Interaction between the Haptoglobin 2 Phenotype and Diabetes Mellitus on Systolic Pulmonary Arterial Pressure and Nitric Oxide Bioavailability in Hemodialysis Patients

Dahan, Inbal; Farber, Evgeny; Thauho, Nadia; Nakhoul, Nakhoul; Francis, Adi; Awawde, Mohamad; Levy, Andrew P.; Kim-Shapiro, Daniel B.; Basu, Swati; Nakhoul, Farid

doi:https://doi.org/10.1155/2015/613860

Journal of Diabetes Research

On this page

Abstract Introduction Methods Results Discussion Conclusion Acknowledgments References Copyright Related Articles

Clinical Study | Open Access

Volume 2015 | Article ID 613860 | https://doi.org/10.1155/2015/613860

Interaction between the Haptoglobin 2 Phenotype and Diabetes Mellitus on Systolic Pulmonary Arterial Pressure and Nitric Oxide Bioavailability in Hemodialysis Patients

Inbal Dahan,¹Evgeny Farber,²Nadia Thauho,¹Nakhoul Nakhoul,²Adi Francis,³Mohamad Awawde,³Andrew P. Levy,⁴Daniel B. Kim-Shapiro,⁵Swati Basu,⁵and Farid Nakhoul^1,2

Academic Editor: Hiroshi Okamoto

Received19 Apr 2015

Revised22 May 2015

Accepted26 May 2015

Published11 Jun 2015

Abstract

Elevated systolic pulmonary artery pressure (s-PAP, ≥35 mmHg) serves as an independent predictor of mortality in hemodialysis (HD) and diabetic (DM) patients. A polymorphism in the antioxidant Haptoglobin (Hp) gene has been shown to regulate the bioavailability of nitric oxide (NO), a major mediator of pulmonary vascular tone. We therefore set out to test the hypothesis that the Hp polymorphism may be a determinant of developing elevated s-PAP specifically in the DM state due to a decreased bioavailability of NO. To test our hypothesis we Hp typed and performed transthoracic echocardiography on a series of HD patients and stratified them into elevated and normal s-PAP groups and then evaluated whether there was a significant association between the Hp type, elevated s-PAP, and decreased NO bioavailability as defined by low plasma nitrite. We found a statistically significant interaction between the Hp type and DM on the prevalence of elevated s-PAP and lower mean nitrite levels with the combination of elevated s-PAP and low nitrite levels being significantly more prevalent in Hp 2-2 DM individuals. We conclude that the Hp 2 type is associated with elevated s-PAP levels and low plasma nitrite levels in HD patients specifically in the DM state.

1. Introduction

Pulmonary hypertension (PHT) is an elevation of systolic pulmonary arterial pressure (s-PAP) and resistance that can be the result of heart, lung, or systemic disorders [1, 2]. It is defined as a mean s-PAP exceeding 30 mmHg as measured by right heart catheterization (invasive gold standard) or as an estimated pulmonary artery pressure (e-PASP) exceeding 35 mm/Hg level as measured by Doppler echocardiography [1–3].

PHT involves vasoconstriction and obliteration of the lumen of small vessels in the lungs by plexiform lesions resulting in increased resistance to flow [1–3]. Recently, high e-PASP was recognized as a complication of chronic kidney disease (CKD) and end-stage renal disease (ESRD) [1, 2, 4–6]. We have previously shown a 40% incidence of unexplained high e-PASP in patients with ESRD on chronic hemodialysis (HD) therapy [2, 7–12] and that high e-PASP serves as an independent predictor of increased morbidity and mortality in HD patients [1, 2, 4, 8, 13–15]. Therefore, understanding the factors that contribute to high e-PASP in HD patients is of critical importance. Normally, pulmonary endothelial cells increase the synthesis of nitric oxide (NO) in response to increased pulmonary blood flow and pressure in an attempt to restore normal vascular tone [8]. Therefore, factors which may decrease NO bioavailability may directly impact e-PASP in HD patients.

