Patients with nontuberculous mycobacterial lung disease exhibit unique body and immune phenotypes

Lymphocyte subsets and the increased risk for opportunistic infections in severe restrictive anorexia nervosa

Restrictive anorexia nervosa (AN-R) is characterized not only by psychiatric manifestations but also by significant medical complications. Patients commonly exhibit immune alterations, potentially increasing their susceptibility to infections. While direct evidence linking AN-R to heightened rates of opportunistic infections remains inconclusive, clinical observations suggest a higher incidence of complications and delayed febrile response in patients with infections. Concurrently, malnutrition, a frequent cause of secondary immunodeficiencies, exacerbates this susceptibility by compromising immune function. This paper investigates the immunological profiles of two patients with long-term AN-R who developed severe infections: one with disseminated Mycobacterium kansasii and the other with a co-infection of pulmonary Aspergillus fumigatus and Mycobacterium celatum. These cases, alongside data collected from previously published case reports summarized in this study, highlight the impact of altered immune function associated with mentioned population. The paper aims to explain the underlying mechanisms of immune dysfunction. Proactive monitoring of immune status and incorporating such assays into clinical practice may benefit early detection, effective management, and ultimately, improved outcomes.

Targeting Autophagy as a Strategy for Developing New Host-Directed Therapeutics Against Nontuberculous Mycobacteria

Nontuberculous mycobacteria (NTMs) are increasingly being recognized as opportunistic pathogens in clinical practice because of their innate resistance to antimicrobial treatment and the widespread increase in multidrug-resistant strains on a global scale. NTMs pose a tremendous infection management challenge, especially in individuals with pre-existing lung conditions, as well as those who are immunocompromised. NTMs' capability to evade or suppress the immune responses of their host is a key feature that makes them a cause of persistent chronic infection. Autophagy, an essential cellular defense mechanism that delivers and breaks down intracellular materials in lysosomes, protects the host from mycobacterial infection. Initial studies have revealed encouraging therapeutic strategies that augment endogenous autophagic mechanisms or block harmful host responses, thus having the potential to decrease intracellular mycobacterial infection, including that caused by multidrug-resistant strains. This review discusses how NTMs can evade autophagic mechanisms and considers the possibilities of using autophagy-inducing agents to develop novel therapeutic strategies to combat NTM infection.

Differentiating Nontuberculous Mycobacterial Pulmonary Disease from Pulmonary Tuberculosis in Resource-Limited Settings: A Pragmatic Model for Reducing Misguided Antitubercular Treatment

Background: Differentiating nontuberculous mycobacterial pulmonary disease (NTM-PD) from pulmonary tuberculosis (PTB) remains challenging due to overlapping clinical features, particularly in resource-limited settings where diagnostic errors are frequent. This retrospective case-control study (January 2023-June 2024) aimed to identify key clinical predictors and develop a diagnostic model to distinguish NTM-PD from PTB. Methods: Patients initially presumed to have PTB (meeting clinical-radiological criteria but lacking bacteriological confirmation at admission) at a tertiary tuberculosis hospital were enrolled. Final diagnoses of NTM-PD (n = 105) and PTB (n = 105) were confirmed by mycobacterial culture identification. Clinical, laboratory, and radiological data were compared using univariate analysis. Variables showing significant differences (p < 0.05) were entered into multivariable logistic regression. Diagnostic performance was evaluated via receiver operating characteristic (ROC) curve analysis. Results: Female sex (odds ratio [OR] = 2.51, 95% confidence interval [CI] 1.12-5.60), hemoptysis (OR = 2.20, 1.05-4.62), bronchiectasis (OR = 5.92, 2.56-13.71), and emphysema/pulmonary bullae (OR = 2.69, 1.16-6.24) emerged as independent predictors of NTM-PD, while systemic symptoms favored PTB (OR = 0.45, 0.20-0.99). The model demonstrated 91.4% specificity and 68.6% sensitivity with an area under the curve [AUC] of 0.871. Conclusions: This high-specificity model helps prioritize NTM-PD confirmation in females with hemoptysis and structural lung changes (computed tomography evidence of bronchiectasis and/or emphysema) while maintaining PTB suspicion when systemic symptoms (fever, night sweats, weight loss) dominate. The approach may reduce misguided antitubercular therapy in resource-limited settings awaiting culture results.

Treatment of nontuberculous mycobacterial pulmonary disease requires a stepwise and multidisciplinary approach

INTRODUCTION

Nontuberculous mycobacterial pulmonary disease (NTM-PD) occurs in people with inborn or acquired susceptibility factors. Current treatment guideline recommendations include a watchful waiting strategy, antimycobacterial and surgical treatment, with a comprehensive assessment of clinical, microbiological, and radiological factors determining which approach is most suitable.

AREAS COVERED

Treatment outcomes in NTM-PD are unsatisfactory with culture conversion rates varying from 30 to 80% and recurrence rates up to 50%. Possible explanations include our insufficient knowledge and management of host susceptibility factors, poor guideline adherence by physicians, frequent adverse drug reactions demanding premature discontinuation, inadequate drug exposures due to both drug-drug interactions and inter-patient variability in pharmacokinetics, and a lack of pharmacokinetics/pharmacodynamics targets.

EXPERT OPINION

We describe a stepwise approach to NTM-PD treatment, complementing existing guidelines, including recommendations for a multidisciplinary assessment, classification of disease severity, personalized supportive care, antimycobacterial treatment, adjuvant surgery, and host-directed therapies. The recommendations are informed by PubMed literature and the authors' clinical expertise. Recognizing that our experience is shaped within a specialized reference clinic, we acknowledge that some of these recommendations may not be applicable in all settings.

Lung Microenvironment Among Patients with Nontuberculous Mycobacterial Pulmonary Disease by Metagenomic Sequencing Technique

Background: Nontuberculous mycobacterial pulmonary disease (NTM-PD) is an increasingly prevalent chronic infection, where the host immune status plays a crucial role in disease susceptibility and progression. The complex pulmonary microenvironment, characterized by diverse microbial communities and host immune interactions, exhibits distinct features that may be fundamentally altered by the patient's underlying immune state. Methods: A total of 111 sputum specimens and 64 bronchoalveolar lavage fluid (BALF) specimens were collected from 143 patients diagnosed with NTM-PD under different immune states. Metagenomic sequencing was performed on these specimens to characterize and compare the pulmonary microenvironmental features among NTM-PD patients with a distinct immune status through comprehensive bioinformatic analyses. Results: The immunosuppressed group exhibited a lower α-diversity in sputum specimens (p < 0.05). Principal Coordinates Analysis (PCoA) of β-diversity for sputum and BALF specimens revealed significant differences between the groups (p < 0.05). Linear discriminant analysis Effect Size (LEfSe) analysis identified species enriched in the immunosuppressed group. A co-occurrence network analysis indicated that the immunosuppressed group had more structured and actively connected networks compared to the control group. The Mantel test confirmed that the abundance of these species enriched was associated with clinical immune-inflammation-related indicators in patients. Conclusions: Our study reveals the pulmonary microenvironment in immunosuppressed patients with NTM-PD. Further work is required to explore the two-way relationship between micro-organisms and immune and inflammatory responses, with the influence on patient outcomes.

Pulmonary nontuberculous mycobacterial infections among women with cystic fibrosis and non-cystic fibrosis bronchiectasis

Nontuberculous mycobacteria (NTM) are ubiquitous, opportunistic pathogens that can cause lung disease in people with non-cystic fibrosis bronchiectasis (NCFB) and cystic fibrosis (CF). The incidence of NTM pulmonary infections and lung disease has continued to increase worldwide over the last decade among both groups. Notably, women with NCFB NTM pulmonary disease (NTM-PD) bear a disproportionate burden with NTM rates increasing in this population as well as having consistently higher incidence of NTM-PD compared to men. In contrast, among people with CF, an overall increased risk among women has not been observed. In the United States, the majority of people with CF are taking highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulators, and these numbers are increasing worldwide. The long-term impact of CFTR modulator medications on NTM infections is not entirely understood. Guidelines for the screening, diagnosis, and management of NTM-PD exist for people with NCFB and CF, but do not consider unique implications relevant to women. This review highlights aspects of NTM-PD among women with NCFB and CF, including the epidemiology of NTM infection, special considerations for treatment, and unmet research needs relevant to women with NTM-PD.

Distinctive clinical features of radiological pleuroparenchymal fibroelastosis with nontuberculous mycobacterial pulmonary disease: A multicenter retrospective cohort study

OBJECTIVES

To compare the characteristics and prognosis of patients with nontuberculous mycobacterial (NTM) pulmonary disease (PD) with pleuroparenchymal fibroelastosis (PPFE) with those of patients with nodular/bronchiectatic (NB) and fibrocavitary (FC) NTM-PD.

METHODS

This multicenter, retrospective, observational study enrolled 32 patients with NTM-PPFE (median age: 70.5 years, 15 females) from six institutions in Japan from January 2003 to December 2018. Their clinical characteristics and response to therapy were compared with age- and sex-matched cohorts of patients with noncavitary NB and cavitary NB/FC NTM-PD.

