J Cyst Fibros. 2021 Aug 12:S1569-1993(21)01339-4. doi: 10.1016/j.jcf.2021.07.020. Online ahead of print.

ABSTRACT

Chronic Pseudomonas aeruginosa (Pa) infection is associated with increased morbidity and mortality in people with cystic fibrosis (CF). There is no gold standard definition of chronic Pa infection in CF. We compared chronic Pa definitions using encounter-based versus annualized data in the Early Pseudomonas Infection Control (EPIC) Observational study cohort, and subsequently compared annualized chronic Pa definitions across a range of U.S. cohorts spanning decades of CF care. We found that an annualized chronic Pa definition requiring at least 1 Pa+ culture in 3 of 4 consecutive years ("Green 3/4") resulted in chronic Pa metrics similar to established encounter-based modified Leeds criteria definitions, including a similar age at and proportion who fulfilled chronic Pa criteria, and a similar proportion with sustained Pa infection after meeting the chronic Pa definition. The Green 3/4 chronic Pa definition will be valuable for longitudinal analyses in cohorts with limited culture frequency.

PMID:34393091 | DOI:10.1016/j.jcf.2021.07.020

Acad Radiol. 2021 Aug 12:S1076-6332(21)00304-4. doi: 10.1016/j.acra.2021.06.017. Online ahead of print.

ABSTRACT

RATIONALE: There is no agreed upon method for quantifying ventilation defect percentage (VDP) with high sensitivity and specificity from hyperpolarized (HP) gas ventilation MR images in multiple pulmonary diseases for both pediatrics and adults, yet identifying such methods will be necessary for future multi-site trials. Most HP gas MRI ventilation research focuses on a specific pulmonary disease and utilizes one quantification scheme for determining VDP. Here we sought to determine the potential of different methods for quantifying VDP from HP 129Xe images in multiple pulmonary diseases through comparison of the most utilized quantification schemes: linear binning and thresholding.

MATERIALS AND METHODS: HP 129Xe MRI was performed in a total of 176 subjects (125 pediatrics and 51 adults, age 20.98±16.48 years) who were either healthy controls (n = 23) or clinically diagnosed with cystic fibrosis (CF) (n = 37), lymphangioleiomyomatosis (LAM) (n = 29), asthma (n = 22), systemic juvenile idiopathic arthritis (sJIA) (n = 11), interstitial lung disease (ILD) (n = 7), or were bone marrow transplant (BMT) recipients (n = 47). HP 129Xe ventilation images were acquired during a ≤16 second breath-hold using a 2D multi-slice gradient echo sequence on a 3T Philips scanner (TR/TE 8.0/4.0ms, FA 10-12°, FOV 300 × 300mm, voxel size≈3 × 3 × 15mm). Images were analyzed using 5 different methods to quantify VDPs: linear binning (histogram normalization with binning into 6 clusters) following either linear or a variant of a nonparametric nonuniform intensity normalization algorithm (N4ITK) bias-field correction, thresholding ≤60% of the mean signal intensity with linear bias-field correction, and thresholding ≤60% and ≤75% of the mean signal intensity following N4ITK bias-field correction. Spirometry was successfully obtained in 84% of subjects.

RESULTS: All quantification schemes were able to label visually identifiable ventilation defects in similar regions within all subjects. The VDPs of control subjects were significantly lower (p<0.05) compared to BMT, CF, LAM, and ILD subjects for most of the quantification methods. No one quantification scheme was better able to differentiate individual disease groups from the control group. Advanced statistical modeling of the VDP quantification schemes revealed that in comparing controls to the combined disease group, N4ITK bias-field corrected 60% thresholding had the highest predictive efficacy, sensitivity, and specificity at the VDP cut-point of 2.3%. However, compared to the thresholding quantification schemes, linear binning was able to capture and label subtle low-ventilation regions in subjects with milder obstruction, such as subjects with asthma.