Hp is an acute phase protein that acts as an antioxidant by virtue of its ability to bind free hemoglobin (Hb) and prevent heme-iron mediated oxidation [16–18]. When Hb is released into the circulation, it binds immediately to Hp to form a Hp-Hb complex that is rapidly removed predominately by the macrophage CD163 scavenger receptor expressed on Kupfer cells in the liver [18–23]. A polymorphism at the Hp locus (rs72294371) is associated with three possible Hp genotypes and protein phenotypes denoted 1-1, 2-1, and 2-2 [24]. The Hp protein products of the Hp 1 and Hp 2 alleles differ in both their biochemical and their functional properties such as the ability to serve as an antioxidant and to clear Hb from the plasmatic compartment [19, 21, 25] and these differences are exaggerated in Diabetes Mellitus (DM). The importance of the aforementioned differences in Hb clearance by Hp type is that extra corpuscular Hb has been shown to markedly reduce NO bioavailability in serum [26, 27]. In this study, we set out to test the hypothesis that individuals with the Hp 2 allele would have higher e-PASP specifically in the DM state due to a decreased bioavailability of NO.

2. Subjects and Methods

2.1. Study Design

The current study is a multicenter cross-sectional analysis that was carried out to assess whether the Hp 2 phenotype (Hp 2-2 or Hp 2-1) is associated with elevated e-PASP and decreasing NO bioavailability in DM and non-DM HD patients. The study included 122 HD patients from Baruch Padeh Medical Center and the Holy Family Hospital. 80% of these patients, without differences between the different Hp types, are under chronic treatment with Beta-Blockers, Calcium Channel Blockers, and Angiotensin Receptor Blockers (ARB) for arterial hypertension. Less than 10% of these patients are treated with statins for hypercholesterolemia, due to the high incidence of side effects in HD. All experiments were approved by the Helsinki Committee of both hospitals and informed consent was obtained from all participants. The study participants’ characteristics are presented in Table 1. During data analysis, we stratified the patients into two groups: patients with high e-PASP defined by an e-PASP ≥ 35 mmHg at rest and patients with normal e-PASP defined by e-PASP < 35 mmHg, and we then evaluated whether there was a significant association between Hp 2 phenotype and elevated e-PASP levels and between the Hp 2 phenotype and decreased NO bioavailability as defined by low plasma nitrite levels (less than 0.2 μM). Furthermore to evaluate the influence of DM on the frequency of high e-PASP or on the frequency of low plasma nitrite levels, we stratified members of each group (high and normal e-PASP) into those with and without DM.

2.2. Subjects

The study includes 122 HD patients (males and females), 81 patients with DM and 41 HD patients without DM. Exclusion criteria were severe lung disease, congestive heart failure, pregnancy, and any malignancy. Demographic and clinical data concerning patients (age, sex, diabetic status, comorbidities, and medications used) were obtained directly from the patients or from their hospital files.

2.3. Haptoglobin Typing

Hp phenotyping was performed on plasma samples by polyacrylamide gel electrophoresis as previously described [28]. In brief, 10 μL of Hb-enriched plasma was subjected to electrophoresis in a nondenaturing gel, and the gel was subsequently immersed in solution containing a congener of benzidine with a precipitate forming in the gel corresponding to the location of Hb-Hp complexes. The Hp type of the sample was determined by the banding pattern of the Hp-Hb complexes with each of the three Hp phenotypes having a characteristic banding fingerprint.

2.4. Echocardiographic Measurements of PASP

Estimated systolic pulmonary pressure (e-PASP) was estimated by Doppler echocardiography as described by Gladwin et al. [15]. To avoid overestimation of e-PASP due to volume overload, echo studies in the HD patients were performed within 1 h after completion of HD, when the patients were at optimal dry weight according to hydration status, blood pressure, and weight. Two experienced operators performed all the echocardiographic studies, using an Acuson Sequoia, Aspen, or 128 XP (Mountain View, CA) ultrasound machine. A complete two-dimensional M-mode and Doppler echocardiographic study was obtained from each patient. A tricuspid regurgitation systolic jet was recorded from the parasternal or apical window with the continuous-wave Doppler probe. Systolic right ventricular (or pulmonary artery) pressure was calculated using the modified Bernoulli equation: PAP = 4 × (tricuspid systolic jet)² + 10 mmHg (estimated right atrial pressure). High e-PASP was defined as an e-PASP ≥ 35 mmHg at rest.

