RESUMEN
Epithelial folding is a fundamental biological process that requires epithelial interactions with the underlying mesenchyme. In this issue of Cell, Huycke et al. investigate intestinal villus formation. They discover that water-droplet-like behavior of mesenchymal cells drives their coalescence into uniformly patterned aggregates, which generate forces on the epithelium to initiate folding.
Asunto(s)
Epitelio , Mesodermo , Animales , Humanos , Células Epiteliales/metabolismo , Células Epiteliales/citología , Mucosa Intestinal/metabolismo , Mucosa Intestinal/citología , Mesodermo/metabolismo , Mesodermo/citología , Epitelio/metabolismoRESUMEN
In the prevailing model, Lgr5+ cells are the only intestinal stem cells (ISCs) that sustain homeostatic epithelial regeneration by upward migration of progeny through elusive upper crypt transit-amplifying (TA) intermediates. Here, we identify a proliferative upper crypt population marked by Fgfbp1, in the location of putative TA cells, that is transcriptionally distinct from Lgr5+ cells. Using a kinetic reporter for time-resolved fate mapping and Fgfbp1-CreERT2 lineage tracing, we establish that Fgfbp1+ cells are multi-potent and give rise to Lgr5+ cells, consistent with their ISC function. Fgfbp1+ cells also sustain epithelial regeneration following Lgr5+ cell depletion. We demonstrate that FGFBP1, produced by the upper crypt cells, is an essential factor for crypt proliferation and epithelial homeostasis. Our findings support a model in which tissue regeneration originates from upper crypt Fgfbp1+ cells that generate progeny propagating bi-directionally along the crypt-villus axis and serve as a source of Lgr5+ cells in the crypt base.
Asunto(s)
Mucosa Intestinal , Receptores Acoplados a Proteínas G , Receptores Acoplados a Proteínas G/metabolismo , Animales , Ratones , Mucosa Intestinal/metabolismo , Mucosa Intestinal/citología , Células Madre/metabolismo , Células Madre/citología , Linaje de la Célula , Regeneración , Proliferación Celular , Células Epiteliales/metabolismo , Células Epiteliales/citología , Ratones Endogámicos C57BL , HomeostasisRESUMEN
Many embryonic organs undergo epithelial morphogenesis to form tree-like hierarchical structures. However, it remains unclear what drives the budding and branching of stratified epithelia, such as in the embryonic salivary gland and pancreas. Here, we performed live-organ imaging of mouse embryonic salivary glands at single-cell resolution to reveal that budding morphogenesis is driven by expansion and folding of a distinct epithelial surface cell sheet characterized by strong cell-matrix adhesions and weak cell-cell adhesions. Profiling of single-cell transcriptomes of this epithelium revealed spatial patterns of transcription underlying these cell adhesion differences. We then synthetically reconstituted budding morphogenesis by experimentally suppressing E-cadherin expression and inducing basement membrane formation in 3D spheroid cultures of engineered cells, which required ß1-integrin-mediated cell-matrix adhesion for successful budding. Thus, stratified epithelial budding, the key first step of branching morphogenesis, is driven by an overall combination of strong cell-matrix adhesion and weak cell-cell adhesion by peripheral epithelial cells.
Asunto(s)
Uniones Célula-Matriz/metabolismo , Morfogénesis , Animales , Membrana Basal/metabolismo , Adhesión Celular , División Celular , Movimiento Celular , Rastreo Celular , Embrión de Mamíferos/citología , Células Epiteliales/citología , Células Epiteliales/metabolismo , Epitelio , Regulación del Desarrollo de la Expresión Génica , Células HEK293 , Humanos , Integrinas/metabolismo , Ratones , Modelos Biológicos , Glándulas Salivales/citología , Glándulas Salivales/embriología , Glándulas Salivales/metabolismo , Transcriptoma/genéticaRESUMEN
The oral mucosa remains an understudied barrier tissue. This is a site of rich exposure to antigens and commensals, and a tissue susceptible to one of the most prevalent human inflammatory diseases, periodontitis. To aid in understanding tissue-specific pathophysiology, we compile a single-cell transcriptome atlas of human oral mucosa in healthy individuals and patients with periodontitis. We uncover the complex cellular landscape of oral mucosal tissues and identify epithelial and stromal cell populations with inflammatory signatures that promote antimicrobial defenses and neutrophil recruitment. Our findings link exaggerated stromal cell responsiveness with enhanced neutrophil and leukocyte infiltration in periodontitis. Our work provides a resource characterizing the role of tissue stroma in regulating mucosal tissue homeostasis and disease pathogenesis.
