Haptoglobin phenotype and vascular complications in patients with diabetes

Haptoglobin phenotype and levels in type 2 diabetes and effects of fenofibrate

AIMS/HYPOTHESIS

In diabetes haptoglobin (Hp) 2 vs Hp 1 allelic product is associated with cardiac and renal complications. Few studies report both Hp phenotype and Hp levels. In a Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial substudy we evaluated the Hp phenotype, Hp levels, and fenofibrate effects.

MATERIALS AND METHODS

In 480 adults with type 2 diabetes (T2D) the Hp phenotype was assessed and the Hp level quantified (both using ELISAs assays) in plasma from baseline, after 6 weeks of fenofibrate, and (in n = 200) at 2 years post-randomization to fenofibrate or placebo.

RESULTS

The Hp phenotypes 1-1, 2-1, and 2-2 frequencies were 15%, 49%, and 36%, respectively. Baseline Hp levels differed by phenotype (P < 0.0001) and decreased (median 21%) after 6 weeks fenofibrate in all phenotypes (adjusted mean (95% CI): -0.27 (-0.32, -0.23) mg/mL in Hp 1-1, -0.29 (-0.31, -0.27) mg/mL in Hp 2-1 and -0.05 (-0.07, -0.02) mg/mL in Hp 2-2 (P = 0.005 and P = 0.055 vs Hp 1-1 and Hp 2-1, respectively)). At 2 years post-randomization the Hp levels in the placebo group had returned to baseline, whilst the fenofibrate-group levels remained similar to the 6 week levels.

CONCLUSIONS

In type 2 diabetes, Hp levels differ by Hp phenotype and are decreased by fenofibrate in all phenotypes, but the effect is diminished in Hp 2-2.

N-glycosylation of disease-specific haptoglobin for the early screening of diabetic retinopathy

PURPOSE

Diabetic retinopathy (DR), as one of the microvascular complications of diabetes, is a leading cause of acquired vision loss. Most DR cases are detected in the advanced stage through fundoscopy, making molecular biomarkers urgently needed for early diagnosis of DR.

EXPERIMENTAL DESIGN

Serum disease-specific haptoglobin-β (Hp-β) chains of 100 patients with type 2 diabetes mellitus (T2DM) and 156 T2DM patients with non-proliferative diabetic retinopathy (NPDR) were separated using polyacrylamide gel electrophoresis. After in-gel digestion and enrichment, the intact N-glycopeptides were detected by mass spectrometry.

RESULTS

Fucosylation of Hp-β was significantly increased and sialylation of Hp-β was significantly decreased in background DR (BDR, an early-stage DR) patients compared with non-diabetic retinopathy patients (p < 0.05) and yielded area under curves (AUCs) of 0.801 and 0.829 in training and validation groups, respectively, which had an advantage over glycated hemoglobin A1c (AUC ≤ 0.691). Moreover, a significant increase in sialylated Hp-β was found in severe NPDR patients compared with BDR patients and yielded an AUC of 0.828 to distinguish severe NPDR from BDR.

CONCLUSION

Changes in Hp-β glycosylation are closely related to DR, and may be used for early diagnosis and screening of DR.

Unlocking the link between haptoglobin polymorphism and noninfectious human diseases: insights and implications

Haptoglobin (Hp) is a polymorphic protein that was initially described as a hemoglobin (Hb)-binding protein. The major functions of Hp are to scavenge Hb, prevent iron loss, and prevent heme-based oxidation. Hp regulates angiogenesis, nitric oxide homeostasis, immune responses, and prostaglandin synthesis. Genetic polymorphisms in the Hp gene give rise to different phenotypes, including Hp 1-1, Hp 2-1, and Hp 2-2. Extensive research has been conducted to investigate the association between Hp polymorphisms and several medical conditions including cardiovascular disease, inflammatory bowel disease, cancer, transplantation, and hemoglobinopathies. Generally, the Hp 2-2 phenotype is associated with increased disease risk and poor outcomes. Over the years, the Hp 2 allele has spread under genetic pressures. Individuals with the Hp 2-2 phenotype generally exhibit lower levels of CD163 expression in macrophages. The decreased expression of CD163 may be associated with the poor antioxidant capacity in the serum of subjects carrying the Hp 2-2 phenotype. However, the Hp 1-1 phenotype may confer protection in some cases. The Hp1 allele has strong antioxidant, anti-inflammatory, and immunomodulatory properties. It is important to note that the benefits of the Hp1 allele may vary depending on genetic and environmental factors as well as the specific disease or condition under consideration. Therefore, the Hp1 allele may not necessarily confer advantages in all situations, and its effects may be context-dependent. This review highlights the current understanding of the role of Hp polymorphisms in cardiovascular disease, inflammatory bowel disease, cancer, transplantation, hemoglobinopathies, and polyuria.

Intensified glycemic control by HbA1c for patients with coronary heart disease and Type 2 diabetes: a review of findings and conclusions

The occurrence and development of coronary heart disease (CHD) are closely linked to fluctuations in blood glucose levels. While the efficacy of intensified treatment guided by HbA1c levels remains uncertain for individuals with diabetes and CHD, this review summarizes the findings and conclusions regarding HbA1c in the context of CHD. Our review showed a curvilinear correlation between regulated level of HbA1c and therapeutic effectiveness of intensified glycemic control among patients with type 2 diabetes and coronary heart disease. It is necessary to optimize the dynamic monitoring indicators of HbA1c, combine genetic profiles, haptoglobin phenotypes for example and select more suitable hypoglycemic drugs to establish more appropriate glucose-controlling guideline for patients with CHD at different stage of diabetes.

Label-Free Liquid Chromatography-Mass Spectrometry Proteomic Analysis of Urinary Identification in Diabetic Vascular Dementia in a Han Chinese Population

Objective: This study aimed to identify potential diagnostic biomarkers of diabetic vascular dementia (DVD) and unravel the underlying mechanisms using mass spectrometry (MS).

Methods: Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomic analysis was applied to urine samples from four groups, including 14 patients with vascular dementia (VD), 22 patients with type 2 diabetes mellitus (T2DM), 12 patients with DVD, and 21 normal controls (NCs). Searching the MS data by Proteome Discoverer software (ThermoFisher Scientific; Waltham, MA, USA), protein abundances were analyzed qualitatively and quantitatively and compared between these groups. Combining bioinformatics analysis using Gene Ontology (GO), pathway crosstalk analysis using Kyoto Encyclopedia of Genes and Genomes (KEGG), protein–protein interaction (PPI) network analysis using STRING, and literature searching, the differentially expressed proteins (DEPs) of DVD can be comprehensively judged and were further quantified by receiver operating characteristic (ROC) curve methods.

Results: The proteomic findings showed quantitative changes in patients with DVD compared to patients with NC, T2DM, and VD groups; among 4,744 identified urine proteins, 1,222, 1,152, and 1,180 proteins displayed quantitative changes unique to DVD vs. NC, T2DM, and VD, respectively, including 481 overlapped common DEPs. Then, nine unique proteins [including HP, SERPIND, ATP5PB, VNN2, ALDH3A1, U2AF2, C6, A0A5C2GRG5 (no name), and A0A5C2FZ29 (no name)] and two composite markers (CM) (A0A5C2GRG5+U2AF2 and U2AF2+C6) were confirmed by a ROC curve method.

Conclusion: This study provided an insight into the potential pathogenesis of DVD and elucidated a method for early detection.

