Haptoglobin phenotype is an independent risk factor for cardiovascular disease in individuals with diabetes: The Strong Heart Study

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.

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.

Haptoglobin genotype is a risk factor for coronary artery disease in prediabetes: A case-control study

Objective

Coronary artery disease (CAD) prediction remains inconsistent with many unappreciated risk factors. Haptoglobin genotype determines the haptoglobin protein's effectiveness to bind free hemoglobin and prevent oxidative stress, a contributor to atherosclerosis. The haptoglobin 2-2 genotype increases the prevalence of cardiovascular disease (CVD) approximately five times compared to the 1-1 genotype in individuals with diabetes. The risk is unknown in prediabetes. The purpose of this study was to determine an association between haptoglobin genotype and CAD in prediabetes.

Methods

The researchers used case-control convenience sampling from two cardiovascular disease prevention clinics in Memphis, TN, and Spokane, WA, from January 1, 2016 to March 31, 2020. Participants were ages 35-70, had prediabetes, and free of chronic inflammatory or infectious diseases. Cases had a history of subclinical or clinical CAD, while controls did not have a history of CAD. Differences between cases and controls and among haptoglobin genotypes were analyzed using t-tests and ANOVA for continuous variables and chi-square or Fisher's exact tests for categorical variables. Associations among Hp genotypes and CAD were estimated using logistic regression.

Results

The sample (N = 178; 72 cases and 106 controls) was 96 % white and 64 % male. Cases had lower total cholesterol (p = 0.0001) and high-sensitivity C-reactive protein (p = 0.021). Except for CAD, haptoglobin genotype was independent of any demographic or clinical variable. Haptoglobin 2-2 genotype had 4.0 times higher odds of CAD than haptoglobin 1-1 (p = 0.01).

Conclusion

Haptoglobin 2-2 genotype had approximately four times higher odds of having CAD compared to the haptoglobin 1-1 genotype. Cases had more desirable clinical profiles, likely attributable to more aggressive treatment of traditional risk factors than controls. Haptoglobin genotype is a potentially important CAD risk factor in prediabetes (88 million Americans). Further studies are needed for interventions to reduce the oxidative stress associated with the Hp 2-2 genotype and glycosylated hemoglobin and for CAD reduction.

Precision prognostics for cardiovascular disease in Type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Precision medicine has the potential to improve cardiovascular disease (CVD) risk prediction in individuals with Type 2 diabetes (T2D).

METHODS

We conducted a systematic review and meta-analysis of longitudinal studies to identify potentially novel prognostic factors that may improve CVD risk prediction in T2D. Out of 9380 studies identified, 416 studies met inclusion criteria. Outcomes were reported for 321 biomarker studies, 48 genetic marker studies, and 47 risk score/model studies.

RESULTS

Out of all evaluated biomarkers, only 13 showed improvement in prediction performance. Results of pooled meta-analyses, non-pooled analyses, and assessments of improvement in prediction performance and risk of bias, yielded the highest predictive utility for N-terminal pro b-type natriuretic peptide (NT-proBNP) (high-evidence), troponin-T (TnT) (moderate-evidence), triglyceride-glucose (TyG) index (moderate-evidence), Genetic Risk Score for Coronary Heart Disease (GRS-CHD) (moderate-evidence); moderate predictive utility for coronary computed tomography angiography (low-evidence), single-photon emission computed tomography (low-evidence), pulse wave velocity (moderate-evidence); and low predictive utility for C-reactive protein (moderate-evidence), coronary artery calcium score (low-evidence), galectin-3 (low-evidence), troponin-I (low-evidence), carotid plaque (low-evidence), and growth differentiation factor-15 (low-evidence). Risk scores showed modest discrimination, with lower performance in populations different from the original development cohort.

CONCLUSIONS

Despite high interest in this topic, very few studies conducted rigorous analyses to demonstrate incremental predictive utility beyond established CVD risk factors for T2D. The most promising markers identified were NT-proBNP, TnT, TyG and GRS-CHD, with the highest strength of evidence for NT-proBNP. Further research is needed to determine their clinical utility in risk stratification and management of CVD in T2D.

Interaction between haptoglobin genotype and glycemic variability on diabetic macroangiopathy: a population-based cross-sectional study

PURPOSE

Haptoglobin (Hp) is a hemoglobin-binding protein that functions as an antioxidant in human plasma. It is reported that glycemic variability (GV) plays a key role in diabetes-related complications associated with impaired glucose metabolism and oxidative stress. Here we aim to investigate whether the effect of GV on diabetic macroangiopathy depends on Hp genotype in type 2 diabetes.

METHODS

A number of 860 Chinese patients with type 2 diabetes was genotyped and assigned to two Hp subgroups (Hp 2-2 and Hp 1 carriers). Glycemic variability (GV) was assessed by using a retrospective continuous glucose monitoring system for three consecutive days, and it was measured using the glucose coefficient of variation (%CV), which is calculated as the ratio of glucose standard deviation to glucose mean. Clinical features, history of cardiac surgery, and vascular imaging tests were utilized to diagnose macroangiopathy. We evaluated the interaction between Hp genotypes and %CV on diabetic macroangiopathy. Furthermore, serum concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured using an enzyme-linked immunosorbent assay as a biomarker of oxidative stress.

RESULTS

Serum 8-OHdG levels were positively correlated with %CV in Hp 1 carriers (r = 0.117; p = 0.021). Patients in the highest %CV tertile were associated with a higher prevalence of diabetic macroangiopathy than those in the lowest %CV tertile in Hp 1 carriers (OR = 2.461 [95% CI, 1.183-5.121], p = 0.016), but not in those with Hp 2-2 genotype (OR = 0.540 [95% CI, 0.245-1.191], p = 0.127). A significant interactive effect of Hp genotypes and %CV on diabetic macroangiopathy was found (p interaction = 0.008).

CONCLUSION

Hp genotype modifies the effect of GV on diabetic macroangiopathy among Chinese patients with type 2 diabetes.

Clinical Pathway for Coronary Atherosclerosis in Patients Without Conventional Modifiable Risk Factors: JACC State-of-the-Art Review

Reducing the incidence and prevalence of standard modifiable cardiovascular risk factors (SMuRFs) is critical to tackling the global burden of coronary artery disease (CAD). However, a substantial number of individuals develop coronary atherosclerosis despite no SMuRFs. SMuRFless patients presenting with myocardial infarction have been observed to have an unexpected higher early mortality compared to their counterparts with at least 1 SMuRF. Evidence for optimal management of these patients is lacking. We assembled an international, multidisciplinary team to develop an evidence-based clinical pathway for SMuRFless CAD patients. A modified Delphi method was applied. The resulting pathway confirms underlying atherosclerosis and true SMuRFless status, ensures evidence-based secondary prevention, and considers additional tests and interventions for less typical contributors. This dedicated pathway for a previously overlooked CAD population, with an accompanying registry, aims to improve outcomes through enhanced adherence to evidence-based secondary prevention and additional diagnosis of modifiable risk factors observed.