Asunto(s)
Inmunidad Mucosa , Mucosa Bucal/citología , Mucosa Bucal/inmunología , Neutrófilos/citología , Adulto , Células Epiteliales/citología , Regulación de la Expresión Génica , Predisposición Genética a la Enfermedad , Encía/patología , Humanos , Inflamación/inmunología , Inflamación/patología , Microbiota , Células Mieloides/citología , Periodontitis/genética , Periodontitis/inmunología , Periodontitis/patología , Análisis de la Célula Individual , Células del Estroma/citología , Linfocitos T/citologíaRESUMEN
Organs are composed of diverse cell types that traverse transient states during organogenesis. To interrogate this diversity during human development, we generate a single-cell transcriptome atlas from multiple developing endodermal organs of the respiratory and gastrointestinal tract. We illuminate cell states, transcription factors, and organ-specific epithelial stem cell and mesenchyme interactions across lineages. We implement the atlas as a high-dimensional search space to benchmark human pluripotent stem cell (hPSC)-derived intestinal organoids (HIOs) under multiple culture conditions. We show that HIOs recapitulate reference cell states and use HIOs to reconstruct the molecular dynamics of intestinal epithelium and mesenchyme emergence. We show that the mesenchyme-derived niche cue NRG1 enhances intestinal stem cell maturation in vitro and that the homeobox transcription factor CDX2 is required for regionalization of intestinal epithelium and mesenchyme in humans. This work combines cell atlases and organoid technologies to understand how human organ development is orchestrated.
Asunto(s)
Anatomía Artística , Atlas como Asunto , Desarrollo Embrionario , Endodermo/embriología , Modelos Biológicos , Organoides/embriología , Factor de Transcripción CDX2/metabolismo , Línea Celular , Factor de Crecimiento Epidérmico/farmacología , Células Epiteliales/citología , Femenino , Gastrulación , Eliminación de Gen , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Humanos , Intestinos/embriología , Masculino , Mesodermo/embriología , Persona de Mediana Edad , Neurregulina-1/metabolismo , Especificidad de Órganos , Células Madre Pluripotentes/citologíaRESUMEN
Throughout a 24-h period, the small intestine (SI) is exposed to diurnally varying food- and microbiome-derived antigenic burdens but maintains a strict immune homeostasis, which when perturbed in genetically susceptible individuals, may lead to Crohn disease. Herein, we demonstrate that dietary content and rhythmicity regulate the diurnally shifting SI epithelial cell (SIEC) transcriptional landscape through modulation of the SI microbiome. We exemplify this concept with SIEC major histocompatibility complex (MHC) class II, which is diurnally modulated by distinct mucosal-adherent SI commensals, while supporting downstream diurnal activity of intra-epithelial IL-10+ lymphocytes regulating the SI barrier function. Disruption of this diurnally regulated diet-microbiome-MHC class II-IL-10-epithelial barrier axis by circadian clock disarrangement, alterations in feeding time or content, or epithelial-specific MHC class II depletion leads to an extensive microbial product influx, driving Crohn-like enteritis. Collectively, we highlight nutritional features that modulate SI microbiome, immunity, and barrier function and identify dietary, epithelial, and immune checkpoints along this axis to be potentially exploitable in future Crohn disease interventions.
