Nontuberculous mycobacteria infection and pulmonary disease in bronchiectasis

A genome-wide association study identified PRKCB as a causal gene and therapeutic target for Mycobacterium avium complex disease

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is a chronic progressive lung disease that is increasing in incidence. Host genetic factors are associated with NTM-PD susceptibility. However, the heritability of NTM-PD is not well understood. Here, we perform a two-stage genome-wide association study (GWAS) and discover a susceptibility locus at 16p21 associated with NTM-PD, especially with pulmonary Mycobacterium avium complex (MAC) disease. As the lead variant, rs194800 C allele augments protein kinase C beta (PRKCB) gene expression and associates with severer NTM-PD. The functional studies show that PRKCB exacerbates M. avium infection and promotes intracellular survival of M. avium in macrophages by inhibiting phagosomal acidification. Mechanistically, PRKCB interacts with subunit G of the vacuolar-H+-ATPase (V-ATPase) and vacuolar protein sorting-associated protein 16 homolog (VPS16), blocking the fusion between lysosomes and mycobacterial phagosomes. PRKCB inhibitor has therapeutic potential against M. avium infection. These findings provide insights into the genetic etiology of NTM-PD and highlight PRKCB as an attractive target for host-directed therapy of MAC disease.

Prescription habits and drugs accessibility for the treatment of non-tuberculous mycobacteria infections in Italy: a multicentric survey from the IRENE study group

PURPOSE

Non-tuberculous mycobacteria (NTM) account for high clinical burden, and treatment can be challenging. Moreover, accessibility of NTM medications varies across centers. These challenges may lead to unplanned therapeutic changes, discontinuations, potentially affecting patient outcomes. Aim of this survey was to evaluate the accessibility of NTM-targeting drugs in Italy (with a particular focus on clofazimine) in centers associated with the IRENE Registry, a collaborative network of healthcare professionals.

METHODS

A cross-sectional, internet-based, questionnaire-survey on the use and availability of clofazimineand other NTM-targeting drugs was sent to 88 principal investigators of the IRENE network in Italyin 2020. The questionnaires were designed with closed-ended and open-ended questions and distributed using the SurveyMonkey® platform.

RESULTS

The surveys underscore the more frequent involvement of pulmonologists (42%) and infectious disease specialists (34%) in NTM treating strategies. Respondents were distributed across 18 out of20 Italian regions, with a significant concentration in the north, encompassing university hospitalsand outpatient clinics. Molecular testing is available in 40% of the involved centers, while phenotypic in 30% of the centers. Centers have a multidisciplinary team and an appointed pharmacy service for NTM drugs distribution in 10 and 75% of the cases, respectively. Substantial variability was observed in drug availability and accessibility, drug regimen composition, and drug dosage, particularly for medications like clofazimine.

CONCLUSIONS

This study shows the high heterogeneity of anti-NTM drug availability in Italy and prompts toward a harmonization in antibiotic prescription and access; it also emphasizes the challenges in determining the optimal therapeutic strategies for treating NTM-infections.

Clinical Efficacy of Serum Antiglycopeptidolipid Core IgA Antibody Test for Screening Nontuberculous Mycobacterial Pulmonary Disease in Bronchiectasis: A European Multicenter Cohort Study

BACKGROUND

The serum antiglycopeptidolipid core IgA antibody test has been proposed as a diagnostic tool for Mycobacterium avium complex pulmonary diseases. Cross-reactivity with other nontuberculous mycobacteria (NTM), including Mycobacterium abscessus, indicates that it may have a role as a broader screening test for nontuberculous mycobacterial pulmonary disease (NTM-PD). NTM-PD is believed to be underdiagnosed in patients with bronchiectasis.

RESEARCH QUESTION

Can the serum antiglycopeptidolipid core IgA antibody test be used to screen for NTM-PD in bronchiectasis?

STUDY DESIGN AND METHODS

Patients from the prospective European Bronchiectasis Registry (European Multicentre Bronchiectasis Audit and Research Collaboration-Bronchiectasis Research Involving Databases, Genomics and Endotyping; ClinicalTrails.gov Identifier: NCT03791086) were enrolled. Patients from the United Kingdom, Italy, Spain, Belgium, The Netherlands, and Germany were included. A control cohort of patients without any underlying lung disease also was recruited. The levels of serum IgA antibodies against the glycopeptidolipid core were measured using an enzyme immunoassay kit, and receiver operating characteristics curve analysis was conducted to evaluate the accuracy of the antibody level in screening for NTM-PD.

