Basal Cells Research Articles

A hybrid epithelial-mesenchymal transition program enables basal epithelial cells to bypass stress-induced stasis and contributes to a metaplastic breast cancer progenitor state

BackgroundHuman mammary epithelial cell (HMEC) cultures encounter a stress-associated barrier termed stasis, during which most cells adopt a senescence-like phenotype. From these cultures, rare variants emerge from the basal epithelial population, re-initiating growth. Variants exhibit pre-malignant properties, including an aberrant epigenetic program that enables continued proliferation and acquisition of genetic changes. Following oncogenic transformation, variants produce tumors that recapitulate the histopathological characteristics of metaplastic breast cancer (MBC), a rare and aggressive subtype marked by the differentiation of neoplastic epithelium into squamous and mesenchymal elements.MethodsUsing a serum-free HMEC culture system, we probed the capacity for phenotypic plasticity inherent to basal epithelial cell populations from human breast tissue as they navigated stasis and emerged as variant populations.ResultsWe observed robust activation of a TGF-β-dependent epithelial-mesenchymal transition (EMT) program in basal epithelial cells during stasis, followed by subsequent attenuation of this program in emerging variants. Inhibition of the TGF-β pathway or depleting the EMT regulators Snail or Slug allowed basal epithelial cells to collectively bypass stasis, demonstrating that cellular dysfunction and arrest resulting from TGF-β and EMT activation are central to this in vitro barrier. The spontaneous emergence of variants from stasis cultures was associated with a restricted EMT trajectory, characterized by the stabilization of hybrid EMT states associated with greater proliferative capacity, rather than progressing to a complete mesenchymal state characterized by irreversible growth arrest. Epigenetic mechanisms, which contributed to the dysregulated growth control characteristic of the variant phenotype, also contributed to the stability of the hybrid EMT program in variants. By overcoming the cellular dysfunction and growth arrest resulting from TGF-β and complete EMT, variants exhibited a higher oncogenic transformation efficiency compared to pre-stasis basal epithelial cells. Inhibiting the TGF-β pathway prior to stasis significantly reduced EMT in the basal epithelial population, alleviated selective pressure driving variant emergence, and also enhanced oncogenic transformation efficiency, resulting in tumors with markedly diminished metaplastic differentiation.ConclusionsThis study reveals how an epigenetic program governs basal epithelial cell fate decisions and contributes to the development of MBC progenitors by restricting access to terminal mesenchymal states that induce growth arrest and, instead, favoring hybrid EMT states with enhanced tumorigenic potential.

Collagen signaling and matrix stiffness regulate multipotency in glandular epithelial stem cells in mice

Glandular epithelia, including mammary gland (MG) and prostate, are composed of luminal and basal cells. During embryonic development, glandular epithelia arise from multipotent stem cells (SCs) that are replaced after birth by unipotent basal and unipotent luminal SCs. Different conditions, such as basal cell transplantation, luminal cell ablation, and oncogene expression can reinduce adult basal SC (BaSCs) multipotency in different glandular epithelia. The mechanisms regulating the reactivation of multipotency are incompletely understood. Here, we have found that Collagen I expression is commonly upregulated in BaSCs across the different multipotent conditions. Increasing collagen concentration or stiffness of the extracellular matrix (ECM) promotes BaSC multipotency in MG and prostate organoids. Single cell RNA-seq of MG organoids in stiff conditions have uncovered the importance of β1 integrin/FAK/AP-1 axis in the regulation of BaSC multipotency. Altogether our study uncovers the key role of Collagen signaling and ECM stiffness in the regulation of multipotency in glandular epithelia.

Basal cell carcinoma: A report of a case in the upper lip

Basal cell carcinoma (BCC) is a malignant epithelial tumor that develops from the basal cell layer of the epidermis. It is predominantly found in older adults, with a high incidence in people aged 40 to 80. This form of cancer rarely metastasizes but is known to be locally invasive. In this report, we present a case of a 43-year-old male with a swelling on his upper lip. After thorough clinical, histopathological, and imaging assessments, a BCC was confirmed. He underwent full excision of the lesion with the surrounding tissue to ensure clear margins.

