Ischemia modified albumin and carbonyl protein as potential biomarkers of protein oxidation in hemodialysis

Independent correlation between ischemia modified albumin and parathormone in hemodialysis patients

Introduction. Hemodialysis patients are the group which oxidative stress is found more exacerbated. Ischemia modified albumin (IMA) is a new and sensitive marker for ischemia and oxidative stress. At current study we evaluated relation between IMA and biochemical parameters in hemodialysis patients. Materials and Methods. Thirty-four patients on maintenance hemodialysis were included. Pre-hemodialysis and post-hemodialysis blood samples were taken. Serum IMA and biochemistry parameters were measured. Results. There was a positive correlation between alkaline phosphatase (ALP) and IMA (r=0,268, p<0,05), CRP and IMA (r=0,452, p=0,007), parathormone and IMA (r=0,436, p=0,010), There was a negative correlation between albumin and IMA (r=-0,338, p=0,05). Multiple regression analysis was run to predict IMA levels from parathormone, CRP and creatinine the model statistically significantly predicted relation p<0,05, R=0,506, out of four two variables added statistically significant to the prediction, PTH (p=0,006), CRP (p=0,029). In multiregression analysis, IMA was found to be associated with PTH and CRP independent of creatinine value. Conclusions. We showed for the first time that PTH is associated with IMA in hemodialysis patients, independent of the level of renal function.

Independent correlation between ischemia modified albumin and parathormone in hemodialysis patients

Introduction. Hemodialysis patients are the group which oxidative stress is found more exacerbated. Ischemia modified albumin (IMA) is a new and sensitive marker for ischemia and oxidative stress. At current study we evaluated relation between IMA and biochemical parameters in hemodialysis patients. Materials and Methods. Thirty-four patients on maintenance hemodialysis were included. Pre-hemodialysis and post-hemodialysis blood samples were taken. Serum IMA and biochemistry parameters were measured. Results. There was a positive correlation between alkaline phosphatase (ALP) and IMA (r=0,268, p<0,05), CRP and IMA (r=0,452, p=0,007), parathormone and IMA (r=0,436, p=0,010), There was a negative correlation between albumin and IMA (r=-0,338, p=0,05). Multiple regression analysis was run to predict IMA levels from parathormone, CRP and creatinine the model statistically significantly predicted relation p<0,05, R=0,506, out of four two variables added statistically significant to the prediction, PTH (p=0,006), CRP (p=0,029). In multiregression analysis, IMA was found to be associated with PTH and CRP independent of creatinine value. Conclusions. We showed for the first time that PTH is associated with IMA in hemodialysis patients, independent of the level of renal function.

Blood Thiol Redox State in Chronic Kidney Disease

Thiols (sulfhydryl groups) are effective antioxidants that can preserve the correct structure of proteins, and can protect cells and tissues from damage induced by oxidative stress. Abnormal levels of thiols have been measured in the blood of patients with moderate-to-severe chronic kidney disease (CKD) compared to healthy subjects, as well as in end-stage renal disease (ESRD) patients on haemodialysis or peritoneal dialysis. The levels of protein thiols (a measure of the endogenous antioxidant capacity inversely related to protein oxidation) and S-thiolated proteins (mixed disulphides of protein thiols and low molecular mass thiols), and the protein thiolation index (the molar ratio of the S-thiolated proteins to free protein thiols in plasma) have been investigated in the plasma or red blood cells of CKD and ESRD patients as possible biomarkers of oxidative stress. This type of minimally invasive analysis provides valuable information on the redox status of the less-easily accessible tissues and organs, and of the whole organism. This review provides an overview of reversible modifications in protein thiols in the setting of CKD and renal replacement therapy. The evidence suggests that protein thiols, S-thiolated proteins, and the protein thiolation index are promising biomarkers of reversible oxidative stress that could be included in the routine monitoring of CKD and ESRD patients.

Pilot study to investigate differences in middle molecules, oxidative stress and markers of peripheral vascular disease in patients treated by high flux haemodialysis and haemodiafiltration

Background

Dialysis patients have an increased risk of mortality. Recently treatment with haemodiafiltration (HDF) has been reported to reduce mortality, particularly cardiovascular mortality, compared to standard high-flux haemodialysis (HD). However, why HDF may offer a survival advantage remains to be determined. So, we conducted a pilot study to explore differences in middle-molecules, inflammation and markers of vascular disease in patients treated by HD and HDF.