CONCLUSION: The difference in VDP between healthy controls and patients varied between the different disease states for all quantification methods. Although N4ITK bias-field corrected 60% thresholding was superior in separating the combined diseased group from controls, linear binning is able to better label low-ventilation regions unlike the current, 60% thresholding scheme. For future clinical trials, a consensus will need to be reached on which VDP scheme to utilize, as there are subtle advantages for each for specific disease.

PMID:34393064 | DOI:10.1016/j.acra.2021.06.017

Ann Allergy Asthma Immunol. 2021 Aug 12:S1081-1206(21)00568-8. doi: 10.1016/j.anai.2021.08.010. Online ahead of print.

NO ABSTRACT

PMID:34391901 | DOI:10.1016/j.anai.2021.08.010

J Cyst Fibros. 2021 Aug 11:S1569-1993(21)01340-0. doi: 10.1016/j.jcf.2021.07.021. Online ahead of print.

NO ABSTRACT

PMID:34391678 | DOI:10.1016/j.jcf.2021.07.021

Pediatr Int. 2021 Aug 13. doi: 10.1111/ped.14951. Online ahead of print.

ABSTRACT

BACKGROUND: Cystic fibrosis (CF) is an autosomal recessively inherited disease. Clinical findings vary by age of the patient, the organ systems involved, and the severity of the CFTR gene mutation. Pancreatic and liver involvement is prominent and exocrine pancreatic insufficiency is observed in the majority of patients. Point shear wave elastography (pSWE) is a non-invasive method that can quantitatively determine tissue elasticity and stiffness. In this study, the morphological evaluation of the pancreas was performed using the pSWE technique in pediatric patients diagnosed with CF. The effectiveness of this method for early detection of pancreatic insufficiency was investigated.

METHODS: Fifty-five patients with CF (24 girls, 31 boys) and 60 healthy children (29 girls, 31 boys) without any chronic diseases and who were suitable for the pSWE examination were included in the study.

RESULTS: The mean value of pSWE was 1.12±0.16 in the healthy group and 0.97±0.16 in the patients with cystic fibrosis. There was a statistically significant difference between the two groups (p <0.001). Significant negative correlations were found with between pSWE and age (r:-0.319; p=0.018), height (r:-0.293; p=0.03), serum glucose (r:-0.346; p=0.01), HbA1C (r:-0.592; p=0.02), and duration of the disease (r:-0.806; p<0.001).

CONCLUSION: Investigating pancreatic elasticity and detecting pancreatic insufficiency using pSWE (a simple, inexpensive, and non-invasive method) in the early period before overt laboratory and clinical symptoms of EPI can positively contribute to long-term results in young patients with CF.

PMID:34390069 | DOI:10.1111/ped.14951

Genet Med. 2021 Aug 13. doi: 10.1038/s41436-021-01281-z. Online ahead of print.

NO ABSTRACT

PMID:34389817 | DOI:10.1038/s41436-021-01281-z

J Cyst Fibros. 2021 Aug 10:S1569-1993(21)01308-4. doi: 10.1016/j.jcf.2021.07.010. Online ahead of print.

NO ABSTRACT

PMID:34389256 | DOI:10.1016/j.jcf.2021.07.010

Front Med (Lausanne). 2021 Jul 27;8:598382. doi: 10.3389/fmed.2021.598382. eCollection 2021.

