Increased osteopontin expression in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patient cells is associated with IL-17 expression

Abstract

Background: HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurological inflammatory disease associated with a predominant infiltration of CD4+ T lymphocytes, which are the main subset of HTLV-1-infected cells. It has been demonstrated that in cell line the viral Tax protein transcriptionnally regulate expression of osteopontin, an inflammatory cytokine associated with Th17-related pathologies.

Objectives: The aim of the study was to explore osteopontin expression in HTLV-1 asymptomatic carriers and in HAM/TSP patients and consequences on IL17 expression.

Study design: We quantified Tax, osteopontin, RORγ, IL17 and IL22 mRNA expressions in cells from 10 HAM/TSP patients, 6 asymptomatic HTLV-1 carriers (ASY) and 4 HTLV-1-negative healthy donors during ex vivo culture.

Results: We observed that the expression of osteopontin was higher in HAM/TSP patients and correlated with Tax expression levels. Positive regulation of RORγ, IL17 and IL22 were also observed during cell culture.

Conclusions: Our results propose a new mechanism which could contribute to HAM/TSP pathogenesis.

Keywords: HAM/TSP; HTLV-1; IL-17; Osteopontin.