Laurence Bassinet

Role of Adhesins and Toxins in Invasion of Human Tracheal Epithelial Cells by Bordetella pertussis

ABSTRACT Bordetella pertussis, the agent of whooping cough, can invade and survive in several types of eukaryotic cell, including CHO, HeLa 229, and HEp-2 cells and macrophages. In this study, we analyzed bacterial invasiveness in nonrespiratory human HeLa epithelial cells and human HTE and HAE0 tracheal epithelial cells. Invasion assays and transmission electron microscopy analysis showed that B. pertussis strains invaded and survived, without multiplying, in HTE or HAE0 cells. This phenomenon was bvg regulated, but invasive properties differed between B. pertussis strains and isolates and the B. pertussis reference strain. Studies with B. pertussis mutant strains demonstrated that filamentous hemagglutinin, the major adhesin, was involved in the invasion of human tracheal epithelial cells by bacteria but not in that of HeLa cells. Fimbriae and pertussis toxin were not found to be involved. However, we found that the production of adenylate cyclase-hemolysin prevents the invasion of HeLa and HTE cells byB. pertussis because an adenylate cyclase-hemolysin-deficient mutant was found to be more invasive than the parental strain. The effect of adenylate cyclase-hemolysin was mediated by an increase in the cyclic AMP concentration in the cells. Pertactin (PRN), an adhesin, significantly inhibited the invasion of HTE cells by bacteria, probably via its interaction with adenylate cyclase-hemolysin. Isolates producing different PRNs were taken up similarly, indicating that the differences in the sequences of the PRNs produced by these isolates do not affect invasion. We concluded that filamentous hemagglutinin production favored invasion of human tracheal cells but that adenylate cyclase-hemolysin and PRN production significantly inhibited this process.

Loss-of-Function Mutations in RSPH1 Cause Primary Ciliary Dyskinesia with Central-Complex and Radial-Spoke Defects

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive respiratory disorder resulting from defects of motile cilia. Various axonemal ultrastructural phenotypes have been observed, including one with so-called central-complex (CC) defects, whose molecular basis remains unexplained in most cases. To identify genes involved in this phenotype, whose diagnosis can be particularly difficult to establish, we combined homozygosity mapping and whole-exome sequencing in a consanguineous individual with CC defects. This identified a nonsense mutation in RSPH1, a gene whose ortholog in Chlamydomonas reinhardtii encodes a radial-spoke (RS)-head protein and is mainly expressed in respiratory and testis cells. Subsequent analyses of RSPH1 identified biallelic mutations in 10 of 48 independent families affected by CC defects. These mutations include splicing defects, as demonstrated by the study of RSPH1 transcripts obtained from airway cells of affected individuals. Wild-type RSPH1 localizes within cilia of airway cells, but we were unable to detect it in an individual with RSPH1 loss-of-function mutations. High-speed-videomicroscopy analyses revealed the coexistence of different ciliary beating patterns-cilia with a normal beat frequency but abnormal motion alongside immotile cilia or cilia with a slowed beat frequency-in each individual. This study shows that this gene is mutated in 20.8% of individuals with CC defects, whose diagnosis could now be improved by molecular screening. RSPH1 mutations thus appear as a major etiology for this PCD phenotype, which in fact includes RS defects, thereby unveiling the importance of RSPH1 in the proper building of CCs and RSs in humans.

Mutations in the Amiloride-Sensitive Epithelial Sodium Channel in Patients With Cystic Fibrosis-Like Disease

We investigated whether mutations in the genes that code for the different subunits of the amiloride‐sensitive epithelial sodium channel (ENaC) might result in cystic fibrosis (CF)‐like disease. In a small fraction of the patients, the disease could be potentially explained by an ENaC mutation by a Mendelian mechanism, such as p.V114I and p.F61L in SCNN1A. More importantly, a more than three‐fold significant increase in incidence of several rare ENaC polymorphisms was found in the patient group (30% vs. 9% in controls), indicating an involvement of ENaC in some patients by a polygenetic mechanism. Specifically, a significantly higher number of patients carried c.–55+5G>C or p.W493R in SCNN1A in the heterozygous state, with odds ratios (ORs) of 13.5 and 2.7, respectively.The p.W493R‐SCNN1A polymorphism was even found to result in a four‐fold more active ENaC channel when heterologously expressed in Xenopus laevis oocytes. About 1 in 975 individuals in the general population will be heterozygous for the hyperactive p.W493R‐SCNN1A mutation and a cystic fibrosis transmembrane conductance regulator (CFTR) gene that results in very low amounts (0–10%) functional CFTR. These ENaC/CFTR genotypes may play a hitherto unrecognized role in lung diseases. Hum Mutat 30:1–11, 2009.

