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The aim of this study was to elucidate the mechanism of the formation of the widespread mucous-plugging observed in autopsied lungs from patients with bronchial asthma.We performed morphometric analysis of airways of autopsied lungs from eight patients with bronchial asthma (Group BA), and compared it with those of six chronic bronchitics (Group CB) and four control patients (Control). The following parameters were measured in paraffin sections: volume proportion of bronchial glands to bronchial wall (Gland%); goblet cell granules to total epithelial layer (Goblet%); intraluminal mucus expressed as the mucus occupying ratio (MOR); volume ratio of intraluminal mucus continuous with goblet cells to total intraluminal mucus (Vc/Vtot%); and surface ratio of the contact surface of intraluminal mucus continuous with goblet cells to the total luminal surface (Sc/Stot%).Gland%, Goblet%, and MOR or inflammatory cell numbers in the airway walls both from Group BA and CB were larger than those from the Control group. However, no significant differences were observed between Group BA and CB in Gland%, Goblet%, MOR or inflammatory cell numbers, except for the eosinophil number: i.e. 23±3, 22±3 and 6±2% in Gland%; 22±9, 5±4 and 2±2% in Goblet%; 10±3, 18±3 and 0.3±0.5% in MOR; 199±68, 10±3 and 2±2 cells·mm -2 in eosinophil number of the peripheral airways from Groups BA, CB and Control, respectively. In contrast, marked and significant increases were observed both in Vc/Vtot% and Sc/Stot% in Group BA compared to Groups CB and Control both in central and peripheral airways: i.e. Vc/Vtot% in the peripheral airways was 53±5, 4±3 and 0.8±0.8% from Groups BA, CB and Control, respectively (BA vs CB or BA vs Control, p<0.01 each).These findings suggest that the continuity of goblet cells and intraluminal mucus or lack of full release of mucus, from goblet cells, is peculiar to asthmatic airways, and may contribute to the formation of mucous-plugs.

BackgroundIdiopathic pulmonary fibrosis (IPF) is a disease with a poor prognosis. Although the median survival is 3 years, the clinical course varies to a large extent among IPF patients. To date, there has been no definitive prognostic marker. Extracellular vesicles (EVs) are known to hold nucleic acid, including microRNAs, and to regulate gene expression in the recipient cells. Moreover, EVs have been shown to express distinct surface proteins or enveloped microRNAs depending on the parent cell or pathological condition. We aimed to identify serum EV microRNAs that would be prognostic for IPF.MethodsTo determine target microRNAs in IPF, we measured serum EV microRNA expression profiles using microRNA PCR arrays in a bleomycin mouse model and validated the microRNAs in additional mice using RT-PCR. Secondly, we enrolled 41 IPF patients and conducted a 30-month prospective cohort study. Expression of serum EV miR-21-5p was normalized by dividing by the EV amount. The relative amount of EVs was measured using the ExoScreen method. We calculated the correlations between baseline serum EV miR-21-5p expression and other clinical variables. Furthermore, we determined if serum EV miR-21-5p can predict mortality during 30 months using the Cox hazard model. According to the median level, we divided the IPF patients into two groups. Then we compared the survival rate during 30 months between the two groups using the Kaplan-Meier method.ResultsSerum EV miR-21-5p was elevated in both the acute inflammatory phase (day 7) and the chronic fibrotic phase (day 28) in the mouse model. In the clinical setting, serum EV miR-21-5p was significantly higher in IPF patients than in healthy control subjects. The baseline serum EV miR-21-5p was correlated with the rate of decline in vital capacity over 6 months. Furthermore, serum EV miR-21-5p was independently associated with mortality during the following 30 months, even after adjustment for other variables. In the survival analysis, IPF patients whose baseline serum EV miR-21-5p was high had a significantly poorer prognosis over 30 months.ConclusionsOur results suggest that serum EV miR-21-5p has potential as a prognostic biomarker for IPF.Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-016-0427-3) contains supplementary material, which is available to authorized users.

To determine whether human airway submucosal glands produce and secrete surfactant proteins, we examined their protein and gene expression in submucosal glands from trachea and bronchi obtained from operated and autopsied lungs within 4 h of death. Using a monoclonal antibody (PE-10) against surfactant protein A (SP-A), a positive immunoperoxidase stain was observed over serous cells of submucosal glands in histologic sections of airway walls. Measurement of SP-A in culture medium samples using single-step enzyme-linked immunosorbent assay showed a significant secretion of SP-A by isolated submucosal glands (1.2 +/- 0.08 ng/ml/h, SEM, n = 40). In gene expression experiments by reverse transciption-polymerase chain reaction, the SP-A complementary DNA (cDNA) segment was amplified from isolated submucosal glands, indicating the presence of SP-A messenger RNA (mRNA) in airway submucosal glands. Bronchial superficial epithelial cells failed to show the presence of SP-A mRNA. No cDNA segment of SP-B, SP-C, or SP-D cDNA was amplified from isolated submucosal glands or superficial epithelial cells, whereas all were amplified from alveolar tissue. Furthermore, in contrast to the control alveolar tissue, which expressed both SP-A1 and SP-A2 genes, SP-A2 gene transcript alone was detected in isolated submucosal glands by Southern analysis that included the digestion of the amplified SP-A cDNA fragment with the restriction enzyme Apa I. These findings indicate that human airway submucosal gland cells can transcribe the SP-A2 gene and produce SP-A protein in a manner different from peripheral airways and alveoli, playing a role in the airway defense mechanism.

To elucidate the mechanisms of late asthmatic response (LAR) observed in asthmatic subjects, we have developed an animal model of LAR using guinea pigs. Fifty guinea pigs were immunized with a mixture of Ascaris suum extract and aluminum hydroxide and then challenged with an inhalation of Ascaris suum extract without anesthesia. Twenty of the 50 guinea pigs showed a dual asthmatic response in which the LAR occurred 3 to 6 h after immediate asthmatic response (IAR). Histologic studies by rapid freezing with liquid nitrogen or bronchoalveolar lavage (BAL) were performed in 14 of these 20 guinea pigs with LAR and compared with those in 10 of 18 guinea pigs with only IAR, 10 control guinea pigs, and 10 nonimmunized but challenged guinea pigs. Both the percentage and the absolute number of neutrophils in the BAL fluid of the guinea pigs with LAR were significantly greater than those of the control guinea pigs (p less than 0.02) and than those of the nonimmunized but challenged guinea pigs (p less than 0.02). However, that of guinea pigs with LAR was not significantly different from that of guinea pigs with only IAR. On the other hand, histologic examination showed that eosinophil infiltration within the airway walls of the guinea pigs with LAR was more prominent than that of the guinea pigs with only IAR, and showed that there was no significant difference in neutrophil infiltration within the airway walls between the guinea pigs with LAR and the animals with only IAR. Contraction of airway (bronchus, bronchiole) smooth muscle, submucosal edema, and mucus in airway lumen were also observed in LAR.(ABSTRACT TRUNCATED AT 250 WORDS)