Hemoglobin-Conjugated Gold Nanoclusters for Qualitative Analysis of Haptoglobin Phenotypes

Designing a facile and rapid detection method for haptoglobin (Hp) phenotypes in human blood plasma is urgently needed to meet clinic requirements in hemolysis theranostics. In this work, a novel approach to qualitatively analyze Hp phenotypes was developed using a fluorescent probe of gold nanoclusters (AuNCs). Hemoglobin-conjugated (Hb)-AuNCs were successfully synthesized with blue-green fluorescence and high biocompatibility via one-pot synthesis. The fluorescence of Hb-AuNCs comes from the ligand-metal charge transfer between surface ligands of Hb and the gold cores with high oxidation states. The biocompatibility assays including cell viability and fluorescence imaging, demonstrated high biocompatibility of Hb-AuNCs. For the qualitative analysis, three Hp phenotypes in plasma, Hp 1-1, Hp 2-1, and Hp 2-2, were successfully discriminated according to changes in the fluorescence intensity and peak position of the maximum intensity of Hb-AuNCs. Our work provides a practical method with facile and rapid properties for the qualitative analysis of three Hp phenotypes in human blood plasma.

A wealth of genotype-specific proteoforms fine-tunes hemoglobin scavenging by haptoglobin

The serum haptoglobin protein (Hp) scavenges toxic hemoglobin (Hb) leaked into the bloodstream from erythrocytes. In humans, there are two frequently occurring allelic forms of Hp, resulting in three genotypes: Homozygous Hp 1-1 and Hp 2-2, and heterozygous Hp 2-1. The Hp genetic polymorphism has an intriguing effect on the quaternary structure of Hp. The simplest form, Hp 1-1, forms dimers consisting of two α1β units, connected by disulfide bridges. Hp 2-1 forms mixtures of linear (α1)2(α2)n-2(β)n oligomers (n > 1) while Hp 2-2 occurs in cyclic (α2)n(β)n oligomers (n > 2). Different Hp genotypes bind Hb with different affinities, with Hp 2-2 being the weakest binder. This behavior has a significant influence on Hp's antioxidant capacity, with potentially distinctive personalized clinical consequences. Although Hp has been studied extensively in the past, the finest molecular details of the observed differences in interactions between Hp and Hb are not yet fully understood. Here, we determined the full proteoform profiles and proteoform assemblies of all three most common genetic Hp variants. We combined several state-of-the-art analytical methods, including various forms of chromatography, mass photometry, and different tiers of mass spectrometry, to reveal how the tens to hundreds distinct proteoforms and their assemblies influence Hp's capacity for Hb binding. We extend the current knowledge by showing that Hb binding does not just depend on the donor's genotype, but is also affected by variations in Hp oligomerization, glycosylation, and proteolytic processing of the Hp α-chain.

Blood-Related Toxicity after Traumatic Brain Injury: Potential Targets for Neuroprotection

Emergency visits, hospitalizations, and deaths due to traumatic brain injury (TBI) have increased significantly over the past few decades. While the primary early brain trauma is highly deleterious to the brain, the secondary injury post-TBI is postulated to significantly impact mortality. The presence of blood, particularly hemoglobin, and its breakdown products and key binding proteins and receptors modulating their clearance may contribute significantly to toxicity. Heme, hemin, and iron, for example, cause membrane lipid peroxidation, generate reactive oxygen species, and sensitize cells to noxious stimuli resulting in edema, cell death, and increased morbidity and mortality. A wide range of other mechanisms such as the immune system play pivotal roles in mediating secondary injury. Effective scavenging of all of these pro-oxidant and pro-inflammatory metabolites as well as controlling maladaptive immune responses is essential for limiting toxicity and secondary injury. Hemoglobin metabolism is mediated by key molecules such as haptoglobin, heme oxygenase, hemopexin, and ferritin. Genetic variability and dysfunction affecting these pathways (e.g., haptoglobin and heme oxygenase expression) have been implicated in the difference in susceptibility of individual patients to toxicity and may be target pathways for potential therapeutic interventions in TBI. Ongoing collaborative efforts are required to decipher the complexities of blood-related toxicity in TBI with an overarching goal of providing effective treatment options to all patients with TBI.

The role of haptoglobin and hemopexin in the prevention of delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage: a review of current literature

Delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a major cause of mortality and morbidity. The pathophysiology of DCI after aSAH is thought to involve toxic mediators released from lysis of red blood cells within the subarachnoid space, including free haemoglobin and haem. Haptoglobin and hemopexin are endogenously produced acute phase proteins that are involved in the clearance of these toxic mediators. The aim of this review is to investigate the pathophysiological mechanisms involved in DCI and the role of both endogenous as well as exogenously administered haptoglobin and hemopexin in the prevention of DCI.

Association of rs2000999 in the haptoglobin gene with total cholesterol, HDL-C, and LDL-C levels in Mexican type 2 diabetes patients

Recently, studies have shown significant association between the rs2000999 polymorphism in the haptoglobin-encoding gene (HP) and low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels, which are important risk factors for cardiovascular diseases. However, the association of rs2000999 with serum lipids in Latin American diabetic populations is still uncharacterized. Here, we analyzed the association of rs2000999 with TC, high-density lipoprotein cholesterol (HDL-C), and LDL-C levels in 546 Mexican adults with type 2 diabetes (T2D) and in 654 controls without T2D. In this observational case-control study we included adults from 4 centers of the Mexican Social Security Institute in Mexico City recruited from 2012 to 2015. TC, HDL-C, LDL-C, triglycerides (TG), and glucose levels were measured by an enzymatic colorimetric method. The variant rs2000999 was genotyped using TaqMan real time polymerase chain reaction. The percentage of Native-American ancestry showed a negative association with the rs2000999 A allele. In contrast, the rs2000999 A allele had a strong positive association with European ancestry, and to a lesser extent, with African ancestry. Linear regression was used to estimate the association between the variant rs2000999 and lipid concentrations, using different genetic models. Under codominant and recessive models, rs2000999 was significantly associated with TC and LDL-C levels in the T2D group and in controls without T2D. In addition, the group with T2D showed a significant association between the variant and HDL-C levels. In summary, the rs2000999 A allele in Mexican population is positively associated with the percentage of European and negatively associated with Native American ancestry. Carriers of the A allele have increased levels of TC and LDL-C, independently of T2D diagnosis, and also increased concentrations of HDL-C in the T2D sample.

Genetic determinants of circulating haptoglobin concentration

Haptoglobin (Hp) is a major plasma acute-phase glycoprotein, which binds free haemoglobin to neutralize its toxicity. The HP gene exists as two copy number variants (CNV), Hp1 and HP2, which differ in two ways: serum Hp level and functional differences in Hp protein products. Both mechanisms may underlie the HP CNV's influence on susceptibility and/or outcome in several diseases. A single nucleotide polymorphism rs2000999 has also been associated with serum Hp level. In a meta-analysis of three studies from England, France and Japan, with a combined sample size of 1210 participants, we show that rs2000999's effect on circulating Hp level is independent from that of the HP CNV. The combined use of rs2000999 and the HP CNV can be an important genetic epidemiological tool to discriminate between the two potential mechanisms underlying differences between HP1 and HP2 alleles.

Association of haptoglobin phenotype with incident acute myocardial infarction in Chinese patients with type 2 diabetes

Background

Haptoglobin (Hp) is an abundant plasma protein with anti-oxidant properties. Hp polymorphism is associated with cardio-metabolic dysfunction but the allele conferring risk of developing acute myocardial infarction (AMI) in type 2 diabetes (T2D) patients is unclear. This study aimed to investigate the association of Hp phenotype (Hp 1-1, 2-1 and 2-2) with incident AMI in Chinese T2D patients.