Lysyl Oxidase Mediates Proliferation and Differentiation in the Esophageal Epithelium

In homeostatic conditions, the basal progenitor cells of the esophagus differentiate into a stratified squamous epithelium. However, in the setting of acid exposure or inflammation, there is a marked failure of basal cell differentiation, leading to basal cell hyperplasia. We have previously shown that lysyl oxidase (LOX), a collagen crosslinking enzyme, is upregulated in the setting of allergic inflammation of the esophagus; however, its role beyond collagen crosslinking is unknown. Herein, we propose a non-canonical epithelial-specific role of LOX in the maintenance of epithelial homeostasis using 3D organoid and murine models. We performed quantitative reverse transcriptase PCR, Western blot, histologic analysis, and RNA sequencing on immortalized non-transformed human esophageal epithelial cells (EPC2-hTERT) with short-hairpin RNA (shRNA) targeting LOX mRNA in both monolayer and 3D organoid culture. A novel murine model with a tamoxifen-induced Lox knockout specific to the stratified epithelium (K5CreER; Loxfl/fl) was utilized to further define the role of epithelial LOX in vivo. We found that LOX knockdown decreased the proliferative capacity of the esophageal epithelial cells in monolayer culture, and dramatically reduced the organoid formation rate (OFR) in the shLOX organoids. LOX knockdown was associated with decreased expression of the differentiation markers filaggrin, loricrin, and involucrin, with RNA sequencing analysis revealing 1224 differentially expressed genes demonstrating downregulation of pathways involved in cell differentiation and epithelial development. Mice with Lox knockout in their stratified epithelium demonstrated increased basaloid content of their esophageal epithelium and decreased Ki-67 staining compared to the vehicle-treated mice, suggesting reduced differentiation and proliferation in the Lox-deficient epithelium in vivo. Our results demonstrate, both in vivo and in vitro, that LOX may regulate epithelial homeostasis in the esophagus through the modulation of epithelial proliferation and differentiation. Understanding the mechanisms of perturbation in epithelial proliferation and differentiation in an inflamed esophagus could lead to the development of novel treatments that could promote epithelial healing and restore homeostasis.

Multi-physics ensemble modelling of Arctic tundra snowpack properties

Abstract. Sophisticated snowpack models such as Crocus and SNOWPACK struggle to properly simulate profiles of density and specific surface area (SSA) within Arctic snowpacks due to underestimation of wind-induced compaction, misrepresentation of basal vegetation influencing compaction and metamorphism, and omission of water vapour flux transport. To improve the simulation of profiles of density and SSA, parameterisations of snow physical processes that consider the effect of high wind speeds, the presence of basal vegetation, and alternate thermal conductivity formulations were implemented into an ensemble version of the Soil, Vegetation, and Snow version 2 (SVS2-Crocus) land surface model, creating Arctic SVS2-Crocus. The ensemble versions of the default and Arctic SVS2-Crocus were driven with in situ meteorological data and evaluated using measurements of snowpack properties (snow water equivalent, SWE; depth; density; and SSA) at Trail Valley Creek (TVC), Northwest Territories, Canada, over 32 years (1991–2023). Results show that both the default and Arctic SVS2-Crocus can simulate the correct magnitude of SWE (root-mean-square error, RMSE, for both ensembles – 55 kg m−2) and snow depth (default RMSE – 0.22 m; Arctic RMSE – 0.18 m) at TVC in comparison to measurements. Wind-induced compaction within Arctic SVS2-Crocus effectively compacts the surface layers of the snowpack, increasing the density, and reducing the RMSE by 41 % (176 kg m−3 to 103 kg m−3). Parameterisations of basal vegetation are less effective in reducing compaction of basal snow layers (default RMSE – 67 kg m−3; Arctic RMSE – 65 kg m−3), reaffirming the need to consider water vapour flux transport for simulation of low-density basal layers. The top 100 ensemble members of Arctic SVS2-Crocus produced lower continuous ranked probability scores (CRPS) than the default SVS2-Crocus when simulating snow density profiles. The top-performing members of the Arctic SVS2-Crocus ensemble featured modifications that raise wind speeds to increase compaction in snow surface layers and to prevent snowdrift and increase viscosity in basal layers. Selecting these process representations in Arctic SVS2-Crocus will improve simulation of snow density profiles, which is crucial for many applications.

