scholarly journals Human Lung Epithelial Cells Divide >200 Population Doublings without Engaging a Telomere Maintenance Mechanism

2018 ◽  
Author(s):  
Jennifer R. Peters-Hall ◽  
Jaewon Min ◽  
Enzo Tedone ◽  
Sei Sho ◽  
Silvia Siteni ◽  
...  
Keyword(s):  
Cell Culture ◽  
Epithelial Cells ◽  
Human Lung ◽  
Culture Conditions ◽  
Lung Epithelial Cells ◽  
Telomere Maintenance ◽  
Maintenance Mechanism ◽  
Hayflick Limit ◽  
Human Lung Cells ◽  
Population Doublings

AbstractThe “Hayflick limit” is a “mitotic clock” and primary cells have a finite lifespan that correlates with telomere length. However, introduction of the telomerase catalytic protein component (TERT) is insufficient to immortalize most, but not all, human cell types under typical cell culture conditions. Originally, telomerase activity was only detected in cancer cells but is now recognized as being detectable in transit amplifying cells in tissues undergoing regeneration or in extreme conditions of wound repair. Here we report thatin vitrolow stress culture conditions allow normal human lung basal epithelial cells to grow for over 200 population doublings without engaging any telomere maintenance mechanism. This suggests that most reported instances of telomere-based replicative senescence are due to cell culture stress-induced premature senescence.One Sentence SummaryHuman lung cells growing in reduced stress conditions can divide well beyond the Hayflick limit.

scholarly journals The Moraxella catarrhalis Autotransporter McaP Is a Conserved Surface Protein That Mediates Adherence to Human Epithelial Cells through Its N-Terminal Passenger Domain

2006 ◽  
Vol 75 (1) ◽  
pp. 314-324 ◽  
Author(s):  
Serena L. Lipski ◽  
Christine Akimana ◽  
Jennifer M. Timpe ◽  
R. Mark Wooten ◽  
Eric R. Lafontaine
Keyword(s):  
Sequence Analysis ◽  
Epithelial Cells ◽  
Moraxella Catarrhalis ◽  
Human Lung ◽  
Lipolytic Activity ◽  
Lung Epithelial Cells ◽  
Wild Type ◽  
Passenger Domain ◽  
E Coli ◽  
Human Lung Cells

ABSTRACT The protein McaP was previously shown to be an adhesin expressed by the Moraxella catarrhalis strain O35E, which also displays esterase and phospholipase B activities (J. M. Timpe et al., Infect. Immun. 71:4341-4350, 2003). In the present study, sequence analysis suggests that McaP is a conventional autotransporter protein that contains a 12-stranded β-barrel transporter module (amino acids [aa] 383 to 650) linked to a surface-exposed passenger domain exhibiting lipolytic activity (aa 62 to 330). An in-frame deletion removing most of this predicted N-terminal passenger domain was engineered, and Escherichia coli expressing the truncated McaP protein exhibited greatly reduced adherence to A549 human lung epithelial cells compared to E. coli expressing wild-type McaP. Site-directed mutagenesis of a serine residue at position 62 of McaP, predicted to be important for the lipolytic activity of the protein, resulted in loss of hydrolysis of p-nitrophenyl ester of caproate. E. coli expressing this mutated McaP, however, adhered to A549 monolayers at levels greater than recombinant bacteria expressing the wild-type adhesin. These results indicate that the predicted passenger domain of McaP is involved in both the binding and the lipolytic activity of the molecule and demonstrate that the adhesive properties of McaP do not require its lipolytic activity. Sequence analysis of mcaP from eight Moraxella catarrhalis strains revealed that the gene product is highly conserved at the amino acid level (98 to 100% identity), and Western blot analysis demonstrated that a panel of 16 isolates all express McaP. Flow cytometry experiments using antibodies raised against various portions of McaP indicated that its predicted passenger domain as well as transporter module contain surface-exposed epitopes. In addition to binding to the surface of intact bacteria, these antibodies were found to decrease adherence of M. catarrhalis to A549 human lung cells by up to 47% and to reduce binding of recombinant E. coli expressing McaP by 98%. These results suggest that McaP should be considered as a potential vaccine antigen.

scholarly journals Enhanced Proliferation and Growth of Human Lung Epithelial Cells on Gelatin Microparticle Loaded withEphedraExtracts

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Dolly Singh ◽  
Deepti Singh ◽  
Soon Mo Choi ◽  
Sung Soo Han
Keyword(s):  
Epithelial Cells ◽  
Human Lung ◽  
Cellular Adhesion ◽  
Lung Epithelial Cells ◽  
Drug Release Profile ◽  
In Vitro Biocompatibility ◽  
Human Lung Cells ◽  
Lung Epithelial ◽  
Human Lung Epithelial Cells

The objective of this work was to evaluate the effect of extracts ofEphedra gerardianaloaded onto gelatin particles on human lung epithelial cells. Particles were synthesized using oil-water emulsification technique and were further stabilized by glutaraldehyde. Particle size was evaluated using SEM and zeta potential analyzer and was found to be in the range of 600 nm–1.32 μm. Drug release profile showed controlled and constant release of extract over the period of 5 days. In vitro biocompatibility of gelatin particles loaded with solvent-free extract ofEphedra gerardianawas tested with human lung epithelial cells. Gelatin particle acted not only as scaffold for cellular adhesion but also as carrier matrix for controlled release of extracts. The cell viability was significantly high when cultured in the presence ofEphedraextract in comparison to cells withoutEphedraand 2D system as seen in MTT, SEM, and live/dead staining assay. It is concluded that gelatin microparticle functions both as drug delivery system and scaffold; however, the main finding was the effect ofEphedraextract on human lung cells resulting in enhanced proliferation and consequent promotion of ECM production indicating that extract could be a bioactive component that can be utilized in tissue engineering and regenerative medicine.

