Metabolites from intestinal microbiota are key determinants of host-microbe mutualism and, consequently, the health or disease of the intestinal tract. However, whether such host-microbe crosstalk ...influences inflammation in peripheral tissues, such as the lung, is poorly understood. We found that dietary fermentable fiber content changed the composition of the gut and lung microbiota, in particular by altering the ratio of Firmicutes to Bacteroidetes. The gut microbiota metabolized the fiber, consequently increasing the concentration of circulating short-chain fatty acids (SCFAs). Mice fed a high-fiber diet had increased circulating levels of SCFAs and were protected against allergic inflammation in the lung, whereas a low-fiber diet decreased levels of SCFAs and increased allergic airway disease. Treatment of mice with the SCFA propionate led to alterations in bone marrow hematopoiesis that were characterized by enhanced generation of macrophage and dendritic cell (DC) precursors and subsequent seeding of the lungs by DCs with high phagocytic capacity but an impaired ability to promote T helper type 2 (TH2) cell effector function. The effects of propionate on allergic inflammation were dependent on G protein-coupled receptor 41 (GPR41, also called free fatty acid receptor 3 or FFAR3), but not GPR43 (also called free fatty acid receptor 2 or FFAR2). Our results show that dietary fermentable fiber and SCFAs can shape the immunological environment in the lung and influence the severity of allergic inflammation.
Changes in the pulmonary microbiota are associated with progressive respiratory diseases including chronic obstructive pulmonary disease (COPD). Whether there is a causal relationship between these ...changes and disease progression remains unknown.
To investigate the link between an altered microbiota and disease, we used a murine model of chronic lung inflammation that is characterized by key pathological features found in COPD and compared responses in specific pathogen-free (SPF) mice and mice depleted of microbiota by antibiotic treatment or devoid of a microbiota (axenic).
Mice were challenged with LPS/elastase intranasally over 4 weeks, resulting in a chronically inflamed and damaged lung. The ensuing cellular infiltration, histological damage, and decline in lung function were quantified.
Similar to human disease, the composition of the pulmonary microbiota was altered in diseased animals. We found that the microbiota richness and diversity were decreased in LPS/elastase-treated mice, with an increased representation of the genera Pseudomonas and Lactobacillus and a reduction in Prevotella. Moreover, the microbiota was implicated in disease development as mice depleted, or devoid, of microbiota exhibited an improvement in lung function, reduced inflammation, and lymphoid neogenesis. The absence of microbial cues markedly decreased the production of IL-17A, whereas intranasal transfer of fluid enriched with the pulmonary microbiota isolated from diseased mice enhanced IL-17A production in the lungs of antibiotic-treated or axenic recipients. Finally, in mice harboring a microbiota, neutralizing IL-17A dampened inflammation and restored lung function.
Collectively, our data indicate that host-microbial cross-talk promotes inflammation and could underlie the chronicity of inflammatory lung diseases.
In lung transplant recipients, long-term graft survival relies on the control of inflammation and tissue remodeling to maintain graft functionality and avoid chronic lung allograft dysfunction. ...Although advances in clinical practice have improved transplant success, the mechanisms by which the balance between inflammation and remodeling is maintained are largely unknown.
To assess whether host-microbe interactions in the transplanted lung determine the immunologic tone of the airways, and consequently could impact graft survival.
Microbiota DNA and host total RNA were isolated from 203 bronchoalveolar lavages obtained from 112 patients post-lung transplantation. Microbiota composition was determined using 16S ribosomal RNA analysis, and expression of a set of genes involved in prototypic macrophage functions was quantified using real-time quantitative polymerase chain reaction.
We show that the characteristics of the pulmonary microbiota aligned with distinct innate cell gene expression profiles. Although a nonpolarized activation was associated with bacterial communities consisting of a balance between proinflammatory (e.g., Staphylococcus and Pseudomonas) and low stimulatory (e.g., Prevotella and Streptococcus) bacteria, "inflammatory" and "remodeling" profiles were linked to bacterial dysbiosis. Mechanistic assays provided direct evidence that bacterial dysbiosis could lead to inflammatory or remodeling profiles in macrophages, whereas a balanced microbial community maintained homeostasis.
The crosstalk between bacterial communities and innate immune cells potentially determines the function of the transplanted lung offering novel pathways for intervention strategies.
Barrier integrity is central to the maintenance of healthy immunological homeostasis. Impaired skin barrier function is linked with enhanced allergen sensitization and the development of diseases ...such as atopic dermatitis (AD), which can precede the development of other allergic disorders, for example, food allergies and asthma. Epidemiological evidence indicates that children suffering from allergies have lower levels of dietary fibre-derived short-chain fatty acids (SCFA). Using an experimental model of AD-like skin inflammation, we report that a fermentable fibre-rich diet alleviates systemic allergen sensitization and disease severity. The gut-skin axis underpins this phenomenon through SCFA production, particularly butyrate, which strengthens skin barrier function by altering mitochondrial metabolism of epidermal keratinocytes and the production of key structural components. Our results demonstrate that dietary fibre and SCFA improve epidermal barrier integrity, ultimately limiting early allergen sensitization and disease development.
The Graphical Abstract was designed using Servier Medical Art images (https://smart.servier.com).
