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Abstract
Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.
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Affiliation(s)
- Margaret McCort
- Albert Einstein College of Medicine, Division of Infectious Disease, New York, NY, USA
| | - Erica MacKenzie
- University of Chicago Medicine, Section of Infectious Diseases and Global Health, Chicago, IL, USA
| | - Kenneth Pursell
- University of Chicago Medicine, Section of Infectious Diseases and Global Health, Chicago, IL, USA
| | - David Pitrak
- University of Chicago Medicine, Section of Infectious Diseases and Global Health, Chicago, IL, USA
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Manos J. Current and Emerging Therapies to Combat Cystic Fibrosis Lung Infections. Microorganisms 2021; 9:1874. [PMID: 34576767 DOI: 10.3390/microorganisms9091874] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/30/2022] Open
Abstract
The ultimate aim of any antimicrobial treatment is a better infection outcome for the patient. Here, we review the current state of treatment for bacterial infections in cystic fibrosis (CF) lung while also investigating potential new treatments being developed to see how they may change the dynamics of antimicrobial therapy. Treatment with antibiotics coupled with regular physical therapy has been shown to reduce exacerbations and may eradicate some strains. Therapies such as hypertonic saline and inhaled PulmozymeTM (DNase-I) improve mucus clearance, while modifier drugs, singly and more successfully in combination, re-open certain mutant forms of the cystic fibrosis transmembrane conductance regulator (CFTR) to enable ion passage. No current method, however, completely eradicates infection, mainly due to bacterial survival within biofilm aggregates. Lung transplants increase lifespan, but reinfection is a continuing problem. CFTR modifiers normalise ion transport for the affected mutations, but there is conflicting evidence on bacterial clearance. Emerging treatments combine antibiotics with novel compounds including quorum-sensing inhibitors, antioxidants, and enzymes, or with bacteriophages, aiming to disrupt the biofilm matrix and improve antibiotic access. Other treatments involve bacteriophages that target, infect and kill bacteria. These novel therapeutic approaches are showing good promise in vitro, and a few have made the leap to in vivo testing.
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Permpalung N, Bazemore K, Chiang TPY, Mathew J, Barker L, Nematollahi S, Cochran W, Sait AS, Avery RK, Shah PD. Impact of COVID-19 on Lung Allograft and Clinical Outcomes in Lung Transplant Recipients: A Case-control Study. Transplantation 2021; 105:2072-2079. [PMID: 34075005 DOI: 10.1097/tp.0000000000003839] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The impacts of COVID-19 on lung allograft function, rejection, secondary infection, and clinical outcomes in lung transplant recipients (LTRs) remain unknown. METHODS A 1:2 matched case-control study was performed to evaluate rehospitalization, lung allograft function, and secondary infections up to 90 d after COVID-19 diagnosis (or index dates for controls). RESULTS Twenty-four LTRs with COVID-19 (cases) and 48 controls were identified. Cases and controls had similar baseline characteristics and lung allograft function. LTRs with COVID-19 had higher incidence of secondary bacterial infection (29.2% versus 6.3%, P = 0.008), readmission (29.2% versus 10.4%, P = 0.04), and for-cause bronchoscopy (33.3% versus 12.5%, P = 0.04) compared with controls. At d 90, mortality in cases versus controls was 8.3% versus 2.1% (P = 0.21), incidence of invasive fungal infections in cases versus controls was 20.8% versus 8.3% (P = 0.13) and forced expiratory volume in 1 s (FEV1) decline ≥10% from baseline occurred in 19% of cases versus 12.2% of controls (P = 0.46). No acute cellular rejection, acute antibody-mediated rejection, or new donor-specific anti-HLA antibodies were observed among cases or controls within 90 d post index date. CONCLUSIONS We found LTRs with COVID-19 were at risk to develop secondary infections and rehospitalization post COVID-19, compared with controls. While we did not observe post viral acute cellular rejection or antibody-mediated rejection, further studies are needed to understand if LTRs with COVID-19 who did not recover baseline lung function within 90 d have developed chronic lung allograft dysfunction stage progression.
