Inflammation and Symptom Change in Interstitial Cystitis or Bladder Pain Syndrome: A Multidisciplinary Approach to the Study of Chronic Pelvic Pain Research Network Study.

OBJECTIVE To explore inflammatory factors that influence symptom changes in interstitial cystitis or bladder pain syndrome (IC or BPS). This longitudinal, prospective study examined the association of inflammation elicited by Toll-like receptor (TLR) stimulation in peripheral blood mononuclear cells (PBMCs) and diurnal cortisol rhythms with changes in painful and urinary symptoms of IC or BPS and symptom flares over a 48-week period. MATERIALS AND METHODS Participants were 24 women meeting criteria for IC or BPS who supplied blood for isolation of PBMCs and 3 days of salivary cortisol samples prior to a baseline visit. Participants completed the Genitourinary Pain Index (pain and urinary subscales) and reported symptom flares every 2 weeks for 48 weeks. Mixed effects longitudinal and regression models were used to determine if inflammatory variables were associated with the changes in IC or BPS symptoms (time × variable interactions), and the probability of a symptom flare. RESULTS Elevated TLR-4 inflammation (P = .031) and elevated TLR-2 inflammation (P = .045) from PBMCs, and flattened diurnal cortisol slope (P = .012) were each associated with less improvement in genitourinary pain over time. Additionally, elevated TLR-4 inflammation was associated with less improvement in urinary symptoms (P = .018), whereas TLR-2 inflammation and cortisol slopes were not (both P > .16). In contrast, no inflammatory measure was associated with an increased likelihood of reporting a symptom flare (all P > .25). CONCLUSION TLR-mediated inflammation and diurnal cortisol slope may be useful as markers of symptom changes in IC or BPS.