Female gender appears to be protective in the development of
abdominal aortic aneurysms (AAAs). This study sought to identify gender differences in
cytokine and
chemokine expression in an experimental rodent AAA model. Male and female rodent aortas were perfused with either saline (control) or
elastase to induce AAA formation. Aortic diameter was determined and aortic tissue was harvested on postperfusion days 4 and 7.
Cytokine and
chemokine gene expression was examined using focused gene arrays. Immunohistochemistry was used to quantify aortic leukocyte infiltration. Data were analyzed by Student's t-tests and ANOVA.
Elastase-perfused female rodents developed significantly smaller
aneurysms compared to males by day 7 (93 +/- 10% vs. 201 +/- 25%, P = 0.003).
Elastase-perfused female aortas exhibited a fivefold decrease in expression of the BMP family and
ligands of the TNF superfamily compared to males. In addition, the expression of members of the
TGF beta and
VEGF families were three to fourfold lower in female
elastase-perfused aortas compared to males. Multiple members of the
interleukin,
CC chemokine receptor, and CC
ligand families were detectable in only the male
elastase-perfused aortas. Female
elastase-perfused aortas demonstrated a corollary twofold lower neutrophil count (females: 17.5 +/- 1.1 PMN/HPF; males: 41 +/- 5.2 neutrophils/HPF, P = 0.01) and a 1.5-fold lower macrophage count (females: 12 +/- 1.1 macrophages/HPF; males: 17.5 +/- 1.1 macrophages/HPF, P = 0.003) compared to male
elastase-perfused aortas. This study documents decreased expression of multiple
cytokines and
chemokines and diminished leukocyte trafficking in female rat aortas compared to male aortas following
elastase perfusion. These genes may contribute to the gender disparity seen in AAA formation.