Septin-dependent defense mechanisms against Pseudomonas aeruginosa are stalled in cystic fibrosis bronchial epithelial cells.

Airway epithelial cells form a physical barrier against inhaled pathogens and coordinate innate immune responses in the lungs. Bronchial cells in people with cystic fibrosis (pwCF) are colonized by Pseudomonas aeruginosa because of the accumulation of mucus in the lower airways and an altered immune response. This leads to chronic inflammation, lung tissue damage, and accelerated decline in lung function. Thus, identifying the molecular factors involved in the host response in the airways is crucial for developing new therapeutic strategies. The septin (SEPT) cytoskeleton is involved in tissue barrier integrity and anti-infective responses. SEPT7 is critical for maintaining SEPT complexes and for sensing pathogenic microbes. In the lungs, SEPT7 may be involved in the epithelial barrier resistance to infection; however, its role in cystic fibrosis (CF) P. aeruginosa infection is unknown. This study aimed to investigate the role of SEPT7 in controlling P. aeruginosa infection in bronchial epithelial cells, particularly in CF. The study findings showed that SEPT7 encages P. aeruginosa in bronchial epithelial cells and its inhibition downregulates the expression of other SEPTs. In addition, P. aeruginosa does not regulate SEPT7 expression. Finally, we found that inhibiting SEPT7 expression in bronchial epithelial cells (BEAS-2B 16HBE14o- and primary cells) resulted in higher levels of internalized P. aeruginosa and decreased IL-6 production during infection, suggesting a crucial role of SEPT7 in the host response against this bacterium. However, these effects were not observed in the CF cells (16HBE14o-/F508del and primary cells) which may explain the persistence of infection in pwCF. The study findings suggest the modification of SEPT7 expression as a potential approach for the anti-infective control of P. aeruginosa, particularly in CF.

Airway infections as a risk factor for Pseudomonas aeruginosa acquisition and chronic colonisation in children with cystic fibrosis.

BACKGROUND: Pseudomonas aeruginosa (Pa) infection is detrimental to people with cystic fibrosis (pwCF). Several clinical and genetic factors predispose to early Pa infections. However, the role of earlier infections with other pathogens on the risk of Pa infection in paediatric pwCF remains unknown. METHODS: Using Kaplan-Meier method, we computed the cumulative incidences of bacterial and fungal initial acquisition (IA) and chronic colonisation (CC) in 1,231 French pwCF under 18 years of age for methicillin-susceptible and resistant Staphylococcus aureus (MSSA and MRSA), Stenotrophomonas maltophilia, Haemophilus influenzae, Achromobacter xylosoxidans, and Aspergillus species. Previous infections were analysed as Pa-IA and Pa-CC risk factors using Cox regression models. RESULTS: By 2 years of age, 65.5% pwCF had experienced at least one bacterial or fungal IA, and 27.9% had experienced at least one CC. The median age of Pa-IA was 5.1 years, and Pa-CC was present in 25% pwCF by 14.7 years. While 50% acquired MSSA at 2.1 years, 50% progressed to chronic MSSA colonisation at 8.4 years. At 7.9 and 9.7 years, 25% pwCF were infected by S. maltophilia and Aspergillus spp., respectively. The risk of Pa-IA and Pa-CC increased with IAs of all other species, with hazard ratios (HR) up to 2.19 (95% Confidence interval (CI) 1.18-4.07). The risk of Pa-IA increased with the number of previous bacterial/fungal IAs (HR=1.89, 95% CI 1.57-2.28), with a 16% increase per additional pathogen; same trend was noted for Pa-CC. CONCLUSIONS: This study establishes that the microbial community in CF airways can modulate Pa occurrence. At the dawn of targeted therapies, it paves the way for characterizing future trends and evolution of infections.

Immune Response in Cystic Fibrosis: Interplay between the Host and Microbes.

Cystic fibrosis (CF) is a rare genetic disease caused by genetic variants of the cystic fibrosis transmembrane conductance regulator (CFTR) [...].

Effect of Flagellin Pre-Exposure on the Inflammatory and Antifungal Response of Bronchial Epithelial Cells to Fungal Pathogens.

