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.

Transcriptome analysis of long non-coding RNAs in Mycobacterium avium complex-infected macrophages.

Mycobacterium avium complex (MAC) is a non-tuberculous mycobacterium widely distributed in the environment. Even though MAC infection is increasing in older women and immunocompromised patients, to our knowledge there has been no comprehensive analysis of the MAC-infected host-cell transcriptome-and particularly of long non-coding RNAs (lncRNAs). By using in vitro-cultured primary mouse bone-marrow-derived macrophages (BMDMs) and Cap analysis of gene expression, we analyzed the transcriptional and kinetic landscape of macrophage genes, with a focus on lncRNAs, during MAC infection. MAC infection of macrophages induced the expression of immune/inflammatory response genes and other genes similar to those involved in M1 macrophage activation, consistent with previous reports, although Nos2 (M1 activation) and Arg1 (M2 activation) had distinct expression profiles. We identified 31 upregulated and 30 downregulated lncRNA promoters corresponding respectively to 18 and 26 lncRNAs. Upregulated lncRNAs were clustered into two groups-early and late upregulated-predicted to be associated with immune activation and the immune response to infection, respectively. Furthermore, an Ingenuity Pathway Analysis revealed canonical pathways and upstream transcription regulators associated with differentially expressed lncRNAs. Several differentially expressed lncRNAs reported elsewhere underwent expressional changes upon M1 or M2 preactivation and subsequent MAC infection. Finally, we showed that expressional change of lncRNAs in MAC-infected BMDMs was mediated by toll-like receptor 2, although there may be other mechanisms that sense MAC infection. We identified differentially expressed lncRNAs in MAC-infected BMDMs, revealing diverse features that imply the distinct roles of these lncRNAs in MAC infection and macrophage polarization.

Disseminated Mycobacterium avium Infection with Different Clinical Presentation in Two Human Immunodeficiency Virus-positive Patients.

ABSTRACT: Microorganisms belonging to the Mycobacterium avium complex (MAC) are ubiquitous in the environment, but only a minority of infected persons develop disease. An underlying lung disease or immune deficiency is a prerequisite for clinical manifestation. However, disseminated MAC disease primarily manifests in people living with human immunodeficiency virus (HIV) in the severe immunodeficiency stage with a whole host of clinical symptoms. We present two cases of disseminated M. avium infection in people living with HIV in the stage of severe immunodeficiency. Both patients exhibited distinct disease progression, with the absence of pulmonary symptoms being a common characteristic. The first patient predominantly experienced high fever, accompanied by diarrhea and severe anemia. The normothermia in the second patient was incongruent with the presence of marked cachexia, severe abdominal pain, and magnetic resonance imaging evidence of abdominal lymph node involvement. The causative agent was isolated from both sputum and stools. The patients underwent treatment that comprised aminoglycoside, macrolide, ethambutol, and rifampicin. Although both patients achieved optimal viral suppression of HIV, the immunologic response to antiretroviral therapy was suboptimal. The first patient died in the setting of severe immunodeficiency due to the development of decompensated liver cirrhosis, while the second patient demonstrated a slight reverse course of the disease.

Human mesenchymal stromal cells inhibit Mycobacterium avium replication in clinically relevant models of lung infection.

INTRODUCTION: Novel therapeutic strategies are urgently needed for Mycobacterium avium complex pulmonary disease (MAC-PD). Human mesenchymal stromal cells (MSCs) can directly inhibit MAC growth, but their effect on intracellular bacilli is unknown. We investigated the ability of human MSCs to reduce bacterial replication and inflammation in MAC-infected macrophages and in a murine model of MAC-PD. METHODS: Human monocyte-derived macrophages (MDMs) were infected with M. avium Chester strain and treated with human bone marrow-derived MSCs. Intracellular and extracellular colony-forming units (CFUs) were counted at 72 hours. Six-week-old female balb/c mice were infected by nebulisation of M. avium Chester. Mice were treated with 1×106 intravenous human MSCs or saline control at 21 and 28 days post-infection. Lungs, liver and spleen were harvested 42 days post-infection for bacterial counts. Cytokines were quantified by ELISA. RESULTS: MSCs reduced intracellular bacteria in MDMs over 72 hours (median 35% reduction, p=0.027). MSC treatment increased extracellular concentrations of prostaglandin E2 (PGE2) (median 10.1-fold rise, p=0.002) and reduced tumour necrosis factor-α (median 28% reduction, p=0.025). Blocking MSC PGE2 production by cyclo-oxygenase-2 (COX-2) inhibition with celecoxib abrogated the antimicrobial effect, while this was restored by adding exogenous PGE2. MSC-treated mice had lower pulmonary CFUs (median 18% reduction, p=0.012), but no significant change in spleen or liver CFUs compared with controls. CONCLUSION: MSCs can modulate inflammation and reduce intracellular M. avium growth in human macrophages via COX-2/PGE2 signalling and inhibit pulmonary bacterial replication in a murine model of chronic MAC-PD.