Methods

This prospective study included Chinese T2D participants from the Singapore Study of Macro-angiopathy and Micro-vascular Reactivity in Type 2 Diabetes (SMART2D) and Diabetic Nephropathy (DN) cohorts. Information on incidence of non-fatal AMI was collected by data linkage with the Singapore Myocardial Infarction Registry. Hp phenotype was determined using enzyme-linked immunosorbent assay. Cox proportional hazards regression models were used to evaluate the association of Hp phenotype with incident AMI, adjusted for traditional risk factors separately in two cohorts, then meta-analysed.

Results

In total, 2324 Chinese participants (SMART2D; N = 1034, mean age [SD] of 59 [11]) and (DN: N = 1290, mean age [SD] of 58 [12]) were included in this study. There were total of 30 (56 events per 10,000 patient-years) and 99 (128 events per 10,000 patient-years) AMI events in SMART2D and DN cohorts respectively. In meta-analysis, presence of Hp 1 allele conferred 43% (hazard ratio [HR] = 1.43 [95% CI 1.10–1.87], P = 0.008, P_het = 0.413) increased risk of incident AMI, independent of age, sex, smoking, body mass index, HbA1c, diabetes duration, lipids, hypertension, renal function and usage of insulin and RAS antagonist. In adjusted model, compared to Hp 2-2 groups, individuals with Hp 1-1 (HR = 2.18 [95% CI 1.19–3.76], P = 0.010, P_het = 0.193) and Hp 2-1 (HR = 1.45 [95% CI 0.98–2.14], P = 0.065, P_het = 0.576) were at a higher risk of incident AMI. Moreover, compared to Hp 2-2 groups, non-Hp 2-2 groups (Hp 1-1 and Hp 2-1) were at 55% increased risk of incident AMI (HR = 1.55 [95% CI 1.07–2.24], P = 0.021, P_het = 0.940).

Conclusions

Hp 1-1 phenotype was associated with increased risk of incident AMI, independent of traditional risk factors, in Chinese patients with T2D. Hp phenotyping may allow for identification of T2D individuals at higher risk for onset of AMI. However, further studies are needed to understand the underlying mechanism between Hp alleles and risk for AMI.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0867-4) contains supplementary material, which is available to authorized users.

The early detection of atherosclerosis in type 1 diabetes: why, how and what to do about it

The major cause of morbidity and often premature mortality in people with type I diabetes (T1D) is cardiovascular disease owing to accelerated atherosclerosis. We review publications relating to the rationale behind, and clinical tests for, detecting and treating early atherosclerosis in people with T1D. Currently available tools for atherosclerosis assessment include risk equations using vascular risk factors, arterial intima-media thickness, the ankle-brachial index, coronary artery calcification and angiography, and for more advanced lesions, intravascular ultrasound and optical coherence tomography. Evolving research tools include risk equations incorporating novel clinical, biochemical and molecular tests; vascular MRI and molecular imaging. As yet there is little information available to quantify early atherosclerosis. With better means to control the vascular risk factors, such as hypertension, dyslipidaemia and glycaemic control, and emerging therapies to control novel risk factors, further epidemiologic and clinical trials are merited to facilitate the translation into clinical practice of robust means to detect, monitor and treat early atherosclerosis in those with T1D.

Association of the genetic variant rs2000999 with haptoglobin and diabetic macrovascular diseases in Chinese patients with type 2 diabetes

AIMS

The common copy number variant (CNV) in the haptoglobin (Hp) gene may influence the susceptibility to diabetic macrovascular diseases. We aimed to investigate the relationship of the genetic variant rs2000999, located in the haptoglobin-related protein (HPR) gene, with serum Hp levels and diabetic macrovascular diseases in Chinese type 2 diabetes patients.

METHODS

The Hp CNV and rs2000999 were genotyped in a group of 5457 Chinese patients with type 2 diabetes. Associations of rs2000999 with the common Hp CNV, susceptibility to diabetic macrovascular diseases and related metabolic traits were analysed. Furthermore, 886 patients were selected to detect serum Hp levels and to evaluate the correlation between rs2000999 and serum Hp levels.

RESULTS

The genetic variant rs2000999 was not associated with diabetic macrovascular diseases (P = 0.6109), while subjects carrying the A allele had higher levels of low-density lipoprotein cholesterol (P = 0.0578) and a smaller inter-adventitial diameter of the common carotid artery (P = 0.0266). Additionally, rs2000999 exhibited strong association with serum Hp levels (P = 2.03 × 10^-21).

CONCLUSIONS

The genetic variant rs2000999 was not associated with diabetic macrovascular diseases but showed an association with metabolic traits and serum Hp levels in Chinese patients with type 2 diabetes.

Haptoglobin Hp2 Variant Promotes Premature Cardiovascular Death in Stroke Survivors

BACKGROUND AND PURPOSE

Haptoglobin (Hp) is an acute phase plasma protein protecting tissues from oxidative damage. It exists in 2 variant alleles (hp1/hp2) giving rise to 3 protein isoforms with different biochemical properties and efficiency to limit oxidative stress. We previously found that hp2 variant is associated with stroke risk in the patients with carotid stenosis and the risk of ischemic cardiovascular events in a general population cohort. This study examined the hypothesis that Hp genotype is associated with general cardiovascular risk in patients with stroke.

METHODS

Hp was genotyped in SAM study (Helsinki Stroke Aging Memory, n=378). A total of 1426 individuals ascertained from a nationally representative cross-sectional health survey served as population controls.

RESULTS

Hp genotype frequencies were 15.6% (hp1-1), 44.2% (hp1-2), and 40.2% (hp2-2) in patients with stroke. During a mean of 7.5-year follow-up after first-ever stroke, hp2 carriers had a substantially higher rate of cardiac deaths (24.5% versus 8.5%; P=0.006) and a trend toward more fatal strokes (23.5% versus 13.6%; P=0.122). The combined risk of ischemic cardiovascular deaths was 2.4-fold higher among hp2 carriers (95% confidence interval, 1.28-4.43) after adjustment for major cardiovascular risk factors.

CONCLUSIONS

Hp2 allele is associated with premature ischemic cardiovascular deaths after first-ever ischemic stroke.

Cardiovascular complications of type 1 diabetes: update on the renal link

AIMS

Despite recent findings of increased life expectancy among individuals with type 1 diabetes, mortality remains greatly increased compared to the general population. As this is largely the result of cardiovascular and renal complications, we aimed to review recent findings surrounding these diseases in type 1 diabetes.

METHODS

We reviewed published findings concerning the cardiovascular complications of type 1 diabetes, with a particular focus on links with renal disease.

RESULTS

The cardiovascular and renal complications of type 1 diabetes share many features including insulin resistance, oxidative damage, and genetic associations with the Haptoglobin genotype, and both are strongly affected by glycemic control.

CONCLUSIONS

Although current knowledge on predictors of type 1 diabetes cardiovascular and renal complications has increased, further investigation is required to understand the mechanisms leading to cardio-renal complications in this population.

