Different CFTR modulator combinations downregulate inflammation differently in cystic fibrosis

Outcomes of SARS-CoV-2 infection in patients with cystic fibrosis: A multicenter retrospective research network study

BACKGROUND

In this study, we report clinical outcomes in COVID-19 infection in a large cohort of people with cystic fibrosis (pwCF) and compare these outcomes to a propensity score matched cohort of people without CF.

METHODS

Analysis of a multicenter research network TriNETX was performed including patients more than 16 years of age diagnosed with COVID-19. Outcomes in COVID-19 positive pwCF were compared with a propensity-matched cohort of people without CF.

RESULTS

A total of 507,810 patients with COVID-19 were included (422 patients, 0.08% with CF; 507,388 patients, 99.92% without CF. Mean age at COVID-19 diagnosis in CF cohort was 46.6 ± 19.3 years, with female predominance (n = 225, 53.32%). Majority of the participants were Caucasian (n = 309, 73.22%). In the crude, unmatched analysis, mortality, hospitalization, critical care need, mechanical ventilation, acute kidney injury and composite (combination of intubation and mortality) outcome at 30 days was higher in the pwCF. Following robust propensity matching, pwCF had higher hospitalization rate (RR 1.56, 95% CI 1.20-2.04), critical care need (RR 1.78, 95% CI 1.13-2.79), and acute renal injury (RR 1.60, 95% CI 1.07-2.39) as compared to patients without CF.

CONCLUSION

People with CF are at risk of poor outcomes with COVID-19.5.2% of these patients died within one month of COVID-19 diagnosis, and more than one in 10 patients required critical care. Therefore, the relatively young median age of cystic fibrosis patients, and lower prevalence of obesity do not protect these patients from severe disease contrary to prior reports.

Pseudomonas aeruginosa infection, but not mono or dual-combination CFTR modulator therapy affects circulating regulatory T cells in an adult population with cystic fibrosis

BACKGROUND

Chronic infection and an exaggerated inflammatory response are key drivers of the pathogenesis of cystic fibrosis (CF), especially CF lung disease. An imbalance of pro- and anti-inflammatory mediators, including dysregulated Th2/Th17 cells and impairment of regulatory T cells (Tregs), maintain CF inflammation. CF transmembrane conductance regulator (CFTR) modulator therapy might influence these immune cell abnormalities.

METHODS

Peripheral blood mononuclear cells and serum samples were collected from 108 patients with CF (PWCF) and 40 patients with non-CF bronchiectasis. Samples were analysed for peripheral blood lymphocytes subsets (Tregs; Th1-, Th1/17-, Th17- and Th2-effector cells) and systemic T helper cell-associated cytokines (interleukin [IL]-5, IL-13, IL-2, IL-6, IL-9, IL-10, IL-17A, IL-17F, IL-4, IL-22, interferon-γ, tumour necrosis factor-α) using flow cytometry.

RESULTS

51% of PWCF received CFTR modulators (ivacaftor, ivacaftor/ lumacaftor or tezacaftor/ ivacaftor). There were no differences in proportions of analysed T cell subsets or cytokines between PWCF who were versus were not receiving CFTR modulators. Additional analysis revealed lower percentages of Tregs in PWCF and chronic pulmonary Pseudomonas aeruginosa infection; this difference was also present in PWCF treated with CFTR modulators. Patients with non-CF bronchiectasis tended to have higher percentages of Th2- and Th17-cells and higher levels of peripheral cytokines versus PWCF.

CONCLUSIONS

Chronic P. aeruginosa lung infection appears to impair Tregs in PWCF (independent of CFTR modulator therapy) but not those with non-CF bronchiectasis. Moreover, our data showed no statistically significant differences in major subsets of peripheral lymphocytes and cytokines among PWCF who were versus were not receiving CFTR modulators.

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.