Comparison of treatment outcomes between intermittent and daily regimens in non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease in relation to sputum smear results: a retrospective cohort study.

This study retrospectively analyzed the treatment outcomes of 110 patients with non-cavitary nodular bronchiectatic-type Mycobacterium avium complex pulmonary disease who received intermittent or daily treatment with a three-drug oral antibiotic regimen (i.e., a macrolide, ethambutol, and rifampin) at a tertiary referral center in South Korea. Among these patients, 36 had sputum smear positivity. Of these 36 patients, intermittent treatment led to a lower culture conversion rate than daily treatment [50.0% (8/16) vs 85.0% (17/20), P = 0.034].

Risk factors for clinical progression in patients with pulmonary Mycobacterium avium complex disease without culture-positive sputum: a single-center, retrospective study.

OBJECTIVES: Limited data are available on the progression of pulmonary Mycobacterium avium complex (MAC) disease without culture-positive sputum. The aim of this study was to identify the risk factors associated with clinical progression of pulmonary MAC disease diagnosed by bronchoscopy. METHODS: A single-center, retrospective, observational study was conducted. Pulmonary MAC patients diagnosed by bronchoscopy without culture-positive sputum from January 1, 2013, to December 31, 2017 were analyzed. Clinical progression after diagnosis was defined as having culture-positive sputum at least once or initiation of guideline-based therapy. Then, clinical characteristics were compared between clinically progressed patients and stable patients. RESULTS: Ninety-three pulmonary MAC patients diagnosed by bronchoscopy were included in the analysis. During the 4-year period after diagnosis, 38 patients (40.9%) started treatment, and 35 patients (37.6%) had new culture-positive sputum. Consequently, 52 patients (55.9%) were classified into the progressed group, and 41 patients (44.1%) were classified into the stable group. There were no significant differences between the progressed and the stable groups in age, body mass index, smoking status, comorbidities, symptoms, or species isolated from bronchoscopy. On multivariate analysis, male sex, monocyte to lymphocyte ratio (MLR) ≥ 0.17, and the presence of combined lesions in the middle (lingula) and lower lobes were risk factors for clinical progression. CONCLUSIONS: Some patients with pulmonary MAC disease without culture-positive sputum progress within 4 years. Therefore, pulmonary MAC patients, especially male patients, having higher MLR or lesions in the middle (lingula) and lower lobes might need careful follow-up for a longer time.

Mycobacterium Avium Complex Infection of the Spine in a Patient Without Acquired Immune Deficiency Syndrome: A Case Report and Literature Review.

A 52-year-old patient misdiagnosed with spinal tuberculosis was successfully diagnosed with Mycobacterium avium infection using metagenomic next-generation sequencing and cured with four-drug combination protocol chemotherapy (amikacin, rifampicin, clarithromycin, ethambutol) and spinal fixation.

A marmoset model for Mycobacterium avium complex pulmonary disease.