Stem cell expressed CXCR4 regulates tissue composition in the vomeronasal organ.

The vomeronasal organ (VNO) detects signaling molecules that often prompt innate behaviors such as aggression and reproduction. Vomeronasal sensory neurons, classified into apical and basal lineages based on receptor expression, have a limited lifespan and are continuously replaced from a common stem cell niche. Using a combination of single-cell RNA sequencing data, immunofluorescence staining, and lineage tracing, we identified CXCR4 expression in proliferative stem cells and the basal neuronal lineage. Mice with a conditional knockout of Cxcr4 showed an increased number of SOX2-positive proliferative stem cells and enhanced basal neuronal lineage maturation. In addition, computational gene perturbation analysis revealed 87 transcription factors that may contribute to neurogenesis, among which SOX2. Conditional knockout of Cxcr4 did not only disturb neuronal maturation, but also affected non-neuronal cell types, resulting in a decrease of basal lamina lining quiescent stem cells and an increase in sustentacular support cells. Together, these findings enhance our understanding how a common pool of stem cells can give rise to different cell types of the VNO, highlighting the distinct role of CXCR4 in this process.

Human pancreatic cancer single cell atlas reveals association of CXCL10+ fibroblasts and basal subtype tumor cells.

Pancreatic ductal adenocarcinoma (PDAC) patients with tumors enriched for the basal-like molecular subtype exhibit enhanced resistance to standard of care treatments and have significantly worse overall survival (OS) compared to patients with classical subtype enriched tumors. It is important to develop genomic resources, enabling identification of novel putative targets in a statistically rigorous manner. We compiled a single cell RNA sequencing (scRNAseq) atlas of the human pancreas with 229 patient samples, aggregated from publicly available raw data. We mapped cell-type specific scRNAseq gene signatures in bulk RNAseq (n=744) and spatial transcriptomics (ST) (n=22) and performed validation using multiplex immunostaining. Analysis of tumor cells from our scRNAseq atlas revealed nine distinct populations, two of which aligned with the basal subtype, correlating with worse OS in bulk RNAseq. Deconvolution identified one of the basal populations to be the predominant tumor subtype in non-dissociated ST tissues and in vitro tumor cell and patient-derived organoid lines. We discovered a novel enrichment and spatial association of CXCL10+ cancer associated fibroblasts (CAFs) with basal tumor cells. We identified that besides immune cells, ductal cells also express CXCR3, the receptor for CXCL10, suggesting a relationship between these cell types in PDAC tumor microenvironment. We show that our scRNAseq atlas (700,000 cells), integrated with ST data, has increased statistical power and is a powerful resource, allowing for expansion of current subtyping paradigms in PDAC. We uncovered a novel signaling niche marked by CXCL10+ CAFs and basal tumor cells that could be explored for future targeted therapies.

Esophageal submucosal gland duct adenoma: An unrecognised esophageal counterpart of minor salivary gland tumours with frequent BRAF V600E mutations.

