Nasal Epithelial Cell Proliferation Research Articles

Epidermal growth factor activates a hypoxia-inducible factor 1α-microRNA-21 axis to inhibit aquaporin 4 in chronic rhinosinusitis.

The pathogenesis of chronic rhinosinusitis (CRS) is largely unknown, but accumulating evidence supports the role of the airway epithelium in its pathophysiology. In our study here, we evaluated whether epidermal growth factor (EGF) regulates a hypoxia-inducible factor 1α (HIF-1α)-microRNA-21 (miR-21)-aquaporin 4 (AQP4) axis in nasal epithelial cells from CRS patients. We found that, compared with normal sinus mucosa, EGF, HIF-1α, and miR-21 were upregulated and AQP4 was downregulated in sinus mucosa from patients with CRS and in a CRS mouse model. It was established that EGF upregulated HIF-1α and miR-21 expression, that HIF-1α regulated miR-21 transcription, and that the AQP4 gene was a target of miR-21. Knockdown of EGF and HIF-1α mRNAs and of miR-21, or overexpression of AQP4 mRNA, inhibited proliferation and promoted apoptosis of hypoxia-exposed human nasal epithelial cells, effects that were associated with reduced levels of α-SMA, fibronectin, and vimentin, as well as promoted caspase-3 activity and E-cadherin levels. In the mouse CRS model, EGF elevation increased in vivo production of inflammatory IL-4 and IFN-γ to promote CRS, which was reversed by AQP4 elevation. Collectively, EGF upregulates HIF-1α and miR-21 expression to inhibit AQP4 expression, thereby promoting the proliferation of nasal epithelial cells and the development of CRS.

YAP Promotes Cell Proliferation and Epithelium-Derived Cytokine Expression via NF-κB Pathway in Nasal Polyps.

BackgroundHippo-Yes-associated protein (YAP) pathway plays an important role in epithelial cell proliferation and inflammation development in chronic rhinosinusitis with nasal polyps (CRSwNP). However, the underlying mechanisms remain unclear.ObjectiveThis study intends to investigate the role of YAP and the nuclear factor kappa-B (NF-κB) pathway in cell proliferation and the expression of epithelium-derived cytokines in nasal polyps (NP).MethodsThe expression levels of YAP, TEA domain family member 1 (TEAD1), Ki-67, and NF-κB as well as interleukin (IL-) 33, IL-25 and thymic stromal lymphopoietin (TSLP) in sinonasal mucosa, primary nasal epithelial cells (NPECs), and human nasal epithelial RPMI 2650 cells were detected. NPECs were cultured and treated with verteporfin (VP), YAP shRNA or BAY 11–7082.ResultsThe hippo pathway effector YAP, Ki-67, p65 NF-κB, and cyclin D1 were significantly increased in NP compared with control mucosa, which was accompanied by overexpression of IL-33, IL-25, and TSLP. Pharmaceutical inhibition of YAP by VP suppressed cell proliferation of RPMI 2650 cells by blocking cell cycle progression at G0/G1 without inducing obvious cell apoptosis. Furthermore, lentiviral transfection-mediated knockdown of hippo pathway activity reduced the expression of IL-33, IL-25, TSLP as well as p65 NF-κB in RPMI 2650 cells. Downregulation of NF-κB pathway with BAY 11–7082 in NPECs could decrease the mRNA level of TSLP, IL-33 and IL-25 accordingly.ConclusionInhibition of hippo pathway suppressed nasal epithelial cell proliferation and declined the expression of epithelium-derived cytokines via the NF-κB pathway in NPECs.