Role of haptoglobin 2-2 genotype on disease progression and mortality among South Indian chronic kidney disease patients

BACKGROUND

Haptoglobin (HP), a plasma glycoprotein, binds to free hemoglobin and prevents the loss of iron and kidney damage. The variations of HP gene affect its enzyme activity, resulting in varied antioxidant, angiogenic and anti-inflammatory properties. HP 2-2 genotype showed 3.84 fold increased risk for the development of CKD in Taiwan population. With this background, the present work focused to conduct a prospective case-control study in South Indian population to evaluate whether the HP variants are associated to nondialysis (ND) (CKD stages 1-4) and ESRD (CKD stage 5) conditions.

METHODS AND RESULTS

Totally 392 CKD patients (nondialysis, ND; n = 170, end-stage renal disease, ESRD; n = 222) and 202 healthy individuals were enrolled. The blood samples collected from the patients were used to determine biochemical parameters and HP genotyping. Gene frequency and biochemical parameters were statistically analyzed for disease association. Results showed that HP 2-2 genotypes were significantly associated with ND and ESRD disease development compared to controls. Higher HP2-2 genotype frequency showed an increased hazard ratio for overall disease progression among ND patients (hazard ratio = 3.86; 95% CI 1.88 to 7.93; P = 0.0002). Survival analysis also showed that non-HP2-2 patients have a statistically significantly decreased risk for mortality compared to patients with the HP2-2 genotype (ESRD patients hazard ratio = 4.05; P = 0.04).

CONCLUSION

The present study confirms that HP2-2 polymorphism is statistically associated with the risk of CKD incidence, progression, and mortality among South Indians. Concluding our results, the HP2-2 genotype could be an independent predictor of all-cause mortality and disease progression in patients with CKD.

Precision Prognostics for Cardiovascular Disease in Type 2 Diabetes: A Systematic Review and Meta-analysis

Background Precision medicine has the potential to improve cardiovascular disease (CVD) risk prediction in individuals with type 2 diabetes (T2D). Methods We conducted a systematic review and meta-analysis of longitudinal studies to identify potentially novel prognostic factors that may improve CVD risk prediction in T2D. Out of 9380 studies identified, 416 studies met inclusion criteria. Outcomes were reported for 321 biomarker studies, 48 genetic marker studies, and 47 risk score/model studies. Results Out of all evaluated biomarkers, only 13 showed improvement in prediction performance. Results of pooled meta-analyses, non-pooled analyses, and assessments of improvement in prediction performance and risk of bias, yielded the highest predictive utility for N-terminal pro b-type natriuretic peptide (NT-proBNP) (high-evidence), troponin-T (TnT) (moderate-evidence), triglyceride-glucose (TyG) index (moderate-evidence), Genetic Risk Score for Coronary Heart Disease (GRS-CHD) (moderate-evidence); moderate predictive utility for coronary computed tomography angiography (low-evidence), single-photon emission computed tomography (low-evidence), pulse wave velocity (moderate-evidence); and low predictive utility for C-reactive protein (moderate-evidence), coronary artery calcium score (low-evidence), galectin-3 (low-evidence), troponin-I (low-evidence), carotid plaque (low-evidence), and growth differentiation factor-15 (low-evidence). Risk scores showed modest discrimination, with lower performance in populations different from the original development cohort. Conclusions Despite high interest in this topic, very few studies conducted rigorous analyses to demonstrate incremental predictive utility beyond established CVD risk factors for T2D. The most promising markers identified were NT-proBNP, TnT, TyG and GRS-CHD, with the highest strength of evidence for NT-proBNP. Further research is needed to determine their clinical utility in risk stratification and management of CVD in T2D.

Clinical utility of inflammatory and genetic biomarkers for cardiovascular disease prevention, categorization, and treatment

ABSTRACT

The complex interplay of increased atherogenic lipoproteins, inflammation, and immune activation hallmarks the pathogenesis of atherosclerotic cardiovascular disease (ASCVD). Atherosclerotic cardiovascular disease remains a leading cause of death, yet risk estimator tools lack comprehensiveness for genetic/inflammatory biomarkers associated with ASCVD. Unexplained ASCVD risk necessitates a better understanding of primary, secondary, and tertiary prevention variables. This article discusses the clinical utility of genetic and inflammatory biomarkers for ASCVD risk prediction, management, treatment, and recategorization into primary, secondary, and tertiary prevention. Furthermore, nurse practitioners (NPs) should use a ternary prevention classification system instead of the current binary system to mitigate risk in the large group of patients with subclinical ASCVD. High-sensitivity C-reactive protein (hs-CRP)-linearly associated with ASCVD-and lipoprotein-associated phospholipase-A 2 (Lp-PLA 2 ) and myeloperoxidase (MPO), both associated with plaque vulnerability/rupture, are inflammatory biomarkers. Elevated hs-CRP, MPO, and Lp-PLA 2 treatment requires addressing root causes of elevation (e.g., obesity, insulin resistance, tobacco use, gingival disease, and chronic autoimmune/infectious conditions). In addition, haptoglobin (Hp) phenotype determines the antioxidant potential of Hp. Haptoglobin phenotype, a root cause of ASCVD, is a one-time test. Individuals with Hp 2-2 should adopt a gluten-free diet to reduce endothelial and intestinal inflammation. Nurse practitioners should use stricter glycemic goals (hemoglobin A1c ≤6.5%) and add daily vitamin E if this group has type 2 diabetes. Genetic/inflammatory biomarkers should be used to better predict ASCVD risk and tailor primary, secondary, and tertiary prevention treatment. Clinical use of these biomarkers reaches beyond the standard of care to reduce residual ASCVD risk.

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.

Haptoglobin genotype and its relation to asymptomatic cerebral small-vessel disease in type 1 diabetes

AIM

Cerebral small-vessel disease (SVD) is prevalent in type 1 diabetes and has been associated with the haptoglobin variant allele Hp1. Contrarily, the Hp2-allele has been linked to cardiovascular disease and the role of haptoglobin-genotype in asymptomatic SVD is unknown. We, therefore, aimed to evaluate the alleles' association with SVD.

METHODS

This cross-sectional study included 179 neurologically asymptomatic adults with type 1 diabetes (women 53%, mean age 39 ± 7 years, diabetes duration 23 ± 10 years, HbA_1c 8.1 ± 3.2% [65 ± 12 mmol/mol]). Examinations included genotyping (genotypes Hp1-1, Hp2-1, Hp2-2) by polymerase chain reaction, clinical investigation, and magnetic resonance brain images assessed for SVD manifestations (white matter hyperintensities, cerebral microbleeds, and lacunar infarcts).

RESULTS

SVD prevalence was 34.6%. Haptoglobin genotype frequencies were 15.6% (Hp1-1), 43.6% (Hp1-2), and 40.8% (Hp2-2). Only diastolic blood pressure differed between the genotypes Hp1-1, Hp1-2, and Hp2-2 (81 [74-83], 75 [70-80], and 75 [72-81] mmHg, p = 0.019). Haptoglobin genotype frequencies by presence versus absence of SVD were 16.1%; 46.8%; 37.1% versus 15.4%; 41.9%; 42.7% (p = 0.758). Minor allele frequencies were 39.5% versus 36.3% (p = 0.553). Hp1 homozygotes and Hp2 carriers displayed equal proportions of SVD (35.7% vs 34.4%, p > 0.999) and SVD manifestations (white matter hyperintensities 14.3% vs 17.9%, p = 0.790; microbleeds 25.0% vs 21.9%, p = 0.904; lacunar infarcts 0% vs 3.6%, p > 0.999). Hp1-1 was not associated with SVD (OR 1.19, 95% CI 0.46-2.94, p = 0.712) when adjusting for age, blood pressure, and diabetic retinopathy.