Asunto(s)
Enfermedad de Crohn/microbiología , Células Epiteliales/metabolismo , Microbioma Gastrointestinal , Antígenos de Histocompatibilidad Clase II/metabolismo , Intestino Delgado/inmunología , Intestino Delgado/microbiología , Transcriptoma/genética , Animales , Antibacterianos/farmacología , Relojes Circadianos/fisiología , Enfermedad de Crohn/inmunología , Enfermedad de Crohn/metabolismo , Dieta , Células Epiteliales/citología , Células Epiteliales/inmunología , Citometría de Flujo , Microbioma Gastrointestinal/efectos de los fármacos , Microbioma Gastrointestinal/genética , Perfilación de la Expresión Génica , Antígenos de Histocompatibilidad Clase II/genética , Homeostasis , Hibridación Fluorescente in Situ , Interleucina-10/metabolismo , Interleucina-10/farmacología , Intestino Delgado/fisiología , Linfocitos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Periodicidad , Linfocitos T/inmunología , Transcriptoma/fisiologíaRESUMEN
Intracellular accumulation of misfolded proteins causes toxic proteinopathies, diseases without targeted therapies. Mucin 1 kidney disease (MKD) results from a frameshift mutation in the MUC1 gene (MUC1-fs). Here, we show that MKD is a toxic proteinopathy. Intracellular MUC1-fs accumulation activated the ATF6 unfolded protein response (UPR) branch. We identified BRD4780, a small molecule that clears MUC1-fs from patient cells, from kidneys of knockin mice and from patient kidney organoids. MUC1-fs is trapped in TMED9 cargo receptor-containing vesicles of the early secretory pathway. BRD4780 binds TMED9, releases MUC1-fs, and re-routes it for lysosomal degradation, an effect phenocopied by TMED9 deletion. Our findings reveal BRD4780 as a promising lead for the treatment of MKD and other toxic proteinopathies. Generally, we elucidate a novel mechanism for the entrapment of misfolded proteins by cargo receptors and a strategy for their release and anterograde trafficking to the lysosome.
Asunto(s)
Benzamidas/metabolismo , Compuestos Bicíclicos con Puentes/farmacología , Heptanos/farmacología , Lisosomas/efectos de los fármacos , Proteínas de Transporte Vesicular/metabolismo , Factor de Transcripción Activador 6/metabolismo , Animales , Benzamidas/química , Benzamidas/farmacología , Compuestos Bicíclicos con Puentes/uso terapéutico , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Mutación del Sistema de Lectura , Heptanos/uso terapéutico , Humanos , Receptores de Imidazolina/antagonistas & inhibidores , Receptores de Imidazolina/genética , Receptores de Imidazolina/metabolismo , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Riñón/citología , Riñón/metabolismo , Riñón/patología , Enfermedades Renales/metabolismo , Enfermedades Renales/patología , Lisosomas/metabolismo , Masculino , Ratones , Ratones Transgénicos , Mucina-1/química , Mucina-1/genética , Mucina-1/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Respuesta de Proteína Desplegada/efectos de los fármacos , Proteínas de Transporte Vesicular/químicaRESUMEN
In multicellular systems, oriented cell divisions are essential for morphogenesis and homeostasis as they determine the position of daughter cells within the tissue and also, in many cases, their fate. Early studies in invertebrates led to the identification of conserved core mechanisms of mitotic spindle positioning centred on the Gαi-LGN-NuMA-dynein complex. In recent years, much has been learnt about the way this complex functions in vertebrate cells. In particular, studies addressed how the Gαi-LGN-NuMA-dynein complex dynamically crosstalks with astral microtubules and the actin cytoskeleton, and how it is regulated to orient the spindle according to cellular and tissue-wide cues. We have also begun to understand how dynein motors and actin regulators interact with mechanosensitive adhesion molecules sensing extracellular mechanical stimuli, such as cadherins and integrins, and with signalling pathways so as to respond to extracellular cues instructing the orientation of the division axis in vivo. In this Review, with the focus on epithelial tissues, we discuss the molecular mechanisms of mitotic spindle orientation in vertebrate cells, and how this machinery is regulated by epithelial cues and extracellular signals to maintain tissue cohesiveness during mitosis. We also outline recent knowledge of how spindle orientation impacts tissue architecture in epithelia and its emerging links to the regulation of cell fate decisions. Finally, we describe how defective spindle orientation can be corrected or its effects eliminated in tissues under physiological conditions, and the pathological implications associated with spindle misorientation.
Asunto(s)
Huso Acromático/metabolismo , Citoesqueleto de Actina/metabolismo , Animales , Diferenciación Celular , Polaridad Celular , Células Epiteliales/citología , Células Epiteliales/metabolismo , Epitelio/metabolismo , Humanos , Mitosis , Transducción de SeñalRESUMEN
Liver regeneration is a complex process involving the crosstalk of multiple cell types, including hepatocytes, hepatic stellate cells, endothelial cells and inflammatory cells. The healthy liver is mitotically quiescent, but following toxic damage or resection the cells can rapidly enter the cell cycle to restore liver mass and function. During this process of regeneration, epithelial and non-parenchymal cells respond in a tightly coordinated fashion. Recent studies have described the interaction between inflammatory cells and a number of other cell types in the liver. In particular, macrophages can support biliary regeneration, contribute to fibrosis remodelling by repressing hepatic stellate cell activation and improve liver regeneration by scavenging dead or dying cells in situ. In this Review, we describe the mechanisms of tissue repair following damage, highlighting the close relationship between inflammation and liver regeneration, and discuss how recent findings can help design novel therapeutic approaches.