Display omitted
Abstract
Introduction: Emerging evidence suggests that long-term pulmonary symptoms and functional impairment occurs in a proportion of individuals following SARS-CoV-2 infection. Although the ...proportion of affected patients remains to be determined, physicians are increasingly being confronted with patients reporting respiratory symptoms and impairment beyond the acute phase of COVID-19. In face of limited evidence, the Swiss Society for Pulmonology established a working group to address this area of unmet need and formulated diagnostic and treatment recommendations for the care of patients with pulmonary long COVID (LC). Method: The Swiss COVID Lung Study group and Swiss Society for Pulmonology (SSP) formulated 13 questions addressing the diagnosis and treatment of pulmonary LC. A survey within the SSP special interest groups involved in care of LC patients was conducted in Switzerland. A CORE process/Delphi-like process was used to formulate recommendations. Forty experienced pulmonologists replied to the first survey and 22 completed the second follow-up survey. Agreement of ≥70% consensus led to formulation of a recommendation. Results: The participants in the survey reached consensus and formulated a strong recommendation for regarding the following points. Patients hospitalized for COVID-19 should have a pulmonary assessment including pulmonary function tests. Symptomatic subjects affected by COVID-19, including those with mild disease, should benefit from a pulmonary follow-up. Persistent respiratory symptoms after COVID-19 should be investigated by a pulmonary follow-up including plethysmography, diffusion capacity measurement, and blood gases analysis. Individuals having suffered from COVID-19 and who present with persistent respiratory symptoms should be offered a rehabilitation. Additional questions were given moderateor weak recommendations for. The panel did not reach sufficient consensus for pharmacological therapy (e.g., therapy specifically targeting lung fibrosis) to formulate recommendations for LC drug treatment. Conclusion: The formulated recommendations should serve as an interim guidance to facilitate diagnosis and treatment of patients with pulmonary LC. As new evidence emerges, these recommendations may need to be adapted.
There is accumulating evidence that the lower airway microbiota impacts lung health. However, the link between microbial community composition and lung homeostasis remains elusive. We combine ...amplicon sequencing and bacterial culturing to characterize the viable bacterial community in 234 longitudinal bronchoalveolar lavage samples from 64 lung transplant recipients and establish links to viral loads, host gene expression, lung function, and transplant health. We find that the lung microbiota post-transplant can be categorized into four distinct compositional states, 'pneumotypes'. The predominant 'balanced' pneumotype is characterized by a diverse bacterial community with moderate viral loads, and host gene expression profiles suggesting immune tolerance. The other three pneumotypes are characterized by being either microbiota-depleted, or dominated by potential pathogens, and are linked to increased immune activity, lower respiratory function, and increased risks of infection and rejection. Collectively, our findings establish a link between the lung microbial ecosystem, human lung function, and clinical stability post-transplant.
The Global Initiative for Asthma (GINA) is a network of individuals, organizations, and public health officials that was established to disseminate information about the care of patients with asthma ...and to improve asthma care. The GINA ("Global Strategy for Asthma Management and Prevention") report has been updated annually since 2002. Due to new knowledge and therapeutic development in the field, the Swiss Respiratory Society felt the need to provide a new document that is based on both the available literature and the recommendations of the 2016 GINA report. Key new features of the 2016 GINA report include a "new" definition of asthma, underscoring its heterogeneous nature, and the core elements of variable symptoms and variable expiratory airflow limitation; the importance of confirming the diagnosis of asthma in order to minimize both under- and overtreatment; practical tools for the assessment of symptom control and risk factors for adverse outcomes; a comprehensive approach to asthma management that acknowledges the foundational role of inhaled corticosteroid therapy, but also provides a framework for individualizing patient care; an emphasis on maximizing the benefit of available medications by addressing common problems such as incorrect inhaler technique and poor adherence; a continuum of care for worsening asthma, starting with early self-management and progressing to primary care or acute care management; and diagnosis of the asthma/chronic obstructive pulmonary disease overlap syndrome. This document is meant to advice the key stakeholders on the diagnosis and management of asthma and highlights the need to individualize the care of each and every asthmatic patient.
The Airway Microbiome and Disease Marsland, Benjamin J., PhD; Yadava, Koshika, MSc; Nicod, Laurent P., MD
Chest,
08/2013, Letnik:
144, Številka:
2
Journal Article
Recenzirano
Although traditionally thought to be sterile, accumulating evidence now supports the concept that our airways harbor a microbiome. Thus far, studies have focused upon characterizing the bacterial ...constituents of the airway microbiome in both healthy and diseased lungs, but what perhaps provides the greatest impetus for the exploration of the airway microbiome is that different bacterial phyla appear to dominate diseased as compared with healthy lungs. As yet, there is very limited evidence supporting a functional role for the airway microbiome, but continued research in this direction is likely to provide such evidence, particularly considering the progress that has been made in understanding host-microbe mutualism in the intestinal tract. In this review, we highlight the major advances that have been made discovering and describing the airway microbiome, discuss the experimental evidence that supports a functional role for the microbiome in health and disease, and propose how this emerging field is going to impact clinical practice.
Immune checkpoint inhibitors (ICIs) have been shown to improve overall and progression-free survival in various cancers but have been associated with various immune-related adverse events (IRAEs), ...including interstitial lung disease, especially organizing pneumonia. We report 2 cases of isolated severe airway disease attributable to ICIs, a rarely reported pattern of lung toxicity. The first patient received nivolumab with or without ipilimumab in a randomized double-blind trial for locoregional metastatic melanoma. The second patient was treated with nivolumab for lung adenocarcinoma. An IRAE was suspected in both cases due to a temporal relationship between ICI initiation and symptom onset. ICIs were stopped, and high-dose prednisone, inhaled corticosteroids, and bronchodilators were administered, allowing a rapid clinical and functional improvement in Patient 1. In Patient 2, despite prolonged high-dose prednisone, only a stabilization of forced expiratory volume in 1 s could be achieved, and the disease course was complicated by respiratory infections resulting in further loss of lung function. The patient died 1 year later due to progression of metastatic disease. These 2 cases suggest that pulmonary IRAEs secondary to ICIs may present as isolated bronchitis or bronchiolitis, with variable outcomes following ICI withdrawal and systemic corticosteroids.
PDF
