Piezo2: A Candidate Biomarker for Visceral Hypersensitivity in Irritable Bowel Syndrome?

Abstract

Background/aims: Currently, there exists no biomarker for visceral hypersensitivity in irritable bowel syndrome (IBS). Piezo proteins have been proven to play an important role in the mechanical stimulation to induce visceral pain in other tissues and may also be a biomarker candidate. The aim of this study was to test the expressions of Piezo1 and Piezo2 proteins in the intestinal epithelial cells from different intestinal segments and to explore the correlation between Piezo proteins expression and visceral pain threshold.

Methods: Post-infectious IBS was induced in mice via a Trichinella spiralis infection. Visceral sensitivity was measured with abdominal withdrawal reflex to colorectal distention. Inflammation in the small intestine and colon was scored with H&E staining. Expression location of Piezo proteins was confirmed by immunohistochemistry. Abundance of Piezo proteins were measured with real-time reverse transcriptase polymerase chain reaction.

Results: Piezo1 and Piezo2 proteins were expressed in the intestinal epithelial cells. The expression levels of Piezo1 and Piezo2 were abundant in the colon than the small intestine (P < 0.001 for Piezo1, P = 0.003 for Piezo2). Expression of Piezo2 in the colon significantly correlated to the visceral sensitivity (r = -0.718, P = 0.001) rather than the mucosal inflammation.

Conclusion: Piezo2 is a candidate biomarker for visceral hypersensitivity in IBS.

Keywords: Hyperalgesia; Ion channels; Irritable bowel syndrome; Piezo2 protein, human; Pizeo1 protein, human.

Figure 1

Weight, abdominal withdrawal reflex scores, and thresholds of control and post-infectious irritable bowel syndrome (PI-IBS) mouse model. (A) Weight of control and PI-IBS mice (*P = 0.011). (B) Thresholds of the colorectal distention intensities that evoke abdominal contraction of the mice. Mean ± SEM values were plotted (*P < 0.001). (C) Box plot of abdominal withdrawal reflex scores. Lines represent the median within the box, the 25th and 75th centiles at the ends of the box, and the error bars define the 5th and 95th centiles (*P < 0.001).

Figure 2

Inflammation scores in H&E stained sections of small intestine. (A) H&E stained sections of small intestine from control mice. (B) H&E stained sections of small intestine from mice with acute infection. (C) H&E stained sections of small intestine from mice with post-infection. (D) Inflammation scores. Lines represent the median within the box, the 25th and 75th centiles at the ends of the box, and the error bars define the 5th and 95th centiles. *P < 0.001.

Figure 3

Inflammation scores in H&E stained sections of colon. (A) H&E stained sections of colon from control mice. (B) H&E stained sections of colon from mice with acute infection. (C) H&E stained sections of colon from mice with post-infection. (D) Inflammation scores. Lines represent the median within the box, the 25th and 75th centiles at the ends of the box, and the error bars define the 5th and 95th centiles. *P < 0.001.

Figure 4

Immunohistochemistry staining for Piezo1. (A) Expression of Piezo1 in control group small intestine. (B) Expression of Piezo1 in the colon of mice in control group. (C) Expression of Piezo1 in the colon of mice in acute infection group. (D) Expression of Piezo1 in the colon of mice in post-infection group. (E) Comparison of Piezo1 expression in control group small intestine and colon. (F) Comparison of Piezo1 expression in control, acute infection, and post-infection groups. *P < 0.05.

Figure 5

Immunohistochemistry staining for Piezo2. (A) Expression of Piezo2 in control group small intestine. (B) Expression of Piezo2 in the colon of mice in control group. (C) Expression of Piezo2 in the colon of mice in acute infection group. (D) Expression of Piezo2 in the colon of mice in post-infection group. (E) Comparison of Piezo2 expression in control group small intestine and colon. (F) Comparison of Piezo2 expression in control, acute infection, and post-infection groups. *P < 0.05.

Figure 6

Relative expression of Piezo1 and Piezo2. (A) Relative expression of Piezo1 in control group small intestine and colon. (B) Relative expression of Piezo2 in control group small intestine and colon. (C) Relative expression of Piezo1 in small intestine of mice in control, acute infection, and post-infection groups. (D) Relative expression of Piezo2 in small intestine of mice in control, acute infection, and post-infection groups. (E) Relative expression of Piezo1 in colon of mice in control, acute infection, and post-infection groups. (F) Relative expression of Piezo2 in colon of mice in control, acute infection, and post-infection groups. *P < 0.05.

Figure 7

Correlation between visceral sensation and expression of Piezo1 and Piezo2. (A) Correlation between visceral sensation and expression of Piezo1 in small intestine samples from mice in control group, acute infection group, and post-infection group. (B) Correlation between visceral sensation and expression of Piezo1 in the colon samples from mice in control group, acute infection group, and post-infection group. (C) Correlation between visceral sensation and expression of Piezo2 in the small intestine samples from mice in control group, acute infection group, and post-infection group. (D) Correlation between visceral sensation and expression of Piezo2 in the colon samples from mice in control group, acute infection group, and post-infection group.