An ELISA for elastase alpha 1-protease inhibitor complexes in human plasma and serum

Systemic levels of cotinine and elastase, but not pulmonary function, are associated with the progression of small abdominal aortic aneurysms

OBJECTIVE

to study whether smoking and impaired pulmonary function are associated with the expansion of abdominal aortic aneurysms (AAA).

METHODS AND MATERIAL

seventy-nine men with small (3-5 cm), screen-detected AAA underwent a simple 5-step smoking history, measurement of the forced first second expiratory volume (FEV1), venepuncture and annual ultrasound scan for mean follow-up period of 3.5 years.

RESULTS

all but one patient had a significantly reduced FEV1 (p<0.05, Mann-Whitney). The FEV1/expected FEV1 ratio (rFEV1) was not related to AAA expansion but was negatively correlated with P-elastase-alpha1-antitrypsin-complexes (P-Elastase). P-Elastase was positively correlated with smoking and S-cotinine. Smoking, S-cotinine, and P-elastase were positively correlated with the mean annual AAA expansion rate but not rFEV1.

CONCLUSION

in general, patients with AAA have impaired pulmonary function. A simple five step smoking classification is as predictive of AAA-expansion as S-cotinine. Smoking may cause elastase secretion leading to pulmonary and aortic elastin degradation but the lack of association between AAA-expansion and rFEV1 suggest that other mechanisms are important.

The plasma level of matrix metalloproteinase 9 may predict the natural history of small abdominal aortic aneurysms. A preliminary study

OBJECTIVES

increased levels of various proteinases have been detected in abdominal aortic aneurysms (AAA) and are assumed to cause the degradation of the aortic wall. To determine whether systemic measurement of these proteinases and their inhibitors may predict the natural cause of AAA.

METHODS AND MATERIAL

serum (S) and plasma (P) samples were obtained from 121 men following the diagnosis of a small AAA (3-5 cm) at population screening. Annual control scans were performed to check for expansion. Circulating levels of elastase-alpha 1 antitrypsin-complexes, alpha 1 antitrypsin, matrix metalloproteinase (MMP) 2 & 9, tissue-inhibitor-matrixproteinase 1 & 2, procollagen III-N-terminal-propeptide, and elastin-peptides were measured in a random group of 36 men.

RESULTS

alpha 1 antitrypsin was significantly and positively associated with expansion. Similarly, P-MMP9 levels were significantly associated with size and expansion. There was a difference between median serum and plasma values, probably because of secretion from platelets.

CONCLUSION

P-MMP9 and P-alpha 1 antitrypsin may predict the natural history of AAA.

A simple visual immunoassay (VIA) for the semiquantitative determination of plasma elastase levels

Elastase levels are an important marker of the extent and severity of inflammatory processes. We describe a visual immunoassay based on two monoclonal antibodies for the semi-quantitative determination of plasma elastase levels. The method is rapid, reliable, easy to perform, and does not require special laboratory equipment. There is coincidence of our results with those obtained by quantitative methods. The assay is suitable to obtain information for the management of patients in most intensive care units.

Immunoglobulin A antibodies against Chlamydia pneumoniae are associated with expansion of abdominal aortic aneurysm

BACKGROUND

The aim of this study was to examine the possible association between the progression of small abdominal aortic aneurysm (AAA) and chronic infection with Chlamydia pneumoniae.

METHODS

Patients from a hospital-based mass screening programme for AAA with annual follow-up (mean 2.7 years) were included. After initial interview, 139 men aged 65-73 years with a small AAA underwent examination and blood sampling. Immunoglobulin (Ig) G and IgA titres against C. pneumoniae were measured by a microimmunofluorescence test.

RESULTS

Some 83 (95 per cent confidence interval 74-93) per cent of the men had an IgA titre of 20 or more, or an IgG titre of 32 or more. Men with an IgA titre of 20 or more had a 48 per cent higher AAA expansion rate than those with a titre of less than 20 (3.1 versus 2.1 mm/year; P < 0.05). Multiple linear and logistic regression analyses showed that an IgA titre of 20 or more was a significant independent predictor of increased AAA expansion, adjusted for known risk factors of expansion. Initial AAA size and serum total cholesterol level were also predictors of expansion.