Conditioned medium from umbilical cord mesenchymal stem cells improves nasal mucosa damage by radiation

To explore therapeutic effects of conditioned medium from human umbilical cord mesenchymal stem cells (hUC-MSCs) on nasal mucosa radiation damage both in vivo and in vitro. The mucus cilia clearance time (7 and 30days), degree of mucosal edema (7, 30, 90 and 180days), cilia coverage (180days) of concentrated conditioned medium group improved compared with radiotherapy control group. The proliferation and migration abilities of irradiated and non-irradiated nasal epithelial cells significantly increased after culture in bronchial epithelial cell growth medium (BEGM) containing 10% conditioned medium of hUC-MSCs compared to cells cultured in BEGM alone. Soluble factors secreted by hUC-MSCs may promote nasal epithelial cell proliferation and migration. Intranasal administration of hUC-MSC conditioned medium effectively repairs nasal mucosa radiation damage.

Inhalation exposure to ethylene induces eosinophilic rhinitis and nasal epithelial remodeling in Fischer 344 rats

This study investigated the time- and concentration-dependent effects of inhaled ethylene on eosinophilic rhinitis and nasal epithelial remodeling in Fisher 344 rats exposed to 0, 10, 50, 300, or 10,000 ppm ethylene, 6 h/day, 5 days/week for up to 4 weeks. Morphometric quantitation of eosinophilic inflammation and mucous cell metaplasia/hyperplasia (MCM) and nasal mucosal gene expression were evaluated at anatomic sites previously shown to undergo ethylene-induced epithelial remodeling. Serum levels of total IgE, IgG1 and IgG2a were measured to determine if ethylene exposure increased the expression of Th2-associated (IgE and IgG1) relative to Th1-associated (IgG2a) antibody isotypes. Rats exposed to 0 or 10,000 ppm for 1, 3, 5, 10, or 20 days were analyzed to assess the temporal pattern of ethylene-induced alterations in nasal epithelial cell proliferation, morphology and gene expression. Rats exposed to 0, 10, 50, 300, and 10,000 ppm ethylene for 20 days were analyzed to assess concentration-dependent effects on lesion development. Additional rats exposed 4 weeks to 0, 300, or 10,000 ppm ethylene were held for 13 weeks post-exposure to examine the persistence of ethylene-induced mucosal alterations. The data indicate that cell death and reparative cell proliferation were not a part of the pathogenesis of ethylene-induced nasal lesions. Enhanced gene expression of Th2 cytokines (e.g., IL-5, IL-13) and chitinase (YM1/2) in the nasal mucosa was much greater than that of Th1 cytokines (e.g., IFNγ) after ethylene exposure. A significant increase in MCM was measured after 5 days of exposure to 10,000 ppm ethylene and after 20 days of exposure 10 ppm ethylene. Ethylene-induced MCM was reversible after cessation of exposure. No increase in total serum IgE, IgG1 or IgG2a was measured in any ethylene-exposed group. These data do not support involvement of an immune-mediated allergic mechanism in the pathogenesis of ethylene-induced nasal lesions in rats. Repeated inhalation of ethylene can induce a local Th2-mediated response in the nasal mucosa of rats, however the mechanisms which induce nasal inflammatory and epithelial responses are yet to be determined.

Derivation of an Inhalation Reference Concentration Based upon Olfactory Neuronal Loss in Male Rats following Subchronic Acetaldehyde Inhalation

Acetaldehyde inhalation induces neoplastic and nonneoplastic responses in the rodent nasal cavity. This experiment further characterizes the dose-response relationship for nasal pathology, nasal epithelial cell proliferation, and DNA–protein cross-link formation in F-344 rats exposed subchronically to acetaldehyde. Animals underwent whole-body exposure to 0, 50, 150, 500, or 1500 ppm acetaldehyde for 6 h/day, 5 days/wk for up to 65 exposure days. Respiratory tract histopathology was evaluated after 4, 9, 14, 30, and 65 exposure days. Acetaldehyde exposure was not associated with reduced body weight gain or other evidence of systemic toxicity. Histologic evaluation of the nasal cavity showed an increased incidence of olfactory neuronal loss (ONL) following acute to subchronic exposure to ≥ 150 ppm acetaldehyde and increased olfactory epithelial cell proliferation following exposure to 1500 ppm acetaldehyde. The severity of the ONL demonstrated dose-and temporal-dependent behaviors, with minimal effects noted at 150–500 ppm acetaldehyde and moderately severe lesions seen in the highest exposure group, with increased lesion severity and extent as the exposure duration increased. Acetaldehyde exposure was also associated with inflammation, hyperplasia, and squamous metaplasia of the respiratory epithelium. These responses were seen in animals exposed to ≥500 ppm acetaldehyde. Acetaldehyde exposure was not associated with increased DNA–protein cross-link formation in the respiratory or olfactory epithelium. A model of acetaldehyde pharmacokinetics in the nose was used to derive an inhalation reference concentration (RfC) of 0.4 ppm, based on the no-observed-adverse-effect level (NOAEL) of 50 ppm for the nasal pathology seen in this study.

