Distribution of haptoglobin phenotypes in a Korean population, using the semi-automated PhastSystem

Development of a sensitive and reliable ELISA kit of urinary haptoglobin to predict progress of diabetic kidney disease

AIMS

Urinary haptoglobin (UHp) is a potential biomarker for predicting progress of diabetic kidney disease (DKD) to remedy the defects of currently used urinary albumin. The clinical application of UHp is however limited, owing to the extremely low level in urine. This study aims to establish an enzyme-linked immunosorbent assay (ELISA) kit specifically for detecting UHp in urine samples of patients with diabetes and DKD.

MATERIALS AND METHODS

Supersensitive human haptoglobin antibodies were generated for ELISA kit development, and the sensitivity, specificity and reproducibility of the kit was evaluated. This kit was used to detect UHp in 246 healthy individuals and 83 patients with type 2 diabetes (T2D). The interference of blood haptoglobin genotypes on UHp measurement was analysed.

RESULTS

The UHp ELISA kit had a standard curve ranging from 5 to 200 ng/ml. The low detection limit was 0.11 ng/ml. The coefficients of variation of intra- and interassay were 5.5% and 8.3%, respectively. The kit showed high accuracy with 100.9% mean recovery rate, and linearity R²  = 0.999. The reference range of UHp was 0-42.3 ng/g creatinine (0-Q95) in the healthy individuals. UHp level was significantly higher in T2D patients with microalbuminuria and macroalbuminuria than that in T2D without microalbuminuria (p < 0.01). The UHp concentration measured by this kit was not affected by haptoglobin genotypes.

CONCLUSIONS

We have generated an ELISA kit to accurately detect UHp levels, which is potentially a reliable biomarker of DKD.

Phenotypic polymorphism of haptoglobin: a novel risk factor for the development of infection in liver cirrhosis

The α-chain alleles 1 and 2 of haptoglobin (Hp) molecule account for three phenotypes, which have biologically important differences in their antioxidant, scavenging, and immunomodulatory properties and may thereby influence the course of inflammatory diseases. A follow-up observational study was conducted to assess the association between haptoglobin phenotype and the development of clinically significant bacterial infections in patients with liver cirrhosis. Sera of 336 patients with liver cirrhosis of various etiologies and 384 healthy subjects were investigated. Haptoglobin phenotypes were determined by gel electrophoresis and assigned corresponding genotype. Haptoglobin phenotype distributions of patients and controls was similar (Hp1-1: 10.7% vs 11.5%, Hp2-1: 47.9% vs 46.1% and Hp2-2: 41.4% vs 42.4%). The probability of clinically significant bacterial infections was calculated for each haptoglobin phenotype (Hp1-1: 50.0%, Hp2-1: 36.0% and Hp2-2: 26.6%, p = 0.039). In a logistic regression analysis, Hp1-1 phenotype (p = 0.015, OR: 2.74, 95% CI: 1.22-6.13), Child-Pugh stage (p = 0.038, OR: 1.40, 95% CI: 1.02-1.91) and presence of co-morbidities (p < 0.001, OR: 2.64, 95% CI: 1.63-4.27) were independently associated with infections. In a Cox regression analysis, Hp1-1 phenotype (p = 0.014), Child-Pugh stage C (p < 0.001), and presence of co-morbidities (p = 0.004) were associated with time to first infectious episode. Phenotypic haptoglobin polymorphism was independent predictor for risk and time to first clinically significant bacterial infectious episode.

Polymorphism of haptoglobin in patients with premature rupture of membrane

PURPOSE

To investigate whether allelic polymorphism of haptoglobin (Hp) is associated with premature rupture of membrane (PROM), the Hp phenotypes of pregnant women with PROM were analyzed.

PATIENTS AND METHODS

The Hp phenotypes of 221 pregnant Korean women (187 control and 34 PROM patients) were determined by benzidine/hydrogen peroxide staining, following native polyacrylamide gel electrophoresis of hemoglobin-mixed sera. The Hp allele frequencies were calculated from the data of Hp phenotypes, and overall association with PROM was evaluated using Pearson Chi-Square test.

RESULTS

The polymorphic distribution of the patients cohort who underwent a normal delivery (control group) was similar to that of healthy Koreans. In contrast, however, patients with PROM showed significantly higher occurrence of the Hp 1-1 phenotype than control group (23.5% vs 8.0%). Hp 2-2 phenotype was lower in PROM cohort (38.2%) than in the control group (48.7%). The Hp(1) allele frequency in PROM group was significantly higher than that in the control group (0.426 vs 0.297, p = 0.034) with odds ratio of 1.762 (95% CI: 1.038 - 2.991).