2.5. Measurement of Plasma Nitrite

Plasma nitrite was used as a measure of NO bioavailability as this measure has been shown to reflect NOS function [29–32]. For this measurement, blood was drawn into Lithium-Heparin tubes and immediately centrifuged for 2 minutes and the plasma was quickly frozen in dry ice and stored at −20°C until the nitrite measurements were performed. Plasma was mixed with an equal volume of 100% methanol, vortexed, and centrifuged at 11,500 g for 10 minutes. The supernatant was loaded into 96-well plates and nitrite concentrations were measured using an ENO-20 NO_x analyzer (EICOM, San Diego, CA, USA). The nitrite was separated via column chromatography and reacted individually with the Griess reagent to synthesize a red diazo compound that was read at a wavelength of 540 nm by a visible light detector in the ENO-20. A level of plasma nitrite of below 0.2 μM was defined as low based on previous studies [33–40] demonstrating that the normal mean plasma nitrite is approximately 0.2 μM.

2.6. Statistics

Patients were stratified into high e-PASP (≥35 mmHg) and normal e-PASP groups. Cross-tabulation and Pearson’s chi-square tests were used to evaluate the prevalence of the three different Hp phenotypes in each group. Logistic regression analysis was used to evaluate interaction between Hp phenotypes and DM on high e-PASP levels. In this logistic regression model, the e-PASP group (high versus normal) was set as a dependent variable (binary outcome). Hp phenotypes, DM, and the interaction of Hp phenotype and DM were set as independent variables (covariates). Logistic regression analysis was also used to evaluate interaction between Hp phenotypes and DM on low levels of nitrite (<0.2 μM). In this logistic regression model, the nitrite levels group (above 0.2 μM versus less than 0.2 μM) was set as a dependent variable (binary outcome). Hp phenotypes, DM, and the interaction of Hp phenotype and DM were set as independent variables (covariates). Proportion test, -test, chi-square test, and Fisher’s exact tests were used to determine significant associations between Hp phenotype and high e-PASP as well as between Hp phenotype and plasma nitrite levels. ANOVA tests were used to define significant differences in nitrite mean levels according to the Hp phenotype and between groups. Data analysis was done using IBM SPSS software version 20.0. The data are shown as mean ± SEM and a probability was considered statistically significant.

3. Results

3.1. E-PASP Is DM and Hp Type Dependent

PHT was defined as an estimated systolic pulmonary pressure (e-PASP) exceeding 35 mmHg by Doppler echocardiography. As shown in Figure 1(a) among individuals with high e-PASP there was a significant increase in DM as compared to non-DM individuals (). Furthermore, as demonstrated in Table 2, the prevalence of high e-PASP was significantly increased () only in individuals with the Hp 2 phenotype (Hp 2-2 and Hp 2-1). Logistic regression analysis demonstrated a statistically significant interaction between the Hp phenotype and DM on the prevalence of elevated e-PASP () with elevated e-PASP being significantly more prevalent in Hp 2-2 DM individuals () (Figure 1(b)).

(a)

(b)

Figure 1

E-PASP is increased in DM and in Hp 2-2. (a) Association of e-PASP and DM. Among individuals with high e-PASP, the prevalence of DM was significantly increased ( compared to non-DM individuals). There was no relationship between DM and e-PASP in individuals with normal e-PASP. (b) Association of Hp phenotype and e-PASP. DM dependent significant differences in the prevalence of high e-PASP seen in (a) above were only in study participants with the Hp 2-2 phenotype ( comparing prevalence of high e-PASP in Hp 2-2 participants with and without DM).

3.2. DM and Hp-Dependent Differences in Mean Plasma Nitrite Levels of HD Patients

Endothelial dysfunction contributes to increased rates of high e-PASP in DM and in HD patients. Hence, we sought to determine whether there were DM and Hp-dependent differences in NO bioavailability by measuring plasma nitrite levels of HD patients [32]. When comparing nitrite mean levels across the three Hp phenotypes, we found significantly lower mean nitrite levels in study participants with the Hp 2 phenotype (Hp 2-2 or Hp 2-1) compared with participants with Hp 1-1 phenotype (Figure 2). The Hp-dependent differences in the mean nitrite levels were statistically significant among DM () but not in non-DM study participants ().