CONCLUSIONS

Although the SVD prevalence was high, we detected no significant association between SVD and haptoglobin-genotype.

Oxidative Stress Underpins Clinical, Social, and Genetic Risk Factors for Atherosclerotic Cardiovascular Disease

Background

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide and is poorly predicted with current risk estimation tools. The biological mechanisms relating ASCVD risk factors to oxidative stress (OS) and how this accumulates ASCVD risk are misunderstood.

Purpose

To develop a comprehensive conceptual model explaining how expanded clinical, social, and genetic ASCVD risk factors accumulate ASCVD risk through OS.

Conclusions

OS (primarily from excess reactive oxygen species) and inflammation are present along the entire ASCVD pathophysiologic continuum. An expanded list of clinical and social ASCVD risk factors (including hypertension, obesity, diabetes, kidney disease, inflammatory diseases, substance use, poor nutrition, psychosocial stress, air pollution, race, and genetic ancestry) influence ASCVD largely through increased OS. Many risk factors exert a positive feedback mechanism to increase OS. One genetic risk factor, haptoglobin (Hp) genotype, is associated with higher ASCVD risk in diabetes and hypothesized to do the same in those with insulin resistance due to the Hp 2-2 genotype increasing OS.

Implications

Understanding the biological mechanisms of OS informs how these ASCVD risk factors relate to each other and compound ASCVD risk. Individualized ASCVD risk estimation should include a comprehensive, holistic perspective of risk factors to better address the clinical, social, and genetic influences of OS. Preventing and reducing OS is key to preventing ASCVD development or progression.

Haptoglobin Genotype Does Not Confer a Risk of Stroke in Type 1 Diabetes

The exon copy number variant in the haptoglobin gene is associated with cardiovascular and kidney disease. For stroke, previous research is inconclusive. We aimed to study the relationship between the haptoglobin Hp1/2 genotype and stroke in individuals with type 1 diabetes from the Finnish Diabetic Nephropathy Study. We included two partially overlapping cohorts: one with haptoglobin genotypes determined using genotyping for 179 individuals with stroke and 517 matched control subjects, and the other using haptoglobin genotype imputation for a larger cohort of 500 individuals with stroke and 3,806 individuals without stroke. We observed no difference in the Hp1-1, Hp2-1, and Hp2-2 genotype frequencies between individuals with or without stroke, neither in the genotyping nor the imputation cohorts. Haptoglobin genotypes were also not associated with the ischemic or hemorrhagic stroke subtypes. In our imputed haptoglobin cohort, 61% of individuals with stroke died during follow-up. However, the risk of death was not related to the haptoglobin genotype. Diabetic kidney disease and cardiovascular events were common in the cohort, but the haptoglobin genotypes were not associated with stroke when stratified by these complications. To conclude, the Hp1/2 genotypes did not affect the risk of stroke or survival after stroke in our cohort with type 1 diabetes.

Haptoglobin 1 allele predicts higher serum haptoglobin concentration and lower multiorgan failure risk in sickle cell disease

Haptoglobin (HP) is an acute-phase protein and the main scavenger of cell-free hemoglobin. When HP is depleted, as observed in hemolytic conditions such as sickle cell disease (SCD), cell-free hemoglobin can lead to acute organ damage. The impact of the HP 1-1, 2-1, and 2-2 isoforms on HP and cell-free hemoglobin concentrations and SCD-related complications is unclear. In a longitudinal cohort of patients with SCD, the HP 1 allele was associated with higher HP and lower cell-free hemoglobin concentrations at a routine clinic visit as well as during hospitalization for a vaso-occlusive episode or acute chest syndrome. With a median follow-up of 6.8 years, acute chest syndrome occurred in 42% (n = 163) and multiorgan failure in 14% (n = 53) of 391 patients with SCD with a minimum follow-up of 6 months. The HP 1 allele was independently associated with lower risk of developing multiorgan failure during acute chest syndrome (additive model hazard ratio, 0.5; P < .001). Future studies assessing the regulation of HP concentrations and ability to bind cell-free hemoglobin according to the HP genotype may help to identify patients with SCD at high risk for multiorgan failure and to guide interventions, such as rapid initiation of exchange transfusion or HP replacement therapy.

Plasma proteomics reveals an improved cardio-metabolic profile in patients with type 2 diabetes post-liraglutide treatment

BACKGROUND

Diabetes mellitus is a chronic multisystem disease with a high global prevalence, including in Saudi Arabia. The Glucagon-like Peptide (GLP-1) receptor agonist liraglutide is known to lower glucose levels, reduce weight and improve cardiovascular outcome. However, mechanisms underlying the benefits of liraglutide treatment in patients with type 2 diabetes mellitus (T2DM) remain unclear.

METHODS

In the present study, a 2D-DIGE MALDI-TOF mass spectrometric approach combined with bioinformatics and network pathway analysis explore the plasma proteomic profile. The study involved 20 patients with T2DM with mean age of 54.4 ± 9.5 years and Hemoglobin A1c (HbA1c) between 8% and 11% (inclusive).

RESULTS

A statistically significant change (p < .006) was observed in HbA1c with no significant changes in body weight, renal function, or markers of dyslipidemia post-treatment with liraglutide. 2 D-DIGE gel analysis identified significant changes (⩾1.5-fold change, Analysis of variance (ANOVA), p ⩽ 0.05) in 72 proteins, (62 down and 10 up) in liraglutide pre-treatment compared to the post-treatment state. Proteins identified in our study were found to regulate metabolic processes including acute phase response proteins, enzymes, apolipoproteins with involvement of the inflammatory signaling pathways, NF-κB, AKT, and p38 MAPK.

CONCLUSION

Liraglutide treatment decreased levels of acute phase response that to reduce the systemic chronic inflammatory state and oxidative stress, and eventually improve the cardio-metabolic profile in these patients.

Urinary Proteome Differences in Canine Diabetes with and without the Presence of Microalbuminuria

Simple Summary

Canine diabetes is a serious disease, which can lead to numerous complications. There are limited data on urine proteomics in dogs, and none of the effect of diabetes mellitus on the urine proteome. In this study we aimed to analyze the protein composition of the urine collected from the healthy animals and compare it with two diabetic groups (normoalbuminuric and microalbuminuric). There are significant differences between these three groups, and we believe that the identified proteins hold promise as a potential diagnostic tool, which can be later on used in clinical practice, and for better understanding of the disease.

Abstract

In this study we aimed to analyze the protein composition of the urine collected from the healthy animals and compare it to the two diabetic groups (DM I normoalbuminuric diabetic dogs; DM II diabetic dogs with microalbuminuria). We tried to identify potential urinary proteins which could be up- or downregulated in diabetic patients even before the appearance of microalbuminuria. Methods: After obtaining urine, we performed two-dimensional electrophoresis, followed by Delta2D software analysis, which allowed for selection and identification with MALDI-TOF spectrometry, statistically significant differentially expressed proteins. Our study revealed 286 common protein spots on 2D gels from the diabetic and control group. From these proteins five were positively identified by MALDI-TOF MS. To further evaluate the five differentiating proteins, the Panther program was used to assign them to appropriate biological process. Conclusion: Significant number of identified proteins play a role in intracellular signaling—vesicle formation, bonding, transport through membranes. This may suggest that first signs of kidney diabetic cellular impairment may be seen in the urine composition before any clinical signs occur.