ABSTRACT

Background and Aims: Cystic fibrosis-related liver disease (CFLD) is one of the leading causes of morbidity and mortality in cystic fibrosis (CF). Several non-invasive diagnostic methods have been proposed as screening tools for CFLD. Our aim was to rank all available non-invasive modalities for diagnostic performance. Methods: A systematic search was performed in five medical databases to find studies which reported on any single or composite non-invasive diagnostic test (as an index test) compared to the Debray, the EuroCare or the Colombo criteria (as a reference standard). Ranking was carried out with a Bayesian diagnostic test accuracy network meta-analysis based on superiority indices, calculated for pooled sensitivity (Se) and specificity (Sp) with a 95% confidence interval (CI). The study was registered under CRD42020155846 in PROSPERO. Results: Fifteen studies with 15 index tests and a combination of them were included. The New criteria proposed by Koh et al. - which represent a composite diagnostic definition for CFLD including liver biochemistry, ultrasonography, transient elastography and fibrosis markers-had the best performance for detecting CFLD (Se:94%[CI:58-100], Sp:72%[CI:52-84]); while transient elastography (Se:65%[CI:56-74], Sp:88%[CI:84-91]) and a combination of it with a tissue inhibitor of metalloproteinase-4 measurement (Se:78%[CI:30-100], Sp:64%[CI:18-95%]) proved to be the second and third best options, respectively. In the imaging techniques subgroup, transient elastography (Se:66%[CI:57-72], Sp:88%[CI:85-91%]), acoustic radiation force impulse in the right lobe (Se:54%[CI:33-74], Sp:88%[CI:66-96]) and that in the left lobe (Se:55%[CI:23-81], Sp:82%[CI:50-95]) were ranked the highest. Comparing biochemical markers/fibrosis indices, the measurement of the Forns index (Se:72%[CI:25-99], Sp:63%[CI:16-94]), the aspartate aminotransferase-to-platelet ratio (Se:55%[CI:41-68], Sp:83%[CI:66-89]) and alkaline phosphatase (Se:63%[CI:18-93], Sp:64%[CI:19-95]) were ranked the highest. Conclusion: The New criteria show the best diagnostic performance. In clinical practice, transient elastography seems to be a simple, cheap and non-invasive tool, outperforming imaging, biochemical and fibrosis tests for detecting CFLD. Further studies are needed to validate our findings.

PMID:34386504 | PMC:PMC8353091 | DOI:10.3389/fmed.2021.598382

Front Pharmacol. 2021 Jul 27;12:714452. doi: 10.3389/fphar.2021.714452. eCollection 2021.

ABSTRACT

Cystic Fibrosis (CF) is caused by a defect in the CF transmembrane conductance regulator (CFTR) gene responsible for epithelial ion transport. Nasal potential difference (PD) measurement is a well established diagnostic technique for assessing the efficacy of therapies in CF patients and animal models. The aim was to establish a rapid nasal PD protocol in mice and quantify the efficacy of lentiviral (LV) vector-based CFTR gene therapy. Anaesthetised wild-type (WT) and CF mice were non-surgically intubated and nasal PD measurements were made using a range of buffer flow rates. Addition of the cAMP agonist, isoproterenol, to the buffer sequence was then examined. The optimised rapid PD technique was then used to assess CFTR function produced by second and third generation LV-CFTR vectors. V5 epitope tagged-CFTR in nasal tissue was identified by immunohistochemistry. When intubated, mice tolerated higher flow rates. Isoproterenol could discriminate between WT and CF mice. Improved chloride transport was observed for the second and third generation LV-CFTR vectors, with up to 60% correction of the cAMP-driven chloride response towards WT. V5-CFTR was located in ciliated epithelial cells. The rapid PD technique enables improved functional assessment of the bioelectrical ion transport defect for both current and potential CF therapies.

PMID:34385926 | PMC:PMC8353152 | DOI:10.3389/fphar.2021.714452

Eur Respir J. 2021 Aug 12:2100746. doi: 10.1183/13993003.00746-2021. Online ahead of print.

ABSTRACT

BACKGROUND: Inhibition of the epithelial sodium channel (ENaC) in cystic fibrosis (CF) airways provides a mutation-agnostic approach that could improve mucociliary clearance in all CF patients. BI 1265162 is an ENaC inhibitor with demonstrated preclinical efficacy and safety already demonstrated in humans.

OBJECTIVE: We present results from BALANCE-CF™ 1, a Phase II, placebo-controlled, randomised, double-blind study of four dose levels of BI 1265162 versus placebo for 4 weeks on top of standard of care in adults and adolescents with CF.

