Rheumatoid arthritis (RA) is a widely prevalent (1-3%) chronic systemic disease thought to have an autoimmune component; both humoral and cellular mechanisms have been implicated. Primary osteoarthritis (OA) is considered to be distinct from rheumatoid arthritis, and here damage is thought to be secondary to cartilage degeneration. In rheumatoid arthritis, immune complexes are present that consist exclusively of immunoglobulin, implying that this is both the 'antibody' (rheumatoid factor [RF]) and the 'antigen' (most commonly IgG). Autoantigenic reactivity has been localized to the constant-region (C gamma 2) domains of IgG. There is no evidence for a polypeptide determinant but carbohydrate changes have been reported. We have therefore conducted a study, simultaneously in Oxford and Tokyo, to compare in detail the N-glycosylation pattern of serum IgG (Fig. 1) isolated from normal individuals and from patients with either primary osteoarthritis or rheumatoid arthritis. The results, which required an evaluation of the primary sequences of approximately 1,400 oligosaccharides from 46 IgG samples, indicate that: (1) IgG isolated from normal individuals, patients with RA and patients with OA contains different distributions of asparagine-linked bi-antennary complex-type oligosaccharide structures, (2) in neither disease is the IgG associated with novel oligosaccharide structures, but the observed differences are due to changes in the relative extent of galactosylation compared with normal individuals. This change results in a 'shift' in the population of IgG molecules towards those carrying complex oligosaccharides, one or both of whose arms terminate in N-acetylglucosamine. These two arthritides may therefore be glycosylation diseases, reflecting changes in the intracellular processing, or post-secretory degradation of N-linked oligosaccharides.

The occurrence of N-linked oligosaccharides lacking galactose is significantly higher than normal in serum IgG of patients with rheumatoid arthritis (RA) in whom rheumatoid factor (RF), an autoantibody against autologous IgG, has been detected. In the present study, IgGs with and without RF activity (IgGRF and non-RF IgG, respectively) were prepared from sera of RA patients, and their oligosaccharide structures were characterized in order to investigate the relationship between RF activity and glycosylation. Three IgGRF fractions and a non-RF IgG fraction were obtained based on their ability to bind to an IgG-Sepharose column. The specific RF activity, as measured by immunoassays, was highest in the IgGRF fraction, which bound most avidly to the IgG-Sepharose. When the oligosaccharides were released by hydrazinolysis, and analyzed by MALDI-TOF mass spectrometry and HPLC, in combination with sequential exoglycosidase treatment, all the IgG samples were found to contain a series of biantennary complex-type oligosaccharides. The incidence of galactose-free oligosaccharides was significantly higher in both IgGRFs and non-RF IgG from RA patients compared with IgG from healthy individuals. In all IgGRFs, the levels of sialylation and galactosylation were lower than those in non-RF IgG from RA patients; the sialylation of non-RF IgG was the same as that of IgG from healthy individuals. In addition, the decreases in galactosylation and sialylation of oligosaccharides in IgGRF correlated well with the increase in RF activity. These findings could contribute to our understanding of the mechanisms of IgG-IgG complex formation and the pathogenicity of these complexes in RA patients.

The sugar chains of IgG samples purified from sera of patients with rheumatoid arthritis (RA) contain many fewer galactose residues than those from sera of healthy individuals. Enzymatic studies revealed that the low galactose content in the IgGs of RA patients results from the reduced activity in the B cells of a galactosyltransferase (EC 2.4.1.90), which preferentially transfers galactose to asialo-agalacto-IgG. Asialo-agalacto-transferrin and asialo-ovine submaxillary mucin were also galactosylated by detergent-activated human B cell homogenates. However, no difference in the enzymatic activities toward these two acceptors was detected between the B cells from RA patients and from non-RA patients and healthy individuals. Enzyme kinetic studies revealed that an affinity of the galactosyltransferase in the B cells from RA patients was lowered for UDP-Gal but not for asialo-agalacto-IgG, while the affinities for UDP-Gal and asialo-agalacto-transferrin of the galactosyltransferase were not changed between the B cells from RA patients and from non-RA patients and healthy individuals in accordance with their enzyme activities. The results indicated that the reduced galactosyltransferase activity toward asialo-agalacto-IgG in the B cells from RA patients can be ascribed to the lowered affinity for UDP-Gal.

