Expression of wild-type CFTR suppresses NF-kappaB-driven inflammatory signalling

Human Norovirus-Induced Gene Expression Biomarkers in Zebrafish

ABSTRACT

The challenges associated with development of an animal model system to replicate human norovirus (HuNoV) has hampered the study of the pathogenesis and therapeutic interventions for this virus. In this study, we replicated HuNoV GII.4 and evaluated virus gene expression in infected zebrafish. Three doses of inoculation resulted in successful virus replication. Genes for transmembrane transporters (tfa, cftr, slc26a3, and slc26a6), a heat shock chaperone (hspa8), and immune response cytokines (ifng1 and il1b) were highly expressed in HuNoV-infected zebrafish; however, expression levels of genes were reduced in zebrafish infected with thermally inactivated HuNoV. These results confirm HuNoV replication in juvenile zebrafish and will facilitate the investigation of biomarker gene expression during HuNoV infection.

HIGHLIGHTS

ABCC7/CFTR Expression Is Associated with the Clinical Course of Ulcerative Colitis Patients

Inflammatory bowel disease includes ulcerative colitis (UC) and Crohn's disease (CD) of unknown etiology. The expression of ATP-binding cassette (ABC) family proteins has been associated with drug resistance and development of UC. The cystic fibrosis transmembrane conductance regulator (CFTR) or also known as ABCC7 is involved in the inflammatory chronic response. The aim of this study was to evaluate the role of ABCC7/CFTR in UC patients and normal controls without inflammation. This is an exploratory, observational, and cross-sectional study that included a total of 62 patients with UC and normal controls. Gene expression of CFTR was measured by RT-PCR, and protein expression of CFTR was determined by western blot analysis. We found a significant downregulation of the CFTR gene expression in patients with active UC compared to normal controls without inflammation (P < 0.004); even the gene expression of CFTR was decreased in remission UC patients compared to normal controls without inflammation (P = 0.04). The CFTR gene expression was associated with the clinical course of UC and the protein expression of CFTR was decreased in active UC patients compared to normal controls without inflammation suggesting that this molecule might play a role in the inflammation in UC patients.

Enhanced Expression of Human Epididymis Protein 4 (HE4) Reflecting Pro-Inflammatory Status Is Regulated by CFTR in Cystic Fibrosis Bronchial Epithelial Cells

Decreased human epididymis protein 4 (HE4) plasma levels were reported in cystic fibrosis (CF) patients under CFTR potentiator ivacaftor therapy, which inversely correlated with lung function improvement. In this study, we investigated whether HE4 expression was affected via modulation of CFTR function in CF bronchial epithelial (CFBE) cells in vitro. HE4 protein levels were measured in the supernatants of CFBE 41o⁻ cells expressing F508del-CFTR or wild-type CFTR (wt-CFTR) after administration of lumacaftor/ivacaftor or tezacaftor/ivacaftor, while HE4 expression in CFBE 41o⁻ cells were also analyzed following application of adenylate cyclase activators Forskolin/IBMX or CFTR_inh172. The effect of all of these compounds on CFTR function was monitored by the whole-cell patch-clamp technique. Induced HE4 expression was studied with interleukin-6 (IL-6) in F508del-CFTR CFBE 41o⁻ cells under TNF-α stimulation for 1 h up to 1 week in duration. In parallel, plasma HE4 was determined in CF subjects homozygous for p.Phe508del-CFTR mutation receiving lumacaftor/ivacaftor (Orkambi^®) therapy. NF-κB-mediated signaling was observed via the nuclear translocation of p65 subunit by fluorescence microscopy together with the analysis of IL-6 expression by an immunoassay. In addition, HE4 expression was examined after NF-κB pathway inhibitor BAY 11-7082 treatment with or without CFTR modulators. CFTR modulators partially restored the activity of F508del-CFTR and reduced HE4 concentration was found in F508del-CFTR CFBE 41o⁻ cells that was close to what we observed in CFBE 41o⁻ cells with wt-CFTR. These data were in agreement with decreased plasma HE4 concentrations in CF patients treated with Orkambi^®. Furthermore, CFTR inhibitor induced elevated HE4 levels, while CFTR activator Forskolin/IBMX downregulated HE4 in the cell cultures and these effects were more pronounced in the presence of CFTR modulators. Higher activation level of baseline and TNF-α stimulated NF-κB pathway was detected in F508del-CFTR vs. wt-CFTR CFBE 41o⁻ cells that was substantially reduced by CFTR modulators based on lower p65 nuclear positivity and IL-6 levels. Finally, HE4 expression was upregulated by TNF-α with elevated IL-6, and both protein levels were suppressed by combined administration of NF-κB pathway inhibitor and CFTR modulators in CFBE 41o⁻ cells. In conclusion, CFTR dysfunction contributes to abnormal HE4 expression via NF-κB in CF.

Cystic Fibrosis Lung Disease in the Aging Population

The demographics of the population with cystic fibrosis (CF) is continuously changing, with nowadays adults outnumbering children and a median predicted survival of over 40 years. This leads to the challenge of treating an aging CF population, while previous research has largely focused on pediatric and adolescent patients. Chronic inflammation is not only a hallmark of CF lung disease, but also of the aging process. However, very little is known about the effects of an accelerated aging pathology in CF lungs. Several chronic lung disease pathologies show signs of chronic inflammation with accelerated aging, also termed “inflammaging”; the most notable being chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). In these disease entities, accelerated aging has been implicated in the pathogenesis via interference with tissue repair mechanisms, alterations of the immune system leading to impaired defense against pulmonary infections and induction of a chronic pro-inflammatory state. In addition, CF lungs have been shown to exhibit increased expression of senescence markers. Sustained airway inflammation also leads to the degradation and increased turnover of cystic fibrosis transmembrane regulator (CFTR). This further reduces CFTR function and may prevent the novel CFTR modulator therapies from developing their full efficacy. Therefore, novel therapies targeting aging processes in CF lungs could be promising. This review summarizes the current research on CF in an aging population focusing on accelerated aging in the context of chronic airway inflammation and therapy implications.

Prognosis-Based Early Intervention Strategies to Resolve Exacerbation and Progressive Lung Function Decline in Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disease caused by a mutation(s) in the CF transmembrane regulator (CFTR), where progressive decline in lung function due to recurring exacerbations is a major cause of mortality. The initiation of chronic obstructive lung disease in CF involves inflammation and exacerbations, leading to mucus obstruction and lung function decline. Even though clinical management of CF lung disease has prolonged survival, exacerbation and age-related lung function decline remain a challenge for controlling the progressive lung disease. The key to the resolution of progressive lung disease is prognosis-based early therapeutic intervention; thus, the development of novel diagnostics and prognostic biomarkers for predicting exacerbation and lung function decline will allow optimal management of the lung disease. Hence, the development of real-time lung function diagnostics such as forced oscillation technique (FOT), impulse oscillometry system (IOS), and electrical impedance tomography (EIT), and novel prognosis-based intervention strategies for controlling the progression of chronic obstructive lung disease will fulfill a significant unmet need for CF patients. Early detection of CF lung inflammation and exacerbations with the timely resolution will not only prolong survival and reduce mortality but also improve quality of life while reducing significant health care costs due to recurring hospitalizations.

Autophagy Augmentation to Alleviate Immune Response Dysfunction, and Resolve Respiratory and COVID-19 Exacerbations

The preservation of cellular homeostasis requires the synthesis of new proteins (proteostasis) and organelles, and the effective removal of misfolded or impaired proteins and cellular debris. This cellular homeostasis involves two key proteostasis mechanisms, the ubiquitin proteasome system and the autophagy–lysosome pathway. These catabolic pathways have been known to be involved in respiratory exacerbations and the pathogenesis of various lung diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF), acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and coronavirus disease-2019 (COVID-19). Briefly, proteostasis and autophagy processes are known to decline over time with age, cigarette or biomass smoke exposure, and/or influenced by underlying genetic factors, resulting in the accumulation of misfolded proteins and cellular debris, elevating apoptosis and cellular senescence, and initiating the pathogenesis of acute or chronic lung disease. Moreover, autophagic dysfunction results in an impaired microbial clearance, post-bacterial and/or viral infection(s) which contribute to the initiation of acute and recurrent respiratory exacerbations as well as the progression of chronic obstructive and restrictive lung diseases. In addition, the autophagic dysfunction-mediated cystic fibrosis transmembrane conductance regulator (CFTR) immune response impairment further exacerbates the lung disease. Recent studies demonstrate the therapeutic potential of novel autophagy augmentation strategies, in alleviating the pathogenesis of chronic obstructive or restrictive lung diseases and exacerbations such as those commonly seen in COPD, CF, ALI/ARDS and COVID-19.