Esophageal submucosal gland duct adenoma is an extremely rare benign tumour, with only a few reported cases. We conducted the largest single-centre clinical study of esophageal submucosal gland duct adenoma, examining its molecular mechanisms and clinicopathological features. Between 2018 and 2023, seven cases of esophageal submucosal gland duct adenoma were identified at a tertiary medical centre; two were female and five were male, aged between 51 and 75 years (mean = 63.8 years). Comprehensive evaluations of clinicopathological, immunohistochemical and molecular characteristics were conducted. Histologically, tumours showed papillotubular and cystic patterns lined with double layers of cells arranged in ducts, papillary folds and microcysts. The inner luminal tall columnar cells had eosinophilic cytoplasm and did not show mucin production and the basal cells showed myoepithelial differentiation. Immunohistochemically, inner luminal layer cells were positive for CK7, CK19 and CK5/6 and outer basal layer cells were positive for SMA and P40. Both layers were negative for CK20, CDX2, MUC5AC, MUC6, MUC2, GCDFP15 and Alcian blue-periodic acid-Schiff (AB-PAS). Genomic analyses revealed the presence of BRAF V600E mutations in five of seven tumours (71.43%). This study delineates a distinct subtype of benign adenoma arising from the esophageal submucosal gland duct, characterised by multiple lobulated cystic proliferation of benign epithelial layers within the submucosa. BRAF V600E mutations were present, similar to in sialadenoma papilliferum. We determined the genetic mutation present in esophageal submucosal gland duct adenoma, providing further evidence that it is an esophageal counterpart of minor salivary gland tumours.

Broccoli Byproduct Extracts Attenuate the Expression of UVB-Induced Proinflammatory Cytokines in HaCaT Keratinocytes

Broccoli byproducts are an important source of bioactive compounds, which provide important benefits for human skin due mainly to their antioxidant and anti-inflammatory properties. The primary target of UVB radiation is the basal layer of cells in the epidermis, with keratinocytes being the most abundant cell population in this layer. Given the wide range of side effects caused by exposure to UVB radiation, reducing the amount of UV light that penetrates the skin and strengthening the protective mechanisms of the skin are interesting strategies for the prevention of skin disorders. This work aims to evaluate the protective mechanisms triggered by broccoli by-products extract (BBE) on HaCaT keratinocytes exposed to UVB radiation as well as the study of the regenerative effect of these extracts on the barrier of skin keratinocytes damaged by superficial wounds as a strategy to revalorize this agricultural waste. The results obtained revealed that the BBEs exhibited a high cytoprotective effect on the HaCaT exposed to UVB light, allowing it to effectively reduce the intracellular content of ROS, as well as effectively attenuating the increase in proinflammatory cytokines (IL-1β, IL-6, IL-78, TNF-α) and COX-2 induced by this type of radiation. Furthermore, the BBE could be an excellent regenerative agent for skin wound repair, accelerating the migration capacity of keratinocytes thus contributing to the valorization of this byproduct as a valuable ingredient in cosmetic formulations.

Transcriptomic Analysis of Air–Liquid Interface Culture in Human Lung Organoids Reveals Regulators of Epithelial Differentiation

To develop in vitro respiratory models, it is crucial to identify the factors involved in epithelial cell differentiation. In this study, we comprehensively analyzed the effects of air–liquid interface (ALI) culture on epithelial cell differentiation using single-cell RNA sequencing (scRNA-seq). ALI culture induced a pronounced shift in cell composition, marked by a fivefold increase in ciliated cells and a reduction of more than half in basal cells. Transcriptional signatures associated with epithelial cell differentiation, analyzed using iPathwayGuide software, revealed the downregulation of VEGFA and upregulation of CDKN1A as key signals for epithelial differentiation. Our findings highlight the efficacy of the ALI culture for replicating the human lung airway epithelium and provide valuable insights into the crucial factors that influence human ciliated cell differentiation.

TAp73 and ΔTAp73 isoforms show cell-type specific distributions and alterations in cancer

TP73 is a member of the TP53 gene family and produces N- and C-terminal protein isoforms through alternative promoters, alternative translation initiation and alternative splicing. Most notably, p73 protein isoforms may either contain a p53-like transactivation domain (TAp73 isoforms) or lack this domain (ΔTAp73 isoforms) and these variants have opposing or independent functions. To date, there is a lack of well-characterised isoform-specific p73 antibodies. Here, we produced polyclonal and monoclonal antibodies to N-terminal p73 variants and the C-terminal p73α isoform, the most common variant in human tissues. These reagents show that TAp73 is a marker of multiciliated epithelial cells, while ΔTAp73 is a marker of non-proliferative basal/reserve cells in squamous epithelium. We were unable to detect ΔNp73 variant proteins, in keeping with recent data that this is a minor form in human tissues. Most cervical squamous cell carcinomas (79%) express p73α, and the distribution of staining in basal cells correlated with lower tumour grade. TAp73 was found in 17% of these tumours, with a random distribution and no association with clinicopathological features. These data indicate roles for ΔTAp73 in maintaining a non-proliferative state of undifferentiated squamous epithelial cells and for TAp73 in the production of differentiated multiciliated cells.

