Abstract Digestive system diseases arise primarily through the interplay of genetic and environmental influences; there is an urgent need in elucidating the pathogenic mechanisms of these diseases and deploy personalized treatments. Traditional and long-established model systems rarely reproduce either tissue complexity or human physiology faithfully; these shortcomings underscore the need for better models. Organoids represent a promising research model, helping us gain a more profound understanding of the digestive organs; this model can also be used to provide patients with precise and individualized treatment and to build rapid in vitro test models for drug screening or gene/cell therapy, linking basic research with clinical treatment. Over the past few decades, the use of organoids has led to an advanced understanding of the composition of each digestive organ and has facilitated disease modeling, chemotherapy dose prediction, CRISPR-Cas9 genetic intervention, high-throughput drug screening, and identification of SARS-CoV-2 targets, pathogenic infection. However, the existing organoids of the digestive system mainly include the epithelial system. In order to reveal the pathogenic mechanism of digestive diseases, it is necessary to establish a completer and more physiological organoid model. Combining organoids and advanced techniques to test individualized treatments of different formulations is a promising approach that requires further exploration. This review highlights the advancements in the field of organoid technology from the perspectives of disease modeling and personalized therapy. 

/pdf/applications-of-human-organoids-in-the-personalized-122eb8ve.pdf

Applications of human organoids in the personalized treatment for digestive diseases

Many adult tissues and organs including the intestine rely on resident stem cells to maintain homeostasis and regeneration. In mammals, the progenies of intestinal stem cells (ISCs) can dedifferentiate to generate ISCs upon ablation of resident stem cells. However, whether and how mature tissue cells generate ISCs under physiological conditions remains unknown. Here, we show that infection of the Drosophila melanogaster intestine with pathogenic bacteria induces entry of enteroblasts (EBs), which are ISC progenies, into the mitotic cycle through upregulation of epidermal growth factor receptor (EGFR)‐Ras signaling. We also show that ectopic activation of EGFR‐Ras signaling in EBs is sufficient to drive enteroblast mitosis cell autonomously. Furthermore, we find that the dividing enteroblasts do not gain ISC identity as a prerequisite to divide, and the regenerative ISCs are produced through EB mitosis. Taken together, our work uncovers a new role for EGFR‐Ras signaling in driving EB mitosis and replenishing the ISC pool during fly intestinal regeneration, which may have important implications for tissue homeostasis and tumorigenesis in vertebrates.

Damage‐induced regeneration of the intestinal stem cell pool through enteroblast mitosis in the Drosophila midgut

Tuft cells are found in tissues with distinct stem cell compartments, tissue architecture, and luminal exposures but converge on a shared transcriptional program, including expression of taste transduction signaling pathways. Here, we summarize seminal and recent findings on tuft cells, focusing on major categories of function-instigation of type 2 cytokine responses, orchestration of antimicrobial responses, and emerging roles in tissue repair-and describe tuft cell-derived molecules used to affect these functional programs. We review what is known about the development of tuft cells from epithelial progenitors under homeostatic conditions and during disease. Finally, we discuss evidence that immature, or nascent, tuft cells with potential for diverse functions are driven toward dominant effector programs by tissue- or perturbation-specific contextual cues, which may result in heterogeneous mature tuft cell phenotypes both within and between tissues. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 18 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Tuft Cells: Context- and Tissue-Specific Programming for a Conserved Cell Lineage.

http://www.mucosalimmunology.org/article/S1933021922000861/pdf

Challenges and opportunities targeting mechanisms of epithelial injury and recovery in acute intestinal graft-versus-host disease

Quiescent cancer stem cells (CSC) are resistant to conventional anticancer treatments and have been shown to contribute to disease relapse after therapy in some cancer types. The identification and characterization of quiescent CSCs could facilitate the development of strategies to target this cell population and block recurrence. Here, we established a syngeneic orthotopic transplantation model in mice based on intestinal cancer organoids to profile quiescent CSCs. Single-cell transcriptomic analysis of the primary tumors formed in vivo revealed that conventional Lgr5high intestinal CSCs comprise both actively and slowly cycling subpopulations, the latter of which specifically expresses the cyclin-dependent kinase inhibitor p57. Tumorigenicity assays and lineage tracing experiments showed that the quiescent p57+ CSCs contribute in only a limited manner to steady-state tumor growth but they are chemotherapy resistant and drive posttherapeutic cancer recurrence. Ablation of p57+ CSCs suppressed intestinal tumor regrowth after chemotherapy. Together, these results shed light on the heterogeneity of intestinal CSCs and reveal p57+ CSCs as a promising therapeutic target for malignant intestinal cancer.A quiescent p57+ subpopulation of intestinal CSCs is resistant to chemotherapy and can be targeted to effectively suppress the recurrence of intestinal cancer. 

