Pharmacotherapies and Aortic Heme Oxygenase-1 Expression in Patients with Abdominal Aortic Aneurysm

Abstract

Background: Treatment of cardiovascular risk factors slows the progression of small abdominal aortic aneurysms (AAA). Heme oxygenase-1 (HO-1) is a stress- and hemin-induced enzyme providing cytoprotection against oxidative stress when overexpressed. However, nothing is known about the effects of cardiometabolic standard therapies on HO-1 expression in aortic walls in patients with end-stage AAA.

Methods: The effects of statins, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), calcium channel blockers (CCBs), beta-blockers, diuretics, acetylsalicylic acid (ASA), and therapeutic anticoagulation on HO-1 mRNA and protein expressions were analyzed in AAA patients using multivariate logistic regression analysis and comparison of monotherapy.

Results: Analysis of monotherapy revealed that HO-1 mRNA and protein expressions were higher in patients on diuretics and lower in patients on statin therapy. Tests on combinations of antihypertensive medications demonstrated that ACE inhibitors and diuretics, ARBs and diuretics, and beta-blockers and diuretics were associated with increase in HO-1 mRNA expression. ASA and therapeutic anticoagulation were not linked to HO-1 expression.

Conclusion: Diuretics showed the strongest association with HO-1 expression, persisting even in combination with other antihypertensive medications. Hence, changes in aortic HO-1 expression in response to different medical therapies and their effects on vessel wall degeneration should be analyzed in future studies.

Keywords: abdominal aortic aneurysm; cardiovascular risk factors; heme oxygenase-1; pharmacotherapy; vascular biology.

Figure 1

Stepwise model selection using penalized multiple linear regression for HO-1 mRNA and protein expressions in response to different pharmacological therapies in aortic tissues obtained from patients undergoing elective open surgical repair due to AAA. (A) mRNA expression was measured by qPCR, and data were normalized to an internal control (=1). (B) Protein expression was measured by Western blot, and data were normalized to an internal control (=1). (A,B) Data for HO-1 expression were log transformed, and one statistically significant outlier was omitted from the analysis. Data were analyzed by penalized multiple linear regression (elastic net approach), and HO-1 was set as the outcome variable. Predictors were added to a regression model one at a time to maximize the deviance (x-axis) given the current number of predictors. Regression coefficients, shown on the y-axis, changed as a new predictor was added to the model and reflected the influence of each predictor depending on other predictors present in the model. Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blockers; ASA, acetylsalicylic acid; CCB, calcium channel blockers.

Figure 2

Comparison of HO-1 mRNA expression in response to different pharmacological therapies in aortic tissues obtained from patients undergoing elective open surgical repair due to AAA. (A–H) mRNA expression was measured by real-time PCR, and data were normalized to an internal control that was set to 1. Patients were divided according to the presence (+, blue) or absence (−, red) of the indicated therapy. Statistics: Statistically significant outliers were detected by Grubb’s outlier test. Data are presented as scatter dot plots, where the horizontal line depicts the mean or median with range depending on normality testing. (B,C) Unpaired t-test. (A,D–H) Mann–Whitney U test. * p < 0.05 (+) vs. (−) treatment. (A,D–F,H) One significant outlier was detected in each group. (B,G) One significant outlier was detected in the (−) group. (C) One significant outlier was detected in the (+) group. Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blockers; ASA, acetylsalicylic acid; CCB, calcium channel blocker.

Figure 3

Comparison of HO-1 protein expression in response to different pharmacological therapies in aortic tissues obtained from patients undergoing open surgical repair due to AAA. (A–H) Protein expression was measured by Western blot, and results were divided into patients receiving the indicated therapy (+, blue) or not (−, red). (A) 70 kDa band obtained after Ponceau S staining served as the loading control, and data were normalized to an internal control (=1). Statistics: Significant outliers were detected by Grubb’s outlier test and were removed from all further analysis. (B) One significant outlier was removed from the (−) group. (D,F) One significant outlier was removed from the (+) group. Data are presented as scatter dot plots, where the horizontal line depicts the mean or median with range depending on normality testing. (A–F), Unpaired t-test. (G,H) Mann–Whitney U test. * p < 0.05 (−) vs. (+) diuretics. *** p < 0.001 (−) vs. (+) statins. Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blockers; ASA, acetylsalicylic acid; CCB, calcium channel blocker.