scholarly journals TMPRSS2 and furin are both essential for proteolytic activation of SARS-CoV-2 in human airway cells

2020 ◽  
Vol 3 (9) ◽  
pp. e202000786 ◽  
Author(s):  
Dorothea Bestle ◽  
Miriam Ruth Heindl ◽  
Hannah Limburg ◽  
Thuy Van Lam van ◽  
Oliver Pilgram ◽  
...  
Keyword(s):  
Serine Protease ◽  
Drug Targets ◽  
Therapeutic Potential ◽  
Severe Disease ◽  
Acute Infection ◽  
Airway Epithelial Cells ◽  
Surface Glycoprotein ◽  
Proteolytic Activation ◽  
Human Airway ◽  
Airway Cells

The novel emerged SARS-CoV-2 has rapidly spread around the world causing acute infection of the respiratory tract (COVID-19) that can result in severe disease and lethality. For SARS-CoV-2 to enter cells, its surface glycoprotein spike (S) must be cleaved at two different sites by host cell proteases, which therefore represent potential drug targets. In the present study, we show that S can be cleaved by the proprotein convertase furin at the S1/S2 site and the transmembrane serine protease 2 (TMPRSS2) at the S2′ site. We demonstrate that TMPRSS2 is essential for activation of SARS-CoV-2 S in Calu-3 human airway epithelial cells through antisense-mediated knockdown of TMPRSS2 expression. Furthermore, SARS-CoV-2 replication was also strongly inhibited by the synthetic furin inhibitor MI-1851 in human airway cells. In contrast, inhibition of endosomal cathepsins by E64d did not affect virus replication. Combining various TMPRSS2 inhibitors with furin inhibitor MI-1851 produced more potent antiviral activity against SARS-CoV-2 than an equimolar amount of any single serine protease inhibitor. Therefore, this approach has considerable therapeutic potential for treatment of COVID-19.

scholarly journals TMPRSS2 and furin are both essential for proteolytic activation and spread of SARS-CoV-2 in human airway epithelial cells and provide promising drug targets

2020 ◽  
Author(s):  
Dorothea Bestle ◽  
Miriam Ruth Heindl ◽  
Hannah Limburg ◽  
Thuy Van Lam van ◽  
Oliver Pilgram ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Protease Inhibitor ◽  
Host Cell ◽  
Serine Protease ◽  
Drug Targets ◽  
Serine Protease Inhibitor ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Human Airway ◽  
Human Airway Epithelial Cells

AbstractIn December 2019, a novel coronavirus named SARS-CoV-2 first reported in Wuhan, China, emerged and rapidly spread to numerous other countries globally, causing the current pandemic. SARS-CoV-2 causes acute infection of the respiratory tract (COVID-19) that can result in severe disease and lethality. Currently, there is no approved antiviral drug for treating COVID-19 patients and there is an urgent need for specific antiviral therapies and vaccines.In order for SARS-CoV-2 to enter cells, its surface glycoprotein spike (S) must be cleaved at two different sites by host cell proteases, which therefore represent potential drug targets. In the present study we investigated which host cell proteases activate the SARS-CoV-2 S protein in Calu-3 human airway epithelial cells. We show that S can be cleaved by both the proprotein convertase furin at the S1/S2 site and the transmembrane serine protease 2 (TMPRSS2) at the S2’ site. We demonstrate that TMPRSS2 is essential for activation of SARS-CoV-2 S in Calu-3 cells through antisense-mediated knockdown of TMPRSS2 expression. Further, we show that SARS-CoV-2 replication can be efficiently inhibited by two synthetic inhibitors of TMPRSS2 and also by the broad range serine protease inhibitor aprotinin. Additionally, SARS-CoV-2 replication was also strongly inhibited by the synthetic furin inhibitor MI-1851. Combining various TMPRSS2 inhibitors with MI-1851 produced more potent antiviral activity against SARS-CoV-2 than an equimolar amount of any single serine protease inhibitor. In contrast, inhibition of endosomal cathepsins by E64d did not affect virus replication.Our data demonstrate that both TMPRSS2 and furin are essential for SARS-CoV-2 activation in human airway cells and are promising drug targets for the treatment of COVID-19 either by targeting one of these proteases alone or by a combination of furin and TMPRSS2 inhibitors. Therefore, this approach has a high therapeutic potential for treatment of COVID-19.

