Host engulfment pathway controls inflammation in inflammatory bowel disease

Area of Science:

• Gastroenterology and Immunology
• Cell Biology and Molecular Mechanisms
• Biomarker Discovery

Background:

• Chronic inflammatory diseases like IBD lack effective biomarkers, as many patients do not respond to existing treatments.
• Microbial sensing in the gut initiates inflammation, a common factor in IBD pathogenesis.
• ELMO1 (engulfment and cell motility protein 1) is identified as a crucial microbial sensor in epithelial and phagocytic cells.

Purpose of the Study:

• To investigate the role of ELMO1 in microbial sensing and inflammatory responses within the context of IBD.
• To explore the potential of the ELMO1-MCP-1 axis as an early diagnostic biomarker for IBD.

Main Methods:

• Utilized a stem cell-based 'gut-in-a-dish' coculture model with enteroid-derived monolayers (EDMs) from mice and IBD patients.
• Infected EDMs with IBD-associated microbes to monitor inflammatory responses.
• Analyzed ELMO1 expression in colonic biopsies from IBD patients and correlated it with cytokine levels.

Main Results:

• ELMO1-depleted EDMs showed reduced bacterial internalization, lower pro-inflammatory cytokine production, and decreased monocyte recruitment.
• ELMO1 expression was elevated in the colonic epithelium and inflammatory infiltrates of IBD patients.
• Higher ELMO1 expression correlated positively with elevated pro-inflammatory cytokines MCP-1 and TNF-α.

Conclusions:

• The epithelial ELMO1 → MCP-1 axis is critical for initiating and propagating inflammation in IBD by mediating bacterial sensing and monocyte recruitment.
• Dysregulation of this axis presents a potential early diagnostic biomarker for IBD and other inflammatory disorders.