Whole-lung pathology of pleuroparenchymal fibroelastosis (PPFE) in an explanted lung: Significance of elastic fiber-rich, non-specific interstitial pneumonia-like change in chemotherapy-related PPFE.

Pleuroparenchymal fibroelastosis (PPFE) is characterized by upper lobe-predominant subpleural fibroelastosis. Despite its characteristic uneven distribution, detailed whole-lung pathological features of PPFE have rarely been studied. We investigated PPFE in the explanted lungs from a 19-year-old male patient with a history of chemotherapy. Grossly, the explanted lungs showed upper lobe-predominant shrinkage with subpleural and central consolidation. Histologically, fibroelastosis was prominent in the perilobular areas and along the bronchovascular bundles. The other areas of the lung showed diffuse, non-specific interstitial pneumonia (NSIP)-like change with a characteristic increase of septal elastic fibers. In the digital image analysis, the ratio of elastic fibers to whole fibrosis (EF score) was lower in the subpleural areas than in the NSIP-like lesions, but the EF scores of the latter showed no significant difference between upper and middle/lower lobes. In the present case, the diffusely distributed elastic fiber-rich NSIP-like change, probably caused by the earlier chemotherapy, may have been conducive to the development of PPFE. This suggests that some unknown vulnerability of the upper lobe may exist, various primary lesions converging to the upper lobe predominance of PPFE.

Stomach encyclopedia: Combined single-cell and spatial transcriptomics reveal cell diversity and homeostatic regulation of human stomach.

The stomach is an important digestive organ with various biological functions. However, because of the complexity of its cellular and glandular composition, its precise cellular biology has yet to be elucidated. In this study, we conducted single-cell RNA sequencing (scRNA-seq) and subcellular-level spatial transcriptomics analysis of the human stomach and constructed the largest dataset to date: a stomach encyclopedia. This dataset consists of approximately 380,000 cells from scRNA-seq and the spatial transcriptome, enabling integrated analyses of transcriptional and spatial information of gastric and metaplastic cells. This analysis identified LEFTY1 as an uncharacterized stem cell marker, which was confirmed through lineage tracing analysis. A wide variety of cell-cell interactions between epithelial and stromal cells, including PDGFRA+BMP4+WNT5A+ fibroblasts, was highlighted in the developmental switch of intestinal metaplasia. Our extensive dataset will function as a fundamental resource in investigations of the stomach, including studies of development, aging, and carcinogenesis.