scholarly journals TMPRSS2 Is the Major Activating Protease of Influenza A Virus in Primary Human Airway Cells and Influenza B Virus in Human Type II Pneumocytes

2019 ◽  
Vol 93 (21) ◽  
Author(s):  
Hannah Limburg ◽  
Anne Harbig ◽  
Dorothea Bestle ◽  
David A. Stein ◽  
Hong M. Moulton ◽  
...  
Keyword(s):  
Influenza A ◽  
Influenza B Virus ◽  
Influenza B ◽  
Virus Infectivity ◽  
Type Ii ◽  
Proteolytic Activation ◽  
Human Airway ◽  
Type Ii Pneumocytes ◽  
Airway Cells

ABSTRACT Cleavage of influenza virus hemagglutinin (HA) by host cell proteases is essential for virus infectivity and spread. We previously demonstrated in vitro that the transmembrane protease TMPRSS2 cleaves influenza A virus (IAV) and influenza B virus (IBV) HA possessing a monobasic cleavage site. Subsequent studies revealed that TMPRSS2 is crucial for the activation and pathogenesis of H1N1pdm and H7N9 IAV in mice. In contrast, activation of H3N2 IAV and IBV was found to be independent of TMPRSS2 expression and supported by an as-yet-undetermined protease(s). Here, we investigated the role of TMPRSS2 in proteolytic activation of IAV and IBV in three human airway cell culture systems: primary human bronchial epithelial cells (HBEC), primary type II alveolar epithelial cells (AECII), and Calu-3 cells. Knockdown of TMPRSS2 expression was performed using a previously described antisense peptide-conjugated phosphorodiamidate morpholino oligomer, T-ex5, that interferes with splicing of TMPRSS2 pre-mRNA, resulting in the expression of enzymatically inactive TMPRSS2. T-ex5 treatment produced efficient knockdown of active TMPRSS2 in all three airway cell culture models and prevented proteolytic activation and multiplication of H7N9 IAV in Calu-3 cells and H1N1pdm, H7N9, and H3N2 IAV in HBEC and AECII. T-ex5 treatment also inhibited the activation and spread of IBV in AECII but did not affect IBV activation in HBEC and Calu-3 cells. This study identifies TMPRSS2 as the major HA-activating protease of IAV in human airway cells and IBV in type II pneumocytes and as a potential target for the development of novel drugs to treat influenza infections. IMPORTANCE Influenza A viruses (IAV) and influenza B viruses (IBV) cause significant morbidity and mortality during seasonal outbreaks. Cleavage of the viral surface glycoprotein hemagglutinin (HA) by host proteases is a prerequisite for membrane fusion and essential for virus infectivity. Inhibition of relevant proteases provides a promising therapeutic approach that may avoid the development of drug resistance. HA of most influenza viruses is cleaved at a monobasic cleavage site, and a number of proteases have been shown to cleave HA in vitro. This study demonstrates that the transmembrane protease TMPRSS2 is the major HA-activating protease of IAV in primary human bronchial cells and of both IAV and IBV in primary human type II pneumocytes. It further reveals that human and murine airway cells can differ in their HA-cleaving protease repertoires. Our data will help drive the development of potent and selective protease inhibitors as novel drugs for influenza treatment.

scholarly journals Insulin signaling via the PI3-kinase/Akt pathway regulates airway glucose uptake and barrier function in a CFTR-dependent manner

2017 ◽  
Vol 312 (5) ◽  
pp. L688-L702 ◽  
Author(s):  
Samuel A. Molina ◽  
Hannah K. Moriarty ◽  
Daniel T. Infield ◽  
Barry R. Imhoff ◽  
Rachel J. Vance ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Epithelial Cells ◽  
Small Molecules ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Airway Epithelia ◽  
Human Airway ◽  
Airway Cells

