Nerve growth factor does not seem to be a biomarker for neurogenic lower urinary tract dysfunction after spinal cord injury

Urine Biomarkers in the Management of Adult Neurogenic Lower Urinary Tract Dysfunction: A Systematic Review

BACKGROUND

Neurogenic lower urinary tract dysfunction requires lifelong surveillance and management for the perseveration of patients' quality of life and the prevention of significant morbidity and mortality. Urine biomarkers are an attractive noninvasive method of surveillance for these patients. The aim of this systematic review is to search for and critically appraise studies that investigate the clinical usefulness of urine biomarkers in the management of neurogenic lower urinary tract dysfunction (NLUTD) in adults.

METHODS

This review was conducted according to PRISMA and MOOSE guidelines. Search strategy included PubMed, CENTRAL, and Scopus (until October 2022). Studies investigating potential urine biomarkers for the management of adults with NLUTD were included.

RESULTS

Fifteen studies fulfilled the criteria. To date, a variety of different urine molecules have been investigated for the diagnosis and management of neurogenic overactive bladder and detrusor overactivity (nerve growth factor, brain-derived neurotrophic factor, prostaglandin E2, prostaglandin F2α, transformation growth factor β-1, tissue inhibitor metalloproteinase-2, matrix metalloproteinase-2, substance P, microRNA), diagnosis of vesicoureteral reflux (exosomal vitronectin), urinary tract infection (neutrophil gelatinase-associated lipocalin, interleukin 6) and bladder cancer screening (cytology, BTA stat, survivin) in neurological patients.

CONCLUSION

Further studies are needed to specify the utility of each molecule in the management algorithm of adult NLUTD.

Urinary brain-derived neurotrophic factor and nerve growth factor as noninvasive biomarkers of overactive bladder in children

Introduction

Overactive bladder (OAB) is the most common urinary disorder and the leading cause of functional daytime intermittent urinary incontinence in children. The aim of this study was to determine whether urinary brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) concentrations, normalized to urine creatinine, could be used as biomarkers for diagnosis and treatment monitoring of OAB in children.

Materials and methods

Urine samples of 48 pediatric patients with OAB were collected at the start of anticholinergic therapy (baseline), at follow-up visits (3 and 6 months), and from 48 healthy controls. Urinary BDNF and NGF concentrations were determined by ELISA method (Merck, Darmstadt, Germany) and Luminex method (Thermo Fisher Scientific, Waltham, USA). Differences of frequency between quantifiable analyte concentrations between subject groups were determined using Fisher’s exact test.

Results

There was no statistically significant difference between quantifiable analyte concentrations between patients at baseline and the control group for BDNF and NGF by either the ELISA or Luminex method (P = 1.000, P = 0.170, P = 1.000, and P = N/A, respectively). There was a statistically significant difference between quantifiable BDNF by the ELISA method between patients at baseline and complete success follow-up (P = 0.027), while BDNF by Luminex method and NGF by both methods were not statistically significant (P = 0.078, P = 0.519, and P = N/A, respectively).

Conclusions

This study did not demonstrate that urinary BDNF and NGF concentrations, can be used as biomarkers for diagnosis and therapy monitoring of OAB in children.

Biomarkers in Spinal Cord Injury: Prognostic Insights and Future Potentials

Spinal Cord Injury (SCI) is a major challenge in Neurotrauma research. Complex pathophysiological processes take place immediately after the injury and later on as the chronic injury develops. Moreover, SCI is usually accompanied by traumatic injuries because the most common modality of injury is road traffic accidents and falls. Patients develop significant permanent neurological deficits that depend on the extent and the location of the injury itself and in time they develop further neurological and body changes that may risk their mere survival. In our review, we explored the recent updates with regards to SCI biomarkers. We observed two methods that may lead to the appearance of biomarkers for SCI. First, during the first few weeks following the injury the Blood Spinal Cord Barrier (BSCB) disruption that releases several neurologic structure components from the injured tissue. These components find their way to Cerebrospinal Fluid (CSF) and the systemic circulation. Also, as the injury develops several components of the pathological process are expressed or released such as in neuroinflammation, apoptosis, reactive oxygen species, and excitotoxicity sequences. Therefore, there is a growing interest in examining any correlations between these components and the degrees or the outcomes of the injury. Additionally, some of the candidate biomarkers are theorized to track the progressive changes of SCI which offers an insight on the patients' prognoses, potential-treatments-outcomes assessment, and monitoring the progression of the complications of chronic SCI such as Pressure Ulcers and urinary dysfunction. An extensive literature review was performed covering literature, published in English, until February 2018 using the Medline/PubMed database. Experimental and human studies were included and titles, PMID, publication year, authors, biomarkers studies, the method of validation, relationship to SCI pathophysiology, and concluded correlation were reported. Potential SCI biomarkers need further validation using clinical studies. The selection of the appropriate biomarker group should be made based on the stage of the injuries, the accompanying trauma and with regards to any surgical, or medical interference that might have been done. Additionally, we suggest testing multiple biomarkers related to the several pathological changes coinciding to offer a more precise prediction of the outcome.

Sensory Hyperinnervation Distinguishes Bladder Pain Syndrome/Interstitial Cystitis from Overactive Bladder Syndrome

PURPOSE

Pain is the key symptom that distinguishes bladder pain syndrome/interstitial cystitis from overactive bladder syndrome but overlap occurs. To find a discriminating marker for these bladder diseases we examined sensory hyperinnervation and neurotrophin receptor expression in bladder biopsies as well as nerve growth factor levels in urine.

MATERIALS AND METHODS

Bladder biopsies from patients with bladder pain syndrome/interstitial cystitis, including 12 with and 19 without Hunner lesions, 13 with overactive bladder syndrome and 12 healthy controls, were analyzed by immunohistochemistry with antibodies to the nerve cell marker PGP9.5 (neuron-specific protein gene product 9.5), p75^NTR (p75 neurotrophin receptor), the B-lymphocyte marker CD20 and mast cell tryptase. Urinary nerve growth factor was quantified by enzyme-linked immunosorbent assay.

RESULTS

Subepithelial sensory hyperinnervation on PGP9.5 staining had 97% sensitivity and 76% specificity, increased lymphocytic infiltration had 90% sensitivity and 80% specificity, and urothelial defects had 97% sensitivity and 76% specificity to distinguish bladder pain syndrome/interstitial cystitis with and without Hunner lesions from overactive bladder syndrome and healthy controls. Increased sensory innervation was associated with submucosal mast cell localization. Staining of p75^NTR in basal urothelial cells was indicative of bladder pain syndrome/interstitial cystitis. Urinary nerve growth factor levels were below the detection level and did not differentiate bladder diseases from healthy controls.

CONCLUSIONS

Sensory hyperinnervation and basal urothelial p75^NTR staining together with assessment of inflammatory lymphocytes and urothelial integrity allow for the differentiation of bladder pain syndrome/interstitial cystitis and overactive bladder syndrome even in the absence of Hunner lesions. Furthermore, these histopathological criteria enable the identification of early disease stages or oligosymptomatic/asymptomatic cases and may permit timely treatment to prevent disease progress.