3.3. Hp Genotype Dependent Differences in the Prevalence of NO Bioavailability

Low NO bioavailability as defined in the methods was a plasma nitrite of less than 0.2 μM. Logistic regression analysis demonstrated a significant effect of Hp phenotype on the prevalence of low NO bioavailability (). As shown in Figure 3, none of the Hp 1-1 study participants had nitrite levels below 0.2 μM compared with 16.3% of the Hp 2-1 and 28.3% of the Hp 2-2 phenotype participants ().

3.4. Low Nitrite Levels and DM Correlate with Elevated e-PASP Levels

Logistic regression analysis demonstrated a statistically significant relationship between low nitrite levels (below 0.2 μM) and the prevalence of high e-PASP (). As shown in Figure 4(a), 67% of study participants with nitrite levels below 0.2 μM had high e-PASP levels while only 36.2% of study participants with normal nitrite levels had high e-PASP (). Among those individuals with low nitrite levels and high e-PASP, 71% were Hp 2-2 ( compared with Hp 2-1 genotype, Figure 4(b)) and 90% of these Hp 2-2 individuals had DM (Figure 4(c)).

(a)

(b)

(c)

Figure 4

Decreased NO bioavailability is associated with e-PASP, DM, and the Hp 2-2 phenotype. (a) Association of low plasma nitrite and e-PASP. 67% of study participants with nitrite levels below 0.2 μM had high e-PASP levels while only 36% of individuals with normal nitrite levels had high e-PASP (). (b) Association of the Hp phenotype and low plasma nitrite and high e-PASP. 71% of individuals with low nitrite levels and high e-PASP had the Hp 2-2 phenotype ( compared to Hp 2-1 phenotype). (c) Association of DM and the Hp 2-2 genotype with low plasma nitrite and high e-PASP. 90% of all Hp 2-2 individuals who had low nitrite and high e-PASP had DM ( comparing prevalence of DM versus non-DM in this Hp 2-2 cohort with low nitrite and high e-PASP).

4. Discussion

Elevated e-PASP is an independent risk factor for increased morbidity and mortality in dialysis patients. In this study, we have demonstrated that there is a highly significant interaction between the Hp phenotype and DM on the prevalence of high e-PASP in individuals undergoing dialysis with a marked increase in the prevalence of high e-PASP in individuals with the Hp 2-2 phenotype and DM. These data also demonstrate that the Hp 1-1 phenotype may exert a protective role in dialysis patients against developing high e-PASP.

The increased risk of developing high e-PASP in Hp 2-2 DM was associated with a marked reduction in NO bioavailability in this study. These results are consistent with recently published work demonstrating that the Hp polymorphism may modulate NO bioavailability in preeclampsia [25].

NO is known to play a key role in regulating pulmonary vascular tone. Free extra corpuscular Hb is increased in other conditions with pulmonary hypertension, including pulmonary embolism, and this condition is associated with increased NO consumption [41].

Accordingly, differences between individuals in factors that influence the clearance of Hb may influence NO bioavailability and increasing the steady state concentration of free Hb could cause pulmonary hypertension. We have previously demonstrated an interaction between the Hp genotype and DM on the clearance of free Hb [42] and on the expression of CD163, the Hp-Hb scavenger receptor in man [18]. We hypothesize that the major reason for the reduced bioavailability of NO in the plasma Hp 2-2 DM individuals is due to increased plasma Hb in these individuals due to a slower clearance of Hb in this population. In Hp 2-2 DM individuals, we have shown that this Hb is tethered to HDL and Hb tethered to HDL has been shown to reduce NO bioavailability [43, 44]. The tethering of Hb to HDL is via a specific interaction of Hp with helix 6 of ApoA1, the major protein component of HDL. Every day approximately 650 mg of Hb is released into the blood stream and the fate of this extra corpuscular Hb is Hp genotype dependent with the Hp-Hb complex being cleared from the plasmatic compartment by the macrophage CD163 receptor. The Hp 1-1 protein clears Hb more quickly than the Hp 2-2 protein and so there is more Hp 2-2-Hb available to bind to ApoA1 in Hp 2-2 individuals [45, 46]. NO bioavailability may also be reduced to increased presence of reactive oxygen species (ROS) that react with NO and that are formed due to redox activity of cell-free hemoglobin [43, 44] which is increased in Hp 2-2 DM individuals. While it is known that drugs can also influence plasma nitrite levels (in particular statins) [47], we believe that this is unlikely to explain the current findings as less than 10% of these patients are treated with statins with no Hp or DM dependent differences in drugs administered in this study cohort.

