Cystic fibrosis

Management of distal intestinal obstruction syndrome by enteroscopy in a post-lung transplant patient

This is a case of a male patient who had a post-lung transplant complication given to distal intestinal obstruction by meconium. He was managed with laxative irrigation though enteroscope directly in the ileum with immediate resolution, without complications, avoiding surgical management. No similar cases have been reported.

Combined Liver-Lung-Kidney Transplant in a Patient with Cystic Fibrosis

BACKGROUND Individuals with cystic fibrosis (CF) constituted approximately 10% of organ transplants in 2019, with the majority of transplants consisting of bilateral lung transplant. Multiorgan transplantation in individuals with cystic fibrosis (CF) is rare, and usually involves the liver and lung combined. Since kidney disease is not a common sequela of CF, the need for renal transplant in individuals who have not previously undergone lung transplant is uncommon. CASE REPORT We report a case of successful liver-lung-kidney transplant in a 23-year-old man with CF-related liver and lung disease, who developed renal failure due to IgA nephropathy. He required renal replacement therapy during the months before transplantation. After discussions among the liver, lung, and renal transplant teams, the patient was listed for multiorgan transplantation. An appropriate single donor for all organs was identified, and the patient underwent transplantation. The patient required extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) perioperatively, with total operative time of 23 h and 1 min. Postoperative course was notable for hemothorax and medication-induced acute tubular necrosis, which resolved without the need for renal replacement therapy. Liver and lung graft function was normal at 6 months, and renal function was minimally reduced. CONCLUSIONS Triple organ transplantation in CF is a viable option for individuals with multiorgan failure who may otherwise not qualify for single/dual organ transplantation. Use of ECMO and CRRT can be necessary during the long operative procedure. Optimal immunosuppression protocols for this group of patients has not yet been established, and ethical concerns regarding multiorgan transplantation exist.

A quantitative super-resolution imaging toolbox for diagnosis of motile ciliopathies

Airway clearance of pathogens and particulates relies on motile cilia. Impaired cilia motility can lead to reduction in lung function, lung transplant, or death in some cases. More than 50 proteins regulating cilia motility are linked to primary ciliary dyskinesia (PCD), a heterogeneous, mainly recessive genetic lung disease. Accurate PCD molecular diagnosis is essential for identifying therapeutic targets and for initiating therapies that can stabilize lung function, thereby reducing socioeconomic impact of the disease. To date, PCD diagnosis has mainly relied on nonquantitative methods that have limited sensitivity or require a priori knowledge of the genes involved. Here, we developed a quantitative super-resolution microscopy workflow: (i) to increase sensitivity and throughput, (ii) to detect structural defects in PCD patients' cells, and (iii) to quantify motility defects caused by yet to be found PCD genes. Toward these goals, we built a localization map of PCD proteins by three-dimensional structured illumination microscopy and implemented quantitative image analysis and machine learning to detect protein mislocalization, we analyzed axonemal structure by stochastic optical reconstruction microscopy, and we developed a high-throughput method for detecting motile cilia uncoordination by rotational polarity. Together, our data show that super-resolution methods are powerful tools for improving diagnosis of motile ciliopathies.

Pulmonary Complications in Cystic Fibrosis: Past, Present, and Future

Cystic fibrosis (CF) is an autosomal recessive genetic condition with multisystemic disease manifestations, the most prominent of which occur in the respiratory system. Despite significant developments in disease understanding and therapeutics, each contributing to improved lung function and survival in patients with CF, several pulmonary complications, including pneumothorax, massive hemoptysis, and respiratory failure, continue to occur. In this review, we briefly describe each of these complications and their management and discuss how they impact the care and disease trajectory of individuals in whom they occur. Finally, we discuss the evolving role that palliative care and CF transmembrane conductance regular modulator therapies play in the natural disease course and care of patients with CF.

Rescue of multiple class II CFTR mutations by elexacaftor+tezacaftor+ivacaftor mediated in part by the dual activities of elexacaftor as both corrector and potentiator

Positive results in pre-clinical studies of the triple combination of elexacaftor, tezacaftor and ivacaftor, performed in airway epithelial cell cultures obtained from patients harbouring the class II cystic fibrosis transmembrane conductance regulator (CFTR) mutation F508del-CFTR, translated to impressive clinical outcomes for subjects carrying this mutation in clinical trials and approval of Trikafta.Encouraged by this correlation, we were prompted to evaluate the effect of the elexacaftor, tezacaftor and ivacaftor triple combination on primary nasal epithelial cultures obtained from individuals with rare class II CF-causing mutations (G85E, M1101K and N1303K) for which Trikafta is not approved.Cultures from individuals homozygous for M1101K responded better than cultures harbouring G85E and N1303K after treatment with the triple combination with respect to improvement in regulated channel function and protein processing. A similar genotype-specific effect of the triple combination was observed when the different mutations were expressed in HEK293 cells, supporting the hypothesis that these modulators may act directly on the mutant proteins. Detailed studies in nasal cultures and HEK293 cells showed that the corrector, elexacaftor, exhibited dual activity as both corrector and potentiator, and suggested that the potentiator activity contributes to its pharmacological activity.These pre-clinical studies using nasal epithelial cultures identified mutation genotypes for which elexacaftor, tezacaftor and ivacaftor may produce clinical responses that are comparable to, or inferior to, those observed for F508del-CFTR.

Ivacaftor partially corrects airway inflammation in a humanized G551D rat

Animal models have been highly informative for understanding the pathogenesis and progression of cystic fibrosis (CF) lung disease. In particular, the CF rat models recently developed have addressed mechanistic causes of the airway mucus defect characteristic of CF, and how these may change when cystic fibrosis transmembrane conductance regulator (CFTR) activity is restored using new modulator therapies. We hypothesized that inflammatory changes to the airway would develop spontaneously and progressively, and that these changes would be resolved with modulator therapy. To test this, we used a humanized-CFTR rat expressing the G551D variant that responds to the CFTR modulator ivacaftor. Markers typically found in the CF lung were assessed, including neutrophil influx, small airway histopathology, and inflammatory cytokine concentration. Young hG551D rats did not express inflammatory cytokines at baseline but did upregulate these in response to inflammatory trigger. As the hG551D rats aged, histopathology worsened, accompanied by neutrophil influx into the airway and increasing concentrations of TNF-α, IL-1α, and IL-6 in the airways. Ivacaftor administration reduced concentrations of these cytokines when administered to the rats at baseline but was less effective in the rats that had also received inflammatory stimulus. Therefore, we conclude that administration of ivacaftor resulted in an incomplete resolution of inflammation when rats received an external trigger, suggesting that CFTR activation may not be enough to resolve inflammation in the lungs of patients with CF.

Association of cystic fibrosis transmembrane conductance regulator with epithelial sodium channel subunits carrying Liddle's syndrome mutations

The association of the cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC) in the pathophysiology of cystic fibrosis (CF) is controversial. Previously, we demonstrated a close physical association between wild-type (WT) CFTR and WT ENaC. We have also shown that the F508del CFTR fails to associate with ENaC unless the mutant protein is rescued pharmacologically or by low temperature. In this study, we present the evidence for a direct physical association between WT CFTR and ENaC subunits carrying Liddle's syndrome mutations. We show that all three ENaC subunits bearing Liddle's syndrome mutations (both point mutations and the complete truncation of the carboxy terminus), could be coimmunoprecipitated with WT CFTR. The biochemical studies were complemented by fluorescence lifetime imaging microscopy (FLIM), a distance-dependent approach that monitors protein-protein interactions between fluorescently labeled molecules. Our measurements revealed significantly increased fluorescence resonance energy transfer between CFTR and all tested ENaC combinations as compared with controls (ECFP and EYFP cotransfected cells). Our findings are consistent with the notion that CFTR and ENaC are within reach of each other even in the setting of Liddle's syndrome mutations, suggestive of a direct intermolecular interaction between these two proteins.