RATIONALE: Mycobacterium avium complex, is the most common nontuberculous mycobacterial respiratory pathogen in humans. Disease mechanisms are poorly understood due to the absence of a reliable animal model for M. avium complex pulmonary disease. OBJECTIVES: The objectives of this study were to assess the susceptibility, immunologic and histopathologic responses of the common marmoset (Callithrix jacchus) to M. avium complex pulmonary infection. METHODS: 7 adult female marmosets underwent endobronchial inoculation with 108 colony-forming units of M. intracellulare and were monitored for 30 or 60 days. Chest radiograph was assessed at baseline (prior to infection) and at the time of sacrifice (30 days for 3 animals and 60 days for 4 animals), and bronchoalveolar lavage cytokines, histopathology and cultures of the bronchoalveolar lavage, lungs, liver and kidney were assessed at time of sacrifice. Serum cytokines were monitored at baseline and weekly for 30 days for all animals and at 60 days for those alive. Group differences in serum cytokine measurements between those that tested positive versus negative for the M. intracellulare infection were assessed using a series of linear mixed models. MEASUREMENTS AND MAIN RESULTS: Five of seven animals (two at 30 days and three at 60 days of infection) had positive lung cultures for M. intracellulare. Extra-pulmonary cultures were positive in three animals. All animals appeared healthy throughout the study. All five animals with positive lung cultures had radiographic changes consistent with pneumonitis. At 30 days, those with M. intracellulare lung infection showed granulomatous inflammation, while at 60 days there were fewer inflammatory changes but bronchiectasis was noted. The cytokine response in the bronchoalveolar lavage fluid was uniformly greater in the animals with positive M. intracellulare cultures than those without a productive infection, with greater levels at 30-days compared to 60-days. Similarly, serum cytokines were more elevated in the animals that had positive M. intracellulare cultures compared to those without a productive infection, peaking 14-21 days after inoculation. CONCLUSION: Endobronchial instillation of M. intracellulare resulted in pulmonary mycobacterial infection in marmosets with a differential immune response, radiographic and histopathologic abnormalities, and an indolent course consistent with M. avium complex lung infection in humans.

Patient-Reported Symptom and Health-Related Quality-of-Life Validation and Responsiveness During the First 6 Months of Treatment for Mycobacterium avium Complex Pulmonary Disease.

BACKGROUND: Nontuberculous mycobacteria (NTM), predominately Mycobacterium avium complex (MAC), cause chronic pulmonary disease. Improvements in symptoms and health-related quality of life (HRQoL) are important treatment outcomes, but no validated patient-reported outcome (PRO) measure exists. RESEARCH QUESTION: What are the validity and responsiveness of the Quality of Life-Bronchiectasis (QOL-B) questionnaire respiratory symptoms scale and key HRQoL measures during the first 6 months of MAC pulmonary disease (MAC-PD) treatment? STUDY DESIGN AND METHODS: Comparison of Two- vs Three-antibiotic Therapy for Pulmonary Mycobacterium Avium Complex Disease (MAC2v3) is an ongoing randomized, multisite pragmatic clinical trial. Patients with MAC-PD were randomized to azithromycin-based two-drug or three-drug therapy; treatment groups were combined for this analysis. PROs were measured at baseline, 3 months, and 6 months. The QOL-B respiratory symptoms, vitality, physical functioning, health perceptions, and NTM symptom domain scores (on a scale of 0-100, with 100 being best) were analyzed separately. We performed psychometric and descriptive analyses in the population enrolled as of the time of analysis and calculated the minimal important difference (MID) using distribution-based methods. Finally, we evaluated responsiveness using paired t tests and latent growth curve analysis in the subset with longitudinal surveys completed by the time of analysis. RESULTS: The baseline population included 228 patients, of whom 144 had completed longitudinal surveys. Patients predominately were female (82%) and had bronchiectasis (88%); 50% were 70 years of age or older. The respiratory symptoms domain showed good psychometric properties (no floor or ceiling effects; Cronbach's α, 0.85) and an MID of 6.4 to 6.9. Vitality and health perceptions domain scores performed similarly. Respiratory symptoms domain scores improved by 7.8 points (P < .0001) and 7.5 points (P < .0001), and the physical functioning domain score improved by 4.6 points (P < .003) and 4.2 points (P = .01) at 3 and 6 months, respectively. Latent growth curve analysis confirmed a nonlinear, statistically significant improvement in respiratory symptoms and physical functioning domain scores by 3 months. INTERPRETATION: The QOL-B respiratory symptoms and physical functioning scales exhibited good psychometric properties in patients with MAC-PD. Respiratory symptoms scores improved beyond the MID by 3 months after treatment initiation. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03672630; URL: www. CLINICALTRIALS: gov.

Apoptosis Inhibitor of Macrophages Contributes to the Chronicity of Mycobacterium avium Infection by Promoting Foamy Macrophage Formation.