Methods

Observational cross-sectional study measuring serum β2-microglobulin (β2M), Advanced Glycosylation End Products (AGEs) by skin autofluorescence (SAF), oxidative stress with ischaemia modified albumin ratio (IMAR) and peripheral vascular disease assessment using Ankle-Brachial Index (ABI), and arterial stiffness using Cardio-Ankle Vascular Index (CAVI).

Results

We studied 196 patients, mean age 69.1 ± 12.4 years, 172 (87.8%) treated by HD and 24 (12.2%) by HDF. Age, body mass index, co-morbidity and dialysis vintage were not different between HD and HDF groups. Middle molecules; β₂M (31±9.9 vs 31.2±10 ug/mL) and SAF (2.99±0.72 vs 3.0±0.84 AU), ABI (1.06±0.05 vs 1.07±0.10) and CAVI (9.34±1.55 vs 9.35±1.23) were not different, but IMAR was higher in the HD patients (38.4±14.8 vs 31.3 ± 17.4, P = 0.035)

Conclusions

In this pilot observational study, we found patients treated by HDF had lower oxidative stress as measured by IMAR, with no differences in middle molecules. Lower oxidative stress would be expected to have diverse protective effects on the cardiovascular system Although we found no differences in ABI and CAVI, future studies are required to determine whether reduced oxidative stress translates into clinically relevant differences over time.

The Effect of the Hydroalcoholic Extract of Watercress on the Levels of Protein Carbonyl, Inflammatory Markers, and Vitamin E in Chronic Hemodialysis Patients

Introduction

Chronic kidney disorder is a main public health concern. Inflammatory processes and oxidative stress are common in end-stage renal disease patients. We aimed to evaluate the effect of the hydroalcoholic extract of watercress (WC) on the inflammatory cytokines and protein carbonyl (PCO) contents in chronic hemodialysis patients.

Methods

This was a double-blind randomized clinical trial performed on 46 hemodialysis patients. The participants were randomly divided into two groups: intervention group (500 mg hydroalcoholic extract of WC every day for 4 weeks) and control group (500 mg of white flour every night for 4 weeks). The blood samples were taken to determine the levels of vitamin E, PCO, and inflammatory cytokines at baseline and the end of treatment.

Results

Forty-five patients completed the study (22 patients in the intervention group and 23 patients in the control group). There was a significant reduction in the PCO level (20.33 ± 4.40 vs. 15.06 ± 6.41, P=0.001) in the intervention group; also, this change was statistically significant relative to the control group. Furthermore, there were significant reductions in hs-CRP (8953.30 ± 5588.06 vs. 7249.86 ± 5091.62, P=0.007) and IL-6 (60.10 (55.99, 73.10) vs. 55.21 (53.39, 60.48), P=0.050) in the intervention group, but these changes were not significant in comparison with the control group.

Conclusion

We conclude that the hydroalcoholic extract of WC reduced the PCO content in hemodialysis patients via inhibition of protein oxidation. Although WC administration had caused a significant reduction in IL-6 and CRP levels, these differences were not statistically significant relative to the control group. Further research is needed to identify the antioxidant and anti-inflammatory effects of WC in hemodialysis patients.

Plasma Protein Carbonyls as Biomarkers of Oxidative Stress in Chronic Kidney Disease, Dialysis, and Transplantation

Accumulating evidence indicates that oxidative stress plays a role in the pathophysiology of chronic kidney disease (CKD) and its progression; during renal replacement therapy, oxidative stress-derived oxidative damage also contributes to the development of CKD systemic complications, such as cardiovascular disease, hypertension, atherosclerosis, inflammation, anaemia, and impaired host defence. The main mechanism underlying these events is the retention of uremic toxins, which act as a substrate for oxidative processes and elicit the activation of inflammatory pathways targeting endothelial and immune cells. Due to the growing worldwide spread of CKD, there is an overwhelming need to find oxidative damage biomarkers that are easy to measure in biological fluids of subjects with CKD and patients undergoing renal replacement therapy (haemodialysis, peritoneal dialysis, and kidney transplantation), in order to overcome limitations of invasive monitoring of CKD progression. Several studies investigated biomarkers of protein oxidative damage in CKD, including plasma protein carbonyls (PCO), the most frequently used biomarker of protein damage. This review provides an up-to-date overview on advances concerning the correlation between plasma protein carbonylation in CKD progression (from stage 1 to stage 5) and the possibility that haemodialysis, peritoneal dialysis, and kidney transplantation improve plasma PCO levels. Despite the fact that the role of plasma PCO in CKD is often underestimated in clinical practice, emerging evidence highlights that plasma PCO can serve as good biomarkers of oxidative stress in CKD and substitutive therapies. Whether plasma PCO levels merely serve as biomarkers of CKD-related oxidative stress or whether they are associated with the pathogenesis of CKD complications deserves further evaluation.

