Huang YJ, Lynch SV. The emerging relationship between the airway microbiota and chronic respiratory disease: clinical implications

Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California San Francisco, 513 Parnassus Avenue, Med Sci S357, San Francisco, CA 94143, USA.
Expert Review of Respiratory Medicine 12/2011; 5(6):809-21. DOI: 10.1586/ers.11.76
Source: PubMed


Until recently, relationships between evidence of colonization or infection by specific microbial species and the development, persistence or exacerbation of pulmonary disease have informed our opinions of airway microbiology. However, recent applications of culture-independent tools for microbiome profiling have revealed a more diverse microbiota than previously recognized in the airways of patients with chronic pulmonary disease. New evidence indicates that the composition of airway microbiota differs in states of health and disease and with severity of symptoms and that the microbiota, as a collective entity, may contribute to pathophysiologic processes associated with chronic airway disease. Here, we review the evolution of airway microbiology studies of chronic pulmonary disease, focusing on asthma, chronic obstructive pulmonary disease and cystic fibrosis. Building on evidence derived from traditional microbiological approaches and more recent culture-independent microbiome studies, we discuss the implications of recent findings on potential microbial determinants of respiratory health or disease.

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Available from: Susan V Lynch
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    • "Recent studies show that the lower respiratory tract is a microbial reservoir in HIV-infected individuals rather than being a sterile environment as observed in healthy non-infected subjects and this may contribute to recurrent pneumonia and COPD in HIV-infected patients (Huang et al., 2011; Iwai et al., 2012). Moreover, the lung microbiome in People living with HIV is similar to that observed in COPD and cystic fibrosis (Huang and Lynch, 2011). Impaired MCC, is primarily responsible for microbial colonization of airways in chronic airway diseases like COPD and cystic fibrosis (Sethi, 2000; Livraghi and Randell, 2007). "
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    ABSTRACT: Impaired mucociliary clearance (MCC) is a hallmark of acquired chronic airway diseases like chronic bronchitis associated with chronic obstructive pulmonary disease (COPD) and asthma. This manifests as microbial colonization of the lung consequently leading to recurrent respiratory infections. People living with HIV demonstrate increased incidence of these chronic airway diseases. Bacterial pneumonia continues to be an important comorbidity in people living with HIV even though anti-retroviral therapy has succeeded in restoring CD4+ cell counts. People living with HIV demonstrate increased microbial colonization of the lower airways. The microbial flora is similar to that observed in diseases like cystic fibrosis and COPD suggesting that mucociliary dysfunction could be a contributing factor to the increased incidence of chronic airway diseases in people living with HIV. The three principal components of the MCC apparatus are, a mucus layer, ciliary beating, and a periciliary airway surface liquid (ASL) layer that facilitates ciliary beating. Cystic fibrosis transmembrane conductance regulator (CFTR) plays a pivotal role in regulating the periciliary ASL. HIV proteins can suppress all the components of the MCC apparatus by increasing mucus secretion and suppressing CFTR function. This can decrease ASL height leading to suppressed ciliary beating. The effects of HIV on MCC are exacerbated when combined with other aggravating factors like smoking or inhaled substance abuse, which by themselves can suppress one or more components of the MCC system. This review discusses the pathophysiological mechanisms that lead to MCC suppression in people living with HIV who also smoke tobacco or abuse illicit drugs.
    Full-text · Article · Nov 2015 · Frontiers in Microbiology
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    • "Recent studies have shown that an unhealthy status of the respiratory microbiome persists in high-risk populations, such as infants, the elderly and patients with COPD, CF or bronchiectasis , in whom the microbial communities are much less diversified than those found in healthy individuals [27] [28] [29] [30] [31] [32]. Diversity is a major factor that promotes system stability [33], loss of diversity thus lessens the protective effects of the microbiome and renders patients vulnerable to infection. "
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    ABSTRACT: The human pharyngeal microbiome, which resides at the juncture of digestive and respiratory tracts, may have an active role in the prevention of respiratory tract infections, similar to the actions of the intestinal microbiome against enteric infections. Recent studies have demonstrated that the pharyngeal microbiome comprises an abundance of bacterial species that interact with the local epithelial and immune cells, and together, they form a unique micro-ecological system. Most of the microbial species in microbiomes are obligate symbionts constantly adapting to their unique surroundings. Indigenous commensal species are capable of both maintaining dominance and evoking host immune responses to eliminate invading species. Temporary damage to the pharyngeal microbiome due to the impaired local epithelia is also considered an important predisposing risk factor for infections. Therefore, reinforcement of microbiome homeostasis to prevent invasion of infection-prone species would provide a novel treatment strategy in addition to antibiotic treatment and vaccination. Hence continued research efforts on evaluating probiotic treatment and developing appropriate procedures are necessary to both prevent and treat respiratory infections.
    Full-text · Article · Jun 2014 · Genomics Proteomics & Bioinformatics
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    • "It has been suggested that the fungal colonization could contribute to or trigger - as do other virus infections (HPV, CMV etc) - pathophysiologic processes associated with lung cancer [19]. However, while there is evidence of the involvement of specific fungal species in asthma, chronic obstructive pulmonary disease (COPD) [20,21] and cystic fibrosis (CF) [21-24], little is known of the airway fungal microbiota in the pathogenesis of lung cancer [19]. "
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    ABSTRACT: Airways of lung cancer patients are often colonized by fungi. Some of these colonizing fungi, under particular conditions, produce cancerogenic mycotoxins. Given the recent interest in the infective origin of lung cancer, with this preliminary study we aim to give our small contribution to this field of research by analysing the fungal microbiome of the exhaled breath condensate of lung cancer patients from Puglia, a region of Italy. We enrolled 43 lung cancer patients and 21 healthy subjects that underwent exhaled breath condensate and bronchial brushing collection. The fungal incidence and nature of sample collected were analysed by using a selected media for Aspergillus species. For the first time we were able to analyse the fungal microbioma of the exhaled breath condensate. 27.9% of lung cancer patients showed a presence of Aspergillus niger, or A. ochraceus or Penicillium ssp. while none of the healthy subjects did so. The results confirmed the high percentage of fungal colonization of the airways of lung cancer patients from Puglia, suggesting the need to conduct further analyses in this field in order to evaluate the exact pathogenetic role of these fungi in lung cancer as well as to propose efficient, empirical therapy.
    Full-text · Article · Feb 2014 · BMC Pulmonary Medicine
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