Epithelial-mesenchymal Crosstalk Research Articles

O13 Benchmarking a human pluripotent stem cell-derived hair-bearing skin organoid model to prenatal skin

Abstract Introduction and aims Molecular regulation of mammalian skin development has been largely derived from murine studies. The lack of human studies stems primarily from the difficulties in prenatal human skin access. There is an important need to study human prenatal skin owing to the notable differences between human and mouse skin and the paucity of mechanistic understanding of congenital skin disorders. Methods We assembled the first comprehensive multiomic reference atlas of prenatal human skin (21 samples from 7 to 16 postconception weeks), combining single-cell (235 201 cells) and spatial transcriptomic data. We followed 84 skin organoids (SkOs) using single-cell analysis over a 5-month culture period and characterized the spatial organization of the skin in mature SkOs. Prenatal skin, SkO and any relevant pre-existing single-cell RNA-Seq datasets were integrated into the analysis. Cell–cell interactions and cell-lineage determination were explored using CellPhoneDB and trajectory inferences. We evaluated the differentiation trajectory alignment between prenatal skin and SkO using the Genes2Genes analysis. Results Our findings reveal predicted factors regulating the epithelial–mesenchymal crosstalk during human hair follicle formation; progressive expression of scar-promoting genes in later gestation, potentially contributing to scarless healing properties of human prenatal skin observed during the early stages of gestation and expression of genes causing genetic skin disorders in the same cell types in prenatal human skin and SkO. We also found that SkOs morphologically recapitulate human skin development from early (periderm formation and shedding) to late (cornification and hair follicle formation) stages. We also demonstrated that SkO and prenatal skin mesenchyme differentiation into hair follicle dermal condensate and dermal papilla is highly conserved at the cellular and molecular level. Conclusions SkOs faithfully recapitulate human prenatal skin development and are a valuable model for mechanistic studies on skin development including hair follicle biology and congenital skin disorders.

NR2F2 alleviates pulmonary fibrosis by inhibition of epithelial cell senescence

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fatal, and aging-associated interstitial lung disease with a poor prognosis and limited treatment options, while the pathogenesis remains elusive. In this study, we found that the expression of nuclear receptor subfamily 2 group F member 2 (NR2F2), a member of the steroid thyroid hormone superfamily of nuclear receptors, was reduced in both IPF and bleomycin-induced fibrotic lungs, markedly in bleomycin-induced senescent epithelial cells. Inhibition of NR2F2 expression increased the expression of senescence markers such as p21 and p16 in lung epithelial cells, and activated fibroblasts through epithelial-mesenchymal crosstalk, inversely overexpression of NR2F2 alleviated bleomycin-induced epithelial cell senescence and inhibited fibroblast activation. Subsequent mechanistic studies revealed that overexpression of NR2F2 alleviated DNA damage in lung epithelial cells and inhibited cell senescence. Adenovirus-mediated Nr2f2 overexpression attenuated bleomycin-induced lung fibrosis and cell senescence in mice. In summary, these data demonstrate that NR2F2 is involved in lung epithelial cell senescence, and targeting NR2F2 may be a promising therapeutic approach against lung cell senescence and fibrosis.

Human iPSC-Based Model of COPD to Investigate Disease Mechanisms, Predict SARS-COV-2 Outcome, and Test Preventive Immunotherapy.

Chronic inflammation and dysregulated repair mechanisms after epithelial damage have been implicated in chronic obstructive pulmonary disease (COPD). However, the lack of ex vivo-models that accurately reflect multicellular lung tissue hinders our understanding of epithelial-mesenchymal interactions in COPD. Through a combination of transcriptomic and proteomic approaches applied to a sophisticated in vitro iPSC-alveolosphere with fibroblasts model, epithelial-mesenchymal crosstalk was explored in COPD and following SARS-CoV-2 infection. These experiments profiled dynamic changes at single-cell level of the SARS-CoV-2-infected alveolar niche that unveiled the complexity of aberrant inflammatory responses, mitochondrial dysfunction, and cell death in COPD, which provides deeper insights into the accentuated tissue damage/inflammation/remodeling observed in patients with SARS-CoV-2 infection. Importantly, this 3D system allowed for the evaluation of ACE2-neutralizing antibodies and confirmed the potency of this therapy to prevent SARS-CoV-2 infection in the alveolar niche. Thus, iPSC-alveolosphere cultured with fibroblasts provides a promising model to investigate disease-specific mechanisms and to develop novel therapeutics.