Quantification of Phenotypic Variability of Lung Disease in Children with Cystic Fibrosis

Cystic fibrosis (CF) lung disease has the greatest impact on the morbidity and mortality of patients suffering from this autosomal-recessive multiorgan disorder. Although CF is a monogenic disorder, considerable phenotypic variability of lung disease is observed in patients with CF, even in those carrying the same mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene or CFTR mutations with comparable functional consequences. In most patients with CF, lung disease progresses from childhood to adulthood, but is already present in infants soon after birth. In addition to the CFTR genotype, the variability of early CF lung disease can be influenced by several factors, including modifier genes, age at diagnosis (following newborn screening vs. clinical symptoms) and environmental factors. The early onset of CF lung disease requires sensitive, noninvasive measures to detect and monitor changes in lung structure and function. In this context, we review recent progress with using multiple-breath washout (MBW) and lung magnetic resonance imaging (MRI) to detect and quantify CF lung disease from infancy to adulthood. Further, we discuss emerging data on the impact of variability of lung disease severity in the first years of life on long-term outcomes and the potential use of this information to improve personalized medicine for patients with CF.

Pancreas transplantation for cystic fibrosis: A frequently missed opportunity

Cystic fibrosis (CF) is an inherited autosomal recessive disorder. Despite optimized therapy, the majority of affected individuals ultimately die of respiratory failure. As patients with CF are living longer, extra-pulmonary manifestations may develop including pancreatic failure, which manifests as exocrine insufficiency, and CF-related diabetes (CFRD). Both of these can be managed through pancreas transplantation. Pancreas transplantation is usually performed in combination with another organ, most often with a kidney transplant for end-stage diabetic nephropathy. In the CF patient population, the two settings where inclusion of a pancreas transplant should be considered would be in combination with a lung transplant for CF pulmonary disease, or in combination with a liver for CF-related liver disease with cirrhosis. This report will discuss this topic in detail, including a review of the literature regarding combinations of lung/pancreas and liver/pancreas transplant.

Would it have happened without Christmas? Thoracic emphysema and allergic bronchopulmonary aspergillosis in a juvenile cystic fibrosis patient with the G551D mutation receiving ivacaftor

Potent CFTR modulators improve CF manifestations far beyond expectations, including reduction of risk of typical complications. This is the first report of a patient who developed life-threatening ABPA and emphysema after overwhelming improvement. https://bit.ly/2P96PTy.

Fungal Infection and Inflammation in Cystic Fibrosis

Fungi are frequently recovered from lower airway samples from people with cystic fibrosis (CF), yet the role of fungi in the progression of lung disease is debated. Recent studies suggest worsening clinical outcomes associated with airway fungal detection, although most studies to date are retrospective or observational. The presence of fungi can elicit a T helper cell type 2 (Th-2) mediated inflammatory reaction known as allergic bronchopulmonary aspergillosis (ABPA), particularly in those with a genetic atopic predisposition. In this review, we discuss the epidemiology of fungal infections in people with CF, risk factors associated with development of fungal infections, and microbiologic approaches for isolation and identification of fungi. We review the spectrum of fungal disease presentations, clinical outcomes after isolation of fungi from airway samples, and the importance of considering airway co-infections. Finally, we discuss the association between fungi and airway inflammation highlighting gaps in knowledge and future research questions that may further elucidate the role of fungus in lung disease progression.

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.

Towards Human Translation of Lentiviral Airway Gene Delivery for Cystic Fibrosis: A One-Month CFTR and Reporter Gene Study in Marmosets

Gene therapy continues to be a promising contender for the treatment of cystic fibrosis (CF) airway disease. We have previously demonstrated that airway conditioning with lysophosphatidylcholine (LPC) followed by delivery of a HIV-1-based lentiviral (LV) vector functionally corrects the CF transmembrane conductance regulator (CFTR) defect in the nasal airways of CF mice. In our earlier pilot study we showed that our technique can transduce marmoset lungs acutely; this study extends that work to examine gene expression in this nonhuman primate (NHP) 1 month after gene vector treatment. A mixture of three separate HIV-1 vesicular stomatitis virus G (VSV-G)-pseudotyped LV vectors containing the luciferase (Luc), LacZ, and hCFTR transgenes was delivered into the trachea through a miniature bronchoscope. We examined whether a single-dose delivery of LV vector after LPC conditioning could increase levels of transgene expression in the trachea and lungs compared with control (phosphate-buffered saline [PBS]) conditioning. At 1 month, bioluminescence was detected in vivo in the trachea of three of the six animals within the PBS control group, compared with five of the six LPC-treated animals. When examined ex vivo there was weak evidence that LPC improves tracheal Luc expression levels. In the lungs, bioluminescence was detected in vivo in four of the six PBS-treated animals, compared with five of the six LPC-treated animals; however, bioluminescence was present in all lungs when imaged ex vivo. LacZ expression was predominantly observed in the alveolar regions of the lung. hCFTR was detected by qPCR in the lungs of five animals. Basal cells were successfully isolated and expanded from marmoset tracheas, but no LacZ-positive colonies were detected. There was no evidence of an inflammatory response toward the LV vector at 1 month postdelivery, with cytokines remaining at baseline levels. In conclusion, we found weak evidence that LPC conditioning improved gene transduction in the trachea, but not in the marmoset lungs. We also highlight some of the challenges associated with translational lung gene therapy studies in NHPs.

Bone Cells Differentiation: How CFTR Mutations May Rule the Game of Stem Cells Commitment?

Cystic fibrosis (CF)-related bone disease has emerged as a significant comorbidity of CF and is characterized by decreased bone formation and increased bone resorption. Both osteoblast and osteoclast differentiations are impacted by cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The defect of CFTR chloride channel or the loss of CFTRs ability to interact with other proteins affect several signaling pathways involved in stem cell differentiation and the commitment of these cells toward bone lineages. Specifically, TGF-, nuclear factor-kappa B (NF-B), PI3K/AKT, and MAPK/ERK signaling are disturbed by CFTR mutations, thus perturbing stem cell differentiation. High inflammation in patients changes myeloid lineage secretion, affecting both myeloid and mesenchymal differentiation. In osteoblast, Wnt signaling is impacted, resulting in consequences for both bone formation and resorption. Finally, CFTR could also have a direct role in osteoclasts resorptive function. In this review, we summarize the existing literature on the role of CFTR mutations on the commitment of induced pluripotent stem cells to bone cells.

SPLUNC1: a novel marker of cystic fibrosis exacerbations

Acute pulmonary Exacerbations (AE) are episodes of clinical worsening in cystic fibrosis (CF), often precipitated by infection. Timely detection is critical to minimise morbidity and lung function declines associated with acute inflammation during AE. Based on our previous observations that airway protein Short Palate Lung Nasal epithelium Clone 1 (SPLUNC1) is regulated by inflammatory signals, we investigated the use of SPLUNC1 fluctuations to diagnose and predict AE in CF.We enrolled CF participants from two independent cohorts to measure AE markers of inflammation in sputum and recorded clinical outcomes for a 1-year follow-up period.SPLUNC1 levels were high in healthy controls (n=9, 10.7 μg mL^-1), and significantly decreased in CF participants without AE (n=30, 5.7 μg mL^-1, p=0.016). SPLUNC1 levels were 71.9% lower during AE (n=14, 1.6 μg mL^-1, p=0.0034) regardless of age, sex, CF-causing mutation, or microbiology findings. Cytokines Il-1β and TNFα were also increased in AE, whereas lung function did not consistently decrease. Stable CF participants with lower SPLUNC1 levels were much more likely to have an AE at 60 days (HR: 11.49, Standard Error: 0.83, p=0.0033). Low-SPLUNC1 stable participants remained at higher AE risk even one year after sputum collection (HR: 3.21, Standard Error: 0.47, p=0.0125). SPLUNC1 was downregulated by inflammatory cytokines and proteases increased in sputum during AE.In acute CF care, low SPLUNC1 levels could support a decision to increase airway clearance or to initiate pharmacological interventions. In asymptomatic, stable patients, low SPLUNC1 levels could inform changes in clinical management to improve long-term disease control and clinical outcomes in CF.

