J Hist Med Allied Sci. 2022 Jan 10:jrab056. doi: 10.1093/jhmas/jrab056. Online ahead of print.

ABSTRACT

The framing of cystic fibrosis (CF) changed from a strictly genetic disease in the mid- to late-twentieth century to a genetic/infectious hybrid of sorts by the early twenty-first century, providing an opportunity to examine the nature of disease definition in medicine. Respiratory infections had long been associated with CF, yet it was not until the late twentieth century that many physicians became concerned about the possibility of patient-to-patient transmission of a particularly pathogenic microorganism. Initially termed Pseudomonas cepacia, the microbe was linked to rapid decline and even death in some people with CF, and early efforts to prevent its spread included the segregation of infected individuals. However, soon after segregation was implemented in a range of medical and social contexts, physicians began to suspect that people with CF did not always test positive for P. cepacia in the setting of infection, due to challenges isolating and identifying the microorganism in the laboratory. These sources of diagnostic uncertainty, coupled with the severe health outcomes associated with P. cepacia infection, prompted those in leadership positions to treat all people with CF as a potential source of contagion and restrict their in-person interactions, a practice that has had a profound impact on the CF community.

PMID:35020899 | DOI:10.1093/jhmas/jrab056

Anesth Analg. 2022 Jan 12. doi: 10.1213/ANE.0000000000005856. Online ahead of print.

ABSTRACT

Cystic fibrosis (CF) is the most common fatal genetic disease in North America. While CF is more common among Whites, it is increasingly being recognized in other races and ethnicities. Although there is no cure, life expectancy has steadily improved, with the median survival exceeding 46 years in the United States. There are now more adults than children with CF in the United States. CF is caused by mutations in a gene that encodes the cystic fibrosis transmembrane conductance regulator (CFTR) protein, expressed in many epithelial cells. More than 2100 CFTR mutations have been linked to CF, and newer CFTR modulator drugs are being used to improve the production, intracellular processing, and function of the defective CFTR protein. CF is a multisystem disease that affects primarily the lungs, pancreas, hepatobiliary system, and reproductive organs. Anesthesiologists routinely encounter CF patients for various surgical and medical procedures, depending on the age group. This review article focuses on the changing epidemiology of CF, advances in the classification of CFTR mutations, the latest innovations in CFTR modulator therapies, the impact of the coronavirus disease pandemic, and perioperative considerations that anesthesiologists must know while caring for patients with CF.

PMID:35020677 | DOI:10.1213/ANE.0000000000005856

Am J Physiol Lung Cell Mol Physiol. 2022 Jan 12. doi: 10.1152/ajplung.00397.2021. Online ahead of print.

ABSTRACT

There is an urgent need to understand how SARS-CoV-2 infects the airway epithelium and in a subset of individuals leads to severe illness or death. Induced pluripotent stem cells (iPSCs) provide a near limitless supply of human cells that can be differentiated into cell types of interest, including airway epithelium, for disease modeling. We present a human iPSC-derived airway epithelial platform, composed of the major airway epithelial cell types, that is permissive to SARS-CoV-2 infection. Subsets of iPSC-airway cells express the SARS-CoV-2 entry factors ACE2 and TMPRSS2. Multiciliated cells are the primary initial target of SARS-CoV-2 infection. Upon infection with SARS-CoV-2, iPSC-airway cells generate robust interferon and inflammatory responses and treatment with remdesivir or camostat methylate causes a decrease in viral propagation and entry, respectively. In conclusion, iPSC-derived airway cells provide a physiologically relevant in vitro model system to interrogate the pathogenesis of, and develop treatment strategies for, COVID-19 pneumonia.

PMID:35020534 | DOI:10.1152/ajplung.00397.2021

Am J Physiol Lung Cell Mol Physiol. 2022 Jan 12. doi: 10.1152/ajplung.00388.2021. Online ahead of print.