Health and economic consequences of an outbreak of pertussis among healthcare workers in a hospital in France

BACKGROUND Bordetella pertussis is highly contagious, and because immunity wanes after vaccination, it continues to be a cause of cough among adults. OBJECTIVE To describe the healthcare services used and productivity losses accrued by healthcare workers (HCWs) missing work due to pertussis. METHODS After 3 pertussis cases were confirmed among HCWs, all hospital employees and patients with a cough were screened between November 2000 and March 2001. Each potential case underwent diagnostic tests and received antibiotics (spiramycin or azithromycin) when appropriate. Symptomatic employees were not allowed to return to work until they received an antibiotic for at least 5 days. Services used (physician visits and calls, antibiotics, diagnostic tests, hospitalization, and treatment provided to their contacts) were combined with cost estimates (in 2002 euros) for these services in France. RESULTS Ninety-one potential cases were identified (77 HCWs, 12 patients, and 2 family members). Of them, 89% received antibiotics and 22% had at least one contact who was also treated. Approximately half (55%) of the HCWs who were cases missed 5 days of work. Four patients were admitted to the hospital as a result of the infection. The average medical cost was 297 euros per potential case: diagnostic tests accounted for 32% and hospitalization for 31%. Total cost (medical and productivity) was 46,661 euros for 91 cases, 42% from productivity losses. An investigation to identify these potential cases also accrued additional costs. CONCLUSION Serious adverse health and economic consequences arose from transmission of pertussis among HCWs, their families, and patients.

Nosocomial Pertussis Outbreak Among Adult Patients and Healthcare Workers

We describe a pertussis outbreak among adult patients in a French general hospital following transmission from a healthcare worker. This index case transmitted pertussis to other healthcare workers, who, in turn, contaminated other staff and two immunosuppressed patients. This raises questions about infection control.

Cystic Fibrosis Transmembrane Conductance Regulator Channel Dysfunction in Non–Cystic Fibrosis Bronchiectasis

RATIONALE Although in patients with diffuse bronchiectasis (DB) and a normal sweat test the presence of one mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is frequently observed, its pathogenic role in the development of DB remains unclear. OBJECTIVES To evaluate the association between CFTR heterozygosity and CFTR protein dysfunction in the airways of patients with DB. METHODS Nasal potential difference was measured in 122 patients with DB of unknown origin and with a normal sweat test (Cl(-) < 60 mmol/L). They were classified according to the presence of CFTR mutations: zero (85 patients), one (22 patients), or two mutations (15 patients). Control groups comprised 26 healthy subjects, 38 obligate heterozygotes for CFTR, and 92 patients with classic cystic fibrosis (CF) with an abnormal sweat test (Cl(-) > or = 60 mmol/L). Patients classified as mild-CF were carrying at least one mild mutation and patients classified as severe-CF were homozygous for the F508del mutation. MEASUREMENTS AND MAIN RESULTS There was a continuum of airway CFTR dysfunction in the study population as shown by nasal potential difference measurements, ranging from normal values in healthy subjects, to intermediate values in subjects with DB, to highly abnormal values in subjects classified as severe-CF. This continuum of airway CFTR dysfunction was thus strongly associated with defects in the CFTR gene. Moreover, among patients with DB, a similar continuum in intermediate nasal potential difference was identified that was associated with the bearing of zero, one, or two CFTR mutations. These electrophysiological phenotypes and CFTR genotypes were also associated with the clinical phenotype, as shown by the frequency of Staphylococcus aureus and Pseudomonas aeruginosa bronchial colonization. CONCLUSIONS Our study supports the hypothesis that a unique CFTR mutation may have pathogenic consequences in patients with DB.

Quantitative analysis of ciliary beating in primary ciliary dyskinesia: a pilot study