Different CFTR modulator combinations downregulate inflammation differently in cystic fibrosis

Previously, we showed that serum and monocytes from patients with CF exhibit an enhanced NLRP3-inflammasome signature with increased IL-18, IL-1β, caspase-1 activity and ASC speck release (Scambler et al. eLife 2019). Here we show that CFTR modulators down regulate this exaggerated proinflammatory response following LPS/ATP stimulation. In vitro application of ivacaftor/lumacaftor or ivacaftor/tezacaftor to CF monocytes showed a significant reduction in IL-18, whereas IL-1β was only reduced with ivacaftor/tezacaftor. Thirteen adults starting ivacaftor/lumacaftor and eight starting ivacaftor/tezacaftor were assessed over three months. Serum IL-18 and TNF decreased significantly with treatments, but IL-1β only declined following ivacaftor/tezacaftor. In (LPS/ATP-stimulated) PBMCs, IL-18/TNF/caspase-1 were all significantly decreased and IL-10 was increased with both combinations. Ivacaftor/tezacaftor alone showed a significant reduction in IL-1β and pro-IL-1β mRNA. This study demonstrates that these CFTR modulator combinations have potent anti-inflammatory properties, in addition to their ability to stimulate CFTR function, which could contribute to improved clinical outcomes.

CFTR inhibits the invasion and growth of esophageal cancer cells by inhibiting the expression of NF-κB

Our study aimed to explore the function of cystic fibrosis transmembrane conductance regulator (CFTR) in esophageal cancer. Twenty patients with esophageal squamous cell carcinoma (ESCC) and 20 patients with esophageal adenocarcinoma (EA) were enrolled in this study. The levels of CFTR and NF-κB in tumor tissues and adjacent normal tissues were detected, respectively. The expression of CFTR were detected by qRT-PCR and Western blot in normal esophageal cell line, esophagus squamous cell, carcinoma cell lines, and EA cell lines, respectively. Effects of CFTR silencing and overexpression on NF-κB protein expression were detected by Western blot. Transwell assay was performed to detect cell invasion. Mouse tumor model was established and the effect of CFTR inhibitor on tumor growth was examined. The expression of CFTR was downregulated in tumor tissues and cancer cell lines. CFTR silencing promoted the expression of NF-κB-p65 and NF-κB-p50, and the results of CFTR overexpression were reversed. In addition, CFTR silencing promoted the invasion of cancer cells and tumor growth in mice. Besides that, NF-κB inhibitor reduced the enhancing effects of CFTR silencing on esophageal cell invasion. We conclude that CFTR inhibits the growth and migration of esophageal cancer cells by downregulating of the NF-κB protein expression.

Cystic fibrosis transmembrane conductance regulator-emerging regulator of cancer

Mutations of cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis, the most common life-limiting recessive genetic disease among Caucasians. CFTR mutations have also been linked to increased risk of various cancers but remained controversial for a long time. Recent studies have begun to reveal that CFTR is not merely an ion channel but also an important regulator of cancer development and progression with multiple signaling pathways identified. In this review, we will first present clinical findings showing the correlation of genetic mutations or aberrant expression of CFTR with cancer incidence in multiple cancers. We will then focus on the roles of CFTR in fundamental cellular processes including transformation, survival, proliferation, migration, invasion and epithelial-mesenchymal transition in cancer cells, highlighting the signaling pathways involved. Finally, the association of CFTR expression levels with patient prognosis, and the potential of CFTR as a cancer prognosis indicator in human malignancies will be discussed.

The role of Nuclear Factor-kappa B signaling in human cervical cancer

Background The Nuclear Factor kappaB (NF-kB) family consists of transcription factors that play a complex and essential role in the regulation of immune responses and inflammation. NF-kB has recently generated considerable interest as it has been implicated in human cancer initiation, progression and resistance to treatment. In the present comprehensive review the different aspects of NF-kB signaling in the carcinogenesis of cancer of the uterine cervix are discussed. NF-kB functions as part of a network, which determines the pattern of its effects on the expression of several other genes (such as crosstalks with reactive oxygen species, p53, STAT3 and miRNAS) and thus its function. Activation of NF-kB triggered by a HPV infection is playing an important role in the innate and adaptive immune response of the host. The virus induces down regulation of NF-kB to liquidate the inhibitory activity for its replication triggered by the immune system leading a status of persistant HPV infection. During the progression to high grade intraepithelial neoplasia and cervical cancer NF-KB becomes constitutionally activated again. Mutations in NF-kB genes are rare in solid tumors but mutations of upstream signaling molecules such as RAS, EGFR, PGF, HER2 have been implicated in elevated NF-kB signaling. NF-kB can stimulate transcription of proliferation regulating genes (eg. cyclin D1 and c-myc), genes involved in metastasis, VEGF dependent angiogenesis and cell immortality by telomerase. NF-kB activation can also induce the expression of activation-induced cytodine deaminase (AID) and the APOBEC proteins, providing a mechanistic link between the NF-kB pathway and mutagenic characteristic of cervical cancer. Inhibition of NF-kB has the potential to be used to reverse resistance to radiotherapy and systemic anti-cancer medication, but currently no clinicaly active NF-kB targeting strategies are available.

Activation of Nuclear Factor-κB by Tumor Necrosis Factor in Intestinal Epithelial Cells and Mouse Intestinal Epithelia Reduces Expression of the Chloride Transporter SLC26A3

BACKGROUND & AIMS

Diarrhea associated with inflammatory bowel diseases has been associated with increased levels of inflammatory cytokines, including tumor necrosis factor (TNF). The intestinal mucosa of patients with inflammatory bowel diseases has reduced expression of solute carrier family 26 member 3 (SLC26A3, also called DRA). We investigated whether TNF directly affects expression of DRA in human intestinal epithelial cells (IECs) and in the intestines of mice, and studied the mechanisms of these effects.

METHODS

We performed quantitative reverse transcription polymerase chain reaction, immunofluorescence, and immunoblot analyses in Caco-2, HT-29, and T-84 cells human IECs cultured in 2 or 3 dimensions with or without TNF (50 ng/mL for 6-24 hours). We purified nuclear extracts and quantified nuclear factor-κB (NF-κB) activation and DNA binding. We isolated intestinal crypts from C57BL/6 mice, cultured enteroids, incubated these with TNF (50 ng/mL, 24 hours), and quantified messenger RNAs. DRA-mediated exchange of Cl- for HCO3- was measured by uptake of 125I. Expression of the NF-κB inhibitor α (IkBa) was knocked down in Caco-2 cells with small interfering RNAs. Activation of NF-κB in response to TNF was measured by luciferase reporter assays; binding of the NF-κB subunit p65 in cells was analyzed in chromatin immunoprecipitation assays. DRA promoter activity was measured in a luciferase reporter assay. C57BL/6 mice were injected with TNF (5 μg/mouse for 3-6 hours) or vehicle (control); intestines were collected and analyzed by immunofluorescence, or RNA and protein were collected from the mucosa.

RESULTS

Incubation of IECs with TNF reduced expression of DRA. Knockdown of NF-κB inhibitor α in IECs led to nuclear translocation of the NF-κB subunit p65 and reduced levels of DRA messenger RNA and protein. Expression of a transgene encoding p65 or p50 in IECs led to significant reductions in the promoter activity of DRA and its expression. In chromatin immunoprecipitation assays, p65 bound directly to the promoter of DRA, at the regions of -935 to -629 and -375 to -84. Injection of mice with TNF or incubation of crypt-derived enteroids with TNF reduced their expression of DRA messenger RNA and protein.

CONCLUSIONS

In human IECs and intestinal tissues from mice, we found TNF to activate NF-κB, which reduced expression of the Cl- / HCO3- exchanger DRA (SLC26A3), via direct binding to the promoter of DRA. This pathway is an important therapeutic target for inflammatory bowel disease-associated diarrhea.

Dysregulated Chemokine Signaling in Cystic Fibrosis Lung Disease: A Potential Therapeutic Target

CF lung disease is characterized by a chronic and non-resolving activation of the innate immune system with excessive release of chemokines/cytokines including IL-8 and persistent infiltration of immune cells, mainly neutrophils, into the airways. Chronic infection and impaired immune response eventually lead to pulmonary damage characterized by bronchiectasis, emphysema, and lung fibrosis. As a complete knowledge of the pathways responsible for the exaggerated inflammatory response in CF lung disease is lacking, understanding these pathways could reveal new therapeutic targets, and lead to novel treatments. Therefore, there is a strong rationale for the identification of mechanisms and pathways underlying the exaggerated inflammatory response in CF lung disease. This article reviews the role of inflammation in the pathogenesis of CF lung disease, with a focus on the dysregulated signaling involved in the overexpression of chemokine IL-8 and excessive recruitment of neutrophils in CF airways. The findings suggest that targeting the exaggerated IL-8/IL-8 receptor (mainly CXCR2) signaling pathway in immune cells (especially neutrophils) may represent a potential therapeutic strategy for CF lung disease.