Bronchial epithelial cells (BEC) play a crucial role in innate immunity against inhaled fungi. Indeed, in response to microorganisms, BEC synthesize proinflammatory cytokines involved in the recruitment of neutrophils. We have recently shown that BEC exert antifungal activity against Aspergillus fumigatus by inhibiting filament growth. In the present study, we first analyzed the inflammatory and antifungal responses of BEC infected by several fungal species such as Aspergillus spp., Scedosporium apiospermum and Candida albicans, which are frequently isolated from the sputum of people with chronic pulmonary diseases. The airways of these patients, such as people with cystic fibrosis (pwCF), are mainly colonized by P. aeruginosa and secondary by fungal pathogens. We have previously demonstrated that BEC are capable of innate immune memory, allowing them to increase their inflammatory response against A. fumigatus following a previous contact with Pseudomonas aeruginosa flagellin. To identify the impact of bacteria exposure on BEC responses to other fungal infections, we extended the analysis of BEC innate immune memory to Aspergillus spp., Scedosporium apiospermum and Candida albicans infection. Our results show that BEC are able to recognize and respond to Aspergillus spp., S. apiospermum and C. albicans infection and that the modulation of BEC responses by pre-exposure to flagellin varies according to the fungal species encountered. Deepening our knowledge of the innate immune memory of BEC should open new therapeutic avenues to modulate the inflammatory response against polymicrobial infections observed in chronic pulmonary diseases such as CF.

Modifier Factors of Cystic Fibrosis Phenotypes: A Focus on Modifier Genes.

Although cystic fibrosis (CF) is recognized as a monogenic disease, due to variants within the CFTR (Cystic Fibrosis Transmembrane Regulator) gene, an extreme clinical heterogeneity is described among people with CF (pwCF). Apart from the exocrine pancreatic status, most studies agree that there is little association between CFTR variants and disease phenotypes. Environmental factors have been shown to contribute to this heterogeneity, accounting for almost 50% of the variability of the lung function of pwCF. Nevertheless, pwCF with similar CFTR variants and sharing the same environment (such as in siblings) may have highly variable clinical manifestations not explained by CFTR variants, and only partly explained by environmental factors. It is recognized that genetic variants located outside the CFTR locus, named "modifier genes", influence the clinical expression of the disease. This short review discusses the latest studies that have described modifier factors associated with the various CF phenotypes as well as the response to the recent CFTR modulator therapies.

Secretory phospholipase A2 expression and activity in preterm clinical chorioamnionitis with fetal involvement.

Secretory phospholipase A2 (sPLA2) regulates the first step of inflammatory cascade and is involved in several pathological processes. sPLA2 also plays a role in preterm labor and parturition, since they are triggered by inflammatory mediators such as prostaglandins. Interestingly, chorioamnionitis (i.e., the presence of intrauterine inflammation) is also often associated with preterm birth. We aimed to verify if chorioamnionitis with fetal involvement modifies sPLA2 activity and expression profile in mothers and neonates delivered prematurely. We collected maternal plasma and amniotic fluid, as well as bronchoalveolar lavage fluid from preterm neonates born to mothers with or without clinical chorioamnionitis with fetal involvement. We measured concentrations of sPLA2 subtype-IIA and -IB, total enzyme activity, and proteins. Urea ratio was used to obtain epithelial lining fluid concentrations. Enzyme activity measured in maternal plasma (P < 0.001) and amniotic fluid (P < 0.001) was higher in chorioamnionitis cases than in controls. This was mainly due to the increased production of sPLA2-IIA, as the subtype -IB was present in a smaller amount and was similar between the two groups; sPLA2-IIA was increased in epithelial lining fluid (P = 0.045) or increased, although without statistical significance, in maternal plasma (P = 0.06) and amniotic fluid (P = 0.08) of chorioamnionitis cases. Cytokines that are known to increase sPLA2-IIA expression (TNF-α and IL-1ß) or whose expression was increased by sPLA2-IIA (IL-8) were higher in histologically confirmed chorioamnionitis [TNF-α (P = 0.028), IL-1ß (P < 0.001), and IL-8 (P = 0.038)]. These data represent the basis for future studies on sPLA2-IIA inhibition to prevent deleterious consequences of chorioamnionitis and preterm birth.

SLC6A14 Impacts Cystic Fibrosis Lung Disease Severity via mTOR and Epithelial Repair Modulation.

