Systemic Inflammation and Repair of Abdominal Aortic Aneurysm

Plasma complement component C2: a potential biomarker for predicting abdominal aortic aneurysm related complications

Blood-based adjunctive measures that can reliably predict abdominal aortic aneurysm (AAA)-related complications hold promise for mitigating the AAA disease burden. In this pilot study, we sought to evaluate the prognostic performance of complement factors in predicting AAA-related clinical outcomes. We recruited consecutive AAA patients (n = 75) and non-AAA patients (n = 75) presenting to St. Michael's Hospital. Plasma levels of complement proteins were assessed at baseline, as well as prospectively measured regularly over a period of 2 years. The primary outcome was the incidence of rapidly progressing AAA (i.e. aortic expansion), defined as change in AAA diameter by either 0.5 cm in 6 months, or 1 cm in 12 months. Secondary outcomes included incidence of major adverse aortic events (MAAE) and major adverse cardiovascular events (MACE). All study outcomes (AAA diameter, MACE and MAAE) were obtained during follow-up. Multivariable adjusted Cox regression analyses were performed to assess the prognostic value of plasma C2 levels in patients with AAA regarding rapid aortic expansion and MAAE and MACE. Event-free survival rates of both groups were also compared. Compared to non-AAA patients, patients with AAA demonstrated significantly higher plasma concentrations of C1q, C4, Factor B, Factor H and Factor D, and significantly lower plasma concentrations of C2, C3, and C4b (p = 0.001). After a median of 24 months from initial baseline measurements, C2 was determined as the strongest predictor of rapid aortic expansion (HR 0.10, p = 0.040), MAAE (HR 0.09, p = 0.001) and MACE (HR 0.14, p = 0.011). Based on the data from the survival analysis, higher levels of C2 at admission in patients with AAA predicted greater risk for rapid aortic expansion and MAAE (not MACE). Plasma C2 has the potential to be a biomarker for predicting rapid aortic expansion, MAAE, and the eventual need for an aortic intervention in AAA patients.

Blood Biomarkers and Serologic Immunological Profiles Related to Periodontitis in Abdominal Aortic Aneurysm Patients

Background

Periodontitis is a chronic inflammatory gum disease associated with systemic diseases such as cardiovascular diseases.

Aim

To investigate the association of systemic blood biomarkers, C-reactive protein (CRP), levels of lipopolysaccharide (LPS), and IgG levels against periodontal pathogens Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) with the stability, based on the aortic diameter, the growth rate and the eligibility for surgical intervention, of patients with abdominal aortic aneurysm (AAA).

Methods

Patients with stable AAA (n = 30) and unstable AAA (n = 31) were recruited. The anti-A. actinomycetemcomitans and anti-P. gingivalis IgG levels were analyzed by ELISA, the LPS analysis was performed by using the limulus amebocyte lysate (LAL) test, and plasma levels of CRP were determined using an immune turbidimetric method. The association between these blood systemic biomarkers, AAA features, periodontal clinical parameters and oral microbial profiles were explored. Regression models were used to test the relationship between variables.

Results

The presence of antibodies against Pg and Aa, LPS and high CRP concentrations were found in all AAA patients. The IgG levels were similar in patients with stable and unstable AAA (both for Aa and Pg). Among investigated blood biomarkers, only CRP was associated with AAA stability. The amount of LPS in saliva, supra, and subgingival plaque were significantly associated with the systemic LPS (p <0.05).

Conclusions

This post-hoc study emphasizes the presence of antibodies against Pg and Aa, LPS and high CRP concentrations in all AAA patients. The presence of Pg in saliva and subgingival plaque was significantly associated with the blood LPS levels. For further studies investigating periodontitis and systemic diseases, specific predictive blood biomarkers should be considered instead of the use of antibodies alone.