Formaldehyde-induced gene expression in F344 rat nasal respiratory epithelium

Formaldehyde (FA), an occupational and environmental toxicant used extensively in the manufacturing of many household and personal use products, is known to induce squamous cell carcinomas in the nasal turbinates of rats and mice and squamous metaplasia in monkey noses. Tissue responses to FA include a dose dependent epithelial degeneration, respiratory cell hypertrophy, and squamous metaplasia. The primary target for FA-induced toxicity in both rodents and monkeys is the respiratory nasal epithelium. FA increases nasal epithelial cell proliferation and DNA–protein crosslinks (DPX) that are associated with subsequent nasal cancer development. To address the acute effects of FA exposure that might contribute to known pathological changes, cDNA gene expression analysis was used. Two groups of male F344 rats received either 40 ul of distilled water or FA (400 mM) instilled into each nostril. Twenty-four hours following treatment, nasal epithelium was recovered from which total RNA was used to generate cDNA probes. Significance analysis of microarrays (SAM) hybridization data using Clontech™ Rat Atlas 1.2 arrays revealed that 24 of the 1185 genes queried were significantly up-regulated and 22 genes were significantly downregulated. Results for ten of the differentially expressed genes were confirmed by quantitative real time RT PCR. The identified genes with FA-induced change in expression belong to the functional gene categories xenobiotic metabolism, cell cycle, apoptosis, and DNA repair. These data suggest that multiple pathways are dysregulated by FA exposure, including those involved in DNA synthesis/repair and regulation of cell proliferation. Differential gene expression profiles may provide clues that could be used to define mechanisms involved in FA-induced nasal cancer.

FOUR-WEEK INHALATION CELL PROLIFERATION STUDY OF THE EFFECTS OF VINYL ACETATE ON RAT NASAL EPITHELIUM

Inhalation exposure of rats to 600 ppm vinyl acetate monomer produced nasal papillomas, squamous-cell carcinomas, and carcinoma in situ in rats. These tumors had a very long latency to onset, appearing only at terminal sacrifice. Nonneoplastic lesions were largely confined to the olfactory regions lining the dorsal meatus and mainly consisted of epithelial degeneration and basal-cell hyperplasia. The no-observed-adverse-effect level (NOAEL) for these effects was 50 ppm. Vinyl acetate is metabolized by nasal carboxylesterase to acetaldehyde, a DNA-protein cross-linking agent, and acetic acid, a cytotoxicant. Both vinyl acetate and acetaldehyde are clastogenic. These observations support the notion that multiple stages are likely involved in the mechanism of vinyl acetate carcinogenesis. The purpose of these experiments was to study the role of induced cell proliferation in the early changes in nasal epithelium that lead to cancer. Rats were exposed to 0, 50, 200, 600, or 1000 ppm vinyl acetate for 1, 5, or 20 exposures and killed 18 h after the last exposure for evaluation of nasal epithelial cell proliferation. In respiratory epithelium, cell proliferation rates were elevated after a single exposure, but returned to control levels after 5 and 20 exposures. In olfactory epithelium, cell proliferation rates also increased after an initial exposure and subsided after 5 exposures but then rebounded with a second wave of proliferation following 20 exposures. Histopathological changes were largely confined to the olfactory epithelium. The NOAEL for all effects was 200 ppm. These results demonstrate the capability for distinctly different responses between respiratory and olfactory epithelium. The complex nature of the responses further suggests a role for cellular and biochemical adaptation in the toxic responses to vinyl acetate exposure.