Back Cover Image

ON THE BACK COVER: Immunofluorescence analysis of a histological section derived from a cutaneous squamous cell carcinoma specimen. S100A4 (green), primarily expressed by fibroblast cells, cytokeratin 14 (red), primarily expressed by basal epidermal cells, and DAPI (blue) to mark cell nuclei.Credit: Alexandra Pittar, Centre for Cancer Biology, an Alliance between SA Pathology and the University of South Australia, Adelaide, Australia. image

Biased signaling by mutant EGFR underlies dependence on PKCα in lung adenocarcinoma

Activating mutations in the epidermal growth factor receptor (EGFR) promote ligand-independent signaling; however, the mechanisms involved are poorly defined, and it is unknown whether this generates specific vulnerabilities. We previously observed robust expression of protein kinase Cα (PKCα) in lung adenocarcinoma (LUAD) with mutant EGFR (mEGFR), which, unlike the activation of PKCα, is independent of mEGFR activity. Here, we identify a critical role for PKCα in anchorage-independent growth and survival of lung cancer cells with mEGFR. Mechanistically, signaling pathways initiated by mEGFR show a high preference for ligand-independent phosphorylation on Y992, resulting in biased activation and dependence on phospholipase-Cγ and PKCα. Moreover, through bioinformatic approaches, we find that mEGFR LUAD demonstrates a transcriptomic profile most similar to lung basal cells, which exhibit elevated levels of PKCα, suggesting that mEGFR tumors arise in cell types with high intrinsic levels of PKCα. Taken together, these findings explain the dependence of mEGFR on PKCα.

Mechanistic insights into intrauterine adhesions.

Intrauterine adhesions (IUA), also known as Asherman's syndrome, arise from damage to the basal layer of the endometrium, frequently caused by intrauterine interventions. This damage leads to nonregenerative healing of endometrium resulting in replacement by fibrous connective tissue, which bring about the adherence of opposing endometrium to render the uterine cavity and/or cervical canal partially or completely obliterated. IUA is a common cause of the refractory uterine infertility. Hysteroscopy is the gold standard for diagnosis of IUA. However, the method of accurately predicting the likelihood of achieving a live birth in the future remains established. Classical treatments have shown limited success, particularly in severe cases. Therefore, utilizing new research methods to deepen the understanding of the pathogenesis of IUA will facilitate the new treatment approaches to be found. In this article we briefly described the advances in the pathogenesis of IUA, with focus on inflammation and parenchymal cellular homeostasis disruption, defects in autophagy and the role of ferroptosis, and we also outlined the progress in IUA therapy.

Identification of miR-141 as a Regulator of Epidermal Homeostasis

MicroRNAs (miRNAs), small endogenous non-coding RNAs, are involved in the regulation of epidermal homeostasis. Among them, miR-203 was the most described and expressed in human epidermis, promoting keratinocyte differentiation by repressing genes involved in proliferation. To identify other miRNAs involved in this process, the miRNomes of normal human keratinocytes cultured in monolayer (2D) or in 3D reconstructed skin were compared. Besides miR-203, miR-141 was one of the most expressed miRNAs in 3D culture and was overexpressed in 3D vs 2D condition, i.e. during keratinocyte differentiation. Functional experiments revealed that, mostly expressed in the basal layer, miR-141 decreased keratinocyte proliferation and clonogenicity, while promoting differentiation. Target prediction algorithm coupled with transcriptomic data of keratinocytes overexpressing miR-141, as well as 3'UTR luciferase assays enabled to evidence CCND2 mRNA as a direct target of miR-141, leading to its down-regulation by miR-141 overexpression. Finally, CCND2 silencing decreased keratinocyte proliferation and induced their differentiation, revealing that miR-141 action was mediated by CCND2. MiR-141 features were also compared with miR-203 in parallel experiments. Although miR-141 displayed similar functions to the ones of miR-203, it exhibited different localization and targets, suggesting a joint participation of miR-141 and miR-203 in engaging and maintaining keratinocyte towards differentiation, respectively.