Cystic fibrosis (CF), due to pathogenic variants in CFTR gene, is associated with chronic infection/inflammation responsible for airway epithelium alteration and lung function decline. Modifier genes induce phenotype variability between people with CF (pwCF) carrying the same CFTR variants. Among these, the gene encoding for the amino acid transporter SLC6A14 has been associated with lung disease severity and age of primary airway infection by the bacteria Pseudomonas aeruginosa. In this study, we investigated whether the single nucleotide polymorphism (SNP) rs3788766, located within SLC6A14 promoter, is associated with lung disease severity in a large French cohort of pwCF. We also studied the consequences of this SNP on SLC6A14 promoter activity using a luciferase reporter and the role of SLC6A14 in the mechanistic target of rapamycin kinase (mTOR) signaling pathway and airway epithelial repair. We confirm that SLC6A14 rs3788766 SNP is associated with lung disease severity in pwCF (p = 0.020; n = 3,257, pancreatic insufficient, aged 6-40 years old), with the minor allele G being deleterious. In bronchial epithelial cell lines deficient for CFTR, SLC6A14 promoter activity is reduced in the presence of the rs3788766 G allele. SLC6A14 inhibition with a specific pharmacological blocker reduced 3H-arginine transport, mTOR phosphorylation, and bronchial epithelial repair rates in wound healing assays. To conclude, our study highlights that SLC6A14 genotype might affect lung disease severity of people with cystic fibrosis via mTOR and epithelial repair mechanism modulation in the lung.

Factors Predisposing the Response to Lumacaftor/Ivacaftor in People with Cystic Fibrosis.

Lumacaftor/ivacaftor (LUMA-IVA) therapy is prescribed to people with cystic fibrosis (pwCF) homozygous for the Phe508del-CFTR variant to restore CFTR protein function. There is, however, large inter-individual variability in treatment response. Here, we seek to identify clinical and/or genetic factors that may modulate the response to this CFTR modulator therapy. A total of 765 pwCF older than 12 years under LUMA-IVA therapy and with lung function and nutritional measurements available before and after treatment initiation were included. Response to treatment was determined by the change in lung function and nutritional status, from baseline and over the first two years after initiation, and it was assessed by weighted generalized estimating equation models. Gains in lung function and nutritional status were observed after 6 months of treatment (on average 2.11 ± 7.81% for percent predicted FEV1 and 0.44 ± 0.77 kg/m2 for BMI) and sustained over the 2 years. We observed that the more severe patients gained the most in lung function and nutritional status. While females started with a nutritional status more impaired than males, they had a larger response and regained BMI Z-score values similar to men after 2 years of treatment. We observed no association between variants in solute carrier (SLC) genes and the respiratory function response to LUMA-IVA, but the SLC6A14 rs12839137 variant was associated with the nutritional response. Further investigations, including other genomic regions, will be needed to fully explore the inter-individual variability of the response to LUMA-IVA.

Risk factors for Pseudomonas aeruginosa airway infection and lung function decline in children with cystic fibrosis.

Background Cystic fibrosis (CF) lung disease is characterised by recurrent Pseudomonas aeruginosa (Pa) infections, leading to structural lung damage and decreased survival. The epidemiology of Pa infection and its impact on lung function in people with CF (pwCF), especially in recent birth cohorts, remain uncertain. Methods We included 1,231 French pwCF under 18 years of age. Age at initial acquisition (Pa-IA), chronic colonisation (Pa-CC), and duration from Pa-IA to Pa-CC were estimated using the Kaplan-Meier method. Demographic, clinical, and genetic characteristics were analysed as risk factors for Pa infection using Cox regression models. Lung function decline was assessed by modelling percent-predicted forced expiratory volume in 1 s (ppFEV1) before Pa infection, after Pa-IA, and after Pa-CC. Results Among the 1,231 pwCF, 50% had Pa-IA by the age of 5.1 years [95% confidence interval (CI) 3.8-6.2] and 25% had Pa-CC by the age of 14.7 years (95% CI 12.1 to ∞). We observed that CF-related diabetes and liver disease were risk factors for Pa, while gender, CFTR variants, and CF centre size were not. Genetic variants of TNF, DCTN4, SLC9A3, and CAV2 were confirmed to be associated with Pa. The annual rate of ppFEV1 decline before Pa was -0.38% predicted/year (95% CI -0.59 to -0.18), which decreased significantly after Pa-IA to -0.93% predicted/year (95% CI -1.14 to -0.71) and after Pa-CC to -1.51% predicted/year (95% CI -1.86 to -1.16). Conclusions We identified and replicated several risk factors associated with Pa infection and showed its deleterious impact on lung function in young pwCF. This large-scale study confirmed that Pa airway infection is a major determinant of lung disease severity.

Flagellin From Pseudomonas aeruginosa Modulates SARS-CoV-2 Infectivity in Cystic Fibrosis Airway Epithelial Cells by Increasing TMPRSS2 Expression.

