Studies on swine and canine serum haptoglobins

Low levels of haptoglobin and putative amino acid sequence in Taiwanese Lanyu miniature pigs

Porcine haptoglobin (Hp) is an acute phase protein. Its plasma level increases significantly during inflammation and infection. One of the main functions of Hp is to bind free hemoglobin (Hb) and inhibit its oxidative activity. In the present report, we studied the Hp phenotype of Taiwanese Lanyu miniature pigs (TLY minipigs; n=43) and found their Hp structure to be a homodimer (beta-alpha-alpha-beta) similar to human Hp 1-1. Interestingly, Western blot and high performance liquid chromatographic (HPLC) analysis showed that 25% of the TLY minipigs possessed low or no plasma Hp level (<0.05 mg/ml). The Hp cDNA of these TLY minipigs was then cloned, and the translated amino acid sequence was analyzed. No sequences were found to be deficient; they showed a 99.7% identity with domestic pigs (NP_999165). The mean overall Hp level of the TLY minipigs (0.21 +/- 0.25 mg/ml; n=43) determined by enzyme-linked immunosorbent assay (ELISA) was markedly lower than that of domestic pigs (0.78 +/- 0.45 mg/ml; p<0.001), while 25% of the TLY minipigs had an Hp level that was extremely low (<0.05 mg/ml). In addition, the initial recovery rate (first 40 min) in the circulation of infused fluorescein isothiocyanate (FITC)-Hb was significantly higher in the TLY minipigs with extremely low Hp levels than those with high levels. This data suggests that the low concentration of Hp-Hb complex is responsible for the higher recovery rate of Hb in the circulation. TLY minipigs have been used as an experimental model for cardiovascular diseases; whether they can be used as a model for inflammatory diseases, with Hp as a marker, remains a topic of interest. However, since the Hp level varies significantly among individual TLY minipigs, it is necessary to prescreen the Hp levels of the animals to minimize variation in the experimental baseline. The present study may provide a reference value for future use of the TLY minipig as an animal model for inflammation-associated diseases.

Validation of a commercially available human immunoturbidimetric assay for haptoglobin determination in canine serum samples

Haptoglobin is a positive acute-phase protein with a valuable role as a marker of inflammation in both human and veterinary medicine. The aim of this study was to validate a commercially available immunoturbidimetric method designed for human haptoglobin determination (Izasa SA, Barcelona, Spain) for its use in canine samples. Cross-reactivity between anti-human haptoglobin antiserum and canine haptoglobin was found when agarose gel immunodiffusion and ELISA tests were performed. The use of canine pooled serum with haptoglobin concentration of 6.3 g/L as standard provided higher analytical range than commercially available standards. Intra-assay and inter-assay coefficients of variation were 2.49% and 4.60%, respectively. A linear regression model between immunoturbidimetric results and a previously validated spectrophotometric method (Tridelta Development Limited, Ireland) yielded a slope at 95% confidence interval of 0.94 (0.86, 1.02) and y-intercept at 95% confidence interval of 0.11 (-0.59, 0.82). No significant differences were produced by anticoagulants, lipaemia and bilirubinaemia, although haemolysis significantly decreased haptoglobin. A significant increase of haptoglobin concentration was detected in inflammatory conditions such as pyometra and leishmaniasis, in neoplastic conditions, and after glucocorticoid administration. Canine serum haptoglobin concentration can be reliably measured using the commercially available Izasa immunoturbidimetric method developed for human haptoglobin determination. This method is precise and accurate, provides a wider analytical range than previous reported methods, and can be easily automated and used for routine haptoglobin determination in canine samples.

Toxicities of hemoglobin solutions: in search of in-vitro and in-vivo model systems

Several hemoglobin-based oxygen carriers (HBOCs) have been developed with a rationale focused on exploiting one or more physicochemical properties (e.g., oxygen affinity, molecular weight, viscosity, and colloid osmotic pressure) resulting from the chemical or recombinant modification of hemoglobin (Hb). Several chemically modified Hbs have reached late stages of clinical evaluation in the United States and Canada. These Hbs, in general, demonstrated mixed preclinical safety and efficacy, and reasonable safety in Phase I trials. However, as clinical development shifted into later stages, an undesirable safety and efficacy profile became clear in patient populations studied, and as a result some products were withdrawn from further clinical pursuit. Several questions still remain unanswered regarding the safety of Hb products for their proposed clinical indication(s). For example, 1) were preclinical studies predictive of clinical outcome? And, 2) were the most appropriate preclinical studies performed to predict clinical outcome? The primary objectives of this analysis are to explore prelinical safety issues associated with HBOCs and provide an overview of the in-vitro and in-vivo models employed. The methods for obtaining data to serve as a basis for discussion are compiled from a literature-based survey of safety and efficacy derived from biochemical, cellular, and whole animal assessment of HBOCs. Results from this overview of a vast body of published data may provide a means for identifying critical preclinical safety issues, which may ultimately lead to identification of potential limitations in the effective clinical use of certain HBOCs.

