Context.-Surgical and pathologic handling of lung physically affects lung tissue. This leads to artifacts that alter the morphologic appearance of pulmonary parenchyma.Objective.-To describe and illustrate mechanisms of ex vivo artifacts that may lead to diagnostic pitfalls.Design.-In this study 4 mechanisms of ex vivo artifacts and corresponding diagnostic pitfalls are described and illustrated.Results.-The 4 patterns of artifacts are: (1) surgical collapse, due to the removal of air and blood from pulmonary resections; (2) ex vivo contraction of bronchial and bronchiolar smooth muscle; (3) clamping edema of open lung biopsies; and (4) spreading of tissue fragments and individual cells through a knife surface. Morphologic pitfalls include diagnostic patterns of adenocarcinoma, asthma, constrictive bronchiolitis, and lymphedema.Conclusion.-Four patterns of pulmonary ex vivo artifacts are important to recognize in order to avoid morphologic misinterpretations.

The cellular and molecular pathways in asthma are highly complex. Increased understanding can be obtained by unbiased transcriptomic analysis (RNA-Seq). We hypothesised that the transcriptomic profile of whole human endobronchial biopsies differs between asthma patients and controls.First, we investigated the feasibility of obtaining RNA from whole endobronchial biopsies suitable for RNA-Seq. Secondly, we examined the difference in transcriptomic profiles between asthma and controls. This cross-sectional study compared four steroid-free atopic asthma patients and five healthy nonatopic controls. Total RNA from four biopsies per subject was prepared for RNA-Seq. Comparison of the numbers of reads per gene in asthma and controls was based on the Poisson distribution.46 genes were differentially expressed between asthma and controls, including pendrin, periostin and BCL2. 10 gene networks were found to be involved in cellular morphology, movement and development.RNA isolated from whole human endobronchial biopsies is suitable for RNA-Seq, showing different transcriptomic profiles between asthma and controls. Novel and confirmative genes were found to be linked to asthma. These results indicate that biological processes in the airways of asthma patients are regulated differently when compared to controls, which may be relevant for the pathogenesis and treatment of the disease. @ERSpublications Transcriptome sequencing shows processes in the airways of asthmatics are differently regulated at transcriptomic level

Oral prednisolone changes the transcriptomic profile of the ASM layer in asthma. This indicates that in parallel to antiinflammatory properties, glucocorticoids also exert effects on gene expression of ASM, which is correlated with improved airway function.

In asthma, ECM in ASM is related to the dynamics of airway function in the absence of differences in ECM expression between asthma and controls. This indicates that the ASM layer in its full composition is a major structural component in determining variable airways obstruction in asthma.

Airway smooth muscle from asthma patients can be distinguished from that of atopic and nonatopic control subjects by a specific gene expression profile, which is associated with airway hyper-responsiveness.