Calcium stone lithoptysis in primary ciliary dyskinesia

Lower airway clinical outcome measures for use in primary ciliary dyskinesia research: a scoping review

Objectives

Disease-specific, well-defined and validated clinical outcome measures are essential in designing research studies. Poorly defined outcome measures hamper pooling of data and comparisons between studies. We aimed to identify and describe pulmonary outcome measures that could be used for follow-up of patients with primary ciliary dyskinesia (PCD).

Methods

We conducted a scoping review by systematically searching MEDLINE, Embase and the Cochrane Database of Systematic Reviews online databases for studies published from 1996 to 2020 that included ≥10 PCD adult and/or paediatric patients.

Results

We included 102 studies (7289 patients). 83 studies reported on spirometry, 11 on body plethysmography, 15 on multiple-breath washout, 36 on high-resolution computed tomography (HRCT), 57 on microbiology and 17 on health-related quality of life. Measurement and reporting of outcomes varied considerably between studies (e.g. different scoring systems for chest HRCT scans). Additionally, definitions of outcome measures varied (e.g. definition of chronic colonisation by respiratory pathogen), impeding direct comparisons of results.

Conclusions

This review highlights the need for standardisation of measurements and reporting of outcome measures to enable comparisons between studies. Defining a core set of clinical outcome measures is necessary to ensure reproducibility of results and for use in future trials and prospective cohorts.

Broncholithiasis: Treatment Evaluation in 63 Patients

BACKGROUND

Broncholithiasis is a rare disease defined as the presence of calcified material (broncholith) within the tracheobronchial tree. We described our experience in broncholithiasis to provide a more effective clinical basis for the management of this condition.

METHODS

We retrospectively reviewed the clinical characteristics, treatments, and outcomes of patients with broncholithiasis at Xiangya Hospital in China from May 2009 to November 2019.

RESULTS

Sixty-three patients were enrolled in this study with a median age of 57 years. Cough (57.1%) was the most common symptom of broncholithiasis, followed by hemoptysis (23.8%). Tuberculosis was the most common comorbidity (38%), while 21 patients (30.0%) did not exhibit underlying diseases. Broncholiths within the bronchus led to airway dilation (19.0%), obstructive atelectasis (46.0%), and pneumonia (30.2%). The condition of most patients improved after undergoing endoscopic removal (76.5%) of the broncholiths. The condition of three patients (100%) improved after the surgical removal of the broncholiths. Of the 38 patients (60.3%) who failed to receive removal of broncholiths, 16 received anti-infection treatment, and the other 22 received observation. Most patients (50.0%) who were treated with anti-infectives showed an improvement, whereas the condition of 33.3% of patients who did not receive treatment worsened.

CONCLUSION

Broncholithiasis is a benign bronchial disease that can cause complications. Endoscopic removal of broncholiths is considered as initial therapy and surgical removal is suggested as a second-line treatment. Treatment with anti-infectives is required for patients who fail to receive removal of broncholiths.

Pseudomonas aeruginosa β-carbonic anhydrase, psCA1, is required for calcium deposition and contributes to virulence

Calcification of soft tissue leads to serious diseases and has been associated with bacterial chronic infections. However, the origin and the molecular mechanisms of calcification remain unclear. Here we hypothesized that a human pathogen Pseudomonas aeruginosa deposits extracellular calcium, a process requiring carbonic anhydrases (CAs). Transmission electron microscopy confirmed the formation of 0.1-0.2 μm deposits by P. aeruginosa PAO1 growing at 5 mM CaCl₂, and X-ray elemental analysis confirmed they contain calcium. Quantitative analysis of deposited calcium showed that PAO1 deposits 0.35 and 0.75 mM calcium/mg protein when grown at 5 mM and 10 mM CaCl₂, correspondingly. Fluorescent microscopy indicated that deposition initiates at the cell surface. We have previously characterized three PAO1 β-class CAs: psCA1, psCA2, and psCA3 that hydrate CO₂ to HCO₃^-, among which psCA1 showed the highest catalytic activity (Lotlikar et. al. 2013). According to immunoblot and RT-qPCR, growth at elevated calcium levels increases the expression of psCA1. Analyses of the deletion mutants lacking one, two or all three psCA genes, determined that psCA1 plays a major role in calcium deposition and contributes to the pathogen's virulence. In-silico modeling of the PAO1 β-class CAs identified four amino acids that differ in psCA1 compared to psCA2, and psCA3 (T59, A61A, A101, and A108), and these differences may play a role in catalytic rate and thus calcium deposition. A series of inhibitors were tested against the recombinant psCA1, among which aminobenzene sulfonamide (ABS) and acetazolamide (AAZ), which inhibited psCA1 catalytic activity with K_Is of 19 nM and 37 nM, correspondingly. The addition of ABS and AAZ to growing PAO1 reduced calcium deposition by 41 and 78, respectively. Hence, for the first time, we showed that the β-CA psCA1 in P. aeruginosa contributes to virulence likely by enabling calcium salt deposition, which can be partially controlled by inhibiting its catalytic activity.

