Effect Of Haptoglobin Research Articles

Endothelial Microvascular Dysfunction and Its Relationship with Haptoglobin Levels in Patients with Different Phenotypes of Chronic Heart Failure

Aim. To study the relationship between the level of haptoglobin and the main indicators of microcirculation (MC) in patients with different phenotypes of chronic heart failure (CHF).Materials and methods. Patients with different phenotypes of functional class II-IV chronic heart failure according to NYHA (n=80) underwent a general clinical examination, determination of the serum haptoglobin level by enzyme-linked immunosorbent assay, as well as an assessment of the MC state on the medial surface of the upper third of the leg by laser Doppler flowmetry (LDF).Results. Patients with CHF included patients with preserved left ventricular ejection fraction (HFpEF; n=27, intermediate ejection fraction (HFmrEF; n=25) and reduced ejection fraction (HFrEF; n=28). The median value of haptoglobin in the HFpEF group was 1387.6 [ 747.5; 1946.9] mg/l, in the HFmrEF group was 1583.4 [818.9; 2201.4] mg/l, in the HFrEF group was 968.5 [509.5; 1324.4] mg/l. Correlation analysis revealed statistically significant relationships between haptoglobin and the amplitudes of the endothelial frequency range (Ae) in the groups of HFmrEF (r=-0.628, 95% confidence interval [CI] -0.256; -0.825, p=0.003) and HFrEF (r=-0.503, 95% CI -0.089; -0.803, p=0.02). A negative relationship between the haptoglobin level and Kv and σ was revealed, as well as a formula for calculating the value of haptoglobin was obtained, which is predicted on the basis of the amplitude index of the endothelial frequency range: [haptoglobin]=1787-(4053×Ae).Conclusion. The multifactorial effect of haptoglobin is realized in the central and peripheral mechanisms of MC regulation. Low values of haptoglobin in blood plasma should be considered as a potential marker for the development of complications and used in a comprehensive assessment of the state of patients with CHF. Evaluation of the diagnostic and prognostic significance of haptoglobin, especially in patients with HFmrEF, requires further study.

Anti-inflammatory effects of haptoglobin on LPS-stimulated macrophages: Role of HMGB1 signaling and implications in chronic wound healing.

Nonhealing wounds possess elevated numbers of pro-inflammatory M1 macrophages, which fail to transition to anti-inflammatory M2 phenotypes that promote healing. Hemoglobin (Hb) and haptoglobin (Hp) proteins, when complexed (Hb-Hp), can elicit M2-like macrophages through the heme oxygenase-1 (HO-1) pathway. Despite the fact that nonhealing wounds are chronically inflamed, previous studies have focused on non-inflammatory systems, and do not thoroughly compare the effects of complexed vs individual proteins. We aimed to investigate the effect of Hb/Hp treatments on macrophage phenotype in an inflammatory, lipopolysaccharide (LPS)-stimulated environment, similar to chronic wounds. Human M1 macrophages were cultured in vitro and stimulated with LPS. Concurrently, Hp, Hb, or Hb-Hp complexes were delivered. The next day, 27 proteins related to inflammation were measured in the supernatants. Hp treatment decreased a majority of inflammatory factors, Hb increased many, and Hb-Hp had intermediate trends, indicating that Hp attenuated overall inflammation to the greatest extent. From this data, Ingenuity Pathway Analysis software identified high motility group box 1 (HMGB1) as a key canonical pathway-strongly down-regulated from Hp, strongly up-regulated from Hb, and slightly activated from Hb-Hp. HMGB1 measurements in macrophage supernatants confirmed this trend. In vivo results in diabetic mice with biopsy punch wounds demonstrated accelerated wound closure with Hp treatment, and delayed wound closure with Hb treatment. This work specifically studied Hb/Hp effects on macrophages in a highly inflammatory environment relevant to chronic wound healing. Results show that Hp-and not Hb-Hp, which is known to be superior in noninflammatory conditions-reduces inflammation in LPS-stimulated macrophages, and HMGB1 signaling is also implicated. Overall, Hp treatment on M1 macrophages in vitro reduced the inflammatory secretion profile, and also exhibited benefits in in silico and in vivo wound-healing models.

Effect of haptoglobin on the treatment of chronic hepatitis B with interferon.

There are two main types of drugs that are used to treat chronic hepatitis B (CHB), including interferon (IFN) and nucleotide analogues. IFN inhibits the virus through direct antiviral activity and via immune regulation, and it has been widely applied for the treatment of CHB and other infections. However, the efficiency of IFN therapy is not entirely satisfactory. The aim of the present study was to investigate the factors affecting IFN therapy. The plasma of patients with CHB treated with IFN was collected and divided into the virological response group and non-virological response group according to their virological response. Serum proteins of virologically responsive patients were compared before and after IFN therapy using isobaric tags for relative and absolute quantitation technology. ELISA was used to validate these results in the same sample. In in vitro cell experiments, HepG2.2.15 cells were transfected with haptoglobin (Hp)-targeting small interfering RNA to inhibit expression of the Hp protein, and reverse transcription-quantitative polymerase chain reaction and western blotting were utilized to detect hepatitis B virus (HBV)-DNA, IFN and downstream molecular changes in the cell supernatants. The Hp protein levels were demonstrated to be significantly lower following 48 weeks of IFN therapy, and the levels of Hp in patients in the virological response group were significantly lower than those in the non-virological response group. In in vitro cell experiments, following inhibition of Hp protein expression, significantly decreased levels of HBV-DNA, and elevated levels of IFN and its downstream molecules were observed. These findings suggest that Hp may be able to predict the efficacy of IFN therapy, and it may inhibit HBV clearance. There is an association between Hp and IFN, which requires further clinical and laboratory studies to explore.

