Dada, LA;Welch, LC;Magnani, ND;Ren, Z;Han, H;Brazee, PL;Celli, D;Flozak, AS;Weng, A;Herrerias, MM;Kryvenko, V;Vadász, I;Runyan, CE;Abdala-Valencia, H;Shigemura, M;Casalino-Matsuda, SM;Misharin, AV;Budinger, GRS;Gottardi, CJ;Sznajder, JI;
PMID: 36626234 | DOI: 10.1172/jci.insight.159331
Persistent symptoms and radiographic abnormalities suggestive of failed lung repair are among the most common symptoms in patients with COVID-19 after hospital discharge. In mechanically ventilated patients with ARDS secondary to SARS-CoV-2 pneumonia, low tidal volumes to reduce ventilator-induced lung injury necessarily elevate blood CO2 levels, often leading to hypercapnia. The role of hypercapnia on lung repair after injury is not completely understood. Here, using a mouse model of hypercapnia exposure, cell lineage-tracing, spatial transcriptomics and 3D-cultures, we show that hypercapnia limits β-catenin signaling in AT2 cells, leading to their reduced proliferative capacity. Hypercapnia alters expression of major Wnts in PDGFRα+-fibroblasts from those maintaining AT2 progenitor activity towards those that antagonize β-catenin signaling thereby limiting progenitor function. Constitutive activation of β-catenin signaling in AT2 cells or treatment of organoid cultures with recombinant WNT3A protein bypasses the inhibitory effects of hypercapnia. Inhibition of AT2 proliferation in hypercapnic patients may contribute to impaired lung repair after injury, preventing sealing of the epithelial barrier, increasing lung flooding, ventilator dependency and mortality. .
Yu, P;Deng, W;Bao, L;Qu, Y;Xu, Y;Zhao, W;Han, Y;Qin, C;
PMID: 35094625 | DOI: 10.1177/03009858211071016
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes severe viral pneumonia and is associated with a high fatality rate. A substantial proportion of patients infected by SARS-CoV-2 suffer from mild hyposmia to complete loss of olfactory function, resulting in anosmia. However, the pathogenesis of the olfactory dysfunction and comparative pathology of upper respiratory infections with SARS-CoV-2 are unknown. We describe the histopathological, immunohistochemical, and in situ hybridization findings from rodent models of SARS-CoV-2 infection. The main histopathological findings in the olfactory epithelia of K8-hACE2 Tg mice, hACE2 Tg mice, and hamsters were varying degrees of inflammatory lesions, including disordered arrangement, necrosis, exfoliation, and macrophage infiltration of the olfactory epithelia, and inflammatory exudation. On the basis of these observations, the nasal epithelia of these rodent models appeared to develop moderate, mild, and severe rhinitis, respectively. Correspondingly, SARS-CoV-2 viral RNA and antigen were mainly identified in the olfactory epithelia and lamina propria. Moreover, viral RNA was abundant in the cerebrum of K18-hACE2 Tg mice, including the olfactory bulb. The K8-hACE2 Tg mouse, hACE2 Tg mouse, and hamster models could be used to investigate the pathology of SARS-CoV-2 infection in the upper respiratory tract and central nervous system. These models could help to provide a better understanding of the pathogenic process of this virus and to develop effective medications and prophylactic treatments.
Griffin, B;Warner, B;Chan, M;Valcourt, E;Tailor, N;Banadyga, L;Leung, A;He, S;Boese, A;Audet, J;Cao, W;Moffat, E;Garnett, L;Tierney, K;Tran, K;Albietz, A;Manguiat, K;Soule, G;Bello, A;Vendramelli, R;Lin, J;Deschambault, Y;Zhu, W;Wood, H;Mubareka, S;Safronetz, D;Strong, J;Embury-Hyatt, C;Kobasa, D;
| DOI: 10.1016/j.isci.2021.103530
The golden hamster model of SARS-CoV-2 infection recapitulates key characteristics of COVID-19. In this work we examined the influence of the route of exposure, sex, and age on SARS-CoV-2 pathogenesis in hamsters. We report that delivery of SARS-CoV-2 by a low versus high volume intranasal or intragastric route results in comparable viral titers in the lung and viral shedding. However, low-volume intranasal exposure results in milder weight loss while intragastric exposure leads to a diminished capacity to regain body weight. Male hamsters, and particularly older male hamsters, display an impaired capacity to recover from illness and delayed viral clearance. These factors were found to influence the nature of the host inflammatory cytokine response, but had a minimal effect on the quality and durability of the humoral immune response and susceptibility to re-infection. These data further elucidate key factors that impact pre-clinical challenge studies carried out in the hamster model of COVID-19.