5. Conclusion

In conclusion, these studies suggest a potential mechanism explaining why Hp 2-2 DM may predispose to high e-PASP and possibly a clinically relevant target endpoint for interventional studies to try to reduce morbidity and mortality in Hp 2-2 DM dialysis patients. If these data are confirmed, patients entering the HD program might be screened for Hp phenotype and e-PASP and for patients with preexisting elevated e-PASP peritoneal dialysis or preemptive kidney transplantation could be considered. These studies suggest that extra corpuscular Hb derived iron may play a major role in developing elevated e-PASP and therefore strategies to reduce NO scavenging by this extra corpuscular Hb iron via iron chelation therapy may reduce e-PASP. It is of considerable interest that a recent study [48] showing marked benefit from chelation therapy on cardiovascular disease in DM may have been mediated through reducing iron mediated vascular disease in Hp 2-2 DM individuals. It is therefore sobering that perhaps the high doses of IV iron which the HD population is currently receiving may have untoward effects.

Conflict of Interests

The institution of Andrew Levy owns rights to a patent that the Haptoglobin phenotype can predict diabetic complications.

Acknowledgments

The authors acknowledge NIH Grant HL058091 to Daniel B. Kim-Shapiro for support of work conducted at Wake Forest and the Israel Science Foundation grant to Andrew P. Levy as well as Basem Hijazi for his important help in data analysis. All authors have read the journal’s authorship agreement and policy on disclosure of potential conflict of interests.