Management of broncholithiasis

Broncholithiasis is a condition in which calcified material has entered the tracheobronchial tree, at times causing airway obstruction and inflammation. Broncholiths generally originate as calcified material in mediastinal lymph nodes that subsequently erode into adjacent airways, often as a result of prior granulomatous infection. Disease manifestations range from asymptomatic stones in the airway to life-threatening complications, including massive hemoptysis and post-obstructive pneumonia. Radiographic imaging, particularly computed tomography scanning of the chest, is integral in the evaluation of suspected broncholithiasis and can be helpful to assess involvement of adjacent structures, including vasculature, prior to any planned intervention. Management strategies largely depend on the severity of disease. Observation is warranted in asymptomatic cases, while therapeutic bronchoscopy and surgical interventions may be necessary for cases involving complications. Bronchoscopic extraction is often feasible in cases in which the broncholith is freely mobile within the airway, whereas partially-embedded broncholiths represent additional challenges. Surgical intervention is indicated for advanced cases deemed not amenable to endoscopic management. Complex cases involving complications such as massive hemoptysis and/or bronchomediastinal fistula formation are best managed with a multidisciplinary approach, utilizing expertise from fields such as pulmonology, radiology, and thoracic surgery.

In Situ Biomineralization and Particle Deposition Distinctively Mediate Biofilm Susceptibility to Chlorine

Microbial biofilms and mineral precipitation commonly co-occur in engineered water systems, such as cooling towers and water purification systems, and both decrease process performance. Microbial biofilms are extremely challenging to control and eradicate. We previously showed that in situ biomineralization and the precipitation and deposition of abiotic particles occur simultaneously in biofilms under oversaturated conditions. Both processes could potentially alter the essential properties of biofilms, including susceptibility to biocides. However, the specific interactions between mineral formation and biofilm processes remain poorly understood. Here we show that the susceptibility of biofilms to chlorination depends specifically on internal transport processes mediated by biomineralization and the accumulation of abiotic mineral deposits. Using injections of the fluorescent tracer Cy5, we show that Pseudomonas aeruginosa biofilms are more permeable to solutes after in situ calcite biomineralization and are less permeable after the deposition of abiotically precipitated calcite particles. We further show that biofilms are more susceptible to chlorine killing after biomineralization and less susceptible after particle deposition. Based on these observations, we found a strong correlation between enhanced solute transport and chlorine killing in biofilms, indicating that biomineralization and particle deposition regulate biofilm susceptibility by altering biocide penetration into the biofilm. The distinct effects of in situ biomineralization and particle deposition on biocide killing highlight the importance of understanding the mechanisms and patterns of biomineralization and scale formation to achieve successful biofilm control.

Spatial patterns of carbonate biomineralization in biofilms

Microbially catalyzed precipitation of carbonate minerals is an important process in diverse biological, geological, and engineered systems. However, the processes that regulate carbonate biomineralization and their impacts on biofilms are largely unexplored, mainly because of the inability of current methods to directly observe biomineralization within biofilms. Here, we present a method for in situ, real-time imaging of biomineralization in biofilms and use it to show that Pseudomonas aeruginosa biofilms produce morphologically distinct carbonate deposits that substantially modify biofilm structures. The patterns of carbonate biomineralization produced in situ were substantially different from those caused by accumulation of particles produced by abiotic precipitation. Contrary to the common expectation that mineral precipitation should occur at the biofilm surface, we found that biomineralization started at the base of the biofilm. The carbonate deposits grew over time, detaching biofilm-resident cells and deforming the biofilm morphology. These findings indicate that biomineralization is a general regulator of biofilm architecture and properties.