Effects of medium cut-off dialysis membranes on inflammation and oxidative stress in patients on maintenance hemodialysis

PURPOSE

Medium cut-off membranes were developed for providing increased clearance of larger middle-molecule uremic toxins. We compared the effect of low-flux, medium cut-off, and high-flux membranes on chronic inflammation and oxidative stress in patients with maintenance hemodialysis.

METHODS

A total of 42 patients were enrolled in this study. Total antioxidant status, total oxidant status, paraoxonase-1, ischemia-modified albumin, total Thiol, disulfide bond, and native Thiol were measured to determine oxidative stress. C-reactive protein was measured to define inflammation.

RESULTS

37% of the total patients were females, and the mean age was 52.9 ± 16 years. Serum albumin and Kt/V were similar between groups during the study period. We did not find any significant difference at baseline in the 3rd and 6th months of the study when we compared the inflammatory marker and oxidative indicator levels between three hemodialysis membranes in the whole study group. In the subgroup analysis of 19 patients with a high C-reactive protein level, we found that the medium cut-off membrane significantly reduced serum C-reactive protein level, when compared to low-flux and high-flux membrane [2.8 mg/L vs. 13.7 mg/L and 6.1 mg/L, respectively, p = 0.05]. However, we did not find a significant change in oxidative stress indicators in patients with high C-reactive protein levels between the three dialysers.

CONCLUSION

The medium cut-off membrane has favorable effects on inflammation in patients with maintenance hemodialysis. However, this positive effect could not be demonstrated in oxidative stress.

Advanced oxidation protein products in nondiabetic end stage renal disease patients on maintenance haemodialysis

In chronic kidney disease (CKD), the impairment of the excretory function leads to elevation in the blood concentrations of urea, creatinine, and various protein metabolic products. Advanced oxidation protein products (AOPP), along with protein carbonyls, protein-bound di-tyrosines and S-thiolated proteins, are considered biomarkers of oxidative stress in end-stage renal disease (ESRD) patients on maintenance haemodialysis (HD). In this study, we evaluated the correlations between plasma levels of AOPP (measured by size exclusion/gel filtration high performance liquid chromatography) and those of protein-bound di-tyrosines, protein carbonyls, albumin and fibrinogen in 50 nondiabetic ESRD patients on maintenance HD. Considering that AOPP could represent the bridge between oxidative stress and inflammation, having been identified as proinflammatory mediators, we also evaluated the association between AOPP levels, C-reactive protein concentration and white blood cells count. Finally, we assessed the associations between plasma level of AOPP and serum concentrations of creatinine and urea, both of which showed a strong dependence on the chronological age of haemodialysed patients. Taken together, our results confirm the robust relationship between uraemia and oxidative stress, especially when measured as biomarkers of severe protein oxidative damage (e.g. plasma AOPP).

Plasma Protein Carbonylation in Haemodialysed Patients: Focus on Diabetes and Gender

Patients with end-stage renal disease (ESRD) undergoing haemodialysis (HD) experience oxidative/carbonyl stress, which is postulated to increase after the HD session. The influence of diabetes mellitus and sex on oxidation of plasma proteins in ESRD has not yet been clarified despite that diabetic nephropathy is the most common cause of ESRD in developed and developing countries and despite the increasingly emerging differences between males and females in epidemiology, pathophysiology, clinical manifestations, and outcomes for several diseases. Therefore, this study aimed to evaluate the possible effect of type 2 diabetes mellitus, gender, and dialysis filter on plasma level of protein carbonyls (PCO) in ESRD patients at the beginning and at the end of a single HD session. Results show that mean post-HD plasma PCO levels are significantly higher than mean pre-HD plasma PCO levels and that the type of dialysis filter and dialysis technique are unrelated to plasma PCO levels. The mean level of plasma PCO after a HD session increases slightly but significantly in nondiabetic ESRD patients compared to diabetic ones, whereas it increases more markedly in women than in men. These novel findings suggest that women with ESRD are more susceptible than men to oxidative/carbonyl stress induced by HD.

Serum ischemia-modified albumin levels in adolescent smokers

BACKGROUND

It is known that the biochemical marker linked to tissue ischemia, ischemia-modified albumin (IMA), is related to oxidative stress. Cigarette smoking is a situation with increased oxidative stress causing cell damage and it is thought that many of the negative effects linked to smoking may occur after the biological material in the body is exposed to oxidative damage. This study aimed to identify variability in serum IMA levels in adolescents who smoke.

