Introduction/Rationale: Plasmacytoid dendritic cells (pDC) are major interferon (IFN)-α producing-cells in response to viruses. After maturation, they stimulate T cells. We found that they cross-present antigens from HIV-1-infected CD4+ T cells to specific cytotoxic T cells. During primary HIV infection, IFNs are essential to decrease viral loads, but during chronic infection, they induce immune suppression and metabolic syndrome. Free influenza or Sars-Cov2 viruses were shown by cytometry to induce pDC diversification. Because HIV is rarely free, we stimulated pDC by HIV-1 or 2-infected H9 CD4+ T cells to assess diversification.
Methods: Human pDC were purified from buffy coats by immunomagnetic depletion and CD304+ BD AriaIII sorting, stimulated for 16h by H9 cells, tested by flow cytometry (BD LSR2), multiparametric spectral cytometry (Cytek Aurora, Omics) and single-cell RNA sequencing (scRNAseq, Chromium Next Gem-X Flex 10x Genomics, Illumina NextSeq2000, Human genome GRCh38-2024-1, R v4.05, Seurat, DGE, UMAP, GOE, pseudo-trajectory).
Results: HIV-infected CD4+ T cells induced diversification of pDC into IFN-α and IFN-λ-producing, or mature pDC with T-cell stimulatory potential (CD83), or cytotoxic cells (CD107a, target H9HIV cell apoptosis). Spectral cytometry showed diversification into 10 subpopulations with different functions. scRNAseq showed that H9 cells induced pDC with TLR7/9 signaling pathway, HIV-1 or-2-infected H9 cells induced additional subpopulations with IFN-α and -λ (more with HIV-2), IFN-Stimulated Genes (more with HIV-1), cytotoxicity, T cell activation and regulation genes.
Conclusion: H9 cells induced pDC primed for viral activation, HIV-infected H9 cells induced more populations with surprisingly contrasted functions and differences between HIV-1 and 2 infections which may explain HIV-2 lower pathogenicity. Understanding pDC diversification will enable development of targeted immunotherapeutic strategies to control HIV through adequate modulation of IFN production and cytotoxic T cell responses.
