Evaluation CD4+FOXP3+ T CELL IL-10 and TGF-γ producers in keratoconjunctivitis sicca associated with HTLV-1

Abstract

Background: HTLV-1 is the causative agent of leukemia/lymphoma adult T-cell (ATLL), tropical spastic paraparesis / myelopathy associated with HTLV-1 (HAM / TSP) and uveitis. In addition, keratoconjunctivitis sicca (KCS), a multifactorial disease of the tear and of the ocular surface, has beenmore frequently reported in patients infected with HTLV-1. As for other HTLV-1-associated diseases, KCS has been related to a high proviral load. Regulatory T (Treg) cells are important in maintaining the homeostasis of the immune system. An impairment in theimmunoregulation function of Treg may contribute to the inflammatory environment observed in the KCS. This study aimed to evaluate the Treg cells of patients with KCSassociated with HTLV-1. Methods: Assays immunophenotyping by flow cytometry were conducted to assess the frequency of CD4+Treg cells(FOXP3+), as well as IL-10 and TGF-β productionby Treg. Thirty-sevenHTLV-1 individuals wereincluded (27 asymptomatic for HAM/TSPwith positive diagnosis of ocular manifestation (KCS),10 with negative diagnosis (ASS -asymptomatic). Seventeen non-infected individuals were included as controls (NI). Results: The frequencies of CD4+FOXP3+T cells were significantly higher in KCSand ASS groups when compared to noninfected individuals. As the production of immunosuppressive cytokines, a higher frequency of CD4+FOXP3+double producers of IL-10 and TGF-β in the KCSgroup was observed when compared to group ASS. Conclusion: Our results suggest that while occurs an expansion of Treg cells in HTLV-1, there isnotanefficiently controlofcell activation. Future studies should be conducted to assess more accurately the regulatory mechanisms played by Treg CD4+.