Cystic fibrosis-related diabetes is the most common comorbidity associated with cystic fibrosis (CF) and correlates with increased rates of lung function decline. Because glucose is a nutrient present in the airways of patients with bacterial airway infections and because insulin controls glucose metabolism, the effect of insulin on CF airway epithelia was investigated to determine the role of insulin receptors and glucose transport in regulating glucose availability in the airway. The response to insulin by human airway epithelial cells was characterized by quantitative PCR, immunoblot, immunofluorescence, and glucose uptake assays. Phosphatidylinositol 3-kinase/protein kinase B (Akt) signaling and cystic fibrosis transmembrane conductance regulator (CFTR) activity were analyzed by pharmacological and immunoblot assays. We found that normal human primary airway epithelial cells expressed glucose transporter 4 and that application of insulin stimulated cytochalasin B-inhibitable glucose uptake, consistent with a requirement for glucose transporter translocation. Application of insulin to normal primary human airway epithelial cells promoted airway barrier function as demonstrated by increased transepithelial electrical resistance and decreased paracellular flux of small molecules. This provides the first demonstration that airway cells express insulin-regulated glucose transporters that act in concert with tight junctions to form an airway glucose barrier. However, insulin failed to increase glucose uptake or decrease paracellular flux of small molecules in human airway epithelia expressing F508del-CFTR. Insulin stimulation of Akt1 and Akt2 signaling in CF airway cells was diminished compared with that observed in airway cells expressing wild-type CFTR. These results indicate that the airway glucose barrier is regulated by insulin and is dysfunctional in CF.

scholarly journals Drug repurposing for COVID-19 based on an integrative meta-analysis of SARS-CoV-2 induced gene signature in human airway epithelium

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257784
Author(s):  
Rajaneesh K. Gupta ◽  
Enyinna L. Nwachuku ◽  
Benjamin E. Zusman ◽  
Ruchira M. Jha ◽  
Ava M. Puccio
Keyword(s):  
Gene Networks ◽  
Drug Targets ◽  
Drug Repositioning ◽  
Meta Analysis ◽  
Drug Repurposing ◽  
Gene Signature ◽  
Airway Epithelial Cells ◽  
Gene Ranking ◽  
Human Airway ◽  
Ranking Algorithms

Drug repurposing has the potential to bring existing de-risked drugs for effective intervention in an ongoing pandemic—COVID-19 that has infected over 131 million, with 2.8 million people succumbing to the illness globally (as of April 04, 2021). We have used a novel `gene signature’-based drug repositioning strategy by applying widely accepted gene ranking algorithms to prioritize the FDA approved or under trial drugs. We mined publically available RNA sequencing (RNA-Seq) data using CLC Genomics Workbench 20 (QIAGEN) and identified 283 differentially expressed genes (FDR<0.05, log2FC>1) after a meta-analysis of three independent studies which were based on severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infection in primary human airway epithelial cells. Ingenuity Pathway Analysis (IPA) revealed that SARS-CoV-2 activated key canonical pathways and gene networks that intricately regulate general anti-viral as well as specific inflammatory pathways. Drug database, extracted from the Metacore and IPA, identified 15 drug targets (with information on COVID-19 pathogenesis) with 46 existing drugs as potential-novel candidates for repurposing for COVID-19 treatment. We found 35 novel drugs that inhibit targets (ALPL, CXCL8, and IL6) already in clinical trials for COVID-19. Also, we found 6 existing drugs against 4 potential anti-COVID-19 targets (CCL20, CSF3, CXCL1, CXCL10) that might have novel anti-COVID-19 indications. Finally, these drug targets were computationally prioritized based on gene ranking algorithms, which revealed CXCL10 as the common and strongest candidate with 2 existing drugs. Furthermore, the list of 283 SARS-CoV-2-associated proteins could be valuable not only as anti-COVID-19 targets but also useful for COVID-19 biomarker development.

scholarly journals The SARS-CoV-2 multibasic cleavage site facilitates early serine protease-mediated entry into organoid-derived human airway cells

2020 ◽  
Author(s):  
Anna Z. Mykytyn ◽  
Tim I. Breugem ◽  
Samra Riesebosch ◽  
Debby Schipper ◽  
Petra B. van den Doel ◽  
...  
Keyword(s):  
Serine Protease ◽  
Cleavage Site ◽  
Serine Proteases ◽  
Highly Pathogenic ◽  
Remarkable Feature ◽  
Health Crisis ◽  
Human Airway ◽  
Cell Culture Systems ◽  
Serine Protease Activity ◽  
Airway Cells