Opposing effects of Wnt/β-catenin signaling on epithelial and mesenchymal cell fate in the developing cochlea
Development (Cambridge, England)
Billings, SE;Myers, NM;Quiruz, L;Cheng, AG;
PMID: 34061174 | DOI: 10.1242/dev.199091
During embryonic development, the otic epithelium and surrounding periotic mesenchymal cells originate from distinct lineages and coordinate to form the mammalian cochlea. Epithelial sensory precursors within the cochlear duct first undergo terminal mitosis before differentiating into sensory and non-sensory cells. In parallel, periotic mesenchymal cells differentiate to shape the lateral wall, modiolus and pericochlear spaces. Previously, Wnt activation was shown to promote proliferation and differentiation of both otic epithelial and mesenchymal cells. Here, we fate-mapped Wnt-responsive epithelial and mesenchymal cells in mice and found that Wnt activation resulted in opposing cell fates. In the post-mitotic cochlear epithelium, Wnt activation via β-catenin stabilization induced clusters of proliferative cells that dedifferentiated and lost epithelial characteristics. In contrast, Wnt-activated periotic mesenchyme formed ectopic pericochlear spaces and cell clusters showing a loss of mesenchymal and gain of epithelial features. Finally, clonal analyses via multi-colored fate-mapping showed that Wnt-activated epithelial cells proliferated and formed clonal colonies, whereas Wnt-activated mesenchymal cells assembled as aggregates of mitotically quiescent cells. Together, we show that Wnt activation drives transition between epithelial and mesenchymal states in a cell type-dependent manner.
A single intranasal or intramuscular immunization with chimpanzee adenovirus vectored SARS-CoV-2 vaccine protects against pneumonia in hamsters
Bricker, T;Darling, T;Hassan, A;Harastani, H;Soung, A;Jiang, X;Dai, Y;Zhao, H;Adams, L;Holtzman, M;Bailey, A;Case, J;Fremont, D;Klein, R;Diamond, M;Boon, A;
| DOI: 10.1016/j.celrep.2021.109400
The development of an effective vaccine against SARS-CoV-2, the etiologic agent of COVID-19, is a global priority. Here, we compared the protective capacity of intranasal and intramuscular delivery of a chimpanzee adenovirus-vectored vaccine encoding a pre-fusion stabilized spike protein (ChAd-SARS-CoV-2-S) in Golden Syrian hamsters. While immunization with ChAd-SARS-CoV-2-S induced robust spike protein specific antibodies capable of neutralizing the virus, antibody levels in serum were higher in hamsters vaccinated by an intranasal compared to intramuscular route. Accordingly, against challenge with SARS-CoV-2, ChAd-SARS-CoV-2-S immunized hamsters were protected against less weight loss and had reduced viral infection in nasal swabs and lungs, and reduced pathology and inflammatory gene expression in the lungs, compared to ChAd-Control immunized hamsters. Intranasal immunization with ChAd-SARS-CoV-2-S provided superior protection against SARS-CoV-2 infection and inflammation in the upper respiratory tract. These findings support intranasal administration of the ChAd-SARS-CoV-2-S candidate vaccine to prevent SARS-CoV-2 infection, disease, and possibly transmission.
Rapid endotheliitis and vascular damage characterize SARS-CoV-2 infection in a human lung-on-chip model
Thacker, VV;Sharma, K;Dhar, N;Mancini, GF;Sordet-Dessimoz, J;McKinney, JD;
PMID: 33908688 | DOI: 10.15252/embr.202152744
Severe cases of SARS-CoV-2 infection are characterized by hypercoagulopathies and systemic endotheliitis of the lung microvasculature. The dynamics of vascular damage, and whether it is a direct consequence of endothelial infection or an indirect consequence of an immune cell-mediated cytokine storm remain unknown. Using a vascularized lung-on-chip model, we find that infection of alveolar epithelial cells leads to limited apical release of virions, consistent with reports of monoculture infection. However, viral RNA and proteins are rapidly detected in underlying endothelial cells, which are themselves refractory to apical infection in monocultures. Although endothelial infection is unproductive, it leads to the formation of cell clusters with low CD31 expression, a progressive loss of barrier integrity and a pro-coagulatory microenvironment. Viral RNA persists in individual cells generating an inflammatory response, which is transient in epithelial cells but persistent in endothelial cells and typified by IL-6 secretion even in the absence of immune cells. Inhibition of IL-6 signalling with tocilizumab reduces but does not prevent loss of barrier integrity. SARS-CoV-2-mediated endothelial cell damage thus occurs independently of cytokine storm.