Age-dependent regulation of SARS-CoV-2 cell entry genes and cell death programs correlates with COVID-19 disease severity

2020 ◽  
Author(s):  
Zintis Inde ◽  
Clarence Yapp ◽  
Gaurav N. Joshi ◽  
Johan Spetz ◽  
Cameron Fraser ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cells ◽  
Disease Severity ◽  
Human Lung ◽  
Airway Epithelial Cells ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Lung Maturation ◽  
Human Lung Cells ◽  
Lung Epithelial

ABSTRACTAngiotensin-converting enzyme 2 (ACE2) maintains cardiovascular and renal homeostasis but also serves as the entry receptor for the novel severe acute respiratory syndrome coronavirus (SARS-CoV-2), the causal agent of novel coronavirus disease 2019 (COVID-19)1. COVID-19 disease severity, while highly variable, is typically lower in pediatric patients than adults (particularly the elderly), but increased rates of hospitalizations requiring intensive care are observed in infants than in older children. The reasons for these differences are unknown. To detect potential age-based correlates of disease severity, we measured ACE2 protein expression at the single cell level in human lung tissue specimens from over 100 donors from ∼4 months to 75 years of age. We found that expression of ACE2 in distal lung epithelial cells generally increases with advancing age but exhibits extreme intra- and inter-individual heterogeneity. Notably, we also detected ACE2 expression on neonatal airway epithelial cells and within the lung parenchyma. Similar patterns were found at the transcript level: ACE2 mRNA is expressed in the lung and trachea shortly after birth, downregulated during childhood, and again expressed at high levels in late adulthood in alveolar epithelial cells. Furthermore, we find that apoptosis, which is a natural host defense system against viral infection, is also dynamically regulated during lung maturation, resulting in periods of heightened apoptotic priming and dependence on pro-survival BCL-2 family proteins including MCL-1. Infection of human lung cells with SARS-CoV-2 triggers an unfolded protein stress response and upregulation of the endogenous MCL-1 inhibitor Noxa; in juveniles, MCL-1 inhibition is sufficient to trigger apoptosis in lung epithelial cells – this may limit virion production and inflammatory signaling. Overall, we identify strong and distinct correlates of COVID-19 disease severity across lifespan and advance our understanding of the regulation of ACE2 and cell death programs in the mammalian lung. Furthermore, our work provides the framework for potential translation of apoptosis modulating drugs as novel treatments for COVID-19.

scholarly journals Host mucin is subverted by Pseudomonas aeruginosa during infection to provide free glycans required for successful colonization

2019 ◽  
Author(s):  
Casandra L Hoffman ◽  
Alejandro Aballay
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Human Lung ◽  
Innate Immune ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Human Lung Cells ◽  
Immune Factor ◽  
Host Pathogen

AbstractThe mucosal barrier, found lining epithelial cells, serves multiple functions in a range of animals. The major structural components of mucus are mucins, which are heavily glycosylated proteins that are either membrane bound or secreted by the epithelial cells. Mucins are key components of the innate immune system, as they are involved in the clearance of pathogens from the airways and intestines, and their expression is typically upregulated upon epithelial cell exposure to a variety of pathogens. In this study, we identified the mucin MUL-1 as an innate immune factor that appears to be utilized by P. aeruginosa to colonize hosts. We found that while the expression of several mucins, including MUL-1, increased upon P. aeruginosa infection of the nematode Caenorhabditis elegans, silencing of or deletion of mul-1 resulted in enhanced survival and reduced bacterial accumulation. P. aeruginosa required host sialidase CTSA-1.1 to use mucin-derived glycans to colonize the host, while sialidase-encoding bacteria required host MUL-1 but not CTSA-1.1 to cause a lethal infection. This role of mucins and free glycans in host-pathogen interaction appears to be conserved from C. elegans to humans, as P. aeruginosa binding to human lung epithelial cells was also enhanced in the presence of free glycans, and free glycans reversed the binding defect of P. aeruginosa to human lung cells lacking the mucin MUC1.Author SummaryThe gastrointestinal, respiratory, reproductive, and urinary tracts, are large surfaces exposed to the exterior environment and thus, these mucosal epithelial tissues serve as primary routes of infection. One of the first lines of defense present at these barriers is mucus, which is a highly viscous material formed by mucin glycoproteins. Mucins serve various functions, but importantly they aid in the clearance of pathogens and debris from epithelial barriers and serve as innate immune effectors. In this study, we describe the ability of Pseudomonas aeruginosa to utilize mucin-derived glycans to colonize the intestine and ultimately cause death in Caenorhabditis elegans. We also show conserved mechanisms of P. aeruginosa virulence traits, by demonstrating that free glycans alter the ability of the bacteria to bind to human lung alveolar epithelial cells. Over the course of host-pathogen evolution, pathogens seem to have evolved to use mucins for their own advantage, and thus one of the biggest questions is which party benefits from pathogen-mucin binding. By gaining a better understanding of pathogen-mucin interactions, we can better protect against pathogen infection.

Legionella pneumophila induced microRNA expression in human lung epithelial cells

Pneumologie ◽  
2010 ◽  
Vol 64 (S 03) ◽  
Author(s):  
B Schmeck ◽  
B Dolniak ◽  
I Pollock ◽  
C Schulz ◽  
W Bertrams ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Legionella Pneumophila ◽  
Human Lung ◽  
Microrna Expression ◽  
Lung Epithelial Cells ◽  
Lung Epithelial ◽  
Human Lung Epithelial Cells
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