Nerve growth factor (NGF): a potential urinary biomarker for overactive bladder syndrome (OAB)?

• Published in: BJU international Vol. 111; no. 3; pp. 372 - 380
• Main Authors: Seth, Jai H., Sahai, Arun, Khan, Mohammad S., van der Aa, Frank, de Ridder, Dirk, Panicker, Jalesh N., Dasgupta, Prokar, Fowler, Clare J.
• Format: Journal Article
• Language: English
• Published: Oxford Wiley-Blackwell 01.03.2013; Wiley Subscription Services, Inc
• Subjects: Animals; Biological and medical sciences; biomarker; Biomarkers; Biomarkers - urine; Bladder; Botulinum Toxins, Type A - therapeutic use; Cats; Enzyme-Linked Immunosorbent Assay - methods; Evidence-Based Medicine; Excretory system; Female; Humans; Medical disorders; Medical sciences; Mice; Muscarinic Antagonists - therapeutic use; Nephrology. Urinary tract diseases; nerve growth factor; Nerve Growth Factor - urine; Neuromuscular Agents - therapeutic use; overactive bladder; Rats; Sensitivity and Specificity; Studies; Treatment Outcome; Urinary Bladder, Overactive - drug therapy; Urinary Bladder, Overactive - physiopathology; Urinary Bladder, Overactive - urine; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland; Nephrology; Urinary system disease; Urinary system; Urinary bladder; Biological marker; Nerve growth factor; Biological indicator; Overactive bladder; Bladder disease; Urinary tract disease; biomarker; Urology
• ISSN: 1464-4096; 1464-410X; 1464-410X
• DOI: 10.1111/j.1464-410X.2012.11672.x

What's known on the subject? and What does the study add? The search for a biomarker in overactive bladder syndrome (OAB) is an emerging field of interest, as bladder dysfunction is a common complaint that causes significant morbidity. A biomarker may give us insight as a diagnostic tool, and also inform us about how severe the condition is, how it may progress and how it may best be treated. The protein of interest here is nerve growth factor (NGF) and it has been shown to be a dynamic molecule in the bladder of patients with OAB. Urinary levels have been seen to rise in patients with OAB and fall in those who respond to treatment. However, there have also been many studies that examine this trend in numerous other conditions, e.g. interstitial cystitis, bladder outflow obstruction, renal stone disease and patients with neurological impairment after stroke. As a result the specificity of this as a potential urinary biomarker for OAB is questioned. This is a review of published studies, which discusses the pros and cons of NGF as a potential urinary biomarker. The evidence is examined and the studies are summarised together in a Table. Questions remain about the reliability, practicality and specificity of NGF as a biomarker for OAB. These questions need to be addressed by further studies that could clarify the points raised. Objective To review the current literature on the use of urinary nerve growth factor (NGF) as a potential biomarker for overactive bladder syndrome (OAB). Method A comprehensive electronic literature search was conducted using the PubMed database to identify publications relating to urinary NGF. Results There are a growing number of publications that have measured urinary NGF levels in different types of bladder dysfunction. These range from OAB, bladder pain syndrome, idiopathic and neurogenic detrusor overactivity, bladder oversensitivity and bladder outflow obstruction. Urinary NGF levels do appear to be raised in these pathological states when compared with healthy control samples. In patients with OAB, these raised urinary NGF levels appear to also reduce after successful treatment with antimuscarinics and botulinum toxin A, which indicates a potential use in monitoring responses to treatment. However, raised levels are not limited to OAB, which questions its specificity. Urinary NGF measurements are performed with an enzyme‐linked immunosorbent assay using polyclonal antibodies to NGF. The technique requires standardisation, and the different antibodies to NGF require validating. Also a definition of what is the ‘normal’ range of NGF in urine is still required before it can be used as a diagnostic and prognostic tool. Conclusions Whilst the evidence for an increased urinary NGF in OAB appears convincing, many questions about its validity remain including: specificity, sensitivity, cost‐ and time‐effectiveness. Many criteria for what constitutes a biomarker still need to be evaluated and met before this molecule can be considered for this role.