ABSTRACT

Cystic fibrosis (CF) is a genetic disease caused by mutations of the gene encoding a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR modulator therapies consist of small-molecule drugs that rescue mutant CFTR. Regimens of single or combinations of CFTR modulators still rely on endogenous levels of cAMP to regulate CFTR activity. We investigated CFTR activation by the natural mediator prostaglandin E2 (PGE2) and lubiprostone and tested the hypothesis that receptor-mediated CFTR activators can be used in combination with currently available CFTR modulators to increase function of mutant CFTR. Primary cultured airway epithelia were assayed in Ussing chambers. Experimental CFTR activators and established CFTR modulators were applied for 24 h and/or acutely and analyzed for their effect on CFTR activity as measured by changes in short-circuit current (ISC). In non-CF airway epithelia, acute application of lubiprostone and PGE2 activated CFTR to levels comparable to forskolin. Pre-treatment (24 h) with antagonists to prostaglandin receptors EP2 and EP4 abolished the ability of lubiprostone to acutely activate CFTR. In F508del homozygous airway epithelia pre-treated with the triple combination of elexacaftor, tezacaftor, and ivacaftor (ELEXA/TEZ/IVA; i.e., Trikafta), acute application of lubiprostone was able to maximally activate CFTR. Prolonged (24 h) co-treatment of F508del homozygous epithelia with ELEXA/TEZ/IVA and lubiprostone increased acute CFTR activation by ~60% compared to treatment with ELEXA/TEZ/IVA alone. This work establishes the feasibility of targeting prostaglandin receptors to activate CFTR on the airway epithelia and demonstrates that co-treatment with lubiprostone can further restore modulator-rescued CFTR.

PMID:35020527 | DOI:10.1152/ajplung.00388.2021

Diabetes Technol Ther. 2022 Jan 12. doi: 10.1089/dia.2021.0354. Online ahead of print.

ABSTRACT

Background Cystic fibrosis related diabetes (CFRD) is associated with pulmonary decline, compromised nutritional status and earlier mortality. While diabetes technology is increasingly being used in individuals with CFRD, there is a paucity of data investigating the impact of hybrid-closed loop (HCL) technology on glycemia in this patient population. Materials & Methods In this multicenter retrospective study of 13 adults and adolescents with CFRD, 14 days of continuous glucose monitoring (CGM) data were analyzed at baseline, 1-month and 3-months after transition to the Tandem t:slim X2 pump with Control IQ™ technology, a HCL system. Results Control IQ™ initiation was associated with a significant increase in % time in target range (70-180 mg/dL), as well as decreases in average glucose (AG), % time in hyperglycemic ranges (% time >180 mg/dL, % time >250 mg/dL), and glycemic variability (standard deviation [SD], coefficient of variation [CV]). There was no significant change in % time in hypoglycemia ranges (% time <54 mg/dL, % time <70 mg/dL). Conclusions To our knowledge, this is the first study to report a beneficial effect of FDA-approved HCL technology on glycemia in adults and adolescents with CFRD to date. Future studies are needed to understand the potential long-term glycemic benefits of HCL devices and to explore the impact of this technology on heath-related quality of life (HRQoL), pulmonary function, nutritional status, and mortality.

PMID:35020476 | DOI:10.1089/dia.2021.0354

Appl Environ Microbiol. 2022 Jan 12:aem0232221. doi: 10.1128/aem.02322-21. Online ahead of print.

ABSTRACT

The opportunistic pathogen Pseudomonas aeruginosa, is ubiquitous in the environment, and in humans is capable of causing acute or chronic infections. In the natural environment, predation by bacterivorous protozoa represents a primary threat to bacteria. Here, we determined the impact of long-term exposure of P. aeruginosa to predation pressure. P. aeruginosa persisted when co-incubated with the bacterivorous Acanthamoeba castellanii for extended periods and produced genetic and phenotypic variants. Sequencing of late-stage amoeba-adapted P. aeruginosa isolates demonstrated single nucleotide polymorphisms within genes that encode known virulence factors and this correlated with a reduction in expression of virulence traits. Virulence towards the nematode, Caenorhabditis elegans, was attenuated in late-stage amoeba-adapted P. aeruginosa compared to early-stage amoeba-adapted and non-adapted counterparts. Further, late-stage amoeba-adapted P. aeruginosa showed increased competitive fitness and enhanced survival in amoeba as well as in macrophage and neutrophils. Interestingly, our findings indicate that the selection imposed by amoeba resulted in P. aeruginosa isolates with reduced virulence and enhanced fitness, similar to those recovered from chronic cystic fibrosis infections. Thus, predation by protozoa and long-term colonization of the human host may represent similar environments that select for similar losses of gene function. Importance Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans, and chronic infections in immunocompromised and cystic fibrosis patients. This bacterium is commonly found in soils and water where bacteria are constantly under threat of being consumed by bacterial predators, e.g. protozoa. To escape being killed, bacteria have evolved a suite of mechanisms that protect them from being consumed or digested. Here, we examine the effect of long-term predation on the genotypes and phenotypes expressed by P. aeruginosa. We show that long term co-incubation with protozoa resulted in mutations that resulted in P. aeruginosa becoming less pathogenic. This is particularly interesting as we see similar mutations arise in bacteria associated with chronic infections. Importantly, the genetic and phenotypic traits possessed by late-stage amoeba-adapted P. aeruginosa are similar to what is observed for isolates obtained from chronic cystic fibrosis infections. This notable overlap in adaptation to different host types suggests similar selection pressures amongst host cell types as well as similar adaptation strategies.