Ivacaftor Reduces Inflammatory Mediators in Upper Airway Lining Fluid From Cystic Fibrosis Patients With a G551D Mutation: Serial Non-Invasive Home-Based Collection of Upper Airway Lining Fluid

In cystic fibrosis (CF) therapy, the recent approval of CF-transmembrane conductance regulator (CFTR) channel modulators is considered to be the major breakthrough. However, the current first-line approach based mainly on pulmonary function to measure effects of the novel therapy, tested by forced expiratory volumes in one second (FEV₁), provides restricted sensitivity to detect early structural damages. Accordingly, there is a need for new sensitive surrogate parameters. Most interestingly, these should quantify inflammation that precedes a decline of pulmonary function. We present a novel method assessing inflammatory markers in the upper airways’ epithelial lining fluid (ELF) obtained by nasal lavage (NL). In contrast to broncho-alveolar lavage, ELF sampling by NL is an attractive method due to its limited invasiveness which allows repeated analyses, even performed in a home-based setting. In a longitudinal cohort study (ClinicalTrials.gov, Identifier: NCT02311140), we assessed changes of inflammatory mediators in 259 serially obtained nasal lavages taken up to every second day before and during therapy with ivacaftor from ten CF patients carrying a G551D mutation. Patients were trained to sample NL-fluid at home, to immediately freeze and transfer chilled secretions to centers. Neutrophil Elastase, Interleukins IL-1β, IL-6 and IL-8 in NL were quantified. During 8-12 weeks of ivacaftor-treatment, median values of IL-1β and IL-6 significantly declined 2.29-fold (2.97→1.30 pg/mL), and 1.13-fold (6.48→5.72 pg/mL), respectively. In parallel, sweat tests and pulmonary function improved considerably. This is the first study assessing changes of airway inflammation on a day-to-day basis in CF patients receiving a newly administered CFTR-modulator therapy. It proves a decline of airway inflammation during ivacaftor-therapy.

The effects of nano-curcumin as a nutritional strategy on clinical and inflammatory factors in children with cystic fibrosis: the study protocol for a randomized controlled trial

BACKGROUND

Cystic fibrosis (CF) is a genetic disorder, which is caused by the CFTR protein defects. Along with CFTR dysfunction, inflammation plays a key role in the disease outcomes. Inflammation may develop due to the internal dysfunction of the CFTR protein or external factors. Curcumin affects the CFTR protein function primarily as a corrector and potentiator and secondary as an anti-inflammatory and antimicrobial agent. The present study aims to assess the impact of nano-curcumin on clinical and inflammatory markers in children with CF.

METHODS

This prospective, double blind control trial will be conducted at the Akbar Children's Hospital in Mashhad, Iran. Children with CF will be enrolled based on the eligibility criteria. Placebo and curcumin with the maximum dose of 80 mg considering the body surface of the patients will be administrated for 3 months. The primary outcome is to evaluate inflammation based on serum interleukin-6, interleukin-10, and hs-CRP, stool calprotectin, and neutrophil count of nasopharyngeal swab. The secondary outcome involved clinical assessment via spirometry, anthropometrics, and quality of life. They will be assessed before and after 3 months.

DISCUSSION

Due to the multifarious effects of curcumin on CF disease, it could be proposed as a nutritional strategy in the treatment of cystic fibrosis.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20200705048018N1 . Registered on July 10, 2020.

Cystic Fibrosis Lung Disease in the Aging Population

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

Airway Epithelial Inflammation In Vitro Augments the Rescue of Mutant CFTR by Current CFTR Modulator Therapies

In cystic fibrosis (CF), defective biogenesis and activity of the cystic fibrosis transmembrane conductance regulator (CFTR) leads to airway dehydration and impaired mucociliary clearance, resulting in chronic airway infection and inflammation. The most common CFTR mutation, F508del, results in a processing defect in which the protein is retained in the endoplasmic reticulum and does not reach the apical surface. CFTR corrector compounds address this processing defect to promote mutant CFTR transfer to the apical membrane. When coupled with potentiators to increase CFTR channel activity, these drugs yield significant clinical benefits in CF patients carrying the F508del mutation. However, processing of CFTR and other proteins can be influenced by environmental factors such as inflammation, and the impact of airway inflammation on pharmacological activity of CFTR correctors is not established. The present study evaluated CFTR-rescuing therapies in inflamed CF airway epithelial cultures, utilizing models that mimic the inflammatory environment of CF airways. Primary bronchial epithelial cultures from F508del/F508del CF patients were inflamed by mucosal exposure to one of two inflammatory stimuli: 1) supernatant from mucopurulent material from CF airways with advanced lung disease, or 2) bronchoalveolar lavage fluid from pediatric CF patients. Cultures inflamed with either stimulus exhibited augmented F508del responses following therapy with correctors VX-809 or VX-661, and overcame the detrimental effects of chronic exposure to the CFTR potentiator VX-770. Remarkably, even the improved CFTR rescue responses resulting from a clinically effective triple therapy (VX-659/VX-661/VX-770) were enhanced by epithelial inflammation. Thus, the airway inflammatory milieu from late- and early-stage CF lung disease improves the efficacy of CFTR modulators, regardless of the combination therapy used. Our findings suggest that pre-clinical evaluation of CFTR corrector therapies should be performed under conditions mimicking the native inflammatory status of CF airways, and altering the inflammatory status of CF airways may change the efficacy of CFTR modulator therapies.