RESULTS: Initially, 28 randomised subjects (n=14 each BI 1265162 200 µg BID, placebo BID) were assessed at an interim futility analysis. Compared with placebo, numerical changes of -0.8% (95%CI -6.6, 4.9) in ppFEV1 and +2.1 units (95%CI -2.4, 6.5) in LCI were observed in the active group, meeting a predefined stopping rule; accordingly, the study was terminated. Recruitment had continued during the interim analysis and pending results; 24 patients were added across three dose levels and placebo. The final results including these patients (+1.5% ppFEV1, 200 µg BID dose versus placebo) were not supportive of relevant clinical effect. LCI change was also not supportive, although interpretation was limited due to insufficient traces meeting quality criteria. A 9.4-point improvement in CFQ-R Respiratory Domain was observed in the 200 µg BID dose group versus placebo. BI 1265162 up to 200 µg BID was safe and well-tolerated. Pharmacokinetics were similar to those in healthy volunteers.

CONCLUSION: BI 1265162 was safe, but did not demonstrate a potential for clinical benefit. Development has been terminated.

PMID:34385272 | DOI:10.1183/13993003.00746-2021

BMJ Open Qual. 2021 Aug;10(3):e001199. doi: 10.1136/bmjoq-2020-001199.

ABSTRACT

BACKGROUND: For patients with cystic fibrosis (CF), sustaining lung function through the adolescent years is crucial to slow the progressive decline that leads to significant morbidity and early mortality. This holds true for patients with high per cent predicted forced expiratory volume in 1 s (ppFEV1), as they may receive less vigilant monitoring and treatment. Early identification of lung function decline followed by aggressive treatment can lead to preservation of lung function.

INTERVENTION: The Emory+Children's Pediatric Cystic Fibrosis Program implemented multiple quality improvement (QI) initiatives to identify and aggressively treat adolescent patients with a rapid decline in lung function. These initiatives included (1) lung zones to categorise and highlight lung function decline, (2) individual lung decline tables for quick reference, (3) a lung health algorithm to encourage uniformity, (4) a rapid decliner checklist to identify potential reasons for individual decline and (5) an automated individual patient-level data report and centre scorecard. We tested these interventions with plan-do-study-act cycles and refined as needed.

RESULTS: Implementation of these QI initiatives resulted in overall improvement in lung function and slowing of lung function decline among adolescents with CF . This improvement could be attributed to the more standardised and proactive approach to decreases in lung function and the increased clinician attention to patients with rapid decline, especially for patients with high baseline ppFEV1.

PMID:34385185 | DOI:10.1136/bmjoq-2020-001199

BMJ Open Respir Res. 2021 Aug;8(1):e000985. doi: 10.1136/bmjresp-2021-000985.

ABSTRACT

INTRODUCTION: Massive haemoptysis is a life-threatening event in advanced cystic fibrosis (CF) lung disease with bronchial artery embolisation (BAE) as standard of care treatment. The aim of our study was to scrutinise short-term and long-term outcomes of patients with CF and haemoptysis after BAE using coils.

METHODS: We carried out a retrospective cohort study of 34 adult patients treated for massive haemoptysis with super selective bronchial artery coil embolisation (ssBACE) between January 2008 and February 2015. Embolisation protocol was restricted to the culprit vessel(s) and three lobes maximum. Demographic data, functional end-expiratory volume in 1 s in % predicted (FEV1% pred.) and body mass index before and after ssBACE, sputum colonisation, procedural data, time to transplant and time to death were documented.

RESULTS: Patients treated with ssBACE showed significant improvement of FEV1% pred. after embolisation (p=0.004) with 72.8% alive 5 years post-ssBACE. Mean age of the patients was 29.9 years (±7.7). Mean FEV1% pred. was 45.7% (±20.1). Median survival to follow-up was 75 months (0-125). Severe complication rate was 0%, recanalisation rate 8.8% and 5-year-reintervention rate 58.8%. Chronic infection with Pseudomonas aeruginosa was found in 79.4%, Staphylococcus areus in 50% and Aspergillus fumigatus in 47.1%.

