Arthritis, Rheumatoid* ; Glucose-6-Phosphate Isomerase

OBJECTIVE: Anti-glucose-6-phosphate isomerase (GPI) antibody (Ab) is known to be arthritogenic in K/BxN mice. Anti-GPI Ab is present in some patients with rheumatoid arthritis (RA), but their clinical manifestations are not clearly elucidated. The purpose of this study was to evaluate whether GPI serves as a specific autoantigen in patients with RA and to investigate the relationship of anti-GPI Ab with clinical parameters of RA. METHODS: Sera were collected from 54 patients with RA, 15 patients with osteoarthritis (OA) and 28 healthy controls. The samples were tested by enzyme-linked immunosorbent assay (ELISA) using human recombinant GPI as antigen. Patients with RA were classified according to rheumatoid factor (RF) positivity, the presence of RA shared epitope (SE), the presence of extraarticular manifestations, and evidence of bony erosive changes. RESULTS: Serum levels of anti-GPI Ab were higher in patients with RA than controls (1599.46+/-1022.48 versus 344.82+/-223.16 AU, p<0.001), and the levels of patients with OA were also higher than controls (1161.47+/-917.44 versus 344.82+/-223.16 AU, p<0.01). In RA, there were no significant difference in anti-GPI Ab levels according to RF positivity, the presence of RA SE, the presence of extraarticular manifestations, and evidence of bony erosive changes. CONCLUSION: Our results suggest that anti-GPI Ab may not be RA specific Ab and not related to the severity of RA.
Animals ; Arthritis, Rheumatoid* ; Autoantibodies* ; Enzyme-Linked Immunosorbent Assay ; Glucose-6-Phosphate Isomerase* ; Glucose-6-Phosphate* ; Humans ; Mice ; Osteoarthritis ; Rheumatoid Factor

OBJECTIVE: Autoantibody against glucose-6-phosphate isomerase (GPI) has been shown to be present in both the serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA). The purpose of this study was to evaluate whether GPI serves as a specific autoantigen in the SF of patients with RA and to investigate the relationship of anti-GPI antibody with clinical parameters of RA. METHODS: SF was collected from 34 patients with RA and 34 patients with osteoarthritis (OA). The samples were tested by enzyme-linked immunosorbent assay (ELISA) using human recombinant GPI as antigen. Patients with RA were classified according to rheumatoid factor (RF) positivity, the presence of RA shared epitope, the presence of extraarticular manifestations, and evidence of bony erosive changes. RESUTLS: SF levels of anti-GPI antibody were higher in patients with RA than in patients with OA (631.12+/-534.02 AU versus 112.38+/-90.45 AU, p<0.001). In RA, there was no significant difference in SF anti-GPI antibody levels according to RF positivity, the presence of extraarticular manifestations, and evidence of bony erosive changes. CONCLUSION: Autoantibodies to GPI in SF have more related with patients with RA compared with those with OA. In patients with RA, autoantibodies to GPI in SF are not associated with the poor prognostic factors and disease activity of RA.
Arthritis, Rheumatoid* ; Autoantibodies* ; Enzyme-Linked Immunosorbent Assay ; Glucose-6-Phosphate Isomerase* ; Glucose-6-Phosphate* ; Humans ; Osteoarthritis ; Rheumatoid Factor ; Synovial Fluid*

In order to evaluate the diagnostic accuracy of glucose-6-phosphate isomerase in patients with rheumatoid arthritis, retrieval was performed using the data bases of Medline, Embase, Cochrane library, Cmcc and Cbmdisc (1990 to 2007). We included the articles which reported the studies of GPI measured by enzyme-linked immunosorbent assay in the diagnosis of RA patients. Then we reviewed 15 article and used RevMan Software for analysis; the heterogeneity among the articles was determined to be high (chi2 = 191.65, P < 0.00001). When we analyzed the 5 articles wherein serum was used as the standard, we noticed homogeneity (chi2 = 6.97, P = 0.14). The summary sensitivity was 25%; the summary specificity was 80%; the area under the curve was 0.6279. Our study demonstrated that GPI exhibited high specificity and low sensitivity in diagnosing RA cases. We suggest that GPI be used in conjunction with some assay or other that is characterized by high sensitivity.
Arthritis, Rheumatoid ; blood ; diagnosis ; Enzyme-Linked Immunosorbent Assay ; Female ; Glucose-6-Phosphate Isomerase ; blood ; Humans ; Male ; ROC Curve ; Sensitivity and Specificity