CONCLUSION

A high proportion of men with a small AAA had signs of chronic infection with C. pneumoniae. Aneurysm progression correlated with evidence of chronic C. pneumoniae infection.

Natural history of abdominal aortic aneurysm with and without coexisting chronic obstructive pulmonary disease

PURPOSE

To study the relation between abdominal aortic aneurysms and chronical obstructive pulmonary disease (COPD), in particular the suggested common elastin degradation caused by elastase and smoking.

METHODS

A cross-sectional population study and a prospective cohort study of small abdominal aortic aneurysms was performed in a community setting. All previous diagnoses recorded in a hospital computer database were received for 4404 men 65 to 73 years of age who had been invited to a population screening for abdominal aortic aneurysm. One hundred forty-one men had AAA (4.2%). They were asked to participate in an interview, a clinical examination, and collection of blood sample. Men with an abdominal aortic aneurysm 3 to 5 cm in diameter were offered annual ultrasound scans to check for expansion.

RESULTS

Among patients with COPD 7.7% had abdominal aortic aneurysms (crude odds ratio=2.05). The adjusted odds ratio, however, was only 1.59 after adjustment for coexisting diseases associated with abdominal aortic aneurysm (P=.13). The mean annual expansion was 2.74 mm per year among patients with COPD, 2.72 among patients without COPD, and 4.7 mm among patients who used oral steroids compared with 2.6 among patients who did not use steroids (P < .05). Concentration of serum elastin peptide and plasma elastase-alpha1-antitrypsin complexes correlated negatively with forced expiratory volume in the first second (FEV1) among patients with COPD. However, multivariate regression analysis showed that concentration of serum elastin peptide, therapy with beta-agonists, and FEV1 correlated positively with degree of expansion but that concentration of plasma elastase-alpha1-antitrypsin complexes and serum alpha1-antitrypsin did not influence expansion, suggesting that elastase plays an important role in the pathogenesis of COPD but not of abdominal aortic aneurysm.

CONCLUSION

The high prevalence of abdominal aortic aneurysm among patients with COPD is more likely to be caused by medication and coexisting diseases rather than a common pathway of pathogenesis.

Serum elastase and alpha-1-antitrypsin levels in patients with ruptured and unruptured cerebral aneurysms

Despite advances in surgical treatment and postoperative care, subarachnoid hemorrhage from ruptured cerebral aneurysms remains a devastating event. Excellent surgical results in treating unruptured aneurysms suggest the utility of screening tests to identify high-risk individuals. Unfortunately, none of the known risk factors for subarachnoid hemorrhage correlates strongly enough with the illness to warrant widespread screening for occult aneurysms. Other disease entities suggest that protease-antiprotease imbalances contribute to somatic vessel wall degradation and aneurysm formation. Detection of similar imbalances in selected patients may identify a predisposition to cerebral aneurysm formation. Serum concentrations of elastase and alpha-1-antitrypsin (AAT), important proteolytic and antiproteolytic enzymes, were measured in a series of 19 patients with unruptured aneurysms, 41 patients with ruptured aneurysms, and 27 age-matched operative and nonoperative controls. The elastase:AAT ratio was nearly twice as high in patients with unruptured aneurysms as in operative controls (0.527 +/- 0.1 versus 0.285 +/- 0.06; P < 0.04). Elastase:AAT ratios in patients with ruptured aneurysms (subarachnoid hemorrhage < 48 h) were roughly twice those of controls (0.582 +/- 0.095; P < 0.01). There was no statistical difference between elastase:AAT ratios for patients with ruptured and unruptured aneurysms. Likewise, elastase-AAT values for operative controls and nonoperative volunteers were not significantly different. Differences in serum elastase:AAT ratios between patients with aneurysms and controls reflected differences in elastase concentration (99 +/- 56 micrograms/ml versus 67 +/- 56 micrograms/ml; P < 0.03), not in AAT levels (147 +/- 56 micrograms/ml versus 141 +/- 56 micrograms/ml; P < 0.72).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurements of proteinase 3 and its complexes with alpha 1-proteinase inhibitor and anti-neutrophil cytoplasm antibodies (ANCA) in plasma