DISCUSSION: ssBACE is a safe and effective treatment for massive haemoptysis in patients with CF with good results for controlling haemostasis and excellent short-term and long-term survival, especially in severely affected patients with FEV<40% pred. We think the data of our study support the use of coils and a protocol of careful and prudent embolisation.

PMID:34385150 | DOI:10.1136/bmjresp-2021-000985

Eur J Med Chem. 2021 Aug 2;224:113736. doi: 10.1016/j.ejmech.2021.113736. Online ahead of print.

ABSTRACT

Pyrazolopyrimidinones are fused nitrogen-containing heterocyclic systems, which act as a core scaffold in many pharmaceutically relevant compounds. Pyrazolopyrimidinones have been demonstrated to be efficient in treating several diseases, including cystic fibrosis, obesity, viral infection and cancer. In this study using glioblastoma U-251MG cell line, we tested the cytotoxic effects of 15 pyrazolopyrimidinones, synthesised via a two-step process, in combination with cold atmospheric plasma (CAP). CAP is an adjustable source of reactive oxygen and nitrogen species as well as other unique chemical and physical effects which has been successfully tested as an innovative cancer therapy in clinical trials. Significantly variable cytotoxicity was observed with IC50 values ranging from around 11 μM to negligible toxicity among tested compounds. Interestingly, two pyrazolopyrimidinones were identified that act in a prodrug fashion and display around 5-15 times enhanced reactive-species dependent cytotoxicity when combined with cold atmospheric plasma. Activation was evident for direct CAP treatment on U-251MG cells loaded with the pyrazolopyrimidinone and indirect CAP treatment of the pyrazolopyrimidinone in media before adding to cells. Our results demonstrated the potential of CAP combined with pyrazolopyrimidinones as a programmable cytotoxic therapy and provide screened scaffolds that can be used for further development of pyrazolopyrimidinone prodrug derivatives.

PMID:34384944 | DOI:10.1016/j.ejmech.2021.113736

J Cyst Fibros. 2021 Aug 9:S1569-1993(21)01336-9. doi: 10.1016/j.jcf.2021.07.017. Online ahead of print.

NO ABSTRACT

PMID:34384711 | DOI:10.1016/j.jcf.2021.07.017

BMC Pulm Med. 2021 Aug 13;21(1):261. doi: 10.1186/s12890-021-01634-z.

ABSTRACT

BACKGROUND: While lung transplant (LTX) can be an effective therapy to provide the survival benefit in selected populations, post-transplant outcome in LTX recipients with bronchiectasis other than cystic fibrosis (CF) has been less studied. Pseudomonas aeruginosa, often associated with exacerbations in bronchiectasis, is the most common micro-organism isolated from LTX recipients. We aimed to see the outcomes of patients with bronchiectasis other than CF after LTX and seek the risk factors associated with pre- and post-transplant Pseudomonas status.

METHODS: Patients who underwent LTX at Tohoku University Hospital between January 2000 and December 2020 were consecutively included into the retrospective cohort study. Pre- and post-transplant prevalence of Pseudomonas colonization between bronchiectasis and other diseases was reviewed. Post-transplant outcomes (mortality and the development of chronic lung allograft dysfunction (CLAD)) were assessed using a Cox proportional hazards and time-to-event outcomes were estimated using the Kaplan-Meier method.

RESULTS: LTX recipients with bronchiectasis experienced a high rate of pre- and post-transplant Pseudomonas colonization compared to other diseases with statistical significance (p < 0.001 and p < 0.001, respectively). Nevertheless, long-term survival in bronchiectasis was as great as non-bronchiectasis (Log-rank p = 0.522), and the bronchiectasis was not a trigger for death (HR 1.62, 95% CI 0.63-4.19). On the other hand, the chance of CLAD onset in bronchiectasis was comparable to non-bronchiectasis (Log-rank p = 0.221), and bronchiectasis was not a predictor of the development of CLAD (HR 1.88, 95% CI 0.65-5.40).