Protozoan viruses may influence the function and pathogenicity of the protozoa. Trichomonas vaginalis is a parasitic protozoan that could contain a double stranded RNA (dsRNA) virus, T. vaginalis virus (TVV). However, there are few reports on the properties of the virus. To further determine variations in protein expression of T. vaginalis, we detected 2 strains of T. vaginalis; the virus-infected (V⁺) and uninfected (V⁻) isolates to examine differentially expressed proteins upon TVV infection. Using a stable isotope N-terminal labeling strategy (iTRAQ) on soluble fractions to analyze proteomes, we identified 293 proteins, of which 50 were altered in V⁺ compared with V⁻ isolates. The results showed that the expression of 29 proteins was increased, and 21 proteins decreased in V⁺ isolates. These differentially expressed proteins can be classified into 4 categories: ribosomal proteins, metabolic enzymes, heat shock proteins, and putative uncharacterized proteins. Quantitative PCR was used to detect 4 metabolic processes proteins: glycogen phosphorylase, malate dehydrogenase, triosephosphate isomerase, and glucose-6-phosphate isomerase, which were differentially expressed in V⁺ and V⁻ isolates. Our findings suggest that mRNA levels of these genes were consistent with protein expression levels. This study was the first which analyzed protein expression variations upon TVV infection. These observations will provide a basis for future studies concerning the possible roles of these proteins in host-parasite interactions.
Glucose-6-Phosphate Isomerase ; Glycogen Phosphorylase ; Heat-Shock Proteins ; Host-Parasite Interactions ; Malate Dehydrogenase ; Metabolism ; Polymerase Chain Reaction ; Proteome ; Reticuloendotheliosis virus ; Ribosomal Proteins ; RNA, Double-Stranded ; RNA, Messenger ; Trichomonas vaginalis* ; Trichomonas* ; Triose-Phosphate Isomerase ; Virulence

In industrial fermentation of amino acids the cells are often forced to synthesize the biochemicals excessive of their physiological needs. The knowledge of metabolic networks and their regulation relevant usually come from biochemical research, especially from enzymology, not from engineering study. To enrich the knowledge of metabolic sub-network of L-valine syntheses for higher production of L-valine, Corynebacterium glutamicum AS1.495 and its genetic derivatives AA361, AAT231, AATV341 were used for metabolic flux analysis. AS1.495 is a leucine auxotrophic (Leu-), and the three derivatives carry additional mutations. AA361 contains D-aspartic acid-beta-hydroxamate supersensitive marker (Leu-, L-AAHss), AAT231 (Leu-, L-AAHss, 2-TAr) is D-aspartic acid-beta-hydroxamate supersensitive and 2-thiazole alanine resistant, and AAT341 (Leu-, L-AAHss, 2-TAr, Vd-) is a D-aspartic acid-beta-hydroxamate supersensitive, 2-thiazole alanine resistant and valine-decompose-ability imperfect (Vd-). The concentrations of extra-cellular metabolites were determined under sub-steady-state of the batch culture. The metabolic flux distribution maps of the four strains were obtained, compared and analyzed. Our analysis showed that the flux ratio of EMP and HMP from the glucose-6-phosphate had increased from 0.205 in the parental strain AS1.495 to 0.321 in the multiple-mutation strain AATV341; the flux ratio of L-valine synthesis branch and the rest branches from the pyruvate node increased from 0.188 in AS1.495 to 3.29 in AATV341; the flux of lactic acid synthesis branch decreased from 11.1 in AS1.495 to 1.16 in AATV341; the flux of L-valine synthesis branch increased from 5.37 in AS1.495 to 37.3 in AATV341; and the productivity of L-valine correspondently increased from 4 g/L in AS1.495 to 24.5 g/L in AATV341. These results indicate that the introduction of analog supersensitive marker L-AAH55 and/or analog resistant marker 2-TAr skew the metabolic flux towards the formation of L-valine. This study revealed the usefulness of the metabolic flux analysis as a tool for verification of existing production strains. The analysis may play an important role in helping us b to rationally re-design metabolism for further improvement of fermentation process.
Corynebacterium glutamicum ; classification ; genetics ; metabolism ; Fermentation ; Glucose-6-Phosphate Isomerase ; metabolism ; Industrial Microbiology ; methods ; Mutation ; Pyruvic Acid ; metabolism ; Valine ; analysis ; biosynthesis

