Clarification of human blood ILC subtype interrelatedness and discovery of amphiregulin production by human NK cells shed light on HIV-1 pathogenesis

Human blood innate lymphoid cells (ILCs), which include ILCs and natural killer (NK) cells, derive from a common CD117+ILC precursor (ILCP). Yet, the relationship among the ILC subsets remains unclear. Bulk and single cell RNA-Seq and ATAC-Seq showed that blood ILC subsets cluster into ILC2s, ILCPs, a mixed cluster of CD56dim and CD56– NK cells, and a separate cluster of CD56hiNK cells that shares features with both ILCs and CD56dim/–NK cells. In surprising contrast to mice, tissue repair protein amphiregulin (AREG) was produced by human NK cells, with even higher levels in CD56hiNK cells than in ILCs. AREG expression in NK cells was driven by TCF7/WNT signaling and inhibited by TGFB1, a cytokine elevated in HIV-1+ people. Knockout of RUNX3, a WNT antagonist acting downstream of TGFB1, increased AREG production. Consistent with these findings, AREG+NK cells were decreased in people living with HIV-1. Additionally, functionally defective CD56–NK cells expanded in HIV-1+ people, in inverse correlation with CD56dimNK cells, ILCs, and CD4+T cells. Experiments in tissue culture and in humanized mice showed that CD56–NK cells derive from the epigenetically similar CD56dimNK cells, and that stimulation of MTOR by CD4+T cells or exogenous IL-2 prevents their expansion. These findings clarify how ILC subsets are related to each other and provide insight into how HIV-1 infection disrupts ILC homeostasis and contributes to pathology Different subsets of NK cells and ILCs from HIV-1 negatve and HIV-1+ peoples were sorted, and were subjected to bulk and single cell RNA-Seq and ATAC-Seq. PBMCs or sorted cells were used for in vitro culture, Cas12-crRNA mediated knockout and flow cytometry analysis.