AbstractAfter the SARS-CoV outbreak in 2003, a second zoonotic coronavirus named SARS-CoV-2, emerged late 2019 in China and rapidly caused the COVID-19 pandemic leading to a public health crisis of an unprecedented scale. Despite the fact that SARS-CoV-2 uses the same receptor as SARS-CoV, transmission and pathogenesis of both viruses seem to be quite distinct. A remarkable feature of the SARS-CoV-2 spike is the presence of a multibasic cleavage site, which is absent in the SARS-CoV spike. The viral spike protein not only attaches to the entry receptor, but also mediates fusion after cleavage by host proteases. Here, we report that the SARS-CoV-2 spike multibasic cleavage site increases infectivity on differentiated organoid-derived human airway cells. Compared with SARS-CoV, SARS-CoV-2 entered faster into the lung cell line Calu-3, and more frequently formed syncytial cells in differentiated organoid-derived human airway cells. Moreover, the multibasic cleavage site increased entry speed and plasma membrane serine protease usage relative to endosomal entry using cathepsins. Blocking serine protease activity using the clinically approved drug camostat mesylate effectively inhibited SARS-CoV-2 entry and replication in differentiated organoid-derived human airway cells. Our findings provide novel information on how SARS-CoV-2 enters relevant airway cells and highlight serine proteases as an attractive antiviral target.Significance StatementHighly pathogenic coronaviruses have spilled from animals to humans three times in the past two decades. Late 2019, SARS-CoV-2 emerged in China and was declared a pandemic by March 2020. The other two highly pathogenic coronaviruses, SARS-CoV and MERS-CoV, emerged in 2002 and 2012, respectively, but did not attain sustained human-to-human transmission. Given the high diversity of coronaviruses in animals, urbanization and increased air travel, future coronavirus pandemics are likely to occur intermittently. Identifying which factors determine pandemic potential and pathogenicity are therefore of key importance to global health. Additionally, there is an urgent need to rapidly translate fundamental knowledge to the clinic, a process that is expedited through the use of relevant cell culture systems.

scholarly journals Junctional abnormalities in human airway epithelial cells expressing F508del CFTR

2015 ◽  
Vol 309 (5) ◽  
pp. L475-L487 ◽  
Author(s):  
Samuel A. Molina ◽  
Brandon Stauffer ◽  
Hannah K. Moriarty ◽  
Agnes H. Kim ◽  
Nael A. McCarty ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Gap Junction ◽  
Lectin Binding ◽  
Intercellular Junctions ◽  
Cell Types ◽  
Airway Epithelial Cells ◽  
Transepithelial Resistance ◽  
Dye Transfer ◽  
Human Airway ◽  
Airway Cells

Cystic fibrosis (CF) has a profound impact on airway physiology. Accumulating evidence suggests that intercellular junctions are impaired in CF. We examined changes to CF transmembrane conductance regulator (CFTR) function, tight junctions, and gap junctions in NuLi-1 (CFTRwt/wt) and CuFi-5 (CFTRΔF508/ΔF508) cells. Cells were studied at air-liquid interface (ALI) and compared with primary human bronchial epithelial cells. On the basis of fluorescent lectin binding, the phenotype of the NuLi-1 and CuFi-5 cells at week 8 resembled that of serous, glycoprotein-rich airway cells. After week 7, CuFi-5 cells possessed 130% of the epithelial Na+ channel activity and 17% of the CFTR activity of NuLi-1 cells. In both cell types, expression levels of CFTR were comparable to those in primary airway epithelia. Transepithelial resistance of NuLi-1 and CuFi-5 cells stabilized during maturation in ALI culture, with significantly lower transepithelial resistance for CuFi-5 than NuLi-1 cells. We also found that F508del CFTR negatively affects gap junction function in the airway. NuLi-1 and CuFi-5 cells express the connexins Cx43 and Cx26. While both connexins were properly trafficked by NuLi-1 cells, Cx43 was mistrafficked by CuFi-5 cells. Cx43 trafficking was rescued in CuFi-5 cells treated with 4-phenylbutyric acid (4-PBA), as assessed by intracellular dye transfer. 4-PBA-treated CuFi-5 cells also exhibited an increase in forskolin-induced CFTR-mediated currents. The Cx43 trafficking defect was confirmed using IB3-1 cells and found to be corrected by 4-PBA treatment. These data support the use of NuLi-1 and CuFi-5 cells to examine the effects of F508del CFTR expression on tight junction and gap junction function in the context of serous human airway cells.

scholarly journals Cr(VI)-stimulated STAT3 tyrosine phosphorylation and nuclear translocation in human airway epithelial cells requires Lck