Asunto(s)
Cirrosis Hepática/patología , Cirrosis Hepática/terapia , Regeneración Hepática/fisiología , Trasplante de Células , Células Epiteliales/citología , Células Epiteliales/trasplante , Células Estrelladas Hepáticas/metabolismo , Hepatocitos/citología , Hepatocitos/patología , Hepatocitos/trasplante , Humanos , Inflamación , Macrófagos/citología , Macrófagos/patología , Macrófagos/trasplante , Transducción de SeñalRESUMEN
The small intestinal tuft cell-ILC2 circuit mediates epithelial responses to intestinal helminths and protists by tuft cell chemosensory-like sensing and IL-25-mediated activation of lamina propria ILC2s. Small intestine ILC2s constitutively express the IL-25 receptor, which is negatively regulated by A20 (Tnfaip3). A20 deficiency in ILC2s spontaneously triggers the circuit and, unexpectedly, promotes adaptive small-intestinal lengthening and remodeling. Circuit activation occurs upon weaning and is enabled by dietary polysaccharides that render mice permissive for Tritrichomonas colonization, resulting in luminal accumulation of acetate and succinate, metabolites of the protist hydrogenosome. Tuft cells express GPR91, the succinate receptor, and dietary succinate, but not acetate, activates ILC2s via a tuft-, TRPM5-, and IL-25-dependent pathway. Also induced by parasitic helminths, circuit activation and small intestinal remodeling impairs infestation by new helminths, consistent with the phenomenon of concomitant immunity. We describe a metabolic sensing circuit that may have evolved to facilitate mutualistic responses to luminal pathosymbionts.
Asunto(s)
Intestino Delgado/fisiología , Tritrichomonas/metabolismo , Acetatos/metabolismo , Animales , Fibras de la Dieta/metabolismo , Metabolismo Energético , Células Epiteliales/citología , Células Epiteliales/metabolismo , Células Epiteliales/parasitología , Interleucinas/genética , Interleucinas/metabolismo , Mucosa Intestinal/citología , Intestino Delgado/microbiología , Intestino Delgado/parasitología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microbiota , Plásmidos/genética , Plásmidos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Interleucina/metabolismo , Receptores de Interleucina-17/genética , Receptores de Interleucina-17/metabolismo , Ácido Succínico/metabolismo , Canales Catiónicos TRPM/metabolismo , Tritrichomonas/crecimiento & desarrollo , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfa/genética , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Genome-wide association studies have identified risk loci associated with the development of inflammatory bowel disease, while epidemiological studies have emphasized that pathogenesis likely involves host interactions with environmental elements whose source and structure need to be defined. Here, we identify a class of compounds derived from dietary, microbial, and industrial sources that are characterized by the presence of a five-membered oxazole ring and induce CD1d-dependent intestinal inflammation. We observe that minimal oxazole structures modulate natural killer T cell-dependent inflammation by regulating lipid antigen presentation by CD1d on intestinal epithelial cells (IECs). CD1d-restricted production of interleukin 10 by IECs is limited through activity of the aryl hydrocarbon receptor (AhR) pathway in response to oxazole induction of tryptophan metabolites. As such, the depletion of the AhR in the intestinal epithelium abrogates oxazole-induced inflammation. In summary, we identify environmentally derived oxazoles as triggers of CD1d-dependent intestinal inflammatory responses that occur via activation of the AhR in the intestinal epithelium.