PMID:35020451 | DOI:10.1128/aem.02322-21

Pediatr Pulmonol. 2022 Jan 11. doi: 10.1002/ppul.25825. Online ahead of print.

ABSTRACT

BACKGROUND: The variable response to fat-soluble vitamin supplementation in young children with CF, and factors contributing to this variability, remain under-investigated.

OBJECTIVE: To determine if recommended supplement doses normalize serum vitamin A (retinol), D (25-hydroxy-vitamin D, 25OHD) and E (α-tocopherol), and identify factors predictive of achieving sufficiency, in children with CF in the first 3 years of life.

DESIGN: We studied 144 infants born during 2012-2017 and diagnosed with CF through newborn screening. Serum retinol, 25OHD, α-tocopherol and plasma cytokines interleukin(IL)-6, IL-8, IL10 and tumor necrosis factor (TNF)-α were measured in early infancy and yearly thereafter. Vitamin supplement intakes and respiratory microbiology were assessed every 1-2 months in infancy and quarterly thereafter.

RESULTS: The prevalence of vitamin D insufficiency (<30 ng/mL) at all ages combined was significantly higher (22%) compared to vitamin A (<200 ng/mL, 3%) and vitamin E (<5 µg/mL, 5%). All children were vitamin A sufficient by age 2 years. Vitamin E insufficiency was rare. Only 42% were early responders of vitamin D and 17% remain insufficient despite high supplement intakes. IL-6 was positively correlated, while IL-8, IL-10 and TNF-α were negatively correlated, with retinol and 25OHD. Multiple regression analysis revealed that supplement dose, season, α-tocopherol, pancreatic insufficiency, respiratory infections and IL-10 were significant predictors of 25OHD.

CONCLUSION: Diagnosis through newborn screening coupled with supplementation normalized serum retinol and α -tocopherol in almost all infants with CF by age 3 years. However, response to vitamin D supplements in young children with CF occurred later and variably despite early and sustained supplementation. This article is protected by copyright. All rights reserved.

PMID:35018747 | DOI:10.1002/ppul.25825

Thorax. 2022 Jan 11:thoraxjnl-2021-217576. doi: 10.1136/thoraxjnl-2021-217576. Online ahead of print.

ABSTRACT

BACKGROUND: A basic paradigm of human infection is that acute bacterial disease is caused by fast growing planktonic bacteria while chronic infections are caused by slow-growing, aggregated bacteria, a phenomenon known as a biofilm. For lung infections, this paradigm has been thought to be supported by observations of how bacteria proliferate in well-established growth media in the laboratory-the gold standard of microbiology.

OBJECTIVE: To investigate the bacterial architecture in sputum from patients with acute and chronic lung infections.

METHODS: Advanced imaging technology was used for quantification and direct comparison of infection types on fresh sputum samples, thereby directly testing the acute versus chronic paradigm.

RESULTS: In this study, we compared the bacterial lifestyle (planktonic or biofilm), growth rate and inflammatory response of bacteria in freshly collected sputum (n=43) from patient groups presenting with acute or chronic lung infections. We found that both acute and chronic lung infections are dominated by biofilms (aggregates of bacteria within an extracellular matrix), although planktonic cells were observed in both sample types. Bacteria grew faster in sputum from acute infections, but these fast-growing bacteria were enriched in biofilms similar to the architecture thought to be reserved for chronic infections. Cellular inflammation in the lungs was also similar across patient groups, but systemic inflammatory markers were only elevated in acute infections.

CONCLUSIONS: Our findings indicate that the current paradigm of equating planktonic with acute and biofilm with chronic infection needs to be revisited as the difference lies primarily in metabolic rates, not bacterial architecture.