Preoperative Leukocytosis Among Female Patients Predicts Poor Postoperative Outcomes Following EVAR For Intact Infrarenal AAA

OBJECTIVES

Elevated white blood count (WBC) can be predictive of adverse outcomes following vascular interventions, but the association has not established using multi-institutional data. We evaluated the predictive value of preoperative WBC after endovascular abdominal aortic aneurysm repair (EVAR) for non-ruptured abdominal aortic aneurysms (AAA) in a nationally representative surgical database.

METHODS

Patients with non-ruptured AAA undergoing EVAR were identified in the vascular-targeted National Surgical Quality Improvement Program (NSQIP) database. Baseline characteristics were compared between patients with WBC < 10 K/μL and WBC ≥ 10 K/μL. Multivariable logistic regression analyses were performed to assess the odds of outcomes. The primary outcome was 30-day mortality. Multiple secondary outcomes including length of stay (LOS) > 1 week, 30-day readmission, lower extremity (LE) ischemia, ischemic colitis, myocardial infarction (MI) and others were assessed based on WBC and patient sex.

RESULTS

A total of 10955 patients were included with a mean WBC 7.7 ± 2.7 K/μL. Patients with WBC ≥ 10 K/μL were younger (71.8 ± 9.5 years versus 74.1 ± 8.7 years; P < .001) and were more likely to be diabetic, on steroids, smokers, functionally dependent and presenting emergently (all P ≤ .009). Aneurysm diameter was larger in WBC ≥ 10 K/μL patients (5.9 ± 1.5 cm versus 5.7 ± 1.5 cm; P < .001). Patients with WBC ≥ 10 K/μL had more mortality (2.4% vs 1.3%), LOS > 1 week (13.5% versus 6.7%), 30-day readmissions (9.8% versus 7.3%), LE ischemia (2.3% vs 1.4%), ischemic colitis (1.2% vs 0.5%), and MI (2.0% vs 1.1% ) (all P ≤ .008). Female patients with WBC ≥ 10 K/μL, compared to male patients with WBC ≥ 10 K/μL had more adverse events including mortality, LOS > 1 week, 30-day readmission, LE ischemia (all P ≤ .025). With each incremental increase in WBC by 1K/μL, the adjusted odds ratio of adverse outcomes for all patient was higher (mortality: 1.05 [95% CI, 1.00-1.10], readmission: 1.03 [95% CI, 1.00-1.06], LOS > 1 week: 1.08 [95% CI, 1.05-1.10] and ischemic colitis: 1.11 [95% CI, 1.05-1.16]; all P < .05). The effect was more pronounced in female patients and statistically significant.

CONCLUSIONS

WBC is a predictor of adverse outcomes in patients undergoing EVAR for non-ruptured AAA. After adjusting for associated risk factors, the effect of increasing WBC was more prominent for female patients. Preoperative WBC should be used as a prognostic factor to predict adverse outcomes among EVAR patients.

Matrix Metalloproteinase in Abdominal Aortic Aneurysm and Aortic Dissection

Abdominal Aortic Aneurysm (AAA) affects 4–5% of men over 65, and Aortic Dissection (AD) is a life-threatening aortic pathology associated with high morbidity and mortality. Initiators of AAA and AD include smoking and arterial hypertension, whilst key pathophysiological features of AAA and AD include chronic inflammation, hypoxia, and large modifications to the extra cellular matrix (ECM). As it stands, only surgical methods are available for preventing aortic rupture in patients, which often presents difficulties for recovery. No pharmacological treatment is available, as such researchers are attempting to understand the cellular and molecular pathophysiology of AAA and AD. Upregulation of matrix metalloproteinase (MMPs), particularly MMP-2 and MMP-9, has been identified as a key event occurring during aneurysmal growth. As such, several animal models of AAA and AD have been used to investigate the therapeutic potential of suppressing MMP-2 and MMP-9 activity as well as modulating the activity of other MMPs, and TIMPs involved in the pathology. Whilst several studies have offered promising results, targeted delivery of MMP inhibition still needs to be developed in order to avoid surgery in high risk patients.