Asunto(s)
Colitis/patología , Dieta , Intestinos/patología , Oxazoles/farmacología , Receptores de Hidrocarburo de Aril/metabolismo , Transducción de Señal/efectos de los fármacos , Animales , Antígenos CD1d/genética , Antígenos CD1d/metabolismo , Colitis/inducido químicamente , Colitis/metabolismo , Modelos Animales de Enfermedad , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenasa/metabolismo , Interleucina-10/metabolismo , Intestinos/citología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células T Asesinas Naturales/inmunología , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Receptores de Hidrocarburo de Aril/antagonistas & inhibidores , Receptores de Hidrocarburo de Aril/genética , Triptófano/metabolismoRESUMEN
In the small intestine, a niche of accessory cell types supports the generation of mature epithelial cell types from intestinal stem cells (ISCs). It is unclear, however, if and how immune cells in the niche affect ISC fate or the balance between self-renewal and differentiation. Here, we use single-cell RNA sequencing (scRNA-seq) to identify MHC class II (MHCII) machinery enrichment in two subsets of Lgr5+ ISCs. We show that MHCII+ Lgr5+ ISCs are non-conventional antigen-presenting cells in co-cultures with CD4+ T helper (Th) cells. Stimulation of intestinal organoids with key Th cytokines affects Lgr5+ ISC renewal and differentiation in opposing ways: pro-inflammatory signals promote differentiation, while regulatory cells and cytokines reduce it. In vivo genetic perturbation of Th cells or MHCII expression on Lgr5+ ISCs impacts epithelial cell differentiation and IEC fate during infection. These interactions between Th cells and Lgr5+ ISCs, thus, orchestrate tissue-wide responses to external signals.
Asunto(s)
Diferenciación Celular , Autorrenovación de las Células , Interleucina-10/metabolismo , Células Madre/citología , Linfocitos T Colaboradores-Inductores/metabolismo , Animales , Diferenciación Celular/efectos de los fármacos , Autorrenovación de las Células/efectos de los fármacos , Citocinas/farmacología , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Antígenos de Histocompatibilidad Clase II/metabolismo , Sistema Inmunológico/metabolismo , Intestinos/citología , Intestinos/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Organoides/citología , Organoides/efectos de los fármacos , Organoides/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Salmonella enterica/patogenicidad , Células Madre/metabolismo , Linfocitos T Colaboradores-Inductores/citologíaRESUMEN
Polarization along an apico-basolateral axis is a hallmark of epithelial cells and is essential for their selective barrier and transporter functions, as well as for their ability to provide mechanical resiliency to organs. Loss of polarity along this axis perturbs development and is associated with a wide number of diseases. We describe three steps involved in polarization: symmetry breaking, polarity establishment, and polarity maintenance. While the proteins involved in these processes are highly conserved among epithelial tissues and species, the execution of these steps varies widely and is context dependent. We review both theoretical principles underlying these steps and recent work demonstrating how apico-basolateral polarity is established in vivo in different tissues, highlighting how developmental and physiological contexts play major roles in the execution of the epithelial polarity program.
Asunto(s)
Membrana Basal/metabolismo , Polaridad Celular , Células Epiteliales/citología , Epitelio/metabolismo , Animales , Membrana Basal/citología , Comunicación Celular , Matriz Extracelular/metabolismo , Humanos , Proteínas de la Membrana/metabolismo , Transducción de SeñalRESUMEN
Cell-cell interfaces are found throughout multicellular organisms, from transient interactions between motile immune cells to long-lived cell-cell contacts in epithelia. Studies of immune cell interactions, epithelial cell barriers, neuronal contacts and sites of cell-cell fusion have identified a core set of features shared by cell-cell interfaces that critically control their function. Data from diverse cell types also show that cells actively and passively regulate the localization, strength, duration and cytoskeletal coupling of receptor interactions governing cell-cell signalling and physical connections between cells, indicating that cell-cell interfaces have a unique membrane organization that emerges from local molecular and cellular mechanics. In this Review, we discuss recent findings that support the emerging view of cell-cell interfaces as specialized compartments that biophysically constrain the arrangement and activity of their protein, lipid and glycan components. We also review how these biophysical features of cell-cell interfaces allow cells to respond with high selectivity and sensitivity to multiple inputs, serving as the basis for wide-ranging cellular functions. Finally, we consider how the unique properties of cell-cell interfaces present opportunities for therapeutic intervention.