Correlation of geographic distributions of haptoglobin alleles with prevalence of multiple sclerosis (MS) - a narrative literature review

We have proposed that the myelin damage observed in multiple sclerosis (MS) may be partly mediated through the long-term release and degradation of extracellular hemoglobin (Hb) and the products of its oxidative degradation [Cellular and Molecular Life Sciences, 71, 1789-1798, 2014]. The protein haptoglobin (Hpt) binds extracellular Hb as a first line of defense, and can serve as a vascular antioxidant. Humans have two different Hpt alleles: Hpt1 and Hpt2, giving either homozygous Hpt1-1 or Hpt2-2 phenotypes, or a heterozygous Hpt1-2 phenotype. We questioned whether those geographic regions with higher frequency of the Hpt2 allele (conversely, lower frequency of Hpt1 allele) would correlate with an increased incidence of MS, because different Hpt phenotypes will have variable anti-oxidative potentials in protecting myelin from damage inflicted by extracellular Hb and its degradation products. To test this hypothesis, we undertook a systematic analysis of the literature on reported geographic distributions of Hpt alleles to compare them with data reported in the World Health Organization Atlas of worldwide MS prevalence. We found the frequency of the Hpt1 allele to be low in European and North American countries with a high prevalence of MS, consistent with our hypothesis. However, this correlation was not observed in China and India, countries with the lowest Hpt1 frequencies, yet low reported prevalence of MS. Nevertheless, this work shows the need for continued refinement of geographic patterns of MS prevalence, including data on ethnic or racial origin, and for new clinical studies to probe the observed correlation and evaluate Hpt phenotype as a predictor of disease variability and progression, severity, and/or comorbidity with cardiovascular disorders.

Higher post-acute myocardial infarction plasma haptoglobin level is associated with poor long-term overall survival

AIM

To evaluate the association of post-acute myocardial infarction (AMI) plasma haptoglobin (Hp) levels with long-term overall survival in AMI patients.

METHODS AND RESULTS

Patients who were diagnosed of AMI were recruited and their Hp phenotypes and plasma levels were determined. According to previously reported cutoff point for Hp level (288.4ng/ml), patients were classified as higher Hp group (>288.4ng/ml) and lower Hp group (≤288.4ng/ml). The primary outcome was overall survival. This study recruited and followed a total of 117 patients for a median of 11.0 (3.2-17.6) years. Higher Hp group had 46 patients (39.3%) and lower Hp group had 71 patients (60.7%). Twelve patients had Hp 1-1 (10.3%), 50 with Hp 2-1 (42.7%), and 55 with Hp 2-2 (47.0%). The lower Hp group had significantly better overall survival (174.1 [51.6-212.5] vs. 106.5 [22.2-209.1], P=0.037). There was no significant difference in overall survival between the three phenotype groups (P=0.477). Multivariate regression analysis revealed that increased age (adjusted HR=1.06, 95% CI: 1.03-1.10, P<0.001) and higher Hp level (adjusted HR=1.65, 95%=1.02-2.67, P=0.040) were significantly associated with poor overall survival.

CONCLUSION

Higher post-AMI plasma Hp level was independently associated with poor overall survival in AMI patients. No significant difference in overall survival was noted between three Hp phenotype groups. Acute phase Hp level might reflect the severity of oxidative stress during inflammation process.

Role of Haptoglobin in Health and Disease: A Focus on Diabetes

In Brief Prospective identification of individuals with diabetes who are at greatest risk for developing complications would have considerable public health importance by allowing appropriate resources to be focused on those who would benefit most from aggressive intervention. Haptoglobin (Hp) is an acute-phase protein that is crucial for the elimination of free hemoglobin and the neutralization of oxidative damage. In the past two decades, associations have been made between polymorphisms in Hp and complications arising from diabetes. Individuals with polymorphism in Hp have been shown to have significantly higher risk of developing cardiovascular disease. This review summarizes the current literature on the role of Hp in health and disease, with a focus on diabetes.

Effect of vitamin E supplementation on HDL function by haptoglobin genotype in type 1 diabetes: results from the HapE randomized crossover pilot trial

AIMS

Haptoglobin (Hp) genotype 2-2 increases cardiovascular diabetes complications. In type 2 diabetes, α-tocopherol was shown to lower cardiovascular risk in Hp 2-2, potentially through HDL function improvements. Similar type 1 diabetes data are lacking. We conducted a randomized crossover pilot of α-tocopherol supplementation on HDL function [i.e., cholesterol efflux (CE) and HDL-associated lipid peroxides (LP)] and lipoprotein subfractions in type 1 diabetes.

METHODS

Hp genotype was assessed in members of two Allegheny County, PA, type 1 diabetes registries and the CACTI cohort; 30 were randomly selected within Hp genotype, and 28 Hp 1-1, 31 Hp 2-1 and 30 Hp 2-2 were allocated to daily α-tocopherol or placebo for 8 weeks with a 4-week washout.

RESULTS

Baseline CE decreased with the number of Hp 2 alleles (p-trend = 0.003). There were no differences in LP or lipoprotein subfractions. In intention-to-treat analysis stratified by Hp, α-tocopherol increased CE in Hp 2-2 (β = 0.79, p = 0.03) and LP in Hp 1 allele carriers (β Hp 1-1 = 0.18, p = 0.05; β Hp 2-1 = 0.21, p = 0.07); reduced HDL particle size (β = -0.07, p = 0.03) in Hp 1-1 carriers; increased LDL particle concentration in Hp 1-1; and decreased it in Hp 2-2 carriers. However, no significant interactions were observed by Hp.

CONCLUSIONS

In this type 1 diabetes study, HDL function worsened with the number of Hp 2 alleles. α-Tocopherol improved HDL function in Hp 2-2 carriers and appeared to adversely affect lipid peroxides and lipoprotein subfractions among Hp 1 allele carriers. As no significant interactions were observed, findings require replication in larger studies.

Combined association analysis of interleukin 1-receptor antagonist (IL-1RN) variable number of tandem repeat (VNTR) and Haptoglobin 1/2 polymorphisms with type 2 diabetes mellitus risk

Background

The polymorphism of Interleukin 1 receptor antagonist gene (IL-1RN), which encodes a natural antagonist of pro-inflammatory cytokines belonging to IL-1 family and Haptoglobin (HP) have been studied in various ethnic groups in association with Type 2 Diabetes Mellitus (T2DM) risk and related complications. However, there was no study available among the Emirati population. Hence, we designed a combined study on IL-1RN and HP polymorphism to evaluate their association with prevalence of T2DM, related complication and hypertension and also its interaction with obesity status among Emirati population.

Methods

IL-1RN and HP genotypes were determined in total 487 Emiratis divided in two groups of T2DM case (n = 271) and healthy controls (n = 215) by polymerase chain reaction (PCR) followed by gel electrophoresis. Gene-gene interaction and polymorphism-obesity interaction were determined by multivariate logistic regression analysis.

Results

We found that the frequencies of IL-1RN*1/*1 and HP2-2 genotypes were significantly higher in cases than control and were associated with increased T2DM risk with an odds ratio (OR) of 1.60 (95 % CI 1.10–2.36) and 1.63 (95 % CI 1.11–2.64), respectively. The association lack any interaction with obesity status. Associations with occurrences of T2DM related complications and hypertension were not observed.

Conclusions

We report an association of IL-1RN and HP polymorphism with T2DM risk independent of each other and of obesity status but no association with related complications and hypertension.

Electronic supplementary material

The online version of this article (doi:10.1186/s40200-016-0232-z) contains supplementary material, which is available to authorized users.

Haptoglobin genotype is associated with increased endothelial dysfunction serum markers in type 1 diabetes

BACKGROUND

To evaluate the genotype-driven effect of haptoglobin (Hp) in patients with type 1 diabetes without clinical cardiovascular (CV) disease, considering endothelial dysfunction (ED) and arterial stiffness (AS).

MATERIAL AND METHODS

About 137 patients with type 1 diabetes (duration ≥ 5 years) and 68 age- and sex-matched controls were evaluated for the following: (i) smoking, alcohol intake, BMI, blood pressure, fasting plasma glucose, HbA1c and lipid profile; (ii) microvascular complications; (iii) serum markers of ED (ICAM-1, VCAM-1 and E-selectin); (iv) AS, assessed as aortic pulse wave velocity (aPWV); and (v) Hp genotype.