References

R. Miller-Lotan, Y. Herskowitz, S. Kalet-Litman et al., “Increased renal hypertrophy in diabetic mice genetically modified at the haptoglobin locus,” Diabetes/Metabolism Research and Reviews, vol. 21, no. 4, pp. 332–337, 2005.
View at: Publisher Site | Google Scholar
M. Yigla, F. Nakhoul, A. Sabag et al., “Pulmonary hypertension in patients with end-stage renal disease,” Chest, vol. 123, no. 5, pp. 1577–1582, 2003.
View at: Publisher Site | Google Scholar
L. J. Rubin, “Pathology and pathophysiology of primary pulmonary hypertension,” The American Journal of Cardiology, vol. 75, no. 3, pp. 51A–54A, 1995.
View at: Publisher Site | Google Scholar
M. E. Sise, A. M. Courtwright, and R. N. Channick, “Pulmonary hypertension in patients with chronic and end-stage kidney disease,” Kidney International, vol. 84, no. 4, pp. 682–692, 2013.
View at: Publisher Site | Google Scholar
S. Archer and S. Rich, “Primary pulmonary hypertension: a vascular biology and translational research ‘work in progress’,” Circulation, vol. 102, no. 22, pp. 2781–2791, 2000.
View at: Publisher Site | Google Scholar
M. Yigla, S. Dabbah, Z. S. Azzam, A.-H. Rubin, and S. A. Reisner, “Background diseases in 671 patients with moderate to severe pulmonary hypertension,” The Israel Medical Association Journal, vol. 2, no. 9, pp. 684–689, 2000.
View at: Google Scholar
M. Yigla, R. Banderski, Z. S. Azzam, S. A. Reisner, and F. Nakhoul, “Arterio-venous access in end-stage renal disease patients and pulmonary hypertension,” Therapeutic Advances in Respiratory Disease, vol. 2, no. 2, pp. 49–53, 2008.
View at: Publisher Site | Google Scholar
F. Nakhoul, M. Yigla, R. Gilman, S. A. Reisner, and Z. Abassi, “The pathogenesis of pulmonary hypertension in haemodialysis patients via arterio-venous access,” Nephrology Dialysis Transplantation, vol. 20, no. 8, pp. 1686–1692, 2005.
View at: Publisher Site | Google Scholar
J. Etemadi, H. Zolfaghari, R. Firoozi et al., “Unexplained pulmonary hypertension in peritoneal dialysis and hemodialysis patients,” Revista Portuguesa de Pneumologia, vol. 18, no. 1, pp. 10–14, 2012.
View at: Publisher Site | Google Scholar
M. Yigla, Z. Keidar, I. Safadi, N. Tov, S. A. Reisner, and F. Nakhoul, “Pulmonary calcification in hemodialysis patients: correlation with pulmonary artery pressure values,” Kidney International, vol. 66, no. 2, pp. 806–810, 2004.
View at: Publisher Site | Google Scholar
M. Barak, F. Nakhoul, and Y. Katz, “Pathophysiology and clinical implications of microbubbles during hemodialysis,” Seminars in Dialysis, vol. 21, no. 3, pp. 232–238, 2008.
View at: Publisher Site | Google Scholar
B. Kawar, T. Ellam, C. Jackson, and D. G. Kiely, “Pulmonary hypertension in renal disease: epidemiology, potential mechanisms and implications,” American Journal of Nephrology, vol. 37, no. 3, pp. 281–290, 2013.
View at: Publisher Site | Google Scholar
M. Yigla, Z. Abassi, S. A. Reisner, and F. Nakhoul, “Pulmonary hypertension in hemodialysis patients: an unrecognized threat,” Seminars in Dialysis, vol. 19, no. 5, pp. 353–357, 2006.
View at: Publisher Site | Google Scholar
M. Yigla, O. Fruchter, D. Aharonson et al., “Pulmonary hypertension is an independent predictor of mortality in hemodialysis patients,” Kidney International, vol. 75, no. 9, pp. 969–975, 2009.
View at: Publisher Site | Google Scholar
M. T. Gladwin, V. Sachdev, M. L. Jison et al., “Pulmonary hypertension as a risk factor for death in patients with sickle cell disease,” The New England Journal of Medicine, vol. 350, no. 9, pp. 886–895, 2004.
View at: Publisher Site | Google Scholar
J. M. Makuc and D. Petrovič, “A review of oxidative stress related genes and new antioxidant therapy in diabetic nephropathy,” Cardiovascular and Hematological Agents in Medicinal Chemistry, vol. 9, no. 4, pp. 253–261, 2011.
View at: Publisher Site | Google Scholar
T. Costacou, R. E. Ferrell, and T. J. Orchard, “Haptoglobin genotype: a determinant of cardiovascular complication risk in type 1 diabetes,” Diabetes, vol. 57, no. 6, pp. 1702–1706, 2008.