In Mycobacterium avium infections, macrophages play a critical role in the host defense response. Apoptosis inhibitor of macrophage (AIM), also known as CD5L, may represent a novel supportive therapy against various diseases, including metabolic syndrome and infectious diseases. The mechanisms of AIM include modulating lipid metabolism in macrophages and other host cells. We investigated the role of AIM in M. avium infections in vitro and in vivo. In a mouse model of M. avium pneumonia, foamy macrophages were induced 6 wk after infection. The bacteria localized in these macrophages. Flow cytometric analysis also confirmed that the percentage of CD11chighMHCclassIIhigh interstitial and alveolar macrophages, a cell surface marker defined as foamy macrophages, increased significantly after infection. AIM in alveolar lavage fluid and serum gradually increased after infection. Administration of recombinant AIM significantly increased the number of bacteria in the lungs of mice, accompanied by the induction of inflammatory cytokine and iNOS expression. In mouse bone marrow-derived macrophages, the mRNA expression of AIM after M. avium infection and the amount of AIM in the supernatant increased prior to the increase in intracellular bacteria. Infected cells treated with anti-AIM Abs had fewer bacteria and a higher percentage of apoptosis-positive cells than infected cells treated with isotype control Abs. Finally, AIM in the sera of patients with M. avium-pulmonary disease was measured and was significantly higher than in healthy volunteers. This suggests that AIM production is enhanced in M. avium-infected macrophages, increasing macrophage resistance to apoptosis and providing a possible site for bacterial growth.

Biofilm infection of a central venous port-catheter caused by Mycobacterium avium complex in an immunocompetent child with cystic fibrosis.

BACKGROUND: Mycobacterium (M.) chimaera is a non-tuberculous mycobacterium (NTM) that belongs to M. avium complex (MAC). In patients with cystic fibrosis (CF), MAC can cause bronchopulmonary infections that can be prolonged and difficult to treat. MAC infections of sites other than the lungs or central catheters are rare and almost exclusively associated with immunodeficiency. CASE PRESENTATION: We present a case of an 8-year-old CF patient (delF508 homozygous) with recurrent pulmonary exacerbations, gradual clinical deterioration, B-symptoms (fever, fatigue, weight loss, night sweat), elevated transaminases and intermittent detection of M. chimaera in the sputum without radiological signs of NTM-associated lung disease with a central venous port-catheter. Next-generation sequencing (NGS) revealed M. chimaera port infection that was also confirmed by mycobacterial culture. The patient recovered within 4 weeks after removal of the catheter and initiation of MAC targeted antimicrobial therapy. Electron microscopy of the catheter illustrated the presence of mycobacteria in a biofilm. CONCLUSIONS: MAC central venous catheter infection needs to be considered in immunocompetent people. NGS is a valuable tool for rapid identification of rare infections. MAC capability of biofilm formation renders catheter removal the central therapeutic intervention for the clearance of the infection.

Treatment Outcomes of Cavitary Nodular Bronchiectatic-Type Mycobacterium avium Complex Pulmonary Disease.

We investigated the treatment outcomes of patients with cavitary nodular bronchiectatic (C-NB)-type Mycobacterium avium complex (MAC) pulmonary disease (PD) via outcome comparisons between the fibrocavitary (FC) and C-NB types treated with guideline-based therapy (GBT) composed of daily three-drug oral antibiotics and injectable aminoglycoside. Additionally, we analyzed whether treatment with oral antibiotics alone would result in acceptable outcomes for the C-NB type. From 2002 to 2019, patients with cavitary MAC-PD who received three-drug oral antibiotics with or without an injectable aminoglycoside for ≥1 year were retrospectively enrolled at a tertiary referral center in South Korea. We compared the rates of culture conversion at 12 months according to the radiological type and treatment regimen. The overall culture conversion rate at 12 months of 154 patients with cavitary MAC-PD who received GBT was 75.3%. Among them, the culture conversion rates of 114 patients with the C-NB type were higher than that of 40 patients with the FC-type (80.7% versus 60.0%, respectively; P = 0.009). Of 166 patients with the C-NB-type treated with oral medications with or without an injectable drug, 83.7% achieved culture conversion at 12 months. The conversion rates of those who received oral medications alone and those treated with oral medications and an injectable aminoglycoside were similar (90.4% versus 80.7%, respectively; P = 0.117). In conclusion, the culture conversion rates of the patients with C-NB type treated with GBT were significantly higher than those of patients with the FC type. Additionally, the C-NB type could be treated with oral medications alone.