RESULTS

Patients with NTM-PPFE had a lower body mass index and a higher standard NTM-PD therapy initiation rate than patients with other NTM-PD types. Sputum culture conversion rates were comparable between groups; however, patients with NTM-PPFE had a higher incidence of treatment-related adverse events, including optic neuropathy associated with high-dose ethambutol therapy, lower percent predicted forced vital capacity values, higher serum Krebs von den Lungen-6 (KL-6) levels, and poorer treatment outcomes than the other groups. Cox regression revealed that NTM-PPFE was an independent risk factor for death/pneumothorax (adjusted hazard ratio: 35.3, 95% confidence interval: 3.90-4692).

CONCLUSION

NTM-PPFE is a unique NTM-PD phenotype with a poorer prognosis than the NB and FC phenotypes.

Nontuberculous Mycobacterial Pulmonary Disease: Patients, Principles, and Prospects

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is increasing in incidence globally and challenging to manage. The 2020 multisociety treatment guideline and the 2022 consensus recommendations provide comprehensive evidence-based guides to manage pulmonary diseases caused by the most common NTM. However, with >190 different NTM species that may require different multidrug regimens for treatment, the breadth and complexity of NTM-PD remain daunting for both patients and clinicians. In this narrative review, we aim to distill this broad, complex field into principles applicable to most NTM species and highlight important nuances, specifically elaborating on the presentation, diagnosis, principles of patient-centered care, principles of pathogen-directed therapy, and prospects of NTM-PD.

Nonpharmacological Treatment for Nontuberculous Mycobacterial Pulmonary Disease

Nontuberculous mycobacterial pulmonary disease (NTM-PD) results from the exposure of susceptible hosts to a diverse group of environmental mycobacteria. The emphasis on nonpharmacological strategies is motivated by the widespread presence of NTM in various environments, and the inconsistent success rates of pharmacological treatments. Modifiable factors contributing to NTM-PD development include impaired airway clearance, low body mass index, gastroesophageal reflux disease, and exposure to NTM habitats. This suggests that lifestyle and environmental modifications could affect disease development and progression. The review highlights several modalities that can modify the risk factors. Airway clearance techniques, informed by the "gel-on-brush" model of the bronchial epithelium, aim to enhance mucociliary clearance, and have the potential to alleviate symptoms and improve lung function. The impact of nutritional status is also examined, with a lower body mass index linked to an increased risk and progression of NTM-PD, indicating the importance of targeted nutritional support. Additionally, the theoretical and epidemiological links between gastroesophageal reflux disease and NTM-PD advocate careful management of reflux episodes. Understanding the risk of NTM transmission through environmental exposure to contaminated water and soil is also crucial. Strategies to mitigate this risk, including effective water management and minimizing soil contact, are presented as vital preventive measures. The review supports the inclusion of nonpharmacological treatments within a comprehensive NTM-PD management strategy, alongside conventional pharmacological therapies. This integrated approach seeks to improve the overall understanding and handling of NTM-PD.

Prevalence of bronchiectasis in adults: a meta-analysis

BACKGROUND

Bronchiectasis, once considered an orphan disease, is receiving attention globally owing to its increasing prevalence, healthcare burden, and associated morbidity. However, the prevalence of bronchiectasis is unclear. This meta-analysis estimates the prevalence of bronchiectasis in adults, providing a valuable reference for future research.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched from inception to May 31, 2024 for studies reporting the prevalence of bronchiectasis. Study selection, data extraction, and overall analysis of risk of the retrieved studies were conducted independently by two authors. The tool for assessing the risk of bias in prevalence studies was used to evaluate overall risk. Stata software (version 15.1) was used to performed the meta-analysis. Subgroup and sensitivity analyses were conducted to identify the source of heterogeneity. Funnel plots combined with Egger's test were used to detect publication bias.

RESULTS

The pooled prevalence of bronchiectasis in adults from 15 studies covering 437,851,478 individuals was 680 per 100,000 (95% CI: 634-727 per 100,000). Subgroup analysis showed that the prevalence of bronchiectasis in the United States, Korea, and China was 478 per 100,000 (95% CI: 367-588 per 100,000), 886 per 100,000 (95% CI: 778-993 per 100,000), and 759 per 100,000 (95% CI: 35-2399 per 100,000), respectively; 467 per 100,000 (95% CI: 416-518 per 100,000) in males and 535 per 100,000 (95% CI: 477-592 per 100,000) in females; 3958 per 100,000 (95% CI: 117-12637 per 100,000), 4677 per 100,000 (95% CI: 427-8928 per 100,000), and 3630 per 100,000 (95% CI: 158-7103 per 100,000) among never-smokers, ever-smokers, and current smokers, respectively; 430 per 100,000 (95% CI: 411-450 per 100,000), 380 per 100,000 (95% CI: 374-386 per 100,000), and 351 per 100,000 (95% CI: 342-360 per 100,000) among individuals with body mass index<18.5, 18.5-24.9, and ≥ 25, respectively. Sixteen comorbidities were evaluated in patients with bronchiectasis, revealing a high rate.

CONCLUSION

Bronchiectasis is not a rare disease and requires more attention from scientific researchers.

TRIAL REGISTRATION

The protocol for this review was registered with PROSPERO: CRD42023409216. Registered 26 June 2023.

Clinical Characteristics of Patients with Nontuberculous Mycobacterium Pulmonary Disease in Fuyang, China: A Retrospective Study

Objective

We retrospectively review consecutive patients with nontuberculous mycobacterium (NTM) pulmonary disease reported from a designated hospital for infectious diseases in the Fuyang district of China to determine the clinical characteristics of these patients.

Methods

This research enrolled 234 patients with NTM pulmonary disease between January 2018 and May 2023 in the Fuyang district of China. Data were collected from the electronic medical records. The NTM strain composition and clinical characteristics of NTM pulmonary disease were retrospectively analyzed.

Results

73 (31.20%) patients had previous tuberculosis (TB) or TB exposure history and bronchiectasis. Mixed NTM infection accounted for 12.39%. Mycobacterium intracellulare strain was detected in 132 patients (49.62%). Women were found to be more affected by Mycobacterium avium infection, and men by Mycobacterium abscessus infection. Mycobacterium avium (34.21%) and Mycobacterium abscessus (33.33%) strains were most common in people with previous TB or TB exposure history. Among respiratory tract-related diseases, patients with bronchiectasis had the highest isolation rate of Mycobacterium avium (55.36%). Women were susceptible to bronchiectasis (P <0.01). The median of mononuclear-to-lymphocyte ratio (MLR) was higher in men than in women (P < 0.01). The serum albumin (ALB) level was lower in patients with TB or TB exposure history than in those without TB history (P = 0.034). The prognostic nutritional index (PNI) was lower in patients with TB or TB exposure history than in those without tuberculosis history (P = 0.021). Patients with NTM lung disease were poorly treated.

Conclusion

Clinical symptoms of the disease were not species-specific. Mycobacterium intracellulare and Mycobacterium avium strains were predominant in the Fuyang district of China. Previous TB or TB exposure history immensely enhanced the risk of NTM disease.

Single-cell transcriptomics by clinical course of Mycobacterium avium complex pulmonary disease

Mycobacterium avium complex pulmonary disease (MAC-PD) has a heterogeneous clinical course. However, immune profiles associated with MAC-PD clinical course are limited. We performed single-cell RNA sequencing of peripheral blood mononuclear cells from 21 MAC-PD patients divided into three clinical courses: group A, spontaneous culture conversion; group B, stable disease without antibiotic treatment; and group C, progressive disease with antibiotic treatment. A lower proportion of NK cells and higher proportion of monocytes were noted in group C compared to combined groups A and B. The proportion of classical monocytes was higher in group C compared to groups A and B, while the proportion of non-classical monocytes decreased. EGR1, HSPA1A, HSPA1B, and CD83 were up-regulated in spontaneous culture conversion group A compared to progressive disease group C. Up-regulation of MYOM2 and LILRA4 and down-regulation of MT-ATP8, CD83, and CCL3L1 was found in progressive disease group C. PCBP1, FOS, RGCC, S100B, G0S2, AREG, and LYN were highly expressed in favorable treatment response compared to unfavorable response. Our findings may offer a comprehensive understanding of the host immune profiles that influence a particular MAC-PD clinical course and could suggest an immunological mechanism associated with the disease progression of MAC-PD.

Protein-energy restriction-induced lipid metabolism disruption causes stable-to-progressive disease shift in Mycobacterium avium-infected female mice

BACKGROUND

Disease susceptibility and progression of Mycobacterium avium complex pulmonary disease (MAC-PD) is associated with multiple factors, including low body mass index (BMI). However, the specific impact of low BMI on MAC-PD progression remains poorly understood. This study aims to examine the progression of MAC-PD in the context of low BMI, utilising a disease-resistant mouse model.

METHODS

We employed a MAC infection-resistant female A/J mouse model to compare the progression of MAC-PD under two dietary conditions: one group was fed a standard protein diet, representing protein-energy unrestricted conditions, and the other was fed a low protein diet (LPD), representing protein-energy restriction.

