Nerve growth factor serum concentrations in healthy human volunteers: physiological variance and stability

Plasma calcitonin gene-related peptide and nerve growth factor as headache and pain biomarkers in recently deployed soldiers with and without a recent concussion

OBJECTIVE

The objective of this study was to characterize the utility of calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) as potential biomarkers for headache and pain disorders in the post-military deployment setting.

BACKGROUND

The need to improve recognition, assessment, and prognoses of individuals with posttraumatic headache or other pain has increased interest in the potential of CGRP and NGF as biomarkers.

METHODS

The Warrior Strong Study (NCT01847040) is an observational longitudinal study of United States-based soldiers who had recently returned from deployment to Afghanistan or Iraq from 2009 to 2014. The present nested cross-sectional analysis uses baseline data collected from soldiers returning to Fort Bragg, North Carolina.

RESULTS

In total, 264 soldiers (mean (standard deviation [SD] age 28.1 [6.4] years, 230/264 [87.1%] men, 171/263 [65.0%] White) were analyzed. Mean (SD) plasma levels of CGRP were 1.3 (1.1) pg/mL and mean levels of NGF were 1.4 (0.4) pg/mL. Age was negatively correlated with NGF (-0.01 pg/mL per year, p = 0.007) but was not associated with CGRP. Men had higher mean (SD) CGRP plasma levels than women (1.4 95% confidence interval [CI; 1.2] vs. 0.9 95% CI [0.5] pg/mL, p < 0.002, Kruskal-Wallis test). CGRP levels were lower in participants who had a headache at the time of the blood draw (1.0 [0.6] pg/mL vs. 1.4 [1.2] pg/mL, p = 0.024). NGF was lower in participants with continuous pain (all types; 1.2 [0.4] vs. 1.4 [0.4] pg/mL, p = 0.027) and was lower in participants with traumatic brain injury (TBI) + posttraumatic headache (PTH) versus TBI without PTH (1.3 [0.3] vs. 1.4 [0.4] pg/mL, p = 0.021). Otherwise, CGRP and NGF were not associated with migraine-like headache, TBI status, or headache burden as measured by the number of medical encounters in crude or adjusted models.

CONCLUSION

In this exploratory study, plasma levels of NGF and CGRP showed promise as biomarkers for headache and other types of pain. These findings need to be replicated in other cohorts.

Prediction of relative change in free nerve growth factor following subcutaneous administration of tanezumab, a novel monoclonal antibody to nerve growth factor

Tanezumab is a monoclonal antibody against nerve growth factor (NGF). We investigated tanezumab pharmacokinetic (PK)-NGF relationships and predicted the extent of systemic free NGF suppression with target-mediated drug disposition (TMDD) modeling using data from three pivotal phase III interventional studies (NCT02697773, NCT02709486, and NCT02528188) in patients with osteoarthritis. Patients received tanezumab 2.5 mg or 5 mg every 8 weeks (q8w) subcutaneously. A TMDD model using a previously established population PK model was used to describe plasma tanezumab and serum total NGF concentration data, and simulations were performed to predict "unobserved" free NGF versus time profiles and dose-response relationships for free NGF. A total of 2992 patients had available data for plasma tanezumab or serum total NGF concentrations and were included in the analysis; 706 of these had data for both tanezumab and total NGF concentrations. The model generally performed well to predict observed total NGF concentrations up to ~24 weeks after each dose. Simulations suggested free NGF concentration would be suppressed by ~75% (median) near the peak of tanezumab concentration and by less than 5% (median) around the trough tanezumab concentration with a tanezumab 2.5 mg q8w regimen. Free NGF concentration was predicted to return to baseline level at ~8 weeks (95% prediction interval: 5-16 weeks) after the last tanezumab dose. This model adequately described plasma tanezumab and serum total NGF concentrations following s.c. administration of tanezumab 2.5 or 5 mg q8w, allowed prediction of relative change in systemic free NGF following s.c. administration of tanezumab.

Circulating and Salivary NGF and BDNF Levels in SARS-CoV-2 Infection: Potential Predictor Biomarkers of COVID-19 Disease-Preliminary Data

COVID-19 continues to afflict the global population, causing several pathological diseases and exacerbating co-morbidities due to SARS-CoV-2's high mutation. Recent interest has been devoted to some neuronal manifestations and to increased levels of Nerve Growth Factor (NGF) and Brain-derived Neurotrophic Factor (BDNF) in the bloodstream during SARS-CoV-2 infection, neurotrophins that are well-known for their multifactorial actions on neuro-immune-endocrine and visual functions. Nineteen (19) patients were enrolled in this monocentric prospective study and subjected to anamnesis and biosamples collection (saliva and blood) at hospitalization (acute phase) and 6 months later (remission phase). NGF and BDNF were quantified by ELISA, and biochemical data were related to biostrumental measurements. Increased NGF and BDNF levels were quantified in saliva and serum during the acute phase of SARS-CoV-2 infection (hospitalized patients), and reduced levels were observed in the next 6 months (remission phase), never matching the baseline values. Salivary and circulating data would suggest the possibility of considering sera and saliva as useful matrices for quickly screening neurotrophins, in addition to SARS-CoV2 antigens and RNA. Overall, the findings described herein highlight the importance of NGF and BDNF as dynamic biomarkers for monitoring disease and reinforces the possibility of using saliva and sera for quick, non-invasive COVID-19 screening.