IntroductionThe objective was to investigate associations between the HLA-A gene and Behcet's disease (BD) and its clinical manifestations.MethodsGenotyping for the HLA-A locus was performed using the polymerase chain reaction-Luminex typing method in 223 BD patients and 1,398 healthy controls.ResultsThe phenotypic frequencies of HLA-A*02:07 (odds ratio (OR) = 2.03, P = 0.002), A*26:01 (OR = 1.85, P = 0.008), and A*30:04 (OR = 2.51, P = 0.006) tended to be higher in BD patients than in normal controls, but the frequency of A*33:03 (OR = 0.59, P = 0.003) tended to be lower in BD patients. A meta-analysis adopting our and the Japanese data confirmed the associations of HLA-A*02:07, A*26:01, and A*33:03 with BD. Furthermore, the frequencies of the HLA-A*02:07, A*26:01, and A*30:04 were significantly higher in patients with skin lesions (OR = 2.37, P < 0.0005, Pc < 0.012) and arthritis (OR = 2.32, P = 0.002, Pc = 0.048), with uveitis (OR = 3.01, P < 0.0005, Pc < 0.012), and with vascular lesions (OR = 9.80, P < 0.0005, Pc <0.012) and a positive pathergy test (OR = 4.10, P = 0.002, Pc = 0.048), respectively, than in controls. In HLA-B*51 non-carriers, these associations were also significant, being much stronger between HLA-A*26:01 and uveitis (OR = 4.19, P < 0.0005, Pc < 0.012) and between HLA-A*30:04 and vascular lesions (OR = 13.97, P < 0.00005, Pc < 0.0012). In addition, HLA-A*30:04 was associated with genital ulcers in HLA-B*51 non-carriers (OR = 3.89, P = 0.002, Pc = 0.048).ConclusionsHLA-A*02:07, A*26:01, and A*30:04 were associated with increased risk for BD, while HLA-A*33:03 with decreased risk. HLA-A*02:07, A*26:01, and A*30:04 were associated with skin lesions and arthritis, with uveitis, and with vascular lesions, genital ulcers, and a positive pathergy test, respectively.

We have conducted systematic studies to measure telomere length in human tissues of all types. Progressive telomere shortening with aging was studied in specimens of normal pancreas obtained at autopsy from 69 subjects aged 0 to 100 yr, and age-related shortening of telomere length at a rate of 36 base pairs (bp) per year was detected. Mean telomere length (+/-SD) was 13.9+/-1.4 kilobase pairs (kbp) in 16 neonates, as opposed to 8.4 kbp in 2 centenarians. Mean telomere length (+/-SD) in four age groups, 0-24, 25-49, 50-74, and 75-100 yr, was 13.5+/-1.5, 12.3+/-0.7, 11.3+/-2.5, and 10.7+/-1.8, respectively.

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In order to elucidate the relationship between glycosylation of IgG and aging, oligosaccharide structures of human IgG purified from sera of men and women aged 18 to 73 years were investigated. Oligosaccharides were liberated quantitatively from IgG by hydrazinolysis followed by N-acetylation and were tagged with p-aminobenzoic acid ethyl ester. The oligosaccharide structures were then analyzed by HPLC in conjunction with sequential exoglycosidase digestion. All IgG samples were shown to contain a series of biantennary complex type oligosaccharides which consisted of +/-Galbeta1-4GlcNAcbeta1-2Manalpha1-6(+/-GlcNAcbeta 1-4)(+/-Galbeta1-4GlcNAcbeta1-2Man(alpha)1-3)Man(beta)1-+ ++4GlcNAcbeta1-4(+/- Fucalpha1-6)GlcNAc and their mono- and disialo glycoforms in different ratios. In female IgG samples only, the incidence of non-galactosylated oligosaccharides with non-reducing terminal GlcNAc residues increased with aging (r>0.8), whereas that of digalactosylated oligosaccharides decreased (r<-0.8). A weaker correlation was observed between aging and the incidence of neutral and monosialo oligosaccharides in female IgG (r=0.461 and r= -0.538, respectively) and between aging and the incidence of oligosaccharides with a bisecting GlcNAc in both male and female IgG samples (r=0.566 and r=0.440, respectively). In addition, a significant change with aging in the galactosylation of IgG oligosaccharides was observed in females in their thirties, fifties, and sixties (p<0.02, p<0.01, and p<0.04, respectively). These findings may contribute to our understanding of autoimmune diseases such as rheumatoid arthritis in which glycosylation is involved.

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