Distribution of haptoglobin phenotypes in oesophageal and gastric cancer

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.

Involvement of haptoglobin phenotypes and genotypes in non-muscle invasive bladder cancer: A possible prognostic marker for risk stratification

The association of haptoglobin (Hp) with various cancers has been reported and also it has been documented that the Hp phenotypes/genotypes have different functional ability. So, we examined phenotypes/genotypes of Hp in newly diagnosed, untreated non-muscle invasive bladder cancer (NMIBC) patients and investigated its prognostic value for risk stratification of the cancer. In eighty NMIBC patients and 80 healthy individuals the Hp genotypes and phenotypes were analyzed using polymerase chain reaction (PCR) and two-dimensional gel electrophoresis (2D-GE), respectively. Besides, the presence of the Hpα1, α2, and β chains in the sera was confirmed by Mass Spectrometry (MS). The frequencies of the 1-1 and 2-2 genotypes/phenotypes were respectively higher and lower in healthy subjects compared to the patients. Our results revealed that the 2-2 genotype/phenotype could increase the risk of NMIBC. There was a positive association between the 2-2 genotype/phenotype with the T category/grade of cancer (p<0.05). The present study implied a strong association between the Hp phenotypes and genotypes with NMIBC. It was found that the 2-2 genotype and phenotype could be a risk factor for NMIBC incidence, as well as, progression. This study introduced Hp genotyping as a possible cost-effective and precise method for prognosis of individuals at the risk of NMIBC.

Association between IL1 gene polymorphism and human African trypanosomiasis in populations of sleeping sickness foci of southern Cameroon

BACKGROUND

Human African Trypanosomiasis (HAT) is a neglected tropical disease caused by infections due to Trypanosoma brucei subspecies. In addition to the well-established environmental and behavioural risks of becoming infected, there is evidence for a genetic component to the response to trypanosome infection. We undertook a candidate gene case-control study to investigate genetic associations further.

METHODOLOGY

We genotyped one polymorphism in each of seven genes (IL1A, IL1RN, IL4RN, IL6, HP, HPR, and HLA-G) in 73 cases and 250 controls collected from 19 ethno-linguistic subgroups stratified into three major ethno-linguistic groups, 2 pooled ethno-linguistic groups and 11 ethno-linguistic subgroups from three Cameroonian HAT foci. The seven polymorphic loci tested consisted of three SNPs, three variable numbers of tandem repeat (VNTR) and one INDEL.

RESULTS

We found that the genotype (TT) and minor allele (T) of IL1A gene as well as the genotype 1A3A of IL1RN were associated with an increased risk of getting Trypanosoma brucei gambiense and develop HAT when all data were analysed together and also when stratified by the three major ethno-linguistic groups, 2 pooled ethno-linguistic subgroups and 11 ethno-linguistic subgroups.

CONCLUSION

This study revealed that one SNP rs1800794 of IL1A and one VNTR rs2234663 of IL1RN were associated with the increased risk to be infected by Trypanosoma brucei gambiense and develop sleeping sickness in southern Cameroon. The minor allele T and the genotype TT of SNP rs1800794 in IL1A as well as the genotype 1A3A of IL1RN rs2234663 VNTR seem to increase the risk of getting Trypanosoma brucei gambiense infections and develop sleeping sickness in southern Cameroon.

Haptoglobin Genotypes in Nasopharyngeal Carcinoma

Aim

Haptoglobin polymorphisms are associated with different cancers; however, the occurrence of nasopharyngeal carcinoma (NPC) in relation to haptoglobin polymorphisms has not been reported. In this study, the distribution of haptoglobin genotypes among patients with NPC was investigated and the prognostic significance of haptoglobin genotypes was further analyzed.

Material and methods

Haptoglobin genotypes were analyzed using polymerase chain reaction and electrophoresis. The genotypes were determined in the sera of 49 NPC patients and in 134 controls.

Results

The haptoglobin genotypes of patients with NPC were as follows: Hp 1–1, 2%; Hp 2–1, 39%; Hp 2–2, 59%. The frequency of the Hp 2–2 genotype was much higher in NPC patients than in control individuals (p=0.044). Furthermore, NPC patients with the Hp 2–2 genotype had advanced T stages (p=0.001) and larger primary tumor volumes (p=0.035) than those with Hp 2–1 or 1–1.

Conclusion

An increased frequency of the Hp 2–2 genotype was associated with NPC. The Hp 2 allele was also overexpressed in NPC patients. NPC patients with the Hp 2–2 genotype had advanced T stage and a larger primary tumor volume. Hp 2–2 may be a negative prognostic factor in NPC.