FINDINGS

Our results reveal that protein-energy restriction significantly exacerbates MAC-PD progression by disrupting lipid metabolism. Mice fed an LPD showed elevated fatty acid levels and related gene expressions in lung tissues, similar to findings of increased fatty acids in the serum of patients who exhibited the MAC-PD progression. These mice also exhibited increased CD36 expression and lipid accumulation in macrophages upon MAC infection. In vitro experiments emphasised the crucial role of CD36-mediated palmitic acid uptake in bacterial proliferation. Importantly, in vivo studies demonstrated that administering anti-CD36 antibody to LPD-fed A/J mice reduced macrophage lipid accumulation and impeded bacterial growth, resulting in remarkable slowing disease progression.

INTERPRETATION

Our findings indicate that the metabolic status of host immune cells critically influences MAC-PD progression. This study highlights the potential of adequate nutrient intake in preventing MAC-PD progression, suggesting that targeting CD36-mediated pathways might be a host-directed therapeutic strategy to managing MAC infection.

FUNDING

This research was funded by the National Research Foundation of Korea, the Korea Research Institute of Bioscience and Biotechnology, and the Korea National Institute of Health.

Growing from common ground: nontuberculous mycobacteria and bronchiectasis

Bronchiectasis and nontuberculous mycobacteria (NTM) are intricately intertwined, with NTM capable of being both a cause and consequence of bronchiectatic disease. This narrative review focuses on the common ground of bronchiectasis and NTM pulmonary disease (NTM-PD) in terms of diagnostic approach, underlying risk factors and treatment strategies. NTM-PD diagnosis relies on a combination of clinical, radiological and microbiological criteria. Although their epidemiology is complicated by detection and reporting biases, the prevalence and pathogenicity of NTM species vary geographically, with Mycobacterium avium complex and Mycobacterium abscessus subspecies most frequently isolated in bronchiectasis-associated NTM-PD. Diagnosis of nodular bronchiectatic NTM-PD should prompt investigation of host factors, including disorders of mucociliary clearance, connective tissue diseases and immunodeficiencies, either genetic or acquired. Treatment of NTM-PD in bronchiectasis involves a multidisciplinary approach and considers the (sub)species involved, disease severity and comorbidities. Current guideline-based antimicrobial treatment of NTM-PD is considered long, cumbersome and unsatisfying in terms of outcomes. Novel treatment regimens and strategies are being explored, including rifampicin-free regimens and inclusion of clofazimine and inhaled antibiotics. Host-directed therapies, such as immunomodulators and cytokine-based therapies, might enhance antimycobacterial immune responses. Optimising supportive care, as well as pathogen- and host-directed strategies, is crucial, highlighting the need for personalised approaches tailored to individual patient needs. Further research is warranted to elucidate the complex interplay between host and mycobacterial factors, informing more effective management strategies.

A Puerto Rican Variant of Lady Windermere Syndrome: Reanalyzing the Characteristics of Non-tuberculous Mycobacterial Infection

Lady Windermere syndrome (LWS) is a disease caused by a non-tuberculous Mycobacterium (NTM) that is commonly found in thin women who voluntarily suppress their cough reflex. The NTM that causes this syndrome is Mycobacterium avium complex, an organism commonly present in chlorinated city water and soil. Patients with LWS are tall, lean, elderly white women. We report a case of an immunocompetent 81-year-old thin Puerto Rican female with a recurrent cough since childhood, who was misdiagnosed with tuberculosis (TB) and prophylactically treated. While the patient fitted the clinical picture of NTM pulmonary infection based on symptoms, imaging, and microbiologic findings, her demography and morphologic features were not completely consistent with published findings. The incidence and prevalence of NTM lung disease are rising worldwide due to the aging population, increased use of immunosuppressive medications, and prevalence of chronic pulmonary obstructive disease and bronchiectasis. The goal of this report is to increase awareness of LWS as one of the diagnoses that should be considered in patients presenting with clinical findings resembling TB and bring attention to the different clinical characteristics this patient with LWS possessed.

Usefulness of the mini nutritional assessment short-form for evaluating nutritional status in patients with nontuberculous mycobacterial pulmonary disease: a prospective cross-sectional study

BACKGROUND

Although the Mini Nutritional Assessment (MNA) is recognized as a useful tool for evaluating nutritional status in patients with various diseases, its applicability in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) remains undetermined.

METHODS

We designed a prospective cross-sectional study to investigate whether the MNA Short-Form (MNA-SF) score can serve as a screening tool to assess the nutritional status of patients with NTM-PD. The MNA-SF was conducted upon patient enrollment, and correlation analyses were performed to compare MNA-SF scores with other nutritional measurements and disease severity. Multivariable logistic regression analyses were conducted to evaluate the association between MNA-SF scores and NTM-PD severity.

RESULTS

The 194 patients with NTM-PD included in the analysis had a median age of 65.0 (59.0-69.0) years; 59.3% (n = 115) had low MNA-SF scores (< 12). The low MNA-SF group exhibited a lower body mass index (19.7 vs. 22.4 kg/m2, p < 0.001) and fat-free mass index (14.7 vs. 15.6 kg/m2, p < 0.001) than the normal MNA-SF group, as well as higher incidences of sarcopenia (20.0% vs. 6.3%, p = 0.008) and adipopenia (35.7% vs. 5.1%, p < 0.001). However, no significant differences in calorie and protein intakes were observed between the two groups. Low MNA-SF scores were associated with radiographic severity (adjusted odds ratio 2.72, 95% confidence interval 1.38-5.36) but not with forced vital capacity.

CONCLUSIONS

The MNA-SF can effectively assess the nutritional status of patients with NTM-PD and can serve as an important clinical indicator in NTM-PD where treatment timing is determined by clinical judgment.

Comparison of the sputum microbiome between patients with stable nontuberculous mycobacterial pulmonary disease and patients requiring treatment

BACKGROUND

We evaluated whether the sputum bacterial microbiome differs between nontuberculous mycobacteria pulmonary disease (NTM-PD) patients with stable disease not requiring antibiotic treatment and those requiring antibiotics.

METHODS

We collected sputum samples from 21 clinically stable NTM-PD patients (stable group) and 14 NTM-PD patients needing antibiotic treatment (treatment group). We also obtained 13 follow-up samples from the stable group. We analyzed the 48 samples using 16S rRNA gene sequencing (V3-V4 region) and compared the groups.

RESULTS

In the linear discriminant analysis effect size (LEfSe) analysis, the species Porphyromonas pasteri, Haemophilus parahaemolyticus, Prevotella nanceiensis, and Gemella haemolysans were significantly more prevalent in the sputum of the stable group compared to the treatment group. No taxa showed significant differences in alpha-/beta-diversity or LEfSe between the 21 baseline and 13 follow-up sputum samples in the stable group. In the stable group, the genus Bergeyella and species Prevotella oris were less common in patients who achieved spontaneous culture conversion (n = 9) compared to those with persistent NTM positivity (n = 12) (effect size 3.04, p = 0.039 for Bergeyella; effect size 3.64, p = 0.033 for P. oris). In the treatment group, H. parainfluenzae was more common in patients with treatment success (n = 7) than in treatment-refractory patients (n = 7) (effect size 4.74, p = 0.013).

CONCLUSIONS

Our study identified distinct bacterial taxa in the sputum of NTM-PD patients based on disease status. These results suggest the presence of a microbial environment that helps maintain disease stability.

Cancer immunotherapy with immune checkpoint inhibitors and infections: A particular focus on mycobacterial infections

Cancer treatment is undergoing a major transformation with the advent of immunotherapy with immune checkpoint inhibitors. These drugs, which have a different mechanism of action from conventional cytotoxic chemotherapy, are transforming treatment paradigms for many patients suffering from advanced cancer. On the other hand, they are often complicated by specific adverse events, known as immune-related adverse events (irAEs). Infections occurring during immunotherapy with immune checkpoint inhibitors have recently received increasing attention and sometimes are seen as part of irAEs. Amongst these, mycobacterial infections have attracted particular attention. Recent reports have shown that infections occurring during immunotherapy can not only be caused by immunosuppression, but in addition new type of infections are observed that are not caused by immunosuppression. Specifically, tuberculosis (TB) has recently been shown to develop as a result of an imbalance in immunoregulation and an excessive immune response. This review highlights reports of infections during immunotherapy with immune checkpoint inhibitors, followed by a focus on the association with TB and nontuberculous mycobacteria. It concludes with a discussion of the possible mechanisms of pathogenesis and the implications for clinical practice.

Pharmacotherapeutic Considerations in the Treatment of Nontuberculous Mycobacterial Infections: A Primer for Clinicians

Nontuberculous mycobacteria (NTM) can cause a variety of infections, including serious pulmonary disease. Treatment encompasses polypharmacy, with a targeted regimen of 2-5 active medications, depending on site of infection, species, and clinical characteristics. Medications may include oral, intravenous, and inhalational routes. Medication acquisition can be challenging for numerous reasons, including investigational status, limited distribution models, and insurance prior authorization. Additionally, monitoring and managing adverse reactions and drug interactions is a unique skill set. While NTM is primarily medically managed, clinicians may not be familiar with the intricacies of medication selection, procurement, and monitoring. This review offers insights into the pharmacotherapeutic considerations of this highly complex disease state, including regimen design, medication acquisition, safety monitoring, relevant drug-drug interactions, and adverse drug reactions.

