ORGANIC ANION TRANSPORTER POLYPEPTIDE (OATP) 3A1 AMELIORATES INTESTINAL MUCOSAL DAMAGE IN INFLAMMATORY BOWEL DISEASE
Authors: Yu Sirui , Cheng Ying , Yu Jing , He Shubei , Chai Jin , Pan Qiong 
Published: January 2024

Abstract

BACKGROUND
Inflammatory bowel disease (IBD) is a chronic condition characterised by disruption of the colonic mucosal barrier. OATP3A1/SLCO3A1 is a bile acid efflux transporter, alleviating cholestasis-associated liver injury. However, the functional role and regulational mechanism of intestinal OATP3A1 in IBD remain unclear.

METHODS
The expression and correlation of SLCO3A1 were investigated in the public datasets with IBD patients. Intestinal epithelial cell-specific Slco3a1 knockout (Slco3a1ΔIEC) mice were generated and fed with 4% DSS for functional studies.

RESULTS
Intestinal SLCO3A1 expression was significantly elevated in the ulcerative colitis (UC) and Crohn's disease (CD) patients, and positively correlated with TNFα, IL1β and MADCAM1. Compared with Slco3a1flox/flox littermates administrated by DSS, Slco3a1ΔIEC mice exhibited exacerbated colitis, characterized by more severe weight loss, enhanced colon shortening and spleen swelling. Interestingly, intestine histology assessments revealed that epithelial Oatp3a1 ablation significantly aggravated extensive disruption of the mucosal epithelium and inflammatory infiltration. The intestinal mucosal barrier function of Slco3a1ΔIEC mice was more severely damaged, as assessed by detecting serum permeated FITC-dextran. Expression of tight junction-associated proteins was decreased in Slco3a1ΔIEC mice.

CONCLUSION
Our data showed that intestinal OATP3A1 expression was markedly upregulated and exerted a protective role in inflammatory bowel disease. Overexpression of intestinal OATP3A1 may hold potential as a novel approach to alleviate intestinal inflammation- associated mucosal damage.

Figure 1 SLCO3A1 mRNA levels in the intestinal tissues of IBD patients and generation of Slco3a1ΔIECmice. (A) SLCO3A1 mRNA expression in patients with active UC or active CD and matched controls, revealed by analyzing databases of RNA-Seq data. (B and C) Pearson’s correlation analysis between SLCO3A1 expression and TNF-α, IL1β, or MADCAM1 in colon biopsy samples from active UC (n = 74) and CD (n = 52) patients. Data were collected from GEO database GSE75214. (D) Schematic diagram of Slco3a1ΔIEC mice. (E) Genotyping of Slco3a1ΔIEC mice using genomic DNA extracted from mice tails. (F) Western blot confirmed the intestine epithelia ablation of OATP3A1 in Slco3a1ΔIEC mice.

Figure 2 Effects of intestinal epithelia-specific ablation of OATP3A1 on colitis and mucosal damage in a 4% DSS treatment mouse model of IBD. (A, B) Body weight loss and spleen weight were measured from Slco3a1flox/flox or Slco3a1ΔIEC mice. (C) Serum FITC-dextran level was detected by fluorescence spectrophotometer. (D) Gross morphology images of the colon, and colon length were measured. (E) Representative images of H&E-stained colons, and histopathology analysis of colitis were performed. (F) Immunoblots of colonic lysates on Zo-1, Occludin or Claudin-1(n = 4 for each group). **P &lt; 0.01; ***P &lt; 0.001. n = 5 for Slco3a1flox/flox group; n =6 for Slco3a1ΔIEC group treated with DSS.