Gender and age-related variability of macrophage representation in the internal thoracic artery wall: does it matter?

Area of Science:

• Cardiovascular Surgery
• Immunohistochemistry
• Vascular Biology

Background:

• Coronary artery bypass grafting (CABG) outcomes can vary, with some reports indicating reduced benefits for elderly and female patients receiving a second internal thoracic artery (ITA).
• Macrophages, identified by CD68+ cells, are implicated in the pathogenesis of atherosclerosis and the failure of aortocoronary grafts.

Purpose of the Study:

• To investigate the association between patient age and gender and the distribution of CD68+ cells within the different layers of the ITA wall.
• To explore potential immunological explanations for observed disparities in CABG outcomes related to ITA utilization.

Main Methods:

• Analysis of surplus distal ITA segments from 158 patients (95 male, 63 female) undergoing elective CABG.
• Immunohistochemical assessment to quantify and map the distribution of CD68+ cells in the tunica intima, tunica media, and tunica adventitia.

Main Results:

• CD68+ cells were detected in all ITA samples, with a higher median count in women (55) compared to men (42) (p<0.001), primarily in the tunica intima.
• Approximately 70% of CD68+ cells were located in the tunica adventitia.
• A positive correlation was observed between the total number of CD68+ cells in the arterial wall (including tunica intima and adventitia) and patient age.

Conclusions:

• Increased CD68+ cell populations, especially within the tunica intima of the ITA, may contribute to the diminished benefits of using a second ITA in elderly and female CABG patients.
• Further long-term clinical studies with larger patient cohorts are warranted to validate these immunohistochemical findings and their clinical implications.