RESULTS

Two hundred eighty-two patients were enrolled (151 female patients [53.6%]; median age, 68 years). Median antiglycopeptidolipid core IgA antibody levels were 0.2 U/mL (interquartile range [IQR], 0.1-0.3 U/mL) in patients without NTM isolation and NTM-PD (n = 238), 0.3 U/mL (IQR, 0.2-0.4 U/mL) in patients with NTM isolation that was incompatible with the diagnosis of NTM-PD (n = 18), and 1.5 U/mL (IQR, 0.4-6.2 U/mL) in patients with NTM-PD (n = 26; P = .0001). Antibody levels showed excellent accuracy in identifying patients with NTM-PD (area under the receiver operating characteristic curve, 0.886; 95% CI, 0.800-0.973) in the bronchiectasis cohort and also showed excellent discrimination of patients with NTM-PD from those with NTM isolation who did not meet the diagnostic criteria for NTM-PD (0.816; 95% CI, 0.687-0.945).

INTERPRETATION

The antiglycopeptidolipid core IgA antibody demonstrated excellent efficacy in screening for NTM-PD in a large cohort of patients with bronchiectasis.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT03791086; URL: www.

CLINICALTRIALS

gov.

Discovery and analysis of the relationship between organic components in exhaled breath and bronchiectasis

The prevalence of patients with bronchiectasis (BE) has been rising in recent years, which increases the substantial burden on the family and society. Exploring a convenient, effective, and low-cost screening tool for the diagnosis of BE is urgent. We expect to identify the accuracy (ACC) of breath biomarkers (BBs) for the diagnosis of BE through breathomics testing and explore the association between BBs and clinical features of BE. Exhaled breath samples were collected and detected by high-pressure photon ionization time-of-flight mass spectrometry in a cross-sectional study. Exhaled breath samples were from 215 patients with BE and 295 control individuals. The potential BBs were selected via the machine learning (ML) method. The overall performance was assessed for the BBs-based BE detection model. The significant BBs between different subgroups such as the severity of BE, acute or stable stage, combined with hemoptysis or not, with or without nontuberculous mycobacterium (NTM),P. aeruginosa(P.a) isolation or not, and the BBs related to the number of involved lung lobes and lung function were discovered and analyzed. The top ten BBs based ML model achieved an area under the curve of 0.940, sensitivity of 90.7%, specificity of 85%, and ACC of 87.4% in BE diagnosis. Except for the top ten BBs, other BBs were found also related to the severity, acute/stable status, hemoptysis or not, NTM infection,P.aisolation, the number of involved lobes, and three lung functional parameters in BE patients. BBs-based BE detection model showed good ACC for diagnosis. BBs have a close relationship with the clinical features of BE. The breath test method may provide a new strategy for BE screening and personalized management.

Exploring the Association of Bacterial Coinfections with Clinical Characteristics of Patients with Nontuberculous Mycobacterial Pulmonary Disease

BACKGROUND

Clinical data for bacterial coinfection of the lower respiratory tract in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) are scarce. This study aims to assess the prevalence of bacterial coinfection and clinical features in NTM-PD patients.

METHODS

This retrospective study screened 248 patients with NTM-PD who underwent bronchoscopy between July 2020 and July 2022, from whom newly diagnosed NTM-PD patients were analyzed. Bacterial culture using bronchial washing fluid was performed at the time of NTM-PD diagnosis.

RESULTS

In the 180 patients (median age 65 years; 68% female), Mycobacterium avium complex (86%) was the most frequent NTM isolated. Bacterial coinfections were detected in 80 (44%) patients. Among them, the most common bacterium was Klebsiella pneumoniae (n=25/80, 31.3%), followed by Pseudomonas aeruginosa (n=20/80, 25%) and Staphylococcus aureus (n=20/80, 25%). Compared with NTM-PD patients without bacterial coinfections, patients with bacterial coinfections showed more frequent extensive lung involvement (33% vs. 1%, p<0.001). Additionally, compared with NTM-PD patients without P. aeruginosa infection, those with P. aeruginosa infection were older (74 years vs. 64 years, p=0.001), had more frequent respiratory symptoms (cough/excessive mucus production 70% vs. 38%, p=0.008; dyspnea 30% vs. 13%, p=0.047), and had extensive lung involvement (60% vs. 9%, p<0.001).