LPS decreases CFTR open probability and mucociliary transport through generation of reactive oxygen species

Lipopolysaccharide (LPS) serves as the interface between gram-negative bacteria (GNB) and the innate immune response in respiratory epithelial cells (REC). Herein, we describe a novel biological role of LPS that permits GNB to persist in the respiratory tract through inducing CFTR and mucociliary dysfunction. LPS reduced cystic fibrosis transmembrane conductance regulater (CFTR)-mediated short-circuit current in mammalian REC in Ussing chambers and nearly abrogated CFTR single channel activity (defined as forskolin-activated Cl^- currents) in patch clamp studies, effects of which were blocked with toll-like receptor (TLR)-4 inhibitor. Unitary conductance and single-channel amplitude of CFTR were unaffected, but open probability and number of active channels were markedly decreased. LPS increased cytoplasmic and mitochondrial reactive oxygen species resulting in CFTR carbonylation. All effects of exposure were eliminated when reduced glutathione was added in the medium along with LPS. Functional microanatomy parameters, including mucociliary transport, in human sinonasal epithelial cells in vitro were also decreased, but restored with co-incubation with glutathione or TLR-4 inhibitor. In vivo measurements, following application of LPS in the nasal cavities showed significant decreases in transepithelial Cl^- secretion as measured by nasal potential difference (NPD) – an effect that was nullified with glutathione and TLR-4 inhibitor. These data provide definitive evidence that LPS-generated reactive intermediates downregulate CFTR function in vitro and in vivo which results in cystic fibrosis-type disease. Findings have implications for therapeutic approaches intent on stimulating Cl^- secretion and/or reducing oxidative stress to decrease the sequelae of GNB airway colonization and infection.

Individual and Group Response of Treatment with Ivacaftor on Airway and Gut Microbiota in People with CF and a S1251N Mutation

Ivacaftor has been shown to restore the functionality of the S1251N (also known as c.3752G>A) mutated CFTR, which may cause alterations in both airway and gut physiology and micro-environment, resulting in a change of microbiota in these organs. The aim of the present study was to analyze the effects of ivacaftor on the microbial community composition of both airway and gut in subjects with CF carrying one S1251N mutation, using a 16S rRNA gene-based sequencing approach. In 16 subjects with CF, repetitive samples from airways and gut were collected just before, and 2 months after, and, for 8 patients, also 9 and 12 months after, start of ivacaftor. 16S rRNA based sequencing identified 344 operational taxonomical units (OTUs) in a total of 139 samples (35 nasopharyngeal, 39 oropharyngeal, 29 sputum, and 36 fecal samples). Ivacaftor significantly enhanced bacterial diversity and overall microbiota composition in the gut (p < 0.01). There were no significant changes in the overall microbial composition and alpha diversity in upper and lower airways of these patients after ivacaftor treatment. Treatment with ivacaftor induces changes in gut microbiota whereas airway microbiota do not change significantly over time.

Pseudomonas aeruginosa Virulence Factors Support Voriconazole Effects on Aspergillus fumigatus

Pseudomonas aeruginosa and Aspergillus fumigatus are pathogens that are associated with deterioration of lung function, e.g., in persons with cystic fibrosis (CF). There is evidence that co-infections with these pathogens cause airway inflammation and aggravate pathology in CF lungs. Intermicrobial competition of P. aeruginosa and A. fumigatus has been described, but it is unknown how anti-fungal therapy is affected. The anti-fungal azole voriconazole (VCZ), supernatants of P. aeruginosa laboratory isolates PA14 or PAO1, or clinical isolate Pa10 independently inhibited biofilm metabolism of A. fumigatus isolates 10AF and AF13073. When VCZ and supernatants were combined at their IC₅₀s, synergistic effects on A. fumigatus were found. Synergistic effects were no longer observed when P. aeruginosa supernatants were prepared in the presence of iron, or when P. aeruginosa mutants were lacking the ability to produce pyoverdine and pyochelin. Combination of pure P. aeruginosa products pyoverdine, pyochelin, and pyocyanin with VCZ showed synergistic anti-fungal effects. Combining VCZ with P. aeruginosa supernatants also improved its MIC and MFC against planktonic A. fumigatus. In summary, in the case of P. aeruginosa–A. fumigatus co-infections, it appeared that the P. aeruginosa co-infection facilitated therapy of the Aspergillus; lower concentrations of VCZ might be sufficient to control fungal growth.

Nasal Epithelial Cell-Based Models for Individualized Study in Cystic Fibrosis

The emergence of highly effective CFTR modulator therapy has led to significant improvements in health care for most patients with cystic fibrosis (CF). For some, however, these therapies remain inaccessible due to the rarity of their individual CFTR variants, or due to a lack of biologic activity of the available therapies for certain variants. One proposed method of addressing this gap is the use of primary human cell-based models, which allow preclinical therapeutic testing and physiologic assessment of relevant tissue at the individual level. Nasal cells represent one such tissue source and have emerged as a powerful model for individual disease study. The ex vivo culture of nasal cells has evolved over time, and modern nasal cell models are beginning to be utilized to predict patient outcomes. This review will discuss both historical and current state-of-the art use of nasal cells for study in CF, with a particular focus on the use of such models to inform personalized patient care.

Phenotyping Rare CFTR Mutations Reveal Functional Expression Defects Restored by TRIKAFTATM

The rare Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutations, c.1826A > G (H609R) and c.3067_3072delATAGTG (I1023_V1024del), are associated with severe lung disease. Despite the existence of four CFTR targeted therapies, none have been approved for individuals with these mutations because the associated molecular defects were not known. In this study we examined the consequences of these mutations on protein processing and channel function in HEK293 cells. We found that, similar to F508del, H609R and I1023_V1024del-CFTR exhibited reduced protein processing and altered channel function. Because the I1023_V1024del mutation can be linked with the mutation, I148T, we also examined the protein conferred by transfection of a plasmid bearing both mutations. Interestingly, together with I148T, there was no further reduction in channel function exhibited by I1023-V1024del. Both H609R and I1023_V1024del failed to exhibit significant correction of their functional expression with lumacaftor and ivacaftor. In contrast, the triple modulator combination found in TRIKAFTA^TM, i.e., tezacaftor, elexacaftor and ivacaftor rescued trafficking and function of both of these mutants. These in-vitro findings suggest that patients harbouring H609R or I1023_V1024del, alone or with I148T, may benefit clinically from treatment with TRIKAFTA^TM.

Cystic fibrosis in disguise - the wolf in sheep's clothing, a case report

Background

Childhood hypoglycemia in combination with hepatomegaly is suspicious for inborn errors of metabolism. Cystic fibrosis typically presents with failure to thrive, pulmonary and gastrointestinal symptoms. Hepatic involvement and hypoglycemia can occur in a significant number of patients, although hepatomegaly is uncommon.

Case presentation

A 28 months old boy was presented with recurrent upper airways infections, progressive lethargy and weight loss. Clinically hepatomegaly was the main presenting feature and hypoglycemia (minimum 1.4 mmol/l) was noted as were elevated transaminases. The patient did not produce enough sweat to analyze it. Infectious causes for hepatitis were excluded and a broad metabolic work-up initiated. A therapy with starch was initiated to control hypoglycemia. In further course loose stools were reported and pancreatic elastase was found to be reduced. A further sweat test yielded pathological chloride concentration and genetic testing confirmed the diagnosis of cystic fibrosis.

Conclusions

Cystic fibrosis is a systemic disease and less common presentations need to be considered. Even in the age of CF-newborn screening in many countries CF needs to be ruled out in typical and atypical clinical presentations and diagnostics need to be repeated if inconclusive.

