Expression of programmed death ligand‐1 on bladder tissues is detected in a clinically and histologically well‐defined interstitial cystitis cohort

Objective To investigate the expression of programmed death ligand‐1 (PD‐L1) in interstitial cystitis (IC). Methods We reviewed the data of IC patients underwent hydrodistension plus bladder biopsy. Follow‐ups were performed. We assessed the degree of inflammation of the bladder wall on slides stained with hematoxylin and eosin (H&E). We performed immunohistochemistry for PD‐L1 expression detection and for counting T lymphocytes and B lymphocytes. Results The present study included eight men and 32 women. With H&E staining, we detected 13, 15, and 12 patients with mild, moderate, and severe inflammation. The degree of inflammation was negatively correlated with disease course ( P = 0.018) and positively correlated with bladder pain ( P < 0.001). Hydrodistension was found effective at postoperative 3‐month for 19 patients. Overall, 17, 15, 7, and 1 subject had no, mild, moderate, and high PD‐L1 expression, that correlated positively with the degree of inflammation. Compared with patients with no and mild PD‐L1 expression, patients with moderate and high PD‐L1 expression tended to have more effective hydrodistension outcomes (12 of 32 vs 7 of 8; P = 0.017). In the subset of 12 patients with severe inflammation, there were five of six patients (83.3%) with moderate or high PD‐L1 expression and one of six patients (16.7%) with no and mild PD‐L1 expression with an effective hydrodistension outcome. Conclusions Expression of PD‐L1 on bladder is detected in a cohort of IC patients presented with diffuse global glomerulation or Hunner ulcer. PD‐L1 expression is more common in IC patients with severe bladder inflammation.