Mycobacterium intracellulare induces a Th17 immune response via M1-like macrophage polarization in canine peripheral blood mononuclear cells.

Mycobacterium avium-intracellulare complex (MAC) is one of the most prevalent pathogenic nontuberculous mycobacteria that cause chronic pulmonary disease. The prevalence of MAC infection has been rising globally in a wide range of hosts, including companion animals. MAC infection has been reported in dogs; however, little is known about interaction between MAC and dogs, especially in immune response. In this study, we investigated the host immune response driven by M. intracellulare using the co-culture system of canine T helper cells and autologous monocyte-derived macrophages (MDMs). Transcriptomic analysis revealed that canine MDMs differentiated into M1-like macrophages after M. intracellulare infection and the macrophages secreted molecules that induced Th1/Th17 cell polarization. Furthermore, canine lymphocytes co-cultured with M. intracellulare-infected macrophages induced the adaptive Th17 responses after 5 days. Taken together, our results indicate that M. intracellulare elicits a Th17 response through macrophage activation in this system. Those findings might help the understanding of the canine immune response to MAC infection and diminishing the potential zoonotic risk in One Health aspect.

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.

Early IL-17A production helps establish Mycobacterium intracellulare infection in mice.

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates of M. intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1-2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0-2 weeks) and late (32-34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs of M. intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover, in vitro data showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells upon M. intracellulare infection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonary M. intracellulare infection in mice, at least in part through MMP-3 production.

A Novel Approach to Extensive Clarithromycin-Resistant Mycobacterium avium Complex Pulmonary Disease.

A 48-year-old woman with extensive clarithromycin-resistant Mycobacterium avium complex pulmonary disease (MAC-PD) was successfully treated by left lower lobectomy and lingulectomy following combination treatment of intravenous/inhaled amikacin plus bronchial occlusion by Endobronchial Watanabe Spigots (EWSs). A left pneumonectomy was initially indicated for removing all the lesions, but the procedure would have been barely tolerated by the patient. However, her preoperative combination treatment sufficiently reduced the lesions requiring resection to allow surgical preservation of the left upper division. This novel approach might be promising for patients with Mycobacterium avium complex lung disease whose pulmonary reserve will not allow an extensive parenchymal resection.

Laryngeal Injury Due to Amikacin Inhalation for Refractory Mycobacterium avium Complex Infection.

Inhaled antibiotics have long been used for chronic lung infections, especially in patients with cystic fibrosis and increasingly for non-cystic fibrosis bronchiectasis. Amikacin liposome inhalation suspension (ALIS) has emerged as a promising treatment for Mycobacterium avium complex infection refractory to oral antibiotics. However, despite its efficacy, nearly one-half of patients in phase II and III trials experienced dysphonia as a treatment-associated adverse effect. Here, we describe a patient who experienced severe, acute-onset laryngitis while receiving ALIS for refractory M avium complex infection, prompting discontinuation of ALIS therapy. This is the first report directly describing vocal fold injury due to such therapy. Given the high frequency of dysphonia reported with ALIS, this case highlights the potential severity of laryngeal toxicity, the importance of coordination of care for patients receiving inhaled antibiotics for chronic pulmonary disease, and the need for better insight into mechanisms of toxicity.

Donor-defined mesenchymal stem cell antimicrobial potency against nontuberculous mycobacterium.

Chronic nontuberculous mycobacterial infections with Mycobacterium avium and Mycobacterium intracellulare complicate bronchiectasis, chronic obstructive airway disease, and the health of aging individuals. These insidious intracellular pathogens cause considerable morbidity and eventual mortality in individuals colonized with these bacteria. Current treatment regimens with antibiotic macrolides are both toxic and often inefficient at providing infection resolution. In this article, we demonstrate that human marrow-derived mesenchymal stem cells are antimicrobial and anti-inflammatory in vitro and in the context of an in vivo sustained infection of either M. avium and/or M. intracellulare.