CONCLUSIONS: Despite high prevalence of pre- and post-transplant Pseudomonas colonization, the outcome in LTX recipients with bronchiectasis other than CF was comparable to those without bronchiectasis.

PMID:34384425 | DOI:10.1186/s12890-021-01634-z

Future Microbiol. 2021 Aug 13. doi: 10.2217/fmb-2021-0150. Online ahead of print.

ABSTRACT

People with cystic fibrosis (CF) are highly susceptible to bacterial infections of the airways. By adulthood, chronic Pseudomonas aeruginosa (Pa) is the most prevalent infective organism and is difficult to eradicate owing to its adaptation to the CF lung microenvironment. Long-term suppressive treatment with inhaled antimicrobials is the standard care for reducing exacerbation frequency, improving quality of life and increasing measures of lung function. Levofloxacin (a fluoroquinolone antimicrobial) has been approved as an inhaled solution in Europe and Canada, for the treatment of adults with CF with chronic P. aeruginosa pulmonary infections. Here, we review the clinical principles relating to the use of inhaled antimicrobials and inhaled levofloxacin for the management of P. aeruginosa infections in patients with CF.

PMID:34384254 | DOI:10.2217/fmb-2021-0150

FASEB J. 2021 Sep;35(9):e21797. doi: 10.1096/fj.202100495R.

ABSTRACT

Pseudomonas aeruginosa is a frequent cause of hospital-acquired lung infections characterized by hyperinflammation, antibiotic resistance, and high morbidity/mortality. Here, we show that the genetic ablation of one cAMP-phosphodiesterase 4 subtype, PDE4B, is sufficient to protect mice from acute lung injury induced by P aeruginosa infection as it reduces pulmonary and systemic levels of pro-inflammatory cytokines, as well as pulmonary vascular leakage and mortality. Surprisingly, despite dampening immune responses, bacterial clearance in the lungs of PDE4B-KO mice is significantly improved compared to WT controls. In wildtypes, P aeruginosa-infection produces high systemic levels of several cytokines, including TNF-α, IL-1β, and IL-6, that act as cryogens and render the animals hypothermic. This, in turn, diminishes their ability to clear the bacteria. Ablation of PDE4B curbs both the initial production of acute response cytokines, including TNF-α and IL-1β, as well as their downstream signaling, specifically the induction of the secondary-response cytokine IL-6. This synergistic action protects PDE4B-KO mice from the deleterious effects of the P aeruginosa-induced cytostorm, while concurrently improving bacterial clearance, rather than being immunosuppressive. These benefits of PDE4B ablation are in contrast to the effects resulting from treatment with PAN-PDE4 inhibitors, which have been shown to increase bacterial burden and dissemination. Thus, PDE4B represents a promising therapeutic target in settings of P aeruginosa lung infections.

PMID:34383981 | DOI:10.1096/fj.202100495R

Clin Lab. 2021 Aug 1;67(8). doi: 10.7754/Clin.Lab.2021.210536.

ABSTRACT

BACKGROUND: Pseudomonas aeruginosa is a Gram-negative bacteria that causes a large range of human infections such as lung infection (cystic fibrosis) and urinary tract infection. Even worse, antibiotic resistant bacteria have become a serious health care problem throughout the last decade, and there is a need for a clear approach to regulate and prevent the spread of pseudomonas aeruginosa resistance.

METHODS: A complete analysis of Pseudomonas aeruginosa proteomics data showed that 25% of proteins are hypothetical proteins (HPs) whose function is not precisely defined. HP gene sequence analysis offers a framework for defining sequence-function relationships with a deeper understanding of organisms' molecular mechanisms at the system level. In the current research, we used the power of different bioinformatics tools to assign the potential roles for the HPs based on protein family association, amino acid function, motifs, and pathway analysis.

RESULTS: The current findings show that 30 HPs have well-defined functions and are classified as enzymes, DNA binding, periplasmic binding protein, transport, etc. Seven HPs showed virulence characteristics that is to be expected to be essential for Pseudomonas aeruginosa and pathogenesis survival.