PMID:35017313 | DOI:10.1136/thoraxjnl-2021-217576

Proc Natl Acad Sci U S A. 2022 Jan 18;119(3):e2114886119. doi: 10.1073/pnas.2114886119.

ABSTRACT

CFTR gene mutations that result in the introduction of premature termination codons (PTCs) are common in cystic fibrosis (CF). This mutation type causes a severe form of the disease, likely because of low CFTR messenger RNA (mRNA) expression as a result of nonsense-mediated mRNA decay, as well as the production of a nonfunctional, truncated CFTR protein. Current therapeutics for CF, which target residual protein function, are less effective in patients with these types of mutations due in part to low CFTR protein levels. Splice-switching antisense oligonucleotides (ASOs), designed to induce skipping of exons in order to restore the mRNA open reading frame, have shown therapeutic promise preclinically and clinically for a number of diseases. We hypothesized that ASO-mediated skipping of CFTR exon 23 would recover CFTR activity associated with terminating mutations in the exon, including CFTR p.W1282X, the fifth most common mutation in CF. Here, we show that CFTR lacking the amino acids encoding exon 23 is partially functional and responsive to corrector and modulator drugs currently in clinical use. ASO-induced exon 23 skipping rescued CFTR expression and chloride current in primary human bronchial epithelial cells isolated from a homozygote CFTR-W1282X patient. These results support the use of ASOs in treating CF patients with CFTR class I mutations in exon 23 that result in unstable CFTR mRNA and truncations of the CFTR protein.

PMID:35017302 | DOI:10.1073/pnas.2114886119

Proc Natl Acad Sci U S A. 2022 Jan 18;119(3):e2114858118. doi: 10.1073/pnas.2114858118.

ABSTRACT

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), and the CFTR-W1282X nonsense mutation causes a severe form of CF. Although Trikafta and other CFTR-modulation therapies benefit most CF patients, targeted therapy for patients with the W1282X mutation is lacking. The CFTR-W1282X protein has residual activity but is expressed at a very low level due to nonsense-mediated messenger RNA (mRNA) decay (NMD). NMD-suppression therapy and read-through therapy are actively being researched for CFTR nonsense mutants. NMD suppression could increase the mutant CFTR mRNA, and read-through therapies may increase the levels of full-length CFTR protein. However, these approaches have limitations and potential side effects: because the NMD machinery also regulates the expression of many normal mRNAs, broad inhibition of the pathway is not desirable, and read-through drugs are inefficient partly because the mutant mRNA template is subject to NMD. To bypass these issues, we pursued an exon-skipping antisense oligonucleotide (ASO) strategy to achieve gene-specific NMD evasion. A cocktail of two splice-site-targeting ASOs induced the expression of CFTR mRNA without the premature-termination-codon-containing exon 23 (CFTR-Δex23), which is an in-frame exon. Treatment of human bronchial epithelial cells with this cocktail of ASOs that target the splice sites flanking exon 23 results in efficient skipping of exon 23 and an increase in CFTR-Δex23 protein. The splice-switching ASO cocktail increases the CFTR-mediated chloride current in human bronchial epithelial cells. Our results set the stage for developing an allele-specific therapy for CF caused by the W1282X mutation.

PMID:35017301 | DOI:10.1073/pnas.2114858118

Blood Adv. 2022 Jan 11:bloodadvances.2021006527. doi: 10.1182/bloodadvances.2021006527. Online ahead of print.

NO ABSTRACT

PMID:35015811 | DOI:10.1182/bloodadvances.2021006527

JAMA. 2022 Jan 11;327(2):191. doi: 10.1001/jama.2021.23280.

NO ABSTRACT

PMID:35015036 | DOI:10.1001/jama.2021.23280

J Med Microbiol. 2022 Jan;71(1). doi: 10.1099/jmm.0.001467.

