Gender- and menstrual phase dependent regulation of inflammatory gene expression in response to aerobic exercise.

The immunological reaction to exercise has been investigated with increasing intensity in the last 10-20 years, with most human studies performed in male subjects. Recently, gender-specific aspects have received growing attention, but studies carefully monitoring the influence of gender including the menstrual cycle, are rare. Here, we report gene expression patterns in response to a run at 93% of the individual anaerobic threshold of 9 women with regular menstrual cycles and no use of oral contraceptives who ran both at day 10 (follicular phase, F) and at day 25 (luteal phase, L) of their cycle. 12 male subjects (M) served as controls. The mRNA was pooled group wise and processed on a gene expression microarray encompassing 789 genes, including major genes of the inflammatory and anti-inflammatory reaction. The differences of gene expression between time points to (before run) and t1 (after run) were analyzed. Females in L showed a higher extent of regulation than females in F or men. Among those genes which were up-regulated above 1.5 fold change (log2) pro-inflammatory genes were significantly enriched (p = 0.033, after Bonferroni correction) in L, while this was not the case in F or M. Conversely, women in L showed a strong trend towards downregulation of anti-inflammatory genes. Some prominent genes like IL6 (coding for interleukin-6), and IL1RN (also termed IL1RA, coding for interleukin-1 receptor antagonist) were clearly regulated in opposite directions in L as opposed to F and M. In conclusion, women in L showed a distinctly different pattern of gene regulation in response to exercise, compared with women in F or M. The overall direction of gene expression changes of women in L is clearly pro-inflammatory. This finding accentuates a need for careful consideration of the female cyclic phase when investigating women in exercise immunology studies. Our results may also have implications relevant to other forms of stress in females.