CONCLUSIONS: This study's findings may encourage a better understanding of virulence mechanisms, drug resistance, pathogenesis, and drug discovery to treat Pseudomonas aeruginosa infections.

PMID:34383409 | DOI:10.7754/Clin.Lab.2021.210536

Autophagy. 2021 Aug 12:1-16. doi: 10.1080/15548627.2021.1956105. Online ahead of print.

ABSTRACT

Until recently, the ubiquitin-proteasome system (UPS) and macroautophagy/autophagy were considered to be two independent systems that target proteins for degradation by proteasomes or via lysosomes, respectively. Here, we report that TRIM44 (tripartite motif containing 44) is a novel link that connects the UPS system with the autophagy degradation pathway. Suppressing the UPS degradation pathway leads to TRIM44 upregulation, which further promotes aggregated protein clearance through the binding of K48 ubiquitin chains on proteins. TRIM44 expression activates autophagy via promoting SQSTM1/p62 oligomerization, which rapidly increases the rate of aggregate protein removal. Overall, our data reveal that TRIM44 is a newly identified link between the UPS system and the autophagy pathway. Delineating the cross-talk between these two degradation pathways may reveal new mechanisms of targeting aggregate-prone diseases, such as cancer and neurodegenerative disease.Abbreviations: 3-MA: 3-methyladenine; ACTB: actin beta; ATG5: autophagy related 5; BB: B-box domain; BECN1: beclin1; BM: bone marrow; CC: coiled-coil domain; CFTR: cystic fibrosis transmembrane conductance regulator; CON: control; CQ: chloroquine; DOX: doxycycline; DSP: dithiobis(succinimidly propionate); ER: endoplasmic reticulum; FI: fluorescence intensity; FL: full length; HIF1A/HIF-1#x3B1;: hypoxia inducible factor 1 subunit alpha; HSC: hematopoietic stem cells; HTT: huntingtin; KD: knockdown; KD-CON: knockdown construct control; MM: multiple myeloma; MTOR: mechanistic target of rapamycin kinase; NP-40: nonidet P-40; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; OE: overexpression; OE-CON: overexpression construct control; PARP: poly (ADP-ribose) polymerase; SDS: sodium dodecyl sulfate; SQSTM1/p62: sequestosome 1; Tet-on: tetracycline; TRIM44: tripartite motif containing 44; UPS: ubiquitin-proteasome system; ZF: zinc-finger.

PMID:34382902 | DOI:10.1080/15548627.2021.1956105

Physiol Rep. 2021 Aug;9(15):e14928. doi: 10.14814/phy2.14928.

ABSTRACT

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel whose dysfunction causes cystic fibrosis (CF). The loss of CFTR function in pulmonary epithelial cells causes surface dehydration, mucus build-up, inflammation, and bacterial infections that lead to lung failure. Little has been done to evaluate the effects of lipid perturbation on CFTR activity, despite CFTR residing in the plasma membrane. This work focuses on the acute effects of sphingomyelinase (SMase), a bacterial virulence factor secreted by CF relevant airway bacteria which degrades sphingomyelin into ceramide and phosphocholine, on the electrical circuitry of pulmonary epithelial monolayers. We report that basolateral SMase decreases CFTR-mediated transepithelial anion secretion in both primary bronchial and tracheal epithelial cells from explant tissue, with current CFTR modulators unable to rescue this effect. Focusing on primary cells, we took a holistic ion homeostasis approach to determine a cause for reduced anion secretion following SMase treatment. Using impedance analysis, we determined that basolateral SMase inhibits apical and basolateral conductance in non-CF primary cells without affecting paracellular permeability. In CF primary airway cells, correction with clinically relevant CFTR modulators did not prevent SMase-mediated inhibition of CFTR currents. Furthermore, SMase was found to inhibit only apical conductance in these cells. Future work should determine the mechanism for SMase-mediated inhibition of CFTR currents, and further explore the clinical relevance of SMase and sphingolipid imbalances.

PMID:34382377 | DOI:10.14814/phy2.14928