RESULTS

The prevalence of the 1/1, 2/1 and 2/2 Hp genotypes was 28.5%, 46.7% and 24.8% in patients with type 1 diabetes and 20.9%, 38.8% and 40.3% in controls, respectively. No differences were found in classical CV risk factors between patients homozygous for allele 2 and the remaining genotypes, both in patients with type 1 diabetes and controls. Patients with type 1 diabetes carrying the Hp2/2 genotype had higher concentrations of ICAM-1 (65.1 (56.7-76.0) ng/mL vs. 59.0 (51.7-69.3) ng/mL; P = 0.033) and sVCAM-1 (1133.1 (884.6-1458.6) ng/mL vs. 956.4 (738.5-1206.1) ng/mL; P = 0.040) than those without it. The Hp2/2 genotype remained independently associated with ED after adjusting for CV risk factors (P = 0.038). No significant differences were found for aPWV between Hp genotypes.

CONCLUSIONS

Endothelial dysfunction may be influenced by Hp2/2 genotype in patients with type 1 diabetes with independence of classical CV risk factors.

Inflammatory triggers of acute rejection of organ allografts

Solid organ transplantation is a vital therapy for end stage diseases. Decades of research have established that components of the adaptive immune system are critical for transplant rejection, but the role of the innate immune system in organ transplantation is just emerging. Accumulating evidence indicates that the innate immune system is activated at the time of organ implantation by the release of endogenous inflammatory triggers. This review discusses the nature of these triggers in organ transplantation and also potential mediators that may enhance inflammation resolution after organ implantation.

The haptoglobin 1 allele correlates with white matter hyperintensities in middle-aged adults with type 1 diabetes

Although the haptoglobin (Hp) 1-1 genotype is associated with a lower coronary artery disease (CAD) risk in diabetes, we recently reported an increased stroke incidence in type 1 diabetes with Hp 1-1. We, thus, evaluated differences in earlier brain vascular abnormality markers by Hp using neuroimaging. Neuroimaging was completed in 94 participants of the Pittsburgh Epidemiology of Diabetes Complications study with Hp genotyping available (mean age, 49; duration, 41 years). White matter hyperintensities (WMH) volume, lacunar infarcts, and gray matter atrophy were quantified. Sixteen percent were homozygous for Hp 1 and 43% for Hp 2. A significant trend toward increased WMH was observed with greater duration and the number of Hp 1 alleles. Associations were strongest for the interhemispheric connecting fibers of the corpus callosum. Allowing for duration, sex, waist-to-hip ratio, HbA1c, systolic blood pressure, and lipids in models with backward elimination, results were similar. No significant differences by Hp were noted for atrophy or lacunar infarcts. Consistent with its direct association with stroke, the Hp 1-1 genotype is associated with higher WMH in this population. Further, including mechanistic, studies on the role of the Hp genotype in cerebrovascular disease and the implications for worsening cognitive function are needed.

Presence of haptoglobin-2 allele is associated with worse functional outcomes after spontaneous intracerebral hemorrhage

OBJECTIVE

To determine if the haptoglobin (Hp) phenotype, which has been shown to be a predictor of clinical outcomes in cerebrovascular disorders, particularly subarachnoid hemorrhage, was predictive of functional outcomes after spontaneous intracerebral hemorrhage (ICH).

METHODS

Patients admitted with a diagnosis of ICH were prospectively included and divided into 3 groups based on their genetically determined Hp phenotype: 1-1, 2-1, and 2-2. Outcome measures included mortality and 30-day modified Rankin Scale scores. Demographics and outcomes were compared for each phenotype using multivariate linear regression analysis.

RESULTS

The study included 94 patients. The distribution of Hp phenotype was Hp 1-1, 12 (13%); Hp 2-1, 46 (49%); and Hp 2-2, 36 (38%). The 3 Hp subgroups did not differ in terms of demographic variables, comorbidities, or ICH characteristics. There was a nonsignificant trend toward increased mortality in Hp 2-1 and Hp 2-2 compared with Hp 1-1, with mortality of 8% in Hp 1-1, 17% in Hp 2-1, and 25% in Hp 2-2 (P = 0.408). In the regression model adjusted for confounders, Hp 2-1 (odds ratio = 0.05, 95% confidence interval = 0.01-0.47, P < 0.001) and Hp 2-2 phenotypes (odds ratio = 0.14, 95% confidence interval = 0.02-0.86, P = 0.045) had significantly lower odds of modified Rankin Scale scores 0-2 compared with Hp 1-1.

CONCLUSIONS

After ICH, individuals with the Hp-2 allele (2-1 and 2-2) had worse functional outcomes than individuals with the Hp-1 allele (Hp 1-1). There was a nonsignificant association between Hp phenotype and mortality. Larger prospective studies with better surrogates of ICH outcomes are warranted.

Haptoglobin genotype and cerebrovascular disease incidence in type 1 diabetes

OBJECTIVE

We prospectively evaluated the haptoglobin (Hp)-stroke association in type 1 diabetes and hypothesized that despite increasing the risk of coronary artery disease, the presence of the Hp 2 allele would be associated with a lower incidence of stroke.

METHODS

Participants from the Epidemiology of Diabetes Complications study without prevalent stroke and Hp available were evaluated (n = 607; mean age 27.6 years and duration 19.3 years).

RESULTS

During 22 years of follow-up, stroke incidence did not differ by Hp genotype (p = 0.49). Restricting analyses to those diagnosed with diabetes ≥1965 (13% mortality vs 40% in the <1965 cohort) to diminish potential survival bias, the adjusted hazard ratio (HR) for Hp 1-1 was 3.08 (95% confidence interval (CI) = 0.81-11.77, p = 0.10). Further stratifying by hypertension prevalence, an increased stroke incidence was observed with Hp 1-1 only in those with hypertension (HR = 7.03, 95% CI = 1.42-34.89, p = 0.02).

CONCLUSION

Despite the protective effect against vascular diabetes complications, a borderline increased risk of stroke was observed with Hp 1-1 in type 1 diabetes. This mixed Hp effect on cardiovascular risk by outcome studied merits further investigation and cautions against the universal application of preventive therapies across all Hp genotypes.

Salivary proteins associated with hyperglycemia in diabetes: a proteomic analysis

Effective monitoring of glucose levels is necessary for patients to achieve greater control over their diabetes. However, only about a quarter of subjects with diabetes who requires close serum glucose monitoring, regularly check their serum glucose daily. One of the potential barriers to patient compliance is the blood sampling requirement. Saliva and its protein contents can be altered in subjects with diabetes, possibly due to changes in glycemic control. We propose here that salivary proteomes of subjects with diabetes may be different based on their glycemic control as reflected in A1C levels. A total of 153 subjects with type 1 or 2 diabetes were recruited. Subjects in each type of diabetes were divided into 5 groups based on their A1C levels; <7, 7-8, 8-9, 9-10, >10. To examine the global proteomic changes associated with A1C, the proteomic profiling of pooled saliva samples from each group was created using label-free quantitative proteomics. Similar proteomic analysis for individual subjects (N=4, for each group) were then applied to examine proteins that may be less abundant in pooled samples. Principle component analysis (PCA) and cluster analysis (p<0.01 and p<0.001) were used to define the proteomic differences. We, therefore, defined the salivary proteomic changes associated with A1C changes. This study demonstrates that differences exist between salivary proteomic profiles in subjects with diabetes based on the A1C levels.

