Dennis C. W. Poland

Plasma concentration of C-reactive protein is increased in type I diabetic patients without clinical macroangiopathy and correlates with markers of endothelial dysfunction: evidence for chronic inflammation.

Summary Moderately increased plasma concentrations of C-reactive protein are associated with an increased risk of cardiovascular disease. C-reactive protein, its relation to a low degree of inflammatory activation and its association with activation of the endothelium have not been systematically investigated in Type I (insulin-dependent) diabetes mellitus. C-reactive protein concentrations were measured in 40 non-smoking patients with Type I diabetes without symptoms of macrovascular disease and in healthy control subjects, and in a second group of Type I diabetic patients (n = 60) with normo- (n = 20), micro- (n = 20) or macroalbuminuria (n = 20). Differences in glycosylation of α1-acid glycoprotein were assayed by crossed affinity immunoelectrophoresis. Activation of the endothelium was measured with plasma concentrations of endothelial cell markers. The median plasma concentration of C-reactive protein was higher in Type I diabetic patients compared with healthy control subjects [1.20 (0.06–21.64) vs 0.51 (0.04–9.44) mg/l; p < 0.02]. The Type I diabetic subjects had a significantly increased relative amount of fucosylated α1-acid glycoprotein (79 ± 12 % vs 69 ± 14 % in the healthy control subjects; p < 0.005), indicating a chronic hepatic inflammatory response. In the Type I diabetic group, log(C-reactive protein) correlated significantly with von Willebrand factor (r = 0.439, p < 0.005) and vascular cell adhesion molecule-1 (r = 0.384, p < 0.02), but not with sE-selectin (r = 0.008, p = 0.96). In the second group of Type I diabetic patients, increased urinary albumin excretion was associated with a significant increase of von Willebrand factor (p < 0.0005) and C-reactive protein (p = 0.003), which were strongly correlated (r = 0.53, p < 0.0005). Plasma concentrations of C-reactive protein were higher in Type I diabetic patients without (clinical) macroangiopathy than in control subjects, probably due to a chronic hepatic inflammatory response. The correlation of C-reactive protein with markers of endothelial dysfunction suggests a relation between activation of the endothelium and chronic inflammation. [Diabetologia (1999) 42: 351–357]

Increased α3-fucosylation of α1-acid glycoprotein in Type I diabetic patients is related to vascular function

Diabetic mellitus is attended by the development of endothelial dysfunction which is suggested to be accompanied with a chronic low-degree of inflammation. During a chronic hepatic inflammatory response, specific changes in glycosylation of the acute phase protein α1-acid glycoprotein (AGP) can be detected. In this report we studied the changes in glycosylation of AGP in more detail and evaluated the relation between a change in glycosylation of AGP and urinary albumin secretion in Type I diabetic patients. The glycosylation of AGP, studied by crossed affinity immunoelectrophoresis (CAIE) and high pH anion exchange chromatography with pulse amperometric detection (HPAEC-PAD), showed an increase in α3-fucosylation. Staining with an antibody against sialyl Lewisx (sLex) implied that part of the α3-fucosylation was present in a sLex-conformation. In the group of Type I diabetic patients with increased urinary albumin excretion, a significant increase in α3-fucosylation of AGP (p[emsp4 ]<[emsp4 ]0.0005) could be detected. Therefore, the increased α3-fucosylation of AGP can be used as an additional marker for the development of vascular complications in Type I diabetic patients.

Activated human PMN synthesize and release a strongly fucosylated glycoform of α1-acid glycoprotein, which is transiently deposited in human myocardial infarction

α1‐Acid glycoprotein (AGP) is a major acute‐phase protein present in human plasma as well as in polymorphonuclear leukocytes (PMN). In this report, we show that PMN synthesize a specific glycoform of AGP, which is stored in the specific and azurophilic granules. Activation of PMN results in the rapid release of soluble AGP. PMN AGP exhibits a substantially higher apparent molecular weight than plasma AGP (50–60 kD vs. 40–43 kD), owing to the presence of strongly fucosylated and sialylated polylactosamine units on its five N‐linked glycans. PMN AGP is also released in vivo from activated PMN, as appeared from studies using well‐characterized myocard slices of patients that had died within 2 weeks after an acute myocardial infarction. AGP was found deposited transiently on damaged cardiomyocytes in areas with infiltrating PMN only. It is interesting that this was inversely related to the deposition of activated complement C3. Strongly fucosylated and sialylated AGP glycoforms have the ability to bind to E‐selectin and to inhibit complement activation. We suggest that AGP glycoforms in PMN provide an endogenous feedback‐inhibitory response to excessive inflammation.