Effects of Propylene Oxide on Nasal Epithelial Cell Proliferation in F344 Rats

Effects of Propylene Oxide on Nasal Epithelial Cell Proliferation in F344 Rats. Eldridge, S. R., Bogdanffy, M. S., Jokinen, M.P., and Andrews, L. S. (1995). Fundam. Appl. Toxicol. 27, 25-32. In chronic inhalation studies, propylene oxide (PO), widely used in the chemical and food industries, induced nasal tumors in F344 rats. Nonneoplastic findings of the chronic studies suggest a strong cytotoxic and proliferative component in the mechanism of PO carcinogenicity. A 4-week cell proliferation study was conducted to establish a no-observed-adverse-effect level (NOAEL) for nonneoplastic changes in the nasal epithelium of rats. Male F344 rats were exposed to 0, 10, 20, 50, 150, or 525 ppm PO vapor for up to 4 weeks with up to 4 weeks of recovery. Histopathology showed that the incidence and severity of respiratory epithelial hyperplasia increased with exposure time and regressed after termination of exposure with complete recovery after 4 weeks. Similarly, cell proliferation, as determined by bromodeoxyuridine incorporation into replicating cells, was elevated following 1 and 4 weeks of exposure, but decreased to control values after 1 week of recovery. Degeneration of the olfactory epithelium was found after 4 weeks of exposure with a decrease in incidence and severity after termination of exposure. Cell proliferation at this site was elevated during the 4-week exposure period and 1 week postexposure with return to control values after 4 weeks of recovery. Based on the cytotoxic and proliferative findings, the NOAEL for PO in nasal epithelium is 50 ppm.

Distribution of Mast Cells in Inverted Papilloma and Squamous Cell Carcinoma of the Nose

An increased number of mast cells is found in the epithelial layer of the nasal mucosa of allergic subjects. However, the mechanism of accumulation of the intraepithelial mast cells has not yet been clarified. We have previously shown that the increase of intraepithelial mast cells is related to the proliferation of nasal epithelial cells in vivo, and inverted papilloma and squamous cell carcinoma of the nose seem to be in vivo proliferative states of nasal epithelium. To clarify the mechanism of the accumulation of intraepithelial mast cells, we studied the relationship between nasal tumors of epithelial cell origin and the accumulation of mast cells. Accumulation of mast cells was observed in the nasal inverted papilloma, especially within 50μm from the basement membrane at the tumor site, which might be the site of maximum proliferation of tumor cells as well as secretion of cytokines. The majority of mast cells accumulated were formalin sensitive mast cells (mainly MMCs). On the other hand, in the squamous cell carcinoma of the maxillary sinus, fewer mast cells were found. Results of this study suggest that the accumulation of intraepithelial mast cells is associated with the proliferation of nasal epithelial cells.

Regional Differences in Ozone-Induced Nasal Epithelial Cell Proliferation in F344 Rats: Comparison with Computational Mass Flux Predictions of Ozone Dosimetry

Regional Differences in Ozone-Induced Nasal Epithelial Cell Proliferation in F344 Rats: Comparison with Computational Mass Flux Predictions of Ozone Dosimetry