Changes in the Cystic Fibrosis Airway Microbiome in Response to CFTR Modulator Therapy

The development of CFTR modulator therapies significantly changed the treatment scheme of people with cystic fibrosis. However, CFTR modulator therapy is still a life-long treatment, which is not able to correct the genetic defect and cure the disease. Therefore, it becomes crucial to understand the effects of such modulation of CFTR function on the airway physiology, especially on airway infections and inflammation that are currently the major life-limiting factors in people with cystic fibrosis. In this context, understanding the dynamics of airway microbiome changes in response to modulator therapy plays an essential role in developing strategies for managing airway infections. Whether and how the newly available therapies affect the airway microbiome is still at the beginning of being deciphered. We present here a brief review summarizing the latest information about microbiome alterations in light of modern cystic fibrosis modulator therapy.

Dysfunctional Inflammation in Cystic Fibrosis Airways: From Mechanisms to Novel Therapeutic Approaches

Cystic fibrosis (CF) is an inherited disorder caused by mutations in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein, an ATP-gated chloride channel expressed on the apical surface of airway epithelial cells. CFTR absence/dysfunction results in defective ion transport and subsequent airway surface liquid dehydration that severely compromise the airway microenvironment. Noxious agents and pathogens are entrapped inside the abnormally thick mucus layer and establish a highly inflammatory environment, ultimately leading to lung damage. Since chronic airway inflammation plays a crucial role in CF pathophysiology, several studies have investigated the mechanisms responsible for the altered inflammatory/immune response that, in turn, exacerbates the epithelial dysfunction and infection susceptibility in CF patients. In this review, we address the evidence for a critical role of dysfunctional inflammation in lung damage in CF and discuss current therapeutic approaches targeting this condition, as well as potential new treatments that have been developed recently. Traditional therapeutic strategies have shown several limitations and limited clinical benefits. Therefore, many efforts have been made to develop alternative treatments and novel therapeutic approaches, and recent findings have identified new molecules as potential anti-inflammatory agents that may exert beneficial effects in CF patients. Furthermore, the potential anti-inflammatory properties of CFTR modulators, a class of drugs that directly target the molecular defect of CF, also will be critically reviewed. Finally, we also will discuss the possible impact of SARS-CoV-2 infection on CF patients, with a major focus on the consequences that the viral infection could have on the persistent inflammation in these patients.

CFTR Correctors and Antioxidants Partially Normalize Lipid Imbalance but not Abnormal Basal Inflammatory Cytokine Profile in CF Bronchial Epithelial Cells

