Borrelia burgdorferi Peptidoglycan Shedding Drives Lyme Arthritis Save

Research published in PNAS has shown that long after active Lyme infection in the joint, a peptidoglycan (PG) of the the spirochete Borrelia burgdorferi can be found in the joints of those with late-stage Lyme disease.

The study identifies the B. burgdorferi peptidoglycan, a major component of the cell wall, as an immunogen likely to contribute to inflammation during infection and in cases of postinfectious Lyme arthritis.

A common late-stage complication of Lyme disease is oligoarticular arthritis, usually involving the knee and in a minority of patients chronic proliferative synovitis persists after antibiotic treatment.

They show that B. burgdorferi has a chemically atypical PG (PG^Bb) that is not recycled during cell-wall turnover. Instead, this pathogen sheds PG^Bb fragments into its environment during growth. Patients with LA mount a specific immunoglobulin G response against PG^Bb, which is significantly higher in the synovial fluid than in the serum of the same patient.

They examined synovial fluid from 34 patients with Lyme arthritis and found PG^Bb in 94% of synovial fluid samples, despite having received antibiotic treatment.

These same synovial fluid samples contain proinflammatory cytokines, similar to those produced by human peripheral blood mononuclear cells stimulated with PG^Bb.

Systemic administration of PG^Bbin BALB/c mice elicits acute arthritis.

Altogether, our study identifies PG^Bb as a likely contributor to inflammatory responses in Lyme arthritis patients. B. burgdorferi sheds immunogenic PG^Bb fragments that contribute to the immunopathogenesis of Lyme disease manifestations.