Original Article
Determinants of thromboxane biosynthesis in patients with moderate to severe chronic kidney disease

https://doi.org/10.1016/j.ejim.2016.06.016Get rights and content

Highlights

  • β€’

    Levels of both urinary 11-dehydro-TXB2 and 8-iso-PGF2Ξ± increased sequentially across the four CKD stages.

  • β€’

    Both urinary prostanoids were inversely associated with eGFR and hemoglobin levels (PΒ <Β 0.0001).

  • β€’

    A significant direct correlation was observed between urinary 11-dehydro-TXB2 and 8-iso-PGF2Ξ± (PΒ <Β 0.0001).

  • β€’

    Urinary 8-iso-PGF2Ξ±, hemoglobin levels and eGFR were independent predictors of urinary 11-dehydro-TXB2.

  • β€’

    This study provides biochemical evidence of persistent platelet activation in patients with CKD.

Abstract

Background

Mechanisms of accelerated atherothrombosis in patients with chronic kidney disease (CKD) are only partly characterized. The aims of this study were to evaluate the extent of thromboxane (TX)-dependent platelet activation in patients with CKD, and to characterize the determinants of altered TX biosynthesis in this setting, with particular reference to enhanced lipid peroxidation, low grade inflammation and CKD-related anemia.

Patients and methods

A cross sectional comparison between urinary 8-iso-PGF2Ξ± and 11-dehydro-TXB2, in vivo markers of oxidative stress and platelet activation, respectively, was performed in 115 patients with stage 1–4 CKD.

Results

Levels of both urinary 11-dehydro-TXB2 and 8-iso-PGF2Ξ± increased sequentially across the four CKD stages (PΒ <Β 0.0001, Kruskal–Wallis test). Both urinary prostanoids were inversely associated with either estimated glomerular filtration rate (eGFR, PΒ <Β 0.0001) or hemoglobin levels (PΒ <Β 0.0001). A significant direct correlation was also observed between urinary 11-dehydro-TXB2 and 8-iso-PGF2Ξ± (RhoΒ =Β 0.620, PΒ <Β 0.0001). On multivariate analysis, urinary 8-iso-PGF2Ξ± (Ξ²Β =Β 0.459, PΒ <Β 0.0001), hemoglobin levels (Ξ²Β =Β βˆ’ 0.261, PΒ =Β 0.002) and eGFR (Ξ²Β =Β βˆ’Β 0.172, PΒ =Β 0.032) were independent predictors of urinary 11-dehydro-TXB2 (adjusted R2Β =Β 0.488).

Conclusions

This study provides biochemical evidence of persistent platelet activation in patients with CKD. This condition occurs early in the natural history of the disease and is related to kidney function and oxidative stress. Moreover, we found an independent inverse relationship between hemoglobin levels and TX-dependent platelet activation. This finding may provide a mechanistic link between CKD-related anemia and increased cardiovascular risk.

Introduction

Cardiovascular disease (CVD) has been shown to be a critical factor influencing quality of life and mortality in patients with chronic kidney disease (CKD). There is a well-established association of CKD with the development of atherosclerosis and its thromboembolic complications [1], [2], [3], [4], [5]. In particular, an independent, graded, inverse relationship between estimated glomerular filtration rate (eGFR) and cardiovascular event rates has emerged from large-scale observational studies [1], [6] and CVD is increased in early-stage CKD [7].

Despite these findings, the mechanisms responsible for accelerated atherogenesis remain elusive. Clustering of cardiovascular risk factors such as sustained arterial hypertension, altered lipoprotein levels, diabetes mellitus, or obesity is often observed in CKD [8]. Nonetheless, classical risk factors poorly perform in the prediction of cardiovascular outcomes in this population, thus fostering interest into emerging risk factors.

Oxidative stress has been postulated to be a relevant risk factor for CVD in CKD patients [9], [10], [11], developing from an imbalance between increased free radical production due to dysfunctional mitochondria and reduced antioxidant defenses.

Increased reactive oxidant species (ROS) formation leads to increased lipid peroxidation. A series of bioactive prostaglandin (PG) F2-like compounds (isoprostanes) has been discovered, which represent specific end-products from free radical damage [12], [13]. Among these products, the most meaningful is 8-iso-PGF2Ξ±, which induces vasoconstriction and modulates the function of human platelets [12] and whose levels are increased in association with CVD [12], [14]. F2-isoprostanes can be reliably measured both in plasma and in urine [12]. However, since they are rapidly metabolized, any increase in plasma isoprostane concentration may be due not only to their increased formation from lipid peroxidation, but also to decreased metabolism [15]. Thus, only measurement of F2-isoprostanes in the urine provides a reliable measure of persistent whole-body oxidative stress [12], [15]. However, most of the available studies on isoprostane formation and loss of kidney function have reported increased plasma levels of these iso-eicosanoids, early in the progression of CKD [16], [17], [18].

Enhanced generation of 8-iso-PGF2Ξ± and other biologically active iso-eicosanoids could contribute to persistent platelet activation, as reflected by enhanced urinary 11-dehydro-thromboxane (TX)B2, an enzymatic metabolite of TXA2 [12], [19]. Therefore, the present study was specifically designed to investigate whether urinary 8-iso-PGF2Ξ± excretion rate is altered in CKD patients and whether it correlates with the rate of TXA2 biosynthesis. We also assessed the relative contribution of oxidative stress and TX-dependent platelet activation to CKD stage, impairment of eGFR, proteinuria, CVD factors including diabetes mellitus, plasma uric acid, and hemoglobin (Hb) levels, which have been inversely associated with mortality [20].