Haptoglobin inhibits phospholipid transfer protein activity in hyperlipidemic human plasma

BackgroundHaptoglobin is a plasma protein that scavenges haemoglobin during haemolysis. Phospholipid Transfer Protein (PLTP) transfers lipids from Low Density Lipoproteins (LDL) to High Density Lipoproteins (HDL). PLTP is involved in the pathogenesis of atherosclerosis which causes coronary artery disease, the leading cause of death in North America. It has been shown that Apolipoprotein-A1 (Apo-A1) binds and regulates PLTP activity. Haptoglobin can also bind to Apo-A1, affecting the ability of Apo-A1 to induce enzymatic activities. Thus we hypothesize that haptoglobin inhibits PLTP activity. This work tested the effect of Haptoglobin and Apo-A1 addition on PLTP activity in human plasma samples. The results will contribute to our understanding of the role of haptoglobin on modulating reverse cholesterol transport.ResultsWe analyzed the PLTP activity and Apo-A1 and Haptoglobin content in six hyperlipidemic and six normolipidemic plasmas. We found that Apo-A1 levels are proportional to PLTP activity in hyperlipidemic (R2 = 0.66, p < 0.05) but not in normolipidemic human plasma. Haptoglobin levels and PLTP activity are inversely proportional in hyperlipidemic plasmas (R2 = 0.57, p > 0.05). When the PLTP activity was graphed versus the Hp/Apo-A1 ratio in hyperlipidemic plasma there was a significant correlation (R2 = 0.69, p < 0.05) suggesting that PLTP activity is affected by the combined effect of Apo-A1 and haptoglobin. When haptoglobin was added to individual hyperlipidemic plasma samples there was a dose dependent decrease in PLTP activity. In these samples we also found a negative correlation (-0.59, p < 0.05) between PLTP activity and Hp/Apo-A1. When we added an amount of haptoglobin equivalent to 100% of the basal levels, we found a 64 ± 23% decrease (p < 0.05) in PLTP activity compared to basal PLTP activity. We tested the hypothesis that additional Apo-A1 would induce PLTP activity. Interestingly we found a dose dependent decrease in PLTP activity upon Apo-A1 addition. When both Apo-A1 and Hpt were added to the plasma samples there was no further reduction in PLTP activity suggesting that they act through a common pathway.ConclusionThese findings suggest an inhibitory effect of Haptoglobin over PLTP activity in hyperlipidemic plasma that may contribute to the regulation of reverse cholesterol transport.

Effect of haptoglobin on the metabolism of vitamin C

Haptoglobin is a hemoglobin-binding antioxidant showing a genetic polymorphism with three types: Hp 1-1, Hp 2-1, and Hp 2-2. The Hp 2-2 type has been associated with an increased risk of atherosclerosis. We investigated vitamin C metabolism in vivo and in vitro according to haptoglobin type in a study group of 135 healthy volunteers. Serum vitamin C concentrations were associated with haptoglobin type, showing lowest values in serum from Hp 2-2 subjects (P < 0.01). Renal threshold for L-ascorbic acid was within the normal range and metabolization to oxalate was not different among haptoglobin-type groups. Serum concentrations of other endogenous antioxidants (uric acid, bilirubin, albumin, ceruloplasmin, and total antioxidative status) were not different among haptoglobin-type groups. In vitro experiments showed a lower stability of L-ascorbic acid in blood from subjects with the Hp 2-2 type (P < 0.01). L-Ascorbic acid depletion in vitro was inversely related to haptoglobin concentration (r = -0.738). The results of this study indicate a higher rate of L-ascorbic acid oxidation in Hp 2-2 carriers because they have less protection against hemoglobin-iron driven peroxidation.

Effect of haptoglobin on immunological activity of hemoglobin

The extent to which antigenic determinants of hemoglobin are quantitatively or qualitatively modified on complex formation with haptoglobinhas has been examined. From the data on Ouchterlony double immunodiffusion, it has been apparent that the antigenic determinants of hemoglobin are not modified nor masked by complex formation with human or rabbit haptoglobin, and that new antigenic determinants of hemoglobin do not appear in the molecule. The precipitability of hemoglobin-human haptoglobin complex with anti-hemoglobin serum was much greater than that of the hemogglobin with the same antiserum. Hemoglobin-rabbit haptoglobin complex is also precipitated with anti-hemoglobin serum more readily than free hemoglobin, but the difference is not so marked as for the human moiety. With respect to evoking antibody against hemoglobin in rabbits, the antigenicity of hemoglobin associated with rabbit haptoglobin in vitro is stronger than that of free hemoglobin. With this in mind, in order to clarify one of the explanations of increased antigenicity of hemoglobin associated with haptoglobin, the susceptibility of hemoglobin-haptoglobin complex to cathepsins and other proteases has been compared with that of free hemoglobin. Based on the results, it has been concluded that the resistance to these protease of hemoglobin associated with haptoglobin may be one possible explanation for the stonger antigenicity of hemoglobin-haptoglobin complex compared with free hemoglobin.

Effect of haptoglobin on immunochemical properties of hemoglobin

Effect of haptoglobin on immunochemical properties of hemoglobin