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Affiliation(s)
- Nitipong Permpalung
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
- Division of Mycology, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Katrina Bazemore
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Teresa Po-Yu Chiang
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Joby Mathew
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Lindsay Barker
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Saman Nematollahi
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Willa Cochran
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Afrah S Sait
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Robin K Avery
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Pali D Shah
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
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Eskind CC, Shilts MH, Shaver CM, Das SR, Satyanarayana G. The respiratory microbiome after lung transplantation: Reflection or driver of respiratory disease? Am J Transplant 2021; 21:2333-2340. [PMID: 33749996 PMCID: PMC8926303 DOI: 10.1111/ajt.16568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 02/17/2021] [Accepted: 03/05/2021] [Indexed: 01/25/2023]
Abstract
With the introduction of high-throughput sequencing methods, our understanding of the human lower respiratory tract's inhabitants has expanded significantly in recent years. What is now termed the "lung microbiome" has been described for healthy patients, as well as people with chronic lung diseases and lung transplants. The lung microbiome of lung transplant recipients (LTRs) has proven to be unique compared with nontransplant patients, with characteristic findings associated with disease states, such as pneumonia, acute rejection, and graft failure. In this review, we summarize the current understanding of the lung microbiome in LTRs, not only focusing on bacteria but also highlighting key findings of the viral and the fungal community. Based on our knowledge of the lung microbiome in LTRs, we propose multiple opportunities for clinical use of the microbiome to improve outcomes in this population.
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Affiliation(s)
- Caroline Cohen Eskind
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Meghan H. Shilts
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ciara M. Shaver
- Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Suman R. Das
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Pathology Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Otolaryngology and Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Gowri Satyanarayana
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Bazemore K, Rohly M, Permpalung N, Yu K, Timofte I, Brown AW, Orens J, Iacono A, Nathan SD, Avery RK, Valantine H, Agbor-Enoh S, Shah PD. Donor derived cell free DNA% is elevated with pathogens that are risk factors for acute and chronic lung allograft injury. J Heart Lung Transplant 2021; 40:1454-1462. [PMID: 34344623 DOI: 10.1016/j.healun.2021.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Acute and chronic forms of lung allograft injury are associated with specific respiratory pathogens. Donor-derived cell free DNA (ddcfDNA) has been shown to be elevated with acute lung allograft injury and predictive of long-term outcomes. We examined the %ddcfDNA values at times of microbial isolation from bronchoalveolar lavage (BAL). METHODS Two hundred and six BAL samples from 51 Lung Transplant Recipients (LTRs) with concurrently available plasma %ddcfDNA were analyzed along with microbiology and histopathology. Microbial species were grouped into bacterial, fungal, and viral and "higher risk" and "lower risk" cohorts based on historical association with downstream allograft dysfunction. Analyses were performed to determine pathogen category association with %ddcfDNA, independent of inter-subject variability. RESULTS Presence of microbial isolates in BAL was not associated with elevated %ddcfDNA compared to samples without isolates. However, "higher risk" bacterial and viral microbes showed greater %ddcfDNA values than lower risk species (1.19% vs. 0.65%, p < 0.01), independent of inter-subject variability. Histopathologic abnormalities concurrent with pathogen isolation were associated with higher %ddcfDNA compared to isolation episodes with normal histopathology (medians 1.23% and 0.66%, p = 0.05). Assessments showed no evidence of correlation between histopathology or bronchoscopy indication and presence of higher risk vs. lower risk pathogens. CONCLUSION %ddcfDNA is higher among cases of microbial isolation with concurrent abnormal histopathology and with isolation of higher risk pathogens known to increase risk of allograft dysfunction. Future studies should assess if %ddcfDNA can be used to stratify pathogens for risk of CLAD and identify pathogen associated injury prior to histopathology.