ABSTRACT

Introduction. Pulmonary infections caused by organisms of the Mycobacterium abscessus complex are increasingly prevalent in populations at risk, such as patients with cystic fibrosis, bronchiectasis and emphysema.Hypothesis. M. abscessus infection of the lung is not observed in immunocompetent individuals, which raises the possibility that the compromised lung environment is a suitable niche for the pathogen to thrive in due to the overproduction of mucus and high amounts of host cell lysis.Aim. Evaluate the ability of M. abscessus to form biofilm and grow utilizing in vitro conditions as seen in immunocompromised lungs of patients.Methodology. We compared biofilm formation and protein composition in the presence and absence of synthetic cystic fibrosis medium (SCFM) and evaluated the bacterial growth when exposed to human DNA.Results. M. abscessus is capable of forming biofilm in SCFM. By eliminating single components found in the medium, it became clear that magnesium works as a signal for the biofilm formation, and chelation of the divalent cations resulted in the suppression of biofilm formation. Investigation of the specific proteins expressed in the presence of SCFM and in the presence of SCFM lacking magnesium revealed many different proteins between the conditions. M. abscessus also exhibited growth in SCFM and in the presence of host cell DNA, although the mechanism of DNA utilization remains unclear.Conclusions. In vitro conditions mimicking the airways of patients with cystic fibrosis appear to facilitate M. abscessus establishment of infection, and elimination of magnesium from the environment may affect the ability of the pathogen to establish infection.

PMID:35014948 | DOI:10.1099/jmm.0.001467

Osteoporos Int. 2022 Jan 11. doi: 10.1007/s00198-021-06290-x. Online ahead of print.

ABSTRACT

People with cystic fibrosis (CF) are at increased risk of fractures. Our study found that low trabecular bone score (TBS) (a measure of bone strength) may help identify people with CF at risk of fractures especially when combined with bone density measured by DXA, age, hemoglobin A1c, and transplant status.

INTRODUCTION: People with cystic fibrosis (CF) are at increased risk of fractures. This study aims to evaluate the association of trabecular bone score (TBS) with fractures in CF.

METHODS: A cross-sectional study of adults with CF who completed bone density between 2009 and 2019. TBS was applied to lumbar spine studies.

RESULTS: A total of 202 people with CF were included. A history of fracture was present in 36 (17.8%) subjects. Patients with history of fractures had higher hemoglobin A1c (A1C) (7.8 ± 2.7% vs. 6.7 ± 1.7%, p = 0.024), lower femoral neck (FN) Z/T-score (- 1.05 ± 1.08 vs. - 0.44 ± 1.08, p = 0.012), and lower TBS (1.36 ± 0.13 vs. 1.40 ± 0.11, p = 0.05) compared to those without. Lung transplant recipients had a higher prevalence of fractures (50% vs. 14.1%, p < 0.001). The odds ratio (95%CI) of having a fracture for subjects with TBS (≤ 1.2 vs. > 1.2) stratified by FN Z/T-score (≤ - 2.0 or > - 2.0) was 3.88 (0.92, 16.35), p = 0.07. ROC analysis showed TBS was significantly associated with fractures (p < 0.05); however, FN BMD was superior. A model combining FN BMD, age, A1c, transplant, and TBS improved ROC compared to FN BMD + age (0.837 vs. 0.779, p = 0.031).

CONCLUSIONS: TBS ≤ 1.2 may identify people with CF at high risk of fractures. A model combining FN BMD, age, A1c, transplant, and TBS was significantly associated with fractures compared to FN BMD + age. Future studies are needed to evaluate the prediction of fractures in people with CF using clinical and bone parameters.

PMID:35013769 | DOI:10.1007/s00198-021-06290-x

Rev Argent Microbiol. 2022 Jan 7:S0325-7541(21)00101-2. doi: 10.1016/j.ram.2021.10.004. Online ahead of print.

ABSTRACT

Achromobacter spp. are increasingly recognized as emerging pathogens in immunocompromised patients or suffering cystic fibrosis, but unusual in immunocompetent hosts or individuals that underwent surgery. In this study we describe two simultaneous events attributable to two different Achromobacter spp. contaminated sources. One event was related to an episode of pseudo-bacteremia due to sodium citrate blood collection tubes contaminated with Achromobacter insuavis and the other to Achromobacter genogroup 20 infection and colonization caused by an intrinsically contaminated chlorhexidine soap solution. Both threatened the appropriate use of antimicrobials. Molecular approaches were critical to achieving the accurate species identification and to assess the clonal relationship, strengthening the need for dedicated, multidisciplinary and collaborative work of microbiologists, specialists in infectious diseases, epidemiologists and nurses in the control of infections to clarify these epidemiological situations.

PMID:35012807 | DOI:10.1016/j.ram.2021.10.004

Ther Adv Respir Dis. 2022 Jan-Dec;16:17534666211070143. doi: 10.1177/17534666211070143.