Yeh I, Lang UE, Durieux E, Tee MK, Jorapur A, Shain AH, Haddad V, Pissaloux D, Chen X, Cerroni L, Judson RL, LeBoit PE, McCalmont TH, Bastian BC, de la Fouchardière A.
PMID: 28935960 | DOI: 10.1038/s41467-017-00758-3
Deep penetrating nevus (DPN) is characterized by enlarged, pigmented melanocytes that extend through the dermis. DPN can be difficult to distinguish from melanoma but rarely displays aggressive biological behavior. Here, we identify a combination of mutations of the β-catenin and mitogen-activated protein kinase pathways as characteristic of DPN. Mutations of the β-catenin pathway change the phenotype of a common nevus with BRAF mutation into that of DPN, with increased pigmentation, cell volume and nuclear cyclin D1 levels. Our results suggest that constitutive β-catenin pathway activation promotes tumorigenesis by overriding dependencies on the microenvironment that constrain proliferation of common nevi. In melanoma that arose from DPN we find additional oncogenic alterations. We identify DPN as an intermediate stage in the step-wise progression from nevus to melanoma. In summary, we delineate specific genetic alterations and their sequential order, information that can assist in the diagnostic classification and grading of these distinctive neoplasms.Deep penetrating nevi (DPN) are unusual melanocytic neoplasms with unknown genetic drivers. Here the authors show that majority of DPN harbor activating mutations in the β-catenin and the MAP-kinase pathways; this characteristic can help in the classification and grading of these distinctive neoplasms.
Cell Host Microbe. 2018 Dec 12.
Lee YS, Kim TY, Kim Y, Lee SH, Kim S, Kang SW, Yang JY, Baek IJ, Sung YH, Park YY, Hwang SW, O E, Kim KS, Liu S, Kamada N, Gao N, Kweon MN.
PMID: 30543778 | DOI: 10.1016/j.chom.2018.11.002
Symbionts play an indispensable role in gut homeostasis, but underlying mechanisms remain elusive. To clarify the role of lactic-acid-producing bacteria (LAB) on intestinal stem-cell (ISC)-mediated epithelial development, we fed mice with LAB-type symbionts such as Bifidobacterium and Lactobacillus spp. Here we show that administration of LAB-type symbionts significantly increased expansion of ISCs, Paneth cells, and goblet cells. Lactate stimulated ISC proliferation through Wnt/β-catenin signals of Paneth cells and intestinal stromal cells. Moreover, Lactobacillus plantarum strains lacking lactate dehydrogenase activity, which are deficient in lactate production, elicited less ISC proliferation. Pre-treatment with LAB-type symbionts or lactate protected mice in response to gut injury provoked by combined treatments with radiation and a chemotherapy drug. Impaired ISC-mediated epithelial development was found in mice deficient of the lactate G-protein-coupled receptor, Gpr81. Our results demonstrate that LAB-type symbiont-derived lactate plays a pivotal role in promoting ISC-mediated epithelial development in a Gpr81-dependent manner.
Zhao B, Chen Y, Jiang N, Yang L, Sun S, Zhang Y, Wen Z, Ray L, Liu H, Hou G, Lin X.
PMID: 30842416 | DOI: 10.1038/s41467-019-09060-w
Lgr5+ stem cells are crucial to gut epithelium homeostasis; however, how these cells are maintained is not fully understood. Zinc finger HIT-type containing 1 (Znhit1) is an evolutionarily conserved subunit of the SRCAP chromosome remodeling complex. Currently, the function of Znhit1 in vivo and its working mechanism in the SRCAP complex are unknown. Here we show that deletion of Znhit1 in intestinal epithelium depletes Lgr5+ stem cells thus disrupts intestinal homeostasis postnatal establishment and maintenance. Mechanistically, Znhit1 incorporates histone variant H2A.Z into TSS region of genes involved in Lgr5+ stem cell fate determination, including Lgr5, Tgfb1 and Tgfbr2, for subsequent transcriptional regulation. Importantly, Znhit1 promotes the interaction between H2A.Z and YL1 (H2A.Z chaperone) by controlling YL1 phosphorylation. These results demonstrate that Znhit1/H2A.Z is essential for Lgr5+ stem cell maintenance and intestinal homeostasis. Our findings identified a dominant role of Znhit1/H2A.Z in controlling mammalian organ development and tissue homeostasis in vivo.
