Heightened Proinflammatory Glycosylation of Borrelia burgdorferi IgG Antibodies in Synovial Fluid in Patients With Antibiotic-Refractory Lyme Arthritis.

Objective: Terminal glycans on the Fc portion of IgG antibodies are critical for antibody-triggered, proinflammatory or antiinflammatory responses. We undertook this study to compare glycan profiles of total IgG1 and Borrelia burgdorferi (Bb)-specific IgG1 antibodies in patients with oral antibiotic-responsive or antibiotic-refractory Lyme arthritis (LA).

Methods: Following affinity-column processing, glycan profiles of IgG antibodies were determined in serum and synovial fluid (SF) samples of 21 LA patients using glycoblotting with hydrazide glycan enrichment and determination of glycan structure by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Correlations between glycan profiles and treatment outcomes were analyzed.

Results: Compared with patients with antibiotic-refractory LA, those with antibiotic-responsive LA had total and Bb-specific IgG1 antibody glycans with less intense inflammatory profiles, containing lower percentages of N-acetylglucosamine (GlcNAc) and bisecting GlcNAc and higher percentages of galactose and fucose. In contrast, patients with antibiotic-refractory LA prior to receiving IV antibiotic therapy had total IgG1 and Bb IgG1 antibodies with maximal, minimally opposed, proinflammatory glycan profiles, containing high percentages of GlcNAc and bisecting GlcNAc, intermediate percentages with galactose and fucose, and low percentages with N-acetylneuraminic acid (sialic acid). Patients with refractory LA who were first seen with synovitis after receiving IV antibiotic therapy still had Bb IgG1 antibodies with strongly inflammatory glycan profiles, but their inflammatory potential appeared to be waning.

Conclusion: Patients with oral antibiotic-responsive LA had Bb IgG1 antibodies with more balanced proinflammatory/antiinflammatory glycan profiles, whereas patients with antibiotic-refractory LA had Bb IgG1 antibodies with maximal, minimally opposed, proinflammatory glycan profiles. Among patients with antibiotic-refractory LA, antibodies with this unbalanced inflammatory glycan profile may have a role in sustaining maladaptive joint inflammation.