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Affiliation(s)
- Katrina Bazemore
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore
| | | | - Nitipong Permpalung
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore
| | - Kai Yu
- National Cancer Institute, National Institutes of Health, Rockville, Maryland
| | - Irina Timofte
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; Department of Medicine, University of Maryland, College Park, Maryland
| | - A Whitney Brown
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; Advanced Lung Disease and Transplant Program, Inova Heart and Vascular Institute, Inova Fairfax Hospital, Falls Church, Virginia
| | - Jonathan Orens
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore; Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland
| | - Aldo Iacono
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; Department of Medicine, University of Maryland, College Park, Maryland
| | - Steven D Nathan
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; Department of Medicine, University of Maryland, College Park, Maryland
| | - Robin K Avery
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore
| | - Hannah Valantine
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Sean Agbor-Enoh
- Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland; National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland.
| | - Pali D Shah
- Division of Pulmonary and Critical Care, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore; Genomic Research Alliance for Transplantation (GRAfT), Bethesda, Maryland.
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Divithotawela C, Pham A, Bell PT, Ledger EL, Tan M, Yerkovich S, Grant M, Hopkins PM, Wells TJ, Chambers DC. Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies. J Heart Lung Transplant 2021; 40:951-959. [PMID: 34226118 DOI: 10.1016/j.healun.2021.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 04/21/2021] [Accepted: 05/24/2021] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease. METHODS In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation. RESULTS cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses. CONCLUSIONS Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.
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Affiliation(s)
| | - Amy Pham
- The University of Queensland, Diamantina Institute, The University of Queensland, Wooloongabba, Australia
| | - Peter T Bell
- Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia
| | - Emma L Ledger
- The University of Queensland, Diamantina Institute, The University of Queensland, Wooloongabba, Australia
| | - Maxine Tan
- Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, Australia
| | | | - Michelle Grant
- Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, Australia
| | - Peter M Hopkins
- Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia
| | - Timothy J Wells
- The University of Queensland, Diamantina Institute, The University of Queensland, Wooloongabba, Australia; Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Australia
| | - Daniel C Chambers
- Queensland Lung Transplant Service, The Prince Charles Hospital, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia.
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Amubieya O, Ramsey A, DerHovanessian A, Fishbein GA, Lynch JP, Belperio JA, Weigt SS. Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies. Semin Respir Crit Care Med 2021; 42:392-410. [PMID: 34030202 DOI: 10.1055/s-0041-1729175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.
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Affiliation(s)
- Olawale Amubieya
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Allison Ramsey
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Ariss DerHovanessian
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Gregory A Fishbein
- Department of Pathology, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Joseph P Lynch
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - John A Belperio
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
| | - S Samuel Weigt
- Division of Pulmonary, Critical Care Medicine, Allergy, and Clinical Immunology, Department of Internal Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, California
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Kennedy J, Walker A, Ellender CM, Steinfort K, Martin C, Smith C, Snell G, Whitford H. Outcomes Of Non-Cystic Fibrosis Related Bronchiectasis Post Lung Transplantation. Intern Med J 2021; 52:995-1001. [PMID: 33656222 DOI: 10.1111/imj.15256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Lung transplantation is a recognised treatment for end-stage lung disease due to bronchiectasis. Non-CF bronchiectasis and CF are often combined into one cohort, however outcomes for non-CF bronchiectasis patients varies between centres, and in comparison to those for CF. AIMS To compare lung transplantation mortality and morbidity of bronchiectasis (non-CF) patients to those with CF and other indications. METHODS Retrospective analysis of patients undergoing lung transplantation between 01 January 2008-31 December 2013. Time to and cause of lung allograft loss was censored on 01 April 2018. A case-note review was conducted on a sub-group of 78 patients, to analyse hospital admissions as a marker of morbidity. RESULTS 341 patients underwent lung transplantation, 22 (6%) had bronchiectasis compared to 69 (20%) with CF. The 5-year survival for the bronchiectasis group was 32%, compared to CF 69%, obstructive lung disease (OLD) 64%, pulmonary hypertension 62% and ILD 55% (p = 0.008). Lung allograft loss due to CLAD with predominant infection was significantly higher in the bronchiectasis group at 2 years. The rate of acute admissions was 2.24 higher in the bronchiectasis group when compared to OLD (p = 0.01). Patients with bronchiectasis spent 45.81 days in hospital per person year after transplantation compared with 18.21 days for CF. CONCLUSIONS Bronchiectasis patients in this study had a lower 5-year survival and poorer outcomes in comparison to other indications including CF. Bronchiectasis should be considered a separate entity to CF in survival analysis. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jessica Kennedy