Hyperglycemia Induces Inflammatory Response of Human Macrophages to CD163-Mediated Scavenging of Hemoglobin-Haptoglobin Complexes

Hyperglycemia, a hallmark of diabetes, can induce inflammatory programming of macrophages. The macrophage scavenger receptor CD163 internalizes and degrades hemoglobin-haptoglobin (Hb-Hp) complexes built due to intravascular hemolysis. Clinical studies have demonstrated a correlation between impaired scavenging of Hb-Hp complexes via CD163 and diabetic vascular complications. Our aim was to identify whether hyperglycemia is able to amplify inflammation via Hb-Hp complex interactions with the immune system. M(IFNγ), M(IL-4), and control M0 macrophages were differentiated out of primary human monocytes in normo- (5 mM) and hyperglycemic (25 mM) conditions. CD163 gene expression was decreased 5.53 times in M(IFNγ) with a further decrease of 1.99 times in hyperglycemia. Hyperglycemia suppressed CD163 surface expression in M(IFNγ) (1.43 times). Flow cytometry demonstrated no impairment of Hb-Hp uptake in hyperglycemia. However, hyperglycemia induced an inflammatory response of M(IFNγ) to Hb-Hp1-1 and Hb-Hp2-2 uptake with different dynamics. Hb-Hp1-1 uptake stimulated IL-6 release (3.03 times) after 6 h but suppressed secretion (5.78 times) after 24 h. Contrarily, Hb-Hp2-2 uptake did not affect IL-6 release after 6h but increased secretion after 24 h (3.06 times). Our data show that hyperglycemia induces an inflammatory response of innate immune cells to Hb-Hp1-1 and Hb-Hp2-2 uptake, converting the silent Hb-Hp complex clearance that prevents vascular damage into an inflammatory process, hereby increasing the susceptibility of diabetic patients to vascular complications.

Relation between haptoglobin polymorphism and oxidative stress status, lipid profile, and cardiovascular risk in sickle cell anemia patients

OBJECTIVE

The haptoglobin (Hp) gene located on chromosome 16q22 exhibits a polymorphism that can impact its capacity to inhibit the deleterious oxidative activity of free hemoglobin. We aimed to determine the influence of Hp polymorphism on oxidative stress, lipid profile, and cardiovascular risk in Cameroonian sickle cell anemia patients (SCA patients).

METHOD

The Hp genotypes of 102 SCA patients (SS), 60 healthy individuals (AA), and 55 subjects with sickle cell trait (AS) were determined by allele-specific PCR, and the blood parameters were assessed using standard methods.

RESULTS

Hp2-2 genotype was significantly (P < .05) present in SS (54%) than in AS (42%) and AA (38%). Levels of catalase and cell reactive protein were higher, while levels of total antioxidant capacity, triglycerides, low-density lipoprotein cholestetol, blood pressure, Framingham score, and body mass index were lower in the SCA patients. These parameters appeared to be unrelated to the haptoglobin genotypes. SCA patients with Hp1-1 genotype presented a higher oxidative stress index (0.53 ± 0.31) than those with Hp2-1 (0.33 ± 0.18). Lipid profile and cardiovascular risk were not significantly different between various Hp genotypes in SCA patients.

CONCLUSION

Haptoglobin polymorphism did not affect lipid profile, cardiovascular risk, and oxidative stress status of SCA patients. Nevertheless, SCA patients with Hp1-1 genotype tended to be more prone to oxidative stress than those with Hp2-1.

Interventional study with vitamin E in cardiovascular disease and meta-analysis

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality and atherosclerosis is the common root to most of the CVD. Oxidative stress is one of the most important factors driving atherosclerosis and its complications. Thus, strategies for the prevention and treatment of cardiovascular events had oxidative changes as a potential target. Natural vitamin E consists of a family of eight different compounds, four tocopherols and four tocotrienols. All tocopherols and tocotrienols are potent antioxidants with lipoperoxyl radical-scavenging activities. In addition, α-tocopherol possesses also anti-inflammatory as well as anti-atherothrombotic effects by modulating platelet and clotting system. Experimental and in vitro studies described molecular and cellular signalling pathways regulated by vitamin E antithrombotic and antioxidant properties. While observational studies demonstrated an inverse association between vitamin E serum levels and CVD, interventional trials with vitamin supplements provided negative results. This review focus on the impact of vitamin E in the atherothrombotic process and describes the results of experimental and clinical studies with the caveats related to the interventional trials with vitamin E to prevent CVD.

Haptoglobin as a Biomarker

Haptoglobin (Hp) is a glycoprotein that binds free hemoglobin (Hb) in plasma and plays a critical role in tissue protection and prevention of oxidative damage. Besides, it has some regulatory functions. Haptoglobin is an acute-phase protein, its concentration in plasma changes in pathology, and the test for its concentration is part of normal clinical practice. Haptoglobin is a conservative protein synthesized mainly in the liver and lungs and is the subject of research as a potential biomarker of many diseases, including various forms of malignant neoplasms. Haptoglobin has several unique biophysical characteristics. The human Нр gene is polymorphic, has three structural alleles that control the synthesis of three major phenotypes of haptoglobin: homozygous Нр1-1 and Нр2-2, and heterozygous Нр2-1, determined by a combination of allelic variants that are inherited. Numerous studies indicate that the phenotype of haptoglobin can be used to judge the individual predisposition of a person to various diseases. In addition, Hp undergoes various post-translational modifications (PTMs). These are structural transformations (removal of the signal peptide, cutting off the Pre-Hp precursor molecule into two subunits, α and β, limited proteolysis of α-chains, formation of disulfide bonds, multimerization), as well as chemical modifications of α-chains and glycosylation of the β-chain. Glycosylation of the β-chain of haptoglobin at four Asn sites is the most important variable PTM that regulates the structure and function of the glycoprotein. The study of modified oligosaccharides of the β-chain of Hp has become the main direction in the study of pathological processes, including malignant neoplasms. These characteristics indicate the possibility of the existence of Hp in the form of a multitude of proteoforms, probably performing different functions. This review is devoted to the description of the structural and functional diversity and the potential use of Hp as a biomarker of various pathologies.

Niacin Increases Atherogenic Proteins in High-Density Lipoprotein of Statin-Treated Subjects

[Figure: see text].

Dysfunctional High-Density Lipoproteins in Type 2 Diabetes Mellitus: Molecular Mechanisms and Therapeutic Implications

High density lipoproteins (HDLs) are commonly known for their anti-atherogenic properties that include functions such as the promotion of cholesterol efflux and reverse cholesterol transport, as well as antioxidant and anti-inflammatory activities. However, because of some chronic inflammatory diseases, such as type 2 diabetes mellitus (T2DM), significant changes occur in HDLs in terms of both structure and composition. These alterations lead to the loss of HDLs' physiological functions, to transformation into dysfunctional lipoproteins, and to increased risk of cardiovascular disease (CVD). In this review, we describe the main HDL structural/functional alterations observed in T2DM and the molecular mechanisms involved in these T2DM-derived modifications. Finally, the main available therapeutic interventions targeting HDL in diabetes are discussed.