Cell Proliferation and Formaldehyde‐Induced Respiratory Carcinogenesis

Formaldehyde is a nasal carcinogen in the rat but the cancer risk this chemical poses for humans remains to be determined. Formaldehyde induces nonlinear, concentration-dependent increases in nasal epithelial cell proliferation and DNA-protein cross-link formation following short-term exposure. Presented in this review are results from a mechanistically based formaldehyde inhalation study in which an important endpoint was the measurement of cell proliferation indices in target sites for nasal tumor induction. Male Fischer 344 rats were exposed to 0, 0.7, 2, 6, 10, or 15 ppm formaldehyde for up to 2 years (6 hr/day, 5 day/week). Statistically significant increases in cell proliferation were confined to the 10 and 15 ppm groups, which remained elevated throughout the study. The concentration-dependent increases in cell proliferation correlated strongly with the tumor response curve, supporting the proposal that sustained increases in cell proliferation are an important component of formaldehyde carcinogenesis. The nonlinearity observed in formaldehyde-induced rodent nasal cancer is consistent with a high-concentration effect of regenerative cell proliferation of the target organ coupled with the genotoxic effects of formaldehyde. Cell kinetic data from these studies provide important information that may be utilized in the assessment of risk for humans exposed to formaldehyde.

Mast cell and eosinophil distributions in nasal inverted papilloma

An increased number of mast cells and eosinophils can be recognized in the epithelial layer of nasal mucosa from allergic subjects; these cells are known to play an important role in the manifestation of nasal allergy. Eosinophils accumulate under the effect of eosinophil chemotactic factor released by mast cells. However, the mechanism of accumulation of mast cells has not yet been clarified. Our previous studies have shown that colony stimulating activity of the basophil/eosinophil lineage is enhanced under proliferative conditions for nasal epithelial cells. We therefore studied the distribution of mast cells and eosinophils in inverted papilloma of the nose, in which we can identify proliferation of nasal epithelial cells. Nasal inverted papilloma from 5 patients were examined for mast cell and eosinophil distributions. Serial staining of nasal inverted papilloma showed that the number of mast cells and the percentage of formalin sensitive mast cells within 50 microns of the tumor site and 50 microns above the basement membrane were 16576 +/- 5729/mm3 (90.8%) and 4697 +/- 304/mm3 (76.1%), respectively. However, in comparison with the tumor site, significant differences in the distribution and number of mast cells were seen in the stromal area. The number of mast cells and the percentage of formalin sensitive mast cells within 50 microns and 50 microns above the basement membrane were 2880 +/- 238/mm3 (0%) and 3096 +/- 152/mm3 (0%), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional increases in rat nasal epithelial cell proliferation following acute and subchronic inhalation of formaldehyde

Short-term studies (9 days) in the rat have demonstrated that formaldehyde-induced nasal epithelial lesions are associated with increases in surface epithelial cell proliferation rates. The present studies were designed, in part, to investigate cell proliferation rates in the nasal epithelium of rats exposed to formaldehyde for a longer duration in order to determine if correlations exist between (1) the concentration-response in cell proliferation rate with the previously published formaldehyde bioassay tumor response; (2) sites of increased cell proliferation and the regions of the nasal passages that exhibit formaldehyde-induced cytotoxicity; and (3) sites of increased cell proliferation and the regions of the rat nasal passages previously determined to be most susceptible to neoplasia (i.e., the lateral meatus and nasal septum of the anterior nasal passages). Another important endpoint of this study was to provide data for a comparison of formaldehyde-induced responses in rats with previous findings in rhesus monkeys. Fischer-344 rats were exposed to 0, 0.7, 2, 6, 10, or 15 ppm formaldehyde for up to 6 weeks and pulse labeled with tritiated thymidine prior to each scheduled termination. Exposure to formaldehyde at 6 ppm or higher induced site-specific lesions in the nasal respiratory epithelium and was associated with increases in cell proliferation rate which remained statistically elevated throughout the 6 weeks. While a direct correlation between sites susceptible to formaldehyde-induced nasal cancer and increased cell proliferation was not evident, results from the present studies did demonstrate a clear correlation between sites of cellular injury and increases in cell proliferation and a concentration-dependent response which correlated with the previously published formaldehyde bioassay tumor response. Furthermore, this work demonstrated that form-aldehyde-induced responses in rats exposed to 6 ppm were morphologically similar to those reported in the rhesus monkey; however, the distribution of lesions between the two species differed significantly.