In Vitro Model of the Human Blood-Brain Barrier to Explore HTLV-1 Immunopathogenesis

Cellular components and inflammatory mediators involved in the transmigration of HTLV-1-infected cells across the blood-brain barrier (BBB) are not fully understood. This study proposes a BBB model to identify the immunological mechanisms associated with HTLV-1 pathogenesis. PBMCs from individuals with HTLV-1-associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) (n = 4) or HTLV-1-infected individuals without HAM/TSP (n = 4) were isolated. An indirect cell co-culture was performed between human brain microvascular endothelial (hBMEC) cells and neuroblastoma (SH-SY5Y) cells. PBMCs from healthy individuals (n = 4) were used as a negative control, and MT-2 cells were used as a positive control. Supernatants and cells were collected to quantify inflammatory cytokines and assess cell death after 24, 48, and 72 h. Multiple comparisons were performed using the Kruskal-Wallis test, followed by Fisher's LSD post hoc analysis. We observed that the production of cytokines IL-6, IL-8, IL-1β, TNF, IL-10, and IL-12p70, as well as the rate of neuronal death, was higher in co-cultures mimicking HAM/TSP carriers compared to HTLV-1-infected individuals without HAM/TSP and controls. Our results suggest that the HAM/TSP condition induces the release of IL-6, IL-8, IL-1β, TNF, IL-10, and IL-12p70, along with the infiltration of mononuclear cells, which may lead to neuronal death.