Single-Cell RNA-Seq and Histological Analysis Reveals Dynamic Lrig1 Expression During Salivary Gland Development.

The development of the salivary gland (SG) is a complex process regulated by multiple signaling pathways in a spatiotemporal manner. Various stem/progenitor cell populations and respective cell lineages are involved in SG morphogenesis and postnatal maturation. Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) has been identified as critical regulator of stem cells by virtue of its ability to restrain stem cell proliferation, indicating its potential role in the development of several maxillofacial tissues and in the regulation of the quiescence in adult tissues. This study aimed to investigate the expression pattern and functions of Lrig1 in the developing and mature murine submandibular gland (SMG). To accomplish this objective, we collected the murine SMGs at different developmental stages and examined the expression pattern and levels of Lrig1 with qRT-PCR, immunofluorescent (IF) and RNAscope staining. We observed that Lrig1 was widely distributed in both epithelial and mesenchymal cells throughout embryonic and neonatal stages, with specific localization in the more mature epithelium. Furthermore, through single-cell RNA sequencing (scRNA-Seq) and IF techniques, we confirmed that LRIG1 is highly concentrated along with SMG progenitor markers in acinar and basal cells. Additionally, transcription factors (TFs) that could regulate LRIG1 expression were predicted from JASPAR databases and their motifs were identified by the UCSC browser's BLAT tool. Gene Ontology (GO) enrichment analyses on postnatal day 5 (PN5) scRNA-Seq data also provided insights into Lrig1's functions in SG development. Finally, we also conducted in vitro experiments on a human salivary gland (HSG) cell line to assess LRIG1's impact on HSG proliferation and migration, as well as its potential upstream regulatory TFs. Taken together, our study reveals that LRIG1 plays a vital role in SG development.

Identification of Nicotinic Acetylcholine Receptor for N-Acetylcysteine to Rescue Nicotine-induced Injury Using BeatingCilia in Primary Tissue Derived Airway Organoids.

Smoking is one of the major contributors to airway injuries. N-acetylcysteine (NAC) has been proposed as a treatment or preventive measure for such injuries. However, the exact nature of the smoking-induced injury and the protective mechanism of NAC are not yet fully understood. Here, patient tissue-derived airway organoids for modeling smoking-induced injury, therapeutic investigation, and mechanism studies are developed. Airway organoids consist mainly of ciliated cells, together with basal cells, goblet cells, and myofibroblast-like cells. The organoids display apical-out and basal-in polarity and are enriched in beating cilia, which are sensitive to smoking challenge and NAC treatment. An algorithm is developed to measure ciliary beating activity by analyzing the altered beating pattern of cilia in response to nicotine challenge and NAC treatment. Nicotinic acetylcholine receptors (nAChRs) expressed by airway organoids are involved in the mechanisms of nicotine-induced injury through the nicotine-nAChR pathway. In contrast to the common understanding that NAC has an antioxidative effect that mitigates airway damage, it is elucidated that NAC binding to nicotine can abolish the binding capacity of nicotine to nAChRs and thus prevent nicotine-induced injury. This study focuses on the advances and potential of humanized organoids in understanding biological processes, mechanisms, and identifying therapeutic targets.

Imaging findings in a case of primary intraosseous carcinoma arising from a mandibular cyst.