In the coronavirus disease 2019 (COVID-19) health crisis, one major challenge is to identify the susceptibility factors of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) in order to adapt the recommendations for populations, as well as to reduce the risk of COVID-19 development in the most vulnerable people, especially patients with chronic respiratory diseases such as cystic fibrosis (CF). Airway epithelial cells (AECs) play a critical role in the modulation of both immune responses and COVID-19 severity. SARS-CoV-2 infects the airway through the receptor angiotensin-converting enzyme 2, and a host protease, transmembrane serine protease 2 (TMPRSS2), plays a major role in SARS-CoV-2 infectivity. Here, we show that Pseudomonas aeruginosa increases TMPRSS2 expression, notably in primary AECs with deficiency of the ion channel CF transmembrane conductance regulator (CFTR). Further, we show that the main component of P. aeruginosa flagella, the protein flagellin, increases TMPRSS2 expression in primary AECs and Calu-3 cells, through activation of Toll-like receptor-5 and p38 MAPK. This increase is particularly seen in Calu-3 cells deficient for CFTR and is associated with an intracellular increased level of SARS-CoV-2 infection, however, with no effect on the amount of virus particles released. Considering the urgency of the COVID-19 health crisis, this result may be of clinical significance for CF patients, who are frequently infected with and colonized by P. aeruginosa during the course of CF and might develop COVID-19.

First Wave of COVID-19 in French Patients with Cystic Fibrosis.

Viral infections are known to lead to serious respiratory complications in cystic fibrosis (CF) patients. Hypothesizing that CF patients were a population at high risk for severe respiratory complications from SARS-CoV-2 infection, we conducted a national study to describe the clinical expression of COVID-19 in French CF patients. This prospective observational study involves all 47 French CF centers caring for approximately 7500 CF patients. Between March 1st and June 30th 2020, 31 patients were diagnosed with COVID-19: 19 had positive SARS-CoV-2 RT-PCR in nasopharyngeal swabs; 1 had negative RT-PCR but typical COVID-19 signs on a CT scan; and 11 had positive SARS-CoV-2 serology. Fifteen were males, median (range) age was 31 (9-60) years, and 12 patients were living with a lung transplant. The majority of the patients had CF-related diabetes (n = 19, 61.3%), and a mild lung disease (n = 19, 65%, with percent-predicted forced expiratory volume in 1 s (ppFEV1) > 70). Three (10%) patients remained asymptomatic. For the 28 (90%) patients who displayed symptoms, most common symptoms at admission were fever (n = 22, 78.6%), fatigue (n = 14, 50%), and increased cough (n = 14, 50%). Nineteen were hospitalized (including 11 out of the 12 post-lung transplant patients), seven required oxygen therapy, and four (3 post-lung transplant patients) were admitted to an Intensive Care Unit (ICU). Ten developed complications (including acute respiratory distress syndrome in two post-lung transplant patients), but all recovered and were discharged home without noticeable short-term sequelae. Overall, French CF patients were rarely diagnosed with COVID-19. Further research should establish whether they were not infected or remained asymptomatic upon infection. In diagnosed cases, the short-term evolution was favorable with rare acute respiratory distress syndrome and no death. Post-lung transplant patients had more severe outcomes and should be monitored more closely.

Innate Immune Signaling and Proteolytic Pathways in the Resolution or Exacerbation of SARS-CoV-2 in Covid-19: Key Therapeutic Targets?

COVID-19 is caused by the Severe Acute Respiratory Syndrome (SARS) coronavirus (Cov)-2, an enveloped virus with a positive-polarity, single-stranded RNA genome. The initial outbreak of the pandemic began in December 2019, and it is affecting the human health of the global community. In common with previous pandemics (Influenza H1N1 and SARS-CoV) and the epidemics of Middle east respiratory syndrome (MERS)-CoV, CoVs target bronchial and alveolar epithelial cells. Virus protein ligands (e.g., haemagglutinin or trimeric spike glycoprotein for Influenza and CoV, respectively) interact with cellular receptors, such as (depending on the virus) either sialic acids, Dipeptidyl peptidase 4 (DPP4), or angiotensin-converting enzyme 2 (ACE2). Host proteases, e.g., cathepsins, furin, or members of the type II transmembrane serine proteases (TTSP) family, such as Transmembrane protease serine 2 (TMPRSS2), are involved in virus entry by proteolytically activating virus ligands. Also involved are Toll Like Receptor (TLR) family members, which upregulate anti-viral and pro-inflammatory mediators [interleukin (IL)-6 and IL-8 and type I and type III Interferons among others], through the activation of Nuclear Factor (NF)-kB. When these events (virus cellular entry and innate immune responses) are uncontrolled, a deleterious systemic response is sometimes encountered in infected patients, leading to the well-described "cytokine storm" and an ensuing multiple organ failure promoted by a downregulation of dendritic cell, macrophage, and T-cell function. We aim to describe how the lung and systemic host innate immune responses affect survival either positively, through downregulating initial viral load, or negatively, by triggering uncontrolled inflammation. An emphasis will be put on host cellular signaling pathways and proteases involved with a view on tackling these therapeutically.