Neurocognitive Effects of Cocoa and Red-Berries Consumption in Healthy Adults

In recent decades, the elderly population has increased at higher rates than any other population group, resulting in an increase in age-related diseases such as neurodegenerative and cognitive impairment. To address this global health problem, it is necessary to search for new dietary strategies that can prevent the main neurocognitive problems associated with the ageing process. Therefore, the aim of the present study was to analyze the effect of cocoa flavanols and red berry anthocyanins on brain-derived neurotrophic factor (BDNF) and nerve growth factor receptor (NGF-R) and to stablish the possible improvement in cognitive performance by using a battery of neurocognitive tests that included the Verbal Learning Test Spain-Complutense, the Spatial Recall Test 10/36 BRB-N, the Wechsler Adult Intelligence Scale III and IV, the STROOP Task and the Tower of London Test. A randomized, double-blind, parallel-group study was performed in 60 healthy volunteers between 50 and 75 years old who consumed a cocoa powder, a red berries mixture or a combination of both for 12 weeks. After the intervention, we observed a reduction in the time needed to start (p = 0.031) and finish (p = 0.018) the neurocognitive test known as the Tower of London in all groups, but the decrease in time to finish the task was more pronounced in the intervention with the combination of cocoa-red berries group. We failed to show any significant difference in BDNF and NGF-R sera levels. However we found a negative correlation between BDNF and the number of movements required to finish the TOL in women (p = 0.044). In conclusion, our study showed an improvement in executive function, without any change in neurotrofin levels, for all intervention arms.

Impact of intradetrusor botulinum toxin A injections on serum and urinary concentrations of nerve growth factor and brain-derived neurotrophic factor in patients with multiple sclerosis and neurogenic detrusor overactivity

AIMS

To evaluate the practical relevance of changes in serum and urinary neurotrophins levels in patients with multiple sclerosis (MS) and neurogenic lower urinary tract dysfunction (NLUTD) after intradetrusor injections of botulinum toxin A (BoNTA).

METHODS

The study included 36 patients with MS and NLUTD and 20 controls. The patients with NLUTD received intradetrusor injection of BoNTA (200 U). The nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) levels were measured in serum and urine at baseline and then at 1, 3, and 6 months by enzyme-linked immunosorbent assay. Urinary NGF and BDNF were normalized to creatinine (NGF/Cr, BDNF/Cr). Patients' assessment included urodynamic examination and Neurogenic Bladder Symptom Score (NBSS).

RESULTS

After BoNTA injections, no significant changes were observed in the serum NGF and BDNF or the urinary BDNF/Cr. The urinary NGF/Cr was significantly higher in MS patients (1.23 ± 0.34) at baseline compared with controls (0.084 ± 0.02; p = .021). The urinary NGF/Cr decreased to 0.51 ± 0.12 (p = .001) and 0.53 ± 0.32 (p = .005) at 1 and 3 months, increasing to 1.12 ± 0.49 (p = .003) at 6 months. The urinary NGF/Cr level at baseline demonstrated a low diagnostic accuracy in predicting a better response to the BoNTA treatment (area under the curve = 0.661; p = .047) and no correlation with the urodynamic parameters.

CONCLUSIONS

The urinary NGF/Cr at baseline or its reduction at the first month following treatment does not serve as a predictor for the response to the BoNTA injections or for urodynamic changes.

The Role of Nerves in Skeletal Development, Adaptation, and Aging

The skeleton is well-innervated, but only recently have the functions of this complex network in bone started to become known. Although our knowledge of skeletal sensory and sympathetic innervation is incomplete, including the specific locations and subtypes of nerves in bone, we are now able to reconcile early studies utilizing denervation models with recent work dissecting the molecular signaling between bone and nerve. In total, sensory innervation functions in bone much as it does elsewhere in the body-to sense and respond to stimuli, including mechanical loading. Similarly, sympathetic nerves regulate autonomic functions related to bone, including homeostatic remodeling and vascular tone. However, more study is required to translate our current knowledge of bone-nerve crosstalk to novel therapeutic strategies that can be effectively utilized to combat skeletal diseases, disorders of low bone mass, and age-related decreases in bone quality.

Nerve Growth Factor Serum Levels Are Associated With Regional Gray Matter Volume Differences in Schizophrenia Patients

Numerous neuroimaging studies have revealed structural brain abnormalities in schizophrenia patients. There is emerging evidence that dysfunctional nerve growth factor (NGF) signaling may contribute to structural brain alterations found in these patients. In this pilot study, we investigated whether there was a correlation between NGF serum levels and gray matter volume (GMV) in schizophrenia patients. Further, we investigated whether there was an overlap between the correlative findings and cross-sectional GMV differences between schizophrenia patients (n = 18) and healthy controls (n = 19). Serum NGF was significantly correlated to GMV in the left prefrontal lobe, the left midcingulate cortex, and the brainstem in schizophrenia patients. However, we did not find any correlations of NGF serum levels with GMV in healthy controls. Schizophrenia patients showed smaller GMV than healthy controls in brain regions located in the bilateral limbic system, bilateral parietal lobe, bilateral insula, bilateral primary auditory cortex, left frontal lobe, and bilateral occipital regions. In a conjunction analysis, GMV in the left midcingulate cortex (MCC) appears negatively correlated to NGF serum levels in the group of schizophrenia patients and also to be reduced compared to healthy controls. These results suggest an increased vulnerability of schizophrenia patients to changes in NGF levels compared to healthy controls and support a role for NGF signaling in the pathophysiology of schizophrenia. As our pilot study is exploratory in nature, further studies enrolling larger sample sizes will be needed to further corroborate our findings and to investigate the influence of additional covariates.