CONCLUSION

These findings suggest that pregnant Korean women who possess Hp(1) allele (expressed as Hp 1-1 phenotype) have higher incidence of PROM than women with Hp(2) allele (expressed as Hp 2-2 phenotype). This is the first study that evaluated the significance of Hp polymorphism with respect to the development of PROM.

Possible pathogenetic role of vascular, immunological and genetic factors in certain gastoenterological disorders

A coeliakia és a gyulladásos bélbetegségek (IBD) változatos klinikai megjelenését befolyásoló faktorok jelentős része ismeretlen. A haptoglobin (Hp) molekula három fő fenotípusa eltérő antioxidáns, scavenger és immunmoduláns tulajdonsággal rendelkezik. Nagyszámú coeliakiás és IBD-betegben vizsgáltuk a Hp-polimorfizmus megoszlását és a betegség klinikai megjelenésével való lehetséges kapcsolatát. A Hp-fenotípusokat szérumból nátrium-dodecil-szulfát poliakrilamid gélelektroforézis (SDS-PAGE) és immunblottal határoztuk meg, amely egyértelműen azonosítja a genotípust is. Coeliakiában a kontrollpopulációhoz képest a Hp 2-1 fenotípus előfordulása szignifikánsan gyakoribb volt, míg a Hp 2-2 ritkább. A Hp 2-2 esetén azonban a súlyos, malabszorpcióval jelentkező klinikai betegség kockázata magasabb volt, míg a silent betegségé jóval alacsonyabb. Crohn-betegekben (CD) a Hp 2-1 fenotípus esetén a gyulladásos betegségforma előfordulása szignifikánsan gyakoribb volt a másik két Hp-fenotípushoz viszonyítva, míg a stenotizáló formáé ritkább. Primer szklerotizáló cholangitisben a Hp 1-1 fenotípus nem fordult elő. A Hp szerepét az immunreakciókban betöltött modulálóhatásai és eltérő térszerkezete magyarázhatja. A mikrobiális és autoantigének elleni szerológiai válasz segítséget jelenthet az IBD differenciáldiagnosztikájában, és összefüggést mutat a betegség fenotípusával. Nagyszámú IBD-betegben vizsgáltuk az anti- Saccharomyces cerevisiae (ASCA) és külső membránporin elleni antitestek (anti-Omp) enzimmel kapcsolt immunoszorbens assay (ELISA), illetőleg az atípusos perinukleáris antineutrophil citoplazmatikus antitest (P-ANCA) (indirekt immunfluoreszcencia) előfordulási gyakoriságát és a betegség fenotípusával való lehetséges kapcsolatukat. A szerológiai markerek hasznosnak bizonyultak az IBD differenciáldiagnosztikájában. CD-ben az ASCA- és az anti-Omp-pozitivitás a vékonybél-érintettség és a nem gyulladásos betegségforma szempontjából logisztikus regressziós analízisben is független rizikófaktornak bizonyult, míg a műtéti kockázat tekintetében nem. A nem gyulladásos típusú vékonybél-CD és az antimikrobiális antitest pozitivitásainak száma, illetőleg az antitesttiterek között szintén pozitív korrelációt találtunk (szerológiai-dózis hatás). Továbbá ASCA és az anti-Omp-antitestek jelenléte kapcsolatot mutatott a nucleotid oligomerizációs domén (NOD2/CARD15) genotípussal, és előfordulási gyakoriságuk szignifikánsan nőtt a NOD2/CARD15 mutációk számának növekedésével, ami gén-dózis hatásra utal és alátámasztja a mikrobákkal szembeni megváltozott érzékelés szerepét a CD patogenezisében.

Proteotyping of human haptoglobin by MALDI-TOF profiling: Phenotype distribution in a population of toxic oil syndrome patients

Toxic oil syndrome (TOS) is a disease that appeared in Spain in 1981 as a consequence of the ingestion of an aniline-adulterated oil illegally marketed as edible. TOS affected more than 20 000 people and produced over 400 deaths in the first 18 months after the outbreak. There is evidence that genetic factors could play a role in the susceptibility of individuals towards the disease. Recently, we suggested that haptoglobin (Hp) polymorphism could also play a role in TOS. To provide a rapid method for high-throughput Hp phenotyping, we developed a two-step MALDI-TOF procedure that allows specific identification of the three common Hp alpha chains. Resolution of the homologous alpha-1s and alpha-1f chains, which have a mass difference of only 0.043 Da, is obtained after guanidination of the protein with O-methylisourea. We applied this procedure to the study of the distribution of the Hp alleles HP(1s), HP(1f), HP(2) in a control versus a TOS-affected population, both originally exposed to the toxic oil. The MALDI-TOF proteotyping method was validated by a parallel analysis of the serum samples by 2-DE. Data obtained from 54 TOS cases and 48 control individuals indicate significant differences in the distribution of Hp phenotypes in the two populations.