[Haptoglobin as a biomarker]

Haptoglobin (Hp) is a blood plasma glycoprotein that binds free hemoglobin (Hb) and plays a critical role in tissue protection and the prevention of oxidative damage. In addition, it has a number of regulatory functions. Haptoglobin is an acute phase protein, its concentration in plasma changes in pathology, and the test for its concentration is part of normal clinical practice. Haptoglobin is a conservative protein synthesized mainly in the liver and lungs and is the subject of research as a potential biomarker of many diseases, including various forms of malignant neoplasms. Haptoglobin has several unique biophysical characteristics. Only in humans, the Hp gene is polymorphic, has three structural alleles that control the synthesis of three major phenotypes of Hp, homozygous Hp1-1 and Hp2-2, and heterozygous Hp2-1, determined by a combination of allelic variants that are inherited. Numerous studies indicate that the phenotype of haptoglobin can be used to judge the individual's predisposition to various diseases. In addition, Hp undergoes various post-translational modifications (PTMs). These are structural transformations (removal of the signal peptide, cutting of the Pre-Hp precursor molecule into two subunits, α and β, limited proteolysis of α-chains, formation of disulfide bonds, multimerization), as well as chemical modifications of α-chains and glycosylation of the β-chain. Glycosylation of the β-chain of haptoglobin at four Asn sites is the most important variable PTM that regulates the structure and function of the glycoprotein. The study of modified oligosaccharides of the Hp β-chain has become the main direction in the study of pathological processes, including malignant neoplasms. Many studies are focused on the identification of PTM and changes in the level of the α2-chain of this protein in pathology. These characteristics of Hp indicate the possibility of the existence of this protein as different proteoforms, probably with different functions. This review is devoted to the description of the structural and functional diversity of Hp and its potential use as a biomarker of various pathologies.

Prospection of plasma proteins as biomarkers for diabetes mellitus monitoring

Purpose

This prospective study aimed to detect and identify plasma proteins differentially expressed between groups of Brazilian diagnosed with type 1 (T1DM), type 2 (T2DM) diabetes with good and poor glycemic control and the non-diabetic group denominated control group (CG).

Methods

Patients with T1DM and T2DM were subdivided according to their glycated haemoglobin (HbA_1c) level: ≥ 53 mmol/mol and < 53 mmol/mol. Each subgroup was composed of ten subjects (n = 10). The plasma from each subgroup was pooled and depleted of albumin and IgG. The reminiscent proteins were quantified and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The relative volume of protein bands was determined by densitometry analysis, and those with differential abundance were identified by MALDI-TOF mass spectrometry.

Results

Alpha 2 - Macroglobulin (AMG) was 1.3-fold more abundant in T1DM with HbA_1c ≥ 53 mmol/mol and < 53 mmol/mol and 1.4-fold more abundant in T2DM with HbA_1c ≥ 53 mmol/mol compared to CG. Ceruloplasmin (Cp) and Haptoglobin (Hp) were overexpressed above 1.5-fold in all DM subgroups. Cp in T1DM and Hp in both types of DM were more expressed in HbA_1c ≥ 53 mmol/mol than <53 mmol/mol. Apolipoprotein A-I (Apo A-I) was upregulated only in T2DM subgroups.

Conclusion

In summary, three positive acute-phase proteins, AMG, Cp and Hp were more abundant in diabetic individuals regardless of the diabetes type. The highest Hp abundance in both types of DM with HbA_1c ≥ 53 mmol/mol, reinforces Hp as a possible biomarker associated with diabetic complications.

Haptoglobin and Its Related Protein, Zonulin-What Is Their Role in Spondyloarthropathy?

Haptoglobin (Hp) is an acute phase protein which supports the immune response and protects tissues from free radicals. Its concentration correlates with disease activity in spondyloarthropathies (SpAs). The Hp polymorphism determines the functional differences between Hp1 and Hp2 protein products. The role of the Hp polymorphism has been demonstrated in many diseases. In particular, the Hp 2-2 phenotype has been associated with the unfavorable course of some inflammatory and autoimmune disorders. Its potential role in modulating the immune system in SpA is still unknown. This article contains pathophysiological considerations on the potential relationship between Hp, its polymorphism and SpA.

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.

Effect of Anacetrapib on Cholesterol Efflux Capacity: A Substudy of the DEFINE Trial

Background

Anacetrapib is the only cholesteryl ester transfer protein inhibitor proven to reduce coronary heart disease (CHD). However, its effects on reverse cholesterol transport have not been fully elucidated. Macrophage cholesterol efflux (CEC), the initial step of reverse cholesterol transport, is inversely associated with CHD and may be affected by sex as well as haptoglobin copy number variants among patients with diabetes mellitus. We investigated the effect of anacetrapib on CEC and whether this effect is modified by sex, diabetes mellitus, and haptoglobin polymorphism.

Methods and Results

A total of 574 participants with CHD were included from the DEFINE (Determining the Efficacy and Tolerability of CETP Inhibition With Anacetrapib) trial. CEC was measured at baseline and 24‐week follow‐up using J774 macrophages, boron dipyrromethene difluoride–labeled cholesterol, and apolipoprotein B–depleted plasma. Haptoglobin copy number variant was determined using an ELISA assay. Anacetrapib increased CEC, adjusted for baseline CEC, risk factors, and changes in lipids/apolipoproteins (standard β, 0.23; 95% CI, 0.05–0.41). This CEC‐raising effect was seen only in men (P interaction=0.002); no effect modification was seen by diabetes mellitus status. Among patients with diabetes mellitus, anacetrapib increased CEC in those with the normal 1‐1 haptoglobin genotype (standard β, 0.42; 95% CI, 0.16–0.69) but not the dysfunctional 2‐1/2‐2 genotypes (P interaction=0.02).

Conclusions

Among patients with CHD, anacetrapib at a dose linked to improved CHD outcomes significantly increased CEC independent of changes in high‐density lipoprotein cholesterol or other lipids, with effect modification by sex and a novel pharmacogenomic interaction by haptoglobin genotype, suggesting a putative mechanism for reduced risk requiring validation.

Hp1-1 as a Genetic Marker Regulating Inflammation and the Possibility of Developing Diabetic Complications in Patients with Type 2 Diabetes-Cohort Studies

Background: This study assessed the influence of the haptoglobin phenotype on markers regulating inflammation in patients with type 2 diabetes. Methods: The haptoglobin phenotypes, soluble form of CD163 receptor (sCD163), p53 concentrations and high mobility group box protein 1 (HMGB1), interleukin 10 (IL-10) secretion in serum were assayed via ELISA tests. In the first part of the project, patients were divided into three groups which differed by the haptoglobin phenotype, and afterwards into two groups according to the criterion of the presence or absence of cardiovascular disease. Results: Diabetic patients with haptoglobin phenotype 1-1 (Hp1-1) had a significantly higher concentration of IL-10 and sCD163 compared to haptoglobin phenotype 2-1 (Hp2-1) and haptoglobin phenotype 2-2 (Hp2-2). Moreover, diabetic patients with Hp1-1 had a significantly lower concentration of p53 and HMGB1 compared to diabetic patients with Hp2-1 and Hp2-2. The results have shown that diabetics with Hp2-1 had a significantly lower postprandial glucose level compared to diabetics with Hp2-2. Apart from that, there were no differences in the occurrence of haptoglobin variants between patients with or without cardiovascular disease. Conclusions: Our study provides new data for a relationship between the type of haptoglobin in patients with type 2 diabetes and the concentration of factors that regulate the body’s inflammation. We have shown that the Hp1-1 can serve as a genetic marker of inflammatory processes.

