Therapeutic advances for pulmonary hypertension (PH) have been incremental because of the focus on the pulmonary vasculature in PH pathology. Here, we evaluate the concept that PH is, rather, a systemic disorder involving interplay among multiorgan systems, including brain, gut, and lungs. Therefore, the objective of this study was to evaluate the hypothesis that PH is associated with a dysfunctional brain-gut-lung axis and that global overexpression of ACE2 (angiotensin-converting enzyme 2) rebalances this axis and protects against PH. ACE2 knockin and wild-type (WT; C57BL/6) mice were subjected to chronic hypoxia (10% FIO2) or room air for 4 weeks. Cardiopulmonary hemodynamics, histology, immunohistochemistry, and fecal 16S rRNA microbial gene analyses were evaluated. Hypoxia significantly increased right ventricular systolic pressure, sympathetic activity as well as the number and activation of microglia in the paraventricular nucleus of the hypothalamus in WT mice. This was associated with a significant increase in muscularis layer thickening and decreases in both villi length and goblet cells and altered gut microbiota. Global overexpression of ACE2 prevented changes in hypoxia-induced pulmonary and gut pathophysiology and established distinct microbial communities from WT hypoxia mice. Furthermore, WT mice subjected to fecal matter transfer from ACE2 knockin mice were resistant to hypoxia-induced PH compared with their controls receiving WT fecal matter transfer. These observations demonstrate that ACE2 ameliorates these hypoxia-induced pathologies and attenuates PH. The data implicate dysfunctional brain-gut-lung communication in PH and provide novel avenues for therapeutic interventions.

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Objective Substantial evidence links gut dysbiosis to hypertension in both animal models and in patients with high blood pressure. Increased blood pressure and hypertension‐associated pathologies in normotensive animals transplanted with fecal microbiota from hypertensive animals, support the concept of microbiota‐gut communication as an important early signal initiating and establishing hypertension. We hypothesized that colonic cryp‐3D organoids would retain the characteristics of the in vivo gut epithelium form which they were derived, and would provide a model system to investigate epithelial‐microbiota communication in hypertension. Methods Colonic crypts were isolated from adult Wistar‐Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). 3D organoid cultures were established in organoid growth medium with Matrigel matrix and cultured for 3, 5 and 7 days without passage. The shapes and number of organoids were assessed by bright‐field microscopy using Trypan blue. Growth, differentiation and cell types in organoids were characterized with the use of antibodies (Ki67, Alpi, KRT20 and Muc2). Data were compared between WKY rats and SHR organoids. Results Reproducible 3D organoid cultures were successfully established from the crypts of adult WKY and SHR. They proliferated and differentiated, and predominately contained enterocytes and goblet cells. We observed significantly more organoids per crypt from normotensive vs hypertensive rats (WKY: 0.20 vs. SHR: 0.11; p<0.01). In vivo, WKY rats had 18% longer colons than SHR (0.07 cm/g vs. 0.059 cm/g; p<0.0001). Conclusions These observations demonstrate that 3D organoid cultures maintain characteristics of the colonic epithelium and show significant differences between WKY rats and SHR. Thus, these organoids represent an ideal ex vivo system to investigate the gut epithelium in hypertension, and to examine the effects of gut microbiome‐derived metabolites in blood pressure control and initiation and establishment of hypertension. Support or Funding Information HL132448