Haptoglobin genotype-dependent differences in macrophage lysosomal oxidative injury

The major function of the Haptoglobin (Hp) protein is to control trafficking of extracorpuscular hemoglobin (Hb) thru the macrophage CD163 receptor with degradation of the Hb in the lysosome. There is a common copy number polymorphism in the Hp gene (Hp 2 allele) that has been associated with a severalfold increased incidence of atherothrombosis in multiple longitudinal studies. Increased plaque oxidation and apoptotic markers have been observed in Hp 2-2 atherosclerotic plaques, but the mechanism responsible for this finding has not been determined. We proposed that the increased oxidative injury in Hp 2-2 plaques is due to an impaired processing of Hp 2-2-Hb complexes within macrophage lysosomes, thereby resulting in redox active iron accumulation, lysosomal membrane oxidative injury, and macrophage apoptosis. We sought to test this hypothesis in vitro using purified Hp-Hb complex and cells genetically manipulated to express CD163. CD163-mediated endocytosis and lysosomal degradation of Hp-Hb were decreased for Hp 2-2-Hb complexes. Confocal microscopy using lysotropic pH indicator dyes demonstrated that uptake of Hp 2-2-Hb complexes disrupted the lysosomal pH gradient. Cellular fractionation studies of lysosomes isolated from macrophages incubated with Hp 2-2-Hb complexes demonstrated increased lysosomal membrane oxidation and a loss of lysosomal membrane integrity leading to lysosomal enzyme leakage into the cytoplasm. Additionally, markers of apoptosis, DNA fragmentation, and active caspase 3 were increased in macrophages that had endocytosed Hp 2-2-Hb complexes. These data provide novel mechanistic insights into how the Hp genotype regulates lysosomal oxidative stress within macrophages after receptor-mediated endocytosis of Hb.

Haptoglobin polymorphism in individuals with type 2 diabetic microangiopathy

BACKGROUND

Haptoglobin is an acute phase protein with antioxidant and immunomodulatory properties. Gene polymorphism may be a risk factor for diabetic vascular disease in Iranian population.

AIMS

The study investigates the existence or not of an association between haptoglobin genotypes and prevalence of diabetic microangiopathy in individuals with type 2 diabetic microangiopathy.

MATERIALS AND METHODS

We included 206 type 2 diabetic patients (<5 years duration) categorized into two groups according to the presence or absence of diabetic microvascular complications. The cases of interest were diabetic neuropathy, retinopathy, and nephropathy identified during clinical and or laboratory examination. In addition, 114 age- and sex-matched individuals were selected to serve as a control group. Haptoglobin genotyping was done using an amplification gel electrophoresis.

RESULTS

The frequency of haptoglobin phenotype 2-1 in diabetic patients was 70/206 (33.9%) as compared with 54/114 (47.3%) in nondiabetics (P = 0.01). However, the frequency of haptoglobin phenotype 2-2 was greater in diabetics (126/114, 61.1%) than in those without diabetes (56/114, 49.1%; P = 0.02). Patients with diabetic microangiopathy; however, did not differ significantly between haptoglobin phenotype groups.

CONCLUSIONS

Haptoglobin phenotype 2-2 is considered to be a major susceptibility gene for type 2 diabetic patients. Moreover, haptoglobin phenotype 2-1may be good prognostic factors for the development of diabetes mellitus.

Plasma haptoglobin concentrations are elevated in patients with coronary artery disease

Inflammation underlies the development and progression of coronary artery plaques. Haptoglobin (Hp) is an acute phase protein, the synthesis of which is increased during inflammation. The aim of this study was to investigate plasma Hp concentrations and phenotype in patients with coronary artery disease (CAD). We recruited 359 patients with fixed luminal stenosis ≥50% in at least one coronary artery (CAD group) and 83 patients with luminal stenosis ≤40%, normal ejection fraction, and normal regional wall motion (control group). Plasma Hp concentrations were measured using a phenotype-specific enzyme-linked immunosorbent assay. Hp phenotype was determined by native polyacrylamide gel electrophoresis. Plasma lipid concentrations were measured. Plasma Hp concentrations were significantly higher in the CAD compared with the control group (262.4±144.2 vs 176.0±86.7 ng/mL, P<0.001); however, there was no between group difference in the distribution of Hp phenotype (1-1 = 7.5% vs 7.2%; 2-1 = 40.4% vs 42.2%; 2-2 = 52.1% vs 50.6%). Stepwise multivariate logistic regression revealed that high Hp concentrations (odds ratio [OR] = 5.865), male sex (OR = 3.689), hypertension (OR = 2.632), diabetes mellitus (OR = 3.300), and low-density lipoprotein concentrations (OR = 1.480) were independently associated with CAD (all P<0.05). Hp phenotype was not associated with CAD. Plasma Hp concentrations were significantly correlated with the severity of luminal stenosis (r = 0.236, P<0.001). Our findings suggest that plasma Hp concentrations may be elevated in patients with CAD. There does not appear to be any relationship between Hp phenotype and CAD.

Haptoglobin 2 allele associates with unstable carotid plaque and major cardiovascular events

OBJECTIVE

Intraplaque hemorrhages (IPH) may predispose to unstable atherosclerotic disease and its atherothrombotic complications, ischemic stroke and coronary syndromes. However, the discriminative value of IPH has been limited in histological and imaging studies suggesting that confounding factors modulate the response to IPH. We studied whether common variants of haptoglobin (Hp), which facilitates the removal of free hemoglobin and protects tissues from heme-iron induced oxidative damage, would modify the inflammatory response to IPH and the risk of unstable carotid stenosis (CS) and major cardiovascular diseases.

METHODS

We genotyped Hp polymorphism in 91 patients with a high-grade CS from Helsinki Carotid Endarterectomy Study (HeCES) and in 1417 individuals from Health 2000, a Finnish epidemiological cross-sectional health survey, and determined heme oxygenase-1 (HO1) expression in relation to Hp genotypes in carotid plaques.

RESULTS

In the Health 2000 cohort, Hp genotype frequencies were 0.143 (hp1-1), 0.486 (hp1-2) and 0.371 (hp2-2) consistent with Hardy-Weinberg equilibrium and those reported from other Caucasian populations. Among patients with unstable CS, the frequency of hp2-2 genotype was higher than in the control population (0.516 vs. 0.371, P = 0.025). Hp genotypes correlated with HO1 expression in the plaque (r = 0.47, P = 0.027). In the Health 2000 cohort, hp2 allele was associated with an increased risk of major cardiovascular diseases (ischemic stroke, TIA, myocardial infarction, coronary heart disease) with an adjusted OR of 1.46 (95% CI 1.03-2.06).

CONCLUSION

Common haptoglobin variants modulate the inflammatory response to IPH and associate with the risk of unstable carotid stenosis and major ischemic cardiovascular events.

Vulnerable plaque: from bench to bedside; local pacification versus systemic therapy

Critical coronary stenoses accounts for a small proportion of acute coronary syndromes and sudden death. The majority are caused by coronary thromboses that arise from a nonangiographically obstructive atheroma. Recent developments in noninvasive imaging of so-called vulnerable plaques created opportunities to direct treatment to prevent morbidity and mortality associated with these high-risk lesions. This review covers therapy employed in the past, present, and potentially in the future as the natural history of plaque assessment unfolds.

Heme and haemoglobin direct macrophage Mhem phenotype and counter foam cell formation in areas of intraplaque haemorrhage

PURPOSE OF REVIEW

Several studies have recently shown that haemoglobin drives a novel macrophage subset that is protected from foam cell formation.

RECENT FINDINGS

In a previously overlooked area, two centres have independently shown that heme and haemoglobin drive an atheroprotective macrophage subset. We compare and contrast the approaches and findings of the laboratories and discuss some of the underlying biology and implications, concentrating on the aspects of lipidological relevance.