Interaction between a haptoglobin genetic variant and coronary artery disease (CAD) risk factors on CAD severity in Singaporean Chinese population

BACKGROUND

Haptoglobin (Hp) is a plasma protein with strong anti-inflammation and antioxidant activities. Its plasma level is known to be inversely associated with many inflammatory diseases, including cardiovascular diseases. However, the association of HP genetic variants with coronary artery disease (CAD) severity/mortality, and how they interact with common CAD risk factors are largely unknown.

METHODS

We conducted the analysis in a Singaporean Chinese CAD population with Gensini severity scores (N = 582) and subsequently evaluated the significant findings in an independent cohort with cardiovascular mortality (excluding stroke) as outcome (917 cases and 19,093 controls). CAD risk factors were ascertained from questionnaires, and stenosis information from medical records. Mortality was identified through linkage with the nationwide registry of births and deaths in Singapore. Linear regression analysis between HP genetic variant (rs217181) and disease outcome were performed. Interaction analyses were performed by introducing an interaction term in the same regression models.

RESULTS

Although rs217181 was not significantly associated with CAD severity and cardiovascular mortality (excluding stroke) in all subjects, when stratified by hypertension status, hypertensive individuals with the minor T allele have more severe CAD (β = 0.073, SE = 0.030, p = 0.015) and non-hypertensive individuals with the T allele have lower risk for mortality (odds ratio = 0.771 (0.607-0.980), p = 0.033).

CONCLUSION

HP genetic variant is not associated with CAD severity and mortality in the general population. However, hypertensive individuals with the rs217181 T allele associated with higher Hp levels had more severe CAD while non-hypertensive individuals with the same allele had lower risk for mortality in the Chinese population.

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.

Cardiovascular and Metabolic Protection by Vitamin E: A Matter of Treatment Strategy?

Cardiovascular diseases (CVD) cause about 1/3 of global deaths. Therefore, new strategies for the prevention and treatment of cardiovascular events are highly sought-after. Vitamin E is known for significant antioxidative and anti-inflammatory properties, and has been studied in the prevention of CVD, supported by findings that vitamin E deficiency is associated with increased risk of cardiovascular events. However, randomized controlled trials in humans reveal conflicting and ultimately disappointing results regarding the reduction of cardiovascular events with vitamin E supplementation. As we discuss in detail, this outcome is strongly affected by study design, cohort selection, co-morbidities, genetic variations, age, and gender. For effective chronic primary and secondary prevention by vitamin E, oxidative and inflammatory status might not have been sufficiently antagonized. In contrast, acute administration of vitamin E may be more translatable into positive clinical outcomes. In patients with myocardial infarction (MI), which is associated with severe oxidative and inflammatory reactions, decreased plasma levels of vitamin E have been found. The offsetting of this acute vitamin E deficiency via short-term treatment in MI has shown promising results, and, thus, acute medication, rather than chronic supplementation, with vitamin E might revitalize vitamin E therapy and even provide positive clinical outcomes.

Inflammatory Diseases and Vitamin E-What Do We Know and Where Do We Go?

Inflammation-driven diseases and related comorbidities, such as the metabolic syndrome, obesity, fatty liver disease, and cardiovascular diseases cause significant global burden. There is a growing body of evidence that nutrients alter inflammatory responses and can therefore make a decisive contribution to the treatment of these diseases. Recently, the inflammasome, a cytosolic multiprotein complex, has been identified as a key player in inflammation and the development of various inflammation-mediated disorders, with nucleotide-binding domain and leucine-rich repeat pyrin domain (NLRP) 3 being the inflammasome of interest. Here an overview about the cellular signaling pathways underlying nuclear factor "kappa-light-chain-enhancer" of activated B-cells (NF-κB)- and NLRP3-mediated inflammatory processes, and the pathogenesis of the inflammatory diseases atherosclerosis and non-alcoholic fatty liver disease (NAFLD) is provided; next, the current state of knowledge for drug-based and dietary-based interventions for treating cardiovascular diseases and NAFLD is discussed. To date, one of the most important antioxidants in the human diet is vitamin E. Various in vitro and in vivo studies suggest that the different forms of vitamin E and also their derivatives have anti-inflammatory activity. Recent publications suggest that vitamin E-and possibly metabolites of vitamin E-are a promising therapeutic approach for treating inflammatory diseases such as NAFLD.

Haptoglobin: From hemoglobin scavenging to human health

Haptoglobin (Hp) belongs to the family of acute-phase plasma proteins and represents the most important plasma detoxifier of hemoglobin (Hb). The basic Hp molecule is a tetrameric protein built by two α/β dimers. Each Hp α/β dimer is encoded by a single gene and is synthesized as a single polypeptide. Following post-translational protease-dependent cleavage of the Hp polypeptide, the α and β chains are linked by disulfide bridge(s) to generate the mature Hp protein. As human Hp gene is characterized by two common Hp1 and Hp2 alleles, three major genotypes can result (i.e., Hp1-1, Hp2-1, and Hp2-2). Hp regulates Hb clearance from circulation by the macrophage-specific receptor CD163, thus preventing Hb-mediated severe consequences for health. Indeed, the antioxidant and Hb binding properties of Hp as well as its ability to stimulate cells of the monocyte/macrophage lineage and to modulate the helper T-cell type 1 and type 2 balance significantly associate with a variety of pathogenic disorders (e.g., infectious diseases, diabetes, cardiovascular diseases, and cancer). Alternative functions of the variants Hp1 and Hp2 have been reported, particularly in the susceptibility and protection against infectious (e.g., pulmonary tuberculosis, HIV, and malaria) and non-infectious (e.g., diabetes, cardiovascular diseases and obesity) diseases. Both high and low levels of Hp are indicative of clinical conditions: Hp plasma levels increase during infections, inflammation, and various malignant diseases, and decrease during malnutrition, hemolysis, hepatic disease, allergic reactions, and seizure disorders. Of note, the Hp:Hb complexes display heme-based reactivity; in fact, they bind several ferrous and ferric ligands, including O₂, CO, and NO, and display (pseudo-)enzymatic properties (e.g., NO and peroxynitrite detoxification). Here, genetic, biochemical, biomedical, and biotechnological aspects of Hp are reviewed.

Haptoglobin genotype 2-2 associated with atherosclerosis in patients with ischemic stroke

AIM

Ischemic stroke (IS) is multifactorial disease and therefore different genes and proteins play a role in its development. Haptoglobin (Hp) removes free hemoglobin and protects from iron-induced oxidative damage, inflammatory response, atherosclerosis and cerebrovascular diseases. The aim of this study was to investigate Hp genetic variants in patients with carotid atherosclerotic lesions and IS.

MATERIAL AND METHODS

A total of 121 subjects with IS participated in the study, 81 male and 40 female.

