Immunohistochemical Assessment of Cardiac Macrophages in the Aged Fischer 344 Rat
Year: 2025
Type: article
Abstract: Macrophages have multiple roles in the heart including immune surveillance and extracellular matrix remodeling. Aging increases both collagen deposition and macrophage number in the heart; however, rodent models used to study cardiac macrophages have age-related comorbidities such as atherosclerosis and hypertension. The Fischer 344 rat does not develop these conditions with aging; therefore, the purpose of this study was to evaluate macrophage number and polarization in the hearts of aged (24-month) and young (6-month) Fischer 344 rats. Paraffin-embedded hearts were assessed for collagen deposition and immunolabeled for CD68, CD163, CD206, and galectin-3. Compared with young rats, significantly greater collagen deposition was observed in the old rats. There were no significant differences in CD68 + or CD163 + cells between age groups, but both CD206 + and galectin-3 + cells were more numerous in the aged animals. Double-immunofluorescence studies demonstrated that galectin-3 colocalized with both CD68 and CD163, suggesting that galectin-3 is found in cardiac macrophages. Further colocalization studies demonstrated similar proportions of CD68 + /CD163 − , CD68 + /CD163 + , and CD68 − /CD163 + cells between age groups, suggesting that aging does not affect macrophage polarization. As CD206 + and galectin-3 + cells promote fibrosis, these results warrant future studies that delineate the specific roles of these cells in the aged heart:
Author: Steven A. Bloomer
Institution: Pennsylvania State University
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $4,400
Funder: Pennsylvania State University
OpenAlex ID: W4414489237