Structure and inhibition studies of a type II beta-carbonic anhydrase psCA3 from Pseudomonas aeruginosa

Carbonic anhydrases (CAs) are metallo-enzymes that catalyze the reversible hydration of carbon dioxide into bicarbonate and a proton. The β-class CAs (β-CAs) are expressed in prokaryotes, fungi, plants, and more recently have been isolated in some animals. The β-CA class is divided into two subclasses, termed type I and II, defined by pH catalytic activity profile and active site structural configuration. Type I β-CAs display catalytic activity over a broad pH range (6.5-9.0) with the active site zinc tetrahedrally coordinated by three amino acids and a hydroxide/water. In contrast, type II β-CAs are catalytically active only at a pH 8 and higher where they adopt a functional active site configuration like that of type I. However, below pH 8 they are conformationally self-inactivated by the addition of a fourth amino acid coordinating the zinc and thereby displacing the zinc bound solvent. We have determined the structure of psCA3, a type II β-CA, isolated from Pseudomonas aeruginosa (P. aeruginosa) PAO1 at pH 8.3, in its open active state to a resolution of 1.9 Å. The active site zinc is coordinated by Cys42, His98, Cys101 and a water/hydroxide molecule. P. aeruginosa is a multi-drug resistant bacterium and displays intrinsic resistance to most of the currently used antibiotics; therefore, there is a need for new antibacterial targets. Kinetic data confirm that psCA3 belongs to the type II subclass and that sulfamide, sulfamic acid, phenylboronic acid and phenylarsonic acid are micromolar inhibitors. In vivo studies identified that among six tested inhibitors representing sulfonamides, inorganic anions, and small molecules, acetazolamide has the most significant dose-dependent inhibitory effect on P. aeruginosa growth.

Cryo-electron tomography reveals ciliary defects underlying human RSPH1 primary ciliary dyskinesia

Cilia play essential roles in normal human development and health; cilia dysfunction results in diseases such as primary ciliary dyskinesia (PCD). Despite their importance, the native structure of human cilia is unknown, and structural defects in the cilia of patients are often undetectable or remain elusive because of heterogeneity. Here we develop an approach that enables visualization of human (patient) cilia at high-resolution using cryo-electron tomography of samples obtained noninvasively by nasal scrape biopsy. We present the native 3D structures of normal and PCD-causing RSPH1-mutant human respiratory cilia in unprecedented detail; this allows comparisons of cilia structure across evolutionarily distant species and reveals the previously unknown primary defect and the heterogeneous secondary defects in RSPH1-mutant cilia. Our data provide evidence for structural and functional heterogeneity in radial spokes, suggest a mechanism for the milder RSPH1 PCD phenotype and demonstrate that cryo-electron tomography can be applied to human disease by directly imaging patient samples.

Primary ciliary dyskinesia, an orphan disease

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disease, caused by specific primary structural and/or functional abnormalities of the motile cilia, in contrast with the transitory abnormalities seen in secondary ciliary dyskinesia. Disease-causing mutations in at least 16 genes have already been identified. The true incidence of PCD may be higher than currently reported, because the diagnosis is challenging and often missed. For the confirmation of PCD, both ciliary motility as well as ciliary ultrastructure must be evaluated. An early and adequate diagnosis and therapy can theoretically prevent bronchiectasis. Measurement of nasal nitric oxide has some value as a screening test but cannot be performed in young children. In the respiratory tract epithelium, impaired mucociliary clearance leads to chronic and/or recurrent upper and lower respiratory tract infections. In up to 75 % of the patients, respiratory manifestations start in the newborn period, although the diagnosis is often missed at that time. During embryogenesis, nodal cilia, which are motile cilia, determine the correct lateralization of the organs. Dysfunction of these cilia leads to random lateralization and thus situs inversus in approximately 50 % of the patients with PCD. The tail of a spermatozoon has a structure similar to that of a motile cilium. Consequently, male infertility due to immotile spermatozoa is often part of the characteristics of PCD. Given the heterogeneity and the rarity of the disorder, therapy is not evidence-based. Many treatment schedules are proposed in analogy with the treatment for cystic fibrosis.