Haptoglobin polymorphisms are associated with Crohn's disease, disease behavior, and extraintestinal manifestations in Hungarian patients

Functional differences and association with inflammatory disorders were found relating to three major haptoglobin (Hp) phenotypes. Our aim was to investigate Hp polymorphisms in Hungarian patients with Crohn's disease (CD). Four hundred sixty-eight CD patients and 384 healthy controls were examined. Hp phenotypes were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting of the sera. The frequency of the Hp(1) allele was significantly higher in CD (0.395; OR, 1.24; 95% CI, 1.02-1.52; P=0.03) compared to controls (0.345). In CD, Hp phenotype was associated with disease behavior (OR [Hp(2-1) vs other], 2.06; 95% CI, 1.29-3.28 for inflammatory behavior). Furthermore, an increased frequency of primary sclerosing cholangitis was observed in the Hp 2-2 compared to the Hp 1-1 phenotype (6.5% vs. 0.0%; P=0.039). We conclude that the Hp polymorphism is associated with CD, inflammatory disease behavior, and primary sclerosing cholangitis in Hungarian patients. Further studies are required to evaluate the significance of Hp polymorphisms in other populations from geographically diverse regions.

Haptoglobin genotypic distribution (including Hp0 allele) and associated serum haptoglobin concentrations in Koreans

BACKGROUND

Haptoglobin polymorphism is associated with the prevalence of infections, autoimmune diseases, cardiovascular diseases, and other disorders. Congenital haptoglobin deficiency is associated with anaphylactic transfusion reactions in anhaptoglobinaemic patients with antihaptoglobin antibody.

AIMS

To investigate haptoglobin genotypic distribution (including the Hp(0) allele) and associated serum haptoglobin concentrations in Koreans.

METHODS

Five hundred and nine healthy Korean adults were randomly selected. Two methods were used: haptoglobin genotyping based on a polymerase chain reaction (PCR) system that exploited the structural difference of the Hp(1) and Hp(2 )alleles, and another PCR method that detected haptoglobin gene deletion by amplification of the junctional region of the Hp(0) allele. Serum haptoglobin concentrations were measured by nephelometry.

RESULTS

The haptoglobin genotypes of 509 subjects were as follows: Hp(1)Hp(1), 7.1%; Hp(2)Hp(1), 37.7%; Hp(2)Hp(2), 49.3%; Hp(0)Hp(1), 2.2%; Hp(0)Hp(2), 3.5%; Hp(0)Hp(0), 0.2%. The gene frequency of Hp(0) in Koreans was calculated to be 0.031. Significant differences were seen among the concentrations of each haptoglobin genotype (Kruskal-Wallis test). Hp(0)Hp(2), but not Hp(0)Hp(1), was associated with hypohaptoglobinaemia.

CONCLUSIONS

PCR methods for differentiating between haptoglobin genotypes, including the Hp(0) allele, may be useful in a broad spectrum of basic studies and clinical examinations.

Haptoglobin phenotype and gestational diabetes

OBJECTIVE

Haptoglobin (Hp), an Hb-binding plasma protein, exists in two major allelic variants. Hp1 has higher Hb binding and antioxidant capacity compared with Hp2. Individuals with Hp1 exhibit a lower incidence of angiopathies. Gestational diabetes mellitus (GDM) is an early manifestation of type 2 diabetes in pregnant women. It is usually confined to the time of gestation, but carries an increased risk to develop type 2 diabetes later in life.

RESEARCH DESIGN AND METHODS

From consecutive Caucasian pregnant women (n = 250) referred for oral glucose tolerance testing, the Hp phenotype was determined. Significance of distribution and odds ratios (ORs) associated with Hp phenotype were calculated for women with GDM (n = 110) and women with normal glucose tolerance (n = 140).

RESULTS

-Frequency of GDM in Hp phenotype classes increased with the number of Hp2 alleles (P < 0.001). ORs for GDM in women heterozygous and homozygous for Hp2 were 2.7 (95% CI 1.06-6.84) and 4.2 (1.67-10.55), respectively.

CONCLUSIONS

Hp phenotype is an apparent risk factor for the development of GDM in our study population. This might be due to the low antioxidative potential of Hp2 compared with Hp1.