An Optimised Human Cell Culture Model for Alveolar Epithelial Transport

Robust and reproducible in vitro models are required for investigating the pathways involved in fluid homeostasis in the human alveolar epithelium. We performed functional and phenotypic characterisation of ion transport in the human pulmonary epithelial cell lines NCI-H441 and A549 to determine their similarity to primary human alveolar type II cells. NCI-H441 cells exhibited high expression of junctional proteins ZO-1, and E-cadherin, seal-forming claudin-3, -4, -5 and Na⁺-K⁺-ATPase while A549 cells exhibited high expression of pore-forming claudin-2. Consistent with this phenotype NCI-H441, but not A549, cells formed a functional barrier with active ion transport characterised by higher electrical resistance (529 ± 178 Ω cm² vs 28 ± 4 Ω cm²), lower paracellular permeability ((176 ± 42) ×10⁻⁸ cm/s vs (738 ± 190) ×10⁻⁸ cm/s) and higher transepithelial potential difference (11.9 ± 4 mV vs 0 mV). Phenotypic and functional properties of NCI-H441 cells were tuned by varying cell seeding density and supplement concentrations. The cells formed a polarised monolayer typical of in vivo epithelium at seeding densities of 100,000 cells per 12-well insert while higher densities resulted in multiple cell layers. Dexamethasone and insulin-transferrin-selenium supplements were required for the development of high levels of electrical resistance, potential difference and expression of claudin-3 and Na⁺-K⁺-ATPase. Treatment of NCI-H441 cells with inhibitors and agonists of sodium and chloride channels indicated sodium absorption through ENaC under baseline and forskolin-stimulated conditions. Chloride transport was not sensitive to inhibitors of the cystic fibrosis transmembrane conductance regulator (CFTR) under either condition. Channels inhibited by 5-nitro-1-(3-phenylpropylamino) benzoic acid (NPPB) contributed to chloride secretion following forskolin stimulation, but not at baseline. These data precisely define experimental conditions for the application of NCI-H441 cells as a model for investigating ion and water transport in the human alveolar epithelium and also identify the pathways of sodium and chloride transport.

New use for an old drug: COX-independent anti-inflammatory effects of sulindac in models of cystic fibrosis

Background and Purpose

Pulmonary disease is the main cause of morbidity and mortality in cystic fibrosis (CF) patients due to exacerbated inflammation. To date, the only anti‐inflammatory drug available to CF patients is high‐dose ibuprofen, which can slow pulmonary disease progression, but whose cyclooxygenase‐dependent digestive adverse effects limit its clinical use. Here we have tested sulindac, another non‐steroidal anti‐inflammatory drug with an undefined anti‐inflammatory effect in CF airway epithelial cells.

Experimental Approach

Using in vitro and in vivo models, we NF‐κB activity and IL‐8 secretion. In HeLa‐F508del cells, we performed luciferase reporter gene assays in order to measure i) IL‐8 promoter activity, and ii) the activity of synthetic promoter containing NF‐κB responsive elements. We quantified IL‐8 secretion in airway epithelial CFBE cells cultured at an air‐liquid interface and in a mouse model of CF.

Key Results

Sulindac inhibited the transcriptional activity of NF‐κB and decreased IL‐8 transcription and secretion in TNF‐α stimulated CF cells via a cyclooxygenase‐independent mechanism. This effect was confirmed in vivo in a mouse model of CF induced by intra‐tracheal instillation of LPS, with a significant decrease of the induction of mRNA for MIP‐2, following treatment with sulindac.

Conclusion and Implications

Overall, sulindac decrease lung inflammation by a mechanism independent of cycolooxygenase. This drug could be beneficially employed in CF.

Emerging role of cystic fibrosis transmembrane conductance regulator - an epithelial chloride channel in gastrointestinal cancers

Cystic fibrosis transmembrane conductance regulator (CFTR), a glycoprotein with 1480 amino acids, has been well established as a chloride channel mainly expressed in the epithelial cells of various tissues and organs such as lungs, sweat glands, gastrointestinal system, and reproductive organs. Although defective CFTR leads to cystic fibrosis, a common genetic disorder in the Caucasian population, there is accumulating evidence that suggests a novel role of CFTR in various cancers, especially in gastroenterological cancers, such as pancreatic cancer and colon cancer. In this review, we summarize the emerging findings that link CFTR with various cancers, with focus on the association between CFTR defects and gastrointestinal cancers as well as the underlying mechanisms. Further study of CFTR in cancer biology may help pave a new way for the diagnosis and treatment of gastrointestinal cancers.

CFTR Knockdown induces proinflammatory changes in intestinal epithelial cells

Background

Hyperinflammation is a hallmark feature of cystic fibrosis (CF) airways. However, inflammation has also been documented systemically and, more recently, in extrapulmonary CF-affected tissues such as the pancreas and intestine. The pathogenesis of CF-related inflammation and more specifically the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in that respect are not entirely understood. We have tested the hypothesis that genetic depletion of CFTR will affect the inflammatory status of human intestinal epithelial cell lines.

Methods

CFTR expression was genetically depleted from Caco-2/15 and HT-29 cells using short hairpin RNA interference (shRNAi). Inflammatory conditions were induced by the addition of human recombinant tumor necrosis factor (TNF) or Interleukin-1β (IL-1β) for various periods of time. Gene expression, mRNA stability and secreted levels of interleukin (IL)-6, −8 and 10 were assessed. Analysis of pro- and anti-inflammatory signaling pathways including mitogen-activated protein kinases (p38, ERK 1/2 and JNK), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (IκBα), and nuclear factor-kappa B (NF-κB) was also performed. Eosinophils were counted in the jejunal mucosa of Cftr−/− and Cftr+/+ mice.

Results

CFTR gene and protein knockdown caused a significant increase in basal secretion of IL-8 as well as in IL-1β-induced secretion of IL-6 and −8. Release of the anti-inflammatory cytokine, IL-10, remained unaffected by CFTR depletion. The enhanced secretion of IL-8 stems in part from increased IL8 mRNA levels and greater activation of ERK1/2 MAPK, IκBα and NF-κB in the CFTR knockdown cells. By contrast, phosphorylation levels of p38 and JNK MAPK did not differ between control and knockdown cells. We also found a higher number of infiltrating eosinophils in the jejunal mucosa of Cftr −/− females, but not males, compared to Cftr +/+ mice, thus providing in vivo support to our in vitro findings.

Conclusion

Collectively, these data underscore the role played by CFTR in regulating the intestinal inflammatory responses. Such findings lend support to the theory that CFTR exerts functions that may go beyond its role as a chloride channel whereby its disruption may prevent cells to optimally respond to exogenous or endogenous challenges. These observations are of particular interest to CF patients who were found to display alterations in their intestinal microbiota, thus predisposing them to pathogens that may elicit exaggerated inflammatory responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-015-0107-y) contains supplementary material, which is available to authorized users.

Down-regulated CFTR During Aging Contributes to Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a hyper-proliferative disease of the aging prostate; however, the exact mechanism underlying the development of BPH remains incompletely understood. The present study investigated the possible involvement of the cystic fibrosis transmembrane conductance regulator (CFTR), which has been previously shown to negatively regulate nuclear factor-κB (NF-κB)/cyclooxygenase 2 (COX2)/prostaglandin E2 (PGE2) pathway, in the pathogenesis of BPH. Our results showed decreasing CFTR and increasing COX2 expression in rat prostate tissues with aging. Furthermore, suppression of CFTR led to increased expression of COX2 and over-production of PGE2 in a normal human prostate epithelial cell line (PNT1A) with elevated NF-κB activity. PGE2 stimulated the proliferation of primary rat prostate stromal cells but not epithelial cells, with increased PCNA expression. In addition, the condition medium from PNT1A cells after inhibition or knockdown of CFTR promoted cell proliferation of prostate stromal cells which could be reversed by COX2 or NF-κB inhibitor. More importantly, the involvement of CFTR in BPH was further demonstrated by the down-regulation of CFTR and up-regulation of COX2/NF-κB in human BPH samples. The present results suggest that CFTR may be involved in regulating PGE2 production through its negative regulation on NF-κB/COX2 pathway in prostate epithelial cells, which consequently stimulates cell growth of prostate stromal cells. The overstimulation of prostate stromal cell proliferation by down-regulation of CFTR-enhanced PGE2 production and release during aging may contribute to the development of BPH.