The Clinical Implications of Serum Carbohydrate Antigen 19-9 Levels in Patients with Nontuberculous Mycobacteria Pulmonary Disease

Serum carbohydrate antigen 19-9 (CA19-9) levels can increase in nontuberculous mycobacteria pulmonary disease (NTM-PD), and the levels correlate with disease activity. We compared the clinical characteristics of NTM-PD patients with and without elevated CA19-9 levels and evaluated its association with antibiotic response in a retrospective study of NTM-PD patients diagnosed between January 1994 and December 2020. We analyzed 1112 patients who had serum CA19-9 measured: 322 with elevated CA19-9 and 790 with normal CA19-9. The erythrocyte sedimentation rate and C-reactive protein levels were significantly higher in the elevated CA19-9 group (p < 0.001 and p = 0.029, respectively). The 1-year culture conversion rate after antibiotics did not differ between the elevated (n = 206) and normal (n = 377) CA19-9 groups (80% vs. 72%, p = 0.055). Analysis of a subset of 434 patients revealed that current smoking, bronchiectasis, acid-fast bacilli smear positivity, and the M. abscessus strain significantly reduced microbiological cure rates. Serum CA 19-9 levels did not have a significant association with microbiological cure in a multivariate analysis. These findings suggest that the role of serum CA19-9 in predicting antibiotic treatment outcomes is limited, and that elevated CA19-9 does not necessarily indicate a poor outcome.

Treatable traits and challenges in the clinical management of non-tuberculous mycobacteria lung disease in people with cystic fibrosis

INTRODUCTION

Over the last ten years an increasing prevalence and incidence of non-tuberculous mycobacteria (NTM) has been reported among patients with cystic fibrosis (CF) Viviani (J Cyst Fibros, 15(5):619-623, 2016). NTM pulmonary disease has been associated with negative clinical outcomes and often requires pharmacological treatment. Although specific guidelines help clinicians in the process of diagnosis and clinical management, the focus on the multidimensional assessment of concomitant problems is still scarce.

MAIN BODY

This review aims to identify the treatable traits of NTM pulmonary disease in people with CF and discuss the importance of a multidisciplinary approach in order to detect and manage all the clinical and behavioral aspects of the disease. The multidisciplinary complexity of NTM pulmonary disease in CF requires careful management of respiratory and extra-respiratory, including control of comorbidities, drug interactions and behavioral factors as adherence to therapies.

CONCLUSIONS

The treatable trait strategy can help to optimize clinical management through systematic assessment of all the aspects of the disease, providing a holistic treatment for such a multi-systemic and complex condition.

Epidemiology, clinical characteristics, and outcomes of nontuberculous mycobacterial skin, soft tissue, and bone infections from a single center over a 10-year period

Introduction

Non-tuberculous mycobacteria (NTM) cause a wide variety of clinical syndromes. Data guiding diagnosis and treatment of NTM skin and soft tissue infections (SSTI) and bone infections are limited. We sought to better understand SSTI and bone infections caused by NTM.

Methods

All NTM clinical isolates recovered at Brooke Army Medical Center from 2012 to 2022 were screened; SSTI and bone isolates were included. Electronic health records were reviewed for epidemiologic, microbiologic, and clinical data. Infections were defined as recovery of one or more NTM isolate from skin, soft tissue, or bone cultures with a corresponding clinical syndrome.

Results

Forty isolates of skin, soft tissue, or bone origin from 29 patients were analyzed. Twenty (69 %) patients, majority female (14/20, 70 %), had infecting isolates, most commonly secondary to surgery (35 %) or trauma (35 %). Six of 20 (30 %) had bone infections. Time from symptom onset to isolate recovery was a median 61 days (IQR 43-95). Eight (40 %) had combined medical/surgical therapy, 8 (40 %) had surgery alone, and 4 (20 %) had medical therapy alone. M. abscessus was more frequently isolated from patients with true infections.

Conclusions

Data supporting diagnosis and treatment decisions in NTM SSTI/bone infections is sparse. In this study the majority of NTM isolated were true infections. We confirm that surgery and trauma are the most common routes of exposure. The delay between symptom onset and directed therapy and the wide variety of treatment regimens highlight a need for additional studies delineating criteria for diagnosis and treatment.

Myosteatosis as a prognostic factor of Mycobacterium avium complex pulmonary disease

Quantitative body composition affects the prognosis of patients with Mycobacterium avium complex pulmonary disease (MAC-PD). However, whether the qualitative body composition obtained indirectly through computed tomography (CT) affects their prognosis is debatable. We retrospectively analyzed patients with MAC-PD who underwent non-contrast CT at MAC-PD diagnosis. The cross-sectional area of the erector spinae muscle (ESM area), the Hounsfield unit of the erector spinae muscle (ESM HU), and the cross-sectional area of subcutaneous fat (SQF area) were measured at the level of the first lumbar vertebra. Myosteatosis were defined below the median value of ESM HU for each sex. Of 377 patients, 45 (11.9%) died during the follow-up. Patients who died were older and had a lower ratio of females (33.3%). In body compositions, SQF area and ESM HU were lower in the patients who died. In multivariable analysis, a low ESM HU was associated with increased mortality (ESM HU adjusted hazard ratio [aHR] 0.95, 95% confidence interval [CI] 0.93-0.97) through body composition. SQF area revealed protective effects in MAC-PD patients with body mass index ≥ 18.5 kg/m2 (aHR 0.98, 95% CI 0.95-1.00). In conclusion, the decrease in ESM HU, which indirectly reflects myosteatosis, is associated with mortality in patients with MAC-PD.

Association of body size distortion with low body mass index in female patients with nontuberculous mycobacterial lung disease

BACKGROUND

We have previously reported that female patients with nontuberculous mycobacterial lung disease (NTM-LD) are thinner and eat less than healthy controls. Therefore, we hypothesized that their thinness is associated with body size misperception. The aim of this study was to clarify whether patients' body size perception (BSP) is associated with body mass index (BMI) independent of potential confounders.

METHODS

In this cross-sectional study, we assessed 81 outpatients for BSP using the Japanese version of Body Image Scale, body composition, dietary intake, and biochemical markers. As a control, we used BSP and self-reported anthropometric data from 111 healthy women collected via a web survey. First, BSP and BMI were compared between the patients and the controls. Second, patient data was compared between patients who overestimated their body size (OE, n = 31) and a control who did not (Non-OE, n = 50). Multiple regression analysis was performed to clarify the association between BSP (independent variable) and BMI (dependent variable), adjusting for potential confounders, such as age, disease duration, and nutritional factors.

RESULTS

There was a negative correlation between body size distortion and BMI in both patients and controls (p < 0.001, both). In interpatient comparisons, the OE group had significantly lower BMI and body fat percentage (p < 0.001, both), normalized energy (p = 0.037), and protein (p = 0.013) intakes, and significantly greater weight loss from age 20 (p = 0.003) than the Non-OE group. Multiple regression analysis revealed that overestimation of body size was associated with lower BMI independent of confounders, such as longer disease history, longitudinal weight loss, and nutritional factors.

CONCLUSION

These findings suggest that body size distortion is an etiological factor for lower BMI in female patients with NTM-LD. Thus, it may be important to understand the patient's body image when providing dietary advice.

The lung microbiota in nontuberculous mycobacterial pulmonary disease

BACKGROUND

The role of bacterial microbiota in the pathogenesis of nontuberculous mycobacterial pulmonary disease (NTM-PD) is unclear. We aimed to compare the bacterial microbiome of disease-invaded lesions and non-invaded lung tissue from NTM-PD patients.

METHODS

We analyzed lung tissues from 23 NTM-PD patients who underwent surgical lung resection. Lung tissues were collected in pairs from each patient, with one sample from a disease-involved site and the other from a non-involved site. Lung tissue microbiome libraries were constructed using 16S rRNA gene sequences (V3-V4 regions).

RESULTS

Sixteen (70%) patients had Mycobacterium avium complex (MAC)-PD, and the remaining seven (30%) had Mycobacterium abscessus-PD. Compared to non-involved sites, involved sites showed greater species richness (ACE, Chao1, and Jackknife analyses, all p = 0.001); greater diversity on the Shannon index (p = 0.007); and genus-level differences (Jensen-Shannon, PERMANOVA p = 0.001). Analysis of taxonomic biomarkers using linear discriminant analysis (LDA) effect sizes (LEfSe) demonstrated that several genera, including Limnohabitans, Rahnella, Lachnospira, Flavobacterium, Megamonas, Gaiella, Subdoligranulum, Rheinheimera, Dorea, Collinsella, and Phascolarctobacterium, had significantly greater abundance in involved sites (LDA >3.00, p <0.05, and q <0.05). In contrast, Acinetobacter had significantly greater abundance at non-involved sites (LDA = 4.27, p<0.001, and q = 0.002). Several genera were differentially distributed between lung tissues from MAC-PD (n = 16) and M. abscessus-PD (n = 7), and between nodular bronchiectatic form (n = 12) and fibrocavitary form (n = 11) patients. However, there was no genus with a significant q-value.

