PMC8111526_01
Histopathology of terminal ileum and transverse colon biopsies with staining for ACER2 and the vascular endothelial marker ERG. Terminal ileum biopsies showed mucosae without distortion of villi- or crypt architecture. There was slight expansion of the inflammatory infiltrate, which consisted of plasma cells, lymphocytes, eosinophilic granulocytes, and a few neutrophils. In addition, there were few lymphoid aggregates and a lymphoid follicle. There were no granulomas or epithelial dysplasia. The additional ACE2 staining showed enhanced staining at the brush border and in the vascular endothelium (a, e). Transverse colon biopsies showed slight distortion of the villous architecture of the surface epithelium and slight edema with focal epithelial detachment. There was expansion of the inflammatory infiltrate, which consisted mainly of plasma cells, and neutrophilic-, and eosinophilic granulocytes. There were signs of cryptitis and crypt abscesses. Some crypts showed no architectural changes whereas others showed partial or total damage. Interestingly, the small capillaries showed endotheliitis resulting from extravasation of neutrophilic granulocytes. These activated prominent endothelial cells showed no fibrin deposition or damage. The additional ACE2 staining showed no enhanced staining at the brush border and the staining in the vascular endothelium was blurry (b, d, f). Endothelial cells are highlighted in the ERG staining (c).. ACE, angiotensin-converting enzyme 2; ACER2, angiotensin-converting enzyme receptor 2; ERG, ETS-related gene.
10.1177_17562848211012595-fig1.jpg
PMC8111526_01_10.1177_17562848211012595-fig1.jpg
fig1-17562848211012595
Biopsies were taken from the terminal ileum and transverse colon (Figure 1).
PMC8111526_02
PMC8111526_03