Influenza virus M2 targets cystic fibrosis transmembrane conductance regulator for lysosomal degradation during viral infection

We sought to determine the mechanisms by which influenza infection of human epithelial cells decreases cystic fibrosis transmembrane conductance regulator (CFTR) expression and function. We infected human bronchial epithelial (NHBE) cells and murine nasal epithelial (MNE) cells with various strains of influenza A virus. Influenza infection significantly reduced CFTR short circuit currents (Isc) and protein levels at 8 hours postinfection. We then infected CFTR expressing human embryonic kidney (HEK)-293 cells (HEK-293 CFTRwt) with influenza virus encoding a green fluorescent protein (GFP) tag and performed whole-cell and cell-attached patch clamp recordings. Forskolin-stimulated, GlyH-101-sensitive CFTR conductances, and CFTR open probabilities were reduced by 80% in GFP-positive cells; Western blots also showed significant reduction in total and plasma membrane CFTR levels. Knockdown of the influenza matrix protein 2 (M2) with siRNA, or inhibition of its activity by amantadine, prevented the decrease in CFTR expression and function. Lysosome inhibition (bafilomycin-A1), but not proteasome inhibition (lactacystin), prevented the reduction in CFTR levels. Western blots of immunoprecipitated CFTR from influenza-infected cells, treated with BafA1, and probed with antibodies against lysine 63-linked (K-63) or lysine 48-linked (K-48) polyubiquitin chains supported lysosomal targeting. These results highlight CFTR damage, leading to early degradation as an important contributing factor to influenza infection-associated ion transport defects.

Increased NF-κB Activity and Decreased Wnt/β-Catenin Signaling Mediate Reduced Osteoblast Differentiation and Function in ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Mice

The prevalent human ΔF508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) is associated with reduced bone formation and bone loss in mice. The molecular mechanisms by which the ΔF508-CFTR mutation causes alterations in bone formation are poorly known. In this study, we analyzed the osteoblast phenotype in ΔF508-CFTR mice and characterized the signaling mechanisms underlying this phenotype. Ex vivo studies showed that the ΔF508-CFTR mutation negatively impacted the differentiation of bone marrow stromal cells into osteoblasts and the activity of osteoblasts, demonstrating that the ΔF508-CFTR mutation alters both osteoblast differentiation and function. Treatment with a CFTR corrector rescued the abnormal collagen gene expression in ΔF508-CFTR osteoblasts. Mechanistic analysis revealed that NF-κB signaling and transcriptional activity were increased in mutant osteoblasts. Functional studies showed that the activation of NF-κB transcriptional activity in mutant osteoblasts resulted in increased β-catenin phosphorylation, reduced osteoblast β-catenin expression, and altered expression of Wnt/β-catenin target genes. Pharmacological inhibition of NF-κB activity or activation of canonical Wnt signaling rescued Wnt target gene expression and corrected osteoblast differentiation and function in bone marrow stromal cells and osteoblasts from ΔF508-CFTR mice. Overall, the results show that the ΔF508-CFTR mutation impairs osteoblast differentiation and function as a result of overactive NF-κB and reduced Wnt/β-catenin signaling. Moreover, the data indicate that pharmacological inhibition of NF-κB or activation of Wnt/β-catenin signaling can rescue the abnormal osteoblast differentiation and function induced by the prevalent ΔF508-CFTR mutation, suggesting novel therapeutic strategies to correct the osteoblast dysfunctions in cystic fibrosis.

Second-hand cigarette smoke impairs bacterial phagocytosis in macrophages by modulating CFTR dependent lipid-rafts

Introduction

First/Second-hand cigarette-smoke (FHS/SHS) exposure weakens immune defenses inducing chronic obstructive pulmonary disease (COPD) but the underlying mechanisms are not fully understood. Hence, we evaluated if SHS induced changes in membrane/lipid-raft (m-/r)-CFTR (cystic fibrosis transmembrane conductance regulator) expression/activity is a potential mechanism for impaired bacterial phagocytosis in COPD.

Methods

RAW264.7 murine macrophages were exposed to freshly prepared CS-extract (CSE) containing culture media and/or Pseudomonas-aeruginosa-PA01-GFP for phagocytosis (fluorescence-microscopy), bacterial survival (colony-forming-units-CFU), and immunoblotting assays. The CFTR-expression/activity and lipid-rafts were modulated by transient-transfection or inhibitors/inducers. Next, mice were exposed to acute/sub-chronic-SHS or room-air (5-days/3-weeks) and infected with PA01-GFP, followed by quantification of bacterial survival by CFU-assay.

Results

We investigated the effect of CSE treatment on RAW264.7 cells infected by PA01-GFP and observed that CSE treatment significantly (p<0.01) inhibits PA01-GFP phagocytosis as compared to the controls. We also verified this in murine model, exposed to acute/sub-chronic-SHS and found significant (p<0.05, p<0.02) increase in bacterial survival in the SHS-exposed lungs as compared to the room-air controls. Next, we examined the effect of impaired CFTR ion-channel-activity on PA01-GFP infection of RAW264.7 cells using CFTR172-inhibitor and found no significant change in phagocytosis. We also similarly evaluated the effect of a CFTR corrector-potentiator compound, VRT-532, and observed no significant rescue of CSE impaired PA01-GFP phagocytosis although it significantly (p<0.05) decreases CSE induced bacterial survival. Moreover, induction of CFTR expression in macrophages significantly (p<0.03) improves CSE impaired PA01-GFP phagocytosis as compared to the control. Next, we verified the link between m-/r-CFTR expression and phagocytosis using methyl-β-cyclodextran (CD), as it is known to deplete CFTR from membrane lipid-rafts. We observed that CD treatment significantly (p<0.01) inhibits bacterial phagocytosis in RAW264.7 cells and adding CSE further impairs phagocytosis suggesting synergistic effect on CFTR dependent lipid-rafts.

Conclusion

Our data suggest that SHS impairs bacterial phagocytosis by modulating CFTR dependent lipid-rafts.

Lymphotoxin β receptor activation promotes bladder cancer in a nuclear factor-κB-dependent manner

Bladder cancer (BCa) is the most common tumor of the urinary system. Chronic inflammation in the papillary urothelial neoplasm of low malignant potential (PUNLMP)may contribute to carcinogenesis, including that of BCa, via poorly understood mechanisms. In this study, we show that the lymphotoxin β receptor (LTβR) is upregulated in BCa via activation of the canonical and non-canonical nuclear factor-κB (NF-κB) pathways. The mRNA expression of LTβR in 81 BCa, 10 chronic cystitis and 23 healthy bladder mucosa tissues was investigated by reverse transcription-fluorescent quantitative polymerase chain reaction (RT-FQ-PCR), and protein expression was studied in 73 BCa, 30 cystitis and 15 healthy paraffin-embedded tissue sections by immunohistochemistry. Both LTβR mRNA and protein were upregulated in BCa and cystitis compared to the healthy group (P<0.05). The mRNA level of the downstream NF-κB canonical pathway p65 gene and of the non-canonical pathway RelB gene were higher in the BCa and cystitis groups compared to the healthy one. The level of phosphorylated p65 (p-p65) protein of the canonical NF-κB pathway and that of p52, a protein of the non-canonical NF-κB pathway, were also higher in the BCa and cystitis group compared to the healthy group. The levels of these proteins significantly correlated to the pathological grade, clinical stage and lymph node metastasis of BCa patients (P<0.05). In addition, there was a positive correlation between LTβR and NF-κB pathway proteins. Thus, LTβR signaling may be involved in promoting BCa through the NF-κB pathway, and which may represent the molecular link between inflammation and BCa.

Galectin-9 signaling through TIM-3 is involved in neutrophil-mediated Gram-negative bacterial killing: an effect abrogated within the cystic fibrosis lung

The T cell Ig and mucin domain-containing molecule (TIM) family of receptors have emerged as potential therapeutic targets to correct abnormal immune function in chronic inflammatory conditions. TIM-3 serves as a functional receptor in structural cells of the airways and via the ligand galectin-9 (Gal-9) can modulate the inflammatory response. The aim of this study was to investigate TIM-3 expression and function in neutrophils, focusing on its potential role in cystic fibrosis (CF) lung disease. Results revealed that TIM-3 mRNA and protein expression values of circulating neutrophils were equal between healthy controls (n = 20) and people with CF (n = 26). TIM-3 was detected on resting neutrophil membranes by FACS analysis, and expression levels significantly increased post IL-8 or TNF-α exposure (p < 0.05). Our data suggest a novel role for TIM-3/Gal-9 signaling involving modulation of cytosolic calcium levels. Via TIM-3 interaction, Gal-9 induced neutrophil degranulation and primed the cell for enhanced NADPH oxidase activity. Killing of Pseudomonas aeruginosa was significantly increased upon bacterial opsonization with Gal-9 (p < 0.05), an effect abrogated by blockade of TIM-3 receptors. This mechanism appeared to be Gram-negative bacteria specific and mediated via Gal-9/ LPS binding. Additionally, we have demonstrated that neutrophil TIM-3/Gal-9 signaling is perturbed in the CF airways due to proteolytic degradation of the receptor. In conclusion, results suggest a novel neutrophil defect potentially contributing to the defective bacterial clearance observed in the CF airways and suggest that manipulation of the TIM-3 signaling pathway may be of therapeutic value in CF, preferably in conjunction with antiprotease treatment.

Constitutive activation of nuclear factor κB contributes to cystic fibrosis transmembrane conductance regulator expression and promotes human cervical cancer progression and poor prognosis

OBJECTIVE

Cystic fibrosis transmembrane conductance regulator (CFTR) and nuclear factor κB (NF-κB) have been known to play important roles in the development and progression of many types of cancer including cervical cancer. The study aimed to verify the relevance and significance of CFTR and NF-κB expressions in cervical cancer tissues and cell lines.