METHODS

This case-control study comprised 60 adolescents without any chronic disease. The smoking group was 30 adolescents between the ages of 14 and 17 years who smoked, while the control group was 30 healthy adolescents who did not smoke. Blood samples were collected from all subjects and serum IMA levels and serum nicotine metabolites were determined.

RESULTS

The serum IMA levels in the adolescents who smoked were 0.452±0.094 absorbance unit (ABSU), while the control group had ASBU levels of 0.427±0.054. There was no significant difference between the groups in terms of serum IMA levels (p=0.210). There was a significant difference between the control and smoking groups in terms of serum nicotine metabolite levels (p<0.001).

CONCLUSIONS

Among adolescents who smoke, serum IMA levels may not be a good marker for oxidative stress.

Protein Oxidation in the Lungs of C57BL/6J Mice Following X-Irradiation

Damage to normal lung tissue is a limiting factor when ionizing radiation is used in clinical applications. In addition, radiation pneumonitis and fibrosis are a major cause of mortality following accidental radiation exposure in humans. Although clinical symptoms may not develop for months after radiation exposure, immediate events induced by radiation are believed to generate molecular and cellular cascades that proceed during a clinical latent period. Oxidative damage to DNA is considered a primary cause of radiation injury to cells. DNA can be repaired by highly efficient mechanisms while repair of oxidized proteins is limited. Oxidized proteins are often destined for degradation. We examined protein oxidation following 17 Gy (0.6 Gy/min) thoracic X-irradiation in C57BL/6J mice. Seventeen Gy thoracic irradiation resulted in 100% mortality of mice within 127-189 days postirradiation. Necropsy findings indicated that pneumonitis and pulmonary fibrosis were the leading cause of mortality. We investigated the oxidation of lung proteins at 24 h postirradiation following 17 Gy thoracic irradiation using 2-D gel electrophoresis and OxyBlot for the detection of protein carbonylation. Seven carbonylated proteins were identified using mass spectrometry: serum albumin, selenium binding protein-1, alpha antitrypsin, cytoplasmic actin-1, carbonic anhydrase-2, peroxiredoxin-6, and apolipoprotein A1. The carbonylation status of carbonic anhydrase-2, selenium binding protein, and peroxiredoxin-6 was higher in control lung tissue. Apolipoprotein A1 and serum albumin carbonylation were increased following X-irradiation, as confirmed by OxyBlot immunoprecipitation and Western blotting. Our findings indicate that the profile of specific protein oxidation in the lung is altered following radiation exposure.

Ischemia-modified albumin levels in overt and subclinical hypothyroidism

BACKGROUND

Free radical-mediated oxidative stress (OS) has been implicated in the pathogenesis of thyroid disorders. The ischemia-modified albumin (IMA) has been proposed as a marker of protein oxidative damage, which has been found to reflect hypoxic stress.

AIM

Our aim was to evaluate IMA, malondialdehyde (MDA), and reduced glutathione (GSH) levels in patients with overt hypothyroidism (OHT) and subclinical hypothyroidism (SHT) in comparison to euthyroid controls.

SUBJECTS AND METHODS

Albumin, IMA, IMA/albumin ratio, MDA, GSH, total cholesterol (TC), triglycerides (TG), HDL-Cholesterol were assessed in 105 subjects grouped into OHT, SHT patients, and euthyroid controls with 35 subjects in each group.

RESULTS

MDA and IMA levels were significantly elevated while the GSH concentrations were significantly lower in OHT and SHT patients compared to controls (p < 0.01). When IMA values were normalized for albumin concentrations, the IMA/albumin ratio was also significantly elevated in both patient groups compared to controls (p < 0.01). These changes were more pronounced in the OHT group when compared to SHT group. In OHT group, thyroid-stimulating hormone (TSH) levels showed significant positive correlation with MDA (r = 0.470, p = 0.004), IMA (r = 0.530, p = 0.001), and IMA/albumin ratio (r = 0.525, p = 0.001). Both IMA (r = -0.342, p = 0.041), IMA/albumin ratio (r = -0.378, p = 0.023) showed significant negative correlation with GSH in OHT patients. No significant correlation between variables was, however, observed in SHT group.

CONCLUSIONS

Increase of MDA and IMA levels with decreased antioxidant status indicate the presence of OS in hypothyroid patients, which was more pronounced in OHT patients. Elevated levels of IMA can be a clinically useful marker of protein oxidative damage and OS in hypothyroidism.