TRIOBP modulates β-catenin signaling by regulation of miR-29b in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal and devastating lung disease of unknown etiology, described as the result of multiple cycles of epithelial cell injury and fibroblast activation. Despite this impressive increase in understanding, a therapy that reverses this form of fibrosis remains elusive. In our previous study, we found that miR-29b has a therapeutic effect on pulmonary fibrosis. However, its anti-fibrotic mechanism is not yet clear. Recently, our study identified that F-Actin Binding Protein (TRIOBP) is one of the target genes of miR-29b and found that deficiency of TRIOBP increases resistance to lung fibrosis in vivo. TRIOBP knockdown inhibited the proliferation of epithelial cells and attenuated the activation of fibroblasts. In addition, deficiency of Trio Rho Guanine Nucleotide Exchange Factor (TRIO) in epithelial cells and fibroblasts decreases susceptibility to lung fibrosis. TRIOBP interacting with TRIO promoted abnormal epithelial–mesenchymal crosstalk and modulated the nucleocytoplasmic translocation of β-catenin. We concluded that the miR-29b‒TRIOBP–TRIO–β-catenin axis might be a key anti-fibrotic axis in IPF to regulate lung regeneration and fibrosis, which may provide a promising treatment strategy for lung fibrosis.Graphical

HES1 deficiency impairs development of human intestinal mesenchyme by suppressing WNT5A expression

Serious intestinal side-effects that target the NOTCH-HES1 pathway in human cancer differentiation therapy make it necessary to understand the pathway at the human organ level. Herein, we endogenously introduced HES1−/− mutations into human embryonic stem cells (hESCs) and differentiated them into human intestinal organoids (HIO). The HES1−/− hESCs retained ES cell properties and showed gene expression patterns similar to those of wild-type hESCs when they differentiated into definitive endoderm and hindgut. During the formation of the HES1−/− lumen we noted an impaired development of mesenchymal cells in addition to the increased differentiation of secretory epithelium. RNA-Seq revealed that inhibited development of the mesenchymal cells may have been due to a downregulation of WNT5A signaling. Overexpression of HES1 and silencing of WNT5A in the intestinal fibroblast cell line CCD-18Co indicated that HES1 was involved in the activation of WNT5A-induced fibroblast growth and migration, suggesting the likelihood of the Notch pathway in epithelial-mesenchymal crosstalk. Our results facilitated the identification of more precise underlying molecular mechanisms displaying distinct roles in HES1 signaling in stromal and epithelial development in human intestinal mucosa.

368 Epithelial-mesenchymal crosstalk communication promotes fibroblast activation and fibrosis in RDEB

368 Epithelial-mesenchymal crosstalk communication promotes fibroblast activation and fibrosis in RDEB

TRIB3 Mediates Fibroblast Activation and Fibrosis though Interaction with ATF4 in IPF.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by fibroblast activation, excessive deposition of extracellular matrix, and progressive scarring; the pathogenesis remains elusive. The present study explored the role of Tribbles pseudokinase 3 (TRIB3), a well-known stress and metabolic sensor, in IPF. TRIB3 is down-regulated in the lungs of IPF patients in comparison to control subjects. Deficiency of TRIB3 markedly inhibited A549 epithelial cells' proliferation and migration, significantly reducing wound healing. Conversely, overexpression of TRIB3 promoted A549 cell proliferation and transmigration while it inhibited its apoptosis. Meanwhile, overexpressed TRIB3 inhibited fibroblast activation and decreased ECM synthesis and deposition in MRC5 cells. TRIB3 attenuated pulmonary fibrosis by negative regulation of ATF4, while TRIB3 expression markedly inhibited ATF4 promoter-driven transcription activity and down-regulated ATF4 expression. A co-culture system showed that TRIB3 is important to maintain the normal epithelial-mesenchymal crosstalk and regulate fibroblast activation. Taken together, our data suggested that an axis of TRIB3-ATF4 is a key mediator in IPF which might be a potential target for fibroproliferative lung disease treatment.