Advanced Oxidation Protein Products and Carbonylated Proteins Levels in Endovascular and Open Repair of an Abdominal Aortic Aneurysm: The Effect of Pre-, Intra-, and Postoperative Treatment

Background

In recent years, a rapid increase in studies focusing on the role of oxidative stress in the pathogenesis of an abdominal aortic aneurysm (AAA) has been observed. Oxidative modifications of proteins are infrequently evaluated in reference to AAA.

Objectives

The intensity of oxidative protein modifications, presented as advanced oxidation protein products (AOPP) and carbonylated proteins (C=O), in AAA patients qualified for surgery was estimated. The effect of surgical techniques and intraoperative and postoperative treatment on AOPP and C=O levels was evaluated.

Patients

The EVAR group, consisting of 30 patients, was classified for endovascular aneurysm repair, whereas 28 patients were classified for conventional open repair (OR).

Methods

AOPP and C=O were measured using a colorimetric assay kit.

Results

A significantly lower AOPP level obtained 2-4 days after EVAR surgery in comparison with the value found before surgery was noted. In the case of OR postoperative treatment, a tendency of AOPP level to increase was observed. The tendency of C=O to decrease after surgery in the EVAR group was indicated. However, the C=O level tended to increase after OR surgery and reached a significantly higher value 5-7 days after surgery compared with the value obtained before surgery.

Conclusions

Based on our results, it may be concluded that AAA as well as surgical technique contribute to the formation of AOPP and C=O. The analysis of changes in AOPP and C=O values obtained after surgery revealed a significant effect of a patient's condition before surgery as well as the choice of surgery technique on the values of the studied parameters revealed during postoperative treatment.

Systematic Review of Circulating, Biomechanical, and Genetic Markers for the Prediction of Abdominal Aortic Aneurysm Growth and Rupture

BACKGROUND

The natural course of abdominal aortic aneurysms (AAA) is growth and rupture if left untreated. Numerous markers have been investigated; however, none are broadly acknowledged. Our aim was to identify potential prognostic markers for AAA growth and rupture.

METHODS AND RESULTS

Potential circulating, biomechanical, and genetic markers were studied. A comprehensive search was conducted in PubMed, Embase, and Cochrane Library in February 2017, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Study selection, data extraction, and methodological quality assessment were conducted by 2 independent researchers. Plausibility of markers was based on the amount of publications regarding the marker (more than 3), pooled sample size (more than 100), bias risk and statistical significance of the studies. Eighty-two studies were included, which examined circulating (n=40), biomechanical (n=27), and genetic markers (n=7) and combinations of markers (n=8). Factors with an increased expansion risk included: AAA diameter (9 studies; n=1938; low bias risk), chlamydophila pneumonia (4 studies; n=311; medium bias risk), S-elastin peptides (3 studies; n=205; medium bias risk), fluorodeoxyglucose uptake (3 studies; n=104; medium bias risk), and intraluminal thrombus size (5 studies; n=758; medium bias risk). Factors with an increased rupture risk rupture included: peak wall stress (9 studies; n=579; medium bias risk) and AAA diameter (8 studies; n=354; medium bias risk). No meta-analysis was conducted because of clinical and methodological heterogeneity.

CONCLUSIONS

We identified 5 potential markers with a prognostic value for AAA growth and 2 for rupture. While interpreting these data, one must realize that conclusions are based on small sample sizes and clinical and methodological heterogeneity. Prospective and methodological consonant studies are strongly urged to further study these potential markers.

Prediction of abdominal aortic aneurysm calcification by means of variation of high-sensitivity C-reactive protein

Objective

Abdominal aortic aneurysms are a major cause of death in developed countries, and thrombus and calcification of the aneurysm have been linked to increased complications. This study was conducted in order to identify the biochemical marker associated to the presence of intraluminal thrombus or calcification progression of the aneurysm.

Design

Several clinical laboratory parameters were measured in patients with abdominal aortic aneurysms, in particular those already demonstrated to be related to the pathology, such as lipoprotein (a), white blood cell count, fibrinogen and high-sensitivity C-reactive protein. Most of the patients were analysed for the presence of thrombus or aorta calcification using CT angiography.

