Haptoglobin, acid phosphatase and demographic factors: obesity risk

The aim of this work is to study the risk of obesity posed by two genetic factors: haptoglobin phenotype and acid phosphatase phenotype, one enzymatic activity: acid phosphatase activity (ACP1), age and gender. Haptoglobin (Hp) is a protein of the immune system, and three phenotypes of Hp are found in humans: Hp1-1, Hp2-1, and Hp2-2. This protein is associated with a susceptibility to common pathological conditions, such as obesity. ACP1 is an intracellular enzyme The phenotypes of ACP1 (AA, AB, AC, BB, BC, CC) are also considered. We took a sample of 127 subjects with complete data from 714 registers. Since we intend to identify risk factors for obesity, an ordinal regression model is adjusted, using the Body Mass Index, BMI, to define weight categories. Haptoglobin phenotype, enzymatic activity of ACP1, acid phosphatase phenotype, age and gender are considered as regressor variables. We found three factors associated with an increased risk of obesity: phenotype Hp2-1 of haptoglobin (estimated odds ratio OR 11.54), phenotype AA of acid phosphatase (OR 33.788) and age (OR 1.39). The interaction between phenotype Hp2-1 and phenotype AC is associated with a decreased risk of obesity (OR 0.032); The interaction between phenotype AA and ACP1 activity is associated with a decreased risk of obesity (OR 0.954).

Identification of haptoglobin as an angiogenic factor in sera from patients with systemic vasculitis.

Angiogenesis is an important process in chronic inflammatory diseases. We observed that sera from patients with systemic vasculitis stimulated angiogenesis in an in vitro model using human umbilical vein endothelial cells cultured on a basement membrane (Matrigel) substrate. After 40% ammonium sulfate precipitation, angiogenic activity remained in the low molecular weight fraction and could be inactivated by heat. SDS-page of serum FPLC fractions exhibiting maximal angiogenic activity demonstrated two prominent species of 45 and 16-20 kD in patients' sera. These bands were much less apparent in sera obtained from control subjects. Amino-terminal sequencing of the 45-kD protein demonstrated that it was haptoglobin. Purified haptoglobin stimulated angiogenesis in a dose-dependent manner. The angiogenic activity of vasculitis patients' sera was partially inhibited by an antihaptoglobin antibody. Furthermore, serum haptoglobin levels in vasculitis patients correlated both with disease and angiogenic activity. Haptoglobin angiogenic activity was confirmed in two in vivo models using an implanted disc and a subcutaneous injection of basement membrane. Stimulation of angiogenesis is a newly recognized biological function of haptoglobin. The increased levels of haptoglobin found in chronic inflammatory conditions may play an important role in tissue repair. In systemic vasculitis, haptoglobin might also compensate for ischemia by promoting development of collateral vessels.

Haptoglobin polymorphism correlated with coronary artery disease

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Serum haptoglobin types in patients with hemoglobinopathies

Haptoglobin types were determined in 626 individuals living in the State of Sao Paulo (Brazil). Of these, 484 had Hb AA, 31 major beta thalassemia, 43 minor beta thalassemia, 14 Hb SS, and 54 Hb AS. Frequency distribution of the three most common types observed among patients with type beta thalassemia differed significantly from that observed in the Caucasian group with Hb AA. There was a significant increase in Hp 1-1, which led us to assume that these disorders participate in a selective process acting on haptoglobins and altering the equilibrium of their frequencies. This relationship was not observed when we compared patients with Hb SS and Hb AS with Black patients with Hb AA, although the type most often observed among patients with Hb SS was Hp 1-1. The distributions of Hp groups observed among Caucasian and Black patients with Hb AA were similar to those obtained by other investigators for the South and Southeast regions of Brazil, with the exception of Rio de Janeiro.