Bronchial Epithelial Cells on the Front Line to Fight Lung Infection-Causing Aspergillus fumigatus.

Aspergillus fumigatus is an environmental filamentous fungus that can be pathogenic for humans, wherein it is responsible for a large variety of clinical forms ranging from allergic diseases to life-threatening disseminated infections. The contamination occurs by inhalation of conidia present in the air, and the first encounter of this fungus in the human host is most likely with the bronchial epithelial cells. Although alveolar macrophages have been widely studied in the Aspergillus-lung interaction, increasing evidence suggests that bronchial epithelium plays a key role in responding to the fungus. This review focuses on the innate immune response of the bronchial epithelial cells against A. fumigatus, the predominant pathogenic species. We have also detailed the molecular interactants and the effects of the different modes of interaction between these cells and the fungus.

Update on SLC6A14 in lung and gastrointestinal physiology and physiopathology: focus on cystic fibrosis.

The solute carrier family 6 member 14 (SLC6A14) protein imports and concentrates all neutral amino acids as well as the two cationic acids lysine and arginine into the cytoplasm of different cell types. Primarily described as involved in several cancer and colonic diseases physiopathological mechanisms, the SLC6A14 gene has been more recently identified as a genetic modifier of cystic fibrosis (CF) disease severity. It was indeed shown to have a pleiotropic effect, modulating meconium ileus occurrence, lung disease severity, and precocity of P. aeruginosa airway infection. The biological mechanisms explaining the impact of SLC6A14 on intestinal and lung phenotypes of CF patients are starting to be elucidated. This review focuses on SLC6A14 in lung and gastrointestinal physiology and physiopathology, especially its involvement in the pathophysiology of CF disease.

Cigarette smoke and electronic cigarettes differentially activate bronchial epithelial cells.

BACKGROUND: The use of electronic cigarettes (ECIGs) is increasing, but the impact of ECIG-vapor on cellular processes like inflammation or host defense are less understood. The aim of the present study was to compare the acute effects of traditional cigarettes (TCIGs) and ECIG-exposure on host defense, inflammation, and cellular activation of cell lines and primary differentiated human airway epithelial cells (pHBE). METHODS: We exposed pHBEs and several cell lines to TCIG-smoke or ECIG-vapor. Epithelial host defense and barrier integrity were determined. The transcriptome of airway epithelial cells was compared by gene expression array analysis. Gene interaction networks were constructed and differential gene expression over all groups analyzed. The expression of several candidate genes was validated by qRT-PCR. RESULTS: Bacterial killing, barrier integrity and the expression of antimicrobial peptides were not affected by ECIG-vapor compared to control samples. In contrast, TCIGs negatively affected host defense and reduced barrier integrity in a significant way. Furthermore ECIG-exposure significantly induced IL-8 secretion from Calu-3 cells but had no effect on NCI-H292 or primary cells. The gene expression based on array analysis distinguished TCIG-exposed cells from ECIG and room air-exposed samples. CONCLUSION: The transcriptome patterns of host defense and inflammatory genes are significantly distinct between ECIG-exposed and TCIG-treated cells. The overall effects of ECIGs on epithelial cells are less in comparison to TCIG, and ECIG-vapor does not affect host defense. Nevertheless, although acute exposure to ECIG-vapor induces inflammation, and the expression of S100 proteins, long term in vivo data is needed to evaluate the chronic effects of ECIG use.

Two-hybrid screening of FAM13A protein partners in lung epithelial cells.