The potential role of interleukin (IL)-25/IL-33/thymic stromal lymphopoietin (TSLP) on the pathogenesis of idiopathic pulmonary fibrosis.

Interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin (TSLP) are the important drivers for excessive type-2 immunity. It has been well elucidated that IL-25/IL-33/TSLP plays an important role in allergic airway inflammation and remodeling, whereas their roles in idiopathic pulmonary fibrosis (IPF) still remained largely unclear. Herein, the aim of the review is to discuss the potential role and mechanism of IL-25/IL-33/TSLP on IPF by literature analysis and summary. We have done a literature search using the following terms: ("idiopathic pulmonary fibrosis" OR "IPF" OR "lung fibrosis") and (TSLP or "thymic stromal lymphopoietin" or IL-25 OR IL-17E OR IL-33) from the database of PubMed published in English up to July 2018. We have totally found 58 articles by using the retrieval terms mentioned above. By careful title and abstract reading, 10 original research articles of high quality were enrolled for the full text reading and analysis. Two additional relevant studies were also included during the course of literature readings. IL-25/IL-33/TSLP and their corresponding receptors, that is, IL-17BR/ST2L/TSLPR, are shown to be up-regulated both in IPF patients and bleomycin (BLM)-induced lung fibrosis mice model. IL-25 may promote lung fibrosis by activating IL-17BR+fibroblast and IL-17BR+ILC2 (type 2 innate lymphoid cell). Full length (fl)-IL-33, as a transcription factor mainly in the cell nucleus, mediated non-atopic lung inflammation and fibrosis by modulating expressions of several pro-fibrotic mediators, including transforming growth factor (TGF)-b1. By contrast, mature (m)-IL-33 potentiates lung fibrosis by recruiting ST2L+M2 macrophages and ST2L+ILC2 to enlarge type 2 immunity. TSLP was shown to directly promote CCL2 expression in primary human lung fibroblasts (pHLFs). IL-25/IL-33/TSLP contributes to non-allergic lung fibrosis by mediating persistent abnormal epithelial-mesenchymal crosstalk. IL-25/IL-33/TSLP may serve the promising novel target for the treatment of IPF.

LB1012 Dermal sheath mechanosignaling activation of TGF-β controls progenitor death during hair follicle regression

Epithelial-mesenchymal crosstalk is vital for balancing expansion and regression of the progenitor cell pool during tissue turnover. In the hair growth cycle, little is known about the mechanisms underlying the regulated cell death during follicle regression that precedes each regeneration and hair re-growth. Here, we discover that the dermal sheath smooth muscle, which lines all follicles, controls progenitor death via transforming growth factor (TGF)-β mechanosignaling. The sheath secretes TGF-β, which is first stored as an inactive, latent complex in the basement membrane extracellular matrix. The sheath then contracts to free TGF-β for essential signaling to progenitors for cell death regulation and regression. Finally, we identify Integrin-alpha-V on the sheath surface as the molecular link for force-mediated TGF-β release. Our study establishes the dermal sheath as a mechanosignaling niche that controls progenitor pool reduction through mechanical force, signal activation and cell-cell communication.

Regeneration or Repair? The Role of Alveolar Epithelial Cells in the Pathogenesis of Idiopathic Pulmonary Fibrosis (IPF).

