14 - The Role of Smooth Muscle Cell Piezo1 in the Maintenance of the Small Bowel Epithelium

Poster Number: 14
Publication Number: 14.207

Michael Matthews, University of California, Los Angeles David Geffen School of Medicine, Los Angeles, CA, United States; Geoanna Bautista, University of California Davis Children's Hospital, Sacramento, CA, United States; Yingjie Du, University of California, Los Angeles, Los Angeles, CA, United States; Nicolle Martin, University of California, Davis, Veterinary School, Sacramento, CA, United States; Nam Phuong N. Nguyen, University of California, Los Angeles David Geffen School of Medicine, Los Angeles, CA, United States; Elmira Tokhtaeva, UCLA, Los Angeles, CA, United States; Sergio Solorzano, UCLA, Los Angeles, CA, United States; James Dunn, Stanford University School of Medicine, Palo Alto, CA, United States; Martin Martin, UCLA Mattel Childrens Hospital, Los angeles, CA, United States

Background: Piezo1 is a mechanosensitive ion channel involved in the modulation of trophic effects in mechanosensitive tissues and it is expressed in smooth muscle cells (SMCs) within the muscularis of the intestine. In our previous research, we found that loss of SMC Piezo1 leads to weight loss, thinning of the small bowel muscularis, and dysmotility. However, the role of SMC Piezo1 as it pertains to the small bowel epithelium has yet to be investigated.

Objective: Here, we aim to explore the role of intestinal SMC Piezo1 as it pertains to the growth and maintenance of the small bowel epithelium.

Design/Methods: Using the Piezo1/Myh11-ERT2/Cre-LoxP system, we generated a mouse model with a tamoxifen (Tam) inducible-Piezo1 knockout in the SMCs of the intestine (Piezo1∆SMC). Distal bowel segments were isolated from Piezo1∆SMC and Piezo1WT mice. H&E and immunofluorescence (IF) staining was performed and subsequently quantified.

Results: H&E staining revealed that at 10 days post-Tam, Piezo1∆SMC had substantially longer crypts and villi in both proximal and distal bowel compared to Piezo1WT (p < 0.001). IF staining of the distal bowel was used to examine the epithelium's cellular composition. Compared to Piezo1WT, Piezo1∆SMC crypts had an average of 12.7 ± 1.8 more intestinal stem cells (ISCs) per mm as assessed by Olfm4 (p < 0.0001), and an average of 6 ± 2.2 fewer Paneth cells per mm as assessed by Lys (p < 0.01). Similarly, staining for PAS revealed that in Piezo1∆SMC, there was an average of 38.4 ± 4.5 more Goblet cells per mm in the crypts compared to Piezo1WT (p < 0.0001). Tuft cells were assessed with Dclk1 staining and compared to Piezo1WT, Piezo1∆SMC had 6.3 ± 2.4 more Tuft cells per mm (p < 0.02). The enteroendocrine (EEC) and enterochromaffin (ECC) cell populations were assessed by Chga and 5-HT staining. On average, the villi of Piezo1∆SMC mice had 10.1 ± 1.5 fewer EECs per mm and 11.4 ± 1.7 fewer ECCs per mm compared to Piezo1WT (p < 0.0001). We examined cell proliferation by staining for Ki67 and as expected, there was a marked increase in the crypts of Piezo1∆SMC which had an average of 37.8 ± 3.3 more Ki67+ cells per mm compared to Piezo1WT (p < 0.0001).Conclusion(s): Overall, our data suggests that Piezo1 expression in the intestinal SMCs is critical for maintenance of the epithelium’s crypt-villus axis and cell populations as Piezo1∆SMC was associated with expansion of the crypt-villus axis, enrichment of proliferation and ISCs, increased Goblet and Tuft cells, and relative depletion of Paneth cells, EECs, and ECCs.