A deficiency in cystic fibrosis transmembrane conductance regulator (CFTR) function in CF leads to chronic lung disease. CF is associated with abnormalities in fatty acids, ceramides, and cholesterol, their relationship with CF lung pathology is not completely understood. Therefore, we examined the impact of CFTR deficiency on lipid metabolism and pro-inflammatory signaling in airway epithelium using mass spectrometric, protein array. We observed a striking imbalance in fatty acid and ceramide metabolism, associated with chronic oxidative stress under basal conditions in CF mouse lung and well-differentiated bronchial epithelial cell cultures of CFTR knock out pig and CF patients. Cell-autonomous features of all three CF models included high ratios of ω-6- to ω-3-polyunsaturated fatty acids and of long- to very long-chain ceramide species (LCC/VLCC), reduced levels of total ceramides and ceramide precursors. In addition to the retinoic acid analog fenretinide, the anti-oxidants glutathione (GSH) and deferoxamine partially corrected the lipid profile indicating that oxidative stress may promote the lipid abnormalities. CFTR-targeted modulators reduced the lipid imbalance and oxidative stress, confirming the CFTR dependence of lipid ratios. However, despite functional correction of CF cells up to 60% of non-CF in Ussing chamber experiments, a 72-h triple compound treatment (elexacaftor/tezacaftor/ivacaftor surrogate) did not completely normalize lipid imbalance or oxidative stress. Protein array analysis revealed differential expression and shedding of cytokines and growth factors from CF epithelial cells compared to non-CF cells, consistent with sterile inflammation and tissue remodeling under basal conditions, including enhanced secretion of the neutrophil activator CXCL5, and the T-cell activator CCL17. However, treatment with antioxidants or CFTR modulators that mimic the approved combination therapies, ivacaftor/lumacaftor and ivacaftor/tezacaftor/elexacaftor, did not effectively suppress the inflammatory phenotype. We propose that CFTR deficiency causes oxidative stress in CF airway epithelium, affecting multiple bioactive lipid metabolic pathways, which likely play a role in CF lung disease progression. A combination of anti-oxidant, anti-inflammatory and CFTR targeted therapeutics may be required for full correction of the CF phenotype.

Cytokine Storm and Mucus Hypersecretion in COVID-19: Review of Mechanisms

Mucus is an integral part of the respiratory physiology. It protects the respiratory tract by acting as a physical barrier against inhaled particles and microbes. Excessive inflammation in conditions such as COVID-19 can result in over-production of mucus which obstructs the airway. Build-up of mucus can also contribute to recurrent airway infection, causing further obstruction. This article summarizes the current understanding and knowledge of respiratory mucus production and proposes the role of cytokine storm in inducing sudden mucus hypersecretion in COVID-19. Based on these cascades, the active constituents that inhibit or activate several potential targets are outlined for further research. These may be explored for the discovery and design of drugs to combat cytokine storm and its ensuing complications.

A bird eye view on cystic fibrosis: An underestimated multifaceted chronic disorder

Cystic fibrosis (CF) is an autosomal recessive disease which involves the mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF involves in the inflammatory processes and is considered as a multisystem disorder that is not confined to lungs, but it also affects other vital organs that leads to numerous co-morbidities. The respiratory disorder in the CF results in mortality and morbidity which is characterized by series of serious events involving mucus hypersecretion, microbial infections, airways obstruction, inflammation, destruction of epithelium, tissue remodeling and terminal lung diseases. Mucins are the high molecular weight glycoproteins important for the viscoelastic properties of the mucus, play a significant role in the disease mechanisms. Determining the functional association between the CFTR and mucins might help to identify the putative target for specific therapeutic approach. In fact, furin enzyme which helps in the entry of novel COVID-19 virus into the cell, is upregulated in CF and this can also serve as a potential target for CF treatment. Moreover, the use of nano-formulations for CF treatment is an area of research being widely studied as they have also demonstrated promising outcomes. The in-depth knowledge of non-coding RNAs like miRNAs and lncRNAs and their functional association with CFTR gene expression and mutation can provide a different range of opportunity to identify the promising therapeutic approaches for CF.

Targeting cystic fibrosis inflammation in the age of CFTR modulators: focus on macrophages

Cystic fibrosis (CF) is a life-shortening, multi-organ, autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The most prominent clinical manifestation in CF is the development of progressive lung disease characterised by an intense, chronic inflammatory airway response that culminates in respiratory failure and, ultimately, death. In recent years, a new class of therapeutics that have the potential to correct the underlying defect in CF, known as CFTR modulators, have revolutionised the field. Despite the exciting success of these drugs, their impact on airway inflammation, and its long-term consequences, remains undetermined. In addition, studies querying the absolute requirement for infection as a driver of CF inflammation have challenged the traditional consensus on CF pathogenesis, and also emphasise the need to prioritise complementary anti-inflammatory treatments in CF. Macrophages, often overlooked in CF research despite their integral role in other chronic inflammatory pathologies, have increasingly become recognised as key players in the initiation, perpetuation and resolution of CF lung inflammation, perhaps as a direct result of CFTR dysfunction. These findings suggest that macrophages may be an important target for novel anti-inflammatory interventional strategies to effectively treat CF lung function decline. This review will consider evidence for the efficacy of anti-inflammatory drugs in the treatment of CF, the potential role of macrophages, and the significance of targeting these pathways at a time when rectifying the basic defect in CF, through use of novel CFTR modulator therapies, is becoming increasingly viable.

