Features of the bronchial bacterial microbiome associated with atopy, asthma, and responsiveness to inhaled corticosteroid treatment

Predictive Biomarkers for Asthma Therapy

PURPOSE OF REVIEW

Asthma is a heterogeneous disease characterized by multiple phenotypes. Treatment of patients with severe disease can be challenging. Predictive biomarkers are measurable characteristics that reflect the underlying pathophysiology of asthma and can identify patients that are likely to respond to a given therapy. This review discusses current knowledge regarding predictive biomarkers in asthma.

RECENT FINDINGS

Recent trials evaluating biologic therapies targeting IgE, IL-5, IL-13, and IL-4 have utilized predictive biomarkers to identify patients who might benefit from treatment. Other work has suggested that using composite biomarkers may offer enhanced predictive capabilities in tailoring asthma therapy. Multiple biomarkers including sputum eosinophil count, blood eosinophil count, fractional concentration of nitric oxide in exhaled breath (FeNO), and serum periostin have been used to identify which patients will respond to targeted asthma medications. Further work is needed to integrate predictive biomarkers into clinical practice.

Phenotypic and genetic aspects of epithelial barrier function in asthmatic patients

The bronchial epithelium is continuously exposed to a multitude of noxious challenges in inhaled air. Cellular contact with most damaging agents is reduced by the action of the mucociliary apparatus and by formation of a physical barrier that controls passage of ions and macromolecules. In conjunction with these defensive barrier functions, immunomodulatory cross-talk between the bronchial epithelium and tissue-resident immune cells controls the tissue microenvironment and barrier homeostasis. This is achieved by expression of an array of sensors that detect a wide variety of viral, bacterial, and nonmicrobial (toxins and irritants) agents, resulting in production of many different soluble and cell-surface molecules that signal to cells of the immune system. The ability of the bronchial epithelium to control the balance of inhibitory and activating signals is essential for orchestrating appropriate inflammatory and immune responses and for temporally modulating these responses to limit tissue injury and control the resolution of inflammation during tissue repair. In asthmatic patients abnormalities in many aspects of epithelial barrier function have been identified. We postulate that such abnormalities play a causal role in immune dysregulation in the airways by translating gene-environment interactions that underpin disease pathogenesis and exacerbation.

Potential of Health and Demographic Surveillance System in Asthma and Chronic Obstructive Pulmonary Disease Microbiome Research

Health and demographic surveillance system (HDSS) is a population-based health and vital event registration system that monitors demographic and health events in a geographically defined population at regular intervals. Human microbiome research in the past decade has been the field of increasingly intense research much due to its demonstrated impact upon various health conditions including human chronic airway diseases such as asthma and chronic obstructive pulmonary disease (COPD). Many confounding factors have been revealed to play a role in shaping the microbiome in chronic airway diseases. Asthma and COPD follows a typical pattern of disease progression, which includes stable and exacerbation state in which the microbiota is known to vary. However, many such studies lack extensive and longitudinal sampling with inadequate metadata, which has resulted in the inconsistencies in the observations. HDSS provides such a platform, which can offer a deeper understanding of the role of the microbiome in human health. In this review, we highlight opportunities and limitations in microbiome research with the help of studies conducted on chronic airway diseases like asthma and COPD. In addition, we also emphasize on the benefits of HDSS and future directions in lung microbiome research.

Advances in asthma in 2016: Designing individualized approaches to management

In this year's Advances in Asthma review, we discuss viral infections in asthmatic patients and potential therapeutic agents, the microbiome, novel genetic associations with asthma, air quality and climate effects on asthma, exposures during development and long-term sequelae of childhood asthma, patient-centered outcomes research, and precision medicine. In addition, we discuss application of biomarkers to precision medicine and new information on asthma medications. New evidence indicates that rhinovirus-triggered asthma exacerbations become more severe as the degree of sensitization to dust mite and mouse increase. The 2 biggest drivers of asthma severity are an allergy pathway starting with allergic sensitization and an environmental tobacco smoke pathway. In addition, allergic sensitization and blood eosinophils can be used to select medications for management of early asthma in young children. These current findings, among others covered in this review, represent significant steps toward addressing rapidly advancing areas of knowledge that have implications for asthma management.

The microbiome in allergic disease: Current understanding and future opportunities-2017 PRACTALL document of the American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology

PRACTALL is a joint initiative of the American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology to provide shared evidence-based recommendations on cutting-edge topics in the field of allergy and immunology. PRACTALL 2017 is focused on what has been established regarding the role of the microbiome in patients with asthma, atopic dermatitis, and food allergy. This is complemented by outlining important knowledge gaps regarding its role in allergic disease and delineating strategies necessary to fill these gaps. In addition, a review of progress in approaches used to manipulate the microbiome will be addressed, identifying what has and has not worked to serve as a baseline for future directions to intervene in allergic disease development, progression, or both.

Translational research in pediatric pulmonary disease, 2017

As readers of this journal know, translational research is the application of basic science findings to improve clinical care; a process that was once called “bench-to-bedside” research. In my field of pediatric pulmonary disease, the rapid advancement of basic science understanding into improved clinical care has been, to use an appropriate term, breathtaking. In this perspective article, I will describe a few of these advances, as they relate to specific pulmonary diseases.

Beyond Hygiene: Commensal Microbiota and Allergic Diseases

Complex communities of microorganisms, termed commensal microbiota, inhabit mucosal surfaces and profoundly influence host physiology as well as occurrence of allergic diseases. Perturbing factors such as the mode of delivery, dietary fibers and antibiotics can influence allergic diseases by altering commensal microbiota in affected tissues as well as in intestine. Here, we review current findings on the relationship between commensal microbiota and allergic diseases, and discuss the underlying mechanisms that contribute to the regulation of allergic responses by commensal microbiota.

The Influence of the Microbiome on Early-Life Severe Viral Lower Respiratory Infections and Asthma-Food for Thought?

Severe viral lower respiratory infections are a major cause of infant morbidity. In developing countries, respiratory syncytial virus (RSV)-bronchiolitis induces significant mortality, whereas in developed nations the disease represents a major risk factor for subsequent asthma. Susceptibility to severe RSV-bronchiolitis is governed by gene-environmental interactions that affect the host response to RSV infection. Emerging evidence suggests that the excessive inflammatory response and ensuing immunopathology, typically as a consequence of insufficient immunoregulation, leads to long-term changes in immune cells and structural cells that render the host susceptible to subsequent environmental incursions. Thus, the initial host response to RSV may represent a tipping point in the balance between long-term respiratory health or chronic disease (e.g., asthma). The composition and diversity of the microbiota, which in humans stabilizes in the first year of life, critically affects the development and function of the immune system. Hence, perturbations to the maternal and/or infant microbiota are likely to have a profound impact on the host response to RSV and susceptibility to childhood asthma. Here, we review recent insights describing the effects of the microbiota on immune system homeostasis and respiratory disease and discuss the environmental factors that promote microbial dysbiosis in infancy. Ultimately, this knowledge will be harnessed for the prevention and treatment of severe viral bronchiolitis as a strategy to prevent the onset and development of asthma.