Prognostic relevance of ischemia-modified albumin and NT-proBNP in patients with peripheral arterial occlusive disease

BACKGROUND

Cardiovascular morbidity is high among patients with peripheral arterial occlusive disease (PAOD). The aim of this study was to evaluate the ability of ischemia-modified albumin (IMA), N-terminal proBNP (NT-proBNP), and high-sensitive cardiac Troponin T (hs-cTnT) to predict cardiovascular complications in male patients with Fontaine stage II PAOD.

METHODS

68 men with stage II PAOD underwent treadmill testing. NT-proBNP, IMA and hs-cTnT were measured before and after exercise. Patients were followed up prospectively and complete follow-up data were available for 66 individuals.

RESULTS

Median follow-up time was 43.0months. 12 (18.2%) patients had suffered from a major adverse cardiac event (MACE). IMA and NT-proBNP baseline concentrations were significantly higher in patients who developed MACE during follow-up: IMA: 110.6±2.4kU/L vs. 102.5±0.9kU/L (p<0.001); NT-proBNP: 270.5±295.9ng/L vs. 84.6±15.4ng/L (p=0.007). In multivariable regression models only IMA was significantly associated with the primary endpoint (HR=1.07, CI 1.01-1.13; p=0.029).

CONCLUSION

In the present study, a serum concentration of >103.9kU/L of IMA was a better independent predictor of MACE than NT-proBNP or hs-cTnT. IMA might be a valuable tool for risk stratification in PAOD patients.

Increased ischaemia-modified albumin is associated with inflammation in acute rheumatic fever

INTRODUCTION

Ischaemia-modified albumin, a novel biochemical marker for tissue ischaemia, was found to be associated with oxidative stress. The purpose of this study was to assess the role of ischaemia-modified albumin in the diagnosis of acute rheumatic fever and also to evaluate the ischaemia-modified albumin levels in children with heart valve disease.

METHODS

The study groups, aged 5-18 years, consisted of 128 individuals - 40 with acute rheumatic fever, 35 with congenital heart valve disease, 33 with chronic rheumatic heart disease, and 20 healthy control subjects.

RESULTS

The ischaemia-modified albumin, erythrocyte sedimentation rate, and C-reactive protein levels of the acute rheumatic fever group were significantly higher than those in the chronic rheumatic heart disease, congenital heart valve disease, and control groups, separately (p < 0.001). The ischaemia-modified albumin levels in both carditis and isolated arthritis subgroups of children with acute rheumatic fever were significantly higher than in the control group (p < 0.001, p < 0.01, respectively). However, there was no statistically significant difference between the chorea subgroup and control subjects. In addition, significant correlations were observed between ischaemia-modified albumin and acute phase reactants of patients with acute rheumatic fever (p < 0.001 for both erythrocyte sedimentation rate and C-reactive protein). The ischaemia-modified albumin levels of chronic rheumatic heart disease, congenital heart valve disease, and control subjects were similar.

CONCLUSIONS

The increased level of ischaemia-modified albumin in children with acute rheumatic fever seems to be associated with inflammation. However, further studies are needed to provide stronger evidence.

Ischemia-modified albumin, a predictive marker of major adverse cardiovascular events in continuous ambulatory peritoneal dialysis patients

OBJECTIVES

The aim of this study was to evaluate the efficiency of ischemia-modified albumin (IMA) for predicting major adverse cardiovascular events (MACE) in continuous ambulatory peritoneal dialysis (CAPD) patients.

DESIGN AND METHODS

A prospective observational study was conducted with 120 CAPD patients and 37 healthy volunteers. Demographic and clinical data were collected. The primary end point is the occurrence of MACE.

RESULTS

A total of 157 participants with a mean age of 43.64 years finally completed this study. The CAPD patients had a significantly high rate of MACE (P=0.001) and high levels of IMA than healthy controls (P<0.001). Compared with CAPD patients with normal levels of IMA, the CAPD patients with high levels of IMA (>85 kU/L) had lower non-MACE survival rate (P<0.001), which indicated that the high IMA CAPD patients may suffer a high rate of MACE. In addition, the high IMA CAPD patients also had a low level of serum albumin (P<0.001) and hemoglobin (P=0.018). The correlation analysis showed that the serum albumin level was the most effective factor influencing IMA (B=-0.967, P<0.001).

CONCLUSIONS

CAPD patients with high levels of IMA had a high incidence rate of MACE. IMA was a good predictive marker of MACE and might be important in cardiovascular risk stratification of CAPD patients.