BDNF and tropical spastic paraparesis: In conclusion, VILIP-1, sRAGE, sTREM-1, sTREM-2, BDNF, β-NGF, VEGF, IL-6, TNF-α, IL-18, TGF-β1, and fractalkine/CX3CL1 were not associated with HTLV-1 PVL or the speed of HAM/TSP progression, which limits their use as biomarkers for HAM/TSP.