CONCLUSIONS

We identified differential microbial distributions between disease-invaded and normal lung tissues from NTM-PD patients, and microbial diversity was significantly higher in disease-invaded tissues.

TRIAL REGISTRATION

Clinical Trial registration number: NCT00970801.

Pathophysiology of pulmonary nontuberculous mycobacterial (NTM) disease

In recent years, the incidence and prevalence of pulmonary nontuberculous mycobacterial (NTM) disease have increased worldwide. Although the reasons for this increase are unclear, dealing with this disease is essential. Pulmonary NTM disease is a chronic pulmonary infection caused by NTM bacteria, which are ubiquitous in various environments. In Japan, Mycobacterium avium-intracellulare complex (MAC) accounts for approximately 90% of the causative organisms of pulmonary NTM disease, which is also called pulmonary MAC disease or pulmonary MAI disease. It is important to elucidate the pathophysiology of this disease, which occurs frequently in postmenopausal women despite the absence of obvious immunodeficiency. The pathophysiology of this disease has not been fully elucidated; however, it can largely be divided into bacterial (environmental) and host-side problems. The host factors can be further divided into immune and airway problems. The authors suggest that the triangular relationship between bacteria, immunity, and the airway is important in the pathophysiology of this disease. The latest findings on the pathophysiology of pulmonary NTM disease are reviewed.

Decreased Interleukin-1 Family Cytokine Production in Patients with Nontuberculous Mycobacterial Lung Disease

Nontuberculous mycobacteria (NTM) cause pulmonary disease in individuals without obvious immunodeficiency. This study was initiated to gain insight into the immunological factors that predispose persons to NTM pulmonary disease (NTMPD). Blood was obtained from 15 pairs of NTMPD patients and their healthy household contacts. Peripheral blood mononuclear cells (PBMCs) were stimulated with the Mycobacterium avium complex (MAC). A total of 34 cytokines and chemokines were evaluated in plasma and PBMC culture supernatants using multiplex immunoassays, and gene expression in the PBMCs was determined using real-time PCR. PBMCs from NTMPD patients produced significantly less interleukin-1β (IL-1β), IL-18, IL-1α, and IL-10 than PBMCs from their healthy household contacts in response to MAC. Although plasma RANTES levels were high in NTMPD patients, they had no effect on IL-1β production by macrophages infected with MAC. Toll-like receptor 2 (TLR2) and TWIK2 (a two-pore domain K+ channel) were impaired in response to MAC in PBMCs of NTMPD patients. A TLR2 inhibitor decreased all four cytokines, whereas a two-pore domain K+ channel inhibitor decreased the production of IL-1β, IL-18, and IL-1α, but not IL-10, by MAC-stimulated PBMCs and monocytes. The ratio of monocytes was reduced in whole blood of NTMPD patients compared with that of healthy household contacts. A reduced monocyte ratio might contribute to the attenuated production of IL-1 family cytokines by PBMCs of NTMPD patients in response to MAC stimulations. Collectively, our findings suggest that the attenuated IL-1 response may increase susceptibility to NTM pulmonary infection through multiple factors, including impaired expression of the TLR2 and TWIK2 and reduced monocyte ratio. IMPORTANCE Upon MAC stimulation, the production of IL-1 family cytokines and IL-10 by PBMCs of NTMPD patients was attenuated compared with that of healthy household contacts. Upon MAC stimulation, the expression of TLR2 and TWIK2 (one of the two-pore domain K+ channels) was attenuated in PBMCs of NTMPD patients compared with that of healthy household contacts. The production of IL-1 family cytokines by MAC-stimulated PBMCs and MAC-infected monocytes of healthy donors was reduced by a TLR2 inhibitor and two-pore domain K+ channel inhibitor. The ratio of monocytes was reduced in whole blood of NTMPD patients compared with that of healthy household contacts. Collectively, our data suggest that defects in the expression of TLR2 and TWIK2 in human PBMCs or monocytes and reduced monocyte ratio are involved in the reduced production of IL-1 family cytokines, and it may increase susceptibility to NTM pulmonary infection.

T-cell deficiency and hyperinflammatory monocyte responses associate with Mycobacterium avium complex lung disease

Immunological mechanisms of susceptibility to nontuberculous mycobacterial (NTM) disease are poorly understood. To understand NTM pathogenesis, we evaluated innate and antigen-specific adaptive immune responses to Mycobacterium avium complex (MAC) in asymptomatic individuals with a previous history of MAC lung disease (MACDZ). We hypothesized that Mav-specific immune responses are associated with susceptibility to MAC lung disease. We measured MAC-, NTM-, or MAC/Mtb-specific T-cell responses by cytokine production, expression of surface markers, and analysis of global gene expression in 27 MACDZ individuals and 32 healthy controls. We also analyzed global gene expression in Mycobacterium avium-infected and uninfected peripheral blood monocytes from 17 MACDZ and 17 healthy controls. We were unable to detect increased T-cell responses against MAC-specific reagents in MACDZ compared to controls, while the responses to non-mycobacteria derived antigens were preserved. MACDZ individuals had a lower frequency of Th1 and Th1* T-cell populations. In addition, MACDZ subjects had lower transcriptional responses in PBMCs stimulated with a mycobacterial peptide pool (MTB300). By contrast, global gene expression analysis demonstrated upregulation of proinflammatory pathways in uninfected and M. avium-infected monocytes, i.e. a hyperinflammatory in vitro response, derived from MACDZ subjects compared to controls. Together, these data suggest a novel immunologic defect which underlies MAC pathogenesis and includes concurrent innate and adaptive dysregulation which persists years after completion of treatment.

Nontuberculous Mycobacteria Lung Disease (NTM-LD): Current Recommendations on Diagnosis, Treatment, and Patient Management

Nontuberculous mycobacteria (NTM) are a group of ubiquitous environmental bacteria that can be found in soil, dust, and water. Mycobacterium avium complex (MAC) is the most common pathogen and the one most associated with chronic pulmonary disease. In recent years, the prevalence of Mycobacterium avium complex-related pulmonary disease (MAC-PD) has increased and is an emerging public health concern. This is due to a combination of environmental and geographic factors, dynamic changes in organism virulence and antimicrobial susceptibility, and evolving host susceptibility. Given the dynamic nature of the disease, management of NTM pulmonary disease (NTM-PD) often includes a multimodal approach including antimicrobial therapy, airway clearance techniques, limiting environmental exposures, and reducing susceptibility to NTM through prevention of reflux and maintenance of body weight. This review will explore the most recent concepts in the diagnosis, treatment, and management of individuals with NTM pulmonary infection.

[Clinical Characteristics of Nontuberculous Mycobacterium Infection Cases in Sichuan, China in 2016-2021: A Retrospective Study]

Objective

To study the distribution of nontuberculous mycobacterium (NTM) strains, clinical characteristics and drug sensitivity data of NTM infections so as to provide support for the prevention and treatment of diseases caused by NTM infection in Sichuan.

Methods

The clinical data of NTM infection cases treated at the Public Health Clinical Center of Chengdu between July 2016 and July 2021 were collected and the characteristics of the infections were retrospectively reviewed.

Results

There were differences in sex, age and underlying diseases among the NTM infection cases in Sichuan. Specifically, young and middle-aged men aged between 20 and 40 were susceptible to AIDS, older men aged over 60 were susceptible to lung diseases, and middle-aged and older women over 40 were susceptible to bronchiectasis. Respiratory tract was the main route of NTM infection. The dominant strain in Sichuan was M. chelonae/ abscessus. The drug resistance rate of M. avium and M. chelonae/ abscessus were relatively higher.

Conclusion

For NTM infection patients with different demographic characteristics and underlying diseases, the NTM infection sites, strains, and drug resistance are also different. Definite etiological diagnosis is essential to the treatment of NTM infection. We should highlight the importance of adopting individualized treatment for different NTM infections.

The Higher Incidence of COVID-19 in Patients With Non-Tuberculous Mycobacterial Pulmonary Disease: A Single Center Experience in Korea

The aim of our study was to investigate the incidence of and risk factors for coronavirus disease 2019 (COVID-19) in patients with non-tuberculous mycobacterial-pulmonary disease (NTM-PD). A total of 3,866 patients with NTM-PD were retrospectively identified from a single center. Compared to the general population of Korea, patients with NTM-PD had a substantially increased age-standardized incidence of COVID-19 from January 2020 to February 2021 (2.1% vs. 0.2%). The odds of being infected with COVID-19 was particularly higher in patients who received treatment for NTM-PD than in those who did not receive treatment for NTM-PD (adjusted odd ratio = 1.99, 95% confidence interval = 1.09-3.64, P = 0.026). Patients with NTM-PD might be regarded as a high-risk group for COVID-19 and may need a more proactive preventive strategy for COVID-19 and other pandemics in the future.