Validation of human haptoglobin immunoturbidimetric assay for detection of haptoglobin in equine and canine serum and plasma

The Incstar(R) SPQ II human haptoglobin (Hpt) (Incstar Corporation, Stillwater, MN) immunoturbidimetric assay was validated for the determination of serum and plasma Hpt concentrations in dogs and horses. The anti-human Hpt antiserum supplied with the assay, displayed monospecificity to both dog and horse serum Hpt by immunoelectrophoresis and Western blotting techniques. The automated immunoturbidimetric assay results correlated well with the cyanmethemoglobin binding assay (r=0.953 for canine serum and r=0.941 for equine serum), and had excellent precision at both high and low serum Hpt concentrations (within run and between run coefficients of variation near or less than 5%). The assay was linear in both species by serial dilution of pooled-high serum with pooled-low serum, saline and with Hpt-free serum. Interference from hemolysis (> 25 mg/dl hemoglobin) and lipemia greater than 100 mg/dl caused a false decrease and false increase respectively in Hpt yield with the immunoturbidimetric assay. The anti-Hpt antibody supplied with the assay kit, once diluted with polymer diluent and stored at 4 degrees C, was stable for up to 6 days and gave consistent results.

Disease-related variations of the glycosylation of haptoglobin in the dog

Haptoglobin phenotypes have been shown in human medicine to be related to the prevalence of various diseases. Furthermore, abnormal glycosylation of haptoglobin has been reported as a consequence of liver disease, cancer and immunological disorders in man. To our knowledge, similar findings have not, so far, been reported in canine disease. The present paper describes a method for investigation of canine haptoglobin phenotypes and of microheterogeneity caused by altered glycosylation. The method consisted of isoelectric focusing (IEF) of dog serum, followed by immunoblotting. The results indicated the existence of only one canine haptoglobin phenotype with a characteristic microheterogeneity pattern in healthy dogs. Changes in this pattern were found in serum from dogs with liver disease, predominantly chronic progressive hepatitis, and with different kinds of anaemia. Pretreatment of serum with neuraminidase or glycopeptidase F (PNGase F) resulted in identical IEF patterns of haptoglobin from healthy and diseased dogs. Moreover, a fucose-specific lectin was capable of binding to some of the abnormal haptoglobin fractions, mainly those found in association with anaemia. The changes described were interpreted as alterations of the carbohydrate content, with or without fucosylation, of some haptoglobin fractions.

The porcine acute phase response to infection with Actinobacillus pleuropneumoniae. Haptoglobin, C-reactive protein, major acute phase protein and serum amyloid A protein are sensitive indicators of infection

In an experimental infection model mimicking acute Actinobacillus pleuropneumoniae (Ap) infection in swine (Sus scrofa) by aerosol inoculation, the development of a number of typical clinical signs was accompanied by a prototypic acute phase reaction encompassing fever and an acute phase protein response peaking at around 2 days after infection. Haptoglobin, C-reactive protein (CRP), and major acute phase protein (MAP) responded with large increases in serum levels, preceding the development of specific antibodies by 4-5 days. Serum amyloid A protein (SAA) was also strongly induced. The increase, kinetics of induction and normalization were different between these proteins. It is concluded that experimental Ap-infection by the aerosol route induces a typical acute phase reaction in the pig, and that pig Hp, CRP, MAP, and SAA are major acute phase reactants. These findings indicate the possibility of using one or more of these reactants for the nonspecific surveillance of pig health status.

Biochemical variation of blood proteins in race hounds

In the present study biochemical polymorphisms were investigated in blood of different race hounds and compared to those of other dog breeds. Twenty-three proteins were separated electrophoretically in starch gel and polyacrylamide gel respectively. For 9 proteins genetic variants could be assured: postalbumin-1 (PA-1), postalbumin-3 (PA-3), transferrin (TRF), plasma esterase (ES), leucine arylaminopeptidase (LAP), haptoglobin (HP), glucose phosphate isomerase (GPI), superoxide dismutase (SOD), albumin (ALB). The already known HP polymorphism was analyzed and described in more detail. In addition, a sex independent variation was found for the GPD.

Bovine and canine acute phase proteins

Acute phase proteins are serum proteins which increase in concentration during the acute phase response to inflammation or infection. The response occurs in all animals, but in different species the response of individual proteins can be significantly different. Of the numerous acute phase proteins which have been identified in humans, a number have been examined in cattle and dogs but usually on an individual basis with little reference to their part in the acute phase response. Biochemical, physiological and clinical investigations into haptoglobin, fibrinogen, alpha 1-proteinase inhibitor, ceruloplasmin, seromucoid and C-reactive protein of cattle and dogs have therefore been reviewed with the emphasis on their role in this response to tissue damage.