CONCLUSION

Less than half of patients with newly diagnosed NTM-PD had bacterial coinfections, linked to extensive lung involvement. Specifically, P. aeruginosa coinfection was significantly associated with older age, more frequent respiratory symptoms, and extensive lung involvement.

Epidemiology of bronchiectasis

Bronchiectasis is a chronic respiratory disease characterised by permanent enlargement of the airways associated with cough, sputum production and a history of pulmonary exacerbations. In the past few years, incidence and prevalence of bronchiectasis have increased worldwide, possibly due to advances in imaging techniques and disease awareness, leading to increased socioeconomic burden and healthcare costs. Consistently, a mortality increase in bronchiectasis patient cohorts has been demonstrated in certain areas of the globe, with mortality rates of 16-24.8% over 4-5 years of follow-up. However, heterogeneity in epidemiological data is consistent, as reported prevalence in the general population ranges from 52.3 to more than 1000 per 100 000. Methodological flaws in the designs of available studies are likely to underestimate the proportion of people suffering from this condition worldwide and comparisons between different areas of the globe might be unreliable due to different assessment methods or local implementation of the same method in different contexts. Differences in disease severity associated with diverse geographical distribution of aetiologies, comorbidities and microbiology might explain an additional quota of heterogeneity. Finally, limited access to care in certain geographical areas is associated with both underestimation of the disease and increased severity and mortality. The aim of this review is to provide a snapshot of available real-world epidemiological data describing incidence and prevalence of bronchiectasis in the general population. Furthermore, data on mortality, healthcare burden and high-risk populations are provided. Finally, an analysis of the geographical distribution of determinants contributing to differences in bronchiectasis epidemiology is offered.

Employing Multicolor Melting Curve Analysis to Rapidly Identify Non-Tuberculous Mycobacteria in Patients with Bronchiectasis: A Study from a Pulmonary Hospital in the Fuzhou District of China, 2018-2022

Non-tuberculous mycobacteria (NTM) infection is common in bronchiectasis, with rising incidence globally. However, investigation into NTM in bronchiectasis patients in China remains relatively limited. This work aimed to identify and understand the features of NTM in bronchiectasis patient in Fuzhou district of China. The pulmonary samples were collected from 281 bronchiectasis patients with suspected NTM infection in Fuzhou, 2018-2022. MPB64 antigen detection was employed for the preliminary evaluation of NTM. Further NTM identification was realized using gene chip and gene sequencing. Among 281 patients, 172 (61.21%) patients were NTM-positive (58.72%) according to MPB64 antigen detection, with females (58.72%) outnumbering males (41.28%) and the highest prevalence in the age group of 46-65 years. In total, 47 NTM single infections and 3 mixed infections (1 Mycobacterium tuberculosis complex-M. intracellulare, 1 M. avium-M. intracellulare, and 1 M. abscessus-M. intracellulare) were identified through multicolor melting curve analysis (MMCA), which was compared with gene sequencing results. Both methods suggested Mycobacterium (M.) intracellulare, M. abscessus, and M. avium as the primary NTM species affecting bronchiectasis patients. M. intracellulare and M. abscessus were more frequent in females than males with the highest prevalence in the age group of 46-65 years according to MMCA. This research provides novel insights into the epidemiological and clinical features of NTM in bronchiectasis patients in Southeastern China. Significantly, M. intracellulare, M. abscessus, and M. avium were identified as the major NTM species, contributing to a better understanding and management of bronchiectasis accompanied by NTM infection.

News in respiratory medicine

Pneumology and phthisiology (respiratory medicine) has undergone dynamic development in the last two decades. The main focus of pulmonology in the past was care for patients with tuberculosis and pneumonia. Since then, respiratory medicine evolved and the current focus is on chronic pulmonary diseases, including chronic obstructive pulmonary disease, bronchial asthma, interstitial lung diseases, but also on acute lung conditions (e.g., pneumonia, pleural diseases, respiratory failure), pneumooncology or highly specialized care for rare lung diseases (e.g., cystic fibrosis, rare interstitial diseases). Bronchology, interventional pneumology and pulmonary function testing are also important components of respiratory medicine. The importance of respiratory medicine was apparent during the COVID-19 pandemic. In this article, we provide a brief overview of the most important news to the field of respiratory medicine in the year 2022, addressing the thematic areas of bronchology, cystic fibrosis, chronic obstructive pulmonary disease, asthma, interstitial lung diseases, pleural diseases, pneumooncology, tuberculosis and non-tuberculous mycobacteria.