Dysregulated signalling pathways in innate immune cells with cystic fibrosis mutations

Cystic fibrosis (CF) is one of the most common life-limiting recessive genetic disorders in Caucasians, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). CF is a multi-organ disease that involves the lungs, pancreas, sweat glands, digestive and reproductive systems and several other tissues. This debilitating condition is associated with recurrent lower respiratory tract bacterial and viral infections, as well as inflammatory complications that may eventually lead to pulmonary failure. Immune cells play a crucial role in protecting the organs against opportunistic infections and also in the regulation of tissue homeostasis. Innate immune cells are generally affected by CFTR mutations in patients with CF, leading to dysregulation of several cellular signalling pathways that are in continuous use by these cells to elicit a proper immune response. There is substantial evidence to show that airway epithelial cells, neutrophils, monocytes and macrophages all contribute to the pathogenesis of CF, underlying the importance of the CFTR in innate immune responses. The goal of this review is to put into context the important role of the CFTR in different innate immune cells and how CFTR dysfunction contributes to the pathogenesis of CF, highlighting several signalling pathways that may be dysregulated in cells with CFTR mutations.

Changing landscape: psychological care in the era of cystic fibrosis transmembrane conductance regulator modulators

PURPOSE OF REVIEW

The current review provides an overview of key psychological issues and challenges for the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator era of care. It discusses research from diagnosis and beyond, to patient-team communication with a particular focus on medical trials, adherence and living with CFTR modulators.

RECENT FINDINGS

The impact of the diagnosis on parents is immense and the complexity of treatment now and in the future, are a challenge for both parents and teams. Communicating digitally is starting to become daily practice for many in CF care, with coronavirus disease 2019 accelerating this process. Participating in trials has a psychological impact, but most of all the (delayed) access and timing of accessing CFTR modulators is an important theme. Adherence remains of significance, both to 'old' and 'new' treatments. Living with CF in the era of CFTR modulators is beginning to impact on patients' quality of life, including new possibilities, opportunities and challenges.

SUMMARY

Psychological care needs to engage and keep pace with the rapid medical changes. Some care priorities remain the same, including psychological screening and assessment, as well as psychoeducation, communication training and psychotherapy. The presence of CF psychologist in the CF clinic remains as important as ever.

Treatment repurposing for inflammatory bowel disease using literature-related discovery and innovation

Inflammatory bowel disease (IBD) incidence has been increasing steadily, most dramatically in the Western developed countries. Treatment often includes lifelong immunosuppressive therapy and surgery. There is a critical need to reduce the burden of IBD and to discover medical therapies with better efficacy and fewer potential side-effects. Repurposing of treatments originally studied in other diseases with similar pathogenesis is less costly and time intensive than de novo drug discovery. This study used a treatment repurposing methodology, the literature-related discovery and innovation (LRDI) text mining system, to identify potential treatments (developed for non-IBD diseases) with sufficient promise for extrapolation to treatment of IBD. By searching for desirable patterns of twenty key biomarkers relevant to IBD (e.g., inflammation, reactive oxygen species, autophagy, barrier function), the LRDI-based query retrieved approximately 9500 records from Medline. The most recent 350 records were further analyzed for proof-of-concept. Approximately 18% (64/350) met the criteria for discovery (not previously studied in IBD human or animal models) and relevance for application to IBD treatment. Many of the treatments were compounds derived from herbal remedies, and the majority of treatments were being studied in cancer, diabetes, and central nervous system disease, such as depression and dementia. As further validation of the search strategy, the query identified ten treatments that have just recently begun testing in IBD models in the last three years. Literature-related discovery and innovation text mining contains a unique search strategy with tremendous potential to identify treatments for repurposing. A more comprehensive query with additional key biomarkers would have retrieved many thousands more records, further increasing the yield of IBD treatment repurposing discovery.