Lav, R;Krivanek, J;Anthwal, N;Tucker, AS;
PMID: 36931279 | DOI: 10.1016/j.stemcr.2023.02.004
Stem cell regulation plays a crucial role during development and homeostasis. Here, an essential source of Wnts from Gli1+ stem/progenitor cells was identified in the murine molar. Loss of Wnt production in Gli1+ apical stem/progenitor cells led to loss of Axin2 at the root apex, mis-regulation of SOX9, loss of BMP and Hh signaling, and truncation of root development. In the absence of Wnt signals, the root epithelium lost its integrity and epithelial identity. This phenotype could be partially mimicked by loss of Sox9 in the Gli1 population. Stabilization of Wnt signaling in the apical papilla led to rapid unordered differentiation of hard tissues and fragmentation of the epithelial root sheath. Wnt signaling from Gli1+ stem/progenitor cells, therefore, orchestrates root development, coordinating mesenchymal and epithelial interactions via SOX9 to regulate stem/progenitor cell expansion and differentiation. Our results demonstrate that disparate stem/progenitor cell populations are unified in their fundamental signaling interactions.
Smith, RJ;Liang, M;Loe, AKH;Yung, T;Kim, JE;Hudson, M;Wilson, MD;Kim, TH;
PMID: 36717563 | DOI: 10.1038/s41467-023-36228-2
Epithelial-mesenchymal signaling in the gastrointestinal system is vital in establishing regional identity during organogenesis and maintaining adult stem cell homeostasis. Although recent work has demonstrated that Wnt ligands expressed by mesenchymal cells are required during gastrointestinal development and stem cell homeostasis, epigenetic mechanisms driving spatiotemporal control of crosstalk remain unknown. Here, we demonstrate that gastrointestinal mesenchymal cells control epithelial fate and function through Polycomb Repressive Complex 2-mediated chromatin bivalency. We find that while key lineage-determining genes possess tissue-specific chromatin accessibility, Polycomb Repressive Complex 2 controls Wnt expression in mesenchymal cells without altering accessibility. We show that reduction of mesenchymal Wnt secretion rescues gastrointestinal fate and proliferation defects caused by Polycomb Repressive Complex 2 loss. We demonstrate that mesenchymal Polycomb Repressive Complex 2 also regulates niche signals to maintain stem cell function in the adult intestine. Our results highlight a broadly permissive chromatin architecture underlying regionalization in mesenchymal cells, then demonstrate further how chromatin architecture in niches can influence the fate and function of neighboring cells.
The circadian clock gene, Bmal1, regulates intestinal stem cell signaling and represses tumor initiation
Cellular and molecular gastroenterology and hepatology
Stokes, K;Nunes, M;Trombley, C;Flôres, DEFL;Wu, G;Taleb, Z;Alkhateeb, A;Banskota, S;Harris, C;Love, OP;Khan, WI;Rueda, L;Hogenesch, JB;Karpowicz, P;
PMID: 34534703 | DOI: 10.1016/j.jcmgh.2021.08.001
Circadian rhythms are daily physiological oscillations driven by the circadian clock: a 24-hour transcriptional timekeeper that regulates hormones, inflammation, and metabolism. Circadian rhythms are known to be important for health, but whether their loss contributes to colorectal cancer is not known.We tested the non-redundant clock gene, Bmal1, in intestinal homeostasis and tumorigenesis, using the Apcmin model of colorectal cancer.Bmal1 mutant, epithelium-conditional Bmal1 mutant, and photoperiod-disrupted mice bearing the Apcmin allele were assessed for tumorigenesis. Tumors and normal non-transformed tissue were characterized. Intestinal organoids were assessed for circadian transcription rhythms by RNA-sequencing, and in vivo and organoid assays were used to test Bmal1-dependent proliferation and self-renewal.Loss of Bmal1 or circadian photoperiod increases tumor initiation. In the intestinal epithelium the clock regulates transcripts involved in regeneration and intestinal stem cell signaling. Tumors have no self-autonomous clock function and only weak clock function in vivo. Apcmin clock-disrupted tumors exhibit high Yap (Hippo signaling) activity but exhibit low Wnt activity. Intestinal organoid assays reveal that loss of Bmal1 increases self-renewal in a Yap-dependent manner.Bmal1 regulates intestinal stem cell pathways, including Hippo signaling, and the loss of circadian rhythms potentiates tumor initiation.