ABSTRACT

OBJECTIVES: [1] To investigate the cardiorespiratory fitness (CRF) levels in children and adolescents with cystic fibrosis (CF) with no ventilatory limitation (ventilatory reserve ⩾ 15%) during exercise, and [2] to assess which physiological factors are related to CRF.

METHODS: A cross-sectional study design was used in 8- to 18-year-old children and adolescents with CF. Cardiopulmonary exercise testing was used to determine peak oxygen uptake normalized to body weight as a measure of CRF. Patients were defined as having 'low CRF' when CRF was less than 82%predicted. Physiological predictors used in this study were body mass index z-score, P. Aeruginosa lung infection, impaired glucose tolerance (IGT) including CF-related diabetes, CF-related liver disease, sweat chloride concentration, and self-reported physical activity. Backward likelihood ratio (LR) logistic regression analysis was used.

RESULTS: Sixty children and adolescents (51.7% boys) with a median age of 15.3 years (25th-75th percentile: 12.9-17.0 years) and a mean percentage predicted forced expiratory volume in 1 second of 88.5% (±16.9) participated. Mean percentage predicted CRF (ppVO2peak/kg) was 81.4% (±12.4, range: 51%-105%). Thirty-three patients (55.0%) were classified as having 'low CRF'. The final model that best predicted low CRF included IGT (p = 0.085; Exp(B) = 6.770) and P. Aeruginosa lung infection (p = 0.095; Exp(B) = 3.945). This model was able to explain between 26.7% and 35.6% of variance.

CONCLUSIONS: CRF is reduced in over half of children and adolescents with CF with normal ventilatory reserve. Glucose intolerance and P. Aeruginosa lung infection seem to be associated to low CRF in children and adolescents with CF.

PMID:35012387 | DOI:10.1177/17534666211070143

J Clin Med. 2021 Dec 23;11(1):44. doi: 10.3390/jcm11010044.

ABSTRACT

BACKGROUND: Plastic bronchitis (PB) may occur not only in children following palliative Fontan procedure but also in those without underlying heart disease. We aim to assess the clinical course, therapeutic measures, outcome, and follow-up of PB in children with congenital heart disease (CHD) and children without cardiac problems.

METHODS: This retrospective case series assessed children with PB admitted to hospital between 2015 and 2019. Parents or guardians of patients were contacted by e-mail or telephone between September 2017 and June 2019 to enquiry about recurrence of PB and strategy of treatment. The diagnosis of PB was based on the expectoration (spontaneous or during bronchoscopy) of endobronchial plugs.

RESULTS: This study delineated the clinical, histological, and laboratory features of plastic bronchitis in children following Fontan procedure (Group A) and in those without heart defects (Group B, non-CHD children). The main symptoms were cough accompanied by dyspnea, and hypoxemia with a decrease in oxygen saturation, often leading to acute respiratory failure. In children with CHD, the first episode of PB occurred at a relatively young age. Although chronic, i.e., lasting more than 3 weeks, inhaled therapy was implemented in both groups of patients, the recurrences of PB were observed. The mean time to PB recurrence after the first episode in Group A was longer than that in Group B (1.47 vs. 0.265 years, p = 0.2035). There was no re-episode with recurrence of PB in 3 cases out of 10 in total in Group A (30%) and 1 case out of 4 in total in Group B (25%). While the majority of children in Group A usually developed bronchial casts on the right side, the patients in Group B (without CHD) suffered from bronchial casts located only on the left side.

CONCLUSIONS: Despite many similarities, clinical, histological, and laboratory studies in the children with plastic bronchitis after Fontan's surgery and in children without heart defects suggest that there are differences in the course of the disease in patients without CHD, such as a more advanced age of the first episode of PB, the location of plastic casts on the left side, and a stronger role of inflammatory factors and mechanisms. Further research is needed to understand the pathophysiology of PB and choose the most appropriate therapy.

PMID:35011785 | DOI:10.3390/jcm11010044

Cells. 2022 Jan 1;11(1):136. doi: 10.3390/cells11010136.