Therapeutic and protective effects of autologous serum in amikacin-induced ototoxicity

OBJECTIVE

Possible therapeutic and protective benefits of intratympanic autologous serum application in amikacin-induced ototoxicity were investigated.

METHODS

Twenty-four guinea pigs were separated equally into two groups: therapeutic (group A) and protective (group B). Transient evoked otoacoustic emissions were recorded before and after autologous serum application. Apoptotic cells were identified in the organ of Corti, spiral limbus and spiral ganglion by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling ('TUNEL') method.

RESULTS

Transient evoked otoacoustic emission responses at 1, 1.4 and 2.8 kHz improved without significance after autologous serum application in group A (p > 0.05). A significantly protective effect of autologous serum was determined at 4 kHz in group B (p < 0.05). There were significantly fewer apoptotic cells at the spiral limbus in the therapeutic and protective groups compared to the control group (p < 0.05).

CONCLUSION

Autologous serum may offer protection against ototoxicity-induced hearing loss, but it cannot restore hearing. Immunohistochemically, autologous serum significantly decreases activation of the intrinsic pathway of pro-apoptotic signalling in mesenchymal cells compared to neurons and neurosensory cells.

Nerve growth factor is critical requirement for in vitro angiogenesis in gastric endothelial cells

Angiogenesis is critical for the healing of gastric mucosal injury and is considered to be primarily regulated by vascular endothelial growth factor (VEGF), the fundamental proangiogenic factor. The role of nerve growth factor (NGF) in gastric angiogenesis is unknown. We examined the expression of NGF and its TrkA receptor in endothelial cells (ECs) isolated from gastric mucosa of rats (GMECs), the effect of NGF treatment on in vitro angiogenesis in GMECs, and, the mechanisms underlying NGF's proangiogenic actions. Isolated GMECs from Fisher rats were treated with vehicle, NGF (10-1,000 ng/ml), VEGF (20 ng/ml), or NGF+VEGF. To determine whether and to what extent NGF is critical for angiogenesis in GMECs, we silenced NGF expression using specific siRNA and examined in vitro angiogenesis with and without treatment with exogenous NGF and/or VEGF. Treatment of GMECs with NGF significantly increased in vitro angiogenesis similar to that seen in GMECs treated with VEGF. Silencing of NGF in GMECs abolished angiogenesis, and this effect was reversed only by exogenous NGF but not VEGF, which indicates a direct proangiogenic action of NGF on GMECs that is, at least in part, distinct and independent of VEGF. NGF's proangiogenic action on GMECs was mediated via PI3-K/Akt signaling. This study showed for the first time that gastric mucosal ECs express NGF and its receptor TrkA and that NGF is critical for angiogenesis in these cells.

Peripheral Levels of BDNF and NGF in Primary Headaches

Neurotrophins, such as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), have been implicated in the generation and modulation of pain. To investigate whether alterations in neurotrophin levels can be detected in subjects suffering from nociceptive disorders, such as primary headaches, we determined the peripheral (platelet and plasma) levels of BDNF and NGF in patients suffering from migraine, with or without aura, or cluster headache (CH), in the interictal phase, and in healthy volunteers. All primary headaches patients studied showed significantly decreased platelet levels of BDNF (migraine vs. controls P < 0.001; CH vs. controls P < 0.01), while a selective reduction of platelet NGF was observed in migraine sufferers and not in CH patients compared with control subjects (migraine vs. controls P < 0.001). These changes were not accompanied by significant modifications of neurotrophin plasma levels. Our findings show for the first time that changes in peripheral levels of neurotrophines (BDNF and NGF) occur in patients suffering from different types of primary headaches, suggesting a potential involvement of BDNF and NGF in the pathophysiology of these disorders, and raising the possibility that differences in peripheral neurotrophins may help to distinguish migraine biologically from CH.

Potential Biomarkers Utilized to Define and Manage Overactive Bladder Syndrome

Clinical diagnosis of overactive bladder (OAB) syndrome has great variation and usually can only be based on subjective symptoms. Measurement of urgency severity score in adjunct with voiding diary may reflect the occurrence of OAB and incontinence severity in daily life. Urodynamic study can detect detrusor overactivity (DO), but not in all OAB patients. A more objective way and less invasive tool to diagnose and assess therapeutic outcome in OAB patients is needed. Recent investigations of the potential biomarkers for OAB include urinary and serum biomarkers and bladder wall thickness. Evidence has also shown that urinary proteins, such as nerve growth factor (NGF) and prostaglandin E2 (PGE2 ) levels increase in patients with OAB, bladder outlet obstruction (BOO) and DO. Patients with OAB have significantly higher urinary NGFlevels and urinary NGF levels decrease after antimuscarinic therapy and further decrease after detrusor botulinum toxin injections. However, the sensitivity of single urinary protein in the diagnosis of OAB is not high and several lower urinary tract diseases may also have elevated urinary NGF levels. Searching for a group of inflammatory biomarkers by microsphere-based array in urine might be a better method in differential diagnosis of OAB from interstitial cystitis, urinary tract infection (UTI) or urolithiasis. Bladder wall thickness has been widely investigated in the diagnosis of BOO and pediatric voiding dysfunction.The role of bladder wall thickness in the diagnosis of OAB, however, has not reach a consistent conclusion. We hereby review the latest medical advances in this field.