View at: Publisher Site | Google Scholar
A. P. Levy, K. R. Purushothaman, N. S. Levy et al., “Downregulation of the hemoglobin scavenger receptor in individuals with diabetes and the Hp 2-2 genotype: implications for the response to intraplaque hemorrhage and plaque vulnerability,” Circulation Research, vol. 101, no. 1, pp. 106–110, 2007.
View at: Publisher Site | Google Scholar
S. K. Moestrup and H. J. Moller, “CD163: a regulated hemoglobin scavenger receptor with a role in the anti-inflammatory response,” Annals of Medicine, vol. 36, no. 5, pp. 347–354, 2004.
View at: Publisher Site | Google Scholar
M. Timmermann and P. Högger, “Oxidative stress and 8-iso-prostaglandin F_2α induce ectodomain shedding of CD163 and release of tumor necrosis factor-α from human monocytes,” Free Radical Biology and Medicine, vol. 39, no. 1, pp. 98–107, 2005.
View at: Publisher Site | Google Scholar
M. Melamed-Frank, O. Lache, B. I. Enav et al., “Structure-function analysis of the antioxidant properties of haptoglobin,” Blood, vol. 98, no. 13, pp. 3693–3698, 2001.
View at: Publisher Site | Google Scholar
M. Vardi, S. Blum, and A. P. Levy, “Haptoglobin genotype and cardiovascular outcomes in diabetes mellitus—natural history of the disease and the effect of vitamin e treatment. Meta-analysis of the medical literature,” European Journal of Internal Medicine, vol. 23, no. 7, pp. 628–632, 2012.
View at: Publisher Site | Google Scholar
R. Asleh, J. Guetta, S. Kalet-Litman, R. Miller-Lotan, and A. P. Levy, “Haptoglobin genotype- and diabetes-dependent differences in iron-mediated oxidative stress in vitro and in vivo,” Circulation Research, vol. 96, no. 4, pp. 435–441, 2005.
View at: Publisher Site | Google Scholar
A. P. Levy, R. Asleh, S. Blum et al., “Haptoglobin: basic and clinical aspects,” Antioxidants & Redox Signaling, vol. 12, no. 2, pp. 293–304, 2010.
View at: Publisher Site | Google Scholar
J. T. Sertório, R. Lacchini, L. M. Amaral et al., “Haptoglobin polymorphism affects nitric oxide bioavailability in preeclampsia,” Journal of Human Hypertension, vol. 27, no. 6, pp. 349–354, 2013.
View at: Publisher Site | Google Scholar
C. D. Reiter, X. D. Wang, J. E. Tanus-Santos et al., “Cell-free hemoglobin limits nitric oxide bioavailability in sickle-cell disease,” Nature Medicine, vol. 8, no. 12, pp. 1383–1389, 2002.
View at: Publisher Site | Google Scholar
V. C. Sandrim, M. F. Montenegro, A. C. T. Palei et al., “Increased circulating cell-free hemoglobin levels reduce nitric oxide bioavailability in preeclampsia,” Free Radical Biology and Medicine, vol. 49, no. 3, pp. 493–500, 2010.
View at: Publisher Site | Google Scholar
W. Koch, W. Latz, M. Eichinger et al., “Genotyping of the common haptoglobin Hp 1/2 polymorphism based on PCR,” Clinical Chemistry, vol. 48, no. 9, pp. 1377–1382, 2002.
View at: Google Scholar
P. Kleinbongard, A. Dejam, T. Lauer et al., “Plasma nitrite reflects constitutive nitric oxide synthase activity in mammals,” Free Radical Biology and Medicine, vol. 35, no. 7, pp. 790–796, 2003.
View at: Publisher Site | Google Scholar
T. Lauer, M. Preik, T. Rassaf et al., “Plasma nitrite rather than nitrate reflects regional endothelial nitric oxide synthase activity but lacks intrinsic vasodilator action,” Proceedings of the National Academy of Sciences of the United States of America, vol. 98, no. 22, pp. 12814–12819, 2001.
View at: Publisher Site | Google Scholar
P. M. Rhodes, A. M. Leone, P. L. Francis, A. D. Struthers, and S. Moncada, “The L-arginine: nitric oxide pathway is the major source of plasma nitrite in fasted humans,” Biochemical and Biophysical Research Communications, vol. 209, no. 2, pp. 590–596, 1995.
View at: Publisher Site | Google Scholar
D. B. Kim-Shapiro and M. T. Gladwin, “Pitfalls in measuring NO bioavailability using NOx,” Nitric Oxide, vol. 44, pp. 1–2, 2015.
View at: Publisher Site | Google Scholar
P. Kleinbongard, A. Dejam, T. Lauer et al., “Plasma nitrite concentrations reflect the degree of endothelial dysfunction in humans,” Free Radical Biology & Medicine, vol. 40, no. 2, pp. 295–302, 2006.
