Serum Cytokine Profiling in Cats with Acute Idiopathic Cystitis.

Background: Feline idiopathic cystitis (FIC) is a common lower urinary tract disorder of domestic cats that resembles interstitial cystitis/painful bladder syndrome (IC/PBS) in humans. Diagnosis of FIC is based on clinical signs and exclusion of other disorders because of a lack of specific pathologic findings or other objective biomarkers. Cytokines are potential noninvasive biomarkers to define the presence, severity, and progression of disease, and response to treatment. Objectives: The objective of this pilot study was to determine concentrations of selected cytokines in serum from healthy cats and cats with acute FIC. Animals: Serum samples from 13 healthy cats and from 12 cats with nonobstructive acute FIC were utilized. Methods: Multiplex analysis of 19 cytokines (CCL2, CCL5, CXCL1, CXCL12, CXCL8, Flt3L, GM-CSF, IFN-c, IL-12 (p40), IL-13, IL-18, IL-1b, IL-2, IL-4, IL-6, PDGF-BB, SCF, sFas, and TNF-alpha) was performed with a commercially available feline-specific multiplex bead-based assay. Results: Mean serum concentrations of IL-12 (p40; P < 0.0001), CXCL12 (P = 0.002), IL-18 (P = 0.032), and Flt3L (P = 0.0024) were significantly increased in FIC cats compared to healthy cats. GM-CSF, IL-1b, IL-2, and PDGF-BB were undetectable or detected in an insufficient number of cats to allow meaningful comparisons. Conclusions and Clinical Importance: We have identified increased serum concentrations of pro-inflammatory cytokines and chemokines CXCL12, IL-12, IL-18, and Flt3L in FIC-affected cats. These findings suggest potential candidates for noninvasive biomarkers for diagnosis, staging, and therapeutic outcome monitoring of affected cats and provide additional insight into the etiopathogenesis of FIC.