Nutritional status in female patients with nontuberculous mycobacterial lung disease and its association with disease severity

Background

In women, slender body habitus has been reported to be one of the predisposing factors underlying the development and poor prognosis of non-tuberculous mycobacterial lung disease (NTM-LD). Given the lack of nutritional data contributing to treatment strategies, we aimed to clarify the nutritional status of female patients with NTM-LD and its association with disease severity.

Methods

In this single-center observational study, we enrolled 81 female outpatients with NTM-LD. Data on healthy women of similar ages were selected from our previous survey data and categorized as controls. First, we compared anthropometric and dietary survey data between patients and controls. Second, after the patients were categorized into relatively mild (mild, n = 40) and relatively severe groups (severe, n = 41) based on pulmonary X-ray-image finding scores, body composition, nutritional intake, and biochemical markers were compared between the groups. To identify nutritional factors associated with disease severity, logistic regression analyses were performed.

Results

Compared with controls, patients with NTM-LD had significantly lower energy intake, body mass index, body fat, and skeletal muscle mass (all p < 0.001). Compared with the mild group, the severe group had significantly lower skeletal muscle mass (p = 0.037), albumin (p = 0.029), transthyretin (prealbumin) (p = 0.002), retinol-binding protein (p = 0.011), and hemoglobin (p = 0.001); however, no between-group differences were observed in energy or nutrient intake. Logistic analyses revealed that transthyretin (p = 0.025) and hemoglobin (p = 0.003) levels were independent factors associated with disease severity.

Conclusions

This is the first study to comprehensively report the association between NTM-LD severity and nutritional status, including body composition, nutrient intake, and biomarkers. The results suggest that initiating nutritional therapy from the mild stage of the disease to prevent undernutrition is warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02109-5.

Antibiotic Maintenance and Redevelopment of Nontuberculous Mycobacteria Pulmonary Disease after Treatment of Mycobacterium avium Complex Pulmonary Disease

Limited data are available regarding the impact of the antibiotic maintenance period on the redevelopment of nontuberculous mycobacteria-pulmonary disease (NTM-PD) after microbiological cure of Mycobacterium avium complex (MAC)-PD. This retrospective study included 631 MAC-PD patients who achieved microbiological cure between 1994 and 2021. Data on the antibiotic maintenance period, defined as the time between culture conversion and treatment completion, were collected. Redevelopment, the subsequent diagnosis of NTM-PD regardless of causative organism after microbiological cure, was investigated. Factors associated with redevelopment were analyzed after adjusting for disease severity using the body mass index, age, cavity, erythrocyte sedimentation rate, and sex (BACES) scoring system. In total, 205 (33%) patients experienced redevelopment, with a median maintenance period after culture conversion of 15.0 months (interquartile range, 13.0 to 22.0 months). A greater proportion of patients with the nodular bronchiectatic form of MAC-PD (87% versus 80%, P = 0.033) and a longer maintenance period (median 15.0 versus 14.0 months, P < 0.001) were noted in the redevelopment group compared with the nonredevelopment group. The cumulative rate of redevelopment according to the maintenance period did not differ between the >12-month and ≤12-month groups in the total patient population or the subgroups sorted according to BACES severity. No association between a maintenance period >12 months and redevelopment was identified in multivariate models. Extending the antibiotic maintenance period more than 12 months did not reduce the redevelopment rate even with adjustment for disease severity, suggesting the need to further optimize the duration of the antibiotic maintenance period.

IMPORTANCE Limited data are available regarding the impact of the antibiotic maintenance period on the redevelopment of Mycobacterium avium complex-pulmonary (MAC-PD) disease after microbiological cure. To improve treatment outcomes and reduce the recurrence rate, current guidelines recommend maintenance of antibiotics for a minimum of 12 months after achievement of negative culture conversion. However, the optimal duration of antibiotic therapy for MAC-PD is not currently known. Moreover, in real-world clinical practice, total antibiotic duration is mainly impacted by the length of the maintenance period; however, it is unknown whether extending the maintenance period is beneficial for preventing redevelopment of NTM-PD. Our study may help to address concerns regarding the antibiotic maintenance period after achievement of negative culture conversion in patients with MAC-PD.

Mycobacterium abscessus: It's Complex

Mycobacterium abscessus (M. abscessus) is an opportunistic pathogen usually colonizing abnormal lung airways and is often seen in patients with cystic fibrosis. Currently, there is no vaccine available for M. abscessus in clinical development. The treatment of M. abscessus-related pulmonary diseases is peculiar due to intrinsic resistance to several commonly used antibiotics. The development of either prophylactic or therapeutic interventions for M. abscessus pulmonary infections is hindered by the absence of an adequate experimental animal model. In this review, we outline the critical elements related to M. abscessus virulence mechanisms, host-pathogen interactions, and treatment challenges associated with M. abscessus pulmonary infections. The challenges of effectively combating this pathogen include developing appropriate preclinical animal models of infection, developing proper diagnostics, and designing novel strategies for treating drug-resistant M. abscessus.

Osteoporosis in nontuberculous mycobacterial pulmonary disease: a cross-sectional study

Background

Since nontuberculous mycobacterial pulmonary disease (NTM-PD) is common in middle-aged/elderly slender women at risk of osteoporosis, we hypothesized that NTM-PD could be associated with osteoporosis. The study aimed to evaluate the prevalence of osteoporosis in patients with NTM-PD compared with that in the general population and determine the factors associated with osteoporosis in the subjects, including the serum estradiol (E₂) and 25-hydroxyvitamin D (25OHD) levels.

Methods

We have recruited 228 consecutive adult patients with NTM-PD from a prospective cohort study at the Keio University Hospital, who had no history of osteoporosis or osteoporosis-associated bone fracture but underwent dual-energy X-ray absorptiometry-based bone mineral density (BMD) evaluation from August 2017–September 2019. The E₂ and 25OHD levels were measured in 165 patients with available stored serum samples. We performed multivariable logistic regression analyses for osteopenia and osteoporosis.

Results

Osteoporosis (T-score ≤  − 2.5) and osteopenia (T-score − 1 to − 2.5) were diagnosed in 35.1% and 36.8% of patients with NTM-PD, respectively. Compared with the general population, the proportion of osteoporosis was significantly higher in 50–59-, 60–69-, and 70–79-year-old women with NTM-PD. Multivariable analysis revealed that older age (adjusted odds ratio [aOR] for 1-year increase = 1.12; 95% confidence interval [CI] = 1.07–1.18), female sex (aOR = 36.3; 95% CI = 7.57–174), lower BMI (aOR for 1 kg/m² decrease = 1.37; 95% CI = 1.14–1.65), and chronic Pseudomonas aeruginosa (PA) infection (aOR = 6.70; 95% CI = 1.07–41.8) were independently associated with osteoporosis. Additionally, multivariable analysis in 165 patients whose serum E₂ and 25OHD levels were measured showed that both low E₂ levels (< 10 pg/mL) and lower 25OHD levels were independently associated with osteoporosis.

Conclusions

Middle-aged/elderly women with NTM-PD have a higher prevalence of osteoporosis than the general population. BMD screening should be considered in NTM-PD, especially in older females with severe diseases such as chronic PA infection and lower BMI, and low serum E₂ and 25OHD levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01991-3.

Novel Screening System of Virulent Strains for the Establishment of a Mycobacterium avium Complex Lung Disease Mouse Model Using Whole-Genome Sequencing

The establishment of animal models reflecting human Mycobacterium avium complex (MAC) lung disease (LD) pathology has the potential to expand our understanding of the disease pathophysiology. However, inducing sustained infection in immunocompetent mice is difficult since MAC generally shows less virulence and higher genetic variability than M. tuberculosis. To overcome this hurdle, we developed a screening system for identifying virulent MAC strains using whole-genome sequencing (WGS). We obtained nine clinical strains from Mycobacterium avium complex lung disease (MAC-LD) patients and divided them into two groups to make the mixed strain inocula for infection. Intranasal infection with the strain mixture of both groups in BALB/c mice resulted in progressive infection and extensive granuloma formation in the lungs, suggesting the existence of highly pathogenic strains in each group. We hypothesized that the change in the abundance of strain-specific single-nucleotide variants (SNVs) reflects the change in bacterial number of each strain in infected lungs. Based on this hypothesis, we quantified individual strain-specific SNVs in bacterial DNA from infected lungs. Specific SNVs for four strains were detected, suggesting the pathogenicity of these four strains. Consistent with these results, individual infection with these four strains induced a high lung bacterial burden, forming extensive peribronchial granuloma, while the other strains showed a decreased lung bacterial burden. The current method combining mixed infection and WGS accurately identified virulent strains that induced sustained infection in mice. This method will contribute to the establishment of mouse models that reflect human MAC-LD and lead to antimycobacterial drug testing. IMPORTANCE To promote research on Mycobacterium avium complex (MAC) pathogenicity, animal models reflecting human progressive MAC lung disease (MAC-LD) are needed. Because there is high genetic and virulence diversity among clinical MAC strains, choosing a suitable strain is an important process for developing a mouse model. In this study, we developed a screening system for virulent strains in mice by combining mixed infection and whole-genome sequencing analysis. This approach is designed on the hypothesis that in vivo virulence of MAC strains can be examined simultaneously by comparing changes in the abundance of strain-specific single-nucleotide variants in the mouse lungs after infection with mixed strains. The identified strains were shown to induce high bacterial burdens and cause extensive peribronchial granuloma resembling the pulmonary pathology of human MAC-LD. The current method will help researchers develop mouse models that reflect human MAC-LD and will lead to further investigation of MAC pathogenicity.

