Effects of gender on gene expression in the blood of ischemic stroke patients

Abstract

This study examined the effects of gender on RNA expression after ischemic stroke (IS). RNA obtained from blood of IS patients (n=51; 153 samples at < or =3, 5, and 24 hours) and from matched controls (n=52) were processed on Affymetrix microarrays. Analyses of covariance for stroke versus control samples were performed separately for both genders and the regulated genes for females compared with males. In all, 242, 227, and 338 male-specific genes were regulated at < or =3, 5, and 24 hours after IS, respectively, of which 59 were regulated at all time points. Overall, 774, 3,437, and 571 female-specific stroke genes were regulated at < or =3, 5, and 24 hours, respectively, of which 152 were regulated at all time points. Male-specific stroke genes were associated with integrin, integrin-liked kinase, actin, tight junction, Wnt/β-catenin, RhoA, fibroblast growth factors (FGF), granzyme, and tumor necrosis factor receptor (TNFR)2 signaling. Female-specific stroke genes were associated with p53, high-mobility group box-1, hypoxia inducible factor (HIF)1α, interleukin (IL)1, IL6, IL12, IL18, acute-phase response, T-helper, macrophage, and estrogen signaling. Cell death signaling was overrepresented in both genders, although the molecules and pathways differed. Gender affects gene expression in the blood of IS patients, which likely implies gender differences in immune, inflammatory, and cell death responses to stroke.

Figures

Figure 1

Numbers of genes regulated at different times after ischemic stroke in both genders. (A) Numbers of sex-specific stroke probe sets (for genes) regulated at ⩽3, 5, and 24 hours after ischemic stroke (IS) compared with controls. The top, middle, and bottom Venn diagrams show the ⩽3-, 5-, and 24-hour results, respectively. For each Venn diagram, male-specific IS genes are in the left circle, female-specific IS genes are in the right circle, and the genes regulated in both genders after ischemic stroke (common IS gene) are in the middle, which overlaps both circles. (B) Of the 242, 227, and 338 male-specific IS probe sets at ⩽3, 5, and 24 hours, respectively, after IS, 59 probe sets (representing 44 genes) were regulated at all 3 times (FDR <0.05 and a FC>∣1.5∣). (C) Of the 774, 3,437, and 571 female-specific IS probe sets at ⩽3, 5, and 24 hours, respectively, 152 (representing 119 genes) were regulated at all three times (FDR <0.05 and a FC>∣1.5∣). FC, fold change; FDR, false discovery rate.

Figure 2

Top network that was overrepresented by the genes regulated in whole blood of females but not of males at 24 hours after ischemic stroke. The major apoptosis pathway genes (namely caspase 1, APAF1, NAIP), inflammatory genes (NFκB, Stat 3), and immune-modulatory genes (Inflammasome, NLRC4).

Figure 3

Plot of RNA expression for male- and female-specific ischemic stroke genes. (A) Plot of the RNA expression (Y axis, fold change) for the 59 probe sets (X axis) regulated in males who were underexpressed (41 down) or overexpressed (18 up) at ⩽3 hours (blue diamonds), 5 hours (red triangles), and 24 hours (green circles) after ischemic stroke. The changes of expression for most of the probe sets were similar for the 3-, 5-, and 24-hour time points. (B) Plot of the RNA expression (Y axis, fold change) for the 152 probe sets (X axis) regulated in females who were underexpressed (57 down) or overexpressed (95 up) at ⩽3 hours (blue diamonds), 5 hours (red triangles), and 24 hours (green circles) after ischemic stroke. It must noted that the changes of expression for the 5-hour time point were either decreased compared with other downregulated genes at 3 and 24 hours or were generally increased compared with other upregulated genes at 3 and 24 hours.