Single-cell RNA-seq analysis of the lymphoproliferative disorders triggered by defective LAT signalosome. Modulation of the pathology in the context of two additional mutations, Stat6KO or Grap2KO

LatY136F mice in which tyrosine 136 of the LAT adaptor is mutate accumulate CD4+ T cells that trigger a fast-onset autoimmune and inflammatory condition called LAT signaling pathology (LSP). Its histopathological manifestations resemble those of human IgG4-related disease (IgG4-RD), an inflammatory condition unifying a constellation of clinical entities leading to multi-organ damage. LatY136F mice deprived of STAT6 transcription factor develop a lymphoproliferative disorder with a kinetics and magnitude identical to that of LatY136F mice. Consistent with a role of STAT6 in Th2 differentiation, the LatY136F x Stat6KO lymphoproliferative disorder is characterize by a lymphoproliferation of both CD4 and CD8 Tc producing high levels of IFN-g. This Tc proliferation is associated with massive B cell proliferation and hyperglobulinemia G2a and G2b. Using single-cell RNA sequencing, we analyzed 48287 CD4 and CD8 T cells isolated from the spleen of LatY136F and LatY136F x Stat6KO mice over the period that leads to LSP installation. In this study, LatY136F lymphoproliferative disorder is also analyze in Grab2KO mice. Unexpectedly, LatY136F x Grap2KO mice present a lymphoproliferative disorder similar to the one observed in LatY136F mice but this time TCRgd Tc. Lymphoid cells were isolated from spleen of LatY136F, LatY136F x Stat6KO and LatY136F x Grap2KO mice. T cell are first enriched and then purified by cell sorting. Library are processed using Chromium Single Cell 3’ kit from 10X Genomics (California, USA). Sequencing was realized on a NovaSeq6000 system (Illumina). FASTQ raw files were processed using Cell Ranger software (v2.1.1, default parameters), which performs alignment, filtering, barcode counting and unique molecular identifier (UMI) counting. Reads were aligned to the mouse mm10 genome.