CXCL13 and Lyme disease: Previous studies have shown that prolonged Bb infection can cause inflammation and increased production of CXCL13 in the cerebrospinal fluid (CSF), leading to lymphocytic pleocytosis.[11, 14, 87, 88, 89] Reduction of inflammation leads to a decrease in focal neurodegeneration, suggesting indirect cytotoxicity as a possible model for the pathogenesis of neuroborreliosis.[89] Although neuroinflammation caused by Bb infection is sufficient to cause neurological symptoms, it is unable to induce Bb extravasation across the BBB.