Motor repertoire is age-inadequate in infants with cystic fibrosis

BACKGROUND

General movements (GMs) in infants occur as fidgety movements (FMs) between postterm 9 and 20 weeks. We aimed to evaluate FMs and motor repertoire in infants with cystic fibrosis (CF) and their relation with clinical findings.

METHODS

Demographic and clinical characteristics were recorded. FMs and motor repertoire were analyzed from a 5-min video recording of each infant. Videos were rated based on the Prechtl General Movement Assessment and motor optimality score (MOS) was calculated.

RESULTS

The analysis included 18 infants with CF and 20 healthy infants at postterm age of 3-5 months. MOS was significantly lower in the infants with CF compared to controls (p < 0.05). Fifty percent of the infants with CF had abnormal or absent/sporadic FMs. MOS was negatively associated with hospitalization duration (r = -0.378, p = 0.036); and positively associated with vitamin A level in CF infants (r = 0.665, p = 0.026).

CONCLUSIONS

Infants with genetically anticipated severe CF phenotype tended to have lower MOS. MOS may be used in addition to genetic testing to predict disease severity in infants with CF. Infants with CF, absent/sporadic FMs, and lower MOS could be considered for planning specific age-adequate early intervention programs.

IMPACT

Motor repertoire was age-inadequate in infants with cystic fibrosis (CF). 50% of infants with CF had abnormal or absent/sporadic fidgety movements (FMs). Motor optimality score (MOS) was positively associated with vitamin A level and negatively correlated with hospitalization duration in infants with CF. MOS tended to decrease as genetically anticipated disease severity increased; thus, MOS might enable us to predict disease severity in CF. The relationship between motor repertoire and phenotype and genotype is unclear and warrants further study. CF infants with absent/sporadic FMs, and lower MOS could be considered for planning early intervention.

Immunoglobulin G: A useful outcome marker in the follow-up of cystic fibrosis patients?

Background and Methods

Hypergammaglobulinemia (hyper‐IgG) and hypogammaglobulinemia (hypo‐IgG) have been reported in patients with cystic fibrosis (CF). Although the clinical respiratory course is paradoxically different, depending on the IgG status, this association remains elusive. Therefore, we performed a longitudinal study to assess the annual evolution of IgG profiles in a cohort of pediatric patients with CF, from their diagnosis until 2016. We then compared clinical findings with the patients’ IgG status to determine whether IgG status could reflect the respiratory clinical course of patients with CF.

Results

Among the 66 patients with CF that were aged between 12 months and 18 years in 2016 (mean age: 9.3 years [SD: 5.2]), hypo‐IgG was observed in 15.2% and no hyper‐IgG was identified. Longitudinal assessment since diagnosis revealed no hyper‐IgG but 33.3% of patients had at least one sample showing hypo‐IgG, among which two patients displayed persistent hypo‐IgG. The number of pulmonary exacerbations, duration of antibiotic therapy, and erythrocyte sedimentation rate were all lower in hypo‐IgG patients. No difference was observed for the genotype, chronic Pseudomonas aeruginosa or Staphylococcus aureus infection, and in the parameters of lung function.

Conclusion

The IgG profile of pediatric patients with CF has changed over recent decades, particularly with regard to hyper‐IgG. In a significant portion of the pediatric CF population, hypo‐IgG is transient and only identifiable in longitudinal assessments. This study reinforces that hypo‐IgG patients paradoxically present a more favorable course of clinical status. Therefore, IgG levels could be a useful outcome marker in the follow‐up of patients with CF.

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Abnormal immunoglobulin G (IgG) levels have been described in patients with cystic fibrosis (CF). With this longitudinal study, we sought to determine whether IgG status could reflect the respiratory clinical course of CF patients. The assessment in 2016 identified 15.2% of 66 pediatric patients as hypo‐IgG, whereas no hyper‐IgG was highlighted. The longitudinal assessment of IgG since diagnosis revealed no hyper‐IgG and hypo‐IgG was transient in at least one‐third of our patients, except for two, who both displayed persistent hypo‐IgG. Therefore, three populations can be identified, according to the patient's IgG profile during their follow‐up: a first with persistent hypo‐IgG since diagnosis; a second with a transient deficiency, which likely normalizes in adolescence; a third whose IgG remains within a normal range. CF patients with hypo‐IgG appear to be protected from pulmonary exacerbations and therefore could present a more favorable respiratory course, even with low IgG levels since diagnosis. This suggests that IgG levels could be a useful outcome marker in CF patient follow‐up in order to predict their respiratory clinical course.

Resolvin D1 and D2 reduce SARS-CoV-2-induced inflammatory responses in cystic fibrosis macrophages

An excessive, non‐resolving inflammatory response underlies severe COVID‐19 that may have fatal outcomes. Therefore, the investigation of endogenous pathways leading to resolution of inflammation is of interest to uncover strategies for mitigating inflammation in people with SARS‐CoV‐2 infection. This becomes particularly urgent in individuals with preexisting pathologies characterized by chronic respiratory inflammation and prone to bacterial infection, such as cystic fibrosis (CF). Here, we analyzed the immune responses to SARS‐CoV‐2 virion spike 1 glycoprotein (S1) of macrophages (MΦ) from volunteers with and without CF and tested the efficacy of resolvins (Rv) D1 and D2 in regulating the inflammatory and antimicrobial functions of MΦ exposed to S1. S1 significantly increased chemokine release, including interleukin (IL)‐8, in CF and non‐CF MΦ, while it enhanced IL‐6 and tumor necrosis factor (TNF)‐α in non‐CF MΦ, but not in CF cells. S1 also triggered the biosynthesis of RvD1 and modulated microRNAs miR‐16, miR‐29a, and miR‐103, known to control the inflammatory responses. RvD1 and RvD2 treatment abated S1‐induced inflammatory responses in CF and non‐CF MΦ, significantly reducing the release of select chemokines and cytokines including IL‐8 and TNF‐α. RvD1 and RvD2 both restored the expression of miR‐16 and miR‐29a, while selectively increasing miR‐223 and miR‐125a, which are involved in NF‐κB activation and MΦ inflammatory polarization. During Pseudomonas aeruginosa infection, S1 stimulated the MΦ phagocytic activity that was further enhanced by RvD1 and RvD2. These results provide a map of molecular responses to SARS‐CoV‐2 in MΦ, key determinants of COVID‐19‐related inflammation, unveiling some peculiarity in the response of cells from individuals with CF. They also demonstrate beneficial, regulatory actions of RvD1 and RvD2 on SARS‐CoV‐2‐induced inflammation.

The CFTR P67L variant reveals a key role for N-terminal lasso helices in channel folding, maturation, and pharmacologic rescue

Patients with cystic fibrosis (CF) harboring the P67L variant in the cystic fibrosis transmembrane conductance regulator (CFTR) often exhibit a typical CF phenotype, including severe respiratory compromise. This rare mutation (reported in <300 patients worldwide) responds robustly to CFTR correctors, such as lumacaftor and tezacaftor, with rescue in model systems that far exceed what can be achieved for the archetypical CFTR mutant F508del. However, the specific molecular consequences of the P67L mutation are poorly characterized. In this study, we conducted biochemical measurements following low-temperature growth and/or intragenic suppression, which suggest a mechanism underlying P67L that (1) shares key pathogenic features with F508del, including off-pathway (non-native) folding intermediates, (2) is linked to folding stability of nucleotide-binding domains 1 and 2, and (3) demonstrates pharmacologic rescue that requires domains in the carboxyl half of the protein. We also investigated the "lasso" helices 1 and 2, which occur immediately upstream of P67. Based on limited proteolysis, pulse chase, and molecular dynamics analysis of full-length CFTR and a series of deletion constructs, we argue that P67L and other maturational processing (class 2) defects impair the integrity of the lasso motif and confer misfolding of downstream domains. Thus, amino-terminal missense variants elicit a conformational change throughout CFTR that abrogates maturation while providing a robust substrate for pharmacologic repair.