SUMMARY

Treatments based on direct heme-mimetics or other agonists of this pathway have enormous potential for linked antioxidant protection via heme oxygenase 1 and reduced foam cell formation via liver X receptor, a potent combination for treating atherosclerosis.

Plaque neovascularization: defense mechanisms, betrayal, or a war in progress

Angiogenesis is induced from sprouting of preexisting endothelial cells leading to neovascularization. Imbalance in the angiogenic and antiangiogenic mediators triggers angiogenesis, which may be physiological in the normal state or pathological in malignancy and atherosclerosis. Physiologic angiogenesis is instrumental for restoration of vessel wall normoxia and resolution inflammation, leading to atherosclerosis regression. However, pathological angiogenesis enhances disease progression, increasing macrophage infiltration and vessel wall thickness, perpetuating hypoxia and necrosis. In addition, thin-walled fragile neovessels may rupture, leading to intraplaque hemorrhage. Lipid-rich red blood cell membranes and free hemoglobin are detrimental to plaque composition, increasing inflammation, lipid core expansion, and oxidative stress. In addition, associated risk factors that include polymorphysms in the haptoglobin genotype and diabetes mellitus may modulate the features of plaque vulnerability. This review will focus on physiological and pathological angiogenesis in atherosclerosis and summarizes the current status of anti-vascular endothelial growth factor (VEGF) therapy, microvascular rarefaction, and possible statin-mediated effects in atherosclerosis neovascularization.

Haptoglobin genotype and its role in determining heme-iron mediated vascular disease

Haptoglobin (Hp) is a hemoglobin (Hb) binding protein whose major function is to prevent heme-iron mediated oxidation. The polymorphic nature of the Hp gene results in varying levels of antioxidant function associated with the protein products. Multiple clinical studies have now determined that the Hp 2-2 genotype is associated with an increased risk of developing vascular complications in patients suffering from diabetes. The mechanism for this phenomenon is a decrease in antioxidant capability associated with the Hp 2-2 protein. Specifically, heme iron associated with the Hp2-2/Hb complex is more redox active than other Hp type complexes and has been shown in a number of systems to lead to increased levels of oxidative stress in the form of oxidized lipids and decreased lipoprotein function. In addition, Hp 2-2/Hb complexes are cleared less efficiently from the circulation, leading to a buildup of iron in the plasma and in tissues. Recent analyses from clinical studies utilizing vitamin E treatment have shown beneficial results specifically in the diabetic Hp 2-2 genotype population. The use of vitamin E in the treatment of Hp 2-2 diabetics has the potential to greatly reduce medical costs and improve quality of life in the ever-growing diabetic population.

A genome-wide association study identifies rs2000999 as a strong genetic determinant of circulating haptoglobin levels

Haptoglobin is an acute phase inflammatory marker. Its main function is to bind hemoglobin released from erythrocytes to aid its elimination, and thereby haptoglobin prevents the generation of reactive oxygen species in the blood. Haptoglobin levels have been repeatedly associated with a variety of inflammation-linked infectious and non-infectious diseases, including malaria, tuberculosis, human immunodeficiency virus, hepatitis C, diabetes, carotid atherosclerosis, and acute myocardial infarction. However, a comprehensive genetic assessment of the inter-individual variability of circulating haptoglobin levels has not been conducted so far.

We used a genome-wide association study initially conducted in 631 French children followed by a replication in three additional European sample sets and we identified a common single nucleotide polymorphism (SNP), rs2000999 located in the Haptoglobin gene (HP) as a strong genetic predictor of circulating Haptoglobin levels (P_overall = 8.1×10⁻⁵⁹), explaining 45.4% of its genetic variability (11.8% of Hp global variance). The functional relevance of rs2000999 was further demonstrated by its specific association with HP mRNA levels (β = 0.23±0.08, P = 0.007). Finally, SNP rs2000999 was associated with decreased total and low-density lipoprotein cholesterol in 8,789 European children (P_{total cholesterol} = 0.002 and P_LDL = 0.0008).

Given the central position of haptoglobin in many inflammation-related metabolic pathways, the relevance of rs2000999 genotyping when evaluating haptoglobin concentration should be further investigated in order to improve its diagnostic/therapeutic and/or prevention impact.

Broad-spectrum four-dimensional orthogonal electrophoresis: a novel comprehensively feasible system for protein complexomics investigation

The major challenge of "protein complexomics" is to separate intact protein complexes or interactional proteins without dissociation or denaturation from complex biological samples and to characterize structural subunits of protein complexes. To address these issues, we developed a novel approach termed "broad-spectrum four-dimensional orthogonal electrophoresis (BS4-DE) system," which is composed of a nondenaturing part I and denaturing part II. Here we developed a mild acidic-native-PAGE to constitute part I, together with native-thin-layer-IEF and basic-native-PAGE, widening the range of BS4-DE system application for extremely basic proteins with the range of pI from about 8 to 11 (there are obviously 1000 kinds of proteins in this interval), and also speculated on the mechanism of separating. We first proposed ammonium hydroxide-ultrasonic protein extractive strategy as a seamless connection between part I and part II, and also speculated on the extractive mechanism. More than 4000 protein complexes could be theoretically solved by this system. Using this approach, we focus on blood rich in protein complexes which make it challenging to sera/plasma proteome study. Our results indicated that the BS4-DE system could be applied to blood protein complexomics investigation, providing a comprehensively feasible approach for disease proteomics.

Haptoglobin 2-2 genotype is associated with increased risk of type 2 diabetes mellitus in northern Chinese

The aim of this study was to investigate the association between haptoglobin (Hp) gene polymorphism and occurrence of type 2 diabetes mellitus (T2DM) in a northern Chinese population. We studied the association of the Hp gene polymorphism with T2DM in 584 unrelated T2DM patients and 690 control subjects with normal glucose tolerance among northern Chinese. The patients were diagnosed in accordance with the guidelines of the American Diabetes Association. The clinical characteristics of the study population were recorded, and the Hp genotype was determined. The frequencies of the genotypes in the group of T2DM patients and the controls were as follows: Hp2-2, 51.7% and 44.1%; Hp2-1, 39.7% and 45.1%; and Hp1-1, 8.6% and 10.9%, respectively. There was significant difference for the genotypic and allelic distribution between the two groups (p=0.021 and p=0.007, respectively). Even after readjusting for the confounding effects of age, gender, and body mass index, a significant effect of genotypes on T2DM was still found in the recessive model for the Hp2 allele tested (p=0.002). Those who had the Hp2-2 genotype had a significantly higher risk for T2DM than those with other genotypes (odds ratio=1.441, 95% confidence interval=1.143-1.817). The results showed that the Hp2-2 genotype is associated with increased risk of T2DM in the northern Chinese Han population.

Does haptoglobin genotype affect early onset of diabetic retinopathy in patients with type 2 diabetes?

PURPOSE

There are 2 common alleles for Hp (Hp-1 and Hp-2) and 3 common Hp genotypes: Hp1-1, Hp2-1, and Hp2-2. The haptoglobin genotype may play a dual role in morbidities of diabetes: Hp1-1, protective and Hp2-2, provocative. This study investigated the possible association of haptoglobin genotypes with onset of retinopathy in Type 2 diabetes (DM2).

METHODS

The sample included 98 consecutive adults with DM2 under routine outpatient follow-up from 2007 to 2009 who met the criteria for either no retinopathy at ≥10 years after diagnosis (Group 1) or proliferative retinopathy at ≤10 years after diagnosis (Group 2). Blood samples were collected for haptoglobin genotyping by polymerase chain reaction. Findings were compared between and within groups.