Alterations of branching and differential expression of sialic acid on alpha-1-acid glycoprotein in human seminal plasma

BACKGROUND The degree of branching and types of fucosylation of glycans on alpha(1)-acid glycoprotein (AGP) have been found to be associated with alpha(1)-acid glycoprotein concentrations in human seminal plasma. The glycosylation pattern of alpha(1)-acid glycoprotein in seminal plasma obtained from men living in infertile couples can undergo alterations in relation to sperm analysis and/or alpha(1)-acid glycoprotein concentrations. METHODS The glycosylation of alpha(1)-acid glycoprotein was studied upon the reactivity with specific lectins by crossed affinity immunoelectrophoresis (concanavalin A), and by glycoprotein lectin immunosorbent assay (Maackia amurensis and Sambucus nigra lectins), as well as high pH anion-exchange chromatography with pulsed amperometric detection. RESULTS Nonsignificant differences in alpha(1)-acid glycoprotein glycan branching and degree of its sialylation were observed among the AGP derived from seminal plasmas in relation to spermiogram and sperm morphology. However, significant concentration-dependent differences were found in extent of branching and type of sialylation. CONCLUSIONS The presence in seminal plasma of high concentrations of aberrantly glycosylated AGP molecules might be indicative for a chronic inflammatory condition in the reproductive tract, and can be used as additional tool to subdivide the seminal plasmas of men living in infertile couples.

Increased α3‐fucosylation of α1‐acid glycoprotein in patients with congenital disorder of glycosylation type IA (CDG‐Ia)

Increased fucosylation of the type (sialyl) Lewisx was detected on the acute‐phase plasma protein α1‐acid glycoprotein (AGP) in patients with the congenital disorder of glycosylation type IA. This is remarkable, because in these patients the biosynthesis of guanosine 5′‐diphosphate (GDP)‐D‐mannose is strongly decreased, and GDP‐D‐mannose is the direct precursor for GDP‐L‐fucose, the substrate for fucosyltransferases. The concomitantly occurring increased branching of the glycans of AGP and the increased fucosyltransferase activity in plasma suggest that a chronic hepatic inflammatory reaction has induced the increase in fucosylation.

Dental caries related to plasma IgG and alpha1-acid glycoprotein

This study was aimed at determining whether dental caries is associated with induction of the systemic immune system or cytokine response. For this purpose, 85 children from Den Pasar, Bali, Indonesia, aged 6–7 years, were examined clinically and blood plasma was obtained via finger puncture. The concentrations of the acute-phase protein α1-acid glycoprotein (AGP), total IgG and the specific IgG and IgM immunoglobulins against Streptococcus mutans were determined. Immunoelectrophoresis was used for the determination of the AGP concentration and ELISA for IgG and IgM detection. The mean dmft of the whole group was 8.8 ± 2.9, the mean number of infected pulps was 3.9 ± 2.2 and the mean number of abscesses was 0.5 ± 0.8. The plasma concentration of AGP ranged between 0.13 and 1.6 mg/ml serum (mean 0.86 ± 0.26 mg/ml). Stepwise regression analysis revealed that the concentration of IgG against S. mutans (log-transformed) was significantly correlated with dmft (adjusted r2 = 0.083, standardized β coefficient = 0.31, p = 0.008). When the concentration AGP was included in the model the correlation improved significantly (for IgG: adjusted r2 = 0.157, standardised β coefficient = 0.36, p = 0.002; for AGP: β coefficient = –0.30, p = 0.009). The results suggest a relationship between caries and systemic parameters of inflammation. On the basis of this, severe caries might have consequences on the general health of the subject.