Virulence Mechanisms of Mycobacterium abscessus: Current Knowledge and Implications for Vaccine Design

Mycobacterium abscessus is a member of the non-tuberculous mycobacteria (NTM) group, responsible for chronic infections in individuals with cystic fibrosis (CF) or those otherwise immunocompromised. While viewed traditionally as an opportunistic pathogen, increasing research into M. abscessus in recent years has highlighted its continued evolution into a true pathogen. This is demonstrated through an extensive collection of virulence factors (VFs) possessed by this organism which facilitate survival within the host, particularly in the harsh environment of the CF lung. These include VFs resembling those of other Mycobacteria, and non-mycobacterial VFs, both of which make a notable contribution in shaping M. abscessus interaction with the host. Mycobacterium abscessus continued acquisition of VFs is cause for concern and highlights the need for novel vaccination strategies to combat this pathogen. An effective M. abscessus vaccine must be suitably designed for target populations (i.e., individuals with CF) and incorporate current knowledge on immune correlates of protection against M. abscessus infection. Vaccination strategies must also build upon lessons learned from ongoing efforts to develop novel vaccines for other pathogens, particularly Mycobacterium tuberculosis (M. tb); decades of research into M. tb has provided insight into unconventional and innovative vaccine approaches that may be applied to M. abscessus. Continued research into M. abscessus pathogenesis will be critical for the future development of safe and effective vaccines and therapeutics to reduce global incidence of this emerging pathogen.

Tenets of a holistic approach to drinking water-associated pathogen research, management, and communication

In recent years, drinking water-associated pathogens that can cause infections in immunocompromised or otherwise susceptible individuals (henceforth referred to as DWPI), sometimes referred to as opportunistic pathogens or opportunistic premise plumbing pathogens, have received considerable attention. DWPI research has largely been conducted by experts focusing on specific microorganisms or within silos of expertise. The resulting mitigation approaches optimized for a single microorganism may have unintended consequences and trade-offs for other DWPI or other interests (e.g., energy costs and conservation). For example, the ecological and epidemiological issues characteristic of Legionella pneumophila diverge from those relevant for Mycobacterium avium and other nontuberculous mycobacteria. Recent advances in understanding DWPI as part of a complex microbial ecosystem inhabiting drinking water systems continues to reveal additional challenges: namely, how can all microorganisms of concern be managed simultaneously? In order to protect public health, we must take a more holistic approach in all aspects of the field, including basic research, monitoring methods, risk-based mitigation techniques, and policy. A holistic approach will (i) target multiple microorganisms simultaneously, (ii) involve experts across several disciplines, and (iii) communicate results across disciplines and more broadly, proactively addressing source water-to-customer system management.

Sex, ancestry, senescence, and aging (SAnSA) are stark drivers of nontuberculous mycobacterial pulmonary disease

Nontuberculous mycobacterial (NTM) pulmonary disease (PD) disproportionately affects otherwise healthy, older, Caucasian females. The reasons behind this are likely multifactorial involving several conspiring factors. A variety of factors are thought to contribute to increased susceptibility to NTM in the older adult including exposure to various environmental conditions and contaminants across the lifespan, genetic risk factors, hormonal changes, and immunodeficiency. Independent of sex and ancestry, respiratory muscle atrophy intensifies with age and an aging immune system can show functional decline of macrophages, poor lung migration and homing of dendritic cells, promotion of aberrant pro-inflammatory responses, acceleration of inflammation related to aging, and increased immunosenescence. The purpose of this review is to synthesize the current body of knowledge regarding the roles of sex, ancestry, senescence, and aging (SAnSA) in NTM acquisition and the possible mechanisms involved in NTM PD, highlighting age-related respiratory and immune system changes. We also summarize molecular tools and biomarkers of these fields and contextualize these into the study of NTM PD. Finally, we discuss the relevance of biomarkers described for senescence and aging and senolytic therapies as potentially new adjunctive strategies to reduce the burden of NTM PD.

Combination of anti-glycopeptidolipid-core IgA antibody and clinical features for diagnosing potential nontuberculous mycobacterium pulmonary disease in routine practice

Background:

The anti- Mycobacterium avium complex (MAC) antibody test measures levels of IgA antibody against the glycopeptidolipid (GPL) core in the bacterial cell walls and is a useful clinical indicator of nontuberculous mycobacterium pulmonary disease (NTM-PD). However, it is not currently possible to diagnose the disease using anti-MAC antibodies alone.

Objectives:

The study aim was to assess the efficacy of the combination of anti-MAC antibodies and clinical findings for diagnosing potential NTM-PD.

Methods:

This cross-sectional study included 938 patients tested using the anti-MAC antibody. NTM-PD was diagnosed by multiple positive cultures of the same species in sputum samples. Multivariate logistic regression models were used to identify the clinical factors related to NTM-PD.

Results:

Overall, 19.6% (184/938) of participants were diagnosed with NTM-PD. In multivariate analysis, positive anti-MAC antibodies, low body mass index, absence of malignancy, and cavity-forming lung lesions were significantly associated with NTM-PD at diagnosis. The positive rates of the anti-MAC antibody test were 79.4% (135/170) for MAC and 55.6% (5/9) for Mycobacterium abscessus complex, respectively.

Conclusions:

Bronchoscopic examinations should be performed especially in certain types of individuals from whom sputum samples cannot be obtained. Anti-MAC antibodies are also positive in patients other than those harboring MAC, but the rate may be low because of the different components in GPLs.

Histopathologic Analysis of Surgically Resected Lungs of Patients with Non-tuberculous Mycobacterial Lung Disease: a Retrospective and Hypothesis-generating Study

Non-tuberculous mycobacterial lung disease (NTM-LD) is most commonly due to species within the Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MAbC). Surgical lung resection, typically a lobectomy or segmentectomy, is occasionally undertaken for individuals with recalcitrant but localized NTM-LD. Since the growth characteristics of MAC (slow growers) and MAbC (rapid growers) as well as their drug susceptibility patterns are significantly different, the objective of this study is to characterize and compare the histopathologic features of the resected lungs due to these two major NTM groups. From 1996 to 2017, 356 patients with NTM-LD due to MAC (n=270), MAbC (n=54), or both (n=32) underwent a total of 404 lobar resections (with the lingula counted as a separate lobe) at the University of Colorado Hospital. We analyzed by microscopy the existing surgical lung tissue sections for bronchiolitis, bronchiolectasis, bronchiectasis, non-necrotizing granuloma (airway, parenchymal, and total), necrotizing granuloma (airway, parenchymal, and total), peri-airway fibrosis, fibrous pleuritis, and lymphoid follicles. There were no significant differences in the presence or absence of most of the histopathologic features of surgically removed lungs due to MAC, MAbC, or both MAC + MAbC. However, there were significantly more necrotizing granulomas (airway, parenchymal, and total) and fibrous pleuritis in MAC compared to MAbC lung diseases. Since necrotizing granulomas may be a sign of inadequate control of the infection, we posit that their presence may be an indication of increased chronicity, increased virulence of MAC compared to MAbC, and/or impaired host immunity against the NTM. Futures studies to determine the root cause of such differences in histopathologic findings in MAC versus MAbC lung disease may spawn new leads on differential pathogenic mechanisms with different NTM, with the goal of aiming for more targeted therapy against both the NTM and the lung damage induced by them.

The Trend of TIM3 Expression on T Cells in Patients With Nontuberculous Mycobacterial Lung Disease: From Immune Cell Dysfunction to Clinical Severity

Background

The incidence of nontuberculous mycobacterial lung disease (NTM-LD) is increasing worldwide. Immune exhaustion has been reported in NTM-LD, but T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3), a co-inhibitory receptor on T cells, has been scarcely studied.

Methods

Patients with NTM-LD and healthy controls were prospectively recruited from July 2014 to August 2019 at three tertiary referral centers in Taiwan. We examined TIM3 expression on the T cells from the participants using flow cytometry. TIM3 expression was analyzed for different disease statuses and after treatment. The apoptosis and cytokine profiles were analyzed according to the TIM3 expression.