METHODS

The expressions of CFTR and NF-κB p65 were analyzed respectively by immunohistochemistry in total of 135 cervical tissue samples. The correlation to clinicopathologic characteristics and prognostic value was evaluated. The coexpression of CFTR and NF-κB was detected in cervical cancer cell lines. Nuclear factor κB signaling was inhibited by siRNA for NF-κB p65 and activated by stimulation of cells with interleukin β or tumor necrosis factor α.

RESULTS

We found both the membrane expression of CFTR and nuclear translocation of NF-κB p65 were progressively increased from normal cervical tissue, cervical intraepithelial neoplasm, to cervical cancer (overall R² = 0.74, P < 0.001). Cystic fibrosis transmembrane conductance regulator expression and NF-κB activation were also positively associated with stage, histological grade, lymph node metastasis, and invasive interstitial depth. Multivariate analysis showed that coexpression of CFTR and NF-κB was an independent prognostic factor for survival (relative risk, 5.16; P = 0.003). Dual-immunofluorescence analysis showed CFTR and NF-κB were coexpressed in cervical cancer. Studies in vitro revealed that the expression levels of CFTR mRNA and protein were positively related to NF-κB activation.

CONCLUSIONS

Cystic fibrosis transmembrane conductance regulator and NF-κB were coexpressed in cervical cancer, and the activation of NF-κB mediated the expression of CFTR. Multivariate analysis revealed that coexpression of CFTR and NF-κB was associated with poor prognosis in patients with cervical cancer.

Regulation of ion channels and transporters by AMP-activated kinase (AMPK)

The energy-sensing AMP-activated kinase AMPK ensures survival of energy-depleted cells by stimulating ATP production and limiting ATP utilization. Both energy production and energy consumption are profoundly influenced by transport processes across the cell membane including channels, carriers and pumps. Accordingly, AMPK is a powerful regulator of transport across the cell membrane. AMPK regulates diverse K(+) channels, Na(+) channels, Ca(2+) release activated Ca(2+) channels, Cl(-) channels, gap junctional channels, glucose carriers, Na(+)/H(+)-exchanger, monocarboxylate-, phosphate-, creatine-, amino acid-, peptide- and osmolyte-transporters, Na(+)/Ca(2+)-exchanger, H(+)-ATPase and Na(+)/K(+)-ATPase. AMPK activates ubiquitin ligase Nedd4-2, which labels several plasma membrane proteins for degradation. AMPK further regulates transport proteins by inhibition of Rab GTPase activating protein (GAP) TBC1D1. It stimulates phosphatidylinositol 3-phosphate 5-kinase PIKfyve and inhibits phosphatase and tensin homolog (PTEN) via glycogen synthase kinase 3β (GSK3β). Moreover, it stabilizes F-actin as well as downregulates transcription factor NF-κB. All those cellular effects serve to regulate transport proteins.

Normal CFTR inhibits epidermal growth factor receptor-dependent pro-inflammatory chemokine production in human airway epithelial cells

Mutations in cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis, a disease characterized by exaggerated airway epithelial production of the neutrophil chemokine interleukin (IL)-8, which results in exuberant neutrophilic inflammation. Because activation of an epidermal growth factor receptor (EGFR) signaling cascade induces airway epithelial IL-8 production, we hypothesized that normal CFTR suppresses EGFR-dependent IL-8 production and that loss of CFTR at the surface exaggerates IL-8 production via activation of a pro-inflammatory EGFR cascade. We examined this hypothesis in human airway epithelial (NCI-H292) cells and in normal human bronchial epithelial (NHBE) cells containing normal CFTR treated with a CFTR-selective inhibitor (CFTR-172), and in human airway epithelial (IB3) cells containing mutant CFTR versus isogenic (C38) cells containing wild-type CFTR. In NCI-H292 cells, CFTR-172 induced IL-8 production EGFR-dependently. Pretreatment with an EGFR neutralizing antibody or the metalloprotease TACE inhibitor TAPI-1, or TACE siRNA knockdown prevented CFTR-172-induced EGFR phosphorylation (EGFR-P) and IL-8 production, implicating TACE-dependent EGFR pro-ligand cleavage in these responses. Pretreatment with neutralizing antibodies to IL-1R or to IL-1alpha, but not to IL-1beta, markedly suppressed CFTR-172-induced EGFR-P and IL-8 production, suggesting that binding of IL-1alpha to IL-1R stimulates a TACE-EGFR-IL-8 cascade. Similarly, in NHBE cells, CFTR-172 increased IL-8 production EGFR-, TACE-, and IL-1alpha/IL-1R-dependently. In IB3 cells, constitutive IL-8 production was markedly increased compared to C38 cells. EGFR-P was increased in IB3 cells compared to C38 cells, and exaggerated IL-8 production in the IB3 cells was EGFR-dependent. Activation of TACE and binding of IL-1alpha to IL-1R contributed to EGFR-P and IL-8 production in IB3 cells but not in C38 cells. Thus, we conclude that normal CFTR suppresses airway epithelial IL-8 production that occurs via a stimulatory EGFR cascade, and that loss of normal CFTR activity exaggerates IL-8 production via activation of a pro-inflammatory EGFR cascade.

Downregulation of CFTR promotes epithelial-to-mesenchymal transition and is associated with poor prognosis of breast cancer

The epithelial-to-mesenchymal transition (EMT), a process involving the breakdown of cell-cell junctions and loss of epithelial polarity, is closely related to cancer development and metastatic progression. While the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) and HCO3(-) conducting anion channel expressed in a wide variety of epithelial cells, has been implicated in the regulation of epithelial polarity, the exact role of CFTR in the pathogenesis of cancer and its possible involvement in EMT process have not been elucidated. Here we report that interfering with CFTR function either by its specific inhibitor or lentiviral miRNA-mediated knockdown mimics TGF-β1-induced EMT and enhances cell migration and invasion in MCF-7. Ectopic overexpression of CFTR in a highly metastatic MDA-231 breast cancer cell line downregulates EMT markers and suppresses cell invasion and migration in vitro, as well as metastasis in vivo. The EMT-suppressing effect of CFTR is found to be associated with its ability to inhibit NFκB targeting urokinase-type plasminogen activator (uPA), known to be involved in the regulation of EMT. More importantly, CFTR expression is found significantly downregulated in primary human breast cancer samples, and is closely associated with poor prognosis in different cohorts of breast cancer patients. Taken together, the present study has demonstrated a previously undefined role of CFTR as an EMT suppressor and its potential as a prognostic indicator in breast cancer.

Quantification of major urinary metabolites of PGE2 and PGD2 in cystic fibrosis: correlation with disease severity

Cystic fibrosis transmembrane conductance (CFTR) alterations are involved in the overproduction of prostaglandins (PG) in CF in vitro. We assessed the relationship between PGE-M and PGD-M urinary metabolites of PGE2 and PGD2 and CF severity. Twenty-four controls and 35 CF patients were recruited. PGE-M and PGD-M levels were measured by liquid chromatography/mass spectrometry and results were expressed as median and 25th-75th interquartile of ng/mg creatinine (Cr). PGE-M (15.63; 9.07-43.35ng/mg Cr) and PGD-M (2.16; 1.43-3.53ng/mg Cr) concentrations were higher in CF than in controls: PGE-M, (6.63; 4.35-8.60ng/mg Cr); PGD-M (1.23; 0.96-1.54ng/mg Cr). There was no correlation between metabolite levels and spirometric values. Patients with pancreatic insufficiency (n=29) had higher PGE-M levels (19.09; 9.36-52.69ng/mg Cr) than those with conserved function (n=6) (9.61; 5.78-14.34ng/mg Cr). PGE-M levels were associated with genotype severity: mild (7.14; 5.76-8.76, n=8), moderate (16.67; 13.67-28.62ng/mg Cr, n=5) and severe (22.82; 10.67-84.13ng/mg Cr). Our study confirms the key role of CFTR in the regulation of the cyclooxygenase pathway of arachidonic acid metabolism found in in vitro studies.

Cystic fibrosis CFBE41o- cells contain TLR1 SNP I602S and fail to respond to Mycobacterium abscessus

BACKGROUND

Mycobacterium abscessus causes lung infection in patients with cystic fibrosis. M. abscessus stimulates the host innate immune response via TLR2 on respiratory epithelial cells. Signaling through TLR2 requires the formation of TLR2/TLR1 heterodimers on the cell surface.

METHODS

The ability of M. abscessus to stimulate the innate immune response of cystic fibrosis CFBE41o- respiratory epithelial cells was measured as expression of HβD2 by RT PCR, and release of IL-8 by ELISA. Genotyping of CFBE41o- TLR polymorphisms was carried out.