Specific glycosylation of α1-acid glycoprotein characterises patients with familial Mediterranean fever and obligatory carriers of MEFV

BACKGROUND Familial Mediterranean fever (FMF) is a periodic febrile disorder, characterised by fever and serositis. The acute phase response during attacks of FMF results from the release of cytokines, which in turn induce increased expression and changed glycosylation of acute phase proteins. A recent study indicated that attacks in FMF are accompanied by a rise of plasma concentrations of serum amyloid A (SAA) and C reactive protein (CRP), which remain significantly raised during remission relative to healthy controls. Another study suggested that obligatory heterozygotes also display an inflammatory acute phase response. OBJECTIVE To determine the state of inflammation in homozygotic and heterozygotic MEFV genotypes. METHODS CRP and SAA were studied by enzyme linked immunosorbent assay (ELISA). The glycosylation of the acute phase protein, α1-acid glycoprotein (AGP), was visualised with crossed affinoimmunoelectrophoresis with concanavalin A as diantennary glycan-specific component and Aleuria aurantia lectin as fucose-specific affinity component. RESULTS FMF attacks were associated with an increase (p<0.05) in the serum inflammation parameters CRP, SAA, and AGP. The glycosylation of AGP showed an increase (p<0.05) in fucosylated AGP glycoforms, whereas the branching of the glycans remained unaffected. The glycosylation of AGP in the MEFV carrier group, compared with that in a healthy control group, was characterised by a significant increase (p<0.05) in branching of the glycans, whereas the fucosylation remained unaffected. CONCLUSION The findings suggest an FMF-specific release of cytokines, resulting in a different glycosylation of AGP between a homozygotic and heterozygotic MEFV genotype.

Molecular Analysis of Plasma α1,3-Fucosyltransferase Deficiency and Development of the Methods for Its Genotyping

Four patients with mental illness were found to be deficient in plasma α1,3-fucosyltransferase for the first time in Japan [Exp Clin Immunogenet 1999;16:125–130]. Complete sequencing of FUT6 genes in these individuals revealed the presence of two point mutations, i.e., G739 to A (Glu→247 to Lys) and C945 to A (Tyr→315 to stop). In addition to two reported alleles having G739 to A (pf1) and G739 to A and C945 to A (pf3), a new mutated allele having C945 to A (pf2) was found to be present and all the individuals who lack α1,3-fucosyltransferase activity in plasma were found to possess pf genes homozygously (pf/pf). In order to detect such lethal mutations in FUT6 genes easily, PCR-RFLP methods have also been developed and applied for the screening of FUT6 deficiency in a large number of samples which resulted in the demonstration of three additional FUT6-deficient individuals. The absence of α1,3-fucosylated molecules on α1-acid glycoprotein in plasma from all the 7 individuals was confirmed to result from the plasma α1,3-fucosyltransferase deficiency.

Anti-Inflammatory Properties of Specific Glycoforms of Human α1-Acid Glycoprotein

Upon damage to mammalian tissues, such as destruction due to infection, inflammation, neoplasia, burn wounds, and mechanical trauma, a complex series of events must follow in order to prevent further damage, and to restore homeostasis. The sum of these events is known as inflammation, of which the acute-phase response constitutes the set of immediate and early events. Local acute-phase reactions include aggregation of platelets, dilation and subsequent leakage of blood vessels, release of protease inhibitors, and release of cytokines and chemoattractant molecules. The latter attract leukocytes, which in turn, together with the fibroblasts and endothelial cells at the site of inflammation will produce more cytokines, like TNF-α, IL-lβ and IL-6.

Distinct glycoforms of human α1-acid glycoprotein have comparable synthesis rates: a [13C]valine-labelling study in healthy humans

Various α1-acid glycoprotein (AGP) glycoforms are present in plasma differing in extent of branching and/or fucosylation of their 5 N-linked glycans, as well as in concentration. It is assumed that hepatic synthesis determines the relative occurrence of the AGP-glycoforms in plasma, but experimental evidence is lacking. In this study, we have investigated the contribution of fractional synthesis rates to the plasma concentration of AGP-glycoforms that differed in relative occurrence in healthy human plasma. During a [13C]valine infusion, AGP was isolated from the plasma of healthy volunteers. Four AGP-glycoforms, differing strongly in plasma concentration were obtained by sequential affinity chromatography over concanavalin-A- and Aleuria aurantia-agarose columns. The incorporation of the [13C]valine tracer into the AGP-glycoforms was measured by gas chromatography combustion isotope ratio mass spectrometry. The mean fractional synthesis rates of the four AGP-glycoforms did not differ significantly between each other as well between individuals. The results indicated a renewal of about 15%/day of the plasma pools of each of the AGP-glycoforms. This is in support to the assumption that the differences in plasma concentration of the AGP-glycoforms are a reflection of the state of the hepatic glycosylation process. Published in 2004.