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Defect in CEACAM family member expression in Crohn's disease IECs is regulated by the transcription factor SOX9
Giulia Roda1, Stephanie Dahan, Laura Mezzanotte
1Department of Clinical Medicine, Gastroenterology Unit, S. Orsola Hospital, Bologna, Italy.
Background:
CEACAM1, CEACAM5, and CEACAM6 represent 3 of the CEACAM (carcinoembryonic antigen-related cell adhesion molecule) subfamily members expressed on intestinal epithelial cells (IECs). Deficiency in their expression, as seen in inflammatory bowel disease (IBD), results in the lack of activation of CD8+ regulatory T cells in the mucosa. Since CEACAM expression was shown to be regulated by the transcription factor SOX9, we sought to determine whether the defect in CEACAM expression in IBD was related to aberrant SOX9 expression.
Methods:
IECs and lamina propria lymphocytes (LPLs) were freshly isolated from colonic tissues. T84 and HT29 16E cells were cocultured with LPLs. SOX9 and CEACAM subfamily member expression was assessed by real-time polymerase chain reaction (PCR), Western blot, immunohistochemistry, and immunofluorescence.
Results:
In Crohn's disease (CD) but not in ulcerative colitis (UC), a significant reduction in mRNA and protein expression for CEACAM1 and 5 was noted; in contrast, no difference in SOX9 mRNA expression was seen. However, nuclear SOX9 immunostaining was increased in CD IECs. Furthermore, SOX9 protein was reduced in the cytoplasm of LPL-stimulated T84 and HT29 16E cells, while CEACAM5 expression was increased.
Conclusions:
The defect in CEACAM family members in CD IECs appears to be related to the aberrant nuclear localization of SOX9. Changes in SOX9 expression in the CD mucosa relate to the local microenvironment and altered IEC:LPL crosstalk.
Insights
In Crohn's disease, reduced CEACAM expression in intestinal cells is linked to abnormal SOX9 localization, not expression levels. This suggests altered cell communication impacts inflammatory bowel disease.
Area of Science:
- Gastroenterology
- Immunology
- Cell Biology
Background:
- CEACAM1, CEACAM5, and CEACAM6 are cell adhesion molecules on intestinal epithelial cells (IECs).
- Deficiency in CEACAM expression in inflammatory bowel disease (IBD) impairs CD8+ regulatory T cell activation.
- SOX9 is a transcription factor regulating CEACAM expression.
Purpose of the Study:
- To investigate if aberrant SOX9 expression underlies the defect in CEACAM expression observed in IBD.
- To explore the relationship between SOX9 and CEACAM expression in the context of Crohn's disease (CD) and ulcerative colitis (UC).
Main Methods:
- Isolated IECs and lamina propria lymphocytes (LPLs) from colonic tissues.
- Co-cultured cell lines (T84, HT29 16E) with LPLs.
- Assessed SOX9 and CEACAM expression using RT-PCR, Western blot, immunohistochemistry, and immunofluorescence.
Main Results:
- Crohn's disease (CD) showed reduced CEACAM1 and CEACAM5 mRNA and protein compared to controls.
- SOX9 mRNA levels were unchanged, but nuclear SOX9 immunostaining increased in CD IECs.
- LPL-stimulated cells exhibited reduced cytoplasmic SOX9 and increased CEACAM5 expression.
Conclusions:
- Aberrant nuclear localization of SOX9 in CD IECs contributes to the defect in CEACAM family members.
- Altered SOX9 expression in the CD mucosa is influenced by the local microenvironment and disrupted IEC:LPL crosstalk.
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