Effect of new neuronal growth factor on healing of sciatic nerve in rats

OBJECTIVE

The study aimed to investigate the effect of a new peptide new nerve growth factor (NNGF) on the healing of divided sciatic nerves in rats.

MATERIAL AND METHODS

Twenty Sprague-Dawley rats of 250-300g were divided into two groups (group 1 - study group and group 2 - control group). Under ketamine intramuscular anesthesia sciatic nerves were exposed, divided and repaired using 10/0 dexon. Study animals had 10mg/kg body weight of NNGF added to the repair. Electromyographic studies of the hind libs were carried out after 8weeks. The average stimulation was 50mA for 200μS and four twitches (T) were recorded. The animals were euthanized and the sciatic nerves were removed for histological analysis.

RESULTS

There were no deaths in either of the groups. Electromyographic study showed that in the control group the average T1-T4 was 0.587±0.17% and in the study group the average was 87.89±5.02% (p value of 0.001). Histologically the control group showed regenerated axons sprouting from the proximal segment of cut nerve with empty endoneurial channels, while in the study group whole nerve trunks were seen within endoneurial channels.

CONCLUSION

This study shows that the NNGF has a positive influence on the experimental healing of sciatic nerves in animals.

Harm avoidance involved in mediating the association between nerve growth factor (NGF) gene polymorphisms and antidepressant efficacy in patients with major depressive disorder

BACKGROUND

Antidepressants have variable efficacies in subjects with major depressive disorder (MDD). Nerve growth factor (NGF) has been suggested to play an important role in the pathogenesis of depressive symptoms and the response to antidepressant therapy. The aim of this study was to examine whether NGF gene polymorphisms are associated with the antidepressant therapeutic efficacy in subjects with MDD.

METHODS

A naturalistic follow-up study was carried out on 557 subjects with MDD. Of the enrolled patients, 304 completed the 8-week open-label antidepressant treatment. Seven single-nucleotide polymorphisms (SNPs) of the NGF gene were genotyped. The 21-item Hamilton Depression Rating Scale was used to assess depressive severity from baseline to endpoint. Tridimensional Personality Questionnaire was used to assess baseline personality traits. Single marker and haplotype analyses were conducted. Binary logistic regression was used to calculate odds ratios of remission. Structural equation modeling was used to analyze the predicted mediation effect.

RESULTS

A significant difference in genotype frequencies between remitters and non-remitters was observed in three NGF SNPs (rs12760036, rs7523654, and rs17033692). The haplotype analysis revealed that the CCC haplotype (rs2254527-rs6678788-rs12760036) was associated with a higher remission rate, while the CCA haplotype was associated with a lower remission rate. The harm avoidance psychological factor partially mediated the effect of NGF variants on antidepressant efficacy.

LIMITATIONS

The selected SNPs may not cover whole NGF gene.

CONCLUSIONS

NGF variants are associated with remission rates after 8-week antidepressant treatment, and harm avoidance partially mediated the effect of NGF variants on treatment outcomes.

Proinflammatory and anti-inflammatory cytokine changes related to menopause

The aim of the study

The aim of the study was to determine menopause-related changes in serum levels of main proinflammatory and anti-inflammatory cytokines.

Material and methods

The study included 175 women, who were divided into 5 study groups (group 1 – fertile women; group 2 – pre- and perimenopausal women; group 3 – postmenopausal women; group 4 – surgically induced menopausal women; group 5 – women with chronic inflammatory pathology). We evaluated the serum levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-17, IL-20 and of the tumour necrosis factor (TNF)α with the use of two multiplex cytokine kits. We also determined the serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (17β-E2), progesterone (P), dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) using sandwich ELISA.

Results

The serum level of IL-1β, IL-8 and TNF-α in women with natural menopause and in women with surgically induced menopause is significantly higher than in fertile women in the control group. In patients with surgically induced menopause and in women with natural menopause, IL-8 serum levels are similar to those seen in patients with chronic inflammatory diseases. There is a statistically significant decrease in serum levels of IL-20 in women with natural or surgical menopause than in fertile and premenopausal women.

Conclusions

Women in menopause have elevated levels of the key proinflammatory cytokines, i.e. IL-1β, IL-8 and TNF-α and low serum levels of IL-20 in comparison with fertile women.

Serum nerve growth factor (NGF) levels in children with attention deficit/hyperactivity disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed neurobehavioral disorder of childhood. The etiopathogeny of ADHD has not been totally defined. Recent reports have suggested a pathophysiological role of neurotrophins in ADHD. In this study, we evaluated serum levels of nerve growth factor (NGF) in patients with ADHD. The sample population consisted of 44 child or adolescent patients diagnosed with ADHD according to DSM-IV criteria; 36 healthy subjects were included in the study as controls. Venous blood samples were collected, and NGF levels were measured. The mean serum NGF levels of the ADHD patients were significantly higher than those of the controls. Age and gender of the patients were not correlated with serum NGF levels. There were no significant differences in NGF levels among the combined and predominantly inattentive subtypes of ADHD. Our study suggests that there are higher levels of serum NGF in drug naive ADHD patients, and that increased levels of NGF might have an important role in the pathophysiology of ADHD.

DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration

Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

Gender effect on neurodegeneration and myelin markers in an animal model for multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) varies considerably in its incidence and progression in females and males. In spite of clinical evidence, relatively few studies have explored molecular mechanisms possibly involved in gender-related differences. The present study describes possible cellular- and molecular-involved markers which are differentially regulated in male and female rats and result in gender-dependent EAE evolution and progression. Attention was focused on markers of myelination (MBP and PDGFαR) and neuronal distress and/or damage (GABA synthesis enzymes, GAD65 and GAD67, NGF, BDNF and related receptors), in two CNS areas, i.e. spinal cord and cerebellum, which are respectively severely and mildly affected by inflammation and demyelination. Tissues were sampled during acute, relapse/remission and chronic phases and results were analysed by two-way ANOVA.

RESULTS

1. A strong gender-dependent difference in myelin (MBP) and myelin precursor (PDGFαR) marker mRNA expression levels is observed in control animals in the spinal cord, but not in the cerebellum. This is the only gender-dependent difference in the expression level of the indicated markers in healthy animals; 2. both PDGFαR and MBP mRNAs in the spinal cord and MBP in the cerebellum are down-regulated during EAE in gender-dependent manner; 3. in the cerebellum, the expression profile of neuron-associated markers (GAD65, GAD67) is characterized by a substantial down-regulation during the inflammatory phase of the disease, which does not differ between male and female rats (two-way ANOVA); 4. there is an up-regulation of NGF, trkA and p75 mRNA expression in the early phases of the disease (14 and 21 days post-immunization), which is not different between male and female.

CONCLUSIONS

It is reported herein that the regulation of markers involved in demyelination and neuroprotection processes occurring during EAE, a well-established MS animal model, is gender- and time-dependent. These findings might contribute to gender- and phase disease-based therapy strategies.

Reproducibility of serum cytokines and growth factors

BACKGROUND

In most studies, circulating biomarkers are usually assessed from a single sample, assuming that this single measurement represents the long-term biomarker status of the individual. Such an assumption is rarely tested although it may not be valid for all biomarkers. The objective of this study was to investigate the temporal reproducibility of a panel of cytokines and growth factors.

METHODS

Thirty-five postmenopausal women with two annual visits and 30 premenopausal women with three annual visits were randomly selected from the participants in an existing prospective cohort. A total of 23 serum cytokines, nine growth factors and C-reactive protein (CRP) were measured using the Luminex xMap technology. In addition, for eight biomarkers, regular and high sensitivity (hs) assays were compared.

RESULTS

The biomarkers with adequate (>60%) detection rates and acceptable (> or =0.55) intra-class correlation coefficients (ICCs) were: hsIL-1beta, IL-1RA, hsIL-2, hsIL-4, hsIL-5, hsIL-6, hsIL-10, IL-12p40, hsIL-12p70, hsTNF-alpha, TNF-R1, TNF-R2, CRP, HGF, NGF, and EGFR. The remaining biomarkers either had low temporal reproducibility or were undetectable in more than 40% of samples.

CONCLUSIONS

The results suggest that 16 of the 41 biomarkers measured with Luminex technology showed sufficient sensitivity and temporal reproducibility in sera.

Increased levels of nerve growth factor in the airways of patients with sarcoidosis

OBJECTIVES

Nerve growth factor (NGF) is a potent neuronal growth factor with inflammatory properties that recently has been proposed to be of importance in airway pathology. A role for NGF in the inflammatory granulomatous lung disease sarcoidosis is not well elucidated. The aims of this study were to investigate the secreted levels of NGF in bronchoalveolar lavage fluid (BALF) from sarcoidosis patients compared with patients with resolved disease, patients with another granulomatous disease--chronic beryllium disease (CBD)--and healthy subjects and also to investigate the relationship between NGF levels and markers of inflammation.

METHODS AND RESULTS

NGF levels in BALF from 56 patients with active sarcoidosis (22 with Löfgren's syndrome), nine subjects with resolved sarcoidosis, six patients with CBD, and 31 healthy subjects were compared. A 10-fold elevation of NGF levels was found in patients with active sarcoidosis compared with subjects with clinically resolved sarcoidosis, patients with CBD and healthy subjects. In sarcoidosis patients, positive correlations between concentrations of NGF and lymphocytes, eosinophils and interferon-gamma, interleukin (IL)-4, IL-10, IL-12 were found.

CONCLUSIONS

We demonstrate that secreted levels of NGF are markedly enhanced in the airways in active pulmonary sarcoidosis. Furthermore, a relationship between NGF and pulmonary inflammation in sarcoidosis is supported.

