American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Feb 2020
General and Organ Fat Assessed by Magnetic Resonance Imaging and Respiratory Outcomes in Childhood.
Rationale: Obesity has been implicated as a pathogenic factor in asthma, but the underlying role of general and organ fat is unclear. Objectives: We hypothesized that organ fat, rather than the total fat mass, increases the risk of asthma. Methods: In a population-based prospective cohort study among 5,421 children aged 10 years, we measured general fat including body mass index and fat mass index by dual-energy X-ray absorptiometry, and organ fat including subcutaneous fat index, visceral fat index, pericardial fat index, and liver fat fraction by magnetic resonance imaging. ⋯ Higher visceral fat index, independent of fat mass index, was associated with higher FVC (z-score difference [95% CI], 0.07 [0.03 to 0.10]), lower FEV1/FVC (z-score difference [95% CI], -0.05 [-0.09 to -0.01]), and higher risk of asthma (odds ratio, 1.20; 95% CI, 1.01 to 1.43 per SD score increase). No other organ fat measures were independently associated with lung function or asthma. Conclusions: The obesity-asthma link is driven mainly by visceral fat, independent of total fat mass; therefore, abdominal fat might contribute to asthma development.
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Am. J. Respir. Crit. Care Med. · Feb 2020
Nasal Pneumococcal Density Is Associated with Microaspiration and Heightened Human Alveolar Macrophage Responsiveness to Bacterial Pathogens.
Rationale: Pneumococcal pneumonia remains a global health problem. Colonization of the nasopharynx with Streptococcus pneumoniae (Spn), although a prerequisite of infection, is the main source of exposure and immunological boosting in children and adults. However, our knowledge of how nasal colonization impacts on the lung cells, especially on the predominant alveolar macrophage (AM) population, is limited. ⋯ Similarly, AM-heightened opsonophagocytic capacity was correlated with nasopharyngeal pneumococcal density (r = 0.61, P = 0.025). Conclusions: Our findings demonstrate that nasal colonization with pneumococcus and microaspiration prime AMs, leading to brisker responsiveness to both pneumococcus and unrelated bacterial pathogens. The relative abundance of AMs in the alveolar spaces, alongside their potential for nonspecific protection, render them an attractive target for novel vaccines.