Primary intraosseous carcinoma not otherwise specified (PIOC NOS) is a rare tumor assumed to arise from the epithelium, such as odontogenic cysts or benign tumors. Its clinical and imaging diagnoses are often challenging, especially in the early stages, as it mimics jaw cysts and benign tumors, and no specific findings have been identified. This report presents the case of a 66-year-old male patient with mandibular PIOC, highlighting the imaging findings over time. Magnetic resonance imaging (MRI) before symptom onset showed a cystic lesion in the right mandible with a soft tissue component. Both the fluid component and soft tissue exhibited low apparent diffusion coefficient values (1.0 × 10-3 mm2/s and 1.3 × 10-3 mm2/s, respectively). Subsequent MRI approximately 5months later during symptom onset showed a slight increase in the soft tissue component. Based on the clinical and imaging findings, ameloblastoma was suspected, prompting a biopsy for confirmation. However, the histopathological findings showed squamous cell carcinoma (SCC). MRI performed approximately 1month later exhibited significant tumor growth and extension beyond the jawbone, consistent with a malignant tumor. Histopathological examination identified areas with a basal layer in a palisading arrangement, indicating a pre-existing odontogenic cyst, and showed a transition from epithelial dysplasia to SCC. In addition, carcinoma cell invasion and proliferation into the cyst were observed. Based on these findings, PIOC of the right mandible was determined to be the definitive diagnosis.

Single-cell RNA sequencing of zebrafish olfactory epithelium reveals cellular heterogeneity and responses to a conspecific alarm substance

Olfaction, the sense of smell, is vital for the survival of many species and serves as an excellent system for investigating the molecular basis of behavior. Fishes possess a well-developed olfactory system that governs various behaviors related to feeding, reproduction, and fear. However, the cellular diversity and heterogeneity of the fish olfactory epithelium remains largely unexplored. This study presents a single-cell atlas of the zebrafish olfactory epithelium using single-cell RNA sequencing (scRNA-seq). Through scRNA-seq analysis of approximately 10,587 ​cells, we identified nine distinct cell types with unique transcriptional profiles, including immature and mature olfactory sensory neurons (OSNs), horizontal basal cells, globose basal cells, and sustentacular cells, as well as lymphocyte and myeloid cells expressing immune signals. Further subcluster analysis revealed selective and combinatorial expression of key components in odorant-mediated signal transduction by distinct OSN populations. Additionally, we discovered transcriptional changes specific to certain OSN populations following exposure to a conspecific alarm substance. The single-cell transcriptional atlas of the zebrafish olfactory epithelium provided in this study serves as a valuable tool for exploring cell diversity and assessing genetic profiles from functional and behavioral perspectives in fish.

Study of the Correlation between the Extent and Clinical Severity, and the Histopathological Characteristics of Geographic Tongue.

Geographic tongue is an oral lesion with an unknown etiology. Recently, the Geographic Tongue Area and Severity Index (GTASI) has been proposed to assess the area and severity of geographic tongue, aiming to measure the clinical severity of the condition. However, this index does not account for the histopathology, which vary based on the clinical stage of the lesion and the biopsy area. The present study aimed to evaluate the correlation between GTASI score and its histopathological features. This cross-sectional observational study included 40 participants diagnosed with GT confirmed both clinically and histopathologically. Considering GT severity, a vast majority 60% of cases were classified as mild, with females' predominance in both mild and severe categories. The average age of participants was 56 years for mild and severe cases and 47 years for moderate ones. The prevalent histopathological features of geographic tongue included parakeratosis, acanthosis, spongiosis, basal layer hyperplasia, mono- and polymorphonuclear exocytosis, suprapapillary hypotrophy, claviform epithelial ridges, fusion of epithelial ridges, conjunctival papillary edema, and chronic subepithelial infiltration, with no significant differences taking into consideration clinical severity level. Papillary vascular ectasia, Munro microabscesses, Kogoj pustules, and dense connective tissue were more prevalent in with more severe cases of GT. Mild inflammatory infiltrate intensity was predominant in persons with mild GT, while moderate infiltrate intensity was found predominantly in moderate cases of GT. The clinical severity level of GT closely corresponds with its histopathological characteristics.