NGF plasma levels increase due to alcohol intoxication and decrease during withdrawal

Recent studies show that alcohol dependence is associated with alterations in plasma levels of nerve growth factor (NGF). The aim of this study was to further elucidate reported alterations in NGF plasma levels during alcohol intoxication and withdrawal. Therefore, we assessed NGF plasma levels by enzyme-linked immunosorbent assay (ELISA) on admission (day 0) and day 7 of alcohol withdrawal in male alcohol dependent patients (n=75) in comparison to healthy controls (n=44). We found significant higher (U=1005.0, p<0.001) NGF plasma levels in the alcohol-dependent patients. Subgroup analysis showed significant higher (U=-2.934, p=0.003) NGF plasma levels in patients suffering from acute alcohol intoxication (group A) than in early abstinent patients (group B). From day 0 to day 7 of alcohol withdrawal NGF plasma levels decreased significantly in both groups (group A: Z=-3.118, p=0.002, group B: Z=-2.103, p=0.035). Our results suggest that acute alcohol intoxication is associated with an increase in NGF plasma levels, which decrease during alcohol withdrawal. These results suggest that NGF plasma levels increase as part of a regulation mechanism that counteracts alcohol intoxication.

Serum neurotrophins—A study on the time course and influencing factors in a large old age sample

The neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are important mediators of brain and neuronal development, the maintenance of homeostatic conditions in the adult nervous system, and the complex interplay of central and peripheral physiological and pathophysiological factors. To date there are few studies examining blood concentrations of neurotrophic factors in large samples of healthy and diseased individuals and no published study specifically addresses peripheral BDNF and NGF levels in late life. Using improved highly sensitive and specific fluorometric two-site enzyme-linked immunosorbent assays we examined BDNF (n=465) and NGF (n=175) serum levels in a large cohort of elderly individuals (age range: 70-103 years). Neither BDNF nor NGF serum levels proved to be normally distributed, indicating that previously published studies with small sample sizes using parametric testing may be misleading. A significant correlation was found between BDNF and platelet count (r=0.344, p<0.01), age and BDNF protein (r=-0.101, p=0.029) and BDNF and NGF serum levels (r=0.152, p=0.04). No other major influencing factors were found including gender, depression, and dementia.

Clinical relevance of nerve growth factor serum levels in patients with atopic dermatitis and psoriasis

BACKGROUND

Nerve growth factor (NGF) is known to act as a potent mediator in neuroinflammatory processes. Recent studies point to a role of NGF in the skin pathophysiology of atopic dermatitis (AD) and psoriasis. Hereby, NGF was found to interact with the major cellular components (mast cells and eosinophils) of both skin diseases.

OBJECTIVES

In order to investigate NGF serum levels as a possible clinical marker of disease activity and immunological status, we determined serum NGF, eosinophil cationic protein (ECP), total IgE and score of AD (SCORAD) in 57 patients with AD as well as NGF and the psoriasis area and severity index (PASI) in 17 patients with psoriasis. Fifty healthy subjects served as controls.

METHODS

We used a highly sensitive improved fluorometric two-site ELISA system for serum NGF detection. IgE and ECP were measured by CAP-FEIA and radioimmunoassay.

RESULTS

We did not find a significant correlation between NGF and either ECP, total IgE, or severity of disease assessed by SCORAD. Also in patients with psoriasis, there was no significant correlation with disease activity determined by PASI.

CONCLUSION

Even though there is increasing evidence showing NGF to be involved in the local inflammatory pathophysiology of AD within skin lesions, our findings suggest that NGF systemic serum concentration is not a suitable parameter to estimate the clinical or immunological status of AD or psoriasis patients. This result is inconsistent with some previous studies showing a positive correlation of serum NGF with AD severity, which might be, for example, due to the fact that the present results are corrected for unspecific binding.

Maternal nerve growth factor serum levels in the perinatal period

Neurotrophins, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), are potent modulators of neuronal and immune function, and have been implicated recently in diseases associated with pregnancy. In contrast to serum BDNF, which is reportedly suppressed in the perinatal period, regulation of NGF in the perinatal period is unknown. In this study, serum NGF concentrations were measured in 40 pregnant (follow-up: 30th and 37th week of gestation, 1 week and 8 weeks after childbirth) and 40 non-pregnant women. Maternal NGF serum levels did not differ significantly from controls (median: 7.6 pg NGF/ml serum) neither before nor after childbirth, although there was a trend towards increased NGF concentrations at the 37th week of gestation (median: 12.5 pg NGF/ml serum) and 1 week after childbirth (median: 11.6 pg NGF/ml serum). There was no association of maternal NGF with 17beta-estradiol, progesterone, dehydroepiandrosterone sulfate (DHEAS) and cortisol concentrations in maternal serum, or maternal depression, as measured by the Edinburgh Postnatal Depression Scale (EPDS). In the non-pregnant control group, NGF serum concentrations were negatively correlated with the number of days since the first day of the menstrual cycle (r=-0.32, p<0.05). In conclusion, NGF is not altered during normal pregnancy on a systemic level. In addition, NGF displays a different regulation compared with BDNF during the menstrual cycle.

