Immune Recognition of Citrullinated Proteoglycan Aggrecan Epitopes in Mice with Proteoglycan-Induced Arthritis and in Patients with Rheumatoid Arthritis
Fig 5
Anti-PG peptide antibodies in serum samples from mice with PGIA or GIA, or from naïve mice.
IgG antibodies reacting with Cit or R versions of 6 PG peptides were measured by ELISA using biotinylated Cit-R peptide pairs. Delta optical density at 450 nm (ΔOD 450 nm) was determined as described in the Methods. (A) Serum antibodies against the Cit versions of six PG peptides in mice with PGIA (red bars) or GIA (blue bars) or naïve mice (gray bars). Data are shown as the mean ΔOD 450 nm±SEM (PGIA n = 10 mice/peptide; GIA n = 3–5 mice/peptide; Naïve n = 3 mice/peptide). Inter-group comparisons were made using Kruskal-Wallis test followed by Dunn’s multiple comparison test (#p<0.05: PGIA vs naïve mice). (B) Cit:R ratios of peptide-specific serum antibodies from mice with PGIA or GIA and from naïve mice. Data are expressed as Cit:R ratios of ΔOD 450 nm (mean±SEM) of serum antibodies specific for the peptide pairs in the groups of mice described above. Inter-group comparisons were made as described for graph A above (#p<0.05: GIA vs naïve or PGIA vs GIA mice). A Cit:R ratio of 1.0 is indicated by a dotted line. None of the Cit:R ratios were significantly different from 1.0 as determined by Wilcoxon signed rank test.