RESULTS

Among 121 patients with IS, 79 had diffuse atherosclerotic plaques and stenosis. Hp genotype was statistically significantly associated with CDFI neck carotid artery stenosis findings (p = 0.006). Patients with Hp1-2 genotype had statistically significantly larger odds for atherosclerotic changes compared to those with Hp1-1 genotype, as well as those with Hp2-2 genotype.

CONCLUSION

This study has shown an association of the Hp2-2 genotype and atherosclerosis in patients with IS, indicating Hp2-2 genotype as a genetic biomarker for precision medicine and personalized healthcare.

The haptoglobin 2-2 genotype is associated with cardiac autonomic neuropathy in type 1 diabetes: the RETRO HDLc study

AIM

The haptoglobin (Hp) 2-2 genotype has been shown to increase the risk of coronary artery disease, kidney dysfunction and mortality from cardiovascular and renal causes in type 1 diabetes (T1D). Similar associations, however, have not been observed in those without diabetes. As cardiac autonomic neuropathy (CAN) is a cardiovascular disease risk factor, we assessed the presence of an association between the Hp 2-2 genotype and CAN.

METHODS

The study included 216 individuals with childhood-onset T1D and 200 individuals with normal glucose tolerance (NGT) of similar age and gender distribution to their counterparts with T1D. CAN was assessed using an electrocardiogram as an abnormal, age-specific, heart rate response to deep breathing. Multivariable logistic regression models were used to assess the association between the Hp 2-2 genotype and CAN.

RESULTS

Compared with NGT, participants with T1D had a similar proportion of Hp 2-2 carriers (41.5% vs. 32.0%, p = 0.05) but a greater CAN prevalence (28.2% vs. 5.0%, p < 0.0001). In multivariable logistic regression models, those carrying the Hp 2-2 genotype had significantly higher odds of CAN compared with Hp 1-1 or Hp 2-1 carriers (OR = 2.27, p = 0.01). The presence of T1D (OR = 4.20, p = 0.0003), hypertension (OR = 2.08, p = 0.03), eGFR (OR = 0.98, p = 0.01) and WBC count (OR = 1.21, p = 0.02) were also associated with CAN. There was no T1D by Hp interaction (p = 0.92), although in stratified analyses, the Hp-CAN association was significant only in T1D.

CONCLUSIONS

The Hp 2-2 genotype was independently associated with greater odds of CAN in T1D though no definitive conclusions could be made in NGT.

The role of hemoglobin degradation pathway in preeclampsia: A systematic review and meta-analysis

INTRODUCTION

Overproduction of fetal hemoglobin by the placenta leading to increased consumption of endogenous heme scavenging proteins has been recently implicated as a novel pathway in the pathogenesis of preeclampsia. The aim of the present systematic review was to evaluate maternal serum levels of fetal hemoglobin, haptoglobin, heme oxygenase-1, hemopexin and α1-microglobulin, as well as haptoglobin phenotypes among preeclamptic and healthy pregnant women and assess their predictive role in the disease.

METHODS

Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched from inception. All studies comparing levels of fetal hemoglobin or heme scavengers among preeclamptic and healthy pregnant controls were deemed eligible.

RESULTS

Twenty-three studies were included, with a total number of 7461 pregnant women. Quantitative synthesis was not conducted for the comparison of serum levels due to high heterogeneity. Current evidence suggests that preeclampsia is associated with increased levels of fetal hemoglobin and α1-microglobulin, as well as with lower levels of serum hemopexin. Data regarding serum haptoglobin and heme oxygenase-1 were conflicting, as the available evidence did not unanimously suggest a significant change of their levels in the disease. Network meta-analysis indicated no significant association for any of the haptoglobin phenotypes with preeclampsia development.

DISCUSSION

The present review suggests that preeclampsia may be associated with increased fetal hemoglobin and α1-microglobulin and decreased hemopexin levels, although inter-study heterogeneity was high. Future large-scale studies are needed to fully elucidate the predictive efficacy of these markers by introducing cut-off values and defining the optimal gestational age for sampling.

Haptoglobin Hp1 Variant Does Not Associate with Small Vessel Disease

Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and protects tissues from oxidative damage. An Hp2 allele has been associated with an increased risk of cardiovascular complications. On the other hand, recent studies have suggested that Hp1 allele increases risk to develop severe cerebral small vessel disease. We aimed to replicate this finding in a first-ever stroke patient cohort. Hp was genotyped by PCR and gel electrophoresis in the Helsinki Stroke Aging Memory Study in patients with DNA and magnetic resonance imaging (MRI) available (SAM; n = 316). Lacunar infarcts and white matter lesions (WML) classified by Fazekas grading from brain MRI were associated with Hp genotypes. As population controls, we used participants of Cardiovascular diseases—a sub study of Health 2000 Survey (n = 1417). In the SAM cohort, 63.0% of Hp1-1 carriers (n = 46), 52.5% of Hp1-2 carriers (n = 141) and 51.2% of Hp2-2 carriers (n = 129) had severe WML (p = 0.372). There was no difference in severe WMLs between Hp1-1 vs. Hp1-2 and Hp2-2 carriers (p = 0.201). In addition, 68.9% of Hp1-1 carriers (n = 45), 58.5% of Hp1-2 carriers (n = 135), and 61.8% of Hp2-2 carriers (n = 126) had one or more lacunar lesions (p = 0.472). There was no difference in the number of patients with at least one lacunar infarct between Hp1-1 vs. Hp1-2 and Hp2-2 groups (p = 0.322). Neither was there any difference when diabetic patients (type I and II) were examined separately. Hp1 allele is not associated with an increased risk for cerebral small vessel disease in a well-characterized Finnish stroke patient cohort.

Haptoglobin-2 variant increases susceptibility to acute respiratory distress syndrome during sepsis

Acute respiratory distress syndrome (ARDS) is an inflammatory lung disorder that frequently complicates critical illness and commonly occurs in sepsis. Although numerous clinical and environmental risk factors exist, not all patients with risk factors develop ARDS, raising the possibility of genetic underpinnings for ARDS susceptibility. We have previously reported that circulating cell-free hemoglobin (CFH) is elevated during sepsis, and higher levels predict worse outcomes. Excess CFH is rapidly scavenged by haptoglobin (Hp). A common HP genetic variant, HP2, is unique to humans and is common in many populations worldwide. HP2 haptoglobin has reduced ability to inhibit CFH-mediated inflammation and oxidative stress compared with the alternative HP1. We hypothesized that HP2 increases ARDS susceptibility during sepsis when plasma CFH levels are elevated. In a murine model of sepsis with elevated CFH, transgenic mice homozygous for Hp2 had increased lung inflammation, pulmonary vascular permeability, lung apoptosis, and mortality compared with wild-type mice. We then tested the clinical relevance of our findings in 496 septic critically ill adults, finding that HP2 increased ARDS susceptibility after controlling for clinical risk factors and plasma CFH. These observations identify HP2 as a potentially novel genetic ARDS risk factor during sepsis and may have important implications in the study and treatment of ARDS.

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.

Haptoglobin Phenotype Modulates Lipoprotein-Associated Risk for Preeclampsia in Women With Type 1 Diabetes

CONTEXT

The incidence of preeclampsia (PE) is increased in women with diabetes (∼20% vs ∼5% in the general population), and first trimester lipoprotein profiles are predictive. Haptoglobin (Hp), a protein with functional genetic polymorphisms, has antioxidant, anti-inflammatory, and angiogenic effects. Among people with diabetes, the Hp 2-2 phenotype is associated with cardiorenal disease.