Haptoglobin

Haptoglobin (Hp) is an abundant human plasma protein that tightly captures hemoglobin (Hb) during hemolysis. The Hb-Hp complex formation reduces the oxidative properties of heme/Hb and promotes recognition by the macrophage scavenger receptor CD163. This leads to Hb-Hp breakdown and heme catabolism by heme oxygenase and biliverdin reductase. Gene duplications of a part of or the entire Hp gene in the primate evolution have led to variant Hp gene products that collectively may be designated "the haptoglobins (Hps)" as they all bind Hb. These variant products include the human-specific multimeric Hp phenotypes in individuals, which are hetero- or homozygous for an Hp² gene allele. The Hp-related protein (Hpr) is another Hp duplication product in humans and other primates. Alternative functions of the variant Hps are indicated by numerous reports on association between Hp phenotypes and disease as well as the elucidation of a specific role of Hpr in the innate immune defense. Recent Advances: Recent functional and structural information on Hp and receptor systems for Hb removal now provides insight on how Hp carries out essential functions such as the Hb detoxification/removal, and how Hpr, by acting as an Hp-lookalike, can sneak a lethal toxin into trypanosome parasites that cause mammalian sleeping sickness. Critical Issues and Future Directions: The new structural insight may facilitate ongoing attempts of developing Hp derivatives for prevention of Hb toxicity in hemolytic diseases such as sickle cell disease and other hemoglobinopathies. Furthermore, the new structural knowledge may help identifying yet unknown functions based on other disease-relevant biological interactions involving Hps. Antioxid. Redox Signal. 26, 814-831.

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

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

Haptoglobin expression in endometrioid adenocarcinoma of the uterus

OBJECTIVE

Elevated serum haptoglobin (Hp) concentrations have been reported in patients with malignant diseases. We have shown that Hp is produced by and localizes only in the stroma and not the epithelium of endometriotic lesions, which share many characteristics of carcinoma. Furthermore, Hp mRNA and protein are found exclusively in the stroma of eutopic endometrium from women with endometriosis and not those without endometriosis. We hypothesized that characteristic patterns of Hp gene expression and protein localization in endometrioid adenocarcinoma of the uterus may provide insight into the clinical utility of Hp as a tumor marker or alternative therapeutic approach.

METHODS

Biopsies of endometrioid adenocarcinoma tumors of the uterus and their adjacent nonaffected endometrium were collected. Normal endometrium was collected from healthy women. Haptoglobin messenger RNA (mRNA) levels were quantified by quantitative polymerase chain reaction (Q-PCR). Haptoglobin protein cell-specific localization was identified by immunohistochemistry.

RESULTS

Haptoglobin mRNA levels were significantly greater (P < .005) in endometrioid adenocarcinoma and adjacent nonaffected endometrial tissues than normal endometrium. No correlation was found between Hp levels and cancer stage (P = .673) or grade (P = .739). Haptoglobin protein localized in both stromal and glandular epithelial cells of endometrioid adenocarcinoma and their adjacent nonaffected tissue but not in control endometrium.

CONCLUSIONS

Our results have identified, for the first time, unique patterns of Hp mRNA expression and protein localization in the stromal and glandular epithelial cells of endometrioid adenocarcinoma of the uterus. We propose that this unique pattern of endometrioid adenocarcinoma Hp expression may be developed as a novel diagnostic marker. Modulation of Hp, with its immunomodulatory and angiogenic properties, may generate novel methods of prevention or treatment for endometrial cancer.

Haptoglobin: a review of the major allele frequencies worldwide and their association with diseases

Haptoglobin (Hp) is a plasma alpha(2)-glycoprotein which binds free haemoglobin, thus preventing oxidative damage. The complex is rapidly removed from the circulation by a specific receptor (CD163) found on macrophages. Three major subtypes, Hp1-1, Hp2-1 and Hp2-2 are the product of two closely related genes HP(1) and HP(2). The frequency of the HP(1) and HP(2) genes varies worldwide depending on racial origin: the HP(1)frequency varying from about 0.07 in parts of India to over 0.7 in parts of West Africa and South America. Both HP(1) and HP(2) have been linked to susceptibility to various diseases. Such associations may be explained by functional differences between the subtypes in the binding of Hb and its rate of clearance from the plasma. However, there are also corresponding negative reports for disease associations. The conflicting evidence on disease association and the lack of association between disease and particular populations, despite the wide range of HP(1) and HP(2) gene frequencies across the world, may indicate that any associations are marginal.

Plasma proteomic analysis of pancreatic cancer by 2-dimensional gel electrophoresis

OBJECTIVE

Late diagnosis is the major reason for poor prognosis of pancreatic cancer (PC). Developing new biomarkers of early stage detection is critical.

METHODS

Proteomic analysis with 2-dimensional gel electrophoresis was used to identify differentially expressed proteins in plasma of PC patients. The 2-dimensional gel electrophoresis plasma protein profiles of 11 PC patients (preoperative and postoperative) were compared with those of 10 patients with chronic pancreatitis (CP) and 11 healthy controls.

RESULTS

Five proteins were found to be constantly changed. Haptoglobin (Hp) beta chain and leucine-rich alpha2 glycoprotein up-regulated slightly in PC plasma. Pancreatic cancer had a higher frequency of Hp2-2 phenotype but lacked Hp1-1 phenotype. Hemoglobin was increased significantly in plasma samples of PC and CP. Alpha1 antitrypsin gradually increased its expression level in healthy control, PC, and CP. Immunoglobin J chain was elevated in CP plasma samples. Haptoglobin, alpha1 antitrypsin, and leucine-rich alpha2-glycoprotein were all greatly elevated after tumor resection in PC patients.

CONCLUSIONS

Proteomic analysis can simultaneously detect changes of multiproteins in plasma of PC, but detected proteins are abundant and common plasma proteins and their diagnostic value may be limited.