RESULTS

CFBE41o- cells are hyporesponsive to M. abscessus. They are homozygous for the TLR1 SNP I602S which has been demonstrated to cause diminished cellular responses to TLR2 agonists.

CONCLUSIONS

Homozygosity for I602S is prevalent in Western Europeans and North American Caucasians, the same demographic in which the ΔF508 mutation is present. This SNP may play a role in the pathogenesis of M. abscessus lung infection in patients with cystic fibrosis.

CFTR mutations altering CFTR fragmentation

Most CF (cystic fibrosis) results from deletion of a phenylalanine (F⁵⁰⁸) in the CFTR {CF transmembrane-conductance regulator; ABCC7 [ABC (ATP-binding cassette) sub-family C member 7]} which causes ER (endoplasmic reticulum) degradation of the mutant. Using stably CFTR-expressing BHK (baby-hamster kidney) cell lines we demonstrated that wild-type CTFR and the F508delCFTR mutant are cleaved into differently sized N- and C-terminal-bearing fragments, with each hemi-CFTR carrying its nearest NBD (nucleotide-binding domain), reflecting differential cleavage through the central CFTR R-domain. Similar NBD1-bearing fragments are present in the natively expressing HBE (human bronchial epithelial) cell line. We also observe multiple smaller fragments of different sizes in BHK cells, particularly after F508del mutation (ladder pattern). Trapping wild-type CFTR in the ER did not generate a F508del fragmentation fingerprint. Fragments change their size/pattern again post-mutation at sites involved in CFTR's in vitro interaction with the pleiotropic protein kinase CK2 (S511A in NBD1). The F508del and S511A mutations generate different fragmentation fingerprints that are each unlike the wild-type; yet, both mutants generate new N-terminal-bearing CFTR fragments that are not observed with other CK2-related mutations (S511D, S422A/D and T1471A/D). We conclude that the F508delCFTR mutant is not degraded completely and there exists a relationship between CFTR's fragmentation fingerprint and the CFTR sequence through putative CK2-interactive sites that lie near F508.

Targeting the Intracellular Environment in Cystic Fibrosis: Restoring Autophagy as a Novel Strategy to Circumvent the CFTR Defect

Cystic fibrosis (CF) patients harboring the most common deletion mutation of the CF transmembrane conductance regulator (CFTR), F508del, are poor responders to potentiators of CFTR channel activity which can be used to treat a small subset of CF patients who genetically carry plasma membrane (PM)-resident CFTR mutants. The misfolded F508del-CFTR protein is unstable in the PM even if rescued by pharmacological agents that prevent its intracellular retention and degradation. CF is a conformational disease in which defective CFTR induces an impressive derangement of general proteostasis resulting from disabled autophagy. In this review, we discuss how rescuing Beclin 1 (BECN1), a major player of autophagosome formation, either by means of direct gene transfer or indirectly by administration of proteostasis regulators, could stabilize F508del-CFTR at the PM. We focus on the relationship between the improvement of peripheral proteostasis and CFTR PM stability in F508del-CFTR homozygous bronchial epithelia or mouse lungs. Moreover, this article reviews recent pre-clinical evidence indicating that targeting the intracellular environment surrounding the misfolded mutant CFTR instead of protein itself could constitute an attractive therapeutic option to sensitize patients carrying the F508del-CFTR mutation to the beneficial action of CFTR potentiators on lung inflammation.

Association of cystic fibrosis transmembrane conductance regulator gene variants with acute lung injury in African American children with pneumonia*

OBJECTIVES

The cystic fibrosis transmembrane conductance regulator regulates fluid balance in alveolar epithelial cells and appears to modulate the inflammatory response. To determine whether more severe lung injury in children who develop community-acquired pneumonia is associated with variations known to affect function in the gene coding for cystic fibrosis transmembrane conductance regulator.

DESIGN

A prospective cohort genetic association study of lung injury in children with community-acquired pneumonia.

SETTING

Three major tertiary care children's hospitals.

SUBJECTS

Caucasian and African American children with community-acquired pneumonia either evaluated in the emergency department or admitted to the hospital.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Caucasian and African American children with pneumonia were genotyped for the most common variants reported to affect cystic fibrosis transmembrane conductance regulator function, the p.508del mutation, the (TG)mTn variable repeat region, and the M470V polymorphism in the cystic fibrosis transmembrane conductance regulator gene. Genotypes and haplotypes were determined, and the association of high-risk alleles or high-risk haplotypes (defined as the presence of at least one variant known to decrease the level of functional cystic fibrosis transmembrane conductance regulator) with the need for mechanical ventilation or the development of acute lung injury was evaluated. Forty-two children in the Caucasian cohort (n = 304) required mechanical ventilation; 32 developed acute lung injury. Forty-three children in the African American cohort (n = 474) required mechanical ventilation; 29 developed acute lung injury. In African American children, high-risk (TG)mTn alleles known to result in decreased levels of functional cystic fibrosis transmembrane conductance regulator were associated with the need for mechanical ventilation (p = .0013) and the development of acute lung injury (p = .0061). Multivariable analysis demonstrated that high-risk (TG)mTn alleles were independently associated with mechanical ventilation (odds ratios = 3.19; 95% confidence interval, 1.63-6.26) and acute lung injury (odds ratios = 3.36; 95% confidence interval, 1.50-7.53) in African American children.

CONCLUSION

Genetic variation in cystic fibrosis transmembrane conductance regulator is associated with acute lung injury in African American children with community-acquired pneumonia.

Atypical activation of the unfolded protein response in cystic fibrosis airway cells contributes to p38 MAPK-mediated innate immune responses

Inflammatory lung disease is the major cause of morbidity and mortality in cystic fibrosis (CF); understanding what produces dysregulated innate immune responses in CF cells will be pivotal in guiding the development of novel anti-inflammatory therapies. To elucidate the molecular mechanisms that mediate exaggerated inflammation in CF following TLR signaling, we profiled global gene expression in immortalized human CF and non-CF airway cells at baseline and after microbial stimulation. Using complementary analysis methods, we observed a signature of increased stress levels in CF cells, specifically characterized by endoplasmic reticulum (ER) stress, the unfolded protein response (UPR), and MAPK signaling. Analysis of ER stress responses revealed an atypical induction of the UPR, characterized by the lack of induction of the PERK-eIF2α pathway in three complementary model systems: immortalized CF airway cells, fresh CF blood cells, and CF lung tissue. This atypical pattern of UPR activation was associated with the hyperinflammatory phenotype in CF cells, as deliberate induction of the PERK-eIF2α pathway with salubrinal attenuated the inflammatory response to both flagellin and Pseudomonas aeruginosa. IL-6 production triggered by ER stress and microbial stimulation were both dependent on p38 MAPK activity, suggesting a molecular link between both signaling events. These data indicate that atypical UPR activation fails to resolve the ER stress in CF and sensitizes the innate immune system to respond more vigorously to microbial challenge. Strategies to restore ER homeostasis and normalize the UPR activation profile may represent a novel therapeutic approach to minimize lung-damaging inflammation in CF.

NF κB expression increases and CFTR and MUC1 expression decreases in the endometrium of infertile patients with hydrosalpinx: a comparative study

BACKGROUND

Hydrosalpinx are associated with infertility, due to reduced rates of implantation and increased abortion rates. The aims of this study were to investigate the expression of cystic fibrosis transmembrane conductance regulator (CFTR), nuclear factor kappa B (NF KappaB) and mucin-1 (MUC-1), and analyze the correlation between the expression of CFTR and NF KappaB or MUC1, in the endometrium of infertile women with and without hydrosalpinx.

METHODS

Thirty-one infertile women with laparoscopy-confirmed unilateral or bilateral hydrosalpinx and 20 infertile women without hydrosalpinx or pelvic inflammatory disease (control group) were recruited. Endometrial biopsy samples were collected and the expression of CFTR, NF KappaB and MUC1 were analyzed using immunohistochemistry and quantitative real-time PCR.

RESULTS

CFTR, NF KappaB and MUC1 mRNA and protein expression tended to increase in the secretory phase compared to the proliferative phase in both groups; however, these differences were not significantly different. The endometrium of infertile patients with hydrosalpinx had significantly higher NF KappaB mRNA and protein expression, and significantly lower CFTR and MUC1 mRNA and protein expression, compared to control infertile patients. A positive correlation was observed between CFTR and MUC1 mRNA expression (r = 0.65, P < 0.05); a negative correlation was observed between CFTR mRNA and NF KappaB mRNA expression (r = -0.59, P < 0.05).

CONCLUSIONS

Increased NF KappaB expression and decreased CFTR and MUC1 expression in the endometrium of infertile patients with hydrosalpinx reinforce the involvement of a molecular mechanism in the regulation of endometrial receptivity.