Results

Unlike previous findings, we found no association between intraluminal thrombus formation and lipoprotein (a), but we evidenced that patients with lower grade of calcification tend to have higher plasma high-sensitivity C-reactive protein values compared with patients with a higher degree of calcification. Instead, no association was found with either white blood cell count or fibrinogen level.

Conclusions

This study suggests that high-sensitivity C-reactive protein is a useful biomarker to assess the evolution of calcification and could be used in triaging patients to identify those who should undergo a rapid imaging, thus allowing prompt initiation of treatment or rule-out suspicious patients from non-essential imaging repetition.

Preoperative Predictors of Long-Term Mortality after Elective Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm

OBJECTIVE

This study aimed to clarify long-term mortality and its predictors in patients with abdominal aortic aneurysm (AAA) who underwent endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

Patients with AAA who underwent elective EVAR at Tokyo Medical and Dental University hospital between 2008 and 2011 were reviewed. The patients' data were retrospectively collected from medical records.

RESULTS

Sixty-four patients were identified for this study. In long-term follow-up, the survival rate was significantly lower in patients with high preoperative C-reactive protein (CRP) levels. Patients with obstructive lung disease (FEV1/FVC <70%) or anemia tended to have a poorer prognosis but the association was not statistically significant. Age, concurrent hyperlipidemia, and blood pressure levels were not predictors of mortality rates.

DISCUSSION

High CRP level, COPD, and anemia reflect inflammation, which is associated with the pathogenesis of AAA. These inflammatory markers are predictors of long-term mortality after EVAR for AAA as well as for other diseases.

CONCLUSIONS

A high preoperative CRP level was a predictor of increased long-term mortality in patients with AAA who underwent EVAR. No specific leading causes of death were identified for this increase in the mortality rate.

Influence of Selective Biochemical and Morphological Agents on Natural History of Aneurysm of Abdominal Aorta Development

BACKGROUND The development of abdominal aortic aneurysm (AAA) is probably influenced by many factors. The role of some of these factors, such as intraluminal thrombus (ILT) or cystatin C serum levels, remains controversial. Proving their influence could have therapeutic implications for some patients with AAA. Associations between the rate of increase in diameter of an aneurysm and ILT, as well as other factors, including biochemical factors (C-Reactive Protein - CRP, cystatin C), age, sex, and comorbidities, could predict disease progression in individual patients. MATERIAL AND METHODS Seventy patients with small AAA were included into the study. The patients were followed using ultrasound and CT imaging. We evaluated aneurysm dimensions and aneurysm wall thickness, as well as ILT and its dimensions, aneurysm wall morphology, CRP, and cystatin C. RESULTS We observed significant growth of AAA and thinning of aneurysmal wall. Aneurysms over 4 cm grew significantly faster in the second year of observation. ILT grew together with AAA size. Age, sex, smoking, dyslipidemias, or controlled arterial hypertension had no influence on aneurysm progression rate. Changes in serum of CRP concentration did not reach statistical significance, but cystatin C levels did. CONCLUSIONS Presence and size of ILT, wall thickness, and cystatin C levels may be considered in prediction of AAA progression. ILT might exert a protective influence on the risk of aneurysm rupture. However, larger aneurysms containing larger thrombi grow faster and their walls undergo more rapid degradation, which in turn increases the risk of rupture. This matter requires further studies.

In-hospital efficacy of endovascular aortic repair in patients with impending rupture versus contained rupture of abdominal aortic aneurysms

BACKGROUND

The purpose of our study was to compare the efficacy of endovascular aortic repair (EVAR) in patients with impending rupture of abdominal aortic aneurysm (IRAAA) versus contained rupture of abdominal aortic aneurysm (CRAAA).

METHODS

Of the 21 patients who underwent EVAR for infrarenal AAA from January 2009 to May 2011, 11 did so for IRAAA and 10 for CRAAA. We compared their demographic and aneurysmal characteristics, comorbidities, complications, and clinical outcomes during hospitalization.