Cystic Fibrosis-Related Diabetes (CFRD): Overview of Associated Genetic Factors

Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population and is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene that encodes for a chloride/bicarbonate channel expressed on the membrane of epithelial cells of the airways and of the intestine, as well as in cells with exocrine and endocrine functions. A common nonpulmonary complication of CF is cystic fibrosis-related diabetes (CFRD), a distinct form of diabetes due to insulin insufficiency or malfunction secondary to destruction/derangement of pancreatic betacells, as well as to other factors that affect their function. The prevalence of CFRD increases with age, and 40–50% of CF adults develop the disease. Several proposed hypotheses on how CFRD develops have emerged, including exocrine-driven fibrosis and destruction of the entire pancreas, as well as contrasting theories on the direct or indirect impact of CFTR mutation on islet function. Among contributors to the development of CFRD, in addition to CFTR genotype, there are other genetic factors related and not related to type 2 diabetes. This review presents an overview of the current understanding on genetic factors associated with glucose metabolism abnormalities in CF.

Treatment of Cystic Fibrosis: From Gene- to Cell-Based Therapies

Prognosis of patients with cystic fibrosis (CF) varies extensively despite recent advances in targeted therapies that improve CF transmembrane conductance regulator (CFTR) function. Despite being a multi-organ disease, extensive lung tissue destruction remains the major cause of morbidity and mortality. Progress towards a curative treatment strategy that implements a CFTR gene addition-technology to the patients’ lungs has been slow and not yet developed beyond clinical trials. Improved delivery vectors are needed to overcome the body’s defense system and ensure an efficient and consistent clinical response before gene therapy is suitable for clinical care. Cell-based therapy–which relies on functional modification of allogenic or autologous cells ex vivo, prior to transplantation into the patient–is now a therapeutic reality for various diseases. For CF, pioneering research has demonstrated proof-of-principle for allogenic transplantation of cultured human airway stem cells into mouse airways. However, applying a cell-based therapy to the human airways has distinct challenges. We review CF gene therapies using viral and non-viral delivery strategies and discuss current advances towards autologous cell-based therapies. Progress towards identification, correction, and expansion of a suitable regenerative cell, as well as refinement of pre-cell transplant lung conditioning protocols is discussed.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

Effect of endoscopic sinus surgery on clinical outcomes in DeltaF508 cystic fibrosis patients

OBJECTIVES

Chronic rhinosinusitis (CRS) is prevalent in the Cystic Fibrosis (CF) population. CRS exacerbations in CF are thought to contribute to pulmonary exacerbations. Literature regarding the impact of endoscopic sinus surgery (ESS) is inconclusive. This study examines rates of lung function decline and pulmonary exacerbation in CF patients who have undergone ESS.

DESIGN

Retrospective review of medical records.

SETTING

Academic Hospital.

PARTICIPANTS

40 adult CF patients.

MAIN OUTCOME MEASURES

Rate of lung function decline (% predicted Forced Expiratory Volume in 1 second [ppFEV₁ ]), number of pulmonary exacerbations (IV/oral antibiotic therapy ± hospital admission) and total number days hospitalised 2-year postoperatively was collected. CRS patients undergoing ESS were matched to those without ESS by gender, age, and F508del genotype.

RESULTS

Forty patients (mean age 37.4, 60% male) were reviewed. No significant difference was found between the surgical group and controls in baseline ppFEV₁ (72.5% vs. 72.7%, P = .98), 2-year preoperative number of pulmonary exacerbations (3.05 vs. 1.65, P = .10), or Lund-Mackay scores (12.25 vs. 11.55, P = .71). No significant difference was found in 1-year (70.5% vs. 72.8%, P = .84) or 2-year (70.4% vs. 72.6% P = .80) postoperative ppFEV₁ and 2-year postoperative pulmonary exacerbations (1.7 vs. 1.45, P = .87). A significant increase was identified in total number days hospitalised postoperatively (4.85, P = .02). In the surgical group, no significant difference was identified between preoperative and postoperative ppFEV₁ , 1 year (-2.51%, P = .32) and 2 years after ESS (-3.10%, P = .51), postoperative rate of pulmonary exacerbations (-1.28, P = .11), or in total number days hospitalised (3.74, P = .14).

CONCLUSIONS

In this study, ESS does not appear to significantly improve ppFEV₁ or decrease the number of pulmonary exacerbations postoperatively.

Educational Needs and Preferences for Patient-Centered Outcomes Research in the Cystic Fibrosis Community: Mixed Methods Study

BACKGROUND

Cystic fibrosis (CF) is a rare, life-shortening, multiorgan disease, the treatment of which has seen significant increases in the life expectancy of those with CF. Many advances in CF care are thanks to the dedicated and active participation of people with CF as research participants. Unfortunately, most CF research teams still do not fully partner with people with CF or their caregivers.

OBJECTIVE

The aim of this study was to determine the interest, knowledge gaps, and desired format for patient-centered outcomes research (PCOR) training in the CF community.

METHODS

We surveyed patients, caregivers, researchers, research staff, and diverse health care providers via list servers and social media outreach about their knowledge of, experience with, and preferences for PCOR training components. We followed the survey with 3 small-group discussion sessions with 22 participants who completed the survey to establish consensus and prioritize key learning components of a PCOR training program. We summarized results using descriptive statistics.

RESULTS

A total of 170 participants completed the survey (patients/caregivers: 96/170, 56.5%; researchers/health care providers: 74/170, 43.5%). Among providers, 26% (19/74) were physicians/advanced practice providers, 20% (15/74) were nurses, and 54% (40/74) were from other disciplines. Among all participants, 86.5% (147/170) expressed interest in learning about PCOR, although training topics and training format differed between the patient/caregiver and researcher/health care provider groups. Before participating in PCOR, patients/caregivers wanted to understand more about expectations of them as partners on PCOR research teams (82/96, 85%). Meanwhile, researchers/health care providers desired information on how to include outcomes important to patients/caregivers (55/74, 74%) and the quality and impact of PCOR research (52/74, 70% and 51/74, 69%, respectively). Patients/caregivers were most interested in learning about the time commitment as a PCOR team member (75/96, 78%). Researchers/health care providers wanted to receive training about how to establish trust (47/74, 64%) and maintain confidentiality (47/74, 64%) when including patient or caregiver partners on the PCOR team. During follow-up discussions, participants emphasized the importance of addressing the traditional patient/caregiver and researchers/health care provider hierarchy by teaching about transparency, appreciation, creating a common language between the groups, and providing specific training on "how" to do PCOR.

CONCLUSIONS

Our findings suggest CF community members are interested in PCOR. A high-quality training program would fill a current deficit in methodological research. This assessment identified the topics and formats desired and can be used to develop targeted training to enhance meaningful PCOR in CF.

Downregulation of epithelial sodium channel (ENaC) activity in human airway epithelia after low temperature incubation

Introduction

The incubation of airway epithelia cells at low temperatures is a common in vitro experimental approach used in the field of cystic fibrosis (CF) research to thermo-stabilise F508del-CFTR and increase its functional expression. Given that the airway epithelium includes numerous ion transporters other than CFTR, we hypothesised that there was an impact of low temperature incubation on CFTR-independent ionoregulatory mechanisms in airway epithelia derived from individuals with and without CF.

Methods

After differentiation at the air–liquid interface, nasal epithelia were incubated at either 37°C or 29°C (low temperature) for 48 hours prior to analysis in an Ussing chamber.

Results

While F508del-CFTR activity was increased after low temperature incubation, activity of CFTR in non-CF epithelia was unchanged. Importantly, cultures incubated at 29°C demonstrated decreased transepithelial potential difference (TEPD) and short-circuit currents (Isc) at baseline. The predominant factor contributing to the reduced baseline TEPD and Isc in 29°C cultures was the reduced activity of the epithelial sodium channel (ENaC), evidenced by a reduced responsiveness to amiloride. This effect was observed in cells derived from both non-CF and CF donors.

