Vitamin D and HTLV Infection: A Systematic Review

Background: Vitamin D has been associated with the pathogenesis of infectious diseases. Objective: To perform a systematic review on the association of vitamin D and outcomes of HTLV (Human T-cell lymphotropic virus) infection. Methods: We searched PubMed, LILACs, Scielo, Embase and Cochrane Library for studies addressing vitamin D and HTLV infection. We included studies published in English since 1980. Studies associated with HIV, bone metabolism and not related to HTLV- associated myelopathy/ tropical spastic paraparesis (HAM/TSP) or adult T cell leukemia/lymphoma (ATL) were excluded. Results: Twenty-three studies were selected and sixteen studies were included in the review (eight experimental studies, three case reports, three cases series, one cross-sectional study and one review). Fourteen studies were focused on ATL, and two on HAM/TSP. The available data show that in vitro exposure to 1,25(OH)2D inhibits proliferation of HTLV-infected lymphocytes in patients with ATL or HAM/TSP. It has been observed that hypercalcemia, the main cause of death in patients with ATL, is not associated with serum levels of 1,25(OH)2D or parathyroid hormone-related protein, but leukemia inhibitory factor/D factor seems to be an important factor for hypercalcemia pathogenesis. It was also demonstrated an association between the VDR ApaI gene polymorphism and a decreased risk of HAM/TSP in HTLV positive individuals. Conclusion: Despite the small number and heterogeneity of the studies, this systematic review suggests that vitamin D play a role in the pathogenesis of HTLV-associated diseases.