RESULTS

Eighty-four patients had no retinopathy and 14 had early proliferative retinopathy. The distributions of the Hp genotypes were as follows: no-retinopathy group: 28.6% Hp1-1, 35.7% Hp2-1, and 35.7% Hp2-2 and proliferative retinopathy group: 22.6% Hp1-1, 27.4% Hp2-1, and 50% Hp2-2 (NS). On statistical analysis (limited to the larger no-retinopathy group), a predominance of Hp1-1 was noted in older patients; Hp2-2 was associated with an increased rate of stroke.

CONCLUSION

The Hp genotype apparently plays no role in the development or worsening of proliferative retinopathy in DM2. Hp1-1 may be involved in delaying the onset of diabetes. Hp2-2 may pose a microvascular risk.

Haptoglobin genotype predicts development of coronary artery calcification in a prospective cohort of patients with type 1 diabetes

Background

Coronary artery disease has been linked with genotypes for haptoglobin (Hp) which modulates extracorpuscular hemoglobin. We hypothesized that the Hp genotype would predict progression of coronary artery calcification (CAC), a marker of subclinical atherosclerosis.

Methods

CAC was measured three times in six years among 436 subjects with type 1 diabetes and 526 control subjects participating in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. Hp typing was performed on plasma samples by polyacrylamide gel electrophoresis.

Results

The Hp 2-2 genotype predicted development of significant CAC only in subjects with diabetes who were free of CAC at baseline (OR: 1.95, 95% CI: 1.07-3.56, p = 0.03), compared to those without the Hp 2-2 genotype, controlling for age, sex, blood pressure and HDL-cholesterol. Hp 2 appeared to have an allele-dose effect on development of CAC. Hp genotype did not predict CAC progression in individuals without diabetes.

Conclusions

Hp genotype may aid prediction of accelerated coronary atherosclerosis in subjects with type 1 diabetes.

Haptoglobin polymorphism and association with complications in ghanaian type 2 diabetic patients

There is scanty information on the role of genetic factors, especially those relating to haptoglobin (Hp) phenotypes in the expression of complications among diabetes mellitus patients in Ghana. In this study, we investigated whether there is any association between Hp phenotypes and diabetic complications and to determine if association of the Hp phenotypes with diabetic complications in Ghanaian diabetics differ from those in Caucasians. A total of 398 participants were randomly recruited into the study. These comprised diabetic patients numbering 290 attending a diabetes Clinic in Ghana and 108 non-diabetic controls from the same community. Analyses of the results indicate that most of the diabetics with complications were of the Hp 2-2 (35%) and Hp 2-1 (23.9%) phenotypes. Fewer diabetics were found to be of the Hp 2-1 M phenotype. The controls were mostly of Hp 1-1 and Hp 2-1 M phenotypes. The odds ratio of having complications in a diabetic with an Hp 2-2 phenotype was 18.27 times greater than that for Hp 0-0. Hp 2-2 phenotype with its poor antioxidant activity may therefore be a useful predictor for the propensity of an individual to develop diabetes complications.

Albuminuria and Diabetic Retinopathy in Type 2 Diabetes Mellitus Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular Genetic Study (SN-DREAMS, report 12)

BACKGROUND

The concordance of microalbuminuria and diabetic retinopathy (DR) has been well reported in persons with type 1 diabetes; however, for type 2 diabetes, there is paucity of data especially from population-based studies. The aim of this study was to estimate the prevalence of albuminuria (micro - and macroalbuminuria) among persons with type 2 diabetes and determine its role as a risk factor for presence and severity of DR.

METHODS

A population-based cross sectional study was conducted in cohort of 1414 subjects with type 2 diabetes from Chennai metropolis. All the subjects underwent comprehensive eye examination including 45 degrees four-field stereoscopic digital photography. DR was clinically graded using Early Treatment Diabetic Retinopathy Study scales. A morning urine sample was tested for albuminuria. Subjects were considered to have microalbuminuria, if the urinary albumin excretion was between 30 and 300 mg/24 hours, and macroalbuminuria at more than 300 mg/24 hours. The statistical software used was SPSS for Windows, Chicago, IL. Student t-test for comparing continuous variables, and χ2 test, to compare proportions amongst groups were used.

RESULTS

The prevalence of microalbuminuria in the study subjects was 15.9% (226/1414), and that of macroalbuminuria, 2.7% (38/1414). Individuals with macroalbuminuria in comparison to micro- or normoalbuminuria showed a greater prevalence of DR (60.5% vs. 31.0% vs. 14.1%, p < 0.001), and also a greater severity of the disease (60.9% vs. 21.4 vs. 9.9, p < 0.001).

CONCLUSIONS

Every 6th individual in the population of type 2 diabetes is likely to have albuminuria. Subjects with microalbuminuria were around 2 times as likely to have DR as those without microalbuminuria, and this risk became almost 6 times in the presence of macroalbuminuria.

Haptoglobin polymorphism as a risk factor for chronic kidney disease: a case-control study

AIMS

Taiwan has the highest incidence and prevalence of end-stage renal disease worldwide. Haptoglobin (Hp) has a role in renal protection, and there are known differences in the function of different Hp alleles. We aim to study the association between Hp genotype and chronic kidney disease (CKD) in Taiwan.

METHODS

We performed one hospital-based, age-matched case-control study of 213 patients with CKD and 213 controls to evaluate the association between Hp polymorphism and CKD. Three major Hp genotypes were determined using polymerase chain reaction and electrophoresis. An unconditional logistic regression model was used to identify the associated risk factors for the development of CKD.

RESULTS

The frequency of Hp2-2 genotype and Hp(2) allele was significantly higher in the CKD group than in controls (p = 0.032 and 0.024, respectively). After adjustment for covariates, the Hp2-2 genotype (vs. Hp1-1; OR 3.841) remained significantly associated with the development of CKD, together with diabetes (OR 3.131), hypertension (OR 1.748) and dyslipidemia (OR 1.646).

CONCLUSION

This present study shows that Hp2-2 genotype is an independent risk factor for CKD. Determination of the Hp genotype may be of potential value to the prediction of genetic risk for CKD.

Haptoglobin polymorphism: a key factor in the proatherogenic role of B cells?

B cells play a role in atherosclerosis. B lymphocytes may reduce the progression of vascular disease. Antibody production against modified auto-antigens is an element in the atheroprotective involvement of B lymphocytes. Paradoxical evidence is emerging from animal studies that suggest a proatherogenic B-cell behaviour independently of autoantibody production. One aspect that has received limited consideration is the role of genetic susceptibility modulated by extracellular matrix proteins. Haptoglobin is a polymorphic glycoprotein that binds to CD22 on B lymphocytes. Hp phenotypes show an important molecular heterogeneity. Hp 2-2 has been linked to an increased susceptibility for atherosclerosis. Haptoglobin and its polymorphism play a role in B-cell migration and function. Hp phenotypes may influence B-T cell dialogue and T cell activation. Haptoglobin is involved in the interplay of lymphocytes, neutrophils, and monocytes. Haptoglobin binds to the CD11b/CD18 receptor and to mast cells. HDL particles can become pro-inflammatory through interactions of Hp-Hb complexes with apolipoprotein A1. Haptoglobin is a chemoattractant to pre-B lymphocytes and monocytes. Beyond the conventional view of haptoglobin as a marker of hemolysis, several findings point towards an immunomodulatory effect of haptoglobin in B-cell mediated progression of atherosclerosis. The balance between proatherogenic and protective immunological properties of the different Hp phenotypes determines if lesions progress or regress. Clinical studies indicate a strong association between the Hp 2-2 phenotype and a more frequent onset of diabetic complications and cardiovascular disease. Findings in animal models (where no haptoglobin polymorphism is present) cannot always be extrapolated to humans.