View at: Publisher Site | Google Scholar
P. Kleinbongard, T. Rassaf, A. Dejam, S. Kerber, and M. Kelm, “Griess method for nitrite measurement of aqueous and protein-containing samples,” Methods in Enzymology, vol. 359, pp. 158–168, 2002.
View at: Publisher Site | Google Scholar
T. D. Presley, A. R. Morgan, E. Bechtold et al., “Acute effect of a high nitrate diet on brain perfusion in older adults,” Nitric Oxide—Biology and Chemistry, vol. 24, no. 1, pp. 34–42, 2011.
View at: Publisher Site | Google Scholar
C. Liu, W. Zhao, G. J. Christ, M. T. Gladwin, and D. B. Kim-Shapiro, “Nitric oxide scavenging by red cell microparticles,” Free Radical Biology and Medicine, vol. 65, pp. 1164–1173, 2013.
View at: Publisher Site | Google Scholar
A. A. Kenjale, K. L. Ham, T. Stabler et al., “Dietary nitrate supplementation enhances exercise performance in peripheral arterial disease,” Journal of Applied Physiology, vol. 110, no. 6, pp. 1582–1591, 2011.
View at: Publisher Site | Google Scholar
G. D. Miller, A. P. Marsh, R. W. Dove et al., “Plasma nitrate and nitrite are increased by a high-nitrate supplement but not by high-nitrate foods in older adults,” Nutrition Research, vol. 32, no. 3, pp. 160–168, 2012.
View at: Publisher Site | Google Scholar
A. Dejam, C. J. Hunter, M. M. Pelletier et al., “Erythrocytes are the major intravascular storage sites of nitrite in human blood,” Blood, vol. 106, no. 2, pp. 734–739, 2005.
View at: Publisher Site | Google Scholar
D. A. Dobrosielski, T. Presley, A. Perlegas, A. P. Marsh, D. Kim-Shapiro, and W. J. Rejeski, “Plasma nitrite response in older women to a physical function test,” Aging Clinical and Experimental Research, vol. 22, no. 5-6, pp. 383–386, 2010.
View at: Publisher Site | Google Scholar
J. T. Sertório, E. M. Neto-Neves, C. A. Dias-Junior et al., “Elevated plasma hemoglobin levels increase nitric oxide consumption in experimental and clinical acute pulmonary thromboembolism,” Critical Care Medicine, vol. 41, no. 7, pp. e118–e124, 2013.
View at: Publisher Site | Google Scholar
R. Asleh, S. Blum, S. Kalet-Litman et al., “Correction of HDL dysfunction in individuals with diabetes and the haptoglobin 2-2 genotype,” Diabetes, vol. 57, no. 10, pp. 2794–2800, 2008.
View at: Publisher Site | Google Scholar
A. I. Alayash, “Oxygen therapeutics: can we tame haemoglobin?” Nature Reviews Drug Discovery, vol. 3, no. 2, pp. 152–159, 2004.
View at: Google Scholar
A. I. Alayash, R. P. Patel, and R. E. Cashon, “Redox reactions of hemoglobin and myoglobin: biological and toxicological implications,” Antioxidants and Redox Signaling, vol. 3, no. 2, pp. 313–327, 2001.
View at: Google Scholar
J. Watanabe, V. Grijalva, S. Hama et al., “Hemoglobin and its scavenger protein haptoglobin associate with ApoA-1-containing particles and influence the inflammatory properties and function of high density lipoprotein,” The Journal of Biological Chemistry, vol. 284, no. 27, pp. 18292–18301, 2009.
View at: Publisher Site | Google Scholar
I. Azarov, X. He, A. Jeffers et al., “Rate of nitric oxide scavenging by hemoglobin bound to haptoglobin,” Nitric Oxide: Biology and Chemistry, vol. 18, no. 4, pp. 296–302, 2008.
View at: Publisher Site | Google Scholar
C. Dezfulian, N. J. H. Raat, and M. T. Gladwin, “A pharmacogenomic study of atorvastatin effects on eNOS activity: do ‘statins’ modulate blood nitrite levels and intravascular oxidant stress in susceptible individuals?” Free Radical Biology & Medicine, vol. 41, no. 7, pp. 1041–1043, 2006.
View at: Publisher Site | Google Scholar
E. Escolar, G. A. Lamas, D. B. Mark et al., “The effect of an EDTA-based chelation regimen on patients with diabetes mellitus and prior myocardial infarction in the Trial to Assess Chelation Therapy (TACT),” Circulation: Cardiovascular Quality and Outcomes, vol. 7, no. 1, pp. 15–24, 2014.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2015 Inbal Dahan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

1243

Downloads

945

Citations