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) with unknown etiology in which gradual fibrotic scarring of the lungs leads to usual interstitial pneumonia (UIP) and, ultimately, to death. IPF affects three million people worldwide, and the only currently available treatments include the antifibrotic drugs nintedanib and pirfenidone, which effectively reduce fibrosis progression are, unfortunately, not effective in curing the disease. In recent years, the paradigm of IPF pathogenesis has shifted from a fibroblast-driven disease to an epithelium-driven disease, wherein, upon recurrent microinjuries, dysfunctional alveolar type II epithelial cells (ATII) are not only unable to sustain physiological lung regeneration but also promote aberrant epithelial–mesenchymal crosstalk. This creates a drift towards fibrosis rather than regeneration. In the context of this review article, we discuss the most relevant mechanisms involved in IPF pathogenesis with a specific focus on the role of dysfunctional ATII cells in promoting disease progression. In particular, we summarize the main causes of ATII cell dysfunction, such as aging, environmental factors, and genetic determinants. Next, we describe the known mechanisms of physiological lung regeneration by drawing a parallel between embryonic lung development and the known pathways involved in ATII-driven alveolar re-epithelization after injury. Finally, we review the most relevant interventional clinical trials performed in the last 20 years with the aim of underlining the urgency of developing new therapies against IPF that are not only aimed at reducing disease progression by hampering ECM deposition but also boost the physiological processes of ATII-driven alveolar regeneration.

C/EBP homologous protein promotes Sonic Hedgehog secretion from type II alveolar epithelial cells and activates Hedgehog signaling pathway of fibroblast in pulmonary fibrosis

BackgroundEndoplasmic reticulum (ER) stress is involved in the pathological process of pulmonary fibrosis, including IPF. It affects a broad scope of cellular types during pulmonary fibrosis but the role in epithelial-mesenchymal crosstalk has not been fully defined. The present study aimed to investigate the effects of Shh secretion by ER stress-challenged type II alveolar epithelial cells (AECII) on fibroblast and pulmonary fibrosis.MethodsConditioned medium (CM) from tunicamycin (TM)-treated AECII was collected and incubated with fibroblast. Short hairpin RNA (shRNA) was used for RNA interference of C/EBP homologous protein (CHOP). The effects of CHOP and HH signaling were evaluated by TM administration under the background of bleomycin-induced pulmonary fibrosis in mice.ResultsBoth expression of CHOP and Shh in AECII, and HH signaling in mesenchyme were upregulated in IPF lung. TM-induced Shh secretion from AECII activates HH signaling and promotes pro-fibrotic effects of fibroblast. Interfering CHOP expression reduced ER stress-induced Shh secretion and alleviated pulmonary fibrosis in mice.ConclusionsOur work identified a novel mechanism by which ER stress is involved in pulmonary fibrosis. Inhibition of ER stress or CHOP in epithelial cells alleviated pulmonary fibrosis by suppressing Shh/HH signaling pathway of fibroblasts.

Expression of Concern: miR-130b-3p Modulates Epithelial-Mesenchymal Crosstalk in Lung Fibrosis by Targeting IGF-1.

Expression of Concern: miR-130b-3p Modulates Epithelial-Mesenchymal Crosstalk in Lung Fibrosis by Targeting IGF-1.

Parallels in signaling between development and regeneration in ectodermal organs.

Ectodermal organs originate from the outermost germ layer of the developing embryo and include the skin, hair, tooth, nails, and exocrine glands. These organs develop through tightly regulated, sequential and reciprocal epithelial-mesenchymal crosstalk, and they eventually assume various morphologies and functions while retaining the ability to regenerate. As with many other tissues in the body, the development and morphogenesis of these organs are regulated by a set of common signaling pathways, such as Shh, Wnt, Bmp, Notch, Tgf-β, and Eda. However, subtle differences in the temporal activation, the multiple possible combinations of ligand-receptor activation, the various cofactors, as well as the underlying epigenetic modulation determine how each organ develops into its adult form. Although each organ has been studied separately in considerable detail, the mechanisms underlying the parallels and differences in signaling that regulate their development have rarely been investigated. First, we will use the tooth, the hair follicle, and the mammary gland as representative ectodermal organs to explore how the development of signaling centers and establishment of stem cell populations influence overall growth and morphogenesis. Then we will compare how some of the major signaling pathways (Shh, Wnt, Notch and Yap/Taz) differentially regulate developmental events. Finally, we will discuss how signaling regulates regenerative processes in all three.

