukocyte stimulation may lead to the most severe forms of AP. The aim of this study was to investigate serum neopterin, a useful in vivo marker of macrophage activation, in mild and severe AP and its relationship with other markers of leukocyte activation, such as interleukin-6 (IL-6) and tumor necrosis factor (TNF).

METHODS

Serum levels of neopterin (mmol/ml), IL-6 (pg/ml), and TNF (pg/ml) were measured on the 1st and 7th day of hospitalization in 17 patients with severe AP and 24 with mild AP. Severe AP was defined in accordance with the Atlanta criteria: all patients have necrosis at contrast-enhanced computerized tomography scan.

RESULTS

Day 1: Neopterin and IL-6 levels were significantly higher in severe than in mild AP and normal controls; mild AP values were also significantly higher than in normal controls. The best neopterin cutoff level we obtained (30 mmol/ml) reached a specificity of 76% and a sensitivity of 46% in distinguishing severe from mild AP. Day 7: Neopterin was significantly higher in severe AP than in mild AP and in normal controls; no difference was seen between mild AP values and normal controls; neopterin serum levels were significantly higher on day 7 than on day 1 in severe AP but not in mild AP; in both groups of patients IL-6 was significantly higher on day 1 than on day 7. Using a neopterin cutoff level of 40 mmol/ml, we found specificity and sensitivity value of 92% in differentiating severe from mild AP. With regard to TNF values, no difference was seen on day 1 and 7 in the two groups of patients in comparison with normal controls. Neopterin serum values did not correlate with IL-6 and TNF on either day.

CONCLUSIONS

These results confirm the activation of the cellular immune system in AP. Initially enhanced NEOP and IL-6 serum levels reflect the severity of the disease; neopterin may be considered a reliable prognostic indicator also at a distance from AP onset because its levels increase during the 1st week of AP in patients with severe forms only.