Oxidative Stress-Related Parthanatos of Circulating Mononuclear Leukocytes in Heart Failure

Abstract

Background: The present study aims to examine the oxidative stress-related activation of poly(ADP-ribose) polymerase (PARP), a cause of parthanatos in circulating mononuclear leukocytes of patients with chronic heart failure (CHF), that was rarely investigated in the human setting yet.

Methods: Patients with CHF (n = 20) and age- and body mass index-matched volunteers (n = 15) with a normal heart function were enrolled. C-reactive protein, N-terminal probrain-type natriuretic peptide (pro-BNP), plasma total peroxide level (PRX), plasma total antioxidant capacity (TAC), oxidative stress index (OSI), leukocyte lipid peroxidation (4-hydroxynonenal; HNE), protein tyrosine nitration (NT), poly(ADP-ribosyl)ation (PARylation), and apoptosis-inducing factor (AIF) translocation were measured in blood samples of fasting subjects.

Results: Plasma PRX, leukocyte HNE, NT, PARylation, and AIF translocation were significantly higher in the heart failure group. Pro-BNP levels in all study subjects showed a significant positive correlation to PRX, OSI, leukocyte HNE, NT, PARylation, and AIF translocation. Ejection fraction negatively correlated with the same parameters. Among HF patients, a positive correlation of pro-BNP with PRX, OSI, and PARylation was still present.

Conclusions: Markers of oxidative-nitrative stress, PARP activation, and AIF translocation in blood components showed correlation to reduced cardiac function and the clinical appearance of CHF. These results may reinforce the consideration of PARP inhibition as a potential therapeutic target in CHF.

Figure 1

Parthanatos in blood components. (a) Plasma total peroxide level. Data are presented as mean ± SEM. (b) Total antioxidant capacity (TAC) change in TAC values in the CHF and control group. Data are presented as mean ± SEM. (c) Oxidative stress index (OSI) is given as the ratio of total peroxide and TAC. Data are presented as mean ± SEM. (d) Oxidative stress in circulating leukocytes. The percentage of positively labeled cellular area compared to total cellular area was calculated on anti-4-hydroynonenal- (HNE-) immunostained leukocyte smears. Data are presented as median (IQR). (e) Nitrative stress in circulating leukocytes. The percentage of positively labeled cellular area compared to the total cellular area was calculated on antinitrotyrosine- (NT-) immunostained leukocyte smears. Data are presented as median (IQR). (f) PARP activity in mononuclear cells. Immunohistochemical labeling of poly(ADP-ribose) (PAR). The end product of PARP was evaluated as described above. Data are presented as median (IQR). (g) AIF translocation in mononuclear cells. Immunohistochemical labeling of AIF. The percentage of positively labeled nuclei compared to the total number of nuclei was calculated. Data are presented as median (IQR) ^∗p < 0.05.

Figure 2

Representative microscopic image of anti-4-hydoxynonenal (HNE), antinitrotyrosine (NT), anti-poly(ADP-ribose) (PAR) stained leukocyte smears, and AIF translocation. The brown-colored (HNE) or black-colored (NT, PAR, and AIF) diamino-benzidine (DAB) represents specific labeling; the blue-colored hematoxylin (HNE) or red-colored Nuclear Fast Red (NFR) (NT, PAR, and AIF) was used for counterstaining. The microscopic images were taken by light microscopy using 40x/0.75 objective; the length of the scale bar is 50 μm. The ratio of positively stained nuclear area is increased in CHF patients' leukocyte smears stained against PAR and AIF.

Figure 3

Linear regression analysis of the relationship between oxidative-nitrative stress, PARP activity, or AIF translocation with pro-BNP levels. (a) Linear regression of pro-BNP levels and plasma total peroxide in all subjects. (b) Linear regression of pro-BNP levels and plasma total peroxide in CHF patients. (c) Linear regression of pro-BNP and oxidative stress index in all subjects. (d) Linear regression of pro-BNP and oxidative stress index in CHF patients. (e) Linear regression of pro-BNP and leukocyte lipid peroxidation (4-hydroxynonenal (HNE)) in all subjects. (f) Linear regression of pro-BNP and leukocyte lipid peroxidation (HNE) in CHF patients. (g) Linear regression of pro-BNP and leukocyte tyrosine nitration in all subjects. (h) Linear regression of pro-BNP and leukocyte tyrosine nitration in the CHF patients. (i) Linear regression of pro-BNP and leukocyte PARyalation in all patients. (j) Linear regression of pro-BNP and leukocyte PARyalation in the CHF patients. (k) Linear regression of pro-BNP and leukocyte AIF translocation in all subjects. (l) Linear regression of pro-BNP and leukocyte AIF translocation in the CHF patients. Increased pro-BNP levels are accompanied with increased oxidative stress (PRX, OSI) and PARP activation of circulating mononuclear leukocytes either in the whole study cohort or in the CHF group alone. Lipid peroxidation, tyrosine nitration, and AIF translocation in circulating mononuclear leukocytes however show correlation with the pro-BNP levels only in the total study cohort. Continuous line represents the regression line, while dashed lines show the 95% confidence bends of the best-fit line. R²: coefficient of determination; p: level of significance.