Structure of the haptoglobin-haemoglobin complex

Red cell haemoglobin is the fundamental oxygen-transporting molecule in blood, but also a potentially tissue-damaging compound owing to its highly reactive haem groups. During intravascular haemolysis, such as in malaria and haemoglobinopathies(1), haemoglobin is released into the plasma, where it is captured by the protective acute-phase protein haptoglobin. This leads to formation of the haptoglobin-haemoglobin complex, which represents a virtually irreversible non-covalent protein-protein interaction(2). Here we present the crystal structure of the dimeric porcine haptoglobin-haemoglobin complex determined at 2.9 angstrom resolution. This structure reveals that haptoglobin molecules dimerize through an unexpected beta-strand swap between two complement control protein (CCP) domains, defining a new fusion CCP domain structure. The haptoglobin serine protease domain forms extensive interactions with both the alpha- and beta-subunits of haemoglobin, explaining the tight binding between haptoglobin and haemoglobin. The haemoglobin-interacting region in the alpha beta dimer is highly overlapping with the interface between the two alpha beta dimers that constitute the native haemoglobin tetramer. Several haemoglobin residues prone to oxidative modification after exposure to haem-induced reactive oxygen species are buried in the haptoglobin-haemoglobin interface, thus showing a direct protective role of haptoglobin. The haptoglobin loop previously shown to be essential for binding of haptoglobin-haemoglobin to the macrophage scavenger receptor CD163 (ref. 3) protrudes from the surface of the distal end of the complex, adjacent to the associated haemoglobin alpha-subunit. Small-angle X-ray scattering measurements of human haptoglobin-haemoglobin bound to the ligand-binding fragment of CD163 confirm receptor binding in this area, and show that the rigid dimeric complex can bind two receptors. Such receptor cross-linkage may facilitate scavenging and explain the increased functional affinity of multimeric haptoglobin-haemoglobin for CD163 (ref. 4).

Identification of haptoglobin as a natural inhibitor of trypanocidal activity in human serum.

Trypanosomes are protozoan parasites of medical and veterinary importance. Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense infect humans, causing African sleeping sickness. However, Trypanosoma brucei brucei can only infect animals, causing the disease Nagana in cattle. Man is protected from this subspecies of trypanosomes by a toxic subtype of high density lipoproteins (HDLs) called the trypanosome lytic factor (TLF). The toxic molecule in TLF is believed to be the haptoglobin-related protein that when bound to hemoglobin kills the trypanosome via oxidative damage initiated by its peroxidase activity. The amount of lytic activity in serum varies widely between different individuals with up to a 60-fold difference in activity. In addition, an increase in the total amount of lytic activity occurs during the purification of TLF, suggesting that an inhibitor of TLF (ITLF) exists in human serum. We now show that the individual variation in trypanosome lytic activity in serum correlates to variations in the amount of ITLF. Immunoblots of ITLF probed with antiserum against haptoglobin recognize a 120-kDa protein, indicating that haptoglobin is present in partially purified ITLF. Haptoglobin involvement is further shown in that it inhibits TLF in a manner similar to ITLF. Using an anti-haptoglobin column to remove haptoglobin from ITLF, we show that the loss of haptoglobin coincides with the loss of inhibitor activity. Addition of purified haptoglobin restores inhibitor activity. This indicates that haptoglobin is the molecule responsible for inhibition and therefore causing the individual variation in serum lytic activity.

Lack of Association Between Haptoglobin Phenotype and Cystic Fibrosis Outcomes

Haptoglobin (Hp), a heme-Iron chelator, has different isoforms which are associated with variable tendency toward infections: Hp 1-1, Hp 2-1, and Hp 2-2. Cystic fibrosis (CF) outcomes are variable and influenced by genetic and environmental factors. The aim of this study was to determine whether Hp phenotype influenced disease severity in CF. One hundred forty-two CF patients from two centers were analyzed for Haptoglobin phenotype using gel electrophoresis of hemoglobin enriched serum. Clinical and microbiological data including bacterial colonization status, lung function, presence of CF-related diabetes and liver disease, rate of exacerbation, and mortality were compared between Hp phenotype groups. We found a trend toward less mucoid PA among Hp 2-2 (20.4 %) compared with Hp 1-1 and Hp 2-1 individuals (33.3 %), p = 0.317. Hp 2-2 individuals also had less antibiotic courses, and lower inflammatory markers without statistical significance. Haptoglobin phenotype is unlikely to be an important modifier of CF phenotype.

Fructose Alters Adiponectin, Haptoglobin and Angiotensinogen Gene Expression in 3T3-L1 Adipocytes

Fructose- or sucrose-rich diets can cause insulin resistance and increase the risk of cardiovascular disease. Adipokines are correlated with the development of these diseases in obesity. We hypothesize that fructose and sucrose induce insulin resistance via effects on adipokine gene expression in adipocytes. This study analyzed the effect of fructose or glucose on adiponectin, haptoglobin, and angiotensinogen gene expression in 3T3-L1 adipocytes. Ten days after differentiation, the cells were pretreated with serum- and glucose-free medium. Twenty-four hours later, fructose or glucose (0, 5, 10, or 20 mmol) was added into the medium, and the cells were collected after a further 24 hours. Adiponectin, haptoglobin, and angiotensinogen gene expression were determined. Adiponectin gene expression increased when 10 or 20 mmol glucose was added compared with that observed for the non–hexose-treated cells. A similar effect occurred when 5 mmol fructose was added. Glucose (10 mmol) and fructose (20 mmol) stimulated haptoglobin gene expression in 3T3-L1 adipocytes compared with 0 mmol, with glucose producing a more pronounced effect. Although 20 mmol fructose caused an increase in angiotensinogen gene expression, glucose did not. In conclusion, in this study of 2 hexoses revealed an increase in adiponectin gene expression, suggesting that the effect of a glucose-rich diet on the development of insulin resistance is not related to the effect of these hexoses on adipocyte adiponectin gene expression. However, insulin resistance and cardiovascular disease promoted by fructose-rich diets could be partially related to the effect of fructose on adiponectin and angiotensinogen gene expression.

