ICAM-1 and VCAM-1 mediate endotoxemic myocardial dysfunction independent of neutrophil accumulation

Area of Science:

• Cardiovascular Physiology
• Immunology
• Sepsis Pathophysiology

Background:

• Sepsis can cause myocardial dysfunction, impacting heart function.
• Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are implicated in sepsis-related organ injury.
• The specific roles of ICAM-1, VCAM-1, and neutrophils in sepsis-induced heart dysfunction are not fully understood.

Purpose of the Study:

• To investigate the involvement of ICAM-1, VCAM-1, and neutrophils in lipopolysaccharide (LPS)-induced myocardial dysfunction.
• To determine the contribution of these factors to cardiac dysfunction during endotoxemia.

Main Methods:

• Mice were administered LPS or vehicle, and cardiac function was assessed using the Langendorff technique.
• Myocardial expression of ICAM-1 and VCM-1, along with neutrophil infiltration, was evaluated using immunofluorescent staining.
• Antibody blockade or genetic knockout of ICAM-1 and VCAM-1, as well as neutrophil depletion, were employed to assess their roles.

Main Results:

• LPS administration significantly depressed left ventricular developed pressure (LVDP) by approximately 40% at 6 hours.
• Myocardial expression of ICAM-1 and VCAM-1, and neutrophil accumulation, increased temporally after LPS exposure.
• Blocking VCAM-1 reduced neutrophil infiltration and prevented cardiac dysfunction; blocking or lacking ICAM-1 prevented dysfunction without reducing neutrophil infiltration.
• Neutrophil depletion did not protect against LPS-induced myocardial dysfunction.

Conclusions:

• Endotoxemic myocardial dysfunction is dependent on both ICAM-1 and VCAM-1.
• Cardiac dysfunction during sepsis occurs independently of neutrophil accumulation.
• Targeting ICAM-1 and VCAM-1 may offer therapeutic strategies for sepsis-induced heart dysfunction.