ABSTRACT

Although some therapeutic progress has been achieved in developing small molecules that correct F508del-CFTR defects, the mechanism of action (MoA) of these compounds remain poorly elucidated. Here, we investigated the effects and MoA of MCG1516A, a newly developed F508del-CFTR corrector. MCG1516A effects on wild-type (WT) and F508del-CFTR were assessed by immunofluorescence microscopy, and biochemical and functional assays both in cell lines and in intestinal organoids. To shed light on the MoA of MCG1516A, we evaluated its additivity to the FDA-approved corrector VX-661, low temperature, genetic revertants of F508del-CFTR (G550E, R1070W, and 4RK), and the traffic-null variant DD/AA. Finally, we explored the ability of MCG1516A to rescue trafficking and function of other CF-causing mutations. We found that MCG1516A rescues F508del-CFTR with additive effects to VX-661. A similar behavior was observed for WT-CFTR. Under low temperature incubation, F508del-CFTR demonstrated an additivity in processing and function with VX-661, but not with MCG1516A. In contrast, both compounds promoted additional effects to low temperature to WT-CFTR. MCG1516A demonstrated additivity to genetic revertant R1070W, while VX-661 was additive to G550E and 4RK. Nevertheless, none of these compounds rescued DD/AA trafficking. Both MCG1516A and VX-661 rescued CFTR processing of L206W- and R334W-CFTR with greater effects when these compounds were combined. In summary, the absence of additivity of MCG1516A to genetic revertant G550E suggests a putative binding site for this compound on NBD1:NBD2 interface. Therefore, a combination of MCG1516A with compounds able to rescue DD/AA traffic, or mimicking the actions of revertant R1070W (e.g., VX-661), could enhance correction of F508del-CFTR defects.

PMID:35011698 | DOI:10.3390/cells11010136

Cells. 2021 Dec 24;11(1):54. doi: 10.3390/cells11010054.

ABSTRACT

CFTR, the cystic fibrosis (CF) gene-encoded epithelial anion channel, has a prominent role in driving chloride, bicarbonate and fluid secretion in the ductal cells of the exocrine pancreas. Whereas severe mutations in CFTR cause fibrosis of the pancreas in utero, CFTR mutants with residual function, or CFTR variants with a normal chloride but defective bicarbonate permeability (CFTRBD), are associated with an enhanced risk of pancreatitis. Recent studies indicate that CFTR function is not only compromised in genetic but also in selected patients with an acquired form of pancreatitis induced by alcohol, bile salts or smoking. In this review, we summarize recent insights into the mechanism and regulation of CFTR-mediated and modulated bicarbonate secretion in the pancreatic duct, including the role of the osmotic stress/chloride sensor WNK1 and the scaffolding protein IRBIT, and current knowledge about the role of CFTR in genetic and acquired forms of pancreatitis. Furthermore, we discuss the perspectives for CFTR modulator therapy in the treatment of exocrine pancreatic insufficiency and pancreatitis and introduce pancreatic organoids as a promising model system to study CFTR function in the human pancreas, its role in the pathology of pancreatitis and its sensitivity to CFTR modulators on a personalized basis.

PMID:35011616 | DOI:10.3390/cells11010054

Int J Mol Sci. 2021 Dec 21;23(1):24. doi: 10.3390/ijms23010024.

ABSTRACT

Most of the ~2100 CFTR variants so far reported are very rare and still uncharacterized regarding their cystic fibrosis (CF) disease liability. Since some may respond to currently approved modulators, characterizing their defect and response to these drugs is essential. Here we aimed characterizing the defect associated with four rare missense (likely Class II) CFTR variants and assess their rescue by corrector drugs. We produced CFBE cell lines stably expressing CFTR with W57G, R560S, H1079P and Q1100P, assessed their effect upon CFTR expression and maturation and their rescue by VX-661/VX-445 correctors. Results were validated by forskolin-induced swelling assay (FIS) using intestinal organoids from individuals bearing these variants. Finally, knock-down (KD) of genes previously shown to rescue F508del-CFTR was assessed on these mutants. Results show that all the variants preclude the production of mature CFTR, confirming them as Class II mutations. None of the variants responded to VX-661 but the combination rescued H1079P- and Q1100P-CFTR. The KD of factors that correct F508del-CFTR retention only marginally rescued R560S- and H1079P-CFTR. Overall, data evidence that Class II mutations induce distinct molecular defects that are neither rescued by the same corrector compounds nor recognized by the same cellular machinery, thus requiring personalized drug discovery initiatives.

PMID:35008443 | DOI:10.3390/ijms23010024