Treatment of B. burgdorferi-infected B6 and B6 Rag1-/- mice with the BCL6 inhibitor FX1 resulted in greater rear ankle swelling, and increased severity of scored parameters of arthritis such as thickening of the tendon sheaths and hypertrophy/hyperplasia of synoviocytes (Fig 9B, 9I and 9J) to the level seen in B6.C3-Bbaa1 mice (Fig 6C). The gene discussed is RAG1; the disease is arthritic joint disease.