Neutrophil-selective CD18 silencing using RNA interference in vivo

Area of Science:

• Immunology
• Molecular Biology
• Genetic Engineering

Background:

• Tissue-specific gene silencing is crucial for genetic engineering and potential human therapies.
• Current mouse models often require complex Cre/loxP systems and multiple transgenic lines.

Purpose of the Study:

• To develop a more efficient method for gene silencing in neutrophils using micro RNA (miRNA).
• To investigate the role of CD18 in neutrophil function and its relevance to leukocyte adhesion deficiency type I (LAD-I).

Main Methods:

• Generation of a single transgenic mouse line expressing a CD18-specific miRNA driven by the myeloid-specific human MRP8 promoter.
• Quantification of CD18 protein levels in various leukocyte subsets.
• Assessment of neutrophil function, including trafficking and adhesion.

Main Results:

• Significant reduction (75-95%) in CD18 protein levels in neutrophils and monocytes of transgenic mice.
• Observed neutrophilia, splenomegaly, and impaired neutrophil trafficking, correlating with CD18 reduction.
• Demonstrated the efficacy of miRNA for silencing genes in terminally differentiated, short-lived neutrophils.

Conclusions:

• Micro RNA-based gene silencing is a powerful tool for manipulating gene expression in neutrophils.
• The developed mouse models are valuable for studying the pathogenesis of LAD-I and the function of CD18 in leukocytes.