RESULTS

The CRAAA group was younger than the IRAAA group. There were no group differences in AAA size, operation time, volume of contrast agent, length of hospital stay (LOHS), or preoperative LOHS. A small difference in mean intraoperative blood loss of ∼4 mL was noted, but was recognized as clinically insignificant. ICU stay and postoperative LOHS were greater in the CRAAA than in the IRAAA. One patient in the IRAAA group had a mild headache after EVAR. Four patients in the CRAAA group had postoperative complications: 1 had acute renal dysfunction; 1 had retroperitoneal infection; 1 had respiratory failure and myocardial infarction; and 1 died of respiratory tract infection and respiratory and cardiac failure.

CONCLUSIONS

Patients undergoing EVAR for CRAAA have a higher incidence of postprocedural severe complications and death than patients undergoing EVAR for IRAAA.

Change in high-sensitive C-reactive protein during abdominal aortic aneurysm formation

OBJECTIVES

We try to clear the relationship between high-sensitive C-reactive protein (hsCRP) release and abdominal aortic aneurysm formation.

METHODS AND RESULTS

A rabbit abdominal aortic aneurysm model was created by elastase perfusion. At days 10, 20, and 30 after elastase perfusion, mean serum hsCRP levels detected by ELISA increased over 200% over their basal level (n = 11, P < 0.05). Serum hsCRP levels were significantly higher in the aneurysm groups than in the sham controls by day 5 (n = 11, P < 0.05) and were positively correlated with percentage vessel diameter changes in the aneurysm group by day 10 (r = 0.8012, n = 33, P < 0.05). In the aneurysm group, increased serum CRP was derived from the liver in early stages, yet from dilated vessels in the later stages, as shown by immunostaining, western blot, and reverse transcriptase-PCR. Similar increased hsCRP levels were also observed in dissected rabbit aortic ring explants from the aneurysm model. Pretreatment with the stretch-activated channel blockers gadolinium or streptomycin, as well as nuclear factor-kappaB inhibitor SN50, blocked hsCRP production in the dilated aortic rings. Stretch-activated channel blockers also inhibited the activation of nuclear factor-kappaB.

CONCLUSION

During abdominal aortic aneurysm formation, increased serum hsCRP levels derive from aneurysmal arteries with degenerating elastic lamina. This process is mediated by mechanical stretch-activated channel-dependent nuclear factor-kappaB translocation to the nucleus.

Expansion of small-diameter abdominal aortic aneurysms is not reflected by the release of inflammatory mediators IL-6, MMP-9 and CRP in plasma

OBJECTIVES

The aim of this study was to evaluate a possible correlation between plasma levels of interleukin-6 (IL-6), metalloproteinase-9 (MMP-9) and C-reactive protein (CRP) and the expansion of small abdominal aortic aneurysms (AAAs).

DESIGN

Patients were selected from a prospective randomised clinical trial and categorised in two groups, in which one group received active treatment (azithromycin) and the other received placebo. No statistical difference in the expansion rate of AAAs between the groups was found and the two groups were considered as one cohort in the present study.

MATERIAL AND METHODS

In this study, 213 patients with AAAs between 35 and 49 mm were followed-up with ultrasound examination every 6th month. Blood samples were taken on two occasions (6 months apart). IL-6 and MMP-9 were analysed on one occasion using Quantikine analysing kits (R&D Systems, Inc., USA). CRP was analysed using sensitive-CRP method.

RESULTS

Levels of IL-6, MMP-9 and CRP did not correlate with AAA expansion. Neither was there any correlation between statin medication and changes in MMP-9 levels over the 6-month period. Patients on statins had a lower expansion rate than those not taking statins: 0.16 versus 0.25 cm per year.

CONCLUSION

No correlation was found between levels of circulating IL-6, MMP-9, CRP and the expansion of small-diameter AAAs, indicating no clinical use of these markers in AAA surveillance.