ICAM-1^null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke

Area of Science:

• Neuroscience
• Immunology
• Pathology

Background:

• Neutrophil accumulation in the brain is a key factor in cerebral ischemia and tissue damage.
• Intercellular Adhesion Molecule (ICAM)-1 is upregulated after ischemic stroke and thought to be crucial for neutrophil recruitment.
• Previous studies suggested ICAM-1 deficiency protected against experimental stroke, but clinical translation failed.

Purpose of the Study:

• To investigate the role of ICAM-1 in cerebral ischemia using a true ICAM-1 null mouse line.
• To determine if the absence of ICAM-1 affects neutrophil infiltration and stroke pathology.

Main Methods:

• Transient middle cerebral artery occlusion (tMCAO) was performed on ICAM-1 null and wild-type C57BL/6 mice.
• Near-infrared imaging was used to track neutrophil accumulation.
• Neutrophil counts in brain tissue were quantified.
• Immunostaining assessed neutrophil distribution.
• Lesion size was measured.

Main Results:

• Absence of ICAM-1 did not ameliorate stroke pathology at acute time points after reperfusion.
• Comparable neutrophil accumulation was observed in the ischemic hemispheres of ICAM-1 null and wild-type mice.
• Neutrophil infiltration into leptomeninges and brain parenchyma was similar between groups.
• Lesion size was comparable in both ICAM-1 null and wild-type mice.

Conclusions:

• The absence of ICAM-1 does not inhibit cerebral ischemia-induced neutrophil accumulation in the brain.
• ICAM-1 deficiency does not provide protection against ischemic stroke in this model.
• These findings suggest ICAM-1 may not be a viable therapeutic target for acute ischemic stroke treatment.