BackgroundPrimary ciliary dyskinesia (PCD) is a rare congenital respiratory disorder characterized by abnormal ciliary motility leading to chronic airway infections. Qualitative evaluation of ciliary beat pattern based on digital high-speed videomicroscopy analysis has been proposed in the diagnosis process of PCD. Although this evaluation is easy in typical cases, it becomes difficult when ciliary beating is partially maintained. We postulated that a quantitative analysis of beat pattern would improve PCD diagnosis. We compared quantitative parameters with the qualitative evaluation of ciliary beat pattern in patients in whom the diagnosis of PCD was confirmed or excluded.MethodsNasal nitric oxide measurement, nasal brushings and biopsies were performed prospectively in 34 patients with suspected PCD. In combination with qualitative analysis, 12 quantitative parameters of ciliary beat pattern were determined on high-speed videomicroscopy recordings of beating ciliated edges. The combination of ciliary ultrastructural abnormalities on transmission electron microscopy analysis with low nasal nitric oxide levels was the “gold standard” used to establish the diagnosis of PCD.ResultsThis “gold standard” excluded PCD in 15 patients (non-PCD patients), confirmed PCD in 10 patients (PCD patients) and was inconclusive in 9 patients. Among the 12 parameters, the distance traveled by the cilium tip weighted by the percentage of beating ciliated edges presented 96% sensitivity and 95% specificity. Qualitative evaluation and quantitative analysis were concordant in non-PCD patients. In 9/10 PCD patients, quantitative analysis was concordant with the “gold standard”, while the qualitative evaluation was discordant with the “gold standard” in 3/10 cases. Among the patients with an inconclusive “gold standard”, the use of quantitative parameters supported PCD diagnosis in 4/9 patients (confirmed by the identification of disease-causing mutations in one patient) and PCD exclusion in 2/9 patients.ConclusionsWhen the beat pattern is normal or virtually immotile, the qualitative evaluation is adequate to study ciliary beating in patients suspected for PCD. However, when cilia are still beating but with moderate alterations (more than 40% of patients suspected for PCD), quantitative analysis is required to precise the diagnosis and can be proposed to select patients eligible for TEM.

Determinants of refusal of A/H1N1 pandemic vaccination in a high risk population: a qualitative approach.

Background Our study analyses the main determinants of refusal or acceptance of the 2009 A/H1N1 vaccine in patients with cystic fibrosis, a high-risk population for severe flu infection, usually very compliant for seasonal flu vaccine. Methodology/Principal Findings We conducted a qualitative study based on semi-structured interviews in 3 cystic fibrosis referral centres in Paris, France. The study included 42 patients with cystic fibrosis: 24 who refused the vaccine and 18 who were vaccinated. The two groups differed quite substantially in their perceptions of vaccine- and disease-related risks. Those who refused the vaccine were motivated mainly by the fears it aroused and did not explicitly consider the 2009 A/H1N1 flu a potentially severe disease. People who were vaccinated explained their choice, first and foremost, as intended to prevent the flus potential consequences on respiratory cystic fibrosis disease. Moreover, they considered vaccination to be an indirect collective prevention tool. Patients who refused the vaccine mentioned multiple, contradictory information sources and did not appear to consider the recommendation of their local health care provider as predominant. On the contrary, those who were vaccinated stated that they had based their decision solely on the clear and unequivocal advice of their health care provider. Conclusions/Significance These results of our survey led us to formulate three main recommendations for improving adhesion to new pandemic vaccines. (1) it appears necessary to reinforce patient education about the disease and its specific risks, but also general population information about community immunity. (2) it is essential to disseminate a clear and effective message about the safety of novel vaccines. (3) this message should be conveyed by local health care providers, who should be involved in implementing immunization.

Bordetella pertussis Adenylate Cyclase-Hemolysin Induces Interleukin-6 Secretion by Human Tracheal Epithelial Cells

ABSTRACT After interaction with tracheal epithelial cells, Bordetella pertussis induces the secretion of interleukin-6. This secretion is dependent on the expression of adenylate cyclase-hemolysin by the bacterium but not on the expression of other characterized bacterial toxins or adhesins. This finding confirms the important role of adenylate cyclase-hemolysin in the pathogenicity of the bacterium.

Real-life initiation of lumacaftor/ivacaftor combination in adults with cystic fibrosis homozygous for the Phe508del CFTR mutation and severe lung disease

OBJECTIVE To investigate the short-term adverse events and effectiveness of lumacaftor/ivacaftor combination treatment in adults with cystic fibrosis (CF) and severe lung disease in a real life setting. METHODS A multicentre observational study investigated adverse events, treatment discontinuation, FEV1 and body mass index (BMI) one month and three months after lumacaftor/ivacaftor initiation in adults with CF and FEV1 below 40% predicted. RESULTS Respiratory adverse events (AEs) were reported by 27 of 53 subjects (51%) and 16 (30%) discontinued treatment. The mean absolute change in FEV1 was +2.06% after one month of treatment (P=0.086) and +3.19% after 3 months (P=0.009). BMI was unchanged. CONCLUSIONS Treatment with lumacaftor/ivacaftor in patients with CF and severe lung disease was discontinued more frequently than reported in clinical trials, due to respiratory AEs. Nevertheless, the patients who continued treatment had an increase in lung function comparable to what was observed in pivotal trials.