OBJECTIVES: Family with sequence similarity 13 member A (FAM13A) genetic variants have been associated with several chronic respiratory diseases including chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF) and lung cancer. The FAM13A protein includes a RhoGTPase activating protein (RhoGAP) domain known to participate in various cellular mechanisms including cell proliferation. While intensive genomic studies have been performed to reveal its involvement in lung diseases, the biological role of FAM13A protein is still not completely elucidated. RESULTS: We therefore performed a two-hybrid screening to identify protein partners of FAM13A using a human lung cancer cDNA library. We identified several protein partners with a high confidence score. Researchers in the field of chronic lung diseases may benefit from this two-hybrid screening data which may reveal new research pathways to decipher.

Genetic Modifiers of Cystic Fibrosis-Related Diabetes Have Extensive Overlap With Type 2 Diabetes and Related Traits.

CONTEXT: Individuals with cystic fibrosis (CF) develop a distinct form of diabetes characterized by ß-cell dysfunction and islet amyloid accumulation similar to type 2 diabetes (T2D), but generally have normal insulin sensitivity. CF-related diabetes (CFRD) risk is determined by both CFTR, the gene responsible for CF, and other genetic variants. OBJECTIVE: To identify genetic modifiers of CFRD and determine the genetic overlap with other types of diabetes. DESIGN AND PATIENTS: A genome-wide association study was conducted for CFRD onset on 5740 individuals with CF. Weighted polygenic risk scores (PRSs) for type 1 diabetes (T1D), T2D, and diabetes endophenotypes were tested for association with CFRD. RESULTS: Genome-wide significance was obtained for variants at a novel locus (PTMA) and 2 known CFRD genetic modifiers (TCF7L2 and SLC26A9). PTMA and SLC26A9 variants were CF-specific; TCF7L2 variants also associated with T2D. CFRD was strongly associated with PRSs for T2D, insulin secretion, postchallenge glucose concentration, and fasting plasma glucose, and less strongly with T1D PRSs. CFRD was inconsistently associated with PRSs for insulin sensitivity and was not associated with a PRS for islet autoimmunity. A CFRD PRS comprising variants selected from these PRSs (with a false discovery rate < 0.1) and the genome-wide significant variants was associated with CFRD in a replication population. CONCLUSIONS: CFRD and T2D have more etiologic and mechanistic overlap than previously known, aligning along pathways involving ß-cell function rather than insulin sensitivity. Two CFRD risk loci are unrelated to T2D and may affect multiple aspects of CF. An 18-variant PRS stratifies risk of CFRD in an independent population.

Respiratory Epithelial Cells Can Remember Infection: A Proof-of-Concept Study.

Human bronchial epithelial cells play a key role in airway immune homeostasis. We hypothesized that these sentinel cells can remember a previous contact with pathogen compounds and respond nonspecifically to reinfection, a phenomenon called innate immune memory. We demonstrated that their preexposure to Pseudomonas aeruginosa flagellin modify their inflammatory response to a second, nonrelated stimulus, including live pathogens or lipopolysaccharide. Using histone acetyltransferase and methyltransferase inhibitors, we showed that this phenomenon relied on epigenetic regulation. This report is a major breakthrough in the field of multimicrobial respiratory tract infections, wherein control of inflammatory exacerbations is a major therapeutic issue.

SERPINA1 Z allele is associated with cystic fibrosis liver disease.

PURPOSE: The SERPINA1 Z allele is associated with cystic fibrosis (CF)-related liver disease (CFLD), a common manifestation in patients with CF. We estimated CFLD incidence based on the SERPINA1 genotype in 3328 CF patients with CFLD-phenotype information. METHODS: The associations of SERPINA1 Z (rs28929474) and S (rs17580) alleles with age at CFLD onset and the development of CFLD-related complications (severe liver disease with cirrhosis, portal hypertension, esophageal varices) were analyzed. RESULTS: Overall, 3% of patients carried the SERPINA1 Z allele and 13% carried the S allele. The cumulative incidence of CFLD increased more rapidly in patients carrying the Z allele (hazard ratio [HR] = 1.6; 95% confidence interval [CI] = 1.1-2.4, P = 0.019), reaching 47% by age 25 compared with 30% in noncarriers. Increased risk was similar for patients with severe CFLD (HR = 1.5, 95% CI = 0.7-3.2, P = 0.31) but failed to reach significance due to a limited sample size of Z-allele carriers. No significant effect was found for the S allele. CONCLUSION: CF patients carrying the SERPINA1 Z allele had an increased risk of developing CFLD and related complications compared with noncarriers. Routine SERPINA1 Z genotyping upon CF diagnosis is warranted for identifying patients worthy of closer liver disease monitoring.