Asunto(s)
Comunicación Celular/fisiología , Compartimento Celular/fisiología , Fenómenos Fisiológicos Celulares/fisiología , Animales , Fusión Celular , Células Epiteliales/citología , Células Epiteliales/fisiología , Humanos , Mecanotransducción Celular/fisiología , Neuronas/citología , Neuronas/fisiologíaRESUMEN
The mesenchymal-amoeboid transition (MAT) was proposed as a mechanism for cancer cells to adapt their migration mode to their environment. While the molecular pathways involved in this transition are well documented, the role of the microenvironment in the MAT is still poorly understood. Here, we investigated how confinement and adhesion affect this transition. We report that, in the absence of focal adhesions and under conditions of confinement, mesenchymal cells can spontaneously switch to a fast amoeboid migration phenotype. We identified two main types of fast migration--one involving a local protrusion and a second involving a myosin-II-dependent mechanical instability of the cell cortex that leads to a global cortical flow. Interestingly, transformed cells are more prone to adopt this fast migration mode. Finally, we propose a generic model that explains migration transitions and predicts a phase diagram of migration phenotypes based on three main control parameters: confinement, adhesion, and contractility.
Asunto(s)
Mesodermo/citología , Animales , Adhesión Celular , Línea Celular Tumoral , Movimiento Celular , Células Epiteliales/citología , Fibroblastos/citología , Adhesiones Focales , Células HeLa , Humanos , Piel/citologíaRESUMEN
Tissue stem cells require unique niche microenvironments. In the presence of specific combinations of niche factors, mouse and human epithelial tissues from stomach, small intestine, colon, pancreas duct, and liver bile duct efficiently form stereotypic organoids. The platform of epitheloid organoids can also be employed for in vitro generation of digestive tissue from human pluripotent stem cells. Organoids hold great promise for basic and translational research.
Asunto(s)
Organoides , Células Madre/citología , Técnicas de Cultivo de Tejidos , Animales , Sistema Digestivo/citología , Células Epiteliales/citología , Humanos , Células Madre Pluripotentes/citología , Investigación Biomédica TraslacionalRESUMEN
The intestinal mucosal barrier controlling the resident microbiome is dependent on a protective mucus layer generated by goblet cells, impairment of which is a hallmark of the inflammatory bowel disease, ulcerative colitis. Here, we show that IL-18 is critical in driving the pathologic breakdown of barrier integrity in a model of colitis. Deletion of Il18 or its receptor Il18r1 in intestinal epithelial cells (Δ/EC) conferred protection from colitis and mucosal damage in mice. In contrast, deletion of the IL-18 negative regulator Il18bp resulted in severe colitis associated with loss of mature goblet cells. Colitis and goblet cell loss were rescued in Il18bp(-/-);Il18r(Δ/EC) mice, demonstrating that colitis severity is controlled at the level of IL-18 signaling in intestinal epithelial cells. IL-18 inhibited goblet cell maturation by regulating the transcriptional program instructing goblet cell development. These results inform on the mechanism of goblet cell dysfunction that underlies the pathology of ulcerative colitis.
Asunto(s)
Colitis Ulcerosa/patología , Colitis Ulcerosa/fisiopatología , Interleucina-18/inmunología , Animales , Colitis Ulcerosa/inducido químicamente , Colitis Ulcerosa/metabolismo , Sulfato de Dextran , Células Endoteliales/metabolismo , Células Epiteliales/citología , Femenino , Células Caliciformes/metabolismo , Células Caliciformes/patología , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Subunidad alfa del Receptor de Interleucina-18/genética , Subunidad alfa del Receptor de Interleucina-18/metabolismo , Mucosa Intestinal/fisiopatología , Masculino , Ratones , Transducción de SeñalRESUMEN
Airway hillocks are stratified epithelial structures of unknown function1. Hillocks persist for months and have a unique population of basal stem cells that express genes associated with barrier function and cell adhesion. Hillock basal stem cells continually replenish overlying squamous barrier cells. They exhibit dramatically higher turnover than the abundant, largely quiescent classic pseudostratified airway epithelium. Hillocks resist a remarkably broad spectrum of injuries, including toxins, infection, acid and physical injury because hillock squamous cells shield underlying hillock basal stem cells from injury. Hillock basal stem cells are capable of massive clonal expansion that is sufficient to resurface denuded airway, and eventually regenerate normal airway epithelium with each of its six component cell types. Hillock basal stem cells preferentially stratify and keratinize in the setting of retinoic acid signalling inhibition, a known cause of squamous metaplasia2,3. Here we show that mouse hillock expansion is the cause of vitamin A deficiency-induced squamous metaplasia. Finally, we identify human hillocks whose basal stem cells generate functional squamous barrier structures in culture. The existence of hillocks reframes our understanding of airway epithelial regeneration. Furthermore, we show that hillocks are one origin of 'squamous metaplasia', which is long thought to be a precursor of lung cancer.
