Natalizumab inhibits the expression of human endogenous retroviruses of the W family in multiple sclerosis patients: a longitudinal cohort study.

BACKGROUND

Several viruses were reported as co-factors triggering the pathogenesis of multiple sclerosis (MS), including the endogenous retroviruses of the HERV-W family, that were also proposed as biomarkers of disease progression and therapy outcome.

OBJECTIVE

The objective of this article is to clarify whether in MS patients treatment with natalizumab has effects on MSRV/syncytin-1/HERV-W expression and the possible relationship with disease outcome.

METHODS

Peripheral blood mononuclear cells were collected from 22 patients with relapsing-remitting disease, at entry and after three, six and 12 months of treatment with natalizumab. The cell subpopulations and the expression of MSRVenv/syncytin-1/HERV-Wenv were analyzed by flow cytometry and by discriminatory env-specific RT-PCR assays.

RESULTS

By flow cytometry the relative amounts of T, NK and monocyte subpopulations were shown to remain fairly constant. A relative increase of B lymphocytes was observed at three to six months (p = 0.033). The MSRVenv and syncitin-1 transcripts were reduced at six to 12 months of therapy (p = 0.0001). Accordingly, at month 12, the plasma-membrane levels of the HERV-Wenv protein were reduced (p = 0.0001). B cells, NK and monocytes but not T cells expressed the HERV-Wenv protein. None of the patients relapsed during therapy.

CONCLUSION

Effective therapy with natalizumab downregulates MSRV/syncytin-1/HERV-W expression.