Id2 controls specification of Lgr5+ intestinal stem cell progenitors during gut development.

The adult intestinal stem cells (ISCs), their hierarchies, mechanisms of maintenance and differentiation have been extensively studied. However, when and how ISCs are established during embryogenesis remains unknown. We show here that the transcription regulator Id2 controls the specification of embryonic Lgr5+ progenitors in the developing murine small intestine. Cell fate mapping analysis revealed that Lgr5+ progenitors emerge at E13.5 in wild-type embryos and differ from the rest on the intestinal epithelium by a characteristic ISC signature. In the absence of Id2, the intestinal epithelium differentiates into Lgr5+ cells already at E9.5. Furthermore, the size of the Lgr5+ cell pool is significantly increased. We show that Id2 restricts the activity of the Wnt signalling pathway at early stages and prevents precocious differentiation of the embryonic intestinal epithelium. Id2-deficient embryonic epithelial cells cultured ex vivo strongly activate Wnt target genes as well as markers of neoplastic transformation and form fast growing undifferentiated spheroids. Furthermore, adult ISCs from Id2-deficient mice display a distinct transcriptional signature, supporting an essential role for Id2 in the correct specification of ISCs.

Distinct populations of embryonic epithelial progenitors generate Lgr5+ intestinal stem cells.

The adult intestinal stem cells (ISCs) are transcriptionally heterogeneous. As the mechanisms governing their developmental specification are still poorly understood, whether this heterogeneity reflects an early determination of distinct cellular sub-types with potentially distinct physiological functions remains an open question. We investigate the cellular heterogeneity within the mouse embryonic midgut epithelium at the molecular and functional levels. Cell fate mapping analysis revealed that multiple early embryonic epithelial progenitors give rise to Lgr5+ ISCs. The origin of the molecularly distinct early precursors along the anterior-posterior axis defines the transcriptional signature of embryonic Lgr5+ ISC progenitors. We further show that the early epithelial progenitors have different capacity to generate Lgr5+ ISC progenitors and Axin2+ early precursors display the highest potential.

Comprehensive peripheral blood immunoprofiling reveals five immunotypes with immunotherapy response characteristics in patients with cancer.

The lack of comprehensive diagnostics and consensus analytical models for evaluating the status of a patient's immune system has hindered a wider adoption of immunoprofiling for treatment monitoring and response prediction in cancer patients. To address this unmet need, we developed an immunoprofiling platform that uses multiparameter flow cytometry to characterize immune cell heterogeneity in the peripheral blood of healthy donors and patients with advanced cancers. Using unsupervised clustering, we identified five immunotypes with unique distributions of different cell types and gene expression profiles. An independent analysis of 17,800 open-source transcriptomes with the same approach corroborated these findings. Continuous immunotype-based signature scores were developed to correlate systemic immunity with patient responses to different cancer treatments, including immunotherapy, prognostically and predictively. Our approach and findings illustrate the potential utility of a simple blood test as a flexible tool for stratifying cancer patients into therapy response groups based on systemic immunoprofiling.

TCF7L1 Controls the Differentiation of Tuft Cells in Mouse Small Intestine.

Continuous and rapid renewal of the intestinal epithelium depends on intestinal stem cells (ISCs). A large repertoire of transcription factors mediates the correct maintenance and differentiation of ISCs along either absorptive or secretory lineages. In the present study, we addressed the role of TCF7L1, a negative regulator of WNT signalling, in embryonic and adult intestinal epithelium using conditional mouse mutants. We found that TCF7L1 prevents precocious differentiation of the embryonic intestinal epithelial progenitors towards enterocytes and ISCs. We show that Tcf7l1 deficiency leads to upregulation of the Notch effector Rbp-J, resulting in a subsequent loss of embryonic secretory progenitors. In the adult small intestine, TCF7L1 is required for the differentiation of secretory epithelial progenitors along the tuft cell lineage. Furthermore, we show that Tcf7l1 promotes the differentiation of enteroendocrine D- and L-cells in the anterior small intestine. We conclude that TCF7L1-mediated repression of both Notch and WNT pathways is essential for the correct differentiation of intestinal secretory progenitors.