Nerve growth factor in serum is a marker of the stage of alcohol disease

Long-term alcohol abuse has deleterious effects on the peripheral and central nervous system. Nerve growth factor (NGF) is a pleiotropic neurotrophic protein involved in development, maintenance of function and regeneration of nerve cells. We examined patients in different stages of alcohol disease and measured their NGF serum concentrations based on the hypothesis that these reflect the state of disease. We examined 57 patients suffering from alcohol-dependence for more than 2 years (DSM IV) on day 8 of a qualified withdrawal, 18 patients with Korsakoff's syndrome and 40 healthy controls. In addition to clinical examination, careful history taking and a standard neuropsychological test battery, serum NGF concentrations were measured by a highly sensitive enzyme-immunoassay. Of the 57 patients 9 had suffered from severe withdrawal delirium in the past, other clinical parameters were alike. Cognitive test performance did not differ from the control group. Mean NGF levels of controls amounted to 42.1pg/ml (S.D. 68.0); mean levels of patients with alcohol dependence were raised significantly to 401.5pg/ml (S.D. 932.6) without delirium in the past and even further to 3292.5pg/ml (S.D. 4879.6) with former withdrawal delirium. By contrast, patients with persistent amnestic disorder (Korsakoff's syndrome) showed values identical to the controls. NGF serum levels were significantly elevated in alcohol-dependent patients, more so in those with prior delirium. Their cognitive tests being normal, this possibly reflects the activity of NGF as an endogenous repair mechanism for damaged neurons. In accordance with this hypothesis, NGF values are "normal" in patients with persistent alcohol-related cognitive decline.

Nerve growth factor concentration in human saliva

OBJECTIVE

The aims of this study were to measure the normal concentration of nerve growth factor (NGF) in healthy human saliva and to investigate the effects of age and gender differences on saliva NGF level.

MATERIALS AND METHODS

Resting whole, stimulated parotid, and stimulated submandibular/sublingual saliva were collected from 127 healthy volunteers with ages ranging from 20 to 81 years. The saliva NGF concentration was measured by enzyme immunoassay.

RESULTS AND CONCLUSIONS

The mean concentrations of NGF were 901.4 +/- 75.6 pg ml(-1) in resting whole saliva, 885.9 +/- 79.9 pg ml(-1) in stimulated parotid saliva, and 1066.1 +/- 88.1 pg ml(-1) in stimulated submandibular/sublingual saliva. The stimulated submandibular saliva showed lower NGF concentrations with increasing age (rho = -0.296, P = 0.001). The NGF concentrations of resting whole saliva (P = 0.025) and stimulated parotid saliva (P = 0.005) were significantly higher in women than men. The NGF concentration of stimulated submandibular saliva was significantly higher than stimulated parotid saliva (P = 0.005) and significantly correlated with stimulated parotid saliva NGF level (rho = -0.244, P = 0.008). We found measurable concentrations of NGF in all three sources of saliva; the concentration was affected by the source for the stimulated parotid and submandibular saliva, age for stimulated submandibular saliva, and gender difference for resting whole saliva and stimulated parotid saliva.

Nerve growth factor serum concentrations rise after successful cognitive-behavioural therapy of generalized anxiety disorder

Generalized anxiety disorder (GAD) is a chronic stress disease with permanent physical tension and cognitive strain. Raised nerve growth factor (NGF) serum levels were reported as an acute stress reaction in soldiers before their first parachute jump even before the rise in cortisol. Taking GAD as a clinical model of chronic stress, we measured NGF in the serum of 22 patients with GAD before and after cognitive-behavioural therapy (CBT) and compared them to those of healthy normal controls. Treatment response was tested by the values of the State and Trait of Anxiety Inventory (STAI) and the Hamilton Anxiety Scale (HAM-A) as treatment outcome variables. The NGF values of patients and controls were similar at baseline (p=0.8941); however, with successful treatment, corresponding to a mean reduction in the HAM-A by more than 50% and a reduction in the clinical global impression scale (CGI) median from 4 to 1, the patients' NGF serum concentrations rose significantly (p=0.0006) which might correspond to an altered stress reaction, possibly contributing to good therapeutic response with CBT. There were 3 patients with a HAM-A decrease of less than 15%. In those patients NGF rose only marginally. Hence, the increase in serum NGF seems to indicate good treatment response.

Adequate antipsychotic treatment normalizes serum nerve growth factor concentrations in schizophrenia with and without cannabis or additional substance abuse

Neurotrophins such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are important for the development and maintenance of neuron function. Neurodevelopment is thought to be impaired in schizophrenia, and vulnerable schizophrenic brains may be more sensitive to toxic influences. Thus, cannabis as a neurotoxin (and other substances) may be more harmful to schizophrenic brains than to non-schizophrenic brains, when used chronically. In a previous study we demonstrated an earlier disease onset and significantly higher serum NGF concentrations in drug-naïve schizophrenic patients with previous long-term cannabis abuse than in schizophrenics without cannabis abuse or cannabis abusers without schizophrenia. We therefore investigated whether this difference is still observed after treatment. Serum NGF measured in 114 treated schizophrenic patients (schizophrenia alone, n=66; schizophrenia plus cannabis abuse, n=42; schizophrenia plus multiple substance abuse, n=6) no longer differed significantly among those groups and from the control groups (healthy controls, n=51; cannabis controls, n=24; multiple substance controls, n=6). These results were confirmed by an additional prospective study in 28 patients suffering from schizophrenia (S) or schizophrenia with cannabis abuse (SC). Previously elevated serum NGF levels in the drug-naïve state, also differing between the groups (S: 83.44+/-265.25 pg/ml; SC: 246.89+/-310.24 pg/ml, S versus SC: p=0.03) dropped to 10.72+/-14.13 pg/ml (S) and 34.19+/-38.96 pg/ml (SC) (S versus SC, p>0.05), respectively, after adequate antipsychotic treatment. We thus conclude that antipsychotic treatment leads to recovery of neural integrity, as indicated by renormalized NGF values.

