Gene expression analysis of urine sediment: evaluation for potential noninvasive markers of interstitial cystitis/bladder pain syndrome

Purpose: Determine if gene expression profiles in urine sediment could provide non-invasive candidate markers for painful bladder syndrome (PBS) with and/or without Hunner lesions. Materials and Methods: Fresh catheterized urine was collected and centrifuged from control (n = 5), lesion-free (n = 5), and Hunner lesion bearing (n = 3) patients. RNA was extracted from the pelleted material and quantified by gene expression microarray (Affymetrix Human Gene ST Array). Results: Three biologically likely hypotheses were tested: A) all three groups are distinct from one another; B) controls are distinct from both types of PBS patients combined, and C) Hunner lesion PBS patients are distinct from controls and non-Hunner-lesion PBS combined. For statistical parity an unlikely fourth hypothesis was included: non-Hunner-lesion PBS patients are distinct from controls and Hunner lesion PBS combined. Analyses supported selective upregulation of genes in the Hunner lesion PBS group (hypothesis C), and these were primarily associated with inflammatory function. This profile is similar to that reported in a prior microarray study of bladder biopsies in Hunner lesion PBS. Conclusions: Urine sediment gene expression from non-Hunner-lesion PBS patients lacked a clear difference from that of control subjects, while the array signatures from PBS patients with Hunner lesions showed a clear, primarily inflammatory, signature. This signature was highly similar to that seen in a prior microarray study of bladder biopsies. Thus, although sample sizes were small, this work suggests that gene expression in urine sediment may provide a non-invasive biomarker for Hunner lesion, but not non-Hunner lesion, PBS.

13

Blalock EM, Korrect GS, Stromberg AJ, Erickson DR