Proinflammatory cytokine secretion is suppressed by TMEM16A or CFTR channel activity in human cystic fibrosis bronchial epithelia

Functional expression of either CFTR or the calcium-activated chloride channel TMEM16A attenuates expression and secretion of the proinflammatory cytokines IL-6, IL-8, and CXCL1/2 in respiratory epithelia. Thus augmented proinflammatory cytokine secretion caused by defective anion transport may contribute to lung inflammation in cystic fibrosis.

Cystic fibrosis (CF) is caused by the functional expression defect of the CF transmembrane conductance regulator (CFTR) chloride channel at the apical plasma membrane. Impaired bacterial clearance and hyperactive innate immune response are hallmarks of the CF lung disease, yet the existence of and mechanism accounting for the innate immune defect that occurs before infection remain controversial. Inducible expression of either CFTR or the calcium-activated chloride channel TMEM16A attenuated the proinflammatory cytokines interleukin-6 (IL-6), IL-8, and CXCL1/2 in two human respiratory epithelial models under air–liquid but not liquid–liquid interface culture. Expression of wild-type but not the inactive G551D-CFTR indicates that secretion of the chemoattractant IL-8 is inversely proportional to CFTR channel activity in cftr^{∆F508/∆F508} immortalized and primary human bronchial epithelia. Similarly, direct but not P2Y receptor–mediated activation of TMEM16A attenuates IL-8 secretion in respiratory epithelia. Thus augmented proinflammatory cytokine secretion caused by defective anion transport at the apical membrane may contribute to the excessive and persistent lung inflammation in CF and perhaps in other respiratory diseases associated with documented down-regulation of CFTR (e.g., chronic obstructive pulmonary disease). Direct pharmacological activation of TMEM16A offers a potential therapeutic strategy to reduce the inflammation of CF airway epithelia.

Inhibition of cellular and systemic inflammation cues in human bronchial epithelial cells by melanocortin-related peptides: mechanism of KPV action and a role for MC3R agonists

BACKGROUND/AIMS

Chemokine signaling from airway epithelium regulates macrophage recruitment to the lung in inflammatory diseases such as asthma. This study investigates the mechanism by which the α-melanocyte stimulating hormone-derived tripeptide, KPV, and the agonist of the dominant melanocortin receptor in airway epithelium (MC3R), γ-melanocyte stimulating hormone (γ-MSH), suppress inflammation in immortalised human bronchial airway epithelium.

METHODS

TNFα and rhino syncitial virus (RSV)-evoked nuclear factor-κB (NFκB) signaling was measured in immortalised human bronchial epithelial cells (16HBE14o-) in response to KPV and γMSH. Cellular and systemic inflammatory signaling was measured by NFκB reporter gene and chemokine (IL8, eotaxin) secretion, respectively.

RESULTS

KPV and γMSH evoked a dose-dependent inhibition of NFκB, matrix metalloproteinase-9 activity, IL8 and eotaxin secretion. The KPV effect was associated with its nuclear import, IκBα stabilisation and suppressed nuclear translocation of YFP-tagged p65RelA. Competition assays revealed an interaction between KPV and the Imp-α3 binding site on p65RelA which may involve blockade of the importin-α armadillo domain 7 and 8. In contrast, the γMSH anti-inflammatory effect required MC3R whose apical expression occurred in epithelium distributed along the length of the respiratory tree in vivo.

CONCLUSION

KPV and γMSH respectively suppress NFκB signalling in airway epithelium by: i) inhibition of p65RelA nuclear import and, ii) epithelial MC3R activation. Melanocortin peptides therefore provide a robust mechanism for targeting airway inflammation in lung disease.

Inflammasome-mediated IL-1β production in humans with cystic fibrosis

BACKGROUND

Inflammation and infection are major determinants of disease severity and consequently, the quality of life and outcome for patients with cystic fibrosis (CF). Interleukin-1 beta (IL-1β) is a key inflammatory mediator. Secretion of biologically active IL-1β involves inflammasome-mediated processing. Little is known about the contribution of IL-1β and the inflammasomes in CF inflammatory disease. This study examines inflammasome-mediated IL-1β production in CF bronchial epithelial cell lines and human patients with CF.

RESULTS

Bronchial epithelial cell lines were found to produce negligible amounts of basal or stimulated IL-1β compared to hematopoeitic cells and they did not significantly upregulate caspase-1 activity upon inflammasome stimulation. In contrast, peripheral blood mononuclear cells (PBMCs) from both CF and healthy control subjects produced large amounts of IL-1β and strongly upregulated caspase-1 activity upon inflammasome stimulation. PBMCs from CF patients and controls displayed similar levels of caspase-1 activation and IL-1β production when stimulated with inflammasome activators. This IL-1β production was dependent on NF-κB activity and could be enhanced by priming with LPS. Finally, chemical inhibition of CFTR activity in control PBMCs and THP-1 cells did not significantly alter IL-1β or IL-8 production in response to P. aeruginosa.

CONCLUSION

Hematopoeitic cells appear to be the predominant source of inflammasome-induced pro-inflammatory IL-1β in CF. PBMCs derived from CF subjects display preserved inflammasome activation and IL-1β secretion in response to the major CF pathogen Pseudomonas aeruginosa. However, our data do not support the hypothesis that increased IL-1β production in CF subjects is due to an intrinsic increase in NF-κB activity through loss of CFTR function.

Regulatory role of β-arrestin-2 in cholesterol processing in cystic fibrosis epithelial cells

Cystic fibrosis (CF) cells exhibit an increase in the protein expression of β-arrestin-2 (βarr2) coincident with perinuclear accumulation of free cholesterol. Arrestins are proteins that both serve as broad signaling regulators and contribute to G-protein coupled receptor internalization after agonist stimulation. The hypothesis of this study is that βarr2 is an important component in the mechanisms leading to cholesterol accumulation characteristic of CF cells. To test this hypothesis, epithelial cells stably expressing GFP-tagged βarr2 (βarr2-GFP) and respective GFP-expressing control cells (cont-GFP) were analyzed by filipin staining. The βarr2-GFP cells show a late endosomal/lysosomal cholesterol accumulation that is identical to that seen in CF cells. This βarr2-mediated accumulation is sensitive to Rp-cAMPS treatment, and depleting βarr2 expression in CF-model cells by shRNA alleviates cholesterol accumulation compared with controls. Cftr/βarr2 double knockout mice also exhibit wild-type (WT) levels of cholesterol synthesis, and WT profiles of signaling protein expression have previously been shown to be altered in CF due to cholesterol-related pathways. These data indicate a significant regulatory role for βarr2 in the development of CF-like cholesterol accumulation and give further insight into cholesterol processing mechanisms. An impact of βarr2 expression on Niemann-Pick type C-1 (NPC1)-containing organelle movement is proposed as the mechanism of βarr2-mediated alterations on cholesterol processing. It is concluded that βarr2 expression contributes to altered cholesterol trafficking observed in CF cells.

CFTR negatively regulates cyclooxygenase-2-PGE(2) positive feedback loop in inflammation

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent anion channel mostly expressed in epithelia. Accumulating evidence suggests that CF airway epithelia are overwhelmed by excessive inflammatory cytokines and prostaglandins (PGs), which eventually lead to the over-inflammatory condition observed in CF lung disease. However, the exact underlying mechanism remains elusive. In this study, we observed increased cyclooxygenase-2 (COX-2) expression and over-production of prostaglandin E(2) (PGE(2)) in human CF bronchial epithelia cell line (CFBE41o--) with elevated NF-κB activity compared to a wild-type airway epithelial cell line (16HBE14o--). Moreover, we demonstrated that CFTR knockout mice had inherently higher levels of COX-2 and NF-κB activity, supporting the notion that lack of CFTR results in hyper-inflammatory signaling. In addition, we identified a positive feedback loop for production of PGE(2) involving PKA and transcription factor, CREB. More importantly, overexpression of wild-type CFTR significantly suppressed COX-2 expression in CFBE41o- cells, and wild-type CFTR protein expression was significantly increased when 16HBE14o-- cells were challenged with LPS as well as PGE(2), indicating possible involvement of CFTR in negative regulation of COX-2/PGE(2). In conclusion, CFTR is a negative regulator of PGE(2)-mediated inflammatory response, defect of which may result in excessive activation of NF-κB, leading to over production of PGE(2) as seen in inflammatory CF tissues.

Overexpression of cystic fibrosis transmembrane conductance regulator (CFTR) is associated with human cervical cancer malignancy, progression and prognosis

OBJECTIVE

To investigate the correlation of cystic fibrosis transmembrane conductance regulator (CFTR) to cervical cancer progression and prognosis by examining CFTR expression levels in different cervical tissues and cell lines.

METHODS

Paraffin-embedded cervical tissue samples (n=192) were collected for immunohistochemistry (IHC), while fresh cervical tissue samples (n=165) and human cervical cell lines were collected for protein and mRNA detection by quantitative real-time PCR and western blot, respectively. Correlations between CFTR expression levels to cancer clinicopathologic features and prognosis were statistically analyzed.