Asunto(s)
Plasticidad de la Célula , Células Epiteliales , Regeneración , Mucosa Respiratoria , Células Madre , Animales , Femenino , Humanos , Masculino , Ratones , Células Epiteliales/citología , Células Epiteliales/patología , Metaplasia/etiología , Metaplasia/patología , Mucosa Respiratoria/citología , Mucosa Respiratoria/lesiones , Mucosa Respiratoria/patología , Células Madre/citología , Tretinoina/metabolismo , Tretinoina/farmacología , Vitamina A/metabolismo , Vitamina A/farmacología , Neoplasias Pulmonares/etiología , Neoplasias Pulmonares/patología , Ratones Endogámicos C57BLRESUMEN
For many adult human organs, tissue regeneration during chronic disease remains a controversial subject. Regenerative processes are easily observed in animal models, and their underlying mechanisms are becoming well characterized1-4, but technical challenges and ethical aspects are limiting the validation of these results in humans. We decided to address this difficulty with respect to the liver. This organ displays the remarkable ability to regenerate after acute injury, although liver regeneration in the context of recurring injury remains to be fully demonstrated. Here we performed single-nucleus RNA sequencing (snRNA-seq) on 47 liver biopsies from patients with different stages of metabolic dysfunction-associated steatotic liver disease to establish a cellular map of the liver during disease progression. We then combined these single-cell-level data with advanced 3D imaging to reveal profound changes in the liver architecture. Hepatocytes lose their zonation and considerable reorganization of the biliary tree takes place. More importantly, our study uncovers transdifferentiation events that occur between hepatocytes and cholangiocytes without the presence of adult stem cells or developmental progenitor activation. Detailed analyses and functional validations using cholangiocyte organoids confirm the importance of the PI3K-AKT-mTOR pathway in this process, thereby connecting this acquisition of plasticity to insulin signalling. Together, our data indicate that chronic injury creates an environment that induces cellular plasticity in human organs, and understanding the underlying mechanisms of this process could open new therapeutic avenues in the management of chronic diseases.
Asunto(s)
Transdiferenciación Celular , Hepatocitos , Hepatopatías , Hígado , Humanos , Sistema Biliar/citología , Sistema Biliar/metabolismo , Sistema Biliar/patología , Biopsia , Plasticidad de la Célula , Enfermedad Crónica , Progresión de la Enfermedad , Células Epiteliales/metabolismo , Células Epiteliales/citología , Células Epiteliales/patología , Hepatocitos/metabolismo , Hepatocitos/citología , Hepatocitos/patología , Insulina/metabolismo , Hígado/patología , Hígado/metabolismo , Hígado/citología , Hepatopatías/patología , Hepatopatías/metabolismo , Regeneración Hepática , Organoides/metabolismo , Organoides/patología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , RNA-Seq , Transducción de Señal , Análisis de la Célula Individual , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
Immune cells rely on transient physical interactions with other immune and non-immune populations to regulate their function1. To study these 'kiss-and-run' interactions directly in vivo, we previously developed LIPSTIC (labelling immune partnerships by SorTagging intercellular contacts)2, an approach that uses enzymatic transfer of a labelled substrate between the molecular partners CD40L and CD40 to label interacting cells. Reliance on this pathway limited the use of LIPSTIC to measuring interactions between CD4+ T helper cells and antigen-presenting cells, however. Here we report the development of a universal version of LIPSTIC (uLIPSTIC), which can record physical interactions both among immune cells and between immune and non-immune populations irrespective of the receptors and ligands involved. We show that uLIPSTIC can be used, among other things, to monitor the priming of CD8+ T cells by dendritic cells, reveal the steady-state cellular partners of regulatory T cells and identify germinal centre-resident T follicular helper cells on the basis of their ability to interact cognately with germinal centre B cells. By coupling uLIPSTIC with single-cell transcriptomics, we build a catalogue of the immune populations that physically interact with intestinal epithelial cells at the steady state and profile the evolution of the interactome of lymphocytic choriomeningitis virus-specific CD8+ T cells in multiple organs following systemic infection. Thus, uLIPSTIC provides a broadly useful technology for measuring and understanding cell-cell interactions across multiple biological systems.