Airway Inflammation and Host Responses in the Era of CFTR Modulators

The arrival of cystic fibrosis transmembrane conductance regulator (CFTR) modulators as a new class of treatment for cystic fibrosis (CF) in 2012 represented a pivotal advance in disease management, as these small molecules directly target the upstream underlying protein defect. Further advancements in the development and scope of these genotype-specific therapies have been transformative for an increasing number of people with CF (PWCF). Despite clear improvements in CFTR function and clinical endpoints such as lung function, body mass index (BMI), and frequency of pulmonary exacerbations, current evidence suggests that CFTR modulators do not prevent continued decline in lung function, halt disease progression, or ameliorate pathogenic organisms in those with established lung disease. Furthermore, it remains unknown whether their restorative effects extend to dysfunctional CFTR expressed in phagocytes and other immune cells, which could modulate airway inflammation. In this review, we explore the effects of CFTR modulators on airway inflammation, infection, and their influence on the impaired pulmonary host defences associated with CF lung disease. We also consider the role of inflammation-directed therapies in light of the widespread clinical use of CFTR modulators and identify key areas for future research.

The Role of Specialized Pro-Resolving Mediators in Cystic Fibrosis Airways Disease

Cystic Fibrosis (CF) is a recessive genetic disease due to mutations of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene encoding the CFTR chloride channel. The ion transport abnormalities related to CFTR mutation generate a dehydrated airway surface liquid (ASL) layer, which is responsible for an altered mucociliary clearance, favors infections and persistent inflammation that lead to progressive lung destruction and respiratory failure. The inflammatory response is normally followed by an active resolution phase to return to tissue homeostasis, which involves specialized pro-resolving mediators (SPMs). SPMs promote resolution of inflammation, clearance of microbes, tissue regeneration and reduce pain, but do not evoke unwanted immunosuppression. The airways of CF patients showed a decreased production of SPMs even in the absence of pathogens. SPMs levels in the airway correlated with CF patients' lung function. The prognosis for CF has greatly improved but there remains a critical need for more effective treatments that prevent excessive inflammation, lung damage, and declining pulmonary function for all CF patients. This review aims to highlight the recent understanding of CF airway inflammation and the possible impact of SPMs on functions that are altered in CF airways.

Mutations of the cystic fibrosis transmembrane conductance regulator gene in males with congenital bilateral absence of the vas deferens: Reproductive implications and genetic counseling (Review)

Congenital bilateral absence of the vas deferens (CBAVD) is predominantly caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CBAVD accounts for 2–6% of male infertility cases and up to 25% of cases of obstructive azoospermia. With the use of pre-implantation genetic diagnosis, testicular or epididymal sperm aspiration, intracytoplasmic sperm injection and in vitro fertilization, patients affected by CBAVD are able to have children who do not carry CFTR gene mutations, thereby preventing disease. Therefore, genetic counseling should be provided to couples receiving assisted reproductive techniques to discuss the impact of CFTR gene mutations on reproductive health. In the present article, the current literature concerning the CFTR gene and its association with CBAVD is reviewed.

CFTR Modulators Dampen Aspergillus-Induced Reactive Oxygen Species Production by Cystic Fibrosis Phagocytes

Excessive inflammation by phagocytes during Aspergillus fumigatus infection is thought to promote lung function decline in CF patients. CFTR modulators have been shown to reduce A. fumigatus colonization in vivo, however, their antifungal and anti-inflammatory mechanisms are unclear. Other treatments including azithromycin and acebilustat may dampen Aspergillus-induced inflammation due to their immunomodulatory properties. Therefore, we set out in this study to determine the effects of current CF therapies on ROS production and fungal killing, either direct or indirect by enhancing antifungal immune mechanisms in peripheral blood immune cells from CF patients upon A. fumigatus infection. Isolated peripheral blood mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) from CF patients and healthy volunteers were challenged with A. fumigatus following pre-treatment with CFTR modulators, azithromycin or acebilustat. Ivacaftor/lumacaftor treated CF and control subject PMNs resulted in a significant reduction (p < 0.05) in Aspergillus-induced ROS. For CF PBMC, Aspergillus-induced ROS was significantly reduced when pre-treated with ivacaftor alone (p < 0.01) or in combination with lumacaftor (p < 0.01), with a comparable significant reduction in control subject PBMC (p < 0.05). Azithromycin and acebilustat had no effect on ROS production by CF or control subject phagocytes. None of the treatments showed an indirect or direct antifungal activity. In summary, CFTR modulators have potential for additional immunomodulatory benefits to prevent or treat Aspergillus-induced inflammation in CF. The comparable effects of CFTR modulators observed in phagocytes from control subjects questions their exact mechanism of action.