Discussion

Significant transcriptional downregulation of ENaC subunits β and γ were observed, which may partially explain the decreased ENaC activity. We speculate that low temperature incubation may be a useful experimental paradigm to reduce ENaC activity in in vitro epithelial cultures.

Development of elexacaftor - tezacaftor - ivacaftor: Highly effective CFTR modulation for the majority of people with Cystic Fibrosis

Introduction: Cystic fibrosis (CF), the most common life-shortening inherited disorder in people of European descent, also occurs in other ethnicities. The identification of the disease, the isolation of the causative gene, termed the cystic fibrosis transmembrane conductance regulator (CFTR) and the improved survival from comprehensive multidisciplinary treatment is one of the success stories of modern medicine. Survival has increased dramatically over the last 50 years, from 10 years in the 1960s to 30 years in the 1990s and approximately 50 years currently.Areas covered: This review will examine the development of highly effective modulators for CF which will revolutionize therapy for more than 90% of the people with CF. This review summarizes the development of triple combination CFTR modulator elexacaftor-tezacaftor-ivacaftor.Expert opinion: The development of this highly effective CFTR modulator for the majority of people with CF will likely change the landscape of CF care. The challenge is to now find highly effective therapy for the remaining 10% of the people with CF who may need other therapeutic agents to correct their primary defect.

Genes Regulating Spermatogenesis and Sperm Function Associated With Rare Disorders

Spermatogenesis is a cell differentiation process that ensures the production of fertilizing sperm, which ultimately fuse with an egg to form a zygote. Normal spermatogenesis relies on Sertoli cells, which preserve cell junctions while providing nutrients for mitosis and meiosis of male germ cells. Several genes regulate normal spermatogenesis, some of which are not exclusively expressed in the testis and control multiple physiological processes in an organism. Loss-of-function mutations in some of these genes result in spermatogenesis and sperm functionality defects, potentially leading to the insurgence of rare genetic disorders. To identify genetic intersections between spermatogenesis and rare diseases, we screened public archives of human genetic conditions available on the Genetic and Rare Diseases Information Center (GARD), the Online Mendelian Inheritance in Man (OMIM), and the Clinical Variant (ClinVar), and after an extensive literature search, we identified 22 distinct genes associated with 21 rare genetic conditions and defective spermatogenesis or sperm function. These protein-coding genes regulate Sertoli cell development and function during spermatogenesis, checkpoint signaling pathways at meiosis, cellular organization and shape definition during spermiogenesis, sperm motility, and capacitation at fertilization. A number of these genes regulate folliculogenesis and oogenesis as well. For each gene, we review the genotype–phenotype association together with associative or causative polymorphisms in humans, and provide a description of the shared molecular mechanisms that regulate gametogenesis and fertilization obtained in transgenic animal models.

Elexacaftor-tezacaftor-ivacaftor: The new paradigm to treat people with cystic fibrosis with at least one p.Phe508del mutation

Cystic fibrosis is the most common life-limiting genetic disease in the Caucasian population, with median predicted survival progressively improving up to 50 years, thanks to highly standardized multidisciplinary approach. Patients with p.Phe508del homozygosity usually have poorer lung function and higher mortality rates per year than other groups. By reason of that, this population has been among the most eligible target of the cystic fibrosis transmembrane conductance regulator (CFTR) modulators, a new class of drugs that can partially restore CFTR function by the correction of CFTR misfolding and trafficking to the cell surface. This narrative review summarizes the current preclinical and clinical evidence of the triple combination of elexacaftor-tezacaftor-ivacaftor, the new benchmark among highly effective CFTR modulators. It provides details on the efficacy and safety that led to drug regulation and approval and discusses future developments in clinical and translational research.

Measuring the impact of CFTR modulation on sweat chloride in cystic fibrosis: Rationale and design of the CHEC-SC study

BACKGROUND

The Characterizing CFTR Modulated Changes in Sweat Chloride and their Association with Clinical Outcomes (CHEC-SC) study is a large epidemiologic study designed to determine the relationship between sweat chloride response and clinical outcomes in people with cystic fibrosis (CF) on commercially approved CFTR modulators. A challenge to study feasibility was capturing sweat chloride measurements before modulator initiation. We tested the hypothesis that historic sweat chloride approximated contemporary pre-modulator values to estimate CFTR modulator-induced changes, allowing a single-visit study design.

METHODS

GOAL and PROSPECT were multi-center prospective studies of individuals initiating ivacaftor or lumacaftor-ivacaftor. At enrollment, pre-modulator sweat chloride was measured and historic results recorded. Post-modulator sweat chloride was measured at 1, 3 and 6 months. For this analysis, differences between historic and pre-modulator sweat chloride were estimated. CFTR modulator-induced sweat chloride mean changes were compared using historic and pre-modulator sweat chloride.

RESULTS

Paired historic and pre-modulator sweat chloride (n=406 participants) revealed a non-significant mean change of -1.0 mmol/L (95% CI: -2.71, 0.66) over an average of 17.2 years. Calculating sweat response to ivacaftor or lumacaftor-ivacaftor using historic or pre-modulator values resulted in similar estimates of modulator response. Based on these results, the CHEC-SC study was designed with a single, post-modulator sweat chloride measurement.

CONCLUSIONS

Historic sweat chloride values provide a reliable estimate of pre-modulator sweat chloride for people starting on modulator therapy. The CHEC-SC study anticipates capturing approximately 5,000 sweat chloride values, providing an unprecedented understanding of sweat chloride across the CF population in the era of CFTR modulators.

Urinary stone disease prevalence and associations in cystic fibrosis

Cystic fibrosis (CF) may predispose patients to urinary stone disease (USD), but reported prevalence of USD in patients with CF in previous small studies is variable. To date, analysis of risk factors for USD within the CF population has been limited. We studied 29,396 patients in the Cystic Fibrosis Foundation Patient Registry to calculate age and sex-stratified prevalence of USD. For adult patients, we examined age and multivariable-adjusted cross-sectional associations between demographic and clinical factors, CFTR mutation class, and prevalent USD. Prevalence of USD was 0.4% (95% CI 0.3-0.5%) under age 18 years, 3.1% (2.7-3.6%) at 18-24 years, 6.4% (5.8-7.1%) at 25-34 years, 7.5% (6.5-8.5%) at 35-44 years, and 6.7% (5.8-7.8%) at 45 years and older. Prevalence for women was higher than men at younger (< 45 years) but not older ages (P value for interaction < 0.0005). Multivariable odds of prevalent USD were significantly increased for severe CFTR mutations, OR 1.53 (1.14-2.06), diabetes, OR 1.24 (1.03-1.50), hypertension, OR 1.58 (1.29-1.93), and chronic macrolide therapy, OR 1.27 (1.07-1.52). BMI was not associated with USD. USD prevalence in CF is similar to that in the general population. With the exception of BMI, known risk factors for USD in the general population also appear to be important for patients with CF. We identified several novel associations in CF patients, including greater prevalence of USD in individuals with severe CFTR mutations and among young women.

Improvement of Pulmonary Function in Cystic Fibrosis Patients following Endoscopic Sinus Surgery

OBJECTIVE/HYPOTHESIS

To compare pre-and post-operative pulmonary function relative to disease severity in cystic fibrosis (CF) patients following endoscopic sinus surgery (ESS).

STUDY DESIGN

Retrospective chart review.

METHODS

Patients with CF who underwent ESS between January 1996 and July 2018 were identified, with subsequent study exclusions based upon surgical indications or incomplete records. CF disease severity was based upon percentage predicted of forced expiratory volume in 1 second (%FEV1) with <40% considered severe disease, 40% to 70% as moderate disease, and >70% as mild disease. The changes in %FEV1 before and after ESS were examined using multivariable mixed-effects models controlling for age, gender, genotype, medications, nutritional status, diabetes status, microbiology results, extent of surgery, and number of surgeries.