After renal injury, selective damage occurs in the proximal tubules as a result of inhibition of glycolysis. The molecular mechanism of damage is not known. Poly(ADP-ribose) polymerase (PARP) activation plays a critical role of proximal tubular cell death in several renal disorders. Here, we studied the role of PARP on glycolytic flux in pig kidney proximal tubule epithelial LLC-PK1 cells using XFp extracellular flux analysis. Poly(ADP-ribosyl)ation by PARP activation was increased approximately 2-fold by incubation of the cells in 10 mM glucose for 30 minutes, but treatment with the PARP inhibitor 3-aminobenzamide (3-AB) does-dependently prevented the glucose-induced PARP activation (approximately 14.4% decrease in 0.1 mM 3-AB-treated group and 36.7% decrease in 1 mM 3-AB-treated group). Treatment with 1 mM 3-AB significantly enhanced the glucose-mediated increase in the extracellular acidification rate (61.1±4.3 mpH/min vs. 126.8±6.2 mpH/min or approximately 2-fold) compared with treatment with vehicle, indicating that PARP inhibition increases only glycolytic activity during glycolytic flux including basal glycolysis, glycolytic activity, and glycolytic capacity in kidney proximal tubule epithelial cells. Glucose increased the activities of glycolytic enzymes including hexokinase, phosphoglucose isomerase, phosphofructokinase-1, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase in LLC-PK1 cells. Furthermore, PARP inhibition selectively augmented the activities of hexokinase (approximately 1.4-fold over vehicle group), phosphofructokinase-1 (approximately 1.6-fold over vehicle group), and glyceraldehyde-3-phosphate dehydrogenase (approximately 2.2-fold over vehicle group). In conclusion, these data suggest that PARP activation may regulate glycolytic activity via poly(ADP-ribosyl)ation of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase in kidney proximal tubule epithelial cells.
Animals ; Cell Death ; Epithelial Cells* ; Glucose ; Glucose-6-Phosphate Isomerase ; Glycolysis ; Hexokinase ; Kidney* ; LLC-PK1 Cells ; Oxidoreductases ; Phosphofructokinase-1 ; Phosphopyruvate Hydratase ; Poly Adenosine Diphosphate Ribose* ; Poly(ADP-ribose) Polymerases* ; Pyruvate Kinase ; Swine

