Isoforskolin downregulates proinflammatory responses induced by Borrelia burgdorferi basic membrane protein A.

The plant Coleus forskohlii is distributed primarily in India, Thailand, China, Egypt and Brazil and has a history of use in the treatment of multiple diseases. Isoforskolin (ISOF) is the principle active component of C. forskohlii native to China and has previously been studied for its biological effects. The aim of the present study was to evaluate the effect of ISOF on the proinflammatory responses induced by recombinant Borrelia burgdorferi basic membrane protein A (rBmpA). In in vitro experiments, the proinflammatory effects of rBmpA and the anti-inflammatory function of ISOF were evaluated in murine macrophages, human macrophages and dendritic cells by detecting the transcription and expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6. In in vivo experiments, mean arthritis index and X-ray and histopathological examinations were used to verify the role of ISOF in experimental Lyme arthritis in mice. The results indicated that rBmpA, which induced the transcription and expression of TNF-α and IL-6, activated proinflammatory responses in murine macrophages, human macrophages and dendritic cells. In turn, ISOF downregulated the transcription and expression of TNF-α and IL-6 induced by rBmpA. Additionally, the in vivo experiments demonstrated that ISOF could also inhibit the symptoms of experimental Lyme arthritis. These results suggest that ISOF may have a potential application as an anti-inflammatory agent for the treatment of Lyme arthritis.