RESULTS

A total of 427 surgeries were performed in 188 patients during the study period. Mean age at first ESS was 12.7 years (SD 6.0 years, range 4-38) and 54.8% were females. The effect of ESS varied by severity of lung disease. After surgery, %FEV1 increased by 8.1% (95% CI: 2.3, 13.9%) among patients with severe lung disease and by 3.0% (95% CI: 0.7, 5.2%) among patients with moderate disease. %FEV1 also increased by 7.3% (95% CI: 4.2, 10.5%) among patients with mild disease whose %FEV1 value was 70% to 80% at baseline. No improvement was observed in patients with a baseline %FEV1 >80%.

CONCLUSIONS

When controlling for important confounding factors, lung function improved following ESS among CF patients with severe and moderate disease and in select patients with mild disease. This improvement was sustained at 12 months following surgery.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1930-1938, 2021.

RNA antitoxin SprF1 binds ribosomes to attenuate translation and promote persister cell formation in Staphylococcus aureus

Persister cells are a subpopulation of transiently antibiotic-tolerant bacteria associated with chronic infection and antibiotic treatment failure. Toxin-antitoxin systems have been linked to persister cell formation but the molecular mechanisms leading to bacterial persistence are mostly unknown. Here, we show that SprF1, a type I antitoxin, associates with translating ribosomes from the major human pathogen Staphylococcus aureus to reduce the pathogen's overall protein synthesis during growth. Under hyperosmotic stress, SprF1 levels increase due to enhanced stability, accumulate on polysomes and attenuate protein synthesis. Using an internal 6-nucleotide sequence on its 5'-end, SprF1 binds ribosomes and interferes with initiator transfer RNA binding, thus reducing translation initiation. An excess of messenger RNA displaces the ribosome-bound antitoxin, freeing the ribosomes for new translation cycles; however, this RNA antitoxin can also displace ribosome-bound mRNA. This translation attenuation mechanism, mediated by an RNA antitoxin, promotes antibiotic persister cell formation. The untranslated SprF1 is a dual-function RNA antitoxin that represses toxin expression by its 3'-end and fine-tunes overall bacterial translation via its 5'-end. These findings demonstrate a general function for a bacterial RNA antitoxin beyond protection from toxicity. They also highlight an RNA-guided molecular process that influences antibiotic persister cell formation.

Modulation of cAMP metabolism for CFTR potentiation in human airway epithelial cells

Cystic fibrosis (CF) is a genetic disease characterized by CF transmembrane regulator (CFTR) dysfunction. With over 2000 CFTR variants identified, in addition to known patient to patient variability, there is a need for personalized treatment. The discovery of CFTR modulators has shown efficacy in certain CF populations, however there are still CF populations without valid therapeutic options. With evidence suggesting that single drug therapeutics are insufficient for optimal management of CF disease, there has been an increased pursuit of combinatorial therapies. Our aim was to test cyclic AMP (cAMP) modulation, through ATP Binding Cassette Transporter C4 (ABCC4) and phosphodiesterase-4 (PDE-4) inhibition, as a potential add-on therapeutic to a clinically approved CFTR modulator, VX-770, as a method for increasing CFTR activity. Human airway epithelial cells (Calu-3) were used to test the efficacy of cAMP modulation by ABCC4 and PDE-4 inhibition through a series of concentration–response studies. Our results showed that cAMP modulation, in combination with VX-770, led to an increase in CFTR activity via an increase in sensitivity when compared to treatment of VX-770 alone. Our study suggests that cAMP modulation has potential to be pursued as an add-on therapy for the optimal management of CF disease.

SARS-CoV-2 may hijack GPCR signaling pathways to dysregulate lung ion and fluid transport

The tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a virus responsible for the ongoing coronavirus disease 2019 (COVID-19) pandemic, toward the host cells is determined, at least in part, by the expression and distribution of its cell surface receptor, angiotensin-converting enzyme 2 (ACE2). The virus further exploits the host cellular machinery to gain access into the cells; its spike protein is cleaved by a host cell surface transmembrane serine protease 2 (TMPRSS2) shortly after binding ACE2, followed by its proteolytic activation at a furin cleavage site. The virus primarily targets the epithelium of the respiratory tract, which is covered by a tightly regulated airway surface liquid (ASL) layer that serves as a primary defense mechanism against respiratory pathogens. The volume and viscosity of this fluid layer is regulated and maintained by a coordinated function of different transport pathways in the respiratory epithelium. We argue that SARS-CoV-2 may potentially alter evolutionary conserved second-messenger signaling cascades via activation of G protein-coupled receptors (GPCRs) or by directly modulating G protein signaling. Such signaling may in turn adversely modulate transepithelial transport processes, especially those involving cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial Na⁺ channel (ENaC), thereby shifting the delicate balance between anion secretion and sodium absorption, which controls homeostasis of this fluid layer. As a result, activation of the secretory pathways including CFTR-mediated Cl⁻ transport may overwhelm the absorptive pathways, such as ENaC-dependent Na⁺ uptake, and initiate a pathophysiological cascade leading to lung edema, one of the most serious and potentially deadly clinical manifestations of COVID-19.

Phenotypes of CF rabbits generated by CRISPR/Cas9-mediated disruption of the CFTR gene

Existing animal models of cystic fibrosis (CF) have provided key insights into CF pathogenesis but have been limited by short lifespans, absence of key phenotypes, and/or high maintenance costs. Here, we report the CRISPR/Cas9-mediated generation of CF rabbits, a model with a relatively long lifespan and affordable maintenance and care costs. CF rabbits supplemented solely with oral osmotic laxative had a median survival of approximately 40 days and died of gastrointestinal disease, but therapeutic regimens directed toward restoring gastrointestinal transit extended median survival to approximately 80 days. Surrogate markers of exocrine pancreas disorders were found in CF rabbits with declining health. CFTR expression patterns in WT rabbit airways mimicked humans, with widespread distribution in nasal respiratory and olfactory epithelia, as well as proximal and distal lower airways. CF rabbits exhibited human CF–like abnormalities in the bioelectric properties of the nasal and tracheal epithelia. No spontaneous respiratory disease was detected in young CF rabbits. However, abnormal phenotypes were observed in surviving 1-year-old CF rabbits as compared with WT littermates, and these were especially evident in the nasal respiratory and olfactory epithelium. The CF rabbit model may serve as a useful tool for understanding gut and lung CF pathogenesis and for the practical development of CF therapeutics.

Therapeutic guidelines for the treatment of cystic fibrosis

Cystic fibrosis (CF) is a complex, systemic autosomal recessive disease that affects the functions of the respiratory system, the digestive tract and all exocrine glands. The frequency for Europe averages 1: 2500 to 1: 3500 live births. The total number of patients with cystic fibrosis in Bulgaria is about 180. About 10% of the patients are diagnosed at birth. About 60–70% of patients are diagnosed before they reach one year of age. Respiratory symptoms predominate in the clinical picture in patients with cystic fibrosis and determine the prognosis in more than 90% of the patients. The treatment of patients with cystic fibrosis is strictly individualized, pharmacological and non-pharmacological and requires a comprehensive therapeutic approach. The complex therapy also includes bronchodilators, NSAIDs, corticosteroids, respiratory rehabilitation in combination with general body massage. Continued courses of broad-spectrum antibiotics are required to suppress chronic infection. With the progression of the disease, complications such as atelectasis, pneumothorax and pulmonary hemorrhages are observed. The establishment of specialized centers with trained and experienced professionals is essential in order to provide optimal patient care. These include frequent clinical evaluations, follow-up of complications, and early interventions for the treatment of patients with cystic fibrosis.

The aim of the article is to familiarize the audience with the therapeutic measures applied in the treatment of patients with cystic fibrosis.