The critical role of nuclear factor I-C in tooth development.

Nuclear factor I-C (NFIC) plays a critical role in regulating epithelial-mesenchymal crosstalk during tooth development. However, it remains largely unknown about how NFIC functions in dentin and enamel formation. In the present review, we aim to summarize the most recent discoveries in the field and gain a better understanding of the roles NFIC performs during tooth formation. Nfic-/- mice exhibit human dentin dysplasia type I (DDI)-like phenotypes signified by enlarged pulp chambers, the presence of short-root anomaly, and failure of odontoblast differentiation. Although loss of NFIC has little effect on molar crown morphology, researchers have detected aberrant microstructures of enamel in the incisors. Recently, accumulating evidence has further uncovered the novel function of NFIC in the process of enamel and dentin formation. During epithelial-mesenchyme crosstalk, the expression of NFIC is under the control of SHH-PTCH-SMO-GLI1 pathway. NFIC is closely involved in odontoblast lineage cells proliferation and differentiation, and the maintenance of NFIC protein level in cytoplasm is negatively regulated by TGF-β signaling pathway. In addition, NFIC has mild effect on ameloblast differentiation, enamel mineralization and cementum formation. NFIC plays an important role in tooth development and is required for the formation of dentin, enamel as well as cementum.

Bidirectional epithelial–mesenchymal crosstalk provides self-sustaining profibrotic signals in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the prototypic progressive fibrotic lung disease with a median survival of 2 to 4 years. Injury to and/or dysfunction of the alveolar epithelium is strongly implicated in IPF disease initiation, but the factors that determine whether fibrosis progresses rather than normal tissue repair occurs remain poorly understood. We previously demonstrated that zinc finger E-box-binding homeobox 1–mediated epithelial–mesenchymal transition in human alveolar epithelial type II (ATII) cells augments transforming growth factor-β–induced profibrogenic responses in underlying lung fibroblasts via paracrine signaling. Here, we investigated bidirectional epithelial–mesenchymal crosstalk and its potential to drive fibrosis progression. RNA-Seq of lung fibroblasts exposed to conditioned media from ATII cells undergoing RAS-induced epithelial–mesenchymal transition identified many differentially expressed genes including those involved in cell migration and extracellular matrix regulation. We confirmed that paracrine signaling between RAS-activated ATII cells and fibroblasts augmented fibroblast recruitment and demonstrated that this involved a zinc finger E-box-binding homeobox 1–tissue plasminogen activator axis. In a reciprocal fashion, paracrine signaling from transforming growth factor-β–activated lung fibroblasts or IPF fibroblasts induced RAS activation in ATII cells, at least partially through the secreted protein acidic and rich in cysteine, which may signal via the epithelial growth factor receptor via epithelial growth factor–like repeats. Together, these data identify that aberrant bidirectional epithelial–mesenchymal crosstalk in IPF drives a chronic feedback loop that maintains a wound-healing phenotype and provides self-sustaining profibrotic signals.

Quantification of Cytokines in Lip Tissue from Infants Affected by Congenital Cleft Lip and Palate.

