MMP9 and tropical spastic paraparesis: MMP expression dysregulation is conspicuous due to observations demonstrating higher expression of MMP gelatinases (MMP-2 and MMP-9) in blood and CSF of HAM/TSP patients and downregulation of Tissue inhibitor of metalloproteinases 1 (TIMP-1) in CD4+ T-cells (Umehara et al., 1998; Mozhgani et al., 2018).