2007 ◽  
Vol 402 (2) ◽  
pp. 261-269 ◽  
Author(s):  
Kimberley A. O'hara ◽  
Rasilaben J. Vaghjiani ◽  
Antonia A. Nemec ◽  
Linda R. Klei ◽  
Aaron Barchowsky
Keyword(s):  
Epithelial Cells ◽  
Protein Binding ◽  
Tyrosine Phosphorylation ◽  
Nuclear Translocation ◽  
Airway Epithelial Cells ◽  
Janus Kinase ◽  
Luciferase Reporter ◽  
Cis Elements ◽  
Human Airway ◽  
Airway Cells

Chronic inhalation of low amounts of Cr(VI) promotes pulmonary diseases and cancers through poorly defined mechanisms. SFKs (Src family kinases) in pulmonary airway cells may mediate Cr(VI) signalling for lung injury, although the downstream effectors of Cr(VI)-stimulated SFKs and how they relate to pathogenic gene induction are unknown. Therefore SFK-dependent activation of transcription factors by non-cytotoxic exposure of human bronchial epithelial cells to Cr(VI) was determined. Protein–DNA binding arrays demonstrated that exposing BEAS 2B cells to 5 μM Cr(VI) for 4 and 24 h resulted in increased protein binding to 25 and 43 cis-elements respectively, while binding to 12 and 16 cis-elements decreased. Of note, Cr(VI) increased protein binding to several STAT (signal transducer and activator of transcription) cis-elements. Cr(VI) stimulated acute tyrosine phosphorylation and nuclear translocation of STAT1 over a 4 h period and a prolonged activation of STAT3 that reached a peak between 48 and 72 h. This prolonged activation was observed for both STAT3α and STAT3β. Immunofluorescent confocal microscopy confirmed that Cr(VI) increased nuclear localization of phosphorylated STAT3 for more than 72 h in both primary and BEAS 2B human airway cells. Cr(VI) induced transactivation of both a STAT3-driven luciferase reporter construct and the endogenous inflammatory gene IL-6 (interleukin-6). Inhibition with siRNA (small interfering RNA) targeting the SFK Lck, but not dominant-negative JAK (Janus kinase), prevented Cr(VI)-stimulated phosphorylation of both STAT3 isoforms and induction of IL-6. The results suggest that Cr(VI) activates epithelial cell Lck to signal for prolonged STAT3 activation and transactivation of IL-6, an important immunomodulator of lung disease progression.

Identification of the first synthetic inhibitors of the type II transmembrane serine protease TMPRSS2 suitable for inhibition of influenza virus activation

2013 ◽  
Vol 452 (2) ◽  
pp. 331-343 ◽  
Author(s):  
Daniela Meyer ◽  
Frank Sielaff ◽  
Maya Hammami ◽  
Eva Böttcher-Friebertshäuser ◽  
Wolfgang Garten ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Serine Protease ◽  
Catalytic Domain ◽  
Serine Proteinase ◽  
Airway Epithelial Cells ◽  
Influenza Viruses ◽  
Surface Glycoprotein ◽  
Type Ii ◽  
Virus Propagation ◽  
Transmembrane Serine Protease

TMPRSS2 (transmembrane serine proteinase 2) is a multidomain type II transmembrane serine protease that cleaves the surface glycoprotein HA (haemagglutinin) of influenza viruses with a monobasic cleavage site, which is a prerequisite for virus fusion and propagation. Furthermore, it activates the fusion protein F of the human metapneumovirus and the spike protein S of the SARS-CoV (severe acute respiratory syndrome coronavirus). Increased TMPRSS2 expression was also described in several tumour entities. Therefore TMPRSS2 emerged as a potential target for drug design. The catalytic domain of TMPRSS2 was expressed in Escherichia coli and used for an inhibitor screen with previously synthesized inhibitors of various trypsin-like serine proteases. Two inhibitor types were identified which inhibit TMPRSS2 in the nanomolar range. The first series comprises substrate analogue inhibitors containing a 4-amidinobenzylamide moiety at the P1 position, whereby some of these analogues possess inhibition constants of approximately 20 nM. An improved potency was found for a second type derived from sulfonylated 3-amindinophenylalanylamide derivatives. The most potent derivative of this series inhibits TMPRSS2 with a Ki value of 0.9 nM and showed an efficient blockage of influenza virus propagation in human airway epithelial cells. On the basis of the inhibitor studies, a series of new fluorogenic substrates containing a D-arginine residue at the P3 position was synthesized, some of them were efficiently cleaved by TMPRSS2.