Cleft lip and palate are amongst the most common congenital malformations worldwide presenting with variable manifestations. Previous research has been primarily focused on the genetical aspects of its complex and multifactorial etiology. In the present study, we investigated the role of cytokines as mediators of epithelial–mesenchymal crosstalk and local site inflammation in cleft affected infants. Lip material was obtained from 12 children aged before primary dentition who suffered from orofacial clefting. The quantification of 12 cytokines (Interleukin-2,4,5,6,10,12,13,17A, Tumor Necrosis Factor-α, Interferon-γ, Transforming Growth Factor beta-1 and Granulocyte-Colony Stimulating Factor) was done using ELISA. Nonparametric Spearman Rho was used to ascertain the correlation between the expression levels of different cytokines. A significantly strong positive correlation was found between IL-2 and IFN-γ coupled with an IL4/IFN-γ ratio favoring IFN-γ. These findings indicate a shift towards the preferential activation of the Th1 differentiation pathway. Further, a pathological reduction in TGFβ-1 levels was noted, which may contribute to mucosal damage. IL-6 was more highly correlated to IFN-γ and IL-12 indicating its potential proinflammatory role in cleft affected tissues. This preferential activation of Th1 cell differentiation and consistent expression of IL-2,6,13 and TNF-α in cleft patients may indicate certain underlying mechanisms for inflammation mediation at the site of clefting.

The role of S100A4 for bone metastasis in prostate cancer cells

BackgroundProstate cancers frequently metastasize to bone, where the best microenvironment for distant colonization is provided. Since osteotropic metastasis of prostate cancer is a critical determinant of patients’ survival, searches for preventive measures are ongoing in the field. Therefore, it is important to dissect the mechanisms of each step of bone metastasis, including the epithelial-mesenchymal transition (EMT) and cross-talk between metastatic niches and cancer cells.MethodsIn this study, we established a highly bone-metastatic subline of human prostate cancer cells by selecting bone-homing population of PC3 cells after cardiac injection of eight-week-old male BALB/c-nude mice. Then we assessed the proliferation, EMT characteristics, and migration properties of the subline (mtPC3) cells in comparison with the parental PC3 cells. To investigate the role of S100A4, we performed gene knock-down by lentiviral transduction, or treated cells with recombinant S100A4 protein or a S100A4-neutralizing antibody. The effect of cancer cells on osteoclastogenesis was evaluated after treatment of pre-osteoclasts with conditioned medium (CM) from cancer cells.ResultsThe mtPC3 cells secreted a markedly high level of S100A4 protein and showed elevated cell proliferation and mesenchymal properties. The increased proliferation and EMT traits of mtPC3 cells was inhibited by S100A4 knock-down, but was not affected by exogenous S100A4. Furthermore, S100A4 released from mtPC3 cells stimulated osteoclast development via the cell surface receptor RAGE. Down-regulation or neutralization of S100A4 in the CM of mtPC3 cells attenuated cancer-induced osteoclastogenesis.ConclusionAltogether, our results suggest that intracellular S100A4 promotes cell proliferation and EMT characteristics in tumor cells, and that secreted S100A4 activates osteoclastogenesis, contributing to osteolytic bone metastasis. Thus, S100A4 upregulation in cancer cells highly metastatic to bone might be a key element in regulating bone metastasis.

Desmoplastic Crosstalk in Pancreatic Ductal Adenocarcinoma Is Reflected by Different Responses of Panc-1, MIAPaCa-2, PaTu-8902, and CAPAN-2 Cell Lines to Cancer-associated/Normal Fibroblasts.