Host genetic effects in pneumonia

Given the coronavirus disease 2019 (COVID-19) pandemic, investigations into host susceptibility to infectious diseases and downstream sequelae have never been more relevant. Pneumonia is a lung disease that can cause respiratory failure and hypoxia and is a common complication of infectious diseases, including COVID-19. Few genome-wide association studies (GWASs) of host susceptibility and severity of pneumonia have been conducted. We performed GWASs of pneumonia susceptibility and severity in the Vanderbilt University biobank (BioVU) with linked electronic health records (EHRs), including Illumina Expanded Multi-Ethnic Global Array (MEGAEX)-genotyped European ancestry (EA, n= 69,819) and African ancestry (AA, n = 15,603) individuals. Two regions of large effect were identified: the CFTR locus in EA (rs113827944; OR = 1.84, p value = 1.2 × 10-36) and HBB in AA (rs334 [p.Glu7Val]; OR = 1.63, p value = 3.5 × 10-13). Mutations in these genes cause cystic fibrosis (CF) and sickle cell disease (SCD), respectively. After removing individuals diagnosed with CF and SCD, we assessed heterozygosity effects at our lead variants. Further GWASs after removing individuals with CF uncovered an additional association in R3HCC1L (rs10786398; OR = 1.22, p value = 3.5 × 10-8), which was replicated in two independent datasets: UK Biobank (n = 459,741) and 7,985 non-overlapping BioVU subjects, who are genotyped on arrays other than MEGAEX. This variant was also validated in GWASs of COVID-19 hospitalization and lung function. Our results highlight the importance of the host genome in infectious disease susceptibility and severity and offer crucial insight into genetic effects that could potentially influence severity of COVID-19 sequelae.

The Potential Causes of Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity, affecting more than 50% of adult CF patients. Despite this high prevalence, the etiology of CFRD remains incompletely understood. Studies in young CF children show pancreatic islet disorganization, abnormal glucose tolerance, and delayed first-phase insulin secretion suggesting that islet dysfunction is an early feature of CF. Since insulin-producing pancreatic β-cells express very low levels of CFTR, CFRD likely results from β-cell extrinsic factors. In the vicinity of β-cells, CFTR is expressed in both the exocrine pancreas and the immune system. In the exocrine pancreas, CFTR mutations lead to the obstruction of the pancreatic ductal canal, inflammation, and immune cell infiltration, ultimately causing the destruction of the exocrine pancreas and remodeling of islets. Both inflammation and ductal cells have a direct effect on insulin secretion and could participate in CFRD development. CFTR mutations are also associated with inflammatory responses and excessive cytokine production by various immune cells, which infiltrate the pancreas and exert a negative impact on insulin secretion, causing dysregulation of glucose homeostasis in CF adults. In addition, the function of macrophages in shaping pancreatic islet development may be impaired by CFTR mutations, further contributing to the pancreatic islet structural defects as well as impaired first-phase insulin secretion observed in very young children. This review discusses the different factors that may contribute to CFRD.

Theoretical study of chloride complexes with hybrid macrocycles

Macrocycle receptors are investigated from DFT calculations to simultaneously recognize two Cl⁻ anions, which show several applications in the environment.

Long-Term Outcomes in Real Life of Lumacaftor-Ivacaftor Treatment in Adolescents With Cystic Fibrosis

Background: The combination of the CFTR corrector lumacaftor (LUM) and potentiator ivacaftor (IVA) has been labeled in France since 2015 for F508del homozygote cystic fibrosis (CF) patients over 12 years. In this real-life study, we aimed (i) to compare the changes in lung function, clinical (e.g., body mass index and pulmonary exacerbations) and radiological parameters, and in sweat chloride concentration before and after initiation of LUM/IVA treatment; (ii) to identify factors associated with response to treatment; and (iii) to assess the tolerance to treatment. Materials and Methods: In this tri-center, non-interventional, and observational cohort study, children (12-18 years old) were assessed prospectively during the 2 years of therapy, and retrospectively during the 2 years preceding treatment. Data collected and analyzed for the study were exclusively extracted from the medical electronic system records of the patients. Results: Forty adolescents aged 12.0-17.4 years at LUM/IVA initiation were included. The lung function decreased significantly during and prior to treatment and increased after LUM/IVA initiation, becoming significant after 2 years of treatment. LUM/IVA significantly improved the BMI Z-score and sweat chloride concentration. By contrast, there was no significant change in exacerbation rates, antibiotic use, or CT scan scores. Age at LUM/IVA initiation was lower in good responders and associated with greater ppFEV1 change during the 2 years of treatment. LUM/IVA was well-tolerated. Conclusion: In F508del homozygote adolescents, real-life long-term LUM/IVA improved the ppFEV1 trajectory, particularly in the youngest patients, nutritional status, and sweat chloride concentration but not exacerbation rates or radiological scores. LUM/IVA was generally well-tolerated and safe.

Multifunctional Delivery Systems for Peptide Nucleic Acids

The number of applications of peptide nucleic acids (PNAs)-oligonucleotide analogs with a polyamide backbone-is continuously increasing in both in vitro and cellular systems and, parallel to this, delivery systems able to bring PNAs to their targets have been developed. This review is intended to give to the readers an overview on the available carriers for these oligonucleotide mimics, with a particular emphasis on newly developed multi-component- and multifunctional vehicles which boosted PNA research in recent years. The following approaches will be discussed: (a) conjugation with carrier molecules and peptides; (b) liposome formulations; (c) polymer nanoparticles; (d) inorganic porous nanoparticles; (e) carbon based nanocarriers; and (f) self-assembled and supramolecular systems. New therapeutic strategies enabled by the combination of PNA and proper delivery systems are discussed.

Cyclic Peptidyl Inhibitors against CAL/CFTR Interaction for Treatment of Cystic Fibrosis

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, encoding for a chloride ion channel. Membrane expression of CFTR is negatively regulated by CFTR-associated ligand (CAL). We previously showed that inhibition of the CFTR/CAL interaction with a cell-permeable peptide improves the function of rescued F508del-CFTR. In this study, optimization of the peptidyl inhibitor yielded PGD97, which exhibits a K_D value of 6 nM for the CAL PDZ domain, ≥ 130-fold selectivity over closely related PDZ domains, and a serum t_1/2 of >24 h. In patient-derived F508del homozygous cells, PGD97 (100 nM) increased short-circuit currents by ∼3-fold and further potentiated the therapeutic effects of small-molecule correctors (e.g., VX-661) by ∼2-fold (with an EC₅₀ of ∼10 nM). Our results suggest that PGD97 may be used as a novel treatment for CF, either as a single agent or in combination with small-molecule correctors/potentiators.

ELISA Test for the Serological Detection of Scedosporium/Lomentospora in Cystic Fibrosis Patients

The detection and diagnosis of the opportunistic fungi Scedosporium spp. and Lomentospora prolificans still relies mainly on low-sensitive culture-based methods. This fact is especially worrying in Cystic Fibrosis (CF) patients in whom these fungal species are frequently isolated and may increase the risk of suffering from an infection or other health problems. Therefore, with the purpose of developing a serologic detection method for Scedosporium/Lomentospora, four different Scedosporium boydii protein extracts (whole cell protein extract, secretome, total cell surface and conidial surface associated proteins) were studied by ELISA to select the most useful for IgG detection in sera from CF patients. The four extracts were able to discriminate the Scedosporium/Lomentospora-infected from Aspergillus-infected and non-infected patients. However, the whole cell protein extract was the one selected, as it was the one with the highest output in terms of protein concentration per ml of fungal culture used, and its discriminatory capacity was the best. The ELISA test developed was then assayed with 212 sera from CF patients and it showed to be able to detect Scedosporium spp. and Lomentospora prolificans with very high sensitivity and specificity, 86%–100% and 93%–99%, respectively, depending on the cut-off value chosen (four values were proposed A_450nm= 0.5837, A_450nm= 0.6042, A_450nm= 0.6404, and A_450nm= 0.7099). Thus, although more research is needed to reach a standardized method, this ELISA platform offers a rapid, low-cost and easy solution to detect these elusive fungi through minimally invasive sampling, allowing the monitoring of the humoral response to fungal presence.