scholarly journals Topical TMPRSS2 inhibition prevents SARS-CoV-2 infection in differentiated primary human airway cells

2021 ◽  
Author(s):  
Wenrui Guo ◽  
Linsey M Porter ◽  
Thomas WM Crozier ◽  
Matthew Coates ◽  
Akhilesh Jha ◽  
...  
Keyword(s):  
Serine Protease ◽  
Treatment Options ◽  
Upper Airway ◽  
Airway Epithelial Cells ◽  
Post Exposure Prophylaxis ◽  
Apical Surface ◽  
Systemic Delivery ◽  
Human Airway ◽  
The Impact

AbstractBackgroundThere are limited effective prophylactic treatments for SARS-CoV-2 infection, and limited early treatment options. Viral cell entry requires spike protein binding to the ACE2 receptor and spike cleavage by TMPRSS2, a cell surface serine protease. Targeting of TMPRSS2 by either androgen blockade or direct inhibition is already in clinical trials in early SARS-CoV-2 infection.MethodsThe likely initial cells of SARS-CoV-2 entry are the ciliated cells of the upper airway. We therefore used differentiated primary human airway epithelial cells maintained at the air-liquid interface (ALI) to test the impact of targeting TMPRSS2 on the prevention of SARS-CoV-2 infection.ResultsWe first modelled the systemic delivery of compounds. Enzalutamide, an oral androgen receptor antagonist, had no impact on SARS-Cov-2 infection. By contrast, camostat mesylate, an orally available serine protease inhibitor, blocked SARS-CoV-2 entry. However, camostat is rapidly metabolised in the circulation in vivo, and systemic bioavailability after oral dosing is low. We therefore modelled local airway administration by applying camostat to the apical surface of the differentiated ALI cultures. We demonstrated that a brief exposure to topical camostat is effective at restricting SARS-CoV-2 viral infection.ConclusionThese experiments demonstrate a potential therapeutic role for topical camostat for pre- or post-exposure prophylaxis of SARS-CoV-2, which can now be evaluated in a clinical trial.

scholarly journals The ΔF508-CFTR mutation results in increased biofilm formation byPseudomonas aeruginosaby increasing iron availability

2008 ◽  
Vol 295 (1) ◽  
pp. L25-L37 ◽  
Author(s):  
Sophie Moreau-Marquis ◽  
Jennifer M. Bomberger ◽  
Gregory G. Anderson ◽  
Agnieszka Swiatecka-Urban ◽  
Siying Ye ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Epithelial Cells ◽  
Biofilm Formation ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Human Airway ◽  
Abiotic Surfaces ◽  
Δf508 Cftr ◽  
Airway Cells ◽  
Human Airway Epithelial Cells

Enhanced antibiotic resistance of Pseudomonas aeruginosa in the cystic fibrosis (CF) lung is thought to be due to the formation of biofilms. However, there is no information on the antibiotic resistance of P. aeruginosa biofilms grown on human airway epithelial cells or on the effects of airway cells on biofilm formation by P. aeruginosa. Thus we developed a coculture model and report that airway cells increase the resistance of P. aeruginosa to tobramycin (Tb) by >25-fold compared with P. aeruginosa grown on abiotic surfaces. Therefore, the concentration of Tb required to kill P. aeruginosa biofilms on airway cells is 10-fold higher than the concentration achievable in the lungs of CF patients. In addition, CF airway cells expressing ΔF508-CFTR significantly enhanced P. aeruginosa biofilm formation, and ΔF508 rescue with wild-type CFTR reduced biofilm formation. Iron (Fe) content of the airway in CF is elevated, and Fe is known to enhance P. aeruginosa growth. Thus we investigated whether enhanced biofilm formation on ΔF508-CFTR cells was due to increased Fe release by airway cells. We found that airway cells expressing ΔF508-CFTR released more Fe than cells rescued with WT-CFTR. Moreover, Fe chelation reduced biofilm formation on airway cells, whereas Fe supplementation enhanced biofilm formation on airway cells expressing WT-CFTR. These data demonstrate that human airway epithelial cells promote the formation of P. aeruginosa biofilms with a dramatically increased antibiotic resistance. The ΔF508-CFTR mutation enhances biofilm formation, in part, by increasing Fe release into the apical medium.

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