Section snippets

Study design and population

This is a cross-sectional observational study. A total of 115 adult Caucasians [median age (IQR) 63 (57–68) years, 81 (70.4%) males] were consecutively recruited from four nephrology outpatient clinics. All patients included in the study were diagnosed as having CKD according to National Kidney Foundation K/DOQI Guidelines [21].

We used a modified National Kidney Foundation classification of CKD, which classifies estimated GFR in the following ranges: at least 60Β mL per minute per 1.73Β m2 (stages

Characteristics of the subjects

Table 1 depicts clinical characteristics and laboratory data of CKD patients according to their eGFR group. Twenty-seven out of 115 CKD patients (23.5%) were diabetics, 88 (76.5%) had systemic arterial hypertension, and 26 (22.6%) had a history of major cardiovascular events (myocardial infarction/stroke). As expected, patients in stage 3–4 were older [69.7 (61.7–76.0) vs. 63.0 (57.0–68.0), PΒ =Β 0.001], and had more frequently arterial hypertension (84.6% vs. 59.5%, PΒ =Β 0.005), anemia (51.3% vs.

Discussion

The risk of developing CVD is high among CKD patients and, as a result, cardiovascular-related complications account for high morbidity and mortality [1], [6]. Multiple factors contribute to CVD in CKD patients, including not only cardiovascular risk factors such as hypertension, diabetes, hyperlipidemia, but also non-traditional factors such as low-grade inflammation, anemia and hyperuricemia [27], [28], [29], [30], [31], [32], [33]. Each one of these complications needs to be identified and

Conclusion

In our study, we have characterized a sensitive marker of in vivo platelet activation, which is abnormal in a higher percentage of CKD patients in stages 3–4 as compared to stages 1–2. Although the mechanisms responsible for platelet activation are likely to be multifactorial in this setting (e.g. endothelial injury, disease-or-treatment metabolic disorders), we provide evidence that progressive renal disease is associated with in vivo TX-dependent platelet activation, which is also affected by

Declaration of interest

The authors declare no conflicts of interests. The authors alone are responsible for the content and writing of this article.

Acknowledgments

We thank Dr. Rossella Liani and Dr. Francesca La Farina for their technical support and expert editorial assistance.

References (58)

  • M. Bonaccio et al.

    Age-sex specific ranges of platelet count and all-cause mortality: prospective findings from the MOLI-SANI study

    Blood

    (2016)
  • A.S. Go et al.

    Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization

    N Engl J Med

    (2004)
  • C. Zoja et al.

    Role of platelets in progressive glomerular diseases

    Pediatr Nephrol

    (1995)
  • S. Tomura et al.

    Activation of platelets in patients with chronic proliferative glomerulonephritis and the nephrotic syndrome

    Clin Nephrol

    (1982)
  • J.S. Cameron

    Platelets in glomerular disease

    Annu Rev Med

    (1984)
  • K. Matsushita et al.

    Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis

    Lancet

    (2010)
  • E.L. Schiffrin et al.

    Chronic kidney disease: effects on the cardiovascular system

    Circulation

    (2007)
  • J. Coresh et al.

    Epidemiology of cardiovascular risk factors in chronic renal disease

    J Am Soc Nephrol

    (1998)
  • D.M. Small et al.

    Oxidative stress, anti-oxidant therapies and chronic kidney disease

    Nephrology (Carlton)

    (2012)
  • R.L. Dumaine et al.

    Renal function, atherothrombosis extent, and outcomes in high-risk patients

    Am Heart J

    (2009)
  • F. Stam et al.

    Endothelial dysfunction contributes to renal function-associated cardiovascular mortality in a population with mild renal insufficiency: the Hoorn study

    J Am Soc Nephrol

    (2006)
  • F. Santilli et al.

    Oxidative stress drivers and modulators in obesity and cardiovascular disease: from biomarkers to therapeutic approach

    Curr Med Chem

    (2015)
  • Z.J. Zhang

    Systematic review on the association between F2-isoprostanes and cardiovascular disease

    Ann Clin Biochem

    (2013)
  • J. Nourooz-Zadeh

    Key issues in F2-isoprostane analysis

    Biochem Soc Trans

    (2008)
  • E. Spandou et al.

    Erythropoietin attenuates renal injury in experimental acute renal failure ischaemic/reperfusion model

    Nephrol Dial Transplant

    (2006)
  • I.S.P. Karamouzis et al.

    Increase in oxidative stress but not in antioxidant capacity with advancing stages of chronic kidney disease

    Am J Nephrol

    (2008)
  • G. Davi et al.

    Platelet activation and atherothrombosis

    N Engl J Med

    (2007)
  • Z. Jing et al.

    Hemoglobin targets for chronic kidney disease patients with anemia: a systematic review and meta-analysis

    PLoS One

    (2012)
  • National Kidney Foundation

    K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification

    Am J Kidney Dis

    (2002)
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    1

    Natale Vazzana and Francesca Santilli contributed equally to this manuscript and should be considered joint first authors.

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