RESULTS

Both CFTR mRNA and protein expression gradually increased from normal to precancerous (LSIL, HSIL) and cervical cancer tissues (p<0.05). Furthermore, CFTR expression level was well-correlated to tumor stage (p<0.001), histological grades (p<0.001), lymphatic metastasis (p<0.001), vascular invasion (p<0.05), interstitial invasive depth (p<0.05), tumor size (p<0.05) and HPV infection (p<0.05). In vitro, CFTR mRNA and protein were expressed strongly both in SiHa and HeLa, but little was seen in Caski and H8 (p<0.05). More importantly, overexpression of CFTR conferred significantly poorer survival in cervical carcinoma (Log rank p=0.028), although it was not an independent predictor for prognosis according to multivariate analysis (p>0.05).

CONCLUSIONS

These results suggest that higher CFTR expression is closely associated with cervical cancer progression, aggressive behaviors and poorer prognosis, indicating that CFTR may function as a novel tumor marker, a prospective prognostic indicator and a potential therapeutic target for cervical cancer.

Ancestral haplotype 8.1 and lung disease severity in European cystic fibrosis patients

BACKGROUND

The clinical course of cystic fibrosis (CF) lung disease varies between patients bearing identical CFTR mutations. This suggests that additional genetic modifiers may contribute to the pulmonary phenotype. The highly conserved ancestral haplotype 8.1 (8.1AH), carried by up to one quarter of Caucasians, comprises linked gene polymorphisms on chromosome 6 that play a key role in the inflammatory response: LTA +252A/G; TNF -308G/A, HSP70-2 +1267A/G and RAGE -429T/C. As inflammation is a key component inducing CF lung damage, we investigated whether the 8.1AH represents a lung function modifier in CF.

METHODS

We analyzed the lung function of 404 European CF patients from France (n=230), Germany (n=95) and UK (n=79). FEV(1) differences between 8.1AH carriers and non-carriers were calculated in each country and pooled using a random effects model.

RESULTS

The frequency of 8.1AH carriers was similar between French (22%), German (29%) and UK (27%) patients. We found that 8.1AH carriers had significantly lower FEV(1), adjusted for age classes and countries (P<0.04, mean FEV(1) difference -6.4% CI95% [-12.4%, -0.5%]). No difference was observed with respect to BMI Z-scores and chronic colonization with P. aeruginosa.

CONCLUSIONS

These findings support the concept that 8.1AH is an important genetic modifier of lung disease in CF. To conclude, multiple linked genes outside the CF locus might explain some of the variability in lung phenotype.

Infection of polarized airway epithelial cells by normal and small-colony variant strains of Staphylococcus aureus is increased in cells with abnormal cystic fibrosis transmembrane conductance regulator function and is influenced by NF-κB

The infection of nonphagocytic host cells by Staphylococcus aureus and more particularly by small-colony variants (SCVs) may contribute to the persistence of this pathogen in the lungs of cystic fibrosis (CF) patients. The development of chronic infections is also thought to be facilitated by the proinflammatory status of CF airways induced by an activation of NF-κB. The aim of this study was to compare the infection of non-CF and CF-like airway epithelial cells by S. aureus strains (normal and SCVs) and to determine the impact of the interaction between cystic fibrosis transmembrane conductance regulator (CFTR) and NF-κB on the infection level of these cells by S. aureus. We developed an S. aureus infection model using polarized airway epithelial cells grown at the air-liquid interface and expressing short hairpin RNAs directed against CFTR to mimic the CF condition. A pair of genetically related CF coisolates with the normal and SCV phenotypes was characterized and used. Infection of both cell lines (non-CF and CF-like) was more productive with the SCV strain than with its normal counterpart. However, both normal and SCV strains infected more CF-like than non-CF cells. Accordingly, inhibition of CFTR function by CFTRinh-172 increased the S. aureus infection level. Experimental activation of NF-κB also increased the level of infection of polarized pulmonary epithelial cells by S. aureus, an event that could be associated with that observed when CFTR function is inhibited or impaired. This study supports the hypothesis that the proinflammatory status of CF tissues facilitates the infection of pulmonary epithelial cells by S. aureus.

Understanding protein kinase CK2 mis-regulation upon F508del CFTR expression

We review areas of overlap between nucleoside diphosphate kinase (NDPK; nm23) and two proteins manifesting an equivalent diversity of action, each with many thousands of publications. The first is a constitutively active protein kinase, CK2 (formerly casein kinase 2), that includes NDPK amongst its hundreds of targets. The second is an enigmatic member of the ATP-binding cassette (ABC) family of membrane pumps that normally hydrolyse ATP to transport substrates. Yet our unusual family member (ABCC7) is not a pump but, uniquely, acts as a regulated anion channel. ABCC7 is the cystic fibrosis transmembrane conductance regulator (CFTR), and we discuss the highly prevalent CFTR mutation (F508del CFTR) in terms of the uncertainties surrounding the molecular basis of cystic fibrosis that cloud approaches to corrective therapy. Using lysates from cells stably expressing either wild-type or F508del CFTR, incubated with the CK2 substrate GTP, we show that the phosphoproteome of F508del CFTR-expressing cells both differs from wild-type CFTR-expressing cells and is significantly enhanced in intensity by ∼1.5-fold (p < 0.05, paired t test with Bonferroni correction, n = 4). Phosphorylation is about 50% attenuated with a specific CK2 inhibitor. We propose that a new function may exist for the CFTR region that is commonly mutated, noting that its sequence (PGTIKENIIF₅₀₈GVSYDEYRYR) is not only highly conserved within the C sub-family of ABC proteins but also a related sequence is found in NDPK. We conclude that a latent path may exist between mutation of this conserved sequence, CK2 hyperactivity and disease pathogenesis that might also explain the heterozygote advantage for the common F508del CFTR mutant .

Dysregulation of TIM-3-galectin-9 pathway in the cystic fibrosis airways

The T-cell Ig and mucin domain-containing molecules (TIMs) have emerged as promising therapeutic targets to correct abnormal immune function in several autoimmune and chronic inflammatory conditions. It has been reported that proinflammatory cytokine dysregulation and neutrophil-dominated inflammation are the main causes of morbidity in cystic fibrosis (CF). However, the role of TIM receptors in CF has not been investigated. In this study, we demonstrated that TIM-3 is constitutively overexpressed in the human CF airway, suggesting a link between CF transmembrane conductance regulator (CFTR) function and TIM-3 expression. Blockade of CFTR function with the CFTR inhibitor-172 induced an upregulation of TIM-3 and its ligand galectin-9 in normal bronchial epithelial cells. We also established that TIM-3 serves as a functional receptor in bronchial epithelial cells, and physiologically relevant concentrations of galectin-9 induced TIM-3 phosphorylation, resulting in increased IL-8 production. In addition, we have demonstrated that both TIM-3 and galectin-9 undergo rapid proteolytic degradation in the CF lung, primarily because of neutrophil elastase and proteinase-3 activity. Our results suggest a novel intrinsic defect that may contribute to the neutrophil-dominated immune response in the CF airways.

Critical modifier role of membrane-cystic fibrosis transmembrane conductance regulator-dependent ceramide signaling in lung injury and emphysema

Ceramide accumulation mediates the pathogenesis of chronic obstructive lung diseases. Although an association between lack of cystic fibrosis transmembrane conductance regulator (CFTR) and ceramide accumulation has been described, it is unclear how membrane-CFTR may modulate ceramide signaling in lung injury and emphysema. Cftr(+/+) and Cftr(-/-) mice and cells were used to evaluate the CFTR-dependent ceramide signaling in lung injury. Lung tissue from control and chronic obstructive pulmonary disease patients was used to verify the role of CFTR-dependent ceramide signaling in pathogenesis of chronic emphysema. Our data reveal that CFTR expression inversely correlates with severity of emphysema and ceramide accumulation in chronic obstructive pulmonary disease subjects compared with control subjects. We found that chemical inhibition of de novo ceramide synthesis controls Pseudomonas aeruginosa-LPS-induced lung injury in Cftr(+/+) mice, whereas its efficacy was significantly lower in Cftr(-/-) mice, indicating that membrane-CFTR is required for controlling lipid-raft ceramide levels. Inhibition of membrane-ceramide release showed enhanced protective effect in controlling P. aeruginosa-LPS-induced lung injury in Cftr(-/-) mice compared with that in Cftr(+/+) mice, confirming our observation that CFTR regulates lipid-raft ceramide levels and signaling. Our results indicate that inhibition of de novo ceramide synthesis may be effective in disease states with low CFTR expression like emphysema and chronic lung injury but not in complete absence of lipid-raft CFTR as in ΔF508-cystic fibrosis. In contrast, inhibiting membrane-ceramide release has the potential of a more effective drug candidate for ΔF508-cystic fibrosis but may not be effectual in treating lung injury and emphysema. Our data demonstrate the critical role of membrane-localized CFTR in regulating ceramide accumulation and inflammatory signaling in lung injury and emphysema.