Immunoglobulin G and A Antibody Responses toBacteroides forsythusandPrevotella intermediain Sera and Synovial Fluids of Arthritis Patients

Abstract

ABSTRACTThe objective of the present study was to investigate immunoglobulin G (IgG) and IgA antibody immune responses toPorphyromonas gingivalis,Prevotella intermedia,Bacteroides forsythus, andCandida albicansin the sera of patients with rheumatoid arthritis (RA), the synovial fluid (SF) of patients with RA (RA-SF samples), and the SF of patients without RA (non-RA-SF samples). An enzyme-linked immunosorbent assay was used to determine IgG and IgA antibody levels in 116 serum samples from patients with RA, 52 RA-SF samples, and 43 non-RA-SF samples; and these were compared with those in SF samples from 9 patients with osteoarthritis (OA-SF samples) and the blood from 100 donors (the control [CTR] group). Higher levels of IgG antibodies againstB. forsythus(P< 0.0001) andP. intermedia(P< 0.0001) were found in non-RA-SF samples than in OA-SF samples, and higher levels of IgG antibodies againstB. forsythus(P= 0.003) andP. intermedia(P= 0.024) were found in RA-SF samples than in OA-SF samples. Significantly higher levels of IgA antibodies againstB. forsythuswere demonstrated in both RA-SF and non-RA-SF samples than in OA-SF samples. When corrected for total Ig levels, levels of IgG antibody againstB. forsythuswere elevated in RA-SF and non-RA-SF samples compared to those in OA-SF samples. Lower levels of Ig antibodies againstB. forsythuswere found in the sera of patients with RA than in the plasma of the CTR group for both IgG (P= 0.003) and IgA (P< 0.0001). When corrected for total Ig levels, the levels of IgG and IgA antibodies againstB. forsythuswere still found to be lower in the sera from patients with RA than in the plasma of the CTR group (P< 0.0001). The levels of antibodies againstP. gingivalisandC. albicansin the sera and SF of RA and non-RA patients were comparable to those found in the respective controls. The levels of IgG and IgA antibodies againstB. forsythuswere elevated in SF from patients with RA and non-RA-SF samples compared to those in OA-SF samples. Significantly lower levels of IgG and IgA antibodies againstB. forsythuswere found in the sera of patients with RA than in the plasma of the CTR group. This indicates the presence of an active antibody response in synovial tissue and illustrates a potential connection between periodontal and joint diseases.