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Neutrophil expressed CD47 regulates CD11b/CD18-dependent neutrophil transepithelial migration in the intestine in
Veronica Azcutia1, Matthias Kelm2, Anny-Claude Luissint2
1Department of Pathology, University of Michigan School of Medicine, Ann Arbor, MI, 48109, USA. vazcucri@med.umich.edu.
Abstract:
Dysregulated neutrophil (PMN) transmigration across epithelial surfaces (TEpM) significantly contributes to chronic inflammatory diseases, yet mechanisms defining this process remain poorly understood. In the intestine, uncontrolled PMN TEpM is a hallmark of disease flares in ulcerative colitis. Previous in vitro studies directed at identifying molecular determinants that mediate TEpM have shown that plasma membrane proteins including CD47 and CD11b/CD18 play key roles in regulating PMN TEpM across monolayers of intestinal epithelial cells. Here, we show that CD47 modulates PMN TEpM in vivo using an ileal loop assay. Importantly, using novel tissue-specific CD47 knockout mice and in vitro approaches, we report that PMN-expressed, but not epithelial-expressed CD47 plays a major role in regulating PMN TEpM. We show that CD47 associates with CD11b/CD18 in the plasma membrane of PMN, and that loss of CD47 results in impaired CD11b/CD18 activation. In addition, in vitro and in vivo studies using function blocking antibodies support a role of CD47 in regulating CD11b-dependent PMN TEpM and chemotaxis. Taken together, these findings provide new insights for developing approaches to target dysregulated PMN infiltration in the intestine. Moreover, tissue-specific CD47 knockout mice constitute an important new tool to study contributions of cells expressing CD47 to inflammation in vivo.
Insights
Neutrophil transmigration across epithelial surfaces is crucial in inflammatory diseases. This study reveals that neutrophil-expressed CD47, not epithelial CD47, significantly regulates this process by associating with CD11b/CD18.
Area of Science:
- Immunology
- Cell Biology
- Gastroenterology
Background:
- Dysregulated neutrophil transmigration across epithelial surfaces (TEpM) is implicated in chronic inflammatory diseases like ulcerative colitis.
- Understanding the molecular mechanisms of TEpM is critical for developing targeted therapies.
- Previous in vitro studies identified CD47 and CD11b/CD18 as key regulators of PMN TEpM.
Purpose of the Study:
- To investigate the role of CD47 in regulating neutrophil transmigration across intestinal epithelial surfaces in vivo.
- To determine whether CD47 expression on neutrophils or epithelial cells is critical for TEpM.
- To elucidate the interaction between CD47 and CD11b/CD18 in the context of neutrophil transmigration.
Main Methods:
- Utilized an in vivo ileal loop assay to study PMN TEpM.
- Employed novel tissue-specific CD47 knockout mice models.
- Conducted in vitro assays and used function-blocking antibodies to analyze CD47 and CD11b/CD18 interactions and function.
Main Results:
- CD47 modulates PMN TEpM in vivo.
- Neutrophil-expressed CD47, rather than epithelial CD47, plays a major role in regulating PMN TEpM.
- CD47 associates with CD11b/CD18 on neutrophils, and its absence impairs CD11b/CD18 activation, affecting PMN TEpM and chemotaxis.
Conclusions:
- Neutrophil CD47 is a key regulator of transmigration across intestinal epithelium.
- Findings provide novel insights into targeting dysregulated neutrophil infiltration in intestinal inflammation.
- Tissue-specific CD47 knockout mice are valuable tools for studying cellular contributions to inflammation.