WFDC1/ps20 Is a Novel Innate Immunomodulatory Signature Protein of Human Immunodeficiency Virus (HIV)-Permissive CD4+CD45RO+Memory T Cells That Promotes Infection by Upregulating CD54 Integrin Expression and Is Elevated in HIV Type 1 Infection

Abstract

Understanding why human immunodeficiency virus (HIV) preferentially infects some CD4⁺CD45RO⁺memory T cells has implications for antiviral immunity and pathogenesis. We report that differential expression of a novel secreted factor, ps20, previously implicated in tissue remodeling, may underlie why some CD4 T cells are preferentially targeted. We show that (i) there is a significant positive correlation between endogenous ps20 mRNA in diverse CD4 T-cell populations and in vitro infection, (ii) a ps20⁺permissive cell can be made less permissive by antibody blockade- or small-interference RNA-mediated knockdown of endogenous ps20, and (iii) conversely, a ps20^lowcell can be more permissive by adding ps20 exogenously or engineering stable ps20 expression by retroviral transduction. ps20 expression is normally detectable in CD4 T cells after in vitro activation and interleukin-2 expansion, and such oligoclonal populations comprise ps20^positiveand ps20^low/negativeisogenic clones at an early differentiation stage (CD45RO⁺/CD25⁺/CD28⁺/CD57⁻). This pattern is altered in chronic HIV infection, where ex vivo CD4⁺CD45RO⁺T cells express elevated ps20. ps20 promoted HIV entry via fusion and augmented CD54 integrin expression; both of these effects were reversed by anti-ps20 antibody. We therefore propose ps20 to be a novel signature of HIV-permissive CD4 T cells that promotes infection in an autocrine and paracrine manner and that HIV has coopted a fundamental role of ps20 in promoting cell adhesion for its benefit. Disrupting the ps20 pathway may therefore provide a novel anti-HIV strategy.