EVALUATION OF SPATIAL PD1 AND PD-L1 EXPRESSION IN INFLAMMATORY BOWEL DISEASE SAMPLES – A PILOT STUDY

Alterations of PD1/PD-L1 pathway may be associated with an excessive inflammatory response in the intestinal wall in inflammatory bowel diseases (IBD). To evaluate the expression of PD-1 and PD-L1 in 4 compartments of intestinal wall (mucosa, submucosa, muscularis propria and lymphatic follicles), high-resolution immunohistochemically stained slides were obtained from formalin-fixed paraf-fin-embedded samples of 10 Crohn’s disease (CD), 9 ulcerative colitis (UC) and 10 unaffected individuals cases. The levels of expression were quantified using the Qu-Path software. PD-1 was detected in lymphatic follicles in affected and unaffected tissue samples and in inflammatory infiltration in IBD. There was no difference between groups neither in PD-1 overall expression nor in individual compartments, with the ex-ception of the mucosal expression. It was higher in the mucosa of CD patients comparing to controls, however this difference was marginal (p = 0.0461). PD-L1 was expressed in endothelium and mesenteric nervous plexi, consistently in each group. There were no significant differences in PD-L1 immunoreactivity in context of histologic compartment nor clinical diagnosis. The results suggest that PD-1 and PD-L1 expression in intestinal tissue is heterogeneous in the analysed groups, thus it may be dependent on individual characteristics.