Severe rheumatoid arthritis prohibits the pregnancy-induced decrease in alpha3-fucosylation of alpha1-acid glycoprotein.

Patients suffering from rheumatoid arthritis (RA) may experience a temporary reduction of disease symptoms during pregnancy. As indicated by the occurrence of RA-disease symptoms during pregnancy, three categories of patients were defined, namely, remission, relapse and unchanged. In all three categories changes in the plasma level and glycosylation of alpha1-acid glycoprotein (AGP) were determined longitudinally in comparison to those occurring in pregnancy of healthy women. In healthy pregnancy, we observed: (i) a peak in the plasma concentration at week 18 and a minimum at week 30; (ii) a continuous increase in the degree of branching of the glycans during the entire pregnancy period, and (iii) a decrease in the degree of alpha3-fucosylation of AGP-glycans with a minimum occurring at week 25. Comparable pregnancy-induced changes in glycosylation were found for two other acute-phase proteins alpha1-protease inhibitor (PI) and alpha1-antichymotrypsin (ACT). Increased oestrogen levels, known to occur during pregnancy, may be one of the factors that induce these changes, because the increased branching and decreased alpha3-fucosylation is in agreement with our earlier findings regarding an involvement of this hormone in the regulation of acute phase protein glycosylation in oestrogen-treated males as well as females. In all three clinical categories in RA, pregnancy also induced a continuous increase in the degree of branching of the glycans of AGP. However, similar changes in concentration and fucosylation were only found during remission of the disease symptoms. In the relapse and unchanged categories in RA, the degree of fucosylation and the plasma concentration of AGP remained constant throughout pregnancy. This indicates a relationship between changes in alpha3-fucosylation of AGP and RA disease activity.

Do synovial fluid acute phase proteins from patients with rheumatoid arthritis originate from serum?

This study was performed in order to gain insight into the occurrence, glycosylation and the possible origin of the acute-phase proteins alpha1-acid glycoprotein (AGP) and alpha1-protease inhibitor (PI) in sera and synovial fluid from patients with rheumatoid arthritis (RA). Therefore paired sera and synovial fluid samples from patients with RA, and paired synovial fluid samples from right and left knees of patients with varying degrees of arthritis were studied. Crossed affinity immunoelectrophoresis (CAIE) was used with concanavalin A and Aleuria aurantia lectin for the detection of the degree of branching and fucosylation, respectively, and the monoclonal CSLEX-1 for the detection of Sialyl Lewis(X) (SLe(X)) groups on AGP. For PI, not only CAIE, but also high-pressure-anion-exchange chromatography with pulsed amperometric detection was used to study the glycosylation. It was established that the concentrations of AGP and PI were increased in the serum of RA patients compared to normal healthy controls, but that the concentration of both proteins, as well as albumin, was significantly lower in synovial fluid than in serum. Furthermore, the type of glycosylation of both AGP and PI found in RA was significantly different from that found in normals, with increased fucosylation, but there were no major differences in the degree of branching of AGP- or PI-glycans in RA, compared to normals. No differences in glycosylation could be established between serum and synovial fluid in RA. For PI an increased fucosylation was found, both in serum and synovial fluid, using both methods of detection, and it could be established that only the alpha1-->3- and not the alpha1-->6-fucosylation of PI was affected by RA. The increased fucosylation of AGP resulted in an increased expression of SLe(X) on AGP-glycans. Since the alpha1-->3-fucosylation of AGP was significantly increased in both serum and synovial fluid from RA patients, and this correlated with systemic but not with local disease parameters, it can be suggested that acute phase proteins in synovial fluid are most probably of hepatic origin.

Glycosylation of alpha 1-acid glycoprotein in septic shock: changes in degree of branching and in expression of sialyl Lewis(x) groups.

The occurrence of differences in acute-phase response, with respect to concentration and glycosylation of alpha 1-acid glycoprotein (AGP) was studied in the sera of patients, surviving or not from septic shock. Crossed affino-immunoelectrophoresis was used with concanavalin A and Aleuria aurantia lectin for the detection of the degree of branching and fucosylation, respectively, and the monoclonal CSLEX-1 for the detection of sialyl Lewisx (SLeX) groups on AGP. Septic shock apparently induced an acute-phase response as indicated by the increased serum levels and changed glycosylation of AGP. In the survivor group a transient increase in diantennary glycan content was accompanied by a gradually increasing fucosylation and SLeX expression, comparable to those observed in the early phase of an acute-inflammatory response. Remarkably, in the non-survivor group a modest increase in diantennary glycan content was accompanied by a strong elevation of the fucosylation of AGP and the expression of SLeX groups on AGP, typical for the late phase of an acute-phase response. Our results suggest that these changes in glycosylation of AGP can have a prognostic value for the outcome of septic shock.

Elevated serum level and altered glycosylation of alpha 1-acid glycoprotein in hyperimmunoglobulinemia D and periodic fever syndrome: evidence for persistent inflammation.

Crossed affinoimmunoelectrophoresis using concanavalin A and Aleuria aurantia lectin as diantennary glycan- and fucose-specific affinocomponents, respectively, was applied to study changes in the concentration and glycosylation of the acute phase protein alpha 1-acid glycoprotein (AGP) in sera obtained from patients with hyperimmunoglobulinemia D and periodic fever syndrome. Increases in concentration of AGP compared to control values were found not only during attacks, but also during remissions. Compared to healthy controls, the presence of diantennary glycan-containing glycoforms of AGP also increased during febrile attacks, while no changes were found during remissions. A continuous high degree of alpha 1-->3 fucosylation was accompanied by a continuous high expression of sialyl Lewisx on AGP. Despite the clinical picture of recurrent febrile attacks with asymptomatic intervals, these studies indicate that hyperimmunoglobulinemia D should be considered a condition of persistent inflammation.

Effects of low dose methotrexate therapy on the concentration and the glycosylation of alpha 1-acid glycoprotein in the serum of patients with rheumatoid arthritis: a longitudinal study.

OBJECTIVE: The concentration, and the degree of fucosylation and sialylation of human serum alpha 1-acid glycoprotein (AGP) were investigated for changes during 24-week low-dose methotrexate (MTX) or azathioprine treatment (AZA) in rheumatoid arthritis (RA) patients. METHODS: Serum samples from a longitudinal study were analyzed by crossed affinoimmunoelectrophoresis with the fucose specific Aleuria aurantia lectin. RESULTS: In general, the degree of fucosylation of AGP in RA sera was higher than in control sera, but decreased markedly under the influence of successful therapy with MTX. Concomitantly, the degree of sialylation of AGP increased and the concentration decreased. For alpha 1-protease inhibitor and haptoglobin similar results were obtained. In AZA responders less pronounced changes than in MTX responders were observed. In MTX nonresponders no significant trends were found. As in control sera, large interindividual differences in the AGP values were found. CONCLUSION: The heavy fucosylation of AGP in RA sera reflects disease activity rather than an intrinsic characteristic of people genetically predisposed to RA, since it was found to decrease upon disease improvement. The differences in effects on AGP of MTX and AZA suggest either a gradual difference in a similar mechanism of action, or a different mechanism of action of the drugs. Fucosylated and sialylated AGP could be important in the etiopathogenesis of RA, because these molecules potentially can bind to adhesion receptors (selectins), which could prevent the extravasation of leukocytes into inflamed joints.