Nerve growth factor in prostatic fluid as a predictive biomarker in chronic prostatitis/chronic pelvic pain syndrome

Nerve growth factor (NGF) plays a key role as the peripheral mediator of several types of painful inflammatory conditions. In search of new biomarkers with which to more clearly define chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), we investigated whether or not NGF in expressed prostatic secretions (EPS) is correlated with symptom severity in CP/CPPS. All CP/CPPS patients underwent a complete history and physical examination, including the NIH Chronic Prostatitis Symptom Index (NIH-CPSI). EPS samples from 16 patients and 3 asymptomatic controls were collected and frozen. The levels of NGF in EPS were measured by enzyme-linked immunosorbent assay. Patients were asked to complete the questionnaires of NIH-CPSI at baseline and at 8 weeks after treatment. Responders for treatment were defined as a 25% decrease in total NIH-CPSI score from the baseline values. Mean NGF in EPS of CP/CPPS patients and asymptomatic controls were 7,555 ± 3,990 pg/ml and 4,374 ± 825 pg/ml, respectively. The levels of NGF in CP/CPPS patients were correlated directly with pain severity (P = 0.042, r = 0.521), but were not correlated with urinary symptoms or the quality of life. There were no significant differences between pre-treatment and post-treatment levels of NGF in EPS. However, in responders, NGF levels were significantly decreased after successful treatment (P = 0.0165). NGF might contribute to the pathophysiology of CP/CPPS. The NGF level in EPS can change according to pain severity. Therefore, these results suggest that nerve growth factor could be used as a new biomarker to evaluate the symptoms of CP/CPPS and the effects of treatment.