Pancreatic ductal adenocarcinoma (PDAC) still represents one of the most aggressive cancers. Understanding of the epithelial-mesenchymal crosstalk as a crucial part of the tumor microenvironment should pave the way for therapies to improve patient survival rates. Well-established cell lines present a useful and reproducible model to study PDAC biology. However, the tumor-stromal interactions between cancer cells and cancer-associated fibroblasts (CAFs) are still poorly understood. We studied interactions between four PDAC cell lines (Panc-1, CAPAN-2, MIAPaCa-2, and PaTu-8902) and conditioned media derived from primary cultures of normal fibroblasts/PDAC-derived CAFs (PANFs). When the tested PDAC cell lines were stimulated by PANF-derived conditioned media, the most aggressive behavior was acquired by the Panc-1 cell line (increased number and size of colonies, remaining expression of vimentin and keratin 8 as well as increase of epithelial-to-mesenchymal polarization markers), whereas PaTu-8902 cells were rather inhibited. Of note, administration of the conditioned media to MIAPaCa-2 cells resulted in an inverse effect on the size and number of colonies, whereas CAPAN-2 cells were rather stimulated. To explain the heterogeneous pattern of the observed PDAC crosstalk at the in vitro level, we further compared the phenotype of primary cultures of cells derived from ascitic fluid with that of the tested PDAC cell lines, analyzed tumor samples of PDAC patients, and performed gene expression profiling of PANFs. Immuno-cyto/histo-chemical analysis found specific phenotype differences within the group of examined patients and tested PDAC cell lines, whereas the genomic approach in PANFs found the key molecules (IL6, IL8, MFGE8 and periostin) that may contribute to the cancer aggressive behavior. The desmoplastic patient-specific regulation of cancer cells by CAFs (also demonstrated by the heterogeneous response of PDAC cell lines to fibroblasts) precludes simple targeting and development of an effective treatment strategy and rather requires establishment of an individualized tumor-specific treatment protocol.

Snail-mediated partial epithelial mesenchymal transition augments the differentiation of local lung myofibroblast

The pathogenesis of pulmonary fibrosis diseases is considered to be related with environmental exposures, but the exact mechanism is unclear and there are no effective treatments. The contribution of epithelial-mesenchymal transition (EMT) to lung fibrosis has been controversial. It was found that partial EMT might play a vital role in renal fibrosis. We also found that partial EMT might be involved in fibrosis diseases. In this study, we used a silicosis animal model of pulmonary fibrosis to observe whether partial EMT existed in pulmonary fibrosis disease and a co-culture system culturing fibroblasts and alveolar epithelial cells stimulated by TGF-β1 to evaluate the probable effects of partial EMT, thus determined the probable role of partial EMT in pulmonary fibrosis diseases. In vivo, the results revealed that partial EMT might exist in silica-induced lung fibrosis model and Snail which is a potent EMT inducer was involved during the process. In vitro, a co-culture system was used to evaluate the effects of EMT in murine alveolar epithelial type II (ATII) cells on the activation of underlying murine lung fibroblasts into myofibroblasts. The results showed that epithelial cells undergoing EMT promoted the differentiation of lung myofibroblast and this epithelial-mesenchymal crosstalk was mainly controlled by Snail. Following Snail silencing the EMT and the activation of NIH-3T3 into myofibroblast were obviously inhibited. It indicated that targeting this novel Snail might be a viable strategy for the treatment of lung fibrosis diseases.

Distinct Regulatory Programs Control the Latent Regenerative Potential of Dermal Fibroblasts during Wound Healing.

Dermal fibroblasts exhibit considerable heterogeneity during homeostasis and in response to injury. Defining lineage origins of reparative fibroblasts and regulatory programs that drive fibrosis or, conversely, promote regeneration will be essential for improving healing outcomes. Using complementary fate-mapping approaches, we show that hair follicle mesenchymal progenitors make limited contributions to wound repair. In contrast, extrafollicular progenitors marked by the quiescence-associated factor Hic1 generated the bulk of reparative fibroblasts and exhibited functional divergence, mediating regeneration in the center of the wound neodermis and scar formation in the periphery. Single-cell RNA-seq revealed unique transcriptional, regulatory, and epithelial-mesenchymal crosstalk signatures that enabled mesenchymal competence for regeneration. Integration with scATAC-seq highlighted changes in chromatin accessibility within regeneration-associated loci. Finally, pharmacological modulation of RUNX1 and retinoic acid signaling or genetic deletion of Hic1 within wound-activated fibroblasts was sufficient to modulate healing outcomes, suggesting that reparative fibroblasts have latent but modifiable regenerative capacity.