Long Chain Saturated Fatty Acids Increase Haptoglobin Gene Expression in C57BL/6J Mice Adipose Tissue and 3T3-L1 Cells

Background Dietary lipids are directly related to the composition of adipose tissue, aetiology of obesity and arousal of obesity-related pathologies, like chronic inflammation states. Haptoglobin is an acute phase protein secreted by the liver and white adipose tissue, and its blood levels vary according to the volume of fat in the body. Aim of the study To investigate the effect of diets enriched with large amounts of dietary fats, which differ in their fatty acid composition, on the haptoglobin gene expression by visceral and subcutaneous adipose tissue of mice fed for 2 days or 8 weeks. 3T3-L1 cells were treated with fatty acids that are found in those types of dietary fats. Methods Mice were treated acutely (for 2 days) or chronically (for 8 weeks) with diets enriched with soybean oil, fish oil, coconut oil or lard. 3T3-L1 cells were treated with six different fatty acids. Haptoglobin gene expression was quantified by northern blotting. Results Both chronic and acute treatment with lard, which is rich in long chain saturated fatty acids, increased the haptoglobin mRNA expression in the retroperitoneal and epidydimal white adipose tissues. Chronic treatment with coconut oil, which is rich in medium chain saturated fatty acids, increased the haptoglobin expression in the epidydimal and subcutaneous depots. In 3T3-L1, palmitic acid increased the haptoglobin gene expression. Conclusion The type of lipids in the diet can differently modulate the white adipose tissue gene expression of haptoglobin, and saturated fatty acids play a major role in promoting a pro-inflammatory environment. This response is fat pad specific and dependant on the duration of treatment.

Proteomic analysis of normal and malignant prostate tissue to identify novel proteins lost in cancer

BACKGROUND. Alterations of important protein pathways, including loss of prostate secretory granules, and disruption of the prostatic secretory pathway have been identified as early events in malignancy. In this study, proteomics was used to map the differences in protein expression between normal and malignant prostate tissues and to identify and analyze differentially expressed proteins in human prostate tissue with particular regard to the proteins lost in malignancy. METHODS. Small quantities of normal and malignant prostate tissue were taken fresh from 34 radical prostatectomy cases. After histological examination, proteins were solubilized from selected tissues and separated using two-dimensional electrophoresis. Using image analysis, the proteome of normal and malignant tissues were mapped and differentially expressed proteins (present in normal and absent in malignant tissue) were identified and subsequently analyzed using peptide mass finger printing and N-terminal sequencing. Western blotting and immunohistochemistry were performed to examine expression profiles and tissue localization of candidate proteins. RESULTS. Comparison of protein maps of normal and malignant prostate were used to identify 20 proteins which were lost in malignant transformation, including prostate specific antigen (PSA), alpha-l antichymotrypsin (ACT), haptoglobin, and lactoylglutathione lyase. Three of the 20 had not previously been reported in human prostate tissue (Ubiquitin-like NEDD8, calponin, and a follistatin-related protein). Western blotting confirmed differences in the expression profiles of NEDD8 and calponin, and immunohistochemistry demonstrated differences in the cellular localization of these two proteins in normal and malignant prostate glands. CONCLUSIONS. The expression of NEDD8, calponin, and the follistatin-related protein in normal prostate tissues is a novel finding and the role of these important functional proteins in normal prostate and their loss or reduced expression in prostate malignancy warrants further investigations. (C) 2002 Wiley-Liss, Inc.

Rhipicephalus (Boophilus) microplus: Distinct acute phase proteins vary during infestations according to the genetic composition of the bovine hosts, Bos taurus and Bos indicus

Tick bites may trigger acute phase responses. Positive and negative acute phase proteins were measured in infested cattle genetically resistant and susceptible to ticks. During heavier infestations levels of haptoglobin increased significantly in susceptible bovines; levels of serum amyloid A increased in resistant bovines; levels of alpha-l-acid glycoprotein decreased significantly in resistant bovines; levels of transferrin decreased significantly in susceptible bovines. In conclusion, tick infestations trigger acute phase responses and enhancement of specific acute phase proteins differs according to the genetic composition of hosts. Acute phase proteins may constitute useful biological signatures for monitoring the stress induced by tick infestations. (c) 2007 Elsevier Inc. All rights reserved.