We have used a surface plasmon resonance biosensor (SPR, BIACORE 2000) to detect antibodies against glucose 6-phosphate isomerase (GPI) in synovial fluids of rheumatoid arthritis (RA) and osteoarthritis (OA). Recombinant human GPI proteins fused with or without NusA were expressed in E. coli, purified to homogeneity and immobilized in flow cells of CM5 sensor chips. The flow cells immobilized with NusA protein or bovine serum albumin were used to monitor non-specific binding. Synovial fluid samples from RA patients showed a significantly higher level of binding to recombinant GPI proteins than samples from OA patients. Proteins which bound to the recombinant GPI proteins were confirmed to be immunoglobulin through the administration of anti-human immunoglobulin. NusA fusion protein was excellent for this assay because of a low background binding activity in the SPR analysis and its advantage of increased solubility in recombinant protein production. These results suggested a useful utilization of recombinant NusA-GPI fusion protein for the detection of autoantibodies against GPI in RA patients.
Aged ; Antibodies/*immunology ; Arthritis, Rheumatoid/*immunology ; Female ; Glucose-6-Phosphate Isomerase/genetics/*immunology/metabolism ; Human ; Male ; Middle Aged ; Osteoarthritis/immunology ; Peptide Elongation Factors/genetics/metabolism ; Recombinant Fusion Proteins/genetics/metabolism ; Surface Plasmon Resonance ; Synovial Fluid/*immunology ; Transcription Factors/genetics/metabolism

Molecular mimicry is an attractive mechanism for triggering autoimmunity. In this review, we explore the potential role of evolutionary conserved bacterial proteins in the production of autoantibodies with focus on granulomatosis with polyangiitis (GPA) and rheumatoid arthritis (RA). Seven autoantigens characterized in GPA and RA were BLASTed against a bacterial protein database. Of the seven autoantigens, proteinase 3, type II collagen, binding immunoglobulin protein, glucose-6-phosphate isomerase, alpha-enolase, and heterogeneous nuclear ribonuclear protein have well-conserved bacterial orthologs. Importantly, those bacterial orthologs are also found in human-associated bacteria. The wide distribution of the highly conserved stress proteins or enzymes among the members of the normal flora and common infectious microorganisms raises a new question on how cross-reactive autoantibodies are not produced during the immune response to these bacteria in most healthy people. Understanding the mechanisms that deselect auto-reactive B cell clones during the germinal center reaction to homologous foreign antigens may provide a novel strategy to treat autoimmune diseases.
Arthritis, Rheumatoid ; Autoantibodies ; Autoantigens ; Autoimmune Diseases* ; Autoimmunity ; Bacteria ; Bacterial Infections* ; Bacterial Proteins ; Clone Cells ; Collagen Type II ; Germinal Center ; Glucose-6-Phosphate Isomerase ; Heat-Shock Proteins ; Immunoglobulins ; Molecular Mimicry* ; Myeloblastin ; Phosphopyruvate Hydratase

OBJECTIVETo systematically evaluate the values of 4 serum markers in the diagnosis of rheumatoid arthritis (RA).

METHODSSerum samples were obtained from 278 RA patients and 510 control subjects and the levels of rheumatoid factor (RF), anticyclic citrullinated peptide antibody (CCP), antikeratin antibody (AKA), and glucose-6-phosphate isomerase (GPI) were detected using immune turbidimetry, ELISA, indirect immunofluorescence, and ELISA, respectively. The values of these 4 serum markers and their combinations in RA diagnosis were systemically assessed.

RESULTSIn RA diagnosis using one serum marker, two markers, and three or four markers, RF, RF+CCP, RF+CCP+GPI, respectively, had the highest sensitivity; CCP, CCP+AKA, and RF+CCP+AKA+GPI, respectively, had the highest specificity; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive predictive value; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the highest negative predictive value; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive likely ratio; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the lowest negative likely ratio.

CONCLUSIONCCP, RF+CCP, and RF+CCP+GPI are the most ideal for RA diagnosis using one, two, and three or more markers, respectively. CCP is the essential marker for RA diagnosis, and a combined detection of the serum makers can significantly improve the diagnostic accuracy.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Arthritis, Rheumatoid ; blood ; diagnosis ; Autoantibodies ; blood ; Biomarkers ; blood ; Case-Control Studies ; Citrulline ; immunology ; Female ; Glucose-6-Phosphate Isomerase ; blood ; Humans ; Keratins ; immunology ; Male ; Middle Aged ; Rheumatoid Factor ; blood ; Young Adult