OBJECTIVE

To investigate whether Hp phenotype is associated with PE in type 1 diabetes mellitus (T1DM) and/or modulates lipoprotein-associated risks.

DESIGN AND SETTING

Multicenter prospective study of T1DM pregnancy.

PATIENTS

Pregnant women with T1DM (normal albuminuria, normotensive at enrolment, n = 47) studied at three visits, all preceding PE onset: 12.3 ± 1.9, 21.8 ± 1.5, and 31.5 ± 1.6 weeks' gestation (mean ± SD).

MAIN OUTCOME MEASURES

Hp phenotype and lipoprotein profiles in women with (n = 23) vs without (n = 24) subsequent PE.

RESULTS

Hp phenotype did not predict PE, but lipoprotein associations with subsequent PE were confined to women with Hp 2-2, in whom the following associations with PE were observed: increased low-density lipoprotein (LDL) cholesterol, LDL particle concentration, apolipoprotein B (APOB), triacylglycerol/high-density lipoprotein (HDL) cholesterol ratio, and APOB/apolipoprotein AI (APOA1) ratio; decreased HDL cholesterol, APOA1, large HDL particle concentration, and peripheral lipoprotein lipolysis (all P < 0.05). In women with one or two Hp-1 alleles, no such associations were observed.

CONCLUSIONS

In women with T1DM, although Hp phenotype did not predict PE risk, lipoprotein-related risks for PE were limited to those with the Hp 2-2 phenotype. Hp phenotype may modulate PE risk in diabetes.

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.

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Haptoglobin Phenotype Is Associated With High-Density Lipoprotein–Bound Hemoglobin Content and Coronary Endothelial Dysfunction in Patients With Mild Nonobstructive Coronary Artery Disease

Objective—

Coronary endothelial dysfunction (ED) is an early stage of atherosclerosis and is associated with impaired high-density lipoprotein (HDL) function. A functional polymorphism at the haptoglobin (Hp) gene locus (rs72294371) has been associated with marked differences in HDL structure and function. We sought to determine whether Hp phenotype was associated with coronary ED and whether the amount of hemoglobin (Hb) tethered to HDL via Hp was Hp-type dependent and associated with ED.

Approach and Results—

Microvascular and epicardial coronary endothelial function was assessed in 338 individuals with nonobstructive coronary artery disease. Microvascular ED was defined as <50% change in coronary blood flow and epicardial ED as ≥20% decrease in coronary artery diameter after intracoronary acetylcholine infusion. The amount of Hb bound to HDL was measured by ELISA after HDL purification from plasma samples using immune-affinity chromatography. One hundred and seventy of the individuals in this study (50.3%) were diagnosed with microvascular ED, 143 (42.3%) with epicardial ED, and 67 (19.7%) had diabetes mellitus (DM). Hp phenotype was significantly associated with microvascular ( P =0.01) and epicardial ED ( P =0.04) among DM individuals. There was a significant and inverse correlation between the amount of HDL-bound Hb and change in coronary blood flow (r=−0.40; P <0.0001) and in coronary artery diameter (r=−0.44; P <0.0001) in response to acetylcholine infusion. Hb content of HDL was significantly increased in individuals with Hp 2-2 and DM. In a logistic regression model, Hp 2-2 phenotype was associated with microvascular ED (odds ratio, 1.9; P =0.03) and the amount of HDL-bound Hb was an independent predictor of both microvascular (odds ratio, 4.6 for each 1-SD increase; P <0.0001) and epicardial (odds ratio, 2.2; P <0.0001) ED.

Conclusions—

Hp phenotype is significantly associated with coronary ED in DM individuals. This association is likely related to increased Hb tethering to HDL via Hp 2-2 in DM.

Haptoglobin 2-2 Genotype is Associated with More Advanced Disease in Subjects with Non-Alcoholic Steatohepatitis: A Retrospective Study

INTRODUCTION

Haptoglobin (Hp) genotypes were reported as an independent risk factor for metabolic diseases. This study aimed to investigate the association between Hp gene polymorphism and the severity of nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 441 subjects (NAFLD group, n = 272; healthy control, n = 169) were recruited, and their clinical biochemical parameters were measured in all subjects. Haptoglobin genotyping was performed using genomic DNA extracted from peripheral blood leukocytes. Among the NAFLD group, 107 patients underwent liver biopsy, and histology was evaluated by a pathologist on the basis of the CRN scoring system.

RESULTS

NAFLD patients had much lower frequency of Hp 1-1 genotype and higher frequency of Hp 2-2 than healthy controls (0.4% vs 9.5%, 55.8% vs 47.9%, P < 0.001). NAFLD patients with Hp 2-2 genotype had much higher levels of body mass index (BMI), total cholesterol (TC), liver enzymes, ferritin, and controlled attenuation parameter (CAP) values than non-Hp 2-2 genotype (P < 0.05). In histology, patients with nonalcoholic steatohepatitis (NASH) had higher frequency of Hp 2-2 genotype than non-NASH patients (71.3% vs 22.2%, P < 0.001); patients with significant fibrosis had higher frequency of Hp 2-2 genotype (78.3% vs 54.8%, P < 0.05) than no/mild fibrosis patients. NAFLD patients with Hp 2-2 genotype had higher proportion with higher steatosis scores, lobular inflammation scores, ballooning scores, NAFLD activity scores (NAS), and fibrosis stages (P < 0.05 for all) than Hp 2-2 groups. Furthermore, Hp 2-2 genotype was independently associated with NASH (OR = 5.985, P < 0.05) and significant fibrosis (OR = 6.584, P < 0.05).

CONCLUSIONS

Hp 2-2 genotype is closely associated with the severity of NAFLD.

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 levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammation, and hypertension in type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an inflammatory condition associated to obesity and increased oxidative stress. Haptoglobin (Hp) is an acute phase reactant that scavenges extracorpuscular hemoglobin from circulation and prevents heme-iron oxidative damage.

OBJECTIVE

To assess the association between Hp levels and Hp1-Hp2 gene polymorphism and clinical and laboratory parameters in patients with T2DM.

METHODS

The study sample consisted of 102 T2DM patients and 62 controls. Hp plasma levels were measured using an ELISA assay, and Hp genotyping was performed using a specific two-step allelic polymerase chain reaction.

RESULTS

Hp levels were higher in T2DM patients as compared to controls (p=0.005). T2DM patients with high blood pressure had higher Hp levels than patients without this comorbidity (p=0.021). Obese T2DM patients had higher Hp levels as compared to obese controls (p=0.009) and to non-obese T2DM patients (p=0.003). The Hp1-Hp1 genotype was showed to be associated to T2DM according to additive (OR=3.038, 95% CI 1.127-8.192; p=0.036) and dominant model (OR=0.320, 95% CI 0.118-0.839; p=0.010), but Hp2 allele carriers contributed with higher Hp levels in T2DM as compared to controls. Waist circumference (p=0.002), BMI (p=0.001), and IL-6 (p=0.012), and hs-CRP (p=0.001) levels positively correlated with Hp levels in the T2DM group.

CONCLUSION

These results suggest that Hp levels are influenced by Hp1-Hp2 polymorphism, obesity, inflammatory status, and high blood pressure in T2DM.