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia.,School of Medicine, Dentistry and Health Science, Melbourne University, Melbourne, Australia.,Department of Respiratory and Sleep Medicine, Austin Hospital, Melbourne, Australia
| | - Anne Walker
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia.,Department of Thoracic Medicine, Royal Adelaide Hospital, South Australia, Australia
| | - Claire M Ellender
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia.,Department of Respiratory & Sleep Medicine, Princess Alexandra Hospital, Brisbane, Australia
| | - Kate Steinfort
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia
| | - Catherine Martin
- Pubic Health and Preventative Medicine, Monash University, Melbourne, Australia
| | - Catherine Smith
- Pubic Health and Preventative Medicine, Monash University, Melbourne, Australia
| | - Gregory Snell
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia
| | - Helen Whitford
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Hospital, Melbourne, Australia
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Combs MP, Wheeler DS, Luth JE, Falkowski NR, Walker NM, Erb-Downward JR, Lama VN, Dickson RP. Lung microbiota predict chronic rejection in healthy lung transplant recipients: a prospective cohort study. Lancet Respir Med 2021; 9:601-12. [PMID: 33460570 DOI: 10.1016/S2213-2600(20)30405-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND Alterations in the respiratory microbiome are common in chronic lung diseases, correlate with decreased lung function, and have been associated with disease progression. The clinical significance of changes in the respiratory microbiome after lung transplant, specifically those related to development of chronic lung allograft dysfunction (CLAD), are unknown. The aim of this study was to evaluate the effect of lung microbiome characteristics in healthy lung transplant recipients on subsequent CLAD-free survival. METHODS We prospectively studied a cohort of lung transplant recipients at the University of Michigan (Ann Arbor, MI, USA). We analysed characteristics of the respiratory microbiome in acellular bronchoalveolar lavage fluid (BALF) collected from asymptomatic patients during per-protocol surveillance bronchoscopy 1 year after lung transplantation. For our primary endpoint, we evaluated a composite of development of CLAD or death at 500 days after the 1-year surveillance bronchoscopy. Our primary microbiome predictor variables were bacterial DNA burden (total 16S rRNA gene copies per mL of BALF, quantified via droplet digital PCR) and bacterial community composition (determined by bacterial 16S rRNA gene sequencing). Patients' lung function was followed serially at least every 3 months by spirometry, and CLAD was diagnosed according to International Society of Heart and Lung Transplant 2019 guidelines. FINDINGS We analysed BALF from 134 patients, collected during 1-year post-transplant surveillance bronchoscopy between Oct 21, 2005, and Aug 25, 2017. Within 500 days of follow-up from the time of BALF sampling, 24 (18%) patients developed CLAD, five (4%) died before confirmed development of CLAD, and 105 (78%) patients remained CLAD-free with complete follow-up. Lung bacterial burden was predictive of CLAD development or death within 500 days of the surveillance bronchoscopy, after controlling for demographic and clinical factors, including immunosuppression and bacterial culture results, in a multivariable survival model. This relationship was evident when burden was analysed as a continuous variable (per log10 increase in burden, HR 2·49 [95% CI 1·38-4·48], p=0·0024) or by tertiles (middle vs lowest bacterial burden tertile, HR 4·94 [1·25-19·42], p=0·022; and highest vs lowest, HR 10·56 [2·53-44·08], p=0·0012). In patients who developed CLAD or died, composition of the lung bacterial community significantly differed to that in patients who survived and remained CLAD-free (on permutational multivariate analysis of variance, p=0·047 at the taxonomic level of family), although differences in community composition were associated with bacterial burden. No individual bacterial taxa were definitively associated with CLAD development or death. INTERPRETATION Among asymptomatic lung transplant recipients at 1-year post-transplant, increased lung bacterial burden is predictive of chronic rejection and death. The lung microbiome represents an understudied and potentially modifiable risk factor for lung allograft dysfunction. FUNDING US National Institutes of Health, Cystic Fibrosis Foundation, Brian and Mary Campbell and Elizabeth Campbell Carr research gift fund.
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