Ablation of p57+ Quiescent Cancer Stem Cells Suppresses Recurrence After Chemotherapy of Intestinal Tumors

Although the mammalian intestinal epithelium manifests robust regenerative capacity after various cytotoxic injuries, the underlying mechanism has remained unclear. Here we identify the cyclin-dependent kinase inhibitor p57 as a specific marker for a quiescent cell population located around the +4 position of intestinal crypts. Lineage tracing reveals that the p57+ cells serve as enteroendocrine/tuft cell precursors under normal conditions but dedifferentiate and act as facultative stem cells to support regeneration after injury. Single-cell transcriptomics analysis shows that the p57+ cells undergo a dynamic reprogramming process after injury that is characterized by fetal-like conversion and metaplasia-like transformation. Population-level analysis also detects such spatiotemporal reprogramming widely in other differentiated cell types. In intestinal adenoma, p57+ cells manifest homeostatic stem cell activity, in the context of constitutively activated spatiotemporal reprogramming. Our results highlight a pronounced plasticity of the intestinal epithelium that supports maintenance of tissue integrity in normal and neoplastic contexts. 

/pdf/spatiotemporal-reprogramming-of-differentiated-cells-1vjjgbqn.pdf

Spatiotemporal reprogramming of differentiated cells underlies regeneration and neoplasia in the intestinal epithelium

Developing CD4+CD8+ double-positive (DP) thymocytes with randomly generated T cell receptors (TCRs) undergo positive (maturation) or negative (apoptosis) selection on the basis of the strength of TCR stimulation. Selection fate is determined by engagement of TCR ligands with a subtle difference in affinity, but the molecular details of TCR signaling leading to the different selection outcomes have remained unclear. We performed phosphoproteome analysis of DP thymocytes and found that p90 ribosomal protein kinase (RSK) phosphorylation at Thr562 was induced specifically by high-affinity peptide ligands. Such phosphorylation of RSK triggered its translocation to the nucleus, where it phosphorylated the nuclear receptor Nur77 and thereby promoted its mitochondrial translocation for apoptosis induction. Inhibition of RSK activity protected DP thymocytes from antigen-induced cell death. We propose that RSK phosphorylation constitutes a mechanism by which DP thymocytes generate a stepwise and binary signal in response to exposure to TCR ligands with a graded affinity. 

A stepwise and digital pattern of RSK phosphorylation determines the outcome of thymic selection

ABSTRACT The tumor immune microenvironment plays a key role in the regulation of cancer progression. Recent studies have suggested a relation between diverse tumor genotypes and tumor immune microenvironment phenotypes for cholangiocarcinoma (CCA). However, the contribution of tumor‐infiltrating immune cells to CCA progression has remained unclear, underscoring the need for genetically defined CCA models in immunocompetent mice. We here aimed to generate genetically engineered and transplantable CCA organoids from C57BL/6 mice and to investigate the role of tumor‐infiltrating immune cells in CCA progression with this model. CCA organoids were generated ex vivo with the use of the CRISPR/Cas9 system. Orthotopic transplantation of CCA organoids harboring mutations in Smad4, Trp53, and Kras into wild‐type C57BL/6 mice resulted in tumor formation accompanied by distant metastasis. Selective depletion of immune cell types in the tumor‐bearing mice revealed an antitumor action of tumor‐infiltrating neutrophils (TINs) that was mediated by direct killing of cancer cells through the production of reactive oxygen species. Furthermore, administration of recombinant human granulocyte colony‐stimulating factor (rhG‐CSF) increased the number and cytotoxicity of TINs, suppressed tumor growth, and prolonged the survival of tumor‐bearing mice. Finally, combination treatment with rhG‐CSF and standard chemotherapy resulted in a synergistic attenuation of tumor growth. Our study therefore provides a syngeneic and genetically defined mouse model of CCA and highlights the therapeutic potential of targeting TINs with rhG‐CSF.

Antitumor Activity of Tumor-Infiltrating Neutrophils Revealed by a Syngeneic Mouse Model of Cholangiocarcinoma.

Quiescent cancer stem cells (CSCs) are resistant to conventional anti-cancer treatments and have been shown to contribute to disease relapse after therapy in some cancer types. The identification and characterization of quiescent CSCs could facilitate the development of strategies to target this cell population and block recurrence. Here, we established a syngeneic orthotopic transplantation model in mice based on intestinal cancer organoids to profile quiescent CSCs. Single-cell transcriptomic analysis of the primary tumors formed in vivo revealed that conventional Lgr5high intestinal CSCs comprise both actively and slowly cycling subpopulations, the latter of which specifically expresses the cyclin-dependent kinase inhibitor p57. Tumorigenicity assays and lineage tracing experiments showed that the quiescent p57+ CSCs contribute in only a limited manner to steady-state tumor growth but they are chemotherapy resistant and drive post-therapeutic cancer recurrence. Ablation of p57+ CSCs suppressed intestinal tumor regrowth after chemotherapy. Together, these results shed light on the heterogeneity of intestinal CSCs and reveal p57+ CSCs as a promising therapeutic target for malignant intestinal cancer.

Ablation of p57+ Quiescent Cancer Stem Cells Suppresses Recurrence After Chemotherapy of Intestinal Tumors.

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Spatiotemporal reprogramming of differentiated cells underlies regeneration and neoplasia in the intestinal epithelium

A stepwise and digital pattern of RSK phosphorylation determines the outcome of thymic selection

Antitumor Activity of Tumor-Infiltrating Neutrophils Revealed by a Syngeneic Mouse Model of Cholangiocarcinoma.

Ablation of p57+ Quiescent Cancer Stem Cells Suppresses Recurrence After Chemotherapy of Intestinal Tumors.