Results
In total 38 participants were included in this study, of whom 19 IBD walkers, 19 non-IBD walkers. One IBD walker fell during exercise on day 1 and dropped out, he was excluded from all statistical analysis. Clinical disease characteristics of IBD patients are shown in Table 1. The IBD study groups consisted of 8 patients with Crohn’s disease and 10 patients with ulcerative colitis. The mean age of diagnosis was 33 ± 13 years. One year before the walking event, a total of 8 (44%) IBD patients had no flare-ups, 6 patients had one to two flare-ups and 4 patients had three of more flare-ups. Baseline characteristics of both between the IBD walkers and the age/gender-matched control group are shown in table 2. The mean age of the study population was 54 ± 12 years and the average BMI of all participants was 26.0 ± 3.8 kg/m2. In each group, 11 participants were female. No significant differences were found between IBD walkers and non-IBD walkers regarding participant characteristics, except for training distance during the last two weeks before the walking event (IBD walkers vs non-IBD walkers, p=0.03).
Responsiveness to fMLF, determined by flow cytometric determination of innate immune markers, is shown in Figure 1. The cellular responsiveness to fMLF is shown as the Median Fluorescent Intensity(MFI) of innate immune markers: Neprilysine (CD10) (Figure 1A), Complement receptor 3 (CD11b) (Figure 1C-D) , Complement receptor 1 (CD35) (Figure 1 E-G) and L-selectin (CD62L) (Figure 1H-J).
Smaller increased responsiveness to fMLF was shown after 3 days of prolonged exercise in the expression of the activation markers CD11b and CD35 in IBD walkers compared to non-IBD walkers in neutrophils (p=0.01; p=0.03) and monocytes (p=0.001; p=0.008). No difference in CD11b and CD35 expression was demonstrated between the study groups at baseline measurements. No difference in responsiveness was seen in the cell adhesion receptor CD62L in neutrophils, monocytes and eosinophils between the study groups. The maturation/activation marker CD10 showed similar smaller increased responsiveness to fMLF after 3 days of repeated prolonged exercise in IBD walkers compared to non-IBD walkers in neutrophils (p=0.005). However, already at day 0, a lower expression of CD10 was demonstrated in the neutrophil compartment of IBD walkers compared to non-IBD walkers (p=0.01).