Results

Among enrolled subjects (47 patients and 46 controls), TIM3 on CD4+ cells (6.44% vs. 4.12%, p = 0.028) and CD8+ cells (18.47% vs. 9.13%, p = 0.003) were higher in NTM-LD patients than in the controls. The TIM3 level on CD4+ and CD8+ T cells was positively associated with T-cell apoptosis in the NTM-LD patients. In stimulating peripheral blood mononuclear cells using PMA plus ionomycin, a high TIM3 level on T cells correlated with low interleukin-2 and tumor necrosis factor-alpha (TNF-α) on CD4+ cells and interferon-gamma and TNF-α on CD8+ T cells. For clinical manifestation, low body mass index (BMI), positive sputum acid-fast smear, and high radiographic score correlated with high TIM3 expression on T cells. After NTM treatment, TIM3+ decreased significantly on CD4+ and CD8+ T cells.

Conclusions

In patients with NTM-LD, TIM3+ expression increased over CD4+ and CD8+ T cells and correlated with cell apoptosis and specific cytokine attenuation. Clinically, TIM3+ T cells increased in patients with low BMI, high disease extent, and high bacilli burden but decreased after treatment.

T-Cell Exhaustion in Mycobacterium tuberculosis and Nontuberculous Mycobacteria Infection: Pathophysiology and Therapeutic Perspectives

Immune exhaustion is a condition associated with chronic infections and cancers, characterized by the inability of antigen-specific T cells to eliminate the cognate antigen. Exhausted T cells display a peculiar phenotypic profile and exclusive functional characteristics. Immune exhaustion has been described in patients with Mycobacterium tuberculosis infection, and cases of tuberculosis reactivation have been reported in those treated with immune checkpoint inhibitors, drugs able to re-establish T-cells’ function. Exhausted T CD8⁺ cells’ profile has also been described in patients with infection due to nontuberculous mycobacteria. In this review, we initially provide an overview of the mechanisms leading to immune exhaustion in patients infected by Mycobacterium tuberculosis and nontuberculous mycobacteria. We then dissect the therapeutic perspectives related to immune checkpoint blockade in patients with these infections.

Respiratory manifestations of Marfan syndrome: a narrative review

Objective

The prevalence of Marfan syndrome (MFS) is estimated to be 1 in 10,000 to 15,000 individuals, but the phenotype of MFS may not be apparent and hence its diagnosis may not be considered by clinicians. Furthermore, the effects of MFS on the lungs and breathing are underrecognized despite the high morbidity that can occur. The objective of this Narrative Review is to delineate the molecular consequences of a defective fibrillin-1 protein and the skeletal and lung abnormalities in MFS that may contribute to respiratory compromise. It is important for clinicians to be cognizant of these MFS-associated respiratory conditions, and a contemporaneous review is needed.

Background

MFS is an autosomal dominant, connective tissue disorder caused by mutations in the FIBRILLIN-1 (FBN1) gene, resulting in abnormal elastic fibers as well as increased tissue availability of transforming growth factor-beta (TGFβ), both of which lead to the protean clinical abnormalities. While these clinical characteristics are most often recognized in the cardiovascular, skeletal, and ocular systems, MFS may also cause significant impairment on the lungs and breathing.

Methods

We searched PubMed for the key words of “Marfan syndrome,” “pectus excavatum,” and “scoliosis” with that of “lung disease,” “breathing”, or “respiratory disease.” The bibliographies of identified articles were further searched for relevant articles not previously identified. Each relevant article was reviewed by one or more of the authors and a narrative review was composed.

Conclusions

Though the classic manifestations of MFS are cardiovascular, skeletal, and ocular, FBN1 gene mutation can induce a variety of effects on the respiratory system, inducing substantial morbidity and potentially increased mortality. These respiratory effects may include chest wall and spinal deformities, emphysema, pneumothorax, sleep apnea, and potentially increased incidence of asthma, bronchiectasis, and interstitial lung disease. Further research into approaches to prevent respiratory complications is needed, but improved recognition of the respiratory complications of MFS is necessary before this research is likely to occur.

Autophagy and Host Defense in Nontuberculous Mycobacterial Infection

Autophagy is critically involved in host defense pathways through targeting and elimination of numerous pathogens via autophagic machinery. Nontuberculous mycobacteria (NTMs) are ubiquitous microbes, have become increasingly prevalent, and are emerging as clinically important strains due to drug-resistant issues. Compared to Mycobacterium tuberculosis (Mtb), the causal pathogen for human tuberculosis, the roles of autophagy remain largely uncharacterized in the context of a variety of NTM infections. Compelling evidence suggests that host autophagy activation plays an essential role in the enhancement of antimicrobial immune responses and controlling pathological inflammation against various NTM infections. As similar to Mtb, it is believed that NTM bacteria evolve multiple strategies to manipulate and hijack host autophagy pathways. Despite this, we are just beginning to understand the molecular mechanisms underlying the crosstalk between pathogen and the host autophagy system in a battle with NTM bacteria. In this review, we will explore the function of autophagy, which is involved in shaping host–pathogen interaction and disease outcomes during NTM infections. These efforts will lead to the development of autophagy-based host-directed therapeutics against NTM infection.

Being Underweight Increases the Risk of Non-Cystic Fibrosis Bronchiectasis in the Young Population: A Nationwide Population-Based Study

Although body mass index (BMI) is a potential risk factor for bronchiectasis in young adults, the association between BMI and incident bronchiectasis has not been well elucidated. This study included 6,329,838 individuals aged 20-40 years from the Korean National Health Insurance Service database 2009-2012 who were followed up until the date of the diagnosis of bronchiectasis, death, or 31 December 2018. We evaluated the incidence and risk of bronchiectasis according to the BMI category. The incidence rate of bronchiectasis increased as BMI decreased in a dose-dependent manner (p for trend <0.01). In multivariable Cox regression analysis, being underweight was an independent risk factor for the development of bronchiectasis, with a hazard ratio of 1.24 (95% confidence interval, 1.19-1.30) compared to being normal weight. In subgroup analysis, the effect of being underweight on the development of bronchiectasis was more evident in males and older individuals (30-40 years) than females and younger individuals (20-29 years), respectively (p for interaction <0.01 for both). These results remained significant in subgroup analysis in which subjects with comorbidities related to being underweight were excluded. Being underweight may be a novel risk factor for the development of bronchiectasis in young adults.

Blood glucose regulation in context of infection

The immune and endocrine systems collectively control homeostasis in the body. The endocrine system ensures that values of essential factors and nutrients such as glucose, electrolytes and vitamins are maintained within threshold values. The immune system resolves local disruptions in tissue homeostasis, caused by pathogens or malfunctioning cells. The immediate goals of these two systems do not always align. The immune system benefits from optimal access to nutrients for itself and restriction of nutrient availability to all other organs to limit pathogen replication. The endocrine system aims to ensure optimal nutrient access for all organs, limited only by the nutrients stores that the body has available. The actual state of homeostatic parameters such as blood glucose levels represents a careful balance based on regulatory signals from the immune and endocrine systems. This state is not static but continuously adjusted in response to changes in the current metabolic needs of the body, the amount of resources it has available and the level of threats it encounters. This balance is maintained by the ability of the immune and endocrine systems to interact and co-regulate systemic metabolism. In context of metabolic disease, this system is disrupted, which impairs functionality of both systems. The failure of the endocrine system to retain levels of nutrients such as glucose within threshold values impairs functionality of the immune system. In addition, metabolic stress of organs in context of obesity is perceived by the immune system as a disruption in local homeostasis, which it tries to resolve by the excretion of factors which further disrupt normal metabolic control. In this chapter, we will discuss how the immune and endocrine systems interact under homeostatic conditions and during infection with a focus on blood glucose regulation. In addition, we will discuss how this system fails in the context of metabolic disease.

A Prospective Cohort Study of Bioavailable 25-Hydroxyvitamin D Levels as a Marker of Vitamin D Status in Nontuberculous Mycobacterial Pulmonary Disease

Research on vitamin D in patients with nontuberculous mycobacterial (NTM) pulmonary disease (PD) is limited. We aimed to compare the vitamin D parameters of patients with NTM-PD to those of a healthy control group, and to assess the possible predictive markers for a clinical response. We prospectively enrolled 53 patients with NTM-PD between January 2014 and December 2016. The clinical data and vitamin D indices, including total, free, bioavailable 25-(OH)D, and vitamin D binding protein (VDBP) genotyping, were measured at baseline and six months after enrollment. An external dataset of 226 healthy controls was compared with the NTM-PD group. The mean age of subjects was 53 years; 54.5% were male. The NTM-PD group was older, predominantly female, and had a lower body mass index (BMI) than the controls. The proportion of patients with vitamin D concentration <50 nmol/L was 52.8% in the NTM-PD group and 54.9% in the control group (p = 0.789). The bioavailable 25-(OH)D concentrations of the NTM-PD group and the controls were similar (6.9 nmol/L vs. 7.6 nmol/L, p = 0.280). In the multivariable analysis, bioavailable 25-(OH)D concentrations were associated with NTM-PD, adjusting for age, sex, BMI, and VDBP levels. Bioavailable 25-(OH)D concentrations were significantly associated with susceptibility to NTM-PD, but not with treatment outcomes. Lower bioavailable 25-(OH)D might be a risk factor for NTM-PD.