Wegener's granulomatosis (WG) is a systemic vasculitis which is diagnosed on clinicopathological findings. The diagnosis may be aided by the presence of anti-neutrophil cytoplasm antibodies (ANCA). In WG, ANCA are primarily directed to proteinase 3 (PR3), a serine protease of the azurophilic granules of the neutrophilic granulocyte. The main plasma inhibitor of PR3 is alpha 1-proteinase inhibitor (PI). To study if free PR3 or complexes between the enzyme and PI or PR3 and ANCA could be found in the plasma from patients with WG we have developed three ELISA systems for the detection of these complexes and free PR3. In all three assays monoclonal antibodies against PR3 were used as capture antibodies. After incubation with plasma, free PR3 was detected by affinity purified rabbit anti-PR3 followed by alkaline phosphatase-labelled swine anti-rabbit IgG. Serial dilutions of purified PR3 was used as standard. The detection limit was 3 ng/ml. PR3 complexed with PI was measured by rabbit anti-PI antibodies and alkaline phosphatase-labelled swine anti-rabbit IgG. Pre-formed in vitro complexes of PR3/PI in serial dilutions were used as standard. The detection limit of this assay was 1 ng/ml. PR3/IgG-ANCA complexes were detected by alkaline phosphatase labelled goat anti-human IgG. A positive plasma sample in serial dilutions was used as standard. Plasma samples from nine patients with WG, eight patients with fever of infectious origin without evidence of vasculitis and ten healthy donors were examined by these methods. Free PR3 could not be found in any of the plasma samples. PR3/PI complexes were detected in healthy donors at levels between 41-85 ng/ml. All WG patients, both active and inactive, had PR3/PI concentrations above this level, and so had all patients with fever. PR3/IgG-ANCA was found in three of the patients with WG, two being ANCA negative with inactive disease and one was ANCA positive with active disease. Thus, the developed methods can be useful for future studies of the clinical relevance of these complexes in patients with WG and possibly other vasculitides.

Aspects of preanalytical variation of lactoferrin and elastase/alpha 1-protease inhibitor complexes

A number of interesting applications of plasma elastase/alpha 1-protease inhibitor complexes (ELA-PI) and lactoferrin (LAC) have recently been suggested. However, the clinical utility of these components often seems to be low. This might be improved by minimizing the preanalytical variation, if possible. Therefore, we have evaluated the influence of various aspects of sampling and handling conditions on the results obtained when measuring ELA-PI and LAC. Blood samples from both healthy persons as well as patients, who had undergone laparotomy the day before, were investigated. We confirmed the previous observations of higher concentrations of ELA-PI and LAC in serum compared to plasma. This was more pronounced in patients than in healthy adults. In EDTA-blood the most important change was seen in samples from patients when stored at room temperature. In this situation increases of LAC concentrations of 50% and 100% following 2 and 5 h, respectively were found. This in vitro release of LAC was abolished when samples were stored on ice until centrifugation within 5 h. In contrast, a statistically significant increase in ELA-PI of 10% was observed following storage on ice for 2 h of blood specimens drawn from healthy persons. EDTA-plasma obtained by venous puncture following minimal stasis contained 10% higher concentrations of LAC compared to samples drawn from intravenous catheters, while no difference was observed in the case of ELA-PI. However, in one individual prolonged venous stasis resulted in larger differences of both LAC and ELA-PI. Different centrifugation conditions (1500 vs. 3000 x g; room temperature vs. 4 degrees C) did not influence concentrations of LAC or ELA-PI measured, neither did eating a normal meal nor moderate physical activity (30 min walk). In conclusion, ELA-PI and LAC should be measured in EDTA-plasma. Blood must be drawn by venous puncture applying minimal stasis or from indwelling venous catheters. Samples for measuring LAC must be stored on ice until centrifugation. Separation of plasma from cells should be performed as fast as possible, but storage for up to 5 h can be accepted.