Lymph Node Stromal Cell Responses to Perinatal T Cell Waves, A Temporal Atlas [scRNA-Seq]
The perinatal period is a critical time-window in establishing T-cell tolerance. Regulatory T cells (Tregs) made during the first two weeks of life are key drivers of perinatal tolerance induction, but how these cells are generated and operate has not been established. To elucidate the unique environment murine perinatal Tregs encounter within the lymph nodes (LNs) as they first emerge from the thymus, and how it evolves over the succeeding days, we employed single-cell RNA sequencing to generate an atlas of the early LN niche. A highly dynamic picture emerged, the stromal-cell compartment showing the most striking changes and putative interactions with other LN cell compartments. In particular, LN stromal cells showed increasing potential for lymphocyte interactions with age. Analogous studies on mice lacking a:ß T cells or enriched for autoreactive a:ß T cells revealed an acute stromal-cell response to a:ß T cell dysfunction, largely reflecting dysregulation of Tregs. Punctual ablation of perinatal Tregs induced stromal-cell activation that was dependent on both interferon-gamma signaling and activation of conventional CD4+ T cells. These findings elucidate some of the earliest cellular and molecular events in perinatal induction of T-cell tolerance, providing a framework for future explorations. Overall design: Pooled inguinal, axillary and brachial LNs were isolated from female WT and KO littermates aged D4-6, D12-15 and D30-45. Each replicate was processed, encapsulated, and sequenced independently. Samples were gently digested and cytofluorometrically sorted according to CD45.2 expression and encapsulated using the Chromium Single cell 3' v3 (10x Genomics).