CONCLUSION

Respiratory infections, situs inversus and male infertility are typical manifestations of PCD, a rare autosomal recessive disorder.

Early adolescent primary ciliary dyskinesia associated with broncholithiasis

Primary ciliary dyskinesia (PCD), is a rare congenital disease group, and contained Kartageners syndrome. This syndrome is characterized with situs viscerum inversus, sinusitis and bronchiectasis. In some elderly patients, broncholithiasis may be associated with PCD. The coexistence of early adolescence PCD and broncolithiasis has not been reported yet. We report here a case of a 14-year-old early adolescent male who had typically presented as PCD-based Kartageners syndrome and developed broncholithiasis which diagnosed with computed tomography.

Genetic causes of bronchiectasis: primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder reflecting abnormalities in the structure and function of motile cilia and flagella, causing impairment of mucociliary clearance, left-right body asymmetry, and sperm motility. Clinical manifestations include respiratory distress in term neonates, recurrent otosinopulmonary infections, bronchiectasis, situs inversus and/or heterotaxy, and male infertility. Genetic discoveries are emerging from family-based linkage studies and from testing candidate genes. Mutations in 2 genes, DNAI1 and DNAH5, frequently cause PCD as an autosomal recessive disorder. A clinical genetic test has been recently established for DNAI1 and DNAH5, which involves sequencing 9 exons that harbor the most common mutations. This approach will identify at least one mutation in these 2 genes in approximately 25% of PCD patients. If biallelic mutations are identified, the test is diagnostic. If only one mutation is identified, the full gene may be sequenced to search for a trans-allelic mutation. As more disease-causing gene mutations are identified, broader genetic screening panels will further identify patients with PCD. Ongoing investigations are beginning to identify genetic mutations in novel clinical phenotypes for PCD, such as congenital heart disease and male infertility, and new associations are being established between 'ciliary' genetic mutations and clinical phenotypes.

High-Resolution CT of Patients with Primary Ciliary Dyskinesia

OBJECTIVE

High-resolution CT is an important tool in the detection and management of bronchiectasis, but there is little information about high-resolution CT findings in primary ciliary dyskinesia (PCD). We analyzed all high-resolution CT studies of the chest available for a cohort of PCD patients to identify an associated pattern of high-resolution CT changes.

MATERIALS AND METHODS

High-resolution CT studies were available for 45 PCD patients from 42 families with ranges of age and disease severity. The images were assessed for severity and distribution of bronchiectasis, peribronchial thickening, mucous plugging, and other findings. A bronchiectasis severity score was calculated. CT findings were correlated with phenotypic findings, including situs type, ciliary ultrastructural defect, nasal level of nitric oxide, forced expiratory volume in 1 second, and microbiologic findings in the airways.

RESULTS

Twenty-nine adults (mean age, 42 +/- 15 years; age range, 21-73 years) and 16 children (mean age, 8 +/- 4 years; age range, 1-14 years) were included; 26 (58%) of the patients were women or girls. Situs inversus totalis (38%) or heterotaxy (18%) was identified in 56% of the patients. A high (9%) prevalence of pectus excavatum was identified. High-resolution CT of all of the adult and 56% of the pediatric patients showed bronchiectasis in a predominantly middle and lower lobe distribution. The right middle lobe was most commonly involved. Bronchiectasis severity score correlated with older age and worse pulmonary function.

CONCLUSION

High-resolution CT shows that pulmonary disease related to PCD predominantly involves the middle and lower lobes of the lungs. In adults, high-resolution CT findings negative for bronchiectasis may have a role in excluding the diagnosis of PCD. Correlation of severity of disease on high-resolution CT with patient phenotype gives further insight into the diversity and natural history of PCD.

Primary ciliary dyskinesia and upper airway diseases

Primary ciliary dyskinesia (PCD) is a rare and difficult-to-diagnose disease with morbidity related to infections of the upper and lower respiratory tract. The disease is caused by mutations in genes that are required for proper ciliary function. The defect in ciliary function results in reduced or absent mucociliary clearance, thereby predisposing the affected individual to repeated bacterial infections. Recent advances in the understanding of the basic biology and function of the cilium have led to the identification of some of the genes that are mutated in cases of PCD. Further studies of this disease will likely lead to earlier diagnosis, better treatment, and improved outcomes.