Raised plasma nerve growth factor levels associated with early-stage romantic love

Our current knowledge of the neurobiology of romantic love remains scanty. In view of the complexity of a sentiment like love, it would not be surprising that a diversity of biochemical mechanisms could be involved in the mood changes of the initial stage of a romance. In the present study, we have examined whether the early romantic phase of a loving relationship could be associated with alterations in circulating levels of neurotrophins (NTs). Plasma levels of NGF, BDNF, NT-3 and NT-4 were measured in a total of 58 subjects who had recently fallen in love and compared with those of two control groups, consisting of subjects who were either single or were already engaged in a long-lasting relationship. NGF level was significantly higher (p < 0.001) in the subjects in love [mean (SEM): 227 (14) pg/ml] than in either the subjects with a long-lasting relationship [123 (10) pg/ml] or the subjects with no relationship [149 (12) pg/ml]. Notably, there was also a significant positive correlation between levels of NGF and the intensity of romantic love as assessed with the passionate love scale (r = 0.34; p = 0.007). No differences in the concentrations of other NTs were detected. In 39 subjects in love who-after 12-24 months-maintained the same relationship but were no longer in the same mental state to which they had referred during the initial evaluation, plasma NGF levels decreased and became indistinguishable from those of the control groups. Taken together, these findings suggest that some behavioural and/or psychological features associated with falling in love could be related to raised NGF levels in the bloodstream.

Impact of Levodopa on Reduced Nerve Growth Factor Levels in Patients With Parkinson Disease

The author s found 6.5-fold reduced nerve growth factor (NGF) levels in the plasma of treated patients with Parkinson disease (PD) compared with healthy control subjects (P = 0.03). A significant positive correlation between levodopa and NGF plasma levels appeared after acute levodopa/benserazide administration. The data suggest that acute levodopa administration may contribute to an increase of NGF plasma concentrations, which are reduced in treated PD patients due to the ongoing disease process itself or chronic antiparkinsonian drug treatment.

Role of nerve growth factor and FSH receptor in epithelial ovarian cancer

The neurotrophins (NT) including nerve growth factor (NGF) are a family of related growth factors that are of major importance in the regulation of neuronal survival and differentiation. In the ovary, they can help in follicular maturation and ovulation by inducing the FSH receptor (FSHR). Current literature shows that perimenopausal ovarian surface epithelium (OSE) can also express FSHR. By G protein link, this FSHR is capable of precipitating neoplasia of OSE, which is the commonest in the ovary. NT are implicated as the cause of this aberrant expression of FSHR in OSE. By central action NT can lower serum FSH, as is found in ovarian cancer. Thus, NGF deregulates expression of FSHR in OSE and secretion of FSH from the pituitary. This phenomenon may hold the key to the hitherto unexplained carcinogenic process of sporadic epithelial ovarian cancer.

Impact of aerobic training on immune-endocrine parameters, neurotrophic factors, quality of life and coordinative function in multiple sclerosis

In recent years it has become clear that multiple sclerosis (MS) patients benefit from physical exercise as performed in aerobic training but little is known about the effect on functional domains and physiological factors mediating these effects. We studied immunological, endocrine and neurotrophic factors as well as coordinative function and quality of life during an 8-week aerobic bicycle training in a waitlist control design. In the immune-endocrine study (1) 28 patients were included, the coordinative extension study (2) included 39 patients. Training was performed at 60% VO(2)max after determining individual exertion levels through step-by-step ergometry. Metabolic (lactate), endocrine (cortisol, adrendocortico-releasing hormone, epinephrine, norepinephrine), immune (IL-6, soluble IL-6 receptor), and neurotrophic (brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF)) parameters were compared from a prestudy and a poststudy endurance test at 60% VO(2)max for 30 min. In study (1), lowered lactate levels despite higher workload levels indicated a training effect. Disease-specific quality of life (as measured by the Hamburg Quality of Life Questionnaire for Multiple Sclerosis, HAQUAMS) significantly increased in the training group. No significant training effects were seen for endocrine and immune parameters or neurotrophins. In study (2), two out of three coordinative parameters of the lower extremities were significantly improved. In summary, low-level aerobic training in MS improves not only quality of life but also coordinative function and physical fitness.

Measurement of nerve growth factor serum concentration in a psychologically stressful situation in men

Psychologically stressful events have been reported to elevate nerve growth factor (NGF) serum concentrations. NGF and cortisol serum concentrations were measured in 20 healthy male volunteers before (3 p.m.) and after (5 p.m.) an academic oral presentation and on a control day. Cortisol showed a significant overall change (p=0.001), i.e. cortisol serum concentrations were increased on the lecture day at 3 p.m. (p=0.007; 155%) and at 5 p.m. (p=0.001; 175%) as compared with the control day. In contrast to cortisol no significant differences among the four serum NGF measurements was detected (Chi-quadrat 2.94, df=3, p=0.401), i.e. the NGF serum concentrations remained unchanged on the lecture day at 3 p.m. (p=0.279) and at 5 p.m. (p=0.627) as compared with the control day. We conclude that NGF serum levels do not change during acute stress, at least after this type of stressor.