Novel Anti-Inflammatory Approaches for Cystic Fibrosis Lung Disease: Identification of Molecular Targets and Design of Innovative Therapies

Cystic fibrosis (CF) is the most common genetic disorder among Caucasians, estimated to affect more than 70,000 people in the world. Severe and persistent bronchial inflammation and chronic bacterial infection, along with airway mucus obstruction, are hallmarks of CF lung disease and participate in its progression. Anti-inflammatory therapies are, therefore, of particular interest for CF lung disease. Furthermore, a better understanding of the molecular mechanisms involved in airway infection and inflammation in CF has led to the development of new therapeutic approaches that are currently under evaluation by clinical trials. These new strategies dedicated to CF inflammation are designed to treat different dysregulated aspects such as oxidative stress, cytokine secretion, and the targeting of dysregulated pathways. In this review, we summarize the current understanding of the cellular and molecular mechanisms that contribute to abnormal lung inflammation in CF, as well as the new anti-inflammatory strategies proposed to CF patients by exploring novel molecular targets and novel drug approaches.

Macrophage dysfunction in cystic fibrosis: Nature or nurture?

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) affect the homeostasis of chloride flux by epithelial cells. This has deleterious consequences, especially in respiratory epithelia, where the defect results in mucus accumulation distinctive of cystic fibrosis. CFTR is, however, also expressed in phagocytic cells, like macrophages. Immune cells are highly sensitive to conditioning by their environment; thus, CFTR dysfunction in epithelia influences macrophages by affecting the lung milieu, but the mutations also appear to be directly consequential for intrinsic macrophage functions. Particular mutations can alter CFTR's folding, traffic of the protein to the membrane and function. As such, understanding the intrinsic effects of CFTR mutation requires distinguishing the secondary effects of misfolded CFTR on cell stress pathways from the primary defect of CFTR dysfunction/absence. Investigations into CFTR's role in macrophages have exploited various models, each with their own advantages and limitations. This review summarizes these methodologic approaches, discussing their physiological correspondence and highlighting key findings. The controversy surrounding CFTR-dependent acidification is used as a case study to highlight difficulties in commensurability across model systems. Recent work in macrophage biology, including polarization and host-pathogen interaction studies, brought into the context of CFTR research, offers potential explanations for observed discrepancies between studies. Moreover, the rapid advancement of novel gene editing technologies and new macrophage model systems makes this assessment of the field's models and methodologies timely.

Targeting the Heme Oxygenase 1/Carbon Monoxide Pathway to Resolve Lung Hyper-Inflammation and Restore a Regulated Immune Response in Cystic Fibrosis

In individuals with cystic fibrosis (CF), lung hyper-inflammation starts early in life and is perpetuated by mucus obstruction and persistent bacterial infections. The continuous tissue damage and scarring caused by non-resolving inflammation leads to bronchiectasis and, ultimately, respiratory failure. Macrophages (MΦs) are key regulators of immune response and host defense. We and others have shown that, in CF, MΦs are hyper-inflammatory and exhibit reduced bactericidal activity. Thus, MΦs contribute to the inability of CF lung tissues to control the inflammatory response or restore tissue homeostasis. The non-resolving hyper-inflammation in CF lungs is attributed to an impairment of several signaling pathways associated with resolution of the inflammatory response, including the heme oxygenase-1/carbon monoxide (HO-1/CO) pathway. HO-1 is an enzyme that degrades heme groups, leading to the production of potent antioxidant, anti-inflammatory, and bactericidal mediators, such as biliverdin, bilirubin, and CO. This pathway is fundamental to re-establishing cellular homeostasis in response to various insults, such as oxidative stress and infection. Monocytes/MΦs rely on abundant induction of the HO-1/CO pathway for a controlled immune response and for potent bactericidal activity. Here, we discuss studies showing that blunted HO-1 activation in CF-affected cells contributes to hyper-inflammation and defective host defense against bacteria. We dissect potential cellular mechanisms that may lead to decreased HO-1 induction in CF cells. We review literature suggesting that induction of HO-1 may be beneficial for the treatment of CF lung disease. Finally, we discuss recent studies highlighting how endogenous HO-1 can be induced by administration of controlled doses of CO to reduce lung hyper-inflammation, oxidative stress, bacterial infection, and dysfunctional ion transport, which are all hallmarks of CF lung disease.

The role of inflammation in cystic fibrosis pulmonary exacerbations

INTRODUCTION

Cystic Fibrosis pulmonary exacerbations are critical events in the lives of people with CF that have deleterious effects on lung function, quality of life, and life expectancy. There are significant unmet needs in the management of exacerbations. We review here the associated inflammatory changes that underlie these events and are of interest for the development of biomarkers of exacerbation.

AREAS COVERED

Inflammatory responses in CF are abnormal and contribute to a sustained proinflammatory lung microenvironment, abundant in proinflammatory mediators and deficient in counter-regulatory mediators that terminate and resolve inflammation. There is increasing interest in these inflammatory pathways to discover novel biomarkers for pulmonary exacerbation management. In this review, we explore the inflammatory changes occurring during intravenous antibiotic therapy for exacerbation and how they may be applied as biomarkers to guide exacerbation therapy. A literature search was conducted using the PubMed database in February 2020.

EXPERT OPINION

Heterogeneity in inflammatory responses to treatment of a pulmonary exacerbation, a disease process with complex pathophysiology, limits the clinical utility of individual biomarkers. Biomarker panels may be a more successful strategy to capture informative changes within the CF population to improve pulmonary exacerbation management and outcomes.

Laboratory biomarkers for lung disease severity and progression in cystic fibrosis

Although the clinical outcomes of cystic fibrosis (CF) have been markedly improved through the recent implementation of novel CF transmembrane conductance regulator (CFTR) modulator drugs, robust and reliable biomarkers are still demanded for the early detection of CF lung disease progression, monitoring treatment efficacy and predicting life-threatening clinical complications. Thus, there is an unmet need to identify and validate novel, ideally blood based biomarkers with strong correlations to the severity of CF lung disease, which represents a major contribution to overall CF morbidity and mortality. In this review, we aim to summarize the utility of thus far studied blood-, sputum- and bronchoalveolar lavage (BAL)-based biomarkers to evaluate inflammatory conditions in the lung and to follow treatment efficacy in CF. Measurements of sweat chloride concentrations and the spirometric parameter FEV₁ are currently utilized to monitor CFTR function and the effect of various CF therapies. Nonetheless, both have inherent pitfalls and limitations, thus routinely analyzed biomarkers in blood, sputum or BAL samples are required as surrogates for lung disorders. Recent discovery of new protein (e.g. HE4) and RNA-based biomarkers, such as microRNAs may offer a higher efficacy, which in aggregate may be valuable to evaluate disease prognosis and to substantiate CF drug efficacy.

Vasculitis in Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal-recessive multi-organ disease characterized by airways obstruction, recurrent infections, and systemic inflammation. Vasculitis is a severe complication of CF that affects 2-3% of CF patients and is generally associated with poor prognosis. Various pathogenic mechanisms may be involved in the development of CF-related vasculitis. Bacterial colonization leads to persistent activation of neutrophilic granulocytes, inflammation and damage, contributing to the production of antineutrophil cytoplasmic autoantibodies (ANCAs). The presence of ANCA may on the other hand predispose to bacterial colonization and infection, likely entertaining a vicious circle amplifying inflammation and damage. As a result, in CF-associated vasculitis, ongoing inflammation, immune cell activation, the presence of pathogens, and the use of numerous medications may lead to immune complex formation and deposition, subsequently causing leukocytoclastic vasculitis. Published individual case reports and small case series suggest that patients with CF-associated vasculitis require immune modulating treatment, including non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, hydroxychloroquine, and/or disease-modifying anti-rheumatic drugs (DMARDs). As immunosuppression increases the risk of infection and/or malignancy, which are both already increased in people with CF, possible alternative medications may involve the blockade of individual cytokine or inflammatory pathways, or the use of novel